AWWA ACE71025

This powerpoint presentation begins by providing a brief overview of the Cr(VI) regulatory horizon. Demonstration testing of reduction/coagulation/filtration (RCF) for hexavalent chromium removal is presented, along with residuals management and analysis. Study results indicate: ferrous sulfate reduced Cr(VI) concentrations from 100 ug/L to less than 1 ug/L within 15 minutes; aeration effectively oxidized the majority of the ferrous iron, even 6 minutes of aeration lowered ferrous concentrations to less than 0.08 mg/L; runs conducted without aeration resulted in filter effluent ferrous iron concentrations of less than 0.03 mg/L; anionic polymer was effective in floc formation and backwash water settling; passive filtration for sludge dewatering is promising for this application; and, backwash water recycle did not negatively impact the RCF process. Includes tables, figures.