Optimization of bioethanol production from sawdust using Saccharomyces cerevisiae as a fermenting agent

Abstract

The growing demand for renewable energy has driven interest in bioethanol from lignocellulosic waste like sawdust. This study optimizes bioethanol production from sawdust via acid hydrolysis and fermentation using Saccharomyces cerevisiae. A Box-Behnken Design (Response Surface Methodology) optimized key parameters: acid concentration (2-10% v/v), temperature (40-50°C), pH (3.5-4.0), and time (30-120 min). The bioethanol was characterized using GC-MS, FTIR, and UV-Vis spectroscopy. Results showed a trade-off between hydrolysis and fermentation efficiency. The highest reducing sugar yield (118.6 g/L) was achieved at 10% acid, 45°C, pH 3.5, and 75 min. However, the maximum ethanol yield (88.4% v/v) occurred under different, milder conditions (6% acid, 40°C, pH 4.0, 120 min), suggesting that severe hydrolysis generates fermentation inhibitors. GC-MS confirmed the presence of ethanol alongside co-products like acetic acid. FTIR and UV-Vis analyses validated the alcohol functional groups and solvent properties. This study provides a foundation for converting sawdust into bioenergy, promoting waste valorization and a circular economy.