Alkaline peroxide pretreatment of rapeseed straw for enhancing bioethanol production by Same Vessel Saccharification and Co-Fermentation

Alkaline peroxide pretreatment of rapeseed straw was evaluated for conversion of cellulose and hemicellulose to fermentable sugars. After pretreatment, a liquid phase called pretreatment liquid and a solid phase were separated by filtration. The neutralized pretreatment liquids were used in a co-fermentation process, with Saccharomyces cerevisiae and Pichia stipitis. The solid fraction was used for simultaneous saccharification and co-fermentation process in the same vessel. The effects of various operating variables were investigated. Pretreatment with 5% (v/v) H2O2 at 50°C for 1h was found to be the optimal pretreatment combination with respect to overall ethanol production. At this condition, 5.73g ethanol was obtained from pretreatment liquid and 14.07g ethanol was produced by co-fermentation of solid fraction with P. stipitis. Optimum delignification was observed when 0.5M MgSO4 was included in the pretreatment mixture, and it resulted in 0.92% increase in ethanol production efficiency.