Biogas Production Performance and Dynamics of Anaerobic Digestion of Different Energy Grasses

Abstract:

Energy grass, as the second generation of new energy crops, has a brightly development prospect. Five kinds of energy grasses were selected as the raw materials. Their physicochemical characteristics were investigated together with the biogas production performances of anaerobic digestion in the process of laboratory scaled batch anaerobic fermentation at mesophilic temperature(35℃). And the dynamics of cumulative biogas production was analyzed. The results indicate that these energy grasses have good performances for the biogas production. But there are great differences in the relationship between the biogas production performances and the energy grass properties. The biogas yield and the lignin content are in a negative linear correlation, it means the lower is the lignin content of raw materials, the better is biogas production performance. The lignin content of Hybrid Pennisetum(24.88%) is higher for its long time growth, so it has a worse biogas production performance and the specific methane yield is only about 26.95% of the theoretical methane production. While the lignin content of Pennisetum purpureum cv.Huanan is lower, it has a better anaerobic digestion performance: the cumulative biogas yield, methane yield and methane content are 379.58mL/g, 228.55 CH4mL/g and 60.21%, respectively. By fitting the cumulative gas production curve, it was concluded that the energy grass digestion process of cumulative biogas production could be appropriately described by the modified Gompertz equation. This study provides a reference for the development and utilization of different energy grasses.