Classifications

• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
  • C12P7/06—Ethanol, i.e. non-beverage
  • C12P7/065—Ethanol, i.e. non-beverage with microorganisms other than yeasts
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • 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
  • C12M21/00—Bioreactors or fermenters specially adapted for specific uses
  • C12M21/12—Bioreactors or fermenters specially adapted for specific uses for producing fuels or solvents
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • 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
  • C12M25/00—Means for supporting, enclosing or fixing the microorganisms, e.g. immunocoatings
  • C12M25/16—Particles; Beads; Granular material; Encapsulation
  • C12M25/18—Fixed or packed bed
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
  • C12N11/02—Enzymes or microbial cells immobilised on or in an organic carrier
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12N—MICROORGANISMS OR ENZYMES; COMPOSITIONS THEREOF; PROPAGATING, PRESERVING, OR MAINTAINING MICROORGANISMS; MUTATION OR GENETIC ENGINEERING; CULTURE MEDIA
  • C12N11/00—Carrier-bound or immobilised enzymes; Carrier-bound or immobilised microbial cells; Preparation thereof
  • C12N11/02—Enzymes or microbial cells immobilised on or in an organic carrier
  • C12N11/08—Enzymes or microbial cells immobilised on or in an organic carrier the carrier being a synthetic polymer
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12P—FERMENTATION OR ENZYME-USING PROCESSES TO SYNTHESISE A DESIRED CHEMICAL COMPOUND OR COMPOSITION OR TO SEPARATE OPTICAL ISOMERS FROM A RACEMIC MIXTURE
  • C12P7/00—Preparation of oxygen-containing organic compounds
  • C12P7/02—Preparation of oxygen-containing organic compounds containing a hydroxy group
  • C12P7/04—Preparation of oxygen-containing organic compounds containing a hydroxy group acyclic
  • C12P7/16—Butanols
• • C—CHEMISTRY; METALLURGY
  • C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
  • C12R—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES C12C - C12Q, RELATING TO MICROORGANISMS
  • C12R2001/00—Microorganisms ; Processes using microorganisms
  • C12R2001/01—Bacteria or Actinomycetales ; using bacteria or Actinomycetales
  • C12R2001/145—Clostridium
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E50/00—Technologies for the production of fuel of non-fossil origin
  • Y02E50/10—Biofuels, e.g. bio-diesel

Definitions

• the present invention relates to a process for the production of alcohols by fermentation of a sugary fluid.
• Alcohols derived from fermentation processes are among the most promising substitutes for petrochemical derivatives.
• ABE Acetone - Butanol - Ethanol
• IBE Isopropanol - Butanol - Ethanol
• IBE Isopropanol - Butanol - Ethanol
• a continuous process with cells in suspension in a homogeneous reactor can also be envisaged. But the productivity is also quite low and can hardly be increased significantly.
• a technical problem is the concentration of cells in the fermentation medium, mainly controlled by the dilution rate applied in the process. This cannot be raised to avoid cell washing (“wash out” according to Anglo-Saxon terminology) in the fermenter. For these reasons, in recent years, a strong interest has been shown in methods aimed at a strong retention of the microbial biomass. There are two ways: "cell immobilization” and cellular "recycling” with a retention by means of membrane filters. The present invention will mainly concern the technique of immobilizing cells.
• the immobilized cells are typically surrounded by polysaccharides excreted by the microorganisms (EPS: “Extracellular Polymeric Substances” according to the Anglo-Saxon terminology), and present different growth and bioactivity regimes from those obtained when the cells are in suspension (see, for example, Halan B., Buehler K., Schmid A., 2012, Biofilms as living catalysts in continuous chemical syntheses, Trends in biotechnol., 30 (9), 453-465).
• EPS Extracellular Polymeric Substances
• the microorganisms are introduced inside a porous matrix, so as to avoid their diffusion towards the external environment, while allowing the transfer of material for carrier and nutrients, as well as reaction products.
• supports using the encapsulation confinement technique include alginate beads (see, for example, Mollah AH, Stuckey DC, 1993, Maximizing the production of acetone-butanol in alginate bead fluidized bed reactor using Clostridium acetobutylicum, J. Chem. Tech.
• Patent FR-3 086 670 has also proposed a process in which at least part of the bacterial biomass is fixed in the fermentation reactor by adsorption in the form of a biofilm on a porous material based on polymeric foam, polyurethane foam type.
• This material has proven to be particularly efficient, allowing a continuous fermentation process, the foam making it possible to fix the bacteria in a sufficiently significant way, that is to say beyond the dilution rate causing cell washing.
• This material opens a new way for the production of IBEA-type mixtures, by also giving access to a production in continuous mode by immobilization of the bacterial biomass.
• Patent FR-3 086 553 proposes a process for cleaning this polyurethane foam, consisting in bringing the foam into contact with a fluid resulting from a fermentation must enriched with alcohol and/or acetone and/or a solution aqueous at basic pH. It is thus possible, once the polymeric foam is "worn out", in particular clogged and/or saturated with biomass, to regenerate it by cleaning in order to reuse it in a fermentation reactor with performances identical to or close to those of a new foam.
• the invention therefore aims to improve continuous fermentation processes, of the type of those producing mixtures of ABE or IBE alcohols, in particular with a view to improving their productivity.
• the subject of the invention is first of all a process for the production of alcohols, according to which a sugary fluid is introduced into a reaction section comprising a support on which microorganisms are immobilized, in order to produce by fermentation a wort enriched in alcohols under the action of said microorganisms, such that the method is operated continuously, and such that periodically (only) a portion of worn support is replaced by a portion of new and/or regenerated support.
• a "worn" support is understood to mean a support whose performance is reduced compared to a new support, in particular by reaching a given clogging/saturation-threshold level, or by reaching a lifespan in production given. The medium will generally be all the more worn the more it is “old”, that is to say that it has been used for a certain time since the start at a given instant of a production campaign.
• “regenerated” support means a worn support which has been treated/cleaned to once again achieve performance close to or identical to a “new” support.
• new support means a support which has never been used in production, and which has therefore not yet been colonized by microorganisms.
• the invention therefore relates to continuous fermentation processes, with a support immobilizing the microorganisms in a fermentation reactor.
• these supports a bit like catalysts in the field of chemistry, are gradually deactivated:
• the support is colonized with micro-organisms (bacteria) at the start, then the support is loaded with bacteria over time. This accumulation is beneficial for a certain period of time, since it increases the concentration of bacterial biomass, and it therefore increases the volume productivity of the fermentation reactor.
• the support is largely colonized by bacteria, and clogging phenomena appear: when the support material is in the form of blocks or particles, clogging can be observed between the particles/blocks and/or within the particles/blocks themselves when their material is porous, which then causes production to drop.
• the death of cells in the biofilm must be taken into account, the wear observed being therefore the conjunction of increasing clogging phenomena and the increasing death of bacteria over time.
• the solution proposed by the invention is to use a support which can be replaced progressively, each time replacing a portion of the support with a new/regenerated portion.
• the support is thus partially renewed: the portion of new or regenerated support which is introduced is gradually colonized in turn by the bacteria, and becomes progressively more effective than the worn portion which has been withdrawn.
• the support maintains sufficient overall efficiency throughout the production campaign, with portions of support that have different “ages”. (We understand by "age” the time spent, at time t, by a portion of support in production since the beginning of a production campaign): the most worn/aged portions of the support are gradually replaced in order to replace them with new/regenerated portions, thus maintaining an average "age", average wear, globally unchanged for the support.
• the microorganisms are, according to the invention, immobilized on the support in the form of biofilms or aggregates on/in the support, chosen preferably porous.
• the support comprises a plurality of support portions arranged successively in a general direction of flow of the (sweet) fluid in the reaction section, and said portions have a decreasing degree of wear from upstream to downstream ( relative to this direction of flow). It is indeed the most upstream portion in relation to the flow of sugary juice which tends to be loaded first with bacteria, which will therefore wear out more than the following ones. According to the invention, this fact is therefore exploited to cause a controlled partial rejuvenation of the support.
• the portion of worn support which is the most upstream in the support is replaced by the portion of new or regenerated support which is arranged downstream of the most downstream portion of the support.
• the support preferably comprises blocks of porous material in bulk, which are, in the reaction zone in production, immersed in a liquid reaction medium bathing said reaction section. These blocks are preferably held in the reaction section by mechanical devices, which are mesh, such as grids, nets, plates provided with orifices, and/or in the form of deflectors.
• the support may preferably be in a material of the foam type, either based on a polymer, of the polyurethane (PU) foam type, or based on a ceramic material.
• PU polyurethane
• Their behavior in a liquid (aqueous) medium will depend on their density; the type/conformation of the mechanical devices holding them in the reaction section will be chosen accordingly.
• the reaction section comprises a reactor
• the support comprises a plurality of layers, successively traversed by the sugary fluid, the portion of spent support and the portion of new and/or regenerated support each corresponding to a layer or a set of adjacent layers of the support.
• the term "layers" is not to be understood in the literal sense as layers which would be perfectly delimited with respect to each other. to the others, continuous and with a planar interface, or which would be perfectly stacked: these layers of material can have irregular, non-planar interfaces, even if they share the support in portions which are approximately of the same height and/or which contain approximately the same amount of porous material. It is for the sake of clarity that the support is represented in the form of a stack of these "layers".
• the spent support portion and the new and/or regenerated support portion each correspond to a layer of the support, the spent support portion withdrawn from the reactor being the most upstream layer of the support and the support portion new or regenerated being introduced into the reactor downstream of the most downstream layer of the support.
• upstream and downstream are understood according to the general direction of flow of the (sweet) fluid in the reaction section, here the reactor, through the support.
• the portion/layer of new or regenerated support is introduced in the form of blocks of bulk material, into the reactor, in solid form, in particular by pneumatic means or mechanical means such as an endless screw.
• the portion/layer of new or regenerated support is introduced in the form of blocks of bulk material, into the reactor, a liquid phase, in particular in suspension in the sugary fluid supplying the reaction section.
• the worn portion/layer of the support is withdrawn from the reactor in the liquid phase. It can in particular be drawn off in suspension in the liquid phase of the fermentation broth leaving the reactor.
• the withdrawal of the portion/layer of worn substrate at one of the ends of the substrate and its replacement by a portion/layer of new/regenerated substrate at its opposite end is carried out counter- current in relation to the direction of circulation of the fluid (sweet) in the reaction section.
• counter-current since the fluid flows from upstream to downstream, by definition according to the conventions of the present invention, in the reaction section, while we come to extract from the support by the upstream and we complete it downstream. This is the wisest mode of operation because, as explained above, it is generally the most upstream portion of the support that tends to load up the most/quickly with bacteria.
• ends are understood to mean the ends (upstream/downstream) of the support relative to the overall direction of flow of the fluid in the reactor in operation.
• the sugary fluid passes through the support on which the microorganisms are immobilized according to a general direction of flow in the reaction section comprising a reactor, the portion of spent support is withdrawn from the reactor, and the portion of new or regenerated support, the spent support portion being withdrawn from the reactor in the most upstream part of the support and the new or regenerated support portion being introduced into the reactor in the most downstream part of the support.
• the portion of spent support that is preferred to be withdrawn from the reactor is the most upstream portion of the support, which is also, generally, its most worn portion. And we prefer to add the portion of new/regenerated support downstream, to take over from the less worn downstream portion: We therefore do not come to replace a portion of support at the same place, we extract a portion of support from one of its ends (the upstream end), and another is added to the other of its ends (the downstream end): We create, or at least intensify, thus creating a "gradient" of degree of aging of the support along the direction of flow of the sugary fluid passing through it, the portions/layers of support being all the more worn as they are located upstream of the support. With this periodic replacement, an “average” level of aging of the support is kept substantially constant, and it is possible to extend the durations of the production campaign and/or make the durations of the iso-duration campaign more productive.
• This first embodiment can be implemented in two different ways, with a reactor oriented essentially along a vertical axis: - either with circulation of the sugary fluid in the reactor from top to bottom, the support extending over at least one part of the height of the useful volume of the reactor, the portion of used support being withdrawn from the reactor in the highest part of the support, and the portion of new or regenerated support being introduced into the reactor in the lowest part of the support,
• the support extending over at least part of the height of the working volume of the reactor, the portion of spent support being withdrawn from the reactor in the lowest part of the support and the portion of new or regenerated support being introduced into the reactor in the highest part of the support.
• the support material will preferably be of low density (PU foam) if a top-down fluid flow in the reactor is chosen, and that it will preferably be of higher density (ceramic foam) if we choose a bottom-up flow.
• the reaction section comprises a series of n reactors fluidly connected in series to each other, and at least one spare reactor.
• the support is then distributed between the n reactors in the form of n support portions, and a portion of the worn support is periodically replaced by a new or regenerated support portion by disconnecting a reactor belonging to the series of n reactors in series and containing the used support portion and connecting the spare reactor containing a new or regenerated support portion to the series of n-1 reactors.
• the reactor that is disconnected is the most upstream reactor with respect to the general direction of flow of the sugary fluid through the series of n reactors, and the spare reactor that is connected is placed downstream of the reactor the further downstream in the series with respect to said direction of flow.
• various treatments are carried out, generally including emptying, and at least one treatment operation for the spent support.
• This treatment may consist of cleaning, of the cleaning type with a view to regenerating it, for example according to the procedure described in the aforementioned patent FR-3,086,553, or may consist of replacing it with a new support.
• the treatment can be continued by sterilization, in order to store it as a spare reactor.
• the reaction section comprises at least one reactor which is provided with a fluid recirculation loop, and this regardless of the embodiment of the invention (independent reactors or mounted in series).
• the reaction section comprises at least one reactor equipped with mechanical stirring means. The recirculation loop and/or mechanical agitation ensure mixing in the reactor which is equipped with it, and homogenizes the content.
• the portion of the worn support and the portion of new or regenerated support which replaces it preferably have the same dimensioning.
• the overall support is thus kept at a constant size.
• the porous support may have a certain buoyancy, in particular when it is in the form of bulk blocks of polyurethane-type polymer foam, which means that if a portion of support is drawn off at one end of the support and add another at the other end (in the case of the first embodiment in particular), with suitable methods of fixing/maintaining the support, after stabilization of the positioning of the portions, the support remains globally in the same place, at the same "height in the reactor (if we take the example of a vertically oriented reactor).
• the periodic replacement of the portion of spent support by a portion of new and/or regenerated support can be done by withdrawing the portion of spent support from the reaction section and introducing the portion of new and/or regenerated support in the reaction section concurrently, or one after the other.
• the portion of new and/or regenerated support is sterilized before introduction into the reaction section.
• the periodic replacement of the portion of worn support by the portion of new or regenerated support is done with constant time intervals, or increasing, or decreasing with time, or according to time intervals controlled according to a measurement or an evaluation of the degree of wear of the support.
• the degree of wear can be evaluated according to different indicators: in particular the measurement or evaluation of the drop in production performance, the evolution of the pH, the measurement or evaluation of the evolution of the ratio between the different fermentation products.
• the process continues, preferably, to produce during the periodic replacement of a portion of worn support by a portion of new or regenerated support:
• this continuous replacement is facilitated if, as already mentioned, the new support is introduced with the sugar flow supply and the worn support is withdrawn with the flow of products leaving the reactor,
• the replacement of one reactor by another can induce a short interruption of production, the time to disconnect one reactor and reconnect the other.
• this partial support replacement leads to a better smoothing of the production.
• the invention in its preferred application, aims to produce a fermentation must comprising isopropanol, butanol and ethanol, the microorganisms being derived from a strain belonging to the genus Clostridium. Preferably, they are supported by a porous support of the foam type based on polymer material, such as polyurethane, or ceramic materials.
• the method according to the present invention relates to the production of a mixture of alcohols of the ABE or IBE or IBEA type, method according to which a sugary fluid is introduced into a reaction section comprising a support made of material porous solid on which microorganisms of the genus Clostridium are immobilized, said support comprising a plurality of portions or layers of bulk porous solid material, which are arranged successively in a general direction of flow of said sugary fluid.
• This preferred embodiment also relates to the reaction section thus equipped with a support.
• FIG. 1 represents an example of a method according to the first embodiment of the invention.
• Figure 2 shows a method according to another example of a method according to the first embodiment of the invention shown in Figure 1.
• Figure 3 shows a variant of the method shown in Figure 1.
• Figure 4 shows a variant of the method shown in Figure 1.
• FIG. 5 represents a method according to a second embodiment of the invention, in the production phase.
• FIG. 6 represents the method according to the second embodiment of the invention according to FIG. 5, during the phase of partial replacement of the support of the microorganisms.
• FIGS. 1 to 4 A first embodiment is described with the aid of FIGS. 1 to 4.
• 1 to 4 are identical except for differently configured fluid inlets/outlets.
• These are conventional fermentation reactors, essentially cylindrical in shape oriented along a vertical axis.
• the sugary fluid 2 comprises C5 and/or C6 sugars in the aqueous phase.
• the fermentation must (which can also be called fermentation juice or wine or fermentation products) 3 is enriched in isopropanol, butanol, ethanol and acetone compared to the sugary fluid 2 by conversion of sugars into alcohol/solvent under the action of a microorganism deposited on the solid support 4 contained in the reactor 1.
• This support 4 comprises a polyurethane foam, which plays the role of a moving bed in the reactor 1 in the form of blocks arranged in bulk and retained by systems of grids/nets not shown which hold them in place over a certain height in the reactor, like a fixed bed. (Alternatively, the foam blocks can be arranged in a structured fashion, not loose).
• the microorganism colonizing the support is of the Clostridium type.
• the fermentation step in the fermentation reactor 1 can be carried out at a temperature of between 28°C and 40°C, preferably between 30°C and 37°C, so that the fermentation must 3,3' comprises products of the IBEA type fermentation reaction, for example isopropanol, which is then evacuated from the reactor.
• the fermentation must 3 (steps not shown) is treated, in particular with one or more successive separation-type steps: it is for example introduced into a separation unit making it possible to separate and extract the compounds of interest from the must of fermentation, the latter being evacuated to be transformed or valued as such.
• the separation residues commonly called vinasses, are evacuated from the separation unit, they are generally composed of water as well as any liquid or solid product not converted or not extracted during the previous stages.
• the separation unit can implement one or more distillations, and optionally a separation of solid and/or suspended matter, for example by centrifugation, decantation and/or filtration.
• support 4 is therefore used to immobilize microorganisms (hereinafter also referred to by the terms bacteria or bacterial biomass), and to promote their growth by adsorption on solid support 4 directly in fermentation reactor 1.
• This immobilization/adsorption step can also be carried out indirectly, in a secondary tank, not shown (optional), operating for example in “in stream” mode with respect to the fermentation reactor 1:
• the solid support 4, once loaded with bacterial biomass is then introduced into the fermentation reactor 1.
• the solid support 4 is partially or, preferably, totally immersed, when the reactor 1 is in operation, in particular to increase the formation of biofilms and improve the performance.
• the solid support has a shape suitable for implementing the method of the invention, that is to say it consists of a plurality of layers stacked on top of each other along the vertical axis of the reactor, which is also the general flow axis of the fluid passing through the reactor.
• the layers are designed to be able to be removed/added in the reactor independently of the others.
• FIGS. 1 and 2 five layers 41 to 45 have been shown, all of the same size, in particular of the same height measured along the vertical axis, and all contiguous.
• the invention adapting the size and the number of layers depending, in particular on the dimensioning of the reactor, and the layers can be superimposed on each other without necessarily being in contact with each other, a space that can be provided between two consecutive layers of the stack.
• the support 4 here consists of a stack of loose foam blocks.
• the "layers” are therefore not to be understood in the literal sense, do not have a flat interface, make it possible to "cut” the support into portions of approximately the same size, here of the same height or, which comes to the same thing, in portions containing the same quantity of foam, these portions being “stacked” along the longitudinal axis, here the vertical axis, of the reactor.
• the foam blocks can be in the form of cubes or parallelepipeds or other elements of any three-dimensional shape.
• the net or the container with grid-like mesh 10 can define a cylindrical type shape whose diameter is less than or substantially equal to the internal diameter of the fermentation reactor 1. More generally, the layers can have a section of the same geometric shape ( circular or not) and slightly lower than that of the reactor, whether cylindrical or not. Within each layer, the particles or blocks of foam can move, they are mobile but contained by the net/grid type container(s).
• the layers of solid support 41 to 45 are preferably centered with respect to the internal walls of the fermentation reactor 1.
• they do not disturb the circulation of the liquid at the inlet and at the outlet of the reactor, in particular when it is operated continuously.
• the possible presence of insolubles such as those from major cereals does not pose a problem.
• the flow of sugary fluid arriving via conduit 1 can also be introduced in line with the solid support layers 4, for example when the first layer or layers are flush with the surface of the reaction medium of the fermentation reactor 1.
• the solid support is flush at the surface of the reaction medium at the inlet of the sugary fluid, the medium is locally less concentrated in alcohol and the growth of bacteria is favored.
• the different layers 41 to 45 are represented symbolically with a shade of gray that is all the stronger as the foam they contain is worn, that is to say that the foam has a higher "age" in the campaign of reactor output.
• the process according to the invention consists in replacing the most worn layer 41 (the most upstream) by extracting it from the reactor (arrow 5), then replacing it with a new or regenerated layer 46 (arrow 6).
• This layer has been represented symbolically in the figure before its introduction into the reactor, insofar as preference is given to adding the support in the form of bulk foam blocks: before introduction, the support can be stored and transported to to the reactor in a container of any shape, of course).
• the height of the support 4 in the reactor after this replacement remains unchanged.
• layer 42 becomes the oldest/worn layer in the layer stack, and layer 46 becomes the "youngest".
• This layer is preferably bare, it contains only polyurethane foam, and it will gradually become activated by bacterial contamination from the other layers and also develop biofilms on the surface of the foam.
• the replacement can be done by dedicated inlets/outlets made in the side wall of the reactor:
• a dedicated outlet can be provided, the evacuated foam then being separated from the fluid it has entrained, the fluid possibly being reinjected into the reactor.
• pneumatic or mechanical means of the endless screw type can be used.
• this counter-current system (between the circulation of the fluid in the reactor and the change of partial support) is very interesting because it makes it possible to maintain the productivity almost constant over time during the production campaign, and to increase the time of use of the reactor (or to keep it constant with better productivity).
• deflectors 8 in the form of grids, perforated plates, solid plates or equivalent means, which are arranged alternately, in staircase, on the height of the support, the spacing between two successive deflectors measured according to the height of the reactor, defining the height of a support layer within the meaning of the invention.
• mechanical means are used to identify the layers and to direct the path of the fluid through the support 4 (in particular in the case of solid, non-perforated plates).
• the sugary fluid is introduced into the lower part of the reactor by a sugary fluid supply inlet, which is also used to periodically introduce new foam.
• a sugary fluid supply inlet which is also used to periodically introduce new foam.
• blocks of foam in suspension to the sugary fluid.
• the foam is added to the sugary fluid upstream, prior to its introduction into the reactor, or the sugary fluid and the foam are jointly introduced directly into the reactor feed inlet.
• a controlled portion of foam is withdrawn with the must 3 through the must withdrawal outlet, for example by providing the outlet with a grid sized to retain the foam blocks, grid which is removed while the spent foam is drawn off.
• FIGS. 5 and 6 A series of three fermentation reactors 31, 32, 33 connected in series with the appropriate fluid connections are used.
• the series of reactors can include more reactors.
• the reactors, all identical, are of the cylindrical type and oriented vertically. Here they are all downflow.
• the sugary fluid 2 is introduced into the upper part of the first reactor 31, the most upstream in the series of three.
• the fermentation must 3 comes out in the lower part of the last reactor 33 of the series, the furthest downstream.
• a fourth reactor 34 identical to the other three, is the spare, inactive reactor.
• All four reactors are provided with a support 4 consisting of blocks of polyurethane foam as previously, held in position in each of the reactors by a container of the net or grid type(s).
• the supports 4 of the reactors have different ages, the more they are arranged in an upstream reactor, the older/worn they are.
• the reactor support 31 has, for example, 1500 hours of operation in production
• the reactor support 32 has 1000 hours of operation
• the reactor support 33 has only 500 hours of operation. Every 500 hours, we will disconnect the reactor with the most worn support, here reactor 31 therefore, from the rest of the series of reactors, and connect, downstream of the downstream reactor 33 the spare reactor 34.
• the sugary fluid is redirected to the inlet in the upper part of the reactor 32, and the wort leaving the reactor 33 is redirected to the inlet in the upper part of the reactor 34, from which the final must emerges in the lower part.
• the reactor 31 which has been disconnected is drained and cleaned. Its aged support 4 is replaced by a support with new and/or regenerated foam. It is then sterilized and put on hold, to constitute a spare reactor. You can always operate with a spare reactor ready, and at least one disconnected reactor being cleaned/prepared.
• the colonization of the newly used reactor 34 is favored by the arrival of liquid heavily loaded with biomass coming from the previous reactors.
• Each reactor can have its own recirculation loop (not shown).
• Several series of reactors can be used in parallel, for a common collection of fermentation musts in order to pool their treatment.
• the sweet fluid is the sweet fluid
• the sugary fluid comprises an aqueous solution of sugars derived from C5 and/or C6 lignocellulose, and/or sugars derived from sacchariferous plants (for example glucose, fructose and sucrose), and/or sugars from starchy plants (for example dextrins, maltose and other oligomers, or even starch).
• the aqueous solution of C5 and/or C6 sugars comes from the treatment of a renewable source.
• the renewable source is of the lignocellulosic biomass type which may in particular comprise ligneous substrates (for example leafy and resinous trees), agricultural by-products (for example straw) or those of industrial generators of lignocellulosic waste (from food industries, paper mills).
• the renewable source can also come from sugar plants, such as for example sugar beet and sugar cane or even starchy plants such as corn and wheat.
• the aqueous solution of C5 and/or C6 sugars can also come from a mixture of different renewable sources.
• the bacterial biomass is mainly adsorbed in the form of a biofilm on a support solid.
• the bacteria are strains belonging to the species Clostridium beijerinckii and/or Clostridium acetobutylicum.
• the bacteria used in the process can be genetically modified strains or not and naturally producing isopropanol and/or strains of Clostridium naturally producing acetone genetically modified to make them produce isopropanol. In the following examples, it is Clostridium beijerinckii DSM 6423.
• the solid backing includes polyurethane foam.
• Polyurethane foam is particularly advantageous because it not only gives access to the production of IBEA type mixtures, but it also gives access to the production of the continuous type by immobilization of the bacterial biomass.
• the polyurethane foam is capable of fixing bacteria of the genus Clostridium in a sufficiently significant way (/.e., beyond the dilution rate causing the cell washing) allowing the continuous production of mixtures of the IBEA type.
• polyurethane foam is suitable for being immobilized by immersion in a reactor.
• a foam based on ceramic material(s) can be used.
• the polyurethane foam has:
• volume cavities /.e., pores or cells whose equivalent sphere diameter is between 0.1 and 5 mm, preferably between 0.25 mm and 1.1 mm, preferably between 0.55 and 0.99mm, and/or
• 10 and 90 g/L preferably between 10 and 80 g/L, preferably between 15 and 45 g/L, such as between 20 and 45 g/L or between 25 and 45 g/L.
• the solid support comprises a net or a container with mesh comprising cubes or parallelepipeds or other elements of any shape in 3 dimensions (polyhedrons) of large or small size (at least one dimension between 3 mm and 10 m, such as from 2 cm to 1 m), and the net or the container with mesh forming a cylinder whose diameter is less than or substantially equal to the internal diameter of the fermentation reactor 1.
• the temperature in the reactor(s) is between 28°C and 40°C, preferably between 30°C and 37°C, in particular here 36°C
• the pressure in the reactor(s) is substantially atmospheric pressure (plus the height of water in the reactor(s))
• the sugary fluid concentration is between 65 and 35 g/L, preferably between 40 and 60 g/L, and in particular here 44 g/L (aqueous medium)
• the reactor(s) are operated continuously, with imposed dilution rates
• the targeted fermentation yield is between 0.28 and 0.34 g of IBEA product/g of sugar used, and in particular here of 0.31 g of IBEA product/g of sugar used.
• the microorganism is Clostridium beijerinckii DSM 6423
• the porous support 4 is PU foam in the form of small loose parallelepipeds of dimensions 20 mm x 20 mm x 7 mm. (but as indicated above, may have other dimensions, for example smaller such as: 5 mm x 5 mm x 3 mm or 10mm x 10mm x 7 mm, or larger)
• the 8 fermentation reactors are filled with solid support 4 and each operate for a given production campaign, here of 1500 hours. Then they are all drained, cleaned, sterilized. They are then filled again with support for a new production campaign of 1500 hours.
• the reactors are sequenced (they are made to operate in a time-shifted manner) so as to have globally continuous production downstream.
• Buffer tanks are also provided downstream of the reactors to smooth the flow rates for the downstream section.
• the time needed to empty/clean/sterilize/refill a reactor is 150 hours.
• Each reactor operates for 1500 hours, according to the productivity profile described above. This profile is equivalent to a constant apparent productivity of 1.67 g/L.h over 1500 h.
• a reactor For 150 hours plus 1500 hours, i.e. a total of 1650 hours, a reactor produces the following quantity P1 of alcohols:
• a reactor performs for one year, i.e. 8000 hours, 8000/1650 production cycles, i.e. 4.85 cycles, and thus produces 4850 tons of alcohol.
• This profile is equivalent to a constant apparent productivity p of 1.90 g/L.h over 5000 h.
• a reactor operates for one year, i.e. 8000 hours, 8000/5150 or 1.56 production cycles, and thus produces 5903 tonnes of alcohol.
• the time needed to empty/clean/sterilize/refill a reactor is 150 hours.
• a reactor performs for one year, ie 8000 hours, 8000/1500 production cycles, ie 5.33 cycles.
• Each of the 8 reactors R1 to R8 has a different age T according to table 1 below, "0" meaning in "cleaning” etc.:
• Each of the 8 reactors has a different productivity p, according to Table 2 below:
• the first mode is the most economical to implement, and the one that offers the greatest increase in production, the second mode being, for its part, a industrial implementation probably easier.

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