Impact of Glucose Supplementation on ABE Yield in Simultaneous Saccharification Fermentation of corn stover

Abstract

Energy sources and supply in Nigeria and the world at large are major concerns, ranging from its shortage or low availability to its effects on the environment. Advances have been made in obtaining more environmentally friendly sources of fuel which would be useful for various domestic, industrial, and commercial purposes. This work takes a shift from the usage of food crops in biofuel production, holding to the fact that continuous usage of food crops tends to bring about a shortage of food crops and the high cost of their purchase. The research evaluated the potential of the production of biobutanol fuel from simultaneous saccharification and fermentation (SSF) of corn stover with glucose supplementation. The optimum pretreatment condition using acid pretreatment was analyzed using the respond surface methodology (RSM). It was found to be at a temperature of 124 °C, a time of 20 minutes, and an acid concentration of 0.92M H₂SO₄. Corn stover was pretreated using this condition and then followed by SSF using cellulase enzyme and Clostridium acetobutylicum. A comparative study was carried out between SSF and SSF with glucose supplementation and a standard refractometer was used to determine the final alcohol content in the broth of both media. After 96hrs, SSF with no supplementation had a 5.6% alcohol content in its broth, while SSF with glucose supplementation had an alcohol content of 20.65%. The result suggests that greater sugar yield, up to an optimum point, from the saccharification part of the SSF would produce higher alcohol content in the broth.  The sugar yield of 80.2% as well as the cellulose and hemicellulose contents of 30% and 41.2% respectively also reveals the feasibility of using corn stover in biofuel production. Similarly, the coefficient of determination (R²values) of sugar yield in the adjusted and predicted values of 0.9761 and 0.9421 as well as that from the standard glucose curve of 0.9252, all show the suitability and adaptability of this model and parameter conditions.

Index Terms: Acid pretreatment, Biobutanol, Cornstover, Fermentable sugar, Lignocellulosic biomass, Simultaneous Saccharification and Fermentation (SSF).