title: Decolorization characteristics of a newly isolated salt-tolerant Bacillus sp. strain and its application for azo dye-containing wastewater in immobilized form.
abstract: Strain CICC 23870 capable of decolorization of various azo dyes under high saline conditions was isolated from saline-alkali soil. The oxygen-insensitive azoreductase in crude extracts exhibited a wide substrate adaptively in the presence of NADH as a cofactor. The decolorization process by free cells followed first-order kinetics, with a high Methyl Orange (MO) tolerance concentration up to 100 mg l(-1) estimated by Haldane model. The average decolorization rate of free cell system was 26.30 mg g(-1) h(-1) at initial MO concentration of 32.7 mg l(-1). However, the values for the systems of immobilized cells (4 mm) in alginate, alginate and nano-TiO2, and alginate and powered activated carbon (PAC) were 6.83, 4.64, and 11.34 mg g(-1) h(-1), respectively. The effective diffusion factors in the tree different matrices were calculated by diffusion-based mathematic model. The diffusion step controls the overall decolorization rate, and the effective diffusion coefficients varied with internal structure of the bead matrices. The diffusion coefficients were increased from 4.98 × 10(-9) to 2.25 × 10(-8) cm(2) s(-1) when PAC was added, but decreased to 6.62 × 10(-10) cm(2) s(-1) when nano-TiO2 was added. The immobilized matrices could be reused for at least three cycles but with a decreased decolorization rate, possibly due to the breakage of beads at the end of each cycle, which led to the loss of immobilized bacteria.
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China. lyu@njfu.edu.cn.|Jiangsu Key Laboratory of Biomass Energy and Materials, Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, Nanjing, 210042, China. lyu@njfu.edu.cn.
authors.forename: Lei
authors.initials: L
authors.lastname: Yu
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Xiao-Yu
authors.initials: XY
authors.lastname: Zhang
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Qing-Wen
authors.initials: QW
authors.lastname: Tang
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Jia
authors.initials: J
authors.lastname: Li
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Tian
authors.initials: T
authors.lastname: Xie
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Ming-Yue
authors.initials: MY
authors.lastname: Cao
authors.affiliation: Key Laboratory of soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
authors.forename: Rui-Chang
authors.initials: RC
authors.lastname: Zhang
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Shi
authors.initials: S
authors.lastname: Wang
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Jin-Mei
authors.initials: JM
authors.lastname: Hu
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China.
authors.forename: Wei-Chuan
authors.initials: WC
authors.lastname: Qiao
authors.affiliation: CAS Key Laboratory of Urban Pollutant Conversion, Department of Chemistry, University of Science and Technology of China, Hefei, 230026, China.
authors.forename: Wen-Wei
authors.initials: WW
authors.lastname: Li
authors.affiliation: College of Biology and the Environment, Co-Innovation Center for Sustainable Forestry in Southern China, Nanjing Forestry University, Nanjing, 210037, China. hhruan@njfu.edu.cn.
authors.forename: Hong-Hua
authors.initials: HH
authors.lastname: Ruan
mesh_terms: D001391:Azo Compounds / Q000378:metabolism*; D001407:Bacillus / Q000187:drug effects / Q000302:isolation & purification* / Q000378:metabolism*; D001673:Biodegradation, Environmental; D001711:Biotransformation; D007700:Kinetics; D009243:NAD / Q000378:metabolism; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009601:Nitroreductases; D012492:Salts / Q000378:metabolism; D012988:Soil Microbiology; D013379:Substrate Specificity; D062065:Wastewater / Q000737:chemistry*; D014873:Water Pollutants / Q000378:metabolism*
chemical_list: D001391:Azo Compounds; D009243:NAD; D009247:NADH, NADPH Oxidoreductases; D009601:Nitroreductases; D012492:Salts; D062065:Wastewater; D014873:Water Pollutants; C100258:methyl orange; C021106:azoreductase
keywords: Anaerobic decolorization; Diffusion modeling; Immobilization; Salt-tolerant bacteria