1. A method, comprising:

a. heating the drying gas;

b. supplying the heated dry gas to a dryer containing the vaporized feedstock to produce a dried vaporized feedstock;

c. gasifying at least a portion of the dried gasification feedstock to generate a syngas;

d. fermenting at least a portion of the syngas in a bioreactor using a microorganism to produce at least one product and a tail gas; and

e. utilizing at least a portion of the tail gas to provide heat for heating the drying gas.

2. The method of claim 1, wherein the gasification feedstock is classified municipal solid waste, unsorted municipal solid waste, industrial solid waste, agricultural waste, forest waste, microbial biomass, lignocellulosic material, sewage, sludge from wastewater treatment, or any combination thereof.

3. The method of claim 1, wherein the tail gas comprises carbon dioxide.

4. The method of claim 3, wherein the tail gas further comprises carbon monoxide, hydrogen, nitrogen, and methane.

5. The method of claim 1, wherein the microorganism is one or more C1 immobilized microorganisms.

6. The method according to claim 5, wherein the C1-immobilized microorganism is selected from the group consisting of Mueller, Clostridium, Ruminococcus, Acetobacter, Eubacterium, Butyribacterium, Acetobacter, Methanosarcina, and Thielenteroides.

7. The method of claim 2, wherein the microbial biomass comprises one or more C1 immobilized microorganisms.

8. The method of claim 7, wherein the C1 immobilized microorganism is selected from the group consisting of Mueller, Clostridium, ruminococcus, Acetobacter, Eubacterium, Butyribacterium, Acetobacter, Methanosarcina, and Thielenteroides.

9. The method of claim 2, wherein the microbial biomass is from a wastewater treatment plant.

10. The method of claim 1, wherein the drying gas is air.

11. The method of claim 1, wherein the gasification results in a higher yield of syngas as compared to gasification without drying the gasification feedstock.

12. The method of claim 1, wherein the gasification produces a higher syngas quality than gasification without drying the gasification feedstock.

13. The method of claim 1, wherein the tail gas is combusted to provide heat for heating the drying gas.

14. The method of claim 1, wherein the tail gas is combusted in a burner to provide heat for heating the drying gas.

15. An apparatus, comprising:

a. a dryer having one or more burners for heating a drying gas, the dryer in communication with the feedstock conduit;

b. a vaporizer in communication with the dryer;

c. a bioreactor in fluid communication with the gasifier;

d. a product conduit and a tail gas conduit, the conduits in fluid communication with the bioreactor; and is

e. The tail gas conduit is also in fluid communication with the one or more burners.

16. The apparatus of claim 15, further comprising a dryer gas conduit in communication with the dryer and capable of heat exchange communication with at least one burner.

17. The apparatus of claim 15, further comprising a product recovery unit in fluid communication with a wastewater treatment unit and a first recirculation conduit from the wastewater treatment unit to the dryer.

18. The apparatus of claim 17, further comprising a biogas processing unit in fluid communication with the first recirculation conduit.

19. The apparatus of claim 15, further comprising a second recycle conduit from the product recovery unit to the dryer.

20. The apparatus of claim 15, further comprising at least one removal unit in fluid communication with at least the gasifier and the bioreactor.

Background

As the world population increases, the waste generated by this population becomes an increasingly interesting problem. One solution for waste disposal is gasification. Gasification is a process of converting carbonaceous material based on organic or fossil fuels into synthesis gas comprising carbon monoxide, carbon dioxide and hydrogen. Gasification advantageously both reduces the amount of waste in the landfill and produces product syngas, which can be converted to useful products by one or more subsequent processes.

The syngas produced from gasification can be utilized by a number of processes including the fischer-tropsch process. The fischer-tropsch process provides for the catalytic hydrogenation of carbon monoxide to produce a variety of products, including hydrocarbons, alcohols, or other oxygenated hydrocarbons. However, the catalytic bed in the fischer-tropsch process is particularly sensitive to the various components that may be present in the synthesis gas stream (depending on the gasification feedstock). One such component is sulfur. If sulfur is not removed from the synthesis gas stream prior to sending the synthesis gas stream to the fischer-tropsch process, the sulfur may deactivate the catalyst required for the fischer-tropsch reaction. Therefore, extensive gas purification techniques are generally required in order to obtain a gas suitable for the fischer-tropsch process.

An alternative to the fischer-tropsch process is gas fermentation. Gas fermentation biologically immobilizes a gas (including syngas) into one or more products. Gas fermentation has several advantages over the fischer-tropsch process. First, the fischer-tropsch process utilizes high temperatures (150 ℃ to 350 ℃), elevated pressures (30 bar) and heterogeneous catalysts such as cobalt, ruthenium and iron. In contrast, gas fermentation occurs at about 37 ℃ and is typically carried out at atmospheric pressure, relative to the fischer-tropsch process,this saves a lot of energy and costs. In addition, the Fischer-Tropsch process requires H in the syngas₂CO ratio is relatively fixed, around 2:1, whereas gas fermentation is capable of receiving and utilizing H with differences₂Various substrates for CO ratios.

When integrating gasification to produce syngas and gas fermentation, measures can be taken to control the type of syngas produced. For example, drying biomass has been discussed in Li, H.Chen, Q., Zhang, X.Finney, K.N., Sharifi, V.N., Swithenbank, J. (2012) Evaluation of a biomass drying process from processes industries: A case study. applied Thermal Engineering,35, 71-80. In the field of pyrolysis and gasification, operating parameters and moisture contents were investigated in Dong, J., Chi, Y, Tang, Y.Ni, M.Nzihou, A., Weiss-Hortala, E.Huang, Q. (2016) Effect of operating parameters and motion content on microbial solid waste gasification, energy & Fuels,30(5), 3994-.

However, there is still a need for a higher level of integration between gasification operations and gas fermentation operations such that the waste stream of one operation is used by the other in the most beneficial way. An unexpectedly beneficial use of the tail gas from a gas fermentation operation is to employ at least a portion of the tail gas to heat the drying gas which is in turn used to dry the feedstock for a gasification operation. Drying the feedstock for gasification operations provides a higher yield and higher quality syngas, thereby increasing the yield of desired products from the overall system of integrated gasification and gas fermentation operations. Surprisingly, from an energy point of view, the energy recovered from the off-gas is significantly greater when used to dry the feedstock than when used to generate electricity or steam.

Disclosure of Invention

The present disclosure relates to a method comprising heating a drying gas; supplying the heated dry gas to a dryer containing the vaporized feedstock to produce a dried vaporized feedstock; gasifying at least a portion of the dried gasification feedstock to generate a syngas; fermenting at least a portion of the syngas in a bioreactor using a microorganism to produce at least one product and a tail gas; and utilizing at least a portion of the tail gas to provide heat to heat the drying gas. In one embodiment, the gasification feedstock is municipal solid waste, agricultural waste, microbial biomass, or any combination thereof. In one embodiment, the tail gas includes carbon dioxide, carbon monoxide, hydrogen, nitrogen, and methane.

The present disclosure also relates to an apparatus, comprising: a dryer having one or more burners for heating a drying gas, the dryer being in communication with the feedstock conduit; a vaporizer in communication with the dryer; a bioreactor in fluid communication with the gasifier; a product conduit and a tail gas conduit, the conduits being in fluid communication with the bioreactor; and the exhaust gas conduit is also in fluid communication with the one or more burners.

In one embodiment, the fermentation process utilizes one or more C1 immobilized microorganisms suitable for fermenting a C1 containing gaseous substrate, such as syngas produced by gasification. In various embodiments, the C1 immobilized microorganism is selected from the group consisting of: moorella (Moorella), Clostridium (Clostridium), Ruminococcus (Ruminococcus), acetobacter (acetobacter), Eubacterium, butyrobacterium (butyrobacterium), acetobacter (oxobacterium), Methanosarcina (Methanosarcina), and sulfoenterobacter (desulfomobacterium). The microorganism may be a member of the genus clostridium. In some cases, the microorganism is Clostridium autoethanogenum.

In various embodiments, the gasification feedstock is municipal solid waste, industrial solid waste, agricultural waste, lignocellulosic material, microbial biomass, or any combination thereof. The gasification feedstock is dried in a dryer and then gasified to produce a syngas stream. At least a portion of the syngas stream is passed to a fermentation process to produce one or more products and possibly at least one byproduct. In some embodiments, the microbial biomass produced from the fermentation process is passed to the gasification operation as a feedstock for gasification.

In some embodiments, substantially all of the microbial biomass produced by the fermentation process is recycled to the fermentation process after product recovery, treated by a wastewater treatment process, and/or sent to a gasification process to produce syngas. In certain instances, the gasification process receives at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or substantially all of the microbial biomass from the fermentation process.

In some embodiments, the microbial biomass produced from the wastewater treatment process is sent to a gasification process. Microbial biomass generated from a wastewater treatment process may be at least partially recovered from an anaerobic digester process in the wastewater treatment process. In each case, at least a portion of the microbial biomass from the wastewater treatment process is dried before being passed to the gasification process. In some cases, substantially all of the microbial biomass from the wastewater treatment process is dried before being passed to the gasification process.

In a particular embodiment, at least a portion of the microbial biomass-depleted water from the fermentation process is sent to the gasification process. In each case, the water depleted in microbial biomass is sent to a gasification process to increase the H in the syngas stream₂The ratio of CO. Preferably, at least a portion of the microbial biomass-depleted water is sent to a gasification process to convert H in the syngas stream₂The CO ratio is increased to at least 2:1, at least 3:1, or at least 4: 1. Passing the microbial biomass-depleted water to a gasification process (wherein H in the syngas stream₂I.e. increased CO ratio) may lead to an increased selectivity for ethanol produced by the gas fermentation process, a decreased selectivity for microbial biomass production, a decreased water consumption for the fermentation reaction and/or a decreased blowdown stream from the wastewater treatment process.

In particular embodiments, at least a portion of the wastewater produced from the fermentation process is sent to the gasification process. The wastewater may comprise one or more products and/or by-products, including but not limited to microbial biomass. In each case, the wastewater generated from the fermentation process is sent to a gasification process to increase the H in the syngas stream₂The ratio of CO. PreferablyAt least a portion of the wastewater generated from the fermentation process is sent to a gasification process to convert H in the syngas stream₂The CO ratio is increased to at least 2:1, at least 3:1, or at least 4: 1. The wastewater generated from the fermentation process is sent to a gasification process (where H in the syngas stream is₂I.e. increased CO ratio) may lead to an increased selectivity for ethanol produced by the gas fermentation process, a decreased selectivity for microbial biomass production, a decreased water consumption for the fermentation reaction and/or a decreased blowdown stream from the wastewater treatment process.

In particular embodiments, at least a portion of the clarified water from the wastewater treatment process is sent to a gasification process. In each case, clarified water from a wastewater treatment process is sent to a gasification process to increase H in a syngas stream₂The ratio of CO. Preferably, at least a portion of clarified water from the wastewater treatment process is sent to the gasification process to convert H in the syngas stream₂The CO ratio is increased to at least 2:1, at least 3:1, or at least 4: 1. Sending clarified water from the wastewater treatment process to a gasification process (wherein H in the syngas stream₂I.e. increased CO ratio) may lead to an increased selectivity for ethanol produced by the gas fermentation process, a decreased selectivity for microbial biomass production, a decreased water consumption for the fermentation reaction and/or a decreased blowdown stream from the wastewater treatment process.

Preferably, at least a portion of at least one effluent from the fermentation process and/or the wastewater treatment process replaces at least a portion of the process water required for the gasification process. In some cases, the process water required for the gasification process is reduced by at least 45%. In at least one embodiment, the process water required for the gasification process is reduced by 45% to 100%. In certain embodiments, the process water required for the gasification process is reduced by 45% to 75%, 55% to 75%, 65% to 75%, 55% to 100%, 65% to 100%, or 75% to 100%.

In certain instances, at least a portion of the at least one effluent is injected into a syngas stream produced by the gasification process to reduce the temperature of the syngas stream. Preferably, the effluent injected into the synthesis gas stream produced by the gasification process is selected from the group consisting of: water depleted in microbial biomass, wastewater produced from fermentation processes, and clarified water from wastewater treatment plants. Preferably, the temperature of the syngas stream is reduced by at least 100 degrees celsius. In at least one embodiment, the syngas stream exiting the gasification process is between 800 ℃ and 1200 ℃. Preferably, the temperature of the synthesis gas stream is reduced to a temperature range suitable for further gas treatment and/or fermentation. In each case, the injection of the at least one effluent into the syngas stream is accomplished to remove the at least one particulate from the syngas stream.

In some cases, the syngas stream is partially quenched. Preferably, the synthesis gas stream is partially quenched by injecting one or more effluents into the synthesis gas stream, the one or more effluents being selected from the group consisting of: water depleted in microbial biomass, wastewater produced from fermentation processes, and clarified water from wastewater treatment plants. In various embodiments, the partial quenching of the syngas stream reduces the temperature of the syngas stream to 700 ℃ to 800 ℃. In various embodiments, this temperature reduction requires approximately 1.2 tons of process water per 10,000Nm, starting at 1000 deg.C³The synthesis gas is quenched. Preferably, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or substantially all of the process water is replaced by injecting one or more effluents into the synthesis gas stream.

In some cases, the syngas stream is fully quenched. Preferably, the synthesis gas stream is fully quenched by injecting one or more effluents into the synthesis gas stream, the one or more effluents being selected from the group consisting of: water depleted in microbial biomass, wastewater produced from fermentation processes, and clarified water from wastewater treatment plants. In various embodiments, the complete quenching of the syngas stream reduces the temperature of the syngas stream to less than 300 ℃. In various embodiments, this temperature reduction requires approximately 4 tons of process water per 10,000Nm, starting at 1000 deg.C³The synthesis gas is quenched. Preferably, the process water is at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90% of the process waterOr substantially all, by injecting one or more effluents into the synthesis gas stream.

In particular embodiments, at least a portion of the biogas generated from the wastewater treatment process is sent to the gasification process. The biogas may comprise one or more components selected from the group consisting of: methane, carbon dioxide, carbon monoxide, ammonia, and sulfur compounds. In each case, this sulfur compound is hydrogen sulfide. In at least one embodiment, the biogas comprises about 60% methane and about 40% carbon dioxide. In at least one embodiment, the biogas comprises about 65% methane and about 35% carbon dioxide.

In particular embodiments, at least a portion of the biogas generated from the wastewater treatment process is used as a heating source. Preferably, at least a portion of the biogas generated from the wastewater treatment process is used as a heating source by the gasification process. In each case, at least a portion of the biogas sent to the gasification process is used as a heating source for melting at least a portion of the slag produced by the gasification process. In one or more embodiments, biogas from the wastewater treatment process is sent to a removal process before being sent to the gasification process. In each case, the removal process includes one or more removal units capable of removing, converting, and/or reducing the amount of at least one component in the biogas stream. Preferably, the removal process removes at least a portion of the at least one sulfur compound from the biogas stream before the biogas stream is sent to the gasification process.

In particular embodiments, at least a portion of the methane in the biogas is reformed to CO and H when gasified by a gasification process₂. In each case, the methane reacts with the moisture contained in the syngas to produce carbon monoxide and hydrogen.

In one embodiment, at least a portion of the tail gas generated from the fermentation process, unused syngas generated from the gasification process, crude ethanol from the product recovery process, and/or fusel oil from the product recovery process is used as the heating source. Preferably, at least a portion of at least one of these effluents is used as a heating source by the gasification process. In each case, at least a portion of at least one of these effluents is sent to the gasification process to be used as a heating source for melting at least a portion of the slag produced by the gasification process. In one or more embodiments, these effluents are treated by a removal process before being sent to the gasification process. In various instances, the removal process includes one or more removal units capable of removing, converting, and/or reducing the amount of at least one component in the effluent.

In addition to passing at least a portion of the clarified water from the wastewater treatment process to the gasification process, at least a portion of the clarified water from the wastewater treatment process may also be passed to the fermentation process. In certain instances, substantially all of the clarified water from the wastewater treatment process is recycled to the gasification process and/or the fermentation process. In certain instances, the gasification process receives at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or substantially all of the clarified water from the wastewater treatment process. In certain instances, the fermentation process receives at least 10%, at least 20%, at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, at least 90%, or substantially all of the clarified water from the wastewater treatment process.

Preferably, the fermentation process utilizes at least a portion of the syngas from the gasification process to produce one or more fuels or chemicals. At least one of the products produced by the fermentation process may be selected from the group comprising: ethanol, acetate, butanol, butyrate, 2, 3-butanediol, 1, 3-butanediol, lactate, butene, butadiene, methyl ethyl ketone, ethylene, acetone, isopropanol, lipids, 3-hydroxypropionate salts, terpenes (including but not limited to isoprene), fatty acids, 2-butanol, isobutylene, isobutanol, 1, 2-propanediol, 1-propanol, and C6-C12 alcohols.

In one or more embodiments, at least a portion of the microbial biomass produced by the fermentation process can be converted to Single Cell Protein (SCP).

In each case, at least a portion of the one or more fuels or chemicals is sent to a secondary conversion process. Preferably, the secondary conversion process further converts at least a portion of the one or more fuels or chemicals to at least one component of diesel fuel, jet fuel, gasoline, propylene, nylon 6-6, rubber, and/or resin.

In one or more embodiments, the syngas from the gasification process is sent to a removal process before being sent to the fermentation process. In each case, the removal process includes one or more removal units capable of removing, converting and/or reducing the amount of microbial inhibitors and/or catalyst inhibitors contained in the syngas stream.

Preferably, the at least one component removed, converted and/or reduced in the synthesis gas stream by the removal process is selected from the group comprising: sulfur compounds, aromatics, alkynes, alkenes, alkanes, alkenes, nitrogen compounds, phosphorous compounds, particulates, solids, oxygen, halogenated compounds, silicon-containing compounds, carbonyl compounds, metals, alcohols, esters, ketones, peroxides, aldehydes, ethers, and tars.

Preferably, the removal process comprises at least one removal unit selected from the group comprising: a hydrolysis unit, an acid gas removal unit, a deoxygenation unit, a catalytic hydrogenation unit, a particle removal unit, a chloride removal unit, a tar removal unit, and a hydrogen cyanide polishing unit. In each case, the removal process includes at least two removal units.

The present disclosure may also provide for an increase and/or decrease in the pressure of the syngas stream at one or more points in the process.

Drawings

Fig. 1 shows a process integration scheme depicting the integration of a gasification process, a gas fermentation process, a product recovery process, and a wastewater treatment process, according to one embodiment of the present disclosure.

Fig. 2 shows the process integration scheme from fig. 1, further including a removal process between the gasification process and the gas fermentation process, according to one embodiment of the present disclosure.

Fig. 3 shows the process integration scheme from fig. 2, further including a removal process following the wastewater treatment process, according to one embodiment of the present disclosure.

Detailed Description

The present disclosure describes the integration of a gasification process and a fermentation process and optionally a wastewater treatment process. The off-gas from the fermentation process is recycled to the gasification process as fuel for the burner in the feedstock dryer of the gasification process, thereby providing a number of unexpected benefits to the efficiency and synergy of the integrated process.

The terms "increased efficiency", "increased efficiency" and the like, when used in connection with a fermentation process, include, but are not limited to: increasing one or more of the growth rate, growth rate at elevated product concentration, and/or product production rate of a microorganism catalyzing the fermentation, increasing the volume of desired product produced per volume of substrate consumed, increasing the production rate or level of desired product produced, increasing the relative proportion of desired product produced compared to other byproducts of the fermentation, reducing the amount of water consumed by the process, and reducing the amount of energy utilized by the process.

The terms "increased efficiency," "increased efficiency," and the like, when used in connection with a gasification process, include, but are not limited to: increasing the amount of syngas produced by the process, decreasing the amount of water supply utilized by the process, optimizing the syngas stream for gas fermentation, decreasing greenhouse gas emissions, and decreasing the amount of energy (including but not limited to external fuel) utilized by the process.

The terms "increased efficiency", and the like, when used in connection with a wastewater treatment process, include, but are not limited to: reducing the residence time of water in the process, increasing the utilization of the biogas generated by the process, reducing the amount of effluent sent to a wastewater treatment process, reducing the volume requirements of the process, reducing the need for ammonia separation by the process, and reducing the amount of energy utilized by the process.

The terms "fermentation", "gas fermentation", and the like should be construed as a process that receives one or more substrates (such as syngas produced by gasification) and produces one or more products by utilizing one or more C1-immobilized microorganisms. Preferably, the fermentation process comprises the use of one or more bioreactors. The fermentation process may be described as "batch" or "continuous". "batch fermentation" is used to describe such a fermentation process: wherein the bioreactor is filled with raw materials (e.g. carbon source) together with microorganisms, wherein the product remains in the bioreactor until the fermentation is completed. In a "batch" process, the product is extracted after the fermentation is completed and the bioreactor is cleaned before the next "batch" is started. "continuous fermentation" is used to describe a fermentation process: wherein the fermentation process is extended for a longer period of time and products and/or metabolites are extracted during the fermentation. Preferably, the fermentation process is continuous.

The term "wastewater treatment" or the like should be construed as a process of separating components from an effluent from a fermentation process to produce clarified water. Wastewater treatment processes may include, but are not limited to, one or more anaerobic digesters with different residence times, and one or more ammonia stripping processes.

The terms "gasification" and the like should be construed to convert organic and/or fossil fuel based carbonaceous materials to carbon monoxide (CO), hydrogen (H)₂) And carbon dioxide (CO)₂) The process of (1). The gasification process may include a variety of technologies including, but not limited to, a counter-current fixed bed gasifier, a co-current fixed bed gasifier, a fluidized bed reactor, an entrained flow gasifier, and a plasma gasifier. The gasification process may utilize any feed that can produce a syngas stream. The term "gasification process" encompasses the gasifier itself along with unit operations associated with gasification, including heating sources for the gasifier and syngas quenching processes.

"syngas stream," "syngas stream," and the like refer to the gaseous substrate exiting the gasification process. The synthesis gas stream should consist mainly of carbon monoxide (CO), hydrogen (H)₂) And carbon dioxide (CO)₂) And (4) forming. The composition of the synthesis gas stream may vary significantly depending on the feedstock and gasification process involved; however, a typical composition of syngas includes thirty percentTo sixty percent (30% to 60%) carbon monoxide (CO), twenty-five to thirty percent (25% to 30%) hydrogen (H)₂) Zero to five percent (0 to 5%) methane (CH)₄) Five to fifteen percent (5 to 15%) carbon dioxide (CO)₂) Plus a lesser or greater amount of water vapor, a lesser amount of sulfur compounds, hydrogen sulfide (H)₂S), carbonyl sulfide (COS), ammonia (NH)₃) And other trace contaminants.

In particular embodiments, the presence of hydrogen results in an increase in the overall efficiency of alcohol production by the fermentation process.

The syngas composition can be modified to provide the desired or optimal H₂:CO:CO₂A ratio. The syngas composition can be improved by adjusting the feedstock fed to the gasification process. Desired H₂:CO:CO₂The ratio depends on the desired fermentation product of the fermentation process. For ethanol, the optimum H₂:CO:CO₂The ratio will be:wherein x>2y, in order to meet the stoichiometric requirements for ethanol production

Operating a fermentation process in the presence of hydrogen has the effect of reducing the CO produced by the fermentation process₂An additional benefit of the amount of (c). E.g. containing a minimum of H₂Will generally produce ethanol and CO by the following stoichiometry₂：[6CO+3H₂O→C₂H₅OH+4CO₂]. As the amount of hydrogen utilized by the C1 immobilized bacteria increases, CO produced₂Reduced amount of [ e.g., 2CO +4H₂→C₂H₅OH+H₂O]。

When CO is the only carbon and energy source for ethanol production, a portion of the carbon is lost to CO as follows₂：

6CO+3H₂O→C₂H₅OH+4CO₂(Δ G ° -224.90 kJ/mol ethanol)

With available H in the substrate₂Is increased, CO is produced₂The amount of (c) is reduced. At a stoichiometric ratio of 2:1 (H)₂CO) is completely avoided₂Is generated.

5CO+1H₂+2H₂O→1C₂H₅OH+3CO₂(Δ G ° -204.80 kJ/mol ethanol)

4CO+2H₂+1H₂O→1C₂H₅OH+2CO₂(Δ G ° -184.70 kJ/mol ethanol)

3CO+3H₂→1C₂H₅OH+1CO₂(Δ G ° -164.60 kJ/mol ethanol)

"stream" refers to any substrate that can be transferred, for example, from one process to another, from one unit to another, and/or from one process to a carbon capture device.

As used herein, "reactant" refers to a substance that participates in and undergoes a change during a chemical reaction. In particular embodiments, the reactants include, but are not limited to, CO and/or H₂。

As used herein, "microbe-inhibiting agent" refers to one or more ingredients that slow or prevent a particular chemical reaction or another process involving a microbe. In particular embodiments, microbial inhibitors include, but are not limited to, oxygen (O)₂) Hydrogen Cyanide (HCN), acetylene (C)₂H₂) And BTEX (benzene, toluene, ethylbenzene, xylene).

As used herein, "catalyst inhibitor," "sorbent inhibitor," and the like refer to one or more substances that reduce the rate of or prevent a chemical reaction. In particular embodiments, the catalyst inhibitor and/or sorbent inhibitor may include, but is not limited to, hydrogen sulfide (H)₂S) and carbonyl sulfide (COS).

"removal process", "removal unit", "cleanup unit", and the like include techniques capable of converting and/or removing microbial inhibitors and/or catalyst inhibitors from a gas stream. In particular embodiments, the catalyst inhibitor must be removed by an upstream removal unit in order to prevent inhibition of one or more catalysts in a downstream removal unit.

The terms "ingredient," "contaminant," and the like as used herein refer to a microbial inhibitor and/or a catalyst inhibitor that may be found in a gas stream. In particular embodiments, these ingredients include, but are not limited to, sulfur compounds, aromatics, alkynes, alkenes, alkanes, alkenes, nitrogen compounds, phosphorous compounds, particulates, solids, oxygen, halogenated compounds, silicon-containing compounds, carbonyl compounds, metals, alcohols, esters, ketones, peroxides, aldehydes, ethers, and tars.

The terms "treated gas," "treated stream," and the like refer to a gas stream that has passed through at least one removal unit and has had one or more components removed and/or converted.

The term "carbon capture" as used herein refers to sequestration from the inclusion of CO₂And/or carbon compounds of a stream of CO (including CO)₂And/or CO), and:

introducing CO₂And/or CO to product; or

Introducing CO₂And/or CO conversion to a substance suitable for long term storage; or

Introducing CO₂And/or CO is captured in a substance suitable for long-term storage;

or a combination of these processes.

The terms "bioreactor", "reactor", and the like include a fermentation device consisting of one or more vessels and/or a column or piping arrangement, including a Continuously Stirred Tank Reactor (CSTR), an Immobilized Cell Reactor (ICR), a Trickle Bed Reactor (TBR), a bubble column, an airlift fermentor, a static mixer, a circulating loop reactor, a membrane reactor such as a hollow fiber membrane bioreactor (HFM BR), or other vessel or other device suitable for gas-liquid contact. The reactor is preferably adapted to receive a gaseous substrate, comprising CO or CO₂Or H₂Or mixtures thereof. The reactor may comprise a plurality of reactors (trays) in parallel or in series. For example, the reactor may be included inA first growth reactor in which the bacteria are cultured and a second fermentation reactor into which the fermentation broth from the growth reactor can be fed and in which most of the fermentation product can be produced.

"nutrient medium" is used to describe a bacterial growth medium. Preferably, the fermentation process utilizes a nutrient medium within the bioreactor. Generally, the term refers to a medium containing nutrients and other components suitable for the growth of a microbial culture. The term "nutrient" includes any substance that can be utilized in the metabolic pathway of a microorganism. Exemplary nutrients include potassium, vitamin B, trace metals, and amino acids.

The term "fermentation broth" or broth "is intended to encompass a mixture of components including a nutrient medium and a culture or one or more microorganisms. Preferably, the fermentation process utilizes a fermentation broth to ferment the syngas stream into one or more products.

The term "acid" as used herein includes both carboxylic acids and associated carboxylate anions, such as a mixture of free acetic acid and acetate present in a fermentation broth as described herein. The ratio of molecular acid to carboxylate in the fermentation broth depends on the pH of the system. In addition, the term "acetate salt" includes acetate salts alone as well as acetic acid molecules or mixtures of free acetic acid and acetate salts, such as mixtures of acetate salts and free acetic acid present in a fermentation broth as described herein.

The term "desired composition" is used to refer to the desired level and type of components in a substance, such as a gas stream, including but not limited to syngas. More particularly if the gas contains specific components (e.g. CO, H)₂And/or CO₂) And/or contains a specific component in a specific ratio and/or does not contain a specific component (e.g., a contaminant harmful to microorganisms) and/or does not contain a specific component in a specific ratio, the gas is considered to have a "desired composition". More than one component may be considered in determining whether the gas stream has the desired composition.

Unless the context requires otherwise, the phrases "fermentation", "fermentation process" or "fermentation reaction" and the like as used herein are intended to encompass both the growth phase and the product biosynthesis phase of the gaseous substrate.

"microorganisms" are microscopic organisms, in particular bacteria, archaea, viruses or fungi. The microorganisms of the present disclosure are typically bacteria. As used herein, a recitation of "microorganism" should be considered to encompass "bacteria". It should be noted that the terms "microorganism" and "bacterium" are used interchangeably throughout this document.

A "parent microorganism" is a microorganism used to produce the microorganisms of the present disclosure. A parent microorganism can be a naturally occurring microorganism (e.g., a wild-type microorganism) or a microorganism that has been previously modified (e.g., a mutant microorganism or a recombinant microorganism). The microorganisms of the present disclosure may be modified to express or overexpress one or more enzymes that are not expressed or overexpressed in the parent microorganism. Similarly, a microorganism of the present disclosure can be modified to contain one or more genes that a parental microorganism does not contain. The microorganisms of the present disclosure may also be modified to not express or express lower amounts of one or more enzymes expressed in the parental microorganism. In one embodiment, the parent microorganism is Clostridium autoethanogenum, Clostridium autodahlii (Clostridium ljungdahlii) or Clostridium ragsdalei (Clostridium ragsdalei). In one embodiment, the parental microorganism is Clostridium ethanogenum LZ1561, deposited at 7.2010 at 7.6.2010 under the terms of the Budapest Treaty at 7.2010 in Deutsche Sammlung von Mikroorganismen und Zellkulturen GmbH (DSMZ) in Braunschweig, Inhoffenstra beta e 7B, D-38124 and having the accession number DSM 23693. This strain is described in international patent application No. PCT/NZ2011/000144, which is published as WO 2012/015317.

The term "derived from" means that the nucleic acid, protein or microorganism is modified or engineered from a different (e.g., parental or wild-type) nucleic acid, protein or microorganism in order to produce a new nucleic acid, protein or microorganism. Such modifications or alterations typically include insertions, deletions, mutations or substitutions of nucleic acids or genes. Generally, the microorganisms of the present disclosure are derived from a parental microorganism. In one embodiment, the microorganism of the present disclosure is derived from clostridium autoethanogenum, clostridium andraeanum, or clostridium ragsdalei. In one embodiment, the microorganism of the present disclosure is derived from clostridium autoethanogenum LZ1561 deposited as DSMZ accession No. DSM 23693.

"Wood-Ljungdahl" refers to the carbon-immobilized Wood-Yangdahl pathway as described, for example, by Ragsdale, Biochim Biophys Acta,1784: 1873-. Predictably, "wood-Yandall microorganism" refers to a microorganism that contains the wood-Yandall pathway. Generally, the microorganisms of the present disclosure contain a natural wood-yandall pathway. In this context, the wood-Yandall pathway may be a natural unmodified wood-Yandall pathway, or may be a wood-Yandall pathway that has been genetically modified to some extent (e.g., overexpressed, heterologously expressed, knocked-out, etc.), provided that it still converts CO, CO₂And/or H₂Conversion to acetyl-CoA.

"C1" refers to a carbon molecule, e.g., CO₂、CH₄Or CH₃And (5) OH. "C1 oxygenate" means a carbon molecule further comprising at least one oxygen atom, e.g., CO₂Or CH₃And (5) OH. "C1 carbon source" refers to a carbon molecule that is used as part or the sole carbon source for a microorganism of the present disclosure. For example, the C1 carbon source may include one or more of the following: CO, CO₂、CH₄、CH₃OH or CH₂O₂. Preferably, the C1 carbon source includes CO and CO₂One or both of them. A "C1 immobilized microorganism" is a microorganism having the ability to produce one or more products from a C1 carbon source. Typically, the microorganism of the present disclosure is a C1 immobilized bacterium.

An "anaerobic microorganism" is a microorganism that does not require oxygen to grow. Anaerobic microorganisms may produce adverse reactions or even die if oxygen is present above a certain threshold. However, some anaerobic microorganisms are able to tolerate low levels of oxygen (e.g., 0.000001% to 5% oxygen). Typically, the microorganism of the present disclosure is an anaerobic microorganism.

"acetogenic bacteria" are obligate anaerobic bacteria that utilize the wood-Yangdale applicationAs a major mechanism for their energy saving and synthesis of acetyl-CoA and acetyl-CoA derived products such as acetate (Ragsdale, Biochim Biophys Acta,1784: 1873-. In particular, acetogens use the wood-yandall pathway as: (1) for removing CO from₂A mechanism for reductive synthesis of acetyl-coa; (2) a terminal electron receiving and energy saving process; (3) for the immobilisation (assimilation) of CO in cellular carbon Synthesis₂(Drake, academic Prokaryotes, by The Prokaryotes, 3 rd edition, page 354, New York, NY, 2006). All naturally occurring acetogens are C1 immortal, anaerobic, autotrophic and nonmethanotrophic. Typically, the microorganism of the present disclosure is an acetogen.

An "ethanologen" is a microorganism that produces or is capable of producing ethanol. Typically, the microorganism of the present disclosure is an ethanologenic organism.

An "autotroph" is a microorganism that is capable of growing in the absence of organic carbon. In contrast, autotrophs use inorganic carbon sources, such as CO and/or CO₂. Typically, the microorganism of the present disclosure is an autotroph.

"carboxydotrophic organisms" are microorganisms that are capable of utilizing CO as the sole source of carbon and energy. Typically, the microorganism of the present disclosure is a carboxydotrophic organism.

"methanotrophic organisms" are microorganisms that are capable of utilizing methane as the sole source of carbon and energy. In certain embodiments, the microorganism of the present disclosure is a methanotrophic organism or is derived from a methanotrophic organism. In other embodiments, the microorganism of the present disclosure is not a methanotrophic organism or is not derived from a methanotrophic organism.

"substrate" refers to a source of carbon and/or energy of a microorganism of the present disclosure. Typically, the substrate is gaseous and comprises a C1 carbon source, e.g., CO₂And/or CH₄. Preferably, the substrate comprises the C1 carbon source CO or CO + CO₂. The substrate may also contain other non-carbon components, such as H₂Or N₂。

The term "co-substrate" refers to a substance that, while not necessarily the primary source of energy and material for product synthesis, can be used for product synthesis when added to another substrate (such as a primary substrate).

The composition of the substrate may have a significant impact on the efficiency and/or cost of the reaction. For example, oxygen (O) is present₂) The efficiency of the anaerobic fermentation process may be reduced. Depending on the composition of the substrate, it may be necessary to treat, scrub or filter the substrate to remove any undesirable impurities (such as toxins, undesirable components or dust particles) and/or to increase the concentration of the desirable components.

In certain embodiments, the fermentation is conducted in the absence of a carbohydrate substrate (such as a sugar, starch, lignin, cellulose, or hemicellulose).

The microorganisms of the present disclosure may be cultured with a gas stream to produce one or more products. For example, the microorganisms of the present disclosure may produce or may be engineered to produce ethanol (WO 2007/117157), acetate (WO 2007/117157), butanol (WO 2008/115080 and WO 2012/053905), butyrate (WO 2008/115080), 2, 3-butanediol (WO 2009/151342 and WO 2016/094334), lactate (WO 2011/112103), butene (WO 2012/024522), butadiene (WO 2012/024522), methyl ethyl ketone (2-butanone) (WO 2012/024522 and WO 2013/185123), ethylene (WO 2012/026833), acetone (WO 2012/115527), isopropanol (WO 2012/115527), lipids (WO 2013/036147), 3-hydroxypropionate (3-HP) (WO 2013/180581), terpenes (including isoprene (WO 2013/180584)), (WO 2012/024522)), (iii), Fatty acids (WO 2013/191567), 2-butanol (WO 2013/185123), 1, 2-propanediol (WO 2014/036152), 1-propanol (WO 2014/0369152), branched acid derivative products (WO 2016/191625), 3-hydroxybutyrate (WO 2017/066498) and 1, 3-butanediol (WO 2017/0066498). In certain embodiments, the microbial biomass itself may be considered a product. These products may be further converted to produce at least one component of diesel, jet fuel, and/or gasoline. In addition, the microbial biomass may be further processed to produce Single Cell Proteins (SCPs).

"Single Cell Protein (SCP)" refers to a microbial biomass that can be used in protein-rich human and/or animal feed foods, often replacing conventional sources of protein supplementation, such as soybean meal or fish meal. The process may include additional separation steps, processing steps or processing steps in order to produce single cell proteins or other products. For example, the method can include sterilizing the microbial biomass, centrifuging the microbial biomass, and/or drying the microbial biomass. In certain embodiments, the microbial biomass is dried using spray drying or paddle drying. The method may further comprise reducing the nucleic acid content of the microbial biomass using any method known in the art, as ingestion of a diet high in nucleic acid content may result in accumulation of nucleic acid degradation products and/or gastrointestinal discomfort. The single-cell protein may be suitable for feeding animals, such as livestock or pets. In particular, the animal feeding diet may be suitable for feeding one or more of beef cattle, dairy cows, pigs, sheep, goats, horses, mules, donkeys, deer, buffalo/bison, llama, alpaca, reindeer, camels, ruminants, gayal, yaks, chickens, turkeys, ducks, geese, quail, guinea fowl, squab/pigeon, fish, shrimp, crustaceans, cats, dogs and rodents. The composition of the food fed to the animal can be tailored to the nutritional requirements of different animals. Additionally, the process can include blending or combining the microbial biomass with one or more excipients.

"excipient" can refer to any substance that can be added to microbial biomass to enhance or modify the form, nature, or nutritional content of the food fed to an animal. For example, the excipients may include one or more of the following: carbohydrates, fibres, fats, proteins, vitamins, minerals, water, flavourings, sweeteners, antioxidants, enzymes, preservatives, probiotics or antibiotics. In some embodiments, the excipient may be hay, straw, silage, grain, oil or fat, or other plant material. The excipients may be those described in Chiba, section 18: diet Formulation and Common Feed Ingredients, Animal Nutrition Handbook, revised 3 rd edition, pages 575 to 633, 2014 any of the fed food Ingredients identified.

A "natural product" is a product produced by a microorganism that has not been genetically modified. For example, ethanol, acetate and 2, 3-butanediol are natural products of Clostridium autoethanogenum, Clostridium andreanum and Clostridium ragsdalei. A "non-natural product" is a product produced by a genetically modified microorganism, and not a product produced by a genetically unmodified microorganism from which the genetically modified microorganism is derived.

"selectivity" refers to the ratio of the yield of a product of interest to the yield of the total fermentation product produced by a microorganism. The microorganisms of the present disclosure can be engineered to produce products at a particular selectivity or at a lowest selectivity. In one embodiment, the target product comprises at least about 5%, 10%, 15%, 20%, 30%, 50%, or 75% of the total fermentation product produced by a microorganism of the present disclosure. In one embodiment, the target product comprises at least 10% of the total fermentation product produced by the microorganism of the present disclosure, such that the selectivity for the target product by the microorganism of the present disclosure is at least 10%. In another embodiment, the target product comprises at least 30% of the total fermentation product produced by the microorganism of the present disclosure, such that the selectivity for the target product by the microorganism of the present disclosure is at least 30%.

The culture is typically maintained in an aqueous medium containing nutrients, vitamins and/or minerals sufficient to allow the growth of the microorganisms. Preferably, the aqueous medium is an anaerobic microorganism growth medium, such as a minimal anaerobic microorganism growth medium.

The cultivation/fermentation should ideally be carried out under suitable conditions to produce the desired product. Typically, the culturing/fermentation is performed under anaerobic conditions. Reaction conditions to be considered include pressure (or partial pressure), temperature, gas flow rate, liquid flow rate, medium pH, medium redox potential, agitation rate (if a continuously stirred tank reactor is used), inoculum level, maximum gas substrate concentration to ensure that the gas in the liquid phase does not become limiting, and maximum product concentration to avoid product inhibition. In particular, the rate of introduction of the substrate can be controlled to ensure that the concentration of gas in the liquid phase does not become limiting, since incubation under gas limiting conditions may consume product.

Operating the bioreactor at elevated pressure allows for increasing the rate of gas mass transfer from the gas phase to the liquid phase. Therefore, it is generally preferred that the cultivation/fermentation is carried out at a pressure higher than atmospheric pressure. In addition, since a given gas conversion is somewhat a function of substrate retention time and retention time is indicative of the required volume of the bioreactor, the use of a pressurized system can greatly reduce the volume of the required bioreactor and thus reduce the capital cost of the culture/fermentation equipment. This in turn means that the retention time, which is defined as the volume of liquid in the bioreactor divided by the input gas flow rate, can be shortened when the bioreactor is maintained at an elevated pressure rather than atmospheric pressure. The optimal reaction conditions will depend in part on the particular microorganism used. In general, however, it is preferred to carry out the fermentation at a pressure above atmospheric pressure. In addition, since a given gas conversion is somewhat a function of substrate retention time, and achieving a desired retention time in turn is indicative of the required volume of the bioreactor, the use of a pressurized system can greatly reduce the volume of the required bioreactor, and thus reduce the capital cost of the fermentation equipment.

The desired product can be isolated or purified from the fermentation broth using any suitable removal process, which can utilize methods or combinations of methods known in the art, including, for example, fractional distillation, vacuum distillation, evaporation, pervaporation, gas stripping, phase separation, and extractive fermentation (including, for example, liquid-liquid extraction). In certain embodiments, the target product is recovered from the fermentation broth by: continuously removing a portion of the fermentation broth from the bioreactor, separating the microbial cells from the fermentation broth, preferably by filtration, and recovering one or more target products from the fermentation broth. The alcohol and/or acetone may be recovered, for example, by distillation. The acid may be recovered, for example, by adsorption on activated carbon. The separated microbial cells may be returned to the bioreactor. The cell-free permeate remaining after the target product has been removed may also be returned to the bioreactor. Additional nutrients (such as vitamin B) may be added to the cell-free permeate to supplement the culture medium, which is then returned to the bioreactor.

The present disclosure shows that by integrating gasification and fermentation operations into an integrated system, unexpected synergy results in improved overall efficiency of the integrated system. More specifically, the present disclosure identifies such integration: wherein the off-gas of the fermentation operation is used to heat the drying gas which is then used to dry the feedstock of the gasification operation.

Off-gas from the fermentation process can be used to generate electricity or steam, but at best, the operator can recover about 60% of the off-gas energy, split to about 40% for electricity, and about 20% for steam. Surprisingly, contrary to the above, using the tail gas to dry the feedstock of the gasification operation, the operator can recover up to about 92% of the energy of the tail gas, because of the increased yield of syngas from the gasification operation.

It has previously been shown that drying the feedstock from 51.2% to 9.2% can increase the cold gas efficiency, i.e., the amount of syngas generated from gasifying the feedstock on an energy basis can be increased from 45% to 70%. Furthermore, the energy basis of the syngas produced is from 3.8MJ/Nm³Increased to 4.9MJ/Nm³Indicating fermentable substances (such as CO and H)₂) Will also increase. This has the added benefit of cost savings in downstream parts of the system, including compression and fermentation. For example, this reduces the specific energy use in downstream fermentation, where the rarer gases require the same compression and reactor volume to produce a smaller amount of ethanol product.

Furthermore, the present disclosure improves the yield and quality of syngas, which yields a greater economic return than using tail gas to generate steam or to generate electricity. More specifically, using the tail gas to dry the feedstock entering the gasifier results in more syngas being produced from the gasifier. Greater syngas production results in larger volumes and higher quality of fermentation process feed and, therefore, greater product production in the fermentation process. The value of the increased amount of product from the fermentation process exceeds the value of the electricity or steam that would be generated from the off-gas if it were not used in the drying operation.

The following table shows a comparison of expected revenue from using tail gas to dry the feedstock to the gasifier versus using the tail gas to generate electricity and steam. The comparison is based on: a gasifier of 41.7 tons/hour (TPH) and a raw gas fermentation unit of 1000 tons/day (TPD), and a raw energy density of 11 MJ/kg.

TABLE 1

Tail gas	50GJ/h
		Efficiency of the dryer	3 GJ/ton water
Removed water	6.7 ton/hr
		Initial water content of municipal solid waste	40％
Final water content of municipal solid waste	23％
		Expected improvement in syngas efficiency	Relative ratio is 16.7%
Expected increase in syngas production	45.9GJ/h
		An increase in ethanol production is expected	1.0 ton/hr
The price of ethanol is $ 1000/ton of tail gas value.	$20/GJ

TABLE 2

It is also noted that the tail gas may be too lean to be used to generate electricity, in which case the value of the feedstock for the dry gasifier becomes even greater.

Other embodiments include one or more effluents selected from the group consisting of: biogas generated by a wastewater treatment process, tail gas generated by a fermentation process, unused syngas generated by a gasification process, microbial biomass generated by a fermentation process, microbial biomass generated by a wastewater treatment process, raw ethanol from a product recovery process, fusel oil from a product recovery process, water depleted of microbial biomass, wastewater generated by a fermentation process, and clarified water from a wastewater treatment process, which effluents may be sent to a gasification process to produce a syngas stream, used by a gasification process as a heating source, and/or used by a gasification process to quench a syngas stream. The synthesis gas stream is preferably suitable for gas fermentation.

These various effluents are produced during or downstream of the fermentation process. The wastewater stream produced by the fermentation process contains organic metabolites such as microbial biomass, ethanol, acetate, and 2, 3-butanediol, as well as various inorganic compounds such as salts and trace metals. The wastewater stream is typically sent to a wastewater treatment process. A typical wastewater treatment process comprises the following steps: (i) isolating microbial biomass, which is a suspended solid; (ii) concentrating microbial biomass solids in a single long residence time (about thirty days) anaerobic digester; (iii)the clarified effluent containing soluble organics is concentrated in a short residence time (approximately two to three days) anaerobic digester where the amount of microbial biomass solids is reduced. Typically, these anaerobic digesters consume a majority, preferably greater than eighty percent (80%), of the organic matter in the feed and produce biogas products. Biogas products are composed primarily of methane (CH)₄) And carbon dioxide (CO)₂) And (4) forming.

The biogas product may be useful for generating power. However, in order to use the biogas for power generation, the biogas must typically be processed by one or more removal units. Furthermore, as explained later, it was found that the use of microbial biomass to produce biogas is a relatively low value use of microbial biomass when compared to the opportunity to gasify microbial biomass.

In addition to the aforementioned steps, the wastewater treatment process may include additional treatment steps after the anaerobic digester. Typically, the treated effluent from the anaerobic digester is subjected to additional treatments including aerobic treatment, struvite recovery, nitrogen recovery, and in some cases reverse osmosis. Clarified water produced by the wastewater treatment process is suitable for reuse and/or discharge. One suitable way of using such clarified water is to recycle the clarified water to the fermentation process and/or the gasification process.

Although wastewater treatment processes can successfully treat wastewater from fermentation processes to produce clarified water, organic metabolites in wastewater streams often present some challenges. In particular, treatment of microbial biomass in wastewater streams by wastewater treatment processes can present design challenges due to: (i) high protein content, thus generating large amounts of ammonia during anaerobic digestion, and (ii) requiring large bulk space to accommodate wastewater treatment processes.

Ammonia presents a challenge to anaerobic digestion because if the concentration of ammonia is high, ammonia is associated with inhibiting methanogenesis during the anaerobic digestion process. Inhibitory concentrations of ammonia have been found to be in the range of 2g/L to 3 g/L. This threshold may be greatly exceeded because digestion of the isolated microbial biomass may result in an ammonia concentration greater than 20 g/L. Therefore, in order to process microbial biomass by a wastewater treatment process, an ammonia stripping process is typically required to reduce the ammonia concentration below inhibitory levels.

The requirement for large plot space poses a significant problem in areas where land is scarce. Each component of the wastewater treatment process requires a large amount of space because of the large volume to be treated. For example, in some cases, a long residence time anaerobic digester may exceed 7,000m³。

The inventors have discovered that these challenges can be overcome by recycling at least a portion of the microbial biomass to the gasification process. As less microbial biomass is sent to anaerobic digestion, less ammonia is produced, thus reducing and/or eliminating the need for an ammonia stripping process. Furthermore, since a larger volume of effluent from the fermentation process is sent to the gasification process, a smaller volume of effluent is sent to the wastewater treatment process. Because of the smaller volume of effluent treated by the wastewater treatment process, the required volume and corresponding plot space requirements are reduced, making this design advantageous for areas where land is scarce.

In addition to overcoming the aforementioned challenges, recycling microbial biomass to the gasification process also provides the following advantageous results: (i) a large portion of the energy contained in the biomass is recovered; (ii) h in the resulting syngas stream₂The CO ratio is increased; (iii) the inorganic content, metallic compounds and alkali elements in the microbial biomass (which would normally require additional treatment steps of a wastewater treatment process) are conveniently collected in the gasification process as part of the ash that already needs to be disposed of, thus reducing overall waste disposal; and (iv) nitrogen contained in the biomass will react in the gasifier to N₂、NH₃And trace amounts of HCN, which is well integrated with existing removal processes.

The inventors have also surprisingly found that the yield in recycling biomass to gasification is increased when compared to using biomass in the production of biogas. In particular, the inventors have found that the gain is increased by 321% when comparing the utilization of biomass in syngas with the utilization of biomass in the production of biogas.

This percentage gain increase is best shown in the table below. Table 3 shows the values generated from 20GJ/h of biomass by each route.

TABLE 3

The calculations shown in the table above compare the conversion value of biomass to biogas via anaerobic digestion with the conversion value of biomass to syngas via gasification. The conversion efficiency for biogas production from biomass via anaerobic digestion is about sixty percent (60%). The conversion efficiency of syngas production from biomass via gasification is about seventy-five percent (75%), which may vary depending on the gasification technology used. GJ/h product gas represents GJ/h biomass multiplied by the corresponding conversion efficiency. GJ/h ethanol represents GJ/h product gas times the conversion efficiency of the gas fermentation. The conversion efficiency of gas fermentation for ethanol production is conservatively about fifty-five percent (55%). With this conversion efficiency, GJ/h ethanol was found to be 8.25. By 11 months and 5 days 2018, the current price of biogas without renewable incentives is between U.S. dollars ($4) and the european union $ ten ($ 10). For analytical purposes, a biogas price of eight dollars per gigajoule ($8/GJ product value) was used. By 11/5 days 2018, the price of low carbon ethanol is currently $ 850/ton ethanol in the european union, $ 1100/ton ethanol in china, and $ 1200/ton ethanol in the united states. For analytical purposes, a price of 1000 dollars/ton of ethanol was used, corresponding to $ 37.30/GJ. The $/h yield is GJ/h product gas multiplied by $/GJ product value. The percentage gain is a comparison of the $/h gain for anaerobic digestion to biogas versus the $/h gain for gasification to syngas. The GJ biomass value illustrates the value of the biomass given the selected process. This is calculated by dividing $/h yield by GJ/h biomass. As shown, the use of biomass to produce syngas through gasification greatly increases the revenue and value of the biomass.

An additional benefit of feeding microbial biomass to the gasification process is that the microbial biomass can help provide a supplemental amount of syngas, which may be needed to adequately supply the fermentation process. For example, based on current design parameters, a gasifier feed rate of about 1,200 dry tons per day, corresponding to 50 dry tons per hour, is required to supply the syngas required for a 100,000 ton/year ethanol production fermentation process. The biomass produced by fermentation processes of this scale is typically between 1,000kg/h and 1,200 kg/h. This amount of biomass is considerable. Where gasifier feedstock is limited or expensive, it may be particularly beneficial to generate make-up quantities of syngas by biomass gasification.

The biomass produced by the fermentation process may require an additional drying step before being passed to the gasifier in order to increase the percentage of biomass content. Depending on the requirements of the gasifier, it may be necessary to dry the biomass to an extent that the biomass constitutes more than 20% by weight.

However, gasifying biomass with increased moisture content has the effect of increasing the H in the syngas produced₂The additional benefit of the CO ratio. At a moisture content of about 15 wt% in the gasification feedstock, the resulting syngas stream has a H of 1:1₂The ratio of CO. When the moisture in the gasification feedstock increased to 40 wt.%, the resulting syngas stream had a H of 2:1₂The ratio of CO. As previously mentioned, H in the syngas stream fed to the fermentation process₂An increased CO ratio leads to an increased efficiency of the fermentation process.

To achieve the aforementioned benefits, the present disclosure recycles one or more of the following effluents selected from the group consisting of: biogas generated by a wastewater treatment process, tail gas generated by a fermentation process, unused syngas generated by a gasification process, microbial biomass generated by a fermentation process, microbial biomass generated by a wastewater treatment process, crude ethanol from a product recovery process, fusel oil from a product recovery process, water depleted of microbial biomass, wastewater generated by a fermentation process, and clarified water from a wastewater treatment process. One or more of these effluents may be sent to the gasification process to produce a syngas stream, used by the gasification process as a heating source, and/or used by the gasification process to quench the produced syngas. The synthesis gas stream is preferably suitable for gas fermentation.

Fig. 1 shows a process integration scheme according to one embodiment of the present disclosure, depicting the integration of a gasification process 300 (with a dryer 10), a gas fermentation process 100, a product recovery process 400, and a wastewater treatment process 200. These processes are integrated in a manner that provides surprising synergy and advantages. The gasification process 300 receives a gasification feed 301, which may be any suitable material that can be gasified to produce a syngas stream 302. In each case, the gasification feed 301 is at least partially composed of sorted and/or unsorted municipal solid waste. In other cases, the gasification feed 301 is at least partially composed of forest waste and/or agricultural waste. In each case, the gasification feed 301 is at least partially composed of industrial solid waste. In particular embodiments, the gasification feed 301 is comprised of one or a combination of two or more of the following: classified municipal solid waste, unclassified municipal solid waste, industrial solid waste, forest waste, agricultural waste, sludge derived from wastewater treatment, sewage, lignocellulosic material, microbial biomass, at least one effluent from fermentation process 100, at least one effluent from product recovery process 400, and at least one effluent from wastewater treatment process 200.

The gasification feed is dried in a dryer 10 as part of a gasification process 300 in a gasifier. The dryer 10 operates using a dryer gas, such as air, to dry the gasification feed. The dryer gas (such as air) is heated and, in one embodiment, contacted with the gasification feed to dry the gasification feed. It is contemplated that in other embodiments, the gasification feed may be heated without direct contact with the drying gas. The air or other drying gas may be heated by using a burner. The dryer gas in the dryer gas duct 8 can be in heat exchange communication with at least one burner. The fuel for the burner is provided by the exhaust gas in conduits 104, 124 and 125.

The gasification process 300 receives a gasification feed 301 and produces a syngas stream 302 suitable for fermentation by the gas fermentation process 100. The fermentation process 100 utilizes this stream as a carbon source to produce one or more products, which may be at least partially contained in one or more effluent streams 102, 104. In each case, the effluent from fermentation process 100 is a fermentation broth. One or more products produced by the fermentation process 100 are removed and/or separated from the fermentation broth by a product recovery process 400 in a product recovery unit. Preferably, the product recovery process 400 removes one or more products 406 and produces at least one effluent 402, 404, 408 comprising a reduced amount of the at least one product. The effluent may be sent to the wastewater treatment process 200 via conduit 402 to produce at least one effluent 202 in a recovery conduit, which may be recycled to the gasification process 300 and/or the fermentation process 100.

The effluent from the fermentation process 100 is the off-gas produced by the fermentation process 100. At least a portion of this tail gas is sent to the gasification process 300 via conduits 104, 124 and 125 and is used in the dryer 10 as fuel for the burner of the dryer 10 to heat the drying gas. In an optional embodiment, at least a portion of the tail gas may be sent to the gasification process 300 via conduit 124 for use as part of the gasification feed 301. In another optional embodiment, at least a portion of the tail gas may be sent to gasification process 300 via conduit 114 to quench syngas stream 302.

In at least one embodiment, the effluent from fermentation process 100 is a fermentation broth. At least a portion of the fermentation broth is sent to product recovery process 400 via conduit 102. In at least one embodiment, the product recovery process 400 separates at least a portion of the microbial biomass from the fermentation process 100. In various embodiments, at least a portion of the microbial biomass separated from the fermentation broth is recycled to the fermentation process 100 via conduit 404. In various embodiments, at least a portion of the microbial biomass separated from the fermentation broth is sent to gasification process 300 via conduit 428. At least a portion of the microbial biomass may be used as part of the gasification feed 301.

In various optional embodiments, at least a portion of the wastewater stream from the fermentation process 100 comprising fermentation broth (which may contain microbial biomass) may be sent directly to the gasification process 300 via conduit 104 without being passed to the product recovery process 400. At least a portion of the wastewater may be sent to the gasification process 300 via conduit 124 for use as part of the gasification feed 301. At least a portion of the fermentation broth may be sent to gasification process 300 via conduit 114 to quench syngas stream 302.

In the case of processing the fermentation broth by the product recovery process 400, at least a portion of the microbial biomass-depleted water produced by removing the microbial biomass from the fermentation broth may be returned to the fermentation process 100 via a conduit 404 and/or sent to the gasification process 300 via a conduit 408. At least a portion of the microbial biomass-depleted water may be sent to the gasification process 300 via conduit 428 for use as part of the gasification feed 301. At least a portion of the microbial biomass-depleted water can be sent via line 418 to quench the syngas stream 302. Further, at least a portion of the effluent from the product recovery process 400 can be sent to the wastewater treatment process 200 via conduit 402. Preferably, the effluent from the product recovery process 400 contains a reduced amount of product and/or microbial biomass.

Preferably, the wastewater treatment process 200 receives and processes effluent from one or more processes to produce clarified water. The clarified water may be sent to one or more processes via conduit 202. In some cases, at least a portion of the clarified water is sent to the fermentation process via conduit 212. At least a portion of the clarified water may be sent to the gasification process 300 through a conduit 232 for use as part of the gasification feed 301. At least a portion of the clarified water may be sent to gasification process 300 via conduit 222 to quench syngas stream 302.

In some cases, wastewater treatment process 200 generates microbial biomass as part of the treatment process. At least a portion of the microbial biomass may be sent to the gasification process 300 via conduit 232. Preferably, the gasification process 300 utilizes at least a portion of the microbial biomass generated by the wastewater treatment process 200 as part of the gasification feed 301.

The wastewater treatment process 200 produces biogas as a byproduct of the treatment of microbial biomass. At least a portion of the biogas may be sent to the gasification process 300 via conduit 202. In some cases, at least a portion of the biogas is sent to the gasification process 300 via conduit 232 for use as part of the gasification feed 301. At least a portion of the biogas may be sent to gasification process 300 via conduit 222 to quench syngas stream 302.

Preferably, the gasification process 300 receives one or more effluents from the fermentation process 100, the product recovery process 400, and/or the wastewater treatment process 200, and produces a syngas stream 302. The syngas stream 302 is preferably suitable for use as a feedstock to the gas fermentation process 100.

To be suitable as feedstock for the gas fermentation process 100, the syngas stream 302 should preferably have a desired composition. In particular instances, the syngas 302 produced by the gasification process 300 contains one or more components that need to be removed and/or converted.

Typical components found in syngas stream 302 that may need to be removed and/or converted include, but are not limited to, sulfur compounds, aromatics, alkynes, alkenes, alkanes, alkenes, nitrogen compounds, phosphorous compounds, particulates, solids, oxygen, halogenated compounds, silicon-containing compounds, carbonyl compounds, metals, alcohols, esters, ketones, peroxides, aldehydes, ethers, and tars. These components may be removed by one or more removal processes.

Fig. 2 illustrates the process integration scheme from fig. 1, further including a removal process 500 between the gasification process 300 and the gas fermentation process 100, according to one aspect of the present disclosure.

Preferably, the removal process 500 includes one or more of the following removal units: a hydrolysis unit, an acid gas removal unit, a deoxygenation unit, a catalytic hydrogenation unit, a particle removal unit, a chloride removal unit, a tar removal unit, and a hydrogen cyanide polishing unit.

When the removal process 500 is incorporated, at least a portion of the syngas 302 from the gasification process 300 is sent to the removal process 500 to remove and/or convert at least a portion of at least one component found in the syngas stream 302. Preferably, the removal process 500 leaves the components within allowable levels in order to produce a treated stream 502 suitable for fermentation by the fermentation process 100.

In various instances, the removal process 500 includes two or more removal units selected from the group consisting of: a hydrolysis unit, an acid gas removal unit, a deoxygenation unit, a catalytic hydrogenation unit, a particle removal unit, a chloride removal unit, a tar removal unit, and a hydrogen cyanide polishing unit. In certain instances, one or more of these removal units are used to remove one or more components from the gas stream that may adversely affect downstream processes (e.g., downstream fermentation process 100 and/or downstream removal units within removal process 500).

One or more components removed and/or converted by removal process 500 can be introduced and/or concentrated by gasification of the microbial biomass. In some cases, the removal process 500 removes ammonia (NH)₃) And/or Hydrogen Cyanide (HCN). When the microbial biomass is gasified by the gasification process 300, the ammonia and/or hydrogen cyanide may be introduced and/or concentrated. Ammonia and hydrogen cyanide may be produced from the nitrogen contained in the microbial biomass that will react in the gasification process 300 to become N₂、NH₃And trace amounts of HCN.

Typically, the syngas stream fed to the fermentation process 100 is gaseous. However, the syngas stream may also be provided in alternative forms. For example, the syngas stream can be dissolved in a liquid saturated with syngas, which can then be fed into the fermentation process 100. By way of further example, the syngas may be adsorbed onto a solid support.

Preferably, the fermentation process 100 utilizes C1 immobilized microorganisms to ferment the syngas stream 302 and produce one or more products. The C1-immobilized microorganisms in fermentation process 100 are typically carboxydotrophic bacteria. In a specific embodiment, the carboxydotrophic bacterium is selected from the group comprising: moorella, clostridium, ruminococcus, acetobacter, eubacterium, butyrobacter, acetobacter, methanosarcina, and devulcanium. In various embodiments, the carboxydotrophic bacterium is clostridium autoethanogenum.

In some cases, one or more of the processes are integrated by utilizing at least a portion of at least one effluent from one process as a heating source for at least one other process.

Fig. 3 illustrates a process integration scheme depicting integration of a gasification process 300, a gas fermentation process 100, a product recovery process 400, and a wastewater treatment process 200, according to one aspect of the present disclosure. In various instances, at least one process is integrated by utilizing at least one effluent from the process as a heating source in at least one other process. In particular embodiments, biogas generated by wastewater treatment process 200 is used as a heating source for one or more processes. Preferably, at least a portion of the biogas generated by the wastewater treatment process 200 is used as a heating source for the gasification process 300. In some cases, the gasification process 300 utilizes at least a portion of the biogas generated by the wastewater treatment process 200 to melt at least a portion of the slag produced by the gasification process 300. In one or more embodiments, at least a portion of the biogas generated by the wastewater treatment process 200 is used as a heating source for the gas fermentation process 100. In one or more embodiments, at least a portion of the biogas generated by the wastewater treatment process 200 is used as a heating source for the product recovery process 400. In one or more embodiments, at least a portion of the biogas generated by the wastewater treatment process 200 is used as a heating source for the removal process 500.

In each case, the biogas stream from the wastewater treatment process 200 is sent to at least one removal process 600 via conduit 202 before being sent to one or more processes. Preferably, the removal process 600 reduces the amount of at least one sulfur compound in the biogas stream.

When the removal process 600 is incorporated after the wastewater treatment process 200, at least a portion of the biogas from the wastewater treatment process 200 is sent to the removal process 600 to remove and/or convert at least a portion of at least one component found in the biogas stream of the biogas treatment unit. Preferably, the removal process 600 leaves the components within allowable levels in order to produce a treated stream 642, 612, 622, and/or 632 suitable for use by the subsequent one or more processes 400, 100, 500, and/or 300.

In particular embodiments, the off-gas generated by fermentation process 100 may also be used as a heating source for one or more processes. For example, at least a portion of the tail gas generated by the fermentation process 100 may be used as a heating source for the gasification process 300. In some cases, the gasification process 300 utilizes at least a portion of the tail gas generated by the fermentation process 100 to melt at least a portion of the slag produced by the gasification process 300. In one or more embodiments, at least a portion of the tail gas generated by the fermentation process 100 is used as a heating source for the product recovery process 400. In each case, off-gas from the fermentation process 100 is sent to at least one removal process before being sent to one or more processes.

In particular embodiments, unused syngas generated by the gasification process 300 is used as a heating source for one or more processes. Preferably, at least a portion of the unused syngas generated by the gasification process 300 is used as a heating source for the gasification process 300. In certain instances, the gasification process 300 utilizes at least a portion of the unused syngas generated by the gasification process 300 to melt at least a portion of the slag produced by the gasification process 300. In one or more embodiments, at least a portion of the unused syngas generated by the gasification process 300 is used as a heating source for the product recovery process 400. In each case, the unused syngas from the gasification process 300 is sent to at least one removal process before being sent to one or more processes.

The fermentation process 100 is preferably capable of producing a variety of products. These products can preferably be separated using the product recovery process 400. In various instances, at least a portion of at least one product produced by fermentation process 100 may be used as a source of one or more processes. In certain instances, at least a portion of the ethanol from the product recovery process 400 is used as a heating source for the gasification process 300. Preferably, the ethanol used as a heating source for one or more processes is caide ethanol that does not meet fuel-grade ethanol specification requirements. In certain instances, the gasification process 300 utilizes at least a portion of the caide ethanol from the product recovery process 400 to melt at least a portion of the slag produced by the gasification process 300.

In some cases, fermentation process 100 produces fusel oil. The fusel oil may be recovered by the product recovery process 400 by any suitable means. For example in the rectification column of a distillation apparatus. In at least one embodiment, at least a portion of the fusel oil from product recovery process 400 is used as a heating source for one or more processes. In some cases, at least a portion of the fusel oil from the product recovery process 400 is used as a heating source for the gasification process 300. Preferably, the gasification process 300 utilizes at least a portion of the fusel oil from the product recovery process 400 to melt at least a portion of the slag produced by the gasification process 300.

A first embodiment includes a method comprising: a) heating the drying gas; b) supplying the heated dry gas to a dryer containing the vaporized feedstock to produce a dried vaporized feedstock; c) gasifying at least a portion of the dried gasification feedstock to generate a syngas; d) fermenting at least a portion of the syngas in a bioreactor using a microorganism to produce at least one product and a tail gas; and e) using at least a portion of the tail gas to provide heat to heat the drying gas.

The process of the first embodiment may have the following gasification feedstocks: classified municipal solid waste, unclassified municipal solid waste, industrial solid waste, agricultural waste, forest waste, microbial biomass, lignocellulosic material, sewage, sludge from wastewater treatment, or any combination thereof.

The process of the first embodiment may be such that the tail gas comprises carbon dioxide. The tail gas may also comprise carbon monoxide, hydrogen, nitrogen and methane.

The method of the first embodiment may have the microorganism being one or more C1 immobilized microorganisms. The C1 immobilized microorganism can be selected from the group consisting of genus Moorella, genus Clostridium, genus Ruminococcus, genus Acetobacter, genus Eubacterium, genus Butyribacterium, genus Acetobacter, genus Methanosarcina, and genus Desulfotomatous.

The gasification feedstock may be the following microbial biomass: it may comprise one or more C1 immobilized microorganisms. The C1 immobilized microorganism can be selected from the group consisting of genus Moorella, genus Clostridium, genus Ruminococcus, genus Acetobacter, genus Eubacterium, genus Butyribacterium, genus Acetobacter, genus Methanosarcina, and genus Desulfotomatous. The gasification feedstock may be the following microbial biomass: which may come from a wastewater treatment plant.

The method of the first embodiment may have the drying gas be air.

The process of the first embodiment, wherein gasification results in a higher syngas yield as compared to gasification without drying the gasification feedstock.

The method of the first embodiment, wherein the gasification produces a higher syngas quality than gasification without drying the gasification feedstock.

The method of the first embodiment, wherein the tail gas is combusted to provide heat for heating the drying gas.

The process of the first embodiment wherein the off-gas is combusted in a burner to provide heat for heating the drying gas.

A second embodiment includes an apparatus comprising: a) a dryer having one or more burners for heating a drying gas, the dryer being in communication with the feedstock conduit; b) a vaporizer in communication with the dryer; c) a bioreactor in fluid communication with the gasifier; d) a product conduit and a tail gas conduit, the conduits being in fluid communication with the bioreactor; and e) the tail gas duct is also in fluid communication with one or more burners.

The apparatus of the second embodiment may further comprise a dryer gas conduit in communication with the dryer and capable of being in heat exchange communication with the at least one burner.

The apparatus of the second embodiment may further comprise a product recovery unit in fluid communication with the wastewater treatment unit and a first recycle conduit from the wastewater treatment unit to the dryer. The apparatus may further include a biogas processing unit in fluid communication with the first recirculation conduit.

The apparatus of the second embodiment may further comprise a second recycle conduit from the product recovery unit to the dryer.

The apparatus of the second embodiment may further comprise at least one removal unit in fluid communication with at least the gasifier and the bioreactor.

All references, including publications, patent applications, and patents, cited herein are hereby incorporated by reference to the same extent as if each reference were individually and specifically indicated to be incorporated by reference and were set forth in its entirety herein. The reference to any prior art in this specification is not, and should not be taken as, an acknowledgment or any form of suggestion that prior art forms part of the common general knowledge in the field of endeavour in any country.

The use of the terms "a" and "an" and "the" and similar referents in the context of describing the disclosure (especially in the context of the following claims) are to be construed to cover both the singular and the plural, unless otherwise indicated herein or clearly contradicted by context. The terms "comprising," "having," "including," and "containing" are to be construed as open-ended terms (e.g., meaning "including, but not limited to,") unless otherwise noted. The term "consisting essentially of … …" limits the scope of the composition, process or method to the specified materials or steps or to those materials or steps that do not materially affect the basic and novel characteristics of the composition, process or method. The use of alternatives (e.g., "or") should be understood to mean one, both, or any combination thereof of alternatives. As used herein, the term "about" means ± 20% of the indicated range, value, or structure, unless otherwise indicated.

Recitation of ranges of values herein are merely intended to serve as a shorthand method of referring individually to each separate value falling within the range, unless otherwise indicated herein, and each separate value is incorporated into the specification as if it were individually recited herein. For example, unless otherwise specified, any concentration range, percentage range, ratio range, integer range, size range, or thickness range should be understood to include the value of any integer within the stated range, and, where appropriate, to include fractions thereof (such as tenths and hundredths of integers).

All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g., "such as") provided herein, is intended merely to better illuminate the disclosure and does not pose a limitation on the scope of the disclosure unless otherwise claimed. No language in the specification should be construed as indicating any non-claimed element as essential to the practice of the disclosure.

Embodiments of the present disclosure are described herein. Variations of those embodiments may become apparent to those of ordinary skill in the art upon reading the foregoing description. The inventors expect skilled artisans to employ such variations as appropriate, and the inventors intend for the disclosure to be practiced otherwise than as specifically described herein. Accordingly, this disclosure includes all modifications and equivalents of the subject matter recited in the claims appended hereto as permitted by applicable law. Moreover, any combination of the above-described elements in all possible variations thereof is encompassed by the disclosure unless otherwise indicated herein or otherwise clearly contradicted by context.