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

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.

Automated summary

This study isolated a new strain that efficiently reduces dyes and Cr(VI) from textile wastewater, achieving high degradation and reduction efficiencies under specific conditions. Different metal ions and electron donors play different roles in promoting the degradation process. Through further investigation, the reduction mechanisms were revealed, with specific surface groups on the bacteria involved in the reduction process.