Effect of Ca(OH)2 pretreatment on biogas production of rice straw fermentation

Previous studies had shown that the digestibility of the lignocellulosic biomass and methane yield were increased with alkali pretreatment prior to anaerobic fermentation. To increase the economic viability of pretreatment technology and simplify operation, a self-designed laboratory-scale continuous anaerobic biogas digester was used in this study. Anaerobically digested slurry, Ca(OH)2 pretreatment, and anaerobic digestion were evaluated for biogas production from rice straw. The results showed that the lignin, cellulose and hemicellulose of rice straw were significantly degraded, and all pretreatments promoted biogas production. The Ca(OH)2 pretreatments exhibited higher biogas production than that of anaerobically digested slurry, and the highest biogas yield was obtained with 8% Ca(OH)2 treatment, which reached up to 14 374 mL, 100.91% higher than that of the control. The results show that rice straw fermentation with Ca(OH)2 pretreatment has the advantages of simple procedure, low cost and high biogas production. Therefore, pretreatment with lime can be applied in household biogasi?cation of rice and other crop straws.