Optimization of Bioethanol Production from Sawdust and Brewery Spent Grain

Abstract

The choice of bioethanol as an alternative energy source is due to the high rate of depletion of the non-renewable energy source. Hence, this study investigated the production of bioethanol from Brewery Spent Grain (BSG) and Sawdust. Strains of Aspergillus spp and Saccharomyces cerevisiae were selected and characterized using morphological indices. The spores of Aspergillus flavus and colonies of Saccharomyces cerevisiae were cultured in a liquid fermentation medium containing brewery spent grain (BSG) and sawdust as substrates for bioethanol production. The process was optimized at pH range 4 - 8, temperature range 30 - 50 °C and substrate concentration 5-30 % for 96 h. Optimum bioethanol yield of 14 % was obtained from BSG at substrate concentration of 25 %, at temperature of 35 oC and pH 4.0. However, optimum bioethanol yield of 10 % was obtained with saw dust at substrate concentration of 25%, temperature of 35 oC and pH 6.0. Thus, there was an increased yield of bioethanol from BSG than sawdust. This study shows the potentials of Aspergillus flavus and Saccharomyces cerevisiae in the production of bioethanol from sawdust and BSG.