The influence of the tower air-lift bioreactor geometry on the oxygen transfer rate in the apparatus

The hydrodynamic and mass transfer parameters in water, in several types of tower-loopair-lift bioreactor were investigated. The following configurations of the apparatus were used forexperiments: internal-loop with eentral draft tube, internal-loop with static mixers in the drafttube, external-loop with various circulation tube diameters (0 < A^/Ar < 1), external-loop withperforated plates in the main zone (multistage reactor). The highest k^a eoefficients were obtainedin external-loop multistage reactor. A^/A^ ratio had significant influence on the main processparameters; gas holdup, liquid circulation velocity, volumetric oxygen transfer coefficient andmixing time.