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Biological phosphorus removal

  • US 7,850,851 B2
  • Filed: 08/14/2006
  • Issued: 12/14/2010
  • Est. Priority Date: 08/12/2005
  • Status: Expired due to Fees
First Claim
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1. A process for treating waste water to remove phosphorous and nitrogen in a treatment system including an anaerobic zone including an anaerobic mixed liquor having organisms which release phosphorous;

  • an anoxic zone including an anoxic mixed liquor having denitrifying phosphorous accumulating organisms which uptake phosphorous and an aerobic zone including an aerobic mixed liquor having organisms which further uptake phosphorous;

    the process comprising the steps of;

    (a) providing wastewater to be treated into the anaerobic zone;

    (b) communicating anaerobic mixed liquor from the anaerobic zone to the anoxic zone;

    (c) communicating anoxic mixed liquor from the anoxic zone to the anaerobic zone;

    (d) communicating anoxic mixed liquor from the anoxic zone to the aerobic zone;

    (e) applying aerobic mixed liquor to a feed side of a membrane filter;

    (f) producing a treated effluent from a filtrate side of the membrane filter;

    (g) flowing oxygen-containing gas bubbles past the feed side of said membrane filter to remove accumulated solids;

    (h) communicating at least some of the material rejected by the membrane filter to a degassing device to remove some or all of any dissolved oxygen contained in said rejected material; and

    (i) communicating said degassed material to the anoxic zone.

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