Application of heat-mass transfer analogy for understanding the mechanism of fouling control in a submerged flat sheet microfiltration membrane

Experiments of microfiltration enhanced with air dispersion were carried out through a submerged flat sheet membrane using commercial yeast suspension. In the experiments, the effect of hydrodynamic parameters like liquid flow velocity, air flow rate and aerator size were examined on flux control of fouling for different feed concentrations at constant transmembrane pressure. The classical heat and mass transfer analogy was applied to get an insight into the mechanism of fouling control in single and two-phase flow systems. The experimental results show that: (a) air dispersion reduced the particle fouling on membrane surface thus causing permeate flux enhancement for any value of air flow rate and for any feed concentration. A maximum flux enhancement factor of 270% was achieved for feed concentration of 25 g/L whereas as it was 60% for feed concentration of 1 g/L at an optimum air flow rate of 64 L/min. (b) Convective back transport of solids from membrane surface due to shear forces generated during two-phase flow was found to the be most significant phenomena of fouling control in submerged flat sheet microfiltration membranes. (c) The classical heat and mass transfer analogy successfully provided the explanation of phenomena of convective back transport of solids due to gas-liquid two-phase flow.