Estimation of dissolved carbon dioxide stripping in a large bioreactor using model medium

Dissolved carbon dioxide (dCO₂) accumulation is one of the most serious problems in the scale-up of industrial cell culture. To predict the effects of dCO₂ stripping in different culture conditions and at different scales, we examined a method of estimation of dCO₂ stripping using a model medium. The operational parameters (e.g., sparging and agitation rate) and the size of the bioreactor (working volume: 80 L, 500 L, 2000 L; aspect ratio: 1.0 ∼ 1.6) were varied, and the model medium was prepared by adjusting pH, density, viscosity, surface tension, and buffer conditions. dCO₂ stripping efficiency was evaluated using the index k_La^CO2, which was defined in accordance with the volumetric oxygen transfer coefficient k_La. The model medium exhibited dCO₂ stripping behavior similar to real culture medium in all experimental conditions tested. It is expected that the use of the model medium to estimate dCO₂ stripping in real cultures will be valuable for determining the culture conditions in bioreactors in scale-up.