Effect of Microwave Pretreatment on Some Properties of Bamboo (Gigantochloa apus) for Bioethanol Production

Abstract

Pretreatment of lignocellulosic biomass plays an essential role in bioethanol production as an alternative biofuel. This process reduces biomass recalcitrance in order to improve cellulose digestibility for saccharification and further fermentation reactions. In this study, microwave (MW) pretreatment was done on bamboo (Gigantochloa apus) to investigate the resulting physicochemical properties and bioethanol produced. Bamboo was irradiated in the microwave at different power (100-600 Watt) and irradiation time (5-20 minutes) followed by Water Soluble content (WSC) and lignin analysis. Simultaneous saccharification and fermentation (SSF) using cellulase enzyme was also done in five different treatment combinations (C1-C5) to investigate the effect of produced reducing sugar and bioethanol. The result shows that increasing MW power and irradiation time could decrease WSC gradually. The lowest WSC of 0.3% was obtained at 600-Watt MW power and 20 minutes irradiation time. Lignin content decreased from 18.9% to 16.0% concerning increasing irradiation time from 5 to 20 minutes under 300-Watt MW power. SEM images show that partial disruption and micro-scale pores existed in pretreated samples. The highest amount of ethanol was obtained at 24 hours fermentation for pretreated bamboo at 300-Watt MW power for 15 minutes followed by cellulase enzyme addition. The overall results showed that microwave pretreatment is a prospective method for future bioethanol production from bamboo due to effective WSC reduction and lignin degradation in a relatively short period of time.