Comparative Studies on Bioethanol Production from Some Sugar Based Agricultural Wastes

Abstract

The suitability of some sugar-based agricultural wastes (pineapple peels, banana peels, and plantain peels) were examined for bioethanol production. They were subjected to different physico-chemical pretreatments in order to identify the most effective process and optimize the yield of bioethanol. They were further hydrolyzed by cellulase enzymes from Trichoderma ressei micro-organism isolated from the soil. The various hydrolysates obtained were subsequently fermented to bioethanol using co-cultures of Pichia stipitis and Saccharomyces cerevisiae fermentative yeasts. Separate hydrolysis and co-fermentation (SHCF) and simultaneous saccharification and co-fermentation (SSCF) methods were adopted and their bioethanol yields compared. The fermentation results revealed that the maximum bioethanol yields for pineapple peels, banana peels, and plantain peels were 4.94, 3.85, and 4.57 (% w/v wet biomass) respectively at 72 hours fermentation period. SSCF strategy was observed to be more effective as it gave better bioethanol yields in all the considered substrates and was less time consuming. Mixed cultures of Trichoderma ressi, Pichia stipitis and Saccharomyces cerevisiae through SSCF process resulted to a better fermentation yield when compared with previous studies by other workers.