title: Bioreduction of Chromate in a Methane-Based Membrane Biofilm Reactor.
abstract: For the first time, we demonstrate chromate (Cr(VI)) bioreduction using methane (CH4) as the sole electron donor in a membrane biofilm reactor (MBfR). The experiments were divided into five stages lasting a total of 90 days, and each stage achieved a steady state for at least 15 days. Due to continued acclimation of the microbial community, the Cr(VI)-reducing capacity of the biofilm kept increasing. Cr(VI) removal at the end of the 90-day test reached 95% at an influent Cr(VI) concentration of 3 mg Cr/L and a surface loading of 0.37g of Cr m(-2) day(-1). Meiothermus (Deinococci), a potential Cr(VI)-reducing bacterium, was negligible in the inoculum but dominated the MBfR biofilm after Cr(VI) was added to the reactor, while Methylosinus, a type II methanotrophs, represented 11%-21% of the total bacterial DNA in the biofilm. Synergy within a microbial consortia likely was responsible for Cr(VI) reduction based on CH4 oxidation. In the synergy, methanotrophs fermented CH4 to produce metabolic intermediates that were used by the Cr(VI)-reducing bacteria as electron donors. Solid Cr(III) was the main product, accounting for more than 88% of the reduced Cr in most cases. Transmission electron microscope (TEM) and energy dispersive X-ray (EDS) analysis showed that Cr(III) accumulated inside and outside of some bacterial cells, implying that different Cr(VI)-reducing mechanisms were involved.
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Chun-Yu
authors.initials: CY
authors.lastname: Lai
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Zhong
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Yin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Jia-Xian
authors.initials: JX
authors.lastname: Chen
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Li-Lian
authors.initials: LL
authors.lastname: Wen
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Ling-Dong
authors.initials: LD
authors.lastname: Shi
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Yan-Ping
authors.initials: YP
authors.lastname: Sun
authors.affiliation: State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: Fang
authors.initials: F
authors.lastname: Ma
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University , P.O. Box 875701, Tempe, Arizona 85287-5701, United States.
authors.forename: Bruce E
authors.initials: BE
authors.lastname: Rittmann
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University , P.O. Box 875701, Tempe, Arizona 85287-5701, United States.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhou
authors.affiliation: Department of Civil and Environmental Engineering, FAMU-FSU College of Engineering, Florida State University , Tallahassee, Florida 32310-6046, United States.
authors.forename: Youneng
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.
authors.forename: Ping
authors.initials: P
authors.lastname: Zheng
authors.affiliation: Department of Environmental Engineering, College of Environmental and Resource Science, Zhejiang University , Hangzhou, China.|State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology , Harbin 150090, China.
authors.forename: He-Ping
authors.initials: HP
authors.lastname: Zhao
mesh_terms: D001419:Bacteria / Q000378:metabolism; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology; D002840:Chromates / Q000378:metabolism*; D002857:Chromium / Q000378:metabolism; D008697:Methane / Q000378:metabolism; D010084:Oxidation-Reduction
chemical_list: D002840:Chromates; D002857:Chromium; D008697:Methane