ABSTRACT
The bioconversion of abundant and renewable cellulosic biomass into ethanol as an alternative to petroleum is gaining importance due to the realization of diminishing natural oil and gas resources. Agricultural and foresty plant residues are an abundant and renewable source of sugar substrates that could be fermented to ethanol. A thermochemical treatment of biomass in which both cellulose and hemicellulose are hydrolyzed to soluble sugar is necessary before yeast fermentation. After thermochemical treatment, cellulase enzymes must be introduced in the system to hydrolyze any remaining cellulose. The simultaneous saccharification and fermentation (SSF), is a method which converts agricultural residue to ethanol. In this investigation, pretreatment of rice husk was effected under, acid, alkaline and mixed treatment, which alkaline pretreatment showed higher biomass degradation. Production of enzyme complex (cellulase) was studied by fungal strain cultivation on pretreatment biomass,using Trichoderma reesei on alkaline pretreated rice husk. The biomass was then subjected to an SSF process, using the cellulase enzymes complex extracted from fungal culture and Saccharomyces cerevisiae yeast cells in batch scale fermentation sysrem. Ethanol production was evaluated by changing various parameters such as: substrate and enzyme concentration, corn steep liquor addition and inoculum percent under SSF conditions.
