US4155845A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treatment of pulp mill effluents
Assignee: Rhone Poulenc Industries SA
•
Filing: 1977-05-10
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Granted: 1979-05-22
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Expires: 1997-05-10
Abstract
Abstract Pulp mill effluents, particularly soda-containing treatment liquors, are subjected to a separatory treatment comprising a pre-treatment with flocculating agent in a sub-critical amount incapable of effecting flocculation, followed by an ultrafiltration of the pre-treated effluent.
Inventors
- 👤 Bernard Ancelle
- 👤 Serge Lambert
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 16:50
CPC Classifications
C; C02; C02F; C02F9/00; B; B01; B01D; B01D21/00; B01D21/01; B01D61/00; B01D61/14; B01D61/145; C02F1/00; C02F1/44; C02F1/444; C02F1/52; C02F2103/00; C02F2103/26; C02F2103/28; Y; Y10; Y10S; Y10S210/00; Y10S210/928
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
75 words
A process for the treatment of soda-containing paper mill effluents from the bleaching of paper pulp comprising the steps of: (a) introducing a sub-critical amount of a flocculation-effective agent to the effluent, said sub-critical amount being from about 2% to about 50% of the amount necessary for true flocculation; and, p1 (b) subjecting the effluent/agent mixture to ultrafiltration, comprising ultrafiltering said mixture across a membrane which is stable to a pH of greater than 8.
Claim 2
Dependent Claim
75 words
A process for the treatment of soda-containing paper mill effluents from the bleaching of paper pulp comprising the steps of: (a) introducing a sub-critical amount of a flocculation-effective agent to the effluent, said sub-critical amount being from about 2% to about 50% of the amount necessary for true flocculation; and, p1 (b) subjecting the effluent/agent mixture to ultrafiltration, comprising ultrafiltering said mixture across a membrane which is stable to a pH of greater than 8.
Claim 3
Dependent Claim
19 words
The process of claim 1, wherein the amount of said agent introduced is from about 7% to about 15%.
Claim 4
Dependent Claim
37 words
The process of claim 1, wherein said agent is selected from the group consisting of: (a) calcium hydroxide and aluminum sulfate; (b) calcium hydroxide and carbon dioxide; (c) calcium chloride and sodium carbonate; and, (d) aluminum chlorosulfate.
Claim 5
Dependent Claim
38 words
The process of claim 3, further comprising the addition of a flocculation adjuvant of sodium acrylate/acrylamide copolymers in the range of from about 0.1 to about 10% based on the weight of the inorganic constituent of said agent.
Claim 6
Dependent Claim
29 words
The process of claim 1, wherein the ultrafiltration step comprises ultrafiltering said mixture across a membrane having a cut-off threshhold towards proteins of from about 4,000 to about 100,000.
Claim 7
Dependent Claim
29 words
The process of claim 1, wherein the ultrafiltration step comprises ultrafiltering said mixture across a membrane having a cut-off threshhold towards proteins of from about 5,000 to about 25,000.
Claim 8
Dependent Claim
17 words
The process of claim 5, wherein said membrane is stable to a pH of greater than 10.
Claim 9
Dependent Claim
26 words
The process of claim 5, wherein said membrane has a flow rate, with pure water at 2 bars, of at least about 700 l/day/m 2 .
Claim 10
Dependent Claim
26 words
The process of claim 5, wherein said membrane has a flow rate, with pure water at 2 bars, of at least about 4,000 l/day/m 2 .
Claim 11
Dependent Claim
44 words
The process of claim 5, wherein the ultrafiltration step further comprises: (a) maintaining a pressure differential across said membrane of from about 0.5 to about 20 bars; and, (b) providing a flow rate of said mixture across said membrane of at least 0.1 m/second.
Claim 12
Dependent Claim
47 words
The process of claim 5, wherein the ultrafiltration step further comprises: (a) maintaining a pressure differential across said membrane of from about 1 to about 6 bars; and, (b) providing a flow rate of said mixture across said membrane of from about 1 to about 3 m/second.
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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) | 1982-05-21 | 1982-11-20 | 1983-05-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-05-21 | 1986-11-20 | 1987-05-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-05-21 | 1990-11-20 | 1991-05-22 | $7700.00 | Window Closed / Lapsed |