Mass Transfer Considerations for Scale-Up and Scale-Down of Animal Cell Bioprocesses
The development, characterization and validation of animal cell bioprocesses can greatly benefit from straight forward scale-up/-down procedures that generally rely on scale down models. The match of scale down model data to the data gathered at larger scales relies on several factors one of which is the mass transfer coefficient. This study reports the kLa for O2 and CO2 measured in a bioreactor equipped with a ring sparger. The results indicate that higher power input leads to a decrease of CO2 elimination capacity. When high power input is attributed to a smaller bubble diameter, this finding confirms a conclusion in literature that relates CO2 elimination to bubble size (Mostafa and Gu (2003), Biotechnol Prog 19(1):45–51; Frahm et al. (2002), J Biotechnol 99(2):133–148). Aeration rate, however, does not influence the mass transfer ratio at a given power input.