title: Decolorization of azo dyes by Shewanella oneidensis MR-1 in the presence of humic acids.
abstract: The effects of humic acid (HA) on azo dye decolorization by Shewanella oneidensis MR-1 were studied. It was found that HA species isolated from different sources could all accelerate the decolorization of Acid Red 27 (AR27). Anoxic and anaerobic conditions were required for the enhancement of azo dye decolorization by HA. In the presence of 50 mg DOC L⁻¹ Aldrich HA, 15-29% increases in decolorization efficiencies of azo dyes with different structures were achieved in 11 h. The enhancing effects increased with the increase of HA concentrations ranging from 25 to 150 mg DOC L⁻¹, and the decolorization rates were directly proportional to the HA concentrations when they were below 100 mg DOC L⁻¹. Lactate and formate were good electron donors for AR27 decolorization in the presence of HA. Both nitrate (0.1-3.0 mM) and nitrite (0.3-1.2 mM) inhibited AR27 decolorization in the presence of HA, and negligible decolorization was observed before their removal. Soluble FeCl₃ could accelerate the decolorization process in the presence of HA, whereas insoluble hematite could not. These findings may affect the understanding of bioremediation of azo dye-polluted environments and help improve the treatment of azo dye wastewaters.
authors.affiliation: Key Laboratory of Industrial Ecology and Environmental Engineering (Ministry of Education), State Key Laboratory of Fine Chemicals, School of Environmental Science and Technology, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China.
authors.forename: Guangfei
authors.initials: G
authors.lastname: Liu
authors.forename: Jiti
authors.initials: J
authors.lastname: Zhou
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Xiujuan
authors.initials: X
authors.lastname: Wang
authors.forename: Ruofei
authors.initials: R
authors.lastname: Jin
authors.forename: Hong
authors.initials: H
authors.lastname: Lv
mesh_terms: D000548:Amaranth Dye; D001391:Azo Compounds / Q000737:chemistry / Q000378:metabolism*; D001673:Biodegradation, Environmental; D004396:Coloring Agents / Q000737:chemistry / Q000378:metabolism*; D006812:Humic Substances; D007218:Industrial Microbiology / Q000379:methods*; D020592:Shewanella / Q000145:classification / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D006812:Humic Substances; D014874:Water Pollutants, Chemical; D000548:Amaranth Dye