Bioethanol production from agricultural wastes

In this study, different strains of Saccharomyces cerevisiae have been screened for the ability of bioethanol production. Yeasts were grown in synthetic liquid medium containing two different substrates: sucrose at different concentrations (10 to 400g/l) and cane molasses (120g/l of sucrose). The screening was made in batch regime and the growth rates, ethanol and biomass productions were determined. The results indicate a flocculent yeast strain – F as the more suitable microorganism to produce ethanol, presenting the highest value of growth rate (0.49h -1 ) and ethanol yield (0.40g/g) with 120g/l of sucrose concentration. In addition, ethanol production was also studied in a continuous process with the selected yeast strain (F strain), with sucrose and cane molasses (120g/l) at different dilution rates (0.05-0.5 h -1 ). Data showed that when dilution rate raised to 0.4h -1 the highest sugar conversion, 85% and 90%, were achieved with an ethanol production of 40.5g/l and 50.8g/l for sucrose and molasses, respectively.