Efficient reduction of Reactive Black 5 and Cr(VI) by a newly isolated bacterium of Ochrobactrum anthropi

Abstract It is important to obtain bacteria with the ability for reduction of dyes and Cr(Ⅵ) since dyes and Cr(Ⅵ) are often co-exist in textile wastewater. In this study, a new strain belonging to Ochrobactrum anthropi was isolated from textile wastewater, and could efficiently reduce Reactive Black 5 (RB 5) and Cr(Ⅵ). The results showed the degradation efficiency of RB 5 could achieve 100% and reduction efficiency of Cr(Ⅵ) was up to 80% within 3 days at initial RB 5 and Cr(Ⅵ) concentration of 400 mg/L and 20 mg/L. Mn2+ and Cu2+ could enhance the removal of RB 5 and Cr(Ⅵ), respectively. Glycerin, as electron donor, improved reduction efficiencies of RB 5 and Cr(Ⅵ). In addition, reduction mechanisms were further investigated. The results demonstrated that decreasing of RB 5 and Cr(Ⅵ) concentration were mainly through extracellular bioreduction rather than by adsorption. The FTIR and XPS analyses revealed that the O-H, C-C and C-H groups on the cell surface might be involved in the reduction of RB 5 and Cr(Ⅵ). The information gives useful insights into understanding of how the bacterium reduce RB 5 and Cr(Ⅵ). The results indicated that the strain had excellent application prospect for treating industrial wastewater.