Patent US4160731A successfully refreshed from Google Patents.
US4160731A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for dewatering sewage sludges disinfected with lime
Assignee: Wyeth Holdings LLC
•
Filing: 1978-04-18
•
Granted: 1979-07-10
•
Expires: 1998-04-18
Abstract
Abstract A copolymer of acrylamide and 3-(methacrylamido)propyl-trimethyl ammonium chloride is effective in the dewatering of sewage sludges that have been disinfected with lime.
Inventors
- 👤 Carlos L. Doyle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 21:02
CPC Classifications
C; C02; C02F; C02F11/00; C02F11/12; C02F1/00; C02F1/52; C02F1/54; Y; Y10; Y10S; Y10S210/00; Y10S210/901
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
106 words
A process for recovering disinfected solids suitable for use as landfill from sewage sludge which process comprises treating said sewage sludge with an amount of lime sufficient to provide a pH of at least 12.0, adding to the thus treated sludge an effective amount of a copolymer containing repeating units of ##STR3## wherein x represents a mole percent in the range of about 3-60 and y, correspondingly, a mole percent in the range of about 97-40, said copolymer having a standard viscosity of at least about 1.5 cps., filtering the resulting sludge to remove water therefrom, and disposing of the disinfected solids thus obtained as landfill.
Claim 2
Dependent Claim
106 words
A process for recovering disinfected solids suitable for use as landfill from sewage sludge which process comprises treating said sewage sludge with an amount of lime sufficient to provide a pH of at least 12.0, adding to the thus treated sludge an effective amount of a copolymer containing repeating units of ##STR3## wherein x represents a mole percent in the range of about 3-60 and y, correspondingly, a mole percent in the range of about 97-40, said copolymer having a standard viscosity of at least about 1.5 cps., filtering the resulting sludge to remove water therefrom, and disposing of the disinfected solids thus obtained as landfill.
Claim 3
Dependent Claim
19 words
The process of claim 1 wherein the amount of lime employed is sufficient to provide a pH of 12.5.
Claim 4
Dependent Claim
18 words
The process of claim 1 wherein said copolymer has a standard viscosity of at least about 2.5 cps.
Claim 5
Dependent Claim
22 words
The process of claim 1 wherein x represents a mole percent of about 10 and y represents a mole percent of 90.
Claim 6
Dependent Claim
17 words
The process of claim 4 wherein said copolymer has a standard viscosity of at least 2.5 cps.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-07-09 | 1983-01-08 | 1983-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-07-09 | 1987-01-08 | 1987-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-07-09 | 1991-01-08 | 1991-07-10 | $7700.00 | Window Closed / Lapsed |