title: Effect of hydraulic retention time on sulfate reduction in a carbon monoxide fed thermophilic gas lift reactor.
abstract: Thermophilic hydrogenogenic carbon monoxide (CO) converting microorganisms present in anaerobic sludge play a crucial role in the application of CO as electron donor for sulfate reduction. Hydrogenogenic CO conversion was investigated in a gas lift reactor (55 degrees C) at different hydraulic retention times (HRT). Operation at a HRT>9h resulted in predominant consumption of CO-derived H2 by methanogens (up to 90%) and thus in a poor sulfate reduction efficiency of less than 15%. At HRTs<4 h, consumption of the CO-derived H2 was dominated by sulfate-reducers, i.e. up to 95% of H2 was used for sulfate reduction. Sulfate reduction rates of 17 mmol L(-1)d(-1) were achieved at a HRT of 3h, with over 87% of the H2 produced used for sulfate reduction. Methane production, however, persisted when operating under these conditions and increasing the HRT by returning it to values >5.5h resulted in a dominance of methanogenesis over sulfate reduction. The sulfate reduction rates were limited by the amount of CO supplied and its conversion efficiency (about 85%) at higher CO loads likely resulting from a low biomass retention.
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, Bomenweg 2, P.O. Box 8129, 6700 EV Wageningen, The Netherlands.
authors.forename: Jan
authors.initials: J
authors.lastname: Sipma
authors.forename: M Begoña
authors.initials: MB
authors.lastname: Osuna
authors.forename: Gatze
authors.initials: G
authors.lastname: Lettinga
authors.forename: Alfons J M
authors.initials: AJ
authors.lastname: Stams
authors.forename: Piet N L
authors.initials: PN
authors.lastname: Lens
mesh_terms: D000085:Acetates / Q000378:metabolism; D018533:Biomass; D019149:Bioreactors; D002248:Carbon Monoxide / Q000737:chemistry* / Q000378:metabolism; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism; D016999:Sulfur-Reducing Bacteria / Q000378:metabolism*; D013997:Time Factors; D014865:Waste Disposal, Fluid
chemical_list: D000085:Acetates; D012722:Sewage; D013431:Sulfates; D013440:Sulfides; D002248:Carbon Monoxide