title: Effect of sulfide removal on sulfate reduction at pH 5 in a hydrogen fed gas-lift bioreactor.
abstract: Biotechnological treatment of sulfate- and metal-ionscontaining acidic wastewaters from mining and metallurgical activities utilizes sulfate-reducing bacteria to produce sulfide that can subsequently precipitate metal ions. Reducing sulfate at a low pH has several advantages above neutrophilic sulfate reduction. This study describes the effect of sulfide removal on the reactor performance and microbial community in a high-rate sulfidogenic gas-lift bioreactor fed with hydrogen at a controlled internal pH of 5. Under sulfide removal conditions, 99% of the sulfate was converted at a hydraulic retention time of 24 h, reaching a volumetric activity as high as 51 mmol sulfate/l/d. Under nonsulfide removal conditions, <25% of the sulfate was converted at a hydraulic retention time of 24 h reaching volumetric activities of <13mmol sulfate/l/d. The absence of sulfide removal at a hydraulic retention time of 24 h resulted in an average H2S concentration of 18.2 mM (584 mg S/l). The incomplete sulfate removal was probably due to sulfide inhibition. Molecular phylogenetic analysis identified 11 separate 16S rRNA bands under sulfide stripping conditions, whereas under nonsulfide removal conditions only 4 separate 16S rRNA bands were found. This shows that a less diverse population was found in the presence of a high sulfide concentration.
authors.affiliation: Sub Department of Environmental Technology, Wageningen University and Research Centre, P.O. Box 8129, 6700 EV Wageningen,The Netherlands. Martijn.Bijmans@wur.nl
authors.forename: Martijn F M
authors.initials: MF
authors.lastname: Bijmans
authors.forename: Mark
authors.initials: M
authors.lastname: Dopson
authors.forename: Frederick
authors.initials: F
authors.lastname: Ennin
authors.forename: Piet N L
authors.initials: PN
authors.lastname: Lens
authors.forename: Cees J N
authors.initials: CJ
authors.lastname: Buisman
mesh_terms: D001105:Archaea / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D001673:Biodegradation, Environmental; D019149:Bioreactors / Q000382:microbiology*; D017753:Ecosystem; D006859:Hydrogen / Q000378:metabolism* / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D010084:Oxidation-Reduction; D010802:Phylogeny; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA; D013431:Sulfates / Q000378:metabolism*; D013440:Sulfides / Q000378:metabolism*; D014865:Waste Disposal, Fluid
chemical_list: D007220:Industrial Waste; D012336:RNA, Ribosomal, 16S; D013431:Sulfates; D013440:Sulfides; D006859:Hydrogen