Liquid Homogenization Studies in Animal Cell Bioreactors of up to 8 m3 in Volume

This paper reports extensive studies on characterizing the homogenization of the liquid phase in a commercial animal cell bioreactor of 8 m(3) volume. Using this commercial bioreactor as a model, geometrically-similar scale-down tests in vessels down to 0.2 m diameter have also been conducted. The results show that correlations in the literature work quite well in pre-dieting homogenization as a result of agitation and air sparging even though the level of both is generally two orders of magnitude less than those previously investigated. High aspect ratios give particularly slow blending and imply serious problems for large scale operation with respect to pH and dissolved oxygen gradients. Proposals are put forward for reducing these poor blending characteristics based on these studies and earlier ones which showed that the sensitivity of animal cells to damage due to mechanical agitation and air sparging is less than it was originally thought to be.