强化两相污泥高固厌氧消化系统的微生物群落

Microbial Structure of an Enhanced Two-phase High-solid Anaerobic Digestion System Treating Sludge

污泥高固厌氧消化具有反应器体积小、能耗低、沼渣少等优点,但其相关机制尤其是微生物机制研究还非常有限.利用16S rRNA克隆文库技术,本研究考察了一个中试污泥高固厌氧消化系统稳定运行期的微生物群落.该中试系统采用"超高温酸化(70℃)-高温甲烷化(55℃)"的强化两相厌氧消化工艺,处理剩余活性污泥的含固率约为9%.在总的固体停留时间仅15.5 d(酸化3 d+甲烷化12.5 d)时,系统挥发性固体(volatile solid,VS)去除率为35.7%,甲烷产率(以CH4/VS去除计)为0.648 m^3·kg^(-1).两相的细菌组成差异较大:在超高温酸化相存在大量降解蛋白质/氨基酸的细菌;在高温产甲烷相则主要是降解纤维素等多糖和一些简单糖类的细菌以及长链脂肪酸降解细菌;两相中都存在降解简单糖类的细菌.两相的古菌绝大部分都属于Methanothermobacter,特别是高温产甲烷相检出的古菌100%都属于Methanothermobacter,由于仅在产甲烷相检测到沼气,这表明系统中的甲烷化过程主要通过氢营养途径进行.

High-solid anaerobic digestion（HSAD） of sludge has several advantages like smaller reactor,lower energy consumption and less digestate. However,the understanding about the mechanism especially the microbial mechanism is still limited. In this study,microbial communities of a pilot-scale sludge HSAD system at steady state were investigated with 16 S rRNAclone library technology.The system employed an enhanced two-phase anaerobic digestion process,i. e. ‘hyperthermophilic acidogenesis（70℃,3 d）-thermophilic methanogenesis（55℃,12. 5 d） ＇to treat waste activated sludge with a solid content of about 9%. The volatile solid（VS） removal rate was 35. 7% and methane yield（CH4/VSremoved） was 0. 648 m^3·kg^-1. The bacterial compositions of the two phases were significantly different： there were plenty of proteolytic bacteria in hyperthermophilic acidogenesis phase; and the bacteria degrading polysaccharides like cellulose and the bacteria utilizing long-chain fatty acids were found in thermophilic methanogenesis phase; some bacteria degrading simple saccharides existed in both phases. In both phases, the dominant archaea were Methanothermobacter. Especially,100% of the retrieved archaea in the thermophilic methanogenesis phase belonged to genus Methanothermobacter. This indicated that hydrogenotrophic methanogenesis was the predominant methanogenesis pathway in this system since methane was only detected in the methanogenesis phase.