Abstract: Ultrasound (US) cleaning technique was applied to remove fouling of PVDF(polyvinylidene fluoride) microfiltration (MF) membrane, used to be fouled by yeast cell and isolated soybean protein (ISP) solution. The US employed was of 40 kHz frequency and 1.43～2.85 W/cm2 output power. The cleaning effects were determined by the assay of flux recovery rate (FR) and cleaning time. Results showed that the membrane, fouled by yeast cell solution, could be recovered by water cleaning with US irradiation. The cleaning time could be achieved with the same FR by the increase of US intensity. However, for the membrane fouled by ISP solution, it took long time to achieve the same FR with ultrasound-associated water cleaning. In addition, it was also found that the chemical cleaning associated with US irradiation could distinctly enhance the cleaning efficiency, such as to restore 91% of the original membrane water permeability within 6 min by a combination of 3 g/L sodium hydroxide with output power of 1.43 W/cm2 US irradiation.

Key words: ultrasound (US), membrane fouling, cleaning, flux recovery (FR) rate