Enhancing Bioethanol Production from Azolla filiculoides through Optimization of Pretreatment and Culture Conditions with Saccharomyces cerevisiae

Purpose: The increasing human population and extreme consumption of fossil fuels create the potential to generate alternative energy sources. Bioethanol is a renewable energy resource for fossil fuels and it can be produced from low-cost raw material. This study aimed to convert the low -value freshwater flora into highvalue bioethanol using Saccharomyces cerevisiae and to optimize the conditions for yield enhancement with the Azolla filiculoides substrate. Research Method: The freshwater flora were collected, cleaned, dried and then pre-treated with 1 M H2SO4 solution at 121 C for 15 min. The flora with significantly higher yields of reducing sugar and alcohol was chosen for further research. Three pre-treatment techniques, including acid (1 M H2SO4), enzymatic (1% alpha-amylase), and a combination of both (1 M H2SO4 and 1% alpha-amylase) were applied to the selected substrate. The technique that resulted in a significantly higher reducing sugar and alcohol yield was chosen. Findings: The study revealed that the Azolla filiculoides substrate produced significantly higher alcohol yield with Saccharomyces cerevisiae using a combination of chemical and enzymatic pre-treatment techniques. When fermentation was done at varying H2SO4 concentrations (0.50-1.75 M), fermentation time (12-60 h), temperature (20-45 oC), rotation speed (50- 250 rpm) and inoculum concentration (25-150 g/L), and significantly higher alcohol yield (19 times than the non -optimized) was obtained after 36 h, at 40 oC and 0.75 MH2SO4 concentration with an inoculum concentration of 75 g/L at 200 rpm. Originality/value: The study concluded that Azolla filiculoides can be used as an efficient raw material for alcohol production.