The Influence of Enzymatic Pretreatment and Food to Microorganism (F/M) Ratio to Biogas Production from Rice Husk Waste During Solid State Anaerobic Digestion (SS-AD)

Solid-state anaerobic digestion (SS-AD) generally occurs at solid concentrations higher than 15. In contrast, liquid anaerobic digestion (AD) handles feed stocks with solid concentrations between 0.5% and 15%. In this study, the effect of Food to Microorganisms (F/M) content to biogas production from rice husk by solid state anaerobic digestion (SS-AD) was investigated. The laboratory scale of anaerobic digestions used in this experiment was operated in batch system and at room temperature. Carbon to Nitrogen (C/N) ratio and total solid (TS) was set at 25 and 21%. Food to Microorganism (F/M) was varied by adding certain percentage rumen fluid (TS 1.5%) to total solution required to adjust TS, i.e., 25, 50, 75, and 100% (correspond to F/M ratio 24.48, 10.12, 8.16, and 6.12). Enzymatic pretreatment was conducted using lignase enzyme. Biogas produced was measured by using water displacement method every two days. The highest biogas production was obtained at F/M 10.12. Specific biogas production on F/M of 24.48, 10.12, 8.16, and 6.12 were 8.03, 12.62, 11.71 and 11.78 ml/gr (TS), respectively. The further research need to be studied was optimization of enzyme concentration and others pretreatment.