Simultaneous anoxic biological phosphorus and nitrogen removal
First Claim
1. A process for treating wastewater to simultaneously remove organic matter, nitrogen, and phosphorus, the process comprising:
- providing two or more streams in a first tank operating under anoxic conditions, the two or more streams including plant influent wastewater and return activated sludge;
mixing the plant influent wastewater and the return activated sludge in the first tank to form a mixed liquor;
transferring the mixed liquor to a second tank operating under microaerophilic conditions to simultaneously effectuate nitrification, denitrification, phosphorous release, and phosphorus uptake in the second tank; and
transferring the mixed liquor to a third tank that separates treated effluent from activated sludge containing microorganisms, wherein a first portion of the activated sludge is returned to the first tank as the return activated sludge and a second portion of the activated sludge is returned to the second tank.
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Accused Products
Abstract
Methods and systems are provided for treating wastewater to simultaneously remove nitrogen, carbon, and phosphorus. The process includes an anoxic tank that receives at least two streams, including plant influent wastewater and return activated sludge. These streams are mixed in the anoxic tank to promote phosphorus release and fermentation of particulate and dissolved organic matter. The mixed liquor is transferred to an aerated tank having low dissolved oxygen concentrations to promote development of phosphorus-release bacteria that is eventually recycled to the anoxic tank by way of the return activated sludge. Simultaneous nitrification, denitrification, and phosphorus release occur in the aerated tank. A membrane tank separates treated effluent from activated sludge in a membrane tank.
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Citations
17 Claims
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1. A process for treating wastewater to simultaneously remove organic matter, nitrogen, and phosphorus, the process comprising:
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providing two or more streams in a first tank operating under anoxic conditions, the two or more streams including plant influent wastewater and return activated sludge; mixing the plant influent wastewater and the return activated sludge in the first tank to form a mixed liquor; transferring the mixed liquor to a second tank operating under microaerophilic conditions to simultaneously effectuate nitrification, denitrification, phosphorous release, and phosphorus uptake in the second tank; and transferring the mixed liquor to a third tank that separates treated effluent from activated sludge containing microorganisms, wherein a first portion of the activated sludge is returned to the first tank as the return activated sludge and a second portion of the activated sludge is returned to the second tank. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A process for treating wastewater to simultaneously remove organic matter, nitrogen, and phosphorus, the process comprising:
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receiving plant influent wastewater and return activated sludge in a first tank operating under anoxic conditions; mixing the plant influent wastewater with the return activated sludge to form a mixed liquor, wherein the mixed liquor comprises bacterial populations that are capable of fermenting dissolved organic matter and particulate organic matter; fermenting the dissolved organic matter and the particulate organic matter, by the bacterial populations, to provide a carbon source in the first tank thus eliminating a need for an addition of an external carbon source; transferring the mixed liquor to a second tank operating under microaerophilic conditions to allow for further fermentation of the dissolved organic matter and the particulate organic matter providing an additional carbon source to promote development of the bacterial populations used for simultaneous phosphorus release and phosphorus uptake in the second tank; transferring the mixed liquor to a third tank that separates treated effluent from activated sludge containing the bacterial populations for fermenting the dissolved organic matter and the particulate organic matter; and recycling a portion of the activated sludge containing the bacterial populations to the first tank as the return activated sludge. - View Dependent Claims (10, 11, 12, 13)
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14. A method for treating wastewater to simultaneously remove organic matter, nitrogen, and phosphorus, the process comprising:
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contacting plant influent wastewater with return activated sludge in an anoxic tank to form a mixed liquor; flowing the mixed liquor to an aerated tank operating under microaerophilic conditions to allow for fermentation of particulate organic matter and dissolved organic matter, wherein the microaerophilic conditions in the aerated tank further allow for simultaneous nitrification, denitrification, phosphorous release, and phosphorus uptake in the aerated tank; flowing the mixed liquor to a membrane tank to separate plant effluent wastewater from activated sludge; recycling a portion of the activated sludge to the anoxic tank as the return activated sludge; and transferring the plant effluent wastewater for further processing. - View Dependent Claims (15, 16, 17)
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Specification