title: Promotion of Ni2+ removal by masking toxicity to sulfate-reducing bacteria: addition of citrate.
abstract: The sulfate-reducing bioprocess is a promising technology for the treatment of heavy metal-containing wastewater. This work was conducted to investigate the possibility of promoting heavy metal removal by the addition of citrate to mask Ni2+ toxicity to sulfate-reducing bacteria (SRB) in batch reactors. SRB growth was completely inhibited in Ni2+-containing medium (1 mM) when lactate served as the sole carbon resource, leading to no sulfate reduction and Ni2+ removal. However, after the addition of citrate, SRB grew well, and sulfate was quickly reduced to sulfide. Simultaneously, the Ni-citrate complex was biodegraded to Ni2+ and acetate. The NiS precipitate was then formed, and Ni2+ was completely removed from the solution. It was suggested that the addition of citrate greatly alleviates Ni2+ toxicity to SRB and improves the removal of Ni2+, which was confirmed by quantitative real-time PCR targeting dissimilatory sulfite reductase (dsrAB) genes. Analysis of the carbon metabolism indicated that lactate instead of acetate served as the electron donor for sulfate reduction. This study offers a potential approach to increase the removal of heavy metals from wastewater in the single stage SRB-based bioprocess.
authors: Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences & Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu 610041, China. jwqian209@outlook.com.
authors: Junwei
authors: J
authors: Qian
authors: Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences & Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu 610041, China. zhuxy@cib.ac.cn.
authors: Xiaoyu
authors: X
authors: Zhu
authors: Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences & Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu 610041, China. taoyong@cib.ac.cn.
authors: Yong
authors: Y
authors: Tao
authors: College of Life Science, Sichuan University, Chengdu 610064, China. zhyn807@163.com.
authors: Yan
authors: Y
authors: Zhou
authors: Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences & Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu 610041, China. hexh@cib.ac.cn.
authors: Xiaohong
authors: X
authors: He
authors: Key Laboratory of Environmental and Applied Microbiology, Chengdu Institute of Biology, Chinese Academy of Sciences & Environmental Microbiology Key Laboratory of Sichuan Province, Chengdu 610041, China. lidp@cib.ac.cn.
authors: Daping
authors: D
authors: Li
mesh_terms: D001419:Bacteria / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019343:Citric Acid / Q000378:metabolism*; D019216:Metals, Heavy / Q000378:metabolism*; D009532:Nickel / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism
chemical_list: D019216:Metals, Heavy; D013431:Sulfates; D013440:Sulfides; D019343:Citric Acid; D009532:Nickel