The effect of rumen and mixed microorganism (rumen and effective microorganism) on biogas production from rice straw waste

The world's fossil fuel sources are rapidly diminishing. Nowadays, the research and development of renewable energy is very important and using lignocellulosic materials to make biogas are the potential one. Rice straw waste was very potential lignoselulosic material because Indonesia has a lot of rice straw waste excessively. Microorganisms that can degrade cellulose, lignocellulose and hemicellulose are needed to produce biogas from rice straw waste. In this study, rumen microorganism and the combination between rumen and effective microorganism were used as a new hypothesis, and effective microorganism was rarely used in former study. The aim of this study was to compare the effect of rumen microorganism and the combination between rumen and effective microorganism to convert lignocellulosic biomass to a good quality of methane and high productivity rate. The digestion was done in a 6 liters batch digester with 60% working volume in 21 days, at 30-40oC, pH 6-7 and 1 atm. Cow dung microorganism was used as control microorganism. The highest yield and production rate of methane in 21 days were 0.6111 Nm³/kgCOD_removal and 0.02505 Nm³/day respectively in 15% (v/v) of rumen. Meanwhile in 10% (v/v) microorganism combination, the yield and production rate were 0.365 Nm³/kgCOD_removal and 0.00059 Nm³/day. Heating value was analyzed after stationary phase and the highest heating value was 744.72Btu/Scf in 5% (v/v) of rumen. Combustion test showed that the fire was blue. It shown that the gas produced has good quality and it can be concluded that rumen microorganism is better than microorganism combination based on the yield, production rate and quality of the biogas.