Anaerobic digestion performance and microbial community structure of corn stover in three-stage continuously stirred tank reactors

[Display omitted] •TSAD combined the process of two-stage with serial CSTR anaerobic digestion.•Mitigation of negative effect caused by serial CSTR at high OLR was verified in TSAD.•Methane yield in TSAD was increased by 23.5–50.5% compared with the one-stage AD.•Methanobacteriaceae and Methanosarcinaceae were the predominant methanogens for TSAD. A new three-stage anaerobic digestion (TSAD) system combining the two-stage and serial continuously stirred tank reactor (CSTR) was developed for the high-efficiency anaerobic digestion (AD) of corn stover. At the same hydraulic retention time of 50 d and organic loading rate (OLR) of 1.8 g TS L−1 d−1, TSAD achieved a 33.2–50.5% higher methane yield than that of the traditional one-stage and two-stage AD. Moreover, the TSAD process showed higher buffering ability and system stability, relieving the negative impact of serial CSTR at high OLR. It was also found that the hydrogenotrophic methanogen Methanobacteriaceae and multi-function methanogen Methanosarcinaceae were dominant, and the populations of Ruminococcaceae and Syntrophomonadaceae with the function of acetogenesis were enriched in TSAD. The results demonstrated that TSAD could be a high efficient system for converting corn stover into bioenergy.