US4076515A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method for treatment of digester supernatant and other streams in wastewater treatment facilities
Assignee: Individual
•
Filing: 1975-07-09
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Granted: 1978-02-28
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Expires: 1995-07-09
Abstract
Abstract Digester supernatants and/or liquors from sludge dewatering are reacted with an excess of an alkaline reagent having a stronger cation than the ammonium ion and the reaction product is separated into a solution containing aqueous ammonia and solids. The aqueous ammonia derived from the separation stage is heated by free steam under a lowered pressure to free ammonia in gaseous form. The ammonia as a gas, or adsorbed in water, or adsorbed in an acid, or as an acid salt is then mixed with conventionally dried sludge to increase the nitrogen content of the sludge from approximately 1-2 percent to as high as 10 percent.
Inventors
- 👤 M. David Rickard
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 21:05
CPC Classifications
C; C02; C02F; C02F11/00; C02F11/12; C02F1/00; C02F1/58; C02F1/586; C05; C05F; C05F7/00; Y; Y02; Y02A; Y02A40/00; Y02A40/10; Y02A40/20; Y02E; Y02E50/00; Y02E50/30; Y02W; Y02W30/00; Y02W30/40; Y10; Y10S; Y10S210/00; Y10S210/918
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
155 words
A method of treating waste water in a sewage treatment plant to remove ammonia comprising the sequential steps of: A. reducing said waste water to sludge; B. placing said sludge in an anaerobic digester; (1) converting a substantial quantity of the putrescible organic material found in said sludge to methane and carbon dioxide, and, (2) converting a substantial quantity of nitrogen found in said sludge to ammonia; C. removing the digester supernatant; D. dewatering said digested sludge to separate from the sludge, dewatering liquor being substantially composed of water and water soluble ammonia; E. combining said supernatant with said dewatering liquor; F. reacting with said supernatant and dewatering liquor, to form a reaction product, a stoichiometric excess of lime thus converting ammonia salts found in the supernatant and dewatering liquor to free or aqueous ammonia; G. rendering the ammonia less soluble in the reaction product by applying to said product, live steam under reduced pressure.
Claim 2
Independent Claim
155 words
A method of treating waste water in a sewage treatment plant to remove ammonia comprising the sequential steps of: A. reducing said waste water to sludge; B. placing said sludge in an anaerobic digester; (1) converting a substantial quantity of the putrescible organic material found in said sludge to methane and carbon dioxide, and, (2) converting a substantial quantity of nitrogen found in said sludge to ammonia; C. removing the digester supernatant; D. dewatering said digested sludge to separate from the sludge, dewatering liquor being substantially composed of water and water soluble ammonia; E. combining said supernatant with said dewatering liquor; F. reacting with said supernatant and dewatering liquor, to form a reaction product, a stoichiometric excess of lime thus converting ammonia salts found in the supernatant and dewatering liquor to free or aqueous ammonia; G. rendering the ammonia less soluble in the reaction product by applying to said product, live steam under reduced pressure.
Claim 3
Dependent Claim
52 words
The method of treating waste water as recited in claim 1 further comprising the steps of A. drying the sludge; B. reacting the ammonia recovered from the waste water with acid to form an ammonium salt; and C. mixing the ammonium salt with the dried sludge to form a nitrogen enriched fertilizer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-27 | 1981-08-29 | 1982-02-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-27 | 1985-08-29 | 1986-02-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-27 | 1989-08-29 | 1990-02-28 | $7700.00 | Window Closed / Lapsed |