BIOETHANOL PRODUCTION VIA FERMENTATION OF BANANA PEEL USING Saccharomyces cerevisiae

Abstract

Bioethanol derived from biomass contributed 10 to 14% of the total world energy supply and solved the world crisis such as global warming and depletion of fossil fuels. Therefore, this research is initiated to produce ethanol from biomass such as banana peel which was fermented bcy different concentration of substrates with 0.5% and 1% yeast in different fermentation period’s day, with the aim of optimizing the substrate concentration for ethanol production. The sample (Banana peel) was collected from Haramaya town, and cleaned with water vigorously before bringing it to the laboratory. Substrate pretreatment was carried out in 500ml conical flasks using dilute sulphuric acid. Among the different substrate concentrations, 40 grams of substrate produced more quantity of ethanol on the 12th day of fermentation. In acid pre-treatment, ethanol production was boosted as compared with the untreated substrate in all the treatments. The maximum ethanol production for 40 g untreated substrate was only 11.0%, whereas that of acid-pretreated was 18.8%. The reducing sugar contents decreased gradually as the fermentation period increased. Moreover, on the 4th day of the fermentation period, the highest reducing sugar concentration (5.3 mg/ml) was obtained from 40 gm of acid pre-treated substrate inoculated with 1% Saccharomyces cerevisiae, whereas the same substrate concentration showed 4.5 mg/ml in the untreated substrate. With an increased time of fermentation, the bioethanol yield and cell density also increased up to the 12th day of the fermentation. In this study, the effect of pre-treatment on bioethanol production was also investigated. The result showed that a 40 g substrate with 1% Saccharomyces cerevisiae showed an optimum ethanol production and the acid pre-treated samples yielded more ethanol than the untreated samples.