Cr(VI) reduction and removal from waste water in the metal processing industry

Abstract

Kverneland Group requires a reduction of Cr(VI) in their waste water and this work investigated the reduction of Cr(VI) in aqueous solution by Ferrous sulfate and elemental iron powder at range pH 12, 7 and 6. Reduction by Ferrous sulfate was possible at all pH levels with increasing efficiency at lower pH values ranging from 70% Cr(VI) remaining at 12 pH, and 17.3% remaining at pH 6. By contrast the reduction by Zero Valent Iron proved ineffective with no discernable reduction of Cr(VI) at pH values at and above 6. Lower pH levels were not able to be tested due to the production of nitrous gas at pH 5.