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Int. J. Mol. Sci. 2015, 16(4), 7932-7943;

Promotion of Ni2+ Removal by Masking Toxicity to Sulfate-Reducing Bacteria: Addition of Citrate

1,* , 2
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
College of Life Science, Sichuan University, Chengdu 610064, China
These authors contributed equally to this work.
Authors to whom correspondence should be addressed.
Academic Editor: Ji-Dong Gu
Received: 21 November 2014 / Revised: 22 January 2015 / Accepted: 3 April 2015 / Published: 9 April 2015
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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. View Full-Text
Keywords: Ni removal; Ni-citrate complex; toxicity masking; lactate; sulfate reduction Ni removal; Ni-citrate complex; toxicity masking; lactate; sulfate reduction

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Qian, J.; Zhu, X.; Tao, Y.; Zhou, Y.; He, X.; Li, D. Promotion of Ni2+ Removal by Masking Toxicity to Sulfate-Reducing Bacteria: Addition of Citrate. Int. J. Mol. Sci. 2015, 16, 7932-7943.

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