Investigating a Stirred Bioreactor: Impact of Evolving Fermentation Broth Pseudoplastic Rheology on Mixing Mechanisms

The culture medium in many fermentations is a non-Newtonian fluid. In bacterial alginate batch production, the broth becomes more pseudoplastic as concentration increases, which impairs mixing process. This work characterizes effect of interaction between changing rheology and impeller on bioreactor fluid dynamics. Experimentally, fermentation with evolving reproduced. Three stages are mimicked using appropriate solutions water xanthan gum. Impeller torque measurements reported. weakening impellers’ over process identified. To overcome experimental limitations, CFD applied to study evolution flow patterns, velocity field, dead zones, vortical structures. Precessional vortex macro-instabilities identified being responsible for unstable patterns at earlier fermentation. A stable parallel pattern accounts weakest final stage. Overall, this contributes complete workflow adapt models characterization aided design stirred tanks well an regime.