Effect of Exogenous Biological Enhancement on Methane Production Characteristics of Aerobic-anaerobic Two-phase Fermentation of Rice Straw

The aerobic hydrolysis process of rice straw was enhanced by biological reinforcement method, and the effects of green Trichoderma and its addition amount (3%, 5%, 7%, and 9% of the total feed mass fraction) on its fermentation characteristics were studied. The biological enhancement time in the aerobic hydrolysis reactor was 24 h, followed by anaerobic fermentation methane production potential testing under 35°C conditions. The results showed that compared with the control group, the addition of Trichoderma viride for biological enhancement resulted in varying degrees of improvement in the degradation rate of lignocellulose, production of volatile fatty acids (VFAs), and gas production rate in each group, with acetic acid being the main component of VFAs. The cumulative methane production was fitted by using Modified Gompertz, and the fitting results were good. The cumulative methane production of each pre-treatment experimental group with 3%, 5%, 7%, and 9% addition of Trichoderma viride was 198. 28 mL/g, 211. 351 mL/g, 228. 44 mL/g, and 234. 78 mL/g, respectively. Compared with that of the CK control group, the methane production was increased by 18.89%, 26.72%, 36.96%, and 40. 76%, respectively. The results showed that the comprehensive effect of adding 7% Trichoderma viride was the best. Under these conditions, the degradation rates of hemicellulose, cellulose and lignin were 36.86%, 31.57%, and 7.43%, respectively, and the methane production was increased by 36.96%. The dominant bacterial communities during aerobic hydrolysis were Firmicutes, Chloroflexi, Proteobacteria, and Bacteroidetes. Among them, the relative abundance of Firmicutes was decreased with the prolongation of hydrolysis time, while the relative abundance of Chloroflexi and Bacteroidetes was increased, indicating that the addition of microbial agents could change the structure of bacterial communities and promote the progress of aerobic hydrolysis reaction. © 2024 Chinese Society of Agricultural Machinery. All rights reserved.