US4110212A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of treating a waste liquid containing polluting compounds
Assignee: LAIDLAW RANSPORTATION Ltd
•
Filing: 1977-04-21
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Granted: 1978-08-29
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Expires: 1997-04-21
Abstract
Abstract Waste liquid containing polluting compounds with an acidic ferrous salt solution to adjust the pH of the liquid to a value within the range of from about 2 to about 5 and to reduce polluting compounds in the waste liquid to a form capable of reacting with an alkali to produce a precipitate. The adjusted waste liquid is then reacted with an alkali to raise the pH of the liquid to a value within the range of from about 9 to about 12.5 and to produce said precipitate. The alkaline waste liquid is then reacted with a silicic compound to form large complex silicate molecules with the precipitate and consequent solidification of the waste liquid into a stable, non-polluting solid.
Inventors
- 👤 David Krofchak
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:36
CPC Classifications
C; C02; C02F; C02F11/00; C02F11/008; C02F1/00; C02F1/52; C02F1/5236; C02F2101/00; C02F2101/10; C02F2101/16; C02F2101/18; C02F2101/20; C02F2101/22
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
127 words
A method of treating a waste liquid containing polluting compounds, including reacting the waste liquid with an acidic ferrous salt solution to adjust the pH of the liquid to a value within the range of from about 2 to about 5 and to reduce polluting compounds in the waste liquid to a form capable of reacting with an alkali to produce a precipitate, reacting the adjusted waste liquid with an alkali to raise the pH of the liquid to a value within the range of from about 9 to about 12.5 and to produce said precipitate, and reacting the alkaline waste liquid with a silicic compound to form large complex silicate molecules with the precipitate and consequent solidification of the waste liquid into a stable, non-polluting solid.
Claim 2
Independent Claim
127 words
A method of treating a waste liquid containing polluting compounds, including reacting the waste liquid with an acidic ferrous salt solution to adjust the pH of the liquid to a value within the range of from about 2 to about 5 and to reduce polluting compounds in the waste liquid to a form capable of reacting with an alkali to produce a precipitate, reacting the adjusted waste liquid with an alkali to raise the pH of the liquid to a value within the range of from about 9 to about 12.5 and to produce said precipitate, and reacting the alkaline waste liquid with a silicic compound to form large complex silicate molecules with the precipitate and consequent solidification of the waste liquid into a stable, non-polluting solid.
Claim 3
Dependent Claim
21 words
A method according to claim 1 wherein the acidic ferrous salt solution is a solution containing ferrous sulphate and sulphuric acid.
Claim 4
Dependent Claim
11 words
A method according to claim 1 wherein the alkali is lime.
Claim 5
Dependent Claim
14 words
A method according to claim 1 wherein the alkali comprises lime and caustic soda.
Claim 6
Dependent Claim
51 words
A method according to claim 1 wherein silicic compound is a compound which becomes active to produce said large complex silicate molecules when the pH of the waste liquid is in the range of from about 9 to about 12.5, and is relatively inactive when the pH is below said range.
Claim 7
Dependent Claim
36 words
A method according to claim 1 wherein the silicic compound is selected from the group consisting of sodium silicate, cement, fly ash, general ash, siliceous slag, siliceous silt, clay, sand and soil of a silicic nature.
Claim 8
Dependent Claim
55 words
A method according to claim 1 wherein the adjusted liquid is reacted with an alkali to raise the pH to about 9 and to produce said precipitate, and an alkaline earth metal compound is added to raise the pH to a higher value and cause the silicic compound to form said large complex silicate molecules.
Claim 9
Dependent Claim
12 words
A method according to claim 1 wherein the alkali comprises caustic soda.
References Cited (Backward Citations)
US3404088A
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US3183186A
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US3342731A
Cited
US3763038A
Cited
US3928195A
Cited
US4025430A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-08-28 | 1982-02-27 | 1982-08-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-08-28 | 1986-02-27 | 1986-08-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-08-28 | 1990-02-27 | 1990-08-29 | $7700.00 | Window Closed / Lapsed |