15-09: ALKALINE HYDROGEN PEROXIDE PRETREATMENT OF CASHEW APPLE BAGASSE FOR ETHANOL PRODUCTION: STUDY OF PARAMETERS

Pretreatment is a critical step in the conversion of lignocellulose to fermentable sugars. Although many pretreatment processes are currently under investigation, none of them are entirely satisfactory in regard to effectiveness, cost, or environmental impact. The use of alkaline hydrogen peroxide (AHP) at pH 11.5 was to be an effective pretreatment of grass stovers and other plant materials in the context of ethanol production. In this context, explored several key parameters to test the potential of AHP for further improvement relevant to lignocellulosic ethanol production using cashew apple bagasse as substrate. In the Northeast of Brazil, the cashew agroindustry has an outstanding role in the local economy and the cashew apple bagasse (CAB) appears as an alternative raw material. In the present study, conditions for obtaining a high sugar yield from bagasse cashew apple using alkaline hydrogen peroxide as pretreatment option and enzymatic saccharification were studied.  The effects of biomass loading (2, 5 and 10% m/v), hydrogen peroxide loading (0-5.0%, v/v), residence time (6, 12 and 24h), and pH control were tested in combination with subsequent digestion with a commercial enzyme. AHP pretreatment was performed at 35°C and atmospheric pressure, and after AHP pretreatment the biomass was washed and neutralized with HCl before enzyme digestion. The enzymatic hydrolysis was carried out at 45°C using biomass loading of 1g cellulose/100 mL solution, 150 rpm and pH 5.0 using a commercial enzyme. Results showed that alkaline hydrogen peroxide is an effective pretreatment for cashew apple bagasse.