Production Of Bioethanol From Wheat Straw By Using Locally Isolated Yeast

Abstract

Production of ethanol from utilized renewable resources such as crop residue can be used as an alternative energy sources .There for, the objective of this work was to use wheat straw sample collected from Wellega Zone, to evaluate bioethanol production potential of wheat straw by using locally isolated yeast. S. cereviciae prepared from teff flour was used for fermentation. Samples were air dried and ground to particle size less than 2.0 mm for proximate and chemical composition analysis. The ethanol production processes were carried out in four main stage such as pretreatment, hydrolysis, fermentation and distillations. For hydrolysis, the three factorial design 2×2×2 was applied to investigate the effect of the weight of the sample (50 and 70g), reaction time of (30 and 60min) and sulfuric acid of concentration (1% and 5%) with a solid to liquid ratio of 1:10 . The fermentation process was held at temperature of 30oC and pH of 5, and treated using different acid concentrations and residence times. The results showed that maximum total sugar concentration 13.66% was obtained at a hydrolysis time of 60 minutes and acid concentration of 5%. In the process, it was observed that ethanol concentration increased with an increase in acid concentration, hydrolysis time and weight of the sample . Under these conditions, maximum bioethanol concentration production was 11% by volume, a maximum result as compared with literature data. Chemical characterization of the bio-ethanol produced as detected by FTIR confirmed the presence of O-H, C-O, -CH2, and CH3 functional groups in the ethanol produced, which indicate the presence of ethanol in the product. In conclusion, the results indicated that being available in plentiful amounts and non-edible material, wheat straw would be potential feedstock for bioethanol production in Ethiopia.