Material balance studies for the conversion of sorghum stover to bioethanol

The conversion of lignocellulosic biomass to ethanol involves three major unit operations such as pretreatment, hydrolysis and fermentation. Each unit operation involves processing of biomass with changes in its structure, and release of fermentable and other sugars and lignin degrading compounds. The evaluation of biomass conversion processes through material balance is fundamentally crucial in its commercialization. This gives an idea about the transfer of biomass from one phase to another and hence eventually of the efficiency of the total process. In the present study, material balance has been evaluated in each unit operations for sorghum biomass to ethanol conversion. An account of carbohydrates in the native as well as pretreated sorghum biomass, the release of fermentable sugars and the conversion of sugars to ethanol was maintained and analysed. Ethanol yield of 91.94 g per kg sorghum was achieved without any detoxification and washing of pretreated biomass after mild acid pretreatment followed by enzymatic hydrolysis and fermentation.