Improvement of membrane permeation performance by ultrasonic microfiltration

To prevent membrane fouling, cross-flow microfiltration with ultrasonic wave cleaning was carried out using a model suspension containing both baker's yeast and bovine serum albumin (BSA), The effects of ultrasonic waves on the permeate flux and rejection of BSA were studied. The steady-state flux obtained in filtration with ultrasonic waves was four to six times greater than that without ultrasonic waves, and a high flux was obtained, even at a low feed flow velocity. There was an optimum membrane pore size and an optimum operating pressure, It was found that ultrasonic waves were very effective for removing the cake layer deposited on the membrane surface and preventing the plugging of the membrane pores. A filtration method in which a feed pump and an ultrasonic generator were operated alternately was very effective for enhancing the flux and solute permeation rate during cross-flow microfiltration.