Production of Liquid Fuel from Rice Husk and Sawdust

Abstract

Energy is the key input to economic growth of a nation and there is a close relation between accessibility of energy and escalation in the quality of nation. As conventional energy sources are limited and will diminish in future after complete consumption, so it is the high time to deal with the renewable and non-conventional energy sources. The necessity of liquid fuel is not only in the transport sector rather it is required in industrial and power sector. Production of liquid fuel from ligno-cellulosic material is one of the sources of renewable energy. As Bangladesh is an agricultural country, rice husk and sawdust are the common sources among all sources of cellulosic material available in the country. In the present study, fermentation method is used to produce liquid fuel from rice husk and sawdust. For fermentation process simultaneous saccharification and fermentation (SSF) process being used. In the process, husk and sawdust was pretreated to neutralize it and then saccharification was carried out with cellulase enzyme with different proportion where temperature was maintained at around 37oC for 84 hours. Fermentation reagents were prepared by adding yeast, peptone and dextrose for yeast inoculums. Saccharified slurry was clutched to fermentation in a mixture of reagents and fermentation medium. The process was carried out for one day in aerobic condition and then next three days in anaerobic condition at a temperature of 35oC. After fermenting clear supernatant is obtained from centrifugation and then gas chromatography (GC) was performed on the product for estimation of ethanol. In the experimentation rice husk and enzyme mixture was added at the ratios of 2.5:1, 3:1 and 3.5:1 respectively. The yields of ethanol are respectively 9.55% (v/w), 8.73% (v/w) and 6.74% (v/w) from respective fermented liquid broth. Sawdust and enzyme ratio of 2.5:1 provide a very low about 1.23% (v/w) of ethanol. This shows that sawdust not prospective but rice husk is a prospective source of extraction of liquid fuel by fermentation.