乙酸驯化对厌氧污泥微生物群落结构及发酵特性的影响

采用乙酸对厌氧污泥进行逐步驯化,以富集乙酸营养型产甲烷菌群,解决厌氧发酵过程中的酸抑制问题.对驯化前后污泥中的微生物群落结构及其在高酸浓度和低p H值条件下的发酵特性进行了研究.结果表明:驯化后污泥中乙酸营养型产甲烷菌中的甲烷八叠球菌属(Methanosarcina)得到了明显富集,其相对丰度由原始的4.2%提高到58.1%,成为耐酸污泥中的主导优势古菌群;氢营养型产甲烷菌属的丰度则都有不同程度的下降.污泥中产甲烷菌群由氢营养型为主导转为乙酸营养型和氢营养型共同主导.驯化前后污泥中细菌的优势菌门均为主要降解纤维素和半纤维素的厚壁菌门(Firmicutes)和降解蛋白质的拟杆菌门(Bacteroidetes),其中驯化后Firmicutes的丰度由48.8%提高到61.7%,而Bacteroidetes的丰度则由30.1%降低至16.9%.驯化后的污泥对高VFA浓度和低pH值的耐受性均有较大程度的提高,其在VFA浓度为7500 mg·L~(-1)及pH 6.0条件下仍可以快速产气.

Effects of acid-tolerant acclimation on microbial community structure and fermentation performance of anaerobic sludge

To resolve the problem of acid inhibition in anaerobic digestion, anaerobic sludge was gradually acclimated with acetic acid for enriching acetotrophic methanogens. The microbial community structure and fermentation performances of pre-and post-acclimation sludge were studied. The results showed that the acetotrophic methanogens especially Methanosarcina was significantly enriched, the relative abundance of Methanosarcina increased from 4.2% to 58.1%, while that of the hydrogenotrophic methanogens was decreased in different degrees during acid acclimation process. After acid acclimation process, the dominant microbial community shifted from hydrogenotrophic methanogens to acetotrophic methanogens and hydrogenotrophic methanogens. The dominant bacteria in both pre-and post-acclimation sludge were Firmicutes and Bacteroidetes. However, the relative abundance of Firmicutes was increased from 48.8% to 61.7%, while that of Bacteroideteswas dereased from 30.1% to 16.9%. Tolerant capabilities of the acclimation sludge to high volatile fatty acid (VFA) concentration and low pH value were obviously increased. The acclimation sludge could rapidly produce methane under the condition of 7500 mg·L^-1 VFA and pH 6.0.