Reduction capabilities of microbial Cr(VI) in anaerobic environment

The changes of Cr(Ⅵ) and Fe(Ⅱ) concentration were measured during Co-culture experiment and slurry experiments.The microbial reducing ability of different chromate concentrations and the effect of chromate on dissimilatory iron reduction in paddy soil were investigated.The result indicated that,although microorganism from paddy soil could directly reduce Cr(Ⅵ),the reduecing rate and efficiency were limited;the higher Cr(Ⅵ) concentration was,the less reducing ability the microbial showed;the microbe from different paddy soils had different effects on Cr(Ⅵ) reducing abilities;The reducing ability of the microbe from Sichuan paddy soil was higher than that from Jiangxi paddy soil.Cr(Ⅵ) added could be rapidly reduced in paddy soil under anaerobic incubation,moreover,the process of dissimilatory iron reduction of soil could obviously promote the Cr(Ⅵ) reduction.The existent of Cr(Ⅵ) could delay the appearance of Fe(Ⅱ);the higher Cr(Ⅵ) concentration was,the later Fe(Ⅱ) appeared.The delayed time of Fe(Ⅱ) appearance was in accordance with the ending time of Cr(Ⅵ) reduction.