# US 2014/0154767 A1 · Anaerobic digestion with supercritical water hydrolysis as pretreatment

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- Number: US 2014/0154767 A1
- Document ID: US20140154767A1
- Status: Published application
- Kind: A1
- Application number: 14/131,107
- Filed: 2012-07-02
- Published: 2014-06-05
- Earliest claimed: 2011-07-06
- Assignees: Hollingford Limited
- Inventors: John O'Regan
- Web page: https://patentgrep.com/patent/US20140154767A1

## CPC

- C12P 5/023: {Methane}
- C02F 11/04: Anaerobic treatment; Production of methane by such processes
- C02F 11/086: {in the supercritical state}
- C02F 2209/02: Temperature
- C02F 2209/03: Pressure
- C02F 2209/06: pH
- C02F 2209/44: Time
- C02F 2301/08: Multistage treatments, e.g. repetition of the same process step under different conditions
- C02F 2301/10: Temperature conditions for biological treatment
- C02F 2303/06: Sludge reduction, e.g. by lysis
- C02F 2303/10: Energy recovery
- Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel
- Y02W 10/30: Wastewater or sewage treatment systems using renewable energies
- C12P: FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE {(brewing of beer C12C; producing vinegar C12J; producing specific peptides or proteins C07K; producing enzymes C12N9/00; DNA or RNA concerning genetic engineering, vectors, e.g. plasmids, or their isolation, preparation or purification C12N15/00; measuring or testing processes involving enzymes or microorganisms C12Q; measuring or testing processes involving nucleic acid amplification reactions C12Q1/6844; fermentation processes to form a food composition, A21 or A23; compounds in general, see the relevant compound class, e.g. C01, C07)}
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

An hydrolysis stage of an anaerobic digestion (AD) process includes supercritical treatment in a reactor (R1). The treatment may use sub-stoichiometric oxygen so that there is not full oxidation. Effluent from the supercritical treatment may be used to pre-heat the organic matter in-feed to the supercritical treatment. There may be a second supercritical treatment in a second reactor (R2). This may have full stoichiometric oxygen, to oxidise the solids from the first reactor (R1) effluent. Furthermore, it provides heat for pre-heating its own in-feed and also that for the first reactor (R1). The output from the hydrolysis may be only clarified liquid, leading to particularly efficient downstream AD processes. The second supercritical treatment rector may oxidise also fed-back solids from the final stage of the AD.

## Claims

### Claim at position 1

1-39. (canceled)

### Claim 40

A process for anaerobic digestion of organic matter such as waste, the process comprising hydrolysis, acidogenesis, and methanogenesis, wherein the hydrolysis step includes supercritical treatment of the organic matter in a reactor by elevation of the organic matter to a temperature of at least 374° C. and a pressure of at least 221 bar for a supercritical residence time.

### Claim 41 (depends on 40)

The process as claimed in claim 40, wherein the residence time is in the range of 60 s to 180 s.

### Claim 42 (depends on 40)

The process as claimed in claim 40, wherein the supercritical treatment is performed in a reactor comprising a bulk reactor section followed by a plug flow reactor section; and wherein the organic matter is of the type having a moisture content greater than 70%.

### Claim 43 (depends on 40)

The process as claimed in claim 40, wherein the organic matter comprises cellulose and lignins; and the organic matter has a pH value in the range of 3.5 to 8.0, preferably 4.5 to 7.5.

### Claim 44 (depends on 40)

The process as claimed in claim 40, wherein oxidant is introduced for the supercritical treatment at a sub-stoichiometric level; and wherein said sub-stoichiometric level is below 40%.

### Claim 45 (depends on 40)

The process as claimed in claim 40, wherein the treatment pressure is in the range of 221 bar to 300 bar; and wherein the organic matter comprises cellulose and lignins; and wherein the supercritical reactor temperature is in the range of 374° C. to 400° C.

### Claim 46 (depends on 40)

The process as claimed in claim 40, wherein the organic matter is pre-heated before the supercritical treatment.

### Claim 47 (depends on 40)

The process as claimed in claim 40, wherein the organic matter is pre-heated before the supercritical treatment; and wherein the pre-heating raises the temperature to above 200° C.; and wherein said pre-treatment uses heat from effluent of the supercritical reactor.

### Claim 48 (depends on 40)

The process as claimed in claim 40, wherein the organic matter is pre-heated before the supercritical treatment; and wherein said pre-treatment uses heat from effluent of the supercritical reactor; and wherein the effluent is directed through an annulus of a heat exchanger, and the inlet organic matter is fed through tubes of said heat exchanger.

### Claim 49 (depends on 40)

The process as claimed in claim 40, wherein the organic matter is re-circulated in a vessel before being pumped to the supercritical reactor.

### Claim 50 (depends on 40)

The process as claimed in claim 40, wherein effluent from the supercritical treatment is delivered to a venting vessel from which gases are vented; and wherein effluent of the supercritical treatment is treated in a second supercritical reactor.

### Claim 51 (depends on 40)

The process as claimed in claim 40, wherein effluent of the supercritical treatment is treated in a second supercritical reactor; and wherein the effluent is processed by a gas-venting vessel and a cyclone separator before the second supercritical treatment.

### Claim 52 (depends on 40)

The process as claimed in claim 40, wherein effluent of the supercritical treatment is treated in a second supercritical reactor; and wherein the effluent is processed by a gas-venting vessel and a cyclone separator before the second supercritical treatment; and wherein the effluent is further processed by addition of process water to provide a solids proportion in the range of about 10% to 14%, preferably about 12%.

### Claim 53 (depends on 40)

The process as claimed in claim 40, wherein effluent of the supercritical treatment is treated in a second supercritical reactor; and wherein the second supercritical treatment is performed in a reactor with full stoichiometric oxygen, so that the second supercritical treatment effluent comprises substantially water and inert solids.

### Claim 54 (depends on 40)

The process as claimed in claim 40, wherein effluent of the supercritical treatment is treated in a second supercritical reactor; and wherein the effluent from the second supercritical treatment is used to pre-heat the in-feed to said second supercritical treatment.

### Claim 55 (depends on 40)

The process as claimed in claim 40, wherein the effluent from the second supercritical treatment is used to pre-heat the in-feed to the first supercritical treatment reactor, and the effluent from the first supercritical treatment reactor is used to pre-heat the in-feed to the second supercritical treatment reactor; and wherein the hydrolysis provides only clarified liquid to the acidogenesis stage; and wherein solids from the acidogenesis or methanogenesis stages are fed back to said hydrolysis stage; and wherein said solids are fed back to the second supercritical reactor.

### Claim 56

An anaerobic digester hydrolysis apparatus comprising a supercritical treatment reactor arranged for supercritical treatment of organic matter by elevation of the organic matter to a temperature of at least 374° C. and a pressure of at least 221 bar for a supercritical residence time.

### Claim 57 (depends on 56)

The apparatus as claimed in claim 56, wherein the supercritical treatment reactor comprises a bulk reactor followed by a plug flow reactor.

### Claim 58 (depends on 56)

The apparatus as claimed in claim 56, further comprising a heater arranged to pre-heat organic matter before entry to the supercritical treatment reactor; and wherein said heater is a heat exchanger arranged to use heat from effluent of the supercritical treatment reactor.

### Claim 59 (depends on 56)

The apparatus as claimed in claim 56, further comprising a pump and a vessel for re-circulating organic matter before being pumped to the supercritical treatment reactor; and further comprising a venting vessel arranged to receive effluent from the supercritical treatment reactor and to vent gases from said effluent.

### Claim 60 (depends on 56)

The apparatus as claimed in claim 56, further comprising a second supercritical treatment reactor arranged to apply supercritical treatment to effluent of the first supercritical reactor.

### Claim 61 (depends on 56)

The apparatus as claimed in claim 56, further comprising a second supercritical treatment reactor arranged to apply supercritical treatment to effluent of the first supercritical reactor; and further comprising a gas-venting vessel and a cyclone separator arranged to process said effluent before the second supercritical treatment reactor; and wherein the second supercritical treatment reactor is adapted to apply full stoichiometric oxygen, so that the second supercritical treatment effluent comprises substantially water and inert solids; and further comprising a heat exchanger arranged to pre-heat in-feed to said second supercritical treatment reactor using effluent from the second supercritical treatment reactor; and wherein a heat exchanger is arranged to pre-heat in-feed to the first supercritical treatment reactor using effluent from the second supercritical treatment reactor.

### Claim 62 (depends on 56)

The apparatus as claimed in claim 56, wherein the apparatus comprises a separator arranged to supply only clarified liquid to an acidogenesis apparatus; and an inlet to receive solids from downstream anaerobic digestion process and a conduit to deliver them to said second supercritical treatment reactor.