Bioreduction of Cr(VI) using bacterial consortia isolated from a municipal wastewater sludge experiencing Cr(VI) loading from an abandoned chrome foundry

Abstract

Due to the threat posed by Cr(VI) on humans and aquatic wildlife, the removal of this metal must be applied effectively and without causing an impact on the environment. Reduction of Cr(VI) using microorganisms has been proposed as an alternative technique for remediation of both soils and groundwater, owing to its environmental friendliness and low-cost. Extensive work on Cr(VI) reduction by microorganisms has been reported, however, most of these scholars have paid attention to pure cultures. In this study, a natural consortium of microbial cultures from a municipal wastewater sludge site was used to investigate the effect of initial Cr(VI) concentration and pH on the Cr(VI) removal by the consortia. The results show that the optimised bacterial consortium was resistant to greater than 400 mg/L Cr(VI) concentration with 50 mg/L being completely removed within 4 h of incubation. The consortia exhibited considerable Cr(VI) removal efficiency in the pH range from 2 to 11, with 100% removal being achieved at a pH value of 7. This study demonstrated that bacteria the bacterial consortium from municipal wastewater sludge could be used for Cr(VI) remediation. Thus, bioremediation is a viable, environmentally friendly technology for applications in hexavalent chromium contaminated site.