The performance of three sparger diameters (DS = 0.6D, DS = D, DS = 1.6D) in combination with three positions
(below, above or level with the impeller) for gas-liquid dispersion and mass transfer were evaluated in the case
of the Rushton turbine and the A315 propeller in up- or down-pumping mode. The results show that the best
results in terms of gas handling and mass transfer capacities are obtained for all impellers with the sparger placed
below it and with a diameter at least equal to the impeller diameter. For the sparger position below the agitator,
the kLa values of the Rushton turbine are greater than those of the A315 propeller, whatever the pumping mode.
The A315 propeller in up-pumping mode is, however, more economically efficient in terms of mass transfer. In
all cases, the up-pumping mode gives better results than the down-pumping one
