The gas-liquid volumetric oxygen transfer coefficient in a three-phase fluidized bed bioreactor was studied using Ca-alginate gels as the solid phase. The coefficient, kLa, in three-phase fluidized beds was smaller than that in bubble columns, regardless of gel diameter. This result was a new finding, and was shown to be characteristic of low-density gel beds. The value of kLa decreased with decreasing gel diameter and with increasing particle concentration in the liquid suspension. This

more »

... es that an optimal gel diameter and particle concentration exist in application of gels to the bioreactor. Dimensionless correlations are proposed for kLa and sG.