Incorporating hydrodynamics into spatiotemporal metabolic models of bubble column gas fermentation

Area of Science:

• Biotechnology
• Chemical Engineering
• Microbial Engineering

Background:

• Gas fermentation is a promising method for producing renewable fuels and chemicals from carbon monoxide (CO)-rich waste streams.
• LanzaTech utilizes a proprietary Clostridium autoethanogenum strain for synthesizing ethanol and 2,3-butanediol.
• Bubble column reactors are crucial for large-scale gas fermentation, necessitating hydrodynamic studies.

Purpose of the Study:

• To investigate the impact of hydrodynamics on bubble column reactor performance for gas fermentation.
• To compare reactor configurations with and without liquid recycle.
• To optimize gas fermentation processes by integrating metabolic models and hydrodynamics.

Main Methods:

• Combined genome-scale metabolic reconstruction of C. autoethanogenum with multiphase convection-dispersion equations.
• Modeled bubble column reactors with and without liquid recycle.
• Analyzed hydrodynamics effects on CO conversion, biomass, and product yields.

Main Results:

• Hydrodynamics negatively impacted CO conversion, biomass, and ethanol production compared to ideal plug flow models.
• Liquid recycle significantly improved CO conversion, biomass, and production of ethanol and 2,3-butanediol.
• Optimized conditions for liquid recycle favored ethanol production over acetate.

Conclusions:

• Integrating metabolic models with two-phase hydrodynamics is powerful for simulating and optimizing gas fermentation reactors.
• Liquid recycle is a beneficial strategy for enhancing the efficiency of bubble column reactors in gas fermentation.
• Further optimization of gas feed, bubble size, and column height can improve product selectivity.