MILD ALKALINE PRETREATMENT APPLIED IN THE BIOREFINERY OF SORGHUM BIOMASS FOR ETHANOL AND BIOGAS PRODUCTION

摘要

Production of bioenergy from lignocellulosic biomass has gained more and more interest over the past years. Due to itshigh content in carbohydrates, Sorghum bicolor is one of the best suited candidate for bioenergy production. However,the lignocellulosic nature of the sorghum biomass raises difficulties to the access of the microbial enzymes to celluloseand hemicellulose and inhibits processes such as hydrolysis, fermentation and anaerobic digestion of biomass toproduce biofuels. In this study, the effects of thermo - chemical pretreatment (mild alkaline pretreatment), applied toimprove biodegradability of three different hybrids of sorghum biomass were investigated. Alkaline pretreatment havepositive effects on the production of lignocellulosic ethanol, increasing both cellulose and hemicellulose content whilebreaking the lignocellulosic bonds and reducing lignin content. The achieved methane yields ranged from 320 to 345 lnCH4/kg VS for the pretreated biomass, approximately 22% higher than the yields obtained from the untreated biomass.Important increase of methane production has been noticed as well in the case of anaerobic digestion of spent bagasseresulted after ethanol fermentation. Mild alkaline pretreatment is a suitable pretreatment method for conversion ofsorghum biomass to ethanol and biogas.