title: Use of silicate minerals for long-term pH control during reductive dechlorination of high tetrachloroethene concentrations in continuous flow-through columns.
abstract: The long-term buffering potential of three silicate minerals (diopside, fayalite and forsterite) present as fine particles in porous quartz sand medium was evaluated in flow-through column experiments over a period of 6.5 months. The columns were operated with PCE concentrations close to saturation and inoculated with the organohalide-respiring consortium SDC-9™, which is able to completely dechlorinate PCE to ethene at high concentrations. In the absence of pH buffering agents, fermentation and organohalide respiration drove the pH close to 6.1, leading to severe inhibition of PCE dechlorination. Forsterite and fayalite were able to maintain the pH close to 7.5 and 6.5, respectively, and to sustain the production of VC and ethene. Diopside gradually lost its buffering capacity during the first 84 days due to the formation of a low reactive leached layer but dechlorination to cis-DCE was still achieved. Among the three minerals tested, forsterite was identified as the best buffering agent. Its presence led to the best PCE removal performance and the highest relative abundance of Dehalococcoides. This study showed that forsterite and fayalite are promising sources of long-term pH buffering for in situ bioremediation of source-zone PCE.
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland; Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland.
authors.forename: Elsa
authors.initials: E
authors.lastname: Lacroix
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland.
authors.forename: Alessandro
authors.initials: A
authors.lastname: Brovelli
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland.
authors.forename: Julien
authors.initials: J
authors.lastname: Maillard
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland.
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Rohrbach-Brandt
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Ecological Engineering Laboratory, Lausanne, Switzerland.
authors.forename: D A
authors.initials: DA
authors.lastname: Barry
authors.affiliation: Ecole Polytechnique Fédérale de Lausanne (EPFL), School of Architecture, Civil and Environmental Engineering (ENAC), Laboratory for Environmental Biotechnology, Lausanne, Switzerland. Electronic address: christof.holliger@epfl.ch.
authors.forename: Christof
authors.initials: C
authors.lastname: Holliger
mesh_terms: D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D010084:Oxidation-Reduction; D017640:Silicates / Q000737:chemistry*; D013750:Tetrachloroethylene / Q000032:analysis / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D017640:Silicates; D014874:Water Pollutants, Chemical; D013750:Tetrachloroethylene
keywords: Acidification; Microbial reductive dechlorination; Organohalide respiration; PCE; Silicate minerals; pH buffer