Patent US2239581A successfully refreshed from Google Patents.
Patent US4698163A successfully refreshed from Google Patents.
US4698163A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Treatment of phosphate-containing wastewater
Assignee: Cyprus Amax Minerals Co
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Filing: 1985-11-12
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Granted: 1987-10-06
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Expires: 2005-11-12
Abstract
Abstract A method is provided for treating contaminated wastewater of pH ranging from about 1.5 to 3 containing phosphate ions and fluoride ions. The method comprises treating the said wastewater with an amount of alkaline agent selected from the group consisting of limestone (CaCO 3 ) and lime [CaO or Ca(OH) 2 ] sufficient to raise and maintain the pH at a level of about 3.5 to 6.5 following uniform mixing thereof in a first stage precipitation step to effect substantial precipitation of the contaminants. The treated wastewater is passed to a first stage settler to effect solid/liquid separation and provide a sludge of the precipitated contaminants which is removed and separated to provide an effluent substantially impoverished in the aforementioned contaminants, following which the contaminant-impoverished effluent is treated in a second stage precipitation step with lime in an amount sufficient to raise and maintain the pH of the effluent at a level of at least about 10.5 to effect further precipitation of said contaminants having improved settling properties, which precipitate is separated and removed to provide a clear effluent characterized in that further precipitation of solids therein is substantially minimized or eliminated downstream from where the effluent is discharged.
Inventors
- 👤 John F. Zibrida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 23:09
CPC Classifications
C; C02; C02F; C02F1/00; C02F1/52; C02F1/5236; Y; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/906; Y10S210/915
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
263 words
A method for the treatment of contaminated wastewater of pH ranging from about 1.5 to 3 containing at least about 100 ppm phosphorus as phosphate ions and at least about 50 ppm fluorine as fluride ions which comprises: treating said wastewater with an amount of an alkaline agent selected from the group consisting of limestone (CaCO 3 ) and lime sufficient to raise and maintain the pH at a level of about 3.5 to 6.5 following uniform mixing thereof in a first stage precipitation to effect substantial precipitation of said contaminants, passing said treated wastewater to a first stage settler to effect solid/liquid separation thereof sufficient to provide a sludge of said precipitated contaminants which is removed for disposal thereof and provide an effluent substantially impoverished in said contaminants, treating said contaminant-impoverished effluent in a second stage precipitation with lime in an amount sufficient to raise and maintain the pH of said effluent at a level of at least about 10.8 to less than 12 following uniform mixing thereof, whereby a further precipitate of said contaminants is produced having improved settling properties, passing said lime-treated effluent at said pH to a second stage settler at which a flocculant is added to provide flocs of said precipitate which settle rapidly to form a sludge thereof and a clearer effluent, removing said sludge and discharging said effluent containing less than about 5 ppm phosphorus and less than about 10 ppm fluoride ions, whereby a clearer effluent is provided characterized in that further precipitation of solids is substantially minimized or eliminated downstream of said effluent discharge.
Claim 2
Independent Claim
263 words
A method for the treatment of contaminated wastewater of pH ranging from about 1.5 to 3 containing at least about 100 ppm phosphorus as phosphate ions and at least about 50 ppm fluorine as fluride ions which comprises: treating said wastewater with an amount of an alkaline agent selected from the group consisting of limestone (CaCO 3 ) and lime sufficient to raise and maintain the pH at a level of about 3.5 to 6.5 following uniform mixing thereof in a first stage precipitation to effect substantial precipitation of said contaminants, passing said treated wastewater to a first stage settler to effect solid/liquid separation thereof sufficient to provide a sludge of said precipitated contaminants which is removed for disposal thereof and provide an effluent substantially impoverished in said contaminants, treating said contaminant-impoverished effluent in a second stage precipitation with lime in an amount sufficient to raise and maintain the pH of said effluent at a level of at least about 10.8 to less than 12 following uniform mixing thereof, whereby a further precipitate of said contaminants is produced having improved settling properties, passing said lime-treated effluent at said pH to a second stage settler at which a flocculant is added to provide flocs of said precipitate which settle rapidly to form a sludge thereof and a clearer effluent, removing said sludge and discharging said effluent containing less than about 5 ppm phosphorus and less than about 10 ppm fluoride ions, whereby a clearer effluent is provided characterized in that further precipitation of solids is substantially minimized or eliminated downstream of said effluent discharge.
Claim 3
Dependent Claim
22 words
The method of claim 1, wherein a portion of the sludge from the second stage settler is recycled to second stage precipitation.
Claim 4
Dependent Claim
30 words
The method of claim 2, whrein the sludge portion recycled to second stage precipitation amounts to about 30% to 90% by volume of the sludge discharged from the second settler.
Claim 5
Dependent Claim
25 words
The metohd of claim 3, wherein the sludge remaining following sludge recycle from the second stage settler is discharged and/or recycled to first stage precipitation.
Claim 6
Independent Claim
278 words
A method for the treatment of contaminated wastewater of pH ranging from about 1.5 to 3 containing at least about 100 ppm phosphorus as phosphate ions and at least about 50 ppm fluorine as fluoride ions which comprises: treating said wastewater with an amount of an alkaline agent selected from the group consisting of limestone (CaCO 3 ) and lime sufficient to raise and maintain the pH at a level of about 3.5 to 6.5 following uniform mixing thereof in a first stage precipitation to effect substantial precipitation of said contaminants, passing said treated wastewater to a first stage settler to effect solid/liquid separation thereof sufficient to provide a sludge of said precipitated contaminants which is removed for disposal thereof and provide an effluent substantially impoverished in said contaminants, treating said contaminant-impoverished effluent in a second stage precipitation with lime in an amount sufficient to raise and maintain the pH of said effluent at a level of at least about 10.8 to less than 12 following uniform mixing thereof, whereby a further precipitate of said contaminants is produced having improved settling properties, passing said lime-treated effluent at said pH to a second stage settler at which a flocculant is added to provide flocs of said precipitate which settle rapidly to form a sludge thereof and a clear effluent, removing said sludge and discharging said effluent containing less than about 2 ppm phosphorus and less than about 5 ppm fluoride ions, whereby clearer effluent is provided characterized in that further precipitation of solids is substantially minimized or eliminated downstream of said effluent discharge, and recycling a portion of said sludge from the second stage settler to second stage precipitation.
Claim 7
Independent Claim
278 words
A method for the treatment of contaminated wastewater of pH ranging from about 1.5 to 3 containing at least about 100 ppm phosphorus as phosphate ions and at least about 50 ppm fluorine as fluoride ions which comprises: treating said wastewater with an amount of an alkaline agent selected from the group consisting of limestone (CaCO 3 ) and lime sufficient to raise and maintain the pH at a level of about 3.5 to 6.5 following uniform mixing thereof in a first stage precipitation to effect substantial precipitation of said contaminants, passing said treated wastewater to a first stage settler to effect solid/liquid separation thereof sufficient to provide a sludge of said precipitated contaminants which is removed for disposal thereof and provide an effluent substantially impoverished in said contaminants, treating said contaminant-impoverished effluent in a second stage precipitation with lime in an amount sufficient to raise and maintain the pH of said effluent at a level of at least about 10.8 to less than 12 following uniform mixing thereof, whereby a further precipitate of said contaminants is produced having improved settling properties, passing said lime-treated effluent at said pH to a second stage settler at which a flocculant is added to provide flocs of said precipitate which settle rapidly to form a sludge thereof and a clear effluent, removing said sludge and discharging said effluent containing less than about 2 ppm phosphorus and less than about 5 ppm fluoride ions, whereby clearer effluent is provided characterized in that further precipitation of solids is substantially minimized or eliminated downstream of said effluent discharge, and recycling a portion of said sludge from the second stage settler to second stage precipitation.
Claim 8
Dependent Claim
41 words
The method of claim 5, wherein the amount of sludge recycled amounts to about 30% to 90% by volume of the sludge discharged from the second stage settler, and wherein the remaining sludge is discharged and/or recycled to first stage precipitation.
Claim 9
Independent Claim
24 words
The method of claims 1 and 5, wherein the effluent prior to discharge is adjusted to a pH value of about 8.5 or less.
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) | 1990-10-05 | 1991-04-06 | 1991-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-05 | 1995-04-06 | 1995-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-05 | 1999-04-06 | 1999-10-06 | $7700.00 | Window Closed / Lapsed |