Patent ID: 7922829

Claim:
A method for removing accumulated, dewatered sludge from the surfaces of a multiplicity of flat-plate membrane cartridges contained in a cassette situated in a membrane filtration tank or basin of a sewage treatment facility, without removing the cartridges from the cassette, comprising: removing a cassette of cartridges from the tank or basin, directing cutting water sprays from a plurality of nozzles through spaces between adjacent cartridges held in the cassette, in a direction essentially parallel to the flat-plate membrane cartridges, and breaking up sludge on the membrane surfaces of the adjacent cartridges, moving the water sprays along the spaces so as progressively to spray substantially the entire space with the cutting sprays, and wherein each cutting spray has a diameter in the range of about 0.03 to 0.06 inch and an impingement pressure of about 3 to 25 psi at 12 inch distance from the nozzle.