High solid fed-batch butanol fermentation with simultaneous product recovery: Part II-process integration.

Area of Science:

• Biochemical Engineering
• Biomass Conversion
• Sustainable Biofuels

Background:

• Sweet Sorghum Bagasse (SSB) is a lignocellulosic biomass rich in fermentable sugars.
• Pretreatment and enzymatic hydrolysis of SSB generate hydrolyzates suitable for biofuel production.
• Fermentation of SSB hydrolyzates can be inhibited by toxic compounds like acetic acid.

Purpose of the Study:

• To develop a fed-batch fermentation process for efficiently converting SSB hydrolyzates into acetone butanol ethanol (ABE).
• To overcome the limitations of batch fermentation caused by toxic chemicals in SSB hydrolyzates.
• To optimize ABE production using a fed-batch reactor with in situ product recovery.

Main Methods:

• Liquid hot water (LHW) pretreatment and enzymatic hydrolysis of SSB to produce hydrolyzates.
• Fed-batch fermentation using a reactor with simultaneous ABE recovery via vacuum.
• Controlled feeding of inhibitory hydrolyzate I after initial growth in hydrolyzate II.

Main Results:

• The fed-batch process successfully fermented SSB hydrolyzates, achieving complete sugar utilization.
• ABE productivity and yield in the fed-batch reactor were 0.44 g L^-1 h^-1 and 0.45, respectively.
• ABE yield was enhanced by the utilization of acetic acid for ABE conversion.

Conclusions:

• Fed-batch fermentation with in situ ABE recovery is an effective strategy for overcoming toxicity in SSB hydrolyzates.
• This integrated approach enables efficient conversion of lignocellulosic biomass into biofuels.
• The process demonstrates the potential for sustainable acetone butanol ethanol production from agricultural residues.