Cleaning of hollow fibre membranes

Abstract

A method and apparatus for recovering fine solids from a liquid feed suspension is disclosed. The apparatus has an operating cycle including a concentration part of the cycle in which solids present in the feed suspension are concentrated and a backwash part of the cycle in which supply of feed suspension to the concentrator is interrupted, the concentrator comprises a shell (11), and a plurality of elastic, hollow, microporous, polymer fibers (12) being fixed at their ends within the shell (11). Pressurized feed suspension is supplied to the outside of the fibers during said concentration part of the cycle and the filtrate may be withdrawn from the fiber lumens during the operating cycle. During the backwash cycle the concentration part of the cycle is terminated by ceasing supply of feed to said exterior surface of the fibers (12). The shell (11) is then sealed and the remaining filtrate removed from the lumens. A source of fluid under pressure is then applied to said lumens before, at the same time as, or just after opening the shell (11) to atmosphere, to cause explosive decompression through the walls of the fibers (12) whereby the fluid under pressure passes through said walls. The pressure level in said lumens is maintained at a predetermined value for a sufficient time following said decompression to cause substantial portions of solids lodged within and/or on the fiber walls to be dislodged. The dislodged contaminant matter is then washed away by the application of a flow of liquid over the surface of the fiber walls; and the concentration part of the operating cycle is recommended by introducing the supply of feed suspension to said exterior surface of said fibers (12).

Dependencies are inferred from the claim text.