Optimization of Hydrolysis and process Conditions for Bioethanol Production from Spirogyra Biomass

Background: Bioethanol is gaining prominence as an eco-friendly alternative to fossil fuels, offering the potential to combat global warming and reduce greenhouse gas emissions. This study explores microalgae, specifically Spirogyra from Ajiwa Dam of Katsina State, Nigeria, as a third-generation biomass for bioethanol production. Methodology: To enable release of fermentable sugars, physical (Sonication and homogenization) and chemical (acid and alkaline) methods of pretreatment were employed. The influence of fermentation conditions (pH, temperature, and fermentation time) on ethanol yield was also evaluated using one-factor-at-a-time (OFAT) optimization. Results: Among the physical and chemical hydrolysis methods studied, the best ethanol yield was observed with acid hydrolysis by H2SO4 (2 N), at 121 ˚C for 30 min with dried biomass. The result shows that the ideal parameters for optimum yeast growth and bioethanol yield of S. cerevisiae are at pH 5.5, 35 ℃ temperature, and a harvesting time of 72 hrs. The physicochemical characteristics were found to be comparable to the ASTM standard and those of commercially available ethanol, respectively. Conclusion: The promising yield obtained in this study suggests that spirogyra biomass can be used as a renewable fermentation feedstock for bioethanol production, as an alternative to lignocellulosic biomass.