Biodegradation kinetics of Cr (VI) by acclimated mixed culture

Abstract

Chromium was discovered in 1797 by Vauquelin. Numerous industrial applications raised chromium to a very important economic element. At the same time, with the development of its uses, the adverse effects of chromium compounds in human health were being investigated. Both acute and chronic toxicity of chromium are mainly caused by hexavalent compounds. It is highly toxic in nature and causes adverse effects on human beings. The present study deals with the removal of hexavalent chromium compound from industrial waste water using biodegradation by an acclimated mixed culture developed from activated sludge. The biodegradation studies are conducted for an initial Cr(VI) concentration ranging from 10-50 mg/L. The enrichment of culture is carried out for a period of 7 days. In these experiments, 100 mL of minimum salt medium (MSM) is autoclaved and added with known amount of acclimated mixed culture obtained from the enrichment procedure. Known amount of Cr(VI) is added in autoclaved MSM to maintain the required concentration of Cr(VI). The flasks are kept in the rotary shaker which is maintained at 37 C and at 150 rpm throughout the biodegradation process. The samples are collected at different intervals. The obtained biomass growth is significant and indicate the considerable decrease in Cr(VI) concentration in the solution The biodegradation rate kinetic parameters are obtained for zero order and three and half order kinetic models.