title: Bio-reduction of tetrachloroethen using a H2-based membrane biofilm reactor and community fingerprinting.
abstract: Chlorinated ethenes in drinking water could be reductively dechlorinated to non-toxic ethene by using a hydrogen based membrane biofilm reactor (H2-MBfR) under denitrifying conditions as it provides an appropriate environment for dechlorinating bacteria in biofilm communities. This study evaluates the reductive dechlorination of perchloroethene (PCE) to non-toxic ethene (ETH) and comparative community analysis of the biofilm grown on the gas permeable membrane fibers. For these purposes, three H2-MBfRs receiving three different chlorinated ethenes (PCE, TCE and DCE) were operated under different hydraulic retention times (HRTs) and H2 pressures. Among these reactors, the H2-MBfR fed with PCE (H2-MBfR 1) accomplished a complete dechlorination, whereas cis-DCE accumulated in the TCE receiving H2-MBfR 2 and no dechlorination was detected in the DCE receiving H2-MBfR 3. The results showed that 95% of PCE dechlorinated to ETH together with over 99.8% dechlorination efficiency. Nitrate was the preferred electron acceptor as the most of electrons generated from H2 oxidation used for denitrification and dechlorination started under nitrate deficient conditions at increased H2 pressures. PCR-DGGE analysis showed that Dehalococcoides were present in autotrophic biofilm community dechlorinating PCE to ethene, and RDase genes analysis revealed that pceA, tceA, bvcA and vcrA, responsible for complete dechlorination step, were available in Dehalococcoides strains.
authors.affiliation: Dicle University, 21000 Diyarbakır, Turkey. Electronic address: karatasserdar@hotmail.com.
authors.forename: Serdar
authors.initials: S
authors.lastname: Karataş
authors.affiliation: Fırat University, Faculty of Engineering, Department of Environmental Engineering, 23119 Elazığ, Turkey. Electronic address: hhasar@firat.edu.tr.
authors.forename: Halil
authors.initials: H
authors.lastname: Hasar
authors.affiliation: Fırat University, Faculty of Engineering, Department of Environmental Engineering, 23119 Elazığ, Turkey. Electronic address: etaskan@firat.edu.tr.
authors.forename: Ergin
authors.initials: E
authors.lastname: Taşkan
authors.affiliation: Yıldız Technical University, Department of Environmental Engineering, İstanbul, Turkey. Electronic address: bestamin.ozkaya@gmail.com.
authors.forename: Bestamin
authors.initials: B
authors.lastname: Özkaya
authors.affiliation: Istanbul Medeniyet University, Department of Bioengineering, İstanbul, Turkey. Electronic address: erkansahinkaya@yahoo.com.
authors.forename: Erkan
authors.initials: E
authors.lastname: Şahinkaya
mesh_terms: D052818:Autotrophic Processes; D001673:Biodegradation, Environmental; D018441:Biofilms; D019149:Bioreactors / Q000382:microbiology*; D041862:Chloroflexi / Q000235:genetics* / Q000378:metabolism; D004867:Equipment Design; D054879:Halogenation; D006859:Hydrogen / Q000737:chemistry; D059013:Microbial Consortia / Q000235:genetics; D013750:Tetrachloroethylene / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000378:metabolism; D018508:Water Purification / Q000295:instrumentation* / Q000379:methods*
chemical_list: D014874:Water Pollutants, Chemical; D006859:Hydrogen; D013750:Tetrachloroethylene
keywords: Dehalococcoides; Hydrogen; Membrane biofilm reactor; Perchloroethene; Reductive dehalogenation