US3716484A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for substantial removal of phosphates from wastewaters
Assignee: Velsicol Chemical LLC
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Filing: 1971-05-10
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Granted: 1973-02-13
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Expires: 1991-05-10
Abstract
Abstract The invention is directed to a process for removing substantial amounts of soluble phosphates from wastewaters at primary treatment stages by means of chemical precipitation utilizing calcium chloride at a pH of 8-9.5, or a combination of calcium chloride and calcium hydroxide. An equivalent amount of calcia may be used in place of the calcium hydroxide.
Inventors
- 👤 P Lincoln
- 👤 P Delamater
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:41
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/52; C02F1/5236; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/906
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
53 words
A process for substantially removing dissolved phosphates from wastewater consisting essentially of the steps of adding calcium hydroxide to said water to provide an alkaline waste water having a pH range of from 8 to 9.5, treating said alkaline water with calcium chloride to thereby precipitate and consequently remove the insoluble phosphates formed.
Claim 2
Dependent Claim
53 words
A process for substantially removing dissolved phosphates from wastewater consisting essentially of the steps of adding calcium hydroxide to said water to provide an alkaline waste water having a pH range of from 8 to 9.5, treating said alkaline water with calcium chloride to thereby precipitate and consequently remove the insoluble phosphates formed.
Claim 3
Dependent Claim
18 words
A process according to claim 1 wherein calcium hydroxide is added in amounts up to about 50 ppm.
References Cited (Backward Citations)
US3462360A
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US3385785A
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US3431200A
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US3440165A
Cited
US3423309A
Cited
US3617569A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-13 | 1976-08-14 | 1977-02-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-13 | 1980-08-14 | 1981-02-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-13 | 1984-08-14 | 1985-02-13 | $7700.00 | Window Closed / Lapsed |