Attainable region analysis for continuous production of second generation bioethanol

Area of Science:

• Biochemical Engineering
• Renewable Energy Technologies
• Process Optimization

Background:

• Lignocellulosic ethanol production faces challenges in biochemical conversion despite advances in pretreatment.
• Optimizing reactor configurations and residence times is crucial for economic viability.
• Continuous enzymatic saccharification and fermentation (SSF) operations require efficient bioreactor design.

Purpose of the Study:

• To identify optimal bioreactor configurations for continuous enzymatic saccharification and fermentation (SSF) with minimized residence times.
• To apply graphical methods, specifically the attainable region method, for optimizing reactor networks.
• To assess the impact of soluble sugars from pretreatment liquor on hydrolysis and SSF.

Main Methods:

• Application of the attainable region method to handle complex, multi-species reaction kinetics in continuous reactors.
• Analysis of reactor networks composed of plug flow reactors (PFRs) and continuous stirred tank reactors (CSTRs).
• Evaluation of separate hydrolysis and fermentation (SHF) and SSF operations using pretreated corn stover.

Main Results:

• Candidate attainable regions were determined for both SHF and SSF processes.
• Reactor networks minimizing residence time were constructed using PFRs and CSTRs.
• Washed solids as substrate improved glucose concentration and yield in SHF, and yield and bioethanol titers in SSF.

Conclusions:

• Attainable region analysis is a powerful tool for optimizing bioreactor networks for lignocellulosic ethanol production (SHF and SSF).
• The methodology is adaptable to various kinetic models, substrates, enzymes, and microorganisms.
• A CSTR followed by a PFR in SSF mode, using washed solids, is the most suitable configuration for minimizing residence time and considering rheological aspects.