CaO2促进污泥厌氧发酵产酸性能的微生物机制
Effects and mechanism of CaO2 on acid production performance of anaerobic sludge fermentation
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摘要: 研究了不同CaO2浓度对剩余污泥厌氧发酵产酸性能和微生物群落变化的影响.试验结果表明,CaO2促进了污泥的水解,当投加量为0.35 g CaO2/g VS时发酵效果最好,产物短链脂肪酸(SCFAs)的浓度达到1424 mg·L-1,约为对照组的4.3倍.高通量测序结果表明投加CaO2会降低微生物群落的多样性,富集水解产酸菌,抑制其它门类细菌,其中,厚壁菌门(Firmicutes)的相对丰度从对照组中的7.16%增加至0.35 g CaO2/g VS组中的64.23%,梭菌纲 (Clostridia)和芽孢杆菌纲(Bacilli)相对丰度显著增加也是SCFAs产量高的主要原因.随着CaO2投加量增加,细菌胞外聚合物(EPS)由紧密结合型(TB-EPS)向松散结合型(LB-EPS)和黏液型(S-EPS)转化,并促进了细菌胞外多糖的合成与分泌,提高了功能菌群的生存能力.细菌的抗氧化酶系统对厌氧发酵体系中功能菌群的筛选可能具有影响.CaO2的加入提高了功能菌群总体SOD和CAT基因的相对丰度,通过促进抗氧化酶的分泌,提高功能菌群的抗氧化能力,使细菌群落向有利于生产SCFAs的菌群转化.Abstract: The effects of different CaO2 concentrations on the acid production performance of anaerobic fermentation of excess sludge were studied and the microbial mechanisms were analyzed. The experimental results showed that CaO2 promoted the hydrolysis of sludge. When the dosage was 0.35 g CaO2/g VS, the fermentation effect was the best. The output of SCFAs reached 1424 mg·L-1, about 4.3 times that of the control group. The oxidative damage caused by CaO2 to bacterial communities is proportional to its concentration. The results of high-throughput sequencing showed that CaO2 would reduce the diversity of microbial communities, enrich acidogenic bacteria and inhibit other bacteria. The relative abundance of Firmicutes increased from 7.16% in the control group to 64.23% in the 0.35 g CaO2/g VS group. The significant increase in the abundance of Clostridia and Bacilli was the main reason for the high yield of SCFAs in this group. With the increase of CaO2 concentration, bacterial extracellular polymer (EPS) transforms from tightly bounded EPS (TB-EPS) to loosely bounded EPS (LB-EPS) and slime EPS (S-EPS), promotes the synthesis and secretion of bacterial extracellular polysaccharide, and improves the viability of functional bacteria. The antioxidant enzymes of bacteria also affect the changing of functional bacteria community in anaerobic fermentation system. The addition of CaO2 improves the relative abundance of SOD and CAT related genes, improves the antioxidant capacity of functional bacteria by promoting the secretion of antioxidant enzymes, and enhances the production of SCFAs.
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Key words:
- anaerobic fermentation /
- excess sludge /
- SCFAs /
- antioxidant enzymes
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