Previous studies showed that chicken manure and straws can be used as a feedstock in the production of methane during anaerobic digestions. The objective was to determine the best mixture of chicken manure and straw in the production of methane during anaerobic digestion. In this study the effect of three volatile solid (VS) rations on methane output, pH, hydrolase activity, and microbial community structure was determined. The optimal manure-straw VS ratio was M2 (9:1), where cumulative methane output reached a maximum of 227,660 ml kg -1 in 50 d. The cellulose activity was higher in the chicken manure to straw ratio of 9 than 4 or 1. The research showed that Megasphaera and Bacteroides were important cellulose-secreting bacteria. The results show: (a) during anaerobic digestion the cellulose and lignin contents were completely degraded; (b) protease, amylase, and lipase activities were higher in M2 (9:1) than M1 (1:0) or M3 (4:1); and (c) increasing amount of straw decreased bacteria and archaea diversity. Due to the addition of straw, the uniden-tified_Prevotellaceae had good physiological activity in the acidic environment between 5 and 30 d, Candidatus_Cloacimonas, unidentified_Lentimicrobiaceae, and Ruminiclostridium were the main archaea between 40 and 50 d.

Anaerobic digestion, one of the most currently remarkable techniques for biogas production, has provided a method of high organic solid waste disposal. Operating temperature, especially in the winter of northern city, makes biomass degradation less efficient. The microorganisms that take on the role of gas production are greatly affected by temperature. In our study, solar energy was selected for anaerobic digestion and winter was selected as the experimental environment. Anaerobic digestion was performed with solar heating and electric heating separately. Parameters were tested (pH, soluble chemical oxygen demand, total ammonia nitrogen, total volatile fatty acids), and microbial structure was monitored. The volume of methane produced was measured over 60 days. The methane yield differed by 15.92% under different conditions. It is clearly shown that methane yield can be improved by a steady temperature environment. Nevertheless, dominant bacteria and microbial structure did not seem to be much different. This study may provide more energy-saving ideas for winter anaerobic digestion projects in northern regions.