US4460470A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process and apparatus for the biological purification of phosphate-containing wastewater
Assignee: Linde GmbH
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Filing: 1983-02-23
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Granted: 1984-07-17
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Expires: 2003-02-23
Abstract
Abstract This invention relates to a process for the biological purification of phosphate-containing wastewater wherein the wastewater is gas-treated, i.e. aerated, in an oxygenation tank in the presence of activated sludge for degrading organic hydrocarbon compounds and absorption of phosphate by microorganisms present in the activated sludge. The wastewater-activated sludge mixture is then withdrawn from the oxygenated tank and divided, in a post clarification stage, into purified, essentially phosphate-free water and phosphate-containing sludge. The phosphate-containing sludge is recycled, at least in part, into the oxygenation tank. A partial stream of wastewater-activated sludge mixture is branched off from the oxygenation tank, and/or recycle sludge is branched off as a partial stream from the post clarification stage, and the mixture is subjected to flotation treatment for thickening. A thus-obtained, low-phosphate flotage, i.e. subnatant liquor, is discharged from the flotation unit. Likewise, resultant, phosphate-rich flotage sludge, i.e. thickened floating sludge, is discharged and heated, and after this heating, is treated anaerobically and mixed with wastewater to be purified. Subsequently, the wastewater-flotage sludge mixture is subjected to a phosphate separation and thus-produced, low-phosphate sludge is recycled into the oxygenation tank, and phosphate-enriched liquid is further treated.
Inventors
- 👤 Hans Reimann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 22:32
CPC Classifications
C; C02; C02F; C02F3/00; C02F3/02; C02F3/12; C02F3/1205; C02F3/1215; C02F1/00; C02F1/24; C02F3/30; C02F3/308; Y; Y02; Y02W; Y02W10/00; Y02W10/10; Y10; Y10S; Y10S210/00; Y10S210/902; Y10S210/906
Claims Analysis
Total Claims: 42
Claim 1
Independent Claim
225 words
In a process for the biological purification of phosphate-containing wastewater wherein the wastewater is aerated in a tank in the presence of activated sludge for degrading of organic hydrocarbon compounds and absorption of phosphate by microorganisms present in the activated sludge, the wastewater-activated sludge mixture then being withdrawn from the aerated tank and divided, in a post clarification stage, into purified, essentially phosphate-free water and phosphate-containing sludge, with the phosphate-containing sludge returned, at least in part, as recycle sludge into the aeration tank, the improvement comprising: feeding at least one of a partial stream of the wastewater-activated sludge mixture treated in the aerated tank and discharged therefrom, and at least one of a partial stream of the recycle sludge from the post-clarification stage, to a flotation separation stage for separation into a low-phosphate flotage and a thickened high-phosphate flotage sludge; separately withdrawing the low-phosphate flotage from the flotation separation stage and the thickened high-phosphate flotage sludge; heating the high-phosphate flotage sludge to a temperature above ambient temperature, and after heating, anaerobically treating the high-phosphate flotage sludge, and then mixing this high-phosphate flotage sludge with an aqueous phase; subjecting the aqueous phase-flotage sludge mixture to a phosphate separation to produce a low-phosphate sludge and a phosphate-enriched liquid; and recycling the low-phosphate sludge into the aerated tank and conducting the phosphate-enriched liquid to a further treatment step.
Claim 2
Dependent Claim
225 words
In a process for the biological purification of phosphate-containing wastewater wherein the wastewater is aerated in a tank in the presence of activated sludge for degrading of organic hydrocarbon compounds and absorption of phosphate by microorganisms present in the activated sludge, the wastewater-activated sludge mixture then being withdrawn from the aerated tank and divided, in a post clarification stage, into purified, essentially phosphate-free water and phosphate-containing sludge, with the phosphate-containing sludge returned, at least in part, as recycle sludge into the aeration tank, the improvement comprising: feeding at least one of a partial stream of the wastewater-activated sludge mixture treated in the aerated tank and discharged therefrom, and at least one of a partial stream of the recycle sludge from the post-clarification stage, to a flotation separation stage for separation into a low-phosphate flotage and a thickened high-phosphate flotage sludge; separately withdrawing the low-phosphate flotage from the flotation separation stage and the thickened high-phosphate flotage sludge; heating the high-phosphate flotage sludge to a temperature above ambient temperature, and after heating, anaerobically treating the high-phosphate flotage sludge, and then mixing this high-phosphate flotage sludge with an aqueous phase; subjecting the aqueous phase-flotage sludge mixture to a phosphate separation to produce a low-phosphate sludge and a phosphate-enriched liquid; and recycling the low-phosphate sludge into the aerated tank and conducting the phosphate-enriched liquid to a further treatment step.
Claim 3
Dependent Claim
25 words
A process according to claim 1, wherein the aqueous phase mixed with the high phosphate flotage sludge is a partial stream of the incoming wastewater.
Claim 4
Dependent Claim
29 words
A process according to claim 1, wherein phosphate-enriched liquid conducted to a further treatment step is subjected to a phosphate precipitation and is then recycled to the aerated tank.
Claim 5
Dependent Claim
23 words
A process according to claim 3, wherein the heating of the high-phosphate flotage sludge is conducted autothermically by aeration with air or oxygen.
Claim 6
Dependent Claim
20 words
A process according to claim 3, wherein the high-phosphate flotage sludge is heated by means of an external heat supply.
Claim 7
Dependent Claim
18 words
A process according to claim 3, wherein the anaerobic treatment is conducted at a pH of about 4-7.
Claim 8
Dependent Claim
27 words
A process according to claim 1, wherein the high-phosphate flotage sludge is heated to a temperature of about 20°-35° C. before being subjected to the phosphate separation.
Claim 9
Dependent Claim
18 words
A process according to claim 7, wherein the anaerobic treatment is conducted at a pH of about 4-.
Claim 10
Dependent Claim
43 words
A process according to claim 7, wherein the withdrawn low-phosphate flotage is fed, in part, to the wastewater-activated sludge mixture from the aerated tank fed to the post clarification, and in part, is enriched with flotation gas and recycled to the flotation stage.
Claim 11
Dependent Claim
23 words
A process according to claim 1, wherein the heating of the high-phosphate flotage sludge is conducted autothermically by aeration with air or oxygen.
Claim 12
Dependent Claim
43 words
A process according to claim 10, wherein the withdrawn low-phosphate flotage is fed, in part, to the wastewater-activated sludge mixture from the aerated tank fed to the post clarification, and in part, is enriched with flotation gas and recycled to the flotation stage.
Claim 13
Dependent Claim
20 words
A process according to claim 1, wherein the high-phosphate flotage sludge is heated by means of an external heat supply.
Claim 14
Dependent Claim
18 words
A process according to claim 12, wherein the anaerobic treatment is conducted at a pH of about 4-7.
Claim 15
Dependent Claim
43 words
A process according to claim 12, wherein the withdrawn low-phosphate flotage is fed, in part, to the wastewater-activated sludge mixture from the aerated tank fed to the post clarification, and in part, is enriched with flotation gas and recycled to the flotation stage.
Claim 16
Dependent Claim
18 words
A process according to claim 1, wherein the anaerobic treatment is conducted at a pH of about 4-7.
Claim 17
Dependent Claim
43 words
A process according to claim 15, wherein the withdrawn low-phosphate flotage is fed, in part, to the wastewater-activated sludge mixture from the aerated tank fed to the post clarification, and in part, is enriched with flotation gas and recycled to the flotation stage.
Claim 18
Dependent Claim
19 words
A process according to claim 15 wherein said heating is conducted up to a temperature of about 25°-30° C.
Claim 19
Dependent Claim
18 words
A process according to claim 1, wherein the anaerobic treatment is conducted at a pH of about 5.5-6.5.
Claim 20
Dependent Claim
43 words
A process according to claim 18, wherein the withdrawn low-phosphate flotage is fed, in part, to the wastewater-activated sludge mixture from the aerated tank fed to the post clarification, and in part, is enriched with flotation gas and recycled to the flotation stage.
Claim 21
Dependent Claim
43 words
A process according to claim 1, wherein the withdrawn low-phosphate flotage is fed, in part, to the wastewater-activated sludge mixture from the aerated tank fed to the post clarification, and in part, is enriched with flotation gas and recycled to the flotation stage.
Claim 22
Dependent Claim
31 words
A process according to claim 1 wherein only the partial stream of the wastewater-activated sludge mixture treated in the aerated tank and discharged therefrom is fed to the flotation separation stage.
Claim 23
Dependent Claim
44 words
A process according to claim 1 further comprising conducting a partial stream of influent wastewater into said anaerobic treatment to permit phosphate released from microorganisms therein to enter the liquid phase resulting in at least 70% separation of released phosphate from the sludge phase.
Claim 24
Dependent Claim
30 words
A process according to claim 1 wherein said separately withdrawing step further comprises removing the top layer from the flotation separation stage down to a depth of about 200 mm.
Claim 25
Dependent Claim
241 words
In an apparatus for conducting a process of biological purification of phosphate-containing wastewater wherein an aerated tank having an inlet for wastewater is connected by aerated tank discharge means to a post-clarification device downstream therefrom and the post-clarification device has a discharge for separated treated water and sludge recycle means for recycling settled sludge to the aerated tank, the improvement comprising: a flotation separation basin (12) adapted for operation as a sludge thickener and having an inlet connected to at least one of the aerated tank (2), the discharge means (3) of the aerated tank (2), or the sludge recycle means (6) for receiving a partial stream therefrom, and with said flotation separation basin (12) having flotage discharge means (15) for discharging low-phosphate flotage and a flotage sludge discharge conduit (19); a heat treatment zone (20) connected to the flotage sludge discharge conduit (19) for receiving flotage sludge from the flotation separation basin; an anaerobic treatment zone (23) connected downstream of the heat treatment zone (20), and having an inlet for receiving a feed from the heat treatment zone and feed means (24) for feeding influent wastewater thereto; a phosphate separating unit (26) connected to the anaerobic treatment zone (23) for receiving a treated flow therefrom, and the phosphate separating unit (26) comprising a sludge return line (27) to the aerated tank (2) for feeding low-phosphate separated sludge to the aerated tank, and a discharge means (28) for discharging phosphate-enriched liquid.
Claim 26
Dependent Claim
241 words
In an apparatus for conducting a process of biological purification of phosphate-containing wastewater wherein an aerated tank having an inlet for wastewater is connected by aerated tank discharge means to a post-clarification device downstream therefrom and the post-clarification device has a discharge for separated treated water and sludge recycle means for recycling settled sludge to the aerated tank, the improvement comprising: a flotation separation basin (12) adapted for operation as a sludge thickener and having an inlet connected to at least one of the aerated tank (2), the discharge means (3) of the aerated tank (2), or the sludge recycle means (6) for receiving a partial stream therefrom, and with said flotation separation basin (12) having flotage discharge means (15) for discharging low-phosphate flotage and a flotage sludge discharge conduit (19); a heat treatment zone (20) connected to the flotage sludge discharge conduit (19) for receiving flotage sludge from the flotation separation basin; an anaerobic treatment zone (23) connected downstream of the heat treatment zone (20), and having an inlet for receiving a feed from the heat treatment zone and feed means (24) for feeding influent wastewater thereto; a phosphate separating unit (26) connected to the anaerobic treatment zone (23) for receiving a treated flow therefrom, and the phosphate separating unit (26) comprising a sludge return line (27) to the aerated tank (2) for feeding low-phosphate separated sludge to the aerated tank, and a discharge means (28) for discharging phosphate-enriched liquid.
Claim 27
Dependent Claim
20 words
An apparatus according to claim 24, wherein the heat treatment zone (20) comprises an aeration zone for conducting autothermic heating.
Claim 28
Dependent Claim
16 words
An apparatus according to claim 24, wherein the phosphate separating unit (26) is a settling tank.
Claim 29
Dependent Claim
37 words
An apparatus according to claim 26, further comprising a mixing zone connected downstream from the heat treatment zone (20), and before the anaerobic treatment zone (23), with the mixing zone connected to the feed means for wastewater.
Claim 30
Dependent Claim
39 words
An apparatus according to claim 26, wherein the anaerobic treatment zone (23) is a two stage (23a, 23b) zone, and the feed means (24) for wastewater is connected to the second stage (23b) of the anaerobic treatment zone (23).
Claim 31
Dependent Claim
73 words
An apparatus according to claim 26, wherein the flotage discharge means is connected to the aerated tank discharge means (3) for feeding a partial stream thereof to the post-clarification device and is also connected to a saturating unit (14) for flotation gas, which is connected to the flotation separation basin (12) for feeding another partial stream to the saturating unit (14) for being saturated with gas and recycled to the flotation separation basin.
Claim 32
Dependent Claim
47 words
An apparatus according to claim 24, further comprising a device (29) for phosphate precipitation arranged in the discharge means (28) of the phosphate separating unit, and the phosphate precipitation device is also connected to the aerated tank for supplying the liquid treated therein to the aerated tank.
Claim 33
Dependent Claim
37 words
An apparatus according to claim 30, further comprising a mixing zone connected downstream from the heat treatment zone (20), and before the anaerobic treatment zone (23), with the mixing zone connected to the feed means for wastewater.
Claim 34
Dependent Claim
39 words
An apparatus according to claim 30, wherein the anaerobic treatment zone (23) is a two stage (23a, 23b) zone, and the feed means (24) for wastewater is connected to the second stage (23b) of the anaerobic treatment zone (23).
Claim 35
Dependent Claim
73 words
An apparatus according to claim 30, wherein the flotage discharge means is connected to the aerated tank discharge means (3) for feeding a partial stream thereof to the post-clarification device and is also connected to a saturating unit (14) for flotation gas, which is connected to the flotation separation basin (12) for feeding another partial stream to the saturating unit (14) for being saturated with gas and recycled to the flotation separation basin.
Claim 36
Dependent Claim
46 words
An apparatus according to claim 26, further comprising a device (29) for phosphate precipitation arranged in the discharge means (28) of the phosphate separating unit, and the phosphate precipitation device also connected to the aerated tank for supplying the liquid treated therein to the aerated tank.
Claim 37
Dependent Claim
37 words
An apparatus according to claim 24, further comprising a mixing zone connected downstream from the heat treatment zone (20), and before the anaerobic treatment zone (23), with the mizing zone connected to the feed means for wastewater.
Claim 38
Dependent Claim
39 words
An apparatus according to claim 35, wherein the anaerobic treatment zone (23) is a two stage (23a, 23b) zone, and the feed means (24) for wastewater is connected to the second stage (23b) of the anaerobic treatment zone (23).
Claim 39
Dependent Claim
72 words
An apparatus according to claim 35, wherein the flotage discharge means is connected to the aerated tank discharge means (3) for feeding a partial stream thereof to the post-clarification device and is connected to a saturating unit (14) for flotation gas, which is connected to the flotation separation basin (12) for feeding another partial stream to the saturating unit (14) for being saturated with gas and recycled to the flotation separation basin.
Claim 40
Dependent Claim
39 words
An apparatus according to claim 24, wherein the anaerobic treatment zone (23) is a two stage (23a, 23b) zone, and the feed means (24) for wastewater is connected to the second stage (23b) of the anaerobic treatment zone (23).
Claim 41
Dependent Claim
72 words
An apparatus according to claim 38, wherein the flotage discharge means is connected to the aerated tank discharge means (3) for feeding a partial stream thereof to the post-clarification device and is connected to a saturating unit (14) for flotation gas, which is connected to the flotation separation basin (12) for feeding another partial stream to the saturating unit (14) for being saturated with gas and recycled to the flotation separation basin.
Claim 42
Dependent Claim
73 words
An apparatus according to claim 24, wherein the flotage discharge means is connected to the aerated tank discharge means (3) for feeding a partial stream thereof to the post-clarification device and is also connected to a saturating unit (14) for flotation gas, which is connected to the flotation separation basin (12) for feeding another partial stream to the saturating unit (14) for being saturated with gas and recycled to the flotation separation basin.
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) | 1987-07-17 | 1988-01-16 | 1988-07-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-07-17 | 1992-01-16 | 1992-07-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-07-17 | 1996-01-16 | 1996-07-17 | $7700.00 | Window Closed / Lapsed |