An integrated approach to optimization of fermentation conditions for bioethanol production from local leftover Injera waste using central composite design

Background: Bioconversion of lignocelluloses to biofuel from cheap non-edible materials such as local leftover Injera waste for renewable energy is very important and minimizes environmental pollution. Local leftover Injera is an abundant, inexpensive, reusable waste to the environment, containing a sufficient amount of carbohydrate material, which is the best source of fermentable sugars. Methods: In this study, local leftover Injera was treated followed by drying, acidic hydrolysis, and alcoholic fermentation. Besides, the optimization of the fermentation process was done using a central composite box Behnken design. The process included physical and chemical pre-treatment of biomass, which was then followed by acid hydrolysis as a potential step. The scarification and fermentation methods were analyzed to acquire the maximum yield of ethanol. The local leftover Injera waste was pretreated with sulfuric acid and sodium hydroxide solutions. The effect of temperature, substrate concentration, as well pH on bioethanol production was optimized and studied. The optimization process was performed under special condition (temperature=25-40°C, pH=3-5, and substrate concentration=50-200 mg/L). Results: The maximum product of ethanol was achieved at a temperature of 32.718°C, substrate concentration of 125 g/L, and a pH of 4 with a maximum ethanol yield of 42.598%. Conclusion: According to the results, the optimum fermentation conditions for bioethanol production from local leftover Injera waste are the points where the maximum product of ethanol was achieved at a temperature of 32.718°C, substrate concentration of 125 g/L, and a pH of 4.