Effects of Agitating Intensity on Anaerobic Digestion Performance of Corn Straw Silage

Anaerobic fermentation can increase biomass energy use efficiency of crop straws and realizes win-win of energy and environment. This paper explored the biogas generation performance of anaerobic digestion of cow dung liquid as nitrogen source in three different levels of stirring intensity at 30℃ constant temperature condition. Through pH value, biogas production, chemical oxygen demand (COD), methane content, volatile fatty acid (VFA), principal component analysis (PCA) and modified Gompertz model, effects of agitating intensity on anaerobic digestion performance of corn straw silage were evaluated. Results indicate that the COD removal rate of three agitating intensity levels is higher than 85%, and pH value is about 6.5; the cumulative biogas production after 20 days is 2 h ＞ 4 h ＞ 1 h of agitating; in the 49th day, the biogas production is 1.9 L at 30 min / 2 h, 1.7 L at 30 min / 4h, and 1.6 L at 30 min / h; the maximum biogas production rate is 30 min / 2 h ＞ 30 min / 4 h＞30 min / h; and the maximum methane production rate is 30 min / 4 h ＞ 30 min / 2 h ＞ 30 min / h; in the same energy consumption, the biogas production at 30 min / 4h is higher than 1 h. In conclusion, overall analysis of energy consumption and economic factors indicate that 30 min/ 4 h agitating intensity is more suitable for straw biogas fermentation project. This study is expected to provide theoretical foundation for biogas fermentation project.