# US 2008/0185336 A1 · Process for solid-state methane fermentation of biomass materials and fermentation apparatus system therefor

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- Number: US 2008/0185336 A1
- Document ID: US20080185336A1
- Status: Published application
- Kind: A1
- Application number: 12/007,957
- Filed: 2008-01-17
- Published: 2008-08-07
- Earliest claimed: 2007-02-05
- Inventors: Takaaki Maekawa; Takeshi Paul Owa
- Web page: https://patentgrep.com/patent/US20080185336A1

## CPC

- C02F 11/02: Biological treatment
- B09B 3/32: Compressing or compacting
- B09B 3/35: Shredding, crushing or cutting
- B09B 3/60: Biochemical treatment, e.g. by using enzymes
- B09B 3/65: Anaerobic treatment
- 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 21/16: {Solid state fermenters, e.g. for koji production}
- C12M 23/58: {Reaction vessels connected in series or in parallel (combinations of bioreactors with other apparatus, C12M43/00)}
- C12M 29/18: {External loop; Means for reintroduction of fermented biomass or liquid percolate (loop type reactors for chemical or physical processes B01J19/2435)}
- C12M 45/04: {Phase separators; Separation of non fermentable material; Fractionation}
- C02F 11/04: Anaerobic treatment; Production of methane by such processes
- Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel
- Y02W 10/20: Sludge processing
- 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)
- B09B: DISPOSAL OF SOLID WASTE NOT OTHERWISE PROVIDED FOR
- 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 process for producing a biogas by solid-state fermentation of a solid biomass material which comprises the steps of: (1) pelletizing the biomass material into pellets; (2) introducing the pellets into an acid fermentation zone; (3) subjecting the biomass material in the pellets to solid-state acid fermentation under facultative anaerobic conditions or under semi-aerobic conditions kept in an oxygen concentration of 0.01% to 5.0%; (4) densifying the pellets by compression to remove the oxygen from among the particles of the biomass material; (5) transferring the densified pellets into a methane fermentation zone; and (6) subjecting the biomass material in the densified pellets to methane fermentation in the methane fermentation zone under anaerobic conditions, and an apparatus system for producing a biogas by solid-state fermentation of a solid biomass material which comprises: an acid fermentation tank (7) having a means for pelletization (4) of the solid biomass material and an air inlet (25) with a movable valve; and a methane fermentation tank (11) having a pellet compressing means (12) connected to the acid fermentation tank (11) through a movable valve (9) for separation.

## Claims

### Claim 1

A process for producing a biogas by solid-state fermentation of a solid biomass material which comprises the steps of:
(1) pelletizing the biomass material into pellets;
(2) introducing the pellets into an acid fermentation zone;
(3) subjecting the biomass material in the pellets to solid-state acid fermentation under facultative anaerobic conditions or under semi-aerobic conditions kept in an oxygen concentration of 0.01% to 5.0%;
(4) densifying the pellets by compression to remove the oxygen from among the particles of the biomass material;
(5) transferring the densified pellets into a methane fermentation zone; and
(6) subjecting the biomass material in the densified pellets to methane fermentation in the methane fermentation zone under anaerobic conditions.

### Claim 2 (depends on 1)

The process for producing a biogas according to claim 1 wherein the biomass material pelletized in step (1) has a particle size not exceeding 100 mm.

### Claim 3 (depends on 1)

The process for producing a biogas according to claim 1 wherein the pelletization of the biomass material in step (1) is conducted by extrusion of the biomass material through a die.

### Claim 4 (depends on 3)

The process for producing a biogas according to claim 3 wherein the extrusion of the biomass material is carried out through a die having a diameter of 7 to 100 mm under a pressure of at least 0.5 MPa.

### Claim 5 (depends on 1)

The process for producing a biogas according to claim 1 wherein the biomass material for pelletization in step (1) is blended beforehand with calcium hydroxide or calcium oxide in an amount of 0.001% to 5% by mass based on the mass of the biomass material.

### Claim 6 (depends on 1)

The process for producing a biogas according to claim 1 wherein the densified pellets of the size-adjusted biomass material in step (6) have a water content of 80% to 85% by mass on the wet basis.

### Claim 7 (depends on 1)

The process for producing a biogas according to claim 1 wherein the methane fermentation in step (6) is followed by recovery of the fermentation residue which is dried for use as a solid fuel.

### Claim 8 (depends on 7)

The process for producing a biogas according to claim 7 wherein the solid fuel is heated with superheated steam followed by heating at 800° C. or higher to produce a thermal decomposition gas.

### Claim 9

An apparatus system for producing a biogas by solid-state fermentation of a solid biomass material which comprises: an acid fermentation tank having a means for pelletization of the solid biomass material and an air inlet with a movable valve; and a methane fermentation tank having a pellet compressing means connected to the acid fermentation tank through a movable valve for separation.

### Claim 10 (depends on 9)

The apparatus system according to claim 9, wherein the acid fermentation tank is provided with a feeding pit for the biomass material connected to a conveyer, an extruder having a die shaped at the tip thereof, and an upwardly slanted bottom surface connected to the extruder through the die; the methane fermentation tank being connected to the acid fermentation tank through a movable valve which is opened or closed by an angle-controlling actuator, the methane fermentation tank being provided on the upper surface thereof with a press-compacting head and a bottom surface shaped to be aslant downwardly in direction of a slurry reservoir; and a recirculation mechanism for returning a slurry collected in the slurry reservoir to the methane fermentation tank.

### Claim 11 (depends on 9)

The apparatus system according to claim 9, wherein a metal-removing mechanism is further provided for a preliminary treatment of the biomass material.

### Claim 12 (depends on 9)

The apparatus system according to claim 9, wherein the methane fermentation tank is provided at a discharge port of the fermentation residue with a drying oven.