Differences of methanogenesis between mesophilic and thermophilic in situ biogas-upgrading systems by hydrogen addition
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To investigate the differences in microbial community structure between mesophilic and thermophilic in situ biogas-upgrading systems by H2 addition, two reactors (35 °C and 55 °C) were run for four stages according to different H2 addition rates (H2/CO2 of 0:1, 1:1, and 4:1) and mixing mode (intermittent and continuous). 16S rRNA gene-sequencing technology was applied to analyze microbial community structure. The results showed that the temperature is a crucial factor in impacting succession of microbial community structure and the H2 utilization pathway. For mesophilic digestion, most of added H2 was consumed indirectly by the combination of homoacetogens and strict aceticlastic methanogens. In the thermophilic system, most of added H2 may be used for microbial cell growth, and part of H2 was utilized directly by strict hydrogenotrophic methanogens and facultative aceticlastic methanogens. Continuous stirring was harmful to the stabilization of mesophilic system, but not to the thermophilic one.
KeywordsIn situ biogas upgrading Homoacetogens Strict aceticlastic methanogens Hydrogenotrophic methanogens Syntrophic acetate-oxidizing bacteria
The data were analyzed on the free online platform of Majorbio I-Sanger Cloud Platform (www.i-sanger.com).
This research was supported jointly by the National Key R & D Program of China (2018YFD0501405), West Light Foundation of Chinese Academy of Sciences (2018XBZG_XBQNXZ_A_004), Youth Innovation Promotion Association of CAS (2017423), Special fund for talented persons of Sichuan provincial Party Committee Organization Department, Key projects for foreign cooperation of International Cooperation Bureau of Chinese Academy of Sciences (182344KYSB20170009), Science and Technology Service Network Initiative (STS) of CAS (KFJ-STS-QYZD-117).
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Conflict of interest
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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