Pilot‐scale studies of Hexavalent Chromium Removal from drinking water

Abstract

The goal of this research was the initial evaluation of several pilot‐scale treatment technologies for hexavalent chromium removal to <5 μg/L (i.e., 95% removal). A major focus was to assess manufacturer‐provided pilot systems with media that were effective in bench‐scale studies as well as technologies that were promising but could not be appropriately tested at bench scale. The technologies tested included ion exchange systems (i.e., column strong‐base and weak‐base anion exchange and reactor‐based strong‐base anion exchange), a reduction/filtration unit using sodium sulfite, and proprietary adsorptive media systems (zeolite and granular activated carbon). In vendor‐independent tests, reduction with ferrous sulfate, coagulation, and filtration was also evaluated. Regeneration efficiency was determined for the best‐performing strong‐base anion exchange resin, including the effect of recycling brine to minimize residuals. Technologies able to consistently treat to concentrations <5 μg/L included column strong‐base anion exchange, weak‐base anion exchange, and reduction–coagulation–filtration using ferrous sulfate.