INVERTED AERATED IMMERSED SCREEN, SCREEN ASSEMBLY AND OPERATING PROCESS

摘要

A static screen used upstream of a membrane assembly within a water treat ment system has a screening surface with a number of openings distributed ov er its area. Liquid flows through the screening surface to reach the membran e assembly. Various shapes of screening surfaces are described including thr ee-dimensional bodies with openings at or near their lower ends. Methods for cleaning the screen are described including aeration, backwashing and lower ing down the water level in an upstream section by partially or completely d raining a tank. Various treatment systems or process designs incorporating t he screen are described. Screen elements may be made in two or more parts co mprising a supporting structure and a separation layer and may be mounted on a conduit or pan.