Computational fluid dynamics modelling of hydrodynamics, mixing and oxygen transfer in industrial bioreactors with Newtonian broths

Industrial aerobic fermentation processes are performed in large-scale bioreactors (> 20 m(3)). Understanding the local values of the velocity field, the eddy dissipation rate and the gas volume fraction is of interest, as these parameters affect mixing and mass transfer and hence fermentation process performance and profitability. Despite the industrial and academic importance of these flow variables in large-scale bioreactors, there is scarce literature addressing it. This article provides a numerical comparison using Computational Fluid Dynamics (CFD) of different industrially relevant reactor types (bubble columns and stirred tanks with different impeller configurations) operated within a realistic range of industrial conditions (40 - 90 m(3), 0.3 - 6 kW m(-3), 0.5 - 1 vvm). Local flow variables and mixing times are evaluated for all cases studied. The collection of these data allows the prediction of the typical values of mixing time (10 - 206 s) and oxygen transfer rate (1 - 8 kg m(-3) h(-1)) in industrial bioreactors, and serves as basis for the comparison between different reactor types.