# US 2017/0283833 A1 · Multiple tank high solids anaerobic digester

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- Number: US 2017/0283833 A1
- Document ID: US20170283833A1
- Status: Published application
- Kind: A1
- Application number: 15/628,189
- Filed: 2017-06-20
- Published: 2017-10-05
- Earliest claimed: 2011-10-19
- Assignees: Anaergia Inc.
- Applicants: Anaergia Inc.
- Inventors: Juan Carlos Josse; Christian Friedl; Martin Bayer
- Web page: https://patentgrep.com/patent/US20170283833A1

## CPC

- C12P 5/023: {Methane}
- C02F 3/286: {including two or more steps}
- C02F 3/2866: {Particular arrangements for anaerobic reactors}
- C02F 11/04: Anaerobic treatment; Production of methane by such processes
- C12M 21/04: {for producing gas, e.g. biogas (digesters for manure with production of biogas A01C3/028, biological treatment of water, waste water or sewage C02F3/00, C02F11/02, preparation of natural gas or syngas C10L3/06, C10L3/10)}
- C12M 23/34: {Internal compartments or partitions}
- C12M 23/58: {Reaction vessels connected in series or in parallel (combinations of bioreactors with other apparatus, C12M43/00)}
- C12M 29/02: {Percolation}
- C12M 29/18: {External loop; Means for reintroduction of fermented biomass or liquid percolate (loop type reactors for chemical or physical processes B01J19/2435)}
- C12P 1/00: Preparation of compounds or compositions, not provided for in groups C12P3/00 - C12P39/00, by using microorganisms or enzymes
- C02F 2209/005: Processes using a programmable logic controller [PLC]
- C02F 2209/42: Liquid level
- C02F 2209/44: Time
- C02F 2301/02: Fluid flow conditions
- C02F 2303/10: Energy recovery
- Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel
- Y02W 10/20: Sludge processing
- 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)
- C12M: APPARATUS FOR ENZYMOLOGY OR MICROBIOLOGY; {APPARATUS FOR CULTURING MICROORGANISMS FOR PRODUCING BIOMASS, FOR GROWING CELLS OR FOR OBTAINING FERMENTATION OR METABOLIC PRODUCTS, i.e. BIOREACTORS OR FERMENTERS}
- 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

A multi-stage anaerobic digester is designed to treat a high solids, stackable feedstock. The system may also receive a pumpable feedstock such as a slurry or sludge. In a first stage, the digestate circulates in one direction around a raceway such that the digestate may pass a feed inlet multiple times before leaving the first tank. An optional side stream loop withdraws fibrous material from near the top of the raceway and return digestate with chopped fibers, preferably lower and further along the raceway. An outlet from the raceway located near, but upstream of, the feed inlet discharges partially digested substrate to a second stage, which is operated as a stirred tank reactor. The two stages may be provided in a single tank with an internal wall separating a ring shaped outer portion from a cylindrical inner portion. The digester may be operated in a thermophilic temperature range.

## Claims

### Claim 1

An anaerobic digester comprising,
a) a covered cylindrical tank;
b) in interior wall dividing the cylindrical tank into a ring shaped outer portion and a cylindrical inner portion; and,
c) a passageway between the outer portion and the inner portion.

### Claim 2 (depends on 1)

The digester or claim 1 further comprising a set of mixers spaced around the ring shaped outer portion and oriented to direct digestate in one direction around the ring shaped outer portion.

### Claim 3 (depends on 2)

The digester of claim 2 further comprising an inlet for adding a substrate to the ring shaped outer portion, wherein the inlet is located downstream of the passageway by an angular displacement of 60 degrees or less from the passageway.

### Claim 4 (depends on 3)

The digester of claim 3 wherein a first of the set of mixers located closest to the inlet in the one direction has a mixing blade that is located higher than the mixing blades of other mixers in the set of mixers.

### Claim 5 (depends on 4)

The digester of claim 4 wherein the height of the mixing blades decreases from the height of the mixing blades of the first mixer along the one direction.

### Claim 6 (depends on 1)

The digester of claim 1 further comprising a side stream in which digestate is withdrawn from a location within one meter of the free surface of the digestate in the ring shaped outer portion and the withdrawn digestate is returned to the ring shaped outer portion at a lower elevation than the withdrawal location.

### Claim 7 (depends on 6)

The digester of claim 6 wherein the withdrawn digestate is returned to the ring shaped outer portion at a position displaced in the one direction away from the withdrawal location.

### Claim 8 (depends on 6)

The digester of claim 6 wherein the side stream comprises a chopper pump.

### Claim 9 (depends on 6)

The digester of claim 6 wherein an inlet to the side stream comprises a crust breaker.

### Claim 10 (depends on 1)

The digester of claim 1 wherein the ring shaped outer portion has at least 40% of the volume of the digester.

### Claim 11 (depends on 1)

The digester of claim 1 wherein the inlet is adapted to introduce a stackable substrate into the ring shaped outer portion and further comprising a second inlet adapted to introduce a pumpable substrate into the ring shaped outer portion.

### Claim 12 (depends on 1)

The digester of claim 1 wherein the passageway comprises a riser such that digestate flows upwards while moving from the outer ring shaped portion to the cylindrical inner portion.