Abstract
Mixing operations in biological processes is of utmost importance due to its effect on scaling-up and heat and mass transfer. This paper presents the characterization of a bench-top bioreactor with different impeller configurations, agitation and oxygen transfer rates, using CFD simulations and experimental procedures. Here, it is demonstrated that factors such as the type of impeller and the flow regime can drastically vary the operation as in the preparation of cultures. It was observed that the bioreactor equipped with a Rushton generates a k L a of 0.0056 s−1 for an agitation velocity and airflow rate of 250 RPM and 5 L/min, respectively. It is suitable result for the dissolved oxygen (DO) but requires a considerable amount of power consumption. It is here where the importance of the agitator’s diameter can be observed, since, in the case of the two propeller types studied, lower energy consumption can be achieved with a smaller diameter, as well as a much smaller shear cup 2.376 against 0.723 s−1 by decreasing by 4 cm the standard diameter of an agitated tank (10 cm). Finally, the k L a values obtained for the different configurations are compared with the maximum shear rate values of different cell cultures to highlight the impact of this study and its applicability to different industries that use agitation processes for cell growth.
Highlights
Several sectors of industry use mixing processes, for example, in the synthesis of products such as oils, cosmetics, pharmaceuticals, food additives, etc
Due to the nature of this study, it was necessary to determine the quality of the simulated models, Due to the nature of this study, it was necessary to determine the quality of the simulated so a mesh independence analysis was needed
The absolute error only considers the interior interval between the meshes already obtained, so it is of how much the results vary between the fine mesh and the normal mesh
Summary
Several sectors of industry use mixing processes, for example, in the synthesis of products such as oils, cosmetics, pharmaceuticals, food additives, etc. In the biotechnology area, mixing is a way of providing a correct microbiological environment in which microorganisms can grow with the best living conditions. Even though it is possible to establish the growth conditions in controlled surroundings, the scaling-up to industrial levels of these processes can be troublesome. This is due to many variables, which are linked to specific agitation parameters such as power number, pumping number and impeller type [1]. Other parameters must be considered, such as ideality and Processes 2020, 8, 878; doi:10.3390/pr8070878 www.mdpi.com/journal/processes
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