Valorization of oil palm empty fruit bunch for bioethanol production through separate hydrolysis and fermentation (SHF) using immobilized cellulolytic enzymes

Abstract

Oil palm empty fruit bunch (EFB) is a lignocellulosic waste from oil palm industry. This biomass is composed of cellulose, hemicellulose, and lignin which could be a good feedstock for second-generation bioethanol production. The cellulolytic enzyme is one of important biocatalyst for conversion cellulose into glucose that subsequently could be fermented to ethanol. However, instability of enzyme is considered as a barrier for large-scale production. Enzyme immobilization is believed can obtain the high stability of enzyme. Therefore, this study explores the immobilization of cellulolytic enzyme on mixed Ca-alginate-activated carbon beads for separate hydrolysis and fermentation (SHF) process of EFB. The mixed of 3% w/v of sodium alginate and 3% w/v of activated carbon was used in immobilized enzymes. Variation of substrate concentration (50 g/L, 100 g/L, and 150 g/L) was conducted in this study. Hydrolysis process was carried out at 50°C, pH 4.8 and 150 rpm of agitation for 96 h. Furthermore, the hydrolyzate was fermented using yeast Saccharomyces cerevisiae to produce ethanol. As results, immobilized of cellulolytic enzyme could convert cellulose into glucose in hydrolysis. The highest glucose yield of 75.48% was provided from 150 g/L of substrate loading concentration. Furthermore, ethanol yield of 78.95% could be provided in fermentation process of 150 g/L of EFB. These results indicate the use of immobilized enzymes could be applied in hydrolysis for bioethanol production.