Full Length Research Paper
Abreham Bekele, Ayana Fite, Me
Abstract
Ethanol is one of the bio-energy sources with high efficiency and low environmental impact. Various raw materials such as agricultural crops, industrial and domestic wastes can be used as carbon source for ethanol production. In the present study, potato peel waste discarded from University of Gondar, student Cafeteria was chosen as a sole carbon source for ethanol production using microbial liquefaction, saccharification and fermentation with sequential and co-culture techniques. Aspergillus niger and Bacillus species were used for hydrolysis while Saccaharomyces cerevisae of bakery and brewery yeast were used for fermentation of potato peel flour with 87% moisture content. The maximum crude supernatant (380mL) was obtained from sequential culture of bacillus sp. with bakery yeast whilst the minimum (74mL) was obtained from A. niger and brewery yeast. After distillation of 150mL of broth, the maximum ethanol distillate was obtained from sequential culture of A. niger and bakery yeast without autoclaving while the minimum was from bacillus and Brewery yeast. The ethanol concentration is maximum for autoclaved and non autoclaved sequential culture of A. niger and bakery yeast (42.5% and 41.3 % v/v respectively). The minimum concentration of ethanol (25.5) was obtained from co-culture of A. niger and brewery yeast followed by bacillus and brewery yeast (27% v/v). The standardized pure ethanol expected in mL was maximum for non autoclaved sequential culture of A. niger and bakery yeast (12mL) followed by autoclaved one (11.9mL). From this study, the use of sequential culture of A. niger and bakery yeast is far better than the other combination used interms of quantity of bio-ethanol.