The effect of enzymatic pretreatment and c/n ratio to biogas production from rice husk waste during solid state anaerobic digestion (SS-AD)

Rice husk is one of agricultural waste generated from the mill is potential to be converted to biogas. Otherwise, biogas production facing problem due to the high lignin content. This research is objected to study the effect of enzymatic pretreatment and C/N ratio to biogas production from rice husk by solid state anaerobic digestion (SS-AD). The laboratory scale-anaerobic digestions was used in this work. It is operated in batch system and with room temperature. Total solid (TS) was set 21%. Enzymatic pretreatment was conducted using lignase enzyme. Carbon to Nitrogen (C/N) ratio was varied from 20, 25, 30, and 35. The C/N ratio is varied by adding some quantity of technical urea to the substrate. Biogas formed was measured using water displacement method in every two days. The result showed that enzymatic pretreatment could increase biogas production from 30 to 55%. The highest biogas production was obtained at C/N ratio 35. Specific biogas production on C/N ratio of 20, 25, 30, and 35 were respectively 12.0, 12.6, 13.5 and 18.2 ml/gr TS. The volumetric loading resulted by SS-AD was higher than liquid anaerobic digestion (L-AD). The further research need to conduct for optimization the enzyme concentration and C/N ratio.