Method for treating a lignocellulosic biomass

Abstract

The invention relates to a method for treating a lignocellulosic biomass, with a) an optional step of impregnating the biomass (1), b) a step of cooking (3) the biomass (1) in the presence of water vapor (2) in order to obtain a mixture comprising the biomass (5) and water vapor (4a), c) a separation step in order to obtain the pretreated biomass (5) and the water vapor (4a), d) a step of condensing (17) the water vapor (4a) from the cooking step b) to liquid effluent (4b), e) an enzymatic hydrolysis step (6) in order to obtain a hydrolyzed biomass (7), f) a step of fermenting (8) the hydrolyzed biomass (7) in order to obtain a mixture comprising a fermented biomass (9) and a solid residue, then at least one step of washing said mixture or said solid residue obtained in step f), using the liquid effluent resulting from the condensation step d).

Description

[0001] PROCESS FOR TREATING LIGNOCELLULOSIC BIOMASS

[0002] Technical field

[0003] The invention relates to a method for treating lignocellulosic biomass to produce so-called second generation (2G) sugar juices, which can then be converted to produce other products by biochemical means, in particular by fermentation (for example alcohols such as ethanol, butanol), or other molecules, for example solvents such as acetone, etc.).

[0004] Prior art

[0005] Lignocellulosic biomass represents one of the most abundant renewable resources on Earth. The substrates considered are very varied, they concern both woody substrates such as different woods (hardwoods and softwoods), co-products from agriculture (wheat straw, corn cobs, etc.) or other agri-food industries, paper mills, lignocellulosic waste, etc.

[0006] The lignocellulosic biomass treatment process generally involves

[0007] - pretreatment of the biomass by cooking, possibly coupled with a steam explosion and optionally preceded by impregnation of the biomass with an acidic, basic, neutral or oxidizing liquor,

[0008] - enzymatic hydrolysis, leading to the production of sweet juices, generally based on 05 and 06 sugars (i.e. sugars with 5 or 6 carbons),

[0009] - then, if we continue the conversion, a fermentation of these sugars by a yeast, to convert them into alcohol of the ethanol type.

[0010] The process also includes steps of separation and / or purification of the targeted final product (sugar, alcohol, solvent, etc.).

[0011] Lignocellulosic biomass is composed of three main polymers: cellulose (35 to 50% by weight), which is a polysaccharide consisting mainly of hexoses; hemicellulose (20 to 40% by weight), which is a polysaccharide consisting mainly of pentoses; and lignin (10 to 30% by weight), which is a polymer with a complex structure and high molecular weight, composed of aromatic alcohols linked by ether bonds. These different molecules are responsible for the intrinsic properties of the plant wall and are organized into a complex tangle. Among the three basic polymers that integrate lignocellulosic biomass, cellulose and hemicellulose are those that allow the production of 2G sugar juices.

[0012] Most often, hemicellulose is mainly broken down into sugar during pretreatment, and the cellulose is converted into sugar (glucose) by enzymatic hydrolysis. However, access to raw cellulose remains difficult for enzymes, hence the need for pretreatment. This pretreatment makes it possible to modify the physicochemical properties of lignocellulosic biomass in order to improve the accessibility of cellulose to enzymes and its reactivity to enzymatic hydrolysis.

[0013] Many technologies of interest to the invention for carrying out this pretreatment exist, which will hereinafter be grouped under the generic term of "cooking": acid cooking, alkaline cooking, cooking by auto-hydrolysis, steam explosion, processes called "organosolv pulping" according to the known English term (or treatment with organo-solvent in French).

[0014] Different configurations are reported for example in the document “Production of bioethanol from lignocellulosic materials via the biochemical pathway: A review”, M. Balat, Energy Conversion and Management 52 (2011) 858-875, or in the document “Bioethanol production from agricultural wastes: an overview”, N. Sarkar, S. Kumar Ghosh, S. Bannerjee, K. Aikat, Renewable Energy 37 (2012) 19-27.

[0015] One of the most effective pretreatments is steam explosion, especially under acidic conditions, which allows almost complete hydrolysis of hemicellulose and a significant improvement in the accessibility and reactivity of cellulose to enzymes. This pretreatment may be preceded by other treatment(s).

[0016] For example, patent FR 3 075203 describes a process with impregnation of the biomass with an acid liquor, then cooking and steam explosion of the impregnated biomass, with adjustment of the acidity of the acid liquor and recycling of the latter.

[0017] These different types of process, starting from lignocellulosic biomass, generate solid residues based on lignin, in particular after enzymatic hydrolysis, and / or after fermentation if the conversion of sugars into alcohol is continued in particular. These solid residues, which will be called in this text "unconverted solid residue" or "washed lignin solid residue", are rich in lignin, which does not react or reacts little to the action of the enzymes used for the hydrolysis of biomass and which are generally cellulases and hemicellulases. These woody residues can be used, in particular as fuels, or be integrated as a filler in resin or bitumen-based products for example. However, these unconverted residues are not made up (apart from a certain quantity of water) only of lignin: they can also contain hemicellulose and / or cellulose which have not reacted to hydrolysis.And removing these residues from the biomass conversion process means losing these unreacted polymeric sugar fractions, which impacts the conversion efficiency of biomass into sugar (or alcohol). This is why a solution has been proposed, for example, in patent EP 3 587 583 to separate the juice (liquid) from fermentation from the lignin-based residue (solid), which consists of a very efficient separation comprising a contacting step followed by extraction / separation and washing of the solid residue to extract the maximum of the liquid juice it contains. However, these solid / liquid separation steps involve the use of a significant quantity of wash water.

[0018] Furthermore, patent application EP 3 177 672 discloses a process for producing chemical compounds, which consists of recovering the steam used in steam cooking biomass, condensing it and then extracting these chemical compounds with which the water is charged and which are by-products of cooking the biomass. It is only after this extraction that the water is then recycled into the biomass cooking reactor. However, this extraction of chemical compounds is an additional step, costly in terms of time and tools.

[0019] The invention then aims to remedy these various drawbacks. The invention aims to improve the processing of lignocellulosic biomass. More specifically, it aims to maintain or increase biomass conversion yields, while reducing the consumables or tools required for this conversion.

[0020] Summary of the invention

[0021] The invention firstly relates to a method for treating a lignocellulosic biomass, said method comprising a) an optional step of impregnating the biomass with a liquor, in particular acid, to obtain an impregnated biomass, b) a step of cooking the biomass, optionally impregnated in step a), in the presence of water vapor, for example of the steam explosion cooking type, to obtain a mixture comprising the pretreated biomass and water vapor, c) a step of separating the mixture of pretreated biomass and water vapor, to obtain on the one hand the pretreated biomass and on the other hand water vapor, d) a step of condensing the water vapor from cooking step b) into a liquid effluent comprising mainly liquid water, e) a step of enzymatic hydrolysis of the pretreated biomass, to obtain a hydrolyzed biomass in the form of sugar(s), in particular monomeric sugars,f) a step of fermentation of the hydrolyzed biomass in the form of sugar(s), in order to obtain a mixture comprising a fermented biomass comprising at least one alcohol in the form of a juice and a solid residue, then at least one treatment step aimed at treating this mixture or one of its components in order to extract, isolate and / or purify the fermented biomass, said treatment step, or at least one of them, comprising at least one step of washing said mixture or said solid residue obtained in step f), said washing step using at least part of the liquid effluent from condensation step d).,

[0022] For the purposes of the present invention, the term “solid” (unconverted) residue means a residue which comprises at least 20% by weight of solid, in particular at least 30 or 35% by weight of solid. The solid content can be measured by its Dry Matter (acronym “DM”) content, which is measured according to the ASTM E1756 - 08 (2015) “Standard Test Method for Determination of Total Solids in Biomass” standard. The DM of the unconverted “solid” residue according to the invention is preferably at least 20, 30 or 35%.

[0023] For the purposes of the present invention, the term "liquid effluent comprising mainly liquid water" means water resulting from the condensation of water vapor recovered after cooking which may contain volatile organic compounds. This liquid effluent generally comprises at least 90% water by volume, for example at least 95% and at most 97 or 98% or 99% water by volume.

[0024] For the purposes of the present invention, when step a) of impregnation is carried out, the impregnation liquor may comprise a chemical compound such as an acid, a base or an oxidizing agent or by a water-based liquor, with autohydrolysis of the biomass naturally releasing an acid, in particular acetic acid.

[0025] The invention thus identified a source of water for washing after enzymatic hydrolysis and fermentation, in particular that of the solid residue, namely the condensed water from cooking the biomass. And this recycling from upstream to downstream of the process (considering the succession of biomass treatment stages) proved very advantageous in several ways:

[0026] - it makes it possible to significantly reduce the water consumption of the process, in particular that of the aforementioned washing step, while the quantity of washing water can represent a significant part of the water required for the entire conversion process (at least 10 or even 20%, for example around 25% of the total water consumed),

[0027] - it limits the dilution of the conversion product, of the alcohol type ethanol before its separation / purification stages, in particular before distillation, since there is no, or less, additional water input

[0028] - this aqueous effluent from cooking has no impact on the quality of the unconverted solid residue obtained after solid / liquid separation of the fermented biomass then washing, the solid residue retains the same calorific properties when it is then used in combustion (no addition of organometallic compounds such as silica, nor additional trace elements generating ash).

[0029] The temperature of the liquid effluent (mainly condensed water) for washing can be between 30 and 90°C, preferably between 30 and 60°C. Carrying out washing with a liquid phase above ambient temperature promotes washing by tending to reduce its duration.

[0030] The pH of the liquid effluent from condensation (mostly condensed water) can be between 2 and 4. This water is in fact acidic when the biomass has been impregnated with an acidic liquor prior to cooking. This acidity can be advantageous because it promotes the decomposition of solid deposits that may have accumulated in the supply lines of the filtration / washing device.

[0031] However, this choice could have proved problematic. Indeed, the liquid effluent resulting from the condensation of the steam during the cooking stage is water which can be loaded with traces of various compounds carried along with it, in particular furfural, 5-HMF, or organic acids, such as acetic acid. However, more particularly furfural or its derivatives are harmful, because they can be toxic, in particular, to the yeasts used during the fermentation stage, which can result in the appearance of a lag time during fermentation, a slowdown in alcohol production, and ultimately a loss of ethanol at the end of fermentation. It is therefore not possible to recycle this condensation water to the reaction stages following cooking, unless one considers first extracting these compounds from the condensed water, which requires a dedicated separation / purification stage, and additional ad hoc tools.And it has proven to be no more relevant to recycle this condensation water to an upstream stage (a stage of impregnation or washing of the biomass before cooking for example or to produce the steam necessary for cooking the biomass), because these compounds risk accumulating from stage to stage, which again would require purifying the condensed water.

[0032] Now what the invention discovered is that it was entirely possible to use / recycle this condensed water, without treatment or purification, downstream of the cooking step generating the steam, but after the fermentation step: thus, the traces of compounds contained in the condensed water do not have any potentially problematic effect on the fermentation, and, surprisingly, using this condensed water after the fermentation did not cause any inconvenience, did not in any way affect the yield or the quality of the targeted product. This recycling is therefore very effective, and occurs in the conversion process at just the appropriate step / time to avoid prior treatment of the condensed water.

[0033] Advantageously, the process according to the invention may comprise, after fermentation step f), at least two treatment steps: g) a step of solid / liquid separation of the fermented biomass, in order to obtain a separate juice comprising at least this alcohol and a solid residue, h) a step of washing the solid residue with, as washing water, at least in part, the liquid effluent from condensation step d).

[0034] Using the condensed water from the steam used during biomass cooking for washing the solid phase recovered after solid / liquid separation from fermentation did not cause any disadvantages, neither in its efficiency in extracting juice trapped in the solid phase, nor in the final quality of the alcohol, nor in the heat capacity of the ultimate solid residue. And, as mentioned previously, the washing water after solid / liquid separation of the fermented biomass can constitute a significant water consumption item for the process as a whole, and reducing or even eliminating a water input for this step is extremely advantageous economically.

[0035] The water vapor separated in separation step c) may be loaded with by-products from the cooking of the biomass from step b), in particular comprising at least one of the following by-products: furfural, sugar degradation compounds such as 5-hydroxymethylfurfural 5-HMF, one or more organic acids such as acetic acid, methanol. The contents of these different by-products (expressed in liters of this vapor once condensed, called “liquid effluent”) may be, for example, the following:

[0036] Furfural: between 10 and 50 g / l

[0037] Acetic acid: between 1 and 15 g / l

[0038] 5-HMF: between 0 and 2 g / l

[0039] Other component(s): less than 1 g / l

[0040] According to one embodiment of the invention, all of the liquid effluent from condensation step d) is used as wash water in washing step h). In this case, all of the condensed effluent is recycled in washing step h). Alternatively, a certain portion may be kept for another use, or, if it is in excess of the requirements, be stored or sent to a final water treatment unit of the process.

[0041] According to one embodiment of the invention, the washing step h) uses as washing water only the liquid effluent from the condensation step d). In this case, the quantity of condensed water is sufficient to completely replace any external water supply; this is the most advantageous configuration because it eliminates any consumption of external water for the washing step. According to one embodiment of the invention, the washing step h) uses as washing water partly the liquid effluent from the condensation step d) and partly another water supply, in particular in a volume proportion of 10 / 90 to 90 / 10. In this case, it may be, in particular, that the quantity of available liquid effluent is insufficient (or for other reasons) and, in this case, it is supplemented with an external water supply.

[0042] The enzymatic hydrolysis steps e) and fermentation f) can be carried out simultaneously on the pretreated biomass. This is known as SSF for the acronym of the English term "Simultaneous Saccharification and Fermentation" or SSCF for the acronym of the English term "Simultaneous Saccharification and Co-Fermentation". They can also be carried out one after the other, in separate reactors in particular.

[0043] The process according to the invention may also comprise: i) a step of separation or purification, in particular distillation, of the fermented biomass, step g) of solid / liquid separation and step h) of washing being carried out before or after said step i) of separation or purification.

[0044] Condensation step d) can be carried out by heat exchange of the water vapor with a fluid used in the process, in order to raise the temperature of said fluid.

[0045] Step g) of solid / liquid separation can be carried out by filtration, in particular using a pressing or draining device, such as a filter press or a vacuum filter, a belt filter, a belt press, a centrifugation, decantation or wringer device or the combination of at least two of these devices.

[0046] Step g) of solid / liquid separation can be carried out discontinuously or continuously.

[0047] Step h) of washing the solid residue can be carried out continuously, in co-current or counter-current.

[0048] In the context of the present invention, when a solid / liquid separation is carried out, the separated "solid phase" is to be understood as containing the solid phase itself and the liquid phase trapped in said solid phase.

[0049] The invention also relates to any installation implementing the method described above.

[0050] The invention also relates to an installation, in particular for implementing the method described above and which comprises: a) an optional impregnation device, in particular an impregnation reactor, of the biomass with a liquor, in particular acid, to obtain an impregnated biomass b) a device for cooking the biomass, optionally impregnated with the impregnation device a), in the presence of water vapor, for example of the steam explosion cooking type, to obtain a mixture comprising the pretreated biomass and water vapor, c) a device for separating the mixture of pretreated biomass and water vapor, to obtain on the one hand the pretreated biomass and on the other hand water vapor, d) a device for condensing the water vapor from the cooking step b) into liquid effluent, in particular a heat exchanger device, e) a device for enzymatic hydrolysis, in particular an enzymatic hydrolysis reactor, of the pretreated biomass,to obtain a hydrolyzed biomass in the form of sugar(s), f) a device for fermenting the hydrolyzed biomass in the form of sugar(s), in particular a fermentation reactor, in order to obtain a mixture comprising a fermented biomass comprising at least one alcohol in the form of a juice and a solid residue, said device being separate from the enzymatic hydrolysis device or being common with it, then at least one treatment device intended to treat this mixture or one of its components in order to extract, isolate and / or purify the fermented biomass, including at least one washing device using at least part of the liquid effluent from the condensation device d).,

[0051] This installation may also comprise, downstream of the fermentation device f), two treatment devices: g) a device for solid / liquid separation of the fermented biomass, in order to obtain a separate juice comprising at least this alcohol, and a solid residue, in particular a pressing or draining device, such as a filter press or a vacuum filter, a belt filter, a belt press, a centrifugation, decantation or spin-drying device or the combination of at least two of these devices h) a device for washing the solid residue, possibly common with the solid / liquid separation device or separate from it, with, as washing water, at least in part, the liquid effluent from the condensation step d).

[0052] The invention also relates to the use of the method or installation described above, for the treatment of lignocellulosic biomasses, such as wood, straw, agricultural residues, paper residues, and all dedicated energy crops, in particular annual or multi-annual plants such as miscanthus, with a view to producing alcohol-type biofuels or bio-sourced molecules. The treatment method targeted by the invention can convert the lignocellulosic biomass into sugary juice, in particular C5 and C6 juices, after enzymatic hydrolysis, then into alcohol(s), in particular ethanol, after fermentation of said sugary juice.

[0053] The invention will be described in detail below, using figures and non-limiting examples.

[0054] List of figures

[0055] Figure 1 is a block diagram of a process for converting lignocellulosic biomass without implementing the invention.

[0056] Figure 2 is a block diagram of a biomass conversion process implementing the invention in a first embodiment.

[0057] Figure 3 is a block diagram of a biomass conversion process implementing the invention in a second embodiment.

[0058] Note that the same references concern the same flow, the same device, the same step from one figure to another.

[0059] The description of the references is presented below:

[0060] 1: Biomass

[0061] 2: Water vapor

[0062] 3: Pre-treatment

[0063] 4a: Vapor phase

[0064] 4b: Pretreatment condensates

[0065] 5: Pretreated biomass

[0066] 6: Enzymatic hydrolysis

[0067] 7: Hydrolyzate

[0068] 8: Fermentation (possibly simultaneous with 6)

[0069] 9: Fermentation must, containing alcohol

[0070] 10a: Solid / liquid filtration

[0071] 10b: Washing of the solid fraction trapped in the solid / liquid separation tool.

[0072] 10c: Compaction of washed solid residue

[0073] 11: Washing water

[0074] 12a: Filtration filtrate

[0075] 12b: Wash filtrate

[0076] 12c: Compaction filtrate

[0077] 13: Washed solid residue

[0078] 14: Purification of alcohol 15: Purified alcohol (ethanol over 96% by weight)

[0079] 16: Vinasses

[0080] 17: Condensation and cooling of steam

[0081] 18: Water treatment

[0082] 19: Water treated for recycling

[0083] Description of the embodiments

[0084] Below is a detailed description of the various key stages of a biomass conversion process to which the invention can advantageously be applied: (this is an example to which the invention is not limited).

[0085] Lignocellulosic biomass conditioning stage

[0086] The treatment process comprises in its first step, a step of conditioning the lignocellulosic biomass with at least one grinding so as to obtain biomass particles having a size of at most 300 mm. It is of course possible to carry out several successive grinding steps in order to reach the target particle size. Generally, the ground biomass has a particle size (the largest size) of at most 300 mm, most often at least 1 mm, and often between 2 and 200 mm. Any method known to those skilled in the art can be implemented to carry out this step. Most often, the grinding of straw is done with screens of 5 to 100 mm. As for the wood, it is generally shredded into parallelepiped plates with a length between 20 and 160 mm, a width between 10 and 100 mm and a thickness between 2 and 20 mm.The crushed lignocellulosic biomass is brought to the next stage by any means known to those skilled in the art, in particular a transfer screw.

[0087] Impregnation step with an acidic liquor

[0088] The treatment method according to the invention comprises a step a) of impregnating the lignocellulosic substrate with an acid liquor so as to obtain an impregnated lignocellulosic substrate whose pH is between 0.1 and 3. This step aims to prepare the lignocellulosic substrate for the pretreatment step.

[0089] The impregnation is carried out in an impregnation reactor at a temperature between 10 and 90°C and preferably at atmospheric pressure. The residence time of the lignocellulosic substrate in the impregnation reactor is usually from 10 seconds to 180 minutes, preferably between 30 seconds and 60 minutes and even more preferably between 30 seconds and 15 minutes. Preferably, the impregnation step is carried out in a single step. The acid liquor is an aqueous solution of a strong acid, which is for example chosen from sulfuric acid, hydrochloric acid, nitric acid, for example at an acid content of between 0.5 and 4% by weight.

[0090] Solid / liquid separation step on the lignocellulosic substrate impregnated with acid liquor The lignocellulosic substrate impregnated with acid liquor is subjected to a solid / liquid separation step in order to obtain a lignocellulosic substrate having a dry matter content of between 15% and 70% by weight and a spent acid liquor. Preferably, the lignocellulosic substrate impregnated with acid liquor is first drained in order to extract at least a portion of the free acid liquor before being treated by solid / liquid separation. The solid / liquid separation step may implement any technique known to those skilled in the art, which may be, for example, decantation, centrifugation or pressing.

[0091] Preferably, pressing of the lignocellulosic substrate is carried out concomitantly with its transfer to the pretreatment stage when the latter implements the steam explosion process which is described below.

[0092] The wet biomass obtained at the end of the solid / liquid separation step, which can be designated by the term "acidified lignocellulosic substrate", has a dry matter content preferably between 15% and 70% by weight, and more preferably between 40 and 65% by weight.

[0093] Pretreatment stage of the acidified lignocellulosic substrate

[0094] The acidified lignocellulosic substrate undergoes a pretreatment step.

[0095] Cellulose (and possibly hemicelluloses) which are the targets of enzymatic hydrolysis are not directly accessible to enzymes. This is why a pretreatment of the biomass is implemented before the enzymatic hydrolysis step.

[0096] Pretreatment aims in particular to modify the physical and physicochemical properties of the cellulose fraction, such as its degree of polymerization and its state of crystallinity.

[0097] Various types of pretreatment are known to those skilled in the art, combining chemical treatment and heat treatment. Examples include acid or basic cooking, the Organosolv process and the steam explosion process.

[0098] The preferred pretreatment process is steam explosion ("Steam Ex" or "Steam Explosion" according to the English terminology) carried out in an acidic medium. This is a process in which the lignocellulosic substrate is rapidly brought to a high temperature by injecting pressurized steam. The treatment is stopped by sudden decompression. The operating conditions of the steam explosion process are as follows: the steam is injected directly into the reactor; the reactor temperature is generally between 150 and 220°C, preferably between 170°C and 210°C, the pressure is between 5 and 25 bar absolute (0.5 and 2.5 MPa), more preferably between 8 and 19 bar absolute (0.8 to 1.9 MPa), the residence time before the expansion phase varies from

[0099] 10 seconds to 50 minutes, and preferably between 3 minutes and 30 or 40 minutes The steam explosion can be carried out in batch or continuous mode, and the depressurization step which allows the biomass to be destructured can take place in one or more stages.

[0100] At the end of the steam explosion pretreatment stage, a pretreated lignocellulosic substrate with a high dry matter content, generally between 20 and 70% by weight, and a vapor phase which can be condensed is obtained.

[0101] Following steam explosion under acidic conditions, the pretreated lignocellulosic substrate generally has a pH lower than that compatible with the medium for enzymatic hydrolysis. Thus, the lignocellulosic substrate is subjected to a neutralization step to bring its pH to a value between 4 and 6.

[0102] For the neutralization step, an aqueous solution containing a neutralizing agent is used which can be chosen from any weak or strong base known to those skilled in the art. By the term base, we mean any chemical species which, when added to water, gives an aqueous solution with a pH greater than 7. Preferably, the neutralizing agent is chosen from potassium hydroxide, sodium hydroxide, ammonia, lime. Even more preferably, the neutralizing agent is chosen from potassium hydroxide and ammonia, alone or in combination with each other. Preferably, the neutralizing agent is used in aqueous solution, with a mass concentration of between 2% and 75%, and even more preferably between 20% and 70%.

[0103] Neutralization is carried out at a temperature between 15°C and 95°C, and preferably between 20°C and 70°C. In general, the temperature of the neutralization step is not precisely controlled and is simply governed by the heat released by the acid-base neutralization reaction.

[0104] The neutralization step can be carried out continuously, batchwise or fed-batch.

[0105] It should be noted that a possible washing step can be carried out before or after the neutralization step, on all or part of the pretreated lignocellulosic substrate.

[0106] If washing is applied, a liquid stream is brought into contact with the pretreated lignocellulosic substrate, then the liquid is separated from the solid. The washing step can be carried out by percolation, by successive mixing operations and liquid / solid separation, by washing on a belt filter or by any other technique known to those skilled in the art. The washing liquid used can be water or a process stream. The mass ratio between the added washing liquid and the liquid contained in the substrate to be washed is generally between 0.5 and 4. The washing step generates a sugary washing juice containing a portion of the hemicelluloses solubilized during the pretreatment. This washing juice can, for example, be used as a carbon source for the production of biocatalysts (enzymes and / or microorganisms). The washing step is generally carried out at a temperature between 10°C and 95°C.

[0107] Enzymatic hydrolysis step

[0108] The pretreated lignocellulosic substrate, optionally neutralized and washed, is sent to the enzymatic hydrolysis stage of the process.

[0109] The pretreated lignocellulosic substrate which is sent to the enzymatic hydrolysis stage has a dry matter content generally between 20% and 70% by weight.

[0110] The objective of enzymatic hydrolysis is to hydrolyze (depolymerize), by means of biocatalysts, hemicelluloses and cellulose into fermentable sugars, preferably glucose.

[0111] The enzymatic hydrolysis step is carried out under mild conditions, at a temperature of the order of 40°C and 55°C, preferably between 45°C and 50°C and at a pH of 4.0 to 5.5, and even more preferably between 4.5 and 5.2. The dry matter content of the enzymatic hydrolysis medium is between 2 and 45% by weight, preferably between 10 and 30% by weight. It is carried out using enzymes produced by a microorganism. Natural or genetically modified microorganisms, such as fungi belonging to the genera Trichoderma, Aspergillus, Penicillium or Schizophyllum, or anaerobic bacteria belonging for example to the genus Clostridium, produce a cocktail of enzymes containing in particular cellulases and hemicellulases, suitable for extensive hydrolysis of cellulose and hemicelluloses.

[0112] Enzymatic hydrolysis can be carried out in continuous or batch mode, or in fed continuous mode, in one or more reactors. The residence time is between 5 hours and 200 hours and preferably between 24 hours and 120 hours and even more preferably between 48 hours and 120 hours.

[0113] At the end of this stage, a hydrolysate containing fermentable sugars is recovered from the bioreactor and is then treated in the fermentation stage.

[0114] It should be noted that the hydrolyzate obtained may optionally undergo one or more treatment steps before the fermentation step. For example, this may involve a pH adjustment, a partial purification in order to limit the content of inhibitory compound for the fermentative microorganism, or at least a partial separation of the solid residues contained in the hydrolyzate (and thus obtain the unconverted solid residue to be treated according to the invention).

[0115] Fermentation stage of the hydrolyzate, when the conversion of the sugars obtained into alcohol(s) is continued

[0116] Depending on the step of the process for producing solvents and / or alcohols, the optionally treated hydrolyzate is sent to the fermentation step allowing the conversion by means of one or more microorganisms of different genera of the fermentable sugars into solvent and / or alcohols of interest. The fermentation methods are known to those skilled in the art and are described in particular in document US 8,456,633.

[0117] The term "solvent" means organic compounds other than alcohols, for example organic compounds having a ketone function such as acetone.

[0118] The term "alcohol" includes, in particular, ethanol, propanol, isopropanol and butanol.

[0119] Natural or genetically modified microorganisms can be chosen for example from Saccharomyces cerevisiae, Schizosaccharomyces pombe, Saccharomyces uvarum, Saccharomyces diastaticus, Kluyveromyces fragilis, Candida shehatae, Pichia stipitis, Pachysolen tannophilis or the bacteria Zymomonas mobilis, Clostridium acetobutylicum, Escherichia coli.

[0120] In the context of the invention, the fermentation step makes it possible, for example, to produce ethanol alone or in a mixture with butanol, propanol, isopropanol and / or acetone. For example, the fermentative microorganism may be capable of producing a mixture called "ABE (acetone-butanol-ethanol)" or "IBE (isopropanol-butanol-ethanol)". Preferably, the microorganism chosen is a natural or genetically modified yeast of the genus Saccharomyces capable of producing ethanol.

[0121] At the end of the stage, a fermentation must diluted in products of interest is recovered.

[0122] According to one embodiment of the method, the hydrolysis and fermentation steps can be carried out at the same time in at least one bioreactor so that the enzymatic hydrolysis and the fermentation are carried out simultaneously according to a method designated by the term "Simultaneous Saccharification and Fermentation (SSF)". When the hydrolysis step is combined with the fermentation step, the operating conditions, in particular temperature, can be adapted to adapt to the tolerances of the fermentation microorganism. For example, the temperature can be lowered to between 28°C and 45°C, and preferably between 30°C and 35°C when the fermentation is carried out with a yeast of the genus Saccharomyces. The pH is preferably adjusted to between 5 and 5.5 in order to promote the performance of the yeasts.The production unit implementing the method according to the invention may comprise, in addition to the installations already described, in situ production units for enzymes and / or yeasts.

[0123] Step of separating solvents and / or alcohols from the fermentation must

[0124] The method according to the invention finally comprises a step of separating the product(s) of interest from the fermentation must, which is preceded or followed by a solid / liquid separation step in order to eliminate at least a fraction of the solid matter contained in the fermentation must, and to produce the unconverted solid residue which will be treated (washed) according to the invention.

[0125] Preferably, the step of separating the product(s) of interest, for example ethanol, uses one or more distillations which is a technology well known to those skilled in the art.

[0126] : lignocellulosic biomass

[0127] According to the invention, the feedstock of the process may be a biomass alone or in a mixture. The quantity of water contained in the raw feedstock may be at least 10%, in particular between 10 and 40% by mass. Alternatively, the biomass may be dry, and contain less than 10% by weight of water.

[0128] The raw biomass is chosen from any type of biomass, preferably solid biomass, and in particular lignocellulosic biomass. Non-limiting examples of types of biomass include, for example, agricultural residues (in particular straw, corn cobs), forestry residues, forestry products, sawmill residues, dedicated crops, for example short-rotation coppices. Preferably, the raw biomass, also called native biomass, is lignocellulosic biomass. It essentially comprises three natural constituents present in variable quantities depending on its origin: cellulose, hemicellulose and lignin. The lignocellulosic biomass feedstock is preferably used in its raw form, i.e. in all three of these constituents: cellulose, hemicellulose and lignin.

[0129] In a preferred embodiment of the invention, the lignocellulosic biomass is chosen from grass biomass, agricultural residues such as straw waste, corn cobs, sugar cane bagasse, forestry or sawmill residues such as wood chips or any other type of woody residue.

[0130] The fluid of i: The optional fluid, injected for impregnation is an aqueous liquid solution containing or not acid, at a temperature between 10 and 95°C and at atmospheric pressure. The pH of this chemical solution is between 0.1 and 12.0, preferably between 0.1 and 7, preferably between 0.3 and 2. According to a preferred embodiment, the liquor used is an acid-catalyzed liquor, and the pH of the liquor is adjusted between 0.1 and 4, in particular between 0.3 and 2. As acid, it is possible for example to use at least one acid chosen from sulfuric acid, hydrochloric acid, nitric acid, oxalic acid. Their content, in the aqueous phase, is preferably between 0.2 and 8% by weight.

[0131] The invention applies similarly to different methods and installations, in particular to:

[0132] - installations / processes which provide pre-treatment by cooking without prior impregnation with a liquor (autohydrolysis for example),

[0133] - installations / processes which provide for pre-treatment by cooking with prior impregnation with a non-acidic liquor.

[0134] Figure 1 shows in summary form the block diagram of an example of a conversion process of this type not in accordance with the invention, a process which provides for pretreatment of the biomass including impregnation with an acid liquor then cooking / explosion with steam, then enzymatic hydrolysis followed by alcoholic fermentation, to transform the biomass into ethanol.

[0135] Figure 1 therefore represents a biomass conversion carried out in the following way: biomass 1 has been previously conditioned (optional step) then possibly pre-impregnated with a liquor, for example acid (optional step). It is introduced into a cooking reactor for a cooking and steam explosion step 3, the reactor also being supplied with water vapor 2. Note that this can be cooking with steam explosion, or cooking without steam explosion but which generates steam. At the end of cooking step 3, the pretreated biomass 5 is separated from the vapor phase 4a. This vapor phase is mainly made up of water but may contain traces of furfural, 5-HMF and acetic acid.

[0136] The pretreated biomass 5 proceeds to the enzymatic hydrolysis step 6, in a suitable reactor which is also supplied with an appropriate enzymatic cocktail to convert the cellulose and hemicelluloses into sugars, in particular into monomeric sugars. The hydrolyzed biomass 7 is then fermented in step 8, by adding yeasts to convert the monomeric sugars into alcohol, in particular into ethanol. Steps 6 and 8 can be carried out simultaneously or not, in one or more reactors in series. At the end of the fermentation, the fermentation must containing the alcohol is treated in a solid / liquid filtration step 10a, by a belt filter or a filter press for example, and the solid fraction trapped in the solid / liquid separation tool of step 10a is then washed in step 10b with an addition 11 of liquid water. The washing filtrate is noted 12b. The filtration filtrate is noted 12a.This step 10b may include repulping or contacting the solid fraction trapped in the solid / liquid separation tool with liquid water 11 followed by solid / liquid separation by filtration for example. “Repulping” or “contacting” means the operation consisting of bringing the fermented biomass or the solid fraction obtained after step 10a) into contact with a washing fluid by suspending the biomass in water.

[0137] Step 10c is a compaction step of the solid fraction trapped in the solid / liquid separation tool after steps 10a and 10b, at the outlet of which a compaction filtering 12c and a washed solid residue also called compact ligneous “washed solid residue” 13 are obtained which is rich in lignin and solids not converted during enzymatic hydrolysis / fermentation. It can, ultimately, be used as fuel. The heat produced can be used in the process in one or more steps requiring heating of a fluid (impregnation liquor), a reactor (cooking during pretreatment) or a reboiler of a distillation column (to purify the alcohol obtained by fermentation, etc.).

[0138] An example of carrying out steps 10a, 10b and 10c is as follows: The separation of the washed solid residue of lignin is preferably carried out by pressure filtration, with a filter press, with a filtration step itself, under pressure (6-8 bars): filling the filtration chambers then filtration. A first liquid fraction, called filtration filtrate, is recovered, with a very low concentration of solids and rich in fermentation products (ethanol) or sugars. The solid fraction remains trapped between the filter press cloths. The filtration step is carried out at a temperature between 30 and 80°C, preferably between 35 and 50°C. It is followed by a washing step of the solid fraction to increase the recovery rate of fermentation products (ethanol) or enzymatic hydrolysis products (sugars). This washing step is carried out by percolating a washing fluid.This washing fluid, as seen further with figures 2 and 3, consists of water, of which, according to the invention, at least 30% of the condensates obtained in the pretreatment step (cooking). A second liquid fraction, called washing filtrate, is recovered, with a very low concentration of solids and rich in fermentation products (ethanol) or sugars. The solid fraction remains in the filter chambers and is more depleted in products of interest than the first solid fraction. The temperature of the washing fluid is between 30 and 90°C, preferably between 50 and 80°C.

[0139] This washing step can also be implemented by repulping the solid fraction after the filtration step with the washing fluid, followed by filtration.

[0140] This operation can be followed by a so-called compaction operation: drainage of the liquid contained in the solid fraction. A compaction filtrate with a very low concentration of solids and sufficiently rich in fermentation products (ethanol) or sugars is recovered. This is then followed by a so-called deconstructing operation to recover the solid fraction, called washed solid residue, depleted in ethanol or sugars, and enriched in unconverted lignin / cellulose / hemicellulose.

[0141] The various filtrates 12a, 12b and 12c are combined and sent to the alcohol purification step 14, which may include at least one of the following treatments: stripping, distillation, dehydration on molecular sieve. This produces a purified alcohol stream 15 (ethanol at least 96% by weight) and vinasses 16. These vinasses 16 are treated in the water treatment step 18, which may include one or more physicochemical treatments, such as evapoconcentration, ultrafiltration, reverse osmosis, and / or biological treatments such as anaerobic digestion to produce biogas. Treated water 19 is obtained which may be recycled in the process.

[0142] If we return to cooking step 3, we therefore have, at the end of cooking, in addition to the pretreated biomass 3, a vapor phase 4a. This is condensed in step 17, by cooling the vapor by heat exchange in liquid phase 4b to heat at least one fluid used in the biomass conversion process. This may involve heating a biomass impregnation liquor (before cooking) or the “wine” obtained after fermentation before distillation. This liquid phase 4b is then sent to water treatment step 18, with the vinasse 16, and therefore contributes to the flow of treated water 19 which leaves it. This vapor 4a is therefore only used to exhaust it thermally and then it is directed in liquid form to the final water treatment unit.

[0143] Figure 2 is a first embodiment of the invention, which modifies the diagram of the process according to the invention in the following way: (only what differs from the process shown in Figure 1 will be described below, for the sake of brevity). The washing water of step 10b is partly a water make-up 11 as previously in Figure 1, and partly the liquid water 4b resulting from the condensation of the steam 4a.

[0144] Figure 3 is a second embodiment of the invention, which modifies the diagram of the process according to the invention of Figure 2 in the following way: (only what differs from the process shown in Figure 2 will be described below, for the sake of brevity). The washing water of step 10b here consists entirely of the liquid water 4b resulting from the condensation of the steam 4a.

[0145] Examples of achievements

[0146] Example 1 (comparative) The biomass considered is a lignocellulosic biomass: wheat straw. Its composition is indicated in Table 1 below

[0147] Table 1

[0148] The biomass is treated according to the process shown in Figure 1 (process not in accordance with the invention):

[0149] 52.2 t / h of crushed biomass 1 enters the process and undergoes pretreatment 3 which consists of:

[0150] - impregnation with an aqueous solution of sulfuric acid: the impregnation is carried out in the presence of acid liquor heated to 80°C.

[0151] - the introduction of this impregnated biomass into a reactor under pressure of ~10 bara heated to 180°C with steam injection 2.

[0152] - a multi-stage expansion to atmospheric pressure releasing steam 4a and a pretreated biomass 5 having a dry matter content of 45% by weight.

[0153] This separation is carried out by one or more cyclones in order to limit the loss of solids.

[0154] The vapor phase 4a at the outlet of this cyclone is at a pressure of 2.1 bara and a temperature of 123°C. This hot flow is used initially to heat the acid liquor to a temperature of 80°C (the vapor does not condense completely) and is then used to preheat the fermentation must before the solid / liquid separation step or the filtered wine at the inlet of the distillation step. The condensation and cooling step 17 is therefore carried out by means of an exchanger. The temperature at the outlet of the condensation step is 30°C. At the outlet of the pretreatment step:

[0155] - The flow rate of condensed vapor phase 4b is 21.4 t / h.

[0156] - The flow rate of pretreated biomass 5 is 96.1 t / h

[0157] Vapor phase 4a contains in particular acetic acid and furfural which are produced during the pretreatment of biomass and are due to the degradation of hemicelluloses and the depolymerization of acetyl groups.

[0158] The composition of 4b condensates is given in Table 2 below:

[0159] Table 2

[0160] The condensates 4b feed the water treatment unit 18, mixed with other process outlet water to be purified.

[0161] The pretreated biomass 5 feeds one or more fermentation reactors in order to convert the sugar polymers into monomeric sugars under the action of an enzymatic cocktail (preferably containing cellulases, betaglucosidases, xylanases), then these sugars into ethanol by fermentation with yeasts (Saccaromyces cerevisiae for the production of ethanol).

[0162] This step can be carried out in two sub-steps: a first of liquefaction 6 with a sequential feeding of the biomass allowing to work with high dry matter content. Then a second of enzymatic hydrolysis and fermentation 8 in batch.

[0163] The enzyme cocktail and yeasts are preferably introduced into the liquefaction reactor 6. An adjustment of the pH of the medium can also be carried out by adding base, for example sodium hydroxide or ammonia.

[0164] The fermentation must obtained 9, the composition of which is given in table 3 below, then feeds the solid / liquid separation stage 10a.

[0165] The fermentation must flow rate 9 is 178.4 t / h.

[0166] Table 3

[0167] The solid / liquid separation tool used is, for example, a filter press.

[0168] This solid / liquid separation step includes a first step 10a of filtration of the fermentation must, followed by a washing step 10b of the remaining solid. The mass ratio between the water flow rate used for this washing step and the flow rate of solid to be washed (solid trapped in the solid / liquid separation tool after step 10a) is 1.08. This washing step allows the ethanol present in the solid to be recovered.

[0169] The flow rate of wash water 11 is 50.5 t / h. The recovery rate of ethanol in the wash filtrate 12b is 80.5% by weight.

[0170] The compaction and deconstructing step 10c allows the recovery of the washed solid residue called washed solid residue of lignin 13. The compaction efficiency is 45%, it corresponds to the recovery rate of ethanol in the compaction filtrate 12c compared to the ethanol present in the solid residue after filtration and washing.

[0171] After solid / liquid separation, all filtrates 12a, washing filtrates 12b and compacting filtrates 12c are combined. The total flow rate of these filtrates is 196 t / h.

[0172] The flow rate of washed solid residue 13 recovered after this separation step is 32.8 t / h. Its composition is given in Table 4 below:

[0173] Table 4

[0174] All the filtrates, containing mainly water and ethanol, but also the compounds produced during the upstream stages (unconverted sugars, impurities produced by fermentation) feed the atmospheric distillation column 14 in order to separate the ethanol produced. Ethanol 15, whose composition is close to the azeotrope with water, is obtained at the top of the column before being sent to the dehydration section. The other liquid compounds of the process 16 (vinasses) are extracted at the bottom of the column and sent to the wastewater treatment section 18.

[0175] The composition of vinasse 16 is given in table 5 below:

[0176] Table 5

[0177] The liquid discharges sent to the water treatment unit are therefore:

[0178] - Condensates 4b at the outlet of the pretreatment section: flow rate of 21.4 t / h

[0179] - Vinasse 16 from the water / alcohol distillation column: flow rate of 185.4 t / h

[0180] The total flow rate of effluent to be treated is therefore 206.8 t / h. The condensates at the pretreatment outlet therefore represent 10% of the water to be treated in the process.

[0181] Example 2 (according to the invention)

[0182] In this example, the condensates 4b are directed directly to the washing step of the residual solid 10b) obtained after filtration of the fermentation must, mixed with a flow of washing water 11, as shown in figure 2. In this example, the proportion of condensates 4b relative to the flow 11 of washing water is 74% (volume).

[0183] The outlet temperature of condensation stage 17 is 80°C.

[0184] The washing ratio to minimize ethanol loss in the washed lignin solid residue 13 is identical to that of Example 1. The flow rate of wash water 11 used in mixture with condensates 4b for washing the washed solid residue is 29.1 t / h.

[0185] The soluble compounds present in the condensates 4b do not impact the recovery yield of ethanol in the filtrates during the washing step.

[0186] After solid / liquid separation, all filtrate 12a, washing filtrate 12b and compaction filtrate 12c are combined. The total flow rate is 196 t / h.

[0187] The operating conditions of step 14 of water / ethanol separation by distillation then by dehydration on molecular sieve are identical to example 1.

[0188] The flow of vinasse 16 extracted at the bottom of the column is sent to the wastewater treatment section 18. The total flow rate of effluent to be treated is 185.4 t / h, which represents a reduction of 10% in the capacity of the water treatment section compared to example 1.

[0189] Example 3 (according to the invention)

[0190] In this example, the condensates 4b are directed directly to the residual solid washing step 10b) obtained after filtration of the fermentation must. The temperature at the outlet of the condensation step 17 is 80°C.

[0191] The washing of the washed solid residue 13 is carried out only with this condensate stream 4b from pretreatment 3, as shown in Figure 3.

[0192] The mass ratio between the condensate flow rate used for this washing step and the solid flow rate to be washed is 0.46, a reduction of 57% compared to examples 1 and 2.

[0193] This washing step allows an ethanol recovery rate in the washing filtrate 12b of 65% by weight.

[0194] The compaction and deconstructing step 10c allows the recovery of the washed solid residue of lignin 13. The compaction efficiency is identical to examples 1 and 2, i.e. an ethanol recovery rate of 45% by weight in the compaction filtrate 12c.

[0195] After solid / liquid separation, all filtrates 12a, washing filtrates 12b and compacting filtrates 12c are combined. The total flow rate of these filtrates is 167 t / h.

[0196] The flow rate of washed solid residue of lignin 13 recovered after this separation step is 32.8 t / h. Its composition is given in Table 6 below:

[0197] Table 6

[0198] The operating conditions of step 14 of water / ethanol separation by distillation then by dehydration on molecular sieve are identical to examples 1 and 2. The vinasse stream 16 extracted at the bottom of the column is sent to the wastewater treatment section 18.

[0199] The total flow rate of effluent to be treated is 156.6 t / h, which represents a 15% reduction in the capacity of the water treatment section compared to example 2, and a 24% reduction in the capacity of the water treatment section compared to example 1.

[0200] The ethanol loss in the washed lignin solid residue is increased by 80% compared to Examples 1 and 2 by a limited washing fluid flow rate.

[0201] In conclusion, the invention makes it possible to reduce the water consumption of the washing operation carried out after fermentation, and to reduce the quantity of water to be treated at the end of the conversion process, without affecting the quality of the product obtained, and even making it possible to increase its yield, by using "as is" condensed water vapor from cooking the biomass, which is a solution that is both simple and effective.

Claims

Claims 1. Method for treating a lignocellulosic biomass, said method comprising a) an optional step of impregnating the biomass (1) with a liquor, in particular acid, to obtain an impregnated biomass, b) a step of cooking (3) the biomass (1), optionally impregnated in step a), in the presence of water vapor (2), for example of the steam explosion cooking type, to obtain a mixture comprising the pretreated biomass (5) and water vapor (4a), c) a step of separating the mixture of pretreated biomass and water vapor to obtain on the one hand the pretreated biomass (5) and on the other hand water vapor (4a), d) a step of condensing (17) the water vapor (4a) from the cooking step b) into a liquid effluent comprising mainly liquid water (4b), e) a step of enzymatic hydrolysis (6) of the pretreated biomass (5), to obtain a hydrolyzed biomass (7) in the form of sugar(s), in particular monomeric,f) a fermentation step (8) of the hydrolyzed biomass (7) in the form of sugar(s), in order to obtain a mixture comprising a fermented biomass (9) comprising at least one alcohol in the form of a juice and a solid residue, then at least one treatment step aimed at treating this mixture or one of its components in order to extract, isolate and / or purify the fermented biomass, said treatment step, or at least one of them, comprising at least one washing step of said mixture or said solid residue obtained in step f), said washing step using at least part of the liquid effluent from condensation step d)., 2. Method according to claim 1, characterized in that it comprises, after the fermentation step f), at least two treatment steps: g) a solid / liquid separation step (10a) of the fermented biomass, in order to obtain a separate juice (12a) comprising at least this alcohol and a solid residue, h) a washing step (10b) of the solid residue with, as washing water, at least in part, the liquid effluent (4b) from the condensation step d) (17).

3. Method according to one of the preceding claims, characterized in that the water vapor (4a) separated in separation step c) is loaded with by-products resulting from the cooking (3) of the biomass from step b), in particular comprising at least one of the following by-products: furfural, sugar degradation compounds such as 5-hydroxymethylfurfural 5-HMF, one or more organic acids such as acetic acid.

4. Method according to claim 2, characterized in that all the liquid effluent (4b) from the condensation step d) (17) is used as washing water in the washing step (10b) h).

5. Method according to one of the preceding claims, characterized in that the washing step (10b) h) only uses as washing water the liquid effluent (4b) from the condensation step d) (17).

6. Method according to one of claims 1 to 4, characterized in that the washing step (10b) h) uses as washing water partly the liquid effluent (4b) from the condensation step d) (17) and partly a supply of other water (11), in particular in a volume proportion of 10 / 90 to 90 / 10.

7. Method according to one of the preceding claims, characterized in that the washing step (10b) h) uses as washing water at least in part the liquid effluent (4b) from the condensation step d) (17), said liquid effluent then being at a temperature between 30 and 60°C and / or at a pH between 2 and 4.

8. Method according to one of the preceding claims, characterized in that the steps (6) of enzymatic hydrolysis e) and (8) of fermentation f) are carried out simultaneously on the pretreated biomass (5).

9. Method according to one of the preceding claims, characterized in that it also comprises: i) a step of separation or purification, in particular distillation, of the fermented biomass, and in that step g) of solid / liquid separation and step h) of washing are carried out before or after said step i) of separation or purification.

10. Method according to one of the preceding claims, characterized in that the condensation step d) (17) is carried out by heat exchange of the water vapor with a fluid used in the method, in order to raise the temperature of said fluid.

11. Method according to one of the preceding claims, characterized in that step g) of solid / liquid separation (10a) is carried out by filtration, in particular using a pressing or draining device, such as a filter press or a vacuum filter, a belt filter, a belt press, a centrifugation, decantation or wringer device or the combination of at least two of these devices.

12. Installation for implementing the method according to one of the preceding claims, characterized in that it comprises: a) an optional impregnation device, in particular an impregnation reactor, of the biomass with a liquor, in particular acid, to obtain an impregnated biomass (1) b) a device for cooking the biomass, possibly impregnated with the device Impregnation step a), in the presence of water vapor (2), for example of the steam explosion cooking type, to obtain a mixture comprising the pretreated biomass (5) and water vapor, c) a device for separating the mixture of pretreated biomass and water vapor, to obtain on the one hand the pretreated biomass (5) and on the other hand water vapor (4a), d) a device for condensing the water vapor from cooking step b) into liquid effluent (4b), in particular a heat exchanger device, e) a device for enzymatic hydrolysis, in particular an enzymatic hydrolysis reactor, of the pretreated biomass, to obtain a hydrolyzed biomass (7) in the form of sugar(s), f) a device for fermenting the hydrolyzed biomass in the form of sugar(s), in particular a fermentation reactor, in order to obtain a mixture comprising a fermented biomass (9) comprising at least one alcohol in the form of a juice and a solid residue (13),said device being distinct from the enzymatic hydrolysis device or being common with it, then at least one treatment device aimed at treating this mixture or one of its components with a view to extracting, isolating and / or purifying the fermented biomass (12a), including at least one washing device using at least part of the liquid effluent (4b) from the condensation step d)., 13. Installation according to the preceding claim, characterized in that, downstream of the fermentation device f), it comprises two treatment devices: g) a device for solid / liquid separation of the fermented biomass, in order to obtain a separated juice (12a) comprising at least this alcohol, and a solid residue, in particular a pressing or draining device, such as a filter press or a vacuum filter, a belt filter, a belt press, a centrifugation, decantation or spin-drying device or the combination of at least two of these devices h) a device for washing the solid residue (13), possibly common with the solid / liquid separation device or separate from it, with, as washing water, at least in part, the liquid effluent (4b) from the condensation device d) (17).

14. Use of the method according to one of claims 1 to 11 for the treatment of lignocellulosic biomasses, such as wood, straw, agricultural residues, paper residues, and all dedicated energy crops, in particular annual or multi-annual plants such as miscanthus, with a view to producing alcohol-type biofuels or bio-sourced molecules.

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