LIQUID SOLID MASS-TRANSFER IN AN AIRLIFT-LOOP REACTOR WITH A DISPERSED SOLID-PHASE/

In processes with immobilized cells mass transfer across the boundary layer surrounding the support often plays an important role. Relativel y little is known about external mass transfer as a function of the su perficial gas velocity in bioreactors such as air-lift loop reactors. In this work ion-exchange resins were used as a solid phase to determi ne the mass-transfer coefficient in such a reactor. Relations between the Sherwood number and the superficial gas velocity were derived and compared with relations from the literature. Relations in which the Sh erwood number is a function of the energy-dissipation rate and relatio ns in which the relative particle velocity is calculated from the rate of free fall of the particle were compared. It was shown that the She rwood numbers that were functions of the energy-dissipation rates were higher than could be calculated on the basis of the rate of free fall . The Sherwood number obtained was used to calculate the k(1,s) of car rageenan gel beads as a solid phase in an air-lift loop reactor. (C) 1 998 SCI.