Effects of Farm Wastes Co-Digestion On Microbial Community, Methane Production, and Fiber Quality As Biorefining Feedstock

The performance of anaerobic digestion is highly correlated to the compositions of its substrate and microbes. A lab-scale anaerobic digestion process of a mixture of dairy manure and corn stover in continuous stirred-tank reactor (CSTR) was performed to investigate the influence of additional organic carbon on methane biogas production, lignocellulose-degrading efficiency, microbial community, and fiber quality of solid digestate for ethanol production. Highest biogas production of 3,158 mL day^-1 was observed at hydraulic retention time (HRT) of 40 days in the digester fed on manure and corn stover. Biogas productivity was closely correlated with the populations of polymer degrading bacteria Bacteroidetes (particularly Unclassified Bacteroidetes) and Clostridia, as well as methanogenic archaea such as Methanosarcina and Methanosaeta. The solid digestate (AD fiber) from co-digestion process showed better conversion efficiency in the enzymatic hydrolysis. Results also indicated that anaerobic co-digestion of corn stover and dairy manure significantly enhanced the energy balance of an integrated anaerobic digestion/bioethanol production process.