US3932278A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Filter cleaning method
Assignee: US Filter Zimpro Inc
•
Filing: 1974-02-15
•
Granted: 1976-01-13
•
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 01:07
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.
References Cited (Backward Citations)
US1634154A
Cited
US966177A
Cited
US1197640A
Cited
US1990214A
Cited
US2144051A
Cited
US2069621A
Cited
US2443373A
Cited
US2648440A
Cited
US2966431A
Cited
US3078224A
Cited
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 |