Mathematical modeling and simulation of a two-phase fluidized-bed bioreactor with an external aerator

The article presents a mathematical model and steady-state characteristics of a continuous-flow two-phase fluidized-bed bioreactor with external aeration. The quantitative description includes biofilm growth on inert carriers, distributions of density, and diffusion coefficients in biofilm, decay of microorganisms, gas-liquid and liquid-biofilm mass transfer, biofilm detachment, biomass thickening and recirculation. The method for the determination of steady-states and the assessment of stability based on the orthogonal collocation method was presented. The effect of key parameters on steady-state properties of the bioreactor was analyzed. These parameters are: carbonaceous substrate concentration in the feed stream, mean residence time of the liquid and the liquid recirculation ratio. It was shown, that stream recirculation improves aeration of the liquid phase and the degree of conversion of a carbonaceous substrate. The effect of a growth kinetic model on the steady-state multiplicity was proved and discussed. The applicability of the bioreactor was assessed for aerobic processes characterized by a varied oxygen requirement, expressed by the growth yield coefficient w_BT . © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 2018 © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1109-1119, 2018.