High-solid enzymatic hydrolysis of sugarcane bagasse and ethanol production in repeated batch process using column...

Area of Science:

• Biotechnology
• Renewable Energy
• Biorefining

Background:

• Sugarcane bagasse is a lignocellulosic biomass abundant in Brazil.
• Alkaline sulfite pretreatment enhances bagasse's enzymatic digestibility.
• Efficient conversion of biomass to biofuels is crucial for sustainable energy.

Purpose of the Study:

• To evaluate packed-bed and bubble column bioreactors for ethanol production from sugarcane bagasse hydrolysate.
• To optimize fermentation conditions using Saccharomyces cerevisiae and Scheffersomyces stipitis.
• To assess the potential of these bioreactors in biorefinery applications.

Main Methods:

• Alkaline sulfite pretreatment of sugarcane bagasse followed by enzymatic hydrolysis in column reactors.
• Fermentation of hydrolysate using Saccharomyces cerevisiae and Scheffersomyces stipitis under varying aeration rates.
• Evaluation of successive repeated batch fermentations.

Main Results:

• Optimized solid loading (9%) in the column reactor yielded 41 g/L glucose with 87% cellulose hydrolysis.
• Saccharomyces cerevisiae achieved higher ethanol yield (0.40 g/g) and productivity (1.58 g/L/h) at 0.5 vvm aeration.
• Scheffersomyces stipitis showed maximum productivity at 0.5-0.7 vvm aeration.
• Repeated batch fermentation with S. cerevisiae reached 38 g/L ethanol and 82% efficiency.

Conclusions:

• Both packed-bed and bubble column bioreactors are effective for ethanol production from sugarcane bagasse.
• Optimized fermentation parameters are key to maximizing ethanol yield and productivity.
• The demonstrated systems show promise for integration into industrial biorefineries.