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METHODS OF CLEANING MEMBRANE MODULES

  • US 20120187044A1
  • Filed: 03/30/2012
  • Published: 07/26/2012
  • Est. Priority Date: 09/19/2003
  • Status: Abandoned Application
First Claim
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1. A method of backwashing a membrane filtration system including a vessel, a membrane module, piping, and a manifold comprising:

  • filtering a feed liquid through pores in walls of membranes of the membrane filtration system to produce a liquid permeate;

    withdrawing the permeate from lumens of the membranes and through the manifold, a portion of the piping, and a valve while filtering the feed liquid;

    stopping the filtration process;

    to isolating the lumens of the membranes, the manifold, the portion of the piping, and a gas inlet when the filtration process is stopped, the lumens of the membranes, the manifold, and the portion of piping upstream of the valve during filtration, wherein the lumens of the membranes, the manifold, and the portion of piping consist of those through which permeate is withdrawn while filtering the feed liquid;

    scouring surfaces of the membranes by flowing bubbles of a first gas past surfaces of the membranes;

    supplying a second gas through a second gas inlet at a pressure less than a bubble point of the membranes;

    applying the second gas to a portion of liquid permeate present in the isolated lumens, manifold, and portion of piping by introducing the second gas through the second gas inlet into the filtration system on a side of the valve in direct fluid communication with the membrane module;

    directing the portion of liquid permeate into the membrane module through a first end of the membrane module and through a second end of the membrane module;

    backwashing the membranes by displacing at least some of the portion of liquid permeate through pores in walls of the membranes, the second gas not penetrating into the membrane pores;

    discharging backwash waste from the vessel;

    refilling the vessel with feed liquid;

    venting the second gas from the isolated lumens, manifold, and portion of piping; and

    resuming filtration.

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