Sustainable Bioethanol Production from Lignocellulosic Plant Wastes: A Renewable Solution to Energy Challenges

Background: Lignocellulosic agricultural residues are increasingly investigated as renewable feedstocks for second-generation bioethanol production because they support waste valorization and reduce dependence on food-based substrates. Sugarcane bagasse is a cellulose-rich agro-industrial residue, but its conversion into ethanol is restricted by lignin-associated biomass recalcitrance. Objective: This study evaluated bioethanol production from sugarcane bagasse using sodium hydroxide pretreatment, enzymatic saccharification, Saccharomyces cerevisiae fermentation, and ethanol recovery. Methods: Sugarcane bagasse was pretreated with 2.5% sodium hydroxide using autoclave-assisted treatment for 30, 60, and 90 min and microwave-assisted treatment for 10 and 20 min. Pretreated biomass was analyzed for cellulose and lignin content. Enzymatic saccharification was performed using cellulase from Trichoderma reesei, followed by batch fermentation using Saccharomyces cerevisiae. Ethanol was recovered by distillation and estimated spectrophotometrically using acidified potassium dichromate. Results: Autoclave-assisted pretreatment increased cellulose from 58.0% to 68.0% and reduced lignin from 30.7% to 11.9%. Microwave-assisted pretreatment produced the highest cellulose content of 71.0% and lowest lignin content of 8.0%. Saccharification absorbance was higher in the autoclaved sample than in the microwave-treated sample, 1.40 versus 1.20, and ethanol production was 2.0% versus 1.7%, respectively. Conclusion: Sugarcane bagasse supported laboratory-scale ethanol production after alkaline pretreatment, but the strongest delignification did not produce the highest ethanol concentration. Optimization of hydrolysis, fermentation, and ethanol yield assessment is required.