Numerical Modelling and Optimization of Bioethanol Concentration Produced from Local Sawdust following Response Surface Methodology

Abstract

This work studies the modelling and optimization of bioethanol production from locally sourced saw dust waste. The saw dust samples are obtained from common wood species in the Nigerian tropical rain forest. Nigeria is one of the producers of wooden products in the world. Many species of wood can be found in Nigeria’s tropical rain forest. Some of the most common wood species include; Astonia boonei (duku), Bombax bounopozense (West African bombax), Brachystegia eurycoma (Okwen), Terminalia superba (White afara). Sawdust samples were obtained from a local saw mill in Edo State, Nigeria. The samples were pre-treated, hydrolyzed, fermented and the bioethanol distilled out. Optimization of bioethanol was performed by using Central Composite design of response surface methodology. Four variables such as acid concentration, hydrolyzing time, hydrolysis temperature and fermentation time were considered as influencing factors on the yield of bioethanol. The optimization of ethanol was investigated in this study under the following conditions: acid concentration (0.5-2.5 %w/w), hydrolysis temperature (100-130 °C), hydrolysis time (10-50 minutes) and fermentation time (2-6 days). It was observed from the statistical analysis that the maximum ethanol yield of 24.85 % (g/L) was obtained at optimum acid hydrolysis of acid concentration 2.0 %w/w, Hydrolysis time 40 minutes, Hydrolysis temperature 122.50 °C, and Fermentation time 5 days.