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Method of exhausting dissolved oxygen in a nitrogen removal wastewater treatment process

  • US 5,160,043 A
  • Filed: 09/09/1991
  • Issued: 11/03/1992
  • Est. Priority Date: 09/09/1991
  • Status: Expired due to Fees
First Claim
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1. A method of exhausting dissolved oxygen in a nitrogen removal wastewater treatment process comprising the steps of:

  • (a) forming a mixed liquor;

    (b) denitrifying the mixed liquor by treating the same in an anoxic treatment zone;

    (c) transferring the mixed liquor from the anoxic treatment zone to an oxic treatment zone and nitrifying the mixed liquor; and

    (d) recycling a portion of the nitrified mixed liquor from the oxic treatment zone back to a preceding anoxic zone;

    said recycling step including the steps of transferring the nitrified mixed liquor from the oxic zone to an exhauster holding tank located in a recycle stream, retaining the nitrified mixed liquor in the exhauster holding tank in the absence of supplied oxygen containing gas for a predetermined period to reduce the dissolved oxygen concentration of the mixed liquor, and transferring the deoxygenated, nitrified mixed liquor from the exhauster holding tank to the anoxic zone.

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