BIOLOGICAL REDUCTION OF HEXAVALENT CHROMIUM IN A LEACHATE FROM VARGÖN ALLOYS AB
Anaerobic biological treatment has proven to be a successful method for reducing Cr(VI) in a leachate from Vargön Alloys AB. Influent chromium concentrations ranged from 10-120 mg/L and satisfactory reduction was achieved in both laboratory and pilot plant studies, as long as sufficient amounts of electron donor were added. Glucose, acetic acid and sulfite evaporator condensate were tested as electron donors. In a biofilm process with suspended carriers, reduction of Cr(VI) to effluent concentrations <0.03 mg/L was obtained at volumetric loads of 195 mg Cr(VI)/L,d (30°C), 170 mg Cr(VI)/L,d (20°C) and 125 mg Cr(VI)/L,d (10°C). Start-up periods were found to be short and satisfactory reduction of Cr(VI) was regained rapidly after perturbations.