Sulfate reduction in methanogenic bioreactors |
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Authors: | Stefanie J.W.H.,Oude Elferink,ré Visser,Look W. Hulshoff Pol,Alfons J.M. Stams |
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Affiliation: | Department of Microbiology, Wageningen Agricultural University, Hesselink can Suchtelenweg 4, 6703 CT Wageningen, the Netherlands;Department of Enuironmental Technology, Wageningen Agricultural University, Wageningen, the Netherlands |
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Abstract: | Abstract: In the anaerobic treatment of sulfate-containing wastewater, sulfate reduction interferes with methanogenesis. Both mutualistic and competitive interactions between sulfate-reducing bacteria and methanogenic bacteria have been observed. Sulfate reducers will compete with methanogens for the common substrates hydrogen, formate and acetate. In general, sulfate reducers have better growth kinetic properties than methanogens, but additional factors which may be of importance in the competition are adherence properties, mixed substrate utilization, affinity for sulfate of sulfate reducers, relative numbers of bacteria, and reactor conditions such as pH, temperature and sulfide concentration. Sulfate reducers also compete with syntrophic methanogenic consortia involved in the degradation of substrates like propionate and butyrate. In the absence of sulfate these methanogenic consortia are very important, but in the presence of sulfate they are thought to be easily outcompeted by sulfate reducers. However, at relatively low sulfate concentrations, syntrophic degradation of propionate and butyrate coupled to HZ removal via sulfate reduction rather than via methanogenesis may become important. A remarkable feature of some sulfate reducers is their ability to grow fermentatively or to grow in syntrophic association with methanogens in the absence of sulfate. |
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Keywords: | Anaerobic conditions Sulfate reduction Interspecies electron transfer Methanogenic degradation Methanogenesis Acetate Propionate Butyrate Hydrogen Syntrophy Sulfide toxicity |
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