Hexavalent Chromium Removal Using Anion Exchange and Reduction With Coagulation and Filtration

Public concern about Cr(VI) in drinking water supplies and potential adverse health effects prompted the City of Glendale and its partners to initiate a four-phase program identifying and implementing cost-effective Cr(VI) treatment. Three effective technologies were identified from initial testing: WBA resin, regenerable SBA resin, and RCF. WBA resin was distinctive in its high Cr(VI) capacity and simplicity but was a new technology. Thus, further study was needed. The key objectives of this project included (1) conducting treatment studies to confirm the efficiencies of weak-base anion (WBA) exchange resins for hexavalent chromium [Cr(VI)] removal from groundwater; (2) characterizing WBA resin residuals to elucidate Cr(VI) removal mechanism(s); (3) investigating residuals handling and disposal options, (4) refining cost estimates of effective Cr(VI) treatment technologies, including WBA, strong-base anion (SBA) exchange resin, and reduction/coagulation/filtration (RCF); and (5) convening an expert panel to recommend treatment technologies for demonstration-scale testing. This research project tested and identified an innovative technology for Cr(VI) removal from drinking water sources. Prior to this study, no treatment technology was proven to achieve removal to low parts-per-billion levels. The research results will benefit the water industry by providing information on effective Cr(VI) treatment technologies, updated costs estimates, and treatment operational conditions. In addition, cost information developed in this study will be of use in regulatory establishment of a Cr(VI)-specific maximum contaminant level (MCL), such as that mandated by the State of California.