factors affecting disinfection by-product formation during

American Water Works Association

RESEARCH FOUNDATION

Factors AffectingDisinfectionBy-ProductFormation DuringChloramination

Subject Area: Water Treatment

Factors Affecting Disinfection By-Product Formation During Chloramination

The mission of the A WWA Research Foundation is to advance the science of water to improve the quality of life. Funded primarily through annual subscription payments from over 900 utilities, consulting firms, and manufacturers in North America and abroad, A WWARF sponsors research on all aspects of drinking water, including supply and resources, treatment, monitoring and analysis, distribution, management, and health effects.

From its headquarters in Denver, Colorado, the AWWARF staff directs and supports the efforts of over 500 volunteers, who are the heart of the research program. These volunteers, serving on various boards and committees, use their expertise to select and monitor research studies to benefit the entire drinking water community.

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Factors Affecting Disinfection By-Product Formation During ChloraminationPrepared by:James M. Symons and Rebecca XiaDepartment of Civil and Environmental Engineering, University of Houston, Houston, Texas 77204-4791

Gerald E. Speitel Jr. and Alicia C. DiehlDepartment of Civil Engineering,University of Texas at Austin, Austin, Texas 78712

Cordelia J. Hwang, Stuart W. Krasner, and Sylvia E. BarrettMetropolitan Water District of Southern California, Water Quality Laboratory, 700 Moreno Avenue, La Verne, California 91750-3399

Sponsored by:AWWA Research Foundation6666 West Quincy Avenue Denver, Colorado 80235-3098

Published by theAWWA Research Foundation andAmerican Water Works Association

Disclaimer

This study was funded by the AWWA Research Foundation (AWWARF).AWWARF assumes no responsibility for the content of the research study

reported in this publication or for the opinions or statements of fact expressed in thereport. The mention of trade names for commercial products does not represent or imply

the approval or endorsement of AWWARF. This report is presented solely for informational purposes.

Library of Congress Cataloging-in-Publication Data Factors affecting disinfection by-product formation during

chloramination / prepared by James M. Symons ... [et al.]. xxxii,330p. 21.5*28cm.

"Sponsored by American Water Works Association ResearchFoundation."Includes bibliographical references.ISBNO-89867-906-0(alk. paper)1. Water-Purification-Disinfection~By-products. 2. Drinking

water-Purification United States. 3. Water-Purification- Chloramination. 4. Chloramines. 5. Water chemistry. I. Symons, James M. II. AWWA Research Foundation. TD459.F33 1997628.1'662-dc21 97-17672

OP

Copyright 1998by

AWWA Research Foundationand

American Water Works Association Printed in the U.S.A.

ISBNO-89867-906-0 Printed on recycled paper.

CONTENTS

LIST OF TABLES..................................................................................................................... xi

LIST OF FIGURES.................................................................................................................. xv

FOREWORD............................................................................................................................ xxi

ACKNOWLEDGMENTS........................................................................................................ xxiii

EXECUTIVE SUMMARY...................................................................................................... xxv

CHAPTER 1: GENERAL PURPOSE OF STUDY.................................................................. 1

CHAPTER 2: LITERATURE REVIEW.................................................................................... 3

Disinfection By-Product Formation ............................................................................... 3

Chloramine/Bromamine Chemistry................................................................................ 5

Recovery of DOX in Measurable DBPs......................................................................... 12

Identification of New DBPs............................................................................................ 13

CHAPTER 3: GENERAL SCOPE OF PROJECT..................................................................... 15

CHAPTER 4: ANALYTIC METHODS AND QUALITY

ASSURANCE/QUALITY CONTROL.......................................................................... 17

Simulated Distribution System Treatment...................................................................... 17

Methodology....................................................................................................... 17

Quality Control/Quality Assurance.................................................................... 18

Formation Potential........................................................................................................ 18

Methodology....................................................................................................... 18

Quality Control/Quality Assurance .................................................................... 19

Preformed Chloramines.................................................................................................. 19

Methodology.................................................................-.-. ............................... 19


Chorine Dosing Solution................................................................................................ 20

Methodology....................................................................................................... 20

Quality Control/Quality Assurance .................................................................... 20

Chlorine Dose................................................................................................................. 21

Methodology....................................................................................................... 21


Residual Concentrations................................................................................................. 21

Methodology....................................................................................................... 21

Quality Control/Quality Assurance.......................................................................23

Disinfection By-Product Sample Treatment................................................................... 23

Methodology....................................................................................................... 23

Quality Control/Quality Assurance .......................................................................24

Disinfection By-Product Analysis.................................................................................. 24

Overview............................................................................................................. 24

Trihalomethanes................................................................................................. 25

Haloacetic Acids................................................................................................. 26

Dissolved Organic Halogen................................................................................ 28

Cyanogen Halide (CNX).................................................................................... 31

Bromide Ion........................................................................................................ 35

Other Analytical Methods................................................................................... 36

CHAPTER 5: CONTROLLED BATCH STUDIES WITH PREFORMED

CHLORAMINES TASK la........................................................................................ 37

Objectives....................................................................................................................... 37

Experimental Approach.................................................................................................. 37

Source Water Quality...................................................................................................... 39

Influence of Total Residual................................................................................ 39

Influence of pH, Cfe/N Mass Ratio, Bromide Ion.......................................................... 50

Residual Species Monochloramine/Dichloramine .......................................... 50

Total Trihalomethanes and Dissolved Organic Halogen.................................... 54

Haloacetic Acids and Cyanogen Halides............................................................ 65

VI

Recovery of Dissolved Organic Halogen With 12 Measured

Disinfection By-Products........................................................................ 71

CHAPTER 6: CONTROLLED BENCH-SCALE MIXING

STUDIES TASK Ib.................................................................................................... 77

Objectives....................................................................................................................... 77

Experimental Approach.................................................................................................. 77

Influence of Mixing........................................................................................................ 81

Residual Species Monochloramine/Dichloramine .......................................... 81

Total Trihalomethanes and Dissolved Organic Halogen.................................... 84

Haloacetic Acids................................................................................................. 92

CyanogenHalides............................................................................................... 97

Implications for Mixing at Larger Scale............................................................. 101

Recovery of Dissolved Organic Halogen With 12 Measured

Disinfection By-Products................................................................................... 102

CHAPTER 7: PILOT PLANT STUDIES TASK 2............................................................... 109

Objectives...................................................................................................................... 109

Experimental Approach................................................................................................. 109

Description of Pilot Plants................................................................................ 109

Lake Austin Water............................................................................................ 114

Lake Houston Water.......................................................................................... 115

California State Project Water........................................................................... 116

Results............................................................................................................................ 118

Lake Austin Water............................................................................................. 119

Lake Houston Water.......................................................................................... 123

California State Project Water........................................................................... 130

Discussion...................................................................................................................... 135

Trihalomethanes................................................................................................ 135

Haloacetic Acids................................................................................................ 136

Cyanogen Halides.............................................................................................. 139

Vll

Dissolved Organic Halogen............................................................................... 140

Point of Chloramine Application....................................................................... 141

Conclusions.................................................................................................................... 142

CHAPTER 8: GEOGRAPHICALLY DIVERSE WATERS TASK 3................................... 143

Objective........................................................................................................................ 143


Source Waters Studied....................................................................................... 143

Bench-Scale Studies.......................................................................................... 144

Full-Scale Studies/Historical Data..................................................................... 144

Results............................................................................................................................ 146

Midsouth Water................................................................................................. 146

Mississippi River Water.................................................................................... 156

Biscayne Aquifer............................................................................................... 164

Northeastern Creek Water................................................................................. 176

Pacific Northwest Lake Water........................................................................... 183

CHAPTER 9: ANALYTICAL APPROACHES TO DETERMINE "NEW"

CHLORAMINE DBFs TASK 4................................................................................. 193

Objectives...................................................................................................................... 193


LC Techniques for Polar DBPs..................................................................................... 194

Overview............................................................................................................ 194

Experimental...................................................................................................... 195

Results and Discussion...................................................................................... 205

Conclusions........................................................................................................ 218

Analysis of DBPs by SDE GC-MS ............................................................................... 219

Overview..................................................................................^......................... 219

Analytical Methods............................................................................................ 220

Samples Evaluated............................................................................................. 224

Vlll


Conclusions........................................................................................................ 233

UF Determination of AMW Distributions..................................................................... 233

Overview............................................................................................................ 233

Analytical Methods............................................................................................ 234

Experimental Plan.............................................................................................. 236

Method Development........................................................................................ 241


Conclusions........................................................................................................ 254

Summary and Conclusions............................................................................................ 256

CHAPTER 10: CONCLUSIONS.............................................................................................. 257

Task la........................................................................................................................... 257

Task Ib........................................................................................................................... 259

Task 2............................................................................................................................. 260

Task 3............................................................................................................................. 262

Task 4............................................................................................................................. 264

CHAPTER 11: RECOMMENDATIONS TO WATER UTILITIES........................................ 267

APPENDIX A: ULTRAFILTRATION CALCULATIONS AND DATA............................... 271

APPENDIX B: DATA FROM INDIVIDUAL TASK 2 PILOT PLANT TESTS ......................281

REFERENCES............................................................................................................................309

LISTOFABBREVIATIONS......................................................................................................325

IX

TABLES

4.1 Recoveries of individual DBFs in the DOX analysis..................................................... 30

4.2 Results from replicates of the same City of Houston tap water sample......................... 31

4.3 Variation in DOX determination with time.................................................................... 32

4.4 CNX analytical standards............................................................................................... 33

5.1 Parameter values for matrix of experimental conditions................................................ 38

5.2 Quality of Lake Austin water collected on 9/17/93........................................................ 40

5.3 Quality of Lake Houston water collected on 10/28/93................................................... 41

5.4 Quality of Lake Houston water collected on 2/22/94..................................................... 42

5.5 Quality of California State Project water collected on 12/9/93...................................... 43

6.1 Chemistry conditions for batch mixing experiments...................................................... 80

6.2 Lake Austin water haloacetic acid concentrations for bench

mixing studies..................................................................................................... 96

6.3 Lake Houston water haloacetic acid concentrations for bench

mixing studies..................................................................................................... 98

6.4 California State Project water haloacetic acid concentrations for

bench mixing studies.......................................................................................... 99

6.5 CNX concentrations for bench mixing studies............................................................... 100

7.1 Summary of Lake Austin water pilot plant results (average values).............................. 120

7.2 Comparison of Task 2 and Tasks la and Ib with data for Lake

Austin water........................................................................................................ 123

7.3 Summary of Lake Houston water pilot plant results (average values)........................... 124

7.4 Comparison of Task 2 data with Tasks la and Ib data for Lake Houston water........... 129

7.5 Summary of California State Project water pilot plant

results (average values)....................................................................................... 131

7.6 Comparison of Task 2 with Tasks 1 a and 1 b data for

California State Project water............................................................................. 136

7.7 Summary of pilot plant data for all three waters tested.................................................. 137

7.8 Comparison of prechloramination and postchloramination ........................................... 141

8.1 Chloramination parameters for bench-scale studies of Task 3 waters ........................... 145

XI

8.2 Influence of water quality parameters on DBF formation in midsouth

water................................................................................................................... 148

8.3 Historical (1993/94) DBF data for midsouth utility....................................................... 153

8.4 Historical (1988/89) DBF data for midsouth utility....................................................... 154

8.5 Influence of water quality parameters on DBF formation in

Mississippi River water...................................................................................... 158

8.6 Historical DBF data for utility treating Mississippi River water.................................... 163


Biscayne Aquifer................................................................................................ 166

8.8 Historical (1994/95) DBF data for utility treating Biscayne

Aquifer water...................................................................................................... 170

8.9 Historical (1988/89) DBF data for utility treating colored

groundwater........................................................................................................ 172


northeastern creek water..................................................................................... 178

8.11 Historical DBF data for northeastern utility treating creek water.................................. 181


Pacific Northwest lake water.............................................................................. 185

8.13 Historical (1991) DBF data for Pacific Northwest utility............................................... 188

8.14 Historical (1994/95) DBF data for Pacific Northwest utility......................................... 190

9.1 Chlorinated model amines, amino acids, and peptides with

LC retention times.............................................................................................. 197

9.2 Comparison of conventional, microbore, and capillary LC ........................................... 200

9.3 Retention times for chlorination and chloramination by-products

of model peptides................................................................................................ 212

9.4 Electrospray mass spectrum interpretation for a reaction product

of chlorine with glycylalanine (monochlorinated product)................................ 217

9.5 Electrospray mass spectrum interpretation for a reaction product

of chlorine with glycylalanine (dichlorinated product)...................................... 217

9.6 Samples for SDE analysis............................................................................................... 225

9.7 Results of SDE GC-MS analyses for DBFs................................................................... 227

xn

9.8 Effect of bromide (and iodide) on THM speciation....................................................... 231

9.9 List of UF experiments................................................................................................... 237

9.10 Summary of coefficients of permeation......................................................................... 243

9.11 Refiltration experiment LHW...................................................................................... 244

9.12 Summary of DOC, SUVA, DOX, and DOX percentage values for bench-,

pilot-, and full-scale tests.................................................................................... 246

10.1 Summary of 2-d SDS disinfection by-product data........................................................ 263

A.I Example of UF calculations............................................................................................ 273

A.2 UF comparison of chloramination and chlorination CSPW........................................ 274

A.3 Comparison of chloramine treatment conditions LHW............................................... 275

A.4 UF data for LHW pilot plant (enhanced coagulation).................................................... 276

A.5 UF data for CSPW full-scale plant................................................................................. 277

A.6 UF data for midsouth water............................................................................................ 278

A.7 UF data for Pacific Northwest water.............................................................................. 279

B.I Lake Austin water pilot plant test run 1 A.................................................................... 282

B.2 Lake Austin water pilot plant test run IB.................................................................... 283

B.3 Lake Austin water pilot plant test run 2A.................................................................... 284

B.4 Lake Austin water pilot plant test run2B.................................................................... 285

B.5 Lake Austin water pilot plant test run 3....................................................................... 286

B.6 Lake Austin water pilot plant test run 4....................................................................... 287

B.7 Lake Austin water pilot plant test run 5A.................................................................... 288

B.8 Lake Austin water pilot plant test runSB.................................................................... 289

B.9 Lake Houston water pilot plant test run 1.................................................................... 290

B.10 Lake Houston water pilot plant test run 2.................................................................... 291

B.ll Lake Houston water pilot plant test run3A................................................................. 292

B.12 Lake Houston water pilot plant test run 3B................................................................. 293

B.13 Lake Houston water pilot plant test run 4A................................................................. 294

B.14 Lake Houston water pilot plant test run4B................................................................. 295

B.15 Lake Houston water pilot plant test run 5A................................................................. 296

B.16 Lake Houston water pilot plant test run 5B................................................................. 297

B.I7 California State Project water pilot plant test run 1..................................................... 298

xin

B.I8 California State Project water pilot plant test run 1 (repeat)....................................... 299

B.19 California State Project water pilot plant test run 2..................................................... 300

B.20 California State Project water pilot plant test run 3A.................................................. 301

B.21 California State Project water pilot plant test run 3B.................................................. 302

B.22 California State Project water pilot plant test run 4A.................................................. 303

B.23 California State Project water pilot plant test run 4A (repeat).................................... 304

B.24 California State Project water pilot plant test run 4B.................................................. 305

B.25 California State Project water pilot plant test run 4B (repeat)..................................... 306

B.26 California State Project water pilot plant test run 5..................................................... 307

xiv

FIGURES

2.1 Chloramine dose-residual curve for California State Project water................................. 6

2.2 Principal species of bromine and bromamines predominating after 1 to 2

minutes at various pH and ammonia:nitrogen ratios............................................ 9

5.1 Lake Houston water chemistry experiments: 2-d TTHM formation

at a C12 to N ratio of 3 to 1................................................................................... 44

5.2 Lake Houston water chemistry experiments: 2-d DOX formation

at a Cl2 to N ratio of 3 to 1................................................................................... 45




at a Cl2 to N ratio of 5 to 1................................................................................... 47





5.7 Lake Austin water, batch studies, dichloramine residuals as a percentage

of total residual as a function of C12/N ratio and pH at a total

residual chlorine of 2 mg/L.................................................................................. 51

5.8 Lake Houston water, batch studies, dichloramine residuals as a percentage

of total residual as a function of C12/N ratio and pH at a total

residual chlorine of 2 mg/L.................................................................................. 52

5.9 California State Project water, batch studies, dichloramine residuals as a

percentage of total residual as a function of C12/N ratio and pH

at a total residual chlorine of 2 mg/L................................................................... 53

5.10 Lake Austin water, batch studies, TTHM (ug/L) as a function of C12/N

ratio and pH at a nominal total residual chlorine of 2 mg/L................................ 55

5.11 Degree of bromination of THMs in Lake Austin water .................................................. 56

5.12 Lake Austin water, batch studies, DOX (ug C17L) as a function of C12/N


xv

5.13 Lake Houston water, batch studies, TTHM (ug/L) as a function of C12/N


5.14 Degree of bromination of THMs in Lake Houston water................................................ 61

5.15 Lake Houston water, batch studies, DOX (|ig C17L) as a function of C12/N


5.16 California State Project water, batch studies, TTHM (ug/L) as a function

of C12/N ratio and pH at a nominal total residual chlorine of 2 mg/L................. 63

5.17 California State Project water, batch studies, DOX (ug C17L) as a function

of C12/N ratio and pH at a nominal total residual chlorine of 2 mg/L................. 64

5.18 Degree of bromination of THMs in California State Project water................................. 65

5.19 Lake Austin water, batch studies, HAA6 (|J.g/L) and CNX (ug/L) as

a function of C12/N ratio and pH at a nominal total residual

chlorine of 2 mg/L............................................................................................... 66

5.20 Lake Houston water, batch studies, HAA6 (|J.g/L) as a function of

C12/N ratio and pH at a nominal total residual chlorine of 2 mg/L...................... 68

5.21 Lake Houston water, batch studies, CNX (|ig/L) as a function of

C12/N ratio and pH at a nominal total residual chlorine of 2 mg/L...................... 69

5.22 California State Project water, batch studies, HAA6 (ug/L) as a function of

C12/N ratio and pH at a total residual chlorine of 2 mg/L.................................... 70

5.23 California State Project water, batch studies, CNX (ug/L) as a function of

C12/N ratio and pH at a total residual chlorine of 2 mg/L.................................... 72

5.24 Lake Austin water chemistry experiments: Micromolar percentage of 2-d DOX

identified by summing the 12 measured 2-d DBFs at different

pHs and C12/N ratios............................................................................................ 73

5.25 Lake Houston water chemistry experiments: Micromolar percentage of 2-d DOX

identified by summing the 12 measured 2-d DBPs at different

pHs and C12/N ratios............................................................................................ 74

5.26 California State Project water chemistry experiments: Micromolar percentage of

2-d DOX identified by summing the 12 measured 2-d DBPs at

different pHs and C12/N ratios............................................................................. 75

xvi

6.1 Side view of baffled beaker and pouring apparatus, plan view of

baffled beaker, and plan view of jar test apparatus,

with pouring apparatus ........................................................................................ 79

6.2 Lake Austin water dichloramine fraction at pH 6, 7/1 C12/N ratio.................................. 82

6.3 Lake Houston water dichloramine fraction at pH 6, 3/1 C12/N ratio............................... 83

6.4 California State Project water dichloramine fraction at pH 6, 3/1 C12/N ratio................ 83

6.5 Impact of mixing on 2-d DBF formation in Lake Austin water at pH

about 6 and C12/N ratio of 7 to 1, ambient bromide (0.24 mg/L)........................ 85




about 10 and C12/N ratio of 5 to 1, ambient bromide (0.24 mg/L)...................... 86





6.10 Impact of mixing on 2-d DBF formation in Lake Houston water at pH

about 6 and C12/N ratio of 3 to 1, 0.5 mg/L bromide added................................ 89









6.15 Impact of mixing on 2-d DBF formation in California State Project water at pH

about 6 and C12/N ratio of 3 to 1, 0.5 mg/L bromide added................................ 93



xvn







6.20 Influence of mixing conditions on the percentage of DOX identified

by summing the 12 measured DBFs (S 12 DBPOX) in Lake Austin

water: pH about 6, C12/N ratio 7 to 1, 2 mg/L nominal total

residual after 2-d, ambient bromide (0.24 mg/L)............................................... 103


by summing the 12 measured DBFs (1. 12 DBPOX) in Lake Austin

water: pH about 8, C12/N ratio 3 to 1,2 mg/L nominal total

residual after 2-d, ambient bromide (0.24 mg/L)............................................... 103


by summing the 12 measured DBFs (2 12 DBPOX) in Lake Austin


residual after 2-d, ambient bromide (0.24 mg/L) ............................................... 104


by summing the 12 measured DBFs (I12 DBPOX) in Lake Houston


residual after 2-d, 0.5 mg/L bromide added....................................................... 105


by summing the 12 measured DBFs (112 DBPOX) in Lake Houston




by summing the 12 measured DBFs (S 12 DBPOX) in Lake Houston



xvm


by summing the 12 measured DBFs (2 12 DBPOX) in California

State Project water: pH about 6, Cla/N ratio 3 to 1, 2 mg/L nominal

total residual after 2-d, 0.5 mg/L bromide added............................................... 107


by summing the 12 measured DBFs (E 12 DBPOX) in California

State Project water: pH about 10, Cb/N ratio 3 to 1, 2 mg/L nominal

total residual after 2-d, ambient bromide (0.10 mg/L)....................................... 107

7.1 University of Houston pilot plant................................................................................... 110

7.2 City of Austin pilot plant................................................................................................ Ill

7.3 Metropolitan Water District of Southern California La Verne pilot plant..................... 112

8.1 Water treatment plant flow schematic for midsouth utility............................................ 147

8.2 Flow diagram of water purification process for utility treating

Mississippi River water...................................................................................... 157

8.3 Water treatment plant flow schematic for utility treating Biscayne Aquifer

water................................................................................................................... 165

8.4 Effect of chlorine dose on TTHM formation in colored groundwaters.......................... 175

8.5 Water treatment plant flow schematic for northeastern utility....................................... 177

8.6 Water treatment flow schematic for Pacific Northwest utility....................................... 184

9.1 High performance liquid chromatography system hardware configuration................... 199

9.2 Particle beam with nebulizer modification..................................................................... 201

9.3 a Enrichment system valve configuration, load mode and inj ect mode............................ 204

9.3b Enrichment system valve configuration, analysis mode................................................. 204

9.4 Chromatograms for LC-KI-UV analyses of LAW Task la samples

and reference solutions....................................................................................... 210

9.5 Chromatograms for LC-KI-UV analyses of the chlorination and

chloramination of glycylalanine......................................................................... 213

9.6 LC-ESI-MS Chromatograms for the reaction of chlorine with

glycylalanine: total ion current, 203 m/z chromatogram, and 278

m/zmasschromatogram..................................................................................... 215

xix

9.7 Mass spectra of LC-ESI-MS peaks from the reaction of chlorine with

glycylalanine....................................................................................................... 216

9.8a Simultaneous distillation extraction (SDE) apparatus.................................................... 221

9.8b Evaporative concentration system.................................................................................. 222

9.9 GC-MS chromatograms of SDE analyses of midsouth distribution system

water, midsouth plant influent, and chloraminated blank................................... 229

9.10 AMW distribution of DOC and UV-254 for source water CSPW

(June 1995)......................................................................................................... 247

9.11 AMW distribution of DOC, UV, and DOX for chlorinated CSPW

(June 1995)......................................................................................................... 248

9.12 AMW distribution of DOC, UV, and DOX for chloraminated CSPW

(June 1995)......................................................................................................... 248

9.13 AMW distribution of source water DOC and of DOC and DOX of

chloraminated LHW, SDS condition A (pH = 6, C12/N = 5/1,

with 48-hr residual of 4 mg/L)............................................................................ 249

9.14 AMW distribution of source water DOC and of DOC and DOX

of chloraminated LHW, SDS condition B (pH = 8, C12/N = 7/1,

with 48-hr residual of 4 mg/L)........................................................................... 249

9.15 Comparison of AMW distribution of DOC for four source waters................................ 251

9.16 Comparison of AMW distribution of DOC for four chloraminated waters................... 251

9.17 AMW distribution of DOC, UV, and DOX for LHW pilot plant effluent

(enhanced coagulation)....................................................................................... 252

9.18 AMW distribution of DOC, UV, and DOX for chloraminated water

from Pacific Northwest....................................................................................... 253

9.19 AMW distribution of DOC, UV, and DOX for chloraminated water

from the midsouth............................................................................................... 253

9.20 AMW distribution of DOC, UV, and DOX for prechlorinated/

postchloraminated CSPW (April 1995).............................................................. 255

9.21 AMW distribution of DOX for four chloraminated waters............................................ 255

xx

FOREWORD

The AWWA Research Foundation is a nonprofit corporation that is dedicated to the

implementation of a research effort to help utilities respond to regulatory requirements and

traditional high-priority concerns of the industry. The research agenda is developed through a process

of consultation with subscribers and drinking water professionals. Under the umbrella of a Strategic

Research Plan, the Research Advisory Council prioritizes the suggested projects based upon current

and future needs, applicability, and past work; the recommendations are forwarded to the Board of

Trustees for final selection. The foundation also sponsors research projects through the unsolicited

proposal process; the Collaborative Research, Research Applications, and Tailored Collaboration

programs; and various joint research efforts with organizations such as the U.S. Environmental

Protection Agency, the U.S. Bureau of Reclamation, and the Association of California Water

Agencies.

This publication is a result of one of these sponsored studies, and it is hoped that its findings

will be applied in communities throughout the world. The following report serves not only as a

means of communicating the results of the water industry's centralized research program but also as

a tool to enlist the further support of the nonmember utilities and individuals.

Projects are managed closely from their inception to the final report by the foundation's staff

and large cadre of volunteers who willingly contribute their time and expertise. The foundation

serves a planning and management function and awards contracts to other institutions such as water

utilities, universities, and engineering firms. The funding for this research effort comes primarily

from the Subscription Program, through which water utilities subscribe to the research program and

make an annual payment proportionate to the volume of water they deliver and consultants and

manufacturers subscribe based on their annual billings. The program offers a cost-effective and fair

method for funding research in the public interest.

A broad spectrum of water supply issues is addressed by the foundation's research agenda:

resources, treatment and operations, distribution and storage, water quality and analysis, toxicology,

economics, and management. The ultimate purpose of the coordinated effort is to assist water

suppliers to provide the highest possible quality of water economically and reliably. The true benefits

are realized when the results are implemented at the utility level. The foundation's trustees are

pleased to offer this publication as a contribution toward that end.

xxi

Disinfection practices in the U.S. drinking water industry are now evolving in response to

several concerns and will continue to evolve over the next decades. In response to current and

anticipated disinfection by-product (DBF) regulations, many utilities have begun to employ

chloramines as a disinfectant, and others will do so in the future. Also, in response both to DBF

regulations and to the Surface Water Treatment Rule (SWTR) and Enhanced SWTR, other utilities

will switch to ozone as the primary disinfectant and chloramines as the secondary disinfectant. A

third possibility is the initial use of free chlorine for disinfection purposes to meet the SWTR,

followed by the introduction of ammonia at some point in the treatment train to minimize further

formation of DBFs. This report addresses what chemical and operation factors influence DBF

formation; what known and unidentified DBFs are formed; and what treatment steps can be

implemented to lower the DBF concentration.

George W. Johnstone James F. Manwaring, P.E.

Chair, Board of Trustees Executive Director

AWWA Research Foundation AWWA Research Foundation

xxn

ACKNOWLEDGMENTS

The authors of this report are indebted to the cooperation and participation of the

following water treatment utilities that were involved in this project:

City of Austin Water Department, Austin, Texas

City of Houston Department of Public Works, Houston, Texas

Metropolitan Water District of Southern California

Palm Beach County Utility Department, West Palm Beach, Florida

Philadelphia Suburban Water Company

A utility in the mid-south

A utility treating Mississippi River water

A utility treating Pacific Northwest lake water

In addition, the advice and help of the Project Advisory Committee (PAC) and

AWWARF project officers Joel Catlin and Ann Scarritt were sincerely appreciated. The PAC

consisted of William Lauer, Program Manager, AWWA, Denver, Colo.; H. Paul Ringhand,

Research Chemist (retired), U.S. Environmental Protection Agency, Cincinnati, Ohio; E. Marco

Aieta, Senior Vice-President, Montgomery Watson, Boulder, Colo.; and Susan Teefy, Water

Quality Engineer, Alameda County Water Department, Fremont, Calif.

The authors would like to thank Djanette Khiari for her work on the simultaneous

distillation extraction and ultrafiltration experiments, Ted. K. Lieu for the liquid chromatography

and mass spectrometry work, Michael Sclimenti for developing the cyanogen halide method and

for work on the California State Project Water (CSPW) pilot plant, Marshall Ray for operation of

the CSPW plant, and Xiaoyan Chang for willing assistance whenever needed.

At the University of Houston, we acknowledge the assistance of Louis A. Simms,

Departmental Chemist, for his support of the dissolved organic halogen analytic work and of the

operation of the pilot plant treating Lake Houston Water.

xxm

EXECUTIVE SUMMARY

INTRODUCTION


several concerns and will continue to evolve over the next decade. In response to current and



regulations and to the Surface Water Treatment Rule (SWTR) and Enhanced SWTR, other

utilities will switch to ozone as the primary disinfectant and chloramines as the secondary

disinfectant. A third possibility is the initial use of free chlorine for disinfection purposes to meet

the SWTR, followed by the introduction of ammonia at some point in the treatment train to

minimize further formation of DBFs.

Some known DBFs (e.g., trihalomethanes, haloacetic acids, and haloacetonitriles)

associated with chlorination have been observed during chloramination as well; however, these

chemicals are generally present at lower concentrations. A decreased dissolved organic halogen

(DOX) concentration also is observed upon chloramination; however, a smaller percentage of the

chemicals comprising the DOX has been identified for chloramination in comparison to

chlorination. Except for cyanogen chloride, halogen-substituted DBFs preferentially formed

from chloramination have not been identified. Furthermore, only limited work on the DBFs

from the chloramination of ozonated water (be they halogen-substituted or not) has been

performed. Thus, prior to this study, two key questions emerged in light of increased use of

chloramines:

1. Why are significant quantities of known DBFs formed in some cases?

2. Are any of the currently unidentified chloramination DBFs of health and potential

regulatory significance?

XXV

Formation of known DBFs may result from specific chemical characteristics of the water

or the chloramination process. These parameters might include the total organic carbon (TOC)

concentration, the bromide ion concentration, the pH, the chlorine to ammonia nitrogen ratio, the

relative ratio of mono- and dichloramine, the chloramine dosage, the order of addition of

chlorine and ammonia, and the intensity of mixing during this addition. Prior to this study, the

importance of these parameters in the formation of known DBFs during chloramination was not

well defined and needed detailed investigation.

To address the above issues, this project covered three primary aspects of work:

1. What chemical and operational factors influence DBF formation;

2. What known and unidentified DBFs are formed; and

3. What treatment steps can be implemented to lower the DBF concentrations.

The project research program consisted of laboratory and pilot-scale work, organized in a

logical progression, starting from a basic investigation of the influence of specific water quality

and operational parameters and progressing to identifying and implementing solutions to

minimize DBF formation under practical treatment conditions.

The primary participants in this project were the University of Houston (UH) and the City

of Houston, the University of Texas at Austin (UT) and the City of Austin, and the Metropolitan

Water District of Southern California (MWDSC). Five other utilities across the country

participated through a full-scale sampling program and provided water for limited laboratory-

scale testing. These utilities were selected to cover various raw water characteristics and

treatment conditions as well as to provide geographical diversity.

APPROACH

The project consisted of four main tasks. In the first task (Task la Chapter 5), batch

experiments were conducted on the three primary water sources, Lake Austin water (LAW),

Lake Houston water (LHW) and California State Project water (CSPW). Using preformed

xxvi

chloramines, the batch experiments to determine DBF formation during chloramination were

chosen to cover variable water chemistry conditions:

pH: 6, 8, 10,

total chlorine residual after 48 hours: 1,2,4 mg/L, and

C12/NH3-N mass ratio (called C12/N ratio): 3/1,5/1,7/1.

This task also included a study of variable mixing conditions, as well as sequential

addition of chlorine followed by ammonia, each under five different water chemistry conditions

(Task Ib Chapter 6):

low, medium, and high mixing energies with simultaneous addition of chlorine

and ammonia, and

chlorine then ammonia with a 30-second delay, low and medium mixing energies.

The formation of DBFs was then measured after two days holding time to simulate

passage through a distribution system (2-d simulated distribution system (SDS) DBFs).

In the second task (Task 2 Chapter 7), a pilot testing program on each of the primary

water sources was conducted to confirm the findings of the batch studies in continuous-flow.

The goal of this task was to provide insight into the expected behavior of full-scale plants.

Whereas Task la was performed entirely on source waters, Task 2 studied source water and post-

filter chloramination of conventionally treated water (i.e., coagulated or softened, settled and

filtered) with and without source water ozonation.

In the third task (Task 3 Chapter 8), the scope of the project was expanded to include

water sources in five other geographical locations: northeast, northwest, deep south (2) and mid-

south. These other water sources were selected to cover a wide range of water qualities and

operational characteristics. Operational data were collected from these five locations as well as

finished water samples for analysis. Finally, source water from these five locations was shipped

to the University of Texas, where selected laboratory-scale batch study tests were performed,

three conditions for each water.

xxvn

For each condition in the first two tasks, four trihalomethanes (THMs) and DOX

concentrations were determined for each sample collected and six haloacetic acids (HAAs) and

two cyanogen halides (CNX) (cyanogen chloride and cyanogen bromide) were determined on

selected representative samples. For Task 3, the complete suite of analyses was performed on all

full-scale and bench-scale tests.

The fourth task (Task 4 Chapter 9) consisted of development and application of

analytical techniques for identifying currently unknown DBFs. These new analytical techniques

were applied to selected representative samples collected throughout the study.

RESULTS

The results of this study confirm that DBF formation during chloramination generally

does not pose a regulatory concern based on current drinking water regulations and probably will

not cause a concern with the proposed Stage 1 regulations. Some problems may arise in meeting

the proposed Stage 2 regulations for HAAs (see Table 10.1). Although chloramines limit the

formation of THMs to concentrations generally below that of Stage 2 of the proposed

Disinfectants/Disinfection By-Products (D/DBP) Rule and limit trichloroacetic acid (TCAA)

generally to concentrations below the detection limit (BDL) of the analytic method used,

chloramines were not as effective in minimizing the formation of dihalogen-substituted HAAs

(DCAA, DBAA, and BCAA collectively called DXAA).

Even though chloramines generally do not produce concentrations of most regulated

chemicals that are of concern, formation of unregulated and uncharacterized halogenated

chemicals, as measured by the DOX analysis, is significant (as high as 300 ug C17L) under some

conditions. Therefore, water utilities may want to consider concentrations of both specific

regulated chemicals and DOX in selecting operating conditions for chloramination.

Some decrease in DBF formation may be observed through improved mixing at the point

of chemical addition. Also, simultaneous addition of chlorine and ammonia, in comparison to

delayed addition of ammonia, should reduce DBF formation, especially formation of THMs. In

bench scale mixing tests, the decrease in DBF formation through improved mixing and

simultaneous chemical addition did not exceed 50 percent based on 48-hr SDS tests; therefore,

this approach to DBF control is most applicable to situations where modest decreases in DBF

xxvm

formation are sought. The possible benefits from this approach also are a function of the quality

of the mixing and chemical addition schemes in current use.

System chemistry affects DBF formation far more than mixing. In general, the formation

of DBFs decreases with increasing pH (up to pH 10 studied) and decreasing Cli/N ratio (down to

3/1 studied) (see Chapters 5 and 6). Therefore, manipulation of these two major operating

variables can significantly impact DBF formation. Unfortunately, the general observations of the

effect of pH and Ck/N ratio on DBF formation may not hold for all waters near neutral pH (7 to

8.5) because of the complexity of haloamine chemistry over this pH range. Therefore, bench

scale testing like that performed in Task la of this research is recommended as an initial step in

investigating the impact of operating conditions on DBF formation. Further investigation at pilot

scale also may be warranted if substantial changes in operating conditions are contemplated.

As noted above, decreasing the Cb/N ratio, especially to low values such as 3/1,

decreases DBF formation. Unfortunately, some water utilities have experienced problems in

maintaining adequate microbiological quality in distribution systems at low C^/N ratios.

Growth of nitrifying bacteria is a particular problem. Therefore, minimizing DBF formation and

maintaining acceptable microbiological water quality in the distribution system may conflict

with one another. Possible adverse water quality impacts should be considered in conjunction

with a decrease in the Cli/N ratio to low levels.

Any strategy aimed at controlling DBF formation through modification of pH and the

Cli/N ratio will have practical ranges of workable values that are specific to each situation. In

some cases, the workable ranges may be inadequate to satisfactorily control DBF formation. In

this study, the HAA6 concentration usually consisted of only dehalogenated acids (e.g.,

dichloroacetic acid). Conceivably, the HAAS concentration in some waters could exceed the

proposed Stage 2 regulations. Under these circumstances, preozonation followed by

chloramination should be considered. This research showed that ozonation prior to

chloramination decreased the formation of both HAAs and DOX.

In addition to pH and the Cb/N ratio, two other system chemistry parameters may be

important in DBF formation: bromide and alkalinity. This research shows that, as the bromide

concentration increases (up to 0.74 mg/L studied), DBF formation likewise increases (see Figure

5.10 as an example) and the speciation within the individual classes of DBFs (e.g., THMs) shifts

toward the bromine substituted chemicals (see Figure 5.14 as an example). Therefore, water

XXIX

utilities that experience cyclical changes in the bromide concentration of their source water can

expect an increase in DBF formation when the bromide ion concentration increases and vice

versa.

Monochloramine can react with organics via an acid-catalyzed mechanism to yield

halogen-substituted organics. This reaction mechanism is catalyzed by proton donors such as

carbonic acid and bicarbonate, the latter of which is a component of alkalinity and a common

constituent of natural waters. Thus, as alkalinity increases, the rate of DBF formation also may

increase. Utilities that have significant alkalinity (up to 165 mg CaCOa/L were investigated),

especially those practicing or considering lime softening, may want to examine the effect of

alkalinity removal on DBF formation. The effect of alkalinity on DBF formation was not

formally part of this research; however, some very limited data from several pilot plant runs

suggest that alkalinity may impact DBF formation.

Specific DBFs (e.g., THMs, HAAs, CNX) may comprise a very small percentage of the

DOX concentration. Under such circumstances, water utilities may want to investigate their

water in more detail to identify additional chemicals. This research examined a number of new

analytical approaches for identifying additional chloramination DBFs (see Chapter 9). Ultra-

filtration (UF) using DOX and TOC surrogates and liquid chromatography (LC) are methods that

could be adopted by a research laboratory to provide general information about halogen-

substituted DBFs. As with other MS investigations into the identification of chlorination DBFs,

the ultimate goal is to develop analytical methods using more readily available instrumentation

once unknown DBFs have been identified. The actual practice of this approach cannot be

instituted, however, until more of the chloramine DBFs are identified and their health

significance evaluated. This study has shown that an initial full-scan, low resolution LC-

electrospray ionization (ESI)-mass spectrometry (MS) run can provide preliminary halogen

content and molecular weight information. Subsequent, high resolution MS and MS-MS runs

could then focus on peaks of interest to determine chemical composition and structure for DBF

identification.

XXX

CONCLUSIONS

In summary, the following major conclusions can be made based on the results of this

study. A complete list of conclusions is contained in Chapter 10.

The results from the bench-scale chemistry studies, the pilot-scale studies, and the

studies of geographically diverse waters generally agreed, giving confidence that

the findings of this study would be applicable to a wide variety of waters.

Over the range studied (1 to 4 mg/L), the total disinfectant residual after two days

of incubation had little influence on the resulting DBFs formed.

Controlling THMs to the levels of Stage 2 of the proposed D/DBP Rule using

chloramination should be possible.

Dihalogen-substituted HAAs (DXAA) dominated the 2-d SDS HAA6, implying

that they might not be well controlled by using chloramination.

Substantial quantities of 2-d SDS DOX were formed in all waters studied,

particularly when dichloramine was present.

Low percentages (commonly below 25 percent) of the 2-d DOX could be

accounted for by summing the molar concentration of the 12 2-d SDS DBFs

measured in this study, indicating that many unidentifiable DBFs were being

formed during chloramination.

In general, DBF formation increases as the pH decreases and the Cb/N ratio

increases.

The presence of bromide ion complicates the control of DBFs because of the

complexity of bromamine chemistry.

When bromide ion is present, CNBr is formed in addition to CNC1, thus

increasing the CNX. The base-catalyzed hydrolysis of CNX resulted in less CNX

being present after two days of incubation at higher pHs.

In the waters where source water chloramination and postfiltration chloramination

were compared, little effect on the resulting SDS DBFs was found.

XXXI

In the bench-scale batch tests, relative mixing energy had little influence on

resulting 2-d SDS DBF concentrations, but simultaneous addition of chlorine and

ammonia is recommended.

Ozonation altered DBF precursors such that applying ozone prior to

chloramination resulted in lessened concentrations of resulting 2-d SDS DBFs.

In some chloraminated water, the <500 dalton ultrafiltration (UF) fraction

represented approximately 43 to 61 percent of the DOX.

In some of the other chloraminated waters, the two highest molecular weight

fractions (the 3K to 10K and >10K) together represented approximately 39 to 55

percent of the DOX. Thus, significant concentrations of halogen-substituted DBFs

with very high molecular weight also are possible.

UF provides a unique analytical tool to preliminarily ascertain which molecular

weight fraction is most significant for a site specific chloramination.

Dihalomethanes (dibromo-, bromoiodo-, and diido-) may be specific

chloramination DBFs.

Monochloramine, not dichloramine, reacted with small model peptides.

UF, simultaneous distillation extraction gas chromatography-mass spectrometry

(SDE-GC-MS), liquid chromatography-electrospray ionization-mass spectrometry

(LC-ESI-MS), and liquid chromatography-potassium iodide-ultraviolet detection

(LC-KI-UV) are all techniques applicable to the study of chloramine DBFs.

RECOMMENDATIONS

Overall, practicing conventional coagulation, adding well mixed chlorine and ammonia

solutions simultaneously in the appropriate ratio, and keeping the pH in the distribution system

(as represented by incubation pH in this study) as high as possible after chloramination at as low

a Cb/N ratio as possible should minimize overall DBF formation. Where needed, preozonation

before chloramine addition should further decrease DBF formation.

xxxn

CHAPTER 1

GENERAL PURPOSE OF STUDY


several concerns and will continue to evolve over the next decade. In response to current and



regulations and to the Surface Water Treatment Rule (SWTR) and Enhanced SWTR, other

utilities will switch to ozone as the primary disinfectant and chloramines as the secondary

disinfectant. A third possibility is the initial use of free chlorine for disinfection purposes to meet

the SWTR, followed by the introduction of ammonia at some point in the treatment train to

minimize further formation of DBFs.

Some known DBFs (e.g., trihalomethanes, haloacetic acids, and haloacetonitriles)

associated with chlorination have been observed during chloramination as well; however, these

chemicals are generally present at lower concentrations. A decreased dissolved organic halogen

(DOX) concentration also is observed upon chloramination; however, a smaller percentage of the

chemicals comprising the DOX has been identified for chloramination in comparison to

chlorination. Except for cyanogen chloride, halogen-substituted DBFs preferentially formed

from chloramination have not been identified. Furthermore, only limited work on the DBFs

from the chloramination of ozonated water (be they halogen-substituted or not) has been

performed. Thus, prior to this study, two key questions emerged in light of increased use of

chloramines:

1. Why are significant quantities of known DBFs formed in some cases?

2. Are any of the currently unidentified chloramination DBFs of health and potential

regulatory significance?

Formation of known DBFs may result from specific chemical characteristics of the water

or the chloramination process. These parameters might include the total organic carbon (TOC)

concentration, the bromide ion concentration, the pH, the chlorine to ammonia nitrogen mass

ratio (called Cb/N ratio), the relative ratio of mono- and dichloramine, the chloramine dosage,

the order of addition of chlorine and ammonia, and the intensity of mixing during this addition.

Prior to this study, the importance of these parameters in the formation of known DBFs during

chloramination was not well defined and needed detailed investigation.

To address the above issues, this project covered three primary aspects of work:

1. What chemical and operational factors influence DBF formation;

2. What known and unidentified DBFs are formed; and

3. What treatment steps can be implemented to lower the DBF concentrations.

The project research program consisted of laboratory and pilot-scale work, organized in a

logical progression, starting from a basic investigation of the influence of specific water quality

and operational parameters and progressing to identifying and implementing solutions to

minimize DBF formation under practical treatment conditions.

The primary participants in this project were the University of Houston (UH) and the City

of Houston, the University of Texas at Austin (UT) and the City of Austin, and the Metropolitan

Water District of Southern California (MWDSC). Five other utilities across the country

participated through a full-scale treatment plant sampling program and provided water for

limited laboratory-scale testing. These utilities were selected to cover various source water

characteristics and treatment conditions as well as to provide geographical diversity.

CHAPTER 2

LITERATURE REVIEW

This chapter is primarily a literature review on DBF formation during chloramination,

chloramine and bromamine chemistry, the nature of possible DBF precursors and the

identification of possible "new" DBFs.

DISINFECTION BY-PRODUCT FORMATION

In general, most reports indicate that chloramination of water produces limited formation

of specific DBFs of current and future regulatory concern, i.e., trihalomethanes (THMs),

haloacetic acids (HAAs), haloacetonitriles (HANs), and cyanogen chloride (CNC1). This review

will focus on the exceptions, which provide some insight into conditions that might promote

formation of specific DBFs during chloramination.

Jacangelo et al. (1989) evaluated pilot- and full-scale treatment trains at four utilities

treating surface waters. Ozone, chlorine and chloramines were studied in various combinations

as primary and secondary disinfectants. At Utility 2, ozone in combination with chloramines as

a secondary disinfectant caused very little formation of THMs, HAAs, HANs and cyanogen

chloride. At Utility 3, which practiced prechloramination, significant production of both THMs

and HAAs occurred; the distribution system concentration of each class of DBFs was 44 ug/L.

The authors speculated that the relatively high levels of DBFs resulted either from inadequate

mixing at the point of chlorine and ammonia addition or from the high raw water TOC (7.7

mg/L). At Utility 4, both ozonation/chloramination and chloramination alone were evaluated. In

both cases, some production of HAAs (10 ng/L) was observed, while the CNC1 concentration

was approximately 3 ng/L with ozonation/chloramination. The raw water had a relatively high

bromide concentration (320 ug/L), so perhaps this played a role in HAA formation. Although

far from conclusive, this study suggests that poor mixing at the point of chlorine and ammonia

application, a high raw water TOC concentration and a high raw water bromide concentration

may be important factors in DBF formation during chloramination.

Stevens et al. (1989) performed some limited tests on chloraminated Ohio River water

measuring non-purgeable organic halogen (NPOX), which is DOX minus the THMs. At a

chloramine dose of 22.9 mg/L, NPOX formation was 20% of that observed at a chlorine dose of

20 mg/L, indicating, as expected, that chloramines produce less halogen substituted by-products

than chlorine. NPOX formation with chloramination did, however, show a pH dependence. The

NPOX concentration was much greater at pH 5.9 than at pH 11.5. This suggests that pH may be

an important factor in studying DBP formation during chloramination.

Krasner et al. (1989a) found that cyanogen chloride was formed to a greater extent in

chloraminated waters in comparison to chlorinated waters. Also, the cyanogen chloride

concentration appeared to be a function of the Cb/N ratio, with the cyanogen chloride

concentration increasing as the ratio increased. This implies that the dichloramine concentration

may be important in cyanogen chloride (and perhaps cyanogen bromide) formation. The need to

consider the effects of chloramine speciation on DBP formation is also illustrated.

Shukairy and Summers (1992) studied ozonation and ozonation followed by

biodegradation in two water sources, groundwater humic substances and Ohio River water. The

waters were either chlorinated or chloraminated after treatment. For humic substances extracted

from groundwater and concentrated to a TOC concentration of 4.7 to 6.4 mg/L, NPOX formation

was 200-250 ug/L in both water treated by chloramination alone and water treated by

chloramination following ozonation. In Ohio River water the corresponding NPOX

concentration was 90 ng/L. In both waters, preozonation had little effect on NPOX formation

upon chloramination. The chloramine dose, however, did affect the resulting NPOX

concentration. The concentration approximately doubled as the chloramine dose was increased

from 1 to 5 mg/mg dissolved organic carbon (DOC). Biodegradation alone and ozonation

followed by biodegradation significantly decreased NPOX formation in both waters. Thus, this

work suggests some dependence of DBP formation on chloramine dose, as well as the potential

for beneficial contributions from a biodegradation step.

USEPA studies at Jefferson Parish, LA (Lykins et al. 1994) compared the performance of

four disinfection schemes in pilot plants operating in parallel: pre- and post-chlorination

(C\2/C\2\ pre- and post-chloramination (NHiCl/NHiCl), preozonation and post-chlorination

(Os/Cb), and preozonation and post-chloramination (Os/NFkCl). The first disinfectant addition

point was prior to a mixing chamber immediately before the sand filters, while the second

addition point was after the sand filters. Nineteen DBFs were measured, and DBP production as

a function of the disinfection scheme was, in descending order:

(NH2C1/NH2C1), and (O3/NH2C1). The use of chloramines dramatically lessened the

concentrations of all of the DBFs, as would be expected. With chloramination, HAAs,

consisting mostly of dichloroacetic acid, were present in the highest concentrations, followed by

the THMs. The concentrations of many DBFs were below the method detection limit. DOX

concentrations averaged 540 ug C17L for C12/C12, 59 ug C1YL for NH2C1/NH2C1 and were about

equal to background for O3/NH2C1. Although the production of halogen-substituted DBFs

decreased through the use of chloramine, it was not eliminated. Also, halogen-substituted DBF

production was greater with (NH2C1/NH2C1) than with (O3/NH2C1).

The City of Portland, OR in the past used prechloramination to treat a low pH (< 7) and

low bromide water. The C12/N mass ratio was 7/1, which favors production of dichloramine.

The resulting THM concentrations were less than 10 ng/L, but HAA concentrations ranged from

20 to 40 ug/L in the distribution system.

The MWDSC treats California State Project Water (CSPW) at the Henry J. Mills

Filtration Plant and used chloramines in the past as the primary disinfectant. During that time,

THMs were less than 10 ug/L. During drought conditions, the bromide concentration in the

water increased to 0.5 mg/L, a relatively high level. As a consequence of this increase, THM

and HAA concentrations on the order of 20 ug/L and 10 ug/L, respectively, were observed.

These increases may have been associated with the instability of bromamines that would be

formed in the high bromide ion concentration water by the reaction of ammonia with

hypobromous acid after oxidation of bromide ion with chlorine.

CHLORAMINE/BROMAMINE CHEMISTRY

Chloramine chemistry is fairly well understood at this time and can be summarized in its

simplest form by the three reversible reactions listed below:

NH3 + HOC1 <-» NH2C1 + H2O (2.1)

NH2C1 + HOC1 <-> NHC12 + H2O (2.2)

NHC12 + HOC1 <-> NC13 + H2O (2.3)

2.5

) 2.0

1.5

1.0

0.5

ttWCUBV 'BE fOOttCUBV (OM

Trichloramine._

2

i

3

i

456 Chlorine Dose (mg/L)

10

8 10 12 Chlorine/Nitrogen Ratio

14 16 18 20

Source: Modified from Barrett et al. (1985)

Figure 2.1 Chloramine dose-residual curve for California State Project water

The dominant chloramine species is a function of the Ch/N ratio and pH. An example is shown

in Figure 2.1 for California State Project water in which the ammonia dose was constant at 0.5

mg N/L and the chlorine dose was varied. At small chlorine doses, NF^Cl dominated, reaching a

peak concentration at a Cb/N ratio of about 5/1. At larger doses, the NF^Cl concentration

decreased and NHCh formed, reaching a peak concentration at a Ch/N ratio of about 8/1. At

even larger chlorine doses (C^/N ratio of 10/1 and greater), both mono- and dichloramine

disappeared and trichloramine and free chlorine formed. This progression from monochloramine

to trichloramine and eventually free chlorine is known as breakpoint chlorination.

Monochloramine is generally the chemical of interest in drinking water disinfection. The

production of dichloramine is favored as the Ch/N ratio increases and the pH decreases. The

hydrolysis reactions (the reverse reactions in Eq. 2.1-2.3) also are of considerable interest

because they generate HOC1, which may be important in the formation of chlorine substituted

orgam'cs, HOBr/OBr", and bromamines. Also, the monochloramine hydrolysis reaction liberates

ammonia, which is needed for bromamine formation. The hydrolysis of monochloramine is a

minimum at pH 8 to 8.5 and is larger at both pH 6 and 10. At equilibrium, several percent, at

most, of the monochloramine is hydrolyzed. The hydrolysis equilibrium for dichloramine is

considerably greater than that for monochloramine, but the rate of hydrolysis is much slower

(Morris and Issac 1983). In addition to hydrolysis and Eq. 2.3, dichloramine decomposes by

several other reactions, as summarized by Jafvert and Valentine (1992). Two of the reaction

pathways are base catalyzed. Therefore, dichloramine decomposition accelerates as the pH

increases and as the concentration of bases increases (e.g., alkalinity). Taken together, the

kinetic and equilibrium considerations lead to the conclusion that dichloramine is much less

stable than monochloramine under most conditions of practical interest. The greater instability

of dichloramine may lead to underestimates of its significance in DBF formation if chloramine

residual speciation measurements are performed after relatively long contact times, which might

be typical of distribution system samples or simulated distribution system tests.

Monochloramine decomposes through disproportionation to dichloramine, with subse

quent decomposition of dichloramine being primarily responsible for oxidant loss. The two

major pathways for monochloramine disproportionation are hydrolysis of monochloramine with

subsequent reaction of free chlorine with monochloramine (Eq. 2.1 and 2.2) and general acid

catalysis, as shown in Eq. 2.4 (Valentine and Jafvert 1988):

NH2C1 + NH2C1 + H+ <-» NHC12 + NH3 + H+ (2.4)

General acid catalysis also liberates ammonia. The rate of general acid catalysis (Eq. 2.4) is a

function of the concentration of proton donors and increases as their concentration increases and

the pH decreases. Valentine and Jafvert (1988) note that the carbonate system, via carbonic acid

and bicarbonate, may significantly increase the rate of acid-catalyzed disproportionation at

concentrations and pH values typical of many drinking waters. Thus, the decomposition rate of

both monochloramine and dichloramine may increase as alkalinity increases.

Monochloramine will produce DOX, ranging from 9-49% of that observed with free

chlorine (Jensen et al. 1985). Monochloramine has little tendency to produce THMs and should

lead to minimal production of HAAs (Coughlan and Davis 1983). Snyder and Margerum (1982)

and Isaac and Morris (1985) showed that monochloramine could transfer chlorine to nitrogenous

organic chemicals by general acid catalysis reactions in a similar reaction scheme to Eq. 2.4,

except that one of the monochloramine molecules is replaced by an organic chemical.

Significant reaction rates for many of the test chemicals were observed through pH values as

high 8 to 8.5. Snyder and Margerum (1982) concluded that general acid catalysis with

monochloramine produced a very reactive chlorinating agent. As with monochloramine

disproportionation, a dependence of reaction rates on the concentration of proton donors would

be expected; therefore, reaction rates may increase as alkalinity increases. Limited data show

that dichloramine gives a much greater production of DOX than monochloramine, not very much

less than that associated with free chlorine (Fujioka et al. 1983).

The presence of bromide complicates the chemistry of the system considerably. The

reactions of bromide with chlorine and the chloramines to produce bromamines are as follows

(Rook 1980; Wajon and Morris 1980; Haag 1980):

Bf + HOC! <-» cr + HOBr (2.5)

NH3 + HOBr <-» NH2Br + H2O (2.6)

NH2Br + HOBr <-> NHBr2 + H2O (2.7)

NHBr2 + HOBr <-> NBr3 + H2O (2.8)

NH2C1 + Br' <-» NH2Br + CK (2.9)

Like chloramines, the speciation of bromamines is a function of pH and the molar ammonia to

bromine ratio, as shown in Figure 2.2. Figure 2.2 is an equilibrium predominance diagram in

which the lines represent equimolar concentrations of the adjacent species. Dibromamine would

be expected as the dominant chemical near neutral pH when a reasonable amount of ammonia is

available (relative to the bromide concentration). At high pH, monobromamine should be the

dominant chemical. At pH 6, dibromamine, tribromamine, and HOBr could be present. At pH

8, any of the three bromamines plus HOBr could be present. At pH 10, only monobromamine

and OBr" could occur. In systems containing both chloramines and bromamines, as in this

research, the dominant brominated species is not easily determined because of the complexities

in estimating the molar ratio of ammonia to bromine. Nevertheless, the diagram is useful in

-2

? 2-'o: ~

w * 0

o

<9O

i T I I I I I i i

Br 2 HOBr

NHBr 2

I

6

PH

OBr-

NH 2 Br

10

Source: Adapted from Johnson and Sun (1975)

Figure 2.2 Principal species of bromine and bromamines predominating after 1 to 2 minutes at

various pH and ammonia:nitrogen ratios

indicating which species might be present as a function of pH. Clearly, the chemistry is probably

most complicated over the pH range of 7 to 8.5 because of the possibility of forming any one of

the three bromamines.

Bromamines form rapidly, relative to chloramines, and are less stable, dissipating rapidly

in the environment. For example, the half-life of dibromamine is 30 min and monobromamine is

19 hr at pH 8 (Wajon and Morris 1980), Thus, dibromamine is considerably less stable than

monobromamine. The decomposition rate of dibromamine decreases as pH increases (especially

in the range of pH 6-8), as the ammonia concentration increases, and as the dibromamine

concentration decreases. Several pathways for dibromamine decomposition have been

postulated. Some of these pathways show HOBr as a decomposition product. Nitrogen gas is a

typical product, although one pathway shows some ammonia as a decomposition product (Jolley

and Carpenter 1983). Decomposition of tribromamine also yields HOBr as a product. The rate

of decomposition increases with increasing pH and increasing ammonia concentration.

Similarly, hydrolysis of monobromamine yields HOBr as a product. The rate of decomposition

increases with increasing pH and decreasing ammonia concentration. Bromamine species are

highly reactive and appear as free chlorine in the standard analytical techniques used to measure

free and combined chlorine (Palin 1975; Gordon et al. 1987). Because bromamine species are

short-lived, however, their contribution to the total disinfectant concentration should be minimal

after the 24- to 48 hour incubation times used to simulate DBF formation in water distribution

systems.

The reactivity of bromamines in the formation of DBFs is largely unknown, although one

report indicates little formation of THMs with dibromamine (Sugam and Helz 1980). If

bromamines are reactive and if the reactivity varies among the bromamine species, DBF

formation should vary with pH and bromide concentration because of the anticipated dependence

of speciation on these variables.

In the presence of ammonia and bromide, the chlorination of waters may produce

bromochloramine in addition to chloramines and bromamines (Valentine 1986). Various

reactions have been proposed for the production of bromochloramine as follows (Wajon and

Morris 1980; Gazda et al. 1993):

NH2C1 + HOBr o NHBrCl + H2O (2.10)

NH2C1 + Br" <-» NHBrCl + other products (2.11)

NH2Br + HOC1 <-> NHBrCl + other products (2.12)

NH2C1 + NHBr2 <-> NHBrCl + other products (2.13)

NH2C1 + NH2Br <-> NHBrCl + other products (2.14)

The reaction of hypobromous acid with monochloramine (Eq. 2.10) is at least three orders of

magnitude faster at pH 6.5 than the reaction of bromide with monochloramine (Eq. 2.11) (Gazda

etal. 1993).

Valentine (1986) studied the oxidation of AyV-diethyl-p-phenylenediamine (DPD) by

bromochloramine. Bromochloramine reacted rapidly with DPD, leading Valentine to conclude

that the bromine atom of bromochloramine is very labile and reactive and that in reactions with

organic chemicals bromochloramine should produce products similar in nature to those produced

by free bromine. In conducting the experiments, Valentine produced bromochloramine by

adding bromide to solutions of monochloramine at pH 6.5. Analysis of the resulting solution

showed significant concentrations of only monochloramine and bromochloramine and no

10

measurable amounts of the bromamine species. Although the results apply to only one

condition, they are suggestive of the possible importance of bromochloramine in DBF formation

in bromide containing waters. Bromochloramine is essentially half bromamine and half

chloramine in character; therefore, in the standard techniques for measuring free and combined

chlorine, half the bromochloramine concentration appears in the free chlorine fraction and half in

the combined chlorine fraction (Valentine 1986).

Consideration of the above allows some general listing of expectations for the

experiments conducted in this project:

1. Formation of DOX is expected in the presence of monochloramine, although little

THM and HAA formation may be observed.

2. Dichloramine concentrations may be significant at low pH and high Cfe/N ratios.

3. If dichloramine is more reactive (as suggested by some DOX data) or if its

instability leads to a greater free chlorine concentration (especially at the 7/1

Cb/N ratio), larger concentrations of DOX, THM, and HAAs should result with

dichloramine, relative to monochloramine.

4. Alkalinity may influence system chemistry through base catalysis of dichloramine

decomposition and acid catalysis of both monochloramine decomposition and

monochloramine reactions with organic chemicals.

5. If bromide is present in the water, HOBr/OBr", bromamines, and

bromochloramine may form. These species should lead to a greater production of

DBFs because of their high reactivity, and increasing bromide concentration

should increase the production of DBFs. Where DBF speciation is analyzed,

increased concentrations of brominated species should be observed.

6. Of the three pH values tested (6, 8, and 10), the greatest uncertainty about

bromamine speciation is at pH 8, and it seems quite possible that this speciation

could vary considerably among water sources at pH 8 for identical conditions of

chloramination. Thus, the DBF formation in the presence of bromide also could

vary considerably.

7. Dibromamine is the least stable bromamine, and HOBr is a likely decomposition

product. Therefore, conditions that select for dibromarnine formation may

11

accentuate DBF production because of reactions with the HOBr generated during

decomposition. This should be most obvious at pH 6 and possibly pH 8.

8. Chloramination conditions leading to the largest concentrations of free chlorine

(high Ch/N ratios and low pH) should promote the largest formation of free and

combined bromine.

9. Examination of dichloramine:total chlorine and dichloramine:monochloramine

ratios as a function of bromide concentration may indicate the relative role of

bromide and bromamine formation in these systems. Reduced formation of

dichloramine in the presence of bromide would indicate that HOC1 is being

consumed by bromide oxidation in preference to dichloramine production from

monochloramine. Also, increases in the free chlorine concentration as the

bromide concentration increases may be indicative of brominated species because

the latter are measured as free chlorine in the standard analytical methods.

RECOVERY OF DOX IN MEASURABLE DBFs

Krasner et al. (1989) correlated the measured molar concentration of DOX with the

arithmetic molar sum of the 21 individual disinfection by-products (DBFs) measured in a survey

of 35 utilities. The correlation coefficient (r) was 0.56, although some increase in DOX

concentration occurred during shipment of the non-dechlorinated samples. The authors state,

"When data for only the utilities that chloraminated were used, the correlation improved," but the

actual value was not given. Also, recovery factors for the individual DBFs in the DOX

determination were not used. These data indicated a little less than 30 percent of the measured

DOX was accounted for by summing the 21 measured DBFs.

Singer et al. (1992) reported on a study where eight water treatment plants were each

sampled three times during the period from June 1991 to February 1992. Plotting the sum of 12

individually measured DBFs versus DOX produced a line with a slope of 0.36 and an R2 value of

0.83, thus indicating that approximately 36% of the measured DOX was accounted for by

summing the 12 individual DBFs.

12

IDENTIFICATION OF NEW DBFs

A search of the literature showed that the characterization of by-products formed upon

chloramination of drinking water is incomplete, with only a small fraction of compounds

identified and currently being monitored. This group consists of small (one and two carbon)

chlorinated and brominated compounds. Other chloramination by-products have been identified

in nonpotable water, i.e., in wastewater and in solutions of fulvic acid, amino acids, amines, and

other organic compounds (Crochet and Kovacic 1973; Ingols et al. 1953; Burttshell et al. 1959;

Minisci and Galli 1965; Kotiaho et al. 1991; and Kanniganti 1992). For example, chlorinated

aldehydes, chlorinated acids and chlorinated ketone by-products have been identified when

fulvic acid is chloraminated (Kanniganti 1992).

In a more general sense, some work has been done on surrogates of DBFs formed upon

treatment. Significant amounts of nonpurgeable organic halogens are formed with

chloramination even though less THMs and other purgeable organic halogen compounds are

formed compared to chlorination (Amy et al. 1990). Furthermore, chloramination (with

monochloramine) of fulvic acid has been hypothesized to produce DOX with compounds of

higher molecular weight than chlorine-produced DOX (Jensen et al. 1985).

Numerous nitrogen containing compounds exist in surface waters, including NOM

substances such as amino acids, peptides, proteins, humic materials, chlorophylls and man-made

organic chemicals such as herbicides, pesticides, and nitrophenols (Le Cloirec et al. 1983) The

total dissolved amino acid concentration in surface waters has been reported to range from 50 to

1000 ug/L (Hureiki et al. 1994) and in some cases has increased after ozonation or biological

filtration (Le Cloirec et al. 1983). Amino acids and peptides may be chlorinated by direct-

transfer mechanisms from inorganic chloramines (Snyder and Margerum 1982; Isaac and Morris

1983a) to produce organic chloramines. Another plausible mechanism for chloramination

reactions is via formation of an imine intermediate to yield a nitrile (Le Cloirec and Martin

1985).

Currently identified and unidentified DBFs may be of interest to utilities for a variety of

reasons, including disinfection differences between species. The current conventional measure

ments for chlorine cannot distinguish all of the chlorine species that may be present (Wolfe et al.

1985). The compounds may only be short-lived intermediates (Isaac and Morris 1983b) or they

13

may be slow to form (White 1992). Water utilities may experience false positives in the

distribution system, indicating the presence of inorganic chloramines where there is none (Wolfe

etal. 1985).

A method that is designed to cover a wide range of target and nontarget compounds with

a broad range of chemical structures is known as a broad-spectrum analysis. Gas

chromatography/mass spectrometry (GC/MS) has conventionally been used for broad screen

analyses because it allows for many compounds (e.g., volatiles and semivolatiles) to be identified

and quantified. GC/MS cannot be used for nonvolatile or heat sensitive compounds, however.

Jersey (1991) developed an HPLC method that is capable of distinguishing between inorganic

monochloramine and inorganic dichloramine and other chlorinated amines and chlorinated

amino acids. Membrane introduction MS has been used for inorganic chloramines (Kotiaho et

al. 1992) and also for organic chloramines (Kotiaho et al. 1991). DBFs associated with

monochloramine could be identified by liquid chromatography (LC) or capillary zone

electrophoresis interfaced to MS (Kotiaho et al. 1992). Budde et al. (1990) describe the use of

LC/PB/MS as a possible broad-spectrum analytical technique applicable to the determination of

nonvolatile compounds in drinking water. Schroder (1991) has described the use of

LC/thermospray/MS for the analysis of surface water.

14

CHAPTERS

GENERAL SCOPE OF PROJECT

The project consisted of four main tasks. In the first task, batch experiments were

conducted on the three primary water sources, Lake Austin water (LAW), Lake Houston water

(LHW) and California State Project water (CSPW). Using preformed chloramines (Task la), the

batch experiments were chosen to cover variable water chemistry conditions:

1. pH: 6, 8,10,

2. total chlorine residual after 48 hours: 1,2,4 mg/L, and

3. C12/NH3-N mass ratio (called C12/N ratio): 3/1,5/1,7/1.

This task also included a study of variable mixing conditions, each under five different

water chemistry conditions (Task Ib):

1. low, medium, and high mixing energies with simultaneous addition of chlorine

and ammonia, and

2. low and medium mixing energies with the addition of chlorine followed by

ammonia after a 30 second delay.

The formation of DBFs was then measured after two days holding time to simulate

passage through a distribution system (2-d simulated distribution system (SDS) DBFs).

In the second task, a pilot testing program on each of the primary water sources was

conducted to confirm the findings of the batch studies in continuous-flow. The goal of this task

was to provide insight into the expected behavior of full-scale plants. Whereas Task 1 was

performed entirely on source waters, Task 2 studied source water and post-filter chloramination

of conventionally treated water (i.e., coagulated or softened, settled and filtered) with and

without source water ozonation.

In the third task, the scope of the project was expanded to include water sources in five

other geographical locations: northeast, northwest, deep south (2) and mid-south. These other

water sources were selected to cover a wide range of water qualities and operational

15

characteristics. Operational data were collected from these five locations as well as finished

water samples for analysis. Finally, source water from these five locations was shipped to the

UT, where selected batch study experiments were performed, three conditions for each water.

For each condition in the first two tasks, four trihalomethanes (THMs) and DOX

concentrations were determined for each sample collected, and six haloacetic acids (HAAs) and

two cyanogen halide (CNX) (cyanogen chloride and cyanogen bromide) were determined on

selected representative samples. For Task 3, the complete suite of analyses was performed on all

full-scale and bench-scale tests.

The fourth task consisted of development and application of analytical techniques for

identifying currently unknown DBFs. These new analytical techniques were applied to selected

representative samples collected throughout the study.

16

CHAPTER 4

ANALYTIC METHODS AND QUALITY ASSURANCE/QUALITY CONTROL

Each major analytical method used in this study for routine analyses is described briefly.

The associated quality control/quality assurance procedures also are presented.

SIMULATED DISTRIBUTION SYSTEM TREATMENT

Methodology

The simulated distribution system (SDS) measurement attempts to simulate conditions

existing in a typical drinking water distribution system. SDS experiments were performed

extensively on each of the three primary waters, and to lesser extent on the various utility waters.

To ensure consistency of results, a 250-L sample of each primary water was obtained and stored

at 4 C. Raw source water was used (1) because raw water frequently is chloraminated in

treatment plants, and (2) to provide a "worst-case" scenario.

For the batch chemistry studies (Task la), 1-L batches of water were dosed to achieve a

matrix of experimental conditions. Before dosing the water, it was brought to room temperature

(22 C) and its pH was adjusted. The pH was adjusted with nitric acid or sodium hydroxide.

Pure acid or base was used, rather than a buffer, to eliminate any competing reactions. A

sequential filling procedure was adopted when filling the bottles in order to achieve mixing.

First the bottles were partially filled with the sample water. The appropriate dosing solutions

were then added to the partially filled bottles. Care was taken not to overflow the bottles

because they contained reagents. Finally, the bottles were filled slightly overfull with sample

water and capped with a Teflon-lined septum. This procedure provided turbulence that

distributed chemicals throughout the bottle. Bromide was added using a potassium bromide

solution. Chlorine was added in the form of preformed chloramines. The bottles were held at

22 C for 48 hours.

17

Quality Control/Quality Assurance

Duplicate bottles were prepared for the first Task 1A samples. Chlorine residual and

THM concentration were measured on the duplicate samples. Very good reproducibility of

chlorine residual and THM concentration was found. Chlorine residual, for a sample size of 60,

had a sample standard deviation of 0.029 and a mean of 1.40. Total THM concentration had a

standard deviation of 0.81 and a mean of 22.2 for a sample size of 44.

Bottles used for sample treatment were washed with Alconox and rinsed four times with

distilled water, then soaked in 50% by volume nitric acid and rinsed seven times with distilled

water. They were then baked for 12 or more hours at 400 C and stored covered. Teflon septa,

when reused, were washed following the same procedure, with the addition of an acetone wash

after the Alconox step and with the elimination of the baking step.

Reagent grade chemicals were used for all solutions. All solutions were mixed with

distilled, deionized water produced on a Milli-Q filter apparatus. Before use, this water was

determined to be free of chlorine demand.

FORMATION POTENTIAL

Methodology

The potential for formation of DBFs in the three primary source waters was measured.

Water for disinfection by-products formation potential (FP) analysis was chlorinated to the

concentration that resulted in a residual free chlorine concentration of between 3 and 5 mg/L

after 4 days contact time at pH 6, 8, and 10. Four-day chlorine demand among samples varied

from 3 to 11 mg/L. Therefore, doses ranged from 6 to 26 mg/L of chlorine. The method used

here follows protocols described in Standard Method 5710 (APHA et al. 1992) with modifi

cations.

The sample water pH was first adjusted with nitric acid or sodium hydroxide. The water

was then placed in 1-L amber glass bottles. A sequential filling procedure was adopted when

filling the bottles in order to achieve mixing as described above. A bottle was half-filled, the

appropriate chlorine solution was added, and the bottle was filled head-space free and capped

18

with a Teflon-lined cap. Each water was chlorinated at three chlorine concentrations, and the

sample with a chlorine residual closest to 4 mg/L was used for analyses. Disinfection by-product

formation potential (DBPFP) is defined here as the concentration of a given disinfection by

product in the water after contact with chlorine under these conditions. The absence of DBFs at

time zero was assumed.


Bottles used for sample treatment were washed with Alconox and rinsed four times with

distilled water, then soaked in 50% by volume nitric acid and rinsed seven times with distilled

water. They were then baked for 12 or more hours at 400 C and stored covered. Teflon septa,

when reused, were washed following the same procedure, with the addition of an acetone wash

after the Alconox step and with the elimination of the baking step.

Reagent grade chemicals were used for all solutions. All solutions were mixed with

distilled, deionized water produced on a Milli-Q filter apparatus.

PREFORMED CHLORAMINES

Methodology

Preformed chloramines were used in the batch chemistry experiments (Task la).

Preformed chloramines were created by mixing aqueous ammonium sulfate and sodium

hypochlorite solutions. These solutions were formulated so that approximately equal volumes of

the two, when combined, would produce the desired Cb/N ratio. Both solutions were adjusted to

pH 9 with nitric acid and/or sodium hydroxide. The concentration of the chlorine solution was

measured prior to creating preformed chloramines, and small adjustments were made, as needed,

in the volume of ammonium solution added to ensure the correct C12/N ratio. The chlorine

solution was added slowly to the ammonium solution with constant mixing in an ice bath at 1 C.

After 15 minutes of mixing, the concentration of the chloramine solution was measured prior to

dosing the samples.

19


Before using a preformed chloramine solution for dosing samples, the concentration was

determined by iodometric titration. Two measurements were made. If these differed by greater

than 0.10 mg/mL, two more measurements were made. If these second measurements differed

by greater than 0.10 mg/mL, a third pair of measurements was made. If these differed by greater

than 0.10 mg/mL, the chloramine solution was discarded and remixed. An average of the two

appropriate measurements was used for calculations. All solutions were mixed with distilled,

deionized water produced on a Milli-Q filter apparatus. Preformed chloramine solutions were

mixed immediately before use and were discarded after use.

CHLORINE DOSING SOLUTION

Methodology

Hypochlorite stock solution was mixed using Aldrich reagent grade sodium hypochlorite

(NaOCl). When shipped, the NaOCl was nominally 10 percent NaOCl, but its concentration

diminished over time. One mL of straight reagent grade NaOCl in 25 mL deionized water was

titrated with standardized sodium thiosulfate titrant. The resulting solution contained

approximately 20 mg/mL C\2 and was used to make the chlorine dosing solution. The desired

concentration of the dosing solution was 4.5 mg/mL.

The required volume of stock solution to produce 250 mL of an approximately 5 mg/mL

dosing solution was calculated. This volume was diluted to 250 mL with deionized water and

stored in an amber bottle with a Teflon lined cap at 4 C until the concentration dropped below 5

mg/mL, between 2 and 4 weeks.


Before using the chlorine solution for dosing samples or making a preformed chloramine

solution, the concentration was determined with iodometric titration. Two measurements were

made. If these differed by greater than 0.10 mg/mL, two more measurements were made. If

20

these second measurements differed by greater than 0.10 mg/mL, a third pair of measurements

was made. If these differed by greater than 0.10 mg/mL, the chlorine solution was discarded and

remixed. All solutions were mixed with distilled, deionized water produced on a Milli-Q filter

apparatus.

CHLORINE DOSE

Methodology

The volume of chlorine dosing solution added to 1-L bottles (1.025 L actual volume) for

formation potential (FP) and simulated distribution system (SDS) measurements was calculated

as:

Volume dosing solution (mL) = 1.025 (L) x Desired dose (mg/L)

Dosing solution concentration (mg/mL)

The dosing solution was added to bottles using the appropriate volume Eppendorf pipette.


The calculated dose volume was rounded to the nearest uL. This value was recorded and

the resulting actual dose concentration was used in subsequent calculations.

RESIDUAL CONCENTRATIONS

Methodology

Free chlorine, monochloramine and dichloramine residuals were determined using

Standard Method 4500-C1 D for amperometric titration (APHA et al. 1992). High concentration

21

solutions, such as the preformed chloramine dosing solutions, were analyzed using Standard

Method 4500-C1B (APHA et al. 1992) for iodometric titration.

High concentrations, including the residual chlorine in FP samples, were measured using

the standard iodometric titration technique: Standard Method 4500-C1 B Iodometric Method I.

Sample water was placed in a beaker. Five mL of glacial acetic acid and 1 g potassium iodide

(KI) were added while stirring. A yellow-orange color appeared at this stage because of

liberation of iodine. The sample was titrated with the appropriate normality solution until it was

a pale lemon yellow. At this point, 4 mL of starch indicator was added to produce a deep blue

color. Titration was continued until disappearance of blue tint. Titrant volume was recorded and

used to calculate the chlorine concentration.

Lower concentrations of chlorine, such as residual chlorine in SDS experiments, were

measured using amperometric titration: Method 4500-C1 D (APHA et al. 1992). This procedure

measured free chlorine, monochloramine, and dichloramine. A sample of between 100 mL and

200 mL was brought to pH 7 and titrated with 0.564 N phenylarsine oxide until all movement of

the amperometric titrator needle stopped. This first volume of titrant indicated free chlorine.

Next, 0.2 mL of 50 g/L KI was added, and the amperometric titrator setting was changed to

"combined chlorine." Titration continued until all movement of the needle once again ceased.

This second volume of titrant indicated monochloramine. Finally, the pH of the solution was

brought down to 4 with 1.0 mL of acetic acid buffer, and 1.0 mL of 50 g/L KI was added.

Titration continued until all movement of the needle once again ceased. This final volume of

titrant indicated dichloramine. After analysis, the electrode was thoroughly rinsed with

deionized water to avoid carryover of KI into the analysis of the next sample.

The amperometric titration technique also would measure free bromines and

bromamines, if present. All the brominated species would most likely be measured as free

chlorine in the analytical technique. Given the instability of bromamines and the high reactivity

of free bromine, no appreciable concentrations of these chemicals would be expected after the

48-hour incubation period of the SDS experiments.

22


A series of 12 measurements on a sample spiked with chloramines showed a standard

deviation of 0.0078 mg/L at an average concentration of 1.86 mg/L for monochloramine and a

standard deviation of 0.027 mg/L at an average concentration of 1.92 mg/L for dichloramine.

The coefficients of variation were 0.42% and 1.41%, respectively.

Before performing iodometric titration on samples, the sodium thiosulfate titrant to be

used was standardized against a potassium dichromate standard, as discussed in Standard

Method 4500-C1 B (APHA et al. 1992). The potassium dichromate solution was mixed using

freshly boiled, then cooled, deionized water. The potassium dichromate was measured to five

decimal places on a Mettler analytical balance. Two separate solutions were made and labeled A

and B. These solutions were stored in the dark at room temperature. The sodium thiosulfate

titrant was standardized against both solutions before using. The sodium thiosulfate titrant was

stored at 4 C and brought to room temperature before use.

Phenylarsine oxide of the correct normality for amperometric titration was obtained from

Aldrich Chemical Company (Milwaukee, Wis.). Before proceeding with titration, a sample of

dilute mono-chloramine was measured to ensure that the system was operational.

DISINFECTION BY-PRODUCT SAMPLE TREATMENT

Methodology

After termination of the incubation period for either simulated distribution system or

formation potential measurements, samples were taken from each 1-L amber bottle. Two 42-mL

samples were taken for THM analysis; two 42-mL samples were taken for HAA analysis; four

42-mL samples were taken for CNX analysis; and two 250-mL samples were taken for DOX

analysis. The water remaining in the 1-L bottle was used for pH and residual chlorine

measurements as described above.

23

Before the sample vials were filled, preservatives and/or dechlorinating agents were

added. THM samples were dosed with 0.5 mL of glacial acetic acid for preservation and with

0.2 mL of 100 g/L sodium sulflte solution for dechlorination. HAA samples were dosed with 0.8

g of solid ammonium chloride for dechlorination. DOX samples were dosed with 0.5 mL of

nitric acid for preservation, and with 0.5 mL of a 100 g/L sodium sulfite solution for

dechlorination. CNX samples were dosed with 0.1 mL of 0.1 N sulfuric acid for preservation

and with approximately 0.05 mL of freshly prepared 0.142 M ascorbic acid for dechlorination.

Water was poured into the vial until it was very slightly overfilled. If the pH of the unpreserved

sample was anticipated to be high (9 to 10), additional acid was added to achieve the desired pH

of 2.0 to 3.0. Care was taken not to overflow the vials containing reagent. A Teflon septum was

placed on the vial and affixed with a plastic screw cap, head-space-free.

These head-space-free samples were placed in a 4 C refrigerator until analyzed or

shipped. Samples for trihalomethane analysis were stored for up to 28 days. Samples for

haloacetic acid analysis were stored for up to 9 days. Samples for CNX and DOX analysis were

immediately shipped via next-day-air in coolers containing blue-ice to ensure that they remained

chilled.


Ascorbic acid and sodium sulfite dechlorination agents were mixed immediately before

use and were not stored. Bottles were washed using the procedure described above. Vials were

baked for 12 or more hours at 550 C.

DISINFECTION BY-PRODUCT ANALYSIS

Overview

THMs were measured by the liquid-liquid extraction methods of Henderson et al. (1976).

HAAs were measured by microextraction at pH 0.5 with methyl tert-buty\ ether (MTBE) and

24

methylation with diazomethane (Krasner et al. 1989b; Barth and Fair 1992). A J&W DB1701

(Folsom, Calif.) capillary column with an electron capture detector was used in gas

chromatographic analysis of THMs and HAAs. DOX was measured with Standard Method

5320B (APHA et al. 1992). CNX was measured using the micro-liquid-liquid-extraction method

of Sclimenti et al. (1994). Bromide was measured by ion chromatography (Kuo et al. 1990).

Trihalomethanes

Methodology

Trihalomethanes were extracted from water with pentane. Trichloroethene (TCE) at an

approximate concentration of 0.7 mg/L pentane was used as the internal standard for gas

chromatagraphic (GC) analysis. Samples were stored in 42-mL nominal vials at 4 C and taken

from cold storage immediately prior to extraction. Only Pierce 42-mL vials were used for the

THM samples taken in Austin, to ensure consistent volume.

Two mL of pentane containing internal standard was taken up in a 5-mL or 3-mL glass

syringe. The sample vial was held upside down, and a syringe needle was inserted through the

Teflon septum, penetrating less than 0.25 inches (0.6 cm), to provide an outlet for displaced

water. Standard pentane was then injected into the vial. The needle of the pentane syringe was

fully inserted, to approximately 1.5 inches (4 cm), while the pentane was injected. After

injection of pentane, the syringe and syringe needle were removed, and vials were placed upside

down in a rack to minimize contact of the organic layer with the punctured septum.

After all the samples were injected with pentane, they were shaken for one hour at a

moderate speed on a horizontal shaker table. Finally, the organic layer was removed from the

vial with a sterile disposable glass pipette and placed in a 1.5-mL GC vial. The GC vial was

capped with a Teflon septum. The vials were placed in a 4 C refrigerator or in a -10 C freezer

depending upon the length of delay before GC analysis. Vials were stored up to one week in the

freezer.

25

Gas chromatographic analysis was performed on a Hewlett Packard (Avondale, Pa.)

5 890A GC equipped with an automatic sampler. For trihalomethanes, a 30-m J&W 1701 fused

silica capillary column with a film thickness of 0.25 mm was used. One uL of sample was

injected; three injections were made for each sample. The initial oven temperature was 70 C for

10 minutes, followed by a 10 C/minute ramp to a maximum temperature of 130 C. Retention

times varied slightly from run to run, so before performing analyses for a given experiment the

100 ng/L standard was analyzed. Separation was good for all peaks.

Quality Assurance/Quality Control

Aqueous standards were extracted and analyzed in the same manner as the samples to

compensate for extraction efficiency. TCE at an approximate concentration of 0.7 mg/L pentane

was used as the internal standard. The ratio of the area of the peak of interest to the peak of the

internal standard was used to quantify concentration.

A five-point standard curve was run with every GC run to eliminate the effect of possible

equipment operating condition variations. The standard concentrations ranged from 1.0 to 20

Hg/L for SDS samples. The standard concentrations ranged from 5.0 to 100 (j.g/L for FP samples.

Typical calibration curves for chloroform achieved a correlation coefficient of 0.990 or better.

Typical calibration curves for the other three compounds achieved a correlation coefficient of

0.998 or better.

Haloacetic Acids

Methodology

Haloacetic acid analysis was performed following the microextraction procedure of Barth

and Fair (1992). This method is similar to Standard Method 6233B (APHA et al. 1992). The

method consists of a series of steps: extraction of acids into ether from water at high ionic

26

strength, followed by esterification of acids with diazomethane to aid in GC identification of

species. Sample water was prepared and stored as described above. Samples were taken from

cold storage immediately prior to extraction. Diazomethane (DAM) was produced immediately

before sample extraction via Standard Method 6233B (APHA et al. 1992) and stored at -70 C

until needed. The DAM storage vial was placed in a weigh boat filled with water, which then

froze. The ice thus formed ensured that the DAM would remain cold after removal from the

freezer, during use.

A 30-mL aliquot of water was taken from the 42-mL sample vial with a 30-mL glass

syringe and transferred to a clean 42-mL vial. Three grams of copper sulfate, 12 g of baked

sodium sulfate, 1.5 mL of concentrated sulfuric acid and 3.0 mL of MTBE were then added to

the vial. The vial was capped, immediately shaken rapidly by hand for 45 seconds, capped with

a Teflon lined septum and placed upside down in a rack. When all sample vials had been treated

in this way, they were placed on a high speed shaker table for 9 minutes. The samples were then

allowed to stand quiescently for 3 minutes to allow separation of the aqueous and organic layers.

Exactly 2.0 mL of the ether layer was transferred from the sample vial to a thick walled

3-mL reaction vial using a 3-mL or a 5-mL glass syringe. The reaction vials were placed in

a -10 C freezer for 7 minutes to chill. When the vials were completely chilled, both the vials and

freshly prepared diazomethane were removed from the freezer. Using a 1-mL Eppendorf pipette,

0.250 mL of cold diazomethane was added to each reaction vial to esterify the acids. The vials

were then placed in the 4 C refrigerator to react for 15 minutes. After reaction, the vials were

removed and the excess diazomethane was quenched with 0.2 mg of silica gel. The MTBE

containing the esterified acids was transferred to 1.5-mL GC vials using sterile glass pipettes.

These samples were analyzed immediately.

Gas chromatographic analysis was performed on a Hewlett Packard 5 890A GC equipped

with an automatic sampler. For HAAs, a 30-m J&W 1701 fused silica capillary column with a

film thickness of 0.25 mm was used. Four uL of sample was injected, and three injections were

made for each sample. The initial oven temperature was 37 C for 14 minutes, followed by a

27

10 C/minute temperature ramp to a temperature of 70 C. A temperature of 70 C was held for 11

minutes, followed by a 10 C/minute temperature ramp to a temperature of 200 C. Good

separation was found for all peaks. In natural waters, the chromatograms had a great deal of

noise, producing some interfering peaks.

Quality Assurance/Quality Control

Aqueous standards were extracted and analyzed in the same manner as the samples to

compensate for extraction efficiency. 1,2-dibromopropane (1,2-DBF) was used as the internal

standard. The ratio of the area of the peak of interest to the peak of the internal standard was

used to quantify concentration.

A five-point standard curve was run with every GC run to eliminate the effect of possible

equipment operating condition variations. The standard concentrations ranged from 1.0 to 20

ug/L for SDS samples. The standard concentrations ranged from 5.0 to 100 u^g/L for FP samples.

Typical calibration curves for MCAA had a correlation coefficient of 0.98 or better. Typical

calibration curves for the other five compounds achieved a correlation coefficient of 0.998 or

better.

Dissolved Organic Halogen

Methodology

Dissolved organic halogen (DOX) is a group parameter that measures "all" of the

halogen-substituted organic compounds in a sample. DOX was analyzed using a Mitsubishi

Chemical Industries Total Organic Halogen Analyzer Model TOX-10 (currently distributed by

Cosa Instruments, Norwood, N.J.). The concentration of dissolved organic halogen was

determined by Standard Method 5320B (APHA et all992).

The general procedure was as follows. First, a 50-mL water sample was automatically

fed at a constant rate through two columns packed with activated carbon produced specifically

for this purpose. The columns were transferred to a washing channel and washed with a 5 g/L as

nitrate solution to desorb the inorganic halide ions adsorbed. The columns were

28

subsequently analyzed for DOX content using microcoulometric titration. A determination was

deemed acceptable if less than 10 percent of the total DOX was recovered from the second

column in series.

A 10 fig C17L 2,4,6-trichlorophenol standard was tested twice with recoveries of 83.4

percent and 91.3 percent, respectively. This gives an indication of the method detection limit.

Each DOX sample was analyzed twice. If the sample values deviated from each other by 10

ug/L or more, a third DOX determination was performed on the duplicate sample bottle. The

DOX concentrations reported were the average of replicate samples.

Before conducting the DOX experiments, the recoveries of the various DBFs of interest

in the DOX analysis were measured in control studies. The results are presented in Table 4.1.

The stock solutions were prepared by dissolving an exactly weighed amount of one specific DBF

in deionized (DI) water. All standard solutions were prepared by the appropriate dilutions of

stock solution with DI water. Adequate recoveries in most of the DOX analyses were found,

thus justifying the use of this analysis as an indicator of a broad spectrum of DBFs. Low

recoveries could be caused by poor adsorption on the activated carbon or by loss during the

nitrate-wash step in the analysis.


Two different sets of tests were conducted to evaluate the performance of the DOX

determination. One consisted of eight replicates of a City of Houston tap water sample (Table

4.2). This gave a measure of the precision of the test.

To ensure that the equipment was performing properly, each day a standard of 49.9 jag

C17L of 2,4,6-trichlorophenol in DI water was analyzed. This indicated whether or not the

analysis was "in control" that day. In addition, sample activated carbon blanks were tested

frequently. The results of these tests (Table 4.3) indicate the general reliability of the DOX test.

29

Table 4.1

Recoveries of individual DBFs in the DOX analysis

Haloacetic Acids

Formula Weight

Weight of Compound in Stock, mg/lOOmL

mmole Compound/L

mmoleX/L

Standard solution*, nmol X/L

DOX, ugC17L(Test-l)

DOX, umol/L

Recovery

DOX, MgCf/L (Test-2)

DOX, ujnol/L

Recovery

DOX, MgCl"/L (Test-3)

DOX,pmol/L

Recovery

DOX, Mg C17L(Test^)

DOX, nmol/L

Recovery

MCAA

94.50

670.2

70.92

70.92

3.55

19.4

0.55

15.4%

9.2

0.26

7.3%

8.0

0.23

6.4%

9.6

0.27

7.6%

DCAA

128.9

382.0

29.64

59.27

2.96

37.78

1.06

35.9%

33.0

0.93

31.4%

TCAA

163.39

439.0

26.87

80.60

4.03

140.28

3.95

98.0%

141.84

4.00

99.1%

134.72

3.79

94.2%

MBAA

138.9

223.0

16.05

16.05

0.80

21.3

0.60

74.7%

23.36

0.66

82.0%

17.94

0.51

63.0%

DBAA

217.86

384.6

17.65

35.31

1.77

56.28

1.59

89.8%

52.0

1.46

83.0%

52.7

1.48

84.1%

66.56

1.87

106.2%

CyanogenHalides

BCAA CNBr CNC1 CHC1,

173.5 106 61.5 119.5

19.848 100

1.14 8.37

2.29 25.10

4.58 1.42 6.02 1.26

148.5 57.7 213.6 38.1

4.18 1.63 20.1 1.07

91.4% 114.9% 9.4% 85.5%

133.0 44.8 213.6 38.8

3.75 1.26 18.5 1.09

81.9%' 89.2% 8.7% 87.1%

142.4

4.01

87.7%

Trihalomethanes

CHCl2Br CHClBr2

164 208.5

100 100

6.10 4.80

18.29 14.39

0.91 0.72

30.0 24.7

0.85 0.70

92.4% 96.7%

30.1 23.3

0.85 0.66

92.7% 91.2%

CHBr,

253

100

3.95

11.86

0.59

21.2

0.60

95.0%

20.0

0.56

95.0%

Mean Recovery

Standard Deviation

Coefficient of Variation

9.2%

4.2%

45.7%

33.6%

3.2%

9.6%

97.1%

2.6%

2.7%

73.2%

9.6%

13.1%

90.8%

10.7%

11.8%

87.0% 102.0% 9.1% 86.3%

4.8% 18.2% 0.5% 1.1%

5.5% 17.8% 5.4% 1.3%

92.5% 94.0%

0.2% 3.9%

0.2% 4.1%

95.0%

0.0%

0.0%

X = halide*20,000; 1 dilution of stock solution, except for BCAA, which was a 500:1 dilution; standard solutions of CNCI and CNBr were prepared directly

30

Table 4.2

Results from replicates of the same City of Houston tap water sample

Test Number

1

2

3

4

5

6

7

8

Mean Value

Standard Deviation


DOX Concentration, ug C17L

145.5

158.8

148.8

177.8

156.3

149.7

155.9

156.1

156.1

9.9

6.3%

Cyanogen Halide (CNX)

Methodology

Materials used. The extraction solvent used was MTBE (OmniSolv; EM Science,

Gibbstown, N.J.). The Na2SC>4 was from J. T. Baker, Inc. (Jackson, Tenn.), and the sulfuric acid

(H2SO4) was American Chemical Society (ACS) reagent grade from Fisher Scientific Co.

(Pittsburgh, Pa.). The "dechlorinating/dechloraminating agent" was 1-ascorbic acid from Sigma

Chemical Co. (St. Louis, Mo.). The methanol for stock standard solutions was GC-GC/MS

solvent from Burdick & Jackson (Muskegon, Mich.).

31

Table 4.3

Variation in DOX determination with time

ExperimentDate

10/3/9310/4/9310/11/9310/12/9310/25/9310/26/9311/15/931 1/22/9311/29/9311/30/9312/6/93

12/13/9312/14/931/10/941/17/941/24/941/25/942/8/94

2/1 1/942/23/948/9/94

10/11/9510/12/9510/19/9511/16/9512/17/951/27/952/26/953/26/95

Mean ValuesStandardDeviation


DOX Blank ValueGig as CD

0.550.470.510.440.460.300.450.390.360.350.420.330.360.300.500.440.260.330.450.290.300.280.430.500.520.410.370.460.520.41

0.08

19.51%

Concentration of DOX in Standard(ugCr/L)

NRNRNRNRNRNR95.888.2NR93.8NR93.6NR

104.8NR89.3NR10298.092.691.4100.6102.888.597.892.396.791.2102.095.6

5.2

5.5%

NR = Not run

32

Table 4.4 outlines the source and physical information for the analytes. The reference

internal standard used, 1,2-DBP, was 98% pure (Chem Services, Inc., West Chester, Pa.). The

internal standard was added at the 100 mg/L level in the MTBE used for extraction. The reagent

water used for preparation of procedural standards was made in the laboratory by an organic-

pure water (OPW) system (Milli-Q UV Plus Ultra-Pure; Millipore Corp., Bedford, Mass.). The

source water for the OPW system was purified laboratory water (Super-Q) that had been

subjected to several stages of cartridge-type purification to filter and demineralize the water and

trap the organic compounds. The OPW was prepared daily or as needed, as storage can increase

the opportunity for contamination from laboratory solvents, etc.

Stock standard solutions. Primary stock solutions were prepared gravimetrically in

methanol from pure compounds. Separate primary stock solutions were prepared for CNC1 and

CNBr. CNC1 is available as a pure gas, whereas CNBr was obtained commercially as a solid

(CNC1, however, may also be purchased as a dilute solution). The primary stock solution for

CNC1 was prepared by measuring 15 mL of pure gas into a gas-tight syringe. (This step must be

performed in a fume hood, ideally in a chemical containment room, as CNC1 is a highly toxic

gas.) This volume was then injected immediately into the head space of a freezer-cooled

(-10 C), septum-sealed, and tared 10-mL volumetric flask containing 8 mL of methanol. The

volumetric flask was inverted several times to dissolve the gas and then weighed to determine

Table 4.4

CNX analytical standards

Compound

Cyanogen Chloride

Cyanogen Bromide

Source Purity (%)

Island* 99.5

Aldrichf 97

Molecular

Weight

61.47

105.93

Boiling

Point ( C)

13.8

61-62

Density

(g/cm3 )

1.186

2.015

* Island Pyrochemical Industries, Great Neck, NY

t Aldrich Chemical Company, Inc., Milwaukee, WI

33

the concentration. The CNC1 primary stock solution was diluted to final volume with methanol,

sealed, and mixed by inverting the flask several times. The final concentration of this primary

stock solution varied between 1 and 2 mg/mL.

The primary stock solution for CNBr was prepared by weighing out an appropriate

amount of the pure compound into a tared, 10-mL, glass-stoppered volumetric flask containing 8

mL of methanol so that the final concentration was approximately 10 mg/mL. The CNBr

primary stock solution was diluted to final volume with methanol, stoppered, and mixed by

inverting the flasks several times. Each of the CNX primary stock solutions were then

transferred to clean, 15-mL, amber-glass storage bottles, with Teflon-faced septa and screw caps,

and stored at 4 C. These primary stock solutions were prepared fresh every 3-6 months.

A secondary standard solution used for procedural standards and matrix spikes was

prepared by diluting the appropriate amount of each primary stock solution into 1.0 mL of

methanol so that the resulting concentration of each analyte was approximately 30 mg/L. This

secondary standard solution was prepared weekly or as needed.

Analytical procedure. The head-space-free samples were extracted as soon as possible

after collection because of the CNBr's instability. Typically, the samples were extracted upon

receipt at the laboratory. No samples more than 48 hr old were analyzed. Resampling and

reanalysis were required if the sample holding time was exceeded. A 30-mL sample aliquot was

extracted after addition of 10 g of Na2SO4 and 4 mL of MTBE. The sample was shaken in a

mechanical shaker (Eberbach Corp., Ann Arbor, Mich.) for 10 min on a fast setting. The layers

were allowed to separate, and the MTBE layer was transferred to two 1.5-mL autosampler vials

and stored at 4 C. The extracts were then analyzed on the GC/ECD.

Gas chromatography. The extracts were analyzed on a GC (model 3600; Varian

Instrument Group, Sunnyvale, Calif.) installed with a septum-equipped, programmable-

temperature injector (SPI model 1093; Varian), ECD, and autosampler (model 8100; Varian).

The analytical column used was a Dura-bond (DB) 624 fused silica capillary column (J&W

Scientific, Folsom, Calif.) with a film thickness of 1.8 mm, an internal diameter of 0.32 mm, and

a length of 30 m. This thick-filmed column, designed for VOCs, was needed to obtain baseline

resolution of all the analytes. A constant-current, pulse-modulated, nickel-63 (63Ni) ECD with a

standard-size cell was used for detection.

34


Aqueous procedural standards were extracted and analyzed in the same manner as the

samples in order to compensate for extraction efficiency. Quantitation was accomplished using

an external standard calibration curve. Additional calibration utilizing the internal standard was

found unnecessary. The internal reference standard, 1,2-DBP, was used only to monitor the

performance of the autosampler injections. The calibration standards ranged from 0.5 to 20 ug/L

for both CNXs. Typical calibration curves for both compounds, using a best-fit polynomial,

achieved a coefficient of determination (R2) of better than 0.999 for each compound.

The method detection limits for CNC1 and CNBr were 0.13 ug/L and 0.26 |ag/L,

respectively. The mean recovery for matrix spikes was 98.6% for CNC1 and 100% for CNBr.

The normalized difference duplicate analyses ranged between 0.1 and 19% for CNC1 and 0 and

19% for CNBr.

Bromide Ion

Methodology

The bromide ion concentration was measured by chemically suppressed ion

chromatography (1C) with conductivity detection. USEPA Method 300.0 (USEPA 1993) was

followed except for the separator columns and eluant. A Dionex (Sunnyvale, Calif.) AS9-SC

analytical column using 22 mM HsBOs with 22 mM ^28407 was used.


The method detection limit (MDL) was 0.01 mg/L. The precision was 4 % at the 0.05

mg/L concentration.

35

OTHER ANALYTICAL METHODS

Total organic carbon (TOC) was measured following Standard Method 5310 (APHA et

al. 1992). Alkalinity was measured with Standard Method 2320 (APHA et al. 1992). Turbidity

was measured using Standard Method 2130 (APHA et al. 1992). The pH of various solutions

and samples was determined using Standard Method 4500-H+ B (APHA et al. 1992).

36

CHAPTER 5 CONTROLLED BATCH STUDIES WITH PREFORMED CHLORAMINES—TASK la

OBJECTIVES

A portion of the first research task consisted of a series of batch experiments conducted

on the three primary water sources: Lake Austin Water (LAW), Lake Houston Water (LHW),

and California State Project Water (CSPW). Experiments were conducted sequentially on each

water source. The batch experiments screened a wide variety of treatment conditions to identify

conditions that promote DBP formation. Of particular interest were the interrelationships among

total residual concentration, residual speciation, chlorine to nitrogen mass ratio, pH, and the

concentration of bromide as they affected the production of the 12 measured DBFs and DOX.

The results of these experiments also aided in the selection of operating conditions for pilot plant

studies and in the selection of appropriate water utilities across the country for sampling.

EXPERIMENTAL APPROACH

The batch experiments were performed at the University of Texas, using one large

sample of water from each source, except for Lake Houston, where two samples were collected.

Collection of 250 L of water occurred during periods of typical raw water quality. The water

was shipped as rapidly as possible and stored at 4 C prior to testing in the various batch

experiments. The experiments were conducted directly on the raw water, so that the maximum

DBP precursor concentrations were present to simulate worst case conditions.

The major variables were TOC concentration, bromide concentration, chloramine dose,

pH and Cla/N ratio. For any given water, the TOC concentration was constant, leaving four

variables to study. Each variable was studied at different levels to establish its importance in

DBP formation. To avoid confounding effects from imperfect mixing, the experiments were

conducted with preformed chloramines. The matrix of experimental conditions is outlined

below.

Three levels of pH were studied to cover the range of current practice. Similarly, three

C12/N ratios were studied to span the broadest possible range of operation in practice. Three

37

chloramine doses were selected to provide the target residual concentrations after 48 hours of

incubation at 20 C. The target concentration of 1 mg/L is typical of current practice, while the

two larger concentrations were selected to examine the importance of disinfectant concentration

in DBF formation. Two levels of bromide concentration were studied, the ambient concentration

and the ambient concentration plus 0.5 mg/L. The added bromide produced a fairly large

concentration to provide some indication of the importance of bromide in DBF formation during

chloramination. These experiments represent a 2x3x3x3 matrix, resulting in 54 experimental

conditions for each water (Table 5.1).

The batch experiments were conducted in 1-L amber glass bottles. The bottles were

partially filled with raw water, chemical conditions were adjusted to the desired level, and the

bottles were dosed with a concentrated stock solution of preformed chloramines and then filled

completely with water to slightly overfull. This final addition of water provided good mixing in

the bottles, as demonstrated by dye tests. The bottles were capped with Teflon-lined septa. Two

replicates were used for each condition. At the completion of the incubation period, the TTHM

and residual disinfectant concentrations (free and combined chlorine) were measured in each

replicate; however, the DOX concentration was not always measured in both replicates because

of the time-consuming nature of the DOX test. If the duplicate DOX measurements from the

first replicate agreed, the other replicate was not analyzed.

TTHMs were measured to quantify DBFs of current regulatory concern, while DOX was

measured as an indicator of a broad spectrum of DBFs. In addition, HAA and CNX concen

trations were measured on selected samples for each water. All HAA and CNX analyses were

Table 5.1

Parameter values for matrix of experimental conditions

Parameter Studied Values

~pti 6, 8, or 10

Chlorine/nitrogen ratio 3/1, 5/1, or 7/1

Total residual (mg/L) 1,2, or 4

Bromide added 0 or 0.5 mg/L

38

performed on samples having a nominal 2 mg/L disinfectant residual. In general, HAA and

CNX analyses were performed at all three pH values, ambient bromide levels and both the 3/1

and 7/1 Cfe/N ratios to survey a broad range of conditions. HAA analyses were also performed

on selected samples that had bromide addition to study the impact of bromide on HAA

speciation. CNX analyses also were performed for LHW and CSPW on samples that had

bromide addition to study the formation of cyanogen bromide. Again, all three pH values and

the 3/1 and 7/1 Cfe/N ratios generally were sampled.

SOURCE WATER QUALITY

As noted above, one "batch" each of LAW and CSPW was used for all LAW and CSPW

experiments. Because dosing with the proper amount of chlorine to achieve the target total

residual was quite difficult for LHW, the first batch was exhausted before this task was

completed, so a second batch of LHW was collected to complete the study. The quality of these

four batches of water is summarized in Tables 5.2 to 5.5. Formation potentials for DOX, THMs,

and HAAs are reported, along with typical water quality parameters. The formation potentials

are shown on both a mass and molar basis so that the fraction of the DOX accounted for by

THMs and HAAs could be calculated.

Influence of Total Residual

In an effort to identify the key variables, all four of the variables studied in this project

were examined for LHW (low in bromide ion concentration). The concentrations of TTHM and

DOX after 24 hours of incubation under various conditions show that changing the total residual

from a nominal value of 1 mg/L to a nominal value of 4 mg/L had a minor influence on the

concentration of these two parameters (Figures 5.1 to 5.6). Because these same data in the other

two primary waters tested behaved similarly, in the remainder of the report, only data collected

at a nominal total residual concentration of 2 mg/L is discussed. This allows the interplay of

C12/N ratio, pH and bromide ion concentration to be displayed in individual graphs, making

comparisons of the data easier.

39

Table 5.2

Quality of Lake Austin Water collected on 9/17/93

Parameter ConcentrationTOC, mg/L

Bromide, mg/L

DOXo, ug Cl/L

Free Chlorine Demand, mg/L

pH

Turbidity/

Alkalinity, mg CaCCb/L

DOXFP4THMFP4

CHC13

CHBrCl2

CHBr2Cl

CHBr3

THMFP

TTHMX

HAAFP4

MCAA

DCAA

TCAA

MBAA

DBAA

BCAA

HAAFP

THAAX

DBPXFP

Percent of DOXFP4

3.1

0.24

6.8

4.1

8.1

0.53

156

pH

Hg/L

839.5

21.6

36.1

32.4

3.9

94.0

3.5

18.0

34.6

28.6

12.4

0.0

97.1

6

Hmole/L

23.65

0.18

0.22

0.16

0.02

0.57

1.72

0.04

0.14

0.21

0.21

0.06

0.00

0.65

1.27

2.99

12.6

PH

ug/L

647.5

29.4

42.4

50.3

9.4

131.5

1.4

19.2

31.9

25.9

15.0

0.0

93.4

8

(imole/L

18.24

0.25

0.26

0.24

0.04

0.78

2.35

0.01

0.15

0.20

0.19

0.07

0.00

0.61

1.22

3.57

19.6

pH

Hg/L

524.0

46.5

61.0

68.4

22.7

198.6

1.6

18.1

28.0

26.5

21.2

0.0

95.4

10

umole/L

14.76

0.39

0.37

0.33

0.09

1.18

3.54

0.02

0.14

0.17

0.19

0.10

0.00

0.62

1.20

4.74

32.1

Note: "0" is concentration at time of sampling, "4" indicates after a 4-day incubation period

40

Table 5.3

Quality of Lake Houston water

Parameter

collected on 10/28/93

ConcentrationTOC, mg/L Bromide, mg/L DOX0, ug Cl/L Free Chlorine Demand, mg/L PH TurbidityAlkalinity, mg CaCO3/L

DOXFP4THMFP4

CHC13CHBrCbCHBr2ClCHBr3THMFPTTHMX

HAAFP4MCAADCAATCAAMBAADBAABCAAHAAFPTHAAX

DBPXFPPercent of DOXFP4

9.2 0.08 17.5 14.9 7.4 5225

PHug/L

IVD

203.236.72.61.4

243.9

10.796.2165.10.00.010.0

282.0

6umole/L

IVD

1.700.220.010.011.945.83

0.110.751.010.000.000.061.934.7510.58

*

PHug/L

IVD

291.350.74.00.0

346.0

12.1121.8147.00.00.014.5

295.4

8umole/L

IVD

2.440.310.020.002.778.30

0.130.940.900.000.000.082.064.8813.18

*

pHug/L

IVD

444.262.55.90.0

512.6

6.9123.162.40.00.015.1

207.5

10umole/L

IVD

3.720.380.030.004.1312.38

0.070.960.380.000.000.091.503.3015.68

*

Note: "0" is concentration at time of sampling, "4" indicates after a 4-day incubation periodIVD = invalid data* Cannot be calculated because DOXFP4 data were invalid

41

Table 5.4

Quality of Lake Houston water collected on 2/22/94

Parameter Concentration

TOC, mg/L

Bromide, mg/L

DOXo, ug Cl/L


Turbidity

Alkalinity, mg CaCO3/L

DOXFP4THMFP4

CHC13

CHBrCb

CHBr2Cl

CHBr3

THMFP

TTHMX

HAAFP4

MCAA

DCAA

TCAA

MBAA

DBAA

BCAA

HAAFP

THAAX

DBPXFPPercent of DOXFP4

6.7

0.075

35.7

12.3

56

46.8

pHHg/L

2513

186.5

27.2

2.8

0.3

216.8

1.3

110.2

208.6

0.0

0.0

15.4

335.5

6umole/L

70.8

1.56

0.17

0.01

0.00

1.74

5.22

0.01

0.85

1.28

0.00

0.00

0.09

2.23

5.73

10.9515.5

pHHg/L

2125

313.1

46.5

3.8

0.3

363.7

15.9

163.7

201.0

0.0

0.0

23.7

404.3

8umole/L

59.9

2.62

0.28

0.02

0.00

2.92

8.77

0.17

1.27

1.23

0.00

0.00

0.14

2.80

6.67

15.4425.8

pHlig/L

1158

61.0

68.4

22.7

152.1

16.7

131.9

58.3

0.0

0.0

20.9

227.8

10umole/L

32.6

0.00

0.37

0.33

0.09

0.79

2.37

0.18

1.02

0.36

0.00

0.00

0.12

20.90

3.53

5.9118.1


42

Table 5.5

Quality of California State Project water collected on 12/9/93

Parameter Concentration

TOC, mg/L

Bromide, mg/L

DOXo, ug Cl/L


PH

Turbidity

Alkalinity, mg CaCO3/L

DOXFP4

THMFP4

CHC13

CHBrCl2

CHBr2Cl

CHBr3

THMFP

TTHMX

HAAFP4

MCAA

DCAA

TCAA

MBAA

DBAA

BCAA

HAAFP

THAAX

DBPXFP

Percent of DOXFP4

2.4

0.103

2.5

5.3

7.6

0.5

73

pH

ug/L

365.5

65.2

55.4

24.0

16.0

160.6

0.0

21.3

40.4

0.0

0.0

12.8

74.5

6

umole/L

10.29

0.55

0.34

0.12

0.06

1.06

3.19

0.00

0.17

0.25

0.00

0.00

0.07

0.49

1.22

4.41

42.8

pH

Hg/L

375.4

121.7

87.8

46.0

3.8

259.3

0.0

30.9

25.0

0.0

0.0

18.4

74.3

8

(amole/L

10.57

1.02

0.54

0.22

0.02

1.79

5.37

0.00

0.24

0.15

0.00

0.00

0.11

0.50

1.15

6.52

61.7

pH

Hg/L I

398.6

176.4

70.2

41.3

7.6

295.5

8.3

25.7

5.8

0.0

0.0

15.7

55.5

10

imole/L

11.23

1.48

0.43

0.20

0.03

2.13

6.40

0.09

0.20

0.04

0.00

0.00

0.09

0.41

0.77

7.17

63.9


43

PH

0.5

mg/

L Br

omid

e A

dded

Figu

re 5

.1

Lak

e H

oust

on w

ater

che

mis

try

expe

rim

ents

: 2-

d T

TH

M f

orm

atio

n at

a C

12 to

N r

atio

of 3

to

1

Am

bien

t Bro

mid

e (0

.08

mg/

L)

Not

e ch

ange

of s

cale

for

"z"

axis

300

b 25o

f

200

1

150

100 50 0

I I

PH

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g/L)

Figu

re 5

.2 L

ake

Hou

ston

wat

er c

hem

istry

exp

erim

ents

: 2-d

DO

X fo

rmat

ion

at a

C\2

to N

ratio

of 3

to 1

ON

PH

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g.L)

Figu

re 5

.3 L

ake

Hou

ston

wat

er c

hem

istr

y ex

perim

ents

: 2-

d T

TH

M f

orm

atio

n at

a C

12 to

N ra

tio o

f 5 to

1

§ '

PH

0.5

mg/

L B

rom

ide

Add

ed

PH

Am

bien

t Bro

mid

e ( 0

.08

mg/

L)

Figu

re 5

.4 L

ake

Hou

ston

wat

er c

hem

istry

exp

erim

ents

: 2-

d D

OX

for

mat

ion

at a

Ch

to N

rat

io o

f 5 to

1

OO

PHPH

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g/L

)

Figu

re 5

.5

Lak

e H

oust

on w

ater

che

mis

try

expe

rim

ents

: 2-

d TT

HM

for

mat

ion

at a

Cb

to N

rat

io o

f 7 to

1

8

10PH

11

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g/L

)

Figu

re 5

.6 L

ake

Hou

ston

wat

er c

hem

istr

y ex

perim

ents

: 2-

d D

OX

for

mat

ion

at a

Cb

to N

ratio

of 7

to 1

INFLUENCE OF pH, C12/N MASS RATIO, BROMIDE ION

Residual Species—Monochloramine/Dichloramine

Figure 5.7 shows the dichloramine to total residual ratio after 48 hours in LAW.

Appreciable dichloramine concentrations were observed only at pH 6. At pH 8 and 10, either

very little dichloramine was formed or it decomposed before the 48-hour measurement. As

expected, the dichloramine to total residual ratio increased with increasing Ch/N ratio. When the

water was spiked with bromide, the dichloramine to total residual ratio decreased at all chlorine

to nitrogen ratios. Considering that chloramines were first formed in bromide-free water and

then samples were dosed with the solution of preformed chloramines, the implication is that free

chlorine and dichloramine were consumed in reactions with bromide. The total chlorine demand

of the water was greater with bromide addition, which provides additional evidence of reactions

with bromide and suggests that the brominated species decomposed before the 48-hour

measurement, as expected. Presumably, chloramine hydrolysis and decomposition (to yield free

chlorine and subsequently free bromine), bromide substitution into the chloramines, or both

would be the mechanisms for bromamine production under such conditions. The further

implication is that more bromine substitution of organic matter will occur as the bromide

concentration increases.

The dichloramine to total residual ratio after 48 hours in LHW (Figure 5.8) was similar to

LAW in that appreciable concentrations were observed only at pH 6. LHW, however, showed a

much smaller decrease in dichloramine concentration in response to bromide addition than did

LAW. This dampened response suggests that less formation of free and combined bromine may

have occurred in this water. It is unclear whether the difference between the two waters is

attributable to differences in inorganic or organic chemistry. LHW has more TOC and much less

alkalinity/hardness as compared with LAW (Table 5.2 to 5.4).

The effect of bromide on the dichloramine to total residual ratio in CSPW (Figure 5.9)

was similar to that observed in Lake Austin, especially at Ch/N ratios of 7/1 and 5/1. This is

again suggestive of significant formation of free or combined bromine. The TOC in CSPW is

similar to that of LAW, and the alkalinity is intermediate between LHW and LAW. Thus, the

data suggest that either a high TOC concentration or low alkalinity "stabilizes" the dichloramine

50

0.5

mg/

L B

rom

ide

Add

ed

Am

bien

t Bro

mid

e (0

.24

mg/

L)

Figu

re 5

.7 L

ake

Aus

tin w

ater

, bat

ch s

tudi

es, d

ichl

oram

ine

resi

dual

s as

a p

erce

ntag

e of

tota

l res

idua

l as

a fu

nctio

n of

Cfe

/N

ratio

and

pH

at a

tota

l res

idua

l chl

orin

e of 2

mg/

L

to

•—

Q.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g/L

)

Figu

re 5

.8 L

ake

Hou

ston

wat

er, b

atch

stu

dies

, dic

hlor

amin

e re

sidu

als

as a

per

cent

age

of to

tal r

esid

ual a

s a

func

tion

of C

fe/N

ratio

and

pH

at a

tota

l res

idua

l chl

orin

e of

2 m

g/L

u>

11'

0.5

mg/

L B

rom

ide

Add

ed

of C

12/N

ratio

and

PH

at a

tota

l res

idua

l chl

orin

e of

2 m

g/L

Am

bien

t Bro

mid

e (0

.10

mg/

L)

as a

fraction in the presence of bromide. Hand and Margerum (1983) and Jafvert and Valentine

(1992) note that the rate of dichloramine decomposition accelerates in the presence of carbonate.

Therefore, the low alkalinity in LHW may account for the greater stability of dichloramine in the

presence of bromide. The greater stability of the preformed dichloramines would lead to less

decomposition and less free chlorine production, a decomposition product. In turn, less free

chlorine would be available to drive bromination reactions through the conversion of bromide to

hypobromous acid.

Total Trihalomethanes and Dissolved Organic Halogen

Lake Austin Water

THM production followed the general trend of decreasing with increasing pH, as shown

in Figure 5.10. This trend is consistent with the premise that dichloramine is active in producing

THMs and is the opposite of that found in chlorination, where base-catalyzed THM formation

mechanisms are favored. Addition of bromide significantly increased the TTHM concentration

at pH 6 and increased it slightly at higher pH. In general, the Cb/N ratio of 5/1 produced the

largest TTHM concentrations. These concentrations, however, were considerably less than the

current and anticipated drinking water MCLs.

The speciation of the THMs is presented in Figure 5.11. The value of "n" on the ordinate

indicates the degree of bromine substitution of the THMs; a value of 3 indicates that only

bromoform is present, while a value of 0 indicates that only chloroform is present. No data are

reported for pH 10 and for pH 8 at the 3/1 C12/N ratio because the TTHM concentration was

below the detection limit. THMs in LAW were quite brominated even before bromide addition,

but the degree of bromine substitution did increase when bromide was added. Increased bromine

substitution is consistent with the observed decrease in dichloramine and presumed increase in

free or combined bromine concentrations (Figure 5.7). Anomalous results at pH 8, Cb/N ratio of

5/1 are attributable to an unexpectedly large chloroform concentration at the ambient bromide

level. The large chloroform concentration also is reflected in the data presented in Figure 5.10.

54

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.2

4 m

g/L)

n 5

me/

L B

rom

ide

AUUC

U

- f r

i /N

ratio

and

PH

at a

nom

inal

tota

l res

idua

lch

lori

ne o

f 2 m

g/L

o

Io ffl

2 -

1 -

O,

C !LJ pH 6, Ambient Br BB pH 8, Ambient Br

E3pH6, Br'added ESS pH 8, Br'added

3to1 5to1 CI2:N Ratio

7to1

Figure 5.11 Degree of bromination of THMs in Lake Austin water

The DOX data (Figure 5.12) give a more complete view of overall DBF formation. Most

of the data follow the general trend of decreasing DBF formation with increasing pH. The key

exception is at pH 8 and a C12/N ratio of 5/1, where a DOX peak occurred with and without

bromide addition. Bromide addition accentuated the production of DOX for nearly all

conditions. Although the DOX analysis cannot differentiate between chlorinated and brominated

organics, the increased production of DOX with bromide addition strongly suggests that

brominated DBFs were formed. Moreover, the DOX measurement underestimates the bromide

impact on a mass basis because it measures all halogens as chloride and because bromide has a

higher molecular weight than chloride.

The DOX data at pH 6 showed some correlation to the dichloratnine concentration

(Figure 5.7). At the ambient bromide concentration, both the DOX concentration and the

dichloramine fraction increased as the C^/N ratio increased, suggesting that dichloramine played

an important role in DOX formation. With bromide addition, the DOX concentration and the

56

300

o o> 3 x o 0

300

250

200

0.5

mg/

L B

rom

ide

adde

dA

mbi

ent B

rom

ide

(0.2

4 m

g/L

)

Figu

re 5

.12

Lake

Aus

tin w

ater

, bat

ch s

tudi

es, D

OX

(ug

C1Y

L) a

s a

func

tion

of C

b/N

ratio

and

pH

at a

nom

inal

tota

l

resi

dual

chl

orin

e of

2 m

g/L

dichloramine fraction again increased as the Cb/N ratio increased; however, their responses

relative to those measured at the ambient bromide concentration differed. The DOX concen

tration with bromide addition was substantially larger at each Cla/N ratio, while the dichloramine

fraction was substantially smaller. These data imply that the addition of bromide caused the

production of brominated species at the expense of dichloramine and that these brominated

species were more reactive with organic matter than the chlorinated species, resulting in a greater

production of DOX.

The peaks in DOX and TTHM concentrations at pH 8 and a Cli/N ratio of 5/1 are

difficult to explain. No dichloramine was present at pH 8 after 48 hours (Figure 5.7), and Jafvert

and Valentine (1992) note that dichloramine decays rapidly at pH 8. Therefore, dichloramine's

role in DOX and TTHM formation was probably much less than at pH 6, where a dichloramine

residual was maintained throughout the incubation period. Other, more reactive chlorinated and

brominated species must have formed. Possibilities include acid-catalyzed reactions with

monochloramine and bromochloramine. NHsCl* is a powerful chlorinating agent and exists in

equilibrium with monochloramine (Snyder and Margerum 1982). Unfortunately, the complexity

of haloamine chemistry at mid-range pH precludes identification of the reactive species without

some more fundamental, highly-controlled experiments, which were beyond the scope of this

work. Although the large peak in DOX concentration at pH 8 might be of some concern, the

results also point to a solution to the problem through modification of the Ch/N ratio. The DOX

concentration was much smaller at both the 3/1 and 7/1 Ch/N ratios. Reasons for the sensitivity

of DOX formation to the Cb/N ratio likewise are not apparent.

Dichloramine was cited above as a likely halogenating agent at pH 6. DBF formation by

NHaCl"1" and acid-catalyzed reactions with monochloramine also may have occurred at pH 6,

although the smaller monochloramine concentration at pH 6, relative to pH 8, may have limited

their influence. Little DBF formation by these mechanisms would be expected at pH 10 because

of the small proton concentration, as illustrated by Snyder and Margerum (1982) in studies with

amines.

58

Lake Houston Water

As with LAW, the TTHM concentrations (Figure 5.13) generally decreased with

increasing pH. The addition of bromide stimulated some additional TTHM production, but the

impact was smaller than in LAW. This is in keeping with the smaller effect of bromide on the

dichloramine to total residual ratio in LHW (Figure 5.8) and the resulting presumption of smaller

free and combined bromine concentrations. A noticeable exception to the general trend occurred

near pH 8 at the 7/1 Cb/N ratio, where a concentration peak was observed, especially with

bromide addition. Even here, however, the TTHM concentration of approximately 40 ng/L was

below current and anticipated regulatory levels. As expected, the addition of bromide increased

the degree of bromine substitution of the THMs (Figure 5.14), but the degree of bromine

substitution was still much smaller than observed in LAW. As with LAW, the smallest value of

n in the presence of added bromide occurred at a Cb/N ratio of 5/1.

The DOX concentration was quite sensitive to the Cb/N ratio and pH and quite

insensitive to the bromide concentration (Figure 5.15). DOX showed even less dependence than

TTHMs on the added bromide. The correlation between dichloramine concentration and DOX

concentration at pH 6 was not nearly as strong as in LAW. The smallest DOX concentration

occurred at the 7/1 Cb/N ratio, which corresponded to the largest dichloramine fraction,

approximately 0.9 (Figure 5.8). These data suggest that species in addition to dichloramine may

be important in DOX formation at pH 6. As was suggested for LAW, NH3C1+ and acid-catalyzed

reactions with monochloramine may be important mechanisms for DBF formation at pH 6.

Thus, the very low concentration of monochloramine at the 7/1 Cb/N ratio may account for the

small DOX formation.

Relatively large DOX concentrations also were observed near pH 8 for the 5/1 and 7/1

Cb/N ratios. As noted above, the maximum TTHM concentration occurred near pH 8 at the 7/1

Cb/N ratio. As with LAW, essentially no dichloramine was measured at pH 8 and 10 after 48

hours; therefore, species other than dichloramine, such as NHsCl+ and acid-catalyzed reactions

with monochloramine, probably played a significant role in DOX formation. The DOX

concentration did decrease considerably near pH 8 at the 3/1 Cb/N ratio. Thus, as with LAW,

59

ON

O

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g/U

O

fcl2

/Nra

,io an

d pH

atan

omin

alto

ta, r

esid

ual

chlo

rine

of 2

mg/

L

c _o

I 2

ICD

0) 0)

0

pH 6, Ambient Br pH 6, Br" added

pH 8, Ambient Br" pH 8, Br" added

Cl3to1 5to1

CI2 :N Ratio7 to 1

Figure 5.14 Degree of bromination of THMs in Lake Houston water

testing of different Cb/N ratios on a water source undergoing chloramination may be warranted

to find a ratio that meets disinfection needs while minimizing DBF production.

California State Project Water

In CSPW, the data, without significant exceptions, followed the general trend outlined

above of lower DBF concentration with increasing pH and decreasing CVN ratio, as shown in

Figure 5.16 for TTHMs and Figure 5.17 for DOX. The increased TTHM and DOX

concentrations with bromide addition are again suggestive of the occurrence of bromine

substitution reactions. The THM speciation data (Figure 5.18) further support the occurrence of

bromine substitution reactions, as the n value increased with bromide addition for all conditions

producing measurable THM concentrations.

61

ON

NJ

300

300

0.5

mg/

L B

rom

ide

Add

ed

Am

bien

t Bro

mid

e (0

.08

mg/

L)

Figu

re 5

.15

Lak

e H

oust

on w

ater

, bat

ch s

tudi

es, D

OX

(ug

C17

L) a

s a

func

tion

of C

12/N

ratio

and

pH

at a

nom

inal

tota

l res

idua

l

chlo

rine

of 2

mg/

L

ON u>

X

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.1

0 m

g/L

)

Figu

re 5

.16

Cal

ifor

nia

Stat

e Pr

ojec

t wat

er, b

atch

stu

dies

, TT

HM

(|ig

/L)

as a

fun

ctio

n of

C12

/N r

atio

and

pH

at a

nom

inal

tota

l

resi

dual

chl

orin

e of

2 m

g/L

120

100

o O) a X o o

20

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.1

0 m

g/L

)

Figu

re 5

.17

Cal

ifor

nia

Stat

e Pr

ojec

t wat

er, b

atch

stu

dies

, DO

X (

ug C

17N

) as

a fu

nctio

n

resi

dual

chl

orin

e of

2 m

g/L

ratio

and

pH

at a

nom

inal

tota

l

« 2 -^

ICDH

O

D)

{§

C



3to1 5to1 CI2 :N Ratio

7to1

Figure 5.18 Degree of bromination of THMs in California State Project water

Haloacetic Acids and Cyanogen Halides

Lake Austin Water

The HAA6 and CNX concentrations for LAW are shown in Figure 5.19. In general, the

concentrations of both classes of chemicals increased as the pH decreased and the Cb/N ratio

increased. The dihalogenated species (DCAA, BCAA, DBAA) were the dominant HAAs. Of

these, DBAA was present at the largest concentration because of the relatively large ambient

bromide concentration (0.24 mg/L). Similarly, the CNBr concentration was greater than the

CNC1 concentration at pH 6 and 8. CNX is unstable at pH 10, so very low concentrations of

both CNBr and CNC1 were observed.

65

12.5 0.

0

Am

bien

t Bro

mid

e (0

.24

mg/

L)

Am

bien

t Bro

mid

e (0

.24

mg/

L)

Figu

re 5

.19

Lak

e A

ustin

wat

er, b

atch

stu

dies

, HA

A6

(ng/

L)

and

CN

X (

ug/L

) as

a f

unct

ion

of C

12/N

rat

io a

nd p

H a

t a

nom

inal

tota

l res

idua

l chl

orin

e of

2 m

g/L

Lake Houston Water

The HAA6 concentrations for LHW are presented in Figure 5.20. The HAA6

concentration was greater than in Lake Austin, reaching levels under some conditions that might

be of future regulatory concern. As with Lake Austin, the HAA6 concentration increased as the

pH decreased and the Cli/N ratio increased. The addition of bromide did not have a large effect

on the HAA6 concentration, but the speciation of HAAs shifted toward the brominated

chemicals. Again, the dihalogenated species dominated, with DCAA present at the largest

concentration under ambient conditions and BCAA at the largest concentration when bromide

was added to the water. The CNX concentrations were also larger than in Lake Austin (Figure

5.21), especially at pH 8 and the 5/1 and 7/1 Cli/N ratios. In the absence of bromide addition,

CNC1 dominated the CNX because of the low ambient bromide concentration in Lake Houston.

With bromide addition, the CNX concentrations increased and CNBr was formed, with CNBr

generally dominating at pH 6 and CNC1 still dominating at pH 8 and 10. Again, low

concentrations of CNX were observed at pH 10, as expected.


The HAA6 concentrations for eight CSPW samples are presented in Figure 5.22. The

trends observed in the other two waters held at pH 6 and 8; the HAA6 concentration increased as

the pH decreased and the C^/N ratio increased. The HAA6 concentrations at pH 10 were larger

than would be expected based on the trends observed in LAW and LHW. The HAA6

concentrations were similar to those observed with LAW and less than those observed in LHW.

The addition of bromide also significantly increased the HAA6 concentration. The three

dihalogenated species dominated the HAAs under ambient conditions (0.10 mg/L Br"), while

BCAA and DBAA were the only HAAs present when bromide was added. The production of

the dihalogenated acetic acids in all three waters indicates that the use of chloramines may not

control these DBFs particularly well. Therefore, dihalogenated acetic acids may be of concern in

some chloraminated waters in meeting anticipated future regulations.

67

50

oo

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g/L

)

Figu

re 5

.20

Lake

Hou

ston

wat

er, b

atch

stu

dies

, HA

A6

(|ag/

L) a

s a

func

tion

of C

12/N

rat

io a

nd p

H a

t a n

omin

al to

tal r

esid

ual

chlo

rine

of 2

mg/

L

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.0

8 m

g/L

)

Figu

re 5

.21

Lake

Hou

ston

wat

er, b

atch

stu

dies

, CN

X (

ng/L

) as

a fu

nctio

n of

Cb/

N ra

tio a

nd p

H a

t a n

omin

al to

tal r

esid

ual

chlo

rine

of 2

mg/

L

2525

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.1

0 m

g/L

)

Figu

re 5

.22

Cal

ifor

nia

Stat

e Pr

ojec

t wat

er, b

atch

stu

dies

, HA

A6

(ug/

L)

as a

func

tion

of C

b/N

rat

io a

nd p

H a

t a to

tal r

esid

ual

chlo

rine

of 2

mg/

L

The CNX (Figure 5.23) was approximately evenly split between CNC1 and CNBr at

ambient conditions, with CNBr dominating when bromide was added. As with the two other

waters, the maximum CNX concentration occurred at pH 8, which suggests that dichloramine is

not the primary species involved in CNX production. Again, NHaCl* and acid-catalyzed

reactions with monochloramine may be more important.

Recovery of Dissolved Organic Halogen With 12 Measured Disinfection By-Products

As noted above, during Task la, certain samples were selected for additional DBF SDS

analyses beyond the SDS THMs and SDS DOX determinations. These selected samples were

also tested for SDS HAA6 and SDS CNC1 and SDS CNBr. Thus, in these samples, after the 48

hours of incubation, 12 DBFs were measured, as well as DOX.

In an effort to determine the qualitative magnitude of the "unknown" halogen-substituted

DBFs that were being formed in these samples, each of the 12 measured DBFs was converted to

umol/L of DOX that it would have contributed to the DOX measurement. The recoveries noted

in Table 4.1 were used in making this calculation. These 12 "DOX equivalencies" were then

summed and compared to the measured DOX concentration. These comparisons are reported as

percentages ((Z 12 Measured DBPOX/DOX) (100)) in Figures 5.24 through 5.26 for the Task la

samples.

The most striking feature of these three figures is that the recovery values are all 35

percent or less, several less than 5 percent. These data tend to be quite variable because of

analytic error in the 12 DBF measurements as well as the analytic error in the DOX

determination. This may be the cause of .the lack of clear trends. In general, the recovery

percentage is lower at the 3/1 Cb/N weight ratio as compared to the 7/1 Cb/N weight ratio.

Recall in the work of Singer et al. (1992) that the slope of the best fit line through the

data was about one-third of the slope of a 100 percent recovery line. Thus, with both free

chlorine and chloramine, a large concentration of "unidentifiable" halogen-substituted DBFs are

formed in the application of these oxidants.

71

to

•W

0.5

mg/

L B

rom

ide

Add

edA

mbi

ent B

rom

ide

(0.1

0 m

g/L

)

Figu

re 5

.23

Cal

ifor

nia

Stat

e Pr

ojec

t wat

er, b

atch

stu

dies

, CN

X (

ug/L

) as

a fu

nctio

n of

C12

/N r

atio

and

pH

at a

tota

l res

idua

l

chlo

rine

of 2

mg/

L

Ambient Bromide (0.24 mg/L) 2 mg/L total residual after 48 hrs.

Figure 5.24 Lake Austin water chemistry experiments: Micromolar percentage of 2-d DOX

identified by summing the 12 measured 2-d DBFs at different pHs and Cla/N ratios

73

Ambient Bromide (0.25 mg/L) 2 mg/L total residual after 48 his.

Figure 5.25 Lake Houston water chemistry experiments: Micromolar percentage of 2-d DOX

identified by summing the 12 measured 2-d DBFs at different pHs and Cb/N ratios

74

gQ

1

II

Ambient Bromide (0.10 mg/L) 2 mg/L total residual after 48 hrs.

Figure 5.26 California State Project water chemistry experiments: Micromolar percentage of

2-d DOX identified by summing the 12 measured 2-d DBPs at different pHs and C^/N ratios

75

CHAPTER 6 CONTROLLED BENCH-SCALE MIXING STUDIES—TASK Ib

OBJECTIVES

The experiments investigated the impact of mixing at the point of ammonia and chlorine

addition on DBF formation. In particular, the relative importance of system chemistry versus

mixing conditions in DBF formation was of interest. Two underlying questions motivated the

design of these experiments. First, can inadequate mixing exacerbate DBF formation under

conditions in which the system chemistry favors DBF formation? Second, can inadequate

mixing cause significant DBF formation under conditions in which the system chemistry leads to

little DBF formation? These questions were investigated in a series of batch mixing experiments

in which chlorine and ammonia solutions were dosed either simultaneously or with a specified

delay in dosing ammonia.


The experiments were conducted in a jar test apparatus at various known values of G

(mean velocity gradient). The main experimental variables were the mixing intensity and the

relative timing in dosing the chlorine and ammonia solutions. Results from the chemistry

experiments were used to select conditions in which mixing intensity may play an important role.

Therefore, a smaller number of conditions were evaluated for each water than in the chemistry

experiments.

The experiments were conducted in 2-L beakers that had Plexiglas baffles installed

according to the pattern of Lai et al. (1975). The calibration curve of Cornwell and Bishop

(1983) was used to calculate G as a function of impeller speed. A correction factor for water

depth was applied based on the formula developed by Cornwell and Bishop (1983). The beakers

were also equipped with two dosing funnels of the design proposed by Hudson (1981) to

reproducibly deliver the chlorine and ammonia dosing solutions to the same location in each

vessel.

7.7

The dosing solutions were delivered to the beakers simultaneously. Simultaneous dosing

was accomplished using an apparatus, shown schematically in Figure 6.1, consisting of an axial

dowel with twelve 20-mL test tubes connected to it. The tubes were connected to a short piece

of bronze pipe with an inner diameter slightly larger than the outer diameter of the dowel. The

bronze pipe was slipped onto the dowel. The connection between the test tube and the pipe was

made near the top of the test tube so that the tubes would be upright when at rest. The test tubes

were affixed to the axial dowel in two batteries of six tubes each, each battery being free to rotate

about the shaft as a group. One set of tubes was used for the chlorine solution, the other for the

ammonia solution. The mouth of each test tube was aligned with one of the funnels when the

tubes were rotated into the pouring position. Thus, when the tubes were filled with the

appropriate solution, upon rotation of the tubes, the solution was discharged from the tubes into

the beakers simultaneously.

The mixing pattern was established in each beaker before the dosing solutions were

applied. Mixing continued for 1 minute after the completion of dosing. Samples were then

transferred rapidly to amber bottles and held for 48 hours at 22 C. As with the chemistry

experiments, the THM and DOX concentrations were measured for all samples at the end of the

incubation period. HAA and CNX concentrations were measured on selected samples. Residual

disinfectant concentration was measured after 48 hours.

A standard jar test apparatus allows six samples to be run simultaneously, with the

mixing intensity the same in each sample. One sample was used as a control and was dosed with

preformed chloramines; therefore, five chemistry conditions could be conveniently investigated

in each experiment. Five different combinations of mixing intensities and timing of the dosing

solutions were studied to span the spectrum of practical applications. Thus, for each water a

matrix of five chemistry conditions by five mixing and dosing conditions resulted, plus five

controls. The five mixing and dosing conditions are listed below and were the same for the three

waters.

1. Low G 60 sec-1, simultaneous addition of chlorine and ammonia, 1 minute of

mixing after chemical addition;

2. Intermediate G 500 sec-1, simultaneous addition of chlorine and ammonia, 1

minute of mixing after chemical addition;

78

Pour

ing

posi

tion

Six

2-L

baffl

ed

beak

ers

in ja

r te

st

appa

ratu

s

'"••

•

n 4

"""•

Res

ting

Posi

tion

. __ .

""•-

•••-

..

F -..

F

jp e

>'our

ing

>ath •X /

\ I

Nitr

ogen

Dos

ing

Funn

el

——

7 C

hlor

ine

/

Dos

ing

/

Funn

el

I*"-

-...-

&

®

Baffl

es

i

.Rot

or

Loca

tion

Chl

orin

e D

osin

gFu

nnel

2-L

Beak

er

• 1)

1

§r 1

solu

tion

dosi

ng t

ube

batte

ry

'Am

mon

ia s

olut

ion

dosi

ng t

ube

batte

ry

Baffl

e

Loca

tion

Nitro

gen

Dosi

ngFu

nnel

* 9

B

Pour

ing

Path Do

wel

Figu

re 6

.1

(A)

Side

vie

w o

f baf

fled

beak

er a

nd p

ouri

ng a

ppar

atus

, (B

) pla

n vi

ew o

f baf

fled

beak

er, a

nd (C

) pla

n vi

ew o

f jar

te

st a

ppar

atus

, with

pou

ring

app

arat

us

3.

4.

5.

High G 1000 sec" 1 , simultaneous addition of chlorine and ammonia, 1 minute of

mixing after chemical addition;

Low G 60 sec" 1 , chlorine addition with 30-second delay before ammonia

addition, 1 minute of mixing after ammonia addition; and

Intermediate G 500 sec" 1 , chlorine addition with 30-second delay before

ammonia addition, 1 minute of mixing after ammonia addition.

The five chemistry conditions were selected for each water based on the results of the

batch chemistry experiments of Task la and are tabulated in Table 6.1. The first three

Table 6.1

Chemistry conditions for batch mixing experiments

Condition

LAW1*LAW 2LAW 3LAW 4*LAWS*LHW1*LHW2LHW3LHW4*LHW5*CSPW1*CSPW2CSPW3CSPW4*CSPW5*

pH

6810810668810668810

C12/N Ratio

7/15/15/13/13/13/13/17/13/15/13/13/17/13/13/1

Target 48-hr residual(mg/L)

222222222222222

bromide

ambientambientambientambientambient

+ 0.5 mg/Lambientambientambientambient

+ 0.5 mg/Lambientambientambientambient

* Analyzed for HAAs and CNX

80

conditions for LAW were selected because they produced the most DBF formation at each pH in

Task la. Minimal DBF formation was expected for the fourth and fifth conditions unless

inadequate mixing or delayed dosing of ammonia promoted DBF formation. For LHW, the first

condition was selected to obtain the maximum DBF production with bromide addition. The

second condition was selected as a control on bromide addition and as a typical operating

condition for this type of water. The third condition was selected because it seemed to produce

the most DBFs in the batch experiments. The fourth condition was selected to simulate a typical

operating condition for this type of water, while the fifth condition was selected to provide an

indication of performance at pH 10. For CSPW, the first condition was selected to obtain the

maximum DBF production with bromide addition at a realistic Cb/N ratio. The second

condition was selected as a control on bromide addition. The third and fourth conditions were

selected to simulate the full range of conditions for pH 8. The fifth condition was selected to

provide an indication of performance at pH 10; the ratio of 3/1 was selected over 5/1 because

greater DBF formation was expected, based on the results of Task la.

INFLUENCE OF MIXING

Residual Species—Monochloramine/Dichloramine

Significant dichloramine concentrations were observed after 48 hours only in the

experiments conducted at pH 6, as expected. Thus, chloramine speciation data are presented

only for one pH 6 experiment on LAW and two each on LHW and CSPW. As noted above, a

control with preformed chloramines was run at one of the five mixing conditions in each

experiment, and these data are presented as well. The dichloramine fraction for Experiment

LAW1 (C12/N of 7/1, ambient bromide) is shown in Figure 6.2. A very large fraction of the total

chlorine residual consisted of dichloramine at all mixing conditions. The control with preformed

chloramines fell within the range of the other data (Figure 6.2). Also, these data agreed well

with the corresponding experiment in Task la.

81

•Ambient Bromide Concentration (0.24 mg/L) O Control. Ambient Bromide Concentration

Medium Med./delay Mixing Condition

Low Low/delay

Figure 6.2 Lake Austin water dichloramine fraction at pH 6, 7/1 Cb/N ratio

In LHW, two experiments were conducted at a CVN of ratio 3/1: with and without

bromide addition. The mixing condition had no clear effect on the dichloramine fraction (Figure

6.3). The dichloramine fraction at the ambient bromide concentration was somewhat larger than

that observed in Task 1 a, especially for the medium intensity mixing. With bromide addition,

the dichloramine fraction was considerably larger than that observed in Task la for all mixing

conditions. The mixing studies were conducted with the second batch of LHW; therefore,

differences between Tasks la and Ib may be attributable to differences in water quality between

the two LHW batches.

Two experiments also were conducted in CSPW at a Cli/N of ratio 3/1: with and without

bromide addition. The experiment at ambient bromide had a larger dichloramine fraction at all

mixing conditions than the experiment with bromide added (Figure 6.4). These differences are

consistent with the consumption of chlorine for the production of bromine and bromamines at the

82

•Ambient Bromide Concentration (0.08 mg/L)S0.5 mg/L Bromide AddedO Control, 0.5 mg/L Bromide AddedO Control, Ambient Bromide Concentration i

High Medium Med./delay

Mixing Condition

Low Low/delay

Figure 6.3 Lake Houston water dichloramine fraction at pH 6, 3/1 C12/N ratio

0.60•Ambient Bromide Concentration (0.10 mg/L) jB0.5 mg/L Bromide Added0 Control, 0.5 mg/L Bromide AddedO Control, Ambient Bromide Concentration

0.00High Medium Med./delay

Mixing Condition

Low Low/delay

Figure 6.4 California State Project water dichloramine fraction at pH 6, 3/1 /C^/N ratio

83

expense of dichloramine production (see Chapter 5). With the exception of the ambient bromide

control, the dichloramine fraction tended to be only slightly larger than that observed in Task la.

Taken as a whole, the experiments on the three water sources indicate that mixing

conditions do not significantly affect the disinfectant speciation at the contact times characteristic

of water distribution systems (e.g., 48 hours). Rather, the system chemistry is the controlling

factor. For contact times characteristic of rapid mix basins (e.g., minutes), mixing might have a

substantial effect on speciation; however, disinfectant speciation shortly after disinfectant

addition was not studied in this research.

Total Trihalomethanes and Dissolved Organic Halogen

Lake Austin Water

The results of the Lake Austin mixing experiments are presented graphically in Figures

6.5 through 6.9, which show the 2-day DBF SDS concentrations (TTHM2 and DOX2). Each

figure represents a given chemistry condition, thus facilitating comparisons among the mixing

conditions. Each figure also includes results from the corresponding control experiment with

preformed chloramines and the corresponding Task la batch experiment. Ideally, the data from

the control and batch experiments should be identical. As noted above, maximum DBF

formation at the respective pH was expected for the first three conditions, while minimal DBF

formation was expected for the fourth and fifth conditions. In general, the data showed the same

trends observed in Task la of decreasing DBF formation with increasing pH and decreasing

CVN ratios. No clear trends were apparent on the impact of mixing conditions on DBF

production. The largest DOX concentrations were observed with medium intensity mixing and

delayed ammonia addition. These DOX concentrations, however, were unexpectedly insensitive

to system chemistry, which arouses a certain degree of suspicion about the data for this mixing

condition. The largest TTHM concentrations generally occurred with medium intensity mixing,

and delayed addition of ammonia had a negligible effect on TTHM formation. Apparently, the

kinetics of THM formation are slow enough that a short delay in ammonia addition is not crucial.

Overall, the results point to a secondary role of mixing in DBF formation in comparison to

system chemistry.

84

160

140

I 120c

•x 100

I 80

U 60

a 40* 20

0High Medium Med./delay Low Low/delay Preformed Batch

Figure 6.5 Impact of mixing on 2-d DBF formation in Lake Austin water at pH about 6 and

C12/N ratio of 7 to 1, ambient bromide (0.24 mg/L)

160

140

120

^^ 100o

1I 80

S* 60

40

20

High Medium MedVdelay Low Low/delay Preformed Batch


Cb/N ratio of 5 to 1, ambient bromide (0.24 mg/L)

85

160 160

0High Medium Med./delay Low Low/delay Preformed Batch

0


ratio of 5 to 1, ambient bromide (0.24 mg/L)

High Medium Med./delay Low Low/delay Preformed Batch



86

0High Medium MedVdelay Low Low/delay Preformed Batch

0



87

Lake Houston Water

The results of the Lake Houston mixing experiments are presented in Figures 6.10

through 6.14 and show several trends. With respect to the chemistry conditions, the increase in

TTHM and DOX concentrations when bromide was added is evident (Figures 6.10 and 6.11).

Also, changing the Cb/N ratio from 7/1 to 3/1 at pH 8 lowered the concentrations of TTHMs and

DOX (Figures 6.12 and 6.13). The lowest concentrations of THMs and DOX were formed at pH

10 (Figure 6.14). These patterns were seen in Task la (Figure 5.13 and somewhat in Figure

5.15). Except for the DOX data presented in Figure 6.10, the "preformed" and "batch" data

agreed fairly well. This disagreement may largely result because the "batch" data were

measured on the first Lake Houston sample and the "preformed" data were measured on the

second Lake Houston sample.

In general, the high and medium intensity mixing conditions produced the lower TTHM

concentrations, while low intensity mixing or delayed addition of ammonia produced higher

concentrations of TTHMs. In addition, the controls with preformed chloramines produced the

lowest THM concentrations. Generally, the range of THM concentrations varied within a factor

of approximately two across the range of mixing conditions for a given chemistry condition.

The DOX data are more difficult to interpret because they do not show much dependence

on the mixing condition. In general, however, higher concentrations of DOX were formed when

a delay in adding the ammonia occurred (Figures 6.11, 6.13, and 6.14).

The results indicate that both mixing and chemical addition points (or timing) influence

TTHM formation. The impact is certainly not dramatic (i.e., factor of 2 for THMs and 1.4 for

DOX), but utilities experiencing problems with TTHM and DOX formation may still observe

noticeable decreases in DBF formation through improvement in either or both of these areas.

The improvement is likely to be greater for THMs than for DOX because the kinetics of THM

formation appear to be more rapid than the kinetics of DOX formation in general.

0High Medium MedVdelay Low Low/delayPreformed Batch

Figure 6.10 Impact of mixing on 2-d DBF formation in Lake Houston water at pH about 6 and

ratio of 3 to 1, 0.5 mg/L bromide added

I_oto u-C

6




89



Cb/N ratio of 7 to 1, ambient bromide (0.08 mg/L)




90

350

Io1•*-*g

§ U

^-H

E

10

0 0High Medium Med./delay Low Low/delay Preformed Batch



91


The results of the CSPW mixing experiments are presented in Figures 6.15 through 6.19

and show several trends. The expected increase in TTHM and DOX concentrations when

bromide was added is evident (Figures 6.15 and 6.16). Also as expected, changing the Cb/N

ratio from 7/1 to 3/1 at pH 8 substantially lowered the TTHM and DOX concentrations (Figures

6.17 and 6.18). The lowest TTHM and DOX concentrations occurred at pH 10 (Figure 6.19).

Except for the data presented in Figure 6.19, the "preformed" and "batch" data agreed fairly

well.

As with the LHW, a priori, one would expect the TTHM and DOX concentrations to

increase "to the right" across Figures 6.15 through 6.19, with the last two data sets on the right

equal to each other and equal to or less than the data collected in the "left-hand" condition,

high-energy mixing. Some anomalies in this trend did occur, as in the low-energy mixing data in

Figure 6.15 for TTHM, and the "medium with delay" DOX data in Figures 6.17 and 6.18. In

general, however, the high and medium intensity mixing conditions produced the lower TTHM

and DOX concentrations, while low intensity mixing or delayed addition of ammonia produced

higher concentrations. Generally, the range of TTHM and DOX concentrations varied within a

factor of approximately two across the range of mixing conditions for a given chemistry

condition (i.e., pH, Cb/N ratio). Therefore, these data also indicate that utilities may achieve

some decreases in THM and DOX formation through improved mixing, simultaneous addition of

chlorine and ammonia, or both.

Haloacetic Acids

Lake Austin Water

In general, only three HA As were formed during the Lake Austin mixing study, DCAA,

DBAA, and BCAA, with the latter two dominating the HAA6 (Table 6.2). The pH 6, 7/1 C12/N

ratio conditions produced the most HAA6 for all of the conditions studied. As with the TTHM

and DOX data, a one-minute period of free chlorine did not enhance HAA6 formation. For the

92


Figure 6.15 Impact of mixing on 2-d DBF formation in California State Project water at pH

about 6 and Ck/N ratio of 3 to 1, 0.5 mg/L bromide added

80

70 —



about 6 and Cb/N ratio of 3 to 1, ambient bromide (0.10 mg/L)

93


0


about 8 and Cb/N ratio of 7 to 1, ambient bromide (0.10 mg/L)

80


Figure 6.18 Impact of mixing on 2-d DBP formation in California State Project water at pH

about 8 and C12/N ratio of 3 to 1, ambient bromide (0.10 mg/L)

94

80

0 0

u

I4-*

24^

U

o UXs


Figure 6.19 Impact of mixing on 2-d DBP formation in California State Project water at pH

about 10 and C12/N ratio of 3 to 1, ambient bromide (0.10 mg/L)

95

Table 6.2

Lake Austin water haloacetic acid concentrations for bench mixing studies

Mixing Condition

High

Medium

Medium w/ delay

Low

Low w/ delay

Task la

High

Medium

Medium w/ delay

Low

Low w/ delay

Task la

High

Medium

Medium w/ delay

Low

Low w/ delay

Task la

CAA BAA DCAA TCAA BCAA (ug/L) (ng/L) (ug/L) (ug/L) (ug/L)

nd

nd

nd

nd

nd

1.1

nd

nd

nd

nd

nd

bdl

nd

nd

nd

nd

nd

bdl

pH 6, 7/1

bdl

bdl

bdl

bdl

bdl

bdl

pH 8, 3/1

bdl

bdl

bdl

bdl

bdl

bdl

pH 10, 3/1

nd

nd

nd

nd

nd

DBAA(ug/L)

HAA6(ug/L)

Cb/N ratio, ambient bromide

4.7

4.7

2.4

4.0

2.1

3.3

1.2

bdl

bdl

bdl

bdl

bdl

6.7

7.7

4.5

5.5

5.4

6.3

5.0

5.6

5.0

4.6

4.2

8.5

17.5

18.0

11.9

14.1

11.8

19.2

Cb/N ratio, ambient bromide

4.5

2.2

2.3

bdl

bdl

2.1

C12/N ratio,

3.1

1.4

2.8

bdl

1.0

bdl 1.0

bdl

nd

bdl

bdl

bdl

bdl

ambient bromide

bdl

nd

bdl

bdl

bdl

bdl

3.0

1.9

3.5

bdl

1.8

2.1

1.7

0.8

1.5

bdl

bdl

bdl

1.8

1.3

1.1

bdl

0.3

2.0

1.6

1.2

bdl

bdl

bdl

1.4

9.3

5.4

6.9

0.0

2.0

6.2

6.3

3.4

4.3

0.0

1.0

2.4

Note: All HAA concentrations are 48-hr SDS values

bdl = below detection limit nd = none detected

96

other two exposure conditions, pH 8 and pH 10, 3/1 Cb/N ratio, the HAA6 concentration was

very low (<10 ug/L). Only small differences in HAA6 concentrations were observed with

different mixing conditions at each chemistry condition.

Lake Houston and California State Project Waters

Similarly, no consistent trend is evident for the HAA6 concentration in the Lake Houston

(Table 6.3) and California State Project mixing studies (Table 6.4) as a function of mixing

intensity or dosing timing. Perhaps the formation kinetics are slower than for THMs, so mixing

and the timing of chemical addition are less important, or the impact of these variables is within

the uncertainty of the HAA analytical method. As expected, a difference was observed with and

without bromide addition. In the absence of bromide addition, DCAA was virtually the only

HAA formed in LHW. With bromide, significant production of both BCAA and DBAA was

observed in LHW and greater production of BCAA and DBAA was observed in CSPW.

Cyanogen Halides

In all three waters, good agreement was observed between HAA6 concentrations

measured in Task la with preformed chloramines and those measured in the Task Ib mixing

studies. Again, this suggests that HAA formation kinetics are rather slow in comparison to the

kinetics of chloramine formation; therefore, within typical operating conditions, chemical dosing

and mixing are of secondary importance in HAA formation.

The cyanogen halide (CNX) results of the bench-scale mixing studies of the three waters

are given in Table 6.5. In all three waters, neither cyanogen chloride (CNC1) nor cyanogen

bromide (CNBr) was found at pH 10 because of base-catalyzed hydrolysis of these compounds.

All the CNC1 levels were low, ranging from less than 0.7 ug/L to 2.8 ug/L, with small variations

in CNC1 concentrations (0.4 to 1.8 ug/L) with changes in mixing conditions. In Lake Austin, at

pH 6 and 8, the concentration of CNC1 for the high-intensity mixing test was slightly greater than

for the low and medium mixing intensities with or without delay in ammonia addition. In Lake

Houston, no consistent trend was observed, with highest CNC1 concentrations at low mixing

97

Table 6.3

Lake Houston water haloacetic acid concentrations for bench mixing studies

Mixing Condition

CAA BAA DCAA(ug/L) (ug/L) (ug/L)

pH 6, 3/1 Cl

High

Medium

Medium

Medium w/ delay

Low

Low

Low w/delay

High

Medium

Medium w/ delay

Low

Low w/ delay

Task la

High

Medium

Medium w/ delay

Low

Low w/ delay

nd

nd

nd

nd

nd

nd

bdl

PH

nd

nd

nd

nd

nd

bdl

pH

nd

nd

nd

nd

2.3

bdl

bdl

bdl

bdl

bdl

bdl

1.5

TCAA BCAA (ug/L) (ug/L)

DBAA(ug/L)

HAA6(ug/L)

,2/N ratio, bromide added

13.3

26.3

17.8

4.8

20.6

19.7

17.1

bdl

1.2

bdl

1.1

bdl

2.2

2.3

24.2

26.7

21.3

8.7

31.1

27.0

28.3

21.1

32.8

12.6

4.4

25.7

21.0

21.7

58.6

87.0

51.7

19.0

77.4

69.9

70.9

8, 3/1 Cb/N ratio, ambient bromide

nd

nd

nd

nd

nd

bdl

10, 5/1 Cl

nd

nd

nd

nd

bdl

26.2

29.9

25.7

32.5

31.2

20.0

bdl

nd

2.5

bdl

2.9

bdl

bdl

1.9

2.5

bdl

4.4

6.5

bdl

bdl

bdl

bdl

bdl

1.9

26.2

31.8

30.7

32.5

38.5

28.4

2/N ratio, ambient bromide

42.3

43.9

30.5

40.9

37.0

bdl

nd

bdl

bdl

1.0

bdl

3.2

2.5

bdl

4.0

bdl

bdl

bdl

bdl

bdl

42.3

47.1

33.0

40.9

44.3

Note: All HAA concentrations are 48-hr SDS values

bdl = below detection limit nd = none detected

98

Table 6.4

California State Project water haloacetic acid concentrations for bench mixing studies

Mixing Condition

High

Medium

Medium w/ delay

Low

Low w/delay

High

Medium

Medium w/ delay

Low

Low w/ delay

Task la

High

Medium

Medium w/ delay

Low

Low w/ delay

Task la

CAA

nd

nd

nd

nd

nd

nd

nd

nd

nd

nd

bdl

nd

nd

nd

nd

nd

2.7

BAA(Hg/L)

pH 6, 3/1

bdl

bdl

bdl

bdl

bdl

pH 8, 3/1 (

nd

nd

nd

nd

nd

bdl

pHl 0,3/1

nd

nd

nd

nd

nd

nd

DCAA

C12/N ratio,

1.7

1.7

4.9

2.3

1.2

TCAA (Hg/L)

bromide

bdl

bdl

bdl

bdl

bdl

BCAA

added

5.7

6.3

6.3

6.6

5.2

DBAA(ug/L)

10.4

11.7

12.8

12.0

11.2

HAA6(HR/L)

17.8

19.7

24.0

20.9

17.6

C12/N ratio, ambient bromide

4.3

7.6

9.1

5.1

5.5

2.8

C12/N ratio,

4.5

5.0

5.2

4.9

5.8

2.5

bdl

1.1

bdl

bdl

bdl

bdl

2.1

2.3

2.8

2.5

2.8

2.1

bdl

2.5

1.1

1.2

1.4

bdl

6.4

13.5

13.0

8.8

9.7

4.9

ambient bromide

bdl

bdl

bdl

bdl

bdl

bdl

1.5

1.9

2.1

2.1

2.1

1.1

bdl

1.0

1.2

1.2

1.2

1.1

6.0

7.9

8.5

8.2

9.1

7.4

Note: All HAA concentrations are 48-hr SDS values bdl = below detection limit nd = none detected

99

o

o

Tab

le 6

.5

CN

X c

once

ntra

tions

for

ben

ch m

ixin

g st

udie

s

Mix

ing

Con

ditio

n

CNC1

(Hg/

L)

CN

Br

(ug/

L)

CN

X

(Hg/

L)

CNC1

(Hg/

L)

CN

Br

(ug/

L),

.

CN

X

'(ug/

L)

CNC1

(Hg/

L)

CN

Br

(Hg/

L)

CN

X

(Hg/

L)

Lake

Aus

tin W

ater

Hig

h

Med

ium

Med

ium

w/ d

elay

Low

Low

w/ d

elay

pH 6

, 7/1

2.7

1.1 0.9 1.5

1.3

C12/N

, am

bien

t Br

5.0

6.5

5.0

6.5

5.8

7.7

7.6

5.9

8.0

7.1

pH 8

, 3/1

1.7

1.0

1.0

1.0

1.0

C12/N

, am

bien

t

nd nd nd nd nd

Br"

1.7

1.0

1.0

1.0

. i.o

PH

nd nd nd nd nd

10, 5

/1 C

12/N

,

nd nd nd nd nd

ambi

ent B

r"

nd nd nd nd nd

Lake

Hou

ston

Wat

er

Hig

h

Med

ium

Med

ium

w/ d

elay

Low

Low

w/ d

elay

pH 6

, 3/1

1.6

1.0

1.7

1.5

1.6

C12/N

, Bf

adde

d

5.0

2.7

2.2

5.4

5.8

6.6

3.7

3.9

6.9

7.4

pH 8

, 3/1

1.5

1.4

1.7

2.8

2.0

C12/N

, am

bien

t

nd nd

* ,

nd nd nd

Br"

1.5

1.4

1.7

2.8

'2.0

pH

nd nd nd nd nd

10, 5

/1 C

12/N

,

nd nd nd nd nd

ambi

ent B

r" nd nd nd nd nd

Cal

iforn

ia S

tate

Pro

ject

Wat

er

Hig

h

Med

ium

Med

ium

w/ d

elay

Low

Low

w/ d

elay

pH 6

, 3/1

nd nd 0.7 nd nd

C12/N

, Br'a

dded

6.2

6.4

7.9

7.7

8.0

6.2

6.4

8.6

7.7

8.0

pH 8

, 3/1

1.0

0.9 1.3 1.2

0.9

C12/N

, am

bien

t Br"

nd nd nd nd nd

1.0

0.9

'

1.3

1.2

.0.9

pH

nd nd nd nd nd

10, 3

/1 C

12/N

,

nd nd nd nd nd

ambi

ent B

r" nd nd nd nd nd

Note:

All

CNC1

and

CN

Br c

once

ntra

tions

are

48-

hr S

DS

valu

es

nd =

non

e de

tect

ed; n

d <

0.7

for C

NC1

, nd

< 1.

0 fo

r CN

Br

intensities for pH 8 data and a dip in the CNC1 level at a medium mixing intensity (no delay) for

pH 6. In the CSPW, no significant differences in CNC1 concentrations were observed as mixing

conditions were varied.

CNBr was only found in the mixing studies conducted at pH 6. In Lake Austin, CNBr

levels showed no discernible trend. In Lake Houston, significantly higher CNBr levels occurred

in the low- and high-intensity mixing experiments. The concentrations for the two medium

energy mixing experiments appeared to be atypically low, however, based on the results of the

Task la studies. In CSPW, CNBr levels were slightly higher in the tests with delayed or

low-intensity mixing as compared to the medium- and high-intensity mixing experiments with no

delay. As with the CNC1 results, however, the differences tended to be relatively small and may

not be statistically significant.

The CNC1 and CNBr concentrations in the mixing studies showed good agreement with

those measured in the Task la studies with preformed chloramines. Thus, as with the HAAs,

chemistry conditions (e.g., pH, Cli/N ratio) appear to impact CNX formation more than the

mixing intensity and dosing timing.

Implications for Mixing at Larger Scale

Given that the mixing experiments were conducted at small scale in laboratory-sized

beakers, it is appropriate to consider how these results relate to the larger-scale mixing occurring

in practice. Clark and Fiessinger (1991) reviewed the literature on mixing and scaleup, and

highlighted several scale-up relationships. Unfortunately, rapid mixing is not well understood,

which is reflected in the available scaleup relationships. Depending upon the relationship

selected, G at large scale should be greater than, equal to, or less than the small-scale G to

achieve the same degree of mixing. For this particular application, relationships that show G at

larger scale equal to or greater than the small-scale G are probably most appropriate because

chloramine formation kinetics are relatively fast. Even with this narrowing of the range of

scaleup relationships, considerable uncertainty remains about the effect of scale on mixing.

Consideration of several aspects of the experimental design and objectives also provides

some insight into the effect of scale on mixing. First, the issue of relative reaction times must be

considered. Rapid mixing occurred for 1 to 2 minutes, prior to 48 hours of incubation to

101

simulate distribution system conditions. Therefore, unless the DBF reaction kinetics were very

rapid, the less than ideal mixing conditions that may have occurred during the brief mixing

period would have been overwhelmed by the far longer reaction time provided by the simulated

distribution system test, which was the focus of this research. Second, two of the mixing

conditions provided a 30-second delay between the addition of chlorine and the subsequent

addition of ammonia. These two mixing conditions may be viewed either as a test of delayed

ammonia addition or as a way of simulating poor mixing during simultaneous addition of the two

chemicals. A 30-second delay in ammonia addition represents a significant opportunity for DBF

formation within the context of typical rapid mix detention times. Third, the G values used in

this research (60, 500, and 1000 sec" 1 ) are smaller than those used in practice. For example, a

high G value at full scale to achieve good mixing would be larger than the high G value of 1000

sec" 1 used in this research. Therefore, the scaling relationships suggesting that G must increase

with scale to maintain identical mixing were followed in a qualitative way in this research.

Considering that the experimental conditions covered a broad range of mixing intensities

and included delayed addition of ammonia, and considering that the objective was to simulate

the impact of mixing at the point of disinfectant addition on distribution system DBF

concentrations, the mixing experiments should provide a reasonable estimate of the relative

impact of mixing on DBF formation at full scale.

RECOVERY OF DISSOLVED ORGANIC HALOGEN WITH 12 MEASURED DISINFECTION BY-PRODUCTS

Among the samples collected during Task Ib, certain samples were selected for

additional DBF SDS analyses beyond the SDS THMs and SDS DOX determinations. These

selected samples were also tested for SDS HAA6 and SDS CNC1 and SDS CNBr. Thus, in these

samples, after the 48 hours of incubation, 12 DBFs were measured, as well as DOX.

These data are presented for the Task Ib samples in Figures 6.20 to 6.27 for each of the

three primary waters. Here again, as in Task la (Figures 5.24 to 5.26), the recovery values are

quite low, less than 16 percent for LHW, less than 23 percent for LAW, and less than 32 percent

for CSPW. For Lake Houston and CSPW, mixing intensity had little effect on the recovery

102

25

oQ

10QCN

I*o=1. "~ 0

CNXdataNotA \/a i 1 ..JillHigh Medium MedVdelay Low Low/delay Batch

Figure 6.20 Influence of mixing conditions on the percentage of DOX identified by summing

the 12 measured DBFs (E 12 DBPOX) in Lake Austin water: pH about 6, C12/N ratio 7 to 1,2

mg/L nominal total residual after 2-d, ambient bromide (0.24 mg/L)

High Medium Med./delay Low Low/delay Batch


the 12 measured DBFs (E 12 DBPOX) in Lake Austin water: pH about 8, C12/N ratio 3 to 1, 2


103



the 12 measured DBFs (Z 12 DBPOX) in Lake Austin water: pH about 10, C12/N ratio 3 to 1, 2


104



the 12 measured DBFs (2 12 DBPOX) in Lake Houston water: pH about 6, C12/N ratio 3 to 1, 2

mg/L nominal total residual after 2-d, 0.5 mg/L bromide added

0High Medium MedVdelay Low Low/delay Batch


the 12 measured DBFs (Z 12 DBPOX) in Lake Houston water: pH about 8, C12/N ratio 3 to 1, 2


105



the 12 measured DBFs (1, 12 DBPOX) in Lake Houston water: pH about 10, C12/N ratio 5 to 1, 2


106

High Low Low/delay BatchMedium Med./delay


the 12 measured DBFs (2 12 DBPOX) in California State Project water: pH about 6, C12/N ratio

3 to 1, 2 mg/L nominal total residual after 2-d, 0.5 mg/L bromide added

High Medium Med7delay Low Low/delay Batch


the 12 measured DBFs (Z 12 DBPOX) in California State Project water: pH about 10, C12/N

ratio 3 to 1, 2 mg/L nominal total residual after 2-d, ambient bromide (0.10 mg/L)

107

factor. Differences were noted in the LAW samples (Figures 6.20 to 6.22) but no particular

pattern developed.

As mentioned previously, the work of Singer et al. (1992) showed that the slope of the

best fit line through the data was about one-third of the slope of a 100 percent recovery line.

Thus, with both free chlorine and chloramines, a large concentration of "unidentifiable" halogen-

substituted DBFs are formed in the application of these oxidants.

108

CHAPTER 7

PILOT PLANT STUDIES—TASK 2

OBJECTIVES

In contrast to Task 1, which was all performed at bench scale, Task 2 was all performed

in pilot plants. The purposes of this phase of the study were to investigate the effects of scaleup

and the influence of some of the key variables in continuous-flow systems, to compare the Task

la results in the batch mode with the continuous-flow mode, and to investigate the influence of

coagulation, enhanced coagulation, ozonation, biofiltration treatment, and point of chlora-

mination (source water versus filtered water) on the resulting DBF formation.


Studies were conducted on each of the primary waters, Lake Austin, Lake Houston, and

California State Project Water. Schematic diagrams of each of the pilot plants are presented in

Figures 7.1 to 7.3. For all of the studies, pilot-plant effluents were incubated for 48 hours at

22 C (25 C for LHW) with a target total residual at the end of incubation of 2 mg/L to simulate

the distribution systems (i.e., SDS-type testing). Various SDS incubation pHs were used, as

described in detail below.

Description of Pilot Plants

Houston

The University of Houston pilot plant consists of a static rapid mixer, a tapered

flocculator, a tube settler with 19 tubes (1-inch ID) at a 60 degree angle and a dual-media filter

(anthracite coal over sand) (see Figure 7.1). The entire plant operates under pressure provided

by a centrifugal pump. The flocculator, settling basin, and filter are constructed of hard, clear

plastic. A flow of 0.3 gallons per minute (1.1 L/min.) (about 450 gallons or 1,700 L per day)

produces an approach velocity in the filter of about 2 gpm/ft2 (5m/hr) and 144 minute detention

109

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time. In operation on LHW, this pilot plant regularly produced water containing 0.5 NTU or less

of effluent turbidity. In the source water chloramination tests, sodium hypochlorite solution and

the ammonium sulfate solution were stored in separate carboys and pumped in the proper

proportion into the source water just prior to a static mixer. In the postfiltration chloramination

tests, a static mixer was placed immediately after the filter, and this is where the two solutions

were added.

The pilot plant is instrumented with a pressure gauge for determining head loss in the

filter and a rotameter for flow control. During backwash, both surface wash and upflow

backwash were available. As the total volume of the pilot plant is about 45 gallons (170 liters),

the theoretical detention time is 144 minutes at a flow rate of 0.3 gpm (1.1 L/min). Thus, about

10 bed volumes pass through the pilot plant each day. For this study, the pilot plant was placed at

the City of Houston's East Water Treatment Plant, where the source was LHW.

Austin

A schematic flow diagram of the Austin pilot plant is presented in Figure 7.2. The plant

has a nominal capacity of 6 gpm (23 L/min.) and consists of two ozone contactors; one

coagulation, flocculation, settling and recarbonation train; three mixed media filters; and two

granular activated carbon (GAC) adsorbers. The ozone contactors were configured for series

operation in a pre-ozonation treatment mode. The pilot plant permitted evaluation of a variety of

different treatment options. For example, the plant was operated with or without preozonation,

and chloramines were injected at several points in the treatment train. For source water

chloramination, chlorine and ammonia solutions were mixed separately in 55-gallon (210-L)

drums and pumped into the influent stream continuously.

Metropolitan Water District of Southern California

MWDSC's pilot-scale water treatment facility is located at its F.E. Weymouth Filtration

Plant in La Verne, Calif. The 6-gpm (23-L/min.) pilot plant was designed to simulate full-scale

conventional treatment, including preoxidation (using ozone); coagulation and flocculation; and

dual-media filtration (see Figure 7.3). The means to test biological filtration were also used.

113

Various ozone dosages were applied countercurrent to the water flow through 4-in. (10-cm)

ceramic diffusers in 16 ft (4.9 m) x 6 in. (15.2 cm) glass ozone contactors. The ozone transfer

efficiencies were >98 percent. For experiments using prechloramination, concurrent chlorine

addition and ammonia addition, at various mass ratios to produce the desired total chloramine

level, were injected at the rapid mix just prior to coagulation. In one of the tests (Run 2), a

deliberate one minute delay in the addition of the ammonia solution was included to assess the

influence of a short period of free chlorine on the formation of DBFs. Conventional alum

coagulation for turbidity removal (not enhanced coagulation) and sedimentation was followed by

dual-media filtration. Two types of filters were used, anthracite coal/sand and GAC/sand at a

filtration rate of 6 gpm/ft2 (15 m/h).

Lake Austin Water

Because the pH of LAW is approximately 8 and current treatment consists of lime

softening, these pilot studies examined performance at SDS incubation pH levels of 8 and 10

only. The full-scale plant used a Cli/N ratio of 4/1.

Operating conditions are outlined below:

Runs 1A and IB: Cb/N of 3/1, ambient bromide concentration, source water

chloramination, lime softening. Two sets of samples were collected after

filtration for SDS measurements. The first set was incubated at pH 10, and the

second set was adjusted to pH 8 with sulfuric acid before incubation to simulate

recarbonation. Thus, this filter run effectively simulated two conditions in the

distribution system for DBF formation.

Runs 2A and 2B: C12/N of 5/1, ambient bromide concentration, source water

chloramination, lime softening. Two sets of samples were collected after

filtration for SDS measurements. The first set was incubated at pH 10, and the

second set was adjusted to pH 8 before incubation to simulate recarbonation.

Thus, this filter run effectively simulated two conditions in the distribution system

for DBF formation.

114

Run 3: CVNof 5/1, ambient bromide concentration, source water

chloramination. In this experiment, the pilot plant was operated as a direct

filtration plant with alum addition to simulate a realistic operating scheme if lime

softening were not practiced on this water. The SDS samples were incubated at

pH8.

Run 4: C^/N of 5/1, ambient bromide concentration, postfilter chloramination.

In this experiment, the pilot plant was again operated as a direct filtration plant

with alum addition with chloramination after some precursor removal. The SDS

samples were incubated at pH 8.

Runs 5A and 5B: CVN of 5/1, ambient bromide concentration, source water

ozonation (applied ozone dose equaled 1 mg/mg TOC, qualitative positive low

ozone residual in contactor effluent), lime softening, and postchloramination.

Two sets of samples were collected after filtration (not biologically active because

of pH 10 and intermittent operation) for SDS measurements at pH 10 and 8, as

before.

Each experiment lasted three days, with a steady-state sampling period of three days.

During this sampling period, samples were collected twice daily for DBF analyses.

Lake Houston Water

Because LHW is very soft and has low alkalinity with an ambient pH of approximately

6.5, and because the current treatment consists of alum coagulation, these pilot studies examined

performance at SDS incubation pH levels of 6 and 8. The full-scale plant operates at a Cli/N

ratio of 5/1.


Run 1: Cla/N of 3/1, ambient bromide concentration, conventional coagulation,

prechloramination. One set of SDS effluent samples was collected and incubated

at pH 8.

115

Run 2: C^/N of 3/1, ambient bromide concentration, conventional coagulation,

postchloramination. One set of SDS effluent samples was collected and incubated

at pH 8.

Runs 3A and 3B: Cb/N of 3/1, ambient bromide concentration, prechloramination,

enhanced coagulation. Two sets of SDS effluent samples were collected, one

incubated at pH 8 and the other incubated at pH 6. This allowed an assessment of

the impact of pH utilizing the enhanced coagulation pH (6) and a pH level (8) for

corrosion control.

Runs 4A and 4B: C^/N of 3/1, ambient bromide concentration, enhanced

coagulation, chloramination after filtration. This test was conducted to assess

moving the point of disinfection because CT credit will not be given in the

proposed Disinfectants/DBP Rule for source water chlorination and

chloramination, because, according to the rule, specified TOC levels must be

removed through enhanced coagulation or softening before disinfection (USEPA

1994b). Two sets of SDS effluent samples were collected, one incubated at pH 8

and the other incubated at pH 6.

Runs 5A and 5B: Cfe/N of 3/1, 0.5 mg/L bromide ion added, prechloramination,

conventional coagulation. Two sets of SDS effluent samples were collected, one

incubated at pH 8 and the other incubated at pH 6.

Each experiment lasted three or four days, with a steady-state sampling period of one to

three days. During this sampling period, samples were collected twice daily for DBF analysis.


Because CSPW has a pH of nearly 8 and more alkalinity than LHW, operation at other

pH values would not simulate realistic treatment conditions for this water. Both standard

conventional treatment and ozonation with and without biofiltration were studied on CSPW.

MWDSC used a pilot plant with two parallel trains, one of which operated in a conventional

mode with chloramination as the sole disinfectant, whereas the other train operated with

116

ozonation, biofiltration, and chloramination. Also, different process scenarios were studied in

the same pilot plant run by collecting samples before and after biologically active filters. The

samples collected before the filter were filtered through a type A/E glass fiber filter (Gelman

Sciences, Inc., Ann Arbor, Mich.), nominal one-micrometer (urn) pore diameter, in the

laboratory before chloramination to simulate the impact of filtration alone (without

biodegradation).

The batch test conditions of ambient bromide ion concentration pH 8, Cla/N ratios of

3/1 and 5/1, and a final total chlorine residual concentration of about 2 mg/L were selected for

testing at the pilot plant because they represented the most realistic conditions for treatment of

this water. Formerly, MWDSC chloraminated at a 3/1 C12/N ratio and currently (1996) uses a

5/1 ratio. In addition to an increase in scale (-3.5 gpm) and incorporation of flow dynamics, the

pilot plant included conventional alum coagulation and filtration for all runs and preozonation

for two sets of runs. Each run was conducted for a minimum of two days with samples collected

twice daily. Two of the tests were repeated two weeks after the initial runs to assess variability

(i.e., because of source water changes and plant reconfiguration).


Run 1: Cla/N of 5/1, ambient bromide, source water chloramination, concurrent

addition in rapid mix, conventional alum treatment, SDS incubation at pH 8. This

run was repeated two weeks after the initial test to assess variability (Run 1

repeat).

Run 2: Ch/N of 5/1, ambient bromide, conventional alum treatment, post-

sedimentation, chloramination with delay, SDS incubation at pH 8. The chlorine

and ammonia addition was staggered (i.e., chlorine was added to sedimentation

basin effluent and the ammonia added one minute later to the filter influent), and

mixing was achieved by turbulence in the pipe.

Runs 3A and 3B: C^/N of 5/1, ambient bromide, preozonation and post-filter

chloramination, ozone residual of 0.35 mg/L (required to achieve a 1/2 log of

Giardia inactivation), SDS incubation at pH 8. The ozone dose (applied =

transferred) was 0.75 mg/L (ozone-to-TOC ratio of 0.23/1 mg/mg). One set of

samples was collected before biofiltration (3B) and another set after biofiltration

117

RESULTS

(3A). The A samples were filtered through the pilot plant's biologically active

GAC filters, and the B samples were batch filtered through a type A/E glass fiber

filter (Gelman), nominal 1-um pore diameter, before batch SDS chloramination

(addition of ammonia then chlorine with vigorous mixing). Possibly

biodegradation may have been occurring in the pilot plant before the biofilters (in

the flocculation/sedimentation basins), as the ozonation train of the plant was

operated without any disinfectant residual through the fiocculation and

sedimentation basins. Biodegradation has been observed in MWDSC's oxidation

demonstration plant (Coffey et al. 1996).

Runs 4A and 4B: Cb/N of 5/1, ambient bromide, preozonation and post-filter

chloramination, ozone residual of 0.55 mg/L (required to achieve 2 logs of

Giardia inactivation), SDS incubation at pH 8. The ozone dose (applied =

transferred) was near 1.8 mg/L (or ozone-to-TOC ratio of 0.61 mg/mg). One set

of samples was collected before biofiltration (4B) and another set after

biofiltration (4A). Samples collected before biofiltration were conventionally

filtered in the laboratory as described above. Both sets of samples were then

batch chloraminated. In an effort to remove any biologically active sites in the

pilot plant flocculation/sedimentation basins, the basins were cleaned and these

runs repeated (Runs 4A repeat and 4B repeat).

Run 5: Cb/N of 3/1, ambient bromide, source water chloramination, concurrent

addition in rapid mix followed by conventional alum treatment. The target SDS

pH was 8. This test allowed comparison with Task la batch study data and also

showed the effect of a different Cb/N ratio.

All of the pilot plants produced effluent turbidities between 0.05 and 0.37 NTU, with

most of the values below 0.15 NTU. Thus, the pilot plants were operating well. Note that the

ammonia-nitrogen (Ntb-N) concentration was not measured. The nitrogen dose was calculated

based on the desired Cb/N ratio and the measured chlorine dose.

118

Lake Austin Water

The data from the eight individual runs are presented in Tables B.I to B.8 in Appendix B.

The data in Table 7.1 are a summary of the key average output values for all eight runs. This

allows for an easy comparison of the influence of the variable operating conditions on the quality

of the effluent.

Residual Disinfectant Species and Concentration

No dichloramine was present in any of the effluent samples at the end of the SDS test.

Also, most of the total residuals were near the target concentration of 2 mg/L.

Disinfection By-Product Formation

Trihalomethanes. The TTHM concentrations were less than 10 ug/L in all of the runs.

The highest TTHM concentration occurred in Run 3, which had the highest source water TOC

concentrations of those runs for which this parameter was measured (4.6 mg/L versus 2.5 to 3.6

mg/L). Note that because of the greater amount of precursor material, Run 3 had the highest

chlorine demand. Thus, to achieve the target residual concentration, more chlorine was added to

Run 3. This may have contributed to the higher concentrations of TTHMs. Moving the point of

chloramine application to after filtration (Run 4) did demonstrate, however, that if direct

filtration was allowed to be completed prior to disinfectant application, TTHM concentrations

would be lower. On the other hand, Run 4 also had 1.0 mg/L less TOC in the source water,

which confounds the analysis.

Haloacetic acids. The HAA6 concentrations were typically in the range of 10 to

20 ug/L. Ozonation, however, did have a positive influence on the removal of HAA6 precursor

119

Tabl

e 7.

1

Sum

mar

y of

Lak

e A

ustin

wat

er p

ilot p

lant

resu

lts (

aver

age

valu

es)

Run

C

ondi

tions

1A A

mbi

ent B

r,Pr

echl

oram

., So

ftIB

Am

bien

t Br,

Prec

hlor

am.,

Soft

2A A

mbi

ent B

r,Pr

echl

oram

., So

ft2B

Am

bien

t Br,

C12/N 3/1

3/1

5/1

5/1

SDS

pH 10 8 10 8

C12 D

ose

mg/

L

2.83

2.83

2.95

2.95

Tota

l R

esid

ual

mg/

L

2.33

2.36

2.45

2.45

Ave

rage

R

esid

ual

mg/

L

2.65

2.60

2.70

2.70

C12

Dem

and

mg/

L

0.50

0.47

0.50

0.50

Sour

ce

TOC

m

g/L

2.5

2.5

2.5

2.5

2dSD

S TT

HM

ug

/L

0.2

0.3 1.9

1.9

2dSD

S H

AA

6 ug

/L

20.0

10.4

12.2

9.6

2dSD

S M

XA

A

ug/L

2.7

0.5

0.4

BD

L

2dSD

S D

XA

Aug

/L

14.6

9.9

11.8

9.6

2dS

DS

TC

AA

Ug/

L

2.7

BD

L

BD

L

BD

L

2dSD

S C

NX

ug

/L

0.3 1.3

0.0 1.5

2dSD

S D

OX

ug

ClT

L

20.4

28.3

32.3

44.1

% D

OX

A

ccou

nted

F

ort

45.1

25.2

16.6

*

11.1

*

Prec

hlor

am.,

Soft

3 A

mbi

ent B

r, 5/

1 Pr

echl

oram

., D

irect

Fi

ltrat

ion

4 A

mbi

ent B

r, 5/

1 Po

stch

lora

m.,

Dire

ct F

iltra

tion

5A A

mbi

ent B

r, O

zone

, 5/

1Po

stch

lora

m.,

Soft

5B A

mbi

ent B

r, O

zone

, 5/

1Po

stch

lora

m.,

Soft

8 3.66

1.77

8 2.47

1.70

10

2.60

2.00

8 2.60

2.10

2.72

1.89

4.6

7.2

2.08

0.77

3.6

1.1

2.30

0.6

NR

0.0

2.35

0.5

NR

1.5

11.6

BDL

11.6

BDL

3.3

65.4

16.2

10.2

BDL

10.2

BDL

4.1

58.8

6.2*

0.8

BDL

0.8

BDL

1.2

28.2

0.6

1.4

BDL

1.4

BDL

6.2

30.3

6.1

Note:

All

DB

F da

ta ro

unde

d to

one

dec

imal

pla

ce, d

ichl

oram

ine

zero

per

cent

of t

otal

res

idua

l

* C

alcu

late

d ba

sed

on a

vera

geva

lues

t O

n m

olar

bas

isB

DL

= B

elow

Det

ectio

n Li

mit

DX

AA

= D

CA

A+

DB

AA

+BC

AA

MX

AA

= M

CA

A+M

BA

AN

R =

Not

Run

as evidenced by the lower concentrations in Runs 5A and 5B (i.e., 0.8 to 1.4 ug/L). Because

ozone can oxidize bromide to bromate, HAA concentrations may have been lower because the

inorganic precursor bromide was lessened in concentration. In other LAW runs, bromine-

substituted HAAs dominated the HAA6 formation. Miltner et. al (1992) observed such a

phenomenon during ozonation studies of bromide-containing waters. In contrast to the TTHMs,

completion of direct filtration prior to chloramination (Run 4) did not lower the HAA6

concentration. An inspection of the data in Table 7.1 shows that the dihalogen-substituted acetic

acids (DXAA) dominated the HAA6 formation in all runs. Chloramines may preferentially form

DXAAs. Smith et al. (1993) found that TCAA was the principal HAA formed during

chlorination, whereas it was not detected during chloramination, yet appreciable formation of

DXAA did occur during chloramination.

Cyanogen halides. CNXs undergo base-catalyzed hydrolysis. Thus, their formation and

stability were high when both treatment and distribution were at pH 8 (i.e., Runs 3 and 4). CNX

formed to a slightly greater extent when incubated at pH 8 after softening at pH 10 (Run 5B),

whereas incubation at pH 10 destroyed them. As with HAA6, moving the point of

chloramination in a direct filtration scheme (compare Run 3 with Run 4) did not influence the

formation of CNX. CNBr was only formed in Run 5B, after ozonation and incubation at pH 8.

The formation of CNBr by ozonation has also been reported in the literature (Krasner et al.

199 la).

Dissolved organic halogen. The most DOX was formed in Runs 3 and 4, at a Ck/N ratio

of 5/1 and an incubation pH of 8 (which is consistent with Task la results), with moving the

point of chloramination having little effect. In every case, Run IB, 2B, and 5B, incubating the

effluent sample at lower pH increased the concentration of DOX somewhat. Comparing Runs

1A and IB with Runs 2A and 2B, respectively, indicates that using a Cb/N ratio of 3/1 produced

somewhat less DOX than a C^/N ratio of 5/1. Comparing Runs 2A and 2B with Runs 5A and

5B, respectively, shows the positive influence of ozonation on destroying DOX precursor.

Finally, the DOX concentration was higher in Run 3 (65.4 ug C17L) as compared to Run

2B (44.1 ug C17L). The chloramination conditions of these runs were identical, except Run 3

was direct filtration without softening of a source water with a TOC concentration of 4.6 mg/L

and Run 2B involved softening of a source water only containing 2.5 mg/L of TOC. TOC

121

removal was 35 percent in the direct filtration run (i.e., effluent TOC of 3.0 mg/L), and although

TOC removal was not measured in Run 2B, traditionally it has not been high during the

softening of LAW. Thus, the major difference between the two runs was the TOC concentration.

Percentage of DOXAccounted for by the Measured DBFs

The percentage of DOX that was accounted for by the 12 measured DBFs ranged from

0.6 percent in Run 5 A to 45.1 percent in Run 1A. In three of the runs, Run 2A, 2B and 4, none

of the individual samples were complete enough to allow the calculation of a recovery

percentage (i.e., not all 12 DBFs were measured in any one sample set), so it was calculated

based on the average values of the 12 measured DBFs measured throughout the runs. The

relatively high concentration of HAA6 and the relatively low concentration of DOX in Run 1A

accounted for the higher percentage of DOX that was accounted for by the 12 measured DBFs in

this test.

Comparison With Task la and Ib Data

The data reported in Chapters 5 (Task la) and 6 (Task Ib) were used for comparison with

the Task 2 data. In Task la, preformed chloramines were added to untreated water, and in Task

Ib chlorine and ammonia were added to untreated water at various mixing intensities. Because

mixing was intense in the rapid mix portion of the pilot plants, the "high" mixing energy data

will be used for comparison to Task 2. Only two runs were performed where all of the

parameters could be compared to Task la and Ib data collected under a similar pH and Cb/N

ratio. In these two situations (Table 7.2), the data agreed fairly well, even though LAW was

tested at different points in time for these three experiments (Task la, Task Ib, and Task 2).

Note that for every situation except the CNX concentration incubated at pH 8, the concentrations

of the SDS DBFs were higher in the pilot plant effluent than in the Task Ib "high" mix

investigation. This may indicate that somewhat less mixing occurred in the pilot plant than in

the Task Ib batch tests. On the other hand, in Task 2, Run 1A and IB, the prechloraminated

water was held at pH 9.5 during the softening part of the treatment; thus, this high pH may have

122

affected some DBFs before the start of the SDS test on the pilot plant effluent (e.g., hydrolysis of

CNX at pH 9.5 before SDS testing at pH 8 in Run IB). This did not occur in the Task Ib study.

Lake Houston Water

The data from the eight individual runs are presented in Tables B.9 to B.I6 in Appendix

B. The data in Table 7.3 are a summary of the key average output values for all eight runs. This


of the effluent.


Dichloramine was present in the effluent samples at the end of the SDS test in the three

incubations conducted at pH 6, Runs 3B (41 percent), 4B (15 percent), and 5B (31 percent). A

little free chlorine was present after incubation of a few of the Run 1, Run 5 A, and Run 5B

Table 7.2

Comparison of Task 2 and Tasks la and Ib with data for Lake Austin water

TOC, mg/L

Br', mg/L

TTHMs, ug/L

HAA6, ug/L

CNX, ug/L

DOX, ug C17L

% DOX Accounted for

C12/N = 3/1Task 2

Run 1A*2.5

0.3

0.2

20.0

0.3

20.4

45.1

, Incubation pHIOTask la Task Ib

"High" Mix3.1

0.24

BDL

3.2

BDL

BDL

IND

3.1

0.24

BDL

6.3

BDL

11.5

14.3

C12/N = 3/1Task 2

Run IB*2.5

0.3

0.3

10.4

1.3

28.3

25.2

[, IncubationTask la

3.1

0.24

BDL

6.2

4.3

31.5

13.5

pH8Task Ib

"High" Mix3.1

0.24

BDL

9.3

1.7

23.3

10.6

* At pH 9.5 during treatment by lime softening BDL = Below detection limit. IND = Indeterminable, DOX concentration below detection limit.

123

Tabl

e 7.

3

Sum

mar

y of

Lak

e H

oust

on w

ater

pilo

t pla

nt r

esul

ts (

aver

age

valu

es)

C12

2d

2d

2d

2d

2d

2d

2d

%

Run

C

ondi

tions

C1

2/N

Inc.

D

ose

Tota

l C1

2 So

urce

Ef

f. R

emov

e SD

S SD

S SD

S SD

S SD

S SD

S SD

S D

OX

pH

mg/

L R

esid

ual

Dem

and

TOC

TO

C

TOC

TT

HM

H

AA

6 M

XA

A

DX

AA

TC

AA

C

NX

D

OX

A

ccou

nted

mg/

L m

g/L

mg/

L %

%

ug

/L

ug/L

ug

/L

ug/L

ug

/L

ug/L

ug

C17

L Fo

r**

1 A

mb.

Br,

Prec

hlor

am.,

3/1

8 9.

00

2.80

6.

20

4.5

2.06

* 54

3.

6 19

.9

0.5

18.5

0.

9 0.

3 10

4.2

6.4

Con

v. C

oag

2 A

mb.

Br,

Con

v. C

oag.

3/

1 8

8.00

2.

80

5.20

12

.3

3.95

68

4.

0 14

.1

BD

L 12

.5

1.6

10.6

10

8.1

6.5

Post

chlo

ram

inat

ion

» »

to

-^

3A

Am

b. B

r, Pr

echl

oram

., 3/

1 8

7.20

1.

50

5.70

10

.1

3.13

69

6.

3 23

.5

BD

L 21

.4

2.1

6.8

101.

6 10

.7

Enh.

Coa

g.

3B

Am

b. B

r, Pr

echl

oram

., 3/

1 6

7.20

1.

80

5.40

10

.1

3.13

69

5.

8 25

.7

BD

L 23

.5

2.1

9.8

112.

3 9.

5

Enh.

Coa

g.

4A

Am

b. B

r, En

h. C

oag.

, 3/

1 8

7.70

2.

80

4.90

10

.3

3.37

67

7.

3 23

.2

1.1

20.1

3.

3 1.

9 81

.9

14.4

Post

chlo

ram

inat

ion

4B

Am

b. B

r, En

h. C

oag.

, 3/

1 6

7.00

3.

00

4.00

10

.3

3.37

67

8.

3 5.

2f

BD

L 4.

1 J

0.6

20.7

§ 11

2.0

10.9

Post

chlo

ram

inat

ion

(con

tinue

s)

Tabl

e 7.

3 (c

ontin

ued)

2d

2d

2d

2d

2d

2d

2d

%

Run

C

ondi

tions

C1

2/N

Inc.

Cl2

Dos

e To

tal

C12

Sour

ce

Eff.

Rem

ove

SDS

SDS

SDS

SDS

SDS

SDS

SDS

DO

X

pH

mg/

L R

esid

ual

Dem

and

TOC

TO

C

TOC

TT

HM

H

AA

6 M

XA

A

DX

AA

TC

AA

C

NX

D

OX

A

ccou

nted

mg/

L m

g/L

mg/

L %

%

ug

/L

ug/L

ug

/L

ug/L

ug

/L

ug/L

ug

ClY

L Fo

r**

5A B

r Add

ition

, Pre

chlo

ram

., 3/

1 8

7.90

1.

70

6.20

9.

1 3.

14

65

41.4

39

.2

4.0

33.3

1.

9 18

.1

188.

0 19

.1

Con

v. C

oag.

5B

Br A

dditi

on, P

rech

lora

m.,

3/1

6 7.

90

1.80

6.

10

9.1

3.14

65

36

.1

34.4

3.

9 28

.8

1.7

21.5

20

3.0

16.4

Con

v. C

oag.

Note:

All

DB

F da

ta ro

unde

d to

one

dec

imal

pla

ce.

Dic

hlor

amin

e w

as 4

1 pe

rcen

t of

tota

l in

Run

3B

, 15

per

cent

of t

otal

in R

un 4

B, a

nd 3

1 pe

rcen

t of t

otal

in

Run

5B.

The

othe

r run

s ha

d ze

ro p

erce

nt d

ichl

oram

ine.

Con

vent

iona

l coa

gula

tion

rem

oved

54

perc

ent o

f sou

rce

wat

er T

OC

whe

n th

e so

urce

wat

er T

OC

con

cent

ratio

n w

as 4

.5 m

g/L

and

65

to 6

8 pe

rcen

t whe

n th

e so

urce

wat

er T

OC

was

9.1

to

12.3

mg/

L. E

nhan

ced

coag

ulat

ion

(1/3

mor

e al

um)

rem

oved

67

to 6

9 pe

rcen

t of t

he s

ourc

e w

ater

whe

n th

e so

urce

wat

er

TOC

con

cent

ratio

n w

as 1

0.1

to 1

0.3

mg/

L. T

hus,

conv

entio

nal c

oagu

latio

n ac

hiev

ed e

nhan

ced

coag

ulat

ion

TOC

rem

oval

per

form

ance

.

Am

b. =

am

bien

t

BD

L =

belo

w d

etec

tion

limit

DX

AA

= D

CA

A +

DB

AA

+ B

CA

A

coag

. = c

oagu

latio

n

conv

. = c

onve

ntio

nal

enh.

= e

nhan

ced

MX

AA

= M

CA

A +

MB

AA

prec

hlor

am. =

pre

chlo

ram

inat

ion

* Ave

rage

val

uef

Stan

dard

dev

iatio

n =

7.3

ug/L

; ran

ge =

1.0

ug/

L to

13.

7 ug

/L}

Ran

ge 1

.0 u

g/L

to 1

2.0

ug/L

§41

perc

ent C

NB

r**

On

mol

ar b

asis

samples, but the concentrations were only 0.3 mg/L or less. The total residuals varied from 1.5 to

3.0 mg/L, fairly close to the target of 2 mg/L, and the chlorine demand varied from 4.0 to 6.2

mg/L.


Trihalomethanes. The TTHM concentrations were less than 10 ug/L in all of the ambient

bromide runs. The highest TTHM concentrations occurred in Runs 5A and 5B (i.e., 41.4 and

36.1 ug/L, respectively), when the source water was spiked with bromide ion. Dibromochlo-

romethane and bromoform both were formed at both incubation pHs in the bromide-spiked runs.

A little bromine substitution did occur even when bromide ion was not added, where the ambient

bromide ion concentration was about 0.05 mg/L. Increasing the alum dose from 66 to 88 mg/L

in an attempt to enhance the coagulation process did not result in a decline in the SDS TTHM

concentrations.

The TOC removal in the "conventional" coagulation runs were: Run 1 54 percent, Run

2 68 percent, and Run 5 65 percent. Increasing the alum dose from the usual 66 mg/L to 88

mg/L, a 33 percent increase in coagulant (Runs 3A and 3B and 4A and 4B), resulted in 69

percent TOC removal in Runs 3A and 3B and 67 percent TOC removal in Runs 4A and 4B.

Higher doses of coagulant could not be used (without concurrent caustic addition) because of

insufficient alkalinity in the source water to buffer the acidic properties of the alum. Except for

Run 1, which had a relatively low source water TOC concentration (4.5 mg/L), the range of the

effluent TOC concentration was from 3.13 to 3.95 mg/L. The high removal percentages were

greater than called for in the M/DBP Rule in the enhanced coagulation section, even though

conventional alum doses were used. Moving the point of chloramination had no impact in this

set of runs.

Haloacetic acids. In Run 3A compared with 3B and Run 5A compared with 5B, the

incubation pH did not have a significant effect on 2d SDS HAA6 concentrations. Furthermore,

comparing Run 1 with 2 and Run 3A with 4A, the point of chloramination did not influence 2d

SDS HAA6 concentrations. Adding bromide ion in Runs 5A and 5B did increase the 2d SDS

HAA6 concentration from a typical range of 14.1 to 25.7 ug/L at ambient bromide ion

concentration to 34.4 to 39.2 ug/L for the bromide-spiked samples. Dichloroacetic acid (DCAA)

126

was the predominant HAA produced in the ambient-bromide samples, whereas trichloroacetic

acid (TCAA) was formed at relatively low levels. In the bromide-spiked samples, high

concentrations of DCAA, bromochloroacetic acid (BCAA) and dibromoacetic acid (DBAA)

were produced. In general, the DXAAs dominated the HAA6 formation, suggesting that

chloramines minimize TTHM and TCAA formation, but not that of DXAA.

With respect to 2d SDS HAA6, Run 4B was problematic. The 2d SDS HAA6

concentration was 13.7 ug/L in one test (which is comparable to that detected in other ambient-

bromide runs, 14.1 to 25.7 ^ig/L), whereas almost none of the HAAs were detected in the other.

All of the other HAA6 concentrations in this run suggest analytic problems.

Cyanogen halides. Changing from prechloramination to postchloramination resulted in a

large increase in the concentration of CNX from Runs 3B and 4B, whereas in comparing Runs

3A and 4A a decrease occurred. Although the concentration of CNX increased from Run 1 to

Run 2, the source water TOC concentration also increased by almost threefold. In general,

incubating the SDS samples at pH 8 rather than pH 6 resulted in less CNX being formed;

compare Runs 3A, 4A, and 5A with Runs 3B, 4B, and 5B. In Runs 5A and 5B, more CNBr was

formed than in the ambient bromide runs, except for Run 4B, in which a surprisingly high

amount of CNBr was formed in spite of only 0.05 mg/L bromide ion being present.

Dissolved organic halogen. Changing the point of chloramination from the source water

to the filtered water had little effect on the concentration of 2d SDS DOX formed. The small

decline that occurred when comparing Run 3A with 4A may have been because the water in Run

3A was at the low pH of the pilot plant (about 4.8) for nearly 2.5 hours plus the time elapsed

until the sample was returned to the laboratory for pH adjustment. In Run 4A, as the water

exited the filter, it was pH adjusted and chloraminated. Thus, chloramines were never in this

sample at acidic pH.

When free chlorine is used (as has been shown in other studies), changing the point of

chlorination has a significant influence on DOX formation. Possibly the kinetics of DOX

formation during chloramination are relatively slow compared to the time it takes to remove the

TOC; thus, the point of chloramine application may be less critical.

As noted before, the two coagulation conditions (conventional versus enhanced) were not

that different. Samples incubated at pH 6 produced somewhat more DOX than samples

127

incubated at pH 8. Fleischacker and Randtke (1983) also showed that lower incubation pH

favors the formation of DOX.

Runs 5A and 5B, in which bromide ion was added to the source water, produced the most

2d SDS DOX, even though the DOX test underreports dissolved organic bromine (DOBr)

because the test reports all halogen measured as chloride. In the ambient-bromide samples, the

DOX concentration ranged from 81.9 to 112.0 ^g C17L, whereas in the bromide-spiked samples

the DOX concentration was 188.0 to 203.0 ng C17L. As shown with the THM analyses in Runs

5 A and 5B, more bromine was substituted when the bromide ion level was raised.

Percentage of DOX Accounted for by the Measured DBFs

Relatively low percentages of DOX were accounted for by the 12 measured DBFs in

these samples, except for Runs 5A and 5B (bromide-spiked samples), in which the percentages

were somewhat higher. In the presence of excess bromide ion, the TTHM, HAA6 and CNX

concentrations were relatively high (the numerator in the calculation), and the DOBr was under-

reported (therefore the DOX the denominator in the calculation is unnaturally low); thus the

percent recoveries were a little higher. All percentages were, however, based on molar

concentrations to minimize problems associated with bromine-substituted DBF formation when

compared to DOX measurement on a chloride basis.

Comparison With Task la and Ib Data

Six runs were performed where all of the parameters could be compared to Task la data

(adding preformed chloramines to untreated water) and three runs could be compared to Task Ib

data (simultaneous addition of chlorine and ammonia with "high" mixing energy) collected

under similar incubation pH and Cla/N ratios. In these comparisons (Table 7.4), the largest area

of variation was the CNX data for Runs 2, 3 A, 4B and 5B. CNX formation was more variable

than that of the other DBFs. Explaining the difference in the HAA6 concentration in Task la as

compared to Run 4B (which was anomalous when compared to the other Task 2 runs and

appeared to have analytic problems) is difficult. The rest of the comparisons were fairly good,

128

to

Tab

le 7

.4

Com

pari

son

of T

ask

2 da

ta w

ith T

asks

la

and

Ib d

ata

for

Lak

e H

oust

on w

ater

TOC

* m

g/L

TTH

M u

g/L

HA

A6

ug/L

CN

Xug

/L

DO

X u

g C1

VL

% D

OX

acc

ount

ed

for§

Task

2

Run

1

4.5

3.6

19.9

0.4

104.

2

6.4

Task

2

Run

2

12.3

4.0

14.1

10.6

108.

1

6.5

C12/N

= 3

/1,

Task

2

Run

3A

Enha

nced

Coa

gula

tion

10.1

6.3

23.5

6.8

101.

6

10.7

,pH

8 Task

4

Run

4A

Enha

nced

Coa

gula

tion

10.3

7.3

23.3

1.9

81.9

14.4

Cl2/N

= 3

/l,p

H6

Task

la 9.2

2.1

28.4

2.5

65.5

12.8

Task

Ib 6.7

1.1 26.6

1.5

99.8

5.6

Task

2

Run

3B

Enha

nced

Coa

gula

tion

10.1

5.8

25.7

9.8

112.

3

9.5

Task

2

Run

4B

Enha

nced

Coa

gula

tion

10.3

8.3

5.2T

20.7

J

112.

0

10.9

Task

la 9.2

5.3

38.5

8.6

174.

1

4.0

C12/N

=3/1

,

Task

2

Run

5B

9.1

36.1

34.4

21.5

203.

0

16.4

pH 6

, +B

r-

Task

Ib 6.7

25.0

58.6

6.6

289.

5

11.3

* So

urce

wat

er T

OC

con

cent

ratio

n

t St

anda

rd D

evia

tion

= 7.

3 ug

/L, R

ange

=1.

0 to

13.

7 ug

/L}

41 p

erce

nt C

NB

r

§ O

n a

mol

ar b

asis

considering that these tests were performed on source water sampled at different points in time

and that the method of applying the chloramines was different.


The data from the ten individual runs are presented in Tables B. 17 to B.26 of Appendix

B. The data in Table 7.5 are a summary of the key average output values for all ten runs. This


of the effluent.


No dichloramine was present in any of the effluent samples at the end of the SDS test.

Also, most of the total residuals were slightly less than the target residual of 2 mg/L. The data in

Table 7.5 show a slight increase in chlorine demand in the runs that included biofiltration, 3A

and 4A, when compared to the companion runs with conventional filtration, 3B and 4B.


Trihalomethanes. The TTHM concentrations were very low in seven of the ten runs (< 5

ug/L), Runs 3A and 3B, 4A and 4B (including repeats) and Run 5. These were the runs in which

ozone was the primary disinfectant and chloramines were added post-filtration, albeit by bench-

scale addition, and the one run with a Ch/N ratio of 3/1.

In Run 1 and Run 1 repeat (5/1 Cb/N ratio), the TTHMs were much higher than

produced by preformed chloramines in Task la (24 to 40 |j.g/L versus below detection limit) and

may have been caused by localized free chlorine concentrations in the pilot plant. This would

also be consistent with the pilot plant operator's observation that the total chlorine residuals were

difficult to adjust and even decreased when the free chlorine dose increased (indicating that the

maximum (5/1 C^/N ratio) on the breakpoint curve had been passed). The Run 1 repeat TTHM

130

Tabl

e 7.

5

Sum

mar

y of

Cal

ifor

nia

Stat

e Pr

ojec

t wat

er p

ilot p

lant

res

ults

(av

erag

e va

lues

)

Run

C

ondi

tions

C1

2/N

SDS

CI2

Tota

l C1

2 So

urce

2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S %

DO

XpH

D

ose

Res

. D

eman

d TO

C

TTH

M

HA

A6

MX

AA

D

XA

A

TCA

A

CN

X

CNC1

C

NB

r D

OX

A

ccou

nted

for*

m

g/L

mg/

L m

g/L

mg/

L ug

/L

ug/L

ug

/L

ug/L

ug

/L

ug/L

ug

/L

ug/L

ug

C17

L

1 A

mbi

ent B

r, Pr

eNH

2Cl,

Con

curr

ent A

dditi

on, A

lum

1 R

epea

t

2 A

mbi

ent B

r, A

lum

, Po

stN

H2C

l w/d

elay

f

3A A

mbi

ent B

r, Pr

eO3 (

0.35

mg/

LR

esid

ual),

Bio

filtra

tion,

Pos

tNH

2Cl

3B

Am

bien

t Br,

PreO

3 (0.

35 m

g/L

Res

idua

l),C

onve

ntio

nal f

iltra

tion,

Pos

tNH

2Cl

5/1

8 2.

16

1.26

0.

90

5/1

8 2.

95

1.63

1.

32

5/1

8 N

A

1.60

N

A

3.2

23.5

10

.2

0

2.9

39.6

15

.0

0

3.2

44.6

12

.0

0

10.2

0

12.1

5.

2 6.

9 44

.0

45.4

15.0

0

13.8

4.

3 9.

5 73

.6

41.1

11.0

1.

0 20

.6

10.7

J 9.

9 10

9.6

30.4

5/1

8 2.

50

1.55

0.

95

3.2

3.0

2.4

0.4

2.1

0 7.

9 6.

6 1.

3 54

.4

6.3

5/1

8 2.

50

1.68

0.

82

3.2

2.8

3.6§

2.

4 1.

8 0

9.7

9.0*

* 0.

7 56

.7

5.8

4A A

mbi

ent B

r, Pr

eO3 (

0.55

mg/

L 5/

1 8

2.60

1.

64

0.96

Res

idua

l),B

iofil

tratio

n, P

ostN

H2C

l 4A

Rep

eat

5/1

8 2.

60

1.52

1.

08

2.9

3.4

2.6

0

3.0

4.4

3.3

0

2.6

0 5.

6 4.

5 1.1

24

.3

17.7

3.3

0 5.

3 4.

5 0.

8 42

.6

13.1

(con

tinue

s)

Tabl

e 7.

5 (c

ontin

ued)

Run

C

ondi

tions

C1

2/N

SDS

C12

Tota

l C1

2 So

urce

2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S 2d

SD

S %

DO

X

pH

Dos

e R

es.

Dem

and

TOC

TT

HM

H

AA

6 M

XA

A

DX

AA

TC

AA

C

NX

CN

C1

CN

Br

DO

X

Acc

ount

edfo

r*

mg/

L m

g/L

mg/

L m

g/L

ug/L

ug

/L

ug/L

ug

/L

ug/L

ug

/L

ug/L

ug

/L

ug C

1"/L

4B

Am

bien

t Br,

PreO

3 (0.

55 m

g/L

Res

idua

l),C

onve

ntio

nal

filtra

tion,

Post

NH

2Cl

4B

Rep

eat

5 A

mbi

ent B

r, Pr

eNH

2Cl,

Con

curr

ent A

dditi

on, A

lum

5/1

8 2.

60

1.81

0.

79

2.9

3.8

2.1

02.

10

5.1

5/1

8 2.

60

1.74

0.

86

3.0

4.6

5.7

0.5

5.2

0 6.

2

3/1

8 3.

20

2.73

0.

47

NA

1.

4 12

.7

1.5

11.2

0

4.0

4.4

0.7

44.9

12

.6

5.4

0.9

39.0

15

.3

3.0

1.0

44.4

6.

2

Note:

All

DB

F da

ta ro

unde

d to

one

dec

imal

pla

ce.

No

dich

lora

min

e in

any

of t

he s

ampl

es.

Val

ues

belo

w d

etec

tion

limit

are

liste

d as

zer

o.

DXAA = DCAA + DBAA + BCAA

MXAA = MCAA + MBAA

NA

= n

ot a

vaila

ble

Post

NH

2C1

= po

stch

lora

min

atio

n

Pre

NH

2C1

= pr

echl

oram

inat

ion

Pre

O3=

pre

ozon

atio

nR

es. =

resi

dual

*On

a m

olar

bas

ist

Chl

orin

e ad

ded

first

, the

n am

mon

ia

J R

ange

= 5

.4-1

7.5

ug/L

§ St

anda

rd d

evia

tion

= 1.

4 u.

g/L

**R

ange

= 5

.9-1

4.1

ug/L

results were even higher than the original Run 1 by approximately 70 percent. The variation

may have been caused by differences in chloramine demand (0.9 and 1.3 mg/L in Run 1 and Run

1 repeat, respectively), source water changes, mixing, or a combination of these factors. The

Cb/N ratio for Runs 1 and 5 were 5/1 and 3/1, respectively, and may account for the higher

TTHM concentrations that occurred in Run 1 and Run 1 repeat because the Task 1 a data showed,

in general, more TTHM formation as the C^/N ratio was increased. Previous bench-scale work

at the MWDSC (Barrett et al. 1985) has shown that free chlorine exists past the maximum of the

breakpoint curve and before the breakpoint for short contact times near a 5/1 Cb/N ratio, as in

Run 1 and Run 1 repeat, whereas no free chlorine is present at a 3/1 Cb/N ratio, as in Run 5 (see

Figure 2.1).

In Run 2, chlorine was added to the sedimentation basin effluent and ammonia was added

approximately one minute later at the filter influent. This short period of free chlorination

caused the TTHM concentration to increase in Run 2 (44.6 ug/L) to even more than in Runs 1

and 1 repeat.

Haloacetic acids. The HAA6 concentrations were highest in Runs 1, 1 repeat, 2, and 5

(Table 7.5). Ozonation appeared to lower the HAA6 formation in Runs 3 and 4, but the

influence of biofiltration was difficult to assess because the concentration of HAA6 was so low.

Similar HAA6 concentrations were formed in Runs 1 and 1 repeat and Run 5 (similar treatment

scheme), although Run 5 was conducted at a lower Cb/N ratio (3/1) than Runs 1 and 1 repeat

(5/1). As was observed for LAW and LHW, the formation of the dihalogen-substituted HA As

(i.e., DCAA, BCAA, and DBAA) was controlled less by chloramination compared to the

formation of TCAA.

Cyanogen halides. The concentration of CNX was the highest in Run 2, where a short

period of free chlorine existed. Krasner et al. (1991b) observed that a short free chlorine contact

before chloramination produced more CNC1 when compared to concurrent addition of chlorine

and ammonia. Note, however, that the increase in CNC1 concentration in Run 2 (delay between

the addition of chlorine and ammonia) was inconsistent from sample to sample, ranging from 5.4

to 17.5 ug/L.

CNC1 was typically at 4 to 7 ug/L in each run, except for Run 2 (with sequential addition

of chlorine and ammonia) and Run 3B (with ozone and no biofiltration). Pederson et al. (1995)

found that CNC1 formed from the reaction of monochloramine with formaldehyde.

133

Formaldehyde is formed by ozone but can be removed during biofiltration (Krasner et al. 1993).

Thus, ozonation without biofiltration has the potential to increase CNC1, which was observed in

Run 3B but not 4B.

In Runs 1 and 2, CNBr was formed at levels of 6.9 to 9.9 ug/L. In Run 5, at a lower

Cb/N ratio (3/1), the CNBr concentration was only 1.0 ug/L. In Runs 3 and 4 (with ozonation)

CNBr was found at 1.3 to 0.7 ug/L. CNBr can be formed by ozone but can be removed in a

biologically active filter (Krasner et al. 1990). Possibly CNBr was formed during ozonation,

then it was removed during biofiltration, and, finally, less was formed during postchloramination

because the precursors had already been used.

Dissolved organic halogen. The period of free chlorination that existed in Run 2

produced the highest concentration of DOX, 109.6 ug C17L (Table 7.5). The increase in ozone

dose between Runs 3A and 3B and Runs 4A and 4B resulted in a decrease in DOX concentration

(54.4 to 56.7 ug C17L compared to 24.3 to 44.9 ug C17L caused by destruction of precursor),

but biodegrading the sample prior to SDS incubation did not remove any more of the DOX

precursors; compare Runs 3A with 3B and Runs 4A, 4A repeat with 4B, 4B repeat. Runs 1 and

5, in which only the Cb/N ratio changed, produced very similar 2d SDS DOX concentrations.

Run 1 repeat, however, produced a much higher DOX concentration than Run 1 (73.6 vs. 44.0

ug C17L). As noted above, the chloramine demand was somewhat higher for Run 1 repeat.

Percentage DOX Accounted for by the Measured DBFs

The recovery of DOX in the 12 measured DBFs was relatively low for Runs 3 A, 3B, 4A,

4A repeat, 4B, 4B repeat, and 5, ranging from 5.8 to 17.7 percent, because of the low

concentrations of the 12 measured DBFs. In Runs 1, 1 repeat, and 2, where higher concen

trations of the 12 measured DBFs were detected, the amount of DOX accounted for by the 12

measured DBFs was correspondingly higher, 30.4 to 45.4 percent.

Comparison With Task la and Task Ib Data

Only one run (Run 5, where the chlorine and ammonia solutions were simultaneously

added to the influent water) was performed where all of the parameters could be compared to

134

Task la and Task Ib data (adding preformed chloramines to untreated water) collected under a

similar pH and Cb/N weight ratio. For this case (Table 7.6), good agreement was obtained for

THM and DOX for both Task la and Task Ib and for Run 5. Although the HAA6 concentration

in Run 5 was about two times the concentration in Tasks la and Ib, the bromide ion

concentration in Run 5 was almost three times the concentration in Tasks la and Ib.

Two tests also allowed the comparison of TTHM and DOX concentrations, Run 1 and

Run 1 repeat, with Task la. The most significant difference was the higher TTHM

concentrations in Run 1 and Run 1 repeat compared to Task la, which was discussed earlier as

possibly caused by poor mixing conditions in the pilot plant. Note that the TTHMs for Run 1

repeat (39.6 ng/L) were almost the same as the concentrations formed in Run 2 (44.6 \ig/L, see

Table 7.31), in which ammonia addition was deliberately delayed to show the influence of

sequential addition and the presence of some free chlorine.

DISCUSSION

Only the three runs with incubation pHs of 6 produced any dichloramine. Review of

Tables 7.2, 7.4, and 7.6 indicates that where applicable, the Task 2 data agreed fairly well with

the Tasks la and Ib (high mixing intensity) data, with a few notable exceptions. This agreement

occurred in spite of Tasks la and Ib being conducted on source water and Task 2 data being

collected on treated and filtered water. Table 7.7 repeats all of the summary data from Tables

7.2, 7.4, and 7.6 in a single table for easy comparison of the key Task 2 data.

Trihalomethanes

All of the filter effluents produced 2d SDS TTHM concentrations that would meet the

current MCL (0.10 mg/L) and the proposed Stage 1 MCL of 0.080 mg/L. All but two runs,

LHW Run 5A (bromide addition and pH 8 incubation) and CSPW Run 2 (one minute delay in

adding the ammonium chloride), would meet the proposed Stage 2 MCL of 0.040 mg/L. In

addition, LHW Run 5B and CSPW Run 1 repeat produced TTHM levels too close to the

proposed Stage 2 MCL to reliably assure potential compliance under these operating regimes.

135

Table 7.6

Comparison of Task 2 with Tasks la and Ib data for California State Project water

Cl2/N3/l,pH8

TOC, mg/L

Br", mg/L

TTHMs, ng/L

HAA6, ug/L

CNX, jig/L

DOX, ug C17L

% DOXAccounted for

Task 2 Run5

NR

0.28

1.4

12.7

4.0

44.4

6.2

Task la

2.4

0.10

0.7

4.9

2.8

42.5

4.3

Task Ib

2.4

0.10

BDL

6.4

NR

31.1

NA

Cl2/N5/l,pH8

Task 2 Runl

3.2

0.23

23.5

10.2

12.1

44.0

45.4

Task 2 RunlRepeat

2.9

0.23

39.6

15.0

13.8

73.6

41.4

Task la

2.4

0.10

BDL

NR

NR

46.1

NA

BDL = Below detection limits NA = Not applicable NR = Not run

The other variables studied had little measurable influence. With respect to TTHM formation,

two conditions are of paramount importance, the rapid reaction that takes place when bromide

ion is present or when free chlorine is present. Thus, rapid mixing of the chlorine and ammonia

is important if TTHM formation is to be minimized.

Haloacetic Acids

In LHW, incubation pH (i.e., pH 8 vs. 6) did not seem to have much effect; compare

Runs 3A and 3B and Runs 5A and 5B. Except for LHW Runs 5A and 5B (bromide addition),

all of the filter effluents from all three waters produced 2d SDS HAA6 concentrations that would

meet both the proposed Stage 1 (0.060 mg HAA5/L) and Stage 2 MCL (0.030 mg HAA5/L),

even though a sixth HAA (BCAA) was included in the arithmetic sum. In addition, LHW Runs

136

Table 7.7

Summary of pilot plant data for all three waters tested

Run Conditions C12/N

Ratio

Inc.

PH

Total

Res.

mg/L

2d SDS 2d SDS DXAA/ 2d SDS CNC1/ 2d SDS % DOX

TTHM HAA6 HAA6 CNX CNX DOX Account-

ug/L ug/L Ratio ug/L Ratio ug C1VL ed for

Lake Austin water (Table 7.9) *

1A

IB

2A

2B

3

4

5A

5B

Ambient Br, Prechloram.




Ambient Br, Direct Fill., Prechloram.

Ambient Br, Direct Filt.,Postchloram.

Ambient Br, Ozone, Postchloram.

Ambient Br, Ozone, Postchloram.

3/1

3/1

5/1

5/1

5/1

5/1

5/1

5/1

10

8

10

8

8

8

10

8

2.3

2.4

2.5

2.5

1.8

1.7

2.0

2.1

0.2

0.3

1.9

1.9

7.2

1.1

BDL

1.5

20.0

10.4

12.2

9.6

11.6

10.2

0.8

1.4

0.7

1.0

1.0

1.0

1.0

1.0

1.0

1.0

0.3

1.3

0.0

1.5

3.3

4.1

1.2

6.2

1.0

1.0

NA

1.0

1.0

1.0

1.0

0.7

20.4

28.3

32.3

44.1

65.4

58.8

28.2

30.3

45.1

25.2

16.6f

ll.lf

16.2

6.2t

0.6

6.1

Lake Houston water (Table 7.19) J

1

2

3A

3B

4A

4B

5A

5B

Ambient Br, Prechloram., Conv. Coag.

Ambient Br, Conv. Coag. Postchloram.

Ambient Br, Prechloram., Enh. Coag.

Ambient Br, Prechloram., Enh. Coag.

Ambient Br, Enh. Coag., Postchloram.

Ambient Br, Enh. Coag., Postchloram.

Br Addition, Prechloram., Conv. Coag.

Br Addition, Prechloram., Conv. Coag.

3tol

3tol

3tol

3tol

3tol

3tol

3 to 1

3tol

8

8

8

6

8

6

8

6

2.8

2.8

1.5

1.8

2.8

3.0

1.7

1.8

3.6

4.0

6.3

5.8

7.3

8.3

41.4

36.1

19.9

14.1

23.5

25.7

23.2

5.2§

39.2

34.4

0.9

0.9

0.9

0.9

0.9

0.8

0.8

0.8

0.3

10.6

6.8

9.8

1.9

20.7

18.1

21.5

1.0

0.9

1.0

0.7

1.0

0.6

0.1

0.3

104.2

108.1

101.6

112.3

81.9

112.0

188.0

203.0

6.4

6.5

10.7

9.5

14.4

10.9

19.1

16.4

(continues)

137

Table 7.7 (continued)

Run Conditions C12/N Inc. Total 2d SDS

Ratio pH Res. TTHM

mg/L ug/L

2dSDS DXAA/ 2d SDS

HAA6 HAA6 CNX

ug/L Ratio ug/L

CNC1/ 2dSDS %DOX

CNX DOX Account-

Ratio ug C1VL ed for

California State Project water (Table 7.31) **

1

1

2

3A

3B

4A

4A

4B

4B

5

Ambient Br, PreNH2Cl, Concurrent

Addition, Alum

Repeat

Ambient Br, Alum, PostNH2Cl w/ delay

Ambient Br, PreO3 (0.35mg/L Res.),

Biofilt., PostNH2Cl


No Biofilt., PostNH2Cl


Biofilt., PostNH2Cl

Repeat


No Biofilt., PostNH2Cl

Repeat

Ambient Br, PreNH2Cl, Concurrent

Addition, Alum

5tol

5tol

5tol

5tol

5tol

5tol

5tol

5tol

5tol

3tol

8

8

8

8

8

8

8

8

8

8

1.3

1.6

1.6

1.8

1.7

1.6

1.5

1.8

1.7

2.7

23.5

39.6

44.6

3.0

2.8

3.4

4.4

3.8

4.6

1.4

10.2

15.0

12.0

2.4

3.6JJ

2.6

3.3

2.1

5.7

12.7

1.0

1.0

0.9

0.9

0.5

1.0

1.0

1.0

0.9

0.9

12.1

13.8

20.6

7.9

9.7

5.6

5.3

5.1

6.2

4.0

0.4

0.3

o.stt0.8

0.9§§

0.8

0.9

0.9

0.9

0.8

44.0

73.6

109.6

54.4

56.7

24.3

42.6

44.9

39.0

44.4

45.4

41.1

30.4

6.3

5.8

17.7

13.1

12.6

15.3

6.2

BDL = below detection limit

biofilt. = biofiltration

coag. = coagulation

conv. = conventional

DXAA = DCAA + DBAA + BCAA

enh. = enhanced

filt. = filtration

inc. = incubation

NA = not available

postchloram. = postchloramination

postNH2Cl = postchloramination

prechloram. = prechloramination

preNH2Cl = prechloramination

preO3 = preozonation

res. = residual

*Dichloramine 0% of total residual. Runs 1A, IB, 2A, 2B, 5A, and 5B involved lime softening

*( Calculated based on average values

{Dichloramine was 41% of total in Run 3B, 15% of total in Run 4B, and 31% of total in Run

5B. The other runs had 0% dichloramine.

§Standard deviation = 7.3 ug/L; range = 1.0 to 13.7 ug/L

**A11 data rounded to one decimal place

ttCNCI range = 5.4 to 17.5 ug/L

tJStandard deviation = 1.4 ug/L

§§CNCI range = 5.9 to 14.1 ng/L

138

3A, 3B, and 4A produced HAA6 levels too close to the proposed Stage 2 MCL to reliably assure

potential compliance under these operating regimes.

Ozonation in LAW Runs 5A and 5B and CSPW Runs 3A, 3B, 4A, 4B, 4A repeat, and 4B

repeat altered the HAA6 precursor material including the inorganic precursor bromide so that

significantly lower concentrations of 2d SDS HAA6 were formed. The other variables studied

had little measurable influence.

The ratio of (DCAA+DBAA+BCAA)/HAA6 was consistently high in all runs in all three

waters (0.7 to 1.0), except for Run 3B in CSPW, where the low (DCAA+DBAA+BCAA)/HAA6

ratio may have been caused by the high standard deviation in the HAA6 data. These high

(DCAA+DBAA+BCAA)/HAA6 ratios indicate that chloramines are less able to control the

dihalogen-substituted haloacetic acids as compared to the monohalogen-substituted HAAs and

TCAA. During the ozonation of fulvic acid, Reckhow and Singer (1984) observed that TCAA

precursors were destroyed whereas the precursors of DCAA were not. This again indicates that

the precursors of TCAA and DCAA are different.

Cyanogen Halides

When comparing higher and lower incubation pHs in LAW and LHW, the lower

incubation pH always produced more 2d SDS CNX; compare LAW Runs 1A and IB, 2A and

2B, and 5A and 5B and LHW Runs 3A and 3B, 4A and 4B, and 5A and 5B. In LAW, the higher

incubation pH of 10 produced low CNX concentration because of base-catalyzed hydrolysis. In

LHW, in which the incubation pHs were 6 and 8, hydrolysis should have been less problematic.

Compared to data from other runs, high 2d SDS CNX concentrations (approximately 20 ng/L)

were produced from LHW Runs 4B (a postchloramination run with an incubation pH of 6) and

CSPW Run 2 (with sequential chlorine and ammonia addition) and in LHW Run 5A and 5B, in

which some additional bromide ion was spiked. The CNC1/CNX ratio showed that in most

cases, the CNX was dominated by CNC1. The relatively high concentration of CNBr was

expected in LHW Runs 5A and 5B, as bromide ion was added. Likewise, moderate amounts of

CNBr in CSPW in Run 1 and Run 1 repeat are consistent with the moderate bromide ion

concentration (0.23 ug/L). The lower CNBr concentrations in CSPW Runs 3A, 4A, and 4A

repeat are consistent with the formation of CNBr and the subsequent removal through

139

biofiltration. The variability of the CNC1 concentrations in CSPW Run 2 and Run 3B may have

influenced the CNC1/CNX ratio.

Dissolved Organic Halogen

When comparing higher and lower incubation pH levels in LAW (pH 10 versus pH 8)

and LHW (pH 8 versus pH 6), the lower incubation pH always produced somewhat more 2d

SDS DOX; compare LAW Runs 1A and IB, 2A and 2B, and 5A and 5B and LHW Runs 3A and

3B, 4A and 4B, and 5A and 5B. The one minute delay in adding the ammonium chloride in

CSPW Run 2 resulted in an increase in the concentration of 2d SDS DOX. In some cases

moving the point of chloramination to after filtration resulted in a slightly lower 2d SDS DOX

(compare LHW Run 3A with 4A), but this trend was not seen in other runs (see below). The

addition of bromide ion in LHW Runs 5 A and 5B resulted in the highest measured 2d SDS DOX

concentration (188.0 to 203.0 ug C17L). Increasing the coagulant dose from 66 mg alum/L to 88

mg alum/L had little effect on the resulting 2d SDS DOX concentration (compare LHW Run 1

with Run 3A and LHW Run 2 with Run 4A), as both coagulant doses achieved similar removals

of TOC, removals that would be defined as enhanced coagulation.

When comparing LAW Runs 2B and 5B, in which both runs involved softening and

chloramination at pH 8, ozone had an effect on DOX formation (lowered the DOX concentration

from 44.1 ug C17L to 30.3 ug C17L). Less of an effect from ozone was observed, however, for

LAW Runs 2A and 5A, in which the incubation pH was 10. Also, when comparing CSPW Runs

3A and 3B with CSPW Runs 4A and 4B, the higher ozone dose decreased the 2d SDS DOX

concentration further.

For all of the calculated percentages of DOX accounted for by the 12 measured DBFs on

a molar basis, the data ranged from 0.6 percent to 45.4 percent. The median value was 12.6

percent. This means that a relatively small fraction of the halogen-substituted compounds being

formed by chloramines can be measured by common techniques.

140

Point of Chloramine Application

Four sets of runs were performed where the only operational difference was the point of

chloramine application, either in the source water (precloramination) or in the filtered water

(postchloramination). The data collected in these four sets of runs (Table 7.8), demonstrated

that, for most of the DBFs measured, the point of chloramine application had little effect on the

resulting concentration after two days. Although rate of formation studies were not performed

on LHW and LAW, apparently the precursor in those waters is so relatively unreactive that the

untreated water can be chloraminated without increasing the 2-day SDS concentration, when

compared to chloramination after some TOX removal. Figure 56 in Symons et al. (1981)

demonstrates this effect graphically.

Table 7.8

Comparison of prechloramination and postchloramination

Run

LAW

3

4

LHW

1

2

3A

4A

3B

4B

Conditions

Prechloramination

Postchloramination

Prechloramination

Postchloramination

Prechloramination

Postchloramination

Prechloramination

Postchloramination

C12/N

5/1

5/1

3/1

3/1

3/1

3/1

3/1

3/1

SDSpH

8

8

8

8

8

8

6

6

TOCmg/L

4.6

2.8

4.5

4.0

10.1

3.4

10.1

3.4

TTHMug/L

7.2

1.1

3.6

4.0

6.3

7.3

5.8

8.3

HAA6 "g/L

11.6

10.2

19.9

14.1

23.5

23.2

25.7

5.2+7.3

CNXug/L

3.3

4.1

0.3

10.6

6.8

1.9

9.8

20.7

DOX ug C17L

65.4

58.8

104.2

108.1

101.6

81.9

112.3

112.0

141

CONCLUSIONS

In conclusion, based on these data, preozonating, adding well mixed chlorine and

ammonia simultaneously, and keeping the pH of chloramination as high as possible would seem

to be the best prescription for treatment to control the concentrations of all of the DBFs measured

(see LAW Runs 5A and 5B and CSPW Run 4B). Location of the chloramination step was not

important because mixing at large scale would probably be more vigorous than at small scale, the

DBF data collected here may somewhat overestimate what might be expected in the field.

Insufficient data were collected in Task 2 to provide any conclusions on the influence of Cli/N

ratio on DBF formation; however, that parameter was well studied in Task la, the results of

which indicated that lower Cb/N ratios were advantageous.

142

CHAPTER 8

GEOGRAPHICALLY DIVERSE WATERS—TASK 3

OBJECTIVE

The objective of Task 3 was to validate the results observed in the three primary study

waters (from Tasks 1 and 2) in diverse waters nationwide. The waters studied were selected so

as to comprise a representative group. Geographical representation in itself was insufficient, as

many water quality parameters that affect chloramine DBF formation (e.g., concentrations of

TOC and bromide, ambient water pH, elevated pH levels during lime softening) transcend

geographical location.

The Task 3 waters were evaluated at bench and full scale. In addition, historical

distribution-system data were requested. The bench-scale tests represented an opportunity to

evaluate the effects of water quality parameters and chloramination operating conditions on DBF

formation. The current and historical distribution-system data provided (1) a comparison of full-

scale findings to bench-scale results and (2) information on DBF exposure with current and

historical chloramination practices.


Source Waters Studied

Studies were conducted on each of five waters nationwide: a midsouth lake/groundwater

supply, the Mississippi River, the Biscayne Aquifer, a northeastern creek, and a Pacific

Northwest lake. The midsouth water supply studied is very high in bromide (i.e., 1.500 to 3000

|j.g/L), and the Biscayne Aquifer is very high in TOC (i.e., 9 to 17 mg/L). On the other hand, the

Pacific Northwest lake is very low in TOC (i.e., 1.1 to 2.2 mg/L) and contains very little bromide

(e.g., 7 Mg/L). In addition, that water is distributed at a relatively low pH (i.e., 6.4 to 6.9), and

the local utility that uses this source water has historically applied chloramines at a Cla/N ratio of

7/1. The Biscayne Aquifer and the Mississippi River water are both treated by lime softening

(up to pH levels of 10.1 and 9.4, respectively). The northeastern utility conventionally treats a

143

surface water with average TOC and bromide levels (i.e., 2.0 to 4.7 mg/L TOC, 50 ug/L

bromide).

Bench-Scale Studies

Each of the Task 3 waters were subjected to three sets of chloramination conditions at

bench scale (Table 8.1); these conditions were similar to those used in Task la to study the three

primary waters. One or two of these C^/N ratios and pH conditions were selected for bench-

scale testing of the Task 3 waters to match the current full-scale treatment, historical full-scale

treatment, or both of each water. The other conditions (total of three per source water) were

selected to provide some contrast for the water quality parameters that were of most interest for

each water in the study.

In each Task 3 test, preformed chloramines were added to untreated source water

adjusted to the pH of interest. (In each of the following tables, the free-chlorine dose used in

preparing the preformed chloramines is provided, along with the Cb/N ratio. The denominator

in the Cla/N ratio was based upon the ammonia-nitrogen concentration of the ammonium

chloride used in preparing the preformed chloramines; thus, the ratio was based on a calculated

value.) These chloraminated samples were stored at room temperature (22 C) for a 48-h period.

A sufficient amount of chloramines was added to each sample so that the final residual (after 48

h) was approximately 2 to 3 mg/L. This created a 2-d SDS value for each parameter measured.

A target 48-h total residual of 2 mg/L was chosen for Task 3, as this proved to be (1) ideal based

on Task 1 and 2 testing and (2) representative of conditions used in typical full-scale

chloraminated distribution systems nationwide.

Full-Scale Studies/Historical Data

A distribution-system sample from each of the Task 3 utilities was collected to obtain

full-scale data. In addition, one year of historical, seasonal (quarterly) THM data was requested.

If the utility had made a major change in chloramination practices in recent history, one year of

144

Table 8.1

Chloramination parameters for bench-scale studies of Task 3 waters

Source Water

Midsouth water

Mississippi River

Biscayne Aquifer

Northeastern creek

Pacific Northwest lake

Batch Number

1

2

3

1

2

3

1

2

3

1

2

3

1

2

3

C12/N Ratio*

5/1

5/1

5/1

3/1

5/1

5/1

3/1

5/1

5/1

3/1

5/1

5/1

7/1

5/1

5/1

PH

6

8

10

8

8

10

10

10

8

8

8

6

6

6

8

*Cl2/N ratio of preformed chloramines.

additional data was requested that represented the previous chloramination conditions. The

current distribution sample, as well as the historical data, represented an opportunity to (1)

evaluate the effects of water quality parameters and chloramination operating conditions beyond

the matrix of elements studied in Task la (e.g., at different pH or Cb/N ratios or both, with more

than one stage of chlorination/chloramination) and (2) provide a comparison of full-scale data to

bench-scale experiments.

Because the operating conditions of some utilities were somewhat different than the

values of these parameters in Task la, complete one-to-one comparisons between full-scale and

bench-scale Task 3 data were not always possible. Instead, the full-scale data emphasize actual

145

DBF occurrence levels, whereas the bench-scale studies provided an opportunity to validate the

observations made during the Task la bench-scale testing of the three primary waters. Also,

some of the source waters contained other sources of nitrogen in addition to the ammonia added

for chloramination (e.g., source-water ammonia). Thus, the C^/N ratio in these studies was not

always that obtained from the addition of chlorine and ammonia during chloramination.

RESULTS

Midsouth Water

Influence of Water Quality Parameters on DBF Formation

Figure 8.1 and Table 8.2 show the current treatment of the midsouth water and the DBF

data for the finished water. The water was chloraminated at a Ch/N ratio of 3.8/1 (assuming

there were no other sources of nitrogen in the source water). The finished-water pH was 7.1. In

addition, the source water (with a bromide level of 1500 ng/L) was subjected to three bench-

scale experiments with a Cb/N ratio of 5/1 at pH levels of 6, 8, and 10 (Table 8.2).

As was observed in tests on the three primary waters, dichloramine formation was

significantly influenced by pH (Figures 5.7, 5.8, and 5.9). Bench-scale chloramination at pH

levels of 6, 8, and 10 resulted in the dichloramine residual representing 26, 2, and 0 percent of

the total residual, respectively. In addition, a significantly higher amount of preformed

chloramines was required to meet the target residual after 48 h at pH 6 than was required with

the pH 8 test (20 versus 5 mg/L chloramine dose, respectively). (At the lower pH,

monochloramine is less stable and is converted, in part, to dichloramine.) DOX, THM, and

HAA formation increased with decreasing pH. Higher DBF production at the lower pH was

probably caused by the presence of a larger chloramine dose, as well as a higher amount of

dichloramines. For the bromide-spiked LHW (Figure 5.15) and CSPW (Figure 5.17) (i.e., total

bromide levels of 580 and 600 ^ig/L, respectively), chloramination at a C12/N ratio of 5/1

produced a similar pH effect on DOX formation; whereas, in bromide-spiked LAW (Figure 5.12)

(total bromide level of 740 ug/L), DOX formation at a C12/N ratio of 5/1 was highest at pH 8,

146

——

ALU

M

CHLO

RAM

INES

DECA

NT

WAT

ER

LIM

E AD

DITI

ONBA

SIN

(pH

ADJ)

SOLI

DSCO

NTAC

T |

BASI

N

FLOC

CULA

TION

BA

SIN

TODE

CANT

BASI

N

SEDI

MENT

ATIO

N BA

SIN

^.....T

TO E

VAPO

RATI

ONPO

ND

DECA

NT W

ATER

TO

LIM

E AD

DITI

ON B

ASIN

Nr

^^m

m m

m m

• •

FILT

ER B

ACKW

ASH

FILT

ERS

FREE

TO D

ECAN

T BA

SIN

____

__^^

>M

CLE

ARW

ELL

I

I DIS

TRIB

UTIO

N PU

MPS

CLEA

RWEL

L

CLEA

RWEL

L

DIST

RI

BUTI

ON

PUM

PS

Figu

re 8

.1 W

ater t

reat

men

t pla

nt fl

ow sc

hem

atic

for m

idso

uth

utili

ty

Table 8.2 Influence of water quality parameters on DBF formation in midsouth water

Parameter

TOCUV-254Bf

Free C12 doseC12/N

pH

TemperatureTime

Free C12 residual

NH2C1 residual

NHC12 residual

Total C12 residual

DOX

CHC13

CHCl2BrCHClBr2

CHBr3TTHM

MCAA

DCAA

TCAA

Units Source Treatment Water Plant

mg/L 3.0 NAcm-' 0.042 NAug/L 1500 NA

mg/L 7.5

mg/mg 3.8/18.0 NA

°C 21 NA

hmg/Ltmg/Lt

mg/Lt

mg/Lt

ugClVL

ug/L

ug/Lug/L

ug/Lug/L

ug/Lug/L

Mg/L

Distribution System

NANA

NA

7.1

16

48

0.2

NA

NA

NA

72

3.8

4.1

8.6

23.840.3

ND

2.5

1.3

Distribution System*

NA

NA

NA

NA21

NA

0.2

NA

NA

1.0

NA

3.4

3.5

7.825.0

39.7

ND

0.8

ND

Batch

1

3.0

0.0421500

20.5

5/1

6.1

22

48

0.042.39

0.84

3.27

162

BDL

3.0

8.725.4

37.0

ND

4.5

5.2

Batch

2

3.0

0.0421500

4.6

5/1

8.122

48

ND

2.54

0.05

2.59

112

BDL

ND

1.6

10.612.2

ND

2.5

1.9

Batch

3

3.0

0.0421500

4.15/1

10.2

22

48

ND

2.61

ND

2.61

77

BDL

ND

ND

9.8

9.8

ND

3.5

1.8

(continues)

148


Parameter

BCAA

MBAA

DBAA

HAA6

CNC1CNBr

CNX

TTHMOX/DOX

HAA6OX/DOXCNXOX/DOXDBPOX/DOXn

n'(3/6)

TTHM-Br/Br'HAA6-Br/Br-CNX-Br/Br'

Units Source Treatment Distribution

Water Plant System

Ug/L 4.4

Ug/L 2.0ug/L 6. 1

ug/L 16.2ug/L NDug/L NQug/L NQ

%

%

%

%

%%%

Distribution

System*

3.00.7

10.9

15.4

ND

4.74.7

Batch

1

6.4

2.4

10.2

28.7

0.5

17

18

7.7

6.1

3.8

17.62.51

0.88

2.20.80.8

Batch

2

3.9

ND

5.7

14.0

0.77.4

8.1

3.1

4.2

2.6

9.9

2.85

0.94

0.80.40.4

Batch

3

2.1

ND1.6

9.0

NDND

ND

3.3

3.9

0

7.2

3.00

0.46

0.60.10

BDL = Below detection limit.NA = Not analyzed or not available.ND = Not detected.NQ = Not quantitated; value -3-4 ug/L.

* Distribution system resampled 42 days after original sampling of source and finished water; batch 1-3 bench-scale testing based upon original source and finished water.

fAs C12

149

followed by pH 6 and then pH 10. For those LAW tests (Figure 5.10), however, the THM

formation did increase with decreasing pH, similar to what was observed for the midsouth water.

CNBr was the predominant CNX in this high-bromide-containing water. As was

observed in the Task la studies (Figures 5.19, 5.21, and 5.23), neither CNX was present (or, if

present, was barely detected) at pH 10 because of base-catalyzed hydrolysis. CNBr was at a higher concentration at pH 6 than at pH 8 in the midsouth water (17 versus 7.4 ug/L,

o

respectively). In the Task la studies, CNX was studied at a C12/N ratio of 5/1 for LHW (direct comparisons to the other two primary waters cannot be made, as those waters were not evaluated for CNX formation at a Cfe/N ratio of 5/1). CNBr formation was somewhat higher at pH 6 than at pH 8 for both the ambient-bromide and bromide-spiked LHW samples; however, the values were too low in the LHW samples (i.e., <1 to 4.5 ug/L) to determine significant trends. The very

high bromide level of the midsouth water produced high enough values of CNBr in order to

better evaluate the impact of pH (i.e., to ascertain whether pH had an effect) on the production of

this CNX at a C12/N ratio of 5/1.

The effects of bromide in the midsouth water on THM and HAA speciation were also

observed. Bromoform was the dominant THM at all pH levels, resulting in a bromine

incorporation factor, n, of 2.5 to 3.0, where

n = Si x [CHCl(3.i)Bri] / Z[CHCl(3-i)Bri] - TTHM-Br/TTHM

THM concentrations are expressed on a molar basis, and n ranges from 0 (for 100 percent

chloroform) to 3 (for 100 percent bromoform) (Gould et al. 1983). (TTHM-Br is the molar sum of bromine in individual THMs.) Bromamines (or free bromine) probably played a significant

role in DBF formation in this water (this issue is discussed further in the historical data section below).

Bromine incorporation into the HAAs was less dramatic. In this study, six of the nine

possible HAAs were measured (i.e., monochloro-, dichloro-, trichloro-, bromochloro-,

monobromo-, and dibromoacetic acid [MCAA, DCAA, TCAA, BCAA, MBAA, and DBAA]).

150

The bromine incorporation factor for the three brominated HAAs, n' (3/6), was 0.46 to 0.94, where

n' [3/6] = [1 x (BCAA+MBAA) + 2 x DBAA] /(MCAA+DCAA+TCAA+BCAA+MBAA+DBAA)

HAA concentrations are expressed on a molar basis, and n' (3/6) ranges from 0 (for 100 percent

of the six measured HAAs as MCAA, DCAA, and TCAA) to 2 (for 100 percent DBAA) (Symons et al. 1994; Shukairy et al. 1994).

For example, at pH 6, a total of 0.20 and 0.15 umol/L of total HAA6 chlorine and bromine (HAA6-C1 and HAA6-Br), respectively, were formed, whereas a total of 0.08 and 0.40 umol/L of TTHM chlorine (TTHM-C1) and TTHM-Br, respectively, were formed. Under these conditions (in this high-bromide water), TTHM-Br was greater than TTHM-C1, whereas HAA6-

Br and HAA6-C1 were approximately the same. As three brominated HAAs were not measured (because of a lack of analytical standards for bromodichloroacetic and dibromochloroacetic acids

and, typically, a poor recovery of tribromoacetic acid by the existing analytical methodology), the formation of brominated HAAs was probably underaccounted for by the measurement of HAA6 (Cowman and Singer 1996). For the midsouth water, the bromide utilization (e.g., umol TTHM-Br/umol Br") was highest at pH 6 (i.e., 2.2, 0.8, and 0.8 percent for THMs, HAA6, and CNBr, respectively).

The percentage of DOX in the bench-scale chloraminated midsouth water that was accounted for by the measured DBFs (where the molar sum of DBF organic halogen [DBPOX] for the measured DBFs is divided by the DOX and expressed on a percentage basis) was 7.2 to

18 percent on a molar basis; this percentage was similar to that observed in Task la waters (Figures 5.24, 5.25, and 5.26). The amount accounted for increased with decreasing pH. At pH

6, THMs, HAA6, and CNX accounted for 7.7, 6.1, and 3.8 percent of the DOX (on a molar

basis), respectively.

The full-scale distribution-system sample from the midsouth utility represented a somewhat lower Cfe/N ratio (3.8/1) and a pH level (7.1) in between the levels evaluated in the bench-scale tests (pH 6 and 8). Chloramine speciation data were not available for this sample, but the neutral pH and a Cb/N ratio (3.8/1) that was lower than the C12/N ratio at the maximum

151

in the breakpoint curve (the maximum occurs at a Cb/N ratio of 5/1) suggest that dichloramine

formation would be relatively low.

DOX formation in the full-scale sample was less than that observed in the bench-scale

tests (which were run under somewhat different chloramination conditions than those applied at

full scale). On the other hand, THM formation was similar to that observed in the bench-scale

test at pH 6 (and Cb/N ratio of 5/1), whereas the HAA6 production was similar to that measured in the bench-scale test at pH 8 (and C^/N ratio of 5/1). The full-scale plant chloraminated water

had an ambient pH of 8.0 and distributed it at a pH of 7.1; therefore, the THM and HAA6 data

matching the bench-scale tests at pH 6 and 8, respectively, appear somewhat consistent considering that the bench and full scale tests did not utilize exactly the same parameter values.

The full-scale CNBr values of <4.7 |ig/L are lower than that observed in the bench-scale

tests. In Task la, CNBr in bromide-spiked LHW at pH 8 decreased in concentration (from 6.4 to

3.9 to <1 ug/L) with decreasing Cb/N ratio. Thus, the use of a somewhat lower Ch/N ratio in the full-scale midsouth-utility sample should explain the somewhat lower CNBr occurrence.

Interpretation of Historical Data

Tables 8.3 and 8.4 show historical data for the midsouth utility. In addition to evaluating

some of this utility's recent historical data (i.e., April 1993 through January 1994), some older

data (i.e., May 1988 through February 1989) from this utility's treatment of some of their other

source waters (Krasner et al. 1989a; MWDSC and JMM 1989) were examined. The 1988/89

waters had bromide levels of up to 3,000 ug/L. These 1988/89 waters were chloraminated at a pH of 7.3 to 8.3 with a C12/N ratio of 3/1, which produced DOX levels ranging from 110 to 350 ug C17L. In both sets of historical data, bromoform dominated THM formation, with TTHMs ranging from 40 to 161 ng/L. The bench-scale tests on this midsouth water suggest that chloramination at a higher pH would be a potential strategy to minimize DBF formation in this high-bromide water.

In the 1988/89 data set, free chlorine residuals within the plant were somewhat higher than the values in the plant effluents (i.e., 0.2-0.4 versus 0.1 mg/L for the three quarters in which

both residuals were measured). During chloramination in which breakpoint chlorination is not

achieved, there should not be a free chlorine residual. The free chlorine residual measured

152

Table 8.3

Historical (1993/94) DBF data for midsouth utility

Parameter

CHC13

CHCl2Br

CHClBr2

CHBr3

TTHM

CH2ClBr

CH2Br2

Units

ug/L

Hg/L

ug/L

Hg/L

ug/Lug/L

ug/L

April 14, 1993 Finished

Water

2.3

6.2

19.5

89.1

117.1

NA

NA

Sept. 29, 1993 Finished

Water

0.8

2.2

5.4

33

41

1.1

6.3

Dec. 21,1993 Finished

Water

1.2

3.8

14

142

161

ND

ND

Jan. 10, 1994 Finished

Water

0.9

4.8

12.3

30.9

48.9

3.2

15.3

NA = Not analyzed.

ND = Not detected.

within the plant may represent, in part, the presence of bromamines or hypobromous acid (or both) (Palin 1975), and these bromine-containing species may be responsible for the formation of

the brominated DBFs.In the 1993/94 data set, there were two sample periods in which the TTHMs exceeded

100 ug/L. Apparently the chlorine was added prior to the ammonia at this facility. Because of the very high amount of bromide typically present in this water supply, even a short period of

free chlorine contact may have been sufficient to generate a significant amount of THMs in

addition to what was formed during chloramination.For the 1988/89 data set, HAA5 ranged from 11 to 21 ug/L (BCAA was not measured at

that time), hi these samples, DBAA dominated HAA formation. Most likely these waters contained other bromine-substituted HAAs (e.g., bromodichloroacetic acid) for which measurements were not made (Cowman and Singer 1996). CNC1 was the only CNX measured at the time of this study; its value ranged from 0.1 to 0.3 ug/L. This midsouth utility was part of a 35-utility DBF study performed in 1988/89. In the 35-utility DBF study, CNC1 was observed

153

Tabl

e 8.

4

Histo

rical

(198

8/89

) DBF

dat

a for

mid

sout

h ut

ility

May

16,

1988

Para

met

erTO

CU

V-2

54B

fFr

ee C

12 d

ose

C12/N

pH Tem

pera

ture

Free

C12

resid

ual

Tota

l C12

resid

ual

DO

XCH

C13

CHCl

2Br

Uni

tsm

g/L

cm"1

Mg/L

mg/

Lm

g/m

g

°Cm

g/L*

mg/

L*ug

ClV

LM

g/LM

g/L

Sour

ce

Wate

rN

AN

AN

A

NA

NA

Trea

t. Pl

ant

NA

NA

NA 6.0

3/1 NA

NA

NA NA

Plan

t Ef

fl. 4.3 NA

NA 7.5 23 0.2 3.7

350

0.6 3.1

Aug

ust 1

5, 19

88So

urce

W

ater

4.6

0.16

630

00 7.9 28

Trea

t. Pl

ant

3.9

0.06

5N

A 6.0

3/1 7.3 28 0.2 3.5

Plan

t Ef

fl. 3.8 0.05

6N

A 7,3 28 0.1 3.3 180

1.0 3.8

Nov

embe

r 1, 1

988

Sour

ce

Wat

er4.

90.

092

2890 8.3 20

Trea

t. Pl

ant

3.6 0.05

5N

A 6.0

3/1 7.3 20 0.3 4.1

Plan

t Ef

fl. 3.6

0.03

8N

A 7.3 20 0.1 3.3 140

0.6

2.9

Febr

uary

6, 1

989

Sour

ce

Wat

er5.3 0.10

428

00

NA 6

Trea

t. Pl

ant

Plan

t Ef

fl.4.5

4.

20.

036

0.03

3N

A

NA

6.0 3/1 NA

N

A6

60.4

0.1

4.9

4.5 110

0.7

4.1(c

ontin

ues)

Tabl

e 8.

4 (c

ontin

ued)

Para

met

erCH

ClBr

2CH

Br3

TTH

MM

CAA

DCA

ATC

AA

MBA

AD

BAA

HA

AS

CNC1

Uni

ts ug/L

ug/L

ug/L

ug/L

ug/L

ug/L

ug/L

ug/L

ug/L

ug/L

May

16,

1988

Sour

ce

Trea

t. Pl

ant

Wat

er

Plan

t Ef

fl. 9.9

26.7

40.3

ND 1.3 ND 1.7 14.5

17.5

0.1

Aug

ust 1

5, 19

88So

urce

Tr

eat.

Plan

tW

ater

Pl

ant

Effl. 8.6

29.8

43.2

ND 0.9

ND 1.2 19.0

21.1 0.1

Nov

embe

r 1,

1988

Sour

ce

Trea

t. Pl

ant

Wat

er

Plan

t Ef

fl. 9.2 40 53 ND 0.8

ND 1.2 13.1

15.1

0.2

Febr

uary

6, 1

989

Sour

ce

Trea

t. Pl

ant

Wat

er

Plan

t Ef

fl. 11 31 47 1.0 0.9

ND 1.4 7.8

11.1

0.3

Effl.

= E

fflue

ntN

A =

Not

ana

lyze

d or

not

ava

ilabl

e.N

D =

Not

det

ecte

d.Tr

eat.

= Tr

eatm

ent

*As C

12

to be preferentially formed in chloraminated waters as compared to chlorinated ones (Krasner et

al. 1989a; MWDSC and JMM 1989). The samples from this midsouth utility, however, were the

one set of chloraminated waters that did not follow this trend. The current data indicate that the CNX formation in the water of this midsouth utility favors CNBr, the bromine-substituted

analogue of CNC1.

For the 1993/94 data set, THM results were obtained as part of a volatile organic compound (VOC) analysis, with gas chromatography/mass spectrometry, during three

samplings. Seventy-two VOCs were analyzed for, almost all of which are synthetic organic chemicals rather than DBFs. During two sample periods, bromochloromethane (CFbClBr) and

dibromomethane (CHiB^) were detected in chloraminated samples from this midsouth utility in

addition to the THMs (Table 8.3); no other VOCs were detected. Also, the formation of

dihalomethanes (other possible by-products of chloramination) was observed in Task 4 testing of

the midsouth chloraminated water (discussed further in Chapter 9). The data sets from this

midsouth utility indicate that bromine-substituted DBFs can be formed during chloramination of a high-bromide water.

Mississippi River Water


Figure 8.2 and Table 8.5 show the current treatment of Mississippi River water at the

participating softening plant and the DBF data for the finished water. The water was

chloraminated at a Cb/N ratio of 4/1 and lime softened. The finished-water pH was 9.0. In

addition, the source water was subjected to three bench-scale experiments with Cb/N ratios of 3/1 and 5/1 at pH 8 and with a C12/N ratio of 5/1 at pH 10 (Table 8.5).

Chloramination at the chosen Cli/N ratios and pH levels resulted in all of the chloramines being measured as monochloramine. The three sets of bench-scale conditions resulted in similar DOX, THM, and HAA6 levels, with a somewhat higher level of DOX at a C12/N ratio of 5/1 and a pH of 8 and the lowest concentration at a Cb/N ratio of 3/1 and a pH of 8. In the Task 1 a study of the three primary waters (at ambient bromide) (Figures 5.12, 5.15, and 5.17) for the same

156

POLY

ELEC

TROL

YTE

LIME

AND

FE

RRIC

SU

LFAT

E

RIVE

R IN

TAKE

- BA

R SC

REEN

PU

MPI

NG'

& SU

RFAC

E ST

ATIO

N SP

RAY

SLOW

MECH

ANIC

AL

MIXI

NG

SETT

LING

BAS

INS

W/M

ECHA

NICA

LSL

UDGE

REMO

VAL

SLUD

GEDI

SCHA

RGE

0 RI

VER

FREE

CH

LORI

NE

^ AM

MONI

A SECO

NDAR

YSE

TTLI

NG

RESE

RVOI

RSPO

LYPH

OSPH

ATE

FLUO

RIDE

i>"

RAPI

DSA

NDRL

TERS

CLEA

RWEL

L HIGH

- PR

ESSU

RE

DIST

RIBU

TION

.

, PU

MPS

*-*

Figu

re 8

.2 Fl

ow d

iagr

am o

f wat

er p

urifi

catio

n pr

oces

s for

util

ity tr

eatin

g M

ississ

ippi

Riv

er w

ater

Table 8.5 Influence of water quality parameters on DBF formation in Mississippi River water

ParameterTOCUV-254BfFree C12 DoseClj/NPHTemperatureTimeFree C12ResidualNH2C1NHC12ResidualTotal C12ResidualDOX :CHC13CHCl2BrCHClBr2CHBr3TTHMMCAADCAATCAA

Unitsmg/Lcm" 1

Mg/Lmg/L

mg/mg

°C

hmg/L*

mg/L*mg/L*

mg/L*

MgClYLMg/LMg/LMg/LMg/LMg/LMg/LMg/LMg/L

Source Treatment Distribution Water Plant System

2.9 NA NA0.079 NA NA

40 NA NA4.34/1

7.7 NA 9.022 NA 24

24NA

<2.3NA

2.3

839.62.8

BDLBDL12.41.3

18.94.4

Batch 1

2.90.079

402.83/18.22248

ND

2.0ND

2.1

595.8NDNDND5.8ND11.01.8

Batch2

2.90.079

404.85/18.02248

ND

2.06ND

2.06

805.5NDNDND5.5ND14.42.2

Batch3

2.90.079

404.75/110.02248

ND

2.5ND

2.5

685.8NDNDND5.8ND14.22.6

(continues)

158


ParameterBCAAMBAADBAAHAA6CNC1CNBrCNXTTHMOX/DOXHAA6OX/DOXCNXOX/DOXDBPOX/DOXnn '(3/6)TTHM-Br/Br-HAA6-Br/Br"CNX-Br/Br"

Source Treatment Distribution Units Water Plant SystemHg/L 3.9Hg/L ND|j.g/L 0.6Hg/L 29.0fig/L 1 .0Hg/L 0.6(jg/L 1.5

%/O

%%

/o

%%

Batch 1

2.6NDND15.42.2NR2.27.56.92.216.6

00.13

03.00

Batch2

3.2NDND19.88.7ND8.75.36.56.418.1

00.13

03.7NA

Batch3

2.8NDND19.6NDNDND6.57.70

14.30

0.110

3.20

BDL = Below detection limit.NA = Not analyzed or not available.ND = Not detected.NR = Not reported; sample not analyzed within holding time.

*As C12 .

159

three sets of conditions studied for the Mississippi River water only (C^/N ratios of 3/1 and 5/1

at pH 8 and a C12/N ratio of 5/1 at pH 10), a C12/N ratio of 5/1 and a pH of 8 also resulted in the highest DOX formation. Because only three of the nine possible Cb/N ratios and pH levels were studied in the Mississippi River water samples, it is not possible to determine whether the DOX

formation trends for the three primary waters were completely reproduced in the Mississippi River water. (The tests in the other Task 3 waters, however, were set up to evaluate the other

C12/N ratios and pH levels evaluated in Task la.)

CNBr was not detected (with a detection limit of 0.5 ng/L) in bench-scale tests of this water, which contained bromide at an average level (40 ^ig/L). CNCl was detected in the pH 8

samples, and the level increased with increasing Cli/N ratio (8.7 j^g/L versus 2.2 ng/L).

Likewise, in the Task la study of ambient-bromide LHW at pH 8 (the only Task la water that

was studied for CNX formation at the intermediate Cli/N ratio of 5/1), more CNCl was formed with a Cli/N ratio of 5/1 than for a 3/1 ratio (15.5 ng/L versus 2.5 ug/L). Ohya and Kanno

(1985) found that CNCl was formed by the reaction of humic acid with hypochlorous acid in the

presence of the ammonium ion. The amount of CNCl was at a maximum when the reaction

mixture contained a Cb/N weight ratio of 8-9/1 (Ohya and Kanno 1985). Similarly, in the Task

la study of ambient-bromide LHW at pH 8, the CNCl concentration was at a maximum at the C12/N ratio of 7/1 (16.9 ng/L).

The effect of bromide was negligible in this water. Chloroform was the only THM

formed in the bench-scale tests; therefore, n equaled 0. DCAA was the dominant HAA formed, whereas TCAA—the other major HAA produced during the chlorination of low-bromide waters

(Krasner et al. 1989a)—was formed at a relatively low level. The value of «' (3/6) for these samples was 0.11 to 0.13. These data are consistent with the observation made during the testing

of the primary waters that DCAA is a chloramine DBF. Smith et al. (1993) also found that

although TCAA was the principal HAA formed during chlorination, it was not detected during

chloramination, whereas there was appreciable DCAA formation. This observation is also consistent with the findings that, when ammonium chloride is used to quench free chlorine

residuals in HAA samples, DCAA forms slowly (over the course of approximately one week) even when stored at 4°C (Krasner et al. 1989b). Thus, at ambient water temperature, some level

of DCAA formation in low-bromide waters (like that observed in the Mississippi River water) should be expected. In addition, BCAA should form, as this is the analogue of DCAA in which

160

one of the chlorine atoms has been replaced with a bromine atom. In the bench-scale studies for

the Mississippi River water, 11 to 14 ug/L of DCAA and 3 ug/L of BCAA were produced,

whereas only 6 ug/L of chloroform formed.

The percentage of DOX in Mississippi River water that was accounted for by the

measured DBFs (14 to 18 percent on a molar basis) was similar to that observed in Task la

waters (Figures 5.24, 5.25, and 5.26) and in the midsouth water (Table 8.2). THMs, HAA6, and

CNC1 accounted for 5.3 to 7.5, 6.5 to 7.7, and 0 to 6.4 percent of the DOX (on a molar basis),

respectively. Under the bench-scale conditions tested, changes in CNC1 formation were the most

significant.

The full-scale distribution system sample from the softening plant represented an

intermediate Cb/N ratio (4/1) and an intermediate pH value (9.0) compared to what was

evaluated at the bench scale. In addition, the distribution-system sample only had a retention

time of ~24 h, whereas the bench-scale tests were conducted for 48 h. The chloramine residual

of the distribution-system sample was reported to be mostly monochloramine. The distribution-

system sample had somewhat higher DOX, THM, and HAA6 concentrations than in the bench-

scale experiment performed at a Cb/N ratio of 5/1 at a pH of 8. The higher concentrations of

DBFs observed at full scale (as compared to bench scale) may have been due, in part, to the

addition of chlorine upstream of ammonia addition at the treatment plant, which probably

resulted in some free-chlorine contact prior to the formation of chloramines.

Chloroform was still the predominant THM in the full-scale distribution system (9.6

ug/L), with a small amount of bromodichloromethane formation (2.8 ^ig/L). DCAA was still the

predominant HAA (18.9 ug/L), with a smaller amount of TCAA produced (4.4 jag/L). In

addition, the other dihalogen-substituted HAAs (BCAA and DBAA) were present, albeit to

lesser extents in this water, with its low-to-moderate concentration of bromide. These data

suggest that the precursors for dihalogenated HAAs may in some cases be different than the

precursors for trihalogenated HAAs. For example, during the ozonation of fulvic acid, Reckhow

and Singer (1984) observed that TCAA precursors were destroyed, whereas the precursors of

DCAA were not. Thus, alternative disinfectants impact DCAA and TCAA precursors

differently. Young et al. (1995) observed that chloral hydrate (trichloroacetaldehyde) production

was minimized by chloramination, whereas the formation of dichloroacetonitrile (DCAN) was

similar during chlorination and chloramination. The results indicated that DCAN was produced

161

from the reaction of chloramines with reaction by-products such as dichloroacetaldehyde. Thus, chloramination has been shown in other studies to form a dihalogen-substituted DBF preferentially over a related trihalogenated species.

CNC1 was found in the distribution system at a level that was lower than that found during bench-scale testing at pH 8 but higher than the "not detected" level found in bench-scale testing at pH 10. At the distribution-system pH of 9.0, base-catalyzed hydrolysis was not as complete as at pH 10. In the 1988/89 35-utility DBF study (Krasner et al. 1989a), another softening plant formed CNC1 (at 4 j^g/L) in the plant, but the level dissipated (down to 1.0 |j.g/L) in the distribution system at a pH of 9.0. Thus, base-catalyzed hydrolysis at pH 9 can be used to minimize exposure to CNC1.


Table 8.6 shows historical data for the softening plant treating Mississippi River water. The water was chloraminated at a Cb/N ratio of 4/1 and lime softened at a pH of 9.1-9.4. The finished-water pH was 8.9-9.2. TTHMs ranged from 0 to 12 |ig/L, with chloroform as the dominant species. Data for other DBFs were not available. Clearly, chloramination of Mississippi River water at this softening facility controlled THM formation. The proposed Disinfectants/DBF Rule (USEPA 1994b) will also set standards for the control of HAAs, as well as TOC. The proposed Stage 1 and 2 maximum contaminant levels (MCLs) for HAAS are 0.060 and 0.030 mg/L, respectively. Based on the current treatment and bench-scale data, compliance with the proposed Stage 1 MCL should be obtainable, whereas the one data point for the current treatment was barely below the proposed Stage 2 MCL based on the HAA6 value of 29.0 |ig/L (the HAAS value, which excludes BCAA, was 25 (ag/L). More data on HAA occurrence will need to be collected, however, to make an assessment of potential compliance with the proposed Stage 2 MCL for HAAS using the existing treatment.

162

Tabl

e 8.6

o\

Hist

oric

al D

BF d

ata

for u

tility

trea

ting

Miss

issip

pi R

iver

wat

erFe

brua

ry 1

7, 19

94Pa

ra

met

erTO

CC1

2do

seC1

2/NPH Te

mp.

Tim

eCH

C13

CHC1

2Br CH

C1Br

2CH

Br3

TTHM

Plan

t Un

its

Inf.

mg/

L 2.

6m

g/L

mg/

mg

7.9°C

1.7

h ug/L

Hg/L

Hg/L

Mg/L

ug/L

Trea

t. Pl

ant

NA 3.5 4/1 9.1 16

Dist.

Syst.

NA 8.9 24 24 7 1 ND ND 8

May

3, 1

994

Plan

t Tr

eat.

Inf.

Plan

t2.5

NA 4.3 4/1

7.7

9.416

22

Dist.

Sy

st.NA 9.0 23 24 9 3 ND ND 12

Sept

embe

r 20,

199

4Pl

ant

Trea

t. Di

st.

Inf.

Plan

t Sy

st.2.

6 NA

NA

5 4/17.9

9.4

8.9

23

28

29 24 ND ND ND

ND ND

Dece

mbe

r 29,

Plan

t Tr

eat.

Inf.

Plan

t2.

9 NA 4.3 4/1

7.9

9.25.0

NA

1994 Di

st.Sy

st. NA 9.2 14 24 9 2 ND

ND 11

Janu

ary

25, 1

995

Plan

t Tr

eat.

Dist.

In

f. Pl

ant

Syst.

2.8

NA

NA4.

2

4/18.0

9.2

9.0

4.4

15

14 24 9 2 ND

ND 11Di

st. S

yst.

= Di

strib

utio

n Sy

stem

Inf.

= In

fluen

tNA

= N

ot an

alyz

ed o

r not

avai

labl

eND

= N

ot d

etecte

dTe

mp.

= Te

mpe

ratu

treTr

eat.=

Tre

atmen

t

Biscayne Aquifer


Figure 8.3 and Table 8.7 show the current treatment of Biscayne Aquifer water at one of

the treatment plants of the participating utility, as well as the DBF data for the finished water. This source water is very complex to treat, as it is relatively high in THM precursors, color,

ammonia, and hydrogen sulfide. At the plant, source water was prechlorinated at ambient pH (i.e., 7), lime-softened at a pH of 9 to 10, and postchloraminated. The finished- water pH was 8-9.

The source water was subjected to three bench-scale experiments with preformed

chloramines, with target C^/N ratios of 3/1 and 5/1 at pH 10 and a C12/N ratio of 5/1 at pH 8. Once the preformed chloramines were added to the source water, however, the C12/N ratio

theoretically should have changed. Assuming that preformed chloramines did not oxidize the hydrogen sulfide as free chlorine does (see discussion below), but that the C12/N ratio did go

down because the ammonia concentration was increased by the presence of source-water

ammonia, the theoretical C12/N ratio of the bench-scale tests was probably in the range of 1.5/1 to 2.7/1.

In the full-scale plant, however, the water was prechlorinated with free chlorine prior to postchloramination. Based upon full-scale data at this plant, in which the prechlorination does

not breakpoint-chlorinate the source-water ammonia and the postchlorination does not

effectively reduce the color, a portion of the chlorine is probably being consumed by oxidation of the hydrogen sulfide. In ozone pilot plant tests of colored groundwater performed by other

investigators, color was not destroyed until the hydrogen sulfide was oxidized (Dunkelberger et al. 1992). Stoichiometrically, the complete oxidation of hydrogen sulfide to sulfate requires an 8.3/1 ratio (on a weight basis) of chlorine to hydrogen sulfide (Equation 8.1), whereas a 2.1/1

weight ratio will oxidize hydrogen sulfide to sulfur and water (Equation 8.2) (White 1992):

4H2O-»H2SO4 +8HC1 (8.1)

H2S + C12 -> S^ + 2 HC1 (8.2)

164

o\

WAT

ER

FROM

W

ELLS

«—

——

— P

RECH

LORI

NATI

ON

LIME

I P

OLYM

ER

I {

GENE

RAL

FILTE

R ,N I

A CO

NTRA

FLOT

YPE"

0"

UPFL

OW C

LARI

FIER

PUSH

MI

XFL

OCCU

LATI

ON

ZONE

SODI

UM H

EXAM

ETAP

HOSP

HATE

- PO

STCH

LORI

NATI

ON-

FILT

ERS

FILT

ERS

SMAL

L CL

EARW

ELL

TRAN

SFER

PU

MPS

CLEA

RWEL

L

CLEA

RWEL

L

HIGH

- PR

ESSU

RE

DIST

RIBU

TION

PU

MPS

Note:

Cen

traflo

w is

a pro

duct

of G

ener

al Fi

lter,

Am

es, I

owa.

Figu

re 8

.3 W

ater t

reat

men

t pla

nt fl

ow sc

hem

atic

for u

tility

trea

ting

Bisc

ayne

Aqu

ifer w

ater

Table 8.7 Influence of water quality parameters on DBF formation in Biscayne Aquifer

Treatment Plant

ParameterTOCUV-254Br'

Free C12 doseEffective C12 dose*Ammonia doseTotal ammoniaTheoretical C12/N

pHTemperatureTimeFree C12 residualNH2C1 residualNHC12 residualTotal C12 residualDOXCHC13CHCl2BrCHClBr2CHBr3TTHM

Source PreCl2 Units Watermg/L 8.9cm' 1 0.209 NAUg/L 89 NAmg/L NAmg/L 8mg/L 4.8mg/L 1.3 0

mg/m 1 .3

g7.1 3.7/1

°C 26 NAh NA

mg/Ltmg/Ltmg/Ltmg/Lt

ugClYLug/Lug/Lug/Lug/Lug/L

PostCl2 Dist. Syst.NA

NA NANA NANA13

17.80.92.2

8.1/1 9.2NA 29NA 48

NA2.2NA2.243182.519.22.9ND

104.6

Batch1

8.90.209

893.93.91.32.6

1.5/1

9.82248

ND2.20ND2.2092

BDLNDNDNDND

Batch2

8.90.209

896.26.21.22.5

2.5/1

9.82248

ND1.81ND1.81115

BDLNDNDNDND

Batch3

8.90.209

897.27.21.42.7

2.7/1

8.22248

ND2.440.062.501480.8NDNDND0.8

(continues)

166


Treatment Plant

ParameterMCAADCAATCAABCAAMBAADBAAHAA6CNC1CNBrCNXTTHMOX/DOXHAA6OX/DOXCNXOX/DOXDBPOX/DOXnn ' (3/6)TTHM-Br/Br"HAA6-Br/Br-CNX-Br/Br-

Source PreCl2 Units Water"g/L"g/Lug/L(ig/Lug/L"g/LHg/L"g/L"g/L"g/L

%/o

/o

/o

/o

%/o

PostCl2 Dist. Syst.4.4

42.213.89.4ND1.8

71.61.4ND1.4

17.74.80.2

22.60.180.1413.06.30

Batch 1

ND6.22.01.8

NDND9.90.5ND0.50

3.30.33.6NA0.15

00.90

Batch2

ND8.62.62.2NDND13.40.7ND0.70

3.50.43.9NA0.13

01.10

Batch3

1.413.92.72.6NDND20.53.6ND3.60.43.51.45.40

0.100

1.30

BDL = below detection limit Dist. Syst. = Distribution System NA = not analyzed or not available ND = not detected Post C12 = Postchlorination PreCl2 = Prechlorination

*Raw-water H2 S = 0.5 mg/L; assuming H2 S oxidized during prechlorination at the full-scale plant. tAs C12 .

167

At a pH of around 7.0, approximately 70 percent of the hydrogen sulfide is oxidized to sulfate and 30 percent to sulfur and water, whereas at pH values of 9 and 10, approximately 50 percent is oxidized to sulfate and 50 percent to sulfur and water (White 1992).

At the time of this sampling, the source-water hydrogen sulfide level was 0.5 mg/L. Thus, the full-scale prechlorination at pH 7 theoretically could have experienced a 3.2-mg/L chlorine demand, as 70 percent of the hydrogen sulfide should have been completely oxidized to sulfate and 30 percent should have been partially oxidized to sulfur. Therefore, if this much chlorine was utilized to oxidize the hydrogen sulfide, then the effective chlorine dose would have

been reduced by the hydrogen sulfide's chlorine demand.

Because the chlorine addition in the full-scale prechlorination should have been inadequate to achieve breakpoint, the total ammonia should equal the source-water amount (1.3 mg/L during this testing) plus the amount added as part of the postchloramination. Based upon this assumption—and taking into account the chlorine demand from hydrogen sulfide (discussed above)—the theoretical Cfe/N ratios of the full-scale treatment were probably around 4/1 and 8/1 for the pre- and postchlorination, respectively. These Cb/N ratios, however, do not consider other sources of chlorine demand (e.g., any chlorine used in oxidizing color-causing organic matter). Thus, it is unlikely that the actual Cla/N ratio was that high during postchloramination, or there would have been breakpoint chlorination of the ammonia. Also, it has been assumed that the ammonia-nitrogen concentration was at a significantly higher concentration than that of

any organic nitrogen that may have been present.

As a result of the low Cb/N ratios and the pH levels used in the bench-scale tests, the chloramine speciation was essentially all monochloramine. A trace of dichloramine (0.06 mg/L) was detected in the pH 8 test only, and it was only in that test that any THMs were detected (0.8 ug/L as the average value of replicate analyses). HAAs were detected in all of the bench tests, with the highest value (20 ug/L) detected in the pH 8 test. The major HAA formed in these tests was DCAA (6-14 ug/L), followed by TCAA (2.0-2.7 ug/L) and BCAA (1.8-2.6 ug/L). Even under these conditions, in which relatively low Cb/N ratios were used, dihalogen-substituted HAAs were formed when THMs were essentially absent. CNC1 was barely detected (0.5 to 0.7

^ig/L) in the pH 10 tests, whereas 3.6 ug/L CNC1 was measured in the pH 8 experiment.A substantial amount of DOX (92 to 148 |*g C17L) was formed in the bench-scale

experiments, suggesting that monochloramine can react with DOX precursors when a relatively

168

high amount of TOC is present, even though the Cfe/N ratio was low. (Snyder and Margerum

[1982] have studied the kinetics of chlorine transfer during chloramination.) In these bench-

scale tests, DOX formation increased with either increasing Cb/N ratio or decreasing pH.

Comparing these results to the Task la studies is difficult, as the three primary waters did not

have such high source-water inorganic chlorine demands. In the bench-scale testing of the

Biscayne Aquifer water, the percentage of DOX accounted for by the measured DBFs was quite

low (3.6 to 5.4 percent). Under these conditions (e.g., a low Cb/N ratio), some degree of

halogen substitution of humic substances occurred, but possibly the conditions were inadequate

to break the halogen-substituted by-products down to the more commonly measured DBFs. Also

under these conditions, bromide utilization was very low (0.9-1.3 percent for the HAAs, none for

the THMs or CNX) in spite of a moderate amount of bromide (89 ng/L).

In the full-scale application, although the Cb/N ratio calculated for the postchlorination

(8/1) was sufficient to breakpoint-chlorinate ammonia, the calculations performed did not

account for chlorine demand from the organic matter (e.g., any chlorine used in oxidizing the

color-causing organic matter). Under these operating conditions, very high amounts of DOX

(431 ng C17L), THMs (105 jig/L), and HAA6 (72 jig/L) were produced. Most of the mass of

HAAs was caused by DCAA (42 ng/L), followed by TCAA (14 fig/L) and BCAA (9 ug/L). For

the full-scale water, the percentage of DOX accounted for by the measured DBFs (23 percent)

was consistent with that observed in other waters studied in this project (Figures 5.24, 5.25, and

5.26). Under these chloramination conditions, bromide utilization was significantly higher (13

and 6 percent for TTHM-Br/Br" and HAA6-Br/Br", respectively) than in the bench-scale tests.

CNC1 (1.4 ng/L) was lower than in the pH 8 bench test, probably because of base-catalyzed

hydrolysis at the distribution-system pH of 9.2.


Tables 8.8 and 8.9 show historical data for the utility treating Biscayne Aquifer water. In

addition to evaluating some of this utility's recent historical data (i.e., February 1994 through

February 1995), some older data (i.e., April 1988 through January 1989) from one of the utility's

other facilities that treated water from another aquifer (MWDSC and JMM 1989) were

examined. In both sets of historical data, high-TOC water (i.e., 11-17 mg/L) was prechlorinated,

169

Tabl

e 8.8

Histo

rical

(199

4/95

) DBF

dat

a for

util

ity tr

eatin

g Bi

scay

ne A

quife

r wat

er

Febr

uary

9, 1

994

May

4, 1

994

Aug

usts

, 199

4 N

ovem

ber 9

,

Para

met

erTO

C*

Free

C12

dose

Effe

ctive

Cl2d

oset

Am

mon

iado

seTo

tal

amm

onia

jTh

eore

tical

C12/N

Units mg/

L

mg/

L

mg/

L

mg/

L

mg/

L

mg/

mg

Trea

tPr

e C1

2NA 9.5 6.9 1.6 4.3

/1

.Pla

nt Post

C12

NA 3.7 10.6

0.9 2.5 6.8/1

Trea

tDi

st.

Pre

Syst.

C1

27-

9 NA 3.5 0.

9 1.6 0.6/1

.Pla

nt Post

C12

NA 10.8

11.7 1.5 3.1 3.7/1

Trea

t.Di

st.

Pre

Syst.

C1

27-

9 NA 9.0 6.4 1.6 4.0

/1

Plan

tPo

st C1

2NA 15

.9

22.3 1.1 2.7 6.7/1

Trea

tDi

st.

Pre

Syst.

C1

27-

9 NA 7.0 4.

4 1.6 2.8/1

.Pla

nt Post

C12

NA 18.6

23.0 1.0 2.6

5.4/1

1994

Fe

brua

ry 2

3, 1

995

Trea

t.Di

st.

Pre

Syst.

C1

27-

9 NA 7.0 4.

4 1.6 2.8/1

Plan

tPo

st Di

st.

C12

Syst.

NA

7-9

12.7

17.1 1.0 2.6

5.4/1

(con

tinue

s)

Tabl

e 8.8

(con

tinue

d)

Febr

uary

9, 1

994

May

4, 1

994

Para

met

erpH

§Ti

me*

*

CHC1

3CH

Cl2B

rCH

ClBr

2CH

Br3

TTH

M

Uni

ts h ug/L

ug/L

ug/L

ug/L

ug/L

Trea

t. Pl

ant

Trea

t. Pl

ant

Pre

Post

Dist.

Pr

e Po

stC1

2 C1

2 Sy

st.

C12

C12

8.8

8.6

9.2

18 32.9

7.1 1.4 ND

41.4

Dist.

Syst. 8.2 18 26.7

4.9 1.2 ND

32.8

Aug

ust5

, 19

94Tr

eat.

Plan

tPr

e Po

st Di

st.C1

2 C1

2 Sy

st.10

.1 9.

2 18 NA

NA

NA

NA

74.2

Nov

embe

r 9, 1

994

Trea

t. Pl

ant

Pre

Post

Dist.

C12

C12

Syst.

10.0

9.1 18 N

AN

AN

AN

A95

.6

Febr

uary

23,

199

5Tr

eat.

Plan

tPr

e Po

st Di

st.C1

2 C1

2 Sy

st.10

.0 9.1 18 55

.08.

00.

7N

D63

.7Di

st. S

yst.

= D

istrib

utio

n Sy

stem

Post

C12 =

Pos

tchl

orin

atio

nPr

e C1

2 = P

rech

lorin

atio

nN

A =

not

ana

lyze

d or

not

ava

ilabl

eN

D =

not

det

ecte

dTr

eat.

Plan

t = T

reat

men

t Pla

nt

*Raw

-wate

r TOC

= 1

1-17

mg/L

.*(

•Hist

orica

l raw

-wat

er H

2S in

this

regi

on =

0.3

-0.6

mg/

L;th

eref

ore

assu

min

g -0

.4 m

g/L

H2S

and

that

H2S

oxi

dize

d du

ring

prec

hlor

inat

ion.

JR

aw-w

ater

am

mon

ia =

1.5

-1.7

mg/

L; t

here

fore

ass

umin

g -1

.6 m

g/L

NH

3-N.

§Raw

-wat

erpH

= 7

.1-7

.4.

**D

istrib

utio

n-sy

stem

TH

Ms r

epre

sent

the

aver

age

of fi

ve d

istrib

utio

n-sy

stem

sam

ples

w

ith re

tent

ion

times

of 2

, 12,

18, 2

4, a

nd 3

6 h

(ave

rage

tim

e =

18 h

r).

-J K)

Tabl

e 8.9

Histo

rical

(198

8/89

) DBF

dat

a for

util

ity tr

eatin

g co

lore

d gr

ound

water

*

April

4, 1

988

Para

mete

rTO

CUV

-254

Br'

C12 d

ose

Effe

ctive

Cl2d

oset

Am

mon

iado

seTo

tal Amm

onia§

Theo

retic

alC1

2/NpH Te

mp.

Total

C12

resid

ual

DOX

Units mg/

Lcm

'1

mg/

Lm

g/L

mg/

L

mg/

L

mg/

L

mg/

mg

°C

mg/

L**

ug C

17L

Pre

Inf.

C12

NA

NANA

NA

NA

NA 10 7.4

1.6

1.6 4.6/1

NA

NANA

NA NA

Post

C12

NA NA NA 10 17.4 1.0 2.6

7.2/1

NA NA NA

Augu

stPr

e Ef

f. In

f. C1

29.1

10

.6 NA

NA

.358

NANA

18

0 NA 10 7.4

1.6

1.6 4.6/1

8.8

7.0

NA24

25

NA

3.8

NA20

0

1, 19

88Po

st C1

28.0 .18

6NA 13 20

.4 1.2 2.8 7.4/1

8.9 26 5.8

Oct

ober

17,

1988

Pre

Eff.

Inf.

C12

7.8

12.7

NA.18

1 .35

1 NA

NA

170

NA 10 7.4

1.6

1.6 4.6/1

8.9

7.2

NA25

24

NA

5.6

NA35

0

Post

C12

Eff.

Inf.

8.6

8.3

10.7

.187

.179

.414

NA

NA

170

8 15.4

0.8 2.4

1.6

7.0/1

9.1

9.2

6.924

25

23

4.4

5.0 250

Janu

ary

23, 1

989

Pre

C12

NA NA NA 13 10.4 1.6 6.5/1

NA NA NA

Post

C12

8.4 .243

NA 8 18.4 1 2.6 9.1/1

8.9 24 6.4

Eff.

8.1 .232 NA 9.1 24 5.8 310

(con

tinue

s)

Tabl

e 8.

9 (c

ontin

ued)

Para

met

erCH

C13

CHCl

2Br

CHCl

Br2

CHBr

3TT

HM

MCA

AD

CAA

TCA

AM

BAA

DBA

AHA

ASCN

C1

Uni

ts ug/L

ug/L

Mg/L

ug/L

ug/L

Mg/L

Mg/L

Mg/L

ug/L

Mg/L

Mg/L

Mg/L

Apr

il 4,

198

8Pr

e Po

st In

f. C1

2 C1

2 Ef

f. 15 2.7

0.5

ND 19 1.5 9.8

6.7

ND

ND 18 NA

Aug

ust 1

, 198

8Pr

e Po

st In

f. C1

2 C1

2 Ef

f. 44 10 2.4

ND 56 2.3 15 10 ND

ND 27 5.4

Oct

ober

17,

1988

Pre

Post

Inf.

C12

C12

Eff. 26 4.5

0.7 1.4 33 2.1 15 8.8

ND

ND 26 7.3

Janu

ary

23, 1

989

Pre

Post

Inf.

C12

C12

Eff.

37 9.3 1.7 0.1 48 2.8 19 13 ND

ND 35 12

Eff.

= Ef

fluen

tIn

f. =

Influ

ent

Post

C12 =

Pos

tchl

orin

atio

nPr

e C12

= P

rech

lorin

atio

nN

A =

not

ana

lyze

d or

not

ava

ilabl

eN

D =

not

det

ecte

dTe

mp.

= T

empe

ratu

re

The

se d

ata t

aken

from

ano

ther

faci

lity

treat

ing

wat

er fr

om a

noth

er a

quife

r nea

r the

Bisc

ayne

Aqu

ifer.

•("Hi

storic

al so

urce

-wat

er H

2S in

this

regi

on =

0.3

-0.6

mg/

L; a

ssum

ing

-0.4

mg/

L H

2S a

nd th

at H

2S o

xidi

zed

durin

g pr

echl

orin

atio

n.JA

mm

onia

dos

ed im

med

iate

ly a

fter p

ostc

hlor

ine

addi

tion

poin

t.§H

istor

ical

sou

rce-

wat

er a

mm

onia

in th

is re

gion

= 1

.5-1

.7 m

g/L;

ass

umin

g -1

,6 m

g/L

NH

3-N.

**As

C12

.

lime-softened (at pH 9 to 10), and postchlorinated. Prechlorination doses ranged from 4 to 13 mg/L, and postchlorination doses were 4 to 19 mg/L. Based on historical source-water ammonia levels of 1.5 to 1.7 mg/L and hydrogen sulfide levels of 0.3 to 0.6 mg/L, theoretical C^/N ratios during prechlorination were in the range of 0.6/1 to 6/1, and for postchlorination they were in the range of 4/1 to 9/1. As discussed above, the actual C^/N ratios were probably lower if there was a significant chlorine demand from other constituents in the water.1

For these historical data sets, TTHMs ranged from 19 to 96 ug/L, with chloroform the dominant THM (where THM speciation data were available). Figure 8.4 shows the effect of chlorine dose on TTHM formation in these colored groundwaters for the current and historical data, as well as the bench-scale experiments. All of the parameters were not identical in each sampling (e.g., contact time); however, this figure highlights the general trend. Low chlorine doses (<7 mg/L) resulted in low Cb/N ratios and essentially no THMs. In these limited data sets, total chlorine doses (for pre- and postchlorination) of 13 to 20 mg/L resulted in 19 to 64 ug/L TTHMs, whereas total chlorine doses of >21 mg/L resulted in 48 to 105 ug/L TTHMs. The correlation coefficients r and r2 for the chlorine-dose/TTHM-formation relationship (i.e., best-fit line not forced through zero) are 0.829 and 0.688, respectively; a high degree of scatter occurred in the data (Figure 8.4).

For the 1988/89 data set, plant-effluent DOX concentrations ranged from 200 to 350 ug C17L, HAAS concentrations were 18 to 35 ng/L, and the CNC1 concentrations ranged from 5 to 12 ug/L. These CNC1 results are higher than those detected in the current distribution system (1.4 ug/L); however, the 1988/89 samples were collected at the plant effluent and may not reflect the full effect of base-catalyzed hydrolysis in the distribution system.

In ozone pilot plant tests of colored groundwater performed by other investigators, ozonation was found to oxidize the hydrogen sulfide, destroy color, and significantly reduce the THM formation potential (Dunkelberger et al. 1992). Ozonation, however, did not have a significant impact on the HAA formation potential. Other analyses of this colored groundwater after ozonation and biofiltration with a 2-h SDS test—with a 4.2 mg/L free chlorine dose in a sample with 1.6 mg/L of raw-water ammonia-nitrogen—yielded 5.9 ug/L TTHMs and 15 ug/L HAAS (Glaze and Weinberg 1993). In this testing, DCAA was the major HAA formed (8.7 ug/L).

174

110

100 90 80

I70

3 6

0(A

50 40 30 20 10 0

i _ ii

._

_ ( _

..'1

r

~ -

-— —

^ ..........

..........

- -.—.

11

! /

........

. _._

... i

. ..

1 i

/

: • : i : +„«

..-„

..*—

'"""

•

...-"

•''....

........

........

... ...._

...

f i /

•i •i

/i » »

•' *

.._; ..-

* !

.* '

................

................

............ ..

................

................

.............^.

.....-..........

................

......_

f lUU

SI

MIIIIIIU

IIIC

1 •

• £

Hyd

roge

n Su

lfide

=2

- 3.1

mg/

L,

: 0.3

- 0.

6 m

g/L

•-

i .

....

. . i

......

... ..

.. ...

. ...

.. ..—

10

15

20

Tota

l Chl

orin

e Do

se (m

g/L)

2530

Figu

re 8

.4 Ef

fect

of c

hlor

ine

dose

on

TTHM

form

atio

n in

col

ored

gro

undw

ater

s

Northeastern Creek Water


Figure 8.5 and Table 8.10 show the current treatment of the northeastern creek water and the DBF data for the finished water. The finished water, however, represents a blend from two different treatment plants (40-60 percent was from the treatment plant treating the creek water). The water was prechlorinated to breakpoint-chlorinate the source-water ammonia (0.1 mg/L); conventionally treated with alum coagulation; partially dechlorinated with sulfur dioxide addition (0.22 mg/L); and postchloraminated at a Clj/N ratio of 3/1 (where the ratio equaled the filter-effluent chlorine residual plus the postchlorination dosage divided by the ammonia dosage). The finished-water pH was 7.1. The source water was subjected to three bench-scale experiments, with C12/N ratios of 2.7/1 and 4.5/1 at pH 8 and with a C12/N ratio of 4.3/1 at pH 6. The Cb/N ratio in the bench-scale experiments is based on the sum of the source-water ammonia and ammonia present in the preformed chloramines, as no prechlorination was used in these experiments to breakpoint-chlorinate the source-water ammonia.

As was observed in tests on the three primary waters (Figures 5.7, 5.8, and 5.9), a significant percentage of the chloramines at pH 6 was dichloramine (68 percent). In these bench- scale tests, the highest DOX and THM formation was at pH 6, whereas a greater amount of HAAs were produced at pH 8. In Task la testing at either a C12/N ratio of 3/1 or 5/1, DOX formation in LHW (Figure 5.15) and CSPW (Figure 5.17) was higher at pH 6 than at pH 8, whereas the maximum DOX for LAW (Figure 5.12) was at pH 8 for a C12/N ratio of 5/1.

In the northeastern creek water, CNC1 formation was highest at a C12/N ratio of 4.5/1 and a pH of 8 (8 ug/L versus 3 [ig/L in the other two tests). Likewise, in the Task la study of ambient-bromide LHW, more CNC1 was formed at a C12/N ratio of 5/1 and a pH of 8 (16 ug/L) than at the lower C12/N ratio (2 ug/L) or the lower pH (7 ug/L).

The effect of bromide was negligible in this water, which contained an average level of bromide (50 ug/L). At pH 8, bromide utilization was highest for the HAAs, whereas at pH 6 it was highest for the THMs. CNBr levels were at or somewhat above the minimum reporting level of 0.5

176

POW

DERE

DAC

TIVA

TED

CARB

ON

HIGH

-LIF

TDI

STRI

BUTI

ONPU

MP

Figu

re 8

.5 W

ater t

reat

men

t pla

nt fl

ow sc

hem

atic

for n

orth

easte

rn u

tility

Table 8.10 Influence of water quality parameters on DBF formation in northeastern creek water

Treatment Plant

ParameterTOC

UV-254Br'

Free C12 dose

Ammonia dose

Total ammonia

CI 2/N

PH

TemperatureTime

Free CI2 residual

NH2C1 residual

NHC12 residual

Total C1 2 residual

DOX

CHC1 3

CHCl2Br

CHClBr2CHBr3

TTHM

MCAA

Source PreCl2 Units Watermg/L 2.0 NA

cm' 1 0.038 NA

ug/L 50 NA

mg/L 3.5

mg/L

mg/L 0.1 0.1

mg/mg >8/l7.4 NA

°C 13 NA

h

mg/Lt

mg/Lt

mg/Ltmg/Lf

ugClVL

ug/L

ug/Lug/Lug/L

ug/Lug/L

PostCl2 Dist. Syst.*

NA NA

NA NA

NA NA

1.2

0.50.6

3/1

NA 7.1

NA 17NA

NAJ

NAJ

NAJ

NA$

59

17.9

8.8

1.0ND

27.7

ND

Batch1

2.0

0.038

50

2.8

0.9

1.0

2.7/1

8.1

22

48

ND

1.76

0.09

1.85

75

3.2

BDL

ND

ND

3.2

ND

Batch2

2.0

0.038

50

4.6

0.9

1.0

4.5/1

7.8

22

48

ND

1.55

ND

1.55

89

2.5

BDL

ND

ND

2.5

1.3

Batch3

2.0

0.038

50

3.2

0.60.7

4.3/1

6.0

22

48

ND

0.58

1.25

1.83144

3.3

2.3

1.2ND

6.8

ND

(continues)

178


Parameter

DCAATCAABCAAMBAADBAAHAA6CNC1CNBrCNXTTHMOX/DOXHAA6OX/DOXCNXOX/DOXDBPOX/DOXn

n '(3/6)TTHM-Br/Br'HAA6-Br/Br-CNX-Br/Br"

Treatment PlantSource PreCl2 PostCl2 Dist.

Units Water Syst.*

ug/L 3.9ug/L 5.1ug/L 2.3ug/L NDug/L 1.2ug/L 12.5Ug/L 1 .4ug/L 0.8ug/L 2.2

%%%/O

/o

/O

%

Batch1

9.72.73.3ND0.816.52.6ND2.63.36.62.011.9

00.23

04.20

Batch2

6.42.73.82.01.8

18.08.30.58.82.25.85.713.7

00.42

08.40.7

Batch3

1.61.71.8NDND5.13.20.84.03.11.41.56.0

0.540.314.11.71.2

BDL = below detection limitDist. Syst. = Distribution SystemNA = Not analyzed or not availableND = Not detectedPost C12 = PostchlorinationPre C12 = prechlorination

*40-60 percent of distribution-system sample came from treatment plant treating creek water.fAs C12^Normally, the distribution system has 0.1-0.2 mg/L free C1 2 residual and 0.6-0.7 mg/L NH2C1residual.

179

The percentage of DOX that was accounted for by the measured DBFs was higher at pH

(12-14 percent) than at pH 6 (6 percent). DOX formation was highest at pH 6, but the makeup of the specific DBFs formed under these conditions was not as well characterized as at pH 8 (i.e., a

smaller percentage of the DOX was accounted for by the measured DBFs at pH 6).In the full-scale facility, DBF formation was different because the water was initially

breakpoint-chlorinated. (In addition, only 40-60 percent of the distribution-system sample came

from the treatment plant treating the creek water.) Under these conditions, the DBF precursors were allowed to react with free chlorine prior to postchloramination. THMs readily formed

during the prechlorination/postchloramination scheme (28 ug/L), whereas THM formation was

well-controlled during bench-scale chloramination (2-7 ng/L).On the other hand, HAA formation at pH 7-8 was similar in bench- and full-scale tests

(12-18 ug/L). During bench-scale chloramination at pH 8, DCAA was the major HAA formed

(6-10 ng/L), with a smaller amount of TCAA formation (3 |ig/L), whereas DCAA and TCAA

production during the prechlorination/postchloramination scheme were similar (4-5 ug/L each). In the 35-utility DBF study, in which most of the facilities utilized prechlorination with or

without postchloramination, the median occurrences of DCAA and TCAA in plant effluents

were comparable (4-7 ug/L each) (Krasner et al. 1989a). These results, and those observed for

other Task la and Task 3 waters in this study, suggest that chloramination is more effective in controlling the production of THMs and TCAA than it is in controlling DCAA formation.


Table 8.11 shows historical data for the northeastern plant treating creek water. The

water was prechlorinated to breakpoint-chlorinate source-water ammonia and was postchloraminated at a Cb/N ratio of 3/1. TTHM concentrations ranged from 14 to 70 ug/L, and

HAA6 concentrations were 26 to 45 ng/L. These levels reflect the exposure of the DBF precursors to free chlorine during prechlorination. In these samples, TCAA levels (19 to 28

ug/L) were higher than the DCAA concentrations (2 to 14 |4.g/L), which is opposite to the trend

observed during bench-scale chloramination, where free-chlorine contact was not experienced.

Surface-water systems that have source-water ammonia typically will breakpoint chlorinate, so that a free chlorine residual is available for disinfection credit. At the northeastern

180

oo

Tabl

e 8.1

1

Hist

oric

al D

BF d

ata

for n

orth

easte

rn u

tility

trea

ting

cree

k w

ater

Mar

ch 1

5, 19

94

Para

met

er

TOC

C12 d

ose

Am

mon

ia

dose

C12/N

pH Tem

p.CH

C13

CHCl

2Br

CHCl

Br2

Pre

Uni

ts In

f. C1

2

mg/

L 4.

7 N

Am

g/L

4.8

mg/

L

mg/

mg

>8/l*

7.3

NA

°C Hg/L

ug/L

Hg/L

Post

C12

NA 0.6

0.2

3/1 6.7

Eff.

Inf.

NA

2.

2

7.0

7.3

5 15.7

5.9

0.7

June

23,

199

4

Pre

Post

C12

C12

NA

N

A

4.9

2.8

0.7

>8/l

3/1

NA

6.

9

Sept

embe

r 1 3

, 1 9

94

Dec

embe

r 1 3

, 1 9

94

Eff.

Inf.

NA

2.

3

7.1

7.321 31

.9

16.1

2.4

Pre

Post

C12

C12

NA

N

A

2.5

2.3 1.0

>8/l

3/1

NA

6.

8

Pre

Eff.

Inf.

C12

NA

2.

2 N

A 5.3 >8/l

7.1

7.2

NA

22 42.4

22.8

5.1

Post

C12

NA 1.1 0.5

3/1 6.8

Eff. NA

7.0 5 8.3 4.3 1.5

(con

tinue

s)

Tabl

e 8.

11 (

cont

inue

d)

Para

met

er

CHBr

3TT

HMM

CAA

DCAA

TCAA

BCAA

MBA

A^

DBAA

10

HAA6

Units Hg

/LHg

/L"g

/L"g

/LHg

/LHg

/L|ig

/L"g

/LHg

/L

Mar

ch 1

5, 19

94

Pre

Post

Inf.

C12

C12

Eff.

Inf.

ND

22.3

ND

14.5

28.0 1.9 0.4

0.2 45.0

June

23,

1994

Pre

Post

C12

C12

Eff. ND

50.4

ND 2.2

20.4 1.3 1.1 1.0 26.0

Sept

embe

r 13,

1994

Pre

Post

Inf.

C12

C12

Eff.

ND

70.3

ND 2.9

19.2

4.7 0.5 0.2 27.5

Dec

embe

r 13,

1994

Pre

Post

Inf.

C12

C12

Eff. ND

14.1

ND 7.3 24.6

2.9 1.1 1.2 37.1

Eff.

= Ef

fluen

tIn

f. =

Influ

ent

NA

= n

ot an

alyze

d or

not

avai

labl

e

ND

= n

ot d

etecte

dPo

st C1

2 = P

ostc

hlor

inat

ion

Pre

C12 =

Pre

chlo

rinat

ion

Tem

p. =

Tem

pera

ture

*Pre

chlo

rinati

on u

sed

to b

reak

poin

t-chl

orin

ate

sour

ce-w

ater

amm

onia.

plant treating creek water, the THM and HAA formation was curtailed with postchloramination. These historical DBF levels are below the proposed Stage 1 MCLs for TTHMs and HAA5 (0.080 and 0.060 mg/L, respectively). Compliance, however, with the proposed Stage 2 MCLs of 0.040 mg/L TTHMs and 0.030 mg/L HAAS might require a change in treatment (e.g., a switch to an alternative disinfectant for primary disinfection, with chloramines for secondary disinfection), as the historical HAAS concentrations—excluding the BCAA values—were 23 to 42 ug/L.

Pacific Northwest Lake Water


Figure 8.6 and Table 8.12 show the current treatment of the Pacific Northwest lake water and the DBF data for the finished water. The water is low in both TOC (1.4 mg/L) and bromide (7 |ag/L) and is an unfiltered supply. It is chlorinated for disinfection, and ammonia is added (2- 5 h downstream) at a Cb/N ratio of 4.7/1 for distribution, with a finished-water pH of 6.7. Historically, the utility treating this source water added the ammonia 30 s after the chlorine at a Cb/N ratio of 7/1. This historical chloramination scheme produced a total chlorine residual of 1.7 mg/L on the average (in 1990), with average residuals of 0.7 and 1.0 mg/L for mono- and dichloramine, respectively. The source water from this utility was subjected to three bench-scale experiments, with C12/N ratios of 7/1 and 5/1 at pH 6.3 and at a C12/N ratio of 5/1 at pH 7.4.

As was observed in tests on the three primary waters, dichloramine formation was significantly influenced by pH and Cb/N ratio (Figures 5.7, 5.8, and 5.9). Bench-scale chloramination at pH 6.3, with Cb/N ratios of 7/1 and 5/1, resulted in the dichloramine residual representing 79 and 32 percent of the total residual, respectively, whereas at pH 7.4 and a Cb/N ratio of 5/1, dichloramine only accounted for 3 percent of the total residual. The high percentage of dichloramine produced in the bench-scale test at a Cb/N ratio of 7/1 and at a pH of 6 is comparable to the historical full-scale percentage (60 percent).

DOX and HAA formation were higher at pH 6.3 than at pH 7.4. (No THMs were formed at either pH in the bench-scale experiments.) As has been observed in the other Task la and Task 3 waters in this study, DCAA was the major HAA produced (10-13 ng/L at pH 6.3). CNC1

183

00

WA

TER

SHED

A

ND

SU

PPLY DI

VERS

ION

DAM

AN

D HE

ADW

ORK

S

DAM

NO

. 1

CH

LOR

INE

DAM

NO

. 2

AM

MO

NIA

Figu

re 8

.6 W

ater

trea

tmen

t flo

w sc

hem

atic

for P

acifi

c N

orth

wes

t util

ity

Table 8.12

Influence of water quality parameters on DBF formation in Pacific Northwest lake water

ParameterTOCUV-254Br'

Free C12 doseC12/NpHTemperatureTimeFree C12

residualNH2C1

residualNHC12

residualTotal C1 2

residualDOXCHC13CHCl2BrCHClBr2CHBr3TTHMMCAADCAATCAA

Source Treatment Units Water Plantmg/L 1.4 NAcm' 1 0.028 NAug/L 7 NAmg/L 2.6

mg/mg 4.7/17.0 NA

°C 9.3 NAh

mg/L*

mg/L*

mg/L*

mg/L*

ugCl'/LHg/LHg/L"g/L|^g/Ll^g/L"g/LHg/Lug/L

Dist.Syst.NANANA

6.710

320ND

NA

NA

0.67

8510.6BDLBDLBDL10.61.016.318.5

Batch1

1.40.028

73.47/16.32248

0.05

0.31

1.33

1.69

39BDLNDNDNDNDND9.72.7

Batch2

1.40.028

73.25/16.32248

ND

1.24

0.59

1.83


Batch3

1.40.028

74.55/17.42248ND

2.42

0.08

2.50


(continues)

185


ParameterBCAA

MBAA

DBAA

HAA6

CNC1

CNBr

CNXTTHMOX/DOX

HAA6OX/DOX

CNXOX/DOX

DBPOX/DOX

n

n ' (3/6)

TTHM-Br/Br-

HAA6-Br/Br-

CNX-Br/Br'

Source Treatment Dist. Units Water Plant Syst.jig/L 2.1

Hg/L ND

Hg/L ND

^g/L 37.8

Hg/L 2.8

Hg/L 0.6

Hg/L 3.4

%

%

%

%

%

%

%

Batch 1

1.8

ND

ND

14.2

2.4

0.5

2.9

0

10.7

4.1

14.8

NA

0.10

0

11.8

5

Batch2

1.5

ND

ND

16.1

2.3

0.5

2.8

011.2

4.2

15.5 ,NA

0.07

0

9.8

5

Batch3

2.7

ND

NR

8.0

6

0.5

7

010.0

13.7

23.7

NA

0.29

017.7

5

BDL = Below detection limit.

Dist. Syst. = Distribution System

NA = Not analyzed or not available.

ND = Not detected.

NR = Not reported; interference with DBAA peak in this sample.

*As C12

186

formation was highest at pH 8 (6 ng/L, versus 2 ug/L at pH 6), which is consistent with that observed for LHW and the northeastern creek water tests at a C12/N ratio of 5/1 (Table 8.10).

The percentage of DOX that was accounted for by the measured DBFs (15-24 percent) was consistent with other waters in this project (Figures 5.24, 5.25, and 5.26). HAAs accounted for 10-11 percent of the DOX (on a molar basis) in each of the bench-scale tests, whereas the CNXs varied from 4 to 14 percent of the DOX.

In the current full-scale treatment, the free-chlorine contact time resulted in a significantly higher concentration of DOX compared to that found in the batch studies (85 versus 27-39 ng C17L with bench-scale chloramination), as well as a higher HAA6 concentration (38 versus 8-16 ug/L) and THM formation (11 |ig/L). As observed with the prechlorination scenario for the northeastern creek water (Table 8.10), DCAA and TCAA formation were now comparable (16-18 ug/L of each). CNC1 formation, however, was consistent with that seen in the bench-scale tests at pH 6.3 (2-3 ng/L). The prechlorination changed the amount and speciation of the THMs and HAAs formed, whereas the postchloramination produced CNC1 results similar to those of the bench-scale chloramination. The testing in this water confirmed that chloramines minimize THM and TCAA formation, whereas DCAA can be produced at a significant level during chloramination.


Tables 8.13 and 8.14 show historical data for the Pacific Northwest facility. In 1991, the water was chlorinated, followed 30 s later by ammonia addition at a 7/1 Cb/N ratio, whereas in the 1994/95 data sets, the water was chlorinated, with ammonia addition 2-5 h later at a 5/1 Cb/N ratio. The THM/HAA data represent the average values of four distribution-system locations with average retention times of 58 to 68 h. In the 1991 data set, TTHM concentrations were relatively low (1-5 ug/L), whereas with the current prechlorination scheme the TTHM concentrations have been up to 14-18 ug/L. The HAA results appear to be higher with the new disinfection scenario. The HAAS concentrations (without BCAA) were 15 and 26 ng/L on the two sample dates for which HAA data were available in 1991, whereas the HAA6 concentration (with 0-2 \ig/L BCAA) was 29-40 ng/L in the 1994/95 data set These results are similar to those

187

00 oo

Tabl

e 8.

13

Hist

oric

al (1

991)

DBF

dat

a for

Pac

ific

Nor

thw

est u

tility

Febr

uary

20,

199

1

Para

met

er

TOC

Bf

Free

C12

dose

C12/N

PH Tem

p.

DO

X

CHC1

3

CHCl

2Br

Sour

ce

Trea

t.

Uni

ts W

ater

Pl

ant

mg/

L 1.3

N

A

ug/L

<5

0 N

A

mg/

L 1.8

mg/

m

7/1

g6.

9 N

A°C

ug C

17L

ug/L

ug/L

Dist

.

Syst.

NA

NA 6.8

NA 73 5.0

ND

Apr

il 9,

199

1

Sour

ce

Trea

t.

Wat

er

Plan

t

1.4

NA

<50

NA 1.8 7/1

6.9

NA

Dist

.

Syst.

NA

NA 6.9 8.5

NA 1.2 ND

Aug

ust 2

0, 1

991

Sour

ce

Trea

t.

Wat

er

Plan

t

1.1

NA

NA

N

A 1.8 7/1

7.4

NA

Dist

.

Syst.

NA

NA 6.7

17.5

NA 4.2 0.8

Dec

embe

r 10,

1991

Sour

ce

Trea

t.

Wat

er

Plan

t

2.2

NA

NA

N

A 1.8 7/1

6.8

NA

Dist

.

Syst.

NA

NA 6.5 6.0

120

4.2

ND

(con

tinue

s)

Tabl

e 8.

13 (

cont

inue

d)

00

Para

met

er

CHCl

Br2

CHBr

3TT

HM

MCA

A

DCA

A

TCA

A

MBA

A

DBA

A

HAAS

CNC1

Uni

ts

Hg/L

Hg/L

HB/L

"g/L

Hg/L

Hg/L

ug/L

ug/L

ug/L

ug/L

Febr

uary

20,

199

1

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND

ND 5.0

NA

NA

NA

NA

NA

NA

NA

Apr

il 9,

1991

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND

ND 1.2 NA

NA

NA

NA

NA

NA 6.4

Aug

ust 2

0, 1

991

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND

ND 5.0

ND

13.6

12.3

ND

ND

25.8

NA

Dec

embe

r 10

, 199

1

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND

ND 4.2

ND 15 ND

ND

ND 15 NA

Dist

. Sys

t. =

Dist

ribut

ion

Syste

mN

A =

Not

ana

lyze

d or

not

ava

ilabl

e.

ND

= N

ot d

etec

ted.

Tem

p. =

Tem

pera

ture

Trea

t. Pl

ant =

Tre

atm

ent P

lant

Tabl

e 8.

14

Histo

rical

(199

4/95

) DBF

dat

a for

Pac

ific N

orth

wes

t util

ity

April

12,

1994

Para

met

er

TOC

Br'

Free

C12

dose

C12/N

pH Tem

p.D

OX

CHC1

3CH

Cl2B

rCH

ClBr

2

Sour

ce

Uni

ts W

ater

mg/

L 1.1

fjg/L

N

A

mg/

Lm

g/m

g7.1

°C

MgC

lVL

Mg/L

Mg/L

Mg/L

Trea

t.

Plan

t

NA

NA 1.8 5/1 NA

Dist.

Syst.

NA

NA 6.4

9.0

NA 13 0.7

ND

Aug

ust 2

, 199

4

Sour

ce

Trea

t.

Wat

er

Plan

t

1.2

NA

NA

N

A 1.7 5/17.

0 N

A

Dist.

Syst.

NA

NA 6.7

NA

NA 15 1.1 ND

Dec

embe

r 6, 1

994

Febr

uary

14,

1995

Sour

ce

Trea

t.

Wat

er

Plan

t

2.0

NA

NA

N

A 1.8 5/17.

2 N

A

Dist.

So

urce

Syst.

W

ater

NA

1.4

NA

N

A

6.7

7.37.2 N

A 17 0.8

ND

Trea

t.

Plan

t

NA

NA 1.8 5/1 NA

Dist.

Syst.

NA

NA 6.7 6.5 NA 14 0.5 ND

(con

tinue

s)

Tabl

e 8.

14 (c

ontin

ued)

Para

met

er

CHBr

3

TTH

M

MCA

A

DCA

A

TCA

A

BCA

A

MBA

A

DBA

A

HA

A6

CNC1

Uni

ts

"g/L

Hg/L

Hg/L

"g/L

ug/L

ug/L

Mg/L

"g/L

Hg/L

Hg/L

Apr

il 12

, 199

4

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND 14 ND 16 13 ND

ND

ND 29 NA

Aug

ust 2

, 199

4

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND 16 ND 11 13 2.3

ND 2.0 28 NA

Dec

embe

r 6, 1

994

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND 18 ND 16 15 1.8 ND 1.2 34 NA

Febr

uary

14,

1995

Sour

ce

Trea

t. D

ist.

Wat

er

Plan

t Sy

st.

ND 15 ND 20 16 2.3

ND 1.5 40 NA

Dist

. Sys

t. =

Dist

ribut

ion

Syste

mN

A =

Not

ana

lyze

d or

not

ava

ilabl

e.

ND

= N

ot d

etec

ted.

Tem

p. =

Tem

pera

ture

Trea

t. Pl

ant =

Tre

atm

ent P

lant

shown for the bench- and current full-scale data in Table 8.12. In one of the two HAA sets from

1991, DCAA was the only HAA detected, whereas DCAA and TCAA are the dominant HAAs in

all of the 1994/95 sets.Although the current full-scale disinfection scenario is resulting in higher levels of THMs

and HAAs, this scheme incorporates a significant amount of free-chlorine contact time, which is

mportant from a microbial perspective for the treatment of an unfiltered surface-water supply.

192

CHAPTER 9ANALYTICAL APPROACHES TO DETERMINE

"NEW" CHLORAMINE DBPs—TASK 4

OBJECTIVES

The objectives of Task 4 of this project were (1) to investigate analytical approaches for the determination of previously undetected DBPs associated with chloramination and (2) to use this protocol to measure chloramine DBPs.

To accomplish this, the following scheme was used:

• Evaluate suitability of liquid chromatography (LC) and LC-mass spectrometry

(MS) analytical methods for the determination of high polarity, low volatility chloramine DBPs, with particular emphasis on N-chloro organic compounds.

• Evaluate and implement concentration techniques to improve sensitivities

(detectability) for semivolatile chloramine DBPs.

• Characterize chloraminated samples by apparent molecular weight (AMW) and relate the distribution of AMW to the methods being developed.


Inorganic chloramines are weaker oxidants than chlorine and would be expected to produce less fragmentation, incomplete oxidation of functional groups, and less halogenation per molecule of DBF precursor. The DBPs formed from chloramination would therefore tend to retain their general precursor polarity characteristics and general precursor structure and occur at lower concentrations than those produced by chlorination. Chloramine DBPs are also expected to cover a wide range of molecular weights and volatilities. To address these issues, a combination of three approaches was used in this study to provide information on the nature of chloramine DBPs and insight into applicable analytical techniques. The work focused primarily on halogenated by-products as halogenated chlorine DBPs have been shown to be of health

concern (Bull and McCabe 1985).

193

Some chlorination by-products can also be formed by chloramination (e.g., THMs and HAAs); therefore, as a starting point, various chlorine DBFs were used as model compounds to evaluate analytical techniques. Some of the model compounds were also studied in Tasks 1 to 3

to determine if they could be produced by chloramines.

Because only approximately 10 to 20 percent of the DOX produced during

chloramination could be accounted for by target compounds measured with gas chromatography

(GC) (Tasks 1 to 3), LC techniques were explored for chloramine DBFs. LC separation coupled

with UV absorbance and MS detection was evaluated for the analysis of N-chloro organic compounds (organic chloramines) and related compounds that are polar, reactive, and nonvolatile. Two methods of interfacing LC and MS were evaluated, particle beam (PB) and

electrospray ionization (ESI).Concentration techniques were evaluated to increase sensitivity for chloramine DBF

detection. An on-line enrichment method was developed for LC, and to further increase

concentration, a separate graphitized carbon (carbopak-B) solid phase extraction (SPEB)

technique was explored. Simultaneous distillation extraction (SDE) concentration, coupled with

GC-MS, was adapted for detection of semivolatile chloramine DBFs.

To provide a better understanding of the nature of chloramine DBFs and to determine the extent of chloramine DBFs detectable by the techniques developed in this study, work was undertaken to determine the size (i.e., molecular weight) distribution of the organic matter and, specifically, the halogenated organic matter after chloramination. An ultrafiltration (UF)

technique was evaluated and utilized to study chloramination effects on a variety of waters.

Results obtained with this approach are expected to guide future detection and analyses.

LC TECHNIQUES FOR POLAR DBFs

Overview

High performance LC was selected as an approach for separating polar chloramine DBFs of low volatility, such as N-chloro organic compounds, prior to identification by MS. The high polarity, low volatility, and instability associated with these by-products make LC a logical

194

choice for chromatographic separation. Many similar compounds are not amenable to GC

techniques unless they undergo complex derivatization processes.

The early portion of the study focused on "bringing on-line" a suitable LC method,

utilizing a UV detector, before investigating the feasibility of using PB as the interface to couple

the LC with the MS for specific compound identification. In addition to chromatographic

conditions, sample concentration techniques, detection, and MS interfacing were evaluated. To

improve detection of low-level chloramine DBFs, on-line enrichment, SPEB, and UF were

investigated. (UF is discussed in a later section.) Post-column KI (potassium iodide)

derivatization (Yoon and Jensen 1993a; 1993b) combined with UV absorbance and MS,

independently or in parallel, was used for detection and compound identification. The use of

conventional, microbore, and capillary reverse-phase LC systems was also explored. LC

conditions were optimized for sensitivity and chromatographic separation prior to PB-MS

interfacing. The initial work was developed and evaluated based on model compounds. Later

work also included analyses of natural waters. The analysis of a model compound was also

conducted using LC-ESI-MS.

Experimental

Model Compound Selection

The model compounds were selected based on chlorination studies of organic nitrogen-

containing wastewaters by Jersey and Johnson (1992) and others (Conyers and Scully 1993;

McCormick et al. 1993). N-chloro alkylamines are relatively stable and are close in character to

the inorganic monochloramine. Chlorinated amino acids and chlorinated peptides were selected

because of the occurrence of the parent compounds and related precursors in natural waters.

Chloramination is expected to form some of the same by-products as chlorination. Not all

chlorination by-products will be formed with chloramination, however, and other unique

chloramination by-products may be formed. Low-molecular-weight compounds were also

chosen to help identify chloramine DBFs that interfere in the total chlorine residual

measurements. These tests are used by utilities to measure disinfecting capability and by kidney

dialysis facilities as an indication of monochloramine removal. The chlorinated by-products of

195

five alkylamines (CLAMs), six amino acids (CLAAs), five peptides (CLPs), monochloramine, and dichloramine were selected as model compounds to be used for initial LC method development (see Table 9.1).

Reagents

The chlorine-containing model compounds are not commercially available. Solutions of the model compounds were prepared fresh daily by chlorination or chloramination of the parent amine, amino acid, or peptide. In some cases, the structure and amount of chlorinated product(s) formed varied with reaction conditions; however, for consistency, the concentrations of model compounds used in this work refer to the initial concentration of the parent compound. Stock solutions (approximately 30,000 mg/L) of each parent amino acid and peptide (Aldrich, Milwaukee, Wis.) were prepared in acidified water to dissolve the compound. Each parent amine was dissolved in water without acid. The chlorine solution (approximately 4,000 mg/L as C\2) was prepared using sodium hypochlorite and buffered at pH 7 with potassium dihydrogen phosphate. The chlorine stock solution was standardized daily using a colorimeter (Hach Model DR-1A, Loveland, Colo.) or an amperometric titrator (Hach, Loveland, Colo.) (Standard Methods; APHA et al. 1992).

Ammonium chloride (1,000 mg/L as N) was used as the ammonia source.The phosphate buffer, 0.02 M and 0.002 M, pH 6.2, was used to maintain pH. The

preparation of the mobile phase included pH verification, filtering through a 0.22-um membrane filter, and degassing by vacuum filtration or sonication daily.

The KI derivatization reagent (pH 4) was 0.09 M KI in 0.24 M acetic acid/0.054 M sodium acetate buffer.

Two solvent systems were used in the project. The first solvent system was methanol (B&J Brand, High Purity Solvent, Baxter Healthcare Corp., Muskegon, Mich.) and water (glass- distilled, reverse osmosis-treated Super-Q), whereas the second system was acetonitrile (B&J Brand, High Purity Solvent) and water. Whenever possible the methanol/water solvent system

196

vo

Tabl

e 9.1

Ch

lorin

ated

mod

el a

min

es, a

min

o ac

ids,

and

pept

ides

with

LC

rete

ntio

n tim

esPa

rent

Com

poun

d Na

me

Pare

nt C

hem

ical F

orm

ula

Pare

ntM

olec

ular

Weig

htRe

tentio

n Ti

me

ofM

odel

Com

poun

ds (m

in)

LC G

radi

ent*

Chlo

rinat

ed A

min

es (C

LAM

s)Am

mon

ia (m

onoc

hlor

amin

e)Am

mon

ia (d

ichl

oram

ine)

Dim

ethyl

amin

eIso

prop

ylam

ine

n-Pr

opyl

amin

et-B

utyl

amin

en-

Buty

lamin

e

NH3

NH3

(CH

3)2-N

H2

(CH

3)2-C

H-NH

2CH

3CH

2CH

2-NH

2(C

H3)3-

C-NH

2CH

3-(CH

2)3-N

H2

17 17 45 59 59 73 73

5.8 9.4 13.0

29.9

31.5

33.9

38.8

3 3 1 1 1 1 1Ch

lorin

ated

Am

ino

Acid

s (C

LAAs

)Al

anin

eAr

gini

neVa

line

Phen

ylala

nine

Tryp

toph

anGl

ycin

e

CH3-C

H(NH

2)CO2

HHN

=C(N

H2)N

H(CH

2)3CH

(NH

2)C02

H(C

H3)2

-CH-

CH(N

H2)C

O2H

C6H5

-CH(

NH2)C

02H

C6H4

-(NHC

H=C)

-CH

2.CH(

NH2)C

O2H

NH2C

H2C

O2H

89 174

117

165

204 75

4.8,

22.1

6.4,

21.5

9.1,

41.0

ll.Sf

48.8

J3.3

, 9.8

2 2 2 2 2 3Ch

lorin

ated

Pep

tides

(CLP

s)Gl

ycyl

glyc

ine

Leuc

ylala

nine

Glyc

ylala

nine

Glyc

ylph

enyl

alani

neGl

ycyl

glyc

ylgl

ycin

e

NH2C

H2C

O-NH

CH2C

O2H

NH2C

H(CH

2CH(

CH3)2

)-CO-

NHCH

2CO

2HNH

2CH

2CO-

NHCH

(CH

3)C02

HN

H2C

H2C

O-NH

-CH(

CH2-C

6H5)C

02H

NH2C

H2C

O-NH

CH2C

O-NH

CH2C

02H

132

202

146

222

189

3.90

12.4,

26.5

3.9,

6.218

.2,2

5.2

4.0,

20.2

,31.

6

3 3 3 3 3

*LC

Grad

ient 1

: A=

Aceto

nitri

le; B

=0.0

2M p

hosp

hate

buffe

r, pH

6.2;

20%

A, 8

0% B

no

hold

; 50%

A, 5

0% B

in 2

5 m

in; 2

0% A

, 80%

B in

10 m

in.

LC G

radi

ent 2

: A

=0.0

02M

pho

spha

te bu

ffer,

pH 6

.2; B

=50%

A a

nd 5

0% M

eOH;

0-2

0% B

in 2

0 m

in; 2

0-70

% B

in 1

0 min

, hol

d 15

min

; 70-

100%

B in

5m

in, h

old

5 m

in.

LC G

radi

ent 3

: A=

0.00

2M p

hosp

hate

buffe

r, pH

6.2;

B=5

0% A

and

50%

MeO

H; 0

-20%

B in

10 m

in; 2

0-70

% B

in 1

0 min

, hol

d 10

min

; 70-

100%

B in

5m

in, h

old

5 m

in.

t Datu

m w

as n

ot co

llecte

d lo

ng en

ough

to v

erify

the p

rese

nce

of a

seco

nd p

eak.

JThi

s com

poun

d di

splay

ed o

nly

one

chro

mato

grap

hic p

eak.

was used instead of the acetonitrile/water system because of the negative health effects associated with acetonitrile.

LC Systems

Two LC systems were used during the methods development process (see Figure 9.1). (Table 9.1 shows the LC gradients used.) One LC was a Waters model 600 MS LC system (Milford, Mass.) equipped with a Waters 484 UV detector and a Waters U6K injector. The other system was a Dionex DX300 Advanced Gradient Pump (Sunnyvale, Calif.) equipped with a Kratos Spectroflow 783 UV detector (Manchester, England [no longer in business]) and a Rheodyne 9000 injector (Cotati, Calif). Data collection and processing for both LC systems were performed using a Nelson Analytical Xtrachrom chromatography data system (Perkin- Elmer, Norwalk, Conn.) or Perkin-Elmer Nelson Turbochrom version 4 software (Norwalk, Conn.). Both LC systems were evaluated as conventional and microbore LC systems with KI- UV and PB-MS. The operating conditions are summarized in Table 9.2. The conventional LC column (Alltech, Deerfield, 111.) was 4.6 mm ID x 250 mm with Econosil C18, 5-fj.m particles. An Alltech Versapak LC column with the same dimensions and specifications was also used and provided similar separations with approximately 40 percent reduction in LC pump pressure.

The Waters conventional LC was also operated as a capillary LC system after replacing the conventional flow parts with commercially-available capillary LC components (LC Packings, San Francisco, Calif). The conversion to a capillary system required replacing the conventional injector with a micro-injector capable of injection volumes down to 160 nL, replacing the conventional UV flow cell with a capillary flow cell (UZ-WA84, LC Packings), replacing the conventional column with a capillary packed column (12-inch [30.5-cm] length, 320-um ID, 5-um Ci 8 packing [FUS-30-05-Ci 8], LC Packings), and adding a mobile phase splitter (Acurate® IC-70, LC Packings). The narrow capillary LC peaks allowed for improved separation of compounds compared to conventional and microbore size columns. The capillary LC system operated with flow rates between 1 to 10 nL/min. The packed capillary column provided increased LC resolution (specification of 75,000 plates) and yielded LC peak widths on the order of 45 to 60 seconds wide.

198

Reag

ent

Wat

er

Enric

hmen

t Pu

mp

J 7HP

LC

Pum

p

J 7M

obile

Ph

ase

A5

mL

Sam

ple

Loop

Mob

ile

Phas

e B

Switc

hing

Va

lve

Anal

ytic

al

Colu

mn

Enric

hmen

t C

olum

n

Was

te

Teflo

n'O

pen

Tubu

lar

Reac

tor

UV D

etec

tor

at 3

53 n

m

Parti

cle

Beam

Inte

rface tt

Mas

s Sp

ectr

omet

eran

dC

ompu

ter

Data

Sys

tem

Vacu

um

Pum

ps

Split

Pum

p

Kl

Post

-Col

umn

Reag

ent

.Com

pute

r Da

ta S

yste

m

Was

te

Figu

re 9

.1 H

igh

perfo

rman

ce li

quid

chr

omat

ogra

phy

syste

m h

ardw

are

conf

igur

atio

n

Table 9.2

Comparison of conventional, microbore, and capillary LC

Column internal

diameter (mm. I.D.)

Flow rates (uL/min)

Injection volumes (uL)

System pressure (psi)

System pressure (kPa)Efficiency (plates/m)

LC peak width (min)

Conventional

>4.0

500-2000

5-300

800-1700

5500-11,70020K-40K

1-2

Microbore

2.1

100-400

5-250

1500-2500

10,000-170035K-70K

1-1.5

Microbore

1.0

10-50

5-50L

1700-2700

11,700-18,60050K-90K

1-1.5

Capillary

0.32

5-15

0.060-10

2000-3000

13,800-20,90090K-120K

0.75-1.0

Capillary

0.20

1-10

0.06-5

2000-3000

13,800-20,200>100K

0.75-1.0

For LC detection, a UV detector (Kratos or Waters) was considered first as an MS

surrogate for the development of the LC separation because it is inexpensive to operate, readily

available, and could be used easily by a utility or commercial laboratory in the future. Because

UV absorbance by the CLAAs and the CLAMs is poor and the non-chlorinated amino acids

absorb UV light in the same region as the CLAAs, the KI derivatization method of Yoon and

Jensen (1993 a; 1993b) was used to lower the detection limit approximately 100 fold (compared

to UV alone) and to distinguish the CLAAs from the parent compounds. KI derivatization and

UV absorption at 353 nm will only detect those by-products that are oxidizable, such as the

N-chloro compounds that contain an active chlorine atom. The LC-KI-UV system was used

either as an independent system or in conjunction with PB-MS (see Figure 9.2). A separate

postcolumn addition pump (Model 100A, Altex, Beckman Instruments, Fullerton, Calif.) was

used to feed the KI solution into a mixing tee, where it reacted with the N-chloro compounds in

the sample and facilitated the release of the iodine product. A reaction delay tube (0.8 mm ID,

10-ft [305-cm] length coiled Teflon® tubing) was attached between the mixing tee and the UV

detector. The reaction delay tube was used to allow sufficient time for the reaction to reach

completion prior to UV detection of the iodine product (X = 353 nm). This method is similar to

that of Jersey and Johnson (1992) that combined KI postcolumn derivatization with

200

to

Extra

con

nect

or to

redu

ce n

ebul

izer

'g

as v

olum

e at

leas

t tw

ofol

d

Neb

uliz

er

Mod

ifica

tion

1—'

Skim

mer

s _

Des

olva

tion

Cha

mbe

r

Cus

tom

ized

Nee

dle

Hel

ium

In

let

Neb

uliz

er

Figu

re 9

.2 P

artic

le b

eam

with

neb

uliz

er m

odifi

catio

n

electrochemical detection of the iodine product. For the current study, however, the inorganic Is"

reaction product was monitored on the LC-UV detector at A,=353 run.The CLAMs, CLAAs, and CLPs were used to evaluate the LC-KI-UV system. The

method was also applied to compare DBF formation from chloramination and chlorination of the parent peptides. Equal molar amounts of (1) chloramines and peptides and (2) chlorine and peptides were used. The chloramines were preformed at a Cla/N weight ratio of 5/1. Chloraminations of gylcylalanine and glycylphenylalanine were also monitored at pH 6 and 8. To assess the applicability of the test to natural waters, six chloraminated LAW samples from Task la were analyzed by LC-KI-UV.

The LC-PB-MS work utilized a VG model TS-250 medium-resolution MS (Manchester, England) equipped with a modified VG Line particle beam interface (Lieu and West 1993; modified further for this work). The MS was operated in the electron impact (El) mode, resolution 0.5K, scanning from a 45 to 650 mass-to-charge ratio (m/z) at a rate of 1.0 sec/scan. The PB-LC-MS interface provided a means to introduce LC eluant into the MS and to produce El mass spectra of the eluting compounds. El spectra provide structural information and can be compared with the National Institutes of Standards and Testing (MIST) library of 62,000 compounds. The PB interface consisted of a nebulizer, a heated desolvation chamber, a set of skimmer lenses, and a probe inlet (see Figure 9.2). The solvent must be removed from the LC eluant prior to ionization of the sample compounds in the MS source. Inefficient removal of the solvent results in poor mass transport through the PB interface. This poor mass transport leads to low recoveries and poor sensitivities. Further degradation of sensitivity and reduction of instrument operation time result from use of highly aqueous mobile phases and inorganic buffers.

The system used for the ESI-MS work was the VG Autospec-OATOF high-resolution magnetic sector MS (Manchester, England). Effluent from a microbore LC system was connected through the ESI interface to the MS. The mass assignment was calibrated using the instrument's hall probe. The instrument was set up to collect low resolution (1,000 resolution, 10 percent valley definition) ESI data with a single point photomultiplier detector, at a scan rate of 4 sec/decade, over a mass range between 75 and 1,000 m/z. The LC flow rate into the ESI

was set to 20 ul/min. The LC column was a Waters NOVA-PAK microbore Cig column (2 mm ID x 150 mm, 5-um particles). The mobile phase was 75 percent methanol, 25 percent water,

202

operated under isocratic conditions. Sample volumes of 50 jaL were used to flush and fill a 10

pL injector loop.

Concentration Systems

An on-line enrichment system similar to that of Jersey and Johnson (1992) was used (see

Figure 9.3 a and b). A 2- or 5-mL loop in the LC injector enabled concentration of the sample by

a factor of 100 or 250 times, respectively. To accommodate a larger sample volume, the sample

was pumped into the enrichment column instead of into the injector. Both configurations had the benefit of backflushing the enrichment column (Waters dg NOVA-PAK) as opposed to the more commonly used forward-flushing technique. Backflushing of the enrichment column focused the sample more effectively than the forward-flushing technique and produced narrower

LC peaks. A separate LC pump (Model 100A, Altex) was used to load the sample onto the enrichment column with a 100 percent water mobile phase. After the sample had been

completely loaded onto the enrichment column, a 6-port valve (7125, Rheodyne, Cotati, Calif.)

was switched to allow the mobile phase (water and acetonitrile, or water and methanol) from the LC pumps to backflush the enrichment column and to move the organic compounds to the analytical column, where the chromatographic separation took place.

Direct sample loading of 30 mL of sample onto the enrichment column with a sample addition pump could theoretically provide a 3,000-fold sample concentration factor. Reagent

water spiked with early eluting inorganic chloramines and with the mid-range eluting N-chlorophenylalanine at pH 4, 6, and 8 was used to investigate breakthrough and recovery. The effects of pH on enrichment loading efficiency were also investigated. Because the polarity of the model compounds is strongly affected by pH, it was thought that the enrichment efficiency possibly could be improved by optimizing the pH in an attempt to maximize enrichment column,

retention.In addition, an off-line solid phase extraction concentration method was explored to

provide a higher concentration factor and allow more flexibility in flow rates and type of elution solvent. Graphitized carbon (carbopak-B) was selected as the solid phase because of its similarity of trapping mode to the DOX method and because it can retain a wide range of

203

Load Mode

Figure 9.3a Enrichment system valve configuration, load mode (dashmarked injector 9000

position) and inject mode (position shown)

Switching Valve 7125

Analysis Mode

Figure 9.3b Enrichment system valve configuration, analysis mode

204

compounds without pH adjustment. The method of Di Corcia and Marchetti (1991) for pesticide analyses was utilized in this study as follows. Sample (2 to 4 L) was passed through the washed carbon (250 mg or 350 mg) column. The adsorbed organic compounds were first eluted with 1 mL of methanol followed by 6 mL of a methylene chloride/methanol (80/20 percent on a volume basis) solution for the base/neutral compounds and then 6 mL of a methylene chloride/methanol (60/40) solution basified with 0.016 mol/L of potassium hydroxide for the acidic fraction. The acidic-fraction eluant was acidifed with 0.2 percent trifluoroacetic acid (on a volume basis), and then both eluants were individually concentrated with gentle warming and a stream of nitrogen to 0.5 mL and 0.3 mL, respectively. The theoretical concentration factor for a 4-L sample was 8,000 for the base/neutral fraction and 13,000 for the acidic fraction.

The SPEB concentration technique was intended to be a sample preparation mode for the LC-UV-PB-MS system. Preliminary evaluation was made using UV detection at 205 nm without KI derivatization and, at times, in series with PB-MS. The N-chloro model compounds were not used for evaluation of the SPEB method because of their instability and lack of PB-MS response. Instead, (1) caffeine was used as a surrogate; (2) a synthetic sample containing phenylalanine, methyl glyoxal, decadienal, atrazine, pyruvic acid, and benzaldehyde was used to represent miscellaneous contaminant types; and (3) raw and chloraminated LHW (batch and pilot plant) and CSPW (pilot plant) samples were tested. The conditions for the batch-tested LHW were a Cb/N weight ratio of 3/1 and a pH of 8; and the pilot plant sample conditions were a Cb/N weight ratio of 3/1 and a pH of 6. The CSPW pilot plant sample conditions were a Cb/N weight ratio of 5/1 and a pH of 8.

Results and Discussion

Concentration Techniques

On-line enrichment. Enrichment columns can be used with LC to obtain trace-level

detection (|o.g/L range) of chloramine DBPs in water. The sample enrichment system works on the assumption that the compounds of interest do not move significantly along the enrichment column when loaded with 100 percent water. The compounds in the sample are trapped on the enrichment column as the water used to load the sample continues through the enrichment

205

column and into a waste container. The compounds will begin to migrate through the enrichment column as an organic solvent is introduced into the mobile phase. Based upon this assumption, the enrichment process has a focusing effect on the trapped compounds as they are removed with the introduction of an organic solvent. In practice, some compounds do move significantly along the enrichment column even when there is no organic solvent present in the mobile phase, especially when large amounts of water are used to load the sample. These compounds do not focus well and result in unacceptable recoveries. On-line concentration using either the 2-mL or 5-mL sample loop injector and a Cig enrichment column was acceptable. The recovery for chlorodimethylamine with the 2 mL loop was 112 percent compared to a direct

10-uL loop injection.

Experiments were also conducted to investigate whether larger sample volumes (up to 30 mL) could be used to increase the concentration factor when using the enrichment process. Evaluation of this enrichment system to ensure adequate concentration of the sample was necessary to increase the probability of detecting trace levels of chloramine DBFs using LC-KI- UV and LC-MS.

At pH 8, breakthrough occurred after 10 mL (10 min at a flow rate of 1 mL/min) for both the inorganic chloramines and N-chlorophenylalanine. At pH 4, the N-chlorophenylalanine behavior was similar to pH 8. At pH 6, N-chlorophenylalanine breakthrough occurred at a similar time but to a much lesser degree. These results indicated the need to look at another on- or off-line sample concentration technique with a higher concentration factor than possible with the 5-mL loop Cig on-line enrichment or the need to increase the LC-MS sensitivity.

Graphitized carbon solid phase extraction. The SPEB extracts were evaluated by LC- UV-PB-MS. Caffeine surrogate recoveries were approximately 50 percent based on UV response for the base/neutral extracts, and caffeine was detected with the PB-MS system. In the synthetic sample, phenylalanine and benzaldehyde were also detected by UV, but not by PB-MS. For the acidic extract of chloraminated LHW, no peaks of interest (i.e., not also in the blank) were observed, but a large column-bleed peak may have masked other peaks of interest. In the base/neutral fraction of the chloraminated LHW, the largest peak was caffeine; however, some small unidentified peaks were detected by UV but not by PB-MS. Further work with the SPEB was suspended for the duration of the project but may be pursued later in combination with a more sensitive ESI-MS system to be discussed later. Evaluation of the SPEB concentration

206

technique for chloramine DBFs concentration was inconclusive. From the work in this project,

the on-line concentration technique with an improved LC interface transport appears to be the

more promising combination.

LC System Modifications

LC gradient. Throughout the study, gradient LC techniques were used (see Table 9.1).

The LC mobile phases initially were 100 percent acetonitrile (mobile phase Al) and 100 percent 0.02 M phosphate buffer, pH 6.2 (mobile phase Bl), but they were changed to 50 percent

methanol/50 percent 0.002 M phosphate buffer, pH 6.2 (mobile phase B2), and 100 percent 0.002 M phosphate buffer, pH 6.2 (mobile phase A2). This ten-fold reduction in phosphate

concentration in the mobile phase provided improved LC separation and reduced the likelihood

of salt buildup in the PB-MS system. The sample was typically loaded onto the column with 100

percent buffer and programmed to 50 percent buffer, 50 percent solvent in two stages. The

specific programs are footnoted in Table 9.1.

PB-MS interface. The feasibility of using the LC-PB-MS technique to analyze for

chloramine DBFs and other previously unidentified DBPs was extensively evaluated. The use of

microbore and capillary LC columns improved PB performance by reducing the volume of solvent entering the PB interface. PB performance was improved because the mechanical pump

oil accumulated less solvent and was able to function more efficiently over a longer time period.

Mechanical pump oil was changed frequently as part of the normal PB maintenance.The PB nebulizer design must be able to accommodate high gas pressures without

introducing large volumes of gas into the source. Too much gas in the source will displace the

ion volume inside the source and prevent the sample from being ionized. Low nebulizer gas

pressures will not provide enough energy to form proper particle droplets or enough momentum

on the particles to pass through the skimmer lens. Optimization of gas pressure, gas volumes,

and LC flow rates was difficult to achieve and appeared to be highly dependent upon the

nebulizer design. No signal was obtained on the VG PB-MS with capillary LC flow rates. With

a modification to the PB, however, microbore flows were successfully coupled with the PB

interface. The modification consisted of adding a metallic insert to the nebulizer (see Figure 9.2

insert) to reduce the internal volume and channel the gas flow, thus permitting the use of higher

207

carrier gas pressures and velocity without significantly increasing the volume of carrier gas

going into the MS source. The higher carrier gas pressures provided additional kinetic energy

and velocity to the sample particles leaving the nebulizer orifice. This increased energy and

velocity compensated for the reduced flow of the microbore LC and helped the sample particles

travel across the skimmer region more effectively. The ability to accomplish this without

contributing additional carrier gas to the MS source was important. The metallic insert

modification and the use of the microbore column resulted in an increase in PB stability,

extended PB operation time, narrower, sharper peaks and an approximately two-fold increase in

sensitivity.

ESI-MS. When the PB results indicated possible loss of chlorine in the PB before entry

into the MS (see below) and UF data (to be discussed later) indicated the importance of higher

molecular-weight halogenated chloramine DBPs, ESI was investigated as the LC interface to the

MS. ESI is an emerging technique for LC-MS interfacing for many biomedical and

environmental applications, as indicated by the number of presentations on the topic at the 1995

American Society of MS conference in Atlanta, Georgia. ESI is superior to PB because it

provides much greater mass transfer through the ESI interface and yields greater sensitivity for

detecting compounds. Mass transfer through the ESI interface is enhanced because the sample is

ionized at atmospheric pressure. Once the compounds are charged, a lens with adjustable

potentials can be used to focus and guide the ions through the skimmer lens into the MS as the

remaining uncharged solvent is removed by the vacuum pumps. The optimal LC flow rate for

the VG ESI is between 10 to 40 uL/min (VG Analytical, Manchester, England).

The energies associated with ESI are much lower (i.e., softer) compared to the El

ionization energies associated with PB. This increases the likelihood of retaining the nitrogen-

chlorine bond during the ionization process. Results from an LC-ESI-MS experiment are

discussed in the model peptide section below.

LC Evaluation and Application

Model N-chloro organic compounds. The LC-KI-UV method was suitable for the

determination of inorganic mono- and dichloramine in drinking water (residuals in mg/L range)

without sample concentration. To determine the model N-chloro organic compounds at the

208

level, sample concentration was necessary. The LC conditions, however, were the same

regardless of concentration technique. The five model CLAMs could be detected at 50 |j,g/L

with the on-line enrichment column process and a 5-mL injection loop, post-column derivatization, and UV detection at 353 run.

Upon chlorination at a 1/1 molar Cla/N ratio, the amino acids tryptophan and phenylalanine each produced one LC/KI-UV peak within the time span monitored, whereas alanine, arginine, and valine produced two major peaks each (Table 9.1). CLAA peak responses were approximately ten times less than the peak responses for the CLAMs. This may be attributed, in part, to the formation of non-KI-reactive chlorine species in addition to the detectable chlorinated organic compounds. Using the more general PB-MS detector, under

excess chlorine conditions, spectra compatible with the corresponding aldehyde, nitrile, and N-chloroaldimine by-products were observed for valine, tryptophan and phenylalanine,

respectively. Conyers and Scully (1993) reported similar results for phenylalanine, and McCormick et al. (1993) reported similar results for valine. The detection limit (i.e., amount needed to obtain identifiable spectra), using the unmodified PB-MS, was approximately 50 to

100 ng for each amino acid with a 10 to 20 uL injection.

Mixtures of the model CLAMs produced LC responses comparable to separate injections of the individual compounds when injected within one hour of mixing. In contrast, mixtures of CLAAs and mixtures of CLPs (discussed below) produced LC chromatograms with peaks of different intensities. Furthermore, some new peaks were present that were not present for the individual CLAAs and CLPs. These results are consistent with those of Jersey (1991) and with a chlorine-exchange mechanism described by Isaac and Morris (1983a; 1983b) in which the more basic compounds have a greater tendency to bind the chlorine. The result of this competition in CLAA and CLP mixtures is the formation of unequal amounts of the chlorinated model compounds, with some peaks disappearing from the chromatogram. These results occurred when the compounds were combined either before or after chlorination. Similar chlorine transfer behavior was observed by Snyder and Margerum (1982) and by Yoon and Jensen (1993b).

Natural water samples. To evaluate the LC-KI-UV system as a screening method, six LAW samples (pH = 6, 8 and 10, Cb/N weight ratio = 3 and 7, ambient bromide, total chlorine residual = 2 mg/L) from the Task 1 batch chloramination experiments were analyzed using the

same LC conditions as for the CLPs (Table 9.1). Figure 9.4 shows the chromatograms for LAW

209

I 4 §

I 4 oii 3

<52S'l

0

as §I 3

I 4o

I 3

•« 2 v

Approximately 1.5 mg/L monochloramine and approximately 0.4 mg/L dichloramine

Products from the reaction of1.4 mg/L glycine and 1.3 mg/L chlorine

LAW chloraminated at pH 10, CI/N 7/1 total chlorine residual = 2 mg/L

LAW chloraminated at pH 8, CI/N 7/1 total chlorine residual = 2 mg/L

10 15 Time (min)

20 25 30

Figure 9.4 Chromatograms for LC-KI-UV analyses of LAW Task la samples and reference

solutions

210

tests at the 7/1 Ch/N weight ratio and pH 8 and 10, as well as a chloramine solution and a chlorinated glycine solution. The inorganic monochloramine peak and one or more small additional peaks were present in all LAW samples. A large dichloramine peak was observed in

the pH 6 samples and a small one in the pH 8 sample with the 7/1 C12/N weight ratio, as

expected. An early eluting peak present in all the LAW samples had a retention time similar to

that of the chlorination by-products of glycine, glycylalanine and glycylglycylglycine (Figure 9.4

and Table 9.1). The early eluting peak was largest (one-tenth to one-twentieth the area of the

inorganic monochloramine peak area) in the three 7/1 Cb/N weight ratio samples (pH 6, 8, and 10), with-the largest peak at pH 8. The peak area was approximately ten-fold less at the 3/1 Cb/N weight ratio. The baseline and chromatography of the LC-KI-UV method were not

impacted by the LAW matrix, and the technique appeared to be applicable to natural waters.Chlorination and chloramination of model peptides. The chromatographic retention

times exhibited by the by-products formed upon chloramination (5/1 Cb/N weight ratio) and chlorination of the model peptides using the LC-KI-UV system are given in Table 9.3. Equal

molar amounts of peptide and disinfectant were used. Chlorination of the peptide nitrogen is

reported to occur at the terminal amine nitrogen and not at the amide linkages (Pereira et al.

1973); therefore, for these calculations, each peptide molecule was considered to contain a single active nitrogen. Because the parent peptides do not react with the KI, no LC peaks were detected

for the unreacted peptides by this method. Free chlorine reacted with the peptides to form two, and in the case of glycylglycylglycine three, chlorinated by-products (as detected by LC-KI-UV). These compounds may be the mono and dichloro peptides (see ESI results below and Pereira et

al. 1973). Chloramination (5/1 Cb/N weight ratio, pH 6.2) of the peptides, however, yielded only one product. For glycylalanine and glycylglycylglycine, the chloramination DBF had a similar retention time to the earliest eluting compound as found after chlorination of the same peptide. The retention time of this early eluting peak was very close to that observed in the

chromatogram of the chlorinated glycine described above. For the leucylalanine and glycylphenylalanine, however, chloramination yielded different DBPs than chlorination.

Chlorination of glycylalanine rapidly yielded two products as shown in the

chromatogram (Figure 9.5D, peaks 1 and 2). Chloramination initially produced peak 1 (Figure

211

Table 9.3

Retention times for chlorination and chloramination

by-products of model peptides

Parent Peptide C12 DBF Chloramine DBP

Retention Time (min)* Retention Time (min)*

Leucylalanine 12.4,26.5 10.8

Glycylalanine 3.9,6.2 4.1

Glycylphenylalanine 18.2,25.2 15.1

Glycylglycylglycine 4.0,20.2,31.6 4.0

*LC gradient: 100% Solvent A; 0-20% solvent B in 10 min; 20-70% Solvent B in 10 min, hold

10 min; 70-100% solvent B in 5 min, hold 5 min.

Solvent A = 0.002 M phosphate buffer, pH 6.2.

Solvent B = 50% A and 50% methanol.

For comparison, the retention times for monochloramine and dichloramine are 5.4 and

9.9 min, respectively

9.5B) and inorganic mono- and dichloramine, and after 16 hours it showed the loss of the

monochloramine and the appearance of another very small peak between 6 and 7 minutes (Figure

9.5C). Peak 2 from the chlorine reaction had a slightly longer retention time than the second

product peak from the 16-hour chloramine reaction and, therefore, was assumed to be a different

compound. This experiment and another one with glycylphenylalanine showed that at pH 6.2,

the monochloramine rather than the dichloramine reacted with the peptides.

Task la data showed that pH strongly affects the DOX formation. Therefore,

chloramination of glycylalanine and glycylphenylalanine was studied at pH 6 and 8 by LC-KI-

UV. The chloramine DBFs detected had the same retention times at pH 8 as at pH 6; however,

the amounts formed were larger at pH 8. At pH 6, dichloramine was present but did not appear

to react. Because the total disinfectant residual was kept constant for both pH's, the reacting

monochloramine concentration was higher at pH 8 and may account for the difference in the

amount of DBPs formed. This relationship for the model peptides was consistent with the

212

9«f8I 7~ 6I5"to 4I 3

10 9

J7l g6

109

£8§7

IB« 4c _«3

1 09

£8I 7

1!f4is-2

1

.--_"-- ^

_1 I ^

-

^

-

'-^ V- v.

i I

.A

, , ,

--"

„-

-

I" , ,

v^.,,-..)

--•

—»•

J v**i , , . 1 . i°o ———— § ——

(D) Glycylalanine + chlorine (100 ppm)(several minutes)

^ __

. , ( , . , , i . , . . i , , , . i , , , ,

^ ————————————————————————— |

(C) Glycylalanine + chloramines(16-hr reaction time)

^

. , i . , . . i , , , . i . , , , i , , , ,

~~J

(B) Glycylalanine + chloramines (100 ppm)(1.5-min reaction time)

^iiltiiiliiiilfitilitfi

—^

(A) Monochloramine and dichloramine

V^> i i j . . i i i , i . i , , , , i , , , ,

10 15 20 25 3(Time (min)

Figure 9.5 Chromatograms for LC-KI-UV analyses of the chlorination and chloramination of glycylalanine (1/1 molar ratio, pH 6)

213

increased concentration of DOX formed in LAW at pH 8 versus pH 6 (at a 5/1 Cla/N weight

ratio) in the Task la batch studies (Figure 5.12).Identification of the chlorinated and chloraminated peptides by PB-MS was investigated.

Each of the model peptides was individually injected through the PB (no LC column) before and

after chlorination, and, in addition, glycylphenylalanine was studied after chloramination. The

mass spectra of the parent and chlorinated model peptide pairs were essentially the same for

reactions carried out under a 1/1 chlorine-to-peptide molar ratio. In order to verify that the

chlorination process with the peptides actually did occur, chlorine residual measurements and

LC-KI-UV injections were performed. In each case, the residual chlorine measurements

confirmed the absence of free chlorine. The LC-KI-UV injections of the chlorinated peptides

produced Kl-derived chromatographic peaks different from free chlorine, suggesting the

presence of N-chloro organic compounds. Under the operating conditions of the VG PB-MS (El

mode), however, the N-chloro mass spectra were not observed.

Identification of the chlorinated glycylalanine by-products by PB-MS was inconclusive.

Utilizing LC-ESI-MS for the analysis of the chlorinated glycylalanine, however, yielded two LC

chromatographic peaks (Figure 9.6) whose spectra (Figure 9.7) were consistent with sodium and

solvent adducts of the chlorinated glycylalanines: chloroglycylalanine at scan 76 and dichloro-

glycylalanine at scan 87. An interpretation of theses spectra appears in Tables 9.4 and 9.5,

respectively. Isotopic masses (181 and 183, 203 and 205, 221 and 222, 235 and 237, and 244

and 245 in Figure 9.7, scan 76) that were two mass units apart at an intensity ratio of 3:1 were

indicative of a compound containing one chlorine atom, and the masses matched those of

chloroglycylalanine (M) products. The isotopic cluster at 383, 385, and 387 m/z at an intensity

ratio of approximately 10:6:1, in addition, was consistent with the sodium adduct of the dimer

(2M). The compound at scan 87 produced mainly two chlorine-containing ions (i.e., those at

237, 255, 269 and 278 m/z) and a four chlorine cluster at 451 m/z (intensity ratios of

approximately 8:10:5:1 for 451:453:455:457 m/z) from the dimer. This spectrum was consistent

with dichloroglycylalanine. These results demonstrate the superior performance of ESI over PB

for coupling LC to MS for the analysis of this type of polar N-chloro DBF.

Microbore or capillary LC coupled with ESI to a high-resolution MS/MS system is the

recommended technique to further pursue chloramine DBP identification. An initial broadscreen

LC-ESI-MS analysis can provide preliminary halogen content and molecular weight information

214

Rel

ativ

e In

tens

ity (%

)R

elat

ive

Inte

nsity

(%)

Rel

ativ

e In

tens

ity (%

)

,2

o N> 3 ^

911

sa,

^ cn^ ° "

gCfli/i

0 -tp o •o

W _LC/a Ln HH g -

oa

1/3 o

t

>oOS 1°-S fQ5 N"

3f3 §-1ooi-b

& s-§. g

TO_ 0 '

O

£

§' i - CD ^^

cno .

Relative Intensity (%)

i i i i i i i i i

— w^o

L ——— 00 » 0

^J W ^

1 0) «<"

K*~> 0) OJ5'

p-

^~ w

S = — in• cS =. CO

r=— 10

-

p- ft=~—

"~

J,

BNcn

o o

s-

10o o

10S-

§.

CO§-

CO8-

g. o

so

S.

Relative Intensity (%)

i i i i i i i i i

- CD<SO§ ^f

r ^j II o

^afflox:|Sc SL *-* a>

3

(D

^ 00

i ro_ tn ro

S

.

-

E= ——————

8

r

Table 9.4

Electrospray mass spectrum interpretation for a reaction

product of chlorine with glycylalanine

(scan no. 76 in Figure 9.7, monochlorinated product, M)

m/z

181203221235244

383

Cluster

M + HM + Na

M + Na + H2OM + Na + MeOHM + Na + ACN

2M + Na

Number of Cl atoms

11111

2

ACN = acetonitrileM = chloroglycylalanine (180 Daltons)MeOH = methanol

Table 9.5

Electrospray mass spectrum interpretation

for a reaction product of chlorine with glycylalanine

(scan no. 87 in Figure 9.7, dichlorinated product, M')

m/z

237255269278

417451

Cluster

M'+NaM' + Na + H2O

M'+Na + MeOHM' + Na + ACN

2M' - Cl + H + Na2M'+Na

Number of Cl atoms

2222

34

ACN = acetonitrileM'= dichloroglycylalanine (214 Daltons)MeOH = methanol

217

for selection of possible DBFs for continued study. Subsequently, high-resolution MS and

MS/MS tests focused on a few peaks could be run to accurately determine the chemical composition and structure to aid in compound identification.

Conclusions

From these data, the following conclusions can be reached:

1. LC is a technique to separate polar N-chloro compounds.

2. Products formed by chloramination of peptides can be detected by postcolumn KJ dervatization with subsequent UV detection at 353 nm.

3. Chloramination of the small model peptides at pH 6 produced some but not all of the same Kl-reactive by-products formed by chlorination. Chloramination at pH

8 produced a higher concentration of the by-products than at pH 6 at a 1/1 molar Cb/peptide ratio. Analysis of a natural water appeared to indicate that

monochloramine, not dichloramine, reacted with small peptides to yield a KI-UV

detectable compound.

4. The PB-EI ionization MS system initially used for this study is not suitable for

determining the structure of N-chloro organic compounds because the chlorine is

often lost before detection.

5. The soft ionization technique of the ESI-MS system subsequently used for this study appears to be applicable to the LC-MS determination of polar N-chloro

compounds that are chloramination by-products.

This work provides guidelines for the continued study of chloramine by-products. An initial full-scan, low resolution LC-ESI-MS run can provide preliminary halogen-content and

molecular weight information. Subsequently, high resolution MS and MS-MS runs could focus

218

on several peaks of interest and accurately determine the chemical composition and structure for

DBF identification.

ANALYSIS OF DBFs BY SDE GC-MS

Overview

SDE was selected as part of the analytical scheme (1) because it selectively isolates

compounds of moderate volatility and polarity and (2) because of its high concentration factor

(theoretically 30,000 to 40,000 times). Determination of organic compounds at the ng/L to ug/L

concentration level has been reported by a number of researchers. The technique was originally

developed by Lickens and Nickerson (1964) for the analysis of hops in beverages. Researchers

have found that the SDE technique is an efficient method for the isolation of specific

compounds. Richard and Junk (1984) reported a high recovery for acidic, basic and neutral

compounds with the exception of acetic acid. Godefroot et al. (1982) reported a high recovery of

organochlorine pesticides and polychlorinated biphenyls at |ag/L levels. Onuska and Terry

(1985) found that the method was more efficient for the quantification of polychlorobenzene

isomers not only "time wise," but also by the simplicity of the method. During the extraction of

fatty acids from water, Janda and Pehal (1984) found that SDE gave recoveries close to 100

percent for €4 to Cn fatty acids. Those results agree with Richard and Junk (1984), in which

lower recoveries were only obtained for acetic and propionic acids. SDE provides good

recoveries for polar semivolatile organic compounds such as phenols and fatty acids, in addition

to offering some sample cleanup and salt removal. SDE in conjunction with GC-MS is well

suited to complement LC techniques and to help elucidate the low molecular-weight compounds

(i.e., < 0.5K daltons).

219

Analytical Methods

Sampling

Pilot-plant samples were incubated for 48 hours to simulate distribution system detention times, whereas utility full-scale samples were collected from locations with an approximate 48- hour detention time in the distribution system. Nonchloraminated control samples were also collected for each location. These controls were usually the source waters at the plant influent. Both samples were shipped iced by overnight delivery service to Metropolitan. No preservative or dechlorinating agent (except cooling to 4°C to minimize further DBF formation) was used. Samples were filtered through glass-fiber and 0.45-um pore-diameter nylon filters, and SDE analysis of the chloraminated sample was begun within 24 hours of receipt.

SDE

Four liters of the water sample and 50 mL of methylene chloride (E.M. Science, Gibbstown, N.J.) were simultaneously distilled from separate flasks (see Figure 9.8a). The steam and steam-distillable organic compounds generated from the water sample were mixed with the solvent vapors and extracted. Condensation and phase separation occurred along the water- cooled separation tube. The lower density liquid (water) returned to reservoir A, whereas the higher density methylene chloride—containing the extracted organic compounds—went to reservoir B. After three hours of continuous extraction, steam generation was stopped and the system was flushed with methylene chloride for another twenty minutes. Then the methylene chloride extract was collected, dried over anhydrous sodium sulfate, and further concentrated. The final concentration method used was the evaporative concentration system (Figure 9.8b) (Ibrahim and Suffet 1987a) followed by nitrogen blowdown to a final volume of 100 uL. The aqueous concentration factor for a 4 L sample concentrated to a final volume of 100 uL of methylene chloride is 40,000 times, presuming 100 percent efficiency.

1-Chloroalkanes were used as surrogates and internal standard (I.S.) compounds (Chem Services, Inc. West Chester, Pa.). 1-Chlorodecane (1 jag) was added to the water sample,

220

DryIce

Condenser

Mixing Chamber

Thermometer

Reservoir B (Water Sample)

Separation Chamber

Reservoir A (Solvent)

Heating Mantles

Figure 9.8a Simultaneous distillation extraction (SDE) apparatus

221

Recovery Condenser

Figure 9.8b Evaporative concentration system

222

1-chlorododecane (1 |^g) was added to the starting methylene chloride solvent prior to extraction,

and 1 -chlorooctane (1 jag) was added to the final concentrated methylene chloride extract prior to injection on the GC-MS.

Reagents, Blanks, and Controls

Methylene chloride was selected over pentane, hexane, diethyl ether, and Freon® as the extraction solvent. Because of its polarity, methylene chloride is better than pentane and hexane for extracting polar halogenated DBFs. It is less hazardous to reflux than diethyl ether and less environmentally damaging than Freon®. Methylene chloride is available with either cyclohexene or amylene as a preservative. Halogenated artifacts have been observed for both preservatives during extraction of samples with a free chlorine residual. With cyclohexene as the preservative, halogenated six-carbon cyclic compounds were found as artifacts following liquid-liquid extractions (LLE) of acidified brines (Campbell et al. 1987) and of chlorinated tap water (Dietrich et al. 1988). With amylene as the preservative, halogenated, non-cyclic, one-to-seven carbon compounds were found as artifacts (Fayad 1988). Cyclohexene was selected as the preservative because the artifacts from cyclohexene and chlorine were expected to be more easily distinguished from DBFs. Dechlorination of samples before SDE was not used because common dechlorinating reagents such as sulfur-reducing agents are known to degrade some DBFs (Croue and Reckhow 1989). Moreover, conversion of free chlorine residuals to chloramines by use of ammonium chloride addition minimized reactions to form such artifacts (Ibrahim et al. 1987b). Thus, extraction of chloraminated samples was believed to be manageable. A chloraminated water blank (pH = 8.4, monochloramine residual = 1.7 mg/L, total chlorine residual =1.9 mg/L) and source water (or a treated water sample before chloramination used as a control sample) for each test were analyzed to act as a blank and control, respectively.

GC-MS Analysis

The extracts were analyzed by GC-MS on either a Finnigan model 4023 quadrupole MS (Sunnyvale, Calif.) or a VG TS-250 magnetic sector MS. A 30-m, 0.25-mm ID DB-5 fused silica capillary column (J&W Scientific, Folsom, Calif.) was used with a temperature program

223

starting at 10°C (if cryogenic cooling was available) or 34°C, ramping initially to 70°C at 2°C/min, then to 150°C at 4 or 7°C/min, and finally to 250°C at 12°C/min, at which the GC was held for 10 min. The MS was scanned from 45 to 650 m/z at low resolution in the El mode at an electron energy of 70 eV. The scan rate was initially set at 0.6 sec/scan and was later changed to 1.0 sec/scan. Compounds were tentatively identified by comparison of their El MS spectra with the NIST library spectra or, in some cases, by manual spectra interpretation.

Samples Evaluated

The method was used to evaluate natural water samples covering a variety of matrices and treatment conditions. Samples representing five different water qualities—LAW, LHW, and CSPW (the three primary waters in Tasks 1 and 2); a Pacific Northwest water and a midsouth water (two waters from Task 3)—were selected. The midsouth water was tested because of its high bromide concentration (1.5 mg/L) and the Pacific Northwest water because of its low bromide and DOC. The general source water characteristics of these waters are given in Table 9.6.

The pilot-plant tests of Task 2 selected for the analysis of chloramine DBFs by SDE GC-MS included prechloramination followed by coagulation for each of the three primary waters. In addition, enhanced coagulation with postchloramination was monitored for the LHW pilot plant. The sampling was done in parallel with Task 2 runs, and the reference run numbers and sample dates are given in Table 9.6.

The SDE method was also used to evaluate drinking water from the full-scale distribution systems of three utilities utilizing chloramines as the final disinfectant (see Table 9.6). The midsouth water samples were collected with the Task 3 samples, whereas the Pacific Northwest water samples for SDE were collected from the same location as the Task 3 samples but were collected 13 days later. In addition, CSPW was sampled from the Henry J. Mills Filtration Plant. Furthermore, the latter three waters were fractionated by UF to determine the molecular weight distribution of the DOX and DOC, which is discussed in the UF section below.

Plant influent samples were also analyzed as controls. For the LHW pilot-plant analysis, the control sample was collected just prior to chloramination (i.e., after enhanced coagulation,

224

Tabl

e 9.

6 Sa

mpl

es fo

r SD

E an

alys

isPi

lot-P

lant

Sam

ples

C12/N

ratio

Disi

nfec

tion

scen

ario

*

Tota

l C12

resid

ual

(mg/

L)

PH Brom

ide

(mg/

L)

Trea

tmen

t con

ditio

ns*

Sam

ple

date

LHW

, Ru

n 1

3/1

Prec

hlor

a-m

inat

ion

2.6

7.5

0.05

Alu

mco

agul

atio

n

10/1

5/94

LHW

, R

un4A

3/1

Postc

hlor

a-m

inat

ion

2.6

7.8

0.05

Enha

nced

alu

mco

agul

atio

n

3/13

/95

LAW

, Ru

n 3

5/1

Prec

hlor

a-m

inat

ion

1.7 8.0

0.3*

*

Dire

ct fi

ltrat

ion

with

alu

m

11/1

4/94

CSPW

, Ru

n 1

5/1

Prec

hlor

am-

inat

ion

1.5 7.8

0.23

Alu

mco

agul

atio

n

9/28

/94

CSPW

, M

ills P

lant

Ef

fluen

t5/1

Prec

hlor

inat

ion,

posta

mm

onia

tion

1.6 8.3 0.13

FeCl

3co

agul

atio

n

5/10

/95

Full-

Scal

e Pl

ants

Paci

fic N

orth

wes

t W

ater

Dist

ribut

ion

Syste

m5/1

Prec

hlor

inat

ion,

posta

mm

onia

tion

1.2 6.8

0.00

7

Unfil

tered

5/30

/95

Mid

sout

h W

ater

D

istrib

utio

n Sy

ste

3.75

/1

Prec

hlor

a-m

i nat

ion

0.1 7.6 1.5 A

lum

coag

ulati

on

5/15

/95

* Se

e ch

apte

rs 7

and

8 fo

r mor

e de

taile

d di

scus

sions

of d

isinf

ectio

n sc

enar

ios a

nd tr

eatm

ent c

ondi

tions

.**

Bro

mid

e no

t mea

sure

d on

sam

ple

date;

val

ue ta

ken

from

pre

viou

s sa

mpl

ing

perio

d.

sedimentation and filtration). For the two waters in which chlorine and ammonia were added sequentially (i.e., at the Mills plant and in the Pacific Northwest water), SDE analysis of the chloraminated waters represented DBFs produced by the combination of chlorination and chloramination.


SDE combined with GC-MS was a very sensitive way to detect and identify the low levels of DBFs expected from chloramination of natural waters. The SDE method achieved a concentration factor of approximately 33,000 based on the recovery of surrogates, enabling GC- MS detection of chloramine DBFs at ng/L levels. More than 50 chemicals total were detected among the five varied chloraminated waters described above (Table 9.7). Although the

• chemicals detected in the Mills and Pacific Northwest samples may reflect the prechlorination, numerous chemicals in the other samples may be a result of chloramination. The most prevalent class of compounds detected consisted of the mixed halogenated THMs containing various combinations of iodine, chlorine, and bromine atoms. Dihalomethanes, halonitriles and other nitriles, and, possibly, small amounts of oxygenated organic compounds were also detected in the chloraminated waters.

Because quantitative standards were not run, these results are qualitative. Compounds detected in both the source and chloraminated waters were not included as possible chloramine DBPs unless they were present at significantly greater intensities in the chloraminated water (greater than two times the response in the corresponding source water or control). A representative chromatogram for the SDE analysis of a chloraminated water (midsouth water), along with its control (plant influent) and the chloraminated blank, is shown in Figure 9.9.

Bromide concentration was the parameter with the most direct impact on the type of DBPs formed in this limited test matrix (other parameters were not studied as in Task 1). Bromide levels ranged from less than 0.01 mg/L in the Pacific Northwest water to 1.5 mg/L in the midsouth water, greater than two orders of magnitude difference. The effect of source-water

226

Table 9.7 Results of SDE GC-MS analyses for DBFs

Possible DBFs*

NH2C1SDE

Blank

CSPW(Mills

Effluent)5/10/95

PacificCSPW Northwest Midsouth LHWRun 1 Dist. Syst. Dist. Syst. Run 4A

9/28/94 5/30/95 5/15/95 3/13/95

LHWRun 1

10/15/94

LAWRun 3

1 1/14/94Dihalomethams:

DibromomethaneBromoiodomethaneDiiodomethane

XXX

Trihalomethanes:Chloroform! XBromodichloromethaneDibromochloromethaneDichloroiodomethaneBromoformBromochloroiodomethaneDibromoiodomethaneChlorodiiodomethanelodoform (triiodomethane)

XXXXXXX

X XX XXX

XXX

XXXXXXXXX

XXXX

XXXX

X

XXXX

XXX

Halonitriles and Other Nitriles:

ChloroacetonitrileDichloroacetonitrileBromochloroacetonitrileBenzonitrilePhenylacetonirrile

XX X

XX

XXX

Other Nitrogen-Containing CompoundsChloropicrin

Halo-Oxy Compounds:Chloroacetic acid + vinyl

chlorideDichloropropanone X

Other Halo Compounds:1,1,1 -TrichloroethaneCarbon tetrachloride1,1,1,2-Tetrachloro-2,2-difluoroethane1,1,2-TrichloroethaneTetrachloroetheneTrichloropropene

227

(continues)


CSPWNH2C1 (Mills SDE Effluent)

PacificCSPW Northwest Midsouth LHW Run 1 Dist. Syst. Dist. Syst. Run 4A

LHW LAW Run 1 Run 3

Possible DBPs* Blank 5/10/95 9/28/94 5/30/95 5/15/95 3/13/95 10/15/94 11/14/94Other Halo Compounds (cont.)

Hexachlorohexadiene X XHexachlorocyclopentadieneBi-(hexachloropentadiene) X XUnknown (halogenated) X

Other Oxy-Compounds:Ethyl acetateMethylbutanal2,3-Dihydro-4-methyl furanToluenef X XXMethylcyclopentanone X4-Hydroxy-4-methoxy- X X

pentanonef

XX

XXXX

XX X

Methylcyclopentene-1-one XBenzaldehydef X X X XPhenolf XX X

X X X XX X

n-Nonanal X

Other Compounds :%Unknown XDimethylheptaneXylene X XXylene (different isomer) XUnknowns (hydrocarbon) XUnknown X X

XXX X

XX

X

Esters:Phosphoric acid, trioctyl ester X(Methyl phenyl) ethylhexylester X

propionic acidHexanedioic acid, dioctyl ester X

Dist. Syst. = Distribution System"These compounds—denoted by an "X"— were found in the samples at more than twice the concentrations found in

the blanks and controls and, thus, may represent DBPs of the disinfection scenario employed. tAlso detected in the blank or control at lower levels. $"Unknown" denotes the presence of a potential DBP compound; however, the identification was not obtained at the

time of this report. Chemical functionality present in the unknown compound is specified inside parentheseswhenever possible.

228

90-^80-£70-

1 60-| 50-

§ *l\ 40 -+32 30-= 20-

10-o-

(A) Midsouth distribution system sample R-M^™-.-"*.

Surrogate1 2057

J I.S., 1325

JU_« « Jl ^ A* I*. ,,>__

Surrogate2236

J200 400 600 800 1000 1200 1400 1600 1800 2000 2200

Scan Number100" 90"

1 60".g .

4) An ~ 5 40*s" 30K 20'

10"

01

(B) Midsouth plant influent sample

Surrogate Surrogate, 2237

2061I.S.

1328 J

U ..... 1 ... . L ....... L.jujuJhuM

\KW

200 400 600 800 1000 1200 1400 1600 1800 2000 2200Scan Number

100 90

-7- 80

S" ^i 60 -1 50§ 40« 30

* 2010"

0^ ,

200

'(C) Chloraminated blank sample "^o&f &

I.S.I ^330l>

I 1.flu J A J . J III . . 1.. •

Surrogate2237

. L wJ400 600 800 1000 1200 1400 1600 1800 2000 2200

Scan Number

Figure 9.9 GC-MS chromatograms of SDE analyses of (A) midsouth distribution system water, (B) midsouth plant influent, and (C) chloraminated blank

229

bromide (and iodide) content on THM speciation in the seven SDE samples is shown in Table 9.8 and is an extension of reported bromide effects on the four bromo-, chloro-, and mixed bromochloro-THMs (Symons et al. 1993). The waters are listed from left to right in order of increasing bromide concentration of the source water in Table 9.8. The low-bromide Pacific Northwest sample contained only chloroform and bromodichloromethane, whereas the bromo- and iodo- species predominated in the high bromide midsouth sample including the fully iodinated THM iodoform. SDE recoveries of-68 percent for diiodomethane and -56 percent for iodoform have been reported (Bruchet et al. 1995). Five of the nine chloro-, bromo-, and iodo- THMs found contained iodine; and at least one iodo-THM was found in all samples except the Pacific Northwest sample, indicating the presence of iodide in most of the samples.

The bromide in source waters typically comes from seawater—either recent intrusion or from ancient (connate) seawater—which in current geologic time contains about 67 mg/L bromide and 0.060 mg/L iodide (Spotte 1979). (Industrial and oil field brines are another source of bromide.) In times of drought and high seawater intrusion, CSPW at the Mills plant has had bromide levels as high as 0.5 mg/L and, thus, most likely an iodide concentration of 0.005 mg/L. In this study, a number of iodinated DBFs that may cause a medicinal taste and odor were identified. For iodoform the odor threshold level is 20 ng/L (Bruchet et al. 1989) and the taste threshold concentration is 5 |ig/L (Hansson et al. 1987). Previous research has shown that iodine incorporation during chloramination is different than that observed for bromide incorporation during chlorination (Hansson et al. 1987). The SDE data also show that the sum of the four bromo-, chloro-, and mixed bromochloro-THMs does not always equal the true total THMs.

In addition to the THMs, the SDE method recovered other halogenated organic compounds. The dihalomethanes dibromomethane, bromoiodomethane and diiodomethane were found in the midsouth water sample. The historical data for this utility (Table 8.3) showed the

presence of dibromomethane (up to 15 ng/L) and bromochloromethane (up to 3 |ig/L), but the

two iodinated compounds were not analyzed for. Carbon tetrachloride was detected in the Pacific Northwest water and LAW, but additional research is required to assess the significance (or lack of) for this compound. A number of other chlorinated alkanes were detected in both

230

Table 9.8 Effect of bromide (and iodide) on THM speciation

Parameter

Sample

Pacific LHW LHW CSPWNorthwest Run 4A Run 1 (MillsDist. Syst. 3/13/95 10/15/94 Effluent)

5/30/95 5/10/94

CSPW LAW MidsouthRun 1 Run 3 Dist. Syst.

9/28/94 11/14/94 5/15/95

Bromide (mg/L) 0.01 0.05 0.05 0.13 0.23 0.30 1.5

Trihalomethanes

Chloroform + + +

Bromodichloromethane + + +

Dibromochloromethane + +

Dichloroiodomethane + +

Bromochloriodomethane +Chlorodiiodomethane -

Dibromoiodomethane -

Bromoform -

Triiodomethane -

Dist. Syst. = Distribution System

+ = found

- = not found

+ + +

+ + + +

+ + + +

+ + + +

+ + + +

4- + + +

+ + + +

+ +

+

source and chloraminated waters and were therefore not considered DBFs. A group of four- and six-chlorine, cyclic and noncyclic, five- and six- carbon dienes were found in the Mills plant

effluent.Organic compounds containing different nitrogen-containing functional groups were also

recovered by SDE. These included the nitro compound chloropicrin, nitriles ranging from

231

chloroacetonitrile to benzonitrile, and the amide N,N-dibutylformamide. Dichloroacetonitrile has been found to be produced during chloramination (Young et al. 1995). The amide in this case was not a DBF (present in raw and treated waters), but its presence showed that this type of compound is recoverable by SDE. Phenylacetonitrile can be formed by the chlorination of the amino acid phenylalanine (Conyers and Scully 1993) and was only detected in the prechlorinated Mills plant effluent.

Oxygenated organic compounds such as aldehydes and ketones are common ozone DBFs (Weinberg et al. 1993). Small amounts of n-nonanal, benzaldehyde, methybutanal, and ethyl acetate, however, were detected in chloraminated waters that were not ozonated. The aldehydes may be DBFs from the reaction of chlorine or chloramines with amino acids (Bruchet et al. 1992;Hrudeyetal. 1988).

In recent years, the SDE technique has mainly been used in drinking-water applications to study taste- and odor-causing compounds in raw water and in ozonated water (Mallevialle et al. 1985). It has not previously been employed in the study of chloramine DBFs. The SDE concentration procedure provided the sensitivity necessary for GC-MS identification of a wide class of compounds at ng/L to ug/L levels. The reaction of the chloramine residual with organic matter in the samples and with solvent components during the heated SDE, however, is of continuing concern.

A number of compounds found in the chloraminated waters (including the chloraminated blank) in this study were not reported as chloramine DBFs. Because this study was only qualitative, compounds that were found in both source and chloraminated waters were generally not reported. Halogenated six-carbon, cyclic compounds (such as chlorocyclohexene—scan #661, cyclohexane—#811, and dichlorocyclohexane isomers—#974 and #1317) were detected only in chloraminated waters (see Figure 9.9C), but they were not reported as chloramine DBFs. These compounds were suspected to be products of the reaction of chloramines with the cyclohexene preservative in the methylene chloride. In fact, the wide range in relative signal responses for the halogenated, six-carbon, cyclic compounds as a function of water sources suggested the presence of matrix or disinfectant residual effects. These results suggest that if halogenated, six-carbon, cyclic compounds are expected to be natural chloramine DBFs for a particular water, another solvent preservative in place of cyclohexene should be used.

232

Conclusions

The SDE technique combined with GC-MS was successfully adapted to detect low level

chloramine DBFs. This concentration procedure provided the sensitivity needed for GC-MS

identification of a wide class of by-products at ng/L to low ug/L levels that would be expected

from chloramination. These compounds constituted the low molecular weight, volatile and

semivolatile compounds that are within the range of applicability of conventional GC-MS

(probably through a molecular weight of 650 daltons). The SDE GC-MS method (1) was

applicable to study a variety of water qualities, including samples after different chloramination

treatments, as exhibited by Task 2 pilot-plant and Task 3 full-scale samples and (2) showed the

influence of source water quality on DBF formation, especially the effect of bromide and iodide.

UF DETERMINATION OF AMW DISTRIBUTIONS

Overview

The UF technique has been used to characterize natural organic matter (NOM) in source

and treated waters, focusing on the molecular size/weight distribution of the organic compounds.

UF is used to fractionate a water sample based on the matrix components' molecular sizes, which

are approximately equal to their molecular weights. (For the rest of this report, the term apparent

molecular weight (AMW) will refer to the unit of size separation achieved by UF.) Analysis of

the fractions obtained produces an AMW profile or fingerprint. The evaluation of the UF

technique was undertaken as a screening procedure to aid in the selection of analytical

techniques for identification of specific DBFs and to describe changes in the AMW caused by

chloramination. UF can also be used as a concentration and isolation technique for MS and other

analytical methods. DOX was used as a surrogate for halogenated DBFs. The fingerprints

obtained from source waters (based on the DOC distributions) were compared to the ones

obtained from the corresponding chloraminated waters. Comparisons between representative

waters from different origins or different treatment conditions or both were made. UF

fractionation was used to characterize the NOM, to monitor changes occurring during treatment,

233

and to attempt to relate these changes to the production of DOX, as well as identified DBFs. Moreover, chloraminated water was fractionated by UF in order to determine the AMW

distribution of the halogenated DBFs.

Analytical Methods

UF Fractionation

Membranes of different molecular weight cutoff (MWC) were used. For a particular

membrane with a predefined MWC, the water sample was fractionated, resulting in two separate fractions. The water that was collected after passing through the membrane (permeate) should contain compounds with lower molecular weight than the nominal MWC, and the water remaining in the reservoir (retentate) should contain compounds with higher molecular weight than the MWC used. In this study, a direct filtration (also called parallel filtration) procedure was used. It consisted of a group of discrete filtrations where a separate aliquot of the

unfractionated sample was passed through each of the membranes.

A stirred UF cell (Amicon Model 2000M, Beverly, Mass.) was used. The UF apparatus

included a 2,000 mL pressurized reservoir. The nitrogen pressure was maintained at 50 to 55 psi

(3.5 to 3.9 kg/cm2) during the whole experiment. The water in the unit was stirred at a constant

rate to reduce concentration polarization. Cellulose acetate (YC) and regenerated cellulose (YM) UF membranes were used. These membranes are considered to be hydrophilic. Four MWCs

were selected for this study: 10,000 (i.e., 10K) (membrane YM10), 3,000 (membrane YM3), 1,000 (membrane YM1), and 500 (i.e., 0.5K) (membrane YC05) daltons.

The unfractionated sample was first filtered through a 0.45 um membrane to remove

particulates and colloids and then was fed to the UF cell. The permeate and retentate were both collected for analysis so that the mass balance for the DOC, UV-254, and DOX concentrations

could be calculated. For an initial sample volume of one liter, the filtration was stopped after

800 mL of permeate (P) was collected. To avoid a dilution effect from the rinse water, the first

100 mL of the permeate was discarded. The 200 mL of retentate (R) remaining in the reservoir

was then collected and combined with an equal volume of deionized water that was used to rinse

234

the reservoir. The permeates and the retentates were analyzed for DOC, DOX and/or UV-254, and these results were used to calculate the mass balance and AMW distribution. The permeate concentrations for the individual fractions were normalized to the concentration of the unfractionated sample based on the mass balance (recovery) before calculation of the AMW distribution. A sample calculation is given in Appendix A. Selected permeates were also analyzed for targeted DBFs.

Surrogate Parameters

Surrogate parameters were used to determine the general characteristics of samples and to provide a means of comparison between samples. Surrogate parameters used in this study were DOC, UV-254, and DOX. These parameters are used as a measure of organic precursors in source water (i.e., DOC and UV-254) or as a measure of DBF formation in treated water (i.e., DOX).

TOC/DOC. TOC is a measure of the total organic carbon in the sample, whereas DOC is the fraction of the TOC that passes through a 0.45-um pore diameter filter. The DOC/TOC is frequently used as a surrogate parameter for DBF precursors (Owen et al. 1993). In this study, all water samples were filtered through 0.45-um pore diameter filters, so the measurements represent DOC values. A Dohrmann DC-180 organic carbon analyzer (Santa Clara, Calif.) was used in this study following the UV-persulfate oxidation standard method 5310C (Standard Methods; APHA et al. 1992).

UV-254. UV-254 provides a measure of the degree of unsaturation/aromaticity of the NOM in the water sample. A Perkin Elmer Lambda 5 UV/VIS spectrophotometer (Norwalk, Conn.) was used following the draft standard method 5910 (USEPA 1994a).

DOX. DOX provides a measure of the total amount of chlorinated, brominated, and iodinated organic compounds that are present in a water sample. A Mitsubishi MCI DOX-10 analyzer (Cosa Instrument Co., Norwood, N.J.) was used following the adsorption-pyrolysis- titrimetric steps (USEPA 1986).

SUVA. The specific UV absorbance (SUVA) was also used to interpret the data. SUVA is defined as UV-254 expressed as absorbance per meter (i.e., m" 1 ) (normally reported in cm" 1 ) divided by the DOC concentration in mg/L; thus, the unit is expressed as (m'^mg/L) or

235

L/(m-mg). Details and guidelines for the evaluation of SUVA can be found in Edzwald and Van

Benschoten (1990). Typically, SUVA at <3 m"V(mg/L) contains largely nonhumic material, whereas SUVA in the range of 4 to 5 m"'/(mg/L) contains mainly humic material.

DBFs

In addition to these general surrogate parameters, specific target DBFs were measured

(for selected samples): neutral-extractable DBFs, HAAs, CNC1 and CNBr (see Chapter 4 for HAA and CNX methods). The neutral-extractable DBFs include the THMs, haloacetonitriles

(HANs), chloropicrin, 1,1-dichloropropanone, and 1,1,1-trichloro-propanone, and they were

determined using a pentane liquid-liquid extraction GC-ECD method that is a modification of

USEPA method 501.2 (Koch et al. 1989).

Experimental Plan

Overview

The UF experimental plan consisted of three major parts: UF method development and validation, UF analysis of bench-scale disinfection scenario studies, and UF analysis of full-scale

studies of diverse waters that paralleled some of the work done in Tasks 1, 2, and 3 of this project. The bench-scale experiments included comparisons of chlorine and chloramination

disinfection, as well as a total of three diverse chloramination conditions. Table 9.9 presents a

complete list of the UF experiments performed.

Method Development, Validation, and QA/QC

Part of the study consisted of the development and optimization of the UF technique for DOX fractionation in chloraminated water, as well as confirmation of DOC and UV-254 fractionation. A series of quality assurance/quality control (QA/QC) experiments were done to

determine interference or contamination, reproducibility, and membrane rejection.

236

Table 9.9

List of UF experiments

Description Surrogate Parameters and DBF Analyses

OtherAnalyses

OPWOPW—SDS A*OPW—Chloraminest

Chlorine/Chloramine Bench-Scale Study CSPW— Chloraminest CSPW—Chlorine§

Chloramine Bench-Scale Study LHWLHW—SDS B** LHW—SDS A*

Pilot-Plant StudyLHW Effluent—run #4A LHW Filter Effluent—run #4A

(influent to chloramination)

Mills-Full-Scale Study CSPW Effluent CSPW Influent

Midsouth Water Effluent Influent

Pacific Northwest Water Effluent Influent

TOC, UVTOC, UV, TOX, THM, HAATOC, UV, TOX, THM, HAA SDE

TOC, UV, TOX, DBPJ, HAA, CNX TOC, UV, TOX, DBF, HAA, CNX

TOC, UVTOC, UV, TOX, DBP, HAATOC, UV, TOX, DBP, HAA

TOC, UV, TOX, DBP, HAA SDE TOC, UV SDE




OPW = organic-pure water.*SDS A = chloramination at pH 6, C12/N =5/1, and 48-hr residual = 4 mg/L. fChloramination at pH 8, C12/N = 5/1, and 48-hr residual = 2 mg/L. JDBP = neutral-extractable DBFs. §Chlorination at pH 8 and 48-hr residual = 2 mg/L.**SDS B = chloramination at pH 8, C12/N = 7/1, and 48-hr residual = 4 mg/L.

237

Method blanks. A laboratory reagent water, with and without chloramines and with and without dechloramination, was studied. First, 4 L of organic pure water (OPW) (Milli-Q UVplus, Waters Assoc., Milford, Mass.) was fractionated through the four membranes, and the resulting permeates and retentates were analyzed for DOC and UV-254. (OPW is a low DOC water with <0.2 mg/L DOC.) Second, 6 L of OPW was chloraminated using the following SDS conditions: pH 6, 5/1 Cla/N weight ratio, and nominal 4 mg/L (actual 5 mg/L) total residual chlorine. These conditions were selected because they were the conditions used in the UF bench-scale experiments. After a 48-hour incubation time, the sample was dechloraminated with 1.2 mL of 5 percent sodium sulfite solution and UF fractionated. Each UF fraction was then analyzed for DOC, UV-254, DOX, THMs and HAAs. The third blank was OPW that was SDS chloraminated (pH 8, 5/1 Ch/N, and 2 mg/L total chlorine residual) but not dechloraminated before UF to parallel the UF full-scale studies.

Reproducibility. To evaluate the reproducibility of the entire UF process, three UF experiments were performed in duplicate: CSPW source water, chloraminated water, and chlorinated water. The CSPW was chloraminated at a 5/1 Cb/N weight ratio. Both the chloramination and chlorination were performed at pH 8 and were dosed to achieve total chlorine and free chlorine residuals of approximately 2 mg/L at the end of 48 hours. The permeates and retentates from the duplicate runs of the source, chloraminated and chlorinated waters were analyzed for DOC and UV-254, resulting in six pairs of DOC and six pairs of UV-254 measurements for each membrane. The permeates and retentates from the duplicate runs of the chloraminated and chlorinated waters were also analyzed for DOX. To evaluate the precision of the DOX measurements on UF-fractionated samples as well as to evaluate the reproducibility of the UF method, the permeates from the duplicate chloraminated water UF runs were sampled twice for DOX analysis. This produced a total of eight pairs (i.e., two UF runs for four membranes each).

Evaluation of membrane rejection. As mentioned above, a permeate sample was collected and aliquots were taken for the various analyses. This approach does not take into consideration membrane rejection of compounds with a lower molecular weight than the MWC (i.e., the non-ideality of UF). Determination of the coefficient of permeation (or correction factor) for each individual membrane used makes possible a more accurate determination of the

238

permeate concentration. For the Mills plant (CSPW) influent and effluent samples, a model developed by Logan and Jiang (1990) was used to determine the permeation coefficients for the surrogate parameters evaluated in this study (DOC, DOX, and UV-254). During the Mills plant testing, the 800 mL of permeate was collected as a series of successive 200 mL fractions, and the TOC, UV and DOX were measured for each individual fraction. Results were processed using the mathematical model developed by Logan and Jiang (1990). The permeation coefficient (p) is equal to one plus the slope of a linear plot of In Cp versus In F, where F is the fractional reduction in retentate volume at time t and Cp is the measured permeate concentration at time t.

To further evaluate the membrane rejection, LHW was fractionated and 500 mL of permeate was refiltered through the same membrane, thus producing a second permeate of 300 mL and a second retentate of 200 mL. Permeate and retentate from the first fractionation, as well as permeate and retentate from the second fractionation, were analyzed for DOC and UV-254.

Applications of UF Fractionation

Comparison of disinfection scenarios. Many utilities have switched from chlorine to chloramines as an alternative disinfectant totally or at least within the distribution system in order to reduce DBF formation. To look at the effect such a change might have on AMW distribution of the halogenated DBFs (e.g., DOX), CSPW was chloraminated and chlorinated under SDS conditions. A 40-L batch sample of CSPW source water was collected so that all three experiments could be compared. These samples were also used in the reproducibility study discussed above. Ten liters of the sample was chloraminated and another ten liters was chlorinated using the SDS conditions given in the reproducibility study (see above). In addition to DOX measurements, unfractionated chlorinated and chloraminated samples and permeates from the 0.5K dalton membranes were analyzed for neutral-extractable DBFs, HAAs, and CNXs as these specific DBFs all have molecular weights below 500 daltons.

The objective of this experiment was to compare the effect of two different disinfection scenarios (chloramination versus chlorination) on the production of DOX (and by inference halogenated DBFs) and on the molecular weight distribution of the organic matrix. All data presented for these three sets of experiments were based on averages obtained from the duplicate

239

runs or, in the case of the DOX formed during chloramination, on averages of four values (duplicate DOX analyses of duplicate UF runs). As mentioned in the methods section, the results were also normalized based on mass balance before calculation of the AMW distribution.

The next disinfection scenario study focused on the organic matrix changes on LHW for two very different chloramination conditions. The conditions were selected because they produced the highest amounts of DOX in the Task la LHW batch studies. Enough LHW for the three UF experiments was collected on January 26, 1995. This sample was submitted to a complete set of experiments that included:

1. UF fractionation of the source water2. Chloramination of the sample using two different SDS conditions:

Parameter Condition A Condition B

pH 68Cla/N weight ratio 5/1 7/1Total C12 Residual(mg/L) 4 4

In each case, the source water sample and the fractions were analyzed for DOC and UV- 254, and the chloraminated samples were analyzed for DOC, UV-254, and DOX. In addition, neutral-extractable DBF and HAA analyses were performed on the chloraminated samples before fractionation and on the <0.5K dalton fractions (permeate and retentate).

Study of geographically diverse waters. Chloraminated samples and non-chloraminated controls from four diverse waters were fractionated by UF and evaluated for DOC, UV-254, DOX, neutral-extractable DBFs, and HAAs. In addition, the samples were analyzed by SDE GC-MS, as discussed earlier in this chapter. Samples were shipped by next day air freight and kept refrigerated until the time of analysis.

The LHW was evaluated at pilot-scale operating under conditions described for Task 2, LHW run 4A (Table 7.15), which represented enhanced coagulation and postchloramination treatment conditions being considered for the proposed Disinfectants/DBF Rule. A set of filter

240

effluent samples before and after chloramination was collected on March 13, 1995, with coagulated/settled water acting as the control sample.

CSPW as currently treated in a full-scale plant (i.e., Mills plant) to meet current regulations was sampled. The water was treated with prechlorination, ferric chloride coagulation (to remove turbidity and not DOC), dual media filtration, and postammoniation. Plant influent and effluent samples were collected for UF.

A source water sample and a distribution sample from the Pacific Northwest water system described in Chapter 8 were collected and shipped on May 30, 1995. They were collected at the same locations as the waters reported in Task 3, Table 8.12 but were sampled 14 days later.

The midsouth location with a high bromide level studied in Task 3, Chapter 8, was also studied by UF. The plant influent and distribution system (representing a 48-hour detention time after chloramination) were sampled on May 15, 1995, concurrently with the Task 3 samples. Table 8.2 describes this.

Method Development

Method Blank Study

For the three types of blanks (OPW, chloraminated OPW, and chloraminated OPW which was dechloraminated), analyses of the fractions obtained by UF fractionation indicated that there was no significant (<0.2 mg/L) contribution of TOC from the membranes or the equipment. All DOC, UV-254, DOX, and THM results were near or below the detection limits of the methods. This confirmed that no contamination or possible reaction of chloramines with the membranes to form THMs or DBFs as measured by surrogate parameters was occurring. Thus, no interferences from the equipment or the membranes created a problem for the study.

Reproducibility

The results obtained from the duplicate runs of chloraminated and chlorinated CSPW were compiled in order to determine the reproducibility between UF runs for the DOC, UV-254,

241

and DOX analyses. The percent average deviation for the UV-254 analyses ranged from 0 to 18 percent, with the smallest deviation for the 3,000 and 10,000 dalton membranes (0 to 1.9 percent), followed by the 0.5K dalton membrane (0 to 4 percent). The 1,000 dalton membrane had the highest deviation for the UV-254 measurements. In terms of DOC, the UF reproducibility paralleled the UV-254 reproducibility, with the best reproducibility for the 10,000 dalton membrane (0.75 to 1.9 percent) and the highest deviation for the 1,000 dalton membrane (10 percent). The 1,000 dalton membrane demonstrated an erratic behavior throughout the study and was changed more frequently than the other membranes. No explanation could be found as that membrane was made from the same material as the 3,000 and 10,000 dalton membranes. Determination of the role of the water matrix on this loss of integrity was not investigated. The reproducibility of the UF fractionation in terms of DOX measurements ranged from 3.3 to 13 percent.

In addition, because duplicate DOX analyses were performed on the duplicate runs of the chloraminated sample, it was possible to determine the reproducibility of the DOX analyses. For all membranes within the same run, the DOX analysis precision was determined to be between 0.34 percent and 9.5 percent average deviation, with a mean and standard deviation of 3.1 percent ± 0.03 percent for n = 10.

Membrane Rejection

The permeation coefficients, which are a measure of the membrane rejection of compounds below the MWC of the membrane, were obtained for CSPW using Mills plant influent and effluent samples. Table 9.10 shows that the 0.5K membrane generally had the highest permeation coefficient of all the membranes (where 1.0 corresponds to 100 percent permeation). This could be due to the slight differences in the manufacturing process of the 0.5K membrane (YC) and the remaining membranes (YM). The IK membrane coefficients of permeation for the source water (DOC and UV-254) and treated water DOX were the lowest values (-0.4). The coefficients as measured by DOX, except for the IK membrane, were similar to those from DOC and UV-254 measurements. For CSPW, the membrane rejection was always higher for the raw water than the treated water as measured by DOC and UV-254. The

242

Table 9.10 Summary of coefficients of permeation

Membrane Influent Effluent

UV-254 DOC UV-254 DOC DOX

0.5K 0.703 NR 0.923 0.911 0.915

IK 0.434 0.410 0.817 0.912 0.465

3K 0.661 0.650 0.870 0.860 0.782

10K 0.645 0.708 0.751 0.818 0.979

NR = not reported

permeation coefficients observed for CSPW for UV-254 and DOC are in the range of those reported by Owen et al. (1993) for Ohio River water and Salt River Project water and provide a general indication of membrane retention. Permeation coefficients reported here, however, were not used in the calculation of AMW distributions, and coefficients were not determined for the other waters evaluated. The UF procedure as used in this study (i.e., collecting permeate fractions of 800 niL) generated "apparent" MW distributions that were used for relative comparisons and to elicit broad trends.

Results for the LHW refiltration study (Table 9.11) indicated that some compounds of O.5K daltons appeared to pass through the 0.5K dalton membrane during the first filtration but, that they were retained during the second filtration. The same phenomenon seemed to occur for the 1,000 dalton membrane. This did not appear to be the case for the larger MWC membranes (3,000 and 10,000 daltons). As discussed above, the degree of rejection can be determined by

243

the permeation coefficient. Aiken (1984) reported that the reliability of the UF fractionation does not exceed 90 percent. Because the general trends rather than the true values were needed for this study, this reliability was considered acceptable for the study.

For the rest of the discussion, the results from the IK dalton membrane are not reported. As mentioned earlier, the results from this MWC membrane were erratic and the permeation coefficients low. The fractions reported in this study are less than 0.5K, 0.5K to 3K, 3K to 10 K and>10Kdaltons.

Table 9.11 Refiltration experiment—LHW

Fraction (MWC)

Whole sample

500 P-l500 R-l

1,000 P-l

1,000 R-l

3,000 P-l

3, 000 R-l

10,000 P-l

10,000 R-l

DOC Initial Mass Balance Fraction DOC Mass Mass Filtration (mg/L) (MWC) Refiltration Balance * Balance (mg/L) (mg/L) (mg/L) Recovery

(%)t6.86

1.01 4.11

11.35

1.14 6.98

20.59

3.00 4.41

7.70

3.60 4.32

6.00

500 P-2500 R-2

1,000 P-2

1,000 R-2

3,000 P-2

3,000 R-2

10,000 P-2

10,000 R-2

0.64 0.970 98.61.47

0.65 1.37 125.4

2.47

2.45 2.92 98.3

3.62

3.64 3.62 100.6

3.60

Permeate Recovery

(%tt

63.1

56.9

81.7

101.0

*Mass balance of second filtration.

fMass balance recovery of DOC from initial filtration for each membrane.

^Recovery of DOC in second filtration from initial filtration for each membrane.

244


Overview

The general results of DOC, UV-254, and DOX UF distributions are given in this

chapter, whereas data for the whole and individual fractions of all samples are summarized in

Appendix A. The DOC, SUVA, and DOX, as well as the percentage of DOX accounted for by

target DBFs in the whole sample and in the < 0.5K dalton fraction, are given in Table 9.12. The waters covered a DOC range from 0.8 to 11 mg/L and DOX levels from 65 to 846 ug/L. The

waters studied had a SUVA ranging from a low of 1.5 L/(m-mg) for the midsouth water to a high

of 4.2 L/(m-mg) for the Pacific Northwest water. The Pacific Northwest water received

disinfection only (this is an unfiltered surface water); thus there was no coagulant addition that

would be able to remove humic substances that contributed to the SUVA value. In tests with

free chlorine only or prechlorination, the yield of DOX per unit DOC was 108 to 253 ng/mg;

whereas when only chloramines were used, DOX per DOC was 20 to 76 ug/mg.

Comparison of Disinfection Scenarios

The DOX of the chlorinated CSPW was 846 ug/L, whereas that of the chloraminated CSPW was 188 ug/L. DOC and UV-254 for the unfractionated sample and AMW profiles did

not change very much with disinfection addition (Figures 9.10 to 9.12). The DOX profiles (see

Figures 9.11 and 9.12) resulting from chlorination and chloramination were similar in this

particular case. Although chlorination produced significantly more DOX than chloramination,

the AMW distribution of the DOX was not significantly different. In both disinfection scenarios,

there was a high percentage of DOX in the <0.5K dalton fraction, whereas this fraction contained

a low percentage of DOC. Only a small percentage of the DOC was halogenated even with free

chlorine, so the different AMW distributions of the DOC and DOX were not in conflict. A high percentage of the DOX was low molecular weight, which has been better identified for the

245

to -c*.

Tabl

e 9.

12

Sum

mar

y of

DOC

, SUV

A, D

OX, a

nd D

OX

per

cent

age

valu

es fo

r ben

ch-,

pilo

t-, a

nd fu

ll-sc

ale

tests

Influ

ent*

Sam

ple

Benc

h-Sc

ale

Expe

rimen

ts:CS

PW—

Chlo

ram

ine

6/21

/95

CSPW

— Ch

lorin

e 6/

21/9

5LH

W S

DS A

LHW

SDS

B

Pilo

t- an

d Fu

ll-Sc

ale

Plan

ts:LH

WM

idso

uth

Wat

erPa

cific

Nor

thw

est W

ater§

CSPW

--4/2

4/95

§

DOC

(mg/

L)

4.06

4.06 11.0

11.0

3.13

3.27 0.81

3.37

SUV

A

DO

C (L

/(m-m

g)

(mg/

L)

2.55 2.55 NA

NA

1.85

1.52

4.22 3.53

3.40

. 3.

35 11.0

11.1

3.27

2.97 0.88

3.00

DO

X(u

g/L)

188

846

512

840

64.7

120

145

325

DOX/

DOC

(ug/

mg)

55.3

253

46.5

75.5

19.8

40.4

165

108

Efflu

ent

TDBP

OX

/ D

OX

t (%

)

5 17 9 6 21 20 10 22

DO

X in

0.

5K

Frac

tion

(%)

42 48 25 44 61 51 27 35

TDBP

OX

/0.5

K

DO

XJ

(%)

12 35 37 13 35 39 38 63

NA

= n

ot a

vaila

ble

* Inf

luen

t or c

ontro

l sam

ple

colle

cted

bef

ore

chlo

ram

inat

ion.

tOrg

anic

hal

ide

iden

tifie

d D

BFs (

neut

ral-e

xtra

ctab

le D

BF, H

AAs,

CNX

)/DO

X o

f unf

ract

iona

ted

sam

ple

(on

a mol

ar b

asis)

.^O

rgan

ic h

alid

e id

entif

ied

DBF

s (ne

utra

l-ext

ract

able

DBF

, HAA

s, CN

X)/D

OX

of 0

.5K

frac

tion

(on

a mol

ar b

asis)

.§P

rech

lorin

ated

/pos

tchl

oram

inat

ed.

<0.5K 0.5- 3 K 3-10K Apparent Molecular Weight Range (daltons)

>10K

Figure 9.10 AMW distribution of DOC and UV-254 for source water—CSPW (June 1995)

chlorinated sample than the chloraminated one. Even though the AMW distributions of

the chlorinated and chloraminated DBFs were the same, their polarity and other characteristics were probably different.

The AMW profile of DOX produced by chloramination can be strongly influenced by the specific chloramination conditions. Task la batch treatment of LHW that was run approximately a year earlier than the UF work generated DOX levels from 25 to 277 (ag/L. In the comparison of two chloramination conditions, condition A (pH 6, 5/1 Cb/N weight ratio) and condition B (pH 8, 7/1 Cfe/N weight ratio), LHW displayed very different responses. The AMW profiles for

the LHW under conditions A and B are given in Figures 9.13 and 9.14. DOX levels of 512 and

840 |ag/L were produced by condition A and B, respectively. Condition A, at pH = 6, had a high concentration of dichloramine (2.8 mg/L) and a lower monochloramine level (1.1 mg/L).

Condition B was between the maximum and the breakpoint on the breakpoint curve and had a

247

<500 500-3,000 3,000-10,000 >10,000 Apparent Molecular Weight Range (daltons)

Figure 9.11 AMW distribution of DOC, UV, and DOX for chlorinated CSPW (June 1995)

<500 500-3,000 3,000-10,000 >10,000 Apparent Molecular Weight Range (daltons)

Figure 9.12 AMW distribution of DOC, UV, and DOX for chloraminated CSPW (June 1995)

248

DOC-Source

DOC-SDS A

DOX-SDS A

<500 500 - 3,000 3,000 - 10,000 >10,000 Apparent Molecular Weight Range (daltons)

Figure 9.13 AMW distribution of source water DOC and of DOC and DOX of chloraminated LHW, SDS condition A (pH - 6, C12/N = 5/1, with 48-hr residual of 4 mg/L)

DOC-Source

DOC-SDS A

DOX-SDS A

500 - 3,000 3,000 -10,000 >10,000 Apparent Molecular Weight Range (daltons)

Figure 9.14 AMW distribution of source water DOC and of DOC and DOX of chloraminated LHW, SDS condition B (pH = 8, C12/N = 7/1, with 48-hr residual of 4 mg/L)

249

concentration of 3.8 mg/L monochloramine and no dichloramine; it produced a very high DOX level. The percent DOX in the <0.5K fraction was also high (44 percent) (Figure 9.14). Compounds in this low molecular weight range should be amenable to GC-MS analytical techniques unless they are too polar. Because only a small percentage of the DOX was accounted for by target DBFs, condition B may have produced more polar, low molecular weight DBFs. Condition A was at the maximum of the breakpoint curve, but at a pH producing a chloramine mixture of mono- and dichloramine, 1.1 and 2.80 mg/L, respectively, in this sample. Under these conditions, less DOX was formed and only 25 percent was in the <0.5K fraction (the DOX was more evenly distributed among the AMW fractions). Under these conditions, the humic (large molecular weight) substances were probably halogenated but were not broken down to relatively low molecular weight DBFs (e.g., as free chlorine does). Thus, techniques that can analyze for high molecular weight DBFs (e.g., LC-MS) are needed for such a sample. These results point out that DOX formation and AMW distribution of the halogenated DBFs can be strongly influenced by specific disinfection conditions.

Study of Geographically Diverse Waters

The data in Figure 9.15 show that the four diverse waters gave very different DOC profiles, even though three of the four waters had very similar DOC concentrations. Most of the DOC from the Pacific Northwest water (DOC = 0.81 mg/L)—which came from a facility that did not coagulate the water—had a molecular weight >10K daltons whereas all of the DOC from LHW after enhanced coagulation—a process that is efficient at removing humic substances— was <10K daltons. These AMW distributions are also consistent with the SUVA values of these waters. The distribution of DOC, however, did not change greatly after chloramination for any of these waters (Figure 9.16).

The DOX concentrations for the unfractionated samples used for UF were a low of 65 ug/L for the enhanced coagulation treated LHW, moderate values for the midsouth water (120 Hg/L) and the Pacific Northwest water (145 ug/L), and a high of 325 ng/L for full-scale treated CSPW (which was prechlorinated). As indicated by the low overall DOX for the LHW, enhanced coagulation removed many of the DBF precursors (Figure 9.17). The DOX yield per unit DOC was lower than previously observed for chloraminated raw LHW (see Table 9.12).

250

LH-Pilot Plant, DOC = 3.13 mg/L

Midsouth, Pacific Northwest, DOC = 3.27 mg/L DOC = 0.806 mg/L

Source Waters

CSPW,April 1995,

DOC = 3.22 mg/L

Figure 9.15 Comparison of AMW distribution of DOC for four source waters

LH-Pilot Plant, Midsouth, Pacific Northwest, DOC = 3.27 mg/L DOC = 2.97 mg/L DOC = 0.88 mg/L

Treated Waters

CSPW,April 1995,

DOC = 3.0 mg/L

Figure 9.16 Comparison of AMW distribution of DOC for four chloraminated waters

251

<0.5K 0.5K-3K 3K-10K Apparent Molecular Weight Range (daltons)

>10K

Figure 9.17 AMW distribution of DOC, UV, and DOX for LHW pilot plant effluent (enhanced coagulation)

The majority of the DOX (61 percent) was in the <0.5K dalton fraction, and a relatively high amount of the DOX was accounted for by target DBF analyses (24 percent). For the Pacific Northwest water, a large fraction of the DOC was in the >10K dalton range (Figures 9.15 and 9.16) and the DOC AMW distribution did not change much with disinfection. Forty-four percent of the DOX had an AMW greater than 10K daltons, and this water demonstrated that halogenated DBFs can have a very high molecular weight. Only 13 percent of the DOX could be accounted for by the target DBFs, as much of the DOX was probably not amenable to GC analyses. The UV-254 and DOX levels were much greater in the >10K fraction than in the other fractions for the Pacific Northwest water (Figure 9.18). These results show the need for an analytical method like LC-ESI-MS to identify high molecular weight DBFs.

The midsouth water had a moderate DOX production, which might have been higher due to the high bromide level (1.5 mg/L) but was consistent with the relatively low SUVA (1.5 L/(nvmg) of the source water. Approximately 50 percent of the DOX was in the <0.5K dalton fraction (Figure 9.19). Twenty-four percent of the DOX was accounted for by the selected DBFs

252

<0.5K 0.5K-3K 3K-10K >10K Apparent Molecular Weight Range (daltons)

Figure 9.18 AMW distribution of DOC, UV, and DOX for chloraminated water from Pacific

Northwest

<0.5K 0.5K-3K 3K-10K Apparent Molecular Weight Range (daltons)

>10K

Figure 9.19 AMW distribution of DOC, UV, and DOX for chloraminated water from the

midsouth

253

analyzed for, and another large fraction of DBFs was identified by SDK GC-MS, as reported earlier in this chapter. The remainder of the DOX was distributed among the other fractions, with 31 percent of the DOX in the 0.5K to 3K dalton range.

The full-scale, prechlorinated/postchloraminated CSPW results are shown in Figure 9.20. As with the chlorinated and chloraminated bench-scale tests of CSPW (Figures 9.11 and 9.12), a moderate amount of the DOX was low molecular weight. In either case where free chlorine was used (alone or as predisinfectant), 21 to 26 percent of the DOX was accounted for by target DBF analyses, whereas only 5 percent of the DOX was accounted for in the chloraminated only CSPW (Table 9.12). Figure 9.21 shows how different the percentage of DOX is for each chloraminated water in each of the various fractions.

Conclusions

UF was used as an analytical tool for the characterization of the AMW distribution of chloramine DBF as measured by DOX. An understanding of the AMW distributions of the DOX and DOC after chloramination can direct further analyses for specific DBFs. The DOC profiles did not change dramatically upon chloramination. In addition, UF can serve as an isolation, desalting and concentration technique for specific analyses such as LC-MS (e.g., one can isolate a fraction with a high percentage of the DOX).

No matter which source was chloraminated, the percentage of DOX in the <0.5K dalton fraction was typically the highest (see Figure 9.21). Thus, a large percentage of halogenated compounds should be amenable to GC-MS techniques unless they are too polar.

As demonstrated by the variety of waters studied, DOX can be of any molecular weight, even greater than 10K daltons (for an uncoagulated water, this may even be a large part of the DOX). These results point to the need for analytical methods such as LC-ESI-MS that can detect high molecular weight compounds with the specificity of MS and MS-MS.

Chlorination produces more DOX than chloramination, but the AMW distributions of the chloramine DOX were not necessarily very different. The chloramine DOX profile was dependent upon the specific conditions of chloramination (i.e., pH, Cb/N ratio), as well as treatment plant operations (use of conventional or enhanced coagulation).

254

<0.5K 0.5K-3K 3K-10K >10 K Apparent Molecular Weight Range (daltons)

Figure 9.20 AMW distribution of DOC, UV, and DOX for prechlorinated/postchloraminated CSPW (April 1995)

Pacific NorthwestDOX=145M9/LMidsouth

= 120pg/L LHW-Pilot-Plant treated DOX = 64.7 M9/L CSPW, April 1995 DOX = 325 M9/L

<0.5K 0.5 K-3 K 3K-10K Apparent Molecular Weight Range (daltons)

>10K

Figure 9.21 AMW distribution of DOX for four chloraminated waters

255

SUMMARY AND CONCLUSIONS

Task 4 investigated several analytical approaches suitable for determining chloramine DBFs and used the various approaches to characterize halogenated DBFs in chloraminated waters. The analytical approaches evaluated were LC-KI-UV and LC-MS; SDE GC-MS; and UF (DOX AMW distribution).

The LC methods focused on polar by-products, particularly those formed from amines and ammo acids. LC with on-line enrichment was found to be suitable for separating polar N-chloro compounds. KI-UV detection was found to be an easy way to monitor compounds prior to using a more exact detector for identification. Analysis of a natural water appeared to indicate that monochloramine, not dichloramine, reacted with small peptides to yield a KI-UV detectable compound. Limited work with LC-ESI-MS demonstrated its potential for identification of chloramine DBFs, in particular for N-chloro compounds. The PB-MS system used, however, was not adequate for determination of the N-chloro compounds.

The SDE, coupled with high performance capillary GC-MS, allowed detection of volatile

and semivolatile chloramine DBFs at low concentrations (ng/L to ug/L). SDE GC-MS results showed the influence of source water quality on chloramine DBF formation, especially the effect of bromide and iodide.

UF was an analytical tool used for the characterization of the AMW distribution of chloramine DBFs as measured by DOX. Specific disinfection conditions were found to strongly influence the AMW distribution of the halogenated DBFs. Generally, the DOX from the chloramination of all source waters studied had a high percentage of low molecular weight (<0.5 K dalton) compounds.

A better understanding of the nature of the DBFs formed by chloramination of diverse waters was gained by application of the LC-KI-UV, LC-ESI-MS, SDE-GC-MS and UF techniques to the analysis of solutions of chloraminated model compounds and natural waters.

256

CHAPTER 10

CONCLUSIONS

Based on the data collected in this investigation, the following are the key findings in each task.

TASK la

• Total disinfectant residual concentration (monochloramine+dichloramine+free chlorine) after 48 hr of incubation had little influence on the concentration of disinfection by-products (DBFs) formed.

• DBF formation followed the general trend of decreasing with increasing pH and decreasing Cb/N ratio. Exceptions to the trend were noted in some instances at pH 8, where the complexity of haloamine chemistry may cause water-specific responses.

• Dichloramine was present after 48-hr simulated distribution system (SDS) tests only at pH 6, and its relative fraction of the total residual increased as the Cla/N ratio increased.

• The production of significant concentrations of DBFs at pH 6 is consistent with the premise that dichloramine, or a decomposition product (i.e., free chlorine), is the active halogenating agent.

• The production of significant concentrations of DBFs in some instances at pH 8 implicates a chemical other than dichloramine as the active halogenating agent. Most probably, acid catalyzed reactions with monochloramine were producing the DBFs. Such reactions would also be expected to occur at pH 6, but not to a very great extent at pH 10 because of the low proton concentration.

• At pH 6, the addition of bromide to the water decreased the dichloramine fraction and increased the total chlorine demand, both of which suggest the increased formation of free and combined bromine. Interestingly, Lake Houston Water (LHW) was the water least susceptible to changes in dichloramine fraction,

257

possibly because the low alkalinity (-70 mg CaCOa/L) decreased the rate ofdichloramine decomposition.For the specific DBFs measured [trihalomethanes (THMs), haloacetic acids(HAAs), cyanogen halide (CNX)], bromide addition increased the concentrationof bromine-substituted DBFs. The dissolved organic halogen (DOX) analysiscannot differentiate between chlorine and bromine-substituted DBFs; however,the increased production of DOX observed with bromide addition implies anincrease in the degree of halogen substitution during chloramination of bromideion-containing waters.In all three waters studied, the dihalogen-substituted species [dichloroacetic acid(DCAA), dibromoacetic acid (DBAA), bromochloroacetic acid (BCAA)] were thedominant HAAs. This suggests that the trihalogen-substituted [e.g.,trichloroacetic acid (TCAA)] and dihalogen-substituted (DXAA) species havedifferent precursor materials and that the use of chloramines preferentiallycontrols the production of some HAA species.Only THMs and HAAs face current or near-term future regulation. Littledifficulty should be expected in meeting expected THM regulations withchloramines. Some difficulty is possible in certain waters with HAAs because ofthe production of DXAA species.

The 12 specific DBFs measured in this task accounted for no more than 35% ofthe DOX concentration on a molar basis, usually much less; therefore, utilitiesmay want to consider both specific DBFs and DOX in selecting appropriatechloramination conditions.

Relatively high concentrations of 2-d SDS DOX were formed in some watersunder some conditions. The maximum concentration found in this task was 258Hg C17L in LHW at pH 6 and a C12/N ratio of 5/1, ambient bromide ionconcentration, 2 mg/L total chlorine residual.

DBF production is quite sensitive to both pH and the Ch/N ratio; therefore,utilities should test both these variables to find operating conditions that meetdisinfection needs while minimizing DBF production. Unfortunately, the 3/1Clz/N ratio, which produced the smallest DBF concentrations in this study, may

258

TASK Ib

not be compatible with the maintenance of acceptable microbial water quality in

some distribution systems because at this ratio, free ammonia may be present, and

this may stimulate the growth of nitrifying bacteria.

Taken as a whole, the experiments on the three water sources indicate that mixing

conditions do not significantly affect the DBF concentration and speciation based

on 48-hr simulated distribution system tests; rather, system chemistry is the

controlling factor.

Considering that the experimental conditions covered a broad range of mixing

intensities and included delayed addition of ammonia, and considering that the

objective was to simulate the impact of mixing at the point of disinfectant

addition on distribution system DBF concentrations, the mixing experiments

should provide a reasonable estimate of the relative impact of mixing on DBF

formation at full scale.

Generally, the THM concentrations varied within a factor of two across the range

of mixing conditions for a given chemistry condition. Therefore, utilities may

achieve some decrease in THM and DOX formation through improved mixing

and simultaneous addition of chlorine and ammonia.

Mixing conditions had no discernible impact on HAA or CNX production.

The 12 specific DBFs measured in this task accounted for no more than 32% of

the DOX concentration on a molar basis, usually much less; therefore, utilities

may want to consider both specific DBFs and DOX in selecting appropriate

chloramination conditions.

Relatively high concentrations of 2-d SDS DOX were formed in some waters

under some conditions. The maximum concentration found in this task was 320

ug C17L in LHW at pH 8, Cli/N ratio of 7/1, low mixing intensity, ambient

bromide ion concentration, 2 mg/L total chlorine residual.

259

TASK 2

The pilot plant data for the three primary water sources agreed fairly well with the Task 1 bench-scale experiments, thus indicating that bench-scale testing is a useful first step to evaluate chloramination DBFs quickly and economically.

The 2-day SDS THM concentrations in all the pilot plant effluents met the proposed Stage 1 MCL; the THM concentrations in the effluents from the pilot plants also met the proposed Stage 2 MCL, with the exception of two runs at extreme conditions (high bromide, low pH; delayed addition of ammonia). In Lake Austin Water (LAW), a higher incubation pH sometimes produced a larger 2-day SDS HAA6 concentration, while little dependence on pH occurred in LHW. Therefore, a water-specific dependence of HAA6 formation on pH may be observed.

Except for one run, the ratio of the total dihalogen-substituted haloacetic acid concentrations to the HAA6 concentration in the 2-day SDS samples was from 0.7 to 1.0 (mostly 1.0). This indicates that chloramination does not control the formation of this group of DBFs very well.

Where source water chloramination and postfilter chloramination were compared (LAW and LHW), the point of adding the chloramines in the treatment train had little influence on the resulting 2-day SDS DBF concentrations. Apparently these waters contained "slow-reacting" precursors.

Ozonation in LAW and California State Project Water (CSPW) altered the HAA6 precursor material so that significantly lower 2-day SDS HAA6 concentrations resulted. This finding is important because it provides an option for utilities that are not able to meet the proposed Stage 2 MCL through chloramination alone.

Lower incubation pH always produced more 2-day SDS CNX. Note that base- catalyzed hydrolysis destroys CNX at pH 10, so even if CNX were formed, it would not be present after 48 hours. Postchloramination sometimes produced more 2-day SDS CNX than prechloramination.

In LAW and LHW, a lower incubation pH always produced more 2-day SDS DOX. Variation of pH was not studied in CSPW in this task.

260

Ozonation, when practiced (LAW, CSPW), followed by chloramination decreased

2-day SDS DOX concentrations relative to chloramination alone.

In LAW, the 2-day SDS DOX concentrations were larger when operating in direct

filtration mode, in comparison to conventional lime softening. Perhaps more

organic matter was removed in lime softening, or perhaps the lower alkalinity

resulting from lime softening decreased the reaction rate for acid-catalyzed

reactions of monochloramine with background organics. The role of alkalinity in

DBF formation may be worth considering in waters with moderate to high

alkalinity.

The 12 specific DBFs measured in this task accounted for no more than 45.4% of


may want to consider both specific DBFs and DOX in selecting appropriate

chloramination conditions.



ug C17L in LHW with prechloramination, conventional coagulation, incubation

pH 6, Cb/N ratio of 3/1, 0.32 mg/L bromide ion added, 2 mg/L total chlorine

residual.

Overall, practicing conventional coagulation, adding well mixed chlorine and

ammonia solutions simultaneously in the appropriate ratio, and keeping the pH in

the distribution system (as represented by incubation pH in this study) as high as

possible after chloramination at as low a Cb/N ratio as possible should minimize

overall DBF formation. Where needed, preozonation before chloramine addition

should further decrease DBF formation.

261

TASK 3

• Although several of the geographically diverse water sources have more

complicated chemical matrices, the full-scale sampling and bench-scale testing of

these waters largely mirrored the findings in the three primary water sources, thus

providing added confidence that the results of this research can be generalized to

utilities across the country (Table 10.1).

• Confirmation of the following points is of particular note.

— As has also been shown elsewhere, low pH and high Cb/N ratios cause the production of dichloramine.

— Bromine-substituted DBFs can be formed during the chloramination of

waters containing high concentrations of bromide.

— Dihalogen-substituted HAAs are preferentially formed over TCAA in

chloraminated waters; DCAA will be the dominant HAA in the absence of

significant bromide concentrations.

— Some waters may have difficulty meeting the proposed Stage 2 MCL for HAAS (0.030 mg/L) using chloramines.

— As long as a significant period of free chlorination does not occur, THM production during chloramination should not be a problem.

— Thus, chloramination is more effective in controlling the production of

THMs and TCAA than the production of DCAA and its bromine-

substituted analogues (DXAA).

• The 12 specific DBFs measured in this task accounted for no more than 23.7% of


may want to consider both specific DBFs and DOX in selecting appropriate chloramination conditions.

262

Table 10.1

Summary of 2-d SDS disinfection by-product data

Lake AustinMedianMinimumMaximum

TTHM Hg/L

Amb.BrWater, Task

3.2ND15.2

TTHM Hg/L + Br

HAA6 Mg/L

Amb.Brla, Total chlorine residual =

8.5ND40.2

Lake Houston Water, Task la, TotalMedianMinimumMaximum

3.9ND17.7

4.7ND38.2

10.73.2

20.1

chlorine residual33.519.549.9

HAA6Hg/L + Br

2mg/L

N/A

= 2mg/L41.738.644.7

CNXHg/L

Amb.Br

4.9ND10.3

'5.4

1.116.9

CNXHg/L + Br

N/A

6.41.2

18.7

California State Project Water, Task la, Total chlorine residual = 2 mg/L Median 3.2 10.9 9.8 3.8 Minimum ND ND 4.9 N/A ND N/A Maximum 10.3 30.7 17.7 17.4

Midsouth Water, Task 3Minimum 9.8Maximum 37.0

Mississippi River Water, TaskMinimum 5.5Maximum 5.8

Biscayne Aquifer Water, TaskMinimum NDMaximum 0.8

N/A

3N/A

3N/A

9.0 N/A28.7

15.4 N/A19.9

9.9 N/A20.5

ND18.0

ND8.7

0.53.6

N/A

N/A

N/A

Northeastern Creek Water, Task 3Minimum 2.5Maximum 6.8

Northwest Water, Task 3Minimum NDMaximum ND

N/A

N/A

5.1 N/A18.0

8.0 N/A16.1

2.68.8

2.87.0

N/A

N/A

Note: All preformed chloramines applied to source waters

Amb. = Ambient N/A = Not applicable ND = None Detected

263

TASK 4



ug C17L in the midsouth water, at incubation pH 6, Cb/N ratio 5/1, 3.3 mg/L total chlorine residual. In the full-scale sampling, 431 ug C17L of DOX was found in

the prechlorinated/postchloraminated Biscayne Aquifer water.

Chloramination of small model peptides showed that monochloramine, not

dichloramine, reacted with these chemicals, providing further evidence of

monochloramine's role in DBF formation.

Although most of the compounds identified in this study have been reported by

others as chlorination by-products, the dihalomethanes found upon

chloramination of the midsouth water may be specific to chloramination.

In some chloraminated water, the <500 dalton ultrafiltration (UF) fraction

represented approximately 43 to 61 percent of the DOX.

In some of the other chloraminated waters, the two highest molecular weight

fractions (the 3K to 10K and >10K) together represented approximately 39 to 55

percent of the DOX. Thus, significant concentrations of halogen-substituted DBFs

with very high molecular weight also are possible.

Thus, UF provides a unique analytical tool to preliminarily ascertain which

molecular weight fraction is most significant for a site specific chloramination.

Simultaneous distillation extraction, gas chromatography-mass spectrometry

(SDE GC-MS) was applicable to a variety of water qualities and provided thesensitivity needed for GC-MS identification of by-products at the ng/L to low

fig/L levels expected from chloramination.

SDE GC-MS measures low molecular weight [<650 daltons, MS scanned from 45

to 650 daltons], volatile and semivolatile compounds of low and moderate

polarity.

264

The particle beam-electron impact (PB-EI) ionization MS system used in this

study was not suitable for determining the structure of N-chloro organic

compounds.

The electrospray ionization (ESI)-MS system is applicable to the liquid

chromatography (LC)-MS determination of polar N-chloro organic compounds

that are chloramination by-products.

This work provides guidelines for the study of chloramine by-products. For future

DBF work, UF is recommended for use to separate and concentrate fractions of

compounds that currently have not been identified.

An initial full-scan, low resolution LC-ESI-MS run can provide preliminary

halogen content and molecular weight information. Subsequent high resolution

MS and MS-MS runs could focus on peaks of interest to determine chemical

composition and structure for DBF identification.

265

CHAPTER 11 RECOMMENDATIONS TO WATER UTILITIES

The results of this study confirm that DBF formation during chloramination generally

does not pose a regulatory concern based on current drinking water regulations and probably will

not cause a concern with the proposed Stage 1 regulations. Some problems may arise in meeting

the proposed Stage 2 regulations for HAAs. Even though chloramines generally do not produce

concentrations of regulated chemicals that are of concern, formation of unregulated and

uncharacterized halogenated chemicals, as measured by the DOX analysis, is significant under

some conditions. Therefore, water utilities may want to consider concentrations of both specific

regulated chemicals and DOX in selecting operating conditions for chloramination.

Some decrease in DBF formation may be observed through improved mixing at the point

of chemical addition. Also, simultaneous addition of chlorine and ammonia, in comparison to

delayed addition of ammonia, should reduce DBF formation, especially formation of THMs. In

bench scale mixing tests, the decrease in DBF formation through improved mixing and

simultaneous chemical addition did not exceed 50 percent in 48-hr simulated distribution system

tests; therefore, this approach to DBF control is most applicable to situations where modest

decreases in DBF formation are sought. The possible benefits from this approach also are a

function of the quality of the mixing and chemical addition schemes in current use.

System chemistry affects DBF formation far more than mixing. In general, the formation

of DBFs decreases with increasing pH and decreasing Cb/N ratio. Therefore, manipulation of

these two major operating variables can significantly impact DBF formation. Unfortunately, the

general observations of the effect of pH and Cb/N ratio on DBF formation may not hold for all

waters near neutral pH (7 to 8.5), because of the complexity of haloamine chemistry over this pH

range. Therefore, bench scale testing like that performed in Task la of this research is

recommended as an initial step in investigating the impact of operating conditions on DBF

formation. Further investigation at pilot scale also may be warranted if substantial changes in

operating conditions are contemplated.As noted above, decreasing the Cla/N ratio, especially to low values such as 3/1,

decreases DBF formation. Unfortunately, some water utilities have experienced problems in

maintaining adequate microbiological quality in distribution systems at low C^/N ratios.

267

Growth of nitrifying bacteria is a particular problem. Therefore, minimizing DBF formation and maintaining acceptable microbiological water quality in the distribution system may conflict with one another. Possible adverse water quality impacts should be considered in conjunction with a decrease in the C12/N ratio to low levels.

In addition to pH and the Cla/N ratio, two other system chemistry parameters may be important in DBF formation: bromide and alkalinity. This research shows that, as the bromide concentration increases, DBF formation likewise increases and the speciation within the individual classes of DBFs (e.g., THMs) shifts toward the bromine substituted chemicals. Therefore, water utilities that experience cyclical changes .in the bromide concentration of their source water can expect a positive correlation between DBF formation and bromide concentration.

Monochloramine can react with organics via an acid-catalyzed mechanism to yield halogen substituted organics. This reaction mechanism is catalyzed by proton donors such as carbonic acid and bicarbonate, the latter of which is a component of alkalinity and a common constituent of natural waters. Thus, as alkalinity increases, the rate of DBF formation also may increase. Utilities that have significant alkalinity, especially those practicing or considering lime softening, may want to examine the effect of alkalinity removal on DBF formation. The effect of alkalinity on DBF formation was not formally part of this research; however, some very limited data from several pilot plant runs suggest that alkalinity may impact DBF formation.

Any strategy aimed at controlling DBF formation through modification of pH and the Cb/N ratio will have practical ranges of workable values that are specific to each situation. In some cases, the workable ranges may be inadequate to satisfactorily control DBF formation. In particular, significant concentrations of dihalogenated acetic acids can be formed during chloramination. Conceivably, the HAA concentration in some waters could exceed the proposed Stage II regulations. Under these circumstances, preozonation followed by chloramination should be considered. This research showed that ozonation prior to chloramination decreased the formation of both HAAs and DOX.

Specific DBFs (e.g., THMs, HAAs, CNX) may comprise a very small percentage of the DOX concentration. Under such circumstances, water utilities may want to investigate their water in more detail to identify additional chemicals. This research examined a number of new analytical approaches for identifying additional chloramination DBFs. Uitrafiltration (UF) using

268

DOX and TOC surrogates and liquid chromatography (LC) are methods that could be adopted by a research laboratory to provide general information about halogen-substituted DBFs. As with other MS investigations into the identification of chlorination DBFs, the ultimate goal is to develop analytical methods using more readily available instrumentation once unknown DBFs have been identified. The actual practice of this approach cannot be instituted, however, until more of the chloramine DBFs are identified and their health significance evaluated. This study has shown that an initial full-scan, low resolution LC-electrospray ionization (ESI)-mass spectrometry (MS) run can provide preliminary halogen content and molecular weight information. Subsequent, high resolution MS and MS-MS runs could then focus on peaks of interest to determine chemical composition and structure for DBF identification.

269

APPENDIX A

ULTRAFILTRATION CALCULATIONS AND DATA

The equations used to generate the ultrafiltration AMW distributions shown in Chapter 9

are given here along with sample calculations. The raw DOC, UV-254, and DOX data used in

the calculations are summarized in Tables A.2 through A.7 (second, fourth, and sixth columns),

and the calculated mass balances (MB) — in the same units as the raw data — are summarized in

the third, fifth, and seventh columns.

UF Calculations

Example: Table A.I shows the DOC calculation for the analysis of a UF fractionation of a water sample (three membranes are used in this example). Column 1 describes the fractions in

terms of the AMW cutoff for each of the three membranes (3 permeates and 3 retentates).

Column 2 lists the corresponding DOC levels obtained. Column 3 shows the mass balances

calculated for each individual membrane. For each individual membrane, the mass balance was

obtained using the following equation:

MB = (Vp-DOCp) + VR-DOCR

Where: Vp: Volume of permeate

VR: Volume of retentate

DOCp: Concentration of permeate

R: Concentration of retentate (after dilution correction)

Mass balances were calculated in order to evaluate losses (organics), such as from

evaporation and adsorption. The DOCs obtained from the mass balances (for each individual

membrane) should be the same as the DOC of the unfractionated (whole) sample. If these values differed, a correction factor was determined. To distribute systematic losses (organics) occurring

during all filtrations over all the fractions, the permeate concentrations were normalized, based

on the recovery shown by the mass balance, to the unfractionated sample. A correction factor

271

was calculated which equaled the DOC of the unfractionated sample divided by the mass balance DOC. The corrected DOC for each permeate was obtained by multiplying the original permeate DOC value by that fraction's correction factor, as shown below for the 0.5K AMW fraction:

Correction Factor0.sK = DOCunfractipnated sample/ MBo.s K.

DOCo.sK, P corrected = DOC0.sK, P ' Correction Factor

To determine the AMW distribution of, for example, DOC, the percent DOC of each

molecular weight range fraction was calculated by (1) subtracting the permeate DOC concentration of one membrane from the DOC concentration of the permeate obtained from the

next larger pore sized (i.e., higher MW) membrane and (2) dividing by the DOC of the unfractionated sample.

For example, for the AMW range less than 0.5K (<0.5K) daltons, the percent DOC equals the DOC of the permeate for the 0.5K AMW fraction times 100 divided by the unfractionated sample DOC. For the range greater than 0.5K and less than 3K daltons (0.5K < AMW < 3K), the percent DOC is calculated by subtracting the DOC of the permeate for the 0.5K AMW cutoff fraction from the permeate DOC for the 3K AMW cutoff fraction, multiplying by 100, and dividing by the DOC of the unfractionated sample. For the range of

AMW greater than 10,000 (>10K daltons), the percent DOC is calculated by substracting the

DOC of the permeate for the 10K AMW cutoff from the unfractionated sample DOC,

multiplying by 100, and dividing by the unfractionated sample DOC. For the example in Table

A.I, the percent DOC in the 0.5K to 3K AMW range equals (1.81 - 0.302) • 100/2.96 = 50.9

percent.

272

Table A.I

Example of UF calculations

Fraction (MWC)

Whole Sample

1 OK PermeatelOKRetentate

3K Permeate

3K Retentate0.5K Permeate

0.5K Retentate

DOC(mg/L)

2.972.455.22

1.96

8.21

0.33

14.68

Mass Balance**

3.01

3.21

3.20

Correction Factor

0.986

0.924

0.928

Corrected DOC (mg/L)

2.972.42

1.81

0.30

Fraction (Daltons)

>10K

3K-10K

0.5K-3K

<0.5K

Percent DOC

18.4

20.5

50.9

10.2

*DOC concentrations of retentates have been corrected for dilution with rinse water.** Permeate and retentate volumes were 800 and 200 mL, respectively.

273

Table A.2

UF comparison of chloramination and chlorination—CSPW

Fraction (MWC)

DOC(mg/L)

DOCMass

Balance

UV-254 (cm-1 ) UVMass Balance

DOX DOXMass

BalanceInfluent

WholeSample

10KP10KR3KP3KR0.5KP0.5KR

4.06

2.916.712.069.810.7614.63

3.67

3.61

3.53

0.104

0.0810.2020.0540.3050.0140.462

0.105

0.104

0.104

SDS— ChloramineWholeSample


3.40

2.776.951.969.660.6815.56

3.61

3.50

3.66

0.108

0.0840.1910.0550.2890.0250.416

0.105

0.102

0.103

188

19731913642071

541

222

193

165

SDS— ChlorineWholeSample

10KP10KR3KP3KR0.5KP0.5KRP = permeateR = retentate

3.35

2.656.382.009.130.8814.22

3.40

3.42

3.54

0.064

0.0510.1120.0340.1740.0130.264

0.063

0.062

0.063

846

66697251112322991893

727

655

617

274

Table A.3 Comparison of chloramine treatment conditions—LHW*

Fraction(MWC)

DOC(mg/L)

DOCmass balance

DOX(mg/L)

DOXmass balance

SourceWhole Sample


Whole Sample


Whole Sample

10KP10KR3KP3KR0.5KP0.5KRP = permeateR = retentate

11.04

6.2423.943.1532.000.8337.00

SDS Condition A:10.96

6.6022.663.39

27.981.64

33.86SDS Condition B:

11.12

6.0523.443.2129.140.39

37.38

11.55

11.81

11.68

Cl2/N=5/l;pH=

11.41

10.77

11.31

Cl2/N=7/l;pH=

10.40

10.99

11.49

6; Total residual 4 mg/L512

425724200906112

12468; Total residual 4 mg/L

840

3408203009402401260

515

412

452

484

492

546

1 UV-254 analyses were not performed on this set of samples.

275

Table A.4 UF data for LHW pilot plant (enhanced coagulation)

Fraction(MWC)

DOC DOC Mass(mg/L) Balance

UV-254(cm' 1 )

UV Mass DOX DOX MassBalance (mg/L) Balance

Influent

Whole Sample10KP10KR3KP3KR0.5KP0.5KR

3.133.14 3.102.962.29 3.317.380.48 3.5215.66

0.0580.0470.0900.0350.1280.0250.294

0.056

0.054

0.079

Effluent


P = permeateR = retentate

3.272.89 3.154.192.11 3.177.420.77 3.5314.56

0.0520.0430.0920.0330.1340.0070.242

650.053 56 58

670.053 39 49

860.054 39 63

163

276

Table A.5

UF data for CSPW full-scale plant*

Fraction

(MWC)DOC DOC Mass

(mg/L) BalanceUV-254(cm' 1 )

UV Mass DOX DOX MassBalance (mg/L) Balance

Influent


3.37

1.88 3.097.921.88 3.479.840.84 4.1417.32

0.1190.0830.2360.0540.3600.0060.590

0.114

0.115

0.123

Effluent


P = permeateR = retentate

3.002.53 3.205.882.08 3.097.101.04 3.53

13.50

0.0700.0580.1240.0490.1540.0140.288

3250.071 297 279

18500.070 249 299

5020.069 113 251

804

*pH = 8.3, C12 /N = 5/1, total residual = 1.6 mg/L

277

Table A.6 UF data for midsouth water

Fraction(MWC)

DOC(mg/L)

DOC UV-254 UVMass DOX

Mass Balance (cm" 1 ) Balance (mg/L)DOX Mass

Balance

Influent


3.272.825.972.008.210.16

15.89

0.050

3.45 0.047 0.0520.070

3.24 0.037 0.0500.104

3.30 0.004 0.0490.230

Effluent


P = permeate

R = retentate

2.972.455.221.968.210.3314.68

0.046 120

3.01 0.039 0.044 96

0.066 137

3.21 0.034 0.044 1050.086 216

3.20 0.008 0.044 43

0.190 246

105

127

83

278

Table A.7

UF data for Pacific Northwest water

Fraction

(MWC)

DOC

(mg/L)

DOC UV-254 UVMass DOX

Mass Balance (cm" 1 ) Balance (mg/L)

DOX Mass

Balance

Influent

Whole Sample

10KP

10KR

3KP

3KR

0.5KP

0.5KR

0.81

0.31

2.49

0.20

3.03

0.12

3.73

0.034

0.75 0.013 0.041

0.152

0.77 0.005 0.039

0.176

0.84 0.003 0.036

0.168

Effluent

Whole Sample

10KP

10KR

3KP

3KR

0.5KP

0.5KR

P = permeate

R = retentate

0.88

0.39

2.77

0.28

3.19

0.154.11

0.04 145

0.86 0.012 0.036 62

0.13 302

0.86 0.007 0.034 51

0.142 362

0.94 0.006 0.036 30

0.156 448

110

113

114

279

APPENDIX B

DATA FROM INDIVIDUAL TASK 2 PILOT PLANT TESTS

281

Table B.I Lake Austin water pilot plant test — run 1A

Description of Conditions: C12 to N Ratio — 3 to 1 Mode of Operation: Ambient bromide (0.30 mg/L), Lime Softening, Prechloramination,

SDS at pH 10, Residual Target 2 mg/L

Date/Time

Run DayCl2 DoseNH4CI-N Dose*TurbidityAlkalinityTOCtpHBrfNorn. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., IdCHC13, 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3, 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dC1MC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.J

Units

mg/Lmg/Lntu

mg CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/L«g/LHg/LHg/LHg/Lpga>Hg/L"g/Lug/LHg/LHg/LHg/LA»fcug/LHg/LMg/L

vgcn

Source

7/25/94

NANA2.721522.57.780.3NANANANANANANANANANANANANANANANANANANANANANANA

Sample 1

7/25/94,am

12.8

0.930.0970NR8.89NR10

9.810

2.280

2.280000000

3.73.84.912.625000

19.945.1%

Sample 1

7/25/94,pm

12.8

0.93NRNRNRNRNR10

9.810

2.040

2.0400000

NRNRNRNRNRNR

-0.50

0.518.6

Sample2

7/27/94,am

32.9

0.970.164NR9.30NR10

9.980

2.290

2.291.1000

J.JO00

1.82.13.48.275.5NRNR

-NR

Sample 2

7/27/94,pm

32.9

0.970.0964NR9.43NR10

10.010

2.360

2.3600000

NRNRNRNRNRNR

-NRNR

-NR

Sample 3

7/28/94,am4

2.80.930.1260NR9.97NR10

9.940

2.570

2.570000000

2.72.33.910.719.6NRNR

-22.7

Sample 3

7/28/94,pm4

2.80.930.1156NR9.68NR10

9.950

2.440

2.4400000

NRNRNRNRNRNR

-NRNR

-NR

Mean Std. Value Dev.

2.83 0.050.94 0.02

2.33 0.180.18

000

0.18 0.4500

2.732.734.0710.5020.03 4.760.25

00.25 0.3520.4 2.1

Task la Data

0.24

2.08

0.70

3.20

00

45.1% NANote: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply

* This value, forNH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratiot Sample collected in early July 1994{ Reported only where all of the target DBFs were measured

282

Table B.2 Lake Austin water pilot plant test — run IB

Description of Conditions: C12 to N Ratio — 3 to 1 Mode of Operation — Ambient bromide (0.30 mg/L), Lime Softening, Prechloramination,


Date/Time

Run DayC12 DoseNH4C1-N Dose*TurbidityAlkalinity

TOCfPHBrtNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3, 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA,2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX,2d%DOXRec.J

Units

mg/Lmg/Lntumg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/LHg/Lug/L"g/Llig/L.ug/Lug/LHg/Lug/Lug/Lug/Lpg/Lug/Lug/Lt&L

t*gcr/L

Source

7/25/94

NANA2.72152

2.57.780.3NANANANANANANANANANANANANANANANANANANANANANANA

Sample 1

7/25/94,am

12.8

0.930.0970

NR8.89NR

88.30

02.27

02.27

2000

2.00000

1.50

14.5161.40

1.427.7

25.2%

Sample 1

7/25/94,pm

12.8

0.93NRNR

NRNRNR

88.31

02.04

02.04

00000

NRNRNRNRNRNR

-1.26

01.2631.2

-

Sample 2

7/27/94,am

32.9

0.970.164

NR9.30NR

88.19

02.31

02.31

00000000001111NRNR

-NR-

Sample 2

7/27/94,pm

32.9

0.970.0964

NR9.43NR

88.24

02.40

02.40

00000

NRNRNRNRNRNR

-NRNR

-NR-

Sample 3

7/28/94,am4

2.80.930.1260

NR9.97NR

88.15

02.57

02.57

0000000000

4.34.3NRNR

-26.2

-

Sample 3

7/28/94,pm4

2.80.930.1156

NR9.68NR

88.11

02.54

02.54

00000

NRNRNRNRNRNR

-NRNR

-NR

-


2.83 0.050.94 0.02

2.36 0.200.33

000

0.33 0.82000

0.500

9.9310.43 5.871.33

01.33 0.1028.3 2.525.2% NA

Task la Data

0.24

2.26

0.50

6.20 .

4.3031.5

13.5%Note: Values below detection limit reported as zeroact. = actualincub = incubationNA = not applicablenom = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation— = does not apply* This value, for NKUCL-N dose, is a multiple of the measured chlorine dose and the CVN ratiot Sample collected in early July 1994| Reported only where all of the target DBFs were measured

283

Table B.3 Lake Austin water pilot plant test — run 2 A


SDS at pH 1 0, Residual Target 2 mg/L

Date/Time


TOCtPHBrtNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC1 3 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3, 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.}

Units

mg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/L"g/LHg/Lug/Lfg/LHg/LHg/LHg/LHg/Lug/Lug/Lfig/LHg/Lug/LVg/L

tig cr/L

Source

8/1/94

NANA2.98153


Sample 1

8/1/94,am

12.930.590.3153

NR9.82NR10

10.190

2.540

2.540000

0.00000

1.1011

12.1NRNR

-31.9

-

Sample 1

8/1/94,pm

12.930.590.0750

NR9.76NR10

10.110

2.610

2.61000

1.21.20NRNRNRNRNRNR

-NRNR

-NR

-

Sample 2

8/3/94,am

32.930.590.1270

NR9.07NR10

9.330

2.160

2.162.41.2.01.2

4.8000000

11.577.5NRNR

-31.7

-

Sample 2

8/3/94,pm

32.990.600.2265

NR9.57NR10

9.700

2.520

2.523.1000

3.10NRNRNRNRNRNR

-NRNR

-NR

-

Sample 3

8/4/94,am4

2.990.600.0960

NR9.59NR10

10.010

2.490

2.49000

1.11.10

00000

12.912.9NRNR

-33. 4

-

Sample 4

8/5/94,am5

2.930.590.0553

NR9.53NR10

10.110

2.380

2.38000

1.21.20NRNRNRNRNRNR

-000

NR-


2.95 0.030.59 0.01

2. 45 0.160.920.20

00.781.90 1.74

000

0.370

11.8072.77 0.42

000

32.3 0.916.6%§

Task la Data

0.24

7.92

0

NR

NR44.5

-Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply

* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratiot Sample collected in early July 1994} Reported only where all of the target DBFs were measured§ Based on information in Mean Value column

284

Table B.4 Lake Austin water pilot plant test — run 2B



Date/Time

Run DayCl2 DoseNH^Cl-N Dose*TurbidityAlkalinity

TOCtPHBr'tNom. Incub. pHAct Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHCl2 Res.,2dTotal Res., 2dCHCl3,2dCHBrCl2,2dCHBr2Cl, 2dCHBr3, 2dTTHM, 2dMCAA,2dDCAA,2dTCAA,2dMBAA,2dDBAA,2dBCAA,2dHAA6,2dCNCL2dCNBr,2dTCNX, 2dDOX,2d%DOXRec.t

Units

mg/Lmg/Lntumg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/Lpg/Lug/Lug/Lug/Lug/Lug/Lug/LPSS/Lug/Lug/LA*#X

tigcr/L

Source

8/1/94

NANA2.98153


Sample 1

8/1/94, am

12.930.570.3153

NR9.82NR

88.12

02.54

02.541.5000

1.5000000

8.58.5NRNR

-44.6

-

Sample1

8/1/94, pm

12.930.570.0750

NR9.76NR8

8340

2.610

2.671000

1.00NRNRNRNRNRNR

-NRNR

-NR-

Sample 2

8/3/94, am3

2.930.490.1270

NR9.07NR8

8.000

2.160

2.162.51.400

3.9000000

10.610.6NRNR

-44.3

-

Sample 2

8/3/94, pm3

2.990.500.2265

NR9.57NR8

8.120

2.520

2.5200000

NRNRNRNRNRNR

-NRNR

-NR-

Sample 3

8/4/94, am4

2.990.570.0960

NR9.59NR8

8.040

2.490

2.490000000000

9.69.6NRNR

-43.4

-

Sample 4

Mean Std. Task la Value Dev. Data

8/5/94, am

52.930.570.0553

NR9.53NR8

7.940

2.380

2.384.8000

4.80NRNRNRNRNRNR

-L540

1.54NR'

2.95 0.030.55 0.04

2.45 0.161.630.23

00

1.87 2.0300000

9.579.57 1.051.540

1.5444.1 0.6

11.1% 5

0.24

2.12

15.50

NR

NR160.0

-Note: Values below detection limit reported as zeroact = actualincub. = incubationNA = not applicablenom. = nominalNR = notnm ;rec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply*Thisvalue,forNH4Cl^Ndose,kaniultipleofthenieasuredchkMTnedo«anduKClj/Nrttt»t Sample collected in early July 1994J Reported only where all of the target DBFs Were measured -,§ Based on information in Mean Value:cohimn

285

Table B. 5 Lake Austin water pilot plant test — run 3

Description of Conditions: CI2 to N Ratio — 5 to 1 Mode of Operation — Direct filtration with Alum, Ambient bromide (NR), Prechloramination,

. SDS at pH 8, Residual Target 2 mg/L

Date/Time

Run DayCl2 DoseNH|CI-N Dose*TurbidityAlkalinity

TOCtPHBr'tNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2Cl Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBrj, 2dTTHM, 2dMCAA,2dDCAA,2dTCAA,2dMBAA,2dDBAA,2dBCAA,2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d%DOXRec.J

Units

mg/Lmg/Lntumg

CaCOs/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/L"g/L"g/LHg/Lmft-Hg/LHg/Lug/L"g/Lug/L"g/L«0£Hg/LHg/LWft

ttgcr/L

Source

1 1/1 1/94

NANA2.91166

4.617.78NRNANANANANANANANANANANANANANANANANANANANANANRNA

Sample 1

11/12/94,am

13.650.730.17162

3.07.65NR

87.97

02.00

02.002.12

1.10

5.200

5.200

1.65.111.9NRNR

-60.6

-

Sample 1

11/12/94,pm

13.650.730.22165

NR7.48NR

87.94

01.51

01.511.91.91.10

4.90NRNRNRNRNRNR.

NRNR

-70.6

-

Sample2

1 1/13/94,am2

3.70.740.13163

NR7.70NR

88.07

01.55

01.552.12.11.20

5.40NRNRNRNRNRNR.

NRNR

-67.0

-

Sample 2

11/13/94,pm2

3.70.740.12164

NR7.58NR

88.47

02.06

02.064.24.42.90

11.50NRNRNRNRNRNR

-NRNR

-61.6

-

Sample 3

11/14/94,am3

3.630.73NRNR

NRNRNR

88.06

01.720

1.726.61.91.10

9.600

4.200

2.33.910.42.80

2.871.0

19.5%

Sample 3

11/14/94,pm3

3.630.730.12161

NR7.90NR

88.10

01.76

01.763.61.71.10

6.400

5.600

2.74.1

12.403.70

3.761.9

12.9%

Mean Value

3.660.73

1.773.422.331.42

07.17

05.00

00

2.204.3711.573.25

03.2565.4

16.2%

Std. Task la Dev. Data

0.030.01

0.24

0.77 2.12

2.74 15.50

1.04 NR

0.64 NR4.7 160.0

4.7% NANote: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runstd. dev. = standard deviation- = does not apply rec. = recovery res. = residual

* This value, for NH,CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratiot Sample collected 11/14/94I Reported only where all of the target DBFs were measured

286

Table B.6 Lake Austin water pilot plant test — run 4

Mode of Operation —

Date/Time


TOCpHBrNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13, 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3, 2dTTHM, 2dMCAA,2dDCAA, 2dTCAA, 2dMBAA,2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.J

Units

mg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/Lt>g/Lug/Lug/Lug/Lug/Lug/Lug/Lfg/Lug/Lug/L/<g/i

pgCr/L

Source

11/18/94

NANA2.72152

3.647.78NRNANANANANANANANANANANANANANANANANANANANANANANA

Description of Conditions: C12 to N Ratio — 5 to 1 Direct Filtration with Alum, Ambient bromide (NR), Postchloramination,

SDS at pH 8, Residual Target 2 mg/LSample

111/18/94,

am1

2.30.460.16160

2.87.83NR

88.10

01.02

07.02

0000

0.000

2.500

3.43

8.9NRNR

-60.5

-

Sample 1

11/18/94,pm

12.30.460.12164

NR7.81NR

88.00

01.23

01.23

01.100

1.10NRNRNRNRNRNR

-NRNR

-52.0

-

Sample2

11/19/94,am2

2.40.480.32165

NR7.72NR

88.19

02.07

02.07

01.400

1.400

5.200

2.73.511.4NRNR

-59.7

-

Sample2

11/19/94,pm2

2.40.480.3166

NR7.77NR

88.01

01.78

01.78

01.500

1.50NRNRNRNRNRNR

-NRNR

-61.6

-

Sample 3

1 1/20/94,am

32.70.540.14162

NR7.71NR

88.07

02.00

02.00

01.300

1.30NRNRNRNRNRNR

- .4.99

04.9963.9

-

Sample 3

1 1/20/94,pm3

2.70.540.10168

NR7.88NR

88.07

02.09

02.0P

01.400

1.40NRNRNRNRNRNR

-3.20

3.255.0

-


2.47 0.190.49 0.04

0.24

7.70 0.46 NA0

1.1200

1.12 0.56 NA0

3.8500

3.053.2570.75 7.77 NA4.10

0470 7.27 NA58.8 4.5 NA

6.2%JNote: Values below detection limit reported as zero

act. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* This value, for NHjCL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBFs were measured t Based on information in the Mean Value column •

287

Table B.7 Lake Austin water pilot plant test — run 5 A

Description of Conditions: C12 to N Ratio — 5 to 1 Mode of Operation — Ambient bromide (NR), Lime Softening, Ozonation, Postchloramination,


Date/Time

Run DayC12 DoseNH4C1-N DoseTurbidityAlkalinity

TOCPHBfNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC1 3 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA,2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d%DOXRec.*

Units

mg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lrng/Lmg/Lmg/Lug/Lug/Lug/Lug/Lfg/Lug/Lug/L"g/Lug/Lug/Lug/Lfg/Lug/Lug/Lfg/L

fg Cr/L

Source

12/9/94

NANA2.2168

NR7.74NRNANANANANANANANANANANANANANANANANANANANANANANA

Sample1

12/9/94,am

1NANA0.1671

NR9.53NR

10.009.83

01.81

01.81

0000

0.000000000

1.40

1.422.50.3%

Sample 1

12/9/94,pm

1NANA

19.0071

NR9.26NR

10.009.97

02.08

02.08

0000

0.000

NRNRNRNRNR

-NRNR

-NR

-

Sample 2

12/10/94am2

NANA0.2169

NR9.7NR

10.009.93

02.00

02.00

0000

0.000

1.100000

1.101.00

1.028.40.9%

Sample 2

12/10/94,pm2

NANA0.1069

NR9.52NR

10.009.99

02.00

02.00

0000

0.00NRNRNRNRNRNR

-NRNR

-NR

-

Sample 3

12/11/94,am3

NANA0.2170

NR9.59NR

10.009.89

01.98

01.98

0000

0.0000000

1.41.40NRNR

-33.6

-

Sample 3

12/11/94,am3

NANA0.1774

NR9.38NR

10.009.91

02.00

02.22

0000

0.00NRNRNRNRNRNR

-•NRNR

-NR

-


0.24

2.02 0.13 NA00000 0 NA0

0.37000

0.470.83 0.74 NA1.20

01.20 0.28 NA28.2 5.55 NA0.6% 0.4% NA

Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* Reported only where all of the target DBFs were measured

288

Table B.8 Lake Austin water pilot plant test — run 5B

Description of Conditions: Cl2 to N Ratio — 5 to 1 Mode of Operation — Ambient bromide (NR), Lime Softening, Ozonation, Postchloramination,


Date/Time

Run DayC12 DoseNH,C1-N DoseTurbidityAlkalinity

TOCpHBr-

Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2 , 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.*

Units

mg/Lmg/Lntumg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/Lug/Lug/Lug/LMg/LHg/Lug/LHg/Lug/Lug/Lug/Lfg/Lug/Lug/LMg/L

ftgCr/L

Source

12/9/94

NANA2.2168

NR7.74NRNANANANANANANANANANANANANANANANANANANANANANANA

Sample1

12/9/94, am

1NANA0.1671

NR9.53NR

87.73

02.35

02.35

0000

0.000

1.40000

1.44.50.75.2

25.72.9%

Sample 1

12/9/94, pm

1NANA0.1971

NR9.26NR

88.17

02.14

02.14

0000

0.00NRNRNRNRNRNR

-NRNR

-NR

-

Sample 2

12/10/94, am2

NANA0.2169

NR9.70NR

87.63

01.830

1.830

1.11.20

2.3000000

1.41.44.32.87.1

31.59.3%

Sample2

12/10/94, pm

2NA

. NA0.169

NR9.52NR

88.02

02.08

02.08

00'

00

0.00NRNRNRNRNRNR

-NRNR

-NR

-

Sample 3

12/11/94, am3

NANA0.2170

NR9.59NR

88.05

02.03

02.03

0000

0.000

1.50000

1.5NRNR

-317

-

Sample 3

12/11/94 am3

NANA0.1774

NR9.38NR

88.00

01.98

01.98

02

2.42.36.70NRNRNRNRNRNR

-NRNR

-NR

-


2.07 0.1 70

0.520.600.387.50 2.77

01.0000

0.51.4 0.06

4.401.756.15 1.3430.3 4.136.1% 4.5%

NA

NA

NA

NA

NANANA-

Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom.= nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* Reported only where all of the target DBFs were measured

289

Table B.9 Lake Houston water pilot plant test — run 1

Description of Conditions: C12 to N Ratio — 3 to 1 Mode of Operation — Ambient bromide (0.05 mg/L), Prechloramination, Conventional Coagulation, SDS at pH 8,

Residual Target 2 mg/L

Date/Time

Run DayAlum DoseC12 DoseNH4C1-N Dose*TurbidityAlkalinity

TOCpHBr'

Nom. Incub. pHAct. Incub. pH,2dFree C12 Res.,2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2 , 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.t

Units

mg/Lmg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/L

mg/Lmg/Lmg/LHg/LHg/LHg/LHg/Lfg/LHg/LHg/LHg/LHg/LHg/LHg/Lt&L"g/L"g/Lfg/L

fgCVL

Source

10/15/95

NANANA3457

4.56.470.05NANA

NA

NANANANANANANANANANANANANANANANANANANA

NA

Sample 1

10/15/95,am

1669.03.00.12NR

NR6.00NR

87.50

0.30

2.350

2.650

3.11.40

4.501.4

12.800

1.83.279.2

000

103.06.4%

Sample 1

10/15/95,pm

1669.03.0

0.15NR

NR5.90NR

87.40

0.10

2.800

2.900

3.51.50

5.00NRNRNRNRNRNR

-0.50

0.599.1

-

Sample 2

10/16/95,am2

669.03.0

0.1331

2.216.24NR

87.90

0.25

2.550

2.8002

0.60

2.600

16.2000

3.619.8NRNR

-105.6

-

Sample2

10/16/95,pm2

669.03.0

0.11NR

NR6.17NR

88.30

0

2.700

2.7002

0.60

2.60NRNRNRNRNRNR

-NRNR

-102.5

-

Sample 3

10/17/95,am3

669.03.0

0.15NR

1.95.80NR

88.00

0

3.200

3.200

2.31.10

3.400

13.82.60

1.13.1

20. 6NRNR

-110.7

-

Sample 3

10/17/94,am3

669.03.0

0.22NR

NR5.55NR

88.00

0

2.800

2.800

2.410

3.40NRNRNRNRNRNR

-NRNR

-104.1

-

Mean Value

669.03.0

2.840

2.551.03

03.580.4714.270.87

00.973.3019.870.25

00.25104.26.4%


0.08

0.20 7.57

0.98 2.10

0.70 28.40

0.35 2.503.86 65.5NA 12.8%

Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply

* This value, forNH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBFs were measured

290

Table B. 10 Lake Houston water pilot plant test — run 2

Description of Conditions: Cl2 to N Ratio — 3 to 1 Mode of Operation — Ambient bromide (0.05 mg/L), Conventional Coagulation, Postchloramination,


Date/Time

Run DayAlum DoseC1 2 DoseNH4C1-N Dose*TurbidityAlkalinity

TOCpHBr-Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.f

Units

mg/Lmg/Lmg/Lntumg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/LHg/LHg/LHg/Lfg/LHg/LHg/LHg/LHg/LHg/LHg/LPg/L"g/LHg/Lfg/L

ngcr/iNA

Source

2/27/95

NANANA62

21.3

12.36.220.05NANANANANANANANANANANANANANANANANANANANANANA

6.5%

Sample 1

2/25/95,am

1668.02.7

0.15NR

NR4.51NR

87.00

02.40

02.403.2

100

4.200

12.41.1000

13.512.91.2

14.1108.2

-

Sample 1

2/25/95,pm

1668.02.7

0.12NR

NR4.60NR

87.12

02.50

02.503.31.400

4.70NRNRNRNRNRNR

-13.21.2

14.4102.76.5%

Sample 2

2/26/95,am2

668.02.70.141.9

3.954.65NR

87.47

03.10

03.102.71.100

3.800

11.32.100

1.314.76.90

6.9105.6

-

Sample2

2/26/95,pm2

668.02.70.2NR

NR4.67NR

87.36

03.00

03.002.8

100

3.80NRNRNRNRNRNR

-6.90

6.9110.9

-

Sample 3

2/27/95,am3

668.02.7

0.22NR

NR4.720.01

87.15

02.90

02.902.81.400

4.20NRNRNRNRNRNR

-NRNR

-113.5

-

Sample 3

2/27/95,am3

668.02.70.25NR

NR4.70NR

87.31

02.80

03.003.2000

3.20NRNRNRNRNRNR

-NRNR

-106.3

-


668.02.7

2.82 0.293.000.98

00

3. 98 0.510

11.851.60

00

0.6514.10 0.859.980.6010.58 5.99108.1 3.886.5% 0.0%

Task la Data

0.08

1.51

2.10

28.40

2.5065.5

12.8%Note: Values below detection limit reported as zeroact. = actualincub. = incubation ,NA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBFs were measured

291

Table B. 11 Lake Houston water pilot plant test — run 3 A

Description of Conditions: Cl2 to N Ratio — 3 to 1 Mode of Operation — Ambient bromide (NR), Prechloramination, Enhanced Coagulation, SDS at pH 8, Residual Target 2 mg/L

Date/Time


TOCpHBfNom. Incub. pHAct. Incub. pH,2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dfCHBrCl2 2dfCHBr2cC 2dfCHBr3 , 2dfTTHM, 2dfMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.J

Units

mg/Lmg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/LPg/Lug/Lug/Lug/Lug/Lug/Lug/LI&Lug/Lug/LPg/L

fgCr/L

Source

11/28/94

NANANA5433

10.16.95NRNANA

NANANANANANANANANANANANANANANANANANANANA

NA

Sample1

1 1/28/94,am

1887.22.4

0.12NR

NR4.73NR

87.20

01.50

01.503.5210

6.500

18.82.500

2.523.86.84

06.8499.1

10.7%.

Sample1

11/28/94,pm

1887.22.4NRNR

NRNRNR

8NR

NRNRNR

-NRNRNRNR

-NRNRNR

•NRNRNR

-NRNR

-NR

-

Sample 2

1 1/29/94,am2

887.22.4

0.220

3.13NRNR

8NR

NRNRNR

-NRNRNRNR

-NRNRNRNRNRNR

-NRNR

-NR

-

Sample 2

1 1/29/94,pm2

887.22.4NRNR

NRNRNR

8NR

NRNRNR

-NRNRNRNR

-NRNRNRNRNRNR

-NRNR

-NR

-

Sample 3

11/30/94,am3

887.22.4

0.17NR

NR4.800.02

87.22

01.50

01.504.11.900

6.000

19.31.700

2.223.2NRNR

-104.1

-

Sample 3

1 1/30/94,am3

887.22.4NRNR

NRNRNR

8NR

NRNRNR

-NRNRNRNR0.00NRNRNRNRNRNR

-NRNR

-NR

-


887.22.4

7.50 0.003.801.950.50

06.25 OJ5

019.052.10

00

2.3523.5 0.426.84

06.84 0.0101.6 3.5410.7% NA

Task la

Data

0.08

7.57

2.70

28.40

2.5065.5

12.8%Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratiot Sample time (am or pm) was not indicated on label} Reported only where all of the target DBFs were measured

292

Table B.I2 Lake Houston water pilot plant test — run 3B

Mode of Operation

Date/Time


TOCPHBr"Norn. Incub. pHAct. Incub. pH, 2dFree C1 2 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., IdCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA,2dTCAA, 2dMBAA,2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.f

Description of Conditions: C12 to N Ratio — 3 to 1 — Ambient bromide (NR), Prechloramination, Enhanced Coagulation, SDS

Units

mg/Lmg/Lmg/Lntumg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/LHg/LHg/LHg/LPg/LHg/LHg/LHg/Lug/L"g/LHg/Lfg/LHg/Lug/LVg/L

fgCVL

Source

1 1/28/94

NANANA5433


Sample 1

11/28/94,am

1887.22.4

0.12NR

NA4.67NR

65.73

01.100.601.702.21.900

4.100

19.3200

2.824.10

7.62.510.1109.68.8%

Sample 1

11/28/94,pm

1887.22.4NRNR

NANRNR

6NRNRNRNR

-NRNRNRNR

-NRNRNRNRNRNR

-NRNR

-NR

-

Sample 2

1 1/29/94,am2887.22.40.22

0

3.134.78NR6

5.740

1.000.901.904.71.700

6.400

20.62.100

2.825.50

7.02.49.4

115.810.2%

Sample2

1 1/29/94,pm2

887.22.4NRNR

NANRNR

6NRNRNRNR

-NRNRNRNR

-NRNRNRNRNRNR

-NRNR

-NR

-

Sample 3

1 1/30/94,am3887.22.40.37NR

NA4.85NR

65.70

01.100.701.805.21.700

6.900

21.72.300

3.427.40NRNR

-111.5

-

at pH 6, ResidualSample

31 1/30/94,

am3887.22.4NRNR

NANRNR

6NRNRNRNR

-NRNRNRNR

-NRNRNRNRNRNR

-NRNR

-NR

-

Mean Value

887.22.4

1.804.031.77

00 ,

5.800

20.532.13

00

3.0025.<57

7.32.59.8

112.39.5%

Target 2 mg/LStd. Task la Dev. Data

0.08

0.10 2.26

1.49 5.30

1.66 38.50

0.49 8.603.18 174.11.0% 4.0%

Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBFs were measured

293

Table B.I3 Lake Houston water pilot plant test — run 4A

Mode of Operation

Date/Time


TOCpHEfNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3, 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.t

Units

mg/Lmg/Lmg/Lntumg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/Lfg/Lug/Lug/Lug/Lug/Lug/Lug/Lfg/Lug/Lug/Lpga*

ngcr/L

Description of Conditions: C12 to N Ratio — 3 to 1 — Ambient bromide (0.05 mg/L), Enhanced coagulation, Postchloramination, SDS at pH 8,

Residual Target 2 mg/LSource

3/11/95

NANANA4235


Sample1

3/11/95,am

1887.72.60.13NR

NR4.65NR

88.44

03.10

03.105.11.800

6.901.3

11.73.40

1.94.9

23.21.90

1.982.3

14.4%

Sample1

3/11/95,pm

1887.72.6

0.11NR

NR4.70NR

88.40

02.94

02.945.11.800

6.90NRNRNRNRNRNR

-NRNR

-85.0

-

Sample 2

3/1 1/95,am2

887.72.60.12

3

3.374.820.01

88.45

02.80

02.80

6200

8.001.1

12.23.20

1.95.5

23.9NRNR

-75.9

-

Sample 2

3/1/95,pm2

887.72.6

0.13NR

NR4.80NR

88.42

02.36

02.365.81.900

7.70NRNRNRNRNRNR

-NRNR

-80.6

-

Sample 3

3/1 1/95,am3887.72.60.15NR

NR4.90NR

87.80

02.57

02.57

51.900

6.901.0

11.23.20

2.05.5

22.9NRNR

-82.9

-

Sample 3

3/1 1/95,am3

887.72.6NRNR

NRNRNR

8NRNRNRNRNRNRNRNRNRNRNRNRNRNRNRNR

-NRNR

-84.8

-


887.72.6

2.75 0.295.401.88

00

7.28 0.531.13

11.703.27

01.935.30

23.33 0.571.90

0/.90 NA81.9 3.4

14.4% NA

Task la Data

0.08

1.51

2.10

28.40

2.5065.5

12.8%Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply

* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBFs were measured

294


Description of Conditions: C12 to N Ratio — 3 to 1 Mode of Operation — Ambient bromide (0.05 mg/L), Enhanced Coagulation, Postchloramination,


Date/Time


TOCPHBr-

Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2 C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrC!2 , 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.f

Units

mg/Lmg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/LHg/LHg/Lug/Lfg/LHg/Lug/LHg/Lug/LHg/LHg/LPg/LHg/L"g/Lfg/L

ngcr/i

Source

3/1 1/95

NANA4235


Sample 1

3/11/95,am

1887.72.6

0.13NR

NR4.75NR

65.98

02.400.502.906.12.300

8.400

6.51.70

1.73.813.712.210.422.6111.813.3%

Sample 1

3/1 1/95,pm

1887.72.6

0.11NR

NR4.70NR6

6.100

2.300.602.906.3200

8.30NRNRNRNRNRNR

-NRNR

-115.5

-

Sample2

3/1 1/95,am2

887.72.6

0.123

3.374.820.01

66.30

02.800.403.207.22.200

9.4000000

1.01.012.36.418.7116.78.5%

Sample 2

3/1/95,pm2

887.72.6

0.13NR

NR4.80NR

66.25

02.700.403.105.5200

7.50NRNRNRNRNRNR

-NRNR

-707.9

-

Sample 3

3/1 1/95,am3

887.72.6

0.15NR

NR4.88NR6

6.220

2.600.302.905.62.300

7.9000000

1.01.0NRNR

-109.2

-

Sample 3

3/1 1/95,am3

887.72.6NRNR

NR4.85NR

6NRNRNRNRNRNRNRNRNR

-NRNRNRNRNRNR

-NRNR

-110.7

-

Mean Value

887.72.6

3.006.142.16

00

8.300

2.170.57

00

1.935.2312.258.40

20.65112.010.9%


0.08

0.15 2.26

0.78 5.30

7.33 38.50

2.76 8.603.5 174.13.4% 4.0%

Note: Values below detection limit reported as zeroact. = actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBPs were measured

295

Table B.I5 Lake Houston water pilot plant test — run 5A


Date/Time

Run DayAlum DoseC12 DoseNH4CI-N Dose*TurbidityAlkalinity

TOCpHBrNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2d .,Total Res., 2dCHC13, 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.f

Units

mg/Lmg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/L"g/LHg/LHg/LP&LHg/LHg/LHg/LHg/LHg/LHg/LP8/L"g/LHg/Lfg/L

fgCr/L

Source

3/11/95

NANANA5535


Description of Conditions: C12 to N Ratio — 3 to 1 0.3 mg/L Bromide Added, Prechloramination, Conventional

SDS at pH 8, Residual Target 2 mg/LSample

13/1 1/95,

am1

667.92.6

0.13NR

NR4.600.38

87.40

01.80

01.806.43.913.918.8

43.000

10.52

3.911.314

41.7NRNR

-189.6

-

Sample 1

3/11/95,pm

1667.92.6NRNR

NR4.63NR

87.350.101.80

01.904.33.913.117.739.0NRNRNRNRNRNR

-NRNR

-185.7

-

Sample 2

3/11/95,am2

667.92.6

0.150

3.144.65NR

87.30

01.60

01.606.21.2

14.219.240.8

08

1.84

10.212.436.4

216.118.1190.619.1%

Sample 2

3/1/95,pm2

667.92.6NRNR

NR4.68NR

87.32

01.75

07.754.66.112

16.739. 4NRNRNRNRNRNR

-NRNR

-79*2

-

Sample 3

3/11/95,am3667.92.6

0.17NR

NR4.66NR

87.24

01.500

1.505.79.712.817.9

46.100

9.51.9411

13.239.6NRNR

-188.5

-

Sample 3

3/11/95,am

3667.92.6NRNR

NR4.67NR

87.30

01.60

01.604.67.911.216.139.8NRNRNRNRNRNR

-NRNR

-179.4

-

Coagulation,


667.92.6

7.69 0.755.305.4512.8717.7341.4 2.73

09.31.94.010.813.239.2 2.72.0016.1078.70 NA188.0 5.0419.1% NA

Task la Data

0.58

1.42

0.00

NR

NR84.3NA


296


Mode of Operation — 0.3

Date/Time


TOCPHBr-

Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6. 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.f

Units

mg/Lmg/Lmg/Lntumg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/L"g/LHg/LHg/LHg/Lfg/Lug/Lug/Lug/Lug/Lug/Lug/LVg/Lug/Lug/LA«fc

itgcr/L

Source

3/1 1/95

NANANA5535


Description of Conditions: C12 to N Ratio — 3 to 1 mg/L Bromide Added, Prechloramination, Conventional Coagulation, SDS at

pH 6, Residual Target 2 mg/LSample

13/1 1/95,

am1

667.92.6

0.13NR

NR4.600.38

65.790.101.000.601.704.73.112

15.735.50

08

1.63.98.811.333.66.614.927.5200.016.4%

Sample 1

3/1 1/95,pm

1667.92.6NRNR

NR4.63NR

65.810.101.000.701.805.34.911.114.4

35.70NRNRNRNRNRNR

-NRNR

-205.6

-

Sample 2

3/1 1/95,am2

667.92.6

0.150

3.144.65NR

65.85

01.200.601.804.96

9.612.7

33.200

8.41.93.88.911.334.3NRNR

-205.8

-

Sample 2

3/1/95,pm2

667.92.6NRNR

NR4.68NR

65.90

01.200.802.004.59.312.516.8

43.10NRNRNRNRNRNR

-NRNR

-797.5

-

Sample 3

3/11/95,am3

667.92.60.17NR

NR4.66NR6

5.910

1.100.701.804.56.610.413

34.500

8.61.74

9.311.835.4NRNR

-206.3

-

Sample 3

3/11/95,am

3667.92.6NRNR

NR4.67NR

65.870.101.000.601.704.66.910.412.8

34.70NRNRNRNRNRNR

-NRNR

-200.8

-


667.92.6

1.80 0.114.756.1311.0014.2336.1

08.31.73.99.011.534.4 0.96.614.927.5 NA202.7 3.7116.4% NA

Task la Data

0.58

1.60

19.10

NR

NR205.8NA


297

Table B.I7 California State Project water pilot plant test — run 1

Description of Conditions: C12 to N Ratio — 5 to 1, Mode of Operation — Ambient Bromide (0.23 mg/L), concurrent NaOCl and NH4C1 added in rapid mix,


Date/Time

Run DayAlum DosePolymer DoseC12 DoseNH4C1-N Dose*TurbidityAlkalinity

Hardness

TOCPHBr'Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13, 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHA A 6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.J

Units

mg/Lmg/Lmg/Lmg/Lntumg

CaCO3/Lmg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/LHg/LHg/LHg/LI&LHg/LMg/Lug/L"g/L"g/LHg/Lfg/LHg/LHg/LPgSL

ngcr/L

Source

9/27/94

NANANANA0.4280

120


Sample1

9/27/94,am

143

2.150.430.09NR

120

NR7.70NR

87.75NRNRNR

1.41-f7.4

.8.55.62.2

23.70

4.300

2.16.813.25.66.812.436.2

56.9%

Sample 1

9/27/94,pm

143

2.250.450.09NR

119

NRNRNR

87.86

01.23

01.235.97.55.12

20.50

2.2000

6.68.85.26.912.147.8

36.7%

Sample 2

9/28/94,am243

2.10.420.05NR

119

NR7.68NR

87.81

01.15

01.156.59

6.52.624.6

03.1000

7.110.24.87

11.842.8

47.1%

Sample 2

9/28/94,pm243

2.150.430.07NR

NR

NR7.75NR

8NRNRNRNR

-6.79.26.62.7

25.20

1.40007

8.45.36.712

49.141.0%


43

2.16 0.060.43

0.23

1.26 0.066.638.555.952.3823.50 2.09

02.75

00

0.536.8870.75 2.775.236.8572.08 0.2544.0 5.8545.4% 8.8%

Task la Data

0.10

2.58

0.00

NR

NR46.1NA

Note: Values below detection limit reported as zeroact. = actual incub. = incubation NA = not applicable nom. = nominal NR = not run

rec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply

* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratiot Measured with colorimetric DPD% Reported only where all of the target DBFs were measured

298

Table B.I8 California State Project water pilot plant test — run 1 (repeat)

Description of Conditions: C12 to N Ratio — 5 to 1 Mode of Operation: Ambient Bromide (0.23 mg/L), concurrent NaOCI and NH4C1 added


Date/Time


Hardness

TOCPHBr'Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 2dTTHM. 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.J

Units


CaCO3/Lmg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/Lt»g/Lug/LUg/Lug/Lug/Lug/LUg/Lfg/Lug/LUg/LI&L

ItgCT/L

Source

10/1/94

NANANANA0.5481

116

2.938.150.23NANANANANANANANANANANANANANANANANANANANANANA

NA

Sample 1

10/10/94,am

143

2.920.580.07NR

112

NR8.11NR

87.970.001.600.001.6010.613.811.75.8

41.90

3.9001

7.812.7NRNR

-69.8

-

Sample 1

10/10/94,pm

1433

0.600.09NR

117

NR8.15NR

87.970.001.780.001.7810.413.811.25.4

40.8NRNRNRNRNRNR

-NRNR

-77.9

-

Sample 2

10/11/94,am243

2.80.560.07NR

118

NR8.18NR

87.97NRNRNR

1.64f10

12.510.75.2

38.40

4.9003

8.916.84.67.972.573. 441.1%

Sample 2

10/11/94,pm243

2.90.580.09NR

NR

NR8.15NR

87.97NRNRNR

1.64f10.614.712.45.8

43.5NRNRNRNRNRNR

-NRNR

-79.4

-

Sample 3

10/12/94,am343

3.070.610.06NR

NR

NR8.00NR

87.970.001.480.001.487.412.111.45.9

36. 80400

2.88.775.5

411.115.1NR

-

Sample 3

10/12/94,pm343

3.020.600.07NR

NR

NR8.04NR

87.970.001.610.001.618.712.210.64.6

36.1NRNRNRNRNRNRNRNRNR

-NR

-

in rapid mix,

Mean Value

43

2.950.59

0.23

1.639.6213.1811.335.45

39.580

4.2700

2.278.4775.004.309.5073.8073.6341.1%


0.10

0.10

0.72 2.38

2.95 0.00

2.10 NR

8.84 HR4.12 46.10

NA NANote: Values below detection limit reported as zeroact. = actual incub. = incubation NA = not applicable nom. = nominal NR = not run


* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratiot Measured with colorimetric DPD% Reported only where all of the target DBFs were measured

299

Table B.I9 California State Project water pilot plant test — run 2

Mode of Operation -

Date/Time

Run DayAlum DosePolymer DoseC12 DoseNH,CI-N Dose*TurbidityAlkalinity

Hardness

TOCpHBr-Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHClj, 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2ctCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.t

Units

mg/Lmg/Lmg/Lmg/L

ntumg

CaCOj/Lmg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/LHg/L

•ug/LHg/LPg/LHg/LHg/LHg/LHg/L"g/LHg/Lfg/LHg/LHg/LHg/L

fgcr/L

Description of Conditions: C12 to N Ratio — 5 to 1 — Ambient Bromide (0.25 mg/L), Postchloramination, 1 Minute. Delay NH4C1,

SDS at pH 8, Target Residual 2 mg/LSource

10/19/94

NANANANA0.578

114


Sample 1

10/18/94,am

143

NRNR0.07NR

111

NR7.94NR

87.85

01.51

01.51

1216.611.6

545.2

03.3

10

2.15.912.314.09.5

23.49103.733.2%

Sample 1

10/18/94,pm

143

NRNR0.08NR

NR

NR7.86NR

87.69

01.66

07.5613.217.211.34.946.6NRNRNRNRNRNRNR17.510.7

28.19110.0

-

Sample 2

10/19/94,am243

NRNR0.06NR

114

NR7.90NR

87.77

01.61

01.6111.715.610.8

543.1

03.4

10

1.65.711.75.49.7

15.06118.227.6%

Sample 2

10/19/94,pm243

NRNR0.07

NR

116

NR7.83NR

87.77

01.63

01.6311.616.210.94.843.5NRNRNRNRNRNRNR5.69.9

75.52106.6

-

Mean Value

43

NRNR

0.25

1.6012.1316.4011.154.9344.60

03.351.00

01.855.8012.0010.669.9120.57109.6330.4%


0.10

7.67 NA

0.35 NA

0.42 NA

6.39 NA6.27 NA4.0% NA



* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBFs were measured

300

Table B.20 California State Project water pilot plant test — run 3A

Description of Conditions: C12 to N Ratio — 5 to 1 Mode of Operation — Ambient Bromide (0.23 mg/L), Preozonation (Target Residual 0.35 mg/L), biofiltration

(GAC/sand), postchloramination, SDS at pH 8, Target Residual 2 mg/L

Date/Time

Run DayO3 doseO3 res.Alum DosePolymer DoseC12 Dose*NH4C1-N Dose*fTurbidityAlkalinity

Hardness

TOCpHBr'Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.§

Units

mg/Lmg/Lmg/Lmg/Lmg/Lmg/Lntumg

CaCO3/Lmg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/L"g/Lug/LHg/Lug/LK/LMg/LHg/LHg/LHg/LHg/Lfig/LP&L"g/Lug/Lfg/L

fgcr/L

Source

10/4/94

NANANANANANA0.6282

119


Sample 1

10/4/94,am

10.750.41

43

2.50.500.1NR

119

NR7.59NR

88.15

01.39

07.39

01.71.50

3.200000

2.02.06.01.37.3

46.56.6%

Sample 1

10/4/94,pm

10.750.38

43

2.50.500.07NR

119

NR7.50NR

88.17

01.45

01.45

01.61.40

3.000000

2.22.25.61.36.8

41.77.2%

Sample2

10/5/94,am2

0.750.31

43

2.50.500.08NR

120

NR7.61NR

88.24

01.79

01.79

01.51.30

2.81.30000

2.43.78.21.39.5

61.75.1%

Sample2

10/5/94,pm2

0.750.43

43

2.50.500.09NR

NR

NR7.91NR

88.19

01.55

07.55

01.51.30

2.8t0000

1.81.8NRNR

-67.6

-

Mean Value

0.750.38

43

2.50.50

0.23

7.550

1.581.38

02.950.43

0000

2.102. 436.601.277.86

54.386.3%


0.000.05

NA

0.78 NA

0.19 NA

0.87 NA

1.43 NA12.26 NA1.1% NA



* Batch chloraminated in laboratoryfThis value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio{Interference in chromatogram§Reported only where all of the target DBFs were measured

301

Table B.21 California State Project water pilot plant test — run 3B

Description of Conditions: C12 to N Ratio — 5 to 1 Mode of Operation — Ambient Bromide (0.23 mg/L), Preozonation (Target Residual 0.35 mg/L), no biofiltration

(laboratory filtration), postchloramination, SDS at pH 8, Target Residual 2 mg/L

Date/Time

Run DayO3 doseO3 res.Alum DosePolymer DoseC12 Dose*NH4C1-N Dose*tTurbidityAlkalinity

Hardness

TOCPHBr'Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res, 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6. 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.§

Units


CaCOj/Lmg

CaCO3/Lmg/LNAmg/LNANA

mg/Lmg/Lmg/Lmg/Lug/LHg/Lug/LHg/Lfg/Lug/Lug/Lug/Lng/Lug/Lug/Lrg/Lug/Lug/LP&L

fgcr/L

Source

10/4/94

NANANANANANA0.6282

119

3.280460.23NANANANANANANANANANANANANANANANANANANANANANANA

Sample1

10/4/94,am

10.750.41

43

2.50.500.1NR

119

NR7.59NR

88.19

01.63

01.63

01.61.40

3.02.30000

2.24.55.90.76.5338.2

7.6%

Sample 1

10/4/94,pm

10.750.38

43

2.50.500.07NR

119

NR7.50NR

88.22

01.72

01.72

01.51.30

2.8t0000

1.61.66.90.57.4

55.05.0%

Sample 2

10/5/94,am2

0.750.31

43

2.50.500.08NR

120

NR7.61NR

88.22

01.59

01.59

01.51.20

2.72.70000

1.94.614.11.0

15.1366.04.9%

Sample2

10/5/94,pm2

0.750.43

43

2.50.500.09NR

NR

NR7.91NR

88.23

01.79

01.79

01.51.30

2.82.20000

1.53.7NRNR

.67.5

-


0.75 0.000.38 0.05

43

2.50.50

0.23 NA

1.68 0.09 NA0

1.531.30

02.83 0.13 NA2.40

0000

1.803.60 1.39 NA8.950.739.69 4.73 NA

56.68 13.52 NA5.8% 1.5% NA

Note: Values below detection limit reported as zerorec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply

act. = actualincub. = incubationNA = not applicablenom. = nominalNR = not run* Batch chloraminated in laboratorytThis value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio{Interference in chromatogram§Reported only where all of the target DBFs were measured

302

Table B.22

California State Project water pilot plant test — run 4ADescription of Conditions: C12 to N Ratio — 5 to 1

Mode of Operation — Ambient Bromide (0.23 mg/L), Preozonation (Target Residual 0.55 mg/L), biofiltration (GAC/sand), postchloramination, SDS at pH 8, Target Residual 2 mg/L

Date/Time

Run DayO3 doseO3 res.Alum DosePolymer DoseCI2 Dose*NH4CI-N Dose*tTurbidityAlkalinity

Hardness

TOCPHBfNom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNCI, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.J

Units


CaCOj/Lmg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/L(•&!>ug/Lug/Lug/Lug/Lug/LUg/Lfg/Lug/Lug/LPg/L

ngcr/L

Source

10/11/94

NANANANANANA0.54

NR

116


Sample 1

10/11/94,am

1NR0.58

43

2.60.520.06NR

116

NR8.00NR

88.34

01.65

01.652.72.11.90

6.700001

2.23.23.90.9

4.8232.6

17.7%

Sample1

10/11/94,pm

1NR0.55

43

2.60.520.08NR

NR

NR8.00NR

88.29

01.61

01.612.42

1.80

6.2NRNRNRNRNRNR

-NRNR

-15.9

-

Sample2

10/12/94,am2

1.460.68

43

2.60.520.05NR

116

NR8.00NR

88.23

01.63

01.63

0000

0.0000002

2.05.01.3

6.33NR-

Sample2

10/12/94,pm2

2.050.46

43

2.60.520.06NR

NR

NR8.00NR

88.30

01.65

01.650.5000

0.5NRNRNRNRNRNR

-NRNR

-NR-


1.76 0.420.57 0.09

43

2.600.52

0.23 NA

1.64 0.02 NA1.401.030.93

03.35 3.59 NA

0000

0.502.102.60 0.85 NA4.461.125.58 1.07 NA24.25 11.81 NA17.7% NA NA

Note: Values below detection limit reported as zero

act. = actual incub. = incubation NA = not applicable nom. = nominal NR = not run


* Batch chloraminated in laboratoryf This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio^Reported only where all of the target DBFs were measured

303

Table B.23 California State Project water pilot plant test — run 4A (repeat)

Mode of Operation — Ambient

Date/TimeRun DayO3 doseO3 res.Alum DosePolymer DoseC12 Dose*NH4C1-N Dose'tTurbidityAlkalinity

HardnessTOCPHBr"Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC1 3 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.J

Units


CaCO3/Lmg CaCO3/L

mg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/Lfg/Lug/Lug/Lug/Lug/Lug/Lug/LPB/Lug/Lug/LPgSL

vg cr/L

Description of Conditions: C12 to N Ratio — 5 to 1 Bromide (0.25 mg/L), Preozonation (Target Residual 0.55 mg/L), bioflltration (GAC/sand), postchloramination, SDS at pH 8, Target Residual 2 mg/LSource

10/24/94

NANANANANANA0.54NR

109

7.850.25NANANANANANANANANANANANANANANANANANANANANANA

NA

Sample1

10/24/94, am1

1.20.643

2.60.520.05NR

109NR7.79NR

88.22

01.62

07.620.81.51.40

3.700000

1.87.84.10.44.5547.06.8%

Sample 1

10/24/94, pm1

1.680.48

43

2.60.520.09NR

NRNR7.83NR

88.21

01.70

01.701.71.31.10

4.1NRNRNRNRNRNR

-NRNR

-52.8

-

Sample 2

10/25/94, am2

1.830.48

43

2.60.520.05NR

115NR7.70NR

88.21

01.35

01.351.91.31.20

4.402001

1.74.74.81.1

5.9423.6

19.3%

Sample 2

10/25/94, pm2

1.83NR43

2.60.520.07NR

NRNR7.76NR

88.16

01.40

01.402.71.31.20

5.2NRNRNRNRNRNR

-NRNR

-47.0

-

Mean Value

1.640.52

43

2.600.52

0.25

7.521.781.351.23

04.35

01.00

00

0.501.753.254.470.785.25

42.6013.1%


0.300.07

NA

0.77 NA

0.64 NA

2.05 NA

0.98 NA12.96 NA8.8% NA



* Batch chloraminated in laboratoryfThis value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratioJ Reported only where all of the target DBPs were measured

304

Table B.24 California State Project water pilot plant test — run

Description of Conditions: Water - Mode of Operation — Ambient Bromide (0.23 mg/L),

4BC12 to N Ratio — 5 to 1 Preozonation (Target Residual 0.55 mg/L),

no biofiltration (laboratory filtration), postchloramination, SDS at pH 8, Target

Date/Time


Hardness

TOCpHBr'Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d%DOX rec.J

Units


CaC03/Lmg

CaCO3/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/LHg/LHg/Lug/Lug/Lfg/Lug/Lug/Lug/Lug/Lug/Lug/Lfg/Lug/Lug/Lfg/L

fgCr/L

Source

10/11/94

NANANANANANA0.5481

116


Sample1

10/11/94,am

1NR0.58

43

2.60.520.06NR

116

NR8.00NR

88.36

01.81

01.812.92

1.80

6.7000002

2.04.80.3

5.1342.0

12.6%

Sample1

10/11/94,pm

1NR0.55

43

2.60.520.08NR

NR

NR8.10NR

88.30

01.83

01.832.91.91.70

6.5 .NRNRNRNRNRNR

-NRNR

-47.7

-

Sample2

10/12/94,am2

1.460.68

43

2.60.520.05NR

116

NR7.95NR

88.24

01.81

01.81

1000

1.000000

2.12.14.01.1

5.04NR-

Sample2

10/12/94,pm2

2.050.46

43

2.60.520.06NR

NR

NR7.94NR

88.31

01.79

01.791.1000

1.1NRNRNRNRNRNR

-NRNR

-:NR

-

Residual 2 mg/LMean Std.Value Dev.

1.76 0.420.57 0.09

43

2.600.52

0.23

1.81 0.021.980.980.88

03.83 3.21

00000

2.052.05 0.074.400.695.09 0.0644.85 4.0312.6% NA

Task laData

NA

NA

NA

NA

NANANA

Note: Values below detection limit reported as zeroact. = actual incub. = incubation NA = not applicable

nom. = nominal NR = not run rec. = recovery

res. = residualstd. dev. = standard deviation- = does not apply

* Batch chloraminated in laboratorytThis value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio{Reported only where all of the target DBFs were measured

305

Table B.25 California State Project water pilot plant test — run 4B (repeat)

Description of Conditions: C12 to N Ratio — 5 to 1 Mode of Operation: Ambient Bromide (0.28 mg/L), Preozonation (Target Residual 0.55 mg/L),no biofiltration (laboratory filtration), postchloramination, SDS at pH 8, Target Residual 2 mg/L

Date/Time


Hardness

TOCPHBr"Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2C1 Res., 2dNHC12 Res., 2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3, 2dTTHM, 2dMCAA,2dDCAA, 2dTCAA, 2dMBAA,2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.tNote: Values belowact. = actualincub. = incubationNA = not applicable

Units


CaCO3/Lmg

CaC03/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/Lfig/Lug/Lug/Lug/Lug/Lug/LHg/Lftg/Lug/Lug/Lftg/L

iig cr/Ldetection

Source

10/24/94

NANANANANANA0.5477

109


Sample1

10/24/94,am

11.20.643

2.60.520.05NR

109

NR7.79NR

88.23

01.83

07.831.051.31.20

3.60

2.400

1.31.85.54.40.65.07NR-

Sample1

10/24/94,pm

11.680.48

43

2.60.520.09NR

NR

NR7.83NR

88.21

01.78

07.784.31.200

5.5NRNRNRNRNRNR

-NRNR

.37.7

-

Sample2

10/25/94,am2

1.830.48

43

2.60.520.05NR

115

NR7.70NR

88.22

01.65

01.655.91.31.10

8.31

3.1000

1.85.96.31.17.4150.2

15.3%

Sample2

10/25/94,pm2

1.83NR

43

2.60.520.07NR

NR

NR7.76NR

88.14

01.71

07.77

0100

7.0NRNRNRNRNRNR

.NRNR

.29.7

-

Mean Std.Value Dev.

1.64 0.300.52 0.07

43

2.600.52

0.28

1.74 0.082.811.200.58

04.59 3.090.502.75

00

0.651.805.70 0.285.350.876.27 7.70

39.00 70.3815.3% NA

Task laData

NA

NA

NA

NA

NANANA

limit reported as zeronomNRrec.

. = nominal= no run= recovery

resstd

. = residual

. dev. = standard deviation- = does not apply

* Batch chloraminated in laboratoryfThis value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio{Reported only where all of the target DBFs were measured

306

Table B.26 California State Project water pilot plant test — run 5


Date/Time


Hardness

TOCPHBr"Nom. Incub. pHAct. Incub. pH, 2dFree C12 Res., 2dNH2 C1 Res., 2dNHCl2 Res.,2dTotal Res., 2dCHC13 , 2dCHBrCl2, 2dCHBr2Cl, 2dCHBr3 , 2dTTHM, 2dMCAA, 2dDCAA, 2dTCAA, 2dMBAA, 2dDBAA, 2dBCAA, 2dHAA6, 2dCNC1, 2dCNBr, 2dTCNX, 2dDOX, 2d% DOX Rec.f

Units


CaCO3/Lmg

CaCOj/Lmg/LNA

mg/LNANA

mg/Lmg/Lmg/Lmg/Lug/Lug/Lug/Lug/Lfg/Lug/Lug/Lug/Lug/Lug/Lug/LUg/Lug/Lug/Lfg/L

pgcr/L

Description of Conditions: C12 to N Ratio — 3 to 1 - Ambient Bromide (0.28 mg/L), Conventional Alum Treatment, Prechloramination,

SDS at pH 8, Target Residual 2 mg/LSource

10/25/94

NANANANA0.5477

109

NR7.850.28NANANANANANANANANANANANANANANANANANANANANANANA

Sample 1

10/25/94,am

143

3.21.140.06NR

115

NR7.82NR

87.80

02.79

02.79

01.300

1.31.95.100

1.93.512.43.01.0

3.9865.56.2%

Sample1

10/25/94,pm

143

3.31.040.07NR

NR

NR7.81NR

87.67

02.78

02.78

01.600

1.6NRNRNRNRNRNR

-NRNR

-33.7

-

Sample 2

10/26/94,am243

3.41.040.06NR

NR

NR7.81NR

87.91

02.81

02.81

01.300

1.31

5.200

2.74

12.9NRNR

-31.1

-

Sample 2

10/26/94,pm243

2.880.990.07NR

NR

NR7.85NR

87.77

02.55

02.55

01.200

1.2NRNRNRNRNRNR

-NRNR

-47.5

-


43

3.20 1.061.05 0.50

0.28

2.73 0.120

1.3500

1.35 0.171.455.15

00

2.303.7572.<55 0:353.020.963.98 NA

44.44 15.786.2% NA

Task la Data

0.10

2.48

0.70

4.90

2.8042.54.3%

Note: Values below detection limit reported as zeroact. - actualincub. = incubationNA = not applicablenom. = nominalNR = not runrec. = recoveryres. = residualstd. dev. = standard deviation- = does not apply* This value, for NH4CL-N dose, is a multiple of the measured chlorine dose and the C12/N ratio t Reported only where all of the target DBPs were measured

307

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ABBREVIATIONS

AC

ACS

ADJ

amu

AMW

AWWA

AWWARF

BAA

BCAA

BDL

CAA

carbopak-BCH2Br2

CH2ClBrCLAAs

CLAMs

CLPs

cm

CNX

CNX-Br

CNX-C1

CNXOX

cone.

CP CSPW

CT °C

d DAM

analytical columnAmerican Chemical Societyadjustment

atomic mass unitapparent molecular weight


American Water Works Association Research Foundation

bromoacetic acid

bromochloroacetic acid

below detection limit

chloroacetic acidgraphitized carbondibromomethanebromochloromethanechlorinated amino acidschlorinated alkylamineschlorinated peptides

centimeter

cyanogen halide

molar concentration of bromine in cyanogen halidemolar concentration of chlorine in cyanogen halideorganic halogen contributed by CNXconcentrationpermeate concentrationCalifornia State Project water

concentration times timedegrees Celsius

daydiazomethane

325

DBAA

1,2-DBP

DBF

DBPFP

DBPOX

DBPOXFPDCAA

DCAN

DIDOC

DOX

DOX2

DOXFP

DOXFP4

DPD

DXAA

ECBCDEl

ESI

eV

F

FP

ft

g G

GAC

GC

gpm

dibromoacetic acid

1,2-dibromopropane

disinfection by-product

disinfection by-product formation potential

organic halogen contributed by DBFsdisinfection by-product organic halogen formation potentialdichloroacetic acid

dichloroacetonitriledeionizeddissolved organic carbon

dissolved organic halogen

dissolved organic halogen concentration after 2 daysdissolved organic halogen formation potential

4-day dissolved organic halide formation potential

JVJV-diethyl-p-phenylenediamine

dihalogen-substituted acetic acidenrichment columnelectron capture detectorelectron impact

electrospray ionizationelectron volt

fractional reduction in retentate volumeformation potential

foot

gram

mean velocity gradientgranular activated carbon

gas chromatograph; gas chromatographygallons per minute

326

hHAA

HAAFP4

HAAS

HAA6

HAA6-Br

HAA6-C1

HAA6OXHAN

HPLC

hr

1C

ID

I.D.

in.

INJ

I.S.

K

kg

KI

L

LAW

LC

LH

LHW

LLElow/delay

m

hour

haloacetic acid

4-day haloacetic acid formation potential

sum of the mass concentrations of five commonly

measured haloacetic acids

sum of the mass concentrations of the six commonly measured

haloacetic acids (MCAA, MBAA, DCAA, DBAA, BCAA, TCAA)

total HAA6 bromine molar concetration

total HAA6 chlorine molar concentration

organic halogen contributed by HAA6haloacetonitrile

high pressure liquid chromatographyhour

ion chromatograph; ion chromatography

inner diameter

inner diameterinch

injector

internal standard

1,000

kilogram

potassium iodide; potassium iodide method

liter

Lake Austin water

liquid chromatograph; liquid chromatography

Lake Houston

Lake Houston water

liquid-liquid extractionlow with delay

meter

327

M

MBMBAA

MCAA

MCL

MDL

med./delay

mg

min

min.

mmmM

mmole

mL

MS

MTBE

MW

MWC

MWDSC

MXAA

m/zn

n

n' (3/6)

N

NA

ND

ng

molar

mass balance

monobromoacetic acid

monochloroacetic acid

maximum contaminant level

method detection limit

medium with delay

milligram

minute

minute

millimeter

millimolar

millimole

milliliter

mass spectrometer; mass spectrometrymethyl ter/-butyl ether

molecular weight

molecular weight cut off

Metropolitan Water District of Southern Californiamonohalogen-substituted acetic acid

mass-to-charge ratio

degree of bromination; sample size

bromine incorporation factor

bromine incorporation factor for the three brominated

haloacetic acids

normal

not analyzed or not available

not detected

nanogram

328

NIST

nm

NOM

NPOXNQ

NTUntu

OPW

P P

PAC

PB

pH

ppm

psi

QA/QCr

randr2

RR2

sec

SDE

SDS

SPEB

std. dev.sur.

SUVASW

SWTR

t

National Institutes of Standards and Testingnanometernatural organic matternon-purgeable organic halogennot quantitatednephelometric turbidity unitnephelometric turbidity unitorganic-pure waterpermeation coefficientpermeate

Project Advisory Committeeparticle beamnegative logarithm of the effective hydrogen-ion

concentration parts per million pounds per square inch quality assurance/quality control correlation coefficient correlation coefficients retentatecoefficient of determination secondsimultaneous distillation extraction simulated distribution system solid phase extraction standard deviation surrogatespecific ultraviolet absorbance switching valve Surface Water Treatment Rule time

329

TCAA

TCE

TCNX

THAAX

THM

TTHM

TTHM2

TTHM-Br

TTHM-C1

THMFP4

TTHMOX

TTHMX

TOC

UF

UH

USEPA

UT

uvUV-VIS

UV-254

V

vocw/

YC

YM

X

jjmol

utnole

trichloroacetic acid

trichloroethene

total cyanogen halide

total haloacetic acid halogen

trihalomethane

total trihalomethanes

total trihalomethanes concentration after 2 days

total trihalomethane bromine molar concentration

total trihalomethane chlorine molar concentration

4-day trihalomethane formation potential

organic halogen contributed by TTHMtotal trihalomethane halogen molar concentration

total organic carbon

ultrafiltration

University of Houston

United States Environmental Protection Agency

University of Texasultraviolet

ultraviolet-visible irradiation

ultraviolet radiation at 254 nanometers

volume

volatile organic compoundwith

cellulose acetateregenerated cellulose

wavelength

microgram

microliter

micron

micromole

micromole

330


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