The Study of Dynamic Milk Ultrafiltration Performance Influenced by Membrane Molecular Weight Cut off

Abstract

<em>The effect of membrane molecular weight cut off (MWCO) at three levels (10, 20 & 50 kD) on dynamic behavior of permeate flux (J_P), hydraulic resistances (total hydraulic resistance, R_T; reversible fouling resistance, R_rf; irreversible fouling resistance, R_if and membrane hydraulic resistance, R_m) and milk solutes rejection (protein, R_P; fat, R_F; lactose, R_L; minerals, R_M and total solids, R_TS) are studied for the ultrafiltration of milk. Experiments are carried out using the pilot plant UF membrane system equipped with a spiral wound module and a polysulfone amide membrane. A three-stage strategy based on a resistance-in-series model (boundary layer-adsorption) was used to determine the different hydraulic resistances. The results showed that the J_P decreases greatly with increasing the process time, but the J_P values obtained for 20 kD were considerably higher than 10 kD & 50 kD during the whole process. R_T increased during operation at all levels of MWCO, but the hydraulic resistance values for 50 kD were significantly greater than 10 & 20 kD. Results for milk solutes rejection showed that the R_P and R_F are almost constant with process time at the corresponding MWCO, whereas the R_L, R_M and R_TS significantly increased.</em>