RESPONSE SURFACE OPTIMIZATION OF THE SIMULTANEOUS SACCHARIFICATION AND FERMENTATION PROCESS OF BIOETHANOL PRODUCTION FROM OIL PALM EMPTY FRUIT BUNCH

ABSTRACT

This study was carried out with the aim of enhancing the production of bioethanol from oil palm empty fruit bunch (OPEFB), through the strategic integration of cellulase and β-glucosidase to enhance enzymatic hydrolysis, alongside the optimization of the simultaneous saccharification and fermentation (SSF) process utilizing response surface methodology (RSM), thereby contributing to the advancement of sustainable biofuel production technologies. The study was carried out using three basic steps, pretreatment to disrupt the recalcitrant structure of lignocellulose and liberate cellulose, hydrolysis of cellulose to obtain fermentable sugars and fermentation of sugars to produce ethanol. Pretreatment step was carried out by subjecting OPEFB to sequential dilute acid/alkaline pretreatment using a 2% (v/v) solution of sulphuric acid (H2SO4) in an autoclave at 121˚C for 20 minutes followed by a 10 % (w/v) solution of sodium hydroxide (NaOH) in an autoclave at 121˚C for 20 minutes. The hydrolysis and fermentation steps were combined in the SSF process using cellulase and β-glucosidase for saccharification of sugars and saccharomyces cerevisiae yeast as the fermentative microorganism at a pH of 4.5. The Box Behnken Design (BBD) in RSM was used to investigate the optimal condition for bioethanol production from OPEFB. The three factors used for this optimization were fermentation time, yeast loading and diammonium phosphate concentration. Chemical pretreatment of OPEFB resulted in a cellulose yield of 64.52% with 15.35% and 20.13% yields of hemicellulose and lignin respectively. Investigation of enzymatic hydrolysis rate by cellulase and β-glucosidase resulted in the highest reducing sugar concentration after 48h of SSF. Optimization of bioethanol production using BBD resulted in a maximum reducing sugar concentration of 0.406703 g/L and bioethanol concentration of 11.601 %(v/v) at optimal conditions of 96 hrs fermentation time, 3.02 % (v/v) yeast loading and 0.57 %(w/v) (NH4)2HPO4 concentration