Effects of indigenous bacteria on Cr(VI) reduction in Cr-contaminated sediment with industrial wastes

摘要

Black,clay-like sediments have been obtained from the area of the pigment manufacturing factories in Dongducheon city,Korea.These sediments were contaminated by heavy metals,especially chromium (700 mg/kg).Indigenous bacteria in the sediments were isolated to investigate their ability to reduce Cr(VI) to Cr(III).The enriched bacterial consortium reduced over 99% of dissolved Cr(VI) in 96 h from the onset of the experiments under anaerobic condition,while there was no change in Cr(VI) concentration until 300 h in abiotic controls.Total amount of dissolved Cr decreased simultaneously when Cr(VI) was reduced,which was likely due to precipitation of Cr(OH)_3 after microbial reduction of Cr(VI) to Cr(III).Under aerobic condition,only 30% of dissolved Cr(VT) was reduced by indigenous bacteria until 900 h.The reduction of Cr(VI) did not accompany bacterial growth since the amount of protein did not show a significant change with time both in the presence and absence of O_2.These indigenous bacteria may play a role in the treatment of Cr(VI)-contaminated sediments.