Bioethanol production from sago pith waste using microwave hydrothermal hydrolysis accelerated by carbon dioxide

Bioethanol production from sago pith waste (SPW) using microwave hydrothermal hydrolysis accelerated by carbon dioxide was studied. The structural change in the SPW after hydrolysis, ethanol purity after fermentation, and distillation were investigated. Energy consumption for microwave hydrothermal hydrolysis was evaluated. A maximum of 43.8% theoretical glucose and 40.5% theoretical ethanol yield were obtained. The ethanol yield coefficient obtained in fermentation was 0.47 (gethanol per gglucose) which was 15.6gethanol per 100g dry SPW. It was also discovered that the lowest energy consumption occurred when energy input was fixed at 108kJ (900W for 2min), amounting to 33kJ and 69kJ to produce one gram glucose after hydrothermal hydrolysis and one gram ethanol after fermentation, respectively. The developed technique for SPW resulted in higher energy saving compared to previous techniques in the absence of enzymes, acid or base catalyst.