US3670887A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Aerobic digestion of sludge with oxygen
Assignee: Union Carbide Corp
•
Filing: 1970-12-14
•
Granted: 1972-06-20
•
Expires: 1990-12-14
Abstract
Abstract BOD-containing water such as sewage is aerated with oxygen and unrecycled sludge is digested with unconsumed oxygen from the aeration.
Inventors
- 👤 John Ruben Mcwhirter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:20
CPC Classifications
C; C02; C02F; C02F3/00; C02F3/02; C02F3/12; C02F3/26; Y; Y02; Y02W; Y02W10/00; Y02W10/10
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
114 words
A method according to claim 1 wherein said aeration zone comprises a preliminary section and a final section, mixed liquor and preliminary unconsumed oxygen-containing gas are discharged from said preliminary section after preliminary mixing and recirculation of one fluid against the other fluids, said mixed liquor is separated into supernatent liquid and preliminary sludge, said preliminary unconsumed oxygen-containing gas and said preliminary sludge are introduced to said final section of the aeration zone for further mixing and recirculation of one fluid against the other fluids, further unconsumed oxygen-containing gas is discharged from said final section as at least part of said second gas, and said activated sludge is also discharged from said final section.
Claim 2
Dependent Claim
27 words
A method according to claim 1 wherein the volatile suspended solids content (VSS) of said waste sludge residue is less than about 0.7 of said activated sludge.
Claim 3
Dependent Claim
41 words
A method according to claim 1 wherein said aeration zone and said digestion zone each comprises at least two stages wherein unconsumed oxygen-containing gas is discharged from the first stage and introduced to the second stage as the aeration gas therefor.
Claim 4
Dependent Claim
75 words
A method according to claim 1 wherein said aeration zone and said digestion zone each comprises at least two stages wherein unconsumed oxygen-containing gas is discharged from the first stage and introduced to the second stage as the aeration gas, oxygenated liquor is discharged from the first stage and introduced to the second stage in cocurrent flow relation with said unconsumed oxygen-containing gas for mixing therewith and recirculation of one fluid against the other fluids.
Claim 5
Dependent Claim
46 words
A method according to claim 2 wherein the liquid-solid contact time of the aeration zone preliminary section is less than about 0.5 of the aeration zone final section such that said preliminary sludge contains unassimilated BOD and said activated sludge is substantially devoid of unassimilated BOD.
Claim 6
Dependent Claim
173 words
A method according to claim 1 wherein two digestion zones are provided, said second gas is simultaneously introduced to a first zone and a second zone, said unreturned activated sludge is introduced to said first zone for charging thereof and the second gas is simultaneously continuously mixed with previously charged activated sludge in said second zone with one fluid recirculated against the other fluids in said second zone as its digestion step; waste sludge residue and third gas are discharged from said second zone after its digestion step; said unreturned activated sludge is thereafter introduced to the emptied second zone for charging thereof and the second gas is simultaneously continuously mixed with the previously charged activated sludge in said first zone with one fluid recirculated against the other fluids in said first zone as its digestion step; waste sludge residue and third gas Are discharged from said first zone after its digestion step; the emptied first zone and charged second zone are thereafter respectively returned to the activated sludge charging and digestion steps.
Claim 7
Dependent Claim
22 words
A method according to claim 1 wherein said second gas has oxygen concentration at least 0.80 times the first gas oxygen concentration.
Claim 8
Dependent Claim
31 words
A method according to claim 1 wherein water is removed from at least part of said waste sludge residue and the dewatered waste sludge residue is returned to said digestion zone.
Claim 9
Dependent Claim
47 words
A method according to claim 1 wherein said first gas comprises at least 90 percent oxygen (by volume), said second gas comprises at least 80 percent oxygen, and at least 70 percent of the oxygen in said first gas is consumed in said aeration and digestion zones.
Claim 10
Dependent Claim
26 words
A method according to claim 1 wherein additional gas comprising at least 60 percent oxygen (by volume) is externally supplied as part of said second gas.
References Cited (Backward Citations)
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US3054602A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-06-20 | 1975-12-20 | 1976-06-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-06-20 | 1979-12-20 | 1980-06-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-06-20 | 1983-12-20 | 1984-06-20 | $7700.00 | Window Closed / Lapsed |