Modeling and CFD‐PBE simulation of an airlift bioreactor for PHB production

Abstract

ABSTRACTIn the present attempt, a 3D simulation using a commercially available computational fluid dynamics package (FLUENT 6.3.26), and a metabolic model were used to investigate hydrodynamics and production of polyhydroxybutyrate (PHB) in an airlift bioreactor, performed by Tavares et al. (L. Z. Tavares, E. S. da Silva, J. G. C. Pradella. Biochem. Eng. J., 2004; 18, 21–31). An Eulerian approach was applied to model the gas–liquid interactions. In order to account for the combined effect of bubble breakup and coalescence in the bioreactor, a population balance model implemented in the software was used. Biosynthesis of PHB in the bioreactor was examined and maximum forward reaction rate values of thiolase, reductase, and synthase steps were determined as V1(thiolase) = 1.8 mM/min, V1(reductase) = 400 mM/min, and V1(synthase) = 380 mM/min to predict the experimental PHB production rate by Tavares et al. suitably. A simplified reaction was considered for PHB production. Moreover, gas holdup, liquid velocity vectors, shear stress, and volumetric oxygen transfer coefficient were investigated. Also, molar concentration profiles of PHB and glucose within the bioreactor were obtained. © 2014 Curtin University of Technology and John Wiley & Sons, Ltd.