Patent US3932278A successfully refreshed from Google Patents.
US3932278A
Expired / Lapsed
US
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Filter cleaning method
Assignee: US Filter Zimpro Inc
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Filing: 1974-02-15
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Granted: 1976-01-13
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Expires: 1994-02-15
Abstract
Abstract A method of cleaning sand or multi-media filters which comprises a process of backwashing the filter with water containing a high concentration of chlorine or ozone.
Inventors
- 👤 John A. Meidl
- 👤 Thomas J. Vollstedt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:14
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/001; C02F1/28; C02F1/283; C02F1/72; C02F1/76; C02F1/78; C02F2303/00; C02F2303/16
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
71 words
The method of backwashing sand or multi-media filters employed in wastewater treatment or sewage treatment plants in order to remove a coating therefrom, said coating consisting at least in part of activated carbon, which comprises contacting the filter media with water containing between about 50 and 500 ppm of chlorine for a period of between about 2 minutes and 1200 minutes, and backwashing the filter to remove the sloughed off coating.
Claim 2
Independent Claim
71 words
The method of backwashing sand or multi-media filters employed in wastewater treatment or sewage treatment plants in order to remove a coating therefrom, said coating consisting at least in part of activated carbon, which comprises contacting the filter media with water containing between about 50 and 500 ppm of chlorine for a period of between about 2 minutes and 1200 minutes, and backwashing the filter to remove the sloughed off coating.
Claim 3
Dependent Claim
17 words
The method according to claim 1 in which gaseous chlorine is used as a source of chlorine.
Claim 4
Dependent Claim
19 words
The method according to claim 1 in which hypochlorite is applied to the filter as a source of chlorine.
Claim 5
Independent Claim
71 words
The method of backwashing sand or multi-media filters employed in wastewater treatment or sewage treatment plants in order to remove a coating therefrom, said coating consisting at least in part of activated carbon, which comprises contacting the filter media with water containing between about 20 and 200 ppm of ozone for a period of between about 2 minutes and 1200 minutes, and backwashing the filter to remove the sloughed off coating.
Claim 6
Independent Claim
71 words
The method of backwashing sand or multi-media filters employed in wastewater treatment or sewage treatment plants in order to remove a coating therefrom, said coating consisting at least in part of activated carbon, which comprises contacting the filter media with water containing between about 20 and 200 ppm of ozone for a period of between about 2 minutes and 1200 minutes, and backwashing the filter to remove the sloughed off coating.
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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) | 1979-01-12 | 1979-07-14 | 1980-01-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-12 | 1983-07-14 | 1984-01-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-12 | 1987-07-14 | 1988-01-13 | $7700.00 | Window Closed / Lapsed |