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Temperature has different effects on anaerobic digestion (AD) of various biomasses, which could bring out changes in microbial communities. The relationship between microbial community and methane production at 35 °C (R35), 38 °C (R38), 41 °C (R41), and 44 °C (R44) was analyzed during AD of corn stover (CS). The results showed that the daily biogas and methane production from R44 were 16.6%–42.4% and 16.2%–40.6% higher than yields from R35, R38 and R41, respectively. The abundance of Bacteroidetes in R35, R38 and R41 was relatively close (30.70%–39.36%), which was low in R44 (16.00%). The abundance of Firmicutes in R35 was 32.30%, however, Firmicutes was the most dominant phylum at R44 (66.58%). The abundance of Miscellaneous_Crenarchaeotic_Group and Euryarchaeota were 54.63 ± 6.47% and 44.43 ± 6.73% across all digesters. This research demonstrated that among all temperatures studied, 44 °C could enhance the conversion efficiency of the substrates to methane and be recommended for better conversion of CS in AD process.

Several completely stirred tank reactors (CSTR) connected in series for anaerobic digestion of corn stover were investigated in laboratory scale. Serial anaerobic digestion systems operated at a total HRT of 40 days, and distribution of HRT are 10 + 30 days (HRT10 + 30 d), 20 + 20 days (HRT20 + 20 d), and 30 + 10 days (HRT30 + 10 d) were compared to a conventional one-step CSTR at the same HRT of 40 d. The results showed that in HRT10 + 30 d serial system, the process became very unstable at organic load of 50 gTS·L−1. The HRT20 + 20 d and HRT30 + 10 d serial systems improved methane production by 8.3–14.6% compared to the one-step system in all loads of 50, 70, 90 gTS·L−1. The conversion rates of total solid, cellulose, and hemicellulose were increased in serial anaerobic digestion systems compared to single system. The serial systems showed more stable process performance in high organic load. HRT30 + 10 d system showed the best biogas production and conversions among all systems.