Patent EP0377320A2 successfully refreshed from Google Patents.
US4297216A
Expired / Lapsed
US
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Method for treatment of biochemical waste
Assignee: Hitachi Ltd
•
Filing: 1978-01-05
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Granted: 1981-10-27
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Expires: 1998-01-05
Abstract
Abstract Method for treatment of biochemical waste which comprises adding acid to the biochemical waste to adjust pH (power of hydrogen ion) thereof, heating the adjusted biochemical waste, adding alkali thereto to neutralize the waste, and treating with anaerobic digestion.
Inventors
- 👤 Masahiko Ishida
- 👤 Ryooichi Haga
- 👤 Youji Odawara
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:42
CPC Classifications
C; C02; C02F; C02F3/00; C02F3/28; C02F3/286; C02F1/00; C02F1/02; Y; Y02; Y02E; Y02E50/00; Y02E50/30; Y02W; Y02W30/00; Y02W30/40
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
154 words
A method for the treatment of a biochemical waste slurry, with the biochemical waste selected from the group of sewage sludge and garbage, comprising the steps of: providing a slurry of the biochemical waste with a solid density greater than 3% by weight; adding acid to the slurry to adjust its pH to a value below 3.5; heating the slurry having its pH below 3.5 within a temperature range of 60° to 200° C. for a period of 1 to 10 minutes to reduce the viscosity of the slurry; thereafter substantially neutralizing the acidity of the slurry to a pH of 5 to 8; anaerobically digesting the substantially neutralized slurry at a temperature within the range of 20° to 50° C. for 20 to 40 days with mechanical agitation through the action of methane producing bacteria to convert the slurry to methane and a digested sludge; and separating the methane from the digested sludge.
Claim 2
Independent Claim
154 words
A method for the treatment of a biochemical waste slurry, with the biochemical waste selected from the group of sewage sludge and garbage, comprising the steps of: providing a slurry of the biochemical waste with a solid density greater than 3% by weight; adding acid to the slurry to adjust its pH to a value below 3.5; heating the slurry having its pH below 3.5 within a temperature range of 60° to 200° C. for a period of 1 to 10 minutes to reduce the viscosity of the slurry; thereafter substantially neutralizing the acidity of the slurry to a pH of 5 to 8; anaerobically digesting the substantially neutralized slurry at a temperature within the range of 20° to 50° C. for 20 to 40 days with mechanical agitation through the action of methane producing bacteria to convert the slurry to methane and a digested sludge; and separating the methane from the digested sludge.
Claim 3
Dependent Claim
58 words
The method of claim 1, further including the step of partially neutralizing the acidity of said slurry to a pH between 3.5 and 5 while simultaneously mechanically agitating said slurry at a temperature substantially below 60° C. for a period of time sufficient to substantially reduce the viscosity of said slurry between said steps of heating and neutralizing.
Claim 4
Dependent Claim
22 words
The method of claim 1, wherein said slurry is provided with a solid density greater than 5% of said step of providing.
Claim 5
Dependent Claim
27 words
The method of claim 3, wherein said step of adding acid adjusts the pH of the slurry to a value within a range of 1 to 3.
Claim 6
Independent Claim
128 words
A method for the treatment of a slurry of biochemical waste, selected from the group of sewage sludge and garbage, comprising the steps of: adding acid to the slurry to adjust its pH to a value below 3.5; heating the slurry having its pH below 3.5 for a period of 1 to 10 minutes within a temperature range of 60° to 200° C.; thereafter substantially neutralizing the acidity of the slurry to a pH of 5 to 8; anaerobically digesting the substantially neutralized slurry at a temperature within the range of 20° to 50° C. for 20 to 40 days with mechanical agitation through the action of methane producing bacteria to convert the slurry to methane and a digested sludge; and separating the methane from the digested sludge.
Claim 7
Independent Claim
128 words
A method for the treatment of a slurry of biochemical waste, selected from the group of sewage sludge and garbage, comprising the steps of: adding acid to the slurry to adjust its pH to a value below 3.5; heating the slurry having its pH below 3.5 for a period of 1 to 10 minutes within a temperature range of 60° to 200° C.; thereafter substantially neutralizing the acidity of the slurry to a pH of 5 to 8; anaerobically digesting the substantially neutralized slurry at a temperature within the range of 20° to 50° C. for 20 to 40 days with mechanical agitation through the action of methane producing bacteria to convert the slurry to methane and a digested sludge; and separating the methane from the digested sludge.
Claim 8
Dependent Claim
58 words
The method of claim 5, further including the step of partially neutralizing the acidity of said slurry to a pH between 3.5 and 5 while simultaneously mechanically agitating said slurry at a temperature substantially below 60° C. for a period of time sufficient to substantially reduce the viscosity of said slurry, between said steps of heating and neutralizing.
Claim 9
Dependent Claim
27 words
The method of claim 5, wherein the step of adding acid adjusts the pH of the slurry to a value within a range of 1 to 3.
Claim 10
Dependent Claim
24 words
The method of claim 5, further including heating the slurry having its pH below 3.5 within a temperature range of 60° to 160° C.
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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) | 1984-10-26 | 1985-04-27 | 1985-10-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-10-26 | 1989-04-27 | 1989-10-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-10-26 | 1993-04-27 | 1993-10-27 | $7700.00 | Window Closed / Lapsed |