(358d) Hydrodynamic Study to Determine Volumetric Mass Transfer Coefficient for Cell Culture Applications

The stirred tank reactors are most commonly used both in the laboratory and process industry to identify key factors that influence reactor performance. Particularly for bioreactors, the volumetric mass transfer coefficient (k_La) of oxygen is used as one of the important parameters for determining efficiencies of reactors and for successful scale-up. A number of methods have been developed to determine the volumetric mass transfer coefficient such as dynamic method, steady-state method, gaseous oxygen balance and carbon dioxide balance. In the present work, using the dynamic “gassing out-gassing-in” method, the effect of various parameters such as impeller agitation rate, air flow rate, and impeller type (e.g. Rushton Turbine, Pitched Blade Turbine, and Dislocated Rushton Turbine) on the volumetric mass transfer coefficient has been investigated in a stirred tank bioreactor. It was found that the volumetric mass transfer coefficient increases with both the agitation rate and the air flow rate. In addition, the power input per unit volume was shown to decrease with the air flow rate or aeration. Furthermore, it was found that the dislocated Rushton turbine can achieve higher volumetric mass transfer coefficient due to enhanced gas dispersion, as compared to the standard Rushton Turbine. Finally, several empirical correlations have been developed for the evaluation of k_La. This study can be used for cell cultivation systems/applications/reactors.