arsenic treatment technologies for soil, waste, and water. u.s
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Solid Waste EPA-542-R-02-004and Emergency Response September 2002(5102G) www.epa.gov/tio
clu-in.org/arsenic
Arsenic Treatment Technologies for Soil, Waste, and Water
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TABLE OF CONTENTS
Section Page
LIST OF ACRONYMS AND ABBREVIATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv
FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
NOTICE AND DISCLAIMER . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi
PART I OVERVIEW AND FINDINGS
1.0 EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 1
2.0 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 12.1 Who Needs to Know about Arsenic Treatment Technologies? . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 12.2 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 12.3 How Often Does Arsenic Occur in Drinking Water? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 12.4 How Often Does Arsenic Occur at Hazardous Waste Sites? . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 22.5 What Are the Structure and Contents of the Report? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 42.6 What Technologies and Media Are Addressed in This Report? . . . . . . . . . . . . . . . . . . . . . . . . 2 - 42.7 How Is Technology Scale Defined? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 42.8 How Are Treatment Trains Addressed? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 52.9 What Are the Sources of Information for This Report? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 52.10 What Other Types of Literature Were Searched and Referenced for This Report? . . . . . . . . . . 2 - 52.11 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 6
3.0 COMPARISON OF ARSENIC TREATMENT TECHNOLOGIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 13.1 What Technologies Are Used to Treat Arsenic? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 13.2 What Technologies Are Used Most Often to Treat Arsenic? . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 13.3 What Factors Affect Technology Selection for Drinking Water Treatment? . . . . . . . . . . . . . . 3 - 33.4 How Effective Are Arsenic Treatment Technologies? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 33.5 What Are Special Considerations for Retrofitting Existing Water Treatment Systems? . . . . . . 3 - 43.6 How Do I Screen Arsenic Treatment Technologies? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 43.7 What Does Arsenic Treatment Cost? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 63.8 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 6
PART II ARSENIC TREATMENT TECHNOLOGY SUMMARIES
PART IIA ARSENIC TREATMENT TECHNOLOGIES APPLICABLE TO SOIL AND WASTE
4.0 SOLIDIFICATION AND STABILIZATION TREATMENT FOR ARSENIC . . . . . . . . . . . . . . . . . . . 4 - 1
5.0 VITRIFICATION FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 1
6.0 SOIL WASHING/ACID EXTRACTION FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 - 1
7.0 PYROMETALLURGICAL RECOVERY FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 1
8.0 IN SITU SOIL FLUSHING FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 1
PART IIB ARSENIC TREATMENT TECHNOLOGIES APPLICABLE TO WATER
9.0 PRECIPITATION/COPRECIPITATION FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 1
10.0 MEMBRANE FILTRATION FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 1
11.0 ADSORPTION TREATMENT FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 1
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12.0 ION EXCHANGE FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 1
13.0 PERMEABLE REACTIVE BARRIERS FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 - 1
PART IIC ARSENIC TREATMENT TECHNOLOGIES APPLICABLE TO SOIL, WASTE, ANDWATER
14.0 ELECTROKINETIC TREATMENT OF ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 - 1
15.0 PHYTOREMEDIATION TREATMENT OF ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 - 1
16.0 BIOLOGICAL TREATMENT FOR ARSENIC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 - 1
APPENDICES
APPENDIX A � LITERATURE SEARCH RESULTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
APPENDIX B � SUPERFUND SITES WITH ARSENIC AS A CONSTITUENT OF CONCERN . . . . . . . . . . . B-1
LIST OF TABLES
Table Page
1.1 Arsenic Treatment Technology Descriptions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 31.2 Summary of Key Data and Findings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 - 42.1 Number of Superfund Sites with Arsenic as a Contaminant of Concern by Media . . . . . . . . . . . . . . . . . 2 - 22.2 Number of Superfund Sites with Arsenic as a Contaminant of Concern by Site Type . . . . . . . . . . . . . . 2 - 43.1 Applicability of Arsenic Treatment Technologies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 93.2 Arsenic Treatment Technologies Screening Matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 103.3 Available Arsenic Treatment Cost Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 153.4 Summary of Cost Data for Treatment of Arsenic in Drinking Water . . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 174.1 Solidification/Stabilization Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 64.2 Long-Term Solidification/Stabilization Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . 4 - 125.1 Vitrification Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 56.1 Soil Washing/Acid Extraction Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . 6 - 47.1 Pyrometallurgical Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 48.1 In Situ Soil Flushing Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 49.1 Precipitation/Coprecipitation Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . 9 - 710.1 Membrane Filtration Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 - 511.1 Adsorption Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 612.1 Ion Exchange Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 513.1 Permeable Reactive Barrier Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . 13 - 614.1 Electrokinetics Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 - 515.1 Phytoremediation Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 - 516.1 Biological Treatment Performance Data for Arsenic . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 - 4
LIST OF FIGURES
Figure Page
2.1 Top Twelve Contaminants of Concern at Superfund Sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 - 32.2 Number of Applications of Arsenic Treatment Technologies at Superfund Sites . . . . . . . . . . . . . . . . . . 2 - 43.1 Number of Identified Applications of Arsenic Treatment Technologies for Soil and Waste . . . . . . . . . . 3 - 23.2 Number of Identified Applications of Arsenic Treatment Technologies for Water . . . . . . . . . . . . . . . . . 3 - 2
LIST OF FIGURES (continued)
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Figure Page
3.3 Number of Identified Applications of Arsenic Treatment Technologies for Soil, Waste, and Water . . . 3 - 34.1 Binders and Reagents Used for Solidification/Stabilization of Arsenic for 21 Identified Superfund
Remedial Action Projects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 14.2 Scale of Identified Solidification/Stabilization Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . 4 - 25.1 Scale of Identified Vitrification Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 26.1 Scale of Identified Soil Washing/Acid Extraction Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . 6 - 17.1 Scale of Identified Pyrometallurgical Recovery Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . 7 - 18.1 Scale of Identified In Situ Soil Flushing Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . . 8 - 19.1 Scale of Identified Precipitaition/Coprecipitation Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . 9 - 210.1 Scale of Identified Membrane Filtration Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . 10 - 111.1 Scale of Identified Adsorption Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 - 212.1 Scale of Identified Ion Exchange Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 - 213.1 Scale of Identified Permeable Reactive barrier Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . 13 - 314.1 Scale of Identified Electrokinetics Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 - 315.1 Scale of Identified Phytoremediation Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . 15 - 216.1 Scale of Identified Biological Treatment Projects for Arsenic Treatment . . . . . . . . . . . . . . . . . . . . . . . 16 - 2
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LIST OF ACRONYMS AND ABBREVIATIONS
AA Activated alumina
AC Activated carbon
ASR Annual Status Report
As(III) Trivalent arsenic, common inorganic formin water is arsenite, H3AsO3
As(V) Pentavalent arsenic, common inorganicform in water is arsenate, H2AsO4
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BDAT best demonstrated available technology
BTEX Benzene, toluene, ethylbenzene, andxylene
CCA Chromated copper arsenate
CERCLA Comprehensive Environmental Response,Compensation, and Liability Act
CERCLIS 3 CERCLA Information System
CLU-IN EPA’s CLeanUp INformation system
CWS Community Water System
cy Cubic yard
DDT Dichloro-diphenyl-trichloroethane
DI Deionized
DOC Dissolved organic carbon
DoD Department of Defense
DOE Department of Energy
EDTA Ethylenediaminetetraacetic acid
EPA U.S. Environmental Protection Agency
EPT Extraction Procedure Toxicity Test
FRTR Federal Remediation TechnologiesRoundtable
ft feet
GJO DOE’s Grand Junction Office
gpd gallons per day
gpm gallons per minute
HTMR High temperature metals recovery
MCL Maximum Contaminant Level(enforceable drinking water standard)
MF Microfiltration
MHO Metallurgie-Hoboken-Overpelt
mgd million gallons per day
mg/kg milligrams per kilogram
mg/L milligrams per Liter
NF Nanofiltration
NPL National Priorities List
OCLC Online Computer Library Center
ORD EPA Office of Research and Development
OU Operable Unit
PAH Polycyclic aromatic hydrocarbons
PCB Polychlorinated biphenyls
POTW Publicly owned treatment works
PRB Permeable reactive barrier
RCRA Resource Conservation and Recovery Act
Redox Reduction/oxidation
RO Reverse osmosis
ROD Record of Decision
SDWA Safe Drinking Water Act
SMZ surfactant modified zeolite
SNAP Superfund NPL Assessment Program
S/S Solidification/Stabilization
SVOC Semivolatile organic compounds
TCLP Toxicity Characteristic LeachingProcedure
TNT 2,3,6-trinitrotoluene
TWA Total Waste Analysis
UF Ultrafiltration
VOC Volatile organic compounds
WET Waste Extraction Test
ZVI Zero valent iron
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FOREWORD
The purpose of this report is to provide a synopsis of the availability, performance, and cost of 13 arsenic treatmenttechnologies for soil, water, and waste. Its intended audience includes hazardous waste site managers; generatorsand treaters of arsenic-contaminated waste and wastewater; owners and operators of drinking water treatment plants;regulators; and the interested public.
There is a growing need for cost-effective arsenic treatment. The presence of arsenic in the environment can pose arisk to human health. Historical and current industrial use of arsenic has resulted in soil and groundwatercontamination that may require remediation. Some industrial wastes and wastewaters currently being producedrequire treatment to remove or immobilize arsenic. In addition, arsenic must be removed from some sources ofdrinking water before they can be used.
Recently the EPA reduced the maximum contaminant level (MCL) for arsenic in drinking water from 0.050 mg/L to 0.010 mg/L, effective in 2006. Current and future drinking water and groundwater treatment systems will requirebetter-performing technologies to achieve this lower level. EPA recently prepared an issue paper, ProvenAlternatives for Aboveground Treatment of Arsenic in Groundwater, that describes four technologies(precipitation/coprecipitation, adsorption, ion exchange, and membrane filtration) for removing arsenic from water. The paper also discusses special considerations for retrofitting systems to meet the lower arsenic drinking waterstandard. This information is incorporated in this report, as well as details on emerging approaches, such asphytoremediation and electrokinetics, for addressing arsenic in groundwater.
This report is intended to be used as a screening tool for arsenic treatment technologies. It provides descriptions ofthe theory, design, and operation of the technologies; information on commercial availability and use; performanceand cost data, where available; and a discussion of factors affecting effectiveness and cost. As a technologyoverview document, the information can serve as a starting point for identifying options for arsenic treatment. Thefeasibility of particular technologies will depend heavily on site-specific factors, and final treatment and remedydecisions will require further analysis, expertise, and possibly treatability studies.
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NOTICE AND DISCLAIMER
Preparation of this report has been funded by the U.S. Environmental Protection Agency (EPA) TechnologyInnovation Office (TIO) under Contract Numbers 68-W-99-003 and 68-W-02-034. Information in this report isderived from numerous sources (including personal communications with experts in the field), some of which havebeen peer-reviewed. This study has undergone EPA and external review by subject-matter experts. Mention oftrade names or commercial products does not constitute endorsement or recommendation for use.
A PDF version of Arsenic Treatment Technologies for Soil, Waste, and Water, is available for viewing ordownloading from the Hazardous Waste Cleanup Information (CLU-IN) system web site at http://clu-in.org/arsenic. A limited number of printed copies are available free of charge, and may be ordered via the web site, by mail or byfacsimile from:
U.S. EPA/National Service Center for Environmental Publications (NSCEP)P.O. Box 42419Cincinnati, OH 45242-2419Telephone: (513) 489-8190 or (800) 490-9198Fax: (513) 489-8695
ACKNOWLEDGMENTS
Special acknowledgment is given to the federal and state staff and other remediation professionals for providinginformation for this document. Their cooperation and willingness to share their expertise on arsenic treatmenttechnologies encourages their application at other sites. Contributors to the report included: U.S. EPA Office ofGroundwater and Drinking Water; U.S. EPA National Risk Management Research Laboratory; U.S. EPA Office ofEmergency and Remedial Response; U.S. EPA Office of Solid Waste; U.S. EPA Region I; U.S. EPA Region III;David Ellis and Hilton Frey of Dupont; Richard M. Markey and James C. Redwine of Southern Company; James D.Navratil of Clemson University; Robert G. Robbins of the Aquamin Science Consortium International; CindySchreier of Prima Environmental; David Smythe of the University of Waterloo; Enid J. "Jeri" Sullivan of the LosAlamos National Laboratory; and G. B. Wickramanayake of the Battelle Memorial Institute.
PART IOVERVIEW AND FINDINGS
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1.0 EXECUTIVE SUMMARY
This report contains information on the current state ofthe treatment of soil, waste, and water containingarsenic, a contaminant that can be difficult to treat andmay cause a variety of adverse health effects in humans. This information can help managers at sites witharsenic-contaminated media, generators of arsenic-contaminated waste and wastewater, and owners andoperators of drinking water treatment plants to:
• Identify proven and effective arsenic treatmenttechnologies
• Screen those technologies based on effectiveness,treatment goals, application-specific characteristics,and cost
• Apply experience from sites with similar treatmentchallenges
• Find more detailed arsenic treatment information
Arsenic is in many industrial raw materials, products,and wastes, and is a contaminant of concern in soil andgroundwater at many remediation sites. Becausearsenic readily changes valence state and reacts to formspecies with varying toxicity and mobility, effectivetreatment of arsenic can be difficult. Treatment canresult in residuals that, under some environmentalconditions, become more toxic and mobile. In addition,the recent reduction in the maximum contaminant level(MCL) for arsenic in drinking water from 0.050 to0.010 mg/L will impact technology selection andapplication for drinking water treatment, and couldresult in lower treatment goals for remediation ofarsenic-contaminated sites. A lower treatment goal mayaffect the selection, design, and operation of arsenictreatment systems.
This report identifies 13 technologies to treat arsenic insoil, waste, and water. Table 1.1 provides briefdescriptions of these technologies. Part II of this reportcontains more detailed information about eachtechnology.
Table 1.2 summarizes the technology applications andperformance identified for this report. The tableprovides information on the number of projects that metcertain current or revised regulatory standards,including the RCRA regulatory threshold for thetoxicity characteristic of 5.0 mg/L leachable arsenic, theformer MCL of 0.050 mg/L arsenic, and the revisedMCL of 0.010 mg/L. The table presents information forsolid-phase media (soil and waste) and aqueous media(water, including groundwater, surface water, drinkingwater, and wastewater). The technologies used to treatone type of media typically show similar applicabilityand effectiveness when applied to a similar media. Forexample, technologies used to treat arsenic in soil haveabout the same applicability and effectiveness, and areused with similar frequency, to treat solid industrial
wastes. Similarly, technologies used to treat one typeof water (e.g., groundwater) typically show similarapplicability, effectiveness, and frequency of use whentreating another type of water (e.g., surface water).
Soil and Waste Treatment Technologies
In general, soil and waste are treated by immobilizingthe arsenic using solidification/stabilization (S/S). Thistechnology is usually capable of reducing theleachability of arsenic to below 5.0 mg/L (as measuredby the toxicity characteristic leaching procedure[TCLP]), which is a common treatment goal for soil andwaste. S/S is generally the least expensive technologyfor treatment of arsenic-contaminated soil and waste.
Pyrometallurgical processes are applicable to some soiland waste from metals mining and smelting industries. However, the information gathered for this report didnot indicate any current users of these technologies forarsenic in the U. S. Other soil and waste treatmenttechnologies, including vitrification, soil washing/acidextraction, and soil flushing, have had only limitedapplication to the treatment of arsenic. Although thesetechnologies may be capable of effectively treatingarsenic, data on performance are limited. In addition,these technologies tend to be more expensive than S/S.
Water Treatment Technologies
Based on the information gathered for this report, precipitation/coprecipitation is frequently used to treatarsenic-contaminated water, and is capable of treating awide range of influent concentrations to the revisedMCL for arsenic. The effectiveness of this technologyis less likely to be reduced by characteristics andcontaminants other than arsenic, compared to otherwater treatment technologies. It is also capable oftreating water characteristics or contaminants other thanarsenic, such as hardness or heavy metals. Systemsusing this technology generally require skilledoperators; therefore, precipitation/coprecipitation ismore cost effective at a large scale where labor costscan be spread over a larger amount of treated waterproduced.
The effectiveness of adsorption and ion exchange forarsenic treatment is more likely than precipitation/coprecipitation to be affected by characteristics andcontaminants other than arsenic. However, thesetechnologies are capable of treating arsenic to therevised MCL. Small capacity systems using thesetechnologies tend to have lower operating andmaintenance costs, and require less operator expertise. Adsorption and ion exchange tend to be used moreoften when arsenic is the only contaminant to betreated, for relatively smaller systems, and as apolishing technology for the effluent from largersystems. Membrane filtration is used less frequently
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because it tends to have higher costs and produce alarger volume of residuals than other arsenic treatmenttechnologies.
Innovative Technologies
Innovative technologies, such as permeable reactivebarriers, biological treatment, phytoremediation, andelectrokinetic treatment, are also being used to treatarsenic-contaminated soil, waste, and water. Thereferences identified for this report contain informationabout only a few applications of these technologies atfull scale. However, they may be used to treat arsenicmore frequently in the future. Additional treatment dataare needed to determine their applicability andeffectiveness.
Permeable reactive barriers are used to treatgroundwater in situ. This technology tends to havelower operation and maintenance costs than ex situ(pump and treat) technologies, and typically requires atreatment time of many years. This report identifiedthree full-scale applications of this technology, buttreatment data were available for only one application. In that application, a permeable reactive barrier istreating arsenic to below the revised MCL.
Biological treatment for arsenic is used primarily totreat water above-ground in processes that usemicroorganisms to enhance precipitation/coprecipitation. Bioleaching of arsenic from soil hasalso been tested on a bench scale. This technology mayrequire pretreatment or addition of nutrients and othertreatment agents to encourage the growth of keymicroorganisms.
Phytoremediation is an in situ technology intended to beapplicable to soil, waste, and water. This technologytends to have low capital, operating, and maintenancecosts relative to other arsenic treatment technologiesbecause it relies on the activity and growth of plants. However, the effectiveness of this technology may bereduced by a variety of factors, such as the weather, soiland groundwater contaminants and characteristics, thepresence of weeds or pests, and other factors. Thereferences identified for this report containedinformation on one full-scale application of thistechnology to arsenic treatment.
Electrokinetic treatment is an in situ technologyintended to be applicable to soil, waste and water. Thistechnology is most applicable to fine-grained soils, suchas clays. The references identified for this reportcontained information on one full-scale application ofthis technology to arsenic treatment.
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Table 1.1Arsenic Treatment Technology Descriptions
Technology DescriptionTechnologies for Soil and Waste TreatmentSolidification/Stabilization
Physically binds or encloses contaminants within a stabilized mass and chemically reduces thehazard potential of a waste by converting the contaminants into less soluble, mobile, or toxicforms.
Vitrification High temperature treatment that reduces the mobility of metals by incorporating them into achemically durable, leach resistant, vitreous mass. The process also may cause contaminantsto volatilize, thereby reducing their concentration in the soil and waste.
Soil Washing/Acid Extraction
An ex situ technology that takes advantage of the behavior of some contaminants topreferentially adsorb onto the fines fraction of soil. The soil is suspended in a wash solutionand the fines are separated from the suspension, thereby reducing the contaminantconcentration in the remaining soil.
PyrometallurgicalRecovery
Uses heat to convert a contaminated waste feed into a product with a high concentration of thecontaminant that can be reused or sold.
In Situ SoilFlushing
Extracts organic and inorganic contaminants from soil by using water, a solution of chemicalsin water, or an organic extractant, without excavating the contaminated material itself. Thesolution is injected into or sprayed onto the area of contamination, causing the contaminantsto become mobilized by dissolution or emulsification. After passing through thecontamination zone, the contaminant-bearing flushing solution is collected and pumped to thesurface for treatment, discharge, or reinjection.
Technologies for Water TreatmentPrecipitation/Coprecipitation
Uses chemicals to transform dissolved contaminants into an insoluble solid or form anotherinsoluble solid onto which dissolved contaminants are adsorbed. The solid is then removedfrom the liquid phase by clarification or filtration.
MembraneFiltration
Separates contaminants from water by passing it through a semi-permeable barrier ormembrane. The membrane allows some constituents to pass, while blocking others.
Adsorption Concentrates solutes at the surface of a sorbent, thereby reducing their concentration in thebulk liquid phase. The adsorption media is usually packed into a column. As contaminatedwater is passed through the column, contaminants are adsorbed.
Ion Exchange Exchanges ions held electrostatically on the surface of a solid with ions of similar charge in asolution. The ion exchange media is usually packed into a column. As contaminated water ispassed through the column, contaminants are removed.
PermeableReactive Barriers
Walls containing reactive media that are installed across the path of a contaminatedgroundwater plume to intercept the plume. The barrier allows water to pass through while themedia remove the contaminants by precipitation, degradation, adsorption, or ion exchange.
Technologies for Soil, Waste, and Water TreatmentElectrokineticTreatment
Based on the theory that a low-density current applied to soil will mobilize contaminants inthe form of charged species. A current passed between electrodes inserted into the subsurfaceis intended to cause water, ions, and particulates to move through the soil. Contaminantsarriving at the electrodes can be removed by means of electroplating or electrodeposition,precipitation or coprecipitation, adsorption, complexing with ion exchange resins, or bypumping of water (or other fluid) near the electrode.
Phytoremediation Involves the use of plants to degrade, extract, contain, or immobilize contaminants in soil,sediment, and groundwater.
BiologicalTreatment
Involves the use of microorganisms that act directly on contaminant species or create ambientconditions that cause the contaminant to leach from soil or precipitate/coprecipitate fromwater.
1 - 4
Tab
le 1
.2Su
mm
ary
of K
ey D
ata
and
Find
ings
Tec
hnol
ogy
Med
ia T
reat
edN
umbe
r of
App
licat
ions
Iden
tifie
da
(Num
ber
with
Per
form
ance
Dat
a)So
il an
d W
aste
Wat
er
Soil
and
Was
teW
ater
Ben
chSc
ale
Pilo
tSc
ale
Full
Scal
eT
otal
Num
ber
ofA
pplic
atio
nsA
chie
ving
<5.
0m
g/L
Lea
chab
leA
rsen
ic
Num
ber
ofA
pplic
atio
nsA
chie
ving
<0.
050
mg/
L A
rsen
ic
Num
ber
ofA
pplic
atio
nsA
chie
ving
<0.0
10 m
g/L
Ars
enic
Solid
ifica
tion/
Stab
iliza
tion
g-
NC
10 (1
0)34
(32)
44 (4
2)37
--
Vitr
ifica
tion
g-
NC
10 (5
)6
(2)
16 (7
)7
--
Soil
Was
hing
/Aci
d Ex
tract
ion
g-
2 (0
)3
(0)
4 (0
)9
(0)
--
-
Pyro
met
allu
rgic
al R
ecov
ery
g-
00
4 (2
)4
(2)
2-
-
In S
itu S
oil F
lush
ing
g-
02
(0)
2 (0
)4
(0)
--
-
Prec
ipita
tion/
Cop
reci
pita
tion
-g
NC
24 (2
2)45
(30)
68 (5
1)-
3619
Mem
bran
e Fi
ltrat
ion
-g
6 (0
)25
(2)
2 (2
)33
(4)
-4
2
Ads
orpt
ion
-g
NC
7 (4
)14
(8)
21 (1
2)-
127
Ion
Exch
ange
-g
NC
07
(4)
7 (4
)-
32
Perm
eabl
e R
eact
ive
Bar
riers
-g
5 (4
)2
(1)
3 (1
)10
(6)
-6
4
Elec
troki
netic
sg
g3
(0)
3 (1
)1
(0)
7 (1
)-
10
Phyt
orem
edia
tion
gg
4 (0
)2
(0)
1 (0
)7
(0)
--
-
Bio
logi
cal T
reat
men
tg
g1
3 (2
)1
(0)
5 (2
)-
10
aA
pplic
atio
ns w
ere
iden
tifie
d th
roug
h a
sear
ch o
f ava
ilabl
e te
chni
cal l
itera
ture
(See
Sec
tions
2.9
and
2.1
0).
The
num
ber o
f app
licat
ions
incl
ude
only
thos
eid
entif
ied
durin
g th
e pr
epar
atio
n of
this
repo
rt, a
nd a
re n
ot c
ompr
ehen
sive
. Li
mite
d in
form
atio
n on
trea
tmen
t of i
ndus
trial
was
tes a
nd w
aste
wat
ers w
asid
entif
ied,
ther
efor
e th
e ta
ble
may
not
be
repr
esen
tativ
e of
thes
e ty
pes o
f app
licat
ions
.N
C =
Dat
a no
t col
lect
ed
! =
Not
app
licab
leSo
urce
: Ada
pted
from
dat
a in
Sec
tions
4.0
to 1
6.0
of th
is re
port
2 - 1
2.0 INTRODUCTION
2.1 Who Needs to Know about Arsenic TreatmentTechnologies?
This report was prepared to provide information on thecurrent state of arsenic treatment for soil, waste, andwater. The report may be used to:
• Identify proven and effective arsenic treatmenttechnologies
• Screen those technologies based on effectiveness,treatment goals, application-specific characteristics,and cost
• Apply experience from sites with similar treatmentchallenges
• Find more detailed arsenic treatment information
The report may be used by remediation site managers,hazardous waste generators (for example, wood treaters,herbicide manufacturers, mine and landfill operators),drinking water treatment plant designers and operators,and the general public to help screen arsenic treatmentoptions.
Arsenic is a common inorganic element found widely inthe environment. It is in many industrial products,wastes, and wastewaters, and is a contaminant ofconcern at many remediation sites. Arsenic-contaminated soil, waste, and water must be treated byremoving the arsenic or immobilizing it. Becausearsenic readily changes valence states and reacts toform species with varying toxicity and mobility,effective, long-term treatment of arsenic can bedifficult. In some disposal environments arsenic hasleached from arsenic-bearing wastes at highconcentrations (Ref. 2.11).
Recently, the EPA reduced the maximum contaminantlevel (MCL) for arsenic in drinking water from 0.050mg/L to 0.010 mg/L, effective in 2006 (Ref. 2.9). Drinking water suppliers may need to add newtreatment processes or retrofit existing treatmentsystems to meet the revised MCL. In addition, it mayaffect Superfund remediation sites and other sites thatbase cleanup goals on the arsenic drinking water MCL. This report provides information needed to help meetthe challenges of arsenic treatment.
2.2 Background
Where Does Arsenic Come From?
Arsenic occurs naturally in rocks, soil, water, air,plants, and animals. Natural activities such as volcanicaction, erosion of rocks, and forest fires, can releasearsenic into the environment. Industrial productscontaining arsenic include wood preservatives, paints,
dyes, pharmaceuticals, herbicides, and semi-conductors. The man-made sources of arsenic in theenvironment include mining and smelting operations;agricultural applications; burning of fossil fuels andwastes; pulp and paper production; cementmanufacturing; and former agricultural uses of arsenic (Ref. 2.1).
What Are the Health Effects of Arsenic?
Many studies document the adverse health effects inhumans exposed to inorganic arsenic compounds. Adiscussion of those effects is available in the followingdocuments:
• National Primary Drinking Water Regulations;Arsenic and Clarifications to Compliance and NewSource Contaminants Monitoring (66 FR 6976 /January 22, 2001) (Ref. 2.1)
• The Agency for Toxic Substances and DiseaseRegistry (ATSDR) ToxFAQsTM for Arsenic (Ref.2.13).
How Does Arsenic Chemistry Affect Treatment?
Arsenic is a metalloid or inorganic semiconductor thatcan form inorganic and organic compounds. It occurswith valence states of -3, 0, +3 (arsenite), and +5(arsenate). However, the valence states of -3 and 0occur only rarely in nature. This discussion of arsenicchemistry focuses on inorganic species of As(III) andAs(V). Inorganic compounds of arsenic includehydrides (e.g., arsine), halides, oxides, acids, andsulfides (Ref. 2.4).
The toxicity and mobility of arsenic varies with itsvalence state and chemical form. Arsenite and arsenateare the dominant species in surface water and sea water,and organic arsenic species can be found in natural gasand shale oil (Ref. 2.12). Different chemicalcompounds containing arsenic exhibit varying degreesof toxicity and solubility.
Arsenic readily changes its valence state and chemicalform in the environment. Some conditions that mayaffect arsenic valence and speciation include (Ref. 2.7):
• pH - in the pH range of 4 to 10, As(V) speciesare negatively charged in water, and thepredominant As(III) species is neutral incharge
• redox potential• the presence of complexing ions, such as ions
of sulfur, iron, and calcium• microbial activity
Adsorption-desorption reactions can also affect themobility of arsenic in the environment. Clays,
2 - 2
carbonaceous materials, and oxides of iron, aluminum,and manganese are soil components that may participatein adsorptive reactions with arsenic (Ref. 2.7).
The unstable nature of arsenic species may make itdifficult to treat or result in treated wastes whosetoxicity and mobility can change under someenvironmental conditions. Therefore, the successfultreatment and long-term disposal of arsenic requires anunderstanding of arsenic chemistry and the disposalenvironment.
2.3 How Often Does Arsenic Occur in DrinkingWater?
Arsenic is a fairly common environmental contaminant.Both groundwater (e.g., aquifers) and surface water(e.g., lakes and rivers) sources of drinking water cancontain arsenic. The levels of arsenic are typicallyhigher in groundwater sources. Arsenic levels ingroundwater tend to vary geographically. In the U.S.,Western states (AK, AZ, CA, ID, NV, OR, UT, andWA) tend to have the highest concentrations (>0.010mg/L), while states in the North Central (MT, ND, SD,WY), Midwest Central (IL, IN, IA, MI, MN, OH, andWI), and New England (CT, MA, ME, NH, NJ, NY, RI,and VT) regions tend to have low to moderateconcentrations (0.002 to 0.010 mg/L). However, someportions of these areas may have no detected arsenic indrinking water. Other regions of the U.S. may haveisolated areas of high concentration. EPA estimates that4,000 drinking water treatment systems may requireadditional treatment technologies, a retrofit of existingtreatment technologies, or other measures to achieve therevised MCL for arsenic. An estimated 5.4% ofcommunity water systems (CWSs) using groundwateras a drinking water source and 0.7% of CWSs usingsurface water have average arsenic levels above 0.010mg/L. (Ref. 2.1)
2.4 How Often Does Arsenic Occur at HazardousWaste Sites?
Hazardous waste sites fall under several clean-upprograms, such as Superfund, Resource Conservationand Recovery Act (RCRA) corrective actions, and statecleanup programs. This section contains informationon the occurrence and treatment of arsenic at NationalPriorities List (NPL) sites, known as Superfund sites.Information on arsenic occurrence and treatment atSuperfund sites was complied from the CERCLIS 3database (Ref. 2.3), the Superfund NPL AssessmentProgram (SNAP) database, and the database supporting
the document "Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition)" (Ref.2.8). The information sources identified for this reportdid not contain information on arsenic occurrence andtreatment at RCRA corrective action and state cleanupprogram sites.
Table 2.1 lists the number of Superfund sites witharsenic as a contaminant of concern by media. Groundwater and soil were the most common mediacontaminated with arsenic at 380 and 372 sites,respectively. The number of sites in Table 2.1 exceedsthe number of total sites with arsenic contamination (568) because each site may have more than one type ofmedia contaminated with arsenic.
Table 2.1Number of Superfund Sites with Arsenic as a
Contaminant of Concern by Media
Media Type Number of Sites
Groundwater 380
Soil 372
Sediment 154
Surface Water 86
Debris 77
Sludge 45
Solid Waste 30
Leachate 24
Other 21
Liquid Waste 12
Air 8
Residuals 1
Source: Ref. 2.3
Arsenic occurs frequently at NPL sites. Figure 2.1shows the most common contaminants of concernpresent at Superfund sites for which a Record ofDecision (ROD) has been signed, through FY 1999, themost recent year for which such information isavailable. Arsenic is the second most commoncontaminant of concern (after lead), occurring at 568sites (47% of all sites on the NPL with RODs).
2 - 3
LeadArsenic
Benzene
ChromiumToluene
Cadmium ZincXylenes
Vinyl chlorideNickel
1,1,1-TCA
Trichloroethylene
352357373375382384425
457
518
591568
529
0
100
200
300
400
500
600
700N
umbe
r of
Site
s
LeadArsenic
Benzene
ChromiumToluene
Cadmium ZincXylenes
Vinyl chlorideNickel
1,1,1-TCA
Trichloroethylene
352357373375382384425
457
518
591568
529
0
100
200
300
400
500
600
700N
umbe
r of
Site
s
Figure 2.1Top Twelve Contaminants of Concern at Superfund Sites
Source: Ref. 2.3
Table 2.2 lists the number of Superfund sites witharsenic as a contaminant of concern by site type. Themost common site types were landfills and otherdisposal facilities, chemicals and allied products, andlumber and wood products. Some sites may have morethan one site type.
Figure 2.2 shows the use of treatment technologies toaddress arsenic at Superfund sites. These projects maybe planned, ongoing, or completed. Solidification/stabilization was the most common treatmenttechnology for soil and waste, used in 45 projects totreat arsenic. The most common treatment technologyfor water was precipitation/coprecipitation, which isknown to have been used in nine projects.
More detail on these applications is provided in thetechnology-specific sections (Sections 4.0 through16.0). Information in Figure 2.2 on the treatment ofcontaminant sources (i.e., contaminated soil, sludge,sediment, or other environmental media excludinggroundwater) and in situ groundwater treatment isbased on a detailed review of RODs and contacts withRPMs. A similar information source for pump and treattechnologies (precipitation/coprecipitation, membranefiltration, adsorption, ion exchange) for groundwatercontaining arsenic at Superfund Sites was not available.
2 - 4
100
42
50
92121
45
PhytoremediationElectrokinetics
Biological TreatmentPermeable Reactive Barriers
Ion ExchangeAdsorption
Membrane FiltrationPrecipitation/Coprecipitation
In Situ Soil FlushingPyrometallurgical Recovery
Soil Washing/Acid ExtractionVitrification
Solidification/Stabilization
Tre
atm
ent T
echn
olog
y
100
42
50
92121
45
100
42
50
92121
45
PhytoremediationElectrokinetics
Biological TreatmentPermeable Reactive Barriers
Ion ExchangeAdsorption
Membrane FiltrationPrecipitation/Coprecipitation
In Situ Soil FlushingPyrometallurgical Recovery
Soil Washing/Acid ExtractionVitrification
Solidification/Stabilization
PhytoremediationElectrokinetics
Biological TreatmentPermeable Reactive Barriers
Ion ExchangeAdsorption
Membrane FiltrationPrecipitation/Coprecipitation
In Situ Soil FlushingPyrometallurgical Recovery
Soil Washing/Acid ExtractionVitrification
Solidification/Stabilization
Tre
atm
ent T
echn
olog
y
Table 2.2Number of Superfund Sites with Arsenic as a
Contaminant of Concern by Site Type
Site TypeNumber of
Sitesb
Landfills and Other Disposal 209
Chemicals and Allied Products 42
Lumber and Wood Products 33
Groundwater Plume Site 26
Metal Fabrication and Finishing 20
Batteries and Scrap Metal 18
Military and Other Ordnance 18
Transportation Equipment 15
Primary Metals Processing 14
Chemicals and Chemical Waste 12
Ordnance Production 12
Electrical Equipment 11
Radioactive Products 9
Product Storage and Distribution 8
Waste Oil and Used Oil 8
Metals 6
Drums and Tanks 6
Transportation 5
Research and Development 5
Othera 104
Sources: Ref. 2.3, 2.15
a Includes site types with fewer than 5 sites, siteswhose site types were identified as “other”or“multiple”, and unspecified industrial wastefacilities.
b Some sites have more than one site type.
Figure 2.2Number of Applications of Arsenic Treatment
Technologies at Superfund Sitesa
a Information on the application of groundwaterpump and treat technologies, includingprecipitation/coprecipitation, membrane filtration,adsorption, and ion exchange, is based on availabledata and is not comprehensive.
2.5 What Are the Structure and Contents of theReport?
Part I of this report, the Overview and Findings,contains an Executive Summary, an Introduction, and aComparison of Arsenic Treatment Technologies. ThisIntroduction describes the purpose of the report,presents background information, and summarizes themethodology used to gather and analyze data. The"Comparison of Technologies" Section (3.0) analyzesand compares the data gathered.
Part II of this report contains 13 sections, eachsummarizing the available information for an arsenictreatment technology. Each summary includes a briefdescription of the technology, information about how itis used to treat arsenic, its status and scale, andavailable cost and performance data, including theamount and type of soil, waste, and water treated and asummary of the results of analyses of untreated soil,waste, and water and treatment residuals for total andleachable arsenic concentrations. The technologysummaries are organized as follows: the technologiestypically used to treat soil and waste appear first, in theorder of their frequency of full-scale applications,followed by those typically used for water in the sameorder, and then by those used to treat soil, waste, andwater.
2 - 5
2.6 What Technologies and Media Are Addressed inthe Report?
This report provides information on the 13 technologieslisted in Table 1.1. These technologies have been usedat full scale for the treatment of arsenic in soil, waste,and water. For the purposes of this report, the term“soil” includes soil, debris, sludge, sediments, and othersolid-phase environmental media. Waste includes non-hazardous and hazardous solid waste generated byindustry. Water includes groundwater, drinking water,non-hazardous and hazardous industrial wastewater,surface water, mine drainage, and leachate.
2.7 How Is Technology Scale Defined?
This report includes available information on bench-,pilot- and full-scale applications for the 13technologies. Full-scale projects include those usedcommercially to treat industrial wastes and those usedto remediate an entire area of contamination. Pilot-scale projects are usually conducted in the field to testthe effectiveness of the technology on a specific soil,waste, and water or to obtain information for scaling atreatment system up to full scale. Bench-scale projectsare conducted on a small scale, usually in a laboratoryto evaluate the technology’s ability to treat soil, waste,and water. These often occur during the early phases oftechnology development.
The report focuses on full- and pilot-scale data. Bench-scale data are presented only when less than 5 full-scaleapplications of a technology were identified. For thetechnologies with at least 5 identified full-scaleapplications (solidification/stabilization, vitrification,precipitation/coprecipitation, adsorption, and ionexchange), the report does not include bench-scale data.
2.8 How Are Treatment Trains Addressed?
Treatment trains consist of two or more technologiesused together, either integrated into a single process oroperated as a series of treatments in sequence. Thetechnologies in a train may treat the same contaminant. The information gathered for this report included manyprojects that used treatment trains. A commontreatment train used for arsenic in water includes anoxidation step to change arsenic from As(III) to its lesssoluble As(V) state, followed by precipitation/coprecipitation and filtration to remove the precipitate.
Some trains are employed when one technology alone isnot capable of treating all of the contaminants. Forexample, at the Baird and McGuire Superfund Site(Table 9.1), an above-ground system consisting of airstripping, metals precipitation, and activated carbonadsorption was used to treat groundwater contaminatedwith volatile organic compounds (VOCs), arsenic, and
semivolatile organic compounds (SVOCs). In thistreatment train the air stripping was intended to treatVOCs, the precipitation, arsenic, and the activatedcarbon adsorption, SVOCs and any remaining VOCs.
In many cases, the available information does notspecify the technologies within the train that areintended to treat arsenic. Influent and effluentconcentrations, where available, often were providedfor the entire train, and not the individual components. In such cases, engineering judgement was used toidentify the technology that treated arsenic. Forexample, at the Greenwood Chemical Superfund site(Table 9.1), a treatment train consisting of metalsprecipitation, filtration, UV oxidation and carbonadsorption was used to treat groundwater contaminatedwith arsenic, VOCs, halogenated VOCs, and SVOCs. The precipitation and filtration were assumed to removearsenic, and the UV oxidation and carbon adsorptionwere assumed to have only a negligible effect on thearsenic concentration.
Where a train included more than one potential arsenictreatment technology, all arsenic treatment technologieswere assumed to contribute to arsenic treatment, unlessavailable information indicated otherwise. Forexample, at the Higgins Farm Superfund site, arsenic-contaminated groundwater was treated withprecipitation and ion exchange (Tables 9.1 and 12.1). Information about this treatment is presented in both theprecipitation/coprecipitation (Section 9.0) and ionexchange (Section 12.0) sections.
Activated carbon adsorption is most commonly used totreat organic contaminants. This technology isgenerally ineffective on As(III) (Ref. 2.14). Wheretreatment trains included activated carbon adsorptionand another arsenic treatment technology, it wasassumed that activated carbon adsorption did notcontribute to the arsenic treatment, unless the availableinformation indicated otherwise.
2.9 What Are the Sources of Information for ThisReport?
This report is based on an electronic literature searchand information gathered from readily-available datasources, including:
• Documents and databases prepared by EPA,DOD, and DOE
• Technical literature• Information supplied by vendors of treatment
technologies• Internet sites• Information from technology experts
2 - 6
Most of the information sources used for this reportcontained information about treatments ofenvironmental media and drinking water. Only limitedinformation was identified about the treatment of industrial waste and wastewater containing arsenic. This does not necessarily indicate that treatmentindustrial wastes and wastewater containing arsenicoccurs less frequently, because data on industrialtreatments may be published less frequently.
The authors and reviewers of this report identified theseinformation sources based on their experience witharsenic treatment. In addition, a draft version of thisreport was presented at the U.S. EPA Workshop onManaging Arsenic Risks to the Environment, whichwas held in Denver, Colorado in May of 2001. Information gathered from this workshop and sourcesidentified by workshop attendees were also reviewedand incorporated where appropriate. Proceedings forthis workshop may be available from EPA in 2002.
2.10 What Other Types of Literature WereSearched and Referenced for This Report?
To identify recent and relevant documents containinginformation on the application of arsenic treatmenttechnologies in addition to the sources listed in Section2.9, a literature search was conducted using theDialog® and Online Computer Library Center (OCLC)services. The search was limited to articles publishedbetween January 1, 1998 and May 30, 2001 in order toensure that the information gathered was current. Thesearch identified documents that included in their titlethe words "arsenic," "treatment," and one of a list ofkey words intended to encompass the types of soil,waste, and water containing arsenic that might besubject to treatment. Those key words were:
- Waste - Water- Sludge - Mine- Mining - Debris- Groundwater - Soil- Hazardous - Toxic- Sediment - Slag
The Dialog® search identified 463 references, and theOCLC search found 45 references. Appendix A liststhe title, author, and publication source for each of the508 references identified through the literature search. The search results were reviewed to identify thereferences (in English) that provided information on thetreatment of waste that contains arsenic using one of thetechnologies listed in Table 1.1. Using thismethodology, a total of 44 documents identifiedthrough the literature search were obtained andreviewed in detail to gather information for this report. These documents are identified in Appendix A with anasterisk (*).
2.11 References
2.1 U.S. EPA. National Primary Drinking WaterRegulations; Arsenic and Clarifications toCompliance and New Source ContaminantsMonitoring; Proposed Rule. Federal Register, Vol65, Number 121, p. 38888. June 22, 2000. http://www.epa.gov/safewater/ars/arsenic.pdf.
2.2 U.S. Occupational Safety and HealthAdministration. Occupational Safety and HealthGuidelines for Arsenic, Organic Compounds (asAs). November, 2001.http://www.osha-slc.gov/SLTC/healthguidelines/arsenic/recognition.html.
2.3 U.S. EPA Office of Emergency and RemedialResponse. Comprehensive EnvironmentalResponse Compensation and Liability InformationSystem database (CERCLIS 3). October 2001.
2.4 Kirk-Othmer. "Arsenic and Arsenic Alloys." TheKirk-Othemer Encyclopedia of ChemicalTechnology, Volume 3. John Wiley and Sons,New York. 1992.
2.5 Kirk-Othmer. "Arsenic Compounds" The Kirk-Othemer Encyclopedia of Chemical Technology,Volume 3. John Wiley and Sons, New York. 1992.
2.6 EPA. Treatment Technology Performance andCost Data for Remediation of Wood PreservingSites. Office of Research and Development.EPA-625-R-97-009. October 1997.http://epa.gov/ncepihom.
2.7 Vance, David B. "Arsenic - Chemical Behaviorand Treatment”. October, 2001.http://2the4.net/arsenicart.htm.
2.8 EPA. Treatment Technologies for Site Cleanup: Annual Status Report (Tenth Edition). Office ofSolid Waste and Emergency Response. EPA-542-R-01-004. February 2001. http://clu-in.org.
2.9 U.S. EPA. National Primary Drinking WaterRegulations; Arsenic and Clarifications toCompliance and New Source ContaminantsMonitoring; Final Rule. Federal Register,Volume 66, Number 14, p. 6975-7066. January22, 2001. http://www.epa.gov/sbrefa/documents/pnl14f.pdf
2 - 7
2.10 U.S. EPA Office of Water. Fact Sheet: EPA toImplement 10ppb Standard for Arsenic inDrinking Water. EPA 815-F-01-010. October,2001. http://www.epa.gov/safewater/ars/ars-oct-factsheet.html.
2.11 Federal Register. Land Disposal Restrictions:Advanced Notice of Proposed Rulemaking. Volume 65, Number 118. June 19, 2000. pp.37944 - 37946.http://www.epa.gov/fedrgstr/EPA-WASTE/2000/June/Day-19/f15392.htm
2.12 National Research Council. Arsenic in DrinkingWater. Washington, D.C. National AcademyPress. 1999. http://www.nap.edu/catalog/6444.html
2.13 The Agency for Toxic Substances and DiseaseRegistry (ATSDR): ToxFAQsTM for Arsenic (12).July, 2001. http://www.atsdr.cdc.gov/tfacts2.html.
2.14 U.S. EPA. Cost Analyses for SelectedGroundwater Cleanup Projects: Pump and TreatSystems and Permeable Reactive Barriers, EPA-542-R-00-013, February 2001. http://clu-in.org
2.15 U.S. EPA Office of Emergency and RemedialResponse. Superfund NPL Assessment Program (SNAP) database. April 11, 2002.
3 - 1
Arsenic Treatment Technologies
Soil and Waste Treatment Technologies• Solidification/
Stabilization• Vitrification• Soil Washing/Acid
Extraction
• PyrometallurgicalRecovery
• In Situ Soil Flushing
Water Treatment Technologies• Precipitation/
Coprecipitation• Membrane Filtration• Adsorption
• Ion Exchange• Permeable Reactive
Barriers
Soil, Waste, and Water Treatment Technologies• Electrokinetics• Phytoremediation
• Biological Treatment
3.0 COMPARISON OF ARSENIC TREATMENTTECHNOLOGIES
3.1 What Technologies Are Used to Treat Arsenic?
This report identifies 13 technologies applicable toarsenic-contaminated soil, waste, and water. Technologies are considered applicable if they havebeen used at full scale to treat arsenic.
Table 3.1 summarizes their applicability to arsenic-contaminated media. The media treated by thesetechnologies can be grouped into two generalcategories: soil and waste; and water.
Technologies applicable to one type of soil and wasteare typically applicable to other types. For example,solidification/stabilization has been used to effectivelytreat industrial waste, soil, sludge, and sediment. Similarly, technologies applicable to one type of waterare generally applicable to other types. For example,precipitation/coprecipitation has been used toeffectively treat industrial wastewaters, groundwater,and drinking water.
3.2 What Technologies Are Used Most Often toTreat Arsenic?
This section provides information on the number oftreatment projects identified for each technology andestimates of the relative frequency of their application. Figures 3.1 to 3.3 show the number of treatmentprojects identified for each technology. Figure 3.1shows the number for technologies applicable to soiland waste based on available data. The most frequently
used technology for soil and waste containing arsenic issolidification/stabilization. The available data showthat this technology can effectively meet regulatorycleanup levels, is commercially available to treat bothsoil and waste, is usually less expensive, and generatesa residual that typically does not require furthertreatment prior to disposal.
Other arsenic treatment technologies for soil and wasteare typically used for specific applications. Vitrification may be used when a combination ofcontaminants are present that cannot be effectivelytreated using solidification/stabilization. It has alsobeen used when the vitrification residual could be soldas a commercial product. However, vitrificationtypically requires large amounts of energy, can be moreexpensive than S/S, and may generate off-gassescontaining arsenic.
Soil washing/acid extraction is used to treat soilprimarily. However, it is not applicable to all types ofsoil or to waste. Pyrometallurgical treatment has beenused primarily to recycle arsenic from industrial wastescontaining high concentrations of arsenic from metalsrefining and smelting operations. These technologiesmay not be applicable to soil and waste containing lowconcentrations of arsenic. In situ soil flushing treatssoil in place, eliminating the need to excavate soil. However, no performance data were identified for thelimited number of full-scale applications of thistechnology to arsenic.
Figure 3.2 shows the number of treatment projectsidentified for technologies applicable to water. Forwater containing arsenic, the most frequently usedtechnology is precipitation/coprecipitation. Based onthe information gathered for this report, precipitation/coprecipitation is frequently used to treat arsenic-contaminated water, and is capable of treating a widerange of influent concentrations to the revised MCL forarsenic. The effectiveness of this technology is lesslikely to be reduced by characteristics and contaminantsother than arsenic, compared to other water treatmenttechnologies. It is also capable of treating watercharacteristics or contaminants other than arsenic, suchas hardness or heavy metals. Systems using thistechnology generally require skilled operators;therefore, precipitation/ coprecipitation is more costeffective at a large scale where labor costs can bespread over a larger amount of treated water produced.
The effectiveness of adsorption and ion exchange forarsenic treatment is more likely than precipitation/coprecipitation to be affected by characteristics andcontaminants other than arsenic. However, thesetechnologies are capable of treating arsenic to the
3 - 2
Num
ber
of A
pplic
atio
ns
Stabilization* Acid Extraction Recovery FlushingSolidification/ Vitrification* Soil Washing/ Pyrometallurgical In Situ Soil
58
6 4 4 2
19
103
0 22 0 00
10
20
30
40
50
60
70
FullPilotBench
Num
ber
of A
pplic
atio
ns
Stabilization* Acid Extraction Recovery FlushingSolidification/ Vitrification* Soil Washing/ Pyrometallurgical In Situ Soil
58
6 4 4 2
19
103
0 22 0 00
10
20
30
40
50
60
70
FullPilotBench
FullPilotBench
45
2
15
73
24 25
8
0 26 5
0
5
10
15
20
25
30
35
40
45
50
Precipitation/Coprecipitation*
Membrane Filtration
Adsorption* Ion Exchange* Permeable Reactive Barriers
Num
ber
of A
pplic
atio
ns FullPilotBench
0
45
2
15
73
24 25
8
0 26 5
0
5
10
15
20
25
30
35
40
45
50
Precipitation/Coprecipitation*
Membrane Filtration
Adsorption* Ion Exchange* Permeable Reactive Barriers
Num
ber
of A
pplic
atio
ns FullPilotBench
FullPilotBench
0
Figure 3.1Number of Identified Applications of Arsenic Treatment Technologies for Soil and Waste
* Bench-scale data not collected for this technology.
Figure 3.2Number of Identified Applications of Arsenic Treatment Technologies for Water
* Bench-scale data not collected for this technology.
3 - 3
1 1 1
3
2
33
4
1
0
1
2
3
4
5
Electrokinetics Phytoremediation Biological Treatment
Num
ber
of A
pplic
atio
ns
FullPilotBench
1 1 1
3
2
33
4
1
0
1
2
3
4
5
Electrokinetics Phytoremediation Biological Treatment
Num
ber
of A
pplic
atio
ns
FullPilotBench
FullPilotBench
Figure 3.3Number of Identified Applications of Arsenic Treatment Technologies for Soil, Waste, and Water
revised MCL. Small capacity systems using thesetechnologies tend to have lower operating andmaintenance costs, and require less operator expertise. Adsorption and ion exchange tend to be used moreoften when arsenic is the only contaminant to betreated, for relatively smaller systems, and as apolishing technology for the effluent from largersystems. Membrane filtration is used less frequentlybecause it tends to have higher costs and produce alarger volume of residuals than other arsenic treatmenttechnologies.
Permeable reactive barriers are used to treatgroundwater in situ. This technology tends to havelower operation and maintenance costs than ex situ(pump and treat) technologies, and typically requires atreatment time of many years. This report identifiedthree full-scale applications of this technology, buttreatment data were available for only one application. In that application, a permeable reactive barrier istreating arsenic to below the revised MCL.
Figure 3.3 shows the number of treatment projectsidentified for technologies applicable to soil, waste, andwater. Three arsenic treatment technologies aregenerally applicable to soil, waste, and water:electrokinetics, phytoremediation, and biologicaltreatment. These technologies have been applied inonly a limited number of applications.
Electrokinetic treatment is an in situ technologyintended to be applicable to soil, waste and water. Thistechnology is most applicable to fine-grained soils, suchas clays. The references identified for this report
contained information on one full-scale application ofthis technology to arsenic treatment.
Phytoremediation is an in situ technology intended to beapplicable to soil, waste, and water. This technologytends to have low capital, operating, and maintenancecosts relative to other arsenic treatment technologiesbecause it relies on the activity and growth of plants. However, this technology tends to be less robust. Thereferences identified for this report containedinformation on one full-scale application of thistechnology to arsenic treatment.
Biological treatment for arsenic is used primarily totreat water above-ground in processes that usemicroorganisms to enhance precipitation/coprecipitation. Bioleaching of arsenic from soil hasalso been tested on a bench scale. This technology mayrequire pretreatment or addition of nutrients and othertreatment agents to encourage the growth of keymicroorganisms.
3.3 What Factors Affect Technology Selection forDrinking Water Treatment?
For the treatment of drinking water, technologyselection depends on several of factors, such as existingsystems, the need to treat for other contaminants, andthe size of the treatment system. Although the datacollected for this report indicate thatprecipitation/coprecipitation is the technology mostcommonly used to remove arsenic from drinking water,in the future other technologies may become more
3 - 4
Leaching Procedure Descriptions
Toxicity Characteristic Leaching Procedure(TCLP): The TCLP is used in identifying RCRAhazardous wastes that exhibit the characteristic oftoxicity. In this procedure, liquids are separatedfrom the solid phase of the waste, and the solidphase is then reduced in particle size until it iscapable of passing through a 9.5 mm sieve. Thesolids are then extracted for 18 hours with a solutionof acetic acid equal to 20 times the weight of thesolid phase. The pH of the extraction fluid is afunction of the alkalinity of the waste. Followingextraction, the liquid extract is separated from thesolid phase by filtration. If compatible, the initialliquid phase of the waste is added to the liquidextract and analyzed, otherwise they are analyzedseparately. The RCRA TCLP regulatory thresholdfor arsenic is 5.0 mg/L in the extraction fluid (Ref.3.22).
Extraction Procedure Toxicity Test (EPT): Thisprocedure is similar to the TCLP test, with thefollowing differences:• The extraction period is 24 hours• The extraction fluid is a pH 5 solution of acetic
acid.The EPT was replaced by the TCLP test in March,1990 for purposes of hazardous waste identification,and is therefore no longer widely used (Ref. 3.23)
Waste Extraction Test (WET): The WET is usedin identifying hazardous wastes in California. Thisprocedure is similar to the TCLP, with the followingdifferences• The solid phase is reduced in particle size until it
is capable of passing through a 2 mm sieve., • The waste is extracted for 48 hours • The extraction fluid is a pH 5 solution of sodium
citrate equal to 10 times the weight of the solidphase. The WET regulatory threshold for arsenicis 5.0 mg/L (Ref. 3.24).
common as drinking water treatment facilities modifytheir operations to meet the revised arsenic MCL.
Precipitation/coprecipitation is often used to removecontaminants other than arsenic from drinking water,such as hardness or suspended solids. However, theprecipitation/coprecipitation processes applied todrinking water usually also remove arsenic, or can beeasily modified to do so. Where precipitation/coprecipitation processes are already in place, or areneeded to remove other contaminants, these processesare commonly used to remove arsenic. Whereprecipitation/coprecipitation is not needed to treatdrinking water for other contaminants, treaters may bemore likely to choose another technology, such asadsorption, ion exchange, or reverse osmosis.
In addition, the size of a drinking water treatmentsystem may affect the choice of technology. Precipitation/coprecipitation processes tend to be morecomplex, requiring more unit operations and greateroperational expertise and monitoring, while adsorptionand ion exchange units are usually less complex andrequire less operator expertise and monitoring. Therefore, operators of smaller drinking water treatmentsystems are more likely to select adsorption or ionexchange to treat arsenic instead of precipitation/coprecipitation.
3.4 How Effective Are Arsenic TreatmentTechnologies?
Applications are considered to have performance datawhen analytical data for arsenic are available bothbefore and after treatment. For the technologiesapplicable to soil and waste, Table 1.2 (presented in theExecutive Summary) includes performance data onlyfor those projects with leachable arsenic concentrationdata for the treated soil and waste, and either leachableor total arsenic concentrations for the untreated soil andwaste. Performance data were compared to the RCRATCLP regulatory threshold of 5.0 mg/L (Ref. 3.1). Forthis table, projects that measured leachability with otherprocedures, such as the EPT and the WET, were alsocompared directly to this level. The tables in thetechnology-specific sections (Sections 4.0 to 16.0)identify the leaching procedures used to measureperformance. The text box to the right describes theleaching procedures most frequently identified in theinformation sources used for this report.
For the technologies applicable to water, theperformance was compared to the former MCL of 0.050mg/L, and the revised MCL of 0.010 mg/L (Ref. 3.2). Information was available on relatively few projectsthat have treated arsenic to below 0.010 mg/L. However, this does not necessarily indicate that thesetreatment technologies cannot achieve 0.010 mg/L
arsenic. In many cases, the treatment goal in theprojects was greater than 0.010 mg/L, and in most caseswas the previous arsenic MCL of 0.050 mg/L. In suchcases, the treatment technology may be capable ofmeeting 0.010 mg/L arsenic with modifications to thetreatment technology design or operating parameters.
3.5 What Are Special Considerations forRetrofitting Existing Water TreatmentSystems?
On January 22, 2001, EPA published a revised MCL forarsenic in drinking water that would require public
3 - 5
water suppliers to maintain arsenic concentrations at orbelow 0.010 mg/L by 2006 (Ref. 2.9). Some 4,000drinking water treatment systems may requireadditional treatment technologies, a retrofit of existingtreatment technologies, or other measures to achievethis level (Ref. 2.10). In addition, this revised MCLmay affect Superfund remediation sites and other sitesthat base cleanup goals on the arsenic drinking waterMCL. A lower goal could affect the selection, design,and operation of treatment systems.
Site-specific conditions will determine the type ofchanges needed to meet the revised MCL. Somearsenic treatment systems may be retrofitted, whileother may require new arsenic treatment systems to bedesigned. In addition, treatment to lower arsenicconcentrations could require the use of multipletechnologies in sequence. For example, a site with anexisting metals precipitation/coprecipitation systemmay need to add another technology such as ionexchange to achieve a lower treatment goal.
In some cases, a lower treatment goal might be met bychanging the operating parameters of existing systems. For example, changing the type or amount of treatmentchemicals used, replacing spent treatment media morefrequently, or changing treatment system flow rates canreduce arsenic concentrations in the treatment systemeffluent. However, such changes may increaseoperating costs from use of additional treatmentchemicals or media, use of more expensive treatmentchemicals or media, and from disposal of increasedvolumes of treatment residuals.
Examples of technology-specific modifications that canhelp reduce effluent concentrations of arsenic include:
Precipitation/Coprecipitation• Use of additional treatment chemicals• Use of different treatment chemicals• Addition of another technology to the treatment
train, such as membrane filtration
Adsorption• Addition of an adsorption media bed• Use of a different adsorption media• More frequent replacement or regeneration of
adsorption media• Decrease in the flow rate of water treated• Addition of another treatment technology to the
treatment train, such as membrane filtrationIon Exchange• Addition of an ion exchange bed• Use of a different ion exchange resin• More frequent regeneration or replacement of ion
exchange media• Decrease in the flow rate of water treated
• Addition of another technology to the treatmenttrain, such as membrane filtration
Membrane Filtration• Increase in the volume of reject generated per
volume of water treated• Use of membranes with a smaller molecular
weight cutoff• Decrease in the flow rate of water treated• Addition of another treatment technology to the
treatment train, such as ion exchange
3.6 How Do I Screen Arsenic TreatmentTechnologies?
Table 3.2 at the end of this section is a screening matrixfor arsenic treatment technologies. It can assistdecision makers in evaluating candidate treatmenttechnologies by providing information on relativeavailability, cost, and other factors for each technology. The matrix is based on the Federal RemediationTechnologies Roundtable Technology (FRTR)Treatment Technologies Screening Matrix (Ref. 3.3),but has been tailored to treatment technologies forarsenic in soil, waste, and water. Table 3.2 differs fromthe FRTR matrix by:
• Limiting the scope of the table to the technologiesdiscussed in this report.
• Changing the information based on the narrowscope of this report. For example, the FRTRscreening matrix lists the overall cost ofadsorption as “worse” (triangle symbol) incomparison to other treatment technologies forwater. However, when applied to arsenictreatment, the costs of the technologies discussedin this report may vary based on scale, watercharacteristics, and other factors. Therefore,adsorption costs are not necessarily higher thanthe costs of other technologies discussed in thisreport, and this technology’s overall cost is ratedas “average” (circle symbol) in Table 3.2.
• Adding information about characteristics that canaffect technology performance or cost.
Table 3.2 includes the following information:
• Development Status - The scale at which thetechnology has been applied. “F” indicates thatthe technology has been applied to a site at fullscale. All of the technologies have been appliedat full scale.
• Treatment Trains - “Y” indicates that thetechnology is typically used in combination withother technologies, such as pretreatment or
3 - 6
treatment of residuals (excluding off gas). “N”indicates that the technology is typically usedindependently.
• Residuals Produced - The residuals typically
produced that may require additionalmanagement. “S” indicates production of a solidresidual, “L”, a liquid residual, and “V” a vaporresidual. All of the technologies generate a solidresidual, with the exceptions of soil flushing andmembrane filtration, which generate only liquidresiduals. Vitrification and pyrometallurgicalrecovery produce a vapor residual.
• O&M or Capital Intensive -This indicates themain cost-intensive parts of the system. “O&M”indicates that the operation and maintenance coststend to be high in comparison to othertechnologies. “Cap” indicates that capital coststend to be high in comparison to othertechnologies. “N” indicates neither operation andmaintenance nor capital costs are intensive.
• Availability - The relative number of vendors thatcan design, construct, or maintain the technology. A square indicates more than four vendors; acircle, two to three vendors; and a triangle, fewerthan two vendors. All of the technologies havemore than four vendors with the exception ofpyrometallurgical recycling, bioremediation,electrokinetics, and phytoremediation, which haveless than two.
• System Reliability/Maintainability - The expectedreliability/maintainability of the technology. Asquare indicates high reliability and lowmaintenance; a circle, average reliability andmaintenance; and a triangle, low reliability andhigh maintenance. Biological treatment,electrokinetics, and phytoremediation are ratedlow because of the limited number of applicationsfor those technologies, and indications that someapplications were not effective.
• Overall Cost - Design, construction, and O&Mcosts of the core process that defines eachtechnology, plus the treatment of residuals. Asquare indicates lower overall cost; a circle,average overall cost; and a triangle, higher overallcost. Solidification/stabilization is rated a lowcost technology because it typically uses standardequipment and relatively low cost chemicals andadditives. Phytoremediation is low cost becauseof the low capital expense to purchase and plantphytoremediating species and the low cost tomaintain the plants.
• Characteristics That May Require Pretreatmentor Affect Performance or Cost - The types ofcontaminants or other substances that generallymay interfere with arsenic treatment for eachtechnology. A “T” indicates that the presence ofthe characteristic may interfere with technologyeffectiveness or result in increased costs. Although these contaminants can usually beremoved before arsenic treatment throughpretreatment with another technology, the additionof a pretreatment technology may increase overalltreatment costs and generate additional residualsrequiring disposal. “Other characteristics” aretechnology-specific elements which affecttechnology performance, cost, or both. Thesecharacteristics are described in Sections 4.0through 16.0.
The selection of a treatment technology for a particularsite will depend on many site-specific factors; thus thematrix is not intended to be used as the sole basis fortreatment decisions.
More detailed information on selection and design ofarsenic treatment systems for small drinking watersystems is available in the document “ArsenicTreatment Technology Design Manual for SmallSystems “ (Ref. 3.25).
3.7 What Does Arsenic Treatment Cost?
A limited amount of cost data on arsenic treatment wasidentified for this report. Table 3.3 summarizes thisinformation. In many cases, the cost information wasincomplete. For example, some data were for operatingand maintenance (O&M) costs only, and did not specifythe associated capital costs. In other cases, a cost perunit of soil, waste, and water treated was provided, buttotal costs were not. For some technologies, no arsenic-specific cost data were identified.
The cost data were taken from a variety of sources,including EPA, DoD, other government sources, andinformation from technology vendors. The quality ofthese data varied, with some sources providing detailedinformation about the items included in the costs, whileother sources gave little detail about their basis. Inmost cases, the particular year for the costs were notprovided. The costs in Table 3.3 are the costs reportedin the identified references, and are not adjusted forinflation. Because of the variation in type ofinformation and quality, this report does not provide asummary or interpretation of the costs in Table 3.3.
In general, Table 3.3 only includes costs specifically fortreatment of arsenic. Because arsenic treatment is verywaste- and site-specific, general technology costestimates are unlikely to accurately predict arsenic
3 - 7
treatment costs. However, general technology costestimates were included for three technologies:solidification/stabilization, pyrometallurgical recovery,and phytoremediation.
One of the solidification/stabilization costs listed inTable 3.3 is a general cost for treatment of metals, andis not arsenic-specific. This cost was included becausesolidification/stabilization processes for arsenic aresimilar to those for treatment of metals. The only costfor pyrometallurgical recovery listed in Table 3.3 is ageneral cost for the treatment of volatile metals and isnot arsenic-specific. This cost was included becausearsenic is expected to behave in a manner similar toother volatile metals when treated usingpryometallurgical recovery processes. Forphytoremediation, costs for applications to metals andradionuclides are included due to the lack of data onarsenic.
The EPA document "Technologies and Costs forRemoval of Arsenic From Drinking Water" (Ref. 3.4)contains more information on the cost to reduce theconcentration of arsenic in drinking water from theformer MCL of 0.050 mg/L to below the revised MCLof 0.010 mg/L. The document includes capital andO&M cost curves for a variety of processes, including:
� Retrofitting of existing precipitation/coprecipitation processes to improve arsenicremoval (enhanced coagulation/filtration andenhanced lime softening)
� Precipitation/coprecipitation followed bymembrane filtration (coagulation-assistedmicrofiltration)
� Ion exchange (anion exchange) with varyinglevels of sulfate in the influent
� Two types of adsorption (activated alumina atvarying influent pH and greensand filtration)
� Oxidation pretreatment technologies (chlorinationand potassium permanganate)
� Treatment and disposal costs of treatmentresiduals (including mechanical andnon-mechanical sludge dewatering)
� Point-of-use systems using adsorption (activatedalumina) and membrane filtration (reverseosmosis)
The EPA cost curves are based on computer costmodels for drinking water treatment systems. Costs forfull-scale reverse osmosis, a common type of membranefiltration, were not included because it generally ismore expensive and generates larger volumes oftreatment residuals than other arsenic treatmenttechnologies (Ref. 3.4). Although the cost informationis only for the removal of arsenic from drinking water,many of the same treatment technologies can be used
for the treatment of other waters and may have similarcosts.
Table 3.4 presents estimated capital and annual O&Mcosts for four treatment technologies based on costcurves presented in �Technologies and Costs forRemoval of Arsenic From Drinking Water�:
1. Precipitation/coprecipitation followed bymembrane filtration (coagulation-assistedmicrofiltration)
2. Adsorption (greensand filtration)3. Adsorption (activated alumina with pH of 7 to 8 in
the influent)4. Ion exchange (anion exchange with <20 mg/L
sulfate in the influent)
The table presents the estimated costs for threetreatment system sizes: 0.01, 0.1, and 1 million gallonsper day (mgd). The costs presented in Table 3.4 are forspecific technologies listed in the table, and do notinclude costs for oxidation pretreatment or managementof treatment residuals. Detailed descriptions of theassumptions used to generate the arsenic treatmenttechnology cost curves are available (Ref. 3.4).
3.8 References
3.1 Code of Federal Regulations, Title 40, Part261.24.http://lula.law.cornell.edu/cfr/
3.2 U.S. EPA Office of Water. Fact Sheet: EPA ToImplement 10ppb Standard for Arsenic inDrinking Water. EPA 815-F-01-010. October,2001. http://www.epa.gov/safewater/ars/ars-oct-factsheet.html
3.3 Federal Remediation Technologies ReferenceGuide and Screening Manual, Version 4.0. Federal Remediation Technologies Roundtable. September 5, 2001.http://www.frtr.gov/matrix2/top_page.html.
3.4 U.S. EPA. Office of Water. Technologies andCosts for Removal of Arsenic From DrinkingWater. EPA-R-00-028. December 2000. http://www.epa.gov/safewater/ars/treatments_and_costs.pdf
3.5 U.S. EPA Office of Research and Development. Engineering Bulletin, Technology Alternatives forthe Remediation of Soils Contaminated withArsenic, Cadmium, Chromium, Mercury, andLead. Cincinnati, OH. March 1997. http://www.epa.gov/ncepi/Catalog/EPA540S97500.html
3.6 Redwine, J.C. Successful In Situ RemediationCase Histories: Soil Flushing AndSolidification/Stabilization With Portland CementAnd Chemical Additives. Southern CompanyServices, Inc. Presented at the Air and Waste
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Management Association’s 93rd AnnualConference and Exhibition, Salt Lake City, June2000.
3.7 Miller JP. In-Situ Solidification/Stabilization ofArsenic Contaminated Soils. Electric PowerResearch Institute. Report TR-106700. PaloAlto, CA. November 1996.
3.8 Federal Remediation Technologies Roundtable(FRTR). In Situ Vitrification at the ParsonsChemical/ETM Enterprises Superfund Site GrandLedge, Michigan. April 17, 2001http://www.frtr.gov/costperf.htm
3.9 U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition). Office of Solid Waste and Emergency Response.EPA-542-R-01-004. February 2001.http://clu-in.org/asr.
3.10 U.S. EPA. Contaminants and Remedial Optionsat Selected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512.July 1995.
3.11 U.S. EPA. Database for EPA REACH IT(REmediation And CHaracterization InnovativeTechnologies). March 2001. http://www.epareachit.org.
3.12 U.S. EPA. Treatment Technology Performanceand Cost Data for Remediation of WoodPreserving Sites. Office of Research andDevelopment. EPA-625-R-97-009. October1997. http://www.epa.gov/ncepi/Catalog/EPA625R97009.html
3.13 E-mail attachment sent from Doug Sutton ofGeotrans, Inc. to Linda Fiedler, U.S. EPA. April20, 2001.
3.14 E-mail attachment sent from Anni Loughlin ofU.S. EPA Region I to Linda Fiedler, U.S. EPA. August 21, 2001.
3.15 Miller JP, Hartsfield TH, Corey AC, Markey RM. In Situ Environmental Remediation of anEnergized Substation. EPRI. Palo Alto, CA.Report No. 1005169. 2001.
3.16 Twidwell, L.G., et al. Technologies and PotentialTechnologies for Removing Arsenic from Processand Mine Wastewater. Presented at"REWAS'99." San Sebastian, Spain. September1999. http://www.mtech.edu/metallurgy/arsenic/REWASAS%20for%20proceedings99%20in%20word.pdf
3.17 U.S. EPA. Arsenic Removal from DrinkingWater by Ion Exchange and Activated AluminaPlants. EPA-600-R-00-088. Office of Researchand Development. October 2000.
3.18 DOE. Permeable Reactive Treatment (PeRT)Wall for Rads and Metals. Office ofEnvironmental Management, Office of Scienceand Technology. DOE/EM-0557. September,2000. http://apps.apps.em.doe.gov/ost/pubs/itsrs/itsr2155.pdf
3.19 Applied Biosciences. June 28, 2001.http://www.bioprocess.com
3.20 Center for Bioremediation at Weber StateUniversity. Arsenic Treatment Technologies. August 27, 200. http://www.weber.edu/Bioremediation/arsenic.htm. .
3.21 Electric Power Research Institute. ElectrokineticRemoval of Arsenic from Contaminated Soil: Experimental Evaluation. July 2000. http://www.epri.com/OrderableitemDesc.asp?product_id.
3.22 U.S. EPA. SW-846 On-Line. Test Methods forEvaluating Solid Wastes. Physical/ChemicalMethods. Method 1311 Toxicity CharacteristicLeaching Procedure. July 1992.http://www.epa.gov/epaoswer/hazwaste/test/pdfs/1311.pdf.
3.23 U.S. EPA. SW-846 On-Line. Test Methods forEvaluating Solid Wastes. Physical/ChemicalMethods. Method 1310A Extraction Procedure(EP) Toxicity Test Method and StructuralIntegrity Test. July 1992.http://www.epa.gov/epaoswer/hazwaste/test/pdfs/1310a.pdf.
3.24 California Code of Regulations. Title 22 Section66261.126, Appendix II. Waste Extraction Test(WET) Procedures. August, 2002. http://ccr.oal.ca.gov/
3.25 U.S. EPA. Arsenic Treatment Technology DesignManual for Small Systems (100% Draft for PeerReview). June 2002. http://www.epa.gov/safewater/smallsys/arsenicdesignmanualpeerreviewdraft.pdf
3.26 Cunningham, S. D. The Phytoremediation of SoilsContaminated with Organic Pollutants: Problemsand Promise. International PhytoremediationConference. May 8-10, Arlington, VA. 1996.
3.27 Salt, D. E., M. et al. Phytoremedia-tion: A NovelStrategy for the Removal of Toxic Metals fromthe Environment Using Plants. Biotechnol.13:468-474. 1995.
3.28 Dushenkov, S., D. et al.. Removal of Uraniumfrom Water Using Terrestrial Plants. Environ, Sci.Technol. 31(12):3468-3474. 1997.
3.29 Cunningham, S. D., and W. R. Berti, and J. W.Huang. Phytoremediation of Contaminated Soils.Trends Biotechnol. 13:393-397. 1995.
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Tab
le 3
.1.
App
licab
ility
of A
rsen
ic T
reat
men
t Tec
hnol
ogie
s
Tec
hnol
ogy
Soila
Was
teb
Wat
er
Gro
undw
ater
and
Sur
face
Wat
erc
Dri
nkin
g W
ater
Was
tew
ater
d
Solid
ifica
tion/
Stab
iliza
tion
gg
Vitr
ifica
tion
gg
Soil
Was
hing
/Aci
d Ex
tract
ion
g
Pyro
met
allu
rgic
al T
reat
men
tg
g
In S
itu S
oil F
lush
ing
g
Prec
ipita
tion/
Cop
reci
pita
tion
gg
g
Mem
bran
e Fi
ltrat
ion
gg
Ads
orpt
ion
gg
Ion
Exch
ange
gg
Perm
eabl
e R
eact
ive
Bar
riers
g
Elec
troki
netic
sg
gg
Phyt
orem
edia
tion
gg
Bio
logi
cal T
reat
men
tg
g
g =
Indi
cate
s tre
atm
ent h
as b
een
cond
ucte
d at
full
scal
e.
aSo
il in
clud
es so
il, d
ebris
, slu
dge,
sedi
men
ts, a
nd o
ther
solid
pha
se e
nviro
nmen
tal m
edia
.b
Was
te in
clud
es n
on-h
azar
dous
and
haz
ardo
us so
lid w
aste
gen
erat
ed b
y in
dust
ry.
cG
roun
dwat
er a
nd su
rfac
e w
ater
als
o in
clud
es m
ine
drai
nage
.d
Was
tew
ater
incl
udes
non
haza
rdou
s and
haz
ardo
us in
dust
rial w
aste
wat
er a
nd le
acha
te.
3 - 1
0
Tab
le 3
.2
Ars
enic
Tre
atm
ent T
echn
olog
ies S
cree
ning
Mat
rix
Rat
ing
Cod
es
- B
ette
r;
- A
vera
ge;
- W
orse
;Y
- Y
es; N
- N
o.F
- Ful
l; P
- Pilo
t.S
- Sol
id; L
- Li
quid
; V -
Vap
or.
Cap
- C
apita
l; N
- N
eith
er; O
&M
- O
pera
tion
&M
aint
enan
ce.
T -
May
requ
ire p
retre
atm
ent o
r aff
ect c
ost a
ndpe
rfor
man
ce.
Development Status
Treatment Train(excludes off-gas treatment)
Residuals Produced
O&M or Capital Intensive
Availability
System Reliability/Maintainability
Overall Cost
Cha
ract
eris
tics T
hat M
ay R
equi
rePr
etre
atm
ent o
r A
ffec
t Per
form
ance
or
Cos
t
High Arsenic Concentration
Arsenic Chemical Form
pH
Oth
er C
hara
cter
istic
sT
echn
olog
ySo
lidifi
catio
n/St
abili
zatio
nF
NS
Cap
TT
•R
edox
pot
entia
l•
Pres
ence
of o
rgan
ics
•Fi
ne p
artic
ulat
e•
Type
of b
inde
r &re
agen
t•
Pret
reat
men
tV
itrifi
catio
nF
NS,
VC
ap& O
&M
•Pr
esen
ce o
fha
loge
nate
d or
gani
cco
mpo
unds
•Pr
esen
ce o
f vol
atile
met
als
•Pa
rticl
e si
ze•
Lack
of g
lass
form
ing
mat
eria
ls•
Moi
stur
e co
nten
t•
Org
anic
con
tent
•V
olum
e of
cont
amin
ated
soil
and
was
te•
Cha
ract
eris
tics o
ftre
ated
was
te
Tab
le 3
.2
Ars
enic
Tre
atm
ent T
echn
olog
ies S
cree
ning
Mat
rix
(con
tinue
d)
Rat
ing
Cod
es
- B
ette
r;
- A
vera
ge;
- W
orse
;Y
- Y
es; N
- N
o.F
- Ful
l; P
- Pilo
t.S
- Sol
id; L
- Li
quid
; V -
Vap
or.
Cap
- C
apita
l; N
- N
eith
er; O
&M
- O
pera
tion
&M
aint
enan
ce.
T -
May
requ
ire p
retre
atm
ent o
r aff
ect c
ost a
ndpe
rfor
man
ce.
Development Status
Treatment Train(excludes off-gas treatment)
Residuals Produced
O&M or Capital Intensive
Availability
System Reliability/Maintainability
Overall Cost
Cha
ract
eris
tics T
hat M
ay R
equi
rePr
etre
atm
ent o
r A
ffec
t Per
form
ance
or
Cos
t
High Arsenic Concentration
Arsenic Chemical Form
pH
Oth
er C
hara
cter
istic
s
3 - 1
1
Soil
Was
hing
/Aci
d Ex
tract
ion
FY
S, L
Cap
& O&
M
T•
Soil
hom
ogen
eity
•M
ultip
leco
ntam
inan
ts•
Moi
stur
e co
nten
t•
Tem
pera
ture
•So
il pa
rticl
e si
zedi
strib
utio
nPy
rom
etal
lurg
ical
Rec
yclin
gF
NS,
L,
VC
ap&
O&
M•
Parti
cle
size
•M
oist
ure
cont
ent
•Th
erm
al c
ondu
ctiv
ity•
Pres
ence
of
impu
ritie
sSo
il Fl
ushi
ngF
YL
O&
MT
T•
Num
ber o
fco
ntam
inan
ts tr
eate
d•
Soil
char
acte
ristic
s•
Prec
ipita
tion
•Te
mpe
ratu
re•
Reu
se o
f flu
shin
gso
lutio
n•
Con
tam
inan
tre
cove
ry
Tab
le 3
.2
Ars
enic
Tre
atm
ent T
echn
olog
ies S
cree
ning
Mat
rix
(con
tinue
d)
Rat
ing
Cod
es
- B
ette
r;
- A
vera
ge;
- W
orse
;Y
- Y
es; N
- N
o.F
- Ful
l; P
- Pilo
t.S
- Sol
id; L
- Li
quid
; V -
Vap
or.
Cap
- C
apita
l; N
- N
eith
er; O
&M
- O
pera
tion
&M
aint
enan
ce.
T -
May
requ
ire p
retre
atm
ent o
r aff
ect c
ost a
ndpe
rfor
man
ce.
Development Status
Treatment Train(excludes off-gas treatment)
Residuals Produced
O&M or Capital Intensive
Availability
System Reliability/Maintainability
Overall Cost
Cha
ract
eris
tics T
hat M
ay R
equi
rePr
etre
atm
ent o
r A
ffec
t Per
form
ance
or
Cos
t
High Arsenic Concentration
Arsenic Chemical Form
pH
Oth
er C
hara
cter
istic
s
3 - 1
2
Prec
ipita
tion/
Cop
reci
pita
tion
FY
SC
ap& O
&M
aT
T•
Pres
ence
of o
ther
com
poun
ds•
Type
of c
hem
ical
addi
tion
•C
hem
ical
dos
age
•Tr
eatm
ent g
oal
•Sl
udge
dis
posa
lM
embr
ane
Filtr
atio
nF
YL
Cap
& O&
M
TT
T•
Susp
ende
d so
lids,
high
mol
ecul
arw
eigh
t, di
ssol
ved
solid
s, or
gani
cco
mpo
unds
and
collo
ids
•Te
mpe
ratu
re•
Type
of m
embr
ane
filtra
tion
•In
itial
was
te st
ream
•R
ejec
ted
was
test
ream
Tab
le 3
.2
Ars
enic
Tre
atm
ent T
echn
olog
ies S
cree
ning
Mat
rix
(con
tinue
d)
Rat
ing
Cod
es
- B
ette
r;
- A
vera
ge;
- W
orse
;Y
- Y
es; N
- N
o.F
- Ful
l; P
- Pilo
t.S
- Sol
id; L
- Li
quid
; V -
Vap
or.
Cap
- C
apita
l; N
- N
eith
er; O
&M
- O
pera
tion
&M
aint
enan
ce.
T -
May
requ
ire p
retre
atm
ent o
r aff
ect c
ost a
ndpe
rfor
man
ce.
Development Status
Treatment Train(excludes off-gas treatment)
Residuals Produced
O&M or Capital Intensive
Availability
System Reliability/Maintainability
Overall Cost
Cha
ract
eris
tics T
hat M
ay R
equi
rePr
etre
atm
ent o
r A
ffec
t Per
form
ance
or
Cos
t
High Arsenic Concentration
Arsenic Chemical Form
pH
Oth
er C
hara
cter
istic
s
3 - 1
3
Ads
orpt
ion
FY
S, L
Cap
& O&
M
aT
TT
•Fl
ow ra
te•
pH•
Foul
ing
•C
onta
min
atio
nco
ncen
tratio
n•
Spen
t med
iaIo
n Ex
chan
geF
YS,
LC
ap& O
&M
aT
TT
•Pr
esen
ce o
fco
mpe
ting
ions
•Pr
esen
ce o
f org
anic
s•
Pres
ence
of t
rival
ent
ion
•Pr
ojec
t sca
le•
Bed
rege
nera
tion
•Su
lfate
Perm
eabl
e R
eact
ive
Bar
riers
FN
SC
apT
•Fr
actu
red
rock
•D
eep
aqui
fers
&co
ntam
inan
t plu
mes
•H
igh
aqui
fer
hydr
aulic
cond
uctiv
ity•
Stra
tigra
phy
•B
arrie
r plu
ggin
g•
PRB
dep
th
Tab
le 3
.2
Ars
enic
Tre
atm
ent T
echn
olog
ies S
cree
ning
Mat
rix
(con
tinue
d)
Rat
ing
Cod
es
- B
ette
r;
- A
vera
ge;
- W
orse
;Y
- Y
es; N
- N
o.F
- Ful
l; P
- Pilo
t.S
- Sol
id; L
- Li
quid
; V -
Vap
or.
Cap
- C
apita
l; N
- N
eith
er; O
&M
- O
pera
tion
&M
aint
enan
ce.
T -
May
requ
ire p
retre
atm
ent o
r aff
ect c
ost a
ndpe
rfor
man
ce.
Development Status
Treatment Train(excludes off-gas treatment)
Residuals Produced
O&M or Capital Intensive
Availability
System Reliability/Maintainability
Overall Cost
Cha
ract
eris
tics T
hat M
ay R
equi
rePr
etre
atm
ent o
r A
ffec
t Per
form
ance
or
Cos
t
High Arsenic Concentration
Arsenic Chemical Form
pH
Oth
er C
hara
cter
istic
s
3 - 1
4
Bio
logi
cal T
reat
men
tF
YS,
LC
ap& O
&M
TT
T•
Iron
con
cent
ratio
n•
Con
tam
inan
tco
ncen
tratio
n•
Ava
ilabl
e nu
trien
ts•
Tem
pera
ture
•Pr
etre
atm
ent
requ
irem
ents
Elec
troki
netic
s F
YS,
LO
&M
TT
T•
Salin
ity &
cat
ion
exch
ange
cap
acity
•So
il m
oist
ure
•Po
larit
y &
mag
nitu
deof
ioni
c ch
arge
•So
il ty
pe•
Con
tam
inan
tex
tract
ion
syst
emPh
ytor
emed
iatio
nF
NL,
SN
TT
T•
Con
tam
inan
t dep
th•
Clim
atic
or s
easo
nal
cond
ition
sSo
urce
: Ada
pted
from
the
Fede
ral R
emed
iatio
n Te
chno
logi
es R
ound
tabl
e Te
chno
logy
Scr
eeni
ng M
atrix
. ht
tp://
ww
w.fr
tr.go
v. S
epte
mbe
r 200
1. (R
ef. 3
.3)
a.R
elat
ive
cost
s for
pre
cipi
tatio
n/co
prec
ipita
tion,
ads
orpt
ion,
and
ion
exch
ange
are
sens
itive
to tr
eatm
ent s
yste
m c
apac
ity, u
ntre
ated
wat
er c
hara
cter
istic
s, an
dot
her f
acto
rs.
Tab
le 3
.3A
vaila
ble
Ars
enic
Tre
atm
ent C
ost D
ata
3 - 1
5
Site
Am
ount
Tre
ated
Cap
ital
Cos
t
Ann
ual
O &
MC
ost
Uni
t Cos
t T
otal
Cos
tC
ost E
xpla
natio
nSo
urce
Sol
idifi
catio
n/St
abili
zatio
n-
--
-$6
0 - $
290
per
ton
-�
Cos
t is f
or S
/S o
f met
als a
nd is
not
arse
nic-
spec
ific
�C
ost y
ear n
ot sp
ecifi
ed
3.5
Elec
trica
l Sub
stat
ion
in F
lorid
a 3,
300
cubi
cya
rds
--
$85
per c
ubic
yard
-�
Excl
udes
Dis
posa
l Cos
ts�
Cos
ts in
199
5 D
olla
rs3.
6, 3
.7
Vitr
ifica
tion
Pars
ons C
hem
ical
Sup
erfu
nd S
ite3,
000
cubi
cya
rds
$350
,000
-$5
50,0
00
-$3
75 -
$425
per t
on-
�C
apita
l cos
t inc
lude
s pilo
t tes
ting,
mob
iliza
tion,
and
dem
obili
zatio
n�
Uni
t cot
s are
for o
pera
tion
ofvi
trific
atio
n eq
uipm
ent o
nly
�C
ost y
ear n
or sp
ecifi
ed
3.8
Soi
l Was
hing
/Aci
d E
xtra
ctio
nK
ing
of P
russ
ia S
uper
fund
Site
12,8
00 c
ubic
yard
s-
-$4
00 p
er to
n-
�C
ost y
ear n
ot sp
ecifi
ed3.
9,3.
10-
--
-$1
00 -
$300
per t
on-
�C
ost y
ear n
ot sp
ecifi
ed3.
10
--
--
$65
per t
on-
�C
ost y
ear n
ot sp
ecifi
ed3.
11-
400
cubi
cya
rds
--
$80
per t
on-
�C
ost y
ear n
ot sp
ecifi
ed3.
11
-38
,000
tons
--
$203
per
ton
$7.7
mill
ion
�C
ost y
ear n
ot sp
ecifi
ed3.
12 P
yrom
etal
lurg
ical
Rec
over
y-
--
-$2
08 to
$45
8pe
r ton
_�
Cos
t is n
ot a
rsen
ic-s
peci
fic�
Cos
ts in
199
1 do
llars
3.10
In S
itu S
oil F
lush
ing
- No
cost
dat
a id
entif
ied
Pre
cipi
tatio
n/C
opre
cipi
tatio
nV
inel
and
Che
mic
al C
ompa
ny 1
,400
gpm
-$4
mill
ion
--
�C
ost y
ear n
ot sp
ecifi
ed3.
13W
inth
rop
Land
fill
65 g
pm$2
mill
ion
$250
,000
--
�C
ost y
ear n
ot sp
ecifi
ed3.
14
Ener
gize
d Su
bsta
tion
in F
lorid
a44
mill
ion
gallo
ns-
-$0
.000
6 pe
rga
llon
-�
Cos
t yea
r not
spec
ified
3.15
Mem
bran
e Fi
ltrat
ion
- No
cost
dat
a id
entif
ied
Tab
le 3
.3A
vaila
ble
Ars
enic
Tre
atm
ent C
ost D
ata
(Con
tinue
d)
Site
Am
ount
Tre
ated
Cap
ital
Cos
t
Ann
ual
O &
MC
ost
Uni
t Cos
t T
otal
Cos
tC
ost E
xpla
natio
nSo
urce
3 - 1
6
Ads
orpt
ion
--
--
$0.0
03 -
$0.7
6pe
r 1,0
00ga
llons
-�
Cos
t yea
r not
spec
ified
3.16
Ion
Exc
hang
e-
-$9
,000
--
-�
Cos
t yea
r not
spec
ified
3.17
Per
mea
ble
Rea
ctiv
e B
arri
erM
ontic
ello
Mill
Tai
lings
-$1
.2m
illio
n-
--
�C
ost y
ear n
ot sp
ecifi
ed3.
18
Ele
ctro
kine
tics
Pede
rok
Plan
t, K
win
t, Lo
pper
sum
,N
ethe
rland
s32
5 cu
bic
yard
s-
-$7
0 pe
r ton
-�
Cos
t yea
r not
spec
ified
3.11
Bla
ckw
ater
Riv
er S
tate
For
est,
FL-
--
$883
per
ton
-�
Cos
t yea
r not
spec
ified
3.21
Phy
tore
med
iatio
n -12
acr
es-
--
$200
,000
�19
98 d
olla
rs�
Cos
t is f
or p
hyto
extra
ctio
n of
lead
from
soil
3.26
-1
acre
, 20
inch
es d
eep
--
-$6
0,00
0 -
$100
,000
�C
ost y
ear n
ot sp
ecifi
ed�
Cos
t is f
or p
hyto
extra
ctio
n fr
om so
il�
Con
tam
inan
t was
not
spec
ified
3.27
--
--
$2 -
$6 p
er1,
000
gallo
ns-
�C
ost i
s for
ex
situ
trea
tmen
t of w
ater
cont
aini
ng ra
dion
uclid
es�
Cos
t yea
r not
spec
ified
3.28
--
--
$0.0
2 - $
.76
per c
ubic
yar
d-
�C
ost y
ear n
ot sp
ecifi
ed�
Cos
t is f
or p
hyto
stab
iliza
tion
of m
etal
s,an
d is
not
ars
enic
-spe
cific
3.29
Bio
logi
cal T
reat
men
t-
--
-$0
.50
per
1,00
0 ga
llons
-�
Cos
t yea
r not
spec
ified
3.19
--
--
$2 p
er 1
,000
gallo
ns-
�C
ost y
ear n
ot sp
ecifi
ed3.
20
- = D
ata
nor p
rovi
ded
gpm
- ga
llons
per
min
ute
3 - 1
7
Tab
le 3
.4Su
mm
ary
of C
osta D
ata
for
Tre
atm
ent o
f Ars
enic
in D
rink
ing
Wat
er
Tec
hnol
ogy
Des
ign
Flow
Rat
e
0.01
mgd
0.1
mgd
1 m
gd
Cap
ital C
ost (
$)A
nnua
l O&
MC
ost (
$)C
apita
l Cos
t ($)
Ann
ual O
&M
Cos
t ($)
Cap
ital C
ost (
$)A
nnua
l O&
MC
ost (
$)
Prec
ipita
tion/
Cop
reci
pita
tion
(coa
gula
tion-
assi
sted
mic
rofil
tratio
n)
142,
000
22,2
0046
3,00
035
,000
2,01
0,00
064
,300
Ads
orpt
ion
(gre
ensa
nd fi
ltrat
ion)
12,4
007,
980
85,3
0013
,300
588,
000
66,3
00
Ads
orpt
ion
(act
ivat
ed a
lum
ina,
influ
ent p
H 7
- 8)
15,4
006,
010
52,2
0023
,000
430,
000
201,
000
Ion
exch
ange
(ani
on e
xcha
nge,
influ
ent <
20 m
g/L
sulfa
te)
23,0
005,
770
54,0
0012
,100
350,
000
52,2
00
Sour
ce: D
eriv
ed fr
om R
ef. 3
.4
a.C
osts
are
roun
ded
to th
ree
sign
ifica
nt fi
gure
s and
are
in S
epte
mbe
r 199
8 do
llars
. C
osts
do
not i
nclu
de p
retre
atm
ent o
r man
agem
ent o
f tre
atm
ent r
esid
uals
. C
osts
for e
nhan
ced
coag
ulat
ion/
filtra
tion
and
enha
nced
lim
e so
fteni
ng a
re n
ot p
rese
nted
bec
ause
the
cost
s cur
ves f
or th
ese
tech
nolo
gies
are
for m
odifi
catio
n of
exis
ting
drin
king
wat
er tr
eatm
ent s
yste
ms o
nly
(Ref
. 3.4
), an
d ar
e no
t com
para
ble
to o
ther
cos
ts p
rese
nted
in th
is ta
ble,
whi
ch a
re fo
r new
trea
tmen
t sys
tem
s.
mgd
= m
illio
n ga
llons
per
day
O&
M =
ope
ratin
g an
d m
aint
enan
cem
g/L
= m
illig
ram
s per
lite
r<
= le
ss th
an
IIARSENIC TREATMENT TECHNOLOGY SUMMARIES
IIAARSENIC TREATMENT TECHNOLOGIES
APPLICABLE TO SOIL AND WASTE
4-1
Summary
Solidification and stabilization (S/S) is anestablished treatment technology often used toreduce the mobility of arsenic in soil and waste. Themost frequently used binders for S/S of arsenic arepozzolanic materials such as cement and lime. S/Scan generally produce a stabilized product thatmeets the regulatory threshold of 5 mg/L leachablearsenic as measured by the TCLP. However,leachability tests may not always be accurateindicators of arsenic leachability for some wastesunder certain disposal conditions.
DryReagents
DryReagents
Pug MillMixer
Pug MillMixer
WasteMaterialWaste
MaterialLiquid
ReagentsLiquid
Reagents
Water(If Required)
Water(If Required)
Stabilized Waste
DryReagents
DryReagents
Pug MillMixer
Pug MillMixer
WasteMaterialWaste
MaterialLiquid
ReagentsLiquid
Reagents
Water(If Required)
Water(If Required)
Stabilized Waste
Model of a Solidification/Stabilization System
13
3 32 2
0
5
10
15
Cement Phosphate pHAdjustment
Agents
Lime Sulfur
13
3 32 2
0
5
10
15
Cement Phosphate pHAdjustment
Agents
Lime Sulfur
Technology Description: S/S reduces the mobilityof hazardous substances and contaminants in theenvironment through both physical and chemicalmeans. It physically binds or encloses contaminantswithin a stabilized mass and chemically reduces thehazard potential of a waste by converting thecontaminants into less soluble, mobile, or toxicforms.
Media Treated:
• Soil• Sludge
• Other solids• Industrial waste
Binders and Reagents used in S/S of Arsenic:
• Cement• Fly Ash• Lime• Phosphate
• pH adjustment agents• Sulfur
4.0 SOLIDIFICATION ANDSTABILIZATION TREATMENT FORARSENIC
Technology Description and Principles
The stabilization process involves mixing a soil orwaste with binders such as Portland cement, lime, flyash, cement kiln dust, or polymers to create a slurry,paste, or other semi-liquid state, which is allowed timeto cure into a solid form. When free liquids are presentthe S/S process may involve a pretreatment step(solidification) in which the waste is encapsulated orabsorbed, forming a solid material. Pozzolanic binderssuch as cement and fly ash are used most frequently forthe S/S of arsenic. No site-specific information iscurrently available on the use of organic binders toimmobilize arsenic.
The process also may include the addition of pHadjustment agents, phosphates, or sulfur reagents toreduce the setting or curing time, increase thecompressive strength, or reduce the leachability ofcontaminants (Ref. 4.8). Information gathered for thisreport included 45 Superfund remedial action projectstreating soil or waste containing arsenic using S/S. Figure 4.1 shows the frequency of use of binders andreagents in 21 of those S/S treatments. The figureincludes some projects where no performance data wereavailable but information was available on the types ofbinders and reagents used. Some projects used morethan one binder or reagent. Data were not available forall 46 projects.
Figure 4.1Binders and Reagents Used for
Solidification/Stabilization of Arsenic for 21Identified Superfund Remedial Action Projects
4-2
19
58
0 20 40 60
Pilot
Full
19
58
0 20 40 60
Pilot
Full
Factors Affecting S/S Performance
• Valence state - The specific arsenic compoundor valence state of arsenic may affect theleachability of the treated material becausethese factors affect the solubility of arsenic.
• pH and redox potential - The pH and redoxpotential of the waste and waste disposalenvironment may affect the leachability of thetreated material because these factors affect thesolubility of arsenic and may cause arsenic toreact to form more soluble compounds or reacha more soluble valence state.
• Presence of organics - The presence of volatileor semivolatile organic compounds, oil andgrease, phenols, or other organic contaminantsmay reduce the unconfined compressivestrength or durability of the S/S product, orweaken the bonds between the waste particlesand the binder.
• Waste characteristics - The presence ofhalides, cyanide, sulfate, calcium, or solublesalts of manganese, tin, zinc, copper, or leadmay reduce the unconfined compressivestrength or durability of the S/S product, orweaken the bonds between the waste particlesand the binder.
• Fine particulate - The presence of fineparticulate matter coats the waste particles andweakens the bond between the waste and thebinder.
• Mixing - Thorough mixing is necessary toensure waste particles are coated with thebinder.
S/S often involves the use of additives or pretreatmentto convert arsenic and arsenic compounds into morestable and less soluble forms, including pH adjustmentagents, ferric sulfate, persulfates, and other proprietaryreagents (Ref. 4.3, 4.8). Prior to S/S, the soil or wastemay be pretreated with chemical oxidation to render thearsenic less soluble by converting it to its As(V) state(Ref. 4.3). Pretreatment with incineration to convertarsenic into ferric arsenate has also been studied, butlimited data are available on this process (Ref. 4.3).
This technology has also been used to immobilizearsenic in soil in situ by injecting solutions of chemicalprecipitants, pH adjustment agents, and chemicaloxidants. In this report, such applications are referredto as in situ S/S. In one full-scale treatment, a solutionof ferrous iron, limestone, and potassium permanganatewas injected (Ref. 4.8). In another full-scale treatment,a solution of unspecified pH adjustment agents andphosphates was injected (Ref. 4.10).
Media and Contaminants Treated
S/S is used frequently to immobilize metals andinorganics in soil and waste. It has been used toimmobilize arsenic in environmental media such as soiland industrial wastes such as sludges and mine tailings.
Type, Number, and Scale of Identified ProjectsTreating Soil and Wastes Containing Arsenic
S/S of soil and waste containing arsenic iscommercially available at full scale. Data sources usedfor this report included information about 58 full-scaleand 19 pilot-scale applications of S/S to treat arsenic. This included 45 projects at 41 Superfund sites (Ref.4.8). Figure 4.2 shows the number of applications atboth full and pilot scale.
Figure 4.2Scale of Identified Solidification/Stabilization
Projects for Arsenic Treatment
Summary of Performance Data
Table 4.1 provides performance data for 10 pilot-scaletreatability studies and 34 full-scale remediationprojects. Due to the large number of projects, Table 4.1lists only those for which leachable arsenicconcentrations are available for the treated soil orwaste, with the exception of projects involving only insitu stabilization. In situ projects without informationon the leachability of arsenic in the stabilized mass areincluded in the table because this type of application ismore innovative and information is available for only afew applications.
The performance of S/S treatment is usually measuredby leach testing a sample of the stabilized mass. Formost land-disposed arsenic-bearing hazardous wastesthat fall under RCRA (including both listed and
4-3
Case Study: Long-Term Stability of S/S ofArsenic
EPA obtained leachate data from landfills acceptingwastes treated using solidification/stabilizationoperated by Waste Management, Inc., Envirosafe,and Reynolds Metals. The Waste Management, Inc.landfills received predominantly hazardous wastesfrom a variety of sources, the Envirosafe landfill received primarily waste bearing RCRA waste codeK061 (emission control dust and sludge from theprimary production of steel in electric furnaces) andthe Reynolds Metals facility was a monofillaccepting waste bearing RCRA waste code K088(spent potliners from primary aluminum reduction). Analysis of the leachate from 80 landfill cellsshowed 9 cells, or 11%, had dissolved arsenicconcentrations higher than the TCLP level of 5.0mg/L. The maximum dissolved arsenicconcentration observed in landfill leachate was 120mg/L. Analysis of the leachate from 152 landfillcells showed 29 cells, or 19%, had total arsenicconcentrations in excess of the TCLP level of 5.0mg/L. The maximum total arsenic concentrationobserved in landfill leachate was 1,610 mg/L (Ref.4.12).
Another study reported the long-term stability of S/Stechnologies treating wastes from three landfillscontaminated with heavy metals, including arsenic(Ref. 4.16). S/S was performed at each site usingcement and a variety of chemical additives. TCLPtesting showed arsenic concentrations ranging fromzero to 0.017 mg/L after a 28-day cure time. Sixyears later, TCLP testing showed leachable arsenicconcentrations that were slightly higher than thosefor a 28-day cure time (0.005 - 0.022 mg/L), but thelevels remained below 0.5 mg/L. However, thestabilized waste was stored above ground, andtherefore may not be representative of wastedisposed in a landfill (see Projects 12, 13, and 16 inTable 4.1 and Table 4.2).
characteristic wastes), the treatment standard is lessthan 5.0 mg/L arsenic in the extract generated by thetoxicity characteristic leaching procedure (TCLP). Thestandard for spent potliners from primary aluminumsmelting (K088) is 26.1 mg/kg total arsenic (Ref. 4.10). For listed hazardous wastes, the waste must be disposedin a Subtitle C land disposal unit after treatment to meetthe standard for arsenic and any other applicablestandards, unless it is specifically delisted. Forhazardous wastes exhibiting the characteristic forarsenic, the waste may be disposed in a Subtitle Dlandfill after being treated to remove the characteristicand to meet all other applicable standards.
Of the 23 soil projects identified for this report, 22achieved a leachable arsenic concentration of less than 5.0 mg/L in the stabilized material. Of the 19 industrialwaste projects, 17 achieved a leachable arsenicconcentration of less than 5.0 mg/L in the stabilizedmaterial. Leachability data are not available for theprojects that involve only in situ stabilization.
Four projects (Projects 25, 26, 27, and 41, Table 4.1)included pretreatment to oxidize As(III) to As(V). Inthese projects, the leachability of arsenic in industrialwastes was reduced to less than 0.50 mg/L. Thecompound treated in Projects 24, 25, and 26 wasidentified as arsenous trisulfide. All three treatmentprocesses involved pretreating a waste containing 5,000to 40,000 mg/kg arsenous trisulfide with chemicaloxidation (Ref. 4.1). The specific arsenic compound inanother S/S treatment (Project 41) was identified asAs2O3. This treatment process included pretreatment bychemical oxidation to form ferric arsenate sludgefollowed by S/S with lime (Ref. 4.3).
Limited data are available about the long-term stabilityof soil and waste containing arsenic treated using S/S. Projects 12, 13, and 16 were part of one study thattested the leachability of arsenic six years after S/S wasperformed (see Case Study: Long-Term Stability of S/Sor Arsenic).
The case study on Whitmoyer Laboratories SuperfundSite discusses in greater detail the treatment of arsenicusing S/S. This information is summarized in Table4.1, Project 20.
Applicability, Advantages, and Potential Limitations
The mobility of arsenic depends upon its valence state,the reduction-oxidation potential of the waste disposalenvironment, and the specific arsenic compoundcontained in the waste (Ref. 4.1). This mobility isusually measured by testing the leachability of arsenicunder acidic conditions. In some disposal environmentsthe leachability of arsenic may be different than that
predicted by an acidic leach test, particularly when thespecific form of arsenic in the waste shows increasedsolubility at higher pH and the waste disposalenvironment has a high pH. Analytical data forleachate from monofills containing wastes bearingRCRA waste code K088 (spent aluminum potliners)indicate that arsenic may leach from wastes at levels
4-4
Case Study: Whitmoyer Laboratories Superfund Site
The Whitmoyer Laboratories Superfund Site was aformer veterinary feed additives and pharmaceuticalsmanufacturing facility. It is located onapproximately 22 acres of land in Jackson Township,Lebanon County, Pennsylvania. Production began atthe site in 1934. In the mid-1950's the facility beganusing arsenic in the production of feed additives. Soils on most of the area covered by the facility arecontaminated with organic arsenic.
Off-site stabilization began in mid-1999 and wascompleted by the spring of 2000. A total of 400 tonsof soil were stabilized using a mixture of 10% water,10% ferric sulfate, and 5% Portland cement. Theconcentration of leachabile arsenic in the treated soilwas below 5.0 mg/L, as measured by the TCLP. Information on the pretreatment arsenic leachabilitywas not available.
Factors Affecting S/S Costs
• Type of binder and reagent - The use ofproprietary binders or reagents may be moreexpensive than the use of non-proprietarybinders (Ref. 4.16).
• Pretreatment - The need to pretreat soil andwaste prior to S/S may increase managementcosts (Ref. 4.18).
• Factors affecting S/S performance - Items inthe “Factors Affecting S/S Performance” boxwill also affect costs.
higher than those predicted by the TCLP (see CaseStudy: Long-term Stability of S/S of Arsenic).
Some S/S processes involve pretreatment of the wasteto render arsenic less soluble prior to stabilization (Ref.4.1, 4.3). Such processes may render the waste lessmobile under a variety of disposal conditions (SeeProjects 25, 26, 27,and 41 in Table 4.1), but also mayresult in significantly higher waste management costsfor the additional treatment steps.
In situ S/S processes may reduce the mobility of arsenicby changing it to less soluble forms, but do not removethe arsenic. Ensuring thorough mixing of the binderand the waste can also be challenging for in situ S/Sprocesses, particularly when the subsurface containslarge particle size soil and debris or subsurfaceobstructions. The long-term effectiveness of this typeof treatment may be impacted if soil conditions causethe stabilized arsenic to change to more soluble andtherefore more mobile forms.
Summary of Cost Data
The reported costs of treatment of soil containingmetals using S/S range from $60 to $290 per ton (Ref.4.5, cost year not identified). Limited site-specific costdata are currently available for S/S treatment of arsenic. At two sites, (Projects 21 and 22), total project costs, in1995 dollars, were about $85 per cubic yard, excludingdisposal costs (Ref. 4.21).
References
4.1. U.S. EPA. Arsenic & Mercury - Workshop onRemoval, Recovery, Treatment, and Disposal.Office of Research and Development. EPA-600-R-92-105. August 1992.http://epa.gov/ncepihom.
4.2. U.S. EPA. Contaminants and Remedial Optionsat Selected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512. July 1995. http://epa.gov/ncepihom.
4.3. U.S. EPA. Final Best Demonstrated AvailableTechnology (BDAT) Background Document forK031, K084, K101, K102, Characteristic ArsenicWastes (D004), Characteristic Selenium Wastes(D010), and P and U Wastes Containing Arsenicand Selenium Listing Constituents. Office ofSolid Waste. May 1990.
4.4. U.S. EPA National Risk Management ResearchLaboratory. Treatability Database. March 2001.
4.5. U.S. EPA Office of Research and Development. Engineering Bulletin, Technology Alternativesfor the Remediation of Soils Contaminated withArsenic, Cadmium, Chromium, Mercury, andLead. Cincinnati, OH. March 1997. http://www.epa.gov/ncepi/Catalog/EPA540S97500.html
4.6. TIO. Database for EPA REACH IT(Remediation And Characterization InnovativeTechnologies). March 2001. http://www.epareachit.org.
4.7. U.S. EPA. Solidification/Stabilization Use atSuperfund Sites. Office of Solid Waste andEmergency Response. EPA 542-R-00-010.September 2000. http://clu-in.org.
4.8. U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition). Office of Solid Waste and Emergency Response. EPA-542-R-01-004. February 2001. http://clu-in.org.
4-5
4.9. U.S. EPA. Treatment Technology Performanceand Cost Data for Remediation of WoodPreserving Sites. Office of Research andDevelopment. EPA-625-R-97-009. October1997. http://epa.gov/ncepihom.
4.10. Code of Federal Regulations, Part 40, Section268. http://lula.law.cornell.edu/cfr/cfr.php?title=40&type=part&value=268
4.11. Personal communication with Jim Sook,Chemical Waste Management, Inc. March 2001.
4.12. Federal Register. Land Disposal Restrictions: Advanced Notice of Proposed Rulemaking. Volume 65, Number 118. June 19, 2000. pp.37944 - 37946. http://www.epa.gov/fedrgstr/EPA-WASTE/2000/June/Day-19/f15392.htm
4.13. U.S. EPA. Biennial Reporting System. DraftAnalysis. 1997.
4.14. Fuessle, R.W. and M.A. Taylor. Stabilization ofArsenic- and Barium-Rich Glass ManufacturingWaste. Journal of Environmental Engineering,March 2000. pp. 272 - 278. http://www.pubs.asce.org/journals/ee.html
4.15. Wickramanayake, Godage, Wendy Condit, andKim Cizerle. Treatment Options for ArsenicWastes. Presented at the U.S. EPA Workshop onManaging Arsenic Risks to the Environment: Characterization of Waste, Chemistry, andTreatment and Disposal. Denver, CO. May 1 -3, 2001.
4.16. Klich, Ingrid. Permanence of MetalsContainment in Solidified and Stabilized Wastes. A Dissertation submitted to the Office ofGraduate Studies of Texas A&M University inpartial fulfillment of the requirements for thedegree of Doctor of Philosophy. December1997.
4.17. Klean Earth Environmental Company. SpringHill Mine Study. August 2001.http://www.keeco.com/spring.htm.
4.18. Markey, R. Comparison and Economic Analysisof Arsenic Remediation Methods Used in Soiland Groundwater. M.S. Thesis. FAMU-FSUCollege of Engineering. 2000.
4.19. Bates, Edward, Endalkachew Sable-Demessie,and Douglas W. Grosse. Solidification/Stabilization for Remediation of WoodPreserving Sites: Treatment for Dioxins, PCP,Creosote, and Metals. Remediation. John Wiley& Sons, Inc. Summer 2000. pp. 51 - 65. http://www.wiley.com/cda/product/0,,REM,00.html
4.20. Palfy, P., E. Vircikova, and L. Molnar. Processing of Arsenic Waste by Precipitation andSolidification. Waste Management. Volume 19. 1999. pp. 55 - 59. http://sdnp.delhi.nic.in/node/jnu/database/
biogeoch/bioch99.html4.21 Redwine JC. Successful In Situ Remediation
Case Histories: Soil Flushing AndSolidification/Stabilization With PortlandCement And Chemical Additives. SouthernCompany Services, Inc. Presented at the Air andWaste Management Association’s 93rd AnnualConference and Exhibition, Salt Lake City, June2000.
4.22 Miller JP. In-Situ Solidification/Stabilization ofArsenic Contaminated Soils. Electric PowerResearch Institute. Report TR-106700. PaloAlto, CA. November 1996.
4.23 E-mail from Bhupi Khona, U.S. EPA Region 3 toSankalpa Nagaraja, Tetra Tech EM, Inc.,regarding S/S of Arsenic at the WhitmoyerLaboratories Superfund site. May 3, 2002.
Tab
le 4
.1So
lidifi
catio
n/St
abili
zatio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic
4-6
Proj
ect
Num
ber
Indu
stry
and
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e, L
ocat
ion,
and
Proj
ect
Com
plet
ion
Dat
eb
Initi
al A
rsen
icC
once
ntra
tion
(mg/
kg) o
rL
each
abili
ty(m
g/L
) (T
est
met
hod)
Fina
l Ars
enic
Con
cent
ratio
n(m
g/kg
) or
Lea
chab
ility
(mg/
L)
(Tes
t met
hod)
Bin
der
orSt
abili
zatio
n Pr
oces
sSo
urce
Env
iron
men
tal M
edia
1D
ispo
sal P
it20
,000
cy
slud
gean
d so
ilFu
llPa
b O
il Su
perf
und
Site
, LA
Aug
ust 1
998
7.5
- 25.
1 m
g/kg
<0.
1 m
g/L
(TC
LP)
Cem
ent,
orga
noph
ilic
clay
, oth
er u
nspe
cifie
dor
gani
c, fe
rric
sulfa
te,
othe
r uns
peci
fied
inor
gani
c, a
nd su
lfur
4.8
2Fi
re/C
rash
Tra
inin
gA
rea;
Fede
ral F
acili
ty
3,00
0 cy
slud
gean
d so
ilFu
llJa
ckso
nvill
e N
aval
Air
Stat
ion
Supe
rfun
dSi
te, F
LO
ctob
er 1
995
ND
c - 61
mg/
kg<5
mg/
L (T
CLP
)C
emen
t, lim
e, o
ther
unsp
ecifi
ed in
orga
nic,
and
kiln
dus
t
4.8
3M
etal
Ore
Min
ing
and
Smel
ting
500,
000
cy so
ilFu
llA
naco
nda
Co.
Smel
ter S
uper
fund
Site
, MT
Janu
ary
1994
50 -
100
mg/
L(E
PT)
<2 m
g/L
(TC
LP)
Uns
peci
fied
inor
gani
c4.
8
4M
uniti
ons
Man
ufac
turin
g/St
orag
e
1,00
0 cy
soil
Full
Fern
ald
Envi
ronm
enta
lM
anag
emen
t Pro
ject
Supe
rfun
d Si
te, O
HSe
ptem
ber 1
999
3 -
18 m
g/kg
<5m
g/L
(TC
LP)
Cem
ent a
ndot
her u
nspe
cifie
din
orga
nic
4.8
5--
Soil
Full
--0.
18 m
g/L
(EPT
)0.
028
mg/
L (E
PT)
Cem
ent
4.4
6--
Soil
Full
--0.
19 m
g/L
(TC
LP)
0.01
7 m
g/L
(TC
LP)
Cem
ent
4.4
7--
Soil
Full
--0.
0086
mg/
L(E
PT)
0.00
49 m
g/L
(EPT
)Pr
oprie
tary
bin
der
4.4
8--
Soil
Full
--0.
0091
mg/
L(T
CLP
)<0
.002
mg/
L (T
CLP
)Pr
oprie
tary
bin
der
4.4
9--
Soil
Full
--0.
017
mg/
L(T
CLP
)0.
0035
mg/
L (T
CLP
)Pr
oprie
tary
bin
der
4.4
Tab
le 4
.1So
lidifi
catio
n/St
abili
zatio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
and
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e, L
ocat
ion,
and
Proj
ect
Com
plet
ion
Dat
eb
Initi
al A
rsen
icC
once
ntra
tion
(mg/
kg) o
rL
each
abili
ty(m
g/L
) (T
est
met
hod)
Fina
l Ars
enic
Con
cent
ratio
n(m
g/kg
) or
Lea
chab
ility
(mg/
L)
(Tes
t met
hod)
Bin
der
orSt
abili
zatio
n Pr
oces
sSo
urce
4-7
10--
Soil
Full
--2,
430
mg/
kg0.
11 -
0.26
mg/
L(T
CLP
)fly
ash
, cem
ent,
and
prop
rieta
ry re
agen
t4.
3
11--
Soil
Full
--0.
10 m
g/L
(TC
LP)
0.04
mg/
L (T
CLP
)--
4.1
12O
il Pr
oces
sing
&R
ecla
mat
ion
Filte
r cak
e an
doi
ly sl
udge
Full
Impe
rial O
il C
o -
Cha
mpi
on C
hem
ical
Co
Supe
rfun
d Si
te,
NJ
40 m
g/kg
ND
c,d (T
CLP
)C
emen
t and
pro
prie
tary
addi
tives
4.16
13O
il Pr
oces
sing
&R
ecla
mat
ion
Soil
Full
Impe
rial O
il C
o -
Cha
mpi
on C
hem
ical
Co
Supe
rfun
d Si
te,
NJ
92 m
g/kg
0.01
7d mg/
L (T
CLP
)C
emen
t and
pro
prie
tary
addi
tives
4.16
14Pe
stic
ides
Soil
Full
--0.
60 m
g/L
(EPT
)28
.0 m
g/L
(WET
)0.
27 m
g/L
(EPT
)6.
5 m
g/L
(WET
)--
4.1
15Ph
arm
aceu
tical
3,80
0 to
ns sl
udge
and
soil
Full
--26
0,00
0 m
g/kg
4,31
0 - 4
,390
mg/
L(T
CLP
)
1.24
- 3.
44 m
g/L
(TC
LP)
Pota
ssiu
m p
ersu
lfate
,fe
rric
sulfa
te, a
ndce
men
t
4.15
16Tr
ansf
orm
er a
ndM
etal
Sal
vage
Soil
Full
Porta
ble
Equi
pmen
tSa
lvag
e C
o, O
R42
mg/
kg0.
004d m
g/L
(TC
LP)
Prop
rieta
ry b
inde
r4.
16
17W
ood
Pres
ervi
ng14
,800
cy
soil
Full
Mac
gilli
s And
Gib
bs/B
ell L
umbe
rA
nd P
ole
Supe
rfun
dSi
te, M
NFe
brua
ry 1
998
1 - 6
72 m
g/kg
55 m
g/L
(TC
LP)
Cem
ent
4.8
Tab
le 4
.1So
lidifi
catio
n/St
abili
zatio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
and
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e, L
ocat
ion,
and
Proj
ect
Com
plet
ion
Dat
eb
Initi
al A
rsen
icC
once
ntra
tion
(mg/
kg) o
rL
each
abili
ty(m
g/L
) (T
est
met
hod)
Fina
l Ars
enic
Con
cent
ratio
n(m
g/kg
) or
Lea
chab
ility
(mg/
L)
(Tes
t met
hod)
Bin
der
orSt
abili
zatio
n Pr
oces
sSo
urce
4-8
18W
ood
Pres
ervi
ngSo
ilFu
ll--
91 -
128
mg/
kg
0.01
5 - 0
.29
mg/
L R
educ
tion
ofhe
xava
lent
chr
omiu
mfo
llow
ed b
yst
abili
zatio
n w
ithce
men
t and
lim
e
4.16
19W
ood
Pres
ervi
ng13
,000
cy
soil
Full
Palm
etto
Woo
dPr
eser
ving
Sup
erfu
ndSi
te, S
C19
89
6,20
0 m
g/kg
0.02
mg/
L (T
CLP
)C
emen
t and
a p
Had
just
men
t age
nt4.
8
20V
eter
inar
y fe
edad
ditiv
es a
ndph
arm
aceu
tical
man
ufac
turin
g
400
tons
Full
Whi
tmoy
erLa
bora
torie
sSu
perf
und
Site
--<
5 m
g/L
(TC
LP)
Wat
er, f
erric
sulfa
te,
and
Portl
and
cem
ent
4.23
21El
ectri
cal s
ubst
atio
n1,
000
cy so
ilPi
lot
Flor
ida
1995
<0.5
-2,0
00 m
g/kg
1.42
- 3.
7 m
g/L
(TC
LP)
ND
- 0.
11 (T
CLP
)C
emen
t and
ferr
ous
sulfa
te4.
21,
4.22
22El
ectri
cal s
ubst
atio
n3,
300
cy so
ilPi
lot
Flor
ida
1995
<0.5
- 1,
900
mg/
kg0.
15 -
3.5
mg/
L(T
CLP
)
0.22
- 0.
38 (T
CLP
)C
emen
t and
ferr
ous
sulfa
te4.
21,
4.22
23W
ood
Pres
ervi
ngSo
ilPi
lot
Selm
a Pr
essu
reTr
eatin
g Su
perf
und
Site
, Sel
ma,
CA
1998
10 m
g/L
(TC
LP)
< 0.
1 m
g/L
(TC
LP)
Prop
rieta
ry b
inde
r4.
19
Tab
le 4
.1So
lidifi
catio
n/St
abili
zatio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
and
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e, L
ocat
ion,
and
Proj
ect
Com
plet
ion
Dat
eb
Initi
al A
rsen
icC
once
ntra
tion
(mg/
kg) o
rL
each
abili
ty(m
g/L
) (T
est
met
hod)
Fina
l Ars
enic
Con
cent
ratio
n(m
g/kg
) or
Lea
chab
ility
(mg/
L)
(Tes
t met
hod)
Bin
der
orSt
abili
zatio
n Pr
oces
sSo
urce
4-9
Indu
stri
al W
aste
s
24Fo
od-g
rade
H3P
O4
man
ufac
ture
from
phos
phat
e ro
ck
--Fu
ll--
70.0
mg/
L (T
CLP
)1.
58 m
g/L
(TC
LP)
--4.
1
25Fo
od-g
rade
H3P
O4
man
ufac
ture
from
phos
phat
e ro
ck
Ars
enou
stri
sulfi
deFu
ll--
5,00
0 - 4
0,00
0m
g/kg
0.43
mg/
L (T
CLP
)O
xida
tion
with
NaO
Han
d N
aOC
l fol
low
edby
stab
iliza
tion
with
bed
ash
4.1
26Fo
od-g
rade
H3P
O4
man
ufac
ture
from
phos
phat
e ro
ck
Ars
enou
stri
sulfi
deFu
ll--
5,00
0 - 4
0,00
0m
g/kg
<0.1
4 m
g/L
(TC
LP)
Oxi
datio
n w
ithhy
drat
ed li
me
and
NaO
Cl f
ollo
wed
by
stab
iliza
tion
with
bed
ash
4.1
27Fo
od-g
rade
H3P
O4
man
ufac
ture
from
phos
phat
e ro
ck
Ars
enou
stri
sulfi
deFu
ll--
5,00
0 - 4
0,00
0m
g/kg
<0.1
0 m
g/L
(TC
LP)
Pret
reat
men
t with
cem
ent a
nd C
aOC
l2fo
llow
ed b
yst
abili
zatio
n w
ith li
me
and
cem
ent
4.1
28--
Dry
was
teFu
ll--
0.00
5 m
g/L
(TC
LP)
<0.0
02 m
g/L
(TC
LP)
Cem
ent a
nd o
ther
unsp
ecifi
ed a
dditi
ves
4.4
29--
Dry
was
teFu
ll--
0.01
mg/
L (E
PT)
0.00
23 m
g/L
(TC
LP)
Cem
ent a
nd o
ther
unsp
ecifi
ed a
dditi
ves
4.4
30--
Slud
geFu
ll--
0.01
1 m
g/L
(EPT
)0.
002
mg/
L (E
PT)
Cem
ent a
nd o
ther
unsp
ecifi
ed a
dditi
ves
4.4
31--
Slud
geFu
ll--
0.01
4 m
g/L
(TC
LP)
<0.0
02 m
g/L
(TC
LP)
Cem
ent a
nd o
ther
unsp
ecifi
ed a
dditi
ves
4.4
Tab
le 4
.1So
lidifi
catio
n/St
abili
zatio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
and
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e, L
ocat
ion,
and
Proj
ect
Com
plet
ion
Dat
eb
Initi
al A
rsen
icC
once
ntra
tion
(mg/
kg) o
rL
each
abili
ty(m
g/L
) (T
est
met
hod)
Fina
l Ars
enic
Con
cent
ratio
n(m
g/kg
) or
Lea
chab
ility
(mg/
L)
(Tes
t met
hod)
Bin
der
orSt
abili
zatio
n Pr
oces
sSo
urce
4-10
32Pe
stic
ide
Pest
icid
e sl
udge
Full
--52
.0 m
g/L
(WET
)19
.0 m
g/L
(EPT
)5.
20 m
g/L
(WET
)0.
14 m
g/L
(EPT
)--
4.1
33W
aste
dis
posa
lH
azar
dous
was
tela
ndfil
l lea
chat
eFu
ll--
4.20
mg/
L (T
CLP
)0.
016
mg/
L (T
CLP
)--
4.1
34W
aste
trea
tmen
tH
azar
dous
was
tein
cine
rato
r ash
Full
--0.
07 m
g/L
(TC
LP)
0.01
9 m
g/L
(TC
LP)
--4.
1
35W
aste
trea
tmen
tH
azar
dous
was
tein
cine
rato
r pon
dsl
udge
Full
--0.
30 m
g/L
(TC
LP)
0.30
mg/
L (E
PT)
<0.0
1 m
g/L
(TC
LP)
<0.0
1 m
g/L
(EPT
)--
4.1
36G
lass
Man
ufac
turin
gD
004/
D00
5W
aste
Pilo
t--
296
mg/
L (T
CLP
)66
.3 m
g/L
(TC
LP)
Cem
ent a
nd fl
y as
h4.
14
37G
lass
Man
ufac
turin
gD
004/
D00
5W
aste
Pilo
t--
6 m
g/L
(TC
LP)
<1 m
g/L
(TC
LP)
Cem
ent a
nd fl
y as
h an
dfe
rrou
s sul
fate
4.14
38G
lass
Man
ufac
turin
gD
004/
D00
5W
aste
Pilo
t--
18 m
g/L
(TC
LP)
<1 m
g/L
(TC
LP)
Cem
ent a
nd fl
y as
h an
dfe
rric
sulfa
te4.
14
39M
inin
gM
ine
Taili
ngs
Pilo
tSp
ring
Hill
Min
e,M
onta
na6,
000
mg/
kgN
Dc (T
CLP
)Si
lica
Mic
roen
caps
ulat
ion
4.17
40--
D00
4, sp
ent
cata
lyst
Pilo
t--
280,
000
mg/
kg0.
79 m
g/L
(TC
LP)
1.25
mg/
L (a
lkal
ine
leac
hing
test
at p
H9.
5)
Che
mic
al o
xida
tion
ofw
aste
to fo
rm fe
rric
arse
nate
slud
ge,
follo
wed
by
stab
iliza
tion
with
lim
e
4.3
41--
P012
, As 2
O3
Pilo
t--
750,
000
mg/
kg<0
.05
- 0.5
9 m
g/L
(TC
LP)
0.34
- 0.
79 m
g/L
(alk
alin
e le
achi
ng te
stat
pH
9.5
)
Che
mic
al o
xida
tion
ofw
aste
to fo
rm fe
rric
arse
nate
slud
ge,
follo
wed
by
stab
iliza
tion
with
lim
e
4.3
Tab
le 4
.1So
lidifi
catio
n/St
abili
zatio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
and
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e, L
ocat
ion,
and
Proj
ect
Com
plet
ion
Dat
eb
Initi
al A
rsen
icC
once
ntra
tion
(mg/
kg) o
rL
each
abili
ty(m
g/L
) (T
est
met
hod)
Fina
l Ars
enic
Con
cent
ratio
n(m
g/kg
) or
Lea
chab
ility
(mg/
L)
(Tes
t met
hod)
Bin
der
orSt
abili
zatio
n Pr
oces
sSo
urce
4-11
42--
Slud
gePi
lot
--6,
430
mg/
L0.
823
mg/
L (T
CLP
)Em
bedd
ing
calc
ium
and
ferr
icar
sena
tes/
arse
nite
s in
ace
men
t mat
rix
4.20
In S
itu S
tabi
lizat
ion
Onl
y43
Agr
icul
tura
lap
plic
atio
n of
pest
icid
es
Soil,
5,0
00 c
ubic
yard
sFu
llW
isco
nsin
DN
R-
Orc
hard
Soi
lN
Dc -
50 m
g/L
(type
of a
naly
sis
not r
epor
ted)
ND
c - 1
mg/
L (ty
pe o
fan
alys
is n
ot re
porte
d)In
situ
trea
tmen
t of
cont
amin
ated
soil
byin
ject
ing
pHad
just
men
t age
nts a
ndph
osph
ates
4.6
44W
ood
pres
ervi
ngw
aste
s, so
il, 5
0,00
0cu
bic
yard
s
Soil,
50,
000
cubi
c ya
rds
Full
Silv
er B
owC
reek
/But
te A
rea
Supe
rfun
d Si
te, M
T19
98
----
In si
tu tr
eatm
ent o
fco
ntam
inat
ed so
il by
inje
ctin
g a
solu
tion
offe
rrou
s iro
n, li
mes
tone
,an
d po
tass
ium
perm
anga
nate
4.8
aEx
clud
es a
ll be
nch-
scal
e pr
ojec
ts.
Als
o ex
clud
es fu
ll- a
nd p
ilot-s
cale
pro
ject
s whe
re d
ata
on th
e le
acha
bilit
y of
stab
ilize
d w
aste
s are
not
ava
ilabl
e.b
Proj
ect c
ompl
etio
n da
tes p
rovi
ded
for S
uper
fund
rem
edia
l act
ion
proj
ects
onl
y.c
Det
ectio
n lim
it no
t pro
vide
d.d
Ana
lyze
d af
ter 2
8 da
ys.
See
Tabl
e 1.
2 fo
r lon
g-te
rm T
CLP
dat
a.
EPT
= Ex
tract
ion
proc
edur
e to
xici
ty te
st.
-- =
Not
ava
ilabl
eTC
LP =
Tox
icity
cha
ract
eris
tic le
achi
ng p
roce
dure
TWA
= T
otal
was
te a
naly
sis
WET
= W
aste
ext
ract
ion
test
OU
= O
pera
ble
Uni
tcy
= C
ubic
yar
dm
g/kg
= M
illig
ram
s per
kilo
gram
mg/
L =
Mill
igra
ms p
er li
ter
4-12
Tab
le 4
.2L
ong-
Ter
m S
olid
ifica
tion/
Stab
iliza
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
n
Initi
al A
rsen
icC
once
ntra
tion
(Tot
al W
aste
Ana
lysi
s)
Fina
l Ars
enic
Con
cent
ratio
n of
Lea
chab
ility
(28
day
cure
tim
e)
Lon
g-T
erm
Lea
chab
le A
rsen
icC
once
ntra
tion
(6 y
ear
cure
tim
e)B
inde
r or
Stab
iliza
tion
Proc
ess
Arc
hive
dFi
eld
1O
il Pr
oces
sing
&R
ecla
mat
ion
Filte
r cak
ean
d oi
lysl
udge
Full
Impe
rial O
il C
o. -
Cha
mpi
onC
hem
ical
Co.
Supe
rfun
d Si
te,
NJ
40 m
g/kg
ND
b (TC
LP)
0.00
9 m
g/L
(TC
LP)
0.00
5 m
g/L
(TC
LP)
Cem
ent a
ndpr
oprie
tary
addi
tives
2O
il Pr
oces
sing
&R
ecla
mat
ion
Soil
Full
Impe
rial O
il C
o. -
Cha
mpi
onC
hem
ical
Co.
Supe
rfun
d Si
te,
NJ
92 m
g/kg
0.01
7 m
g/L
(TC
LP)
0.02
1 m
g/L
(TC
LP)
0.02
2 m
g/L
(TC
LP)
Cem
ent a
ndpr
oprie
tary
addi
tives
3Tr
ansf
orm
er a
ndM
etal
Sal
vage
Soil
Full
Porta
ble
Equi
pmen
tSa
lvag
e C
o., O
R
42 m
g/kg
0.00
4 m
g/L
(TC
LP)
--0.
005
mg/
L(T
CLP
)Pr
oprie
tary
bind
er
Sour
ce:
4.16
aEx
clud
es a
ll be
nch-
scal
e pr
ojec
ts.
Als
o ex
clud
es fu
ll- a
nd p
ilot-s
cale
pro
ject
s whe
re d
ata
on th
e le
acha
bilit
y of
stab
ilize
d w
aste
s are
not
ava
ilabl
e.b
Det
ectio
n lim
it no
t pro
vide
d.
-- =
Not
ava
ilabl
e.N
D =
Not
det
ecte
d.TC
LP =
Tox
icity
cha
ract
eris
tic le
achi
ng p
roce
dure
.
5-1
Summary
Vitrification has been applied in a limited number ofprojects to treat arsenic-contaminated soil and waste. For soil treatment, the process can be applied eitherin situ or ex situ. This technology typically requireslarge amounts of energy to achieve vitrificationtemperatures, and therefore can be expensive tooperate. Off-gases may require further treatment toremove hazardous constituents.
Technology Description: Vitrification is a hightemperature treatment aimed at reducing themobility of metals by incorporating them into achemically durable, leach resistant, vitreous mass(Ref. 5.6). This process also may causecontaminants to volatilize or undergo thermaldestruction, thereby reducing their concentration inthe soil or waste.
Media Treated• Soil• Waste
Energy Sources Used for Vitrification:• Fossil fuels• Direct joule heat
Energy Delivery Mechanisms Used forVitrification:• Arcs• Plasma torches• Microwaves• Electrodes (in situ)
In Situ Application Depth:• Maximum demonstrated depth is 20 feet• Depths greater than 20 feet may require
innovative techniques
Off-GasCollection Hood
Electrodes
Off-Gasto Treatment
Melt Zone
Off-GasCollection Hood
Electrodes
Off-Gasto Treatment
Melt Zone
Model of an In Situ Vitrification System5.0 VITRIFICATION FOR ARSENIC
Technology Description and Principles
During the vitrification treatment process, the metalsare surrounded by a glass matrix and becomechemically bonded inside the matrix. For example,arsenates can be converted into silicoarsenates duringvitrification (Ref. 5.4).
Ex situ processes provide heat to a melter through avariety of sources, including combustion of fossil fuels,and input of electric energy by direct joule heating. Theheat may be delivered via arcs, plasma torches, andmicrowaves. In situ vitrification uses resistance heatingby passing an electric current through soil by means ofan array of electrodes (Ref. 5.6). In situ vitrificationcan treat up to 1,000 tons of soil in a single melt.
Vitrification occurs at temperatures from 2,000 to3,6000F (Ref. 5.1, 5.4). These high temperatures maycause arsenic to volatilize and contaminate the off-gasof the vitrification unit. Vitrification units typicallyemploy treatment of the off-gas using air pollutioncontrol devices such as baghouses (Ref. 5.5).
Pretreatment of the waste to be vitrified may reduce thecontamination of off-gasses with arsenic. For example,in one application (Project 15), prior to vitrification offlue dust containing arsenic trioxide (As2O3), a mixtureof the flue dust and lime was roasted at 400 0C toconvert the more volatile arsenic trioxide to less volatilecalcium arsenate (Ca3(AsO4)2) (Ref. 5.5). Solidresidues from off-gas treatment may be recycled intothe feed to the vitrification unit (Ref. 5.6).
The maximum treatment depth for in situ vitrificationhas been demonstrated to be about 20 feet (Ref. 5.6). Table 5.1 describes specific vitrification processes usedto treat soil and wastes containing arsenic.
Media and Contaminants Treated
Vitrification has been applied to soil and wastescontaminated with arsenic, metals, radionuclides, andorganics. This method is a RCRA best demonstratedavailable technology (BDAT) for various arsenic-containing hazardous wastes, including K031, K084,K101, K102, D004, and arsenic-containing P and Uwastes (Ref. 5.5, 5.6).
5-2
6
10
0 5 10
Pilot
Full 6
10
0 5 10
Pilot
Full
Case Study: Parsons Chemical Superfund SiteVitrification
The Parsons Chemical Superfund Site in GrandLedge, Michigan was an agricultural chemicalmanufacturing facility. Full-scale in situvitrification was implemented to treat 3,000 cubicyards of arsenic-contaminated soil. Initial arsenicconcentrations ranged from 8.4 to 10.1 mg/kg. Eightseparate melts were performed at the site, whichreduced arsenic concentrations to 0.717 to 5.49mg/kg . The concentration of leachable arsenic inthe treated soils ranged from <0.004 to 0.0305mg/L, as measured by the TCLP. The off-gasemissions had arsenic concentrations of <0.000269mg/m3, <0.59 mg/hr (see Table 5.1, Project 6).
Type, Number, and Scale of Identified ProjectsTreating Soil and Wastes Containing Arsenic
Vitrification of arsenic-contaminated soil and waste hasbeen conducted at both pilot and full scale. The sourcesfor this report contained information on ex situvitrification of arsenic-contaminated soil at pilot scaleat three sites and at full scale at one site. Informationwas also identified for two in situ applications forarsenic treatment at full scale. In addition, 7 pilot-scaleand 3 full-scale applications to industrial waste wereidentified. Figure 5.1 shows the number of applicationsidentified at each scale.
Figure 5.1Scale of Identified Vitrification Projects for Arsenic
Treatment
Summary of Performance Data
Table 5.1 lists the vitrification performance dataidentified in the sources used for this report. For ex situvitrification of soil, total arsenic concentrations prior totreatment ranged from 8.7 to 540 mg/kg (Projects 2 and4). Data on the leachability of arsenic from the vitrifiedproduct were available only for Project 4, for which theleachable arsenic concentration was reported as 0.9mg/L. For in situ vitrification of soil, total arsenicconcentrations prior to treatment ranged from 10.1 to4,400 mg/kg (Projects 6 and 5, respectively). Theleachability of arsenic in the stabilized soil and wasteranged from <0.004 to 0.91 mg/L (Projects 5 and 6).
For treatment of industrial wastes, the total arsenicconcentrations prior to treatment ranged from 27 to25,000 mg/kg (Projects 7 and 16) and leachableconcentrations in the vitrified waste ranged from 0.007mg/L to 2.5 mg/L (Projects 15 and 16). For some of theprojects listed in Table 5.1, the waste treated wasidentified as a spent potliner from primary aluminumreduction (RCRA waste code K088) but theconcentration of arsenic in the waste was not identified. Some K088 wastes contain relatively lowconcentrations of arsenic, and these projects mayinvolve treatment of such wastes.
The case study in this section discusses in greater detailthe in situ vitrification of arsenic-contaminated soil atthe Parsons Chemical Superfund Site. This informationis summarized in Table 5.1, Project 6.
Applicability, Advantages, and Potential Limitations
Arsenic concentrations present in soil or waste maylimit the performance of the vitrification treatmentprocess. For example, if the arsenic concentration inthe feed exceeds its solubility in glass, the technology’seffectiveness may be limited (Ref. 5.6). Metals retainedin the melt must be dissolved to minimize the formationof crystalline phases that can decrease leach resistanceof the vitrified product. The approximate solubility ofarsenic in silicate glass ranges from 1 - 3% by weight(Ref. 5.7).
The presence of chlorides, fluorides, sulfides, andsulfates may interfere with the process, resulting inhigher mobility of arsenic in the vitrified product. Feeding additional slag-forming materials such as sandto the process may compensate for the presence ofchlorides, fluorides, sulfides, and sulfates (Ref. 5.4). Chlorides, such as those found in chlorinated solvents,in excess of 0.5 weight percent in the waste willtypically fume off and enter the off-gas. Chlorides inthe off-gas may result in the accumulation of salts ofalkali, alkaline earth, and heavy metals in the solidresidues collected by off-gas treatment. If the residue isreturned to the process for treatment, separation of thechloride salts from the residue may be necessary. Whenexcess chlorides are present, dioxins and furans mayalso form and enter the off-gas treatment system (Ref.5.6). The presence of these constituents may also leadto the formation of volatile metal species or corrosiveacids in the off-gas (Ref. 5.7).
5-3
Factors Affecting Vitrification Performance
• Presence of halogenated organic compounds - The combustion of halogenated organiccompounds may result in incomplete combustionand the deposition of chlorides, which can resultin higher mobility of arsenic in the vitrifiedproduct (Ref. 5.4).
• Presence of volatile metals - The presence ofvolatile metals, such as mercury and cadmium,and other volatile inorganics, such as arsenic,may require treatment of the off-gas to reduce airemissions of hazardous constituents (Ref. 5.6).
• Particle size - Some vitrification units requirethat the particle size of the feed be controlled. For wastes containing refractory compounds thatmelt above the unit's nominal processingtemperature, such as quartz and alumina, sizereduction may be required to achieve acceptablethroughputs and a homogeneous melt. High-temperature processes, such as arcing andplasma processes may not require size reductionof the feed (Ref. 5.6).
• Lack of glass-forming materials - Ifinsufficient glass-forming materials (SiO2 >30%by weight) and combined alkali (Na + K > 1.4%by weight) are present in the waste the vitrifiedproduct may be less durable. The addition of fritor flux additives may compensate for the lack ofglass-forming and alkali materials (Ref. 5.6).
• Subsurface air pockets - For in situvitrification, subsurface air pockets, such asthose that may be associated with buried drums,can cause bubbling and splattering of moltenmaterial, resulting in a safety hazard (Ref. 5.10).
• Metals content - For in situ vitrification, ametals content greater than 15% by weight mayresult in pooling of molten metals at the bottomof the melt, resulting in electrical short-circuiting(Ref. 5.10).
• Organic content - For in situ vitrification, anorganic content of greater than 10% by weightmay cause excessive heating of the melt,resulting in damage to the treatment equipment(Ref. 5.10). High organics concentrations mayalso cause large volumes of off-gas as theorganics volatilize and combust, and mayoverwhelm air emissions control systems.
Factors Affecting Vitrification Costs
• Moisture content - Greater than 5% moisturein the waste may result in greater mobility ofarsenic in the final treated matrix. Thesewastes may require drying prior to vitrification(Ref. 5.4). Wastes containing greater than 25%moisture content may require excessive fuelconsumption or dewatering before treatment(Ref. 5.6).
• Characteristics of treated waste - Dependingupon the qualities of the vitrified waste, thetreated soil and waste may be able to be reusedor sold.
• Factors affecting vitrification performance -Items in the “Factors Affecting VitrificationPerformance” box will also affect costs.
During vitrification, combustion of the organic contentof the waste liberates heat, which will raise thetemperature of the waste, thus reducing the externalenergy requirements. Therefore, this process may beadvantageous to wastes containing a combination ofarsenic and organic contaminants or for the treatment oforgano-arsenic compounds. However, high
concentrations of organics and moisture may result inhigh volumes of off-gas as organics volatilize andcombust and water turns to steam. This can overwhelmemissions control systems.
Vitrification can also increase the density of treatedmaterial, thereby reducing its volume. In some cases,the vitrified product can be reused or sold. Vitrifiedwastes containing arsenic have been reused as industrialglass (Ref. 5.5). Metals retained in the melt that do notdissolve in the glass phase can form crystalline phasesupon cooling that can decrease the leach resistance ofthe vitrified product.
Excavation of soil is not required for in situvitrification. This technology has been demonstrated toa depth of 20 feet. Contamination present at greaterdepths may require innovative application techniques. In situ vitrification may be impeded by the presence ofsubsurface air pockets, high metals concentrations, andhigh organics concentrations (Ref. 5.10).
Summary of Cost Data
Cost information for ex situ vitrification of soil andwastes containing arsenic was not found in thereferences identified for this report. The cost for in situvitrification of 3,000 cubic yards of soil containingarsenic, mercury, lead, DDT, dieldrin and chlordane atthe Parsons Chemical Superfund site are presentedbelow (Ref. 5.8, cost year not provided):
• Treatability/pilot testing $50,000 - $150,000• Mobilization $150,000 - $200,000• Vitrification operation $375 - $425/ ton• Demobilization $150,000 - $200,000
5-4
References
5.1. TIO. Database for EPA REACH IT (RemediationAnd Characterization Innovative Technologies).March 2001. http://www.epareachit.org.
5.2. U.S. EPA. Arsenic & Mercury - Workshop onRemoval, Recovery, Treatment, and Disposal.Office of Research and Development. EPA-600-R-92-105. August 1992.
5.3. U.S. EPA. BDAT Background Document forSpent Potliners from Primary AluminumReduction - K088. Office of Solid Waste. February 1996. http://yosemite1.epa.gov/EE/epa/ria.nsf/ca2fb654a3ebbce28525648f007b8c26/22bebe132177e059852567e8006919c3?OpenDocument
5.4. U.S. EPA. Best Demonstrated AvailableTechnology (BDAT) Background Document forWood Preserving Wastes: F032, F034, and F035;Final. April 1996. http://www.epa.gov/epaoswer/hazwaste/ldr/wood/bdat_bd.pdf
5.5. U.S. EPA. Final Best Demonstrated AvailableTechnology (BDAT) Background Document forK031, K084, K101, K102, Characteristic ArsenicWastes (D004), Characteristic Selenium Wastes(D010), and P and U Wastes Containing Arsenicand Selenium Listing Constituents. Office ofSolid Waste. May 1990.
5.6. U.S. EPA Office of Research and Development. Engineering Bulletin, Technology Alternatives forthe Remediation of Soils Contaminated withArsenic, Cadmium, Chromium, Mercury, andLead. Cincinnati, OH. March 1997. http://www.epa.gov/ncepi/Catalog/EPA540S97500.html
5.7. U.S. EPA. Contaminants and Remedial Options atSelected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512.July 1995. http://www.epa.gov/ncepi/Catalog/EPA540R95512.html
5.8. Federal Remediation Technologies Roundtable(FRTR). In Situ Vitrification at the ParsonsChemical/ETM Enterprises Superfund Site GrandLedge, Michigan.http://www.frtr.gov/costperf.htm.
5.9. FRTR. In Situ Vitrification, U.S. Department ofEnergy, Hanford Site, Richland, Washington; OakRidge National Laboratory WAG 7; and VariousCommercial Sites. http://www.frtr.gov/costperf.htm.
5.10 U.S. EPA. SITE Technology Capsule, GeosafeCorporation In Situ Vitrification Technology. Office of Research and Development. EPA540/R-94/520a. November 1994. http://www.epa.gov/ORD/SITE/reports/540_r-94_520a.pdf.
Tab
le 5
.1V
itrifi
catio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic
5-5
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
e M
edia
or
Was
teSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
n
Vitr
ified
Pro
duct
and
Fina
l Ars
enic
Con
cent
ratio
nV
itrifi
catio
n Pr
oces
sD
escr
iptio
nSo
urce
Env
iron
men
tal M
edia
1M
etal
Ore
Min
ing
and
Smel
ting
Riv
er a
ndha
rbor
slud
gePi
lot
Ecot
echn
eik
B.V
., U
trech
t,N
ethe
rland
s
117
mg/
kg(T
WA
)A
rtific
ial g
rave
lR
otar
y ki
ln v
itrifi
catio
n at
1,15
0°C
5.1
2In
dust
rial L
andf
illM
ixtu
re o
fso
lids,
soil,
and
slud
ge
Pilo
tM
atan
za-
Ria
chue
loR
iver
,M
ondi
tech
,S.
A.,
Bue
nos
Aire
s, A
rgen
tina
8.7
- 12
mg/
kg(T
WA
)A
rtific
ial g
rave
l, 0.
01m
g/L
(TC
LP)
Seiz
ing,
grin
ding
, and
mill
ing
pret
reat
men
tfo
llow
ed b
y vi
trific
atio
n in
a ro
tary
kiln
at 1
,000
°C
5.1
3--
Soil,
400
tons
Full
Cha
tham
Doc
kyar
d, S
t.M
ary’
s Isl
and,
VER
T, K
ent,
Engl
and
--G
lass
fait
Was
tes a
re m
ixed
with
sand
and
lim
esto
ne a
nd fe
dto
a fu
rnac
e co
ntai
ning
apo
ol o
f mol
ten
glas
sm
aint
aine
d at
155
0°C
. G
lass
is re
mov
ed fr
ombo
ttom
of p
ool a
nd w
ater
cool
ed to
pro
duce
fait.
5.1
4--
Soil
Pilo
tU
nive
rsity
of
Pitts
burg
hA
pplie
dR
esea
rch
Cen
ter,
Har
mar
ville
, PA
540
mg/
kg(T
WA
)G
lass
cul
let 0
.9 m
g/L
(TC
LP)
Vor
tec
Cor
pora
tion
Adv
ance
d C
ombu
stio
nM
eltin
g Sy
stem
, cou
nter
-ro
tatin
g vo
rtex
com
bust
orfo
llow
ed b
y cy
clon
e m
elte
ran
d w
ater
que
nch
5.2
5R
CR
A w
aste
cod
eK
031
and
othe
rpe
stic
ide
was
tes
--Fu
ll--
4,40
0 m
g/kg
(TW
A)
0.91
mg/
L (T
CLP
)In
situ
vitr
ifica
tion
at 1
200
degr
ees C
with
uns
peci
fied
air p
ollu
tion
cont
rol
equi
pmen
t
5.5
Tab
le 5
.1V
itrifi
catio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
e M
edia
or
Was
teSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
n
Vitr
ified
Pro
duct
and
Fina
l Ars
enic
Con
cent
ratio
nV
itrifi
catio
n Pr
oces
sD
escr
iptio
nSo
urce
5-6
6A
gric
ultu
ral
chem
ical
sm
anuf
actu
ring
Soil,
3,0
00cu
bic
yard
sFu
llPa
rson
sC
hem
ical
Supe
rfun
d Si
te,
MI
8.4
- 10.
1 m
g/kg
(TW
A)
0.71
7 - 5
.49
mg/
kg(T
WA
)<0
.004
- 0.
0305
mg/
L(T
CLP
)
In si
tu v
itrifi
catio
n, e
ight
sepa
rate
mel
ts.
Stac
k ga
sem
issi
ons o
f ars
enic
<0.0
0026
9 m
illig
ram
s per
cubi
c m
eter
, <0.
59m
illig
ram
s per
hou
r.
5.8
Indu
stri
al W
aste
7In
cine
rato
r air
pollu
tion
cont
rol
scru
bber
was
tew
ater
Inci
nera
tor
ash
Pilo
tU
nive
rsity
of
Pitts
burg
hA
pplie
dR
esea
rch
Cen
ter,
Har
mar
ville
, PA
27 m
g/kg
(TW
A)
Gla
ss c
ulle
t 0.0
5 m
g/L
(TC
LP)
Vor
tec
Cor
pora
tion
Adv
ance
d C
ombu
stio
nM
eltin
g Sy
stem
, cou
nter
-ro
tatin
g vo
rtex
com
bust
orfo
llow
ed b
y cy
clon
e m
elte
ran
d w
ater
que
nch
5.2
8R
esid
ues f
rom
inci
nera
tion
ofm
unic
ipal
solid
was
te
Fly
ash
Pilo
tU
nive
rsity
of
Pitts
burg
hA
pplie
dR
esea
rch
Cen
ter,
Har
mar
ville
, PA
981
mg/
kg(T
WA
)G
lass
cul
let <
0.05
mg/
L(T
CLP
)V
orte
c C
orpo
ratio
nA
dvan
ced
Com
bust
ion
Mel
ting
Syst
em, c
ount
er-
rota
ting
vorte
x co
mbu
stor
follo
wed
by
cycl
one
mel
ter
and
wat
er q
uenc
h
5.2
9--
Haz
ardo
usba
ghou
se d
ust
Pilo
tU
nive
rsity
of
Pitts
burg
hA
pplie
dR
esea
rch
Cen
ter,
Har
mar
ville
, PA
--G
lass
cul
let <
0.02
mg/
L(T
CLP
)V
orte
c C
orpo
ratio
nA
dvan
ced
Com
bust
ion
Mel
ting
Syst
em, c
ount
er-
rota
ting
vorte
x co
mbu
stor
follo
wed
by
cycl
one
mel
ter
and
wat
er q
uenc
h
5.2
10Pr
imar
y al
umin
umre
duct
ion,
RC
RA
haza
rdou
s was
te c
ode
K08
8
Spen
tpo
tline
rs,
30,0
00 to
nspe
r yea
r
Full
Bar
nard
Envi
ronm
enta
l,R
ichl
and,
WA
--M
olte
n gl
ass
Terr
a-V
it pr
oces
s,re
sist
ance
hea
ting
usin
gel
ectro
des s
ubm
erge
d in
the
mol
ten
mas
s, m
olte
n gl
ass
efflu
ent i
s for
med
into
prod
ucts
5.3
Tab
le 5
.1V
itrifi
catio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
e M
edia
or
Was
teSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
n
Vitr
ified
Pro
duct
and
Fina
l Ars
enic
Con
cent
ratio
nV
itrifi
catio
n Pr
oces
sD
escr
iptio
nSo
urce
5-7
11Pr
imar
y al
umin
umre
duct
ion,
RC
RA
haza
rdou
s was
te c
ode
K08
8
Spen
tpo
tline
rs, 2
00- 3
00ki
logr
ams p
erho
ur
Pilo
tEl
kem
Tech
nolo
gy,
Nor
way
--Sl
agSl
aggi
ng p
roce
ss w
ithad
ditio
n of
iron
ore
and
quar
tz
5.3
12Pr
imar
y al
umin
umre
duct
ion,
RC
RA
haza
rdou
s was
te c
ode
K08
8, a
nd e
lect
ric a
rcfu
rnac
e du
st, R
CR
Aha
zard
ous w
aste
cod
eK
066
Spen
tpo
tline
rsPi
lot
Envi
rosc
ienc
e,In
c., V
anco
uver
,W
ashi
ngto
n
--Sl
ag w
ool
Extra
ctiv
e m
etal
lurg
ical
proc
ess c
ondu
cted
in a
shaf
t fur
nace
to p
rodu
cezi
nc, c
alci
um, a
nd le
adox
ides
in th
e ba
ghou
sedu
st, p
ig ir
on, a
nd m
iner
alw
ool
5.3
13Pr
imar
y al
umin
umre
duct
ion,
RC
RA
haza
rdou
s was
te c
ode
K08
8
Spen
tpo
tline
rsPi
lot
Orm
etC
orpo
ratio
n--
Indu
stria
l gla
ssSp
ent p
otlin
ers a
nd g
lass
-fo
rmin
g in
gred
ient
s are
vitri
fied
in a
n in
-flig
htsu
spen
sion
com
bust
orfo
llow
ed b
y a
cycl
one
sepa
ratio
n an
d m
eltin
gch
ambe
r
5.3
14Pr
imar
y al
umin
umre
duct
ion,
RC
RA
haza
rdou
s was
te c
ode
K08
8
Spen
tpo
tline
rsFu
llR
eyno
lds
Met
als
--K
iln re
sidu
e ha
s bee
nde
liste
d, d
ispo
sed
at n
on-
haza
rdou
s lan
dfill
Spen
t pot
liner
s, lim
esto
ne,
and
brow
n sa
nd a
re b
lend
edan
d fe
d to
a ro
tary
kiln
vitri
ficat
ion
unit
5.3
Tab
le 5
.1V
itrifi
catio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
e M
edia
or
Was
teSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
n
Vitr
ified
Pro
duct
and
Fina
l Ars
enic
Con
cent
ratio
nV
itrifi
catio
n Pr
oces
sD
escr
iptio
nSo
urce
5-8
15--
Flue
dus
tFu
ll--
--3,
000
- 235
,000
mg/
kg(T
WA
)0.
007
- 1.8
mg/
L (T
CLP
)
Roa
stin
g at
400
deg
rees
Cto
con
vert
arse
nic
triox
ide
to c
alci
um a
rsen
ate
follo
wed
by
vitri
ficat
ion
inan
iron
silic
ate
slag
at
1,29
0 de
gree
s C
5.5
16Ph
osph
oric
aci
dpr
oduc
tion,
RC
RA
haza
rdou
s was
te c
ode
D00
4
Slud
geco
ntai
ning
arse
nic
sulfi
de
Pilo
tR
hone
-Pou
lenc
20,0
00 -
25,0
00m
g/kg
(TW
A)
<0.5
- 0.
5 m
g/L
(EPT
)<0
.5 -
2.5
mg/
L (T
CLP
)--
5.5
a E
xclu
ding
ben
ch-s
cale
trea
tmen
ts --
= N
ot a
vaila
ble
WET
= W
aste
ext
ract
ion
test
C =
Cel
sius
TC
LP =
Tox
icity
cha
ract
eris
tic le
achi
ng p
roce
dure
EPT
= Ex
tract
ion
proc
edur
e to
xici
ty te
st T
WA
= T
otal
was
te a
naly
sis
6-1
ScrubbingUnit
Treatment Plant
Clean Soil
Contaminated Soil
Clean Water
Residual Soil
Reused Water
WashWater
Water andDetergent
ScrubbingUnit
Treatment Plant
Clean Soil
Contaminated Soil
Clean Water
Residual Soil
Reused Water
WashWater
Water andDetergent
Model of Soil Washing System
3
2
4
0 1 2 3 4
Bench
Pilot
Full
3
2
4
0 1 2 3 4
Bench
Pilot
Full
Summary
Soil washing/acid extraction (soil washing) has beenused to treat arsenic-contaminated soil in a limitednumber of applications. The process is limited tosoils in which contaminants are preferentiallyadsorbed onto the fines fraction. The separatedfines must be further treated to remove orimmobilize arsenic.
Technology Description: Soil washing is an exsitu technology that takes advantage of the behaviorof some contaminants to preferentially adsorb ontothe fines fraction. The soil is suspended in a washsolution and the fines are separated from thesuspension, thereby reducing the contaminantconcentration in the remaining soil.
Media Treated:� Soil (ex situ)
6.0 SOIL WASHING/ACID EXTRACTIONFOR ARSENIC
Technology Description and Principles
Soil washing uses particle size separation to reduce soilcontaminant concentrations. This process is based onthe concept that most contaminants tend to bind to thefiner soil particles (clay, silt) rather than the largerparticles (sand, gravel). Because the finer particles areattached to larger particles through physical processes(compaction and adhesion), physical methods can beused to separate the relatively clean larger particlesfrom the finer particles, thus concentrating thecontamination bound to the finer particles for furthertreatment (Ref. 6.7).
In this process, soil is first screened to removeoversized particles, and then homogenized. The soil isthen mixed with a wash solution consisting of water orwater enhanced with chemical additives such asleaching agents, surfactants, acids, or chelating agentsto help remove organics and heavy metals. Theparticles are separated by size (cyclone and/or gravityseparation depending on the type of contaminants in thesoil and particle size), concentrating the contaminantswith the fines. Because the soil washing processremoves and concentrates the contaminants but does notdestroy them, the resulting concentrated fines or sludgeusually require further treatment. The coarser-grainedsoil is generally relatively �clean�, requiring no
additional treatment. Wash water from the process istreated and either reused in the process, or disposed(Ref. 6.7). Commonly used methods for treating thewastewater include ion exchange and solventextraction. Media and Contaminants Treated
Soil washing is suitable for use on soils contaminatedwith SVOCs, fuels, heavy metals, pesticides, and someVOCs, and works best on homogenous, relativelysimple contaminant mixtures (Ref. 6.1, 6.4, 6.7). Soilwashing has been used to treat soils contaminated witharsenic.
Type, Number, and Scale of Identified ProjectsTreating Soil and Wastes Containing Arsenic
Nine projects were identified where soil washing wasperformed to treat arsenic. Of these, four wereperformed at full scale, including two at Superfundsites. Three projects were conducted at pilot scale, andtwo at bench scale (Ref. 6.4). Figure 6.1 shows thenumber of arsenic soil washing projects at bench, pilot,and full scale.
Figure 6.1Scale of Identified Soil Washing/Acid Extraction
Projects for Arsenic Treatment
6-2
Factors Affecting Soil Washing Performance
• Soil homogeneity - Soils that vary widely andfrequently in characteristics such as soil type,contaminant type and concentration, and whereblending for homogeneity is not feasible, maynot be suitable for soil washing (Ref. 6.1).
• Multiple contaminants - Complex,heterogeneous contaminant compositions canmake it difficult to formulate a simple washingsolution, requiring the use of multiple,sequential washing processes to removecontaminants (Ref. 6.1).
• Moisture content - The moisture content of thesoil may render its handling more difficult. Moisture content may be controlled by coveringthe excavation, storage, and treatment areas toreduce the amount of moisture in the soil (Ref.6.1).
• Temperature - Cold weather can cause thewashing solution to freeze and can affectleaching rates (Ref. 6.1).
Factors Affecting Soil Washing Costs
• Soil particle size distribution - Soils with ahigh proportion of fines may require disposalof a larger amount of treatment residual.
• Residuals management - Residuals from soilwashing, including spent washing solution andremoved fines, may require additionaltreatment prior to disposal.
• Factors affecting soil washing performance -Items in the “Factors Affecting Soil WashingPerformance” box will also affect costs.
Case Study: King of Prussia Superfund Site
The King of Prussia Superfund Site in WinslowTownship, New Jersey is a former waste processingand recycling facility. Soils were contaminated witharsenic, berylllium, cadmium, chromium, copper,lead, mercury, nickel, selenium, silver, and zincfrom the improper disposal of wastes (Project 1). Approximately 12,800 cubic yards of arsenic-contaminated soil, sludge, and sediment was treatedusing soil washing in 1993. The treatment reducedarsenic concentrations from 1 mg/kg to 0.31 mg/kg,a reduction of 69%.
Summary of Performance Data
Table 6.1. lists the available performance data. For soiland waste, this report focuses on performance dataexpressed as the leachability of arsenic in the treatedmaterial. However, arsenic leachability data are notavailable for any of the projects in Table 6.1. The casestudy in this section discusses in greater detail the soilwashing to treat arsenic at the King of PrussiaSuperfund Site. This information is summarized inTable 6.1, Project 1.
Applicability, Advantages, and Potential Limitations
The principal advantage of soil washing is that it can beused to reduce the volume of material requiring furthertreatment (Ref. 6.3). However, this technology isgenerally limited to soils with a range of particle sizedistributions, and contaminants that preferentiallyadsorb onto the fines fraction.
Summary of Cost Data
Table 6.1. shows the reported costs for soil washing totreat arsenic. The unit costs range from $30 to $400 per
ton of material treated (costs not adjusted to a consistentcost year). For one project treating 19,200 tons of soil,sludge, and sediment (Table 6.1, Project 1), the totalreported treatment costs, including off-site disposal oftreatment residuals, was $7.7 million, or $400/ton (Ref.6.6, 6.8, cost year not provided).
References
6.1. U.S. EPA. Engineering Bulletin. TechnologyAlternatives for the Remediation of SoilsContaminated with Arsenic, Cadmium,Chromium, Mercury, and Lead. Office ofEmergency and Remedial Response. 540-S-97-500. March 1997. http://www.epa.gov/ncepi/Catalog/EPA540S97500.html
6.2. U.S. EPA. A Citizen’s Guide to Soil Washing.Office of Solid Waste and Emergency Response. EPA 542-F-96-002. April 1996. http://www.epa.gov/tio/download/remed/soilwash.pdf.
6.3. U.S. EPA. Treatment Technology Performanceand Cost Data for Remediation of WoodPreserving Sites. Office of Research andDevelopment. EPA-625-R-97-009. October1997. http://www.epa.gov/ncepi/Catalog/EPA625R97009.html
6.4. U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition).
6-3
Office of Solid Waste and Emergency Response.EPA-542-R-01-004. February 2001. http://clu-in.org/asr.
6.5. U.S. EPA. Database for EPA REACH IT(REmediation And CHaracterization InnovativeTechnologies). March 2001. http://www.epareachit.org.
6.6. U.S. EPA. Contaminants and Remedial Optionsat Selected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512.July 1995.
6.7. Federal Remediation Technologies Roundtable: Remediation Technologies Screening Matrix andReference Guide Version 3.0. November 2000.http://www.frtr.gov/matrix2/top_page.html.
6.8. Federal Remediation Technologies Roundtable(FRTR). Soil Washing at the King of PrussiaTechnical Corporation Superfund Site. http://www.frtr.gov/costperf.htm.
6-4
Tab
le 6
.1A
rsen
ic S
oil W
ashi
ng T
reat
men
t Cos
t and
Per
form
ance
Dat
a fo
r A
rsen
ic
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
ale
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Soil
Was
hing
Age
nt o
rPr
oces
sC
ost
($/to
n)a
Sour
ce1
Was
te tr
eatm
ent,
recy
clin
g, a
nddi
spos
al
Soil
(12,
800
cy)
Full
Kin
g of
Pru
ssia
Supe
rfun
d Si
te,
Win
slow
Tow
nshi
p,N
J
1 m
g/kg
(TW
A)
0.31
mg/
kg(T
WA
)Sc
reen
ing,
sepa
ratio
n, a
ndfr
oth
flota
tion
$400
6.4,
6.8
2Pe
stic
ide
man
ufac
turin
gSo
il(1
80,0
00 c
y)Fu
llV
inel
and
Che
mic
alC
ompa
ny S
uper
fund
Site
, Ope
rabl
e U
nit 0
1V
inel
and,
NJ
----
----
6.4
3In
orga
nic
chem
ical
man
ufac
turin
g,w
ood
pres
ervi
ng
Soil
(500
0 cy
)Fu
llTe
r Ape
l, M
oerd
ijk,
Net
herla
nds
15 -
455
mg/
kg(T
WA
)20
mg/
kg (T
WA
)--
--6.
5
4--
Soil
Full
--25
0 m
g/kg
(TW
A)
20 m
g/kg
(TW
A)
--$1
00 -
$300
6.6
5H
erbi
cide
man
ufac
turin
g,ex
plos
ives
man
ufac
turin
g
Soil
(130
cy)
Pilo
t--
97 -
227
mg/
kg(T
WA
)6.
6 - 1
42 m
g/kg
(TW
A)
--$6
56.
5
6M
uniti
ons
Man
ufac
turin
gSo
il,se
dim
ents
,an
d ot
her
solid
s (4
00 c
y)
Pilo
t--
2 - 1
29 m
g/kg
(TW
A)
0.61
- 3.
1(m
g/kg
)--
$80
6.5
7M
uniti
ons
Man
ufac
turin
gSo
ilPi
lot
----
----
--6.
5
8Pe
stic
ide
man
ufac
turin
gSo
ilB
ench
Cam
p Pe
ndle
ton
Mar
ine
Cor
ps B
ase
Supe
rfun
d Si
te, C
A
4.5
mg/
kg(T
WA
)3
mg/
kg (T
WA
)--
--6.
5
9W
ood
pres
ervi
ngSe
dim
ent
Ben
chTh
unde
r Bay
,O
ntar
io, C
anad
a9.
1 m
g/kg
(TW
A)
0.01
5 m
g/kg
(TW
A)
----
6.3
aC
ost y
ear n
ot p
rovi
ded.
mg/
kg =
mill
igra
ms p
er k
ilogr
am--
= N
ot a
vaila
ble
TWA
= T
otal
was
te a
naly
sis
cy =
Cub
ic y
ards
7-1
Summary
Information gathered for this report indicate thatpyrometallurgical processes have been implementedto recover arsenic from soil and wastes in four full-scale applications. These technologies may haveonly limited application because of their cost ($208- $458 per ton in 1991 dollars) and because the costof importing arsenic is generally lower thanreclaiming it using pyrometallurgical processes(Ref. 7.6). The average cost of imported arsenicmetal in 1999 was $0.45 per pound (Ref. 7.6, in1999 dollars). In order to make recoveryeconomically feasible, the concentration of metals inthe waste should be over 10,000 mg/kg (Ref. 7.2).
Technology Description: Pyrometallurgicalrecovery processes use heat to convert an arsenic-contaminated waste feed into a product with a higharsenic concentration that can be reused or sold.
Media Treated• Soil• Industrial wastes
Types of Pyrometallurgical Processes• High temperature metals recovery• Slag cleaning process
0
4
0 1 2 3 4
Pilot
Full
7.0 PYROMETALLURGICAL RECOVERYFOR ARSENIC
Technology Description and Principles
A variety of processes reportedly have been used torecover arsenic from soil and waste containing arsenic. High temperature metals recovery (HTMR) involvesheating a waste feed to cause metals to volatilize or“fume”. The airborne metals are then removed with theoff-gas and recovered, while the residual solid materialsare disposed. Other pyrometallurgical technologiestypically involve modifications at metal refiningfacilities to recover arsenic from process residuals. The Metallurgie-Hoboken-Overpelt (MHO) slagcleaning process involves blast smelting with theaddition of coke as a reducing agent of primary andsecondary materials from lead, copper, and ironsmelting operations (Ref. 7.9).
Media and Contaminants Treated
This technology has recovered heavy metals, such asarsenic and lead, from soil, sludge, and industrialwastes (Ref. 7.8). The references used for this reportcontained information on applications of HTMR torecover arsenic from contaminated soil (Ref. 7.3) andsecondary lead smelter soda slag (Ref. 7.8). Inaddition, one metals refining process that was modifiedto recover arsenic (Ref. 7.9) was identified. Therecycling and reuse of arsenic from consumer end-product scrap is not typically done (Ref. 7.6).
Type, Number, and Scale of Identified ProjectsTreating Soil and Wastes Containing Arsenic
This report identified application of pyrometallurgicalrecovery of arsenic at full scale at four facilities (Ref.7.3, 7.8, 7.9). No pilot-scale projects for arsenic werefound.
Figure 7.1Scale of Identified Pyrometallurgical Projects for
Arsenic Treatment
Summary of Performance Data
Table 7.1 presents the available performance data.Because this technology typically generates a productthat is reused instead of disposed, the performance ofthese processes is typically measured by the percentremoval of arsenic from the waste, the concentration ofarsenic in the recovered product, and the concentrationof impurities in the recovered product. Other soil andwaste treatment processes are usually evaluated byleach testing the treated materials.
Both of the soil projects identified have feed and treatedmaterial arsenic concentrations. One project had an
7-2
Case Study: National Smelting and RefiningCompany Superfund Site, Atlanta, Georgia
Secondary lead smelter slag from the NationalSmelting and Refining Company Superfund Site inAtlanta, Georgia was processed using hightemperature metals recovery at a full-scale facility. The initial waste feed had an arsenic concentrationrange of 428 to 1,040 mg/kg. The effluent slagconcentration ranged from 92.1 to 1,340 mg/kg ofarsenic, but met project goals for arsenic leachability(<5 mg/L TCLP). The oxide from the baghousefumes had an arsenic concentration of 1,010 to 1,170mg/kg; however, the arsenic was not recovered (Ref.7.8) (see Project 3, Table 7.1).
Factors Affecting Pyrometallurgical RecoveryPerformance
• Particle size - Larger particles do not allowheat transfer between the gas and solid phasesduring HTMR. Smaller particles may increasethe particulate in the off-gas.
• Moisture content - A high water contentgenerally reduces the efficiency of HTMRbecause it increases energy requirements.
• Thermal conductivity - Higher thermalconductivity of the waste results in better heattransfer into the waste matrix during HTMR(Ref. 7.2).
• Presence of impurities - Impurities, such asother heavy metals, may need to be removed,which increases the complexity of the treatmentprocess.
Factors Affecting Pyrometallurgical RecoveryCosts
• Factors affecting pyrometallurgical recoveryperformance - Items in the “Factors AffectingPyrometallurgical Recovey Performance” boxwill also affect costs.
arsenic feed concentration of 86 mg/kg and a treatedarsenic concentration of 6.9 mg/kg (Project 1). Theother project had an leachable arsenic concentration inthe feed of 0.040 mg/L and 0.019 mg/L in the treatedmaterial (Project 2).
Both of the industrial waste projects identified havefeed and residual arsenic data, and one has post-treatment leachability data. The feed concentrationsranged from 428 to 2,100 mg/kg (Projects 3 and 4). The residual arsenic concentrations ranged from 92.1 to1,340 mg/kg, with less than 5 mg/L leachability (Project3).
The case study in this section discusses in greater detailan HTMR application at the National Smelting andRefining Company Superfund Site. This information issummarized in Table 7.1, Project 3.
Applicability, Advantages, and Potential Limitations
Although recovering arsenic from soil and wastes isfeasible, it has not been done in the U.S. on a largescale because it is generally less expensive to importarsenic than to obtain it through reclamation processes(Ref. 7.5-7). The cost of importing arsenic in 1999 wasapproximately $0.45 per pound (Ref. 7.6, in 1999dollars). In order to make recovery economicallyfeasible, the concentration of metals in the waste shouldbe over 10,000 mg/kg (Ref. 7.2). In some cases, thepresence of other metals in the waste, such as copper,may provide sufficient economic incentive to recovercopper and arsenic together for the manufacture ofarsenical wood preservatives (Ref. 7.1). However,concern over the toxicity of arsenical woodpreservatives is leading to its phase-out (Ref. 7.10).
At present, arsenic is not being recovered domesticallyfrom arsenical residues and dusts at nonferroussmelters, although some of these materials areprocessed for the recovery of other materials (Ref. 7.6).
This technology may produce treatment residuals suchas slag, flue dust, and baghouse dust. Although someresiduals may be treated using the same process thatgenerated them, the residuals may require additionaltreatment or disposal.
Summary of Cost Data
The estimated cost of treatment using HTMR rangesfrom $208 to $458 per ton (in 1991 dollars). However,these costs are not specific to treatment of arsenic (Ref.7.2). No cost data for pyrometallurgical recovery forarsenic was found.
7-3
References
7.1 U.S. EPA. Arsenic & Mercury - Workshop onRemoval, Recovery, Treatment, and Disposal.Office of Research and Development. EPA-600-R-92-105. August 1992.
7.2 U.S. EPA. Contaminants and Remedial Optionsat Selected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512. July 1995. http://www.epa.gov/ncepi/Catalog/EPA540R95512.html
7.3 U.S. EPA National Risk Management ResearchLaboratory. Treatability Database. March 2001.
7.4 Code of Federal Regulations, Part 40, Section268. http://lula.law.cornell.edu/cfr/cfr.php?title=40&type=part&value=268
7.5 U.S. EPA. Final Best Demonstrated AvailableTechnology (BDAT) Background Document forK031, K084, K101, K102, Characteristic ArsenicWastes (D004), Characteristic Selenium Wastes(D010), and P and U Wastes Containing Arsenicand Selenium Listing Constituents. Office ofSolid Waste. May 1990.
7.6 U.S. Geological Survey. Mineral CommoditySummaries. February 2000.http://minerals.usgs.gov/minerals/pubs/commodity/soda_ash/610300.pdf
7.7 U.S. EPA. Engineering Bulletin. TechnologyAlternatives for the Remediation of SoilsContaminated with Arsenic, Cadmium,Chromium, Mercury, and Lead. Office ofEmergency and Remedial Response. March 1997. http://www.epa.gov/ncepi/Catalog/EPA540S97500.html
7.8 U.S. EPA. Superfund Innovative TechnologyEvaluation Program. Technology Profiles TenthEdition. Volume 1 Demonstration Program.Office of Research and Development. EPA-540-R-99-500a. February 1999. http://www.epa.gov/ncepi/Catalog/EPA540R99500A.html
7.9 U.S. EPA. Profiles of Metal RecoveryTechnologies for Mineral Processing and OtherMetal-Bearing Hazardous Wastes. December1994.
7.10 U.S. EPA. Manufacturers to Use New WoodPreservatives, Replacing Most Residential Uses ofCCA. February 12, 2002. http://www.epa.gov/pesticides/citizens/cca_transition.htm
7-4
Tab
le 7
.1A
rsen
ic P
yrom
etal
lurg
ical
Rec
over
y Pe
rfor
man
ce D
ata
for
Ars
enic
Proj
ect
Num
ber
Indu
stry
or S
iteT
ype
Med
ia o
rW
aste
Rec
laim
edSc
ale
Site
Nam
e or
Loc
atio
n
Rec
lam
atio
nPr
oces
s Fee
dA
rsen
icC
once
ntra
tion
Rec
lam
atio
n Pr
oces
sR
esid
ual A
rsen
icC
once
ntra
tion
Rec
over
ed A
rsen
icC
once
ntra
tion
Rec
lam
atio
nPr
oces
s Use
dSo
urce
Env
iron
men
tal M
edia
1--
Soil
(am
ount
not
avai
labl
e)Fu
ll--
86 m
g/kg
(TW
A)
6.9
mg/
kg (T
WA
)--
HTM
R7.
3
2--
Soil
(am
ount
not
avai
labl
e)Fu
ll--
0.04
0 m
g/L
(TC
LP)
0.01
9 m
g/L
(TC
LP)
--H
TMR
7.3
Indu
stri
al W
aste
s3
--Se
cond
ary
lead
smel
ter s
oda
slag
(72
tons
)
Full
Nat
iona
lSm
eltin
g an
dR
efin
ing
Com
pany
Supe
rfun
dSi
te, A
tlant
a,G
A
428
- 1,0
40 m
g/kg
(TW
A)
Slag
, 92.
1 - 1
,340
mg/
kg (T
WA
)Sl
ag, <
5 m
g/L
(TC
LP)
Ars
enic
trio
xide
,1,
010
- 1,1
70 m
g/kg
(TW
A)
HTM
R7.
8
4--
Prim
ary
and
seco
ndar
ym
ater
ials
(add
ition
alde
scrip
tion
ofm
ater
ials
not
avai
labl
e)
Full
Hob
oken
,B
elgi
um2,
100
mg/
kg(T
WA
)Sl
ag, 1
00 m
g/kg
(TW
A)
zinc
flue
dus
t, 1,
000
mg/
kg (T
WA
)
Lead
-cop
per-
iron
allo
y, 5
2,00
0 m
g/kg
(TW
A)
lead
bul
lion,
3,9
00m
g/kg
(TW
A)
Ars
enic
trio
xide
(con
cent
ratio
n no
tav
aila
ble)
MH
O7.
9
TCLP
= T
oxic
ity C
hara
cter
istic
Lea
chin
g Pr
oced
ure.
TWA
= T
otal
Was
te A
naly
sis.
-- =
Not
ava
ilabl
eH
TMR
= H
igh
Tem
pera
ture
Met
als R
ecov
ery.
MH
O =
Met
allu
rgie
-Hob
oken
-Ove
rpel
t pro
cess
.
8-1
Contaminated Soil
Wel
l
Wel
l
Surfactant, Cosolvent, or Water Mixture
Ground Surface
Contaminated Soil
Wel
l
Wel
l
Surfactant, Cosolvent, or Water Mixture
Ground Surface
Model of an In Situ Flushing System
2
2
0 1 2 3
Pilot
Full
Summary
Data gathered for this report show that in situ soilflushing has been used to treat arsenic-contaminatedsoils in a limited number of applications. Twoprojects have been identified that are currentlyoperating at full scale, but performance results arenot yet available.
Technology Description: In situ soil flushing is atechnology that extracts organic and inorganiccontaminants from soil by using water, a solution ofchemicals in water, or an organic extractant, withoutexcavating the contaminated material itself. Thesolution is injected into or sprayed onto the area ofcontamination, causing the contaminants to becomemobilized by dissolution or emulsification. Afterpassing through the contamination zone, thecontaminant-bearing flushing solution is collectedby downgradient wells or trenches and pumped tothe surface for removal, treatment, discharge, orreinjection (Ref. 8.1).
Media Treated:• Soil (in situ)
8.0 IN SITU SOIL FLUSHING FOR ARSENIC
Technology Description and Principles
In situ soil flushing techniques may employ water or amixture of water and additives as the flushing solution. Additives may include acids (sulfuric, hydrochloric,nitric, phosphoric, or carbonic acid), bases (forexample, sodium hydroxide), chelating or complexingagents (such as EDTA), reducing agents, or surfactantto aid in the desorption and dissolution of the targetcontaminants (Ref. 8.1).
Subsurface containment barriers or other hydrauliccontrols have sometimes been used in conjunction withsoil flushing to help control the flow of flushing fluidsand assist in the capture of the contaminated fluid. Impermeable membranes have also been used in somecases to limit infiltration of groundwater, which couldcause dilution of flushing solutions and loss ofhydraulic control (Ref. 8.1).
Media and Contaminants Treated
Soil flushing has been used to treat soils in situcontaminated with organic, inorganic, and metalcontaminants (Ref. 8.1), including arsenic.
Type, Number, and Scale of Identified ProjectsTreating Soil Containing Arsenic
The references identified for this report containedinformation on two full-scale in situ soil flushingprojects for the treatment of arsenic at two Superfundsites (Ref. 8.4), and two at pilot scale at two other sites(Ref. 8.6, 8.7). At one of the Superfund sites, 150,000cubic yards of soil are being treated, while at the other19,000 cubic yards of soil are being treated. Figure 8.1shows the number of projects identified at pilot and fullscale.
Figure 8.1Scale of Identified In Situ Soil Flushing Projects for
Arsenic Treatment
Summary of Performance Data
Arsenic treatment is ongoing at two Superfund sitesusing in situ soil flushing, and has been completed attwo other sites (Ref. 8.3, 8.4, 8.6, 8.7). Performancedata for the Superfund site projects are not yet available
8-2
Case Study: Vineland Chemical CompanySuperfund Site
The Vineland Chemical Company Superfund Site inVineland, New Jersey is a former manufacturingfacility for herbicides containing arsenic. Soilswere contaminated with arsenic from the improperstorage and disposal of herbicide by-product salts (RCRA waste code K031). Approximately 150,000cubic yards of soil were treated. Pretreatmentarsenic concentrations were as high as 650 mg/kg. The soil was flushed with groundwater from thesite, which was extracted, treated to remove arsenic,and reinjected into the contaminated soil. Becausethe species of arsenic contaminating the soil ishighly soluble in water, the addition of surfactantsand cosolvents was not necessary. No data arecurrently available on the treatment performance(Ref. 8.3, 8.4, 8.8) (see Project 1, Table 8.1). Theremedy at this site was changed to soil washing inorder to reduce treatment cost and the time neededto remediate the site.
Factors Affecting Soil Flushing Performance
• Number of contaminants treated - Thetechnology works best when a singlecontaminant is targeted. Identifying a flushingfluid that can effectively remove multiplecontaminants may be difficult (Ref. 8.1).
• Soil characteristics - Some soil characteristicsmay effect the performance of soil flushing. For example, an acidic flushing solution mayhave reduced effectiveness in an alkaline soil(Ref. 8.1).
• Precipitation - Soil flushing may cause arsenicor other chemicals in the soil to precipitate andobstruct the soil pore structure and inhibit flowthrough the soil (Ref. 8.1).
• Temperature - Low temperatures may causethe flushing solution to freeze, particularlywhen shallow infiltration galleries and above-ground sprays are used to apply the flushingsolution (8.1).
Factors Affecting Soil Flushing Costs
• Reuse of flushing solution - The ability toreuse the flushing solution may reduce the costby reducing the amount of flushing solutionrequired (Ref. 8.1).
• Contaminant recovery - Recovery ofcontaminants from the flushing solution and thereuse or sale of recovered contaminants may bepossible in some cases (Ref. 8.3, 8.4).
• Factors affecting soil flushing performance -Items in the “Factors Affecting Soil FlushingPerformance” box will also affect costs.
as the projects are ongoing. Performance data are alsonot available for the other two projects. See Table 8.1for information on these projects. The case study in thissection discusses in greater detail a soil flushingapplication at the Vineland Chemical CompanySuperfund Site. This information is summarized inTable 8.1, Project 3.
Applicability, Advantages, and Potential Limitations
The equipment used for in situ soil flushing is relativelyeasy to construct and operate, and the process does notinvolve excavation or disposal of the soil, therebyavoiding the expense and hazards associated with theseactivities (Ref. 8.1). Spent flushing solutions mayrequire treatment to remove contaminants prior to reuseor disposal. Treatment of flushing fluid results inprocess sludges and residual solids, such as spentcarbon and spent ion exchange resin, which may requiretreatment before disposal. In some cases, the spentflushing solution may be discharged to a publicly-owned treatment works (POTW), or reused in theflushing process. Residual flushing additives in the soilmay be a concern and should be evaluated on a site-specific basis (Ref. 8.1). In addition, soil flushing maycause contaminants to mobilize and spread touncontaminated areas of soil or groundwater.
Summary of Cost Data
No data are currently available on the cost of soilflushing systems used to treat arsenic.
References
8.1. U.S. EPA. Engineering Bulletin. TechnologyAlternatives for the Remediation of SoilsContaminated with Arsenic, Cadmium,Chromium, Mercury, and Lead. Office ofEmergency and Remedial Response. EPA 540-S-97-500. March 1997. http://www.epa.gov/ncepi/Catalog/EPA540S97500.html
8-3
8.2. U.S. EPA. Contaminants and Remedial Optionsat Selected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512July 1995. http://www.epa.gov/ncepi/Catalog/EPA540R95512.html
8.3. U.S. EPA. Database for EPA REACH IT(REmediation And CHaracterization InnovativeTechnologies). March 2001. http://www.epareachit.org.
8.4. U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition). Office of Solid Waste and Emergency Response. EPA-542-R-01-004. February 2001. http://www.epa.gov/ncepi/Catalog/EPA542R01004.html
8.5. U.S. EPA. Recent Developments for In SituTreatment of Metals Contaminated Soil. EPAMarch 1997. http://clu-in.org
8.6 Redwine JC. Innovative Technologies forRemediation of Arsenic in Soil and Groundwater. Southern Company Services, Inc. Presented at theAir and Waste Management Association’s 93rd
Annual Conference and Exhibition, Salt LakeCity, June 2000.
8.7 Miller JP, Hartsfield TH, Corey AC, Markey RM. In Situ Environmental Remediation of anEnergized Substation. EPRI. Palo Alto, CA.Report No. 1005169. 2001.
8.8 U.S. EPA. Vineland Chemical Company, Inc.Fact Sheet. April 2002. http://www.epa.gov/region02/superfund/npl/0200209c.pdf
8-4
Tab
le 8
.1A
rsen
ic In
Situ
Soi
l Flu
shin
g Pe
rfor
man
ce D
ata
for
Ars
enic
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
ale
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Soil
Flus
hing
Age
nt o
rPr
oces
sSo
urce
1Pe
stic
ide
man
ufac
turin
gSo
il(1
50,0
00 c
y)Fu
llV
inel
and
Che
mic
alC
ompa
ny S
uper
fund
Site
, Ope
rabl
e U
nit 0
1V
inel
and,
NJ
20 -
650
mg/
kg(T
WA
)--
Flus
hing
with
gro
undw
ater
follo
wed
by
extra
ctio
n,tre
atm
ent,
and
reus
e to
flus
hso
il. P
roje
ct w
as c
hang
ed to
soil
was
hing
prio
r to
com
plet
ion.
8.3,
8.4
,8.
8
2Pr
imar
yal
umin
umpr
oduc
tion
Soil
(19,
000
cy)
Full
Orm
et S
uper
fund
Site
,H
anni
bal,
OH
--0.
027
mg/
LFl
ushi
ng w
ith w
ater
follo
wed
by e
xtra
ctio
n, tr
eatm
ent,
and
disc
harg
e to
surf
ace
wat
erun
der a
n N
PDES
per
mit.
Pr
ojec
t com
plet
ion
isex
pect
ed in
200
7.
8.3,
8.4
3Po
wer
subs
tatio
nSo
ilPi
lot
Ft. W
alto
n B
each
, FL
----
Flus
hing
with
0.0
1 M
phos
phor
ic a
cid.
8.7
4Po
wer
subs
tatio
nSo
ilPi
lot
Flor
ida
----
Trea
tmen
t tra
in c
onsi
stin
g of
flush
ing
with
citr
ic a
cid
follo
wed
by
iron
copr
ecip
itatio
n an
d ce
ram
icm
embr
ane
filtra
tion.
8.6
mg/
kg =
mill
igra
ms p
er k
ilogr
amm
g/L
= m
illig
ram
s per
lite
r
-- =
Not
ava
ilabl
eTW
A =
Tot
al w
aste
ana
lysi
s
IIBARSENIC TREATMENT TECHNOLOGIES
APPLICABLE TO WATER
9 - 1
Oxidation/ Reduction
(Pretreatment Process)
Groundwater
Solids to Disposal
Sludge Dewatering
Filtrate
Sludge Sludge Thickening
Thickener Overflow
FlocculationpH Adjustment and Reagent Addition
PolymerReagent
Effluent
Clarification
Oxidation/ Reduction
(Pretreatment Process)
Groundwater
Solids to Disposal
Sludge Dewatering
Filtrate
Sludge Sludge Thickening
Thickener Overflow
FlocculationpH Adjustment and Reagent Addition
PolymerReagent
Effluent
Clarification
Model of a Precipitation/Coprecipitation System
Summary
Precipitation/coprecipitation has been the mostfrequently used method to treat arsenic-contaminated water, including groundwater, surfacewater, leachate, mine drainage, drinking water, andwastewater in numerous pilot- and full-scaleapplications. Based on the information collected toprepare this report, this technology typically canreduce arsenic concentrations to less than 0.050mg/L and in some cases has reduced arsenicconcentrations to below 0.010 mg/L.
Technology Description: Precipitation useschemicals to transform dissolved contaminants intoan insoluble solid. In coprecipitation, the targetcontaminant may be dissolved or in a colloidal orsuspended form. Dissolved contaminants do notprecipitate, but are adsorbed onto another speciesthat is precipitated. Colloidal or suspendedcontaminants become enmeshed with otherprecipitated species, or are removed throughprocesses such as coagulation and flocculation.Many processes to remove arsenic from waterinvolve a combination of precipitation andcoprecipitation. The precipitated/coprecipitatedsolid is then removed from the liquid phase byclarification or filtration. Arsenic precipitation/coprecipitation can use combinations of thechemicals and methods listed below.
Media Treated:• Drinking water• Groundwater• Wastewater
• Surface water• Leachate• Mine drainage
Chemicals and Methods Used for ArsenicPrecipitation/Coprecipitation:• Ferric salts, (e.g.,
ferric chloride), ferricsulfate, ferrichydroxide
• Ammonium sulfate• Alum (aluminum
hydroxide)
• pH adjustment• Lime softening,
limestone, calciumhydroxide
• Manganese sulfate• Copper sulfate• Sulfide
9.0 PRECIPITATION/COPRECIPITATIONFOR ARSENIC
Technology Description and Principles
For this report, technologies were consideredprecipitation/coprecipitation if they involved the following steps:
• Mixing of treatment chemicals into the water• Formation of a solid matrix through precipitation,
coprecipitation, or a combination of theseprocesses, and
• Separation of the solid matrix from the water
Technologies that remove arsenic by passing it througha fixed bed of media, where the arsenic may beremoved through adsorption, precipitation/coprecipitation, or a combination of these processes, arediscussed in the adsorption treatment section (Section11.0).
Precipitation/coprecipitation usually involves pHadjustment and addition of a chemical precipitant or
coagulant; it can also include addition of a chemicaloxidant (Ref. 9.1). Oxidation of arsenic to its lesssoluble As(V) state can increase the effectiveness of
9 - 2
Precipitation/Coprecipitation Chemistry
The chemistry of precipitation/coprecipitation isoften complex, and depends upon a variety offactors, including the speciation of arsenic, thechemical precipitants used and their concentrations,the pH of the water, and the presence of otherchemicals in the water to be treated. As a result, theparticular mechanism that results in the removal ofarsenic through precipitation/coprecipitationtreatment is process-specific, and in some cases isnot completely understood. For example, theremoval mechanism in the treatment of As(V) withFe(III) has been debated in the technical literature(Ref. 9.33).
It is beyond the scope of this report to provide allpossible chemical reactions and mechanisms forprecipitation/coprecipitation processes that are usedto remove arsenic. More detailed information on thechemistry involved in specific processes can befound in the references listed at the end of thissection.
45
24
0 10 20 30 40 50
Pilot
Full
precipitation/coprecipitation processes, and can be doneas a separate pretreatment step or as part of theprecipitation process. Some pretreatment processes thatoxidize As(III) to As(V) include ozonation, photooxidation, or the addition of oxidizing chemicals suchas potassium permanganate, sodium hypochlorite, orhydrogen peroxide (Ref. 9.8, 9.16, 9.22, 9.25, 9.29). Clarification or filtration are commonly used to removethe solid precipitate.
Media and Contaminants Treated
Precipitation/coprecipitation is frequently used to treatwater contaminated with metals (Ref. 9.1). Thereferences identified for this report containedinformation on its application to industrial wastewater,groundwater, surface water, leachate, and minedrainage.
Type, Number, and Scale of Identified ProjectsTreating Water Containing Arsenic
Precipitation/coprecipitation processes for arsenic indrinking water, groundwater, and industrial wastewaterare commercially available. The data gathered insupport of this report include information on its full-scale application at 16 sites. Information on full-scaletreatment of drinking water is available for eightfacilities and of industrial wastewater for 21 facilities. Information on 24 pilot-scale applications was alsoidentified. Figure 9.1 shows the number of pilot- andfull-scale precipitation/coprecipitation projects in thesources researched.
Figure 9.1Scale of Identified Precipitation/Coprecipitation
Projects for Arsenic Treatment
Summary of Performance Data
Table 9.1 presents the available performance data forpilot- and full-scale precipitation/coprecipitation
treatment. It contains information on 69 applications,including 20 groundwater, surface water, and minedrainage, 15 drinking water, and 34 industrialwastewater projects. The information that appears inthe "Precipitating Agent or Process" column of Table9.1, including the chemicals used, the descriptions ofthe processes, and whether it involved precipitation orcoprecipitation, is based on the cited references. Thisinformation was not independently checked foraccuracy or technical feasability. For example, in somecases, the reference used may apply the term"precipitation" to a process that is actuallycoprecipitation.
The effectiveness of this technology can be evaluatedby comparing influent and effluent contaminantconcentrations. All of the 12 environmental mediaprojects for which both influent and effluent arsenicconcentration data were available had influentconcentrations greater than 0.050 mg/L. The treatmentsachieved effluent concentrations of less than 0.050mg/L in eight of the projects and less than 0.010 mg/Lin four of the projects. Information on the leachabilityof arsenic from the precipitates and sludges wasavailable for three projects. For all of these projects, theconcentration of leachable arsenic as measured by thetoxicity characteristic leaching procedure (TCLP) (theRCRA regulatory threshold for identifying a waste thatis hazardous because it exhibits the characteristic oftoxicity for arsenic) was below 5.0 mg/L.
9 - 3
Factors Affecting Precipitation/CoprecipitationPerformance
• Valence state of arsenic - The presence of themore soluble trivalent state of arsenic mayreduce the removal efficiency. The solubility ofarsenic depends upon its valence state, pH, thespecific arsenic compound, and the presence ofother chemicals with which arsenic might react(Ref. 9.12). Oxidation to As(V) could improvearsenic removal through precipitation/coprecipitation (Ref. 9.7).
• pH - In general, arsenic removal will bemaximized at the pH at which the precipitatedspecies is least soluble. The optimal pH rangefor precipitation/coprecipitation depends uponthe waste treated and the specific treatmentprocess (Ref. 9.7).
• Presence of other compounds - The presenceof other metals or contaminants may impact theeffectiveness of precipitation/coprecipitation. For example, sulfate could decrease arsenicremoval in processes using ferric chloride as acoagulant, while the presence of calcium or ironmay increase the removal of arsenic in theseprocesses (Ref. 9.7).
Case Study: Winthrop Landfill Site
The Winthrop Landfill Site, located in Winthrop,Maine, is a former dump site that acceptedmunicipal and industrial wastes (See Table 9.1,Project 1). Groundwater at the site wascontaminated with arsenic and chlorinated andnonchlorinated VOCs. A pump-and-treat system forthe groundwater has been in operation at the sitesince 1995. Organic compounds have beenremediated to below action levels, and the pump-and-treat system is currently being operated for theremoval of arsenic alone. The treatment trainconsists of equalization/pH adjustment to pH 3,chemical oxidation with hydrogen peroxide,precipitation/coprecipitation via pH adjustment toPH 7, flocculation/clarification, and sand bedfiltration. It treats 65 gallons per minute ofgroundwater containing average arsenicconcentrations of 0.3 mg/L to below 0.005 mg/L. Through May, 2001, 359 pounds of arsenic hadbeen removed from groundwater at the WinthropLandfill Site using this above ground treatmentsystem. Capital costs for the system were about $2million, and O&M costs are approximately$250,000 per year (Ref. 9.29, cost year notprovided).
Of the 12 drinking water projects having both influentand effluent arsenic concentration data, eight hadinfluent concentrations greater than 0.050 mg/L. Thetreatments achieved effluent concentrations of less than0.050 mg/L in all eight of these projects, and less than0.010 mg/L in two projects. Information on theleachability of arsenic from the precipitates and sludgeswas available for six projects. For these projects theleachable concentration of arsenic was below 5.0 mg/L.
All of the 28 wastewater projects having both influentand effluent arsenic concentration data had influentconcentrations greater than 0.050 mg/L. The treatmentsachieved effluent concentrations of less than 0.050mg/L in 16 of these projects, and less than 0.010 mg/Lin 11 projects. Information on the leachability ofarsenic from the precipitates and sludges was availablefor four projects. Only one of these projects had aleachable concentration of arsenic below 5.0 mg/L.
Projects that did not reduce effluent arsenicconcentrations to below 0.050 or 0.010 mg/L do notnecessarily indicate that precipitation/coprecipitationcannot achieve these levels. The treatment goal forsome applications could have been above theseconcentrations, and the technology may have beendesigned and operated to meet a higher concentration.
Information on treatment goals was not collected forthis report.
Some projects in Table 9.1 include treatment trains, themost common being precipitation/coprecipitation followed by activated carbon adsorption or membranefiltration. In those cases, the performance data listedare for the entire treatment train, not just theprecipitation/coprecipitation step.
The case study in this section discusses in greater detailthe removal of arsenic from groundwater using anaboveground treatment system at the Winthrop LandfillSuperfund site. This information is summarized inTable 9.1, Project 1.
Applicability, Advantages, and Potential Limitations
Precipitation/coprecipitation is an active ex situtreatment technology designed to function with routinechemical addition and sludge removal. It usuallygenerates a sludge residual, which typically requirestreatment such as dewatering and subsequent disposal. Some sludge from the precipitation/coprecipitation ofarsenic can be a hazardous waste and require additionaltreatment such as solidification/stabilization prior todisposal. In the presence of other metals or
9 - 4
Factors Affecting Precipitation/CoprecipitationCosts
• Type of chemical addition - The chemicaladded will affect costs. For example, calciumhypochlorite, is a less expensive oxidant thanpotassium permanganate (Ref. 9.16).
• Chemical dosage - The cost generallyincreases with increased chemical addition. Larger amounts of chemicals added usuallyresults in a larger amount of sludge requiringadditional treatment or disposal (Ref. 9.7,9.12).
• Treatment goal - Application could requireadditional treatment to meet stringent cleanupgoals and/or effluent and disposal standards(Ref. 9.7)
• Sludge disposal - Sludge produced from theprecipitation/coprecipitation process could beconsidered a hazardous waste and requireadditional treatment before disposal, or disposalas hazardous waste (Ref. 9.7).
• Factors affectingprecipitation/coprecipitation performance -Items in the “Factors AffectingPrecipitation/Coprecipitation Performance” boxwill also affect costs.
contaminants, arsenic precipitation/coprecipitationprocesses may also cause other compounds toprecipitate, which can render the resulting sludgehazardous (Ref. 9.7). The effluent may also requirefurther treatment, such as pH adjustment, prior todischarge or reuse.
More detailed information on selection and design ofarsenic treatment systems for small drinking watersystems is available in the document “ArsenicTreatment Technology Design Manual for SmallSystems “ (Ref. 9.36).
Summary of Cost Data
Limited cost data are currently available forprecipitation/coprecipitation treatment of arsenic. Atthe Winthrop Landfill Site (Project 1), groundwatercontaining arsenic, 1,1-dichloroethane, and vinylchloride is being pumped and treated above groundthrough a treatment train that includes precipitation. The total capital cost of this treatment system was $2million ($1.8 million for construction and $0.2 millionfor design). O&M costs were about $350,000 per yearfor the first few years and are now approximately$250,000 per year. The treatment system has a capacityof 65 gpm. However, these costs are for the entire
treatment train (Ref. 9.29, cost year not provided). Atthe power substation in Fort Walton, Florida, (Table9.1, Project 4), the reported O&M cost was $0.006 pergallon (for the entire treatment train, Ref 9.32, cost yearnot provided). Capital cost information was notprovided.
A low-cost, point-of-use precipitation/coprecipitationtreatment designed for use in developing nations witharsenic-contaminated drinking water was pilot-tested infour areas of Bangladesh (Project 31). This simpletreatment process consists of a two-bucket system thatuses potassium permanganate and alum to precipitatearsenic, followed by sedimentation and filtration. Theequipment cost of the project was approximately $6,and treatment of 40 liters of water daily would require amonthly chemical cost of $0.20 (Ref. 9.22, cost year notprovided).
The document "Technologies and Costs for Removal ofArsenic From Drinking Water" (Ref. 9.7) contains moreinformation on the cost of systems to treat arsenic indrinking water to below the revised MCL of 0.010mg/L. The document includes capital and O&M costcurves for three precipitation/coprecipitation processes:
• Enhanced coagulation/filtration• Enhanced lime softening• Coagulation assisted microfiltration
These cost curves are based on computer cost modelsfor drinking water treatment systems. Table 3.4 inSection 3 of this document contains cost estimatesbased on these curves for coagulation assistedmicrofiltration. The cost information available forenhanced coagulation/ filtration and enhanced limesoftening are for retrofitting existingprecipitation/coprecipitation systems at drinking water treatment plants to meet the revisedMCL. Therefore, the cost information could not beused to estimate the cost of a new precipitation/coprecipitation treatment system.
References
9.1 Federal Remediation Technologies ReferenceGuide and Screening Manual, Version 3.0. Federal Remediation Technologies Roundtablehttp://www.frtr.gov./matrix2/top_page.html
9.2 Twidwell, L.G., et al. Technologies andPotential Technologies for Removing Arsenicfrom Process and Mine Wastewater. Presentedat "REWAS '99." San Sebastian, Spain. September 1999.http://www.mtech.edu/metallurgy/arsenic/REWASAS%20for%20proceedings99%20in%20word.pdf
9 - 5
9.3 U.S. EPA. Final Best Demonstrated AvailableTechnology (BDAT) Background Document forK031, K084, K101, K102, Characteristic ArsenicWastes (D004), Characteristic Selenium Wastes(D010), and P and U Wastes Containing Arsenicand Selenium Listing Constituents. Office ofSolid Waste. May 1990.
9.4 U.S. EPA. Best Demonstrated AvailableTechnology (BDAT) Background Document forWood Preserving Wastes: F032, F034, andF035; Final. April, 1996. http://www.epa.gov/epaoswer/hazwaste/ldr/wood/bdat_bd.pdf
9.5 U.S. EPA. Pump and Treat of ContaminatedGroundwater at the Baird and McGuireSuperfund Site, Holbrook, Massachusetts.Federal Remediation Technologies Roundtable. September, 1998. http://www.frtr.gov/costperf.html.
9.6 U.S. EPA. Development Document for EffluentLimitations Guidelines and Standards for theCentralized Waste Treatment Industry. December, 2000.http://www.epa.gov/ost/guide/cwt/final/devtdoc.html
9.7 U.S. EPA. Technologies and Costs for Removalof Arsenic From Drinking Water. EPA-R-00-028. Office of Water. December, 2000.http://www.epa.gov/safewater/ars/treatments_and_costs.pdf
9.8 U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition).Office of Solid Waste and Emergency Response.EPA-542-R-01-004. February 2001.http://www.epa.gov/ncepi/Catalog/EPA542R01004.html
9.9 U.S. EPA National Risk Management ResearchLaboratory. Treatability Database.
9.10 U.S. EPA Technology Innovation Office. Database for EPA REACH IT (REmediationAnd CHaracterization Innovative Technologies).http://www.epareachit.org. March, 2001.
9.11 Electric Power Research Institute. InnovativeTechnologies for Remediation of Arsenic in SoilGroundwater: Soil Flushing, In-Situ Fixation,Iron Coprecipitation, and Ceramic MembraneFiltration. http://www.epri.com. 1996.
9.12 U.S. EPA Office of Research and Development. Contaminants and Remedial Options at SelectedMetal-Contaminated Sites. EPA/540/R-95/512. July, 1995. http://search.epa.gov/s97is.vts
9.13 U.S. EPA Office of Solid Waste and EmergencyResponse. 1997 Biennial Reporting SystemDatabase.
9.14 U.S. EPA. Groundwater Remedies Selected atSuperfund Sites. EPA 542-R-01-022. January,2002. http://clu-in.org
9.15 U.S. EPA. Groundwater Pump and TreatSystems: Summary of Selected Cost andPerformance Information at Superfund-financedSites. EPA-542-R-01-021b. EPA OSWER. December 2001. http://clu-in.org
9.16 MSE Technology Applications, Inc. ArsenicOxidation Demonstration Project - Final Report. January 1998. http://www.arsenic.org/PDF%20Files/Mwtp-84.pdf
9.17 Vendor information provided by MSETechnology Applications, Inc.
9.18 HYDRO-Solutions and Purification. June 28,2001. http://www.mosquitonet.com/~hydro
9.19 DPHE-Danida Arsenic Mitigation Pilot Project. June 28, 2001. http://phys4.harvard.edu/~wilson/2bucket.html.
9.20 Environmental Research Institute. ArsenicRemediation Technology - AsRT. June 28,2001. http://www.eng2.uconn.edu/~nikos/asrt-brochure.html
9.21 A Simple Household Device to Remove Arsenicfrom Groundwater Hence Making it Suitable forDrinking and Cooking. June 28, 2001http://phys4.harvard.edu/~wilson/asfilter1. html
9.22 Appropriate Remediation Techniques forArsenic-Contaminated Wells in Bangladesh.June 28, 2001. http://phys4.harvard.edu/~wilson/murcott.html
9.23 Redox Treatment of Groundwater to RemoveTrace Arsenic at Point-of-Entry Water TreatmentSystems. June 28, 2001http://phys4.harvard.edu/~wilson/Redox/Desc.html
9.24 U.S. EPA Office of Water. Arsenic in DrinkingWater. August 3, 2001. http://www.dainichi-consul.co.jp/english/arsenic/treat1.htm.
9.25 U.S. EPA Office of Research and Development. Arsenic Removal from Drinking Water byCoagulation/Filtration and Lime SofteningPlants. EPA/600/R-00/063. June, 2000.http://www.epa.gov/ncepi/Catalog/EPA600R00063.html
9.26 U.S. EPA and NSF International. ETV JointVerification Statement for ChemicalCoagulant/Filtration System Used in PackagedDrinking Water Treatment Systems. March,2001.
9.27 FAMU-FSU College of Engineering. ArsenicRemediation. August 21, 2001.http://www.eng.fsu.edu/departments/civil/research/arsenicremedia/index.htm
9.28 U.S. EPA. Contaminants and Remedial Optionsat Selected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512. July 1995.
9 - 6
9.29 E-mail attachment sent from Anni Loughlin ofU.S. EPA Region I to Linda Fiedler, U.S. EPA. August 21, 2001.
9.30 U.S. EPA. Arsenic & Mercury - Workshop onRemoval, Recovery, Treatment, and Disposal. Office of Research and Development. EPA-600-R-92-105. August 1992.
9.31 U.S. EPA. Profiles of Metal RecoveryTechnologies for Mineral Processing and OtherMetal-Bearing Hazardous Wastes. December1994.
9.32 Miller JP, Hartsfield TH, Corey AC, MarkeyRM. In Situ Environmental Remediation of anEnergized Substation. EPRI. Palo Alto, CA.Report No. 1005169. 2001.
9.33 Robins, Robert G. Some Chemical AspectsRelating To Arsenic Remedial Technologies. Proceedings of the U.S. EPA Workshop onManaging Arsenic Risks to the Environment. Denver, Colorado. May 1-3, 2001.
9.34 E-mail from Bhupi Khona, U.S. EPA Region 3 toSankalpa Nagaraja, Tetra Tech EM, Inc.,regarding Groundwater Pump-and-Treat ofArsenic at the Whitmoyer LaboratoriesSuperfund site. May 3, 2002.
9.35 Hydroglobe LLC. Removal of Arsenic fromBangladesh Well Water by the StevensTechnology for Arsenic Removal (S.T.A.R.). Hoboken, NJ. http://www.hydroglobe.net.
9.36 U.S. EPA. Arsenic Treatment TechnologyDesign Manual for Small Systems (100% Draftfor Peer Review). June 2002. http://www.epa.gov/ safewater/smallsys/arsenicdesignmanualpeerreviewdraft.pdf
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
9 - 7
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
Env
iron
men
tal M
edia
- Coa
gula
tion/
Filtr
atio
n1
Land
fill
Gro
undw
ater
Full
Win
thro
pLa
ndfil
lSu
perf
und
Site
,W
inth
rop,
ME
0.30
0 m
g/L
<0.0
05 m
g/L
--Tr
eatm
ent t
rain
cons
istin
g of
pH
adju
stm
ent,
oxid
atio
n,flo
ccul
atio
n/cl
arifi
catio
n, a
irst
rippi
ng, a
nd sa
nd-
bed
filtra
tion
9.29
2M
etal
ore
min
ing
and
smel
ting
Surf
ace
wat
er,
8,50
0,00
0ga
llons
Full
Tex-
Tin
Supe
rfun
d Si
te,
OU
1, T
X
----
--Pr
ecip
itatio
n by
pH
adju
stm
ent f
ollo
wed
by fi
ltrat
ion
9.8
Env
iron
men
tal M
edia
- Ir
on C
opre
cipi
tatio
n3
Her
bici
deap
plic
atio
n G
roun
dwat
erFu
ll--
0.00
5 - 3
.8 m
g/L
<0.0
05 -
0.05
mg/
L<5
mg/
L(T
CLP
)Ir
on c
opre
cipi
tatio
nfo
llow
ed b
y m
embr
ane
filtra
tion
9.27
4Po
wer
subs
tatio
nG
roun
dwat
er,
44 m
illio
nga
llons
Full
Ft. W
alto
nB
each
, FL
0.2-
1.0
mg/
L<0
.005
mg/
L--
Iron
cop
reci
pita
tion
follo
wed
by
cera
mic
mem
bran
e fil
tratio
n
9.32
5C
hem
ical
mix
ing
Gro
undw
ater
,43
,000
gpd
Full
Bai
rd a
ndM
cGui
reSu
perf
und
Site
,H
olbr
ook,
MA
----
--Tr
eatm
ent t
rain
cons
istin
g of
air
strip
ping
,pr
ecip
itatio
n (f
erric
chlo
ride,
lim
e sl
urry
,ph
osph
oric
and
sulfu
ric a
cids
, and
amm
oniu
m su
lfate
),fil
tratio
n, a
nd c
arbo
nad
sorp
tion.
9.5,
9.15
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 8
6W
ood
pres
ervi
ngw
aste
sG
roun
dwat
erFu
llSi
lver
Bow
Cre
ek/B
utte
Are
a Su
perf
und
Site
- R
ocke
rTi
mbe
r Fra
min
gA
nd T
reat
men
tPl
ant O
U, M
T
----
--In
situ
trea
tmen
t of
cont
amin
ated
grou
ndw
ater
by
inje
ctin
g a
solu
tion
of fe
rrou
s iro
n,lim
esto
ne, a
ndpo
tass
ium
perm
anga
nate
9.8
7M
etal
ore
min
ing
and
smel
ting
activ
ities
Col
lect
ion
pond
wat
erPi
lot
Rya
n Lo
deM
ine,
AK
4.6
mg/
L0.
027
mg/
L--
Enha
nced
iron
co-
prec
ipita
tion
follo
wed
by
filtra
tion
9.18
8H
erbi
cide
appl
icat
ion
Gro
undw
ater
Pilo
t--
1 m
g/L
(TW
A)
<0.0
05 m
g/L
(TW
A)
--Ir
on c
opre
cipi
tatio
nfo
llow
ed b
y ce
ram
icm
embr
ane
filtra
tion
9.11
9M
etal
ore
min
ing
Aci
d m
ine
wat
er
Pilo
tSu
sie
Min
e/V
alle
yFo
rge
site
,R
imin
i, M
T
12.2
- 16
.5 m
g/L
0.01
7 - 0
.053
mg/
L8,
830-
13,3
00m
g/kg
0.00
51-0
.007
6m
g/L
(TC
LP)
Phot
o-ox
idat
ion
ofar
seni
c fo
llow
ed b
yiro
n co
prec
ipita
tion
9.1
6
10M
etal
spr
oces
sing
Leac
hate
from
nick
el ro
aste
rflu
e du
stdi
spos
al a
rea
Pilo
tSu
sie
Min
e/V
alle
yFo
rge
site
,R
imin
i, M
T
423
- 439
mg/
L <
0.32
mg/
L10
2,00
0 m
g/kg
0.54
7-0.
658
mg/
L (T
CLP
)
Phot
o-ox
idat
ion
ofar
seni
c fo
llow
ed b
yiro
n co
prec
ipita
tion
9.16
Env
iron
men
tal M
edia
- O
ther
or
Uns
peci
fied
Prec
ipita
tion
Proc
ess
11--
"Sup
erfu
ndw
aste
wat
er"
Full
--0.
1 - 1
mg/
L0.
022
mg/
L--
Che
mic
alpr
ecip
itatio
n9.
9
12--
Gro
undw
ater
Full
--10
0 m
g/L
< 0.
2 m
g/L
--Pr
ecip
itatio
n9.
1713
--"S
uper
fund
was
tew
ater
"Fu
ll--
0.1
- 1 m
g/L
0.11
0 m
g/L
--C
hem
ical
prec
ipita
tion
9.9
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 9
14--
Gro
undw
ater
Full
-- 1
00 m
g/L
<0.0
10 m
g/L
--R
educ
tive
Prec
ipita
tion
(add
ition
alin
form
atio
n no
tav
aila
ble)
9.17
15C
hem
ical
man
ufac
turin
gw
aste
s,gr
ound
wat
er
Gro
undw
ater
Full
Pete
rson
/Pur
itan
Inc.
Sup
erfu
ndSi
te -
OU
1,
PAC
Are
a, R
I
----
--In
-situ
trea
tmen
t of
arse
nic-
cont
amin
ated
grou
ndw
ater
by
inje
ctin
g ox
ygen
ated
wat
er
9.8
16C
hem
ical
man
ufac
turin
gG
roun
dwat
er,
65,0
00 g
pdFu
llG
reen
woo
dC
hem
ical
Supe
rfun
d Si
te,
Gre
enw
ood,
VA
----
--Tr
eatm
ent t
rain
cons
istin
g of
met
als
prec
ipita
tion,
filtra
tion,
UV
oxid
atio
n an
d ca
rbon
adso
rptio
n
9.15
17W
aste
dis
posa
lG
roun
dwat
er,
43,0
00 g
pdFu
llH
iggi
ns F
arm
Supe
rfun
d Si
te,
Fran
klin
Tow
nshi
p, N
J
----
--Tr
eatm
ent t
rain
cons
istin
g of
air
strip
ping
, met
als
prec
ipita
tion,
filtra
tion,
and
ion
exch
ange
9.15
18W
ood
pres
ervi
ngG
roun
dwat
er,
3,00
0 gp
dFu
llSa
unde
rs S
uppl
yC
ompa
nySu
perf
und
Site
,C
huck
atuc
k, V
A
----
--Tr
eatm
ent t
rain
cons
istin
g of
met
als
prec
ipita
tion,
filtra
tion,
and
car
bon
adso
rptio
n.
9.15
19H
erbi
cide
man
ufac
turin
gR
CR
A w
aste
code
K03
1,1
mgd
Full
Vin
elan
dC
hem
ical
Com
pany
Supe
rfun
d Si
te,
Vin
elan
d, N
J
----
--M
etal
s pre
cipi
tatio
nfo
llow
ed b
y fil
tratio
n9.
15
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
0
20V
eter
inar
y fe
edad
ditiv
es a
ndph
arm
aceu
tical
sm
anuf
actu
ring
Gro
undw
ater
,50
-100
gpm
Full
Whi
tmoy
erLa
bora
torie
sSu
perf
und
Site
100
mg/
L0.
025
mg/
L--
Neu
traliz
atio
n an
dflo
ccul
atio
n by
incr
easi
ng p
H to
9
9.34
Dri
nkin
g W
ater
- Ir
on C
opre
cipi
tatio
n21
--D
rinki
ng w
ater
,1.
6 m
gdFu
ll--
0.02
03 m
g/L
(TW
A)
0.00
30 m
g/L
(TW
A)
<5 m
g/L
(WET
)Fe
rric
copr
ecip
itatio
nfo
llow
ed b
y ze
olite
softe
ning
9.7
22--
Drin
king
wat
er,
1.4
mgd
Full
--0.
0485
mg/
L(T
WA
)0.
0113
mg/
L(T
WA
)<5
mg/
L (W
ET)
Ferr
icco
prec
ipita
tion
9.7
23--
Drin
king
wat
erFu
llM
cGra
th R
oad
Bap
tist C
hurc
h,A
K
0.37
0 m
g/L
<0.0
05 m
g/L
--En
hanc
ed ir
on c
o -
prec
ipita
tion
follo
wed
by
filtra
tion
9.18
24--
Drin
king
wat
er,
600
mgd
Full
--0.
0026
- 0.
0121
mg/
L0.
0008
- 0.
006
mg/
L80
6-88
0 m
g/kg
<0.0
5-0.
106
mg/
L (T
CLP
)
Ozo
natio
n fo
llow
edby
coa
gula
tion
with
iron-
and
alu
min
um-
base
d ad
ditiv
es a
ndfil
tratio
n
9.25
25--
Drin
king
wat
er,
62.5
mgd
Full
--0.
015
- 0.0
239
mg/
L0.
0015
- 0.
0118
mg/
L29
3-49
3 m
g/kg
0.05
8-0.
114
mg/
L (T
CLP
)
Coa
gula
tion
with
iron
and
alum
inum
base
d ad
ditiv
es,
sedi
men
tatio
n, a
ndfil
tratio
n
9.25
26--
Drin
king
wat
erFu
ll--
Plan
t A: 0
.02
mg/
LPl
ant B
: 0.0
49m
g/L
Plan
t A: 0
.003
mg/
LPl
ant B
: 0.0
12m
g/L
--A
dsor
ptio
n an
dco
prec
ipita
tion
with
iron
hydr
oxid
epr
ecip
itate
s
9.10
27--
Drin
king
wat
er
Pilo
t--
--<0
.002
mg/
L A
rsen
ic (V
)--
Iron
coa
gula
tion
with
dire
ct fi
ltrat
ion
9.24
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
1
28–
Drin
king
wat
er,
5.3
gallo
nsPi
lot
Bha
riab
&Sr
eena
gar
Than
a,B
angl
ades
h
0.28
- 0.
59 m
g/L
<0.0
3 - 0
.05
mg/
L11
94 m
g/kg
Iron
co
-pr
ecip
itatio
nfo
llow
ed b
y fil
tratio
n
9.35
Dri
nkin
g W
ater
- L
ime
Soft
enin
g29
--D
rinki
ng w
ater
Full
5 fa
cilit
ies,
iden
tific
atio
nun
know
n
--<0
.003
mg/
L(T
WA
)<5
mg/
L(T
CLP
)Li
me
softe
ning
at
pH >
10.2
9.7
30--
Drin
king
wat
er,
10 m
gdFu
ll--
0.01
59 -
0.08
49m
g/L
0.00
63 -
0.03
31m
g/L
17.0
-35.
3 m
g/kg
<0.0
5 m
g/L
(TC
LP)
Oxi
datio
n fo
llow
edby
lim
e so
fteni
ngan
d fil
tratio
n
9.25
Dri
nkin
g W
ater
- Po
int-
of-U
se S
yste
ms
31--
Drin
king
wat
er
Pilo
tH
aria
n V
illag
eR
ajsh
aji D
istri
ctB
angl
ades
h
0.09
2 - 0
.120
mg/
L0.
023
- 0.0
36m
g/L
--N
atur
ally
-occ
urrin
giro
n at
9 m
g/L
faci
litat
espr
ecip
itatio
n,fo
llow
ed b
yse
dim
enta
tion,
filtra
tion
and
acid
ifica
tion
9.22
32--
Drin
king
wat
er
Pilo
tW
est B
enga
l,In
dia
0.30
0 m
g/L
0.03
0 m
g/L
--Pr
ecip
itatio
n w
ithso
dium
hyp
ochl
orite
and
alum
, fol
low
edby
mix
ing,
flocc
ulat
ion,
sedi
men
tatio
n, a
ndup
-flo
w fi
ltrat
ion
9.22
33--
Drin
king
wat
er,
40 li
ters
per
day
Pilo
tN
oakh
ali,
Ban
glad
esh
0.12
- 0.
46 m
g/L
<0.0
5 m
g/L
--C
oagu
latio
n w
ithpo
tass
ium
perm
anga
nate
and
alum
, fol
low
ed b
yse
dim
enta
tion
and
filtra
tion
9.19
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
2
34--
Drin
king
wat
er,
1.0
-1.1
gpm
Pilo
tSp
iro T
unne
lW
ater
Filt
ratio
nPl
ant,
Park
City
,U
T
0.06
09 -
0.14
6m
g/L
0.00
12 -
0.03
45m
g/L
--Pr
ecip
itatio
n w
ithfe
rric
chl
orid
e an
dso
dium
hyp
ochl
orite
,fo
llow
ed b
y fil
tratio
n
9.26
35--
Drin
king
wat
er,
20 li
ters
per
day
Pilo
tW
est B
enga
l,In
dia
----
--Pr
ecip
itatio
n by
ferr
ic sa
lt, o
xidi
zing
agen
t, an
d ac
tivat
edch
arco
al, f
ollo
wed
by se
dim
enta
tion
and
filtra
tion
9.21
Was
tew
ater
s - L
ime
Soft
enin
g36
Vet
erin
ary
phar
mac
eutic
als
K08
4,w
aste
wat
erFu
llC
harle
s City
,Io
wa
399
- 1,6
70 m
g/L
(TW
A)
Cal
cium
ars
enat
e,60
.5 -
500
mg/
L(T
WA
)
45,2
00 m
g/kg
(TW
A) 2
,200
mg/
L (T
CLP
)
Cal
cium
hyd
roxi
de9.
3
37--
Was
tew
ater
Full
--4.
2 m
g/L
(TW
A)
0.51
mg/
L (T
WA
)--
Lim
e pr
ecip
itatio
nfo
llow
ed b
yse
dim
enta
tion
9.4
38--
Was
tew
ater
Fu
ll--
4.2
mg/
L (T
WA
)0.
34 m
g/L
(TW
A)
--Li
me
prec
ipita
tion
follo
wed
by
sedi
men
tatio
n an
dfil
tratio
n
9.4
39--
Was
tew
ater
Fu
llB
P M
iner
als
Am
eric
a--
--C
alci
umar
sena
te a
ndca
lciu
m a
rsen
ite,
1,90
0 - 6
,900
mg/
kg (T
WA
)0.
2 - 7
4.5
mg/
L(E
P To
x)
Lim
e9.
3
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
3
Was
tew
ater
s - M
etal
Sul
fate
s40
Vet
erin
ary
phar
mac
eutic
als
K08
4,w
aste
wat
erFu
llC
harle
s City
,Io
wa
125
- 302
mg/
L(T
WA
)M
anga
nese
arse
nate
, 6.0
2 -
22.4
mg/
L (T
WA
)
47,4
00 m
g/kg
(TW
A) 9
84m
g/L
(TC
LP)
Man
gane
se su
lfate
9.3
41M
etal
spr
oces
sing
Spen
t lea
chat
efr
om th
ere
cove
ry o
f Cu,
Ag,
and
Sb
from
ore
s(a
mou
nt n
otav
aila
ble)
Full
Equi
ty S
ilver
Min
e, H
oust
on,
Brit
ish
Col
umbi
a,C
anad
a
----
95 to
98%
reco
very
of
arse
nic
Aci
d ad
ditio
n,
chem
ical
prec
ipita
tion
with
copp
er su
lfate
, and
filtra
tion
9.30
42M
etal
spr
oces
sing
Leac
hate
from
filte
r cak
e fr
ompu
rific
atio
n of
zinc
sulfa
teel
ectro
win
ning
solu
tion
(am
ount
not
avai
labl
e)
Full
Texa
sgul
fC
anad
a,Ti
mm
ons,
Ont
ario
, Can
ada
----
98%
reco
very
of
arse
nic
Aci
d ad
ditio
n,
chem
ical
prec
ipita
tion
with
copp
er su
lfate
, and
filtra
tion
9.30
Was
tew
ater
s - Ir
on C
opre
cipi
tatio
n43
--W
aste
wat
erfr
om w
etsc
rubb
ing
ofin
cine
rato
r ven
tga
s (D
004,
P011
)
Full
Am
eric
anN
uKem
69.6
- 83
.7 m
g/L
(TW
A)
<0.0
2 - 0
.6 m
g/L
(TW
A)
--C
hem
ical
oxi
datio
nfo
llow
ed b
ypr
ecip
itatio
n w
ithfe
rric
salts
9.3
44V
eter
inar
yph
arm
aceu
tical
sK
084,
was
tew
ater
Full
Cha
rles C
ity,
Iow
a15
- 10
7 m
g/L
(TW
A)
Ferr
ic a
rsen
ate,
0.
163
- 0.5
80m
g/L
(TW
A)
9,76
0 m
g/kg
(TW
A)
0.50
8 m
g/L
(TC
LP)
Ferr
ic su
lfate
9.3
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
4
Was
tew
ater
s - O
ther
or
Uns
peci
fied
Prec
ipita
tion
Proc
ess
45--
Was
tew
ater
Fu
ll--
<0.1
- 3.
0 m
g/L
(TW
A)
0.18
mg/
L
(ave
rage
, TW
A)
--C
hem
ical
redu
ctio
nfo
llow
ed b
ypr
ecip
itatio
n,se
dim
enta
tion,
and
filtra
tion
9.4
46C
entra
lized
was
tetre
atm
ent
indu
stry
Was
tew
ater
Full
--57
mg/
L (T
WA
)0.
181
mg/
L(T
WA
)--
Prim
ary
prec
ipita
tion
with
solid
s-liq
uid
sepa
ratio
n
9.6
47C
entra
lized
was
tetre
atm
ent
indu
stry
Was
tew
ater
Full
--57
mg/
L (T
WA
)0.
246
mg/
L(T
WA
)--
Prim
ary
prec
ipita
tion
with
solid
s-liq
uid
sepa
ratio
n fo
llow
edby
seco
ndar
ypr
ecip
itatio
n w
ithso
lids-
liqui
dse
para
tion
9.6
48C
entra
lized
was
tetre
atm
ent
indu
stry
Was
tew
ater
Full
--57
mg/
L (T
WA
)0.
084
mg/
L(T
WA
)--
Prim
ary
prec
ipita
tion
with
solid
s-liq
uid
sepa
ratio
n fo
llow
edby
seco
ndar
ypr
ecip
itatio
n w
ithso
lids-
liqui
dse
para
tion
and
mul
timed
ia fi
ltrat
ion
9.6
49C
entra
lized
was
tetre
atm
ent
indu
stry
Was
tew
ater
Full
--57
mg/
L (T
WA
)0.
011
mg/
L(T
WA
)--
Sele
ctiv
e m
etal
spr
ecip
itatio
n, so
lids-
liqui
d se
para
tion,
seco
ndar
ypr
ecip
itatio
n, s
olid
s-liq
uid
sepa
ratio
n,te
rtiar
y pr
ecip
itatio
n,an
d so
lid-li
quid
sepa
ratio
n
9.6
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
5
50C
hem
ical
and
allie
d pr
oduc
tsW
aste
wat
erFu
ll--
0b. -
0.1
mg/
L(T
WA
)0.
0063
mg/
L(T
WA
)--
Che
mic
ally
ass
iste
dcl
arifi
catio
n 9.
9
51--
Dom
estic
was
tew
ater
Full
--0b.
- 0.
1 m
g/L
(TW
A)
0.00
15 m
g/L
(TW
A)
--C
hem
ical
prec
ipita
tion
9.9
52Tr
ansp
orta
tion
equi
pmen
tin
dust
ry
Was
tew
ater
Full
--0.
1 - 1
mg/
L(T
WA
)<0
.002
mg/
L(T
WA
)--
Che
mic
alpr
ecip
itatio
n an
dfil
tratio
n
9.9
53C
hem
ical
s and
allie
d pr
oduc
tsW
aste
wat
erFu
ll--
0.1
- 1 m
g/L
(TW
A)
0.02
8 m
g/L
(TW
A)
--C
hem
ical
ly a
ssis
ted
clar
ifica
tion
9.9
54W
R M
etal
sIn
dust
ries
(WR
MI)
ars
enic
leac
hing
pro
cess
Met
als
proc
essi
ng
Leac
hate
from
arse
nica
l flu
e-du
sts f
rom
non
-fe
rrou
ssm
elte
rs(a
mou
nt n
otav
aila
ble)
Full
WR
Met
als
Indu
strie
s(lo
catio
n no
tav
aila
ble)
110,
000
- 550
,000
mg/
kg (T
WA
)--
--C
hem
ical
prec
ipita
tion
and
filtra
tion
9.31
55M
etal
spr
oces
sing
Spen
t lea
chat
efr
om th
ere
cove
ry o
f Ag
from
ore
s(a
mou
nt n
otav
aila
ble)
Full
Sher
itt G
ordo
nM
ines
, LTD
.,Fo
rtSa
skat
chew
an,
Alb
erta
, Can
ada
----
--C
hem
ical
prec
ipita
tion
and
filtra
tion
9.30
56M
etal
lurg
ie-
Hob
oken
-O
verp
elt (
MH
O)
solv
ent e
xtra
ctio
npr
oces
sM
etal
spr
oces
sing
Spen
tel
ectro
lyte
from
Cu
refin
ing
(am
ount
not
avai
labl
e)
Full
Ole
n, B
elgi
um--
--99
.96%
reco
very
of
arse
nic
Che
mic
alpr
ecip
itatio
n an
dfil
tratio
n
9.31
57El
ectri
c, g
as, a
ndsa
nita
ryW
aste
wat
erPi
lot
--0b.
- 0.
1 m
g/L
(TW
A)
0.00
28 m
g/L
(TW
A)
--C
hem
ical
ly a
ssis
ted
clar
ifica
tion
9.9
58Pr
imar
y m
etal
sW
aste
wat
erPi
lot
--0b.
- 0.
1 m
g/L
(TW
A)
<0.0
015
mg/
L(T
WA
)--
Che
mic
alpr
ecip
itatio
n9.
9
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
6
59--
Was
tew
ater
bear
ing
unsp
ecifi
edR
CR
A li
sted
was
te c
ode
Pilo
t--
0b. -
0.1
mg/
L(T
WA
)0.
001
mg/
L(T
WA
)--
Che
mic
alpr
ecip
itatio
n,ac
tivat
ed c
arbo
nad
sorp
tion,
and
filtra
tion
9.9
60--
Dom
estic
was
tew
ater
Pilo
t--
0b. -
0.1
mg/
L(T
WA
)0.
001
mg/
L(T
WA
)--
Che
mic
alpr
ecip
itatio
n9.
9
61--
Was
tew
ater
bear
ing
unsp
ecifi
edR
CR
A li
sted
was
te c
ode
Pilo
t--
0.1
- 1 m
g/L
(TW
A)
0.01
2 m
g/L
(TW
A)
--C
hem
ical
prec
ipita
tion,
activ
ated
car
bon
adso
rptio
n, a
ndfil
tratio
n
9.9
62--
Was
tew
ater
bear
ing
unsp
ecifi
edR
CR
A li
sted
was
te c
ode
Pilo
t--
0.1
- 1 m
g/L
(TW
A)
0.01
2 m
g/L
(TW
A)
--C
hem
ical
prec
ipita
tion,
activ
ated
car
bon
adso
rptio
n, a
ndfil
tratio
n
9.9
63--
Was
tew
ater
bear
ing
unsp
ecifi
edR
CR
A li
sted
was
te c
ode
Pilo
t--
0.1
- 1 m
g/L
(TW
A)
0.00
6 m
g/L
(TW
A)
--C
hem
ical
prec
ipita
tion,
activ
ated
car
bon
adso
rptio
n, a
ndfil
tratio
n
9.9
64La
ndfil
lH
azar
dous
leac
hate
, F03
9Pi
lot
--0.
1 - 1
mg/
L(T
WA
)0.
008
mg/
L(T
WA
)--
Che
mic
alpr
ecip
itatio
n,ac
tivat
ed c
arbo
nad
sorp
tion,
and
filtra
tion
9.9
65--
Was
tew
ater
bear
ing
unsp
ecifi
edR
CR
A li
sted
was
te c
ode
Pilo
t--
0.1
- 1 m
g/L
(TW
A)
0.01
4 m
g/L
(TW
A)
--C
hem
ical
prec
ipita
tion,
activ
ated
car
bon
adso
rptio
n, a
ndfil
tratio
n
9.9
Tab
le 9
.1A
rsen
ic P
reci
pita
tion/
Cop
reci
pita
tion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Prec
ipita
ting
Age
ntor
Pro
cess
c.So
urce
9 - 1
7
66M
unic
ipal
land
fill
Leac
hate
Pilo
t--
1 - 1
0 m
g/L
(TW
A)
8 m
g/L
(TW
A)
--C
hem
ical
prec
ipita
tion,
activ
ated
car
bon
adso
rptio
n, a
ndfil
tratio
n
9.9
67M
etal
spr
oces
sing
Scru
bber
wat
erfr
om le
adsm
elte
r
Pilo
t--
3,30
0 m
g/L
0.00
7 m
g/L
--M
iner
al-li
kepr
ecip
itatio
n(a
dditi
onal
info
rmat
ion
not
avai
labl
e)
9.17
68M
etal
spr
oces
sing
Thic
kene
rov
erflo
w fr
omle
ad sm
elte
r
Pilo
t--
5.8
mg/
L0.
003
mg/
L--
Min
eral
-like
prec
ipita
tion
(add
ition
alin
form
atio
n no
tav
aila
ble)
9.17
69--
Indu
stria
lw
aste
wat
erPi
lot
--5.
8 m
g/kg
< 0.
5 m
g/kg
----
9.17
aEx
clud
ing
benc
h-sc
ale
treat
men
ts.
bD
etec
tion
limit
not p
rovi
ded.
cTh
e in
form
atio
n th
at a
ppea
rs in
the
"Pre
cipi
tatin
g A
gent
or P
roce
ss"
colu
mn,
incl
udin
g th
e ch
emic
als u
sed,
the
desc
riptio
ns o
f the
pre
cipi
tatio
n/co
prec
ipita
tion
proc
esse
s, an
d w
heth
er th
e pr
oces
s inv
olve
d pr
ecip
itatio
n or
cop
reci
pita
tion,
wer
e pr
epar
ed b
ased
on
the
info
rmat
ion
repo
rted
in th
e ci
ted
refe
renc
es.
This
info
rmat
ion
was
not
inde
pend
ently
che
cked
for a
ccur
acy
or te
chni
cal f
easa
bilit
y. I
n so
me
case
s the
term
"pr
ecip
itatio
n" m
ay b
e ap
plie
d to
apr
oces
s tha
t is a
ctua
lly c
opre
cipi
tatio
n.
EPT
= Ex
tract
ion
proc
edur
e to
xici
ty te
stm
g/L
= m
illig
ram
s per
lite
rR
CR
A =
Res
ourc
e C
onse
rvat
ion
and
Rec
over
y A
ctW
ET =
Was
te e
xtra
ctio
n te
st
mg/
kg =
mill
igra
ms p
er k
ilogr
am--
= N
ot a
vaila
ble
TWA
= T
otal
was
te a
naly
sis
gpd
= ga
llons
per
day
mgd
= m
illio
n ga
llons
per
day
TCLP
= T
oxic
ity c
hara
cter
istic
leac
hing
proc
edur
e
10-1
Summary
Membrane filtration can remove a wide range ofcontaminants from water. Based on the informationcollected to prepare this report, this technologytypically can reduce arsenic concentrations to lessthan 0.050 mg/L and in some cases has reducedarsenic concentrations to below 0.010 mg/L. However, its effectiveness is sensitive to a variety ofuntreated water contaminants and characteristics. Italso produces a larger volume of residuals and tendsto be more expensive than other arsenic treatmenttechnologies. Therefore, it is used less frequentlythan precipitation/coprecipitation, adsorption, and ion exchange. It is most commonly used to treatgroundwater and drinking water, or as a polishingstep for precipitation processes. Only two full-scaleprojects using membrane filtration to treat arsenicwere identified in the sources researched for thisreport.
Technology Description: Membrane filtrationseparates contaminants from water by passing itthrough a semi-permeable barrier or membrane. The membrane allows some constituents to passthrough, while blocking others (Ref. 10.2, 10.3).
Media Treated:
• Drinking water• Groundwater• Surface water• Industrial wastewater
Types of Membrane Processes:
• Microfiltration• Ultrafiltration• Nanofiltration • Reverse osmosis
Contaminated Water
Membranes
RejectRecycle
Effluent
Contaminated Water
Membranes
RejectRecycle
Effluent
Model of a Membrane Filtration System
10.0 MEMBRANE FILTRATION FORARSENIC
Technology Description and PrinciplesThere are four types of membrane processes:microfiltration (MF), ultrafiltration (UF), nanofiltration(NF), and reverse osmosis (RO). All four of theseprocesses are pressure-driven and are categorized by thesize of the particles that can pass through themembranes or by the molecular weight cut off (i.e.,pore size) of the membrane (Ref. 10.2). The force
required to drive fluid across the membrane depends onthe pore size; NF and RO require a relatively highpressure (50 to 150 pounds per square inch [psi]), whileMF and UF require lower pressure (5 to 100 psi ) (Ref.10.4). The low pressure processes primarily removecontaminants through physical sieving, and the highpressure processes through chemical diffusion acrossthe permeable membrane (Ref. 10.4).
Because arsenic species dissolved in water tend to haverelatively low molecular weights, only NF and ROmembrane processes are likely to effectively treatdissolved arsenic (Ref. 10.4). MF has been used withprecipitation/coprecipitation to remove solidscontaining arsenic. The sources used for this report didnot contain any information on the use of UF to removearsenic; therefore, UF is not discussed in thistechnology summary. MF generates two treatmentresiduals from the influent waste stream: a treatedeffluent (permeate) and a rejected waste stream ofconcentrated contaminants (reject).
RO is a high pressure process that primarily removessmaller ions typically associated with total dissolvedsolids. The molecular weight cut off for ROmembranes ranges from 1 to 20,000, which is asignificantly lower cut off than for NF membranes. Themolecular weight cut off for NF membranes rangesfrom approximately 150 to 20,000. NF is a high-pressure process that primarily removes larger divalentions associated with hardness (for example, calcium[Ca], and magnesium [Mg] but not monovalent salts(for example, sodium [Na] and chlorine [Cl]). NF isslightly less efficient than RO in removing dissolvedarsenic from water (Ref. 10.4).
10-2
6
25
2
0 5 10 15 20 25
Bench
Pilot
Full
6
25
2
0 5 10 15 20 25
Bench
Pilot
Full
Factors Affecting Membrane FiltrationPerformance
• Suspended solids, high molecular weight,dissolved solids, organic compounds, andcolloids - The presence of these constituents inthe feed stream may cause membrane fouling.
• Oxidation state of arsenic - Prior oxidation ofthe influent stream to convert As(III) to As(V)will increase arsenic removal; As(V) isgenerally larger and is captured by themembrane more effectively than As(III).
• pH - pH may affect the adsorption of arsenic onthe membrane by creating an electrostaticcharge on the membrane surface.
• Temperature - Low influent streamtemperatures decreases membrane flux. Increasing system pressure or increasing themembrane surface area may compensate for lowinfluent stream temperature.
MF is a low-pressure process that primarily removesparticles with a molecular weight above 50,000 or aparticle size greater than 0.050 micrometers. The poresize of MF membranes is too large to effectivelyremove dissolved arsenic species, but MF can removeparticulates containing arsenic and solids produced byprecipitation/coprecipitation (Ref. 10.4).
Media and Contaminants Treated
Drinking water, surface water, groundwater, and industrial wastewater can be treated with this technology. Membrane filtration can treat dissolved salts and other dissolved materials (Ref. 10.12).
Type, Number, and Scale of Identified ProjectsTreating Water Containing Arsenic
The data gathered for this report identified one full-scale RO and one full-scale MF treatment of arsenic ingroundwater and surface water (Figure 10.1). The MFapplication is a treatment train consisting ofprecipitation/coprecipitation followed by MF to removesolids. In addition, 16 pilot-scale and three bench-scaleapplications of RO and eight pilot-scale and threebench-scale applications of NF have been identified. One pilot-scale application of MF to remove solidsfrom precipitation/coprecipitation of arsenic has alsobeen identified.
Figure 10.1Scale of Identified Membrane Filtration Projects for
Arsenic Treatment
Summary of Performance Data
Table 10.1 presents the performance data found for thistechnology. Performance results for membranefiltration are typically reported as percent removal, (i.e.,the percentage of arsenic, by mass, in the influent that isremoved or rejected from the influent wastewaterstream). A higher percentage indicates greater removalof arsenic, and therefore, more effective treatment.
Although many of the projects listed in Table 10.1 mayhave reduced arsenic concentrations to below 0.05mg/L or 0.01 mg/L, data on the concentration of arsenicin the effluent and reject streams were not available formost projects.
For two RO projects, the arsenic concentration in thereject stream was available, allowing the concentrationin permeate to be calculated. For both projects, theconcentration of arsenic prior to treatment was greaterthan 0.050 mg/L, and was reduced to less than 0.010mg/L in the treated water.
For two projects involving removal of solids fromprecipitation/coprecipitation treatment of arsenic withMF, the arsenic concentration in the permeate wasavailable. The concentration prior to precipitation/coprecipitation treatment was greater than 0.050 mg/Lfor one project, and ranged from 0.005 to 3.8 mg/L forthe other. For both projects, the concentration in thetreated water was less than 0.005 mg/L.
The case study at the end of this section furtherdiscusses the use of membrane filtration to removearsenic from groundwater used as a drinking watersource. Information for this site is summarized in Table10.1, Project 31.
10-3
Case Study: Park City Spiro Tunnel WaterFiltration Plant
The Park City Spiro Tunnel Water Filtration Plant inPark City, Utah treats groundwater from water-bearing fissures that collect in a tunnel of anabandoned silver mine to generate drinking water. A pilot-scale RO unit treated contaminated water ata flow rate of 0.77 gallons per minute (gpm) fromthe Spiro tunnel for 34 days. The total anddissolved arsenic in the feedwater averaged 0.065and 0.042 mg/L, respectively. The total anddissolved arsenic concentrations in the permeateaveraged <0.0005 and <0.0008 mg/L, respectively. The RO process reduced As (V) from 0.035 to0.0005 mg/L and As (III) from 0.007 to 0.0005mg/L. The membrane achieved 99% total Asremoval and 98% As (V) removal (Ref. 10.12) (seeProject 31, Table 10.1).
Factors Affecting Membrane Filtration Costs
• Type of membrane filtration - The type ofmembrane selected may affect the cost of thetreatment (Ref. 10.1, 10.2).
• Initial waste stream - Certain waste streamsmay require pretreatment, which wouldincrease costs (Ref. 10.4).
• Rejected waste stream - Based onconcentrations of the removed contaminant,further treatment may be required prior to disposal or discharge (Ref. 10.4).
• Factors affecting membrane filtrationperformance - Items in the “Factors AffectingMembrane Filtration Performance” box willalso affect costs.
Applicability, Advantages, and Potential Limitations
Membrane technologies are capable of removing a widerange of dissolved contaminants and suspended solidsfrom water (Ref. 10.12). RO and NF technologiesrequire no chemical addition to ensure adequateseparation. This type of treatment may be run in eitherbatch or continuous mode. This technology’s effectiveness is sensitive to a variety of contaminantsand characteristics in the untreated water. Suspendedsolids, organics, colloids, and other contaminants cancause membrane fouling. Therefore, it is typicallyapplied to groundwater and drinking water, which areless likely to contain fouling contaminants. It is alsoapplied to remove solids from precipitation processesand as a polishing step for other water treatmenttechnologies when lower concentrations must beachieved.
More detailed information on selection and design ofarsenic treatment systems for small drinking watersystems is available in the document “ArsenicTreatment Technology Design Manual for SmallSystems “ (Ref. 10.15).
Summary of Cost Data
The research conducted in support of this report did notdocument any cost data for specific membrane filtrationprojects to treat of arsenic. The document"Technologies and Costs for Removal of Arsenic FromDrinking Water" (Ref. 10.4) contains additionalinformation on the cost of point-of-use reverse osmosissystems to treat arsenic in drinking water to levelsbelow the revised MCL of 0.010 mg/L. The document
includes capital and O&M cost curves for thistechnology. These cost curves are based on computercost models for drinking water treatment systems.
References
10.1 U.S. EPA Office of Research and Development. Arsenic & Mercury - Workshop on Removal,Recovery, Treatment, and Disposal. EPA-600-R-92-105. August 1992.
10.2 U.S. EPA Office of Research and Development. Regulations on the Disposal of ArsenicResiduals from Drinking Water TreatmentPlants. Office of Research and Development. EPA-600-R-00-025. May 2000.http://www.epa.gov/ORD/WebPubs/residuals/index.htm
10.3 U.S. EPA Office of Solid Waste. BDATBackground Document for Spent Potliners fromPrimary Aluminum Reduction - K088. EPA530-R-96-015. February 1996.http://www.epa.gov/ncepi/Catalog/EPA530R96015.html
10.4 U.S. EPA Office of Water. Technologies andCost for Removal of Arsenic from DrinkingWater. EPA 815-R-00-028. December 2000.http://www.epa.gov/safewater/ars/treatments_and_costs.pdf
10.5 U.S. EPA National Risk Management ResearchLaboratory. Treatability Database. March 2001.
10-4
10.6 U.S. Technology Innovation Office. Databasefor EPA REACH IT (REmediation AndCHaracterization Innovative Technologies). http://www.epareachit.org. March 2001.
10.7 U.S. EPA Office of Research and Development. Contaminants and Remedial Options at SelectedMetal-Contaminated Sites. EPA/540/R-95/512. July, 1995. http://search.epa.gov/s97is.vts
10.8 Federal Remediation Technologies ReferenceGuide and Screening Manual, Version 4.0. Federal Remediation Technologies Roundtable. September 5, 2001.http://www.frtr.gov/matrix2/top_page.html.
10.9 U.S. EPA Office of Water. Arsenic in DrinkingWater Rule Economic Analysis. EPA 815-R-00-026. December 2000.http://www.epa.gov/safewater/ars/econ_analysis.pdf
10.10 Code of Federal Regulations, Part 40, Section268. Land Disposal Restrictions.http://lula.law.cornell.edu/cfr/cfr.php?title=40&type=part&value=268
10.11 Code of Federal Regulations, Part 400. EffluentLimitations Guidelines.http://www.epa.gov/docs/epacfr40/chapt-I.info/subch-N.htm
10.12 Environmental Technology Verification Program(ETV). Reverse Osmosis Membrane FiltrationUsed In Packaged Drinking Water TreatmentSystems. http://www.membranes.com. March2001.
10.13 Electric Power Research Institute. InnovativeTechnologies for Remediation of Arsenic in SoilGroundwater: Soil Flushing, In-Situ Fixation,Iron Coprecipitation, and Ceramic MembraneFiltration. http://www.epri.com. April 2000.
10.14 FAMU-FSU College of Engineering. ArsenicRemediation.http://www.eng.fsu.edu/departments/civil/research/arsenicremedia/index.htm August 21,2001.
10.15 U.S. EPA. Arsenic Treatment TechnologyDesign Manual for Small Systems (100% Draftfor Peer Review). June 2002. http://www.epa.gov/ safewater/smallsys/arsenicdesignmanualpeerreviewdraft.pdf
Tab
le 1
0.1
Mem
bran
e Fi
ltrat
ion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
10-5
Proj
ect
Num
ber
Med
ia o
r W
aste
Scal
eSi
te N
ame
orL
ocat
ion
Initi
al A
rsen
icC
once
ntra
tion
Perc
ent A
rsen
ic R
emov
ala o
rFi
nal A
rsen
ic C
once
ntra
tion
Mem
bran
e or
Tre
atm
ent P
roce
ssSo
urce
Nan
ofilt
ratio
n1
Gro
undw
ater
Pilo
tTa
rryt
own,
NY
0.03
8 - 0
.154
mg/
L95
%--
10.4
2G
roun
dwat
erPi
lot
Tarr
ytow
n, N
Y0.
038
- 0.1
54 m
g/L
95%
--10
.43
Gro
undw
ater
with
low
DO
C (1
mg/
L)
Pilo
t--
--60
%Si
ngle
ele
men
t,ne
gativ
ely
char
ged
mem
bran
e
10.4
4G
roun
dwat
er w
ith h
igh
DO
C (1
1mg/
L)
Pilo
t--
--80
%Si
ngle
ele
men
t,ne
gativ
ely
char
ged
mem
bran
e
10.4
5G
roun
dwat
er w
ith h
igh
DO
C (1
1mg/
L)
Pilo
t--
--75
% in
itial
, 3-
16%
fina
lSi
ngle
ele
men
t,ne
gativ
ely
char
ged
mem
bran
e
10.4
6A
rsen
ic sp
iked
surf
ace
wat
erPi
lot
----
Ars
enic
(III
) 20%
Ars
enic
(V) >
95%
Sing
le e
lem
ent
mem
bran
e10
.4
7A
rsen
ic sp
iked
surf
ace
wat
erPi
lot
----
Ars
enic
(III
) 30%
Ars
enic
(V) >
95%
Sing
le e
lem
ent
mem
bran
e10
.4
8A
rsen
ic sp
iked
surf
ace
wat
erPi
lot
----
Ars
enic
(III
) 52%
Ars
enic
(V) >
95%
Sing
le e
lem
ent
mem
bran
e10
.4
9A
rsen
ic sp
iked
DI w
ater
Ben
ch--
--A
rsen
ic (I
II) 1
2%A
rsen
ic (V
) 85%
Sing
le e
lem
ent,
nega
tivel
y ch
arge
dm
embr
ane
10.4
10A
rsen
ic sp
iked
lake
wat
erB
ench
----
Ars
enic
(V) 8
9%Si
ngle
ele
men
t,ne
gativ
ely
char
ged
mem
bran
e
10.4
11A
rsen
ic sp
iked
DI w
ater
Ben
ch--
--A
rsen
ic (V
) 90%
Flat
shee
t, ne
gativ
ely
char
ged
mem
bran
e10
.4
Tab
le 1
0.1
Mem
bran
e Fi
ltrat
ion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Med
ia o
r W
aste
Scal
eSi
te N
ame
orL
ocat
ion
Initi
al A
rsen
icC
once
ntra
tion
Perc
ent A
rsen
ic R
emov
ala o
rFi
nal A
rsen
ic C
once
ntra
tion
Mem
bran
e or
Tre
atm
ent P
roce
ssSo
urce
10-6
Rev
erse
Osm
osis
12Su
rfac
e w
ater
cont
amin
ated
with
woo
dpr
eser
ving
was
tes
Full
--24
.4 m
g/L
Ars
enic
rem
oval
, 99%
reje
ct st
ream
, 57.
7 m
g/L
treat
ed e
fflu
ent s
tream
, 0.0
394
mg/
L
Trea
tmen
t tra
inco
nsis
ting
of R
Ofo
llow
ed b
y io
nex
chan
ge.
Perf
orm
ance
data
are
for R
O tr
eatm
ent
only
.
10.1
13G
roun
dwat
erPi
lot
Cha
rlotte
Har
bor,
FL--
Ars
enic
(III
) 46-
84%
Ars
enic
(V) 9
6-99
%--
10.4
14G
roun
dwat
erPi
lot
Cin
cinn
ati,
OH
--A
rsen
ic (I
II) 7
3%--
10.4
15G
roun
dwat
erPi
lot
Euge
ne, O
R--
50%
--10
.416
Gro
undw
ater
Pilo
tFa
irban
ks, A
L--
50%
--10
.417
Gro
undw
ater
Pilo
tH
udso
n, N
H--
40%
--10
.418
Gro
undw
ater
with
low
DO
CPi
lot
----
> 80
%Si
ngle
ele
men
t,ne
gativ
ely
char
ged
mem
bran
e
10.4
19G
roun
dwat
er w
ith h
igh
DO
CPi
lot
----
> 90
%Si
ngle
ele
men
t,ne
gativ
ely
char
ged
mem
bran
e
10.4
20A
rsen
ic sp
iked
surf
ace
wat
erPi
lot
----
Ars
enic
(III
) 60%
Ars
enic
(V) >
95%
Sing
le e
lem
ent
mem
bran
e10
.4
21A
rsen
ic sp
iked
surf
ace
wat
erPi
lot
----
Ars
enic
(III
) 68%
Ars
enic
(V) >
95%
Sing
le e
lem
ent
mem
bran
e10
.4
22A
rsen
ic sp
iked
surf
ace
wat
erPi
lot
----
Ars
enic
(III
) 75%
Ars
enic
(V) >
95%
Sing
le e
lem
ent
mem
bran
e10
.4
23A
rsen
ic sp
iked
surf
ace
wat
erPi
lot
----
Ars
enic
(III
) 85%
Ars
enic
(V) >
95%
Sing
le e
lem
ent
mem
bran
e10
.4
24G
roun
dwat
erPi
lot
San
Ysi
dro,
NM
--91
%--
10.4
25G
roun
dwat
erPi
lot
San
Ysi
dro,
NM
--99
%H
ollo
w fi
ber,
poly
amid
em
embr
ane
10.4
26G
roun
dwat
erPi
lot
San
Ysi
dro,
NM
--93
-99%
Hol
low
fibe
r, ce
llulo
seac
etat
e m
embr
ane
10.4
Tab
le 1
0.1
Mem
bran
e Fi
ltrat
ion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Med
ia o
r W
aste
Scal
eSi
te N
ame
orL
ocat
ion
Initi
al A
rsen
icC
once
ntra
tion
Perc
ent A
rsen
ic R
emov
ala o
rFi
nal A
rsen
ic C
once
ntra
tion
Mem
bran
e or
Tre
atm
ent P
roce
ssSo
urce
10-7
27G
roun
dwat
erPi
lot
Tarr
ytow
n, N
Y--
86%
--10
.428
Ars
enic
spik
ed la
kew
ater
Ben
ch--
--A
rsen
ic (I
II) 5
%A
rsen
ic (V
) 96%
--10
.4
29A
rsen
ic sp
iked
DI w
ater
Ben
ch--
--A
rsen
ic (I
II) 5
%A
rsen
ic (V
) 96%
--10
.4
30A
rsen
ic sp
iked
DI w
ater
Ben
ch--
--A
rsen
ic (V
) 88%
--10
.431
Drin
king
wat
erPi
lot
Park
City
Spi
roTu
nnel
Wat
erFi
ltrat
ion
Plan
t, Pa
rkC
ity, U
tah
0.06
5 m
g/L
0.00
05 m
g/L
--10
.12
Mic
rofil
trat
ion
32G
roun
dwat
erFu
ll--
0.00
5 - 3
.8 m
g/L
<0.0
05 -
0.05
mg/
LIr
on c
opre
cipi
tatio
nfo
llow
ed b
y m
embr
ane
filtra
tion
10.1
4
33G
roun
dwat
erPi
lot
--0.
2 - 1
.0 m
g/L
<0.0
05 m
g/L
Iron
cop
reci
pita
tion
follo
wed
by
cera
mic
mem
bran
e fil
tratio
n
10.1
3
aPe
rcen
t ars
enic
reje
ctio
n is
1 m
inus
the
mas
s of a
rsen
ic in
the
treat
ed w
ater
div
ided
by
the
mas
s of a
rsen
ic in
the
influ
ent t
imes
100
[(
1-(m
ass o
f ars
enic
influ
ent/m
ass o
f ars
enic
eff
luen
t))*1
00].
DI =
Dei
oniz
edD
OC
= D
isso
lved
org
anic
car
bon
-- =
Not
ava
ilabl
eN
F =
Nan
ofilt
ratio
nR
O =
Rev
erse
Osm
osis
11 - 1
Contaminated Water
Sorbent
Effluent
Contaminated Water
Sorbent
Effluent
Model of an Adsorption System
Summary
Adsorption has been used to treat groundwater anddrinking water containing arsenic. Based on theinformation collected for this report, this technologytypically can reduce arsenic concentrations to lessthan 0.050 mg/L and in some cases has reducedarsenic concentrations to below 0.010 mg/L. Itseffectiveness is sensitive to a variety of untreatedwater contaminants and characteristics. It is usedless frequently than precipitation/coprecipitation,and is most commonly used to treat groundwater anddrinking water, or as a polishing step for other watertreatment processes.
Technology Description: In adsorption, solutes(contaminants) concentrate at the surface of asorbent, thereby reducing their concentration in thebulk liquid phase. The adsorption media is usuallypacked into a column. As contaminated water ispassed through the column, contaminants areadsorbed. When adsorption sites become filled, thecolumn must be regenerated or disposed of andreplaced with new media.
Media Treated:• Groundwater• Drinking water
Types of Sorbent Used in Adsorption to TreatArsenic:• Activated alumina (AA)• Activated carbon (AC)• Copper-zinc granules• Granular ferric hydroxide, ferric hydroxide-
coated newspaper pulp, iron oxide coated sand,iron filings mixed with sand
• Greensand filtration (KMnO4 coated glauconite)• Proprietary media• Surfactant-modified zeolite
11.0 ADSORPTION TREATMENT FOR ARSENIC
Technology Description and Principles
This section discusses arsenic removal processes thatuse a fixed bed of media through which water is passed. Some of the processes described in this section rely on acombination of adsorption, precipitation/coprecipitation, ion exchange, and filtration. However,the primary removal mechanism in each process isadsorption. For example, greensand is made fromglauconite, a green, iron-rich, clay-like mineral thatusually occurs as small pellets mixed with other sandparticles. The glauconite-containing sand is treatedwith potassium permanganate (KMnO4), forming alayer of manganese oxides on the sand. As waterpasses through a greensand filtration bed, the KMnO4oxidizes As(III) to As(V), and As(V) adsorbs onto thegreensand surface. In addition, arsenic is removed byion exchange, displacing species from the manganeseoxide (presumably hydroxide ion [OH-] and water[H2O]). When the KMnO4 is exhausted, the greensandmedia must be regenerated or replaced. Greensandmedia is regenerated with a solution of excess KMnO4. Greensand filtration is also known asoxidation/filtration (Ref. 11.3).
Activated alumina (AA) is the sorbent most commonlyused to remove arsenic from drinking water (Ref. 11.1),and has also been used for groundwater (Ref. 11.4). The reported adsorption capacity of AA ranges from0.003 to 0.112 grams of arsenic per gram of AA (Ref.11.4). It is available in different mesh sizes and itsparticle size affects contaminant removal efficiency.
Up to 23,400 bed volumes of wastewater can be treatedbefore AA requires regeneration or disposal and
replacement with new media (Ref. 11.3). Regenerationis a four-step process:
• Backwashing • Regeneration• Neutralization• Rinsing
11 - 2
8
15
0 5 10 15
Pilot
Full
The regeneration process desorbs the arsenic. Theregeneration fluid most commonly used for AAtreatment systems is a solution of sodium hydroxide. The most commonly used neutralization fluid is asolution of sulfuric acid. The regeneration andneutralization steps for AA adsorption systems mightproduce a sludge because the alumina can be dissolvedby the strong acids and bases used in these processes,forming an aluminum hydroxide precipitate in the spentregeneration and neutralization fluids. This sludgetypically contains a high concentration of arsenic (Ref.11.1).
Activated carbon (AC) is an organic sorbent that iscommonly used to remove organic and metalcontaminants from drinking water, groundwater, andwastewater (Ref. 11.4). AC media are normallyregenerated using thermal techniques to desorb andvolatilize contaminants (Ref. 11.6). However,regeneration of AC media used for the removal ofarsenic from water might not be feasible (Ref. 11.4). The arsenic might not volatilize at the temperaturestypically used in AC regeneration. In addition, off-gascontaining arsenic from the regeneration process maybe difficult or expensive to manage.
The reported adsorption capacity of AC is 0.020 gramsof As(V) per gram of AC. As(III) is not effectivelyremoved by AC. AC impregnated with metals such ascopper and ferrous iron has a higher reported adsorptioncapacity for arsenic. The reported adsorption capacityfor As(III) is 0.048 grams per gram of copper-impregnated carbon and for As(V) is 0.2 grams pergram of ferrous iron-impregnated carbon (Ref. 11.4).
Iron-based adsorption media include granular ferrichydroxide, ferric hydroxide-coated newspaper pulp,ferric oxide, iron oxide-coated sand, sulfur-modifiediron, and iron filings mixed with sand. These mediahave been used primarily to remove arsenic fromdrinking water. Processes that use these mediatypically remove arsenic using adsorption incombination with oxidation, precipitation/coprecipitation, ion exchange, or filtration. Forexample, iron oxide-coated sand uses adsorption andion exchange with surface hydroxides to selectivelyremove arsenic from water. The media requiresperiodic regeneration or disposal and replacement withnew media. The regeneration process is similar to thatused for AA, and consists of rinsing the media with aregenerating solution containing excess sodiumhydroxide, flushing with water, and neutralizing with astrong acid, such as sulfuric acid (Ref. 11.3).
The sources used for this report contained informationon the use of surfactant-modified zeolite (SMZ) atbench scale, but no pilot- or full-scale applications were
identified. SMZ is prepared by treating zeolite with asolution of surfactant, such ashexadecyltrimethylammonium bromide (HDTMA-Br). This process forms a stable coating on the zeolitesurface. The reported adsorption capacity of SMZ is0.0055 grams of As(V) per gram of SMZ at 250C. SMZmust be periodically regenerated with surfactantsolution or disposed and replaced with new SMZ (Ref.11.17).
Media and Contaminants Treated
Adsorption is frequently used to remove organiccontaminants and metals from industrial wastewater. Ithas been used to remove arsenic from groundwater anddrinking water.
Type, Number, and Scale of Identified ProjectsTreating Water Containing Arsenic
Adsorption technologies to treat arsenic-contaminatedwater in water are commercially available. Informationwas found on 23 applications of adsorption (Figure11.1), including 7 full- and 5 pilot-scale projects frogroundwater and surface water and 8 full- and 3 pilot-scale projects for drinking water.
Figure 11.1Scale of Identified Adsorption Projects for Arsenic
Treatment
Summary of Performance Data
Adsorption treatment effectiveness can be evaluated bycomparing influent and effluent contaminantconcentrations. Table 11.1 presents the availableperformance data for this technology. Two of the fourgroundwater and surface water projects having bothinfluent and effluent arsenic concentration data hadinfluent concentrations greater than 0.050 mg/L. Effluent concentrations of 0.050 mg/L or less were
11 - 3
Factors Affecting Adsorption Performance
• Fouling - The presence of suspended solids,organics, solids, silica, or mica, can causefouling of adsorption media (Ref. 11.1, 11.4).
• Arsenic oxidation state - Adsorption is moreeffective in removing As(V) than As(III) (Ref.11.12).
• Flow rate - Increasing the rate of flow throughthe adsorption unit can decrease the adsorptionof contaminants (Ref. 11.1).
• Wastewater pH - The optimal pH to maximizeadsorption of arsenic by activated alumina isacidic (pH 6). Therefore, pretreatment andpost-treatment of the water could be required(Ref. 11.4).
achieved in both of the projects. In the other twogroundwater and surface water projects the influentarsenic concentration was between 0.010 mg/L and0.050 mg/L, and the effluent concentration was lessthan 0.010 mg/L.
Of the ten drinking water projects (eight full and twopilot scale) having both influent and effluent arsenicconcentration data, eight had influent concentrationsgreater than 0.050 mg/L. Effluent concentrations of less than 0.050 mg/L were achieved in seven of theseprojects. For two drinking water projects the influentarsenic concentration was between 0.010 mg/L and0.050 mg/L, and the effluent concentration was lessthan 0.010 mg/L.
Projects that did not reduce arsenic concentrations tobelow 0.050 or 0.010 mg/L do not necessarily indicatethat adsorption cannot achieve these levels. Thetreatment goal for some applications may have beenabove these levels and the technology may have beendesigned and operated to meet a higher arsenicconcentration. Information on treatment goals was notcollected for this report.
Two pilot-scale studies were performed to compare theeffectiveness AA adsorption on As(III) and As(V)(Projects 3 and 4 in Table 11.1). For As(III), 300 bedvolumes were treated before arsenic concentrations inthe effluent exceeded 0.050 mg/L, whereas 23,400 bedvolumes were treated for As(V) before reaching thesame concentration in the effluent. The results of thesestudies indicate that the adsorption capacity of AA ismuch greater for As(V).
The case study at the end of this section discusses ingreater detail the use of AA to remove arsenic from
drinking water. Information for this project issummarized in Table 11.1, Project 13.
Applicability, Advantages, and Potential Limitations
For AA adsorption media, the spent regeneratingsolution might contain a high concentration of arsenicand other sorbed contaminants, and can be corrosive(Ref. 11.3). Spent AA is produced when the AA can nolonger be regenerated (Ref. 11.3). The spent AA mayrequire treatment prior to disposal (Ref. 11.4). Becauseregeneration of AA requires the use of strong acids andbases, some of the AA media becomes dissolved duringthe regeneration process. This can reduce theadsorptive capacity of the AA and cause the AApacking to become "cemented."
Regeneration of AC media involves the use of thermalenergy, which could release volatile arseniccompounds. Use of air pollution control equipmentmay be necessary to remove arsenic from the off-gasproduced (Ref. 11.6).
Competition for adsorption sites could reduce theeffectiveness of adsorption because other constituentsmay be preferentially adsorbed, resulting in a need formore frequent bed regeneration or replacement. Thepresence of sulfate, chloride, and organic compoundshas reportedly reduced the adsorption capacity of AAfor arsenic (Ref. 11.3). The order for adsorptionpreference for AA is provided below, with theconstituents with the greatest adsorption preferenceappearing at the top left (Ref. 11.3):
OH- > H2AsO4- > Si(OH)3O- > F- > HSeO3
- > SO42-
> H3AsO3
This technology’s effectiveness is also sensitive to avariety of contaminants and characteristics in theuntreated water, and suspended solids, organics, silica,or mica can cause fouling. Therefore, it is typicallyapplied to groundwater and drinking water, which areless likely to contain fouling contaminants. It may alsobe used as a polishing step for other water treatmenttechnologies.
More detailed information on selection and design ofarsenic treatment systems for small drinking watersystems is available in the document “ArsenicTreatment Technology Design Manual for SmallSystems “ (Ref. 11.20).
Summary of Cost Data
One source reported that the cost of removing arsenicfrom drinking water using AA ranged from $0.003 to
11 - 4
Factors Affecting Adsorption Costs
• Contaminant concentration - Very highconcentrations of competing contaminants mayrequire frequent replacement or regeneration ofadsorbent (Ref. 11.2). The capacity of theadsorption media increases with increasingcontaminant concentration (Ref. 11.1, 11.4). High arsenic concentrations can exhaust theadsorption media quickly, resulting in the needfor frequent regeneration or replacement.
• Spent media - Spent media that can no longerbe regenerated might require treatment ordisposal (Ref. 11.4).
• Factors affecting adsorption performance -Items in the “Factors Affecting AdsorptionPerformance” box will also affect costs.
Case Study: Treatment of Drinking Water by anActivated Alumina Plant
A drinking water treatment plant using AA (seeTable 11.1, Project 13) installed in February 1996has an average flow rate of 3,000 gallons per day. The arsenic treatment system consists of twoparallel treatment trains, with two AA columns inseries in each train. For each of the trains, the AAmedia in one column is exhausted and replacedevery 1 to 1.5 years after treating approximately5,260 bed volumes.
Water samples for a long-term evaluation werecollected weekly for a year. Pretreatment arsenicconcentrations at the inlet ranged from 0.053 to0.087 mg/L with an average of 0.063 mg/L. Theuntreated water contained primarily As(V) with onlyminor concentrations of As(III) and particulatearsenic. During the entire study, the arsenicconcentration in the treated drinking water wasbelow 0.003 mg/L. Spent AA from the system hadleachable arsenic concentrations of less than 0.05mg/L, as measured by the TCLP, and therefore,could be disposed of as nonhazardous waste.
$0.76 per 1,000 gallons (Ref. 11.4, cost year notprovided). The document "Technologies and Costs forRemoval of Arsenic From Drinking Water" (Ref. 11.3)contains detailed information on the cost of adsorptionsystems to treat arsenic in drinking water to below therevised MCL of 0.010 mg/L. The document includescapital and operating and maintenance (O&M) costcurves for four adsorption processes:
• AA (at various influent pH levels)• Granular ferric hydroxide• Greensand filtration (KMNO4 coated sand)• AA point-of-use systems
These cost curves are based on computer cost modelsfor drinking water systems. The curves show the costsfor adsorption treatment systems with different designflow rates. The document also contains information onthe disposal cost of residuals from adsorption. Many ofthe technologies used to treat drinking water areapplicable to treatment of other types of water, and mayhave similar costs. Table 3.4 in Section 3 of thisdocument contains cost estimates based on these curvesfor AA and greensand filtration.
References
11.1 U.S. EPA. Regulations on the Disposal ofArsenic Residuals from Drinking WaterTreatment Plants. Office of Research andDevelopment. EPA/600/R-00/025. May 2000.http://www.epa.gov/ORD/WebPubs/residuals/index.htm
11.2 Federal Remediation Technologies ReferenceGuide and Screening Manual, Version 3.0. Federal Remediation Technologies Roundtable. March 30, 2001. http://www.frtr.gov/matrix2/top_page.html.
11.3 U.S. EPA. Technologies and Costs for Removalof Arsenic From Drinking Water. EPA 815-R-00-028. Office of Water. December 2000.http://www.epa.gov/safewater/ars/treatments_and_costs.pdf
11.4 Twidwell, L.G., et al. Technologies andPotential Technologies for Removing Arsenicfrom Process and Mine Wastewater. Presentedat "REWAS'99." San Sebastian, Spain. September 1999.http://www.mtech.edu/metallurgy/arsenic/REWASAS%20for%20proceedings99%20in%20word.pdf
11.5 U.S. EPA. Pump and Treat of ContaminatedGroundwater at the Mid-South Wood ProductsSuperfund Site, Mena, Arkansas. FederalRemediation Technologies Roundtable. September 1998. http://www.frtr.gov/costperf.html.
11.6 U.S. EPA. Final Best Demonstrated AvailableTechnology (BDAT) Background Document forK031, K084, K101, K102, Characteristic ArsenicWastes (D004), Characteristic Selenium Wastes(D010), and P and U Wastes Containing Arsenicand Selenium Listing Constituents. Office ofSolid Waste. May 1990.
11 - 5
11.7 U.S. EPA. Groundwater Pump and TreatSystems: Summary of Selected Cost andPerformance Information at Superfund-financedSites. EPA-542-R-01-021b. EPA OSWER. December 2001. http://clu-in.org
11.8 Murcott S. Appropriate RemediationTechnologies for Arsenic-Contaminated Wells inBangladesh. Massachusetts Institute ofTechnology. February 1999.http://web.mit.edu/civenv/html/people/faculty/murcott.html
11.9 Haq N. Low-cost method developed to treatarsenic water. West Bengal and BangladeshArsenic Crisis Information Center. June 2001.http://bicn.com/acic/resources/infobank/nfb/2001-06-11-nv4n593.htm
11.10 U.S. EPA. Arsenic Removal from DrinkingWater by Iron Removal Plants. EPA 600-R-00-086. Office of Research and Development.August 2000. http://www.epa.gov/ORD/WebPubs/iron/index.html
11.11 Harbauer GmbH & Co. KG. Germany. Onlineaddress: http://www.harbauer-berlin.de/arsenic.
11.12 U.S. EPA. Arsenic Removal from DrinkingWater by Ion Exchange and Activated AluminaPlants. EPA 600-R-00-088. Office of Researchand Development. October 2000.http://www.epa.gov/ncepi/Catalog/EPA600R00088.html
11.13 Environmental Research Institute. ArsenicRemediation Technology - AsRT. June 28,2001. http://www.eng2.uconn.edu/~nikos/asrt-brochure.html.
11.14 Redox Treatment of Groundwater to RemoveTrace Arsenic at Point-of-Entry Water TreatmentSystems. June 28, 2001. http://phys4.harvard.edu/~wilson/Redox/Desc.html.
11.15 U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition). Office of Solid Waste and Emergency Response. EPA-542-R-01-004. February 2001. http://clu-in.org/asr
11.16 Electric Power Research Institute. InnovativeTechnologies for Remediation of Arsenic in SoilGroundwater: Soil Flushing, In-Situ Fixation,Iron Coprecipitation, and Ceramic MembraneFiltration. April 2000. http://www.epri.com
11.17 Sullivan, E. J., Bowman, R S., and Leieic, I.A. Sorption of Arsenate from Soil-WashingLeachate by Surfactant-Modified Zeolite. Prepublication draft. January, 2002. [email protected]
11.18 E-mail attachment from Cindy Schreier, PrimaEnvironmental to Sankalpa Nagaraja, Tetra TechEM Inc. June 18, 2002.
11.19 Severn Trent Services. UK. http://www.capitalcontrols.co.uk/
11.20 U.S. EPA. Arsenic Treatment TechnologyDesign Manual for Small Systems (100% Draftfor Peer Review). June 2002. http://www.epa.gov/ safewater/smallsys/arsenicdesignmanualpeerreviewdraft.pdf
Tab
le 1
1.1
Ads
orpt
ion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
11 -
6
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
C
once
ntra
tion
Fina
l Ars
enic
C
once
ntra
tion
Ads
orpt
ion
Proc
ess
Des
crip
tionb
Sour
ceE
nvir
onm
enta
l Med
ia -
Act
ivat
ed A
lum
ina
1--
Gro
undw
ater
Full
----
<0.0
5 m
g/L
Act
ivat
ed a
lum
ina.
Fl
ow ra
te: 3
00lit
ers/
hour
.
11.9
2--
Gro
undw
ater
Pilo
t--
--<0
.05
mg/
LA
ctiv
ated
alu
min
aad
sorp
tion
at p
H 5
11.4
3--
Solu
tion
cont
aini
ngtri
vale
nt a
rsen
ic
Pilo
t--
Triv
alen
tar
seni
c, 0
.1m
g/L
Triv
alen
t ars
enic
, 0.0
5m
g/L
Act
ivat
ed a
lum
ina
adso
rptio
n at
pH
6.0
of
solu
tion
cont
aini
ngtri
vale
nt a
rsen
ic.
300
bed
volu
mes
trea
ted
befo
re e
fflu
ent e
xcee
ded
0.05
mg/
L ar
seni
c.
11.3
4--
Solu
tion
cont
aini
ngpe
ntav
alen
tar
seni
c
Pilo
t--
Pent
aval
ent
arse
nic,
0.1
mg/
L
Pent
aval
ent a
rsen
ic,
0.05
mg/
LA
ctiv
ated
alu
min
aad
sorb
ent a
t pH
6.0
of
solu
tion
cont
aini
ngpe
ntav
alen
t ars
enic
. 23
,400
bed
vol
umes
treat
ed b
efor
e ef
fluen
tex
ceed
ed 0
.05
mg/
Lar
seni
c.
11.3
Tab
le 1
1.1
Ads
orpt
ion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
C
once
ntra
tion
Fina
l Ars
enic
C
once
ntra
tion
Ads
orpt
ion
Proc
ess
Des
crip
tionb
Sour
ce
11 -
7
Env
iron
men
tal M
edia
- A
ctiv
ated
Car
bon
5W
ood
pres
ervi
ngG
roun
dwat
erFu
llM
id-S
outh
Woo
dPr
oduc
t Sup
erfu
ndSi
te, M
ena,
AS
0.01
8 m
g/L
<0.0
05 m
g/L
(29
of 3
5m
onito
ring
wel
ls)
Trea
tmen
t tra
inco
nsis
ting
of o
il/w
ater
sepa
ratio
n, fi
ltrat
ion,
and
carb
on a
dsor
ptio
n.
Perf
orm
ance
dat
a ar
e fo
rth
e en
tire
treat
men
ttra
in.
11.5
6W
ood
Pres
ervi
ngG
roun
dwat
er,
27,0
00 g
pdFu
llN
orth
Cav
alca
deSt
reet
Sup
erfu
nd S
iteH
oust
on, T
X
----
Trea
tmen
t tra
inco
nsis
ting
of fi
ltrat
ion
follo
wed
by
carb
onad
sorp
tion
11.7
7W
ood
Pres
ervi
ngG
roun
dwat
er,
3,00
0 gp
dFu
llSa
unde
rs S
uppl
yC
ompa
ny S
uper
fund
Site
, Chu
ckat
uck,
VA
----
Trea
tmen
t tra
inco
nsis
ting
of m
etal
spr
ecip
itatio
n, fi
ltrat
ion,
and
carb
on a
dsor
ptio
n
11.7
8W
ood
Pres
ervi
ngG
roun
dwat
er,
4,00
0 gp
dFu
llM
cCor
mic
k an
dB
axte
r Cre
osot
ing
Co.
Sup
erfu
nd S
ite,
Portl
and,
OR
----
Trea
tmen
t tra
inco
nsis
ting
of fi
ltrat
ion,
ion
exch
ange
, and
carb
on a
dsor
ptio
n
11.7
9C
hem
ical
mix
ing
and
batc
hing
Gro
undw
ater
,43
,000
gpd
Full
Bai
rd a
nd M
cGui
reSu
perf
und
Site
, H
olbr
ook,
MA
----
Trea
tmen
t tra
inco
nsis
ting
of a
irst
rippi
ng, m
etal
spr
ecip
itatio
n, fi
ltrat
ion,
and
carb
on a
dsor
ptio
n
11.7
10C
hem
ical
Man
ufac
turin
gG
roun
dwat
er,
65,0
00 g
pdFu
llG
reen
woo
dC
hem
ical
Sup
erfu
ndSi
te,
Gre
enw
ood,
VA
----
Trea
tmen
t tra
inco
nsis
ting
of m
etal
spr
ecip
itatio
n, fi
ltrat
ion,
UV
oxi
datio
n an
dca
rbon
ads
orpt
ion
11.7
Tab
le 1
1.1
Ads
orpt
ion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
C
once
ntra
tion
Fina
l Ars
enic
C
once
ntra
tion
Ads
orpt
ion
Proc
ess
Des
crip
tionb
Sour
ce
11 -
8
Env
iron
men
tal M
edia
- Ir
on-B
ased
Med
ia11
Land
fill
Gro
undw
ater
Pilo
t--
--0.
027
mg/
LTr
eatm
ent t
rain
cons
istin
g of
prec
ipita
tion
from
bar
itead
ditio
n fo
llow
ed b
y an
iron
filin
gs a
nd sa
ndm
edia
filte
r. Pe
rfor
man
ce d
ata
are
for
the
entir
e tre
atm
ent
train
.
11.8
,11
.13
12--
Gro
undw
ater
,3,
600g
pdPi
lot
CA
0.01
8 m
g/L
<0.0
02 m
g/L
Fixe
d-be
d ad
sorb
er w
ithsu
lfur-
mod
ified
iron
adso
rben
t; 13
,300
bed
volu
mes
put
thro
ugh
unit
11.1
8
Dri
nkin
g W
ater
- A
ctiv
ated
Alu
min
a13
--D
rinki
ng w
ater
Full
--0.
063
mg/
L<0
.003
mg/
LTw
o ac
tivat
ed a
lum
ina
colu
mns
in se
ries,
med
iare
plac
ed in
one
col
umn
ever
y 1.
5 ye
ars
11.3
14--
Drin
king
wat
erFu
ll--
0.03
4 - 0
.087
mg/
L<0
.05
mg/
LA
ctiv
ated
alu
min
a11
.12
15--
Drin
king
wat
erFu
llPr
ojec
t Ear
thIn
dust
ries,
Inc.
0.34
mg/
L0.
01 -
0.02
5 m
g/L
Act
ivat
ed a
lum
ina
11.8
16--
Drin
king
wat
erFu
ll--
0.04
9 m
g/L
<0.0
03 m
g/L
Two
activ
ated
alu
min
aco
lum
ns in
serie
s, m
edia
repl
aced
in c
olum
n ta
nkev
ery
1.5
year
s
11.3
17--
Drin
king
wat
er,
14,0
00 g
pdFu
llB
ow, N
H0.
057
- 0.0
62m
g/L
0.05
0 m
g/L
Act
ivat
ed a
lum
ina
11.3
Dri
nkin
g W
ater
- Ir
on-B
ased
Med
ia18
--D
rinki
ng w
ater
Full
Har
baue
r Gm
bH &
Co.
, Ber
lin,
Ger
man
y
0.3
mg/
L<0
.01
mg/
LG
ranu
lar f
erric
hydr
oxid
e11
.11
Tab
le 1
1.1
Ads
orpt
ion
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
(con
tinue
d)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
alea
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
C
once
ntra
tion
Fina
l Ars
enic
C
once
ntra
tion
Ads
orpt
ion
Proc
ess
Des
crip
tionb
Sour
ce
11 -
9
19--
Drin
king
Wat
erPi
lot
--0.
1 - 0
.18
mg/
L<0
.01
mg/
LFi
xed
bed
adso
rber
with
ferr
ic h
ydro
xide
-coa
ted
new
spap
er p
ulp;
20,
000
bed
volu
mes
trea
ted
befo
re e
fflu
ent e
xcee
ded
0.01
mg/
L ar
seni
c
11.1
5
20--
Drin
king
wat
erPi
lot
--0.
180
mg/
L0.
010
mg/
LG
ranu
lar f
erric
hydr
oxid
e11
.16
21--
Drin
king
wat
erFu
ll--
0.02
mg/
L0.
003
mg/
LFi
xed
bed
adso
rber
with
ferr
ic o
xide
gra
nule
s11
.19
Dri
nkin
g W
ater
- O
ther
or
Unk
now
n M
edia
22--
Drin
king
wat
er
Full
--5
mg/
L0.
01 m
g/L
Cop
per-
zinc
gra
nule
s11
.14
23--
Drin
king
wat
erPi
lot
AD
I Int
erna
tiona
l--
--A
dsor
ptio
n in
pres
suriz
ed v
esse
lco
ntai
ning
pro
prie
tary
med
ia a
t pH
5.5
to 8
.0
11.1
aEx
clud
ing
benc
h-sc
ale
treat
men
ts.
bSo
me
proc
esse
s em
ploy
a c
ombi
natio
n of
ads
orpt
ion,
ion
exch
ange
, oxi
datio
n, p
reci
pita
tion/
copr
ecip
itatio
n, o
r filt
ratio
n to
rem
ove
arse
nic
from
wat
er.
AA
= a
ctiv
ated
alu
min
aEP
T =
Extra
ctio
n pr
oced
ure
toxi
city
test
mg/
L =
mill
igra
ms p
er li
ter
RC
RA
= R
esou
rce
Con
serv
atio
n an
d R
ecov
ery
Act
gpd
= ga
llons
per
day
m
gd =
mill
ion
gallo
ns p
er d
ay
TCLP
= T
oxic
ity c
hara
cter
istic
leac
hing
proc
edur
e m
g/kg
= m
illig
ram
s per
kilo
gram
-- =
Not
ava
ilabl
e T
WA
= T
otal
was
te a
naly
sis
WET
= W
aste
ext
ract
ion
test
12-1
Summary
Ion exchange has been used to treat groundwaterand drinking water containing arsenic. Based on theinformation collected to prepare this report, thistechnology typically can reduce arsenicconcentrations to less than 0.050 mg/L and in somecases has reduced arsenic concentrations to below0.010 mg/L. Its effectiveness is sensitive to avariety of untreated water contaminants andcharacteristics. It is used less frequently thanprecipitation/coprecipitation, and is most commonlyused to treat groundwater and drinking water, or as apolishing step for other water treatment processes.
Technology Description: Ion exchange is aphysical/chemical process in which ions heldelectrostatically on the surface of a solid areexchanged for ions of similar charge in a solution. It removes ions from the aqueous phase by theexchange of cations or anions between thecontaminants and the exchange medium (Ref. 12.1,12.4, 12.8).
Media Treated:• Groundwater• Surface water• Drinking water
Exchange Media Used in Ion Exchange to TreatArsenic:• Strong base anion exchange resins
Contaminated Water
Ion Exchange Resin
Effluent
Contaminated Water
Ion Exchange Resin
Effluent
Model of an Ion Exchange System12.0 ION EXCHANGE TREATMENT FOR ARSENIC
Technology Description and PrinciplesThe medium used for ion exchange is typically a resinmade from synthetic organic materials, inorganicmaterials, or natural polymeric materials that containionic functional groups to which exchangeable ions areattached (Ref. 12.3). Four types of ion exchange mediahave been used (Ref. 12.1):
• Strong acid• Weak acid• Strong base• Weak base
Strong and weak acid resins exchange cations whilestrong and weak base resins exchange anions. Becausedissolved arsenic is usually in an anionic form, andweak base resins tend to be effective over a smaller pH
range, strong base resins are typically used for arsenictreatment (Ref. 12.1).
Resins may also be categorized by the ion that isexchanged with the one in solution. For example,resins that exchange a chloride ion are referred to aschloride-form resins. Another way of categorizingresins is by the type of ion in solution that the resinpreferentially exchanges. For example, resins thatpreferentially exchange sulfate ions are referred to assulfate-selective. Both sulfate-selective and nitrate-selective resins have been used for arsenic removal(Ref. 12.1).
The resin is usually packed into a column, and ascontaminated water is passed through the column,contaminant ions are exchanged for other ions such aschloride or hydroxide in the resin (Ref. 12.4). Ionexchange is often preceded by treatments such asfiltration and oil-water separation to remove organics,suspended solids, and other contaminants that can foulthe resins and reduce their effectiveness.Ion exchange resins must be periodically regenerated toremove the adsorbed contaminants and replenish theexchanged ions (Ref. 12.4). Regeneration of a resinoccurs in three steps:
• Backwashing• Regeneration with a solution of ions • Final rinsing to remove the regenerating solution
The regeneration process results in a backwashsolution, a waste regenerating solution, and a wasterinse water. The volume of spent regeneration solutionranges from 1.5 to 10 percent of the treated watervolume depending on the feed water quality and type ofion exchange unit (Ref. 12.4). The number of ionexchange bed volumes that can be treated before
12-2
Factors Affecting Ion Exchange Performance
• Valence state - As(III) is generally notremoved by ion exchange (Ref. 12.4).
• Presence of competing ions - Competition forthe exchange ion can reduce the effectivenessof ion exchange if ions in the resin are replacedby ions other than arsenic, resulting in a needfor more frequent bed regeneration (Ref. 12.1,12.9).
• Fouling - The presence of organics, suspendedsolids, calcium, or iron, can cause fouling ofion exchange resins (Ref. 12.4).
• Presence of trivalent iron - The presence ofFe (III) could cause arsenic to form complexeswith the iron that are not removed by ionexchange (Ref. 12.1).
• pH - For chloride-form, strong-base resins, apH in the range of 6.5 to 9 is optimal. Outsideof this range, arsenic removal effectivenessdecreases quickly (Ref. 12.1).
0
7
0 1 2 3 4 5 6 7
Pilot
Full
regeneration is needed can range from 300 to 60,000(Ref. 12.1). The regenerating solution may be used upto 25 times before treatment or disposal is required. The final rinsing step usually requires only a few bedvolumes of water (Ref. 12.4).
Ion exchange can be operated using multiple beds inseries to reduce the need for bed regeneration; beds firstin the series will require regeneration first, and freshbeds can be added at the end of the series. Multiplebeds can also allow for continuous operation becausesome of the beds can be regenerated while otherscontinue to treat water. Ion exchange beds are typicallyoperated as a fixed bed, in which the water to be treatedis passed over an immobile ion exchange resin. Onevariation on this approach is to operate the bed in a non-fixed, countercurrent fashion in which water is appliedin one direction, usually downward, while spent ionexchange resin is removed from the top of the bed. Regenerated resin is added to the bottom of the bed. This method may reduce the frequency of resinregeneration (Ref. 12.4).
Media and Contaminants Treated
Anion exchange resins are used to remove solubleforms of arsenic from wastewater, groundwater, anddrinking water (Ref. 12.1, 12.4). Ion exchangetreatment is generally not applicable to soil and waste. It is commonly used in drinking water treatment forsoftening, removal of calcium, magnesium, and othercations in exchange for sodium, as well as removingnitrate, arsenate, chromate, and selenate (Ref. 12.9).
Type, Number, and Scale of Identified ProjectsTreating Water Containing Arsenic
Ion exchange of arsenic and groundwater, surfacewater, and drinking water is commercially available. Information is available on seven full-scale applications(Figure 12.1), including three applications togroundwater and surface water, and four applications todrinking water. No pilot-scale applications orapplications to industrial wastewater were found in thesources researched.
Summary of Performance Data
Table 12.1 presents the performance data found for thistechnology. Ion exchange treatment effectiveness canbe evaluated by comparing influent and effluentcontaminant concentrations. The single surface waterproject with both influent and effluent arsenicconcentration data had an influent concentrations of0.0394 mg/L, and an effluent concentration of 0.0229mg/L. Of the three drinking water projects with both
Figure 12.1Scale of Identified Ion Exchange Projects for
Arsenic Treatment
influent and effluent concentration data, all had influentconcentrations greater than 0.010 mg/L. Effluentconcentrations of less than 0.010 mg/L wereconsistently achieved in only one of these projects.
Projects that did not reduce arsenic concentrations tobelow 0.050 or 0.010 mg/L do not necessarily indicatethat ion exchange cannot achieve these levels. Thetreatment goal for some applications could have beenabove these levels and the technology may have beendesigned and operated to meet a higher arsenicconcentration. Information on treatment goals was notcollected for this report.
12-3
Factors Affecting Ion Exchange Costs
• Bed regeneration - Regenerating ionexchange beds reduces the amount of waste fordisposal and the cost of operation (Ref. 12.1).
• Sulfate - Sulfate (SO4) can compete witharsenic for ion exchange sites, thus reducingthe exchange capacity of the ion exchangemedia for arsenic. This can result in a need formore frequent media regeneration orreplacement, and associated higher costs (Ref.12.1).
• Factors affecting ion exchange performance- Items in the “Factors Affecting Ion ExchangePerformance” box will also affect costs.
Case Study: National Risk ManagementResearch Laboratory Study
A study by EPA ORD’s National Risk ManagementResearch Laboratory tested an ion exchange systemat a drinking water treatment plant. Weeklysampling for one year showed that the plantachieved an average of 97 percent arsenic removal. The resin columns were frequently regenerated(every 6 days). Influent arsenic concentrationsranged from 0.045 to 0.065 mg/L and effluentconcentrations ranged from 0.0008 to 0.0045 mg/L(Ref. 12.9) (see Project 1, Table 12.1).
The case study at the end of this section furtherdiscusses the use of ion exchange to remove arsenicfrom drinking water. Information for this project issummarized in Table 12.1, Project 1.
Applicability, Advantages, and Potential Limitations
For ion exchange systems using chloride-form resins,the treated water could contain increased levels ofchloride ions and as a result be corrosive. Chloridescan also increase the redox potential of iron, thusincreasing the potential for water discoloration if theiron is oxidized. The ion exchange process can alsolower the pH of treated waters (Ref. 12.4).
For ion exchange resins used to remove arsenic fromwater, the spent regenerating solution might contain ahigh concentration of arsenic and other sorbedcontaminants, and could be corrosive. Spent resin isproduced when the resin can no longer be regenerated.The spent resin may require treatment prior to reuse ordisposal (Ref. 12.8).
The order for exchange for most strong-base resins isprovided below, with the constituents with the greatestadsorption preference appearing at the top left (Ref.12.4).
HCrO4- > CrO4
2- > ClO4- > SeO4
2- > SO42- > NO3
- > Br-
> (HPO42-, HAsO4
2-, SeO32-, CO3
2-) > CN- > NO2- > Cl->
(H2PO4-, H2AsO4
-, HCO3-) > OH- > CH3COO- > F-
The effectiveness of ion exchange is also sensitive to avariety of contaminants and characteristics in theuntreated water, and organics, suspended solids,calcium, or iron can cause fouling. Therefore, it istypically applied to groundwater and drinking water,which are less likely to contain fouling contaminants. Itmay also be used as a polishing step for other watertreatment technologies.
More detailed information on selection and design ofarsenic treatment systems for small drinking watersystems is available in the document “ArsenicTreatment Technology Design Manual for SmallSystems “ (Ref. 12.10).
Summary of Cost Data
One project reported a capital cost for an ion exchangesystem of $6,886 with an additional $2,000 installationfee (Ref. 12.9, cost year not provided). The capacity ofthe system and O&M costs were not reported. Costdata for other projects using ion exchange were notfound.
The document "Technologies and Costs for Removal ofArsenic From Drinking Water" (Ref. 12.1) containsadditional information on the cost of ion exchangesystems to treat arsenic in drinking water to levelsbelow the revised MCL of 0.010 mg/L. The documentincludes capital and O&M cost curves for ion exchangeat various influent sulfate (SO4) concentrations. Thesecost curves are based on computer cost models fordrinking water treatment systems.
The curves estimate the costs for ion exchangetreatment systems with different design flow rates. Thedocument also contains information on the disposal costfor residuals from ion exchange. Table 3.4 in Section 3of this document contains cost estimates based on thesecurves for ion exchange. Many of the technologiesused to treat drinking water are applicable to treatmentof other types of water, and may have similar costs.
12-4
References
12.1 U.S. EPA. Technologies and Costs forRemoval of Arsenic From Drinking Water. EPA-R-00-028. Office of Water. December,2000. http://www.epa.gov/safewater/ars/treatments_and_costs.pdf
12.2 U.S. EPA. Arsenic & Mercury - Workshop onRemoval, Recovery, Treatment, and Disposal.Office of Research and Development. EPA-600-R-92-105. August 1992. http://www.epa.gov/ncepihom
12.3 Federal Remediation Technologies ReferenceGuide and Screening Manual, Version 3.0. Federal Remediation Technologies Roundtable(FRTR). http://www.frtr.gov/matrix2/top_page.html.
12.4 U.S. EPA. Regulations on the Disposal ofArsenic Residuals from Drinking WaterTreatment Plants. EPA-600-R-00-025. Officeof Research and Development. May 2000. http://www.epa.gov/ncepihom
12.5 Tidwell, L.G., et al. Technologies and PotentialTechnologies for Removing Arsenic fromProcess and Mine Wastewater. Presented at"REWAS'99." San Sebastian, Spain. September 1999. http://www.mtech.edu/metallurgy/arsenic/REWASAS%20for%20proceedings99%20in%20word.pdf
12.6 U.S. EPA. Final Best Demonstrated AvailableTechnology (BDAT) Background Document forK031, K084, K101, K102, CharacteristicArsenic Wastes (D004), CharacteristicSelenium Wastes (D010), and P and U WastesContaining Arsenic and Selenium ListingConstituents. Office of Solid Waste. May1990.
12.7 U.S. EPA. Groundwater Pump and TreatSystems: Summary of Selected Cost andPerformance Information at Superfund-financedSites. EPA-542-R-01-021b. EPA OSWER. December 2001. http://clu-in.org
12.8 Murcott, S. Appropriate RemediationTechnologies for Arsenic-Contaminated Wellsin Bangladesh. Massachusetts Institute ofTechnology. February 1999.http://web.mit.edu/civenv/html/people/faculty/murcott.html
12.9 U.S. EPA. Arsenic Removal from DrinkingWater by Ion Exchange and Activated AluminaPlants. EPA-600-R-00-088. Office of Researchand Development. October 2000. http://www.epa.gov/ORD/WebPubs/exchange/EPA600R00088.pdf
12.10 U.S. EPA. Arsenic Treatment TechnologyDesign Manual for Small Systems (100% Draftfor Peer Review). June 2002. http://www.epa.gov/safewater/smallsys/arsenicdesignmanualpeerreviewdraft.pdf
Tab
le 1
2.1
Ion
Exc
hang
e T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic
12-5
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
ale
Site
Nam
e or
Loc
atio
nIo
n E
xcha
nge
Med
ia o
r Pr
oces
s
Unt
reat
edA
rsen
icC
once
ntra
tion
Tre
ated
Ars
enic
Con
cent
ratio
n
Ion
Exc
hang
e M
edia
Reg
ener
atio
nIn
form
atio
nSo
urce
Dri
nkin
g W
ater
1--
Drin
king
Wat
erFu
ll--
Trea
tmen
t tra
inco
nsis
ting
ofpo
tass
ium
perm
anga
nate
gree
nsan
d ox
idiz
ing
filte
r fol
low
ed b
y a
mix
ed b
ed io
nex
chan
ge sy
stem
0.04
0 - 0
.065
mg/
La<0
.003
mg/
LaB
ed re
gene
rate
d ev
ery
6 da
ys12
.1
2--
Drin
king
Wat
erFu
ll--
Trea
tmen
t tra
inco
nsis
ting
of a
solid
oxid
izin
g m
edia
filte
r fol
low
ed b
y an
anio
n ex
chan
gesy
stem
0.01
9 - 0
.055
mg/
La<0
.005
- 0.
080
mg/
La--
12.1
3--
Drin
king
Wat
erFu
ll--
Stro
ngly
bas
ic g
elio
n ex
chan
ge re
sin
inch
lorid
e fo
rm
0.04
5 - 0
.065
mg/
L0.
0008
- 0.
0045
mg/
LR
esin
rege
nera
ted
ever
y fo
ur w
eeks
12.9
4--
Drin
king
Wat
erFu
ll--
Chl
orid
e-fo
rmst
rong
-bas
e re
sin
anio
n-ex
chan
gepr
oces
s
--0.
002
mg/
LSp
ent N
aCl b
rine
reus
ed to
rege
nera
teex
haus
ted
ion-
exch
ange
bed
12.8
Env
iron
men
tal M
edia
5W
ood
Pres
ervi
ng,
spill
of c
hrom
ated
copp
er a
rsen
ate
Surf
ace
wat
erFu
llV
anco
uver
,C
anad
a (s
itena
me
unkn
own)
Ani
on a
nd c
atio
nre
sins
0.03
94 m
g/L
0.02
29 m
g/L
--12
.2
6W
aste
dis
posa
l G
roun
dwat
er,
43,0
00 g
pdFu
llH
iggi
ns F
arm
Supe
rfun
dSi
te, F
rank
linTo
wns
hip,
NJ
Trea
tmen
t tra
inco
nsis
ting
of a
irst
rippi
ng, m
etal
spr
ecip
itatio
n,fil
tratio
n, a
nd io
nex
chan
ge
----
--12
.7
Tab
le 1
2.1
Ion
Exc
hang
e T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic (c
ontin
ued)
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
ale
Site
Nam
e or
Loc
atio
nIo
n E
xcha
nge
Med
ia o
r Pr
oces
s
Unt
reat
edA
rsen
icC
once
ntra
tion
Tre
ated
Ars
enic
Con
cent
ratio
n
Ion
Exc
hang
e M
edia
Reg
ener
atio
nIn
form
atio
nSo
urce
12-6
7W
ood
pres
ervi
ngG
roun
dwat
er,
4,00
0 gp
dFu
llM
cCor
mic
kan
d B
axte
rC
reos
otin
gC
o. S
uper
fund
Site
, Por
tland
,O
R
Trea
tmen
t tra
inco
nsis
ting
offil
tratio
n, io
nex
chan
ge, a
ndca
rbon
ads
orpt
ion
----
--12
.7
a D
ata
are
for e
ntire
trea
tmen
t tra
in, i
nclu
ding
uni
t ope
ratio
ns th
at a
re n
ot io
n ex
chan
ge.
-- =
Not
ava
ilabl
e.TW
A =
Tot
al w
aste
ana
lysi
s.gp
d =
gallo
ns p
er d
aym
g/L
= m
illig
ram
s per
lite
r.
13-1
Plume
Porous Treatment Media
Direction of Groundwater Flow
Lower Confining Layer(Aquitard)
Cap
TreatmentWall
Decreased Contaminant Concentration
Plume
Porous Treatment Media
Direction of Groundwater Flow
Lower Confining Layer(Aquitard)
Cap
TreatmentWall
Decreased Contaminant Concentration
Model of a Permeable Reactive Barrier System
Technology Description: Permeable reactivebarriers (PRBs) are walls containing reactive mediathat are installed across the path of a contaminatedgroundwater plume to intercept the plume. Thebarrier allows water to pass through while the mediaremove the contaminants by precipitation,degradation, adsorption, or ion exchange.
Media Treated:• Groundwater (in situ)
Chemicals and Reactive Media Used in PRBs toTreat Arsenic:• Zero valent iron (ZVI)• Limestone• Basic oxygen furnace slag• Surfactant modified zeolite• Ion exchange resin
Installation Depth:• Up to 30 feet deep using established techniques• Innovative techniques required for depths
greater than 30 feet
Summary
Permeable reactive barriers (PRBs) are being usedto treat arsenic in groundwater at full scale at only afew sites. Although many candidate materials forthe reactive portion of the barrier have been tested atbench scale, only zero valent iron and limestonehave been used at full scale. The installationtechniques for PRBs are established for depths lessthan 30 feet, and require innovative installationtechniques for deeper installations.
13.0 PERMEABLE REACTIVE BARRIERSFOR ARSENIC
Technology Description and Principles
PRBs are applicable to the treatment of both organicand inorganic contaminants. The former usually arebroken down into carbon dioxide and water, while thelatter are converted to species that are less toxic or lessmobile. The most frequent applications of PRBs is thein situ treatment of groundwater contaminated withchlorinated solvents. A number of different treatmentmedia have been used, the most common being zero-valent iron (ZVI). Other media include hydrated lime,slag from steelmaking processes that use a basic oxygenfurnace, calcium oxides, chelators (ligands selected fortheir specificity for a given metal), iron oxides,sorbents, substitution agents (e.g., ion exchange resins)
and microbes (Ref. 13.6, 13.8, 13. 18). The cost of thereactive media will impact the overall cost of PRBremedies. The information sources used for this reportincluded information about PRB applications usingZVI, basic oxygen furnace slag, limestone, surfactantmodified zeolite, and ion exchange resin to treatarsenic.
13-2
For the PRB projects identified for this report, ZVI wasthe most commonly used reactive media. Asgroundwater reacts with ZVI, pH increases, Ehdecreases, and the concentration of dissolved hydrogenincreases. These basic chemical changes promote avariety of processes that impact contaminantconcentrations. Increases in pH favor the precipitationof carbonates of calcium and iron as well as insolublemetal hydroxides. Decreases in Eh drive reduction ofmetals and metalloids with multiple oxidation states. Finally, an increase in the partial pressure of hydrogenin subsurface systems supports the activity of variouschemotrophic organisms that use hydrogen as an energysource, especially sulfate-reducing bacteria andiron-reducing bacteria (Ref. 13.15).
Arsenate [As (V)] ions bind tightly to the iron filings,causing the ZVI to be oxidized to ferrous iron,aerobically or anaerobically in the presence of water, asshown by the following reactions:
(anaerobic) Fe0 + 2H2O Y Fe+2 + H2 + 2OH-
(aerobic) 2Fe0 + 2H2O + O2 Y 2Fe+2 + 4OH-
The process results in a positively charged iron surfacethat sorbs the arsenate species by electrostaticinteractions (Ref. 13.5, 13.17).
In systems where dissolved sulfate is reduced to sulfideby sulfate-reducing bacteria, arsenic may be removedby the precipitation of insoluble arsenic sulfide (As2S3)or co-precipitated with iron sulfides (FeS) (Ref. 13.15).
PRBs can be constructed by excavating a trench of theappropriate width and backfilling it with a reactivemedium. Commercial PRBs are built in two basicconfigurations: the funnel-and-gate and the continuouswall. The funnel-and-gate uses impermeable walls, forexample, sheet pilings or slurry walls, as a “funnel” todirect the contaminant plume to a “gate(s)” containingthe reactive media, while the continuous wall transectsthe flow path of the plume with reactive media (Ref.13.6).
Most PRBs installed to date have had depths of 50 feet(ft) or less. Those having depths of 30 ft or less can beinstalled with a continuous trencher, while depthsbetween 30 and 70 ft require a more innovativeinstallation method, such as biopolymers. Installationof PRBs at depths greater than 70 ft is more challenging(Ref. 13.13).
Media and Contaminants Treated
This technology can treat both organic and inorganiccontaminants. Organic contaminants are broken downinto less toxic elements and compounds, such as carbon
dioxide and water. Inorganic contaminants areconverted to species that are less toxic or less mobile. Inorganic contaminants that can be treated by PRBsinclude, but are not limited to, chromium (Cr), nickel(Ni), lead (Pb), uranium (U), technetium (Tc), iron (Fe),manganese (Mn), selenium (Se), cobalt (Co), copper(Cu), cadmium (Cd), zinc (Zn), arsenic (As), nitrate (NO3
-), sulfate (SO42-), and phosphate (PO4
3-). Thecharacteristics that these elements have in common isthat they can undergo redox reactions and can formsolid precipitates with common groundwaterconstituents, such as carbonate (CO3
2- ), sulfide (S2- ),and hydroxide (OH- ). Some common sources of thesecontaminants are mine tailings, septic systems, andbattery recycling/disposal facilities (Ref. 13.5, 13.6,13.14).
PRBs are designed to treat groundwater in situ. Thistechnology is not applicable to other contaminatedmedia such as soil, debris, or industrial wastes.
Type, Number, and Scale of Identified ProjectsTreating Water Containing Arsenic
PRBs are commercially available and are being usedto treat groundwater containing arsenic at a full scale attwo Superfund sites, the Monticello Mill Tailings andTonolli Corporation sites, although arsenic is not theprimary target contaminant for treatment by thetechnology at either site (Ref. 13.1). At a thirdSuperfund site, the Asarco East Helena site, thistechnology has been tested at a bench scale, andimplementation at a full scale to treat arsenic iscurrently planned (Ref. 13.15). In 1999, a pilot-scaletreatment was conducted at Bodo Canyon Disposal CellMill Tailings Site, Durango, Colorado, to remediategroundwater contaminated with arsenic (Ref. 13.12). In addition, PRBs have been used in two bench-scaletreatability studies by the U.S. Department of Energy’sGrand Junction Office (GJO) to evaluate theirapplication to the Monticello Mill Tailings site and aformer uranium ore processing site (Ref. 13.3). Figure13.1 shows the number of applications found at eachscale.
Additional bench-scale studies of the treatment ofarsenic using PRBs that contain various reactive mediaare listed below (Ref. 13.8, 13.11). These studies werenot conducted to evaluate the application of PRBs tospecific sites. The organizations conducting the studiesare listed in parentheses. However, no performancedata are available for the studies, and therefore, they arenot included in Figure 13.1 above, or in Table 13.1.
13-3
2
3
5
0 1 2 3 4 5
Bench
Pilot
Full
Factors Affecting PRB Performance
� Fractured rock - The presence of fracturedrock in contact with the PRB may allowgroundwater to flow around, rather thanthrough, the PRB (Ref. 13.6).
� Deep aquifers and contaminant plumes -PRBs may be difficult to install for deepaquifers and contaminant plumes (>70 ft deep)(Ref. 13.13).
� High aquifer hydraulic conductivity - Thehydraulic conductivity of the barrier must begreater than that of the aquifer to preventpreferential flow around the barrier (Ref.13.13).
� Stratigraphy - Site stratigraphy may affectPRB installation. For example, clay layersmight be "smeared" during installation,reducing hydraulic conductivity near the PRB(Ref. 13.6).
� Barrier plugging - Permeability and reactivityof the barrier may be reduced by precipitationproducts and microbial growth (Ref. 13.6).
Other Bench-Scale Studies Using Adsorption or IonExchange Barriers
� Activated alumina (Dupont)� Bauxite (Dupont)� Ferric oxides and oxyhydroxides (Dupont,
University of Waterloo), � Peat, humate, lignite, coal (Dupont)� Surfactant-modified zeolite (New Mexico Institute
of Mining and Technology)
Other Bench-Scale Studies Using Precipitation Barriers
� Ferrous hydroxide, ferrous carbonate, ferroussulfide (Dupont)
� Limestone (Dupont)� Zero-Valent Metals (DOE GJO)
Figure 13.1Scale of Identified Permeable Reactive Barrier
Projects for Arsenic Treatment
Summary of Performance Data
Table 1 provides performance data for full-scale PRBtreatment of groundwater contaminated with arsenic atthree sites, two pilot-scale treatability study and fivebench-scale treatability studies. PRB performancetypically is measured by taking groundwater samples atpoints upgradient and downgradient of the wall andmeasuring the concentration of contaminants of concernat each point. Data on the Monticello site show areduction in arsenic concentration from a range of 0.010to 0.013 mg/L before installation of the PRB to <0.002mg/L after the installation of a PRB. One pilot-scalestudy showed a reduction in arsenic concentrationsfrom 0.4 mg/L to 0.02 mg/L. Four bench-scaletreatability studies also show a reduction in arsenicconcentrations.
Applicability, Advantages, and Potential Limitations
PRBs are a passive treatment technology, designed tofunction for a long time with little or no energy input. They produce less waste than active remediation (forexample, extraction systems like pump and treat), as thecontaminants are immobilized or altered in thesubsurface (Ref. 13.14). PRBs can treat groundwaterwith multiple contaminants and can be effective over arange of concentrations. PRBs require no abovegroundequipment, except monitoring devices, allowing returnof the property to economic use during remediation(Ref. 13.5, 13.14). PRBs are best applied to shallow,unconfined aquifer systems in unconsolidated deposits,as long as the reactive material is more conductive thanthe aquifer. (Ref. 13.13).
PRBs rely on the natural movement of groundwater;therefore, aquifers with low hydraulic conductivity canrequire relatively long periods of time to be remediated. In addition, PRBs do not remediate the entire plume,but only the portion of the plume that has passedthrough the PRB. Because cleanup of groundwatercontaminated with arsenic has been conducted at onlytwo Superfund sites and these barriers have beenrecently installed (Tonolli in 1998 and Monticello in1999), the long-term effectiveness of PRBs for arsenictreatment has not been demonstrated (Ref. 13.13).
13-4
Case Study: Monticello Mill Tailings SitePermeable Reactive Barrier
The Monticello Mill Tailings in Southeastern Utahis a former uranium/vanadium processing mill andmill tailings impoundment (disposal pit). In January1998, the U.S. Department of Energy completed aninterim investigation to determine the nature andextent of contamination in the surface water andgroundwater in operable unit 3 of the site. Arsenicwas one among several contaminants in thegroundwater, and was found at concentrationsranging from 0.010 to 0.013 mg/L. A PRBcontaining ZVI was constructed in June 1999 totreat heavy metal and metalloid contaminants in thegroundwater. Five rounds of groundwater samplingoccurred between June 1999 and April 2000, andwas expected to continue on a quarterly basis untilJuly 2001. The average concentration of arsenicentering the PRB, as measured from September toNovember 1999 was 0.010 mg/L, and the effluentconcentration, measured in April 2000, was lessthan 0.0002 mg/L (Ref. 13.1, 13.2, 13.14) (seeProject 2, Table 13.1).
Factors Affecting PRB Costs
� PRB depth - PRBs at depths greater than 30feet may be more expensive to install, requiringspecial excavation equipment and constructionmaterials (Ref. 13.13).
� Reactive media - Reactive media vary in cost,therefore the reactive media selected can affectPRB cost.
� Factors affecting PRB performance - Items inthe �Factors Affecting PRB Performance� boxwill also affect costs.
Summary of Cost Data
EPA compared the costs of pump-and-treat systems at32 sites to the costs of PRBs at 16 sites. Although thesites selected were not a statistically representativesample of groundwater remediation projects, the capitalcosts for PRBs were generally lower than those forpump and treat systems (Ref. 13.13). However, at theMonticello site, estimates showed that capital costs fora PRB were greater than those for a pump-and-treatsystem, but lower operations and maintenance costswould result in a lower life-cycle cost to achieve similarcleanup goals. For the PRB at the Monticello site, totalcapital cost was $1,196,000, comprised of $1,052,000for construction and $144,000 for the reactive PRBmedia. Construction costs are assumed to includeactual construction costs and not design activities ortreatability studies (Ref. 13.14, cost year not provided). Cost data for the other projects described in the sectionare not available.
References
13.1 U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition). Office of Solid Waste and Emergency Response. EPA-542-R-01-004. February 2001. http://clu-in.org
13.2 Personal communication with Paul Mushovic,RPM, Monticello Mill Tailings - OU3 Superfundsite. April 20, 2001.
13.3 U.S. Department of Energy, Grand JunctionOffice (DOE-GJO). Permeable ReactiveBarriers: Treatability Studies. March 2000.http://www.doegjpo.com/.
13.4 Federal Remediation Technologies Roundtable:Remediation Technologies Screening Matrix andReference Guide Version 3.0. http://www.frtr.gov/matrix2/top_page.html.
13.5 Ott N. Permeable Reactive Barriers forInorganics. National Network of EnvironmentalManagement Studies (NNEMS) Fellow. July2000. http://www.clu-in.org.
13.6 U.S. EPA. Permeable Reactive BarrierTechnologies for Contaminant Remediation.Office of Research and Development. EPA-600-R-98-125. September 1998.http://www.epa.gov/ncepi/Catalog/EPA600R98125.html
13.7 U.S. EPA Technology Innovation Office andOffice of Research and Development. Remediation Technologies Development Forum(RTDF). Permeable Reactive Barrier InstallationProfiles. January 2000.http://www.rtdf.org/public/permbarr/prbsumms/.
13.8 DOE - GJO. Research and Application ofPermeable Reactive Barriers. K0002000. April1998. http://www.gwrtac.org/pdf/permeab2.pdf
13.9 Baker MJ, Blowes DW, Ptacek CJ. PhosphorousAdsorption and Precipitation in a PermeableReactive Wall: Applications for WastewaterDisposal Systems. International ContainmentTechnology Conference and Exhibition,February 9-12, 1997. St. Petersburg, Florida.
13-5
13.10 McRae CW, Blowes DW, Ptacek CJ. Laboratory-scale investigation of remediation ofAs and Se using iron oxides. Sixth Symposiumand Exhibition on Groundwater and SoilRemediation, March 18-21, 1997. Montreal,Quebec, Canada.
13.11 U.S. EPA. In Situ Remediation TechnologyStatus Report: Treatment Walls. Office of SolidWaste and Emergency Response. EPA 542-K-94-004. April 1995. http://www.clu-in.org.
13.12 U.S. EPA. Innovative RemediationTechnologies: Field Scale DemonstrationProjects in North America, 2nd Edition. Office ofSolid Waste and Emergency Response. EPA-542-B-00-004. June 2000. http://clu-in.org.
13.13 U.S. EPA. Cost Analyses for SelectedGroundwater Cleanup Projects: Pump and TreatSystems and Permeable Reactive Barriers. Office of Solid Waste and Emergency Response. EPA-542-R-00-013. February 2001. http://clu-in.org.
13.14 DOE. Permeable Reactive Treatment (PeRT)Wall for Rads and Metals. Office ofEnvironmental Management, Office of Scienceand Technology. DOE/EM-0557. September2000. http://apps.em.doe.gov/ost/pubs/itsrs/itsr2155.pdf
13.15 Attachment to an E-mail from Rick Wilkin, U.S.EPA Region 8 to Linda Fiedler, U.S. EPATechnology Innovation Office. July 27, 2001.
13.16 Lindberg J, Sterneland J, Johansson PO,Gustafsson JP. Spodic material for in situtreatment of arsenic in ground water. GroundWater Monitoring and Remediation. 17, 125-3-. December 1997.http://www.ce.kth.se/aom/amov/people/gustafjp/abs11.htm
13.17 Su, C.; Puls, R. W. Arsenate and arseniteremoval by zerovalent iron: kinetics, redoxtransformation, and implications for in situgroundwater remediation. EnvironmentalScience and Technology. Volume 35. pp. 1487-1492. 2001.
3.18 Smyth DJ, Blowes DW, Ptacek, CJ (Departmentof Earth Sciences, University of Waterloo). Steel Production Wastes for Use in PermeableReactive Barriers (PRBs). Third InternationalConference on Remediation of Chlorinated andRecalcitrant Compounds. May 20-23, 2000. Monterey, CA.
13.19 Personal Communication from David Smyth,University of Waterloo to Sankalpa Nagaraja,Tetra Tech, EM Inc. August 13, 2002.
13-6
Tab
le 1
3.1
Perm
eabl
e R
eact
ive
Bar
rier
Ars
enic
Tre
atm
ent P
erfo
rman
ce D
ata
for
Ars
enic
Proj
ect
Num
ber
Scal
eSi
te N
ame
and
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
n (m
g/L
)Fi
nal A
rsen
icC
once
ntra
tion
(mg/
L)
Bar
rier
Typ
e an
dM
edia
Proj
ect D
urat
ion
Sour
ce1
Full
Tono
lli C
orpo
ratio
n Su
perf
und
Site
, Nes
queh
onin
g, P
A0.
313
Not
ava
ilabl
eTr
ench
, lim
esto
neA
ugus
t 199
8 -
pres
ent
13.1
, 13.
7
2Fu
llM
ontic
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Mill
Tai
lings
- O
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ticel
lo, U
T0.
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13
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002
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nd g
ate,
ZV
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ne 1
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ite, C
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-pr
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, Nor
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io, C
anad
a0.
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mg/
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ench
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ture
of
ZVI,
surf
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ed z
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sin
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o C
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rmer
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ity, A
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ena
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elen
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ench
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g/L
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----
13.1
610
Ben
ch–
4 m
g/L
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g/L
Bas
ic o
xyge
n fu
rnac
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ag–
13.1
8
ZVI =
Zer
o va
lent
iron
mg/
L =
Mill
igra
ms p
er li
ter
-- =
Not
ava
ilabl
e
IICARSENIC TREATMENT TECHNOLOGIES
APPLICABLE TO SOIL, WASTE, AND WATER
14-1
Process Control System
Extraction/Exchange
Processing ProcessingAC / DC
Converter
-Cathode
CathodicProcessFluidAcid Front
and/or AnodicProcess Fluid
Anode+
Processed Media
OH -
F - Cl -
CN -PO3-
4
NO -3
Ca2+
Pb2+
Pb2+
Zn2+
Cr2+
H3O+
Extraction/Exchange
Ca2+
Process Control System
Extraction/Exchange
Processing ProcessingAC / DC
Converter
-Cathode
CathodicProcessFluidAcid Front
and/or AnodicProcess Fluid
Anode+
Processed Media
OH -
F - Cl -
CN -PO3-
4
NO -3
Ca2+
Pb2+
Pb2+
Zn2+
Cr2+
H3O+
Extraction/Exchange
Ca2+
Model of an Electrokinetic Treatment System
Summary
Electrokinetic treatment is an emerging remediationtechnology designed to remove heavy metalcontaminants from soil and groundwater. Thetechnology is most applicable to soil with smallparticle sizes, such as clay. However, itseffectiveness may be limited by a variety ofcontaminants and soil and water characteristics. Information sources researched for this reportidentified a limited number of applications of thetechnology to arsenic.
Technology Description: Electrokineticremediation is based on the theory that a low-density current will mobilize contaminants in theform of charged species. A current passed betweenelectrodes is intended to cause water, ions, andparticulates to move through the soil, waste, andwater (Ref. 14.8). Contaminants arriving at theelectrodes can be removed by means ofelectroplating or electrodeposition, precipitation orcoprecipitation, adsorption, complexing with ionexchange resins, or by pumping of water (or otherfluid) near the electrode (Ref. 14.10).
Media Treated:• Soil• Groundwater• Industrial wastes
Chemicals Used in Electrokinetic Process toTreat Arsenic:• Sulfuric Acid• Phosphoric Acid• Oxalic Acid
14.0 ELECTROKINETIC TREATMENT OFARSENIC
Technology Description and Principles
In situ electrokinetic treatment of arsenic uses thenatural conductivity of the soil (created by pore waterand dissolved salts) to affect movement of water, ions,and particulates through the soil (Ref. 14.8). Waterand/or chemical solutions can also be added to enhancethe recovery of metals by electrokinetics. Positively-
14-2
Factors Affecting Electrokinetic TreatmentPerformance
• Contaminant properties - The applicability ofelectrokinetics to soil and water containingarsenic depends on the solubility of theparticular arsenic species. Electrokinetictreatment is applicable to acid-soluble polarcompounds, but not to insoluble metals (Ref.14.6).
• Salinity and cation exchange capacity - Thetechnology is most efficient when theseparameters are low (Ref. 14.14). Chemicalreduction of chloride ions at the anode by theelectrokinetic process may also producechlorine gas (Ref. 14.6).
• Soil moisture - Electrokinetic treatmentrequires adequate soil moisture; thereforeaddition of a conducting pore fluid may berequired (Ref. 14.7). Electrokinetic treatment ismost applicable to saturated soils (Ref. 14.9). However, adding fluid to allow treatment ofsoils without sufficient moisture may flushcontaminants out of the targeted treatment area.
• Polarity and magnitude of the ionic charge -These factors affect the direction and rate ofcontaminant movement (Ref. 14.11).
• Soil type - Electrokinetic treatment is mostapplicable to homogenous soils (Ref. 14.9). Fine-grained soils are more amenable toelectrokinetic treatment due to their largesurface area, which provides numerous sites forreactions necessary for electrokinetic processes(Ref. 14.13).
• pH - The pH can affect processelectrochemistry and cause precipitation ofcontaminants or other species, reducing soilpermeability and inhibiting recovery. Thedeposition of precipitation solids may beprevented by flushing the cathode with water ora dilute acid (Ref. 14.14).
charged metal or metalloid cations, such as As (V) andAs (III) migrate to the negatively-charged electrode(cathode), while metal or metalloid anions migrate tothe positively charged electrode (anode) (Ref. 14.9). Extraction may occur at the electrodes or in an externalfluid cycling/extraction system (Ref. 14.11). Alternately, the metals can be stabilized in situ byinjecting stabilizing agents that react with andimmobilize the contaminants (Ref. 14.12). Arsenic hasbeen removed from soils treated by electrokineticsusing an external fluid cycling/extraction system (Ref.14.2, 14.18).
This technology can also be applied ex situ togroundwater by passing the water between electrodes. The current causes arsenic to migrate toward theelectrodes, and also alters the pH and oxidation-reduction potential of the water, causing arsenic toprecipitate/coprecipitate. The solids are then removedfrom the water using clarification and filtration (Ref.14.21).
Media and Contaminants Treated
Electrokinetic treatment is an in situ treatment processthat has had limited use to treat soil, groundwater, andindustrial wastes containing arsenic. It has also beenused to treat other heavy metals such as zinc, cadmium,mercury, chromium, and copper (Ref. 14.1, 14.4,14.20).
Electrokinetic treatment may be capable of removingcontaminants from both saturated and unsaturated soilzones, and may be able to perform without the additionof chemical or biological agents to the site. Thistechnology also may be applicable to low-permeabilitysoils, such as clay (Ref. 14.1, 14.4, 14.9).
Type, Number, and Scale of Identified ProjectsTreating Soil, Waste, and Water Containing Arsenic
The sources identified for this report containedinformation on one full-scale, three pilot-scale, andthree bench-scale applications of electrokineticremediation to arsenic. Figure 14.1 shows the numberof applications identified at each scale.
Summary of Performance Data
Table 14.1 provides a performance summary ofelectrokinetic treatment of arsenic. One full-scaleapplication reduced arsenic concentrations in soil fromgreater than 250 mg/kg to less than 30 mg/kg. One exsitu pilot-scale application reduced arsenic ingroundwater from 0.6 mg/L to 0.013 mg/L. The casestudy at the end of this section further discusses this
project, and information in Table 14.1, Project 3summarizes the available information about it.
Applicability, Advantages, and Potential Limitations
Electrokinetics is an emerging technology withrelatively few applications for arsenic treatment. It isan in situ treatment technology, and therefore does notrequire excavation of contaminated soil or pumping ofcontaminated groundwater. Its effectiveness may belimited by a variety of soil and contaminantcharacteristics, as discussed in the box opposite. In
14-3
3
1
3
0 1 2 3 4
Bench
Pilot
Full
Case Study: The Overpelt Project
A pilot-scale test of electrokinetic remediation ofarsenic in groundwater was conducted in Belgiumin 1997. This ex situ application involved pumpinggroundwater contaminated with zinc, arsenic, andcadmium and treating it in an electrokineticremediation system with a capacity of 6,600 gpm. The treatment system precipitated thecontaminants, and the precipitated solids wereremoved using clarification and filtration. Theelectrokinetic treatment system did not useadditives or chemicals. The treatment reducedarsenic concentrations in groundwater from 0.6mg/L to 0.013 mg/L. The reported costs of thetreatment were $0.004 per gallon for total cost, and$0.002 per gallon for O&M. (Ref. 14.21) (seeProject 3, Table 14.1).
Factors Affecting Electrokinetic Treatment Costs
• Contaminant extraction system - Someelectrokinetic systems remove the contaminantfrom the subsurface using an extraction fluid. In such systems, the extraction fluid mayrequire further treatment, which can increasethe cost (Ref. 14.4).
• Factors affecting electrokinetic treatmentperformance - Items in the “Factors AffectingElectrokinetic Treatment Performance” boxwill also affect costs.
addition, its treatment depth is limited by the depth towhich the electrodes can be placed.
Figure 14.1Scale of Electrokinetic Projects for Arsenic
Treatment
Summary of Cost Data
Estimated costs of in situ electrokinetic treatment ofsoils containing arsenic range from $50 - $270 per cy(Ref. 14.2, 14.4, cost year not provided). The reportedcosts for one pilot-scale, ex situ treatment ofgroundwater of the treatment were $0.004 per gallon fortotal cost, and $0.002 per gallon for O&M. (Ref. 14.21)(see Project 3, Table 14.1).
References
14.1 U.S. EPA. In Situ Remediation Technology:Electrokinetics. Office of Solid Waste andEmergency Response, Technology InnovationOffice. EPA-542-K-94-007. April 1995. http://clu-in.org
14.2 U.S. EPA. Database for EPA REACH IT(REmediation And CHaracterization InnovativeTechnologies). March 2001. http://www.epareachit.org.
14.3 U.S. EPA. Electrokinetics at an Active PowerSubstation. Federal Remediation TechnologiesRoundtable. March 2000.http://www.frtr.gov/costperf.html.
14.4 Electric Power Research Institute. ElectrokineticRemoval of Arsenic from Contaminated Soil: Experimental Evaluation. July 2000. http://www.epri.com/OrderableitemDesc.asp?product_id.
14.5 Ground-Water Remediation TechnologiesAnalysis Center. Technology Overview Report: Electrokinetics. July 1997.http://www.gwrtac.org/pdf/elctro_o.pdf.
14.6 U.S. EPA. Contaminants and Remedial Optionsat Selected Metal-Contaminated Sites. Office ofResearch and Development. EPA-540-R-95-512. July 1995.http://www.epa.gov/ncepi/Catalog/EPA540R95512.html
14.7 U.S. EPA. Recent Developments for In SituTreatment of Metals Contaminated Soils. Technology Innovation Office. Washington,DC. March 5, 1997.http://clu-in.org/download/remed/ metals2.pdf
14.8 Will, F. "Removing Toxic Substances from SoilUsing Electrochemistry," Chemistry andIndustry, p. 376-379. 1995.
14-4
14.9 Evanko, C.R., and D.A. Dzomback. Remediation of Metals-Contaminated Soils andGroundwater. Prepared for the Ground-WaterRemediation Technologies Analysis Center,Technology Evaluation Report TE-97-01.October 1997.http://www.gwrtac.org/pdf/metals.pdf
14.10 Lindgren, E.R., et al. "ElectrokineticRemediation of Contaminated Soils: An Update,"Waste Management 92, Tucson, Arizona. 1992.
14.11 Earthvision. "Electrokinetic Remediation,"http://www.earthvision.net/filecomponent/1727.html, as of October 1999.
14.12 LaChuisa, L. E-mail attachment from LaurieLaChuisa, Electrokinetics, Inc., to Kate Mikulka,Science Applications International Corporation,Process description. August 1999.
14.13 Acar, Y. B. and R. J. Gale. "ElectrokineticRemediation: Basics and Technology Status,"Journal of Hazardous Materials, 40: p. 117-137. 1995.
14.14 Van Cauwenberghe, L. Electrokinetics,prepared for the Ground-Water RemediationTechnologies Analysis Center, GWRTAC OSeries Technology Overview Report TO-97-03. July 1997. http://www.gwrtac.org/pdf/elctro_o.pdf
14.15 LaChuisa, L. E-mail from Laurie LaChuisa,Electrokinetics, Inc., to Kate Mikulka, ScienceApplications International Corporation, Casestudy for electrokinetic extraction/stabilization ofarsenic. August 1999.
14.16 LaChuisa, L. E-mail from Laurie LaChuisa,Electrokinetics, Inc., to Deborah R. Raja,Science Applications International Corporation,Responses to questions on Case Study. October13, 1999.
14.17 LaChuisa, L. Telephone contact between LaurieLaChuisa, Electrokinetics, Inc., and Deborah R.Raja, Science Applications InternationalCorporation, Responses to questions on CaseStudy. October 11, 1999.
14.18 AAA Geokinetics - Electrokinetic Remediation.April 24, 2001.http://www.geokinetics.com/giiek.htm
14.19 Fabian, G.L., U.S. Army Environmental Center,and Dr. R.M. Bricka, Waterways ExperimentStation. "Electrokinetic Remediation at NAWSPoint Mugu," paper presented at theU.S./German Data Exchange Meeting.September 1999.
14.20 Florida State University – College ofEngineering. August 2001. http://www.eng.fsu.edu/departments/civil/research/arsenicremedia/index.htm
14.21 Pensaert, S. The Treatment of AquifersContaminated with Arsenic, Zinc and Cadmiumby the Bipolar Electrolysis Technique: TheOverpelt Project. 1998.
14.22 Ribeiro, AB, Mateus EP, Ottosen LM, Bech-Nielsen G. Electrodialytic Removal of Cu, Cr,and As from Chromated Copper Arsenate-Treated Timber Waste. Environmental Science& Technology. Vol. 34, No. 5. 2000.http://www.vista.gov.vn/nganhangdulieu/tapchi/clv1899/2000/v34s5.htm
14.23 Redwine, J.C. Innovative Technologies forRemediation of Arsenic in Soil andGroundwater. Southern Co. Services, Inc. August 2001.
14.24 Markey, R. Comparison and Economic Analysisof Arsenic Remediation Methods Used in Soiland Groundwater. M.S. Thesis. FAMU-FSUCollege of Engineering. 2000.
14-5
Tab
le 1
4.1
Ele
ctro
kine
tic T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
ia, V
olum
eSc
ale
Site
Nam
e an
dL
ocat
ion
Initi
al A
rsen
icC
once
ntra
tion
Fina
l Ars
enic
Con
cent
ratio
nor
Tre
atm
ent R
esul
tsE
lect
roki
netic
Pro
cess
Des
crip
tion
Sour
ce1
Woo
d Pr
eser
ving
Soil,
325
cub
icya
rds
Full
Pede
rok
Plan
tK
win
t,Lo
pper
sum
, N
ethe
rland
s
> 25
0 m
g/kg
< 30
mg/
kgC
onta
min
ant r
emov
edby
rec
ircul
atio
n of
ele
ctro
lyte
thro
ugh
casi
ng a
roun
d el
ectro
des
14.2
,14
.18
2H
erbi
cide
appl
icat
ion
Soil,
690
cub
icya
rds
Pilo
t--
450
mg/
kg--
--14
.12,
14.1
5,14
.16,
14.1
7
3M
etal
s ref
inin
gan
d sm
eltin
gG
roun
dwat
erPi
lot
Bel
gium
0.6
mg/
L0.
013
mg/
LB
ipol
ar e
lect
roly
sis,
with
out u
se o
fad
ditio
nal c
hem
ical
s. Ex
situ
, pum
p an
d tre
atap
plic
atio
n
14.2
1
4H
erbi
cide
appl
icat
ion
Soil
&G
roun
dwat
erPi
lot
Flor
ida
ND
- 1,
400
mg/
kg<0
.005
- 0.
7m
g/L
--B
ipol
ar e
lect
roly
sis,
with
out u
se o
fad
ditio
nal c
hem
ical
s
14.2
4
5C
attle
vat
(pes
ticid
e)So
ilB
ench
Bla
ckw
ater
Riv
erSt
ate
Fore
st, F
L11
3 m
g/kg
4.7%
of a
rsen
ic m
igra
ted
toan
ode,
1.6
% to
cat
hode
Add
ition
of s
ulfu
ric a
cid
to e
nhan
ceel
ectro
kine
tic p
roce
ss
14.4
6C
attle
vat
(pes
ticid
e)So
ilB
ench
Bla
ckw
ater
Riv
erSt
ate
Fore
st, F
L11
3 m
g/kg
25%
of a
rsen
ic m
igra
ted
toan
ode,
non
e to
cat
hode
Add
ition
of p
hosp
horic
acid
to e
nhan
ceel
ectro
kine
tic p
roce
ss
14.4
7W
ood
Pres
ervi
ngSa
wdu
st fr
omC
CA
-trea
ted
pol
e
Ben
chLe
iria,
Por
tuga
l81
1- 8
71 m
g/kg
27-9
9% re
mov
al e
ffic
ienc
yEl
ectro
dial
ytic
rem
oval
,en
hanc
ed b
y ad
ditio
n of
oxal
ic a
cid
14.2
2
-- =
Not
ava
ilabl
eC
CA
= C
hrom
ated
cop
per a
rsen
ate
mg/
L =
Mill
igra
ms p
er li
ter
mg/
kg =
Mill
igra
ms p
er k
ilogr
am
15-1
Technology Description: Phytoremediation isdesigned to use plants to degrade, extract, contain,or immobilize contaminants in soil, sediment, orgroundwater (Ref. 15.6). Typically, trees with deeproots are applied to groundwater and other plants areused for shallow soil contamination.
Media Treated:� Soil� Groundwater
Types of Plants Used in Phytoremediation toTreat Arsenic:� Poplar � Cottonwood� Sunflower� Indian mustard� Corn
Summary
Phytoremediation is an emerging technology. Thedata sources used for this report containedinformation on only one applications ofphytoremediation to treat arsenic at full scale andtwo at pilot scale. Experimental research intoidentifying appropriate plant species forphytoremediation is ongoing. It is generallyapplicable only to shallow soil or relatively shallowgroundwater that can be reached by plant roots. Inaddition, the phytoremediating plants mayaccumulate high levels of arsenic during thephytoremediation process, and may requireadditional treatment prior to disposal.
O + exduatese.g., CH C OOH
23
DegradationRoot respiration
CO + H O2 2
Mineralization
Uptake
Transpiration
PhloemPhotosynthesis + O
XylemH O + nutrients
2
2
PhotosynthesisDark Respiration
OrganicchemicalsC H Ozyx
Uptake (andcontaminantremoval)
Transpiration
15.0 PHYTOREMEDIATION TREATMENTOF ARSENIC
Technology Description and Principles
Phytoremediation is an emerging technology generallyapplicable only to shallow contamination that can bereached by plant roots. Phytoremediation applies to allbiological, chemical, and physical processes that areinfluenced by plants and the rhizosphere, and that aid incleanup of the contaminated substances. Phytoremediation may be applied in situ or ex situ, tosoils, sludges, sediments, other solids, or groundwater(Ref. 15.1, 15.4, 15.5, 15.7). The mechanisms ofphytoremediation include phytoextraction (also known asphytoaccumulation, the uptake of contaminants by plantroots and the translocation/accumulation of contaminantsinto plant shoots and leaves), enhanced rhizospherebiodegradation (takes place in soil or groundwaterimmediately surrounding plant roots), phytodegradation(metabolism of contaminants within plant tissues), andphytostabilization (production of chemicalcompounds by plants to immobilizecontaminants at the interface of roots andsoil). The data sources used for this reportidentified phytoremediation applications forarsenic using phytoextraction andphytostabilization.
The selection of the phytoremediatingspecies depends upon the species ability totreat the contaminants and the depth ofcontamination. Plants with shallow roots(for example, grasses, corn) are appropriateonly for contamination near the surface,typically in shallow soil. Plants with deeperroots, (for example, trees) may be capable ofremediating deeper contaminants in soil orgroundwater plumes.
Examples of vegetation used in phytoremediationinclude sunflower, Indian mustard, corn, and grasses(such as ryegrass and prairie grasses) (Ref. 15.1). Someplant species, known as hyperaccumulators, absorb andconcentrate contaminants within the plant at levelsgreater than the concentration in the surrounding soil orgroundwater. The ratio of contaminant concentration inthe plant to that in the surrounding soil or groundwateris known as the bioconcentration factor. Ahyperaccumulating fern (Pteris vittata) has been used inthe remediation of arsenic-contaminated soil, waste, andwater. The fern can tolerate as much as 1,500 parts permillion (ppm) of arsenic in soil, and can have a bioconcentration factor up to 265. The arsenicconcentration in the plant can be as high as 2 percent(dry weight) (Ref. 15.3, 15.6).
15-2
2
1
4
0 1 2 3 4
Bench
Pilot
Full
Factors Affecting PhytoremediationPerformance
� Contaminant depth - The treatment depth islimited to the depth of the plant root system(Ref. 15.5).
� Contaminant concentration - Sites with lowto medium level contamination within the rootzone are the best candidates forphytoremediation processes (Ref. 15.4, 15.5). High contaminant concentrations may be toxicto the remediating flora.
� Climatic or seasonal conditions - Climaticconditions may interfere or inhibit plantgrowth, slow remediation efforts, or increasethe length of the treatment period (Ref. 15.4).
� Contaminant form - In phytoaccumulationprocesses, contaminants are removed from theaqueous or dissolved phase. Phytoaccumulation is generally not effective oncontaminants that are insoluble or stronglybound to soil particles.
� Agricultural factors - Factors that affect plantgrowth and health, such as the presence ofweeds and pests, and ensuring that plantsreceive sufficient water and nutrients will affectphytoremediation processes.
Media and Contaminants Treated
Phytoremediation has been applied to contaminants fromsoil, surface water, groundwater, leachate, and municipaland industrial wastewater (Ref. 15.4). In addition toarsenic, examples of pollutants it can potentially addressinclude petroleum hydrocarbons such as benzene,toluene, ethylbenzene, and xylenes (BTEX), polycyclicaromatic hydrocarbons (PAHs), pentachlorophenol,polychlorinated biphenyls (PCBs), chlorinated aliphatics(trichloroethylene, tetrachloroethylene, and 1,1,2,2-tetrachloroethane), ammunition wastes (2,4,6-trinitrotoluene or TNT, and RDX), metals (lead,cadmium, zinc, arsenic, chromium, selenium), pesticidewastes and runoff (atrazine, cyanazine, alachlor),radionuclides (cesium-137, strontium-90, and uranium),and nutrient wastes (ammonia, phosphate, and nitrate)(Ref. 15.7).
Type, Number, and Scale of Identified ProjectsTreating Soil, Waste, and Water Containing Arsenic
The data sources used for this report containedinformation on phytoremediation of arseniccontaminated soil at full scale at one Superfund site (Ref.15.7). Two pilot-scale applications and four bench-scaletests were also identified (Ref. 15.2, 15.3, 15.7-11). Figure 15.1 shows the number of identified applicationsat each scale.
Figure 15.1Scale of Identified Phytoremediation Projects for
Arsenic Treatment
Summary of Performance Data
Table 15.1 provides a performance summary of theidentified phytoremediation projects. Data on the effectof phytoremediation on the leachability of arsenic fromsoil were not identified. Where available, Table 15.1provides total arsenic concentrations prior to and
following phytoremediation treatment. However, noprojects with arsenic concentrations in the treated soil,waste, and water both prior to and after treatment wereidentified. Bioconcentration factors were available forone pilot- and two bench-scale studies, and ranged from8 to 320.
Applicability, Advantages, and Potential Limitations
Phytoremediation is conducted in situ and thereforedoes not require soil excavation. In addition,revegetation for the purpose of phytoremediation alsocan enhance restoration of an ecosystem (Ref. 15.5).This technology is best applied at sites with shallowcontamination. If phytostabilization is used, thevegetation and soil may require long-term maintenanceto prevent re-release of the contaminants. Plant uptakeand translocation of metals to the aboveground portionsof the plant may introduce them into the food chain ifthe plants are consumed (Ref. 15.5). Products couldbioaccumulate in animals that ingest the plants (Ref.15.4). In addition, the toxicity and bioavailability ofcontaminants absorbed by plants and phytodegradationproducts is not always known.
Concentrations of contaminants in hyperaccumulatingplants are limited to a maximum of about 3% of the
15-3
Factors Affecting Phytoremediation Costs
� Number of crops grown - A greater numberof crops may decrease the time taken forcontaminants to be remediated to specifiedgoals, thereby decreasing costs (Ref. 15.2). However, the number of crops grown will belimited by the length of the growing season, thetime needed for crops to reach maturity, thepotential for multiple crops to deplete the soilof nutrients, climatic conditions, and otherfactors.
� Factors affecting phytoremediationperformance - Items in the �Factors AffectingPhytoremediation Performance� box will alsoaffect costs.
plant weight on a dry weight basis. Based on thislimitation, for fast-growing plants, the maximum annualcontaminant removal is about 400 kg/hectare/year. However, many hyperaccumulating species do notachieve contaminant concentrations of 3%, and are slowgrowing. (Ref. 15.12)
The case study at the end of this section further discussesan application of phytoremediation to the treatment toarsenic-contaminated soil. Information for this project issummarized in Table 15.1, Project 1.
Summary of Cost Data
Cost data specific to phytoremediation of arsenic werenot identified. The estimated 30-year costs (1998dollars) for remediating a 12-acre lead site were$200,000 for phytoextraction (Ref. 15.15). Costs wereestimated to be $60,000 to $100,000 usingphytoextraction for remediation of one acre of20-inch-thick sandy loam (Ref. 15.14). The cost ofremoving radionuclides from water with sun-flowers hasbeen estimated to be $2 to $6 per thousand gallons ofwater (Ref. 15.16). Phytostabilization system costs havebeen estimated at $200 to $10,000 per hectare,equivalent to $0.02 to $1.00 per cubic meter of soil,assuming a 1-meter root depth (Ref. 15.17).
References
15.1 U.S. EPA. Treatment Technologies for SiteCleanup: Annual Status Report (Tenth Edition). Office of Solid Waste and Emergency Response. EPA-542-R-01-004. February 2001.http://www.epa.gov/ncepi/Catalog/EPA542R01004.html
15.2 Cost and Performance Case Study.Phytoremediation at Twin Cities ArmyAmmunition Plant Minneapolis-St.Paul,Minnesota. Federal Remediation TechnologiesRoundtable (FRTR).http://www.frtr.gov/costperf.htm.
15.3 Ma LQ, Komar KM, Tu C, Zhang WH, Cai Y,Kennelly ED. A fern that hyperaccumulatesarsenic. Nature 409:579. February 2001.http://www.ifas.ufl.edu/~qma/PUBLICATION/Nature.pdf
15.4 Federal Remediation Technologies ScreeningMatrix and Reference Guide Version 3.0. FRTR. http://www.frtr.gov/matrix2/top_page.html
15.5 U.S. EPA. Introduction to Phytoremediation.National Risk Management ResearchLaboratories. Office of Research andDevelopment. EPA 600-R-99-107. February2000. http://www.clu-in.org/download/remed/introphyto.pdf
15.6 Zhang W, Cai Y, Tu C, Ma LQ. Speciation andDistribution of Arsenic in an ArsenicHyperaccumulating Plant. Biogeochemistry ofEnvironmentally Important Elements. SymposiaPapers Presented Before the Division ofEnvironmental Chemistry. American ChemicalSociety. San Diego, CA. April 1-5, 2001.
15.7 Schnoor JL. Phytoremediation. TechnologyEvaluation Report. Prepared for Ground-WaterRemediation Technologies Analysis Center(GWRTAC). 1997. http://www.gwrtac.org/html/tech_eval.html#PHYTO
15.8 U.S. EPA. Phytoremediation Resource Guide. Office of Solid Waste and Emergency Response. EPA 542-B-99-003. June 1999.http://www.clu-in.org/download/remed/phytoresguide.pdf
15.9 Compton A, Foust RD, Salt DA, Ketterer ME. Arsenic Accumulation in Potomogetonillinoiensis in Montezuma Well, Arizona.Biogeochemistry of Environmentally ImportantElements. Symposia Papers Presented Beforethe Division of Environmental Chemistry.American Chemical Society. San Diego, CA. April 1-5, 2001.
15.10 Redwine JC. Innovative Technologies forRemediation of Arsenic in Soil andGroundwater. Southern Company Services, Inc.
15.11 Qian JH, Zayed A, Zhu YL, Yu M, Terry N. Phytoaccumulation of Trace Elements byWetland Plants: III. Uptake and Accumulationof Ten Trace Elements by Twelve Plant Species. Journal of Environmental Quality. 1999.
15.12 Lasat, M. The Use of Plants for the Removal ofToxic Metals from Contaminated Soil. American Association for the Advancement ofScience.
15-4
15.13 Lasat, M. Phytoextraction of Toxic Metals: Areview of Biological Mechanisms. J. of Environ.Qual. 31:109-120. 2002.
15.14 Salt, D. E., M. et al. Phytoremediation: A NovelStrategy for the Removal of Toxic Metals fromthe Environment Using Plants. Biotechnol.13:468-474. 1995.
15.15 Cunningham, S. D. The Phytoremediation of SoilsContaminated with Organic Pollutants: Problemsand Promise. International PhytoremediationConference. May 8-10. Arlington, VA. 1996.
15.16 Dushenkov, S., D. et al.. Removal of Uraniumfrom Water Using Terrestrial Plants. Environ, Sci.Technol. 31(12):3468-3474. 1997.
15.17 Cunningham, S. D., and W. R. Berti, and J. W.Huang. Phytoremediation of Contaminated Soils.Trends Biotechnol. 13:393-397. 1995.
Tab
le 1
5.1
Ars
enic
Phy
tore
med
iatio
n T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic
15-5
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
ale
Site
Nam
e or
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
ic
Con
cent
ratio
nB
ioco
ncen
trat
ion
Fact
orR
emed
iatin
gFl
ora
Sour
ce1
Min
ing
Dee
p so
ilFu
llW
hite
woo
d C
reek
Supe
rfun
d Si
te, S
D1,
000
mg/
kgPe
rfor
man
ce d
ata
not a
vaila
ble
due
to d
eath
of
rem
edia
ting
flora
.
Hyb
rid p
opla
r(s
peci
ficva
riety
not
iden
tifie
d)
15.7
2M
uniti
ons
Man
ufac
turin
g/S
tora
ge
Surf
ace
soil
Pilo
tTw
in C
ities
Arm
yA
mm
uniti
on P
lant
, Site
C a
nd S
ite 1
29-3
,M
inne
apol
is-S
t. Pa
ul,
MN
----
--C
orn
(spe
cific
varie
ty n
otid
entif
ied)
, w
hite
mus
tard
(Sin
apis
alb
a)
15.2
3--
Gro
undw
ater
(ex
situ
)Pi
lot
Mon
tezu
ma
Wel
l, A
Z10
0 m
g/L
(Wel
lw
ater
)4.
59 m
g/kg
(sho
ots)
8.87
mg/
kg(r
oots
)
8Po
tom
oget
onill
inoi
ensi
s15
.9
4--
Surf
ace
soil
Ben
ch--
650
--20
- 75
(lea
ves)
Mos
s ver
bena
(V. t
enui
sect
a)15
.10
----
60 -
320
(sho
ots)
Saw
pal
met
to(S
. rep
ens)
5W
ood
Pres
ervi
ngSu
rfac
e so
ilB
ench
FL40
0--
265
Bra
ke fe
rn(P
teri
s vitt
ata)
15.3
6--
Soil
Ben
chEa
st P
alo
Alto
, CA
----
--Ta
mar
isk
(Tam
arix
ram
osis
sim
a),
Euca
lypt
us
15.8
7--
Soil
Ben
ch--
--34
mg/
kg(s
hoot
s)17
7 m
g/kg
(roo
ts)
--W
ater
lettu
ce(P
istia
stra
tiote
s)
15.1
1
16 - 1
Summary
Biological treatment designed to remove arsenicfrom soil, waste, and water is an emergingremediation technology. The information sourcesused for this report identified a limited number ofprojects treating arsenic biologically. Arsenic wasreduced to below 0.050 mg/L in one pilot-scaleapplication. This technology promotesprecipitation/coprecipitation of arsenic in water orleaching of arsenic in soil and waste. The leachatefrom bioleaching requires additional treatment forarsenic prior to disposal.
Technology Description: Biological treatment ofarsenic is based on the theory that microorganisms that act directly on arsenic species or create ambientconditions that cause arsenic to precipitate/coprecipitate from water and leach from soil andwaste.
Media Treated:• Soil• Waste• Water
Microbes Used:• Sulfate-reducing bacteria• Arsenic-reducing bacteria
Effluent
Packedmedia andmicrobes
Influent
Effluent
Packedmedia andmicrobes
Influent
Model of a Biological Treatment System
16.0 BIOLOGICAL TREATMENT FORARSENIC
Technology Description and Principles
Although biological treatments have usually beenapplied to the degradation of organic contaminants,some innovative techniques have applied biologicalremediation to the treatment of arsenic. Thistechnology involves biological activity that promotesprecipitation/coprecipitation of arsenic from water andleaching of arsenic in soil and waste.
Biological precipitation/coprecipitation processesforwater create ambient conditions intended to causearsenic to precipitate/coprecipitate or act directly onarsenic species to transform them into species that aremore amenable to precipitation/coprecipitation. Themicrobes may be suspended in the water or attached toa submerged solid substrate. Iron or hydrogen sulfidemay also be added (Ref. 16.2, 16.3, 16.4, 16.4).
One water treatment process depends upon biologicalactivity to produce and deposit iron oxides within afilter media, which provides a large surface area overwhich the arsenic can contact the iron oxides. Theaqueous solution is passed through the filter, wherearsenic is removed from solution throughcoprecipitation or adsorption to the iron oxides. Anarsenic sludge is continuously produced (Ref. 16.3).
Another process uses anaerobic sulfate-reducingbacteria and other direct arsenic-reducing bacteria toprecipitate arsenic from solution as insoluble arsenic-sulfide complexes (Ref. 16.2). The water containingarsenic is typically pumped through a packed-bedcolumn reactor, where precipitates accumulate until thecolumn becomes saturated (Ref. 16.5). The arsenic isthen stripped and the column is biologically regenerated(Ref. 16.2). Hydrogen sulfide has also been used insuspended reactors to biologically precipitate arsenicout of solution (Ref. 16.2, 16.4). These reactors requireconventional solid/liquid separation techniques forremoving precipitates.
Removal of arsenic from soil biologically via“accelerated bioleaching” has also been tested on abench scale. The microbes in this system producenitric, sulfuric, and organic acids which are intended tomobilize and remove arsenic from ores and sediments(Ref. 16.4). This biological activity also producessurfactants, which can enhance metal leaching (Ref.16.4).
Media and Contaminants Treated
Biological treatment typically uses microorganisms todegrade organic contaminants in soil, sludge, solids groundwater, and wastewaters. Biological treatment
16 - 2
3
1
1
0 1 2 3 4
Bench
Pilot
Full
Factors Affecting Biological TreatmentPerformance
• pH - pH levels can inhibit microbial growth. For example, sulfate-reducing bacteria performoptimally in a pH range of 6.5 to 8.0 (Ref.16.5).
• Contaminant concentration - High arsenicconcentrations may be toxic to microorganismsused in biological treatment (Ref. 16.1).
• Available nutrients - An adequate nutrientsupply should be available to the microbes toenhance and stimulate growth. If the initialsolution is nutrient deficient, nutrient additionmay be necessary.
• Temperature - Lower temperatures decreasebiodegradation rates. Heating may be requiredto maintain biological activity (Ref. 16.1).
• Iron concentration - For biologically-enhanced iron precipitation, iron must bepresent in the water to be treated. The optimaliron level depends primarily on the arsenicconcentration. (Ref. 16.3).
Factors Affecting Biological Treatment Costs
• Pretreatment requirements - Pretreatmentmay be required to encourage the growth of keymicroorganisms. Pretreatment can include pHadjustment and removal of contaminants thatmay inhibit microbial growth.
• Nutrient addition - If nutrient addition isrequired, costs may increase.
• Factors affecting biological treatmentperformance - Items in the “Factors AffectingBiological Treatment Performance” box willalso affect costs.
has also been used to treat arsenic in water viaprecipitation/coprecipitation and in soil throughleaching (Ref. 16.1, 16.3).
Type, Number, and Scale of Identified ProjectsTreating Soil, Waste, and Water Containing Arsenic
The data sources used for this report containedinformation on biological treatment of arsenic at fullscale at one facility, at pilot scale at three facilities, andat bench scale for one project. Figure 16.1 shows thenumber of identified applications at each scale. Anenhanced bioleaching system for treating soilcontaining arsenic has been tested at bench scale (Ref.16.4) (Table 16.1, Project 5). In addition, a biologicaltreatment system using hydrogen sulfide has been usedin a bioslurry reactor to treat arsenic at bench and pilotscales (Ref. 16.4) (Table 16.1, Project 4).
Figure 16.1Scale of Identified Biological Treatment Projects for
Arsenic
Summary of Performance Data
Table 16.1 lists the available performance data for threeprojects using biological treatment for arseniccontamination in water. Of the two projects that treatedwastewaters containing arsenic, only one had bothinfluent and effluent arsenic concentration data (Project1). The arsenic concentration was not reduced to below0.05 mg/L in this project.
One project (Project 3) treated groundwater spiked withsodium arsenite. The groundwater had naturally-occurring iron at 8 - 12 mg/L (Ref. 16.3). The initialarsenic concentration ranged from 0.075 to 0.400 mg/L,and was reduced by treatment to less than 0.050 mg/L. No data were available for the one soil bioleachingproject.
The case study at the end of this section furtherdiscusses a pilot-scale application of biologicaltreatment to arsenic-contaminated groundwater. Information for this project is summarized in Table16.1, Project 3.
Applicability, Advantages, and Potential Limitations
A variety of arsenic-contaminated soil, waste, and watercan be treated using biological processes. Biologicaltreatment of arsenic may produce less sludge thanconventional ferric arsenic precipitation (Ref. 16.2). Ahigh concentration of arsenic could inhibit biologicalactivity (Ref. 16.1, 16.2).
16 - 3
Case Study: Sodium Arsenite SpikedGroundwater, Forest Row, Sussex, UnitedKingdom
Groundwater with naturally-occurring iron between8 and 12 mg/L was extracted in Forest Row,Sussex, England and spiked with sodium arsenite. The arsenic concentration before treatment rangedfrom 0.075 to 0.400 mg/L in the untreated water. The spiked groundwater was passed through a pilotbiological filtration unit, 3 m high with a 15 cmdiameter and filled to 1 m with silica sand. Thearsenic concentration was reduced to <0.04 mg/L(Ref. 16.3) (see Project 3, Table 16.1).
Summary of Cost Data
The reported costs for biological treatment of arsenic-contaminated soil, waste, and water range from lessthan $0.50 to $2.00 per 1,000 gallons (Ref. 16.2, 16.4,cost year not provided).
References
16.1 Remediation Technologies Reference Guide andScreening Manual, Version 3.0. FederalRemediation Technologies Roundtable.http://www.frtr.gov/matrix2/top_page.html.
16.2 Applied Biosciences. June 28, 2001.http://www.bioprocess.com
16.3 Use of Biological Processes for ArsenicRemoval. June 28, 2001. http://www.saur.co.uk/poster.html
16.4 Center for Bioremediation at Weber StateUniversity. Arsenic Treatment Technologies.August 27, 2001. http://www.weber.edu/Bioremediation/arsenic.htm
16.5 Tenny, Ron and Jack Adams. Ferric SaltsReduce Arsenic in Mine Effluent by CombiningChemical and Biological Treatment. August 27,2001. http://www.esemag.com/0101/ferric.html
Tab
le 1
6.1
Bio
logi
cal T
reat
men
t Per
form
ance
Dat
a fo
r A
rsen
ic
16 -
4
Proj
ect
Num
ber
Indu
stry
or
Site
Typ
eW
aste
or
Med
iaSc
ale
Site
Nam
eor
Loc
atio
nIn
itial
Ars
enic
Con
cent
ratio
nFi
nal A
rsen
icC
once
ntra
tion
Prec
ipita
teA
rsen
icC
once
ntra
tion
Bio
logi
cal P
roce
ssSo
urce
1--
Was
tew
ater
Full
----
<0.0
5 m
g/L
--R
educ
tion
and
prec
ipita
tion
from
sulfa
tere
duci
ng b
acte
ria a
nddi
rect
ars
enic
-red
ucin
gba
cter
ia
16.2
2--
Was
tew
ater
Pilo
t--
13 m
g/L
<0.5
mg/
L--
Ana
erob
ic su
lfate
-re
duci
ng b
acte
ria w
ith a
tw
o-st
age
reac
tor,
arse
nic
prec
ipita
tion
and
colu
mn
syst
em
16.1
3--
Gro
undw
ater
spik
ed w
ithso
dium
ars
enite
Pilo
t--
0.07
5 - 0
.400
mg/
L0.
010
- 0.0
40m
g/L
--B
iolo
gica
l filt
ratio
n w
here
mic
robi
al a
ctiv
itypr
oduc
es ir
on o
xide
s for
copr
ecip
itatio
n or
adso
rptio
n of
ars
enic
16.3
4–
Gro
undw
ater
Pilo
t–
––
--Pr
ecip
itatio
n of
ars
enic
sulfi
des u
sing
hyd
roge
nsu
lfide
in a
bio
reac
tor
syst
em
16.4
5–
Ore
s and
sedi
men
tsB
ench
––
–--
Enha
nced
bio
leac
hing
syst
em u
sing
mic
robi
al-
gene
rate
d ac
ids t
oac
cele
rate
ani
on a
ndca
tion
rem
oval
from
ore
san
d se
dim
ents
16.4
mg/
L =
Mill
igra
m p
er li
ter
-- =
Not
ava
ilabl
e