Method for treating wastewater in a membrane bioreactor to produce a low phosphorus effluent
First Claim
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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Abstract
Removal of biological nutrients from a wastewater yielding a low phosphorous (e.g., less than 0.25 mg/L) output includes providing a serial multistage bioreactor containing activated sludge having in hydraulic series an anaerobic zone and a downstream aerobic zone, with each zone having an upstream inlet and a downstream outlet. The wastewater is provided to the anaerobic zone inlet. A quantity of chemical sufficient to precipitate soluble and particulate phosphorous is added to the downstream aerobic zone in an amount sufficient to yield a low phosphorous output. Treated water is separated from the activated sludge and precipitated phosphorous and a return activated sludge separated from the treated water is recycled to the anaerobic zone.
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Citations
15 Claims
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1. A method for removal of biological nutrients from a wastewater yielding a low phosphorous output comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus for removal of biological nutrients from a wastewater comprising:
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a serial multistage reactor configured to contain activated sludge comprising in hydraulic series an anaerobic zone, an upstream aerobic zone and a downstream aerobic zone, each zone having an upstream inlet and a downstream outlet;
an immersed membrane filter operatively associated with the downstream aerobic zone; and
means for adding a quantity of chemical to precipitate soluble and particulate phosphorus downstream of the upstream aerobic zone and upstream of the immersed membrane filter. - View Dependent Claims (12, 13, 14, 15)
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Specification