Patent ID: 7585411

Claim:
A system for the filtration of a liquid feedstock high in suspended solids for the purpose of economically producing permeate lean in suspended solids, which system comprises: a) a plurality of spiral wound membrane filtration cartridges which each includes membrane filter sheet material, feed spacer sheet material and permeate carrier sheet material spirally wound about a perforated permeate collection tube and confined within an open-ended tubular casing in a generally cylindrical, liquid-tight configuration, which casing is not submerged in liquid in a tank but has its exterior surface in contact with the atmosphere, b) an interconnected group of bases each of which supports one said cartridge in a substantially vertical orientation, c) said interconnected group of bases being connected to a supply of a liquid feedstock, d) a seal between each said base and each said cartridge so that liquid feedstock being supplied flows upward in said cartridge through said feed spacer material, e) means for creating a vacuum within each said permeate collection tube to cause liquid lean in suspended solids to permeate through said membrane sheet material as a result of transmembrane pressure (TMP) thereacross and for withdrawing permeate from said cartridge, means for controlling the supply of liquid feedstock so that liquid level in said casing is maintained at about a constant height therewithin and said filtration cartridge operates in dead end mode, f) a bubbler in each said base for creating an upwardly flowing stream of gas bubbles in the liquid feedstock below said cartridge, which stream will enter said open end at the bottom of said cartridge and exit to the atmosphere at an open upper end of said tubular casing, g) a source of pressurized back-flush fluid, h) means for periodically initiating reverse flow of such back-flush fluid through the collection tube and the permeate carrier fabric sheet into said feed spacer material to back-flush said cartridge whenever permeate flow from said cartridge is indicative of an undesirable extent of solids accumulation on said overall membrane surface, and i) means for withdrawing from said system the liquid in said cartridge feed spacer sheet material of each cartridge which includes said back-flush fluid and solids dislodged by said back-flush fluid and the volume of feedstock in said interconnected supporting bases following completion of said back-flush flow and before resupplying fresh liquid feedstock to said bases and said cartridges.