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Performance, granule conductivity and microbial community analysis of upflow anaerobic sludge blanket (UASB) reactors from mesophilic to thermophilic operation

Li, Heng, Han, Kezeng, Li, Zhipeng, Zhang, Jinfeng, Li, Hua, Huang, Yaohua, Shen, Liang, Li, Qingbiao, Wang, Yuanpeng
Biochemical engineering journal 2018 v.133 pp. 59-65
Geobacter, Klebsiella, Methanobacterium, Methanosaeta, chemical oxygen demand, ethanol, glucose, high-throughput nucleotide sequencing, methane, methanogens, microbial communities, sludge, temperature, upflow anaerobic sludge blanket reactor
Effects of temperature variations from mesophilic to thermophilic on the performance of UASB reactors with glucose and ethanol as substrate were investigated. The reactor with ethanol as substrate had better resistance to temperature variations with over 93% COD degradation rate and 75% methane content. The conductivity of granular sludge that degraded ethanol was also considerably higher. High-throughput sequencing indicated that the abundance of Methanobacterium decreased, while Methanosaeta increased with increasing temperature. Moreover, the abundance of Geobacter and Methanosaeta were higher in the reactor with ethanol as substrate than that with glucose, whereas a higher abundance of Klebsiella was observed in the glucose reactor. More importantly, significant correlations were observed between granular sludge conductivity and COD removal rate (R2 = 0.73), between the abundance of Geobacter and COD removal rate (R2 = 0.895). These results indicate that the growth of Geobacter and Methanosaeta which promote transfer electrons in the manner of DIET in anaerobic methanogenic systems might alleviate the effect of temperature variation and facilitate reaction rate.