Weijma J, Stams A J, Hulshoff Pol L W, Lettinga G
Department of Biomolecular Sciences, Laboratory of Microbiology, Wageningen University, Hesselink van Suchtelenweg 4, 6703 CT, Wageningen, The Netherlands.
Biotechnol Bioeng. 2000 Feb 5;67(3):354-63.
Sulfate reduction outcompeted methanogenesis at 65 degrees C and pH 7.5 in methanol and sulfate-fed expanded granular sludge bed reactors operated at hydraulic retention times (HRT) of 14 and 3.5 h, both under methanol-limiting and methanol-overloading conditions. After 100 and 50 days for the reactors operated at 14 and 3.5 h, respectively, sulfide production accounted for 80% of the methanol-COD consumed by the sludge. The specific methanogenic activity on methanol of the sludge from a reactor operated at HRTs of down to 3.5 h for a period of 4 months gradually decreased from 0. 83 gCOD. gVSS(-1). day(-1) at the start to a value of less than 0.05 gCOD. gVSS(-1). day(-1), showing that the relative number of methanogens decreased and eventually became very low. By contrast, the increase of the specific sulfidogenic activity of sludge from 0. 22 gCOD. gVSS(-1). day(-1) to a final value of 1.05 gCOD. gVSS(-1). day(-1) showed that sulfate reducing bacteria were enriched. Methanol degradation by a methanogenic culture obtained from a reactor by serial dilution of the sludge was inhibited in the presence of vancomycin, indicating that methanogenesis directly from methanol was not important. H(2)/CO(2) and formate, but not acetate, were degraded to methane in the presence of vancomycin. These results indicated that methanol degradation to methane occurs via the intermediates H(2)/CO(2) and formate. The high and low specific methanogenic activity of sludge on H(2)/CO(2) and formate, respectively, indicated that the former substrate probably acts as the main electron donor for the methanogens during methanol degradation. As sulfate reduction in the sludge was also strongly supported by hydrogen, competition between sulfate reducing bacteria and methanogens in the sludge seemed to be mainly for this substrate. Sulfate elimination rates of up to 15 gSO(4)(2-)/L per day were achieved in the reactors. Biomass retention limited the sulfate elimination rate.
在温度为65摄氏度、pH值为7.5的条件下，以甲醇和硫酸盐为进料的膨胀颗粒污泥床反应器中，在水力停留时间（HRT）分别为14小时和3.5小时的情况下，无论是甲醇受限还是甲醇过载条件下，硫酸盐还原都胜过甲烷生成。分别在14小时和3.5小时运行的反应器经过100天和50天后，硫化物产量占污泥消耗的甲醇化学需氧量（COD）的80%。在水力停留时间低至3.5小时运行4个月的反应器中，污泥对甲醇的比产甲烷活性从开始时的0.83 gCOD·gVSS⁻¹·天⁻¹逐渐降至低于0.05 gCOD·gVSS⁻¹·天⁻¹，这表明产甲烷菌的相对数量减少并最终变得非常低。相比之下，污泥的比产硫化物活性从0.22 gCOD·gVSS⁻¹·天⁻¹增加到最终值1.05 gCOD·gVSS⁻¹·天⁻¹，表明硫酸盐还原菌得到了富集。从反应器中通过污泥连续稀释获得的产甲烷培养物对甲醇的降解在万古霉素存在下受到抑制，这表明直接从甲醇产甲烷并不重要。在万古霉素存在下，H₂/CO₂和甲酸盐（而非乙酸盐）被降解为甲烷。这些结果表明，甲醇降解为甲烷是通过中间产物H₂/CO₂和甲酸盐进行的。污泥对H₂/CO₂和甲酸盐的比产甲烷活性分别较高和较低，这表明前一种底物可能在甲醇降解过程中作为产甲烷菌的主要电子供体。由于污泥中的硫酸盐还原也受到氢气的强烈支持，污泥中硫酸盐还原菌和产甲烷菌之间的竞争似乎主要是针对这种底物。反应器中的硫酸盐去除率高达每天15 gSO₄²⁻/L。生物量保留限制了硫酸盐去除率。
