# US 8,772,020 B2 · Fermentation system having strainer assembly

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- Number: US 8,772,020 B2
- Document ID: US8772020B2
- Status: Granted
- Kind: B2
- Application number: 12/375,396
- Filed: 2007-08-01
- Published: 2010-01-21
- Granted: 2014-07-08
- Earliest claimed: 2006-08-01
- Assignees: The Regents of the University of California
- Applicants: Dave Konwinski; Ruihong Zhang
- Inventors: Dave Konwinski; Ruihong Zhang
- Web page: https://patentgrep.com/patent/US8772020B2

## CPC

- 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 33/16: {Screw conveyor}
- C12M 45/04: {Phase separators; Separation of non fermentable material; Fractionation}
- C12M 45/06: {by chemical means or hydrolysis}
- Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel
- 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

## Abstract

A fermentation system for production of biogas from solid organic material, the system including at least one fermentation reactor. The fermentation reactor includes a vessel (37) for housing a feed mixture having liquid and solid particles and an outlet port (44), a strainer assembly (33) at the outlet port for filtering processed feed mixture from the vessel, and a biogasification reactor (37) in fluid communication with another fermentation reactor, the other fermentation reactor configured to produce a biomethane. The strainer assembly further includes a mixture driving member (53) positioned in the strainer body (47) adjacent the drain opening (51), the mixture driving member having a driving surface configured to receive the liquid passing through the filter member (60). The driving surface engages the filter member such that solid particles are driven from a surface of the filter member when the driving member is activated. A method of continuously producing a biogas and servicing a strainer assembly for a hydrolysis reactor are disclosed.

## Claims

### Claim 1

A fermentation system for production of biogas from solid organic material, said system comprising:
a first fermentation reactor configured to produce a first biogas including:
a vessel for housing a feed mixture having liquid and solid particles, the vessel containing an outlet port;
a strainer assembly at the outlet port for filtering processed feed mixture from the vessel, the strainer assembly including:
a strainer body having an inlet end fluidly connected to the vessel, service end, and drain opening intermediate the inlet end and service end;
a mixture driving member positioned in the strainer body adjacent the drain opening, the mixture driving member having a driving surface configured to drive solid particles in the strainer body towards the inlet end and an upstream end configured to extend beyond the inlet end into the vessel;
a filter member positioned in the drain opening configured to allow liquid effluent to pass therethrough and retain desired solid particles in the strainer body; and
a drain pipe configured to receive the liquid passing through the filter member; and
a second fermentation reactor in fluid communication with the first reactor, the second reactor configured to produce a second biogas,
wherein the driving surface engages the filter member such that solid particles are driven from a surface of the filter member when the driving member is activated.

### Claim 2 (depends on 1)

The system according to claim 1, wherein the fermentation system is an anaerobic phased digester system, wherein the first fermentation reactor is a hydrolysis reactor and the second fermentation reactor is a biogasification reactor, the system further including:
a buffer tank intermediate the hydrolysis reactor and the biogasification reactor, wherein the buffer tank is configured to equilibrate flow from the hydrolysis reactor.

### Claim 3 (depends on 2)

The system according to claim 2, wherein strainer assembly is configured to regulate the flow of suspended solids introduced to the biogasification reactor.

### Claim 4 (depends on 1)

The system according to claim 1, wherein the mixture driving member is an auger and the driving surface is at least one thread, the at least one thread extending from a central axis of the auger to a point adjacent an inner surface of the strainer body.

### Claim 5 (depends on 4)

The system according to claim 4, wherein the filter member surface is substantially flush with an inner surface of the strainer body.

### Claim 6 (depends on 5)

The system according to claim 5, wherein the at least one thread engages the inner surface of the strainer body and filter member surface such that particles are driven from the surfaces.

### Claim 7 (depends on 6)

The system according to claim 6, wherein an outer edge of the at least one thread is configured to clean the inner surface of the strainer body and filter member surface.

### Claim 8 (depends on 5)

The system according to claim 5, wherein the strainer body is substantially cylindrical and coaxial with the auger, a diameter of the auger is substantially equal to an inner diameter of the strainer body.

### Claim 9 (depends on 8)

The system according to claim 8, wherein the drain opening is a plurality of openings along a periphery of the strainer body and adjacent the service end and the filter member surface is a cylindrical screen substantially flush with an inner surface of the plurality of drain openings.

### Claim 10 (depends on 1)

The system according to claim 1, wherein the filter is configured to retain particles above a predefined threshold within the strainer body.

### Claim 11 (depends on 10)

The system according to claim 10, wherein the predefined threshold is based on dimensions of the solid particles.

### Claim 12 (depends on 1)

The system according to claim 1, further including a removable end plate assembly at the service end of the strainer assembly configured to seal the service end, the end plate assembly including:
an end plate;
a motor mount on the end plate configured to mount a rotating shaft of the mixture driving member; and
a motor for driving the mixture driving member,
wherein the mixture driving member may be removed through the service end of the strainer assembly when the end plate assembly is removed.

### Claim 13 (depends on 1)

The system according to claim 1, wherein the mixture driving member is activated when predetermined conditions are met.

### Claim 14 (depends on 1)

The system according to claim 1, wherein the mixture driving member is monolithically formed.

### Claim 15 (depends on 1)

The system according to claim 1, wherein the mixture driving member includes a plurality of driving surfaces.

### Claim 16 (depends on 1)

The system according to claim 1, wherein strainer assembly is configured to provide hydraulic mixing when the mixture driving member is activated in reversed.

### Claim 17 (depends on 1)

The strainer assembly according to claim 1, wherein the filter member is a screen having a plurality of apertures, the apertures being smaller than a diameter of the smallest solid particles to be retained in the vessel.

### Claim 18 (depends on 1)

The strainer assembly according to claim 1, further including a shut-off valve adjacent the inlet end of the strainer body configured to stop a flow of mixture into the strainer body.

### Claim 19 (depends on 1)

A method of continuously producing biogas using the fermentation system according to claim 1, the method comprising the steps of:
providing the feed mixture;
feeding the feed mixture to the first fermentation reactor configured to produce the biogas from the feed mixture;
reacting the feed mixture in a hydrolysis reactor;
transferring reacted feed mixture composed of liquid and liquid-suspended particles from the hydrolysis reactor to the strainer assembly configured to strain liquid from the reacted mixture;
driving the mixture driving member when predetermined conditions are met;
receiving the liquid passing through the strainer assembly into the drain pipe; and
collecting biogas from the first fermentation reactor.

### Claim 20 (depends on 19)

The method according to claim 19, further including the steps of:
providing a plurality of supplementary fermentation reactors,
wherein the collected liquid is fed to one of the second fermentation reactor or supplementary fermentation reactors.

### Claim 21 (depends on 20)

The method according to claim 20, wherein the first fermentation reactor and supplementary fermentation reactors are hydrolysis reactors, further including the steps of:
providing a biogasification reactor for producing a biogas comprising methane;
feeding the collected liquid from the drain pipe to one of the hydrolysis reactor, supplementary hydrolysis reactors, or biogasification reactor; and
collecting biogas from at least one of the hydrolysis reactor, supplementary hydrolysis reactors, or biogasification reactor.

### Claim 22 (depends on 21)

The method according to claim 21, wherein the mixture driving member is an auger and the driving surface is at least one thread, the at least one thread extending from a central axis of the auger to a point adjacent an inner surface of the strainer body, further wherein the at least one thread engages a surface of the filter member such that particles are driven from the surface of the filter.

### Claim 23 (depends on 22)

The method according to claim 22, wherein the strainer body is substantially cylindrical and coaxial with the mixture driving member, the mixture driving member and an inner surface of the strainer body being substantially equal in diameter.

### Claim 24 (depends on 23)

The method according to claim 23, wherein the drain opening is a plurality of openings along a periphery of the strainer body and the filter member is a cylindrical screen.

### Claim 25 (depends on 22)

The method according to claim 22, further including the steps of:
providing a removable end cap assembly configured to seal the service end of the strainer body, a portion of the strainer body between the drain opening and the end cap defining a service chamber, the end cap assembly being configured to mount the central axis of the mixture driving member;
stopping a flow of the mixture into the strainer body to the drain opening;
removing the end cap assembly; and
moving the mixture driving member out of the strainer body past one end of the strainer body.

### Claim 26 (depends on 25)

The method according to claim 25, wherein the stopping step is performed by a shut-off valve positioned adjacent the inlet end of the strainer body.