Bioethanol Production from Bitter Yam (Dioscorea dumetorum) and Water Yam (Dioscorea alata) Peels

Bioethanol which is an alternative source of fuel to fossil fuels can be produced from renewable crops. However, some of these renewable feedstocks are food competitive. Hence, this study therefore investigated the production of bioethanol from bitter yam and water yam peels. Strains of Aspergillus spp and Saccharomyces cerevisiae were obtained from the Microbiology laboratory of the University and characterized using morphological characteristics. The spores of Aspergillus tamarii and colonies of Saccharomyces cerevisiae were cultured in bitter yam and water yam medium using the bitter and water yam peels as substrates for ethanol production at substrate concentrations of 5 – 30 %, temperature range of 25 - 45 oC, agitation speed of 60-160 rev/min and pH range of 4.0 - 8.0. Optimum bioethanol yield of 13 % was obtained with bitter yam peels at substrate concentration of 20 %, temperature of 35 oC, agitation of 100 rev/min and pH of 7.0. Similarly, optimum bioethanol yield of 11 % was obtained with water yam peels at substrate concentration of 20 %, temperature of 35 oC, agitation of 100 rev/min and pH of 5.0. Bioethanol yield from bitter yam peels was observed to be higher than that of water yam peels at substrate concentration of 20 %, temperature of 35 oC, agitation of 100 rev/min and pH of 7.0. This study shows the potential of bitter yam and water yam peels as substrates for the biosynthesis of ethanol which can serve as alternative source of fuel