Batch Fermentation of Bioethanol from the Residues of Elaeis guineensis: Optimization and Kinetics Evaluation

Bioethanol was produced by Saccharomyces cerevisiae using oil palm trunk (OPT) sap supplemented with palm oil mill effluent (POME) in a shake flask culture. Four variables namely OPT sap to POME ratio, inoculum size, pH and incubation time were chosen to investigate their effects on production of bioethanol using One -Factor -at -a -Time (OFAT) method. The optimum process conditions were found to be at OPT sap to POME ratio of 30:20 and inoculum size of 4% v/v. The fermentation process exhibited better result in slightly basic media. The bioethanol concentration at the optimum condition was 12.52 g/l which equal to bioethanol yield of 44% g/g after four days of fermentation. It was found that the cell growth followed a sigmoidal trend. Logistic model, Luedeking-Piret model and Luedeking-Piret-like model were chosen and validated to describe the behavior of dry weight of the biomass, bioethanol production and glucose consumption, respectively. All selected models fitted well to experimental data, proven by high R2 values (>0.9) and low RMSE values.