Process to improve the efficiency of a membrane filter activated sludge system
First Claim
1. A process for treating BOD, nitrogen, and phosphorus containing wastewater, the process comprising:
- providing wastewater influent into an anoxic zone having activated sludge;
mixing the wastewater influent with the activated sludge in the anoxic zone to form a first mixed liquor;
providing the first mixed liquor into a first of a plurality of further treatment zones;
mixing the first mixed liquor with activated sludge in the first of the plurality of further treatment zones to form a second mixed liquor;
providing the second mixed liquor into a second of the plurality of further treatment zones;
mixing the second mixed liquor with activated sludge in the second of the plurality of further treatment zones to form a third mixed liquor;
providing the third mixed liquor into a third of the plurality of further treatment zones;
mixing the third mixed liquor with activated sludge in the third of the plurality of further treatment zones to form a fourth mixed liquor;
transferring a portion of the fourth mixed liquor from the third of the plurality of further treatment zones to a membrane bioreactor;
filtering the fourth mixed liquor to form a filtrate and an activated sludge; and
selectively recycling at least a portion of the activated sludge from the membrane bioreactor to at least one of the anoxic zone, the first of the plurality of further treatment zones, and the second of the plurality of further treatment zones.
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Accused Products
Abstract
A process for treating BOD, nitrogen and phosphorus containing wastewater, wherein the process includes the steps of providing wastewater influent into an anoxic zone having activated sludge and mixing the wastewater influent with the activated sludge in the anoxic zone to form a mixed liquor. The process further includes providing the mixed liquor into one more further treatment zones and transferring a portion of the mixed liquor from the further treatment zone to a membrane filter wherein a filtrate is separated from sludge. The process also includes selectively recycling at least a portion of the sludge to the anoxic zone as recycled activated sludge.
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Citations
23 Claims
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1. A process for treating BOD, nitrogen, and phosphorus containing wastewater, the process comprising:
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providing wastewater influent into an anoxic zone having activated sludge; mixing the wastewater influent with the activated sludge in the anoxic zone to form a first mixed liquor; providing the first mixed liquor into a first of a plurality of further treatment zones; mixing the first mixed liquor with activated sludge in the first of the plurality of further treatment zones to form a second mixed liquor; providing the second mixed liquor into a second of the plurality of further treatment zones; mixing the second mixed liquor with activated sludge in the second of the plurality of further treatment zones to form a third mixed liquor; providing the third mixed liquor into a third of the plurality of further treatment zones; mixing the third mixed liquor with activated sludge in the third of the plurality of further treatment zones to form a fourth mixed liquor; transferring a portion of the fourth mixed liquor from the third of the plurality of further treatment zones to a membrane bioreactor; filtering the fourth mixed liquor to form a filtrate and an activated sludge; and selectively recycling at least a portion of the activated sludge from the membrane bioreactor to at least one of the anoxic zone, the first of the plurality of further treatment zones, and the second of the plurality of further treatment zones. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A process for treating BOD, nitrogen and phosphorus containing wastewater, the process comprising the steps of:
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providing wastewater influent into a first anoxic zone having activated sludge; mixing the wastewater influent with the activated sludge in the first anoxic zone to form a first mixed liquor; transferring at least a portion of the first mixed liquor into an aerobic zone; mixing the at least a portion of the first mixed liquor with activated sludge in the aerobic zone to form a second mixed liquor; transferring at least a portion of the second mixed liquor into a second anoxic zone; mixing the at least a portion of the second mixed liquor with activated sludge in the second anoxic zone to form a third mixed liquor; transferring at least a portion of the third mixed liquor into a third anoxic zone; mixing the at least a portion of the third mixed liquor with activated sludge in the third anoxic zone to form a fourth mixed liquor; transferring a portion of the fourth mixed liquor from the third anoxic zone to a membrane bioreactor; filtering the portion of the fourth mixed liquor to form a filtrate and an activated sludge; and selectively recycling at least a portion of the activated sludge to at least one of the first anoxic zone, the aerobic zone, and the second anoxic zone. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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21. A process for treating BOD, nitrogen and phosphorus containing wastewater, the process comprising:
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providing wastewater into an aerobic zone having activated sludge; mixing the wastewater with the activated sludge in the aerobic zone to form a first mixed liquor having a dissolved oxygen concentration of at least 1 mg/L; providing a first portion of the first mixed liquor into a first of a plurality of downstream treatment zones; mixing the first portion of the first mixed liquor with activated sludge in the first of the plurality of downstream treatment zones to form a second mixed liquor; transferring a portion of the second mixed liquor from the first of the plurality of downstream treatment zones to a membrane bioreactor; filtering the portion of the second mixed liquor to form a filtrate and a sludge; providing oxygen to the membrane bioreactor; introducing oxygen provided to the membrane bioreactor into the sludge to form an activated sludge with a dissolved oxygen level of between about 4 mg/L and about 8 mg/L; recycling a second portion of the first mixed liquor to a first of a plurality of upstream treatment zones; recycling a portion of the activated sludge to the first of the plurality of upstream treatment zones; mixing the second portion of the first mixed liquor, the portion of the activated sludge, and wastewater in the first of the plurality of upstream treatment zones to form a third mixed liquor; and transferring a portion of the third mixed liquor to a second of the plurality of upstream treatment zones. - View Dependent Claims (22, 23)
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Specification