Experiments on Anaerobic Digestion of Rice Straw for Biogas Production under NaOH Pretreatment

To discuss the effect of NaOH pretreatment technology for biogas production and methane (CH4) content enhancement during the anaerobic digestion of rice straw waste, a self-designed laboratory-scale continuous anaerobic biogas digester was used in this study. Anaerobic biogas slurry, NaOH pretreatment and anaerobic digestion were evaluated for biogas production from rice straw. The results showed that the peak value of biogas production was attained on the 16th day by using 6% NaOH pretreatment on rice straw. However, the highest CH4 content was 60.8% on the 24th day for the 4% NaOH-treated rice straw. The cumulative biogas production of 6% NaOH pretreatment was the highest, about 18 720 mL, which was followed by 8% NaOH (15 057 mL), 4% NaOH (12 103 mL), and 2% NaOH (10 754 mL).