US4385996A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control of trihalomethanes in water treatment
Assignee: POLYPURE Inc 2859 PACES FERRY ROAD SUITE 630 ATLANTA GA 30339
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Filing: 1981-11-03
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Granted: 1983-05-31
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Expires: 2001-11-03
Abstract
Abstract Trihalomethanes (THM's) in water, particularly in drinking water, are substantially reduced by treatment of the water with small amounts, i.e., below about 50 ppm, of sulfite ion supplied by sodium metabisulfite or sulfur dioxide. The addition to the water of the sodium metabisulfite alters the structure of the THM's precursor and lowering the chlorine demand. The sulfite ion may be introduced prior to chlorination, or at an intermediate stage of the chlorination, or in adjunct with the chlorination which permits the use of substantially reduced amounts of chlorination.
Inventors
- 👤 Timothy W. McCarthy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 22:12
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/70; C02F1/72; C02F1/76; C02F2303/00; C02F2303/18; C02F2303/185; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/908
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
102 words
A method of treating water to disinfect the water and reduce the formation of trihalomethanes which comprises adding to the water from about 0.1 to about 50 parts per million of sulfite ion supplied by a compound selected from the group consisting of sodium metabisulfite and sulfur dioxide to reduce the chlorine demand and thereafter adding to the water sufficient chlorine to react with any biological materials present and maintain a residual amount of chlorine sufficient to disinfect the water and make the water potable, whereby the formation of trihalomethanes present in the water amounts to less than 100 parts per billion.
Claim 2
Independent Claim
102 words
A method of treating water to disinfect the water and reduce the formation of trihalomethanes which comprises adding to the water from about 0.1 to about 50 parts per million of sulfite ion supplied by a compound selected from the group consisting of sodium metabisulfite and sulfur dioxide to reduce the chlorine demand and thereafter adding to the water sufficient chlorine to react with any biological materials present and maintain a residual amount of chlorine sufficient to disinfect the water and make the water potable, whereby the formation of trihalomethanes present in the water amounts to less than 100 parts per billion.
Claim 3
Dependent Claim
14 words
The method of claim 1 wherein the sulfite ion is supplied by sodium metabisulfite.
Claim 4
Dependent Claim
14 words
The method of claim 1 wherein the sulfite ion is supplied by sulfur dioxide.
Claim 5
Dependent Claim
25 words
The method of claim 1 wherein the chlorine is added from about 0.5 to about 24 hours after addition of the sulfite ion supplying compound.
Claim 6
Dependent Claim
27 words
The method of claim 1 wherein the amount of sulfite ion supplying compound added to the water is from about 0.5 to about 20 parts per million.
Claim 7
Dependent Claim
22 words
The method of claim 1 wherein the formation of trihalomethanes present in the water amounts to less than 80 parts per billion.
Claim 8
Dependent Claim
23 words
The method of claim 1 wherein the treated water is first coagulated and said sulfite ion is added subsequent to the coagulation step.
Claim 9
Dependent Claim
20 words
The method of claim 1 wherein at least part of the sulfite ion supplying compound is added simultaneously with prechlorination.
Claim 10
Dependent Claim
38 words
The method of claim 1 wherein at least part of the sulfite ion supplying compound is added intermediate of the chlorination treatment of the water and an additional amount of the sulfite ion supplying compound is added post-chlorination.
References Cited (Backward Citations)
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US3994806A
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US3953330A
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US4282104A
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US4243525A
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US4340489A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-30 | 1986-11-29 | 1987-05-31 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-30 | 1990-11-29 | 1991-05-31 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-30 | 1994-11-29 | 1995-05-31 | $7700.00 | Window Closed / Lapsed |