# US 9,751,787 B1 · Anaerobic digesting systems and methods for processing animal waste > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,751,787 B1 - Document ID: US9751787B1 - Status: Granted - Kind: B1 - Application number: 13/592,170 - Filed: 2012-08-22 - Granted: 2017-09-05 - Earliest claimed: 2011-08-23 - Assignees: Daritech, Inc. - Applicants: David DeWaard - Inventors: David DeWaard - Web page: https://patentgrep.com/patent/US9751787B1 ## CPC - C02F 11/04: Anaerobic treatment; Production of methane by such processes - C02F 3/12: Activated sludge processes - C05F 17/40: Treatment of liquids or slurries - C05F 17/50: Treatments combining two or more different biological or biochemical treatments, e.g. anaerobic and aerobic treatment or vermicomposting and aerobic treatment - C12M 29/02: {Percolation} - C12M 33/14: {with filters, sieves or membranes} - C12M 45/04: {Phase separators; Separation of non fermentable material; Fractionation} - C02F 11/121: by mechanical de-watering - C02F 2103/327: {from processes relating to the production of dairy products} - C02F 2203/006: details of construction, e.g. specially adapted seals, modules, connections - 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 - 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) - C05F: ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE - 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 - 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 A digester system for digesting feed material comprises a digester tank, a thickener, and a seal system. The digester tank generates a first digested material and biogas from the feed material. The thickener is operatively connected to the digester tank to remove a second digested material from the feed material to alter a solid content of the feed material in the digester tank. The seal system substantially prevents the thickener from removing biogas from the feed material with the second digested material. ## Claims ### Claim 1 A digester system for digesting feed material comprising liquids and solids, comprising: a digester tank, where the digester tank generates a first digested material and biogas from the feed material; a thickener; a first conduit operatively connected between the thickener and the digester tank to allow a pre-thickened feed material to flow from the digester tank to the thickener; a second conduit operatively connected between the thickener and the digester tank to allow a thickened feed material to flow from the thickener to the digester tank; and a seal conduit operatively connected to the thickener to allow a second digested material to flow out of the thickener; wherein the seal conduit defines a corner portion arranged above the thickener and below a level of the feed material within the digester tank such that the corner portion and the thickener are flooded with teed material substantially to prevent the thickener from allowing entrained biogas in the pre-thickened feed material from exiting the thickener with the second digested material. ### Claim 2 (depends on 1) A digester system as recited in claim 1, in which the seal conduit is configured to maintain back pressure on the second digested material flowing out of the thickener. ### Claim 3 (depends on 1) A digester system as recited in claim 1, further comprising a vacuum break arranged in the corner portion of the seal conduit. ### Claim 4 (depends on 3) A digester system as recited in claim 3, in which the vacuum break terminates above the level of feed material within the digester tank. ### Claim 5 (depends on 1) A digester system as recited in claim 1, in which the thickener maintains a solid content of the feed material in the digester tank within a predetermined range. ### Claim 6 (depends on 1) A digester system as recited in claim 1, further comprising a third conduit operatively connected to the digester tank, where the third conduit allows biogas to flow out of the digester tank. ### Claim 7 (depends on 1) A digester system as recited in claim 1, further comprising a thickener pump for causing at least a portion of the feed material to flow from the digester tank through the first conduit, through the thickener, and back into the digester tank through the second conduit. ### Claim 8 (depends on 1) A digester system as recited in claim 1, in which the thickener comprises a screen structure, where the second digested material flows through the screen structure and out of the thickener. ### Claim 9 (depends on 8) A digester system as recited in claim 8, in which the thickener further comprises: a vane structure; and a housing for supporting the screen structure; whereby rotation of the vane structure relative to the screen structure forces the first portion of the feed material through the screen structure. ### Claim 10 (depends on 9) A digester system as recited in claim 9, in which the vane structure defines at least one working edge in contact with the screen structure. ### Claim 11 (depends on 9) A digester system as recited in claim 9, in which: the screen structure is substantially frustoconical; and the vane structure defines at least one working edge; wherein the at least one working edge is angled such that substantially an entire portion of the at least one working edge is in contact with the screen structure. ### Claim 12 (depends on 9) A digester system as recited in claim 9, in which the thickener further comprises: a motor; and a transmission; wherein the transmission couples the motor to the vane structure such that operation of the motor causes rotation of the vane structure relative to the screen structure about a system axis, and the vane structure may move relative to the motor along the system axis as the vane structure wears. ### Claim 13 (depends on 12) A digester system as recited in claim 12, in which: the screen structure is substantially frustoconical; and the vane structure defines at least one working edge; wherein the at least one working edge is angled with respect to the system axis such that substantially an entire portion of the at least one working edge is in contact with the screen structure. ### Claim 14 A waste processing system for waste slurry, comprising: a digester tank for containing feed material comprising liquids and solids, where the feed material comprises at least a portion of the waste slurry, and the digester tank generates a first digested material and biogas from the feed material; a thickener; a first conduit operatively connected between the thickener and the digester tank to allow a pre-thickened feed material to flow from the digester tank to the thickener; a second conduit operatively connected between the thickener and the digester tank to allow a thickened feed material to flow from the thickener to the digester tank; and a seal conduit operatively connected to the thickener to allow a second digested material to flow out of the thickener; wherein the seal conduit defines a corner portion arranged above the thickener and below a level of the feed material within the digester tank such that the corner portion and the thickener are flooded with feed material substantially to prevent the thickener from allowing entrained biogas in the pre-thickened feed material from exiting the thickener with the second digested material. ### Claim 15 (depends on 14) A waste processing system as recited in claim 14, in which the seal conduit is configured to maintain back pressure on the second digested material flowing out of the thickener. ### Claim 16 (depends on 14) A waste processing system as recited in claim 14, further comprising a vacuum break arranged in the corner portion of the seal conduit. ### Claim 17 (depends on 16) A waste processing system as recited in claim 16, in which the vacuum break terminates above the level of feed material within the digester tank. ### Claim 18 (depends on 14) A waste processing system as recited in claim 14, further comprising a separator for separating the waste slurry into a first slurry portion and a second slurry portion, where the feed material comprises the first slurry portion. ### Claim 19 (depends on 14) A waste processing system as recited in claim 14, further comprising: a first separator for separating the waste slurry into a first slurry portion and a second slurry portion, where the feed material comprises the first slurry portion; and a second separator for separating the second slurry portion into a third slurry portion and a fourth slurry portion, where the feed material further comprises the third slurry portion. ### Claim 20 (depends on 19) A waste processing system as recited in claim 19, in which the fourth slurry portion is used to form at least a portion of the waste slurry. ### Claim 21 (depends on 18) A waste processing system as recited in claim 18, further comprising a batch tank, where the batch tank combines the first slurry portion with water to obtain the feed material. ### Claim 22 (depends on 19) A waste processing system as recited in claim 19, further comprising a batch tank, where the batch tank combines the first slurry portion, the third slurry portion, and water to obtain the feed material. ### Claim 23 (depends on 14) A waste processing system as recited in claim 14, further comprising: a first separator for separating the waste slurry into a first slurry portion and a second slurry portion, where the feed material comprises the first slurry portion; a second separator for separating the second slurry portion into a third slurry portion and a fourth slurry portion; and a third separator for separating the third slurry portion into a fifth slurry portion and a sixth slurry portion, where the feed material further comprises the fifth slurry portion; and a fourth separator for separating the sixth slurry portion into a seventh slurry portion and an eighth slurry portion, where the feed material further comprises the seventh slurry portion. ### Claim 24 (depends on 23) A waste processing system as recited in claim 23, in which the fourth slurry portion is used to form at least a portion of the waste slurry. ### Claim 25 (depends on 23) A waste processing system as recited in claim 23, further comprising a batch tank, where the batch tank combines the first slurry portion, the fifth slurry portion, the seventh slurry portion, and water to obtain the feed material. ### Claim 26 (depends on 18) A waste processing system as recited in claim 18, further comprising a separator for separating the first digested material into a liquid portion and a solids portion. ### Claim 27 (depends on 26) A waste processing system as recited in claim 26, further comprising a storage facility for storing the liquid portion of the first digested material. ### Claim 28 (depends on 27) A waste processing system as recited in claim 27, in which the storage facility further stores the second digested material and the eighth slurry portion. ### Claim 29 (depends on 15) A waste processing system as recited in claim 15, further comprising a thickener pump for causing at least a portion of the feed material to flow from the digester tank through the first conduit, through the thickener, and back into the digester tank through the second conduit. ### Claim 30 (depends on 14) A waste processing system as recited in claim 14, in which the thickener comprises a screen structure, where the second digested material flows through the screen structure and out of the thickener. ### Claim 31 (depends on 30) A waste processing system as recited in claim 30, in which the thickener further comprises: a vane structure; and a housing for supporting the screen structure; whereby rotation of the vane structure relative to the screen structure forces the first portion of the feed material through the screen structure. ### Claim 32 (depends on 31) A waste processing system as recited in claim 31, in which the vane structure defines at least one working edge in contact with the screen structure. ### Claim 33 (depends on 31) A waste processing system as recited in claim 31, in which: the screen structure is substantially frustoconical; and the vane structure defines at least one working edge; wherein the at least one working edge is angled such that substantially an entire portion of the at least one working edge is in contact with the screen structure. ### Claim 34 (depends on 31) A waste processing system as recited in claim 31, in which the thickener further comprises: a motor; and a transmission; wherein the transmission couples the motor to the vane structure such that operation of the motor causes rotation of the vane structure relative to the screen structure about a system axis, and the vane structure may move relative to the motor along the system axis as the vane structure wears. ### Claim 35 (depends on 34) A waste processing system as recited in claim 34, in which: the screen structure is substantially frustoconical; and the vane structure defines at least one working edge; wherein the at least one working edge is angled with respect to the system axis such that substantially an entire portion of the at least one working edge is in contact with the screen structure. ### Claim 36 A method of digesting feed material comprising liquids and solids, the method comprising the steps of: arranging the feed material within a digester tank; combining the feed material with microorganisms within the digester tank to generate a first digested material and biogas from the feed material; allowing a pre-thickened feed material to flow from the digester tank to a thickener; allowing a thickened feed material to flow from the thickener to the digester tank; removing a second digested material from the pre-thickened feed material using the thickener such that the thickened feed material alters a solid content of the feed material in the digester tank; and arranging a seal conduit such that the second digested material flows out of the thickener through the seal conduit and such that at least a corner portion of the seal conduit is above the thickener and below a level of the feed material within the digester tank such that the corner portion and the thickener are flooded with feed material, and back pressure is maintained on the second digested material within the thickener substantially to prevent biogas from being entrained within the second digested feed material leaving the thickener. ### Claim 37 (depends on 36) A method as recited in claim 36, in which the step of removing the second digested material comprises the step of maintaining the solid content of the feed material in the digester tank within a predetermined range. ### Claim 38 (depends on 36) A method as recited in claim 36, further comprising the step of pumping at least a portion of the feed material from the digester tank, through the thickener, and back into the digester tank. ### Claim 39 (depends on 36) A method as recited in claim 36, in which the step of removing the second digested material to alter the solid content of the feed material using the thickener comprises the step of causing the second digested material to flow through a screen.