Comparative Analysis of Adsorptive Media Treatment for Arsenic at SRP Groundwater Wells by Dylan Lesan A Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science Approved November 2015 by the Graduate Supervisory Committee: Paul Westerhoff, Chair Matthew Fraser Kiril Hristovski ARIZONA STATE UNIVERSITY December 2015 ABSTRACT Arsenic (As) is a naturally occurring element that poses a health risk when continually consumed at levels exceeding the Environmental Protection Agencies (EPA) maximum contaminant level (MCL) of 10 ppb. With the Arizona Department of Water Resources considering reliance on other sources of water other than just solely surface water, groundwater proves a reliable, supplemental source. The Salt River Project (SRP) wants to effectively treat their noncompliance groundwater sources to meet EPA compliance. Rapid small-scale column tests (RSSCTs) of two SRP controlled groundwater wells along the Eastern Canal and Consolidated Canal were designed to assist SRP in selection and future design of full-scale packed bed adsorbent media. Main concerns for column choice is effectiveness, design space at groundwater wells, and simplicity. Two adsorbent media types were tested for effective treatment of As to below the MCL: a synthetic iron oxide, Bayoxide E33, and a strong base anion exchange resin, SBG-1. Both media have high affinity toward As and prove effective at treating As from these groundwater sources. Bayoxide E33 RSSCT performance indicated that As treatment lasted to near 60,000 bed volumes (BV) in both water sources and still showed As adsorption extending past this operation ranging from several months to a year. SBG- 1 RSSCT performance indicated As, treatment lasted to 500 BV, with the added benefit of being regenerated. At 5%, 13%, and 25% brine regeneration concentrations, regeneration showed that 5% brine is effective, yet would complicate overall design and footprint. Bayoxide E33 was selected as the best adsorbent media for SRP use in full- scale columns at groundwater wells due to its simplistic design and high efficiency. i DEDICATION I dedicate this thesis to all of those who have supported and encouraged me throughout the highs and lows in this brief—yet exhilarating—segment of my life. I thank my father for inspiring me to not only become an engineer, but the man I am today. To my mother, who wrote the book on compassion (and stress—just kidding!) and was always available to talk with me through my worries and fears. Thanks also to my brother and sister for being amazing siblings able to cope with my craziness. To the rest of my family, whom have established and reinforced the belief that family is always there, no matter what. And my final dedication extends to my grandmother who was a loving, caring woman, teaching me to reciprocate selfless love no matter the circumstances— until we meet again, may you rest in peace. ii ACKNOWLEDGMENTS I first would like to generously thank my advisor, Dr. Paul Westerhoff for trusting me in performing this research and observing my potential while I was but a nervous undergraduate looking for lab experience. You have instilled in me the wonder, fascination, and work ethic to pursue environmental engineering. I would also like to thank my other committee members, Dr. Kiril Hristovski, for the insight and joy that you brought to all Friday meetings, and Dr. Matt Fraser. I would also like to thank all my fellow researchers for being such incredible people and some of the most intelligent people I have ever met: Heather Stancl, Xiangyu Bi, David Hanigan, Mac Gifford, Justin Kidd, Heuidae Lee, Anjali Mulchandani, Natalia Fischer, Onur Apul, and to those who have long graduated and gone to pursue their careers. You all are incredible, talented, bright people and I look forward to all that each of you accomplish. I would especially like to acknowledge SRP for providing the funding that made this research and thesis possible. iii TABLE OF CONTENTS Page LIST OF TABLES ................................................................................................................... vi LIST OF FIGURES ............................................................................................................... vii CHAPTER 1 INTRODUCTION ........................................................................................................ 1 Background on Arsenic in Arizona Groundwater ..................................... 1 Arsenic Redox Chemistry ............................................................. 3 Adverse Health Effects of Arsenic Exposure ............................... 6 Salt River Projects Concern with Arsenic ................................................. 7 Adsorptive Media Treatment for Arsenic .................................. 10 Metal (Hydr)oxides ......................................................... 11 Ion Exchange Resins ...................................................... 13 Competing Species Chemistry Background .............................. 16 Vanadium Background .................................................. 17 Uranium Background ..................................................... 20 Silica Background .......................................................... 23 Sulfate Background ........................................................ 24 Carbonate Background .................................................. 26 Scope of the Thesis .................................................................................. 27 2 MATERIALS AND METHODS .............................................................................. 29 Rapid Small Scale Column Tests (RSSCT) ............................................ 29 iv CHAPTER Page Adsorbent Media Preparation ..................................................... 31 RSSCT Column Packing, Operation, and Sampling ................. 32 Bayoxide E33 Column Operation ................................ 34 SBG-1 Column Operation ............................................ 35 Groundwater Collection ........................................................................... 37 Sample Analysis ....................................................................................... 38 3 RESULTS AND DISCUSSION .............................................................................. 39 Breakthrough Curves ............................................................................... 39 Bayoxide E33 Results .............................................................................. 39 Arsenic Breakthrough Curves .................................................. 40 Silica Breakthrough Curves ...................................................... 42 Vanadium Breakthrough Curves .............................................. 44 Uranium Breakthrough Curves ................................................. 46 Bayoxide E33 Performance ...................................................... 48 SBG-1 Performance ................................................................................. 49 Arsenic and Vanadium Breakthrough Curves ......................... 50 Regeneration of SBG-1 ............................................................. 53 4 SUMMARY AND CONCLUSIONS ...................................................................... 58 Recommendation to SRP ......................................................................... 58 Future Research Considerations .............................................................. 60 REFERENCES........................................................................................................................ 62 v LIST OF TABLES Table Page 2.1 Summary of RSSCT Design Parameters and Full-Scale Column ......................... 31 2.2 SRP Groundwater Quality...................................................................................... 38 4.1 Summary of Operational Conclusions ................................................................... 60 vi LIST OF FIGURES Figure Page 1.1 Arsenic Concnetrations from Select Groundwater Wells ..................................... 2 1.2 Eh-pH Diagram for Arsenic ................................................................................... 4 1.3 Speciation Diagram of (a) Arsenite and (b) Arsenate ............................................ 5 1.4 Images of (a) 32.4E -2N Eastern Canal Groundwater Well and (b) 30.4E -2N Consolidated Canal Well .......................................................................... 8 1.5 Vanadium Eh-pH Diagram ................................................................................... 18 1.6 Speciation Diagram of Vanadium ........................................................................ 19 1.7 Eh-pH Diagram of Uranium ................................................................................. 21 1.8 Speciation Diagram of (a) Uranium and (b) Uranium Carbonate-ligands .......... 22 1.9 Silica (a) Eh-pH Diagram and (b) Speciation Diagram ....................................... 24 1.10 Sulfate (a) Eh-pH Diagram and (b) Speciation Diagram..................................... 25 1.11 Carbonate (a) Eh-pH Diagram and (b) Speciation Diagram ............................... 26 2.1 RSSCT Column Design ........................................................................................ 33 2.2 Bayoxide E33 Packed Column ............................................................................. 35 2.3 SBG-1 Packed Columns ....................................................................................... 36 3.1 Total Arsenic Breakthrough Curves for (a) Eastern Canal Groundwater and (b) Consolidated Canal Groundwater E33 RSSCTs ................................... 41 3.2 Total Silica Breakthrough Curves for (a) Eastern Canal Groundwater and (b) Consolidated Canal Groundwater E33 RSSCTs ................................... 43 vii Figure Page 3.3 Total Vanadium Breakthrough Curves for (a) Eastern Canal Groundwater and (b) Consolidated Canal Groundwater E33 RSSCTs ................................... 45 3.4 Total Uranium Breakthrough Curves for (a) Eastern Canal Groundwater and (b) Consolidated Canal Groundwater E33 RSSCTs ................................... 47 3.5 SBG-1 Virgin Resin Breakthrough Curves for (a) Eastern Canal Groundwater and (b) Consolidated Canal Groundwater .................................................... 51 3.6 SBG-1 Regeneration Cycle Comparison for Eastern Canal Groundwater at (a) 13%and (b) 25% NaCl by Weight ......................................................... 53 3.7 SBG-1 Regeneration Cycle Comparison for Consolidated Canal Groundwater at(a)5%, (b) 13%, and (c) 25% NaCl by Weight ................................... 55 viii CHAPTER 1 INTRODUCTION With increasing concern about the drought in the Colorado River Basin, the Arizona Department of Water Resources is looking towards reliance on other water sources than just surface water from the Colorado River and other rivers within Arizona. The Salt River Project (SRP) being responsible for canal systems in Phoenix and Tempe, may require increased use in groundwater that contains arsenic concentrations exceeding the Environmental Protection Agency’s (EPA) maximum contaminant level (MCL) of 10 µg/L As. Background on Arsenic in Arizona Groundwater Arsenic is the twentieth most abundant element in the earth’s crust with an average concentration of 2 mg/kg (Mohan & Pittman, 2007; U.S.EPA, 2000). These concentrations, however, vary based on the regions geologic formation with arsenic being a major component of mineral species within igneous and sedimentary rocks. Higher arsenic concentrations within groundwater in the Western and Southwestern United States is derived from a combination of sedimentary deposits typically associated with sulfide ores of copper, lead, silver and gold from mines and shale, and iron oxide media with incorporated arsenic (Spencer, 2000; U.S.EPA, 2000; Welch, Westjohn, Helsel, & Wanty, 2000). Weathering and dissolution of the sulfide minerals and microbial redox of iron oxide rocks has contributed to the elevated concentrations of arsenic within Arizona ground waters (McArthur, Ravenscroft, Safiulla, & Thirlwall, 2001). Over 800 groundwater wells from a U.S. Geological Survey were found in Arizona, with nearly 247 of these used for public drinking water; half of these drinking water wells contain 1