Patent US34034A successfully refreshed from Google Patents.
Patent US4444667A successfully refreshed from Google Patents.
US4444667A
Expired / Lapsed
US
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Flocculant for sludges
Assignee: BASF SE
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Filing: 1982-07-12
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Granted: 1984-04-24
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Expires: 2002-07-12
Abstract
Abstract Sludges are flocculated by the addition of a polymer which is prepared by the homopolymerization of N-vinylformamide in the presence of a free-radical polymerization initiator to give a poly-N-vinylformamide, followed by hydrolysis of from 10 to 90% of the formyl groups in the poly-N-vinylformamide.
Inventors
- 👤 Hans Burkert
- 👤 Friedrich Brunnmueller
- 👤 Karl-Heinz Beyer
- 👤 Michael Kroener
- 👤 Hans Mueller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 13:39
CPC Classifications
D; D21; D21H; D21H17/00; D21H17/20; D21H17/33; D21H17/34; D21H17/41; D21H17/44; D21H17/45; D21H17/455; C; C08; C08F; C08F8/00
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
99 words
A process for flocculating sewage sludge or sludge from communal or industrial treatment plants which comprises (a) adding to the sludge a flocculant in sufficient amount to flocculate said sludge wherein said flocculant is a polymer having a Fikentscher K value of about 80 to 200 and prepared by homopolymerization of a compound of the formula CH 2 ═CH--NH--CHO (n-vinylformamide) in the presence of a free-radical polymerization initiator to give a poly-N-vinylformamide, followed by hydrolysis of from 10 to 90% of the formyl groups in the poly-N-vinylformamide, and then (b) separating the flocculated sludge from the residual watery liquid.
Claim 2
Dependent Claim
99 words
A process for flocculating sewage sludge or sludge from communal or industrial treatment plants which comprises (a) adding to the sludge a flocculant in sufficient amount to flocculate said sludge wherein said flocculant is a polymer having a Fikentscher K value of about 80 to 200 and prepared by homopolymerization of a compound of the formula CH 2 ═CH--NH--CHO (n-vinylformamide) in the presence of a free-radical polymerization initiator to give a poly-N-vinylformamide, followed by hydrolysis of from 10 to 90% of the formyl groups in the poly-N-vinylformamide, and then (b) separating the flocculated sludge from the residual watery liquid.
Claim 3
Dependent Claim
25 words
A process as claimed in claim 1, wherein, in the polymer employed, from 40 to 80% of the formyl groups of the poly-N-vinylformamide are hydrolyzed.
Claim 4
Dependent Claim
39 words
A process as claimed in claim 1, wherein the solids content of the sludge is from 2 to 8% by weight, and the amount of flocculant added to the sludge is from 100 to 350 g/m 3 of sludge.
References Cited (Backward Citations)
GB618175A
Cited
DE1224304B
Cited
US3424791A
Cited
DE1817309A1
Cited
FR2076966A5
Cited
US3715336A
Cited
JPS5199693A
Cited
US4217214A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-04-24 | 1987-10-24 | 1988-04-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-04-24 | 1991-10-24 | 1992-04-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-04-24 | 1995-10-24 | 1996-04-24 | $7700.00 | Window Closed / Lapsed |