EFFECTS OF NICKEL ON ACTIVATED SLUDGE PERFORMANCE

AT VARYING COD:TKN RATIOS

by

Patti Gremillion Trahern

Thesis submitted to the Faculty of the

Virginia Polytechnic Institute and State University

in partial fulfillment of the requirements of the degree of

MASTER OF SCIENCE

APPROVED:

W. R. Knocke

in

Sanitary Engineering

J. H. Sherrard

December, 1982

Blacksburg, Virginia

C. W. Randall

ACKNOWLEDGMENTS

Sincere thanks to:

Dr. Joseph H. Sherrard, Dr. William R. Knocke and

Dr. Clifford W. Randall, Advisors and Committee Members, for

their advice, guidance and patience during the course of this

study.

Mr. Glenn Willard, Mr. Richard Mines, Mrs. Marilyn Grender,

and Mr. Victor Gulas for their technical assistance;

Ms. Ann Crate and Ms. Cathy Cook for manuscript preparation.

Special thanks to Bruce, Gordon, and Lynn, for their

unwavering and enthusiastic support.

This research was funded by a grant from the National

Science Foundation.

ii

TABLE OF CONTENTS

ACKNOWLEDGMENTS .

LIST OF TABLES

LIST OF FIGURES

INTRODUCTION

LITERATURE REVIEW .

TREATMENT EFFICIENCY • BOD and COD Removal . Turbidity . . Nitrification . . .

METAL UPTAKE . . . . . . . MECHANISMS OF METAL TOXICITY . SUMMARY ....

MATERIALS AND METHODS .

LABORATORY APPARATUS STARTUP . . . . . . . DAILY PROTOCOL . . . TECHNIQUES OF ANALYSIS

Solids . . . . . . Chemical Oxygen Demand, COD Ammonia Nitrogen, NH3-N Total Kjeldahl Nitrogen, TKN Nitrate Nitrogen, N03-N pH . . . . . . . . . . Alkalinity as Caco3 Nickel, Ni(II) ..

DATA ANALYSIS

RESULTS . . . • . .

TREATMENT EFFICIENCY . COD Removal . . . Reactor Solids, Effluent Suspended Solids, and

Biokinetic Coefficients . . . . • Nitrification .

NICKEL REMOVAL . . . . . . • .

iii

ii

v

vi

1

5

6 6

12 13 14 20 23

24

25 27 29 34 35 35 35 35 36 36 36 36 37

41

49 49

50 51 52

TABLE OF CONTENTS (continued)

DISCUSSION

TREATMENT EFFICIENCY • COD Removal Efficiency . . • . Reactor Solids Effluent Suspended Solids, and

Biokinetic Coefficients • • • . . • • • • . Nitrification

NICKEL REMOVAL . .

SUMMARY AND CONCLUSIONS

BIBLIOGRAPHY

APPENDIX A

APPENDIX B

VITA

ABSTRACT

iv

S3

S3 S3

SS 63 70

73

7S

79

83

102

LIST OF TABLES

TABLE

I U.S. Consumption of Nickel in 1980 ... 3

II Composition of Wastewater Feed Solution 30

III Parameters Monitored During Steady State Periods . • • • • • 32

IV COD:TKN Ratios and Nickel Doses 42

v Sunnnary of Steady State Data - Reactor I 44

VI Summary of Steady State Data - Reactor II 45

VII Summary of Steady State Data - Reactor III 46

VIII Summary of Steady State Data - Reactor IV 47

IX Summary of Steady State Data - Reactor V 48

x Biokinetic Coefficients 6;

v

LIST OF FIGURES

FIGURE

1 Theoretical Solubility of Nickel Hydroxide 16

2 Speciation Diagram for Nickel-Amine Complexes . • • • • . • 17

3 Experimental Completely Mixed Activated Sludge Unit • . . . . • • • • 26

4 COD Removal Efficiency vs. Mean Cell Residence Time • • • . • • • . • • • . • • . 5 4

5 Total Mixed Liquor Suspended Solids vs. Mean Cell Residence Time 56

6 Specific Utilization Rate vs. Mean Cell Residence Time . . . . . . . 59

7 Specific Growth Rate vs. Specific Utilization Rate • . . • . . 60

8 Observed Yield vs. Mean Cell Residence Time 64

9 Percent Nitrification vs. Mean Cell Residence Time . • • • . . . • . . . . • • . • . • . 65

10 Measured Change in Alkalinity vs. Predicted Change in Alkalinity . . . . • . . • • 68

11 Effluent pH vs. Mean Cell Residence Time 69

12 Nickel Removal vs. Mean Cell Residence Time 71

13 Percent Effluent Soluble Nickel vs. Mean Cell Residence Time 72

vi

INTRODUCTION

As the activated sludge process became an increasingly

popular method of wastewater treatment in the fifties and

sixties, more attention was devoted to specific problems

encountered in the optimization of secondary treatment plant

performance. The purpose of secondary wastewater treatment is

to reduce the amount of unstabilized organic material in the

wastewater by biological processes. In the activated sludge

process, this reduction is achieved by the natural respiratory

and oxidative functions of a diverse community of bacteria and

other heteotrophic microorganisms suspended in the wastewater

being treated.

The activated sludge process can also be operated to provide

nitrification. Nitrification, the oxidation of ammonia to

nitrate, is required of wastewater treatment systems discharging

into receiving waters which could be harmed by an ammonia-bearing

effluent. Two types of autotrophic bacteria, Nitrosomonas and

Nitrobacter, are responsible for nitrification. Nitrosomonas

oxidizes ammonia to nitrite:

2 + Nitrosomonas NH4 + 3 o2 [ lj

and then Nitrobacter oxidizes nitrite to nitrate:

2 - Nitrobacter N02 + o2 [ 2]

1

2

Performance of the activated sludge process, capable of very

high organic material removal, is dependent on many factors.

These include plant operating parameters, such as mean cell

residence time, suspended solids concentration, and dissolved

oxygen concentration, and physical factors, such as temperature,

pH and the presence of toxic materials, such as heavy metals.

The impact of heavy metals on human health has been recog-

nized since the 1800's. Adverse effects caused by inhalation of

heavy metal dust and vapor by workers in mining, smelting, and

other metal operations led to the development of metal toxi-

cology. The scope of this field was considerably broadened when

it became apparent that exposure to heavy metals and their toxic

effects was not limited to the industrial workplace. Incidents

such as the occurrence of itai-itai disease and methylMercury

poisoning, which affected many Japanese in the 1970's, piqued

interest in the fate of heavy metals in the environment (1).

In many of these cases, water, and specifically wastewater,

had introduced heavy metals into the environment. Nickel is

contributed to treatment plant influent almost exclusively by

industrial sources (2). A tough, silvery metal, nickel is used

in producing metal alloys, especially stainless steel. In 1970,

600 U.S. companies used nickel, a~d of those 600, 150 users manu-

factured alloys (3). Table 1 presents a breakdown of U.S.

consumption of nickel by use and form in 1980 (4). Nickel may be

released to the environment in smelting, refining, forming and

3

TABLE I

U.S. CONS!JMPTION OF NICKEL IN 1980

Use

Steel: Stainless- and heat-resisting Alloys (excluding stainless)

Super alloys

Ni-Cu and Cu-Ni alloys

Permanent magnetic alloys

Other nickel and nickel alloys

Cast irons

Electroplating

Chemicals and other chemical uses

Other uses

TOTAL

Short Tons

54,738 16,936

19,153

8, 775

538

27,444

4,074

18,751

1,475

4,442

156,299

4

fabrication operations. Most of these operations are more likely

to release nickel to the atmosphere than directly to wastewater

streams; however, electroplating rinses and any type of operation

which uses water to wash down nickel-bearing dust may contaminate

wastewater streams.

The purpose of this investigation was to determine the

effects of a small dose of nickel on activated sludge performance

by evaluating organic removal efficiency, degree of nitrifi-

cation, and biokinetic coefficients. Nitrification being of

particular interest, nitrogen loading rates were varied to assess

the effect of nitrogen concentration on nickel toxicity to

nitrification.

LITERATURE REVIEW

Much of the early work on metal toxicity to activated

sludge, co11ducted in the 1960's, concentrated on the effect of

heavy metals on treatment efficiency. Later studies, using

analytic techniques developed in the field of physical and

chemical kinetics, investigated the effects of heavy metals at

different stages of growth and substrate utilization by the

biomass responsible for organic degradation. These studies used

the concept of mean cell residence time as elucidated initially

by Jenkin (5) and expanded by others (6,7,8) as the primary

operating variable for the activated sludge process.

The effects of heavy metals on nitrification were briefly

noted in some of the early work, but interest in this particular

area was stimulated by the increasing number of activated sludge

plants required to provide nitrification as effluent standards

became more stringent.

Heavy metal doses used in these studies ranged from less

than 1 mg/1 to 100 mg/l. The effects of lesser doses are of

greater relevance to actual plant performance, as average heavy

metal concentrations in the influent to wastewater treatment

plants are generally low. For example, Hannah and others (2)

found an average of 0.2 mg/l nickel reaching 157 wastewater

plants, with individual plants receiving between 0.04 and 3 m.g/l

nickel average. A similar range was reported by Barth (9) in his

survey of four municipal plants.

5

6

Other researchers were interested in the phenomenon of metal

removal or uptake by activated sludge. Information as to how

metals actually bonded to the sludge led to hypotheses about the

mechanisms of toxicity.

The purpose of this chapter is to review and discuss re-

search conducted in these areas: (1) effects of heavy metals on

treatment efficiency, including nitrification, (2) heavy metal

uptake, and (3) mechanisms of heavy metal toxicity.

TREATMENT EFFICIENCY

Treatment efficiency for secondary wastewater treatment

systems is usually defined in terms of the effluent BOD and

suspended solids limitations placed upon them by regulatory

agencies. Researchers have used BOD removal rates, COD removal

rates, effluent turbidity and degree of nitrification to evaluate

the relative performance of metal-fed systems. Copper, chromium,

nickel and zinc have been of primary interest. Researchers have

observed the effects of shock loading and continuous dosing of

these metals on bench-scale and full-scale activated sludge

systems. Early research focused on copper, and these studies set

the protocol for the following investigations of nickel and other

heavy metals.

BOD and COD Removal

Heukelekian and Gellman (10) tested the effect of several

heavy metals, including nickel, on the oxidation of sewage and

7

activated sludge-sewage mixtures. They found that concentrations

of heavy metals from 5 to 100 mg/l depressed oxidation by both

sewage and activated sludge-sewage mixtures. Metals had a toxic

effect within a characteristic pH range, which, for copper,

corresponded to its solubility. The ratio of organic material to

metal concentration influenced toxicity. The activated sludge-

sewage mixtures were less susceptible to the toxic effects of

metals and exhibited an "increased tolerance" to metals upon

repeated exposures. Appearance of toxic effects tended to be

delayed for these mixtures when compared to sewage mixtures.

In 1963, McDermott (11) reported the effects of copper on

"replicate" activated sludge pilot plants. The pilot plants,

which were used in concurrent and later studies (12,13,14),

included units for primary settling, "spiral flow" aeration,

final settling, and anaerobic sludge digestion. The plants were

fed undiluted domestic sewage, supplemented synthetically if

necessary to approximate the characteristics of strong sewage.

The concept of mean cell residence time had not then been fully

developed. Researchers instead attempted to approach steady

state conditions by maintaining constant mixed liquor suspended

solids concentrations and detention times similar to those

encountered in the field.

McDermott dosed the pilot plants with up to 25 mg/l copper.

The metal-fed units experienced drops in COD removal efficiency

8

which ranged from insignificant to seven percent, with doses

under 1 mg/l having no apparent effect on removal efficiency.

That same year, Moulton (15) found that continuous doses up

to 45 mg/l of copper reduced but did not totally inhibit COD

removal by activated sludge. A year later, Salotto (12) epplied

continuous 1 and 5 mg/l doses of copper to pilot plants similar

to those used by McDermott. He discovered that the toxicity of

copper was not greatly affected by variations in organic loading.

COD removal efficiency was reduced by the addition of 5 mg/l of

copper, however.

In 1965, McDermott and others (13) turned their attention to

nickel toxicity. They conducted a pilot study to assess the

effect of continuous doses of nickel ranging from 1 to 10 mg/l

on replicate activated sludge pilot plants. BOD removal was

slightly depressed by nickel concentrations between 2.5 and 10

mg/l. Decrease in treatment efficiency was not proportional to

nickel dose. Treatment efficiency was about the same for the

unit fed 1 mg/l nickel and for the control unit run simulta-

neously. The researchers concluded that 1 mg/l produced no

significant toxic effects. The control unit used for comparison,

however, was about eight percent less efficient than the control

units run simultaneously with the reactors dosed between 2.5 and

10 mg/l. The possibility exists, therefore, that toxic effects

did occur at 1 mg/l.

9

Summarizing the results of these and other pilot studies on

the effects of copper, chromium, nickel, and zinc at doses

varying from 0.4 to 50 mg/l on replicate activated sludge plants,

Barth (14) noted that treatment efficiency was reduced by small

doses of each metal. Based on loss of treatment efficiency, a

threshold concentration for continuous doses of each metal was

set. The threshold concentration for nickel was estimated to be

between 1 and 2.5 mg/l.

Concurrently, Barth and others (16) studied the effects of

mixtures of copper, chromium, nickel and zinc, totaling 8.9, 4.9,

and 2.0 mg/l on pilot plants. The two higher concentrations

caused five percent decreases in COD removal efficiencies,

whereas the effect of the third, lower concentration was slight.

The results of a field survey of four municipal wastewater

treatment plants receiving wastes bearing copper, chromium,

nickel, and zinc, conducted by Barth and others (9), indicated

that treatment efficiency measured in the field was not notice-

ably impaired by similar concentrations of heavy metals. Of the

three activated sludge plants studied, treatment efficiency at

two was evaluated as excellent, with BOD removal averaging 92

percent at both plants, and COD removal averaging 85 and 87

percent. The third plant achieved only 75 percent BOD and 67

percent COD removals, but this lower efficiency was attributed to

process design limitations rather than to the presence of metals.

10

The development of the concept of mean cell residence tine

(MCRT), a parameter based on kinetically derived equations, but

easily determined from field measurements, led to a reawakening

of interest in the area of metal toxicity. Derived from kinetic

relationships for substrate utilization, mean cell residence time

offered activated sludge treatment plant operators a tool for

process optimization, and researchers a tool for further explor-

ation of the effects of metals on the activated sludge process.

Mean cell residence time, a measure of the time an individual

cell remains in the activated sludge system, depends upon a

number of practical values, including detention time, mixed

liquor suspended solids concentration, and degree of treatment.

It also depends upon the growth and decay rates of the micro-

organisms composing the biomass. Evaluation of certain para-

meters at known mean cell residence times allows calculation of

these kinetic rates.

Bagby (17), Weber (18), Sujarittanonta (19), and DiSalvo

(20) operated bench-scale, continuous flow activated sludge units

fed continuous doses of heavy metals at different MCRT's.

Organic removal efficiency was measured and changes in biokinetic

growth and utilization coefficients evaluated. Changes in treat-

ment efficiency were related to metal concentration and to metal

concentration-to-total system solids and organic load-to-metal

concentration ratios.

11

In Bagby's (17) study of cadmium and nickel, one reactor was

fed 5 mg/l cadmium and 1 mg/l nickel; the other, 10 rng/l cadmium

and 5 mg/l nickel, over a range of mean cell residence times. A

follow-up study was conducted at one MCRT with 5 mg/l cadmium and

1 mg/l nickel, and synthetic feed components doubled. At both

combined metal concentrations, COD removal efficiency was reduced

for all MCRT's. Increase in organic loading to the metal-fed

unit resulted in good COD removal, while increase in the ratio

of total influent metal concentration to total system solids de-

creased removal efficiency.

Weber (18) found that cadmium concentrations of 5 and 10

mg/l caused a slight drop in COD removal efficiencies for similar

units. Biokinetic coefficients were not affected. Sujarittanonta

(19) observed that nickel concentrations of 1 and 5 mg/l also did

not significantly alter treatment efficiency. Nickel toxicity

depended upon the COD-to-nickel ratio, the mixed liquor suspended

solids-to-nickel ratio, and the operating MCRT. Biokinetic

coefficients varied with COD-to-nickel ratios.

DiSalvo (20) dosed similar units with 0.5 mg/l nickel at

different organic loadings. COD removal efficiency was not

significantly impaired by the addition of this small concen-

tration of nickel over a range of MCRT's, although slight

inhibition was apparent at lower MCRT's. For both organic

loadings, removal efficiency increased with MCRT. Maximum

yield coefficient was greater for the metal-fed reactor than

12

for the control fed the same organic loading, and comparable

for the metal-fed reactor fed half the organic loading. (Control

data was collected, however, during a separnte, earlier study

(19); thus differences in yield coefficient between control and

metal-fed reactors cannot be attributed definitely to the

presence or absence of nickel.)

Turbidity

At low doses, heavy metals appear to improve settling by

changing floe characteristics, and effluent suspended solids

may be measurably reduced. Barth (16) found that both BOD and

suspended solids in the effluent from a reactor fed a low con-

centration of a mixture of heavy metals (2 mg/l) were less than

for his control, and surmised that the metal-fed sludge, being

more dense, settled more effeciently. McDermott (11) also

noted improved settling, despite increased effluent solids, for

reactors fed 1 mg/l copper. In most of the heavy metal studies

(11,13,15,16,21), however, effluent turbidity and suspended

solids increased in proportion to metal concentration. Moulton

(15), applying continuous doses of copper up to 45 mg/l, attri-

buted increased effluent suspended solids to the escape of

bacterial cells. Neufeld (22), primarily interested in the

phenomenon of heavy metals-induced deflocculation, found in-

creased suspended solids in the effluent of reactors shock-dosed

with mercury. While the increase in effluent suspended solids

could, in the case of non-soluble or partially soluble feed,

13

result from decreased organic removal efficiency, it seems

reasonable to speculate, as Moulton did, that higher doses of

heavy metals may cause an increase in the concentration of

bacterial cells in the effluent.

Nitrification

From the results of pilot studies, Barth (14) observed that,

for metal-fed reactors, effluent ammonia and dissolved oxygen

concentrations were higher, effluent nitrate much lower, and

effluent nitrite erratic.

Tomlinson (23) conducted a fill-and-draw batch activated

sludge reactor study, and concluded that heavy metals (copper,

mercury, and chrome) have a diminished effect on Nitrosomonas

when it is in mixtures of activated sludge and sewage than when

in pure cultures. Because sludge can accumulate metals, he

suggested that long-term effects might be more severe than

short-term effects.

In Weber's (18) study, nitrification was inhibited by

cadmium at concentrations of 5 and 10 mg/l applied to bench-

scale, continuous flow activated sludge reactors. Bagby (17)

found nitrification greatly reduced for a mixture of 5 mg/l

cadmium and 1 mg/l nickel applied to similar units, and almost

completely inhibited for a mixture of 10 mg/l cadmium and 5 mg/l

nickel. When substrate strength was doubled, some nitrification

was achieved at the lower combined metal concentration.

14

Sujarittanonta (19) showed that l and 5 mg/l of nickel also

effected an almost complete inhibition of nitrification. As for

COD removal, the COD-to-nickel ratio influenced the toxicity of

nickel on nitrification. In contrast, DiSalvo (20) discovered

substantial nitrificationin reactors fed 0.5 mg/l nickel; in

fact, nitrate production was higher for the nickel-fed reactors

than for the control. (As noted above, the control data used for

comparison was collected during another study (19).) Low pH's

did not hinder nitrification.

METAL UPTAKE

Nickel's behavior in aqueous systems is characteristic of

the heavy metals. These transition elements have unfilled inner

electron shells which make them amenable to coordination with

molecules and anions. In coordinative relationships, the type

and number of coordinative partners may change without change in

the oxidation state of either the metal cation or other species

involved (24).

Formation of a coordinative relationship between a metal

cation and either a molecule or an anion is known as com-

plexation. The participating nolecule or anion is a ligand.

Chelation is a form of complexation where the ligand (or

chelating agent) has multiple bonding sites and forms, with

the cation, a ring structure.

Metal and ligand solubility, pH, and the type and concen-

tration of metals and ligands present determine the distribution

15

of metal species in an aqueous system. The effect of pH on the

theoretical solubility of nickel hydroxide is shown in Figure 1.

A speciation diagram for nickel-amine complexes is shown in

Figure 2. (Calculations for these figures are presented in

Appendix A.)

In activated sludge, the potential for formation of coordi-

native relationships with metals is high. Heavy metals tend to

form stable compounds with carboxyl, hydroxyl, carbonyl, amino,

and sulfur groups. These groups are found in the cells and

cellular products---polysaccharides, lipids, and nucleic acids,

which constitute the biomass of activated sludge. Other che-

lating agents present in wastewater may include NTA (nitrilo-

triacetate); EDTA (ethylenediamine tetraacetate); sodium citrate;

linear chain polyphosphates used for detergent manufacture, water

treatment, metal cleaning, and food processing; humic material,

and amino acids (25).

Many researchers have observed the rate at which heavy

metals were taken up or removed by activated sludge. McDermott

(13) noted that approximately 30 percent of influent nickel was

removed by a complete activated sludge unit. This included a

small amount removed in primary settling. Salotto (12) found

that more copper remained soluble at higher organic loadings. He

suggested that more soluble metal complexes were formed at these

higher loadings.

0

2

4 • N z a.

~

6

7

8

16

Ni(0Hl2a41

0 2 4 6 8 10 12

pH

FIGURE I. THEORETICAL SOLUBILITY OF NICKEL HYDROXIDE.

14

~

z 0

I-<..> ex a: LL.

17

1.0

0.90

0.80

0.70

Ni(NH3)4•2 Ni++

060

0.50

~

0.30

0.20

0.10

0 -2.0 -1.0 0 1.0 2.0 3.0 4.0 5.0 6.0

FIGURE 2. SPECIATION DIAGRAM FOR NICKEL -AMINE COMPLEXES.

7.0

18

Esmond and Petrasek (26) discovered that, regardless of

influent concentration, nickel removal at a 2-MGD pilot plant

operated at a mean cell residence time of 13 days was approxi-

mately 15 parts per billion. This was in contrast to the

removals of other metals, which were removed at a greater rate

as their influent concentrations increased. They inferred that

the sludge had a "fixed demand" for nickel.

In a field study of a 6.5-MGD conventional activated sludge

plant, Oliver and Cosgrove (27) determined that only one percent

of the total nickel and less than one percent of the dissolved

nickel was removed. Removals of most other metals was sub-

stantially higher.

Chen and others (28) reported that secondary treatment at

a 340-MGD activated sludge plant achieved less than 30 to 60

percent removal of total nickel and less than 40 percent of

soluble nickel. Nickel remained in soluble form through the

activated sludge process and was more likely to be associated

with smaller particulates. In this respect, nickel behaved like

lead and manganese, in contrast to other metals studied.

Neufeld and Hermann (29) used sewage cultures acclimated to

sewage feed to assess the effects of shock doses of mercury,

cadmium, and zinc. ~ found that uptake was not dependent on

metal concentration or on organism viability. Some metals seemed

to reach a saturation value, such that the percentage of metal on

the floe at the higher doses was lower than for smaller doses.

19

Cheng and others (30) conducted heavy metals uptake studies

on batch-operated, laboratory-scale activated sludge reactors,

using nickel doses ranging from 2 to 25 mg/l. Results indicated

that uptake of heavy metals took place in two phases. The first

phase was very rapid (3 to 10 minutes); the second, slow and

long-term. Addition of soluble ligands such as ETDA and NTA

interfered with metal uptake by the sludge. Order of uptake

efficiency corresponded to metal solubility, with nickel being

less easily removed than other metals. Uptake of metals was

greater at higher initial concentrations, but the percentage of

uptake was less. Contrary to results for other metals, nickel

uptake in relationship to unit weight of volatile suspended

solids decreased as the volatile suspended solids increased, with

a maximum nickel removal per unit volatile suspended solids of

two percent.

Uptake increased with increasing pH until precipitation

began to occur. Cheng speculated that a high pH environment

favors uptake by reducing the competition between metal cations

and hydrogen ions for binding sites in the biofloc.

Jenkins (31) found that samples of domestic sewage dosed

with 1 to 100 mg/l of nickel precipitated approximately fifty to

sixty percent of the nickel. In contrast to copper, precipi-

tation of nickel was only slightly affected by pH.

Friedman and Dugan (32) studied the uptake of copper and

cobalt by Zoogloea in both growth and non-growth situations,

20

using batch cultures. They found that both cell and surrounding

matrix took up metals which accounted for as much as 34 percent

of total cell weight. Growth or physiological state of the

organism affected the rate of accumulation of metal ions by

cells. Affinity was greater between older cells and metals than

between actively growing cells and metals. The investigators

suggested that this was the result of increased synthesis of

zoogleal material by mature cells and subsequent uptake of ions

by this material.

MECHANISMS OF METAL TOXICITY

It is the coordinative aspects of the physico-chemical

behavior of heavy metals, described above, which are thought to

cause their toxicity. It has been hypothesized that the toxic

effects of heavy metals on activated sludge are caused by form-

ation of complexes between metal cations and enzymes crucial to

respiration in the microorganisms constituting the biomass. Two

types of inhibition are considered relevant: competitive in-

hibition and noncompetitive inhibition.

Competitive inhibition occurs when a compound structurally

similar to the substrate binds to the active site of an enzyme,

thereby preventing substrate utilization. The degree of in-

hibition depends upon the relative concentrations of the sub-

strate and the competing compound. Competitive inhibition is

reversible (33). Increases in organic loading or the addition of

21

preferred ligands or other cations may facilitate the release of

metal cations (25,30,34).

Noncompetitive inhibition occurs when strong covalent bonds

form between an enzyme and a substance, which either block the

active site or contort the physical configuration of the enzyme.

Noncompetitive inhibition is not reversible (33). Heavy metals

may also combine with amino acids and precipitate them as metal-

protein salts.

Poon and Bhayani (35) studied the effects of copper,

chromium, nickel, silver, and zinc on pure cultures of typical

"sewage bacteria," Zoogloea ramigera, and of a poorly settling

fungus, Geotrichium candidum, by measuring oxygen uptake rates

of cultures dosed with from 1 to 100 mg/l heavy metal. Results

were interpreted using the Michaelis-Menten model of enzyme

inhibition. Nickel and silver were found to be most toxic to the

sewage bacteria. Nickel and the other metals produced linear

noncompetitive inhibition in sewage bacteria, and linear com-

petitive inhibition in the fungus. The authors suggested that

this difference in reaction might explain patterns of mixed

inhibition in mixed cultures such as activated sludge.

Adjustments in cell metabolism may account for the ability

of biological systems to acclimate to the presence of heavy

metals. Toxic effects may be mitigated by the replacement of

damaged enzymes, the use of alternate metabolic pathways, or the

development of new pathways (36).

22

The flocculating characteristics of activated sludge also

seem to influence metal toxicity. Pavoni and others (37) found

that bioflocculation occurred in the endogenous growth phase of

microorganisms and proceeded similarly in cultures with different

predominant organisms. Bioflocculation depends upon the accumu-

lation and bonding of exocellular polymers, which consist of

polysaccharide, protein, RNA, and DNA, and have functional

surface groups that are anionic or nonionic at neutral pH's.

These characteristics make them prime coordinative partners for

metal cations.

In a study conducted by Bitton and Freihofer (38), both

cadmium and copper were toxic to both capsulated and non-

capsulated bacteria. But the extracellular polysaccharides

produced by the capsulated bacteria evidently chelated the metal

ions and reduced their toxicity. Dugan and Feister (39) noted,

in a comparison of aerobic waste treatment systems and the

characteristics of lake eutrophication, that the extracellular

polymer fibrils produced by floe-forming bacteria have the

ability to concentrate and accumulate transition metal cations.

When separated, the polymer flocculates the metal and settles

out.

Brown and Lester (40), summarizing work related to the

mechanisms of flocculation with respect to metal removal effic-

iency in activated sludge, reported that the major mechanism of

uptake appears to be physico-chemical interaction or absorption

23

by negatively charged groups present on extracellular polymers.

Absorption depends upon the quantity of polymer, which in turn

depends upon the nutrients available, sludge age, and polymer

oxidation; on the type of polymer (gels absorbing better than

soluble polymers); on the presence of other cations such as

calcium and magnesium, which may be replaced by heavy metals,

and by the possibility of formation of cation-anion matrices in

the floe. Metals may also adsorb to cell walls or accumulate in

cytoplasm.

SUMMARY

With few exceptions (17,18,19,20), metal toxicity studies

have concentrated on evaluating the effects of relatively high

doses of heavy metals, not usually encountered in the field, on

the activated sludge process. At these doses, nitrification has

been severely inhibited. The purpose of the current study was to

continue earlier studies conducted at VPI&SU (19,20), in which

bench-scale reactors were dosed 0.5 and 1 mg/l nickel, in order

to assess the effects on nitrification of varying the COD:TKN

ratio on reactors fed relatively low concentrations of nickel.

liATERIALS AND METHODS

The purpose of this study was to determine the effects of

continuously fed doses of nickel of approximately 0.5 mg/l on the

performance of bench-scale, completely mixed, continuous flow

activated sludge reactors. This study utilized similar operating

parameters, including nickel dose, as earlier work (20) conducted

at VPI&SU, which compared the effects of COD:Ni ratio on perfor-

mance of similar units. This previous study found an apparent

increase in nitrification for metal-fed reactors operated at

COD:TKN ratios of 3.7:1 when compared to a control unit operated

under similar conditions (19). The current study held nickel and

COD concentrations constant, and varied influent nitrogen concen-

trations in order to assess the effect of the COD:TKN ratio on

performance. Of particular interest were the effects of nickel

on the process of nitrification.

In this study, three bench-scale, completely mixed, con-

tinuous flow activated sludge reactors were operated over a

period of eight months, from March to November, 1980. Two

reactors received 0.5 mg/l concentrations of nickel as Ni(II),

while the third reactor received no nickel and served as a

control unit. All reactors were fed a soluble, synthetic waste-

water with 400 mg/l influent COD. One nickel-fed reactor and the

control reactor were operated at an influent COD:TKN ratio of

2.4:1, while the other nickel-fed reactor was operated at an

influent COD:TKN ratio of 7.3:1.

24

25

As in previous studies of the effects of nickel on activated

sludge conducted at VPI&SU, mean cell residence time was varied

to produce comparable sets of data. All reactors were operated

at a hydraulic detention time of 14 hours, at an ambient temper-

ature of 20° ± 1° C.

LABORATORY APPARATUS

A schematic diagram of the laboratory apparatus used in this

study is shown in Figure 3. Each plexiglass unit consisted of a

6.0-liter aeration tank and a 2.5-liter settling tank, separated

by a sliding baffle. Compressed air, filtered through glass

wool, was released into the aeration tank through two porous

diffuser stones. Sufficient air was introduced into the reactor

to maintain a dissolved oxygen concentration above 2.0 mg/l.

Adjustment of the baffle height, the flow of compressed air,

and the position of the diffuser stones was made to provide the

following:

a. continuous and thorough mixing of the contents of

the aeration tank,

b. quiescent conditions for optimum settling in the

settling tank, and

c. constant exchange of solids beneath the baffle

between tanks.

In practice, these conditions were achieved by adjusting the

baffle between tanks so that it imparted a rolling motion to the

contents of the aeration tank, and by raising or lowering the

ADJUSTABLE BAFFLE

CALIBRATED

EFFLUENT eOLLECTION

~ ~ TANK

26

p

FEED PUMP

CALIBRATED FEED TANK

COTTON AIR Fil TER

2 DIFFUSER STONES

AERATION TANK

SETTLING TANK

FIGURE 3. EXPERIMENTAL COMPLETELY MIXED

ACTIVATED SLU OGE UNIT.

27

baffle to obtain a well-mixed, aerated sludge blanket with a

well-defined interface in the settling tank.

Each reactor received 14.5 liters of feed solution per day,

pumped continuously from a 19-liter Nalgene carboy through Tygon

tubing to the reactor by a Durrum Instrument Corporation positive

displacement pump (Model 12AP Dial-a-Pump). Feed carboys and

feed lines were rinsed daily with a mild chlorine solution to rid

them of any microorganisms which might consume feed nutrients

before they reached the reactor, thereby reducing the strength

of the feed.

Effluent from each reactor was collected in a 19-liter

Nalgene carboy.

STARTUP

During the course of this study, three bench-scale, com-

pletely mixed, continuous flow activated sludge reactors were

operated over a period of eight months. The study began in

December, 1979, when the initial activated sludge culture was

obtained from a continuous flow reactor operated by another

student. Two liters of sludge was transferred to an aerated

2-gallon glass jar, which served as a batch reactor unit, and

diluted with tap water to 5 liters. The sludge had been

acclimated to a feed similar in composition to the feed used in

this study, except that bacto-peptone was to replace jack bean

meal as the organic nutrient source. After transfer, the sludge

in the batch reactor was fed a mixture of jack bean meal and the

28

bacto-peptone. The proportion of bacto-peptone to jack bean meal

was gradually increased until the organic feed consisted entirely

of bacto-peptone.

At the end of December, the batch culture was seeded with

500 mls of settled solids from activated sludge obtained from

the nitrification basin sludge return lines at the Roanoke Water

Pollution Control Facility, Roanoke, Virginia.

Attempts to start continuous flow reactors in January and

February, 1980, were hindered by faulty pump operation. In

March, the first continuous flow reactor was started up with 2.5

liters of sludge transferred from the batch reactor and diluted

with tap water to 8.5 liters. The reactor was operated at a

COD:TKN ratio of 3.7:1, with no supplemental ammonia being added.

Beginning at this time, the sludge was fed continuous doses of

nickel. The dosage was increased over a period of two weeks

until the desired Ni(II) concentration of 0.5 mg/l was reached.

Two weeks after startup of the first unit, 4 liters of

completely mixed sludge was transferred from the first continuous

flow reactor to a second. Tap water was added to each reactor to

bring the total volume of each to 8.5 liters. The second con-

tinuous flow reactor was operated at a COD:TKN ratio of 2.4:1.

It continued to receive 0.5 mg/l nickel. On the same ~ 2.5

liters of completely mixed activated sludge were transferred from

the batch reactor to another 2-gallon aerated glass jar. Tap

29

water was added to each to bring the total volume of each to 5

liters.

A week later, the entire contents of one of these batch

reactors were transferred to a third continuous flow reactor.

Tap water was added to bring the total volume of the reactor to

8.5 liters. The third continuous flow reactor was operated at a

COD:TKN ratio of 2.4:1 and received no nickel, as it was to serve

as the control.

Within a week, the contents of the control reactor turned

bright pink. Microscopic examination of the culture revealed

that it was infested with small worms. The contents of the

reactor were disposed and 2.5 liters of mixed liquor transferred

from the batch reactor to the continuous reactor. The contents

of the reactor were again diluted with tap water to a volume of

8.5 liters, and feeding and wasting resumed.

For the last run of the control reactor, the culture was

seeded with an additional 2 liters of settled solids from the

nitrification basin sludge return lines at the Roanoke Water

Pollution Control Facility. The purpose of reseeding was to

increase the solids concentration of the reactor in order to

achieve a relatively high mean cell residence time in a short

period of time.

DAILY PROTOCOL

Each day, a 16-liter feed solution was prepared from the

components listed in Table II for each reactor, and a calculated

30

TABLE II

COMPOSITION OF WASTEWATER FEED SOLUTION

Stock Quantity Concentration Used Per Final Per 2 Liters 16 Liters Concentration

Constituent (gm) (ml) (mg/1)

Bacto-Peptone (nutrient broth) 64.5* 87.5 353

MgS04 7H20 20.0 80.0 50.0

MnS04 H20 2.00 80.0 5.00

FeC13 6H 20 0.25 80.0 0.63

CaC12 1.50 80.0 3.75

(NH4) 2so4 200 85.4 variable **

KH 2Po4 *** 105 107.0 349

K2HP04 *** 214 107.0 716

NiC12 6H 2) 8.10 8.00 2.03 [Ni(II)] = 0.50

* Prepared in one liter stock solutions (Nominal COD of waste 400 mg/1)

**One nickel-fed reactor received no (NH4) 2so4 . The other nickel-fed reactor and the control received 534 mg/l (NH4) 2so4 for an [NH4-N] = 56 mg/l

*** Phosphate buffer solution

31

amount of completely mixed solids wasted from the reactor. When

a reactor reached steady state at the desired mean cell residence

time, the parameters listed in Table III were monitored daily.

Daily protocol proceeded as follows:

a. The feed pump was stopped and the feed line removed from

the reactor and from the feed carboy. The effluent port of the

settling tank was plugged, and the baffle separating the aeration

tank and the settling tank removed, allowing the contents of the

reactor to mix completely. The feed carboy was rinsed once with

a mild chlorine solution (15 mls bleach in 8 liters tap water)

and then four times with tap water.

b. The correct amounts of stock feed solutions listed in

Table II were added to the feed carboy, and diluted with tap

water to 16 liters in order to achieve the concentrations listed

in Table II. The feed carboy was vigorously shaken to ensure

complete mixing of the feed components and tap water, and thus

the homogeneity of the feed solution.

c. While the feed solution was allowed to equilibrate,

samples of the effluent were taken. The effluent carboy was

first capped and vigorously shaken to completely nix its con-

tents. Then 50 mls of sample, pipetted from the carboy, were

transferred to an acid-washed Nnlgene bottle and acidified with

concentrated nitric acid to a pH below 2.0, and reserved for

Ni(II) analysis. Another 450 mls were filtered through a

Millipore filter apparatus. Of this filtered sample, 200 mls

32

TABLE III

PARAMETERS MONITORED DURING STEADY STATE PERIODS

Sample

Influent Feed

Unfiltered Effluent

Filtered Effluent

Reactor

Parameters Monitored

Chemical Oxygen Demand Ammonia Nitrogen Concentration Total Kjeldahl Nitrogen Concentration Nickel Concentration pH Alkalinity as Caco3 Nitrate Nitrogen Concentration

Nickel Concentration Suspended Solids Concentration

Chemical Oxygen Demand Ammonia Nitrogen Concentration Total Kjeldahl Nitrogen Concentration Nickel Concentration Nitrate Nitrogen Concentration pH Alkalinity as Caco3

Mixed Liquor Suspended Solids

33

were used for immediate pH and alkalinity measurements; 50 mls

were transferred to an acid-washed Nalgene bottle and acidified

as described above, and 300 mls were transferred to another

acid-washed Nalgene bottle, acidifed with concentrated sulfuric

acid to a pH below 2.0, and stored at 4°C for subsequent

analyses.

d. After effluent sampling was completed, wasting was

accomplished by pumping from the reactor a calculated amount of

completely mixed sludge with a Fisher Scientific Manostat Vari-

staltic pump (Solid State Model). The sludge was then poured

from the graduated cylinder in which it was collected into a

beaker, whose contents were kept completely mixed by a magnetic

stir bar. A sample was withdrawn, filtered through a Millipore

filter apparatus, and the Reeve-Angel 0.45-µ filter retrieved and

analyzed for suspended solids.

e. Samples of the feed solution were then taken. The feed

carboy was capped and vigorously shaken to completely mix its

contents. Filtration was not necessary, as all feed components

were soluble. Therefore, only one sample was taken for Ni(II)

analysis. Otherwise, influent sampling proceeded exactly as

effluent sampling.

f. Following sampling, the feed lines were returned to the

reactor and the feed carboy, and the feed pump was started.

34

Daily wasting rates were initially based on the previous

day's solids concentrations in the reactor and in the effluent

and calculated to achieve the desired mean cell residence time

a~ d to the equation:

where

8 c

e c

vx Q X+(Q-0 )X w 'w e

mean cell residence time, days

V volume of reactor, liters

X mixed liquor suspended solids, mg/l

Qw wasting rate, liters/day

Q flow rate, liters/day

X suspended solids in the effluent, mg/l. e

[ 3]

The results obtained by this method, however, were erratic.

Starting in May, wasting rates were calculated using the esti-

mation of mean cell residence time:

[4]

where the parameters are as described above (Equation 3).

TECHNIQUES OF ANALYSIS

Parameters listed in Table III were tested according to the

following procedures.

35

Solids

Mixed liquor suspended solids taken from the completely

mixed contents of the aeration and settling tanks and effluent

suspended solids were measured according to the procedures for

determining "Total Filtrable Residue Dried at 103-105°C", as

described in Standard Methods for the Examination of Water and

Wastewater (Standard Methods) (41), Test 208B. Reeve-Angel

5.5-cm glass-fiber filters (0.45 micron pore size) were used in

filtering solids through a Millipore filter apparatus. Solids

were weighed on a Mettler Instrument Corporation balance

(Model HlO).

Chemical Oxygen Demand, COD

The soluble COD concentration of the influent and the

filtered effluent was determined by analyzing preserved samples

as described in Standard Methods (41), Test 508.

Ammonia Nitrogen, NH3-N

The NH3-N concentration of the influent and the filtered

effluent was determined by distilling preserved samples and then

analyzing the samples according to the procedure for the "Acidi-

metric Titration Technique," as described in Standard Methods

(41), Test 418D.

Total Kjehdahl Nitrogen, TKN

The TKN concentration of the influent and the filtered

effluent was determined by first digesting and distilling

36

preserved samples according to the procedure for determining

organic nitrogen, and then analyzing samples using the

"Acidimetric Titration Technique," as described in Standard

Methods (41), Test 421.

Nitrate Nitrogen, N03-N

The N03-N concentration of the influent and the filtered

effluent was determined using the "Brucine Method" as described

in Standard Methods (41), Test 4190. Prepared samples were

analyzed on a Bausch & Lomb Spectronic 100 spectrophotometer.

The pH of the influent and the unfiltered effluent was taken

immediately upon sample collection with a Fischer Accumet pH

meter (Model 120).

Alkalinity as Caco3

Alkalinity of the influent and the unfiltered effluent was

determined immediately upon sample collection according to the

procedure outlined in Standard Methods (41), Test 403. The end

point pH during titration was taken as 5.1.

Nickel, Ni(II)

Ni(II) concentration of the influent and both filtered and

unfiltered effluent was determined by atomic absorption spectro-

photometry, using a Perkin Elmer 403 atomic absorption

37

spectrophotometer. Unfiltered samples were first digested

according to the instructions for "Sample Pretreatment of Total

Metal Analysis" set forth in Standard Methods (41), Method 301C.

DATA ANALYSIS

The following equations were used to evaluate degree of

treatment efficiency and nitrification, and to determine specific

growth and utilization rates and the biokinetic yield and decay

coefficients over a range of mean cell residence times.

where

The soluble removal efficiency is:

E s

s -s o e s

0

(100)

E soluble COD removal efficiency, percent s S influent soluble COD, mg/l

0

S = effluent soluble COD, mg/l e

To calculate percentage effluent ammonia:

where

100(NH3-Neff) TKN

[ s]

[6]

percentage of influent nitrogen exiting as

ammonia nitrogen, percent

NH3-Neff = effluent ammonia concentration, mg/l

38

TKN influent total Kjeldahl nitrogen concentration,

mg/l

To calculate percentage synthesized nitrogen:

where

% Synthesized Nitrogen lOO(TKN-(TKNeff+N03-Neff))

TKN

% Synthesized Nitrogen = percentage of influent total

kjeldahl nitrogen synthesized, percent

TKN influent total Kjeldahl nitrogen, mg/l

TKNeff effluent total kjeldahl nitrogen, mg/l

N03-Neff effluent nitrate nitrogen, mg/l

To calculate percentage nitrate:

where

100(N03-Neff) TKN [8]

percentage of influent nitrogen exiting as

nitrate nitrogen, mg/l

N0 3-Neff = effluent nitrate nitrogen, mg/l

and TKN is as defined above (Equation 7).

[ 7]

The specific growth rate was calculated by inverting the

mean cell residence time:

µ [ 9]

where

39

-1 µ specific growth rate, days

8 = mean cell residence time, days c

The specific utilization a ~ was calculated by:

where

u

G

u s -s o e

X8

-1 specific utilization rate, days

hydraulic detention time, days

X = mixed liquor suspended solids, mg/l

and S and S are defined above (Equation 5). o e

[ 10]

Biokinetic coefficients were determined from correlation

of specific utilization and specific growth rate, as shown in

Figure 7. This relationship is:

where

1 =

9 c

y max

1 Y U-k max d e

c

-1 specific growth rate, days

-1 maximum cell yield, days

-1 decay coefficient, days

and U is as defined above (Equation 8).

The observed yield coefficient is calculated by:

y obs

[11]

[12]

where

40

Yobs observed yield coefficient, days-l

Sc mean cell residence time, days

and other parameters are as defined above (Equation 12).

RESULTS

The purpose of this study was to determine the effects of

a small soluble dose of nickel on bench-scale, continuous flow

activated sludge units operated at various mean cell residence

times (MCRT's). The effects of nickel on nitrification were of

particular interest. Influent ammonia concentration was varied

to assess the influence of nitrogen concentration on the degree

of nitrification in the presence of nickel. Pertinent data were

collected to determine the degree of nitrification at each MCRT,

as well as to permit evaluation of organic removal rates, bio-

kinetic coefficients, and nickel removal.

The COD:TKN ratios and nickel doses for the five reactors

discussed in this study are given in Table IV. Raw data for all

reactors are presented in Appendix B.

Three of these reactors (Reactors I, II, and IV) were

operated during the course of the study, each brought to steady

state at four mean cell residence times. All reactors received

a synthetic, soluble feed with a COD of approximately 400 mg/l.

Data from two separate, earlier studies have been included

for comparison. These studies used sinilar bench-scale units

and amassed the same types of data. These reactors (Reactors II

and V) also received 400 mg/l influent COD.

Reactor I was operated at a COD:TKN ratio of 2.4:1 and

served as the control unit. It was operated at four mean cell

residence times from 5.6 to 18.1 days. Total influent nitrogen

41

42

TABLE IV

COD:TKN RATIOS AND NICKEL DOSES

Influent Influent Reactor COD:TKN Ratio Nickel Dose, mg/1

I 2.4:1

II 2.4:1 0.56

III 3.7:1 0.58

IV 7.3:1 0.54

v 3.7:1 0.97

43

was 166 mg/l, with approximately 61 mg/l organic nitrogen and

the remainder ammonia nitrogen. Control data are presented in

Table V.

Reactor II was fed 0.56 mg/l total nickel and a total

nitrogen concentration of 166 mg/l, constituted by about 60 mg/l

organic nitrogen and 106 mg/l ammonia nitrogen, for a COD:TKN

ratio of 2.4:1, identical to the control. It was operated at

four mean cell residence times, from 4.2 to 14.0 days. Data

collected from this reactor are presented in Table VI.

Reactor III received 0.58 mg/l nickel and 110 mg/l total

influent nitrogen for a COD:TKN ratio of 3.7:1. Approximately

half the influent nitrogen was contributed by ammonia and half

by organic sources. Reactor III was operated at three mean cell

residence times, from 6.0 to 12.0 days. Data for this reactor

are presented in Table VII (20).

Reactor IV received 0.54 mg/l nickel and 55 mg/l total

influent nitrogen, all of it organic, for a COD:TKN ratio of

7.3:1. Mean cell residence times varied from 5.2 to 15.0 days.

Data for this reactor are presented in Table VIII.

Reactor V was fed 0.97 mg/l nickel and, as Reactor III, half

ammonia nitrogen and half organic nitrogen, for a total influent

nitrogen concentration of 106 mg/l. COD:TKN ratio was 3.7:1.

Mean cell residence times varied from 5.2 to 14.5 days. Data

from this reactor are presented in Table IX (19).

44

TABLE V SUMMARY OF STEADY STATE DATA - REACTOR I

COD:TKN = 2.4:1, Ni(II) = 0.02 mg/l

Mean Cell Residence Time, days Parameter

COD Feed, mg/l Effluent, mg/l (1) Net Change, %

Reactor Solids Reactor, mg/l Effluent, mg/l

Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %

Organic Nitrogen, Feed, mg/1 Effluent, mg/1 Net Change, %

NH -N r-::-(1)

Org-N

(1)

Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)

£!! Feed Effluent

Alkalinity as Caco3 Feed, mg/l Effluent, mg/1 Net Change, %

Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l

-1 Observed Yield, day -1 Specific Growth Rate, day

-1 Specific Utilization Rate, day

Wasting Rate, l/day

(l)filtered

5.6 8.1 9.7 18.1

377 26

93.1

1427 87

103 87

-15.1

63 2

97.6

0.50 86

7.1 6.3

428 125

-70.9

0.02 0.04 0.02

0.334

0.179

0.420

o. 710

396 38

90.3

1304 64

112 85

-23.9

56 3

94.0

a.so 77

7.0 6.0

440 104

-76.3

0.02 0.04 0.03

0.323

0.124

0.468

0.530

401 37

90.7

1634 49

95 77

-14.5

63 5

92.0

0.90 82

7.1 5.7

428 35

-91.8

0.02 0.04 0.03

0.316

0.104

0.380

0.475

358 28

92.2

2650 71

111 107

-3.7

61 3

95.8

0.40 56

7.1 6.6

474 267

-43.8

0.03 0.14 0.01

0.285

0.055

0.212

0.100

45

TABLE VI SUM¥.ARY OF STEADY STATE DATA - REACTOR II

COD:TKN = 2.4:1, Ni(II) = 0.56 mg/l Mean Cell Residence Time, days

Parameter COD --Feed, mg/l

Effluent, mg/l (1) Net Change, %

Reactor Solids Reactor, mg/l Effluent, mg/l

Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %

Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %

NH -N 3-

(1)

Org-N

( 1)

Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)

£!! Feed Effluent

Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %

Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l Removal, %

-1 Observed Yield, day -1 Specific Growth Rate, day

-1 Specific Utilization Rate, day

Wasting Rate, l/day (l)filtered

4.2 7.8 11.9 14.0

368 34

90.5

728 52

91 151

+70.2

51 2

95.7

0.50 5

7.0 7.2

397 566

+43.3

0.62 0.49 0.47 20.6

0.305

0.239

0.783

1.075

401 31

92.2

1596 46

105 84

-20.6

58 4

94.1

0.60 76

7.1 6.0

429 77

-82.0

0.55 a.so 0.28 27.8

0.305

0.128

0.395

o. 710

410 41

89.3

2405 33

109 73

-34.0

64 2

96. 9

0.70 89

7.2 4.9

461 1

-99.8

0.55 0.48 0.48 11.3

0.305

0.084

0.262

0.530

411 28

93.2

2625 25

119 76

-36.6

59 1

99.2

0.60 97

7.2 5.1

462 0

-100

0.53

0.51

0.305

0.071

0.249

0.475

46

TABLE VII SUMMARY OF STEADY STATE DATA -REACTOR III COD:TKN = 3.7:1, Ni(II) = 0.58 mg/l

Mean Cell Residence Time, days Parameter

COD Feed, mg/l Effluent, mg/l (1) Net Change, %

Reactor Solids Reactor, mg/l Effluent, mg/l

Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %

Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %

NH -N r-::-

(1)

Org-N

(1)

Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)

.E!! Feed Effluent

Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %

Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l Removal, %

-1 Observed Yield, day

-1 Specific Growth Rate, day

-1 Specific Utilization Rate, day

~a Rate, l/day

(l)filtered

6. 0 8. 9 12. 0

412 57

86.2

1258 39

55 61

+9.9

55 4

92.4

36

7.0 6.6

254 145 -42. 9

0.59 0.56 0.55 6.8

0.34

0.167

0.486

1.000

401 36

90.9

1721 30

56 45

-18.7

57 5

91. 7

57

7.0 5.6

255 23

-91.0

0.55 0.50 0.48 12.7

0.31

0.112

0.365

o. 725

418 37 91.2

2158 26

56 43

-23.5

54 4

92.0

61

7.0 5.3

250 10

-96.0

0.60 0.60 0.60 0

0.27

0.083

0.304

0.540

47

TABLE VIII SUMMARY OF STEADY STATE DATA - REACTOR IV

COD:TKN = 7.3:1, Ni(II) = 0.54 mg/l Mean Cell Residence Time, days

Parameter COD --Feed, mg/l

Effluent, mg/l (1) Net Change, %

Reactor Solids Reactor, mg/l Effluent, mg/l

Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %

Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %

NH -N ~

(1)

Org-N

( 1)

Nitrate Nitrogen, N0 3-N Feed, mg/l Effluent, mg/l (1)

E!! Feed Effluent

Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %

Nickel, Ni (II) Feed, mg/l Effluent, total, mg/l Effluent, soluble, mg/l Removal, %

-1 Observed Yield, day -1 Specific Growth Rate, day

-1 Specific Utilization Rate, day

Wasting Rate, l/day (l)filtered

5.2 7.2 13.5 15.0

396 35

91.2

994 43

0.1 35

+100

54 4

91. 9

0.60 2

7.0 7.6

241 378

+57.9

0.55 0.51 0.44 10.9

0.291

0.193

0.620

1.075

411 57

84.0

1086 36

0.3 30

+100

55 10

81.0

0.60 17

7.0 7.3

247 328

+32.5

0.53 0.40 0.34 24.9

0.273

0.139

0.556

o. 710

423 29

93.0

1942 15

0 0 0

57 2

95.8

0.60 53

7.1 6.4

242 84

-65.4

0.54 0.36 0.32 34.8

0.227

0.074

0.346

0.530

400 9

97.6

2363 16

0 0.3

60 3

95.4

0.50 53

7.2 6.6

253 112

-55.6

0.53 o.so 0.46 6.9

0.218

0.067

0.282

0.475

48

TABLE IX SUMMARY OF STEADY STATE DATA - REACTOR V

COD:TKN = 3.7:1, Ni(II) = 0.97 mg/l

Parameter COD Feed, mg/l

Effluent, mg/l (1) Net Change, %

Reactor Solids Reactor, mg/l Effluent, mg/l

Ammonia Nitrogen, Feed, mg/l Effluent, mg/l Net Change %

Organic Nitrogen, Feed, mg/l Effluent, mg/l Net Change, %

NH -N r-:: (1)

Org-N

(1)

Nitrate Nitrogen, N03-N Feed, mg/l Effluent, mg/l (1)

~ Feed Effluent

Alkalinity as Caco3 Feed, mg/l Effluent, mg/l Net Change, %

Nickel, Ni (II) Feed, mg/l Effluent, total, ng/l Effluent, soluble, mg/l Removal, %

-1 Observed Yield, day -1 Specific Growth Rate, day

-1 Specific Utilization Rate, day

Wasting Rate, l/day (l)filtered

Mean Cell Residence Time, days 5.2 10.6 14.5

394 25

93.7

1106 29

56 86

+53.6

53 3

94.1

1.4

7.2 7.7

241 337

+40.1

0.99

0.92 7.1

0.334

0.192

0.572

1. 250

396 29

92.7

1475 11

57 89

+56.1

51 4

91.9

1. 7

7.1 7.6

232 354

+52.7

1.0

0.86 14.0

0.227

0.094

0.427

0.700

399 33

91. 7

1716 11

49 85

+73.5

53 8

84.6

1.6

7.0 7.6

233 360

+51.8

0.93

0.85 8.6

0.184

0.069

0.366

0.500

49

TREATMENT EFFICIENCY

Influent and effluent COD, influent and effluent ammonia,

TKN, and organic nitrogen, and other parameters were analyzed so

that common expressions of treatment efficiency could be calcu-

lated. These included COD removal efficiency, ·degree of nitrifi-

cation, and the biokinetic growth and utilization rates. Effluent

suspended solids were also measured as an indication of treatment

efficiency.

COD Removal

Reactor I. For all HCRT's, COD removal exceeded 90 percent,

for influent COD's averaging 383 mg/l. Small changes in removal

efficiency were not related to mean cell residence time. Average

effluent COD levels were maintained between 26 and 38 mg/l.

Reactor II. COD·removal efficiency varied from 89 to 93 percent

for influent COD's averaging 398 mg/l. Average effluent COD's

ranged from 31 to 41 mg/l.

Reactor III. An average of 86 to 91 percent of the influent COD

of 407 mg/l was removed. Average effluent COD values ranged from

36 to 57 mg/l.

Reactor IV. Net change in COD varied from 84 to 98 percent, for

an average influent COD of 408 mg/l. Effluent COD's ranged from

9 to 57 mg/l.

Reactor V. Influent COD, which averaged 396 mg/l, was reduced to

25 to 33 mg/l, with all MCRT's showing good removals.

50

Reactor Solids, Effluent Suspended Solids, and Biokinetic Coefficients

Reactor I. Reactor solids were maintained at 1427, 1304, 1634,

and 2650 mg/l for MCRT's of 5.6, 8.1, 9.7, and 18.1 days, re-

spectively. Effluent suspended solids ranged from 49 to 87 mg/l

on the average, with daily values rising as high as 204 mg/l.

The observed yield and the specific growth rate declined with

increasing MCRT. Specific utilization rate was erratic.

Reactor II. Reactor solids were held at 728, 1596, 2405, and

2625 mg/l to achieve MCRT's of 4.2, 7.8, 11.9, and 14.0 days.

Effluent solids ranged from 25 to 52 mg/l. Observed yield was

maintained at a relatively constant level throughout the study.

The specific growth rate and the specific utilization rate

declined as MCRT increased.

Reactor III. MCRT's of 6.0, 8.9, and 12.0 days were maintained,

with average reactor solids of 1258, 1721, and 2158 mg/l,

respectively. Effluent suspended solids measured from 26 to

39 mg/l.

Reactor IV. Reactor solids were 994, 1086, 1942, and 2363 mg/l

for MCRT's of 5.2, 7.2, 13.5, and 15.0 days, respectively.

Average removal of suspended d~ was quite high at higher

MCRT's, with effluent suspended solids averaging 15 to 16 mg/l.

At lower MCRT's, effluent suspended solids varied from 36 to

43 mg/l. Observed yield, specific growth rate, and specific

utilization rate declined as MCRT increased.

51

Reactor V. Reactor suspended solids were 1106, 1475, and

1716 mg/l for MCRT's of 5.2, 10.6, and 14.5 days, respectively.

Effluent suspended solids were low, ranging from 11 to 29 mg/l.

Observed yield, specific growth rate, and specific utilization

rate declined with increasing MCRT.

Nitrification

Reactor I. Net changes in ammonia concentration varied from a

3.7 to 23.9 percent decrease, while organic nitrogen was almost

completely destroyed at each MCRT. Nitrate was produced at each

MCRT, with effluent nitrate concentration varying from 56 to

86 mg/l. Effluent ammonia and nitrate concentrations were

erratic.

The pH of the reactor dropped at all MCRT's, as alkalinity

was destroyed. Changes in alkalinity did not correspond well to

either ammonia and organic nitrogen destruction or to nitrate

production.

Reactor II. Disappearance of organic nitrogen was virtually

total at all MCRT's. Nitrate production increased with in-

creasing MCRT to a maximum of 97 mg/l.

Alkalinity was produced at a MCRT of 4.2 days, but at all

other times, alkalinity was destroyed. Alkalinity destruction

was complete at 13.1 days. The pH correspondingly rose at 4.2

days from 7.0 to 7.2, and dropped at other MCRT's to a low of 5.1

at 14.0 days.

52

Reactor Ill. As for Reactor II, ammonia concentration increased

at the low MCRT, and then decreased with increasing MCRT. Organic

nitrogen removals were about 92 percent throughout the study.

Effluent nitrate increased from 36 to 61 mg/l.

Alkalinity destruction was evident at all MCRT's. As

alkalinity decreased, so did pH, to a low of 5.3 at a MCRT of

12.0 days.

Reactor IV. Ammonia was produced at the two lower MCRT's,and

destroyed at the two higher. Organic nitrogen was reduced at

all MCRT's, from 81 to 96 percent. Effluent nitrate production

occurred at all MCRT's, increasing from a minimum of 2 mg/l

at the lowest MCRT of 5.2 days to SJ mg/l at the two higher.

Reactor V. Organic nitrogen was destroyed and ammonia produced

at each MCRT. Nitrate production was practically absent, with

effluent nitrate concentration averaging 1.6 mg/l.

Alkalinity was produced at all MCRT's, and pH of the

effluent rose to 7.6 and 7.7.

Nickel Removal

For Reactors 11 and IV, nickel was removed at all MCRT's,

but at varying levels. Nickel removal for Reactor Ill was

slight, with no nickel removal occurring at 12.0 days. Nickel

removal for Reactor V averaged 10 percent over the course of the

study.

DISCUSSION

TREATMENT EFFICIENCY

As in previous studies (19,20), the effect of nickel on

degree of treatment efficiency, as measured by COD removal,

effluent suspended solids concentration, and, in particular,

nitrate production, of the activated sludge process was of

primary interest. Evaluation of common parameters, such as

influent and effluent COD, reactor suspended solids concen-

tration, and hydraulic detention and mean cell residence times

(MCRT), also permitted determination of specific growth and

substrate utilization rates, which, in turn, were used to cal-

culate biokinetic yield and decay coefficients for each reactor.

COD Removal Efficiency

COD removal efficiency was good to excellent for all five

reactors, as can be seen from Figure 4, which shows COD removal

efficiency vs. mean cell residence time. Efficiency was not

impaired even at the highest nickel dose of 0.97 mg/l. Differ-

ences in efficiency did not relate to COD:TKN ratio or to nickel

dose. Nor did they relate to MCRT, although the two lowest

removal rates occurred at MCRT's less than 8 days, and the

highest at 15.0 days.

These results support earlier findings (13), which

also showed little or no change in removal efficiencies for

reactors dosed at similar nickel concentrations. They tend

53

54

FIGURE 4. COD REiwlOVAL EFFICIENCY vs. MEAN CELL RESIDENCE.

SS

to substantiate the hypothesis that the threshold concentration

for nickel toxicity, as judged by COD removal efficiency, is

equal to, or greater than, 1 mg/l.

Reactor Solids, Effluent Suspended Solids, and Biokinetic Coefficients

Total mixed liquor suspended solids increased with mean cell

residence time for all reactors, as shown in Figure S. Reactor

solids concentrations were consistently lower for Reactor V, with

a 0.97 mg/l nickel dose, than for Reactor III, fed the same

COD:TKN ratio, but half the nickel concentration. As discussed

above, both these reactors showed good to excellent COD removal.

Toxic effects on the heterotrophic community are thus apparent at

nickel doses below those necessary to affect degree of treatment.

Reactor solids concentrations were also dependent on COD:TKN

ratio at moderate to high MCRT's, as evidenced by Reactors II,

III, and IV. Fed approximately the same nickel dose as Reactor

IV, but two and three times the influent nitrogen concentration,

respectively, Reactors II and III carried proportionately greater

solids concentrations. At low MCRT's, influent nitrogen concen-

tration for Reactor IV was sufficient to support solids concen-

trations similar to those of the other reactors, fed greater

influent nitrogen.

At moderate to high MCRT's, Reactors II and III carried

higher solids concentrations than Reactor I, the control, which

was fed equal and greater influent nitrogen. This reactor showed

(/) 0 ...J 0

5000

2500

(/) 2000 0 UJ 0 z ~ 1500 (/) ::> (/)

~ 1000 ::> 0 ...J

~ 500 x :i;:

0 0 2

56

4 6 8 10 12

0 REACTOR I /;:, REACTOR lI. 0 REACTOR m 0 REACTOR N 0 REACTOR 1L

14 16

ec, MEAN CELL RESIDENCE TIME I DAYS

FIGURE 5. TOTAL MIXED LIQUOR SUSPENDED SOLIDS vs. MEAN CELL RESIDENCE TIME.

18

57

erratic increase in reactor solids over the range of MCRT's. In

part, this departure from the ordered relationship among Reactors

II, III, and IV was caused by the loss of solids over Reactor I's

weir, as the sludge tended to bulk at higher MCRT's. It is also

possible that the solids in Reactors II and III had accumulated

nickel to the degree that reactor solids were measurably in-

creased, as compared to Reactor I, by the added weight of the

nickel. Given the small quantities of nickel applied to the

reactor, removal rates, and the relatively short duration of the

study, this could account for only a very small increase (<40

mg/l, had removal been complete.)

All reactors, except Reactor I, produced a fairly clear

effluent over the range of MCRT's. Effluent suspended solids

decreased as MCRT increased. Nickel visibly improved settling,

with nickel-fed Reactors II and IV having fine, dense, rapidly

settling sludge in the settling tank of the bench-scale unit.

The control, on the other hand, frequently spilled large masses

of floating solids, driving daily average suspended solids above

200 mg/l. Effluent suspended solids for this reactor were higher

at all MCRT's than for any other reactor. From this evidence, as

well as from the lower-than-expected reactor solids found in this

unit, it is surmised that the control may have been infested with

~ type of Microorganisms, inhibited by even low doses of

nickel, which adversely affected process performance.

58

Alternatively, poor settling may have been caused by inefficient

reactor design (42).

Figure 6 shows the specific substrate utilization rate vs.

mean cell residence time for all reactors. The specific sub-

strate utilization rate, which is a measure of the amount of COD

removed per day per unit weight of microbial mass, decreased with

MCRT for all reactors. This is an obvious result of the main-

tenance of consistent COD removal rates, while reactor solids

increased with MCRT. At higher mean cell residence times and

reactor solids concentrations, each microorganism consumes less

organic matter, as there is proportionately less available. The

relative specific utilization rates of the five reactors differed

simply with reactor solids concentrations, as discussed above.

Figure 7 shows specific growth rate as a function of

specific utilization rate for all reactors. The biokinetic yield

coefficient, Y , and decay coefficient, kd, were determined max

from the coordinates plotted on this graph by linear regression,

and these values are presented in Table X. The yield coefficient

is the maximum microbial mass produced per day per unit mass of

substrate used, while the decay coefficient is a measure of

endogenous decay. The decay coefficient is used to account for

the fact that not all cells are dividing at a maximum rate,

dependent only on generation time and maximum utilization rate

(42). Endogenous decay is the metabolism of protoplasm by

microbial cells when substrate availability is limited.

1.0

090

0.80

-I (/) >- 0.70 <t 0 -w .....

0.60 <t a:: z 0 ..... 0.50 <t N ..J ..... 0.40 :::> (.)

LL (.) 0.30 w a.. VI -:::> 0.20

0.10

0 0

0 REACTOR I t:::. REACTOR n 0 REACTOR m 0 REACTOR DZ 0 REACTOR 1Z:

2 4 6

59

8 10 12

9c, MEAN CELL RESIDENCE TIME 1 DAYS

14 16

FIGURE 6. SPECIFIC UTILIZATION RATE vs. MEAN CELL RESIDENCE TIME.

18

0.35

- 0.30 I

en >-<t 0 0.25 w I-<t a:: 0.20 :E: I-3:: 0 0.15 a: c:> (.)

LL.

u 0.10 w Cl. en . u 0.05 g_

0

60

0 REACTOR I

6 REACTOR 1I

0 REACTOR m 0 REACTOR Ill

0 REACTOR 1Z

0 0.10 020 0.30 040 0.50 0.60 0.70 0.80 0.90

U, SPECIFIC UTILIZATION RATE, DAYS- 1

FIGURE 7. SPECIFIC GROWTH RATE vs. SPECIFIC UTILIZATION RATE.

1.00

61

TABLE X

BIOKINETIC COEFFICIENTS

Correlation Reactor COD:TKN kd y Coefficient max

I 2.4:1 0.018 0.362 0.62

II 2.4:1 0.000 0.305 0.99

III 3.7:1 0.057 0.461 1.00

IV 7.3:1 0.042 0.355 0.94

v 3.7:1 0.160 0.611 0.99

62

Y varied among the reactors, with Reactor II showing the max

lowest value, and Reactor V, dosed at 1.0 mg/l nickel, showing

the highest value. For the reactors dosed at approximately 0.5

mg/l, Y did not depend upon the COD:TKN ratio. Y 's for max max

Reactors I, II, and IV were in the typical range of 0.25 to 0.40

(43), with Reactors III and V slightly greater.

The decay coefficient, kd, also varied among the reactors.

As for Y , kd for the reactors dosed at 0.5 mg/l was in-max

dependent of the COD:TKN ratio. The kd's for Reactors III and IV

fell into the typical range of 0.04 to 0.075 (43), with Reactors

I and II having relatively small kd's, and Reactor V, relatively

large.

The biokinetic coefficients were noticeably different for

Reactors II and V, Reactor II being distinguished by a very low

decay coefficient (essentially zero), and Reactor V having high

decay and growth coefficients. It appears that the low decay

rate for Reactor II resulted from the relatively large amount of

influent nitrogen available, which may have permitted enhanced

growth of both heterotrophs and autotrophs. This interpretation

is not conclusively supported, however, by the results for

Reactor I, fed the same COD:TKN ratio.

The marked differences in the biokinetic coefficients for

Reactor V, when compared to the other reactors, are attributed to

the nickel dose, which, as noted above, depressed reactor solids

concentration, while having no observable effects on COD removal.

63

The high Y reflects the greater-than-90-percent COD removal max

efficiencies for all reactors achieved over the range of mean

cell residence times for all reactor solids concentrations, and

should not connote stimulation.

The observed yield, shown in Figure 8, decreased with MCRT,

except ·for Reactor II, which had a fairly constant Y b , due to 0 s

the fact that the decay coefficient for this reactor was very

close to zero. The relative observed yields among reactors

at most MCRT's corresponded to relative reactor solids concen-

tration, again excepting the control, which showed a higher

observed yield than suggested by comparison.

Nitrification

As shown in Figure 9, which presents percentage nitrifi-

cation as a function of MCRT, production and destruction of

ammonia followed two distinct patterns. For Reactors I, II,

III, and IV, effluent ammonia nitrogen was produced at low

MCRT's. As MCRT increased, effluent ammonia nitrogen was

reduced increasingly below influent levels, until, at the

highest MCRT, destruction either remained fairly constant,

or fell off slightly to markedly. For Reactor V, effluent

ammonia was produced at all MCRT's, with effluent ammonia

concentration increasing with MCRT.

Net ammonia production at low MCRT's results from the

breakdown of organic nitrogen by microorganisms during synthesis,

in the absence of a well-established nitrifying population.

0.45

040

64

FIGURE 8. OBSERVED YIELD vs. MEAN CELL RESIDENCE TIME.

,oo

,0

10

10 z ... .. eo " .. ~

i !,Cl .. z •o ... V .. ... )0 ..

zo

,o

0 0

,oo

10

,o

z 10 ... .. " "' ,o .. i ~

~o z ... 40 u "' ... .. so

zo

,o

0 0

NH4 •-N

~ o:

' IZ •• 9c, M [ AN C[LL ~[SID[IIC[ TIM[

. . . "

~········

SYNTHlStZ NITIID11£N

' • IZ II

1k, M[AII C[LL flUIO[NCE TIM[

II

II

100

90

ID

70 z ... i '° .. i $0 .. z 401 ... u "' : JO

zo

10

0 o·

100

90

,o

z 70 ... .. ~ '° .. i $0 .. : 40 u "' r )o

zo

10

0 0

NH4 t •N

IYTH£SIZ[D NITIIOG[N

4 I II .. lie, M[AN C[LL IICSIOENCE TIM[

I I

NH4• •N

~ SYN!"ft[AIJ!ED ~N NITROGEN

4 I II II le, MEAN CELL RESIDENCE TIME

II

II

100.----,-------..----.--- ..

90

10

z 70 .. g,o ~ i IC) .. z .,,o u "' f JO

NN4• •N

NITIIOG[~ I • • • 1 0 0 4 I 12 16

lie, M[AN CfLL RUIO[NC[ TIM£

0 REACTOR I 6 REACTOR n 0 REACTOR m 0 REACTOR nr 0 REACTOR JZ'

II

FIGURE 9. PERCENT NITRIFICATION vs. MEAN CELL RESIDENCE TIME.

a, VI

66

As MCRT increases, the number of nitrifiers increases as well.

This is evidenced by Figure 9, which shows the percentage

nitrate-nitrogen rising with MCRT. Little organic nitrogen

appeared in the effluent of any reactor at any mean cell resi-

dence time, indicating that utilization of organic nitrogen was

not inhibited by these nickel concentrations.

Reactors I, II, III, and IV had good to excellent nitrifi-

cation, while Reactor V had almost none. Reactor IV, with no

annnonia-nitrogen in the influent, and the lowest COD:TKN ratio,

achieved 96 percent nitrification at a MCRT of 13.5 days.

Reactors I, II, and III, with close or equal COD:TKN ratios, had

similar degrees of nitrification at moderate MCRT's. The nickel-

fed reactors (Reactors II and IV) were less efficient than the

control (Reactor I) at lower MCRT's. At high MCRT's, however,

nitrate production for the control dropped significantly. This

decrease was unexpected, and probably resulted from insufficient

stabilization of the reactor following reseeding, as described in

"Materials and Methods".

The stabilization of nitrification at similar levels for

Reactors II and III at moderate MCRT's suggests that the frac-

tion of nitrifiers in the biomass increases with MCRT until a

maximum relative concentration is reached. Excess nitrogen exits

the reactor as ammonia-nitrogen. The influent nitrogen concen-

tration for the reactor with the lowest COD:TKN ratio (Reactor

.IV) was such that total consumption by the nitrifying population

67

was achieved. The nickel dose of 0.5 mg/l appeared to have no

effect on nitrification, except, as noted above, at low MCRT's.

In contrast, the nickel dose of 0.97 mg/l resulted in sharp

inhibition of nitrification. This is consistent with other

reported findings (14).

For all reactors, measured alkalinity corresponded closely

to predicted alkalinity, as calculated by the equation:

..:.Alk 3.57 [(6 Org-N) -(Synthesized N)]

-7.14(6NO; -N)

where

6Alk

60rg-N

Synthesized N

~ ~

change in alkalinity, mg/l

change in organic nitrogen, mg/l

synthesized nitrogen, mg/l

change in nitrate nitrogen, mg/l

and shown in Figure 10.

This relationship, developed by Scearce and others (44),

accounts not only for alkalinity destroyed during nitrification,

but also for alkalinity produced when organic nitrogen is miner-

alized to ammonia, and destroyed if the ammonia is synthesized by

the microorganisms in the biomass.

Figure 11 presents effluent pH vs. MCRT. Effluent pH

decreased, as expected, with the mineralization of ammonia,

which liberates hydrogen ions. A comparison of Figures 9 and

11 shows that substantial nitrification is possible at pH's down

' 0 E -.., 0 u a u (/) c(

~ .... z :J c( :Ill: ..J c(

z

68

200

100

0

-100

-200

0 0 REACTOR I -300

~ REACTORU 0 REACTOR m

-400 0 REACTOR llr 0 REACTOR 7

-500 -500 -400 -300 -200 -ioo 0 100 200

PREDICTED CHANGE IN ALKALINITY AS caco,,mg/I

FIGURE 10. MEASURED CHANGE IN ALKALINITY vs. PREDICTED CHANGE IN ALKALI NI TY.

8.0

7.5

7.0

6.5

6.0 x Q.

I-z 5.5 w :l ...I u. u. w 5.0

4.5

0 0 2

0 REACTOR l Cl REACTOR lI 0 REACTOR m 0 REACTOR DZ 0 REACTOR Y

4 6 8

69

10 12 14

ec, MEAN CELL RESIDENCE TIME, DAYS

16

FIGURE 11. EFFLUENT pH vs. MEAN CELL RESIDENCE TIME.

18

70

to 4.9. These results contradict the widely held belief that

nitrification rates are critically reduced at low pH's. Although

nitrification rate may indeed be slowed at low pH's, the decrease

is insufficient to reduce ultimate nitrate production.

NICKEL REMOVAL

Figure 12 shows nickel removal for nickel-fed reactors over

the range of MCRT's, on a total nickel basis. Nickel removal,

while not related to COD:TKN ratio, followed a similar pattern

for all reactors, peaking at moderate to high MCRT's. This

pattern of uptake may be related to the typical growth stages for

the microorganisms constituting the biomass at different MCRT's,

to exocellular polymer production, or to the types of

microorganisms prevalent at different MCRT's. Reactor II, which

showed the greatest single nickel removal at a moderate MCRT,

also had the highest reactor solids at that MCRT. The

relationship does not bear out at other MCRT's or among the other

reactors.

The percentage of total nickel in soluble form for Reactors

II, III, and IV is present in Figure 13. (Total nickel concen-

tration was not measured for Reactor V.) Almost all nickel

remained soluble for these reactors, except at moderate MCRT's,

where the soluble portion dropped to as low as 56 percent.

Moderate MCRT's seemed to favor uptake of the nickel by the

sludge, perhaps by exocellular polymers or by individual cells.

100

90

80

10 ~ 0

....J <l > 60 0 ~ w a:: ....J 50 w ~ (J

z I- 40 z w (J a:: w 30 (l.

20

10

0

71

6 REACTOR n 0 REACTOR lII.

0 REACTOR DZ'

0 REACTOR Y

0 2 4 6 8 10 12 14 16

ec, MEAN CELL RESIDENCE TIME' DAYS

FIGURE 12. NICKEL REMOVAL vs. MEAN CELL RESIDENCE TIME.

18

72

~ 0 0 0 ~

§ 90 0 z 0 _J 0 w ~ 80 u z w _J 10 CD :) _J 0 (/)

(/) 60 <l

_J w ~ 50 u z _J <l ~ 40 0 ~

~ z w 30 :) 6 REACTOR II _J u... u... 0 REACTOR m w

20 ~ 0 REACTOR Ill z w u a:: 10 w a..

0 0 2 4 6 8 10 12 14 16 18

ac, MEAN CELL RESIDENCE TIME, DAYS

FIGURE 13. PERCENT EFFLUENT SOLUBLE NICKEL vs. MEAN CELL RESIDENCE TIME.

SUNMARY AND CONCLUSIONS

In this study, data were collected from three bench-scale,

continuous flow activated sludge reactors and compared to the

data collected from two similar units in earlier studies (19,20).

The reactors were fed nickel doses up to 0.97 mg/1 and at dif-

ferent COD:TKN ratios. From the results of this study, the

following conclusions can be drawn:

1. COD removal efficiency is not impaired by nickel doses

up to 1 mg/1, nor is there an increase in effluent suspended

solids for these doses. The threshold concentration for nickel

toxicity to the activated sludge process, as measured by common

parameters of process performance, is thus greater than 1 mg/1.

2. Reactor solids concentration depends upon the COD:TKN

ratio, with higher concentrations carried at low COD:TKN ratios

at moderate to high mean cell residence times. One mg/1 nickel

depresses reactor solids concentration.

3. One mg/1 nickel causes an apparent increase in cell

yield and in endogenous decay, as measured by the biokinetic

yield and decay coefficients. A 0.5 mg/1 dose of nickel has a

varying effect on these parameters at different COD:TKN ratios.

4. One mg/l nickel inhibits nitrification almost com-

pletely, while a 0.5 mg/l dose has no adverse effect on degree

of nitrification, except at low mean cell residence times.

5. Nickel generally remains soluble through the activated

sludge process. Nickel removal is erratic over a range of mean

73

74

cell residence times, with moderate mean cell residence times

favoring uptake of the nickel by the sludge.

6. At high COD:TKN ratios, complete nitrification is

possible, while lower COD:TKN ratios tend to result in incomplete

but stable nitrification.

7. Degree of alkalinity destruction can be accurately

predicted over a range of COD:TKN ratios.

BIBLIOGRAPHY

1. Friburg, Lars, et al., Handbook on the Toxicology of Metals. Elsevier/North Holland Biomedical Press, Amsterdam (1979).

2. Hannah, Sidney A., et al., Metals in Municipal Sludge and Industrial Pretreatment as a Control Option. United States Environmental Protection AGency, Cincinnati (1977).

3. Conunittee on Medical and Biological Effects on Environmental Pollution, Nickel. National Academy of Sciences, Washington, D.C. (1975).

4. Seb ley, Scott F. , "Nickel." Minerals Yearbook Vol. I: Metals and Minerals, United States Department of Interior, Bureau of Mines (1981).

5. Jenkins, D. and W. E. Garrison, "Control of Activated Sludge by Mean Cell Residence Time." Journal Water Pollution Control Federation, 40, 1905 (1968).

6. Lawrence, A. W. and P. L. McCarty, "Unified Biological Treatment Design and Operation." Sanitary Engineering Division-ASCE, 2.§_, 757

Basis for Journal (1970).

7. Sherrard, J. H., "Kinetics and Stoichiometry of Completely Mixed Activated Sludge." Journal Water Pollution Control

d a ~ 1968 (1977).

8. Stall, T. R., and J. H. Sherrard, "Evaluation of Control Parameters for the Activated Sludge Process.'' Journal Water Pollution Control Federation, 2.Q_, 450 (1978).

9. Barth, E. F., et al., "Field Survey of Four Municipal Wastewater Treatment Plants Receiving Metallic Wastes." Journal Water Pollution Control Federation, l]__, 1101 (1965).

10. Heukelekian, H., and I. Gellman, "Studies of Biochemical Oxidation by Direct Methods IV: Effects of Toxic Metal Ions on Oxidation." Journal Water Pollution Control Federation, 27, No. 1, 70 (1955).

11. McDermott, G. N., et al., "Effects of Copper on Aerobic Biological Sewage Treatment." Journal Water Pollution Control Federation, 1.2_, 227 (1963).

75

76

12. Salotto, B. V., "Organic Load and the Toxicity of Copper to the Activated Sludge Process." Proceedings of the 19th Industrial Waste Conference, No. 117, Purdue University (1964).

13. McDermott, J. N., et al., "Nickel in Relation to Activated Sludge and Anaerobic Digestion Processes." Journal Water Pollution Control d a ~ 163 (1965).

14. Barth, E. F., et al., "Summary Report on the Effects of Heavy Metals inthe Biological Treatment Processes." Journal Water Pollution Control d a ~ 86 (1965).

15. Moulton, E. Q., and K. S. Shumate, "The Physical and Bio-logical Effects of Copper on Aerobic Biological Waste Treatment Processes." Proceedings of the 18th Industrial Waste Conference, Purdue University (1963).

16. Barth, E. F. et al., "Effects of a Mixture of Heavy Metals on Sewage Treatment Processes," Proceedings of the 18th Industrial Waste Conference, Purdue University, 1963.

17. Bagby, M. M., "The Effects of Cadmium and Nickel, In Combi-nation, on the Completely Mixed Activated Sludge Process." Master's Thesis, Virginia Polytechnic Institute and State University (1979).

18. Weber, A. S. and J. H. Sherrard, "Effects of Cadmium on the Completely Mixed Activated Sludge Process." Journal Water Pollution Control Federation, _2l, 2378 (1980).

19. Sujarittanonba, S., "The Effects of Nickel on the Completely Mixed Activated Sludge Process." Ph.D. Dissertation, Virginia Polytechnic Institute and State University (1979).

20. DiSalvo, R., and J. H. Sherrard, "The Stimulation of Nitri-fication at Low Nickel Concentrations." Proceedings, 12th Annual Middle Atlantic Industrial Waste Conference (1980).

21. Adams, C. E. ~a "The Effects and Removal of Heavy Metals in Biological Treatment." Heavy Metals in the Aquatic Environment, ed. P. A. Krenkel, Pergamon Press, Oxford (1975).

22. Neufeld, R. D., "Heavy Metals-Induced Deflocculation of Activated Sludge." Journal Water Pollution Control Feder-a ~ 1940 (1976).

77

23. Tomlinson, T. G., et al., "Inhibition of Nitrification in the Activated Sludge Process of Sewage Disposal." Journal of Applied Bacteriology, 29, No. 2, 266 (1966).

24. Stumm, W. and J. J. Morgan, Aquatic Chemistry-An Intro-duction Emphasizing Chemical Equilibria in Natural Waters. Wiley Interscience, New York (1970).

25. Manahan, S. E. and M. J. Smith, "The Importance of Chelating Agents." Water and Sewage Works, 2_, Vol. 120, 120 (1973).

26. Esmond, S. E., and A. C. Petrasek, "Trace Metal Removal." Industrial Water Engineering, l!_, 14-17 (1974).

27. Oliver, B. G. and E. G. Cosgrove, "The Efficiency of Heavy Metal Removal by a Conventional Activated Sludge Treatment Plant." Water Research, ~ 869 (1974).

28. Chen, K. Y. et al., "Trace Metals in Wastewater Effluents." Journal a ~ Control d a ~ 2663 (1974).

29. Neufeld, R. D., and E. R. Hermann, "Heavy Metal Removal by Acclimated Activated Sludge." Journal Water Pollution Control Federation,!!}__, 310 (1975).

30. Cheng, M. H. et al., "Heavy Metal Uptake by Activated Sludge." JournalWater Pollution Control Federation, !!}__, 362 (1975).

31. Jenkins, S. H., et al., "The Solubility of Heavy Metal Hydroxides in Water-,-Sewage,and Sewage Sludge II: The Precipitation of Metals in Sewage." International Journal Air and Water ~ 679 (1964).

32. Friedman, B. A., and R. R. Dugan, "Concentration and accumu-lation of metallic ions by the bacterium Zoogloea." Develop-ments in Industrial Microbiology, 2_, 381 (1968).

33. Baum, S. J., Introduction to Organic & Biological Chemistry, Second Edition. Macmillan Publishing Co., Inc., New York (1978).

34. Kugelman, I. J. and P. L. McCarty, "Cation Toxicity and Stimulation in Anaerobic Waste Treatment, II: Daily Feed Studies." Proceedings of the 19th Industrial Waste Con-ference, Purdue University (1964).

35. Poon, P. C. and K. H. Bhayani, "Metal Toxicity to Sewage Organisms." Journal Sanitary Engineering Division -ASCE, 2!_, 161 (1971).

78

36. Kugelman, S. J., and McCarty, P. L., "Cation Toxicity and Stimulation in Anaerobic Waste Treatment, II: Daily Feed Studies." Proc., 19th Industrial Waste Conference, Purdue University (1964).

37. Pavoni, J. L. et al., "Bacterial Exocellular Polymers and Biological Flocculation." Journal Water Pollution Control Federation, 44, 414 (1972).

38. Bitton, G., and V. Freihofer, "Influence of Extracellular Polysaccharides on the Toxicity of Copper and Cadmium towards Klebsilla aerogenes." Microbial Ecology, ~ 119 (1978).

39. Dugan, P. and P. Fister, "Implications of Microbial Polymer Synthesis in Waste Treatment and Lake Eutrophication," in Advances in Water Pollution Research, ed. S. H. Jenkins, Proceedings of the 5th Int'l. Conf. Water Poll. Res. Pergamon Press, Ltd., London (1971).

40. Brown, M. J. and J. N. Lester, "Metal Removal in Activated Sludge: The Role of Bacterial Exocellular Polymers." Water Research, ll• 817 (1979).

41. Standard Methods for the Examination of Water and Waste-water, 14th Edition. American Public Health Assoc., Washington, D.C. (1976).

42. Knocke, W.R., Personal Communication, Blacksburg, Virginia (1982).

43. MetCalf & Eddy, Inc., Wastewater Engineering, Treatment, Disposal, Reuse, Second Edition. McGraw-Hill Book Company, New York (1979).

44. Scearce, S. N. et al., "Prediction of Alkalinity Changes in the Activated Sludge Process." Journal Water Pollution Control Federation, -2l• No. 2, 399 (1980).

APPENDIX A

79

APPENDIX A-I

EQUILIBRIUM REACTIONS AND CONSTANTS FOR NICKEL HYDROXIDE

++ - + Ni + OH ~ Ni(OH)

+ [Ni(OH) ]

103.4 ++ -

[Ni ][OH]

+ -Ni(OH) +OH ~

[Ni(OH)2] 6 8 ------= 10.

+ -[Ni(OH) ] [OH ]

Ni(OH) J 102.8

Ni(OH)2 aq ~ Ni(OH)z s

80

APPENDIX A-II

EQUILIBRIUM REACTIONS AND CONSTANTS

FOR NICKEL-AMINE COMPLEXES

++ --- +2 Ni + NH3 - Ni (NH3)

N1.(NH3)+ 2 NH --- .( )+2 + 3 -Ni NH 3 2

Kl [Ni(NH3)+2]

103 ++ [Ni ] [NH3]

+2

K2 [Ni(NH3) 2 ]

102.18 +2 [Ni (NH3) ] [NH3]

+2

K3 [Ni(NH3) 3 ]

101. 64 . +2 [Ni(NH3) 2 ][NH3]

K4 [Ni(NH3):2]

101.16 = [Ni(NH3);2][NH3 ]

81

3 {31 = Kl = 10

82

APPENDIX A-II (continued)

1

1

APPENDIX B

83

TABLE B-1 RAW DATA FOR REACTOR I AT 0 • 5.59 DAYS c

COD MLSS Ni(Il} Ccncentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1980} (mg/l} (mg/l} (%} (mg/l} (mg/l} (days} (mg/l} (mg/l} (mg/l}

8/23 382 26 93.2 1496 90 5.52 0.022 0.044 0.024 7.1 6.3 8/24 386 26 93.3 1$84 70 6.25 0.018 0.042 0.021 7.1 6.3 8/25 394 26 93.4 1380 136 4.11 0.018 0.040 0.017 7.1 6.2 8/26 378 30 92.1 1312 70 5.88 0.016 0.037 0.024 7.0 6.2 8/27 302 22 92.7 1376 74 5.86 0.020 0.034 0.019 7.1 6.4 8/28 422 26 93.8 1516 80 5.91 0.025 0.032 0.025 7.1 6.4 AVG 377 26 93.1' 14"27 87 5.59 0.020 0.038 0.022 7.1 6.3 00

.po

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Uate Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980} (mg/l} (mg/l} (%} (mg/I} (mg/l} (%} (mg/l} (mg/l} (t} (mg/l) (mg/l)

8/23 456 168 -63.2 113 106 6.2 53.7 0 100 0.60 73.3 8/24 446 118 -73.5 9.9. 7 80.6 19.2 63.8 7.9 87.6 0.60 75.6 8/25 378 110 -70.9 96.3 89.6 7.0 56.0 0 100 0.50 80.6 8/26 434 109 -74.9 89.6 86.2 3.8 57.1 0 100 0.40 98.0 8/27 441 123 -72.1 106 77.3 27.1 59.4 0 100 0.40 107 8/28 412 120 -70.9 112 81.8 27.0 87.4 1.6 98.2 0.60 78.2 AVG 428 125 -70.9 103 86.9 15.1 62.9 1.6 97.6 0.50 85.5

TABLE 8-11 RAW DATA FOR REACTOR I AT 6 c • B.06 DAYS

COD .MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent ec Feed Effluent Effluent Feed Effluent

Filtered Efficiency Solids Solids Unfiltered Filtered Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)

8/11 397 43.2 89.1 996 30 8.94 0.035 0.039 0.021 7 .o 6.2 8/12 364 35.0 90.4 1400 54 7.95 0.015 0.039 0.040 7.0 6.1 8/13 405 35.0 91.4 1492 44 9.02 0.019 0.042 0.019 7.0 6. (I 8/14 392 35.0 91.1 688 204 1.82 0.014 0.051 0.026 7.0 6.0 8/15 389 35.0 91.0 1568 38 9.79 0.018 0.044 0.027 7.1 6.0 8/16 405 26.0 93.6 1484 46 8.83 0.025 0.040 0.037 7.0 6.0 8/17 418 59.7 85.7 1500 34 10.04 0.033 0.044 0.023 7.0 6.0 AVG 396 38.4 90.3 1304 64 8.06 0.023 0.043 0.028 7.0 6.0 CXl

V1

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date ·Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mgil) (mg/l)

8/11 431 137 -68.2 114 94.6 17 .o 57.7 0 100 0.50 72.3 8/12 4ll 93 -77.4 104 85.1 18.2 49.8 2.8 94.4 0.50 69.9 8/13 430 83 -80.7 111 81.2 26.8 59.9 5.0 91. 7 0.60 62.1 8/14 457 81 -82.3 117 90.2 22.9 57.7 1.1 98.1 0.50 80.7 8/15 446 176 -60.5 112 81.2 27.5 56.0 5.0 91.1 0.40 85.9 8/16 448 82 -81. 7 110 80.6 26.7 57.1 1.2 97.9 0.40 87.7 8/17 456 77 -83.1 115 82.9 27.9 56.0 8.4 85.0 0.40 77.0 AVG 440 104 -76.3 ll2 85.1 23.9 56.3 3.4 94.0 0.50 76.5

TABLE B-III RAW DATA FOR REACTOR I AT 0 c • 9.66 DAYS

COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent ec Feed Effluent Effluent Feed Effluent

Filtered Efficiency Solids Solids Unfiltered Filtered Filtered ( 1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)

7/24 376 35 90.7 1880 42 10.78 0.018 0.079 0.018 7.0 6.0 7/25 418 30 92.8 1736 50 9.67 0.009 0.032 0.035 7.0 5.7 7/26 408 33 91.9 1644 36 10.87 0.013 0.036 0.023 7.1 5.5 7/27 401 38 90.5 1804 48 10.02 0.014 0.041 0.038 7.0 5.7 7/28 410 33 92.0 1524 44 9.66 0.009 0.027 0.023 7.1 5.6 7/29 385 45 88.3 1468 38 10.14 0.026 0.032 0.031 7.1 5.6 7/30 406 45 88.9 1380 82 6.50 0.020 0.044 0.018 7.1 5.5

AVG 401 37 90.7 1634 49 9.66 0.016 0.042 0.027 7.1 5.6 00 (J\

Alkalinity as Caco3 NH 3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/I) (mg/l) (%) (mg/l) (mg/l) (%) (mg/ 1) (mg/l)

7/24 428 82 -80.8 91.3 86.8 -4.9 67.7 0 100 0.90 71.6 7/25 438 37 -91.6 95.8 73.9 -22.9 57.6 2.3 96.1 0.90 74.9 7/26 424 24 -94.3 110 72.8 -33.8 54.9 18.5 66.3 1.00 87 .0 7/27 394 35 -91.1 102 77.3 -24.2 86.8 8.9 89.8 0.90 85.3 7/28 446 23 -94.8 54.9 76.7 +39.7 64.9 1.1 98.3 0.90 89.3 7/29 416 24 -94.2 102 77.8 -23.7 49.9 0 100 0.90 89.9 7/30 447 19 -95.8 110 75.0 -31.8 62.2 4.0 93.6 0.90 75.4

AVG 428 35 -91.8 95.1 77 .2 -14.5 63.4 5.0 92.0 0.90 81.9

TABLE B-IV RAW DATA FOR REACTOR I AT e • 18.08 DAYS c

COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1980) (mg/ l) (mg/ l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)

10/19 339 32 90.6 2440 66 17.36 0.058 0.234 0.170 7.0 6.5 10/20 371 32 91.4 2450 54 20.37 0.034 0.170 0.146 7.1 6.5 10/21 371 28 92.S 2640 56 20.96 0.034 0.118 0.107 7.2 6.7 10/22 315 20 93.7 2570 56 20.54 0.020 0.133 0.066 7.1 6.7 10/23 363 28 92.3 2960 94 15.25 0.027 0.116 0.062 7.2 6.7 10/24 390 28 92.8 2840 100 14.00 0.028 0.062 0.036 7.2 6.7 AVG 358 28 92.2 2650 71 18.08 0.034 0.139 0.098 7.1 6.6 CXl ......

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/ 1) (mg/ 1)

10/19 454 226 -50.2 106 98.6 -7.0 62.1 3.9 -93.7 0.30 45.7 10/20 468 289 -38.3 107 113 +5.6 65.5 0 100 0.40 60.5 10/21 485 276 -43.1 105 114 +8.6 67.2 0 100 a.so 58.2 10/22 482 280 -41.9 122 102 -16.4 51.5 0 100 0.40 51.9 10/23 464 275 -40.7 112 106 -5.4 58.8 3.9 -93.4 0.30 56.7 10/24 490 253 -48.4 116 107 -7.8 59.4 7.2 -87.9 0.40 62.8 AVG 474 267 -43.8 111 107 -3.7 60.8 2.5 -95.8 0.40 56.0

TABLE B-V RAW DATA FOR REACTOR II AT 6 • 4.18 DAYS c

COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent 6 Feed Effluent Effluent Removal Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

8/18 356 30 91.6 636 52 3.91 0.670 0.411 0.397 38.7 7.0 7.2 8/19 383 37 90.3 692 62 3. 73 0.573 0.529 0.490 7.7 7.0 7.3 8/20 415 34 91.8 908 64 4.21 0.618 0.531 0.508 14.1 7.0 7.2 8/21 290 34 88.3 712 42 4.55 0.678 0.494 0.473 27.1 7.0 7.2 8/22 396 37 90.7 692 42 4.50 0.574 0.485 0.460 15.5 7 .1 7.2 A\IG 368 34 90.5 728 52 4.18 0.623 0.490 0.466 20.6 7.0 7.2

00 00

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) co (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

8/18 389 610 +56.8 89.l 162 +81.8 47.3 0 100 0.50 6.3 8/19 424 535 +26.2 104 143 +37.5 54. 2 5.0 90.8 0.50 6.0 8/20 392 546 +39.3 98.0 144 +46.9 53.2 1.1 97.9 0.50 5.0 8/21 355 562 +58.3 63.8 148 +132 43.7 4.5 89.7 0.50 4.9 8/22 424 576 +35.9 102 156 +52.9 53.8 0 100 0.50 4.9 AVG 397 566 +43.3 91.4 151 +70.2 50.4 2.1 95.7 0.50 5.4

TABLE B-VI RAW DATA FOR REACTOR II AT ec • 7.80 DAYS

COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluer.t

Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/ 1) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

7/17 409 32 92.2 1648 60 7.01 o.530 0.290 0.220 45.3 7.1 5.9 7/18 405 28 93.1 1700 80 6.26 0.518 0.401 0.251 22.6 7.1 6.1 7/19 402 32 92.0 1592 54 7.22 0.516 0.658 0.255 27.5 7.1 6.3 7/20 409 63 84.6 1572 30 8. 73 0.529 0.397 0.259 25.0 7.1 6.1 7/21 417 24 94.2 1564 40 8.00 0.530 0.380 0.295 28.3 7.1 6.0 7/22 405 28 93.l 1640 68 6.63 0.532 0.366 0.310 31.2 7.1 6.0 7/23 380 24 93.7 1536 12 10.40 0.648 0.398 0.302 36.7 7.1 5.9 7/24 394 24 93.9 1624 38 8.23 0.559 0.410 0.313 26.7 7.0 5.8 7/25 364 28 92.3 1532 60 6.80 0.578 1.492 0.302 40.1 7.0 5.8 7/26 402 28 93.0 1624 32 8.66 0.528 0.346 0.285 34.5 7.1 5.9 7/27 421 35 91. 7 1524 30 8.66 0.606 0.345 0.239 43.l 7.0 6.2 CX>

\0 AVG 401 31 92.2 1596 46 7.80 0.552 0.498 0.276 27.8 7. 1 6.0

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/1)

7/17 439 54 -87.7 115 91.0 20.9 55.4 0.8 98.6 0.50 81.3 7/18 436 94 -78.4 110 84.3 23.4 54.8 4.7 91.4 0.60 68.9 7/19 436 117 -73.2 109 88.2 19.1 74.5 3.1 95.8 0.60 73.3 7/20 442 97 -78.1 111 89.9 19.0 51.8 0 100 0.60 74.3 7/21 435 76 -82.5 110 87.1 20.8 54.8 0 100 0.60 81. 3 7/22 424 64 -84.9 108 82.9 23.2 63.6 3.9 93.9 0.60 69.0 7/23 427 55 -87.1 96.4 76.2 21.0 58.2 8.4 85.6 0.50 84.3 7/24 435 45 -89.7 95.2 75.6 20.6 54.3 5.0 90.8 0.50 71.6 7/25 389 53 -86.4 93.5 77.3 17.3 55.0 5.0 90.9 0.50 96.1 7/26 443 61 -86.2 -- 78.4 -- -- 8.4 -- .,0. 70 79.3 7/27 416 135 -67.6 -- 89.6 -- -- 3.9 -- o. 70 69.2 AVG 429 77 -82.0 105 83.7 20.6 58.0 3.9 94.l 0.60 76.3

TABLE B-VII RAW DATA FOR REACTOR II AT 6 • 11.88 DAYS c

COD HLSS Ni(ll) Concentration pH

Date Feed Effluent Removal Reactor Effluent a Feed Effluent Effluent Removal Feed Effluent Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered

(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

6/24 412 28 93.2 2556 38 11. 52 0.543 0.475 0.468 12.5 7.2 4.9 6/25 408 46 88.7 2432 34 11. 72 0.535 0.512 0.467 4.3 7.2 4.9 6/26 408 42 89.7 2448 22 12.97 0.550 0.486 0.477 12.4 7.2 4.9 6/27 -- 28 -- 2468 30 12.15 0.548 0.487 0.491 11.1 7.2 4.9 6/28 419 50 88.1 2368 50 10.30 0.541 0.498 0.503 8.0 7.2 4.9 6/29 405 57 85.9 2232 24 12.50 0.545 0.480 0.490 11.9 7.2 4.9 6/30 408 39 90.4 2328 30 11. 97 0.554 0.450 0.479 18.8 7.2 5.2 AVG 410 41 89.3 2405 33 11.88 0.545 0.484 0.482 11. 3 7.2 4.9

\0 0

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Het Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

6/24 465 0 -100 109 76.2 -30.1 76.7 0 100 0.60 89.1 6/25 462 0 -100 111 74.8 -32.6 57.9 0 100 0.70 97.0 6/26 462 0 -100 112 75.3 -32.8 80.4 0 100 o. 70 94.3 6/27 460 0 -100 -- 74.2 -- -- 0 -- --0 84.4 6/28 460 0 -100 108 65.5 -39.4 57.1 6.2 89.1 0.80 87.2 6/29 455 0 -100 108 71.1 -34.2 56.6 1.1 98.1 o. 70 82.0 6/30 462 6 -98.7 108 70.6 -34.6 57.7 3.3 94.3 0.70 85.7 AVG 461 1 99.8 109 72.5 -34.0 64.4 1. 5 96.9 0.70 88.5

TABLE B-VIII RAW DATA FOR REACTOR II AT 6 • 14.00 DAYS c

COD MLSS Hi(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent

1''iltered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

6/12 407 27 93.4 2564 26 13. 77 0.541 0.507 0.501 6.3 7.2 5.0 6/13 411 27 93.4 2560 28 13.53 0.532 0.534 0.510 -- 7.2 5.0 6/14 407 27 93.4 2528 30 13.25 0.555 0.589 0.510 -- 7.2 5.1 6/15 415 27 93.5 2624 24 14.09 0.528 0.667 0.516 -- 7.2 5.0 6/16 415 31 92.5 2600 22 14. 32 0.523 0.589 0.513 -- 7.2 5.1 6/17 415 27 93.5 2716 16 15.24 0.526 4 .137 0.512 -- 7.2 5.1 6/18 407 31 92.4 2780 28 13. 79 0.524 54.0 0.493 -- 7.2 5.1 AVG 411 28 93.2 2625 24.9 14.00 0.533 8.718 0.508 7.2 5.1 \0 -- I-'

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

6/12 462 0 -100 119 72.8 38.8 59.9 1. 7 97.2 0.90 99.1 6/13 463 0 -100 120 75.0 37.5 57.4 1. 7 97 .0 0.40 84.9 6/14 463 0 -100 116 75.3 35.1 55.2 0 100 0.40 101 6/15 462 0 -100 122 75.9 37.8 52.3 0 100 0.40 99.5 6/16 465 0 -100 121 76.2 37.0 55.8 0 100 0.40 99.3 6/17 458 0 -100 118 78.9 33.1 65.5 0 100 0.60 98.3 6/18 461 0 -100 120 75.6 37.0 60.2 0 100 0.80 97.3 AVG 462 0 -100 119 75.7 36.6 59.0 0.5 99.2 0.60 97.1

TABLE B-IX RAW DATA FOR REACTOR Ill AT 6 • 5.99 DAYS c

COD HLSS Ni(ll) Concentration pH Date Feed Effluent Removal Reactor Effluent 6 Feed Effluent Effluent Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)

8/3 408.7 66.0 83.8 1292 38 5.92 .58 .55 .54 7.0 6.7 8/4 414.7 68.3 83.5 1232 46 5.69 .57 .56 .55 7 .o 6.7 8/5 412. 7 58.l 85.9 1292 54 5.33 .59 .56 .56 7.1 6.6 8/6 408.7 53.l 87.0 1216 44 5.64 .60 .55 .55 7.0 6.6 8/7 412.7 38.2 90.7 1256 16 7.36 .59 .57 .56 7.1 6.5

AVG 411.5 56.7 96.2 1258 39 5.99 .59 .56 .55 7.0 6.6 \0 N

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

8/3 252 173 -31.3 55.2 62.4 +13.0 55.4 6.0 -89.2 0.50 29.0 8/4 256 171 -33.2 55.7 63.2 +13.5 56.0 6.0 -89.3 0.50 39.8 8/5 254 154 -39.4 54.6 61.3 +12.3 55.4 4.2 -92.4 0.50 33.6 8/6 255 150 -41.2 55.2 60.0 +8.7 55.4 3.0 -94.6 0.50 37.5 8/7 254 133 -47.6 55.7 57.0 +2.3 54.9 1.8 -96.7 0.50 43.9

AVG 254 156 -38.6 55.3 60.8 +9.9 55.4 4.2 -92.4 0.50 36.8

TABLE B-X RAW DATA FOR REACTOR III AT 0

c • 8.86 DAYS

COD MLSS Ni(II) Concentration pH

Date Feed Effluent Removal Reactor Effluent 0 Feed Effluent Effluent Feed Effluent Filtered Efficiency Solids Solids

c Unfiltered Filtered Filtered

(1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l)

8/8 397.3 41.l 89.6 1712 20 9. 73 .56 .51 .49 7.0 5.4 8/9 403.l 32.7 91.9 1724 28 8.96 .53 .50 .46 7 .o 5.5 8/10 403.l 36.6 90.9 1712 42 7.90 .54 .47 .47 7.0 5.7 8/11 399.2 32.7 91.8 1756 38 8.17 .56 .51 .50 7.0 5.7 8/12 403.l 38.7 90.4 1700 20 9.54 .54 .52 .50 7.0 5.7

AVG 401.2 36.4 90.9 1721 30 8.86 .55 .50 .48 7.0 5.6 \0 VJ

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration

Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent Filtered Change Filtered Change Filtered Change Filtered

(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (l!lg/l) (mg/l) (%) (mg/l) (mg/l)

8/8 252 15 -94.0 53.8 49.5 -8.0 58.5 4.6 -92.l 0.50 49.8 8/9 257 17 -93.4 56.3 44.6 -20.8 54.6 4.1 -92.5 0.50 61.2 8/10 255 25 -90.2 56.0 44.l -21.2 55.7 4.4 -92.l 0.50 63.0 8/11 254 28 -89.0 54.9 43.7 -20.4 56.3 5.4 -90.4 0.50 63.3 ~ 259 28 -89.2 57.4 44.5 -22.5 57.7 4.9 -91.5 0.50 51.5

AVG 255 23 -91.0 55.7 45.3 -18.7 56.6 4.7 -91. 7 0.50 57.8

TABLE B-XI RAW DATA FOR REACTOR III A1' 6 • 12.04 DAYS c

COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) \ (mg/l) (mg/l) (mg/l)

7/29 427.4 51.8 87.9 2164 34 11.10 .59 .60 .60 7.0 5.3 7/30 403.2 43.6 89.2 2160 12 13. 71 .58 .61 .61 7.0 5.2 7 /31 423.4 37.2 91.2 2152 30 11.60 .59 .59 .59 7.0 5.2 8/1 417.3 24.7 94.1 2160 30 11.55 .62 .59 .58 7.1 5.3 8/2 416.7 26.9 93.5 2156 24 12.24 .60 .60 .60 7.0 5.3

AVG 417 .6 36.8 91.2 2158 26 12.04 .6 .6 .6 7.0 5.3 \0 ~

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1979) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

7/29 238 10 -95.8 56.0 41.8 -25.3 54.3 6.5 -88.0 0.5 54.4 7 /30 250 9 -96.4 55.4 43.6 -21.3 51.0 4.4 -91.4 0.5 70.0 7/31 257 9 -96.5 56.0 43.0 -23.2 56.0 4.4 -92.1 0.5 60.5 8/1 251 11 -95.6 55.4 42.l -24.0 54.4 3.7 -93.2 0.5 67.5 8/2 253 11 -95.6 55.7 42.3 -24.0 54.9 2.9 -94.7 0.5 54.l

AVG 250 10 -96.0 55.7 42.6 -23.5 54.1 4.4 -92.0 0.5 61.3

TABLE B-XII RAW DATA FOR REACTOR IV AT a

c • 5.17 DAYS

COD HLSS Ni(II) Concentration pH

Date Feed Effluent Removal Reactor Effluent ec Feed ~ Effluent Removal Feed Effluent Filtered Efficiency Solids Solids Unfiltered Filtered Efficiency Filtered

(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

8/11 419 35 91. 7 1388 40 5.81 0.522 0.465 0.444 10.9 7.0 7.6 8/12 335 31 90.8 728 58 3.96 0.518 0.514 0.456 0.8 7.0 7.6 8/13 418 35 91.6 1040 80 4.03 0.594 0.557 0.427 6.2 7.0 7.6 8/14 405 34 91.6 1384 20 6.70 0.509 0.590 0.440 15.9 7 .o 7.6 8/15 403 30 92.6 800 32 5.27 0.520 0.484 0.435 6.9 7.0 7.6 8/16 407 34 91. 7 780 30 5.34 0.595 0.491 0.456 17.5 7.0 7.6 8/17 388 45 88.4 840 38 5.05 0.608 0.499 0.434 17.9 7.0 7.6

\0

AVG 396 35 91.2 994 43 5.17 0.552 0.514 0.442 10.9 7.0 7.6 V1

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration

Uate Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent Filtered Change Filtered Change Filtered Change Filtered

(1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

8/11 265 303 +44.5 0 34.7 -- 59.4 7.3 87.7 0.6 3.3 8/12 243 361 +48.6 0 33.0 -- 46.5 6.2 86.7 0. 7 1.0 8/13 204 363 +77.9 0 34.2 -- 52.1 3.3 93.7 0.6 1.6 8/14 250 377 +50.8 0 35.3 -- 54.9 3.9 92.9 0.6 1.0 8/15 251 378 +50.6 0 34.2 -- 56.0 3.3 94.1 0.7 1.3 8/16 250 390 +56.0 0 35.8 -- 56.6 4.0 92.9 0.6 1.1 8/17 221 391 +76.9 0.6 37.0 -- 54.8 2.7 95.1 0.5 1.0

AVG 241 378 +57.9 0.1 34.9 -- 54.3 4.4 91.9 0.6 1.5

TABLE B-XllI RAW DATA FOR REACTOR IV AT 8 • 7.19 DAYS c

COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (l!lg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

7/29 410 61 85.l 1416 48 7.22 0.548 0.353 0.300 35.6 7.0 7.2 7/30 410 57 86.1 1294 32 8.09 0.529 0.320 0.246 39.5 7.0 7.3 7/31 414 45 89.l 1280 48 6.93 0.531 0.317 0.236 40.3 7.1 7.2 8/1 410 45 89.0 1068 18 9.02 0.532 0.352 0.266 33.8 7.0 7.2 8/2 410 123 70.0 468 34 4.97 0.517 0.418 0.393 19.2 7.1 7.2 8/3 410 66 83.9 708 42 5.56 0.525 0.532 0.484 -- 7.1 7.3 8/4 414 62 85.0 1368 28 8.57 0.532 0.501 0.459 5.8 7.0 7.5 '° AVG 411 57 84.0 1086 36 7.19 0.531 0.399 0.341 24.9 7.0 7.3 (1\

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) Cmg/l) (%) (mg/l) (mg/l)

7/29 244 350 +43.4 0 34.7 -- 54.9 5.1 90.7 o. 7 26.3 7/30 247 325 +31.6 0 33.0 -- 54.9 4.0 92.7 0.7 22.7 7/31 248 286 +15.3 0 26.9 -- 54.9 11. 7 78.7 0.6 24.4 8/1 248 296 +19.3 0 27.4 -- 56.6 8.4 85.2 0.7 20.2 8/2 247 306 +23.9 0.6 22.4 -- 54.3 25.2 53.6 0.6 10.7 8/3 248 368 +48.4 0.6 34.2 -- 54.3 5.6 89.7 0.6 6.4 8/4 249 363 +45.8 0.6 30.8 -- 54.8 12.9 76.5 0.6 5.0 AVG 247 328 32.5 0.3 29.9 -- 55.0 10.4 81.0 0.6 16.5

TABLE B-XIV RAW DATA FOR REACTOR IV AT 6 • 13.45 DAYS c

COD HLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed f;ffluent Effluent Removal Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered . Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

7/17 433 10 97.7 2000 18 12.96 0.535 0.365 0.310 31.8 7.1 6.4 7/18 432 28 93.5 2l12 34 11.26 0.535 0.351 0.297 34.4 7.1 6.4 7 /19 412 60 85.4 1968 16 13.21 0.517 0.365 0.327 29.4 7.1 6.4 i/20 439 32 92.7 1916 12 13. 77 0.554 0.339 0.331 38.8 7.1 6.3 7/21 4ll 32 92.2 1960 6 14.84 0.538 0.325 0.310 39.6 7.1 6.3 7/22 424 10 97.6 1948 14 13.48 -- 0.376 0.352 -- 7.0 6.3 7/23 412 32 92.2 1688 6 14.66 -- 0.349 0.337 -- 7.0 6.4

AVG 423 29 93.0 1942 15 13.45 0.536 0.353 0.323 34.8 7.1 6.4 '° -...J

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

7/17 243 80 -67.l 0 0 0 53.8 1.1 98.0 0.7 47.8 7/18 243 85 -65.0 0 0 0 50.4 2.8. 94.4 0.5 60.8 7/19 239 87 -63.6 0 0 0 47.0 2.8 94.0 0.5 61.2 7 /20 248 85 -65.7 0 0 0 79.8 0 100 0.6 45.3 7/21 246 83 -66.3 0 0 0 59.4 l. 7 97.1 0.6 48.8 7/22 237 83 -65.0 0 0 0 53.2 4.5 91.5 0.8 50.6 7/23 237 83 -65.0 0 0 0 53.8 2.2 95.9 0.6 58.3

AVG 242 84 -65.4 0 0 0 56.8 2.2 95.8 0.6 53.3

TABLE B-XV RAW DATA FOR REACTOR IV AT 6 • 15.0 DAYS c

COD HLSS Ni(ll) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

5/26 403 4 99.0 2290 20 14.23 0.516 0.542 0.475 -- 7.2 6.7 5/27 411 11 97.3 2230 12 15.44 0.524 0.514 0.490 1.9 7.2 6.6 5/28 403 11 97.3 2280 12 15.49 0.524 0.487 0.468 7.1 7.2 6.6 5/29 373 11 97.l 2410 8 16.30 0.529 0.488 0.442 7.8 7.2 6.6 5/30 411 8 98.l 2460 16 15.01 0.533 0.478 0.452 10.3 7.2 6.6 5/31 399 15 96.2 2440 14 15.30 0.529 0.489 0.442 7.6 7.2 6.6 6/1 403 6 98.5 2430 30 13.11 0.567 0.488 0.445 13.9 7.2 6.6 AVG 400 9 97.6 2363 16 15.00 0.532 0.498 0.459 6.9 7.2 6.6 \0

00

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Feed Effluent

Filtered Change Filtered Change Filtered Change Filtered (1980) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l)

5/26 255 127 -50.2 0 0.6 -- 61.3 3.9 93.6 0.6 54.6 5/27 256 109 -57.4 0 0 -- 62.4 2.8 95.5 0.6 57.8 5/28 253 115 -54.6 0 0.8 -- 58.5 1. 7 97.l 0.5 50.6 5/29 249 113 -54.6 0 0.6 -- 59.0 2.8 95.3 0.4 47.9 5/30 254 109 -57.l 0 0 -- 55.2 2.5 95.5 0.4 46.l 5/31 252 106 -57.9 0 0 -- 59.0 2.8 95.3 0.4 58.5 6/1 252 107 -57.5 0 0 -- 62.2 2.8 95.5 0.5 56.8 AVG 253 112 -55.6 0 0.3 -- 59.7 2.8 95.4 0.5 53.2

TABLE B-XVI RAW DATA FOR REACTOR V AT 8 • 5.2 DAYS c

COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Removal Feed Effluent

Fil tend Efficiency Solids Solids c Filtered Efficiency Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) c.ngt1> (%)

5/2 410 24 94.2 1124 20 5.5 1.00 0.92 8.0 7.1 7.7 5/3 396 28 92.9 1120 30 5.1 0.96 0.80 16.7 7.1 7.7 5/4 383 32 91.6 1116 27 5.3 0.98 0.91 7.1 7.2 7.6 5/5 396 20 95.0 1120 36 4.9 1.00 1.03 -3.0 7.0 7.6 5/6 400 24 94.0 1036 32 5.0 1.01 1.05 -4.0 7.3 7.7 5/7 389 24 93.8 1112 28 5.2 0.97 0.89 8.2 7.2 7.7 5/8 387 20 94.8 1112 29 5.2 1.00 0.84 16.0 7.2 7.7 AVG 394 25 93.8 1106 29 5.2 0.99 0.92 7.0 7.2 7.7 '° '°

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Effluent

Filtered Change Filtered Change Filtered Change Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l)

5/2 238 330 38.7 58.2 87.9 51.0 54.3 3.4 -93.7 1.3 5/3 244 338 38.5 52.6 86.2 63.9 52.6 2.2 -95.8 0.7 5/4 246 326 32.5 60.5 96.2 42.5 52.1 2.8 -94.6 2.0 5/5 236 336 42.4 60.5 90.7 49.9 52.1 1. 7 -96.7 1.5 5/6 237 344 45.1 53.8 87.4 62.5 53.2 2.2 -95.9 1.6 5/7 239 340 42.3 50.4 82.9 64.5 53.2 3.4 -93.6 1.1 5/8 244 344 41.0 53.8 80.6 49.8 52.6 6.2 -88.2 1.3 AVG 241 337 40.1 55.7 86.0 54.9 52.9 3.1 -94.1 1.4

TABLE B-XVII RAW DATA FOR REACTOR V AT 6 • 10.6 DAYS c

COD MLSS Ni(ll) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Removal Feed Effluent

Filtered Efficiency Solids Solids c Filtered Efficiency Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (%)

3/10 406 36 91.l 1480 12 10.5 1.01 0.85 15.8 7.1 7.6 3/11 414 28 93.2 1512 4 11.5 1.03 o. 70 32.0 7.1 7.8 3/12 398 28 93.0 1564 6 11.3 1.00 0.95 5.0 7.2 7.7 3/13 387 32 91.7 1488 14 10.2 1.02 0.90 11.8 7.1 7.6 3/14 387 28 92.8 1488 5 11.4 0.99 0.77 22.2 7.0 7.6 3/15 375 28 92.5 1396 24 9.1 0.96 1.00 -4.2 7.1 7.6 3/16 402 24 94.0 1436 12 10.4 0.98 0.84 14.3 7.1 7.5 ..... AVG 396 29 92.6 1475 11 10.6 1.00 0.86 13.8 7.1 7.6 0

0

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Effluent

Filtered Change Filtered Change Filtered Change Filtered (1978) (mg/l) (mg/ 1) (%) (mg/l) (mg/l) (%) (mg/l) (mg/ l) (%) (mg/l)

3/10 236 356 50.8 56.0 82.9 48.0 48.7 5.3 -89.1 1.9 3/11 229 362 58.1 52.6 85.7 62.9 53.2 3.3 -93.8 1. 7 3/12 224 352 57.l 56.0 89.0 58.9 53.8 4.0 -92.6 1.8 3/13 229 356 55.5 57.1 92.4 61.8 51.5 4.2 -91.8 1.8 3/14 230 354 53.9 57.l 95.2 66.7 52.l 5.6 -89.3 1.9 3/15 236 361 53.0 52.7 94.1 50.1 45.9 3.3 -92.8 1.5 3/16 242 340 40.5 56.0 85.2 52.1 51.5 3.3 -93.6 1.6 AVG 232 354 52.7 56.8 89.2 57.2 50.6 4.1 -91.9 1. 7

TABLE B-XVIII RAW DATA FOR REACTOR V AT 6 • 14.5 DAYS c

COD MLSS Ni(II) Concentration pH Date Feed Effluent Removal Reactor Effluent e Feed Effluent Effluent Removal Feed Effluent

Filtered Efficiency Solids Solids c Unfiltered Filtered Efficiency Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (days) (mg/l) (mg/l) (mg/l) (%)

2/22 402 34 91.5 1736 6 15.5 0.85 -- o. 79 7.1 7.1 7.7 2/23 412 46 88.8 1704 12 14.2 1.00 -- 0.90 10.0 6.9 7.7 2/24 410 38 90.7 1684 8 15.0 0.95 -- 0.83 12.6 7.1 7.5 2/25 402 42 89.6 1648 17 13.2 0.86 -- 0.81 5.8 7.1 7.7 2/26 395 30 92.4 1704 4 16.0 0.98 -- 0.79 19.4 7.1 7.5 2/27 )85 34 91.2 1732 8 15.1 0.94 -- 0.87 7.5 7.1 7.7 2/28 370 27 92.7 1768 16 13.6 0.88 -- 0.90 -2.3 7.0 7.5 3/1 393 23 94.2 1672 14 13.8 0.93 -- 0.87 6.5 7.0 7.6 3/2 431 27 93.7 1808 20 13.0 1.00 -- 0.90 10.0 7 .0 7.6 3/3 )93 31 92.1 1702 6 15.5 0.89 -- 0.88 1.1 7.0 7.6 ...... AVG )99 3) 91. 7 1716 11 14. 5 0.93 -- 0.85 7.8 7.0 7.6 0 ......

Alkalinity as Caco3 NH3-N Concentration Org-N Concentration N03-N Concentration Date Feed Effluent Net Feed Effluent Net Feed Effluent Net Effluent

Filtered Change Filtered Change Filtered Change Filtered (1978) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l) (mg/l) (%) (mg/l)

2/22 222 352 58.6 47.0 84.0 78.7 44.8 10.0 -77.7 1.4 2/23 218 344 57.8 47.0 86.2 83.4 53.8 6.8 -87.4 1.6 2/24 230 346 50.4 52.1 84.0 61.2 49.8 9.0 -81.9 1.4 2/25 222 352 58.6 38.l 84.0 120.5 61.6 9.0 -85.4 1.4 2/26 274 350 27.7 53.8 84.0 56.1 61.6 6.7 -89.1 1. 6 2/27 232 356 53.4 52.1 85.1 63.3 49.8 7.9 -84.1 1. 5 2/28 246 354 43.9 53.8 84.0 56.1 48.1 6.7 -86.1 1.6 3/1 272 388 42 .6 49.3 81.8 65.9 52.6 10.0 -81.0 1.6 3/2 240 384 60.0 51.0 90.7 77.8 57.6 7.9 -86.3 2.2 3/3 225 371 64.9 49.8 88.4 77.5 54.4 7.9 -85.5 1. 7 AVG 233 360 51.8 49.4 85.2 74.1 53.4 8.2 -84.5 1.6

The vita has been removed from the scanned document

EFFECTS OF NICKEL ON ACTIVATED SLUDGE PERFORMANCE

AT VARYING TKN:COD RATIOS

by

Patti G. Trahern

(ABSTRACT)

The effects of a continuous dose of 0.5 mg/l nickel on

activated sludge performance at varying COD:TKN ratios were

investigated. Continuous flow, complete mix, bench-scale

reactors were operated over a range of mean cell residence times,

and COD removal efficiency, biokinetic coefficients, extent of

nitrification, and nickel removal evaluated at each. Data from

two earlier studies, in which 0.5 and 1 mg/l nickel doses were

applied to similar units, were included for comparison.

Organic removal efficiency was not impaired for the nickel

doses considered. Biokinetic coefficients and nitrate production

were also unaffected by 0.5 mg/l nickel. In contrast, one mg/l

nickel sharply inhibited nitrification, caused an apparent

decrease in reactor solids concentration, and related biokinetic

changes in coefficients. Nickel removal was erratic.