Optimization and Kinetic Modeling of Ethanol Production from Oil Palm Frond Juice in Batch Fermentation

Ethanol was produced from oil palm frond juice (OPFJ) by using Saccharomyces cerevisiae yeast cells. Experiments were operated in a batch mode by varying the oil palm age between 3-4, 4-7, 7-10, 10-20 and 20-25 years. Experimental results showed that OPFJ at 3-4 years gave the highest concentrations of glucose and ethanol as 31.26 and 11.50 g/l. Ethanol yield was 0.39 g-ethanol/g-glucose, which estimated as 76.47% of the theoretical yield (0.51 g-ethanol/g-glucose). Additionally, the Monod and modified Gompertz equations were used to describe the kinetics of substrate utilizationand product formation. The values of the kinetic parameters in Monod and modified Gompertz equations of OPFJ extracted from oil palm aged 3-4 years were evaluated: maximum specific growth rate (μ_max) was 0.29 g/g-VSS.hr, saturation concentration (K_s) 47.05 g/l, maximum ethanol concentration (P_m) 11.50 g/l, maximum ethanol production rate (r_p,m) 0.24 g./l.hr and lag phase 0.12 hr. Both models fitted well to the experimental data, which had the high regression coefficient values (R²>0.95).