Aeration and mixing in vortex fermenters.
The overall apparent volumetric gas-liquid mass transfer coefficient (kLa) and the mixing time (t95) were determined in a 240 dm3 vortex aerated fermenter over stirrer speed and air flow ranges of 300-800 rpm and 10-45 normal dm3 min-1, respectively. The mass transfer data obtained in an aqueous salt solution (2.5 kg m-3 NaCl in water) compared well with the measurements in a fermentation medium used in culture of certain microaerophilic bacteria. Over the ranges examined, the gas-liquid mass transfer coefficient depended only on air flow rate; the dependence was linear with flow. Mixing time declined with increasing agitation according to a power-law relationship. The mixing and mass transfer characteristics of the vortex aerated system were compared with that of a 'standard' stirred tank fermenter (27 dm3). The mixing time variations with respect to agitation rate were remarkably similar for the two types of fermenters examined.
Chisti
Y
Y
Department of Chemical Engineering, University of Waterloo, Ontario, Canada.
Moo-Young
M
M
D000332:Aerobiosis; D001709:Biotechnology / Q000295:instrumentation* / Q000379:methods; D004566:Electrodes; D005285:Fermentation; D005740:Gases; D007700:Kinetics; D010100:Oxygen
D005740:Gases; D010100:Oxygen