title: Removal of multiple electron acceptors by pilot-scale, two-stage membrane biofilm reactors.
abstract: We studied the performance of a pilot-scale membrane biofilm reactor (MBfR) treating groundwater containing four electron acceptors: nitrate (NO3(-)), perchlorate (ClO4(-)), sulfate (SO4(2-)), and oxygen (O2). The treatment goal was to remove ClO4(-) from ∼200 μg/L to less than 6 μg/L. The pilot system was operated as two MBfRs in series, and the positions of the lead and lag MBfRs were switched regularly. The lead MBfR removed at least 99% of the O2 and 63-88% of NO3(-), depending on loading conditions. The lag MBfR was where most of the ClO4(-) reduction occurred, and the effluent ClO4(-) concentration was driven to as low as 4 μg/L, with most concentrations ≤10 μg/L. However, SO4(2-) reduction occurred in the lag MBfR when its NO3(-) + O2 flux was smaller than ∼0.18 g H2/m(2)-d, and this was accompanied by a lower ClO4(-) flux. We were able to suppress SO4(2-) reduction by lowering the H2 pressure and increasing the NO3(-) + O2 flux. We also monitored the microbial community using the quantitative polymerase chain reaction targeting characteristic reductase genes. Due to regular position switching, the lead and lag MBfRs had similar microbial communities. Denitrifying bacteria dominated the biofilm when the NO3(-) + O2 fluxes were highest, but sulfate-reducing bacteria became more important when SO4(2-) reduction was enhanced in the lag MBfR due to low NO3(-) + O2 flux. The practical two-stage strategy to achieve complete ClO4(-) and NO3(-) reduction while suppressing SO4(2-) reduction involved controlling the NO3(-) + O2 surface loading between 0.18 and 0.34 g H2/m(2)-d and using a low H2 pressure in the lag MBfR.
authors.affiliation: MOE Key Lab of Environmental Remediation and Ecosystem Health, College of Environmental and Resource Science, Zhejiang University, Hangzhou, China; Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA. Electronic address: hopechoil@gmail.com.
authors.forename: He-Ping
authors.initials: HP
authors.lastname: Zhao
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA.
authors.forename: Aura
authors.initials: A
authors.lastname: Ontiveros-Valencia
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA; Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
authors.forename: Youneng
authors.initials: Y
authors.lastname: Tang
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA.
authors.forename: Bi-O
authors.initials: BO
authors.lastname: Kim
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA; School of Civil and Environmental Engineering, Georgia Institute of Technology, 790 Atlantic Drive, Atlanta, GA 30332-0355, USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Vanginkel
authors.affiliation: APTwater Inc., 2516 Verne Roberts Circle, Suite H-102, Antioch, CA 94509, USA.
authors.forename: David
authors.initials: D
authors.lastname: Friese
authors.affiliation: APTwater Inc., 2516 Verne Roberts Circle, Suite H-102, Antioch, CA 94509, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Overstreet
authors.affiliation: CDM Smith, 14432 SE Eastgate Way, Bellevue, WA 98007, USA.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Smith
authors.affiliation: CDM Smith, 14432 SE Eastgate Way, Bellevue, WA 98007, USA.
authors.forename: Patrick
authors.initials: P
authors.lastname: Evans
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA.
authors.forename: Rosa
authors.initials: R
authors.lastname: Krajmalnik-Brown
authors.affiliation: Swette Center for Environmental Biotechnology, Biodesign Institute at Arizona State University, P.O. Box 875701, Tempe, AZ 85287-5701, USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Rittmann
mesh_terms: D001419:Bacteria / Q000254:growth & development; D018441:Biofilms; D019149:Bioreactors; D004583:Electrons; D008567:Membranes, Artificial; D009566:Nitrates / Q000302:isolation & purification; D010100:Oxygen / Q000302:isolation & purification; D010472:Perchlorates / Q000302:isolation & purification; D010865:Pilot Projects; D013431:Sulfates / Q000302:isolation & purification; D013997:Time Factors; D014865:Waste Disposal, Fluid; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods*
chemical_list: D008567:Membranes, Artificial; D009566:Nitrates; D010472:Perchlorates; D013431:Sulfates; D010100:Oxygen; C494474:perchlorate
keywords: Hydrogen; Microbial ecology; Nitrate; Perchlorate; Pilot membrane biofilm reactor; Sulfate