Ethanol Production from Gmelina arborea Wood Wastes by Saccharomyces cerevisiae using Submerged Fermentation

Abstract

Lignocellulose wastes are the most abundant residues on the surface of the earth. This project studies the possibility of ethanol production from a forestry waste. Wood wastes from Gmelina arborea were treated with dillute sulfuric acid to break down the lignin component. Fermentation for ethanol production was done using baker’s yeast (Saccharomyces cerevisiae ATCC 204508/S288c) for 120 hours using submerged fermentation, and the pH, reducing sugar, specific gravity and lignin content were determined using standard techniques. Ethanol concentration and yield were measured via vinometer and ethanol standard curve techniques. From the results, the highest pH was obtained at 72 hours of the fermentation period. The reducing sugar content and specific gravity decreased over the fermentation time . The acid-pretreated wood wastes gave a maximum ethanol concentration of 3.84 % and a yield of 7.60 ml/g as measured from the vinometer and ethanol standard curve methods at 72 and 96 hours of fermentation, respectively. About 13.6% v/v of ethanol was recovered from the distillation process employed to separate the components of the product generated after fermentation. The observations in this research reveal the possibility of producing ethanol from G. arborea wood wastes and under optimized culture conditions. This could serve as an alternate means of biofuel generation and hence value addition to the wastes.

Keywords: Gmelina arborea, Saccharomyces cerevisiae, Ethanol, Submerged fermentation