Optimization Of Dilute Acid Hydrolysis For Bioethanol Production From Selected Agricultural Wastes
Amina Ahmed El-Imam, Aishat Ajibola Rufai, Florence Oladeji, Latifa Saidu, and Eromosele Ighalo
Keywords: Bioethanol, optimisation, Hydrolysis, Food waste, Valorisation.
The potential of bioethanol production from selected agricultural wastes (cassava peels, corn bran and millet bran) was investigated in this study. Firstly, yeasts were isolated from rotting orange and subjected to ethanol tolerance screening. Next, the substrates were subjected to dilute acid hydrolysis using different concentrations of HNO3 (3 %, 4 % and 5 %) at 20 % solid loading and then autoclaved at 121 oC for 30 minutes. Dilute acid optimisation yielded varying amounts of reducing sugars. The 3 %, 4 % and 5 % HNO3 solutions produced hydrolysates with the highest amounts of reducing sugars of 19.28 g/L, 16.36 g/L and 7.59 g/L from cassava peels, corn bran, and millet bran, respectively. Hydrolysate fermentation resulted in bioethanol concentrations of 7.73 g/L from cassava peels hydrolysate, 8.98 g/L from corn bran hydrolysate and 1.69 g/L from millet bran hydrolysate. This study demonstrates that various hydrolysates require different concentrations of catalyst for optimum sugar release. It also shows that bioethanol can be produced from millet bran and other abundant biomass, thus contributing valorising them.