Author(s): AncaIrina Galaction, AncaMarcela Lup teanu
The models describing the flow or the heat and mass transfer in stirred bioreactors can be eas ily adapted for the continuous ph ase from the stirred bed bioreactors. But, for the immobilized biocatal yst phase, new models have to be established. Therefore, in this paper the influences of the main factors on mixing for a bioreactor with stirred bed of S. cerevisiae immobilized cells in alginate have been analyzed.. The mixing efficien cy continuously increases with rotation speed acceleration for the distances between th e stirrers of 1.5d and 2d, the lowest mixing intensity being invari ably recorded for 2d. The vari ation of mixing time obtained by placing the impellers at a dist ance of 0.5d and d was sinusoidal and more evident for the closest positions of the stirrers. In all studied cases, the mixing time increases for about 3.5 - 4 times with the increase of the volumetric fraction of biocatalyst fr om 7 to 40%. The most efficient mixing has been obtained for biocatalyst particles with 4.6 mm diameter.