# US 4,400,195 A · Method for the anaerobic digestion of solid organic waste

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- Number: US 4,400,195 A
- Document ID: US4400195A
- Status: Granted
- Kind: A
- Application number: 06/347,073
- Filed: 1982-02-08
- Granted: 1983-08-23
- Earliest claimed: 1980-04-03
- Assignees: Instituut voor Bewaring en Verwerking van Landbouwprodukten
- Inventors: Berend A. Rijkens
- Web page: https://patentgrep.com/patent/US4400195A

## CPC

- C12P 5/023: {Methane}
- C05F 17/00: Preparation of fertilisers characterised by biological or biochemical treatment steps, e.g. composting or fermentation
- C05F 17/50: Treatments combining two or more different biological or biochemical treatments, e.g. anaerobic and aerobic treatment or vermicomposting and aerobic treatment
- Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel
- Y02P 20/145: the feedstock being materials of biological origin
- Y02W 30/40: Bio-organic fraction processing; Production of fertilisers from the organic fraction of waste or refuse
- 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)}
- C05F: ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The present invention relates to a method wherein solid organic waste originating from plants or animals or both, is digested by an anaerobic fermentation, that is less labor, time and space consuming than the conventional aerobic fermentation method, and may be performed with waste that has not to be subjected to a pre-treatment wherein a slurry having a rather low solids content is prepared. According to the present method solid organic waste originating from plants or animals or both is decomposed under anaerobic conditions in at least one primary reactor, whereupon the water soluble fatty acids formed by said decomposition together with other soluble organic and inorganic substances are removed to a substantial extent by rinsing with an aqueous liquid in order to avoid that in the reactor the concentration of fermentation inhibiting substances becomes too high and/or the pH of the contents of the reactor becomes too low, and the solution thus formed is fed to at least one auxiliary reactor wherein the organic material is converted into a mixture of carbon dioxide and methane under anaerobic conditions in a way known per se and the sludge formed in the primary reactor is removed therefrom.

## Claims

### Claim 1

A method for the anaerobic digestion of solid organic material originating from plants or animals or both comprising the steps of:
(a) simultaneously composting the solid organic waste under anaerobic conditions in a primary reaction space provided with a strainer while;
(b) rinsing the solid organic waste from step (a) with an aqueous liquid to substantially dissolve and remove soluble organic and inorganic substances and the water soluble fatty acids formed by the decomposition;
(c) feeding the aqueous liquid obtained in step (b) substantially free from undissolved solid organic waste from the primary reaction space into an auxiliary reactor;
(d) leaving the remaining compost behind in the primary reaction space;
(e) under anaerobic conditions in the auxiliary reactor, converting the dissolved organic material in the aqueous solution into a mixture of carbon dioxide and methane gas; and
(f) removing the remaining compost from the primary reaction space.

### Claim 2 (depends on 1)

The method described in claim 1 wherein the primary reaaction space is fully sealed.

### Claim 3 (depends on 2)

The method described in claim 2 wherein more than one primary reaction space is used.

### Claim 4 (depends on 3)

The method described in claim 3 wherein the waste is delivered intermittently into the primary reaction space.

### Claim 5 (depends on 1, 2, 3, 4)

The method described in claim 1, 2, 3 or 4 wherein the effluent from the auxiliary reactor is used in rinsing the decomposing solid organic waste in step (b).

### Claim 6 (depends on 1)

The method as described in claim 1 wherein step (b) is discontinued from the time the methane generation in the primary reaction space occurs at a steady self-supporting rate.