IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
|
출원번호 |
US-0210487
(2011-08-16)
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등록번호 |
US-8808544
(2014-08-19)
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발명자
/ 주소 |
- Smith, George W.
- Liu, Wenjun
- Doyle, Michael L.
- McKean, Colin M.
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출원인 / 주소 |
- Evoqua Water Technologies LLC
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인용정보 |
피인용 횟수 :
0 인용 특허 :
157 |
초록
Systems and methods for treating wastewater including a dissolved air flotation operation performed upon a portion of a mixed liquor output from a contact tank prior to the mixed liquor entering a biological treatment tank.
대표청구항
▼
1. A wastewater treatment system comprising: a contact tank having an first inlet configured to receive wastewater to be treated, a second inlet, and an outlet, the contact tank configured to mix the wastewater to be treated with activated sludge to form a first mixed liquor;a dissolved air flotatio
1. A wastewater treatment system comprising: a contact tank having an first inlet configured to receive wastewater to be treated, a second inlet, and an outlet, the contact tank configured to mix the wastewater to be treated with activated sludge to form a first mixed liquor;a dissolved air flotation unit having an inlet in fluid communication with the outlet of the contact tank and a gas inlet configured to introduce gas into the dissolved air flotation unit to facilitate the flotation of suspended matter from the first mixed liquor and the removal of the suspended matter from the dissolved air flotation unit, the dissolved air flotation unit configured to separate the suspended matter from a portion of the first mixed liquor to form a solids-lean dissolved air flotation unit effluent and waste solids, to output the waste solids through a solids outlet of the dissolved air flotation unit, and to output the solids-lean dissolved air flotation unit effluent through an effluent outlet of the dissolved air flotation unit;a biological treatment unit having a first inlet in fluid communication with the outlet of the contact tank, a second inlet, a third inlet in fluid communication with the effluent outlet of the dissolved air flotation unit, and an outlet, the biological treatment unit configured to biologically break down organic components of the first mixed liquor and of an effluent from the dissolved air flotation unit to form a second mixed liquor;a clarifier having an inlet in fluid communication with the outlet of the biological treatment unit, an effluent outlet, and a return activated sludge outlet, the clarifier configured to output a clarified effluent through the effluent outlet and a return activated sludge though the return activated sludge outlet;a dissolved air flotation unit effluent conduit extending between the effluent outlet of the dissolved air flotation unit and the third inlet of the biological treatment unit;a mixed liquor conduit extending between the outlet of the contact tank and the first inlet of the biological treatment unit;a first return activated sludge conduit extending between the return activated sludge outlet of the clarifier and the second inlet of the contact tank; anda second return activated sludge conduit extending between the return activated sludge outlet of the clarifier and the second inlet of the biological treatment unit. 2. The system of claim 1, where the biological treatment unit includes: an aerated anoxic region having a first inlet in fluid communication with the outlet of the contact tank, a second inlet, and an outlet; andan aerobic region having a first inlet in fluid communication with the outlet of the aerated anoxic region, a second inlet in fluid communication with the effluent outlet of the dissolved air flotation unit, and an outlet. 3. The system of claim 2, wherein the aerated anoxic region and the aerobic region are included in a same treatment tank. 4. The system of claim 3, wherein the aerated anoxic region and the aerobic region are separated by a partition. 5. The system of claim 2, wherein the aerated anoxic region is included in a first treatment tank and the aerobic region is included in a second treatment tank distinct from the first treatment tank. 6. The system of claim 2, comprising a first sub-system including the contact tank and the dissolved air flotation unit which is physically separated from a second sub-system including the biological treatment unit and the clarifier. 7. The system of claim 2, wherein the contact tank and the aerated anoxic region are included in a same tank. 8. The system of claim 1, further comprising an anaerobic digester having an inlet in fluid communication with the solids outlet of the dissolved air flotation unit and an outlet. 9. The system of claim 8, wherein the outlet of the anaerobic digester is in fluid communication with at least one of the contact tank and the biological treatment unit. 10. The system of claim 9, further comprising a primary clarifier having an inlet in fluid communication with a source of the wastewater to be treated and a solids-lean outlet in fluid communication with the contact tank. 11. The system of claim 10, further comprising a thickener having an inlet in fluid communication with a solids-rich outlet of the primary clarifier and an outlet in fluid communication with the anaerobic digester. 12. The system of claim 10, wherein the primary clarifier further comprises a solids-rich outlet in fluid communication with the dissolved air flotation unit. 13. A method of treating wastewater comprising: introducing the wastewater into a contact tank including an activated sludge;mixing the wastewater with activated sludge in the contact tank to form a mixed liquor;directing a first portion of the mixed liquor to a dissolved air flotation unit;separating the first portion of the mixed liquor in the dissolved air flotation unit to form a solids-lean dissolved air flotation unit effluent and waste biosolids;directing a second portion of the mixed liquor to a biological treatment unit;directing the solids-lean dissolved air flotation unit effluent to the biological treatment unit;biologically treating the mixed liquor and the solids-lean dissolved air flotation unit effluent in the biological treatment unit to form a biologically treated mixed liquor;directing the biologically treated mixed liquor to a clarifier;separating the biologically treated mixed liquor in the clarifier to form a clarified effluent and a return activated sludge;recycling a first portion of the return activated sludge to the contact tank;recycling a second portion of the return activated sludge to the biological treatment unit; anddirecting the clarified effluent to a treated wastewater outlet. 14. The method of claim 13, wherein the biological treatment unit includes an aerated anoxic treatment unit and an aerobic treatment unit, and the method further comprises: directing the second portion of the mixed liquor to the aerated anoxic treatment unit; treating the second portion of the mixed in the aerated anoxic treatment unit to form an anoxic mixed liquor; directing the anoxic mixed liquor to the aerobic treatment unit;directing the solids-lean dissolved air flotation tank effluent to the aerobic treatment unit;treating the anoxic mixed liquor and the solids-lean dissolved air flotation unit effluent in the aerobic treatment tank to form an aerobic mixed liquor;directing the aerobic mixed liquor to the clarifier;separating the aerobic mixed liquor in the clarifier to form the clarified effluent and the return activated sludge; andrecycling the second portion of the return activated sludge to the aerated anoxic treatment unit. 15. The method of claim 14, wherein the first portion of the return activated sludge and the second portion of the return activated sludge comprise about 100% of all return activated sludge formed in the clarifier. 16. The method of claim 15, wherein the first portion of the return activated sludge comprises between about 10% and about 20% of all return activated sludge recycled from the clarifier. 17. The method of claim 13, wherein the first portion of the mixed liquor comprises between about one third and about two thirds of all mixed liquor formed in the contact tank. 18. The method of claim 17, wherein the dissolved air flotation unit removes between about 60% and about 100% of suspended solids in the first portion of the mixed liquor as waste biosolids. 19. The method of claim 18, wherein an amount of suspended solids removed in the dissolved air flotation unit is adjusted based upon a concentration of a bacteria in the biological treatment unit. 20. The method of claim 17, wherein the dissolved air flotation unit removes between about 40% and about 80% of biological oxygen demand in the first portion of the mixed liquor. 21. The method of claim 13, further comprising treating at least a portion of the waste biosolids in an anaerobic digester to produce an anaerobically digested sludge. 22. The method of claim 21, further comprising recycling at least a portion of the anaerobically digested sludge to at least one of the contact tank and the biological treatment unit. 23. The method of claim 22, further comprising: separating the water to be treated into a solids-lean portion and a solids-rich portion;directing the solids-rich portion into a thickener to produce a solids-rich output and a solids-lean effluent;directing the solids-lean portion into the contact tank;directing a solids-rich output from the thickener into the anaerobic digester; anddirecting a solids-lean effluent of the thickener into the contact tank. 24. A method of facilitating increased operating efficiency of a wastewater treatment system comprising: providing a dissolved air flotation unit in a wastewater treatment system in fluid communication between a contact tank and a biological treatment unit, the dissolved air flotation unit configured to separate a portion of a first mixed liquor output from the contact tank to form a solids-lean dissolved air flotation unit effluent and waste solids, and to direct the solids-lean dissolved air flotation unit effluent into the biological treatment unit, the dissolved air flotation unit reducing the amount of biological oxygen demand to be treated in the biological treatment unit as compared to the wastewater treatment system operating in the absence of the dissolved air flotation unit; andproviding for a solids-liquid separation unit in fluid communication downstream of the biological treatment unit to recycle a return activated sludge formed from a mixed liquor output from the biological treatment unit to the contact tank. 25. The method of claim 24, further comprising providing for between about 10% and about 20% of the return activated sludge formed to be recycled to the contact tank. 26. The method of claim 25, further comprising adjusting an amount of return activated sludge recycled to the contact tank based upon a concentration of a bacteria in the biological treatment unit. 27. The method of claim 24, further comprising providing an anaerobic digester having an inlet in fluid communication with an outlet of the dissolved air flotation unit and an outlet in fluid communication with at least one of an inlet of the contact tank and an inlet of the biological treatment unit.
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