EPA/600/R-08/005 January 2008 Arsenic Removal from Drinking Water by Iron Removal U.S. EPA Demonstration Project at Sabin, MN Six-Month Evaluation Report by Wendy E. Condit Abraham S.C. Chen Battelle Columbus, OH 43201-2693 Contract No. 68-C-00-185 Task Order No. 0029 for Thomas J. Sorg Task Order Manager Water Supply and Water Resources Division National Risk Management Research Laboratory Cincinnati, Ohio 45268 National Risk Management Research Laboratory Office of Research and Development U.S. Environmental Protection Agency Cincinnati, Ohio 45268 November 14, 2007 DISCLAIMER The work reported in this document was funded by the United States Environmental Protection Agency (EPA) under Task Order 0029 of Contract 68-C-00-185 to Battelle. It has been subjected to the Agency’s peer and administrative reviews and has been approved for publication as an EPA document. Any opinions expressed in this paper are those of the author(s) and do not, necessarily, reflect the official positions and policies of the EPA. Any mention of products or trade names does not constitute recommendation for use by the EPA. ii FOREWORD The U.S. Environmental Protection Agency (EPA) is charged by Congress with protecting the Nation’s land, air, and water resources. Under a mandate of national environmental laws, the Agency strives to formulate and implement actions leading to a compatible balance between human activities and the ability of natural systems to support and nurture life. To meet this mandate, EPA’s research program is providing data and technical support for solving environmental problems today and building a science knowledge base necessary to manage our ecological resources wisely, understand how pollutants affect our health, and prevent or reduce environmental risks in the future. The National Risk Management Research Laboratory (NRMRL) is the Agency’s center for investigation of technological and management approaches for preventing and reducing risks from pollution that threaten human health and the environment. The focus of the Laboratory’s research program is on methods and their cost-effectiveness for prevention and control of pollution to air, land, water, and subsurface resources; protection of water quality in public water systems; remediation of contaminated sites, sediments and ground water; prevention and control of indoor air pollution; and restoration of ecosystems. NRMRL collaborates with both public and private sector partners to foster technologies that reduce the cost of compliance and to anticipate emerging problems. NRMRL’s research provides solutions to environmental problems by: developing and promoting technologies that protect and improve the environment; advancing scientific and engineering information to support regulatory and policy decisions; and providing the technical support and information transfer to ensure implementation of environmental regulations and strategies at the national, state, and community levels. This publication has been produced as part of the Laboratory’s strategic long-term research plan. It is published and made available by EPA’s Office of Research and Development to assist the user community and to link researchers with their clients. Sally Gutierrez, Director National Risk Management Research Laboratory iii ABSTRACT This report documents the activities performed and the results obtained from the first six months of the EPA arsenic removal technology demonstration project at the Sabin, MN facility. The main objective of the project is to evaluate the effectiveness of Kinetico’s FM-248-AS arsenic removal system using Macrolite® media in removing arsenic to meet the new arsenic maximum contaminant level (MCL) of 10 μg/L. Additionally, this project evaluates (1) the reliability of the treatment system for use at small water facilities, (2) the required system operation and maintenance (O&M) and operator skill levels, and (3) the cost-effectiveness of the technology. The project also characterizes water in the distribution system and residuals generated by the treatment process. The types of data collected include system operation, water quality (both across the treatment train and in the distribution system), process residuals, and capital and O&M costs. After engineering plan review and approval by the state, the FM-248-AS treatment system was installed and became operational on January 19, 2006. The system consisted of two 63-in-diameter, 86-in-tall fiberglass reinforced plastic (FRP) contact tanks and two 48-in-diameter, 72-in-tall FRP pressure tanks, all configured in parallel. Each pressure tank contained 25 ft3 of Macrolite® media, which is a spherical, low density, chemically inert ceramic media designed for filtration rates up to 10 gal/min (gpm)/ft2. The system used prechlorination to oxidize As(III) and Fe(II) and the contact tank to improve the formation of As(V)-laden particles prior to entering the pressure filters. The system operated at approximately 238 gpm for 3.0 hr/day (on average), producing 6,650,000 gal of water through July 30, 2006. The average flowrate corresponded to a contact time of 7.1 min and a filtration rate of 9.5 gpm/ft2. A number of issues related to the control of the frequency and duration of backwash operation were experienced as discussed in the report. The source water had an average pH of 7.4 and total arsenic concentrations ranged from 32.8 to 49.8 μg/L, with the soluble fraction consisting of As(V) at 23.9 μg/L and As(III) at 13.2 μg/L. Concentrations of both As(V) and As(III) varied considerably during the course of this six-month study period, with As(III) concentrations exhibiting a decreasing trend and As(V) concentrations exhibiting an increasing trend especially during the first month. Total iron concentrations ranged from 1,203 to 1,936 μg/L, which existed primarily in the soluble form with an average concentration of 1,135 μg/L. Raw water soluble iron and soluble arsenic concentrations corresponded to a ratio of 31:1. Total arsenic concentrations in treated water averaged 6.3 μg/L and ranged from 3.5 to 10.6 μg/L. Due to total arsenic breakthrough at 10.6 μg/L on July 26, 2006, a run length study will be conducted during the next six- month period. Comparison of the distribution system sampling results before and after the second quarter of operations demonstrated a considerable decrease in arsenic (27.4 to 7.1 μg/L), iron (1,211 to 75 μg/L), and manganese (114 to 60 μg/L). Further decreases were observed in manganese concentrations within the distribution system, when compared to the concentrations in the filter effluent (i.e., 203 and 217 [on average] following Tanks A and B) to those in the distribution system (i.e., 60 μg/L [on average] in the second quarter of system operation). Copper (179 to 127 μg/L) and lead concentrations (4.2 to 1.3 μg/L) also decreased. Alkalinity and pH did not appear to be significantly affected. Filter tank backwash occurred automatically about 3 times/tank/week, which was triggered primarily by the 48-hr standby time setpoint, due to low operational time of the treatment system (i.e., 3.0 hrs/day). Approximately 161,550 gal of wastewater, or 2.4% of the amount of water treated, was generated during the first six months. Under normal operating conditions, the backwash wastewater contained 116 to 550 mg/L of total suspended solids (TSS), 29.8 to 176.8 mg/L of iron, 2.0 to 8.6 mg/L of manganese, and iv 6.1 to 27.6 μg/L of arsenic, with the majority existing as particulates. The average amount of solids discharged per backwash cycle was approximately 5.2 lb, including 1.6 lb of elemental iron, 0.09 lb of elemental manganese, and 0.01 lb of elemental arsenic. The capital investment for the system was $287,159, consisting of $160,875 for equipment, $49,164 for site engineering, and $77,120 for system installation, shakedown, and startup. Using the system’s rated capacity of 250 gpm (or 360,000 gal/day [gpd]), the capital cost was $1,149/gpm or $0.80/gpd. This calculation does not include the cost of the building to house the treatment system. The estimated O&M costs included chemical supply and labor. O&M costs were estimated at $0.69/1,000 gal and will be refined at the end of the one-year evaluation period. v CONTENTS DISCLAIMER..............................................................................................................................................ii FOREWORD...............................................................................................................................................iii ABSTRACT.................................................................................................................................................iv APPENDICES............................................................................................................................................vii FIGURES....................................................................................................................................................vii TABLES....................................................................................................................................................viii ABBREVIATIONS AND ACRONYMS....................................................................................................ix ACKNOWLEDGMENTS...........................................................................................................................xi 1.0 INTRODUCTION.................................................................................................................................1 1.1 Background...................................................................................................................................1 1.2 Treatment Technologies for Arsenic Removal.............................................................................2 1.3 Project Objectives.........................................................................................................................2 2.0 SUMMARY AND CONCLUSIONS....................................................................................................5 3.0 MATERIALS AND METHODS...........................................................................................................7 3.1 General Project Approach.............................................................................................................7 3.2 System O&M and Cost Data Collection.......................................................................................8 3.3 Sample Collection Procedures and Schedules............................................................................10 3.3.1 Source Water.................................................................................................................10 3.3.2 Treatment Plant Water...................................................................................................10 3.3.3 Backwash Water............................................................................................................10 3.3.4 Distribution System Water............................................................................................10 3.3.5 Residual Solids..............................................................................................................10 3.4 Sampling Logistics.....................................................................................................................10 3.4.1 Preparation of Arsenic Speciation Kits..........................................................................10 3.4.2 Preparation of Sampling Coolers...................................................................................12 3.4.3 Sample Shipping and Handling.....................................................................................12 3.5 Analytical Procedures.................................................................................................................12 4.0 RESULTS AND DISCUSSION..........................................................................................................13 4.1 Facility Description....................................................................................................................13 4.1.1 Source Water Quality....................................................................................................13 4.1.2 Distribution System and Treated Water Quality...........................................................18 4.2 Treatment Process Description...................................................................................................18 4.3 Treatment System Installation....................................................................................................21 4.3.1 System Permitting..........................................................................................................22 4.3.2 Building Construction....................................................................................................22 4.3.3 System Installation, Startup, and Shakedown................................................................22 4.4 System Operation.......................................................................................................................24 4.4.1 Coagulation/Filtration Operation...................................................................................24 4.4.2 Backwash Operation......................................................................................................27 4.4.2.1 Backwash Frequency Issues..........................................................................27 4.4.2.2 Backwash Duration Issues............................................................................27 4.4.2.3 Backwash Alarms..........................................................................................28 4.4.3 Residual Management...................................................................................................28 4.4.4 Reliability and Simplicity of Operation.........................................................................28 4.4.4.1 Pre- and Post-Treatment Requirements.........................................................28 vi 4.4.4.2 System Automation.......................................................................................29 4.4.4.3 Operator Skill Requirements.........................................................................29 4.4.4.4 Preventative Maintenance Activities.............................................................29 4.4.4.5 Chemical Handling and Inventory Requirements.........................................29 4.5 System Performance...................................................................................................................29 4.5.1 Treatment Plant Sampling.............................................................................................30 4.5.1.1 Arsenic..........................................................................................................30 4.5.1.2 Iron................................................................................................................34 4.5.1.3 Manganese.....................................................................................................36 4.5.1.4 pH, DO, and ORP..........................................................................................38 4.5.1.5 Chlorine and Ammonia.................................................................................38 4.5.1.6 Other Water Quality Parameters...................................................................38 4.5.2 Backwash Water Sampling............................................................................................38 4.5.3 Distribution System Water Sampling............................................................................39 4.6 System Cost................................................................................................................................39 4.6.1 Capital Cost...................................................................................................................39 4.6.2 O&M Cost.....................................................................................................................41 5.0 REFERENCES....................................................................................................................................43 APPENDICES APPENDIX A: OPERATIONAL DATA................................................................................................A-1 APPENDIX B: ANALYTICAL DATA TABLES..................................................................................B-1 FIGURES Figure 3-1. Process Flow Diagram and Sampling Schedule and Locations...........................................11 Figure 4-1. Preexisting Pump House at Sabin, MN................................................................................14 Figure 4-2. Preexisting Filtration System at Sabin, MN.........................................................................14 Figure 4-3. Water Tower at Sabin, MN..................................................................................................15 Figure 4-4. Schematic of Kinetico’s FM-248-AS Arsenic Removal System.........................................20 Figure 4-5. Treatment System Components...........................................................................................20 Figure 4-6. New Building and Associated Infrastructure.......................................................................23 Figure 4-7. Delivery and Off-Loading of Macrolite® Treatment System Equipment............................23 Figure 4-8. Calculated and Instantaneous Flowrate Readings................................................................26 Figure 4-9. Differential Pressure Versus Filter Run Time......................................................................26 Figure 4-10. Total Arsenic Concentrations Across Treatment Train........................................................34 Figure 4-11. Arsenic Speciation Results at Wellhead (IN), after Contact Tank (AC), after Tank A (TA), and after Tank B (TB)...................................................................................35 Figure 4-12. Total Iron Concentrations Across Treatment Train.............................................................36 Figure 4-13. Total Manganese Concentrations Across Treatment Train..................................................37 Figure 4-14. Total Manganese Concentrations Versus Total Chlorine Residuals....................................37 vii TABLES Table 1-1. Summary of the Arsenic Removal Demonstration Sites........................................................3 Table 3-1. Predemonstration Study Activities and Completion Dates....................................................7 Table 3-2. Evaluation Objectives and Supporting Data Collection Activities........................................8 Table 3-3. Sampling Schedule and Analyses..........................................................................................9 Table 4-1. Water Quality Data at Sabin, MN........................................................................................16 Table 4-2. Physical Properties of 40/60 Mesh Macrolite® Media.........................................................18 Table 4-3. Design Features of Macrolite® Arsenic Removal System....................................................21 Table 4-4. FM-248-AS Treatment System Operational Parameters.....................................................25 Table 4-5. Summary of PLC Settings for Backwash Operations..........................................................28 Table 4-6. Summary of Arsenic, Iron, and Manganese Results............................................................31 Table 4-7. Summary of Other Water Quality Parameter Results..........................................................32 Table 4-8. Backwash Water Sampling Results.....................................................................................40 Table 4-9. Distribution System Sampling Results.................................................................................40 Table 4-10. Capital Investment for Kinetico’s FM-248-AS System.......................................................41 Table 4-11. O&M Costs for Kinetico’s FM-248-AS System..................................................................42 viii ABBREVIATIONS AND ACRONYMS ∆p differential pressure AAL American Analytical Laboratories Al aluminum AM adsorptive media As arsenic ATS Aquatic Treatment Systems bgs below ground surface C/F coagulation/filtration Ca calcium Cl chlorine CRF capital recovery factor Cu copper DO dissolved oxygen EPA U.S. Environmental Protection Agency F fluoride Fe iron FedEx Federal Express FRP fiberglass reinforced plastic gpd gallons per day gpm gallons per minute HIX hybrid ion exchanger hp horsepower ICP-MS inductively coupled plasma-mass spectrometry ID identification IX ion exchange LCR (EPA) Lead and Copper Rule MCL maximum contaminant level MDH Minnesota Department of Health MDL method detection limit MEI Magnesium Elektron, Inc. Mg magnesium μm micrometer Mn manganese MPCA Minnesota Pollution Control Agency mV millivolts Na sodium ix NA not analyzed NaOCl sodium hypochlorite ND not detected NS not sampled NTU nephelometric turbidity units O&M operation and maintenance OIP operator interface panel OIT Oregon Institute of Technology ORD Office of Research and Development ORP oxidation-reduction potential P&ID piping and instrumentation diagram Pb lead pCi/L picocuries per liter psi pounds per square inch psig pounds per square inch gauge PLC programmable logic controller PO orthophosphate 4 POU point-of-use PVC polyvinyl chloride QA quality assurance QA/QC quality assurance/quality control QAPP Quality Assurance Project Plan Ra radium RPD relative percent difference RO reverse osmosis Sb antimony SDWA Safe Drinking Water Act SiO silica 2 SMCL secondary maximum contaminant level SO sulfate 4 STS Severn Trent Services TBD to be determined TDS total dissolved solids TOC total organic carbon TSS total suspended solids UPS uninterruptible power supply V vanadium x