AWWA JAW62637

Total chromium-Cr(III) and hexavalent chromium [Cr(VI)]- have been regulated by national drinking water regulations since 1975. The federal maximum contaminant level (MCL) for total Cr is set at 100 µg/L, and the California MCL is 50 µg/L. Increasing public concern about Cr(VI) in drinking water supplies, a California state mandate to establish a Cr(VI)-specific MCL, and the potential for stricter regulations at both the federal and California levels have sparked interest in cost-effective treatment technologies that can remove Cr(VI) to low µg/L concentrations. This research evaluated the performance of five vendor-provided technologies to identify an effective treatment option for demonstration-scale testing. The systems included strong-base anion and weak-base anion exchange columns, strong-base anion exchange and granular activated carbon columns, magnetized ion exchange using a continuous reactor, zeolite adsorptive media, and reduction with sodium bisulfite or sodium sulfite followed by filtration. The pilot testing identified several effective treatment options, all of which have the potential for removing Cr(VI) from drinking water to concentrations below or even far below the 5- µg/L goal of this research. Previous studies focused on reduction of Cr(VI) to levels 10-1,000 times greater than those targeted by this testing. If a low MCL is promulgated for Cr(VI) or consumers become concerned about drinking water with elevated concentrations, water utility managers now have treatment options to consider that effectively reduce Cr(VI) to low levels. Includes 21 references, tables, figures.