温度转换对厌氧消化系统连续运行及微生物群落的影响

Effect of temperature conversion on continuous operation and microbial community of anaerobic digestion system

通过210d的连续厌氧消化试验,实现了以餐厨垃圾为发酵底物的同一厌氧消化系统内发酵温度从中温到高温的转换.试验结果显示,中温阶段,最高有机负荷(OLR)为6.5kg COD/(m^(3)·d),平均沼气产率658L/(kg COD·d);产甲烷优势菌属包括Methanosaeta(57.0%)、Methanospirillum(10.0%)、Methanomethylovorans(9.2%)和Methanobacterium(19.7%),其与水解酸化类细菌、同型产乙酸菌等形成互营关系,实现高效产甲烷过程.经35d升温过程后,中温发酵系统平稳转换为高温发酵系统.高温系统稳定运行时OLR为5.0kg COD/(m^(3)·d),平均沼气产率480L/(kg COD·d);产甲烷优势菌属主要为Methanoculleus(96.2%),其与互养产氢类细菌和互营乙酸氧化细菌等形成互营关系,共同推动H_(2)利用和产甲烷过程.但高温系统在试验后期呈现明显酸化趋势,产气效率大幅下降,推断是因为该阶段产甲烷菌活性受到抑制,而水解产酸菌大量富集,使得有机酸生成与利用过程失衡,最终导致系统崩溃.综上说明厌氧发酵系统在线温度转换具有技术可行性,但高温系统的运行性能和稳定性较中温系统偏低.

Through 210 days of continuous anaerobic digestion experiment in the same anaerobic digestion system with food waste as fermentation substrate,the conversion of fermentation temperature from medium temperature to high temperature was achieved.In medium temperature fermentation stage,the maximum organic loading rates(OLR)was 6.5kg COD/(m^(3)·d),the average biogas production rate was 658L/(kg COD·d);Methanosaeta(57.0%)、Methanospirillum(10.0%)、Methanomethylovorans(9.2%)and Methanobacterium(19.7%),which formed a symbiotic relationship with hydrolytic acidifying bacteria and homoacetogenesis to achieve efficient methanogenic process,were included in the dominant methanogens.After 35 days’heating process,the medium temperature fermentation system smoothly converted into high temperature system.In high temperature fermentation stage,the maxium OLR was 5.0kg COD/(m^(3)·d),and the average biogas production rate was 480L/(kg COD·d);Methanoculleus(96.2%)became dominant methanogenic bacteria,and formed an interacting relationship with syntrophic hydrogen-producing bacteria and syntrophic acetate oxidation bacteria,which jointly promoted H_(2)utilization and methanogenic process.However,obvious acidification trend and reduced gas production efficiency appeared in later stage of high-temperatures system.It was inferred that the activity of methanogens was inhibited with highly enriching of hydrolytic acid-producing bacteria,resulting the imbalance of organic acids production and utilization and the system collapse.Therefore,online temperature conversion of anaerobic fermentation system was technically feasible,but the performance and stability of high temperature fermentation system were lower than that of medium temperature fermentation system.