title: Thiosulphate conversion in a methane and acetate fed membrane bioreactor.
abstract: The use of methane and acetate as electron donors for biological reduction of thiosulphate in a 5-L laboratory membrane bioreactor was studied and compared to disproportionation of thiosulphate as competing biological reaction. The reactor was operated for 454 days in semi-batch mode; 30 % of its liquid phase was removed and periodically replenished (days 77, 119, 166, 258, 312 and 385). Although the reactor was operated under conditions favourable to promote thiosulphate reduction coupled to methane oxidation, thiosulphate disproportionation was the dominant microbial process. Pyrosequencing analysis showed that the most abundant microorganisms in the bioreactor were phototrophic green sulphur bacteria (GSB) belonging to the family Chlorobiaceae and thiosulphate-disproportionating bacteria belonging to the genus Desulfocapsa. Even though the reactor system was surrounded with opaque plastic capable of filtering most of the light, the GSB used it to oxidize the hydrogen sulphide produced from thiosulphate disproportionation to elemental sulphur. Interrupting methane and acetate supply did not have any effect on the microbial processes taking place. The ultimate goal of our research was to develop a process that could be applied for thiosulphate and sulphate removal and biogenic sulphide formation for metal precipitation. Even though the system achieved in this study did not accomplish the targeted conversion using methane as electron donor, it does perform microbial conversions which allow to directly obtain elemental sulphur from thiosulphate.
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6700 AA, Wageningen, The Netherlands.
authors.forename: Diego A
authors.initials: DA
authors.lastname: Suarez-Zuluaga
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands.
authors.forename: Peer H A
authors.initials: PH
authors.lastname: Timmers
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands.
authors.forename: Caroline M
authors.initials: CM
authors.lastname: Plugge
authors.affiliation: Laboratory of Microbiology, Wageningen University, Dreijenplein 10, 6703 HB, Wageningen, The Netherlands.
authors.forename: Alfons J M
authors.initials: AJ
authors.lastname: Stams
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6700 AA, Wageningen, The Netherlands.
authors.forename: Cees J N
authors.initials: CJ
authors.lastname: Buisman
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, Bornse Weilanden 9, 6700 AA, Wageningen, The Netherlands. jan.weijma@wur.nl.
authors.forename: Jan
authors.initials: J
authors.lastname: Weijma
mesh_terms: D000085:Acetates / Q000737:chemistry*; D001105:Archaea / Q000378:metabolism; D001419:Bacteria / Q000378:metabolism; D019149:Bioreactors; D004583:Electrons; D008697:Methane / Q000737:chemistry*; D010084:Oxidation-Reduction; D013455:Sulfur / Q000737:chemistry; D013885:Thiosulfates / Q000737:chemistry*
chemical_list: D000085:Acetates; D013885:Thiosulfates; D013455:Sulfur; D008697:Methane
keywords: Anaerobic oxidation of methane; Desulfocapsa; Green sulphur bacteria; Pyrosequencing; Sulphur production; Thiosulphate disproportionation