Key Laboratory of Industrial Ecology and Environmental Engineering, Ministry of Education, School of Environmental Science and Technology, Dalian University of Technology, Dalian, 116024, China.
Sci Rep. 2017 May 10;7(1):1681. doi: 10.1038/s41598-017-01885-z.
Bioremediation of Cr(VI) and nitrate is considered as a promising and cost-effective alternative to chemical and physical methods. However, organo-Cr(III) complexes in effluent generally causes environmental concerns due to second-pollution. Here, Cr(VI) reduction and immobilization efficiencies of anaerobic activated sludge were investigated. Anaerobic activated sludge showed strong reduction ability of Cr(VI) and possessed a great potential of Cr(III) immobilization. Almost 100.0 mg l Cr(VI) could be completely reduced and immobilized by anaerobic activated sludge in a sequencing batch reactor in 24 h. And most generated Cr(III) was accumulated outside of sludge cells. Extracellular polymeric substances (EPS) could bind to Cr(VI) and form EPS-Cr(VI) interaction to reduce the toxic effect of Cr(VI) and promote the Cr(VI) reduction. Protein-like and humic-like substances were responsible for binding with Cr(VI), meanwhile the process was a thermodynamically favorable binding reaction. Then Cr(VI) was reduced to Cr(III) by membrane-associated chromate reductase of sludge. Eventually, the generated Cr(III) might exist as poly-nuclear Cr(III) complexes adhered to sludge surfaces.
生物修复 Cr(VI) 和硝酸盐被认为是一种有前途且具有成本效益的替代化学和物理方法的方法。然而，废水中的有机-Cr(III) 络合物通常会由于二次污染而引起环境问题。在这里，研究了厌氧活性污泥对 Cr(VI) 的还原和固定效率。厌氧活性污泥对 Cr(VI) 具有很强的还原能力，并且具有很好的 Cr(III) 固定潜力。在序批式反应器中，厌氧活性污泥在 24 小时内几乎可以完全还原和固定 100.0 mg/L 的 Cr(VI)。并且大多数生成的 Cr(III) 积累在污泥细胞外。细胞外聚合物物质 (EPS) 可以与 Cr(VI) 结合并形成 EPS-Cr(VI) 相互作用，从而降低 Cr(VI) 的毒性并促进 Cr(VI) 的还原。蛋白质样和腐殖质样物质负责与 Cr(VI) 结合，同时该过程是一种热力学有利的结合反应。然后，Cr(VI) 被污泥中膜结合的铬酸盐还原酶还原为 Cr(III)。最终，生成的 Cr(III) 可能以附着在污泥表面的多核 Cr(III)络合物形式存在。
