OPTIMIZED PRODUCTION OF BIOETHANOL BY FERMENTATION OF ACID HYDROLYZED-CORN STOVER EMPLOYING SACCHAROMYCES CEREVISIAE YEAST STRAIN
In this study, corn stover was converted into ethanol using a locally-fabricated bioreactor and process conditions were optimized. The corn stover biomass used as substrate was milled, screened to 200 μm and hydrolyzed with between 0.1-0.5 M HCl. The hydrolysis experiment was carried out for substrate concentrations of 20, 25, and 30% (w/v) of milled bagasse prepared in a 1000 mL glass jar containing distilled water. For each substrate concentration, the time, temperature, and acid concentration were varied between 10 – 60 min., 80 – 97 °C, and 0.1 – 0.5 M, respectively to find the optimum glucose yield. Glucose concentration in the optimum hydrolysate sample was determined using glucose oxidase method. Fermentation experiment was conducted in the bioreactor using 700 ml of the hydrolysate and Saccharomyces cerevisiae supplemented with minerals to yield ethanol of 21.47 g/L after 48 hours. A linear regression model developed after analysis of variance was able to predict the concentration of glucose produced during the acid hydrolysis, and the optimum ethanol yield of 21.47 g/L compares well with previous reported yield values found in literature.