Anaerobic digestion could treat organic wastes and recovery energy. Dry anaerobic digestion had advantages of low heating energy, small digester and less digestate, but its methane production was poor. In this study, an enhanced dry anaerobic digestion of swine manure (thermal treatment + dry anaerobic digestion) was proposed, and its feasibility was investigated via semi-continuous experiment. Results showed that methane production rates were 314.6, 416.0, 298.0 and 69.9 mL CH4/g VS at solid retention time (SRT) of 41 d, 35 d, 29 d and 23 d. Volatile solids (VS) removal rate and methane production rate could reached 71.4% and 416.0 mL CH4/g VS respectively at SRT of 35 d. Methane production rate of the enhanced dry anaerobic digestion was 390% higher than that of dry anaerobic digestion. Microbial study indicated that hydrogenotrophic methanogens predominated with the abundance of 90.2%, while acetoclastic methanogens were not detected. This process was feasible, and was of great practical importance.
Keywords: Dry anaerobic digestion; Methane production rate; Methanogenic pathways; Swine manure; Thermal treatment.
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