AWWA WKICO66062

This powerpoint presentation begins by introducing a case study of Cr(VI) at Glendale, California. The methods for analyzing contaminant removal processes are examined and include: XRF, XRD, SEM, chemical tests, XAFS, leaching procedures. Treatment implications from analytical results included: low pH is necessary for maximizing Cr(VI) capacity on WBA resins (but not SBA resins) - protonation of amine group, less OH- competition, HCrO₄<sup>-M/sup> speciation; Cr(VI) is reduced to Cr(III) by the two WBA resins, perhaps after being adsorbed; Cr is not retained on the resins in the form of small precipitates - added stability; lack of crystalline solids suggests another electron donor perhaps part of the ion exchange functional groups or the backbone of the resin material; other elements are simultaneously removed by the WBA resins, such as U, V, and Cu - may limit operational life. Disposal options for treatment residuals are listed, along with TCLP Results, CWET Results, and Total Uranium Results. Summary and Conclusions: mechanism of WBA resin treatment involves reduction of Cr(VI) to Cr(III); no evidence of crystalline Cr(III) precipitates on the resins; WBA resins likely to be classified as non-hazardous waste by federal standards and hazardous waste by California standards; and, uranium accumulation may limit useful operational life of one resin rather than capacity. Includes tables, figures.