Integrated Metabolic and Process Modeling of Bubble Column Reactors for Gas Fermentation

Abstract

Gas fermentation has emerged as an attractive option for producing renewable fuels and chemicals from carbon monoxide (CO) rich waste streams. Bubble column reactors are being developed for large-scale production, motivating the investigation of multiphase reactor hydrodynamics. We combined two-phase hydrodynamics with a genome-scale reconstruction of Clostridium autoethanogenum metabolism and multiphase convection-dispersion equations to compare the performance of bubble column reactors with and without liquid recycle. Hydrodynamics were predicted to diminish column performance with respect to CO conversion, biomass accumulation and ethanol production when compared to column models in which the gas phase was modeled as ideal plug flow plus axial dispersion. Liquid recycle was predicted to be advantageous by increasing CO conversion, biomass production, and ethanol and 2,3-butanediol production compared to the non-recycle reactors. Our results demonstrate the power of combining metabolic models and hydrodynamics for simulating and optimizing gas fermentation reactors.