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Method for treating wastewater in a membrane bioreactor to produce a low phosphorus effluent

  • US 6,946,073 B2
  • Filed: 09/02/2003
  • Issued: 09/20/2005
  • Est. Priority Date: 09/02/2003
  • Status: Active Grant
First Claim
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1. A method for removal of biological nutrients from a wastewater yielding a low phosphorous output comprising:

  • a) providing a serial multistage bioreactor containing activated sludge comprising in hydraulic series an anaerobic zone, an upstream aerobic zone, a downstream aerobic zone and an immersed membrane filter operatively associated with the downstream aerobic zone, each zone having an upstream inlet and a downstream outlet;

    b) providing a wastewater to the anaerobic zone inlet;

    c) adding a quantity of chemical to precipitate soluble and particulate phosphorous in an amount sufficient to yield a low phosphorous output downstream of the upstream aerobic zone and upstream of the immersed membrane filter;

    d) separating treated water from the activated sludge and precipitated phosphorous by the immersed membrane filter; and

    e) recycling return activated sludge separated by the immersed membrane filter from treated water to the anaerobic zone.

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