Statistical Optimization of Fermentation Conditions for Bioethanol Production Using Palm Kernel Shells

A large amount of waste palm kernel shell is generated from palm oil processing. These waste residues are indiscriminately dumped, constituting nuisance to the environment. Palm kernel shell has great potential to be transformed into bio-based chemicals. This study focused on utilising palm kernel shell, an agricultural lignocellulosic biomass for bioethanol production. Raw shells were pretreated with 0.5% v/v H2SO4 acid solution at 100 ˚C for 30 minutes and 0.5 M NaOH alkaline solution at 120 ˚C for 20 minutes in an autoclave. The pretreated palm kernel shell was hydrolyzed at varied enzyme concentration of 10 -30 FPU/g for 72 hours at 50 ˚C. Fermentation was carried out on the hydrolysates at varied conditions of yeast concentration (1 – 5% v/v) temperature (25 – 35 ˚C) and time (24- 72 hours). Lowest glucose of 32.19 g/L at 10 FPU while highest glucose concentration of 39.78 g/L was obtained at enzyme concentration of 30 FPU. The conditions for maximum bioethanol production were 1.506% v/v, 35 ˚C and 70 hours for yeast concentration, temperature and time respectively. Analysis of variance showed that yeast concentration was significant for the fermentation process (p= 0.0186). These results confirmed the feasibility of transforming palm kernel shells to bioethanol.