Chromium removal from strong base anion exchange waste brines

Abstract

Regeneration of strong base anion exchange (SBA-IX) resin produces concentrated and hazardous brine. One alternative regenerant and two brine treatment options were investigated to reduce the hazardous characteristics of the brine. These included replacing sodium chloride with sodium bicarbonate as regenerant; using ferrous sulfate (FeSO4) to reduce/coagulate hexavalent chromium (Cr(VI)) in the brine; and applying weak base anion exchange (WBA-IX) resin and chemical reductive media (CRM) to adsorb/reduce Cr(VI). It was found that bicarbonate was as effective as chloride in regenerating chromium-saturated resins, and the affinity of bicarbonate-form resin for chromium was similar to that of chloride-form. It was observed that ferrous sulfate applied at doses close to the stoichiometric ratio achieved near complete removal of total Cr from SBA-IX brine. In column tests, two CRM exhibited more than twenty times greater removal capacity for total Cr than the WBA-IX resins