Low frequency ultrasound has been used to facilitate cross-flow ultrafiltration of dairy whey solutions. Experimental results show that
ultrasonic irradiation at low power levels can significantly enhance the permeate flux with an enhancement factor of between 1.2 and 1.7. The
use of turbulence promoters (spacers) in combination with ultrasound can lead to a doubling in the permeate flux. The application of a combined
pore blockage/cake resistance model to the observed experimental data suggests that the use of ultrasound acts to lower the compressibility
of both the initial protein deposit and the growing cake. Conversely, the pore blockage parameter is not significantly affected. The use of a
gel polarization model shows that the ultrasonic irradiation increases the mass transfer coefficient within the concentration polarization layer.
Electron microscopy results showed no evidence that the ultrasonic irradiation altered the membrane integrity. HPLC analysis of the whey
proteins in the feed solution before and after sonication showed that the concentration profile of the whey proteins was also not affected by
the sonication process.