Separation and concentration of milk proteins with a submerged membrane vibrational system

Abstract A transverse vibrating membrane filtration system was used for the separation and concentration of milk proteins at low operating temperatures using 0.04 µm polyvinylidene fluoride (PVDF) hollow fibre membranes. Filtration was carried out using skim milk and milk protein concentrate solutions (MPC60, MPC66, MPC71) to simulate different stages of the concentration process. It was found that the submerged membrane system with the aid of membrane vibration can maintain very high transmission of whey proteins (α-Lactalbumin and β-Lactoglobulin) while fully rejecting casein micelles. Furthermore, low transmembrane pressure (TMP) rise was observed during long term filtration experiments conducted over a 24 h period for high viscosity MPC60 and MPC66 solutions (12.93 cP and 21.06 cP at 10 °C) at a constant permeate flux of 10 L/m 2 h and 5 L/m 2 h respectively. Interestingly, the TMP was observed to rise and then stabilise at approximately 18 kPa even when operated at a supra-critical flux of 17–19 L/m 2 h during MPC60 filtration, indicating that the application of membrane vibration can prevent further membrane fouling. In addition, a comparison of the transverse vibration system with a conventional cross-flow system showed that the vibrating system had significantly better system performance and separation efficiency.