METHOD FOR CLEANING A MEMBRANE FILTER USING ULTRASOUND AND BACKWASH PULSES AND DEVICE ADAPTED THEREFOR

The invention relates to a method for cleaning a filter element made of a porous material. The method comprises directing ultrasound to the filter element, and directing after a predefined time from starting of the ultrasound an impulse to a filtrate reservoir causing filtrate inside the filtrate reservoir to be forced inside the filter element in order to remove particles from the surface of the filter element. Pressure of the impulse is between 4 to 8 times higher than the forward pressure and also that the reverse flux, measured in volume per area time, caused by the impulse is at the minimum 2 to 8 times the feed flux. The invention also relates to a filtering device comprising a filter element made of a porous material.