Method for producing sugar syrup from residual lignocellulosic biomass

Abstract

A method for producing a sugar syrup containing fermentable sugars from lignocellulosic biomass containing paper waste, particularly printable paper, printed paper, or cardboard, comprising: (a) shredding the lignocellulosic biomass containing paper waste; (b) impregnating the lignocellulosic biomass containing paper waste, or the shredded lignocellulosic biomass obtained at the completion of step (a), in an aqueous medium; and (ii) a thermal pretreatment step carried out without the addition of acid at a temperature of 80°C to 150°C and a pH of 6.5 to 8.5 to obtain a pretreated product, wherein the impregnation and thermal pretreatment steps are simultaneous or followed by (i) and (ii).; (c) enzymatic hydrolysis of the pretreated product obtained at the completion of step (b) to convert cellulose and hemicellulose into a sugar syrup containing fermentable sugars; and (d) recovering the sugar syrup containing fermentable sugars obtained at the completion of step (c).

Description

Technical Field

[0001] The present invention relates to the field of production of fermentable sugars and relates to the use of residual lignocellulosic resources, such as paper / board types, as substrates for methods of preparing such sugars. The present invention particularly describes the methods and their treatment used to prepare raw materials in order to enable the production of sugar syrups, particularly purified glucose syrup, which can be used as raw materials, particularly in the biofuel or biotechnology industries.

[0002] In particular, the present invention relates to a method for producing a sugar syrup containing fermentable sugars, particularly a syrup containing glucose, from lignocellulosic biomass including paper waste, particularly printing paper, printed paper, chart paper, wrapping paper or cardboard. The present invention also relates to a sugar syrup containing fermentable sugars, particularly a syrup containing glucose, obtainable by the above method.

[0003] The use of the method for producing biosource molecules or biofuels, preferably ethanol, and the process for producing biofuels, particularly ethanol, are also the subject of the present invention.

Background Art

[0004] The lignocellulosic biomass currently mainly used as a source of fermentable sugars at the pilot or industrial scale is so-called 2G biomass (second generation), i.e., plant-type biomass such as forestry and agricultural industry residues (wheat straw, corn cobs and sugarcane bagasse) (Nizami et al., 2017). To date, the following limitations have been highlighted: - The scarcity of development of collection channels and grouping of sources; - Exposure to seasonal variations in quantity, quality, and availability; - Exposure to competition from soil fertilization in the fields and vegetation cover; - High hemicellulose and lignin content, more complex access to cellulose, and reduced glucose yield; - The need to apply cumbersome and costly pretreatment that can generate molecules that inhibit fermentation (HMF, furfural, ...) (Soltanian et al., 2020).

[0005] The use of paper and cardboard overcomes most of these limitations, and the initial pretreatment that virgin materials receive upstream in the production chain (in the paper industry during production) allows access to products with higher cellulose content in a less intensive and less complex way.

[0006] Conventional technologies include several types of processing methods for improving the quality of lignocellulosic biomass. All of these methods target the hydrolysis of cellulose and / or hemicellulose monomers that make up the biomass. Hydrolysis (Nizami et al., 2017) can be carried out as follows: - Biological or biochemical means using enzymes and / or microorganisms; - Thermochemical and / or mechanical means.

[0007] Non-biological methods include those using concentrated acid, gasification, hydrothermal decomposition, and thermal decomposition.

[0008] In the case of biological methods, the first step involves pre-treating the biomass to increase the digestibility of cellulose and release monomeric sugars (mainly glucose). Different pre-treatment techniques exist, including the following (Soltanian et al., 2020): - Method using dilute acid, - Method using solid acids, - Alkali method, - AVAP method, - Organosolve method, - Steam explosion, - Methods using supercritical water, - Extrusion molding.

[0009] The addition of chemical catalysts such as acids or bases in the pretreatment step leads to a significant increase in the accessibility of cellulose to hydrolytic enzymes, and therefore the yield of simple sugars released, such as glucose. The drawback of this pretreatment is, in addition to its cost, the risk of generating toxic molecules such as furfural or hydroxymethylfurfural (HMF), which can form rapidly at high temperatures. After this pretreatment, the chemical catalysts and their water-soluble degradation products, such as sugar molecules, must be extracted by separation methods such as ion chromatography or reverse osmosis (referred to as "downstream processing"), which result in high costs and technical constraints.

[0010] To overcome this limitation, methods that do not use (or use much less of) chemical catalysts have been developed for the pretreatment of plant fibers: steam explosion. By impregnating the matrix at high temperature / high pressure and then performing a rapid pressure release step, it becomes possible to separate polymers from sugars with greater efficiency. However, this method is applied to flows of materials with precisely controlled particle size and composition, and therefore requires grinding and fine screening steps. Consequently, sources of paper waste containing mixtures of materials with plastic and / or metallic impurities pose a risk of causing rapid damage to the steam explosion equipment.

[0011] The final step is the conversion of the sugar (after its purification). This often involves fermentation and distillation to reach high-value final products such as ethanol.

[0012] Processes utilizing hydrolysis by biological means can be classified into four subcategories depending on whether or not they group the basic steps of the method together (Parisutham et al., 2014): - "Separate Hydrolysis and Fermentation" (SHF) - "Simultaneous Saccharification and Fermentation" (SSF) - "Simultaneous saccharification and co-fermentation" (SSCF) - "Integrated Bioprocessing" (CBP).

[0013] The advantage of performing a combined process such as SSF, SSCF or CBP is that the number of steps and reactors can be reduced through the coexistence of an enzyme (or enzymes) capable of depolymerizing cellulose and a microorganism (or microorganisms) capable of converting simple sugars into the target molecule. This generally enables the required investment and thus the reduction of the manufacturing cost of the target molecule. In this case, the process is developed and optimized especially for a given molecule and market. This process most often uses genetically modified microorganisms.

[0014] The upgrading of paper to other target products such as sugars and / or ethanol is described in the prior art. For example, Patent Document 1 performs enzymatic hydrolysis and pretreatment with dilute acid. Patent Document 2 applies acid hydrolysis by continuous use of dilute acid and concentrated acid. Patent Document 3 uses fine spraying of biomass by mechanical pretreatment without acidic digestion. Patent Document 4 describes a method for preparing ethanol, especially a method including a step of preheating with high-temperature steam.

Prior Art Documents

Patent Documents

[0015]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Non-Patent Documents

[0016]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0017] The object of the present invention is to hydrolyze cellulose and, where applicable, hydrolyze hemicellulose contained in residual lignocellulosic biomass without relying on cumbersome pretreatment and purification methods, thereby obtaining an optimal mass yield while reducing impurities and operating costs associated with the use of chemical catalysts and simplifying subsequent so-called "downstream processing" steps (such as clarification, purification, and concentration steps).

[0018] The present invention has the specific object of developing a method for producing a sugar syrup containing fermentable sugars, particularly a syrup containing glucose, from lignocellulosic biomass containing paper waste, particularly waste from printing paper, printed paper, or cardboard. A further object of the present invention is to upgrade the above sugar syrup by producing biosource molecules or biofuels, preferably ethanol.

[0019] A further object of the present invention is to obtain platform molecules having a high added value (sugars or others) from paper-cardboard waste, which are particularly useful for producing biofuels and chemical molecules with less environmental impact and at low cost.

Means for Solving the Problems

[0020] In a first aspect, the present invention relates to a method for producing a sugar syrup containing fermentable sugars from lignocellulosic biomass containing paper waste, the method particularly comprising the following steps: a. Optionally, a step of pulverizing the lignocellulosic biomass; b. i. An impregnation step and ii. a thermal pretreatment step of the lignocellulosic biomass, wherein the impregnation step and the thermal pretreatment step are simultaneous or ii follows i continuously; c. An enzymatic hydrolysis step of the pretreatment product; and d. A step of recovering a sugar syrup containing fermentable sugars.

[0021] In a second aspect, the present invention relates to a sugar syrup containing a fermentable sugar, particularly a glucose syrup, which can be obtained by the method of the present invention.

[0022] In a third aspect, the present invention relates to the use of the present invention's method or syrup for producing biosource molecules or biofuels, preferably ethanol.

[0023] In a fourth aspect, the present invention relates to a process for producing biofuels, particularly ethanol. [Modes for carrying out the invention]

[0024] [Detailed description of the invention] Any reference to a range of values ​​in the specification and / or claims implies that the limits of the range (values) are included, unless otherwise specified.

[0025] The present invention relates to a method for producing a sugar syrup containing fermentable sugars, particularly a glucose syrup, from lignocellulosic biomass, including paper waste, particularly printing paper, printed paper, or cardboard, the method comprising the following steps: a. Optionally, a step of crushing the lignocellulosic biomass, including paper waste; bi. A step of impregnating the lignocellulosic biomass containing paper waste or pulverized lignocellulosic biomass obtained after step a. in an aqueous medium, preferably in water, and at ambient temperature; and ii. A heat pretreatment step to obtain a pretreatment product, carried out without the addition of acid at 80°C to 150°C, preferably 90°C to 130°C, more preferably 100°C or 120°C, at a pH of 6.5 to 8.5, specifically pH 6.5 to 8, more specifically pH 6.8 to 7.5, preferably at a neutral pH, wherein the impregnation and heat pretreatment steps are performed simultaneously, or i. is followed by ii; c. Enzymatic hydrolysis of the pretreatment product obtained after step b for converting cellulose and hemicellulose into sugar syrups containing fermentable sugars, particularly glucose-containing syrups; and, d. A step of recovering the sugar syrup containing fermentable sugars, particularly the glucose syrup, obtained after step c.

[0026] In one preferred embodiment, the present invention relates to a method for producing a glucose-containing syrup from lignocellulosic biomass, particularly including paper waste, printing paper, printed paper, or cardboard, the method comprising the following steps: a. Optionally, a step of crushing the lignocellulosic biomass, including paper waste; bi. A step of impregnating the lignocellulosic biomass containing paper waste or pulverized lignocellulosic biomass obtained after step a. in an aqueous medium, preferably in water, at ambient temperature; and ii. A heat pretreatment step to obtain a pretreatment product, carried out without the addition of acid at 80°C to 150°C and a pH of 6.5 to 8.5, specifically at a pH of 6.5 to 8, wherein the impregnation and heat pretreatment steps are performed simultaneously, or i. is followed by ii; c. Enzymatic hydrolysis of the pretreatment product obtained after step b for converting cellulose and hemicellulose into a glucose-containing syrup; and d. A step of recovering the glucose-containing syrup obtained after step c.

[0027] In the context of this invention, the term "sugar syrup" refers to a thick, viscous liquid containing sugar in solution. The term "sugar syrup" is interchangeable with the term "sugar juice." In one particular embodiment, the sugar syrup containing glucose also contains xylose in a smaller proportion than glucose. In one particular embodiment, the sugar syrup contains 70-85% glucose and 10-15% xylose.

[0028] In the context of this invention, the term “fermentable sugar” refers to simple sugars or mixtures thereof, such as glucose, fructose, arabinose, mannose, galactose, and xylose. These “simple sugars” can be fermented under the action of yeast or bacteria to produce alcohol. In particular, they are monosaccharides (i.e., sugars containing five or six carbon atoms), especially hexoses such as glucose. Preferably, “fermentable sugar” refers to monomeric fermentable sugars, i.e., those containing a single unit. More preferably, “fermentable sugar” contains glucose and a smaller proportion of xylose, or is essentially composed of them.

[0029] In the context of the present invention, the term "lignocellulosic biomass" refers to a substrate essentially composed of cellulose (30-70%), hemicellulose (5-35%), and lignin (5-25%), determined relative to the dry weight of the lignocellulosic biomass. In one particular embodiment, the lignocellulosic biomass is a substrate essentially composed of cellulose (30-70%), hemicellulose (5-25%), and lignin (5-25%). In another particular embodiment, the lignocellulosic biomass is a substrate essentially composed of cellulose (30-70%), hemicellulose (5-20%), and lignin (5-20%). In yet another particular embodiment, the lignocellulosic biomass is a substrate essentially composed of cellulose (30-70%), up to 18% hemicellulose, and up to 19% lignin. Cellulose is a glucose polymer, or hexose; hemicellulose is a polysaccharide essentially composed of pentoses (e.g., xylose and arabinose) and glucose; and lignin is a polymer rich in phenolic units. Cellulose is a major source of fermentable sugars. The "lignocellulosic biomass" used in this invention includes paper waste. The paper waste may have been recycled several times, for example up to seven times, and the average size of the fibers contained in this paper waste is generally 0 mm to 2 mm, more preferably 0.1 mm to 1.5 mm.

[0030] In one particular embodiment, the substrate providing lignocellulosic biomass is composed of paper waste.

[0031] (none)

[0032] In one particular embodiment, the substrate providing lignocellulosic biomass includes paper waste and a co-substrate.

[0033] In another specific embodiment, the substrate providing lignocellulosic biomass includes paper waste and is contained in or composed of more complex waste such as the fermentable fraction of household waste (FFHW). In a specific embodiment of the present invention using a lignocellulosic substrate contained in FFHW, the percentage of cellulose in the FFHW is less than 50% by weight, for example, 10 to 40% by weight. FFHW, and more generally the household waste in which it is contained, has a different composition depending on the region of the world being considered. FFHW can be used in the present invention to provide lignocellulosic biomass to be treated, insofar as the cellulose, hemicellulose, and lignin content, particularly that contributed by paper waste, provides a substrate in which the composition is within the proportions defined above. For example, FFHW that can be processed according to the present invention may include 10% to 20% by weight of paper, and / or 8% to 15% by weight of flat cardboard and / or 3% to 6% by weight of textiles, and / or 15% to 25% by weight of sanitary textile waste (considered separately from other textiles), for example, about 13% by weight, 10% by weight, 4.6% by weight, and 21% by weight, respectively, where these percentages are determined as dry weight percentages of the FFHW under consideration. The remaining fraction of the FFHW consists of horticultural waste or food waste (60% to 80%), which, where applicable, may also be related to other types of fibers such as wood residue. Together, the waste that forms the FFHW (also called the organic fraction from ROF or mechanobiological treatment of the residual organic fraction - MBT) can be used as a lignocellulose substrate for carrying out the method of the present invention. In addition to the fermentable fraction, household waste HW may also include composite materials, plastics, unclassified combustible materials, glass, metals, unclassified non-combustible materials, and slightly hazardous waste. This non-fermentable waste is typically discarded during the mechanobiological sorting process that enables the production of FFHW. Thus, FFHW can be defined considering the mode in which it is obtained: the result of household waste collection, followed by mechanobiological separation to ultimately retain only the fine organic fraction of this waste.

[0034] In a particular embodiment of the present invention, the substrate providing lignocellulosic biomass includes paper waste and FFHW as a co-substrate.

[0035] In one embodiment, the lignocellulosic biomass may include alternative or additional plant-type residues. Non-limiting examples of plant-type lignocellulosic biomass include residues from forestry and agricultural industries such as wheat straw, corn cobs, and sugarcane bagasse, and residues from the agrofood industry. In one particular embodiment, when the lignocellulosic biomass includes plant-type waste derived from forestry or agricultural industries, the respective percentages of hemicellulose and lignin by dry weight of the total biomass mixture are less than 19% and 18%, respectively. In one particular embodiment of the present invention, the lignocellulosic biomass contains little to no plant-type waste (by dry weight %) derived from forestry or agricultural industries.

[0036] In the context of the present invention, paper waste includes or essentially consists of paper and cardboard waste. Generally, paper and cardboard waste corresponds to a mixture of paper and cardboard waste, which may include, by weight relative to dry weight, 5 to 60% chipboard, between 5% and 60%, particularly between 10 and 20%, of office paper type printed paper, and between 5% and 100% corrugated cardboard.

[0037] In a particular embodiment of the present invention, the paper waste is selected from the group consisting of paper (in particular printed paper or printing paper), boxes, newspapers, magazines, and papermaking sludge. This waste may contain undesirable impurities such as plastics and metals, as well as ink components, which are present in very small amounts.

[0038] In one preferred embodiment of the present invention, the paper waste is a mixture of low-quality lignocellulose waste (paper, cardboard type) in the following average proportions (+ / - 5%, the total proportion not exceeding 100%) by total dry weight: - Chipboard: 20% - Newspaper: 30% - Magazines 20% - Office paper: 10% - Cardboard: 20%.

[0039] In one particular embodiment of the present invention, the lignocellulosic biomass before crushing and / or impregnation, i.e., the “raw material” lignocellulosic biomass, consists of paper waste in a total content by dry weight of biomass between 70% and 100% by weight, particularly between 85% and 96% by weight.

[0040] In another specific embodiment of the present invention, the lignocellulosic biomass before grinding and / or impregnation, i.e., the “raw material” lignocellulosic biomass, consists of, for example, FFHW with a total dry matter content of 45% to 55% by weight, particularly about 50% by weight, of the biomass.

[0041] In another embodiment of the present invention, where the lignocellulosic biomass described above consists of a mixture of paper waste and FFHW, the total dry matter content varies between 50 and 96% by weight of the biomass depending on the addition ratio of the substrate and co-substrate.

[0042] The impregnation step (also called pulping) bi allows for the acquisition of a relatively homogeneous suspension free from drying and / or floating aggregates. Generally, the aggregates are little to no hydrolyzed in the subsequent enzymatic hydrolysis step c. In a particular embodiment of the present invention, the impregnation step bi is carried out for 5 to 30 minutes, preferably 15 minutes. The impregnation step bi may include stirring. Taking the necessary steps to obtain the desired homogenization is within the realm of the art. For example, mixing can be carried out until floating blocks, especially those larger than 10 cm in size, disappear, and such disappearance can be determined by visual inspections performed at predetermined and / or regular intervals within the reactor.

[0043] The impregnated biomass obtained after process bi typically has a total dry matter content of 5% to 30%, and especially 10% to 20%.

[0044] In a particular embodiment of the present invention, especially in the case of compressed raw material biomass such as paper / cardboard bales, the method may include step a for crushing the raw material lignocellulosic biomass, which includes paper waste.

[0045] In a particular embodiment of the method of the present invention, lignocellulosic biomass is provided in the form of paper waste.

[0046] In a particular embodiment of the method of the present invention, lignocellulosic biomass is provided in the form of a fermentable fraction (FFHW) of household waste.

[0047] In one specific embodiment of the present invention, the method described above does not include a step of crushing the lignocellulosic biomass, including paper waste. This provides better tolerance to the quality of the biomass being fed in, and plastic or metallic impurities do not affect the effectiveness or proper implementation of the method.

[0048] In the context of the present invention, lignocellulosic biomass is subjected to heat pretreatment to enhance its reactivity to enzymatic hydrolysis and to increase enzymatic access to cellulose.

[0049] In prior art, acidic or basic chemical agents are typically added to lignocellulosic biomass to improve (catalyze) cellulose release. However, the presence of chemical catalysts presents a significant obstacle from a purification standpoint and strongly impacts the economic feasibility of this activity.

[0050] Therefore, the heat pretreatment step b.ii. is carried out without the addition of acid, preferably without a chemical catalyst. This makes it possible to obtain an optimal mass yield while preventing the formation of inhibitory molecules (particularly in relation to the fermentation process), reducing operating costs associated with the use of chemical catalysts, and reducing the complexity of downstream processing solutions.

[0051] Advantageously, the heat pretreatment step b.ii. is carried out at a pressure of 1 to 5 bar, preferably 1.5 to 3 bar, and more preferably about 2 bar.

[0052] Typically, the heat pretreatment step b.ii. is carried out for 10 to 120 minutes, preferably 10 to 60 minutes, and more preferably 30 minutes.

[0053] The above impregnation bi and heat pretreatment b.ii steps can be performed simultaneously or sequentially, particularly as a function of the density of the lignocellulosic biomass. If the impregnation bi and heat pretreatment b.ii. steps are performed simultaneously, these two steps may be carried out over a total time of 10 to 120 minutes, preferably 10 to 60 minutes, and more preferably 30 minutes.

[0054] In a particular embodiment of the present invention, the impregnation step bi and the heat pretreatment step b.ii. are carried out simultaneously, for example, in the same reactor, particularly in the presence of highly loosened lignocellulosic biomass such as uncompressed paper.

[0055] In another preferred embodiment of the present invention, the impregnation step bi and the heat pretreatment step b.ii. are carried out sequentially, for example, in two different reactors. The impregnation step bi is therefore followed by the heat pretreatment step b.ii. In this case, the homogenization obtained in the impregnation step is better controlled. This has the advantage of making the biomass more uniform and more receptive to the action of enzymes, while ensuring the inactivation of the initially present microorganisms (especially bacteria).

[0056] In the context of the present invention, the pre-treatment product obtained after step b. may also be referred to as “paste” or “slurry.” This means, for example, that pieces of paper or cardboard are no longer visible to the naked eye.

[0057] In some cases (optionally), a freeze and / or thaw and / or pasteurization step may be performed after step b. to limit the risk of contamination in the subsequent enzymatic hydrolysis step, which may lead to a loss of yield.

[0058] In one particular embodiment of the present invention, the enzymatic hydrolysis step c is carried out using an enzyme cocktail such as a mixture of cellulose-degrading enzymes and / or hemicellulose-degrading enzymes, particularly a mixture of cellulase and hemicellulase.

[0059] Cellulases can be selected from the group formed by endocellulase, exocellulase, β-glucosidase, and mixtures thereof.

[0060] Hemicellulases can be selected from the group formed by xylanases, xylosidases, endoglucanases, endoxylanases, endoxylanases, and β-xylosidases, as well as from several arabinofuranosidases and esterases and mixtures thereof.

[0061] Preferably, the mixture of cellulose-degrading and / or hemicellulose-degrading enzymes is selected from Ctech3® (Novozymes), Deltazym® (WeissBioTech), and Isobake CX®, and more preferably Ctech3®.

[0062] Typically, hydrolysis step c is carried out using 10 to 60 mg of enzyme per g of biomass, preferably 10 to 60 mg of enzyme per g of cellulose, and more preferably 15 to 25 mg of enzyme per g of cellulose.

[0063] In a particular embodiment of the present invention, the yield of enzymatic hydrolysis is 40% to 80%, typically 60% to 70%. Theoretically, the yield is calculated as the ratio of the amount of monomeric sugar released to the total molar amount initially available. In practice, the inventors measured the amount of glucose released in relation to the cellulose content (cellulose content = amount by weight in the total amount of raw materials).

[0064] This enzymatic hydrolysis step c allows for the hydrolysis of sugars derived from both the cellulose and hemicellulose fractions.

[0065] In one particular embodiment of the present invention, step c includes a pre-pH adjustment step to obtain an acidic pH, for example, a pH of about 5. The pre-treated product obtained after step b, which may be frozen and / or thawed and / or pasteurized, generally has a basic or neutral pH, meaning that pH adjustment is generally performed by adding an acid such as sulfuric acid or phosphoric acid, preferably sulfuric acid.

[0066] Compared to conventional processing methods, such as acid-based treatment of 2G biomass, the sugar syrup produced after enzymatic hydrolysis has a lower mineral content, facilitates the purification process, does not generate fermentation inhibitory complexes such as furfural or HMF, and allows for an increase in sugar release yield.

[0067] In one particular embodiment of the present invention, a sugar syrup containing fermentable sugars recovered after step d, particularly a syrup containing glucose, has at least one of the following features: - Total dry matter content of 5% to 25% by weight, preferably 5% to 20% by weight, and especially 10% to 20% by weight; - Free glucose content of 60% to 75% by weight of the dry matter, typically 65% ​​to 70% by weight; - A glucose-to-total sugar ratio of 60% to 90% by weight, preferably 80% to 90% by weight, relative to the weight of the dry matter.

[0068] In the context of this invention, dry matter content refers to all dry matter present in the product, measured, for example, according to the protocol described in standard ISO 6731. Free glucose content refers to the amount of glucose (in dry matter) relative to the total amount of substance (dry matter) contained in the product, and this parameter is conventionally measured by liquid-phase HPLC or an equivalent analytical method and then estimated by calculation.

[0069] In one particular embodiment of the present invention, the above method further includes the following steps: e. A clarification step for separating solid residue from liquid residue, comprising a clarification step of a sugar syrup containing fermentable sugars, particularly a glucose syrup, recovered after step d, preferably comprising a rough screening, a fine screening, and / or a sedimentation and / or centrifugation step. f. A purification step, preferably on activated carbon, of the sugar syrup containing fermentable sugars obtained after step e, particularly a syrup containing glucose, and g. A step to recover the purified sugar syrup containing fermentable sugars, particularly the purified syrup containing glucose, obtained after step f.

[0070] Advantageously, clarification step e. includes a microscreening and / or sedimentation and / or centrifugation step. In a particular embodiment, clarification step e. includes a microscreening, sedimentation and centrifugation step.

[0071] The purification step f of the present invention enables the removal of residual substances in the suspension, such as some ions and / or salts, as well as the capture of soluble contaminants such as metal salts and ink residues.

[0072] Advantageously, the purification step f. is carried out by filtration on activated carbon. Non-limiting examples of activated carbon that can be used in step f. are powdered Colorsorb 620 (Jacobi), granular BGX (Chemviron), powdered CPW (Chemviron), and CXV (the former carbon).

[0073] Therefore, for purification, a simple clarification process (solid-liquid separation) combined with passage through activated carbon appears to be sufficient. This is advantageous compared to conventional methods, particularly those for 2G sugars that typically require a purification step using ion chromatography.

[0074] In one particular embodiment of the present invention, after the purification step f. or the recovery step g., the above method further includes: h. A step of concentrating the purified sugar syrup containing fermentable sugars obtained after step f. or g., particularly the purified syrup containing glucose, preferably using a vacuum evaporator, more preferably a forced recirculation or a flow-through thin-layer evaporator; and i. A step to recover the purified and concentrated sugar syrup containing fermentable sugars obtained after step h, particularly the purified and concentrated syrup containing glucose.

[0075] The concentration process, in particular, ensures the stability of the product by reducing the risk of contamination (especially bacterial contamination).

[0076] In one particular embodiment, a sugar syrup containing fermentable sugars recovered after step g. or i., particularly a syrup containing glucose, has at least one of the following characteristics: - Total dry matter content of 45% to 75% by weight, preferably 50% or 60% by weight; - Free glucose content of 60% to 75% by weight of the dry matter, typically 65% ​​to 70% by weight; - The ratio of glucose to total sugars, typically 75% to 85% by weight, and especially 80% by weight, relative to the dry weight.

[0077] In one preferred embodiment, a method for producing a glucose-containing syrup from lignocellulosic biomass, particularly including paper waste, printing paper, printed paper, or cardboard, comprises the following steps: a. A step of crushing the lignocellulosic biomass, including paper waste, if necessary; bi. An impregnation step of the lignocellulosic biomass containing paper waste or pulverized lignocellulosic biomass obtained after step a. in an aqueous medium, preferably in water, and at ambient temperature; and ii. A heat pretreatment step to obtain a pretreatment product, carried out without the addition of acid at 80°C to 150°C, preferably 90°C to 130°C, more preferably 100°C or 120°C, at a pH of 6.5 to 8.5, specifically pH 6.5 to 8, more specifically pH 6.8 to 7.5, preferably at a neutral pH, wherein the impregnation and heat pretreatment steps are performed simultaneously, or i. is followed by ii; c. Enzymatic hydrolysis of the pretreatment product obtained after step b, for converting cellulose and hemicellulose into a glucose-containing syrup; d. Recovery step for recovering the glucose-containing syrup obtained after step c; e. A clarification step for separating solid residue from liquid residue, comprising a syrup containing glucose recovered after step d, preferably comprising a rough screening, a fine screening, and / or a sedimentation and / or centrifugation step. f. A purification step on activated carbon to purify the glucose-containing syrup obtained after step e.; g. Recovery of the purified syrup containing glucose obtained after step f; h. A concentration step, preferably using a vacuum evaporator, more preferably a forced recirculation or a fall-film thin-layer evaporator, to concentrate the purified syrup containing glucose obtained after step g.; and, i. A step to recover the purified and concentrated syrup containing glucose obtained after step h.

[0078] The present invention also provides a sugar syrup containing fermentable sugars, particularly a glucose syrup, which can be obtained using the method of the present invention. - A ratio of glucose to total sugars of 70% to 90% by weight, or 75% to 85% by weight, preferably 80% to 85% by weight, of the dry matter; and / or The present invention relates to a syrup characterized by having a furfural or hydroxymethylfurfural (HMF) content of less than 5000 ppm, and more favorably less than 200 ppm.

[0079] The above syrup may contain components other than glucose, which are present in a proportion of 10% to 30% by weight of the dry weight. Non-limiting examples of the above components include sugars such as xylose, galactose, arabinose, and mannose, trace amounts of solvent, and trace amounts of ash.

[0080] The present invention also relates to a method of the present invention or the use of the syrup of the present invention for producing biosource molecules (molecules of bio-origin or derived from bio).

[0081] Non-limiting examples of biosource molecules of the present invention include sugars (monosaccharides), ethanol, isobutene, 1,3-propanediol, 2,3-butanediol, 3-hydroxypropionic acid, acetic acid, butyric acid, capric acid, citric acid, fumaric acid, malic acid, propionic acid, pyruvic acid, succinic acid, levulinic acid, 2,5-franzicarboxylic acid, sorbitol, and xylitol.

[0082] For example, the following molecules can be produced by the biological conversion of glucose and are described in the prior art: lactic acid (Xu et al., 2014; Yadav et al., 2020), acetic acid (Kondo et al., 1996), butyric acid (Fu et al., 2017), propionic acid (Wang et al., 2013), succinic acid (Ong et al., 2019), isopropanol (Ferreira dos Santos Vieira et al., 2020), isobutene (US20180057843, US9249430, WO2014086781), butanol (Cheng et al., 2019; Birgen et al., 2019), and farnesane (WO2007139924, WO2008045555).

[0083] The biosource molecule of the present invention is preferably selected from the group formed by lactic acid, acetic acid, butyric acid, propionic acid, succinic acid, isopropanol, and isobutene, and more preferably selected from the group formed by lactic acid, acetic acid, butyric acid, propionic acid, and isopropanol.

[0084] The present invention also relates to a method of the present invention or the use of the syrup of the present invention for producing biofuels, preferably ethanol.

[0085] The present invention also relates to a method for producing biofuels, particularly ethanol, comprising the steps of the present invention and a subsequent fermentation step for converting a sugar syrup containing fermentable sugars, particularly a glucose syrup, recovered after step g. or step i., into a biofuel, particularly ethanol.

[0086] In one particular embodiment of the present invention, the fermentation process is carried out by yeast and / or bacteria. The yeast can be selected from the group formed by yeasts of the genera Saccharomyces, Yarrowia, and Leuconostoc. The bacteria can be selected from the group formed by bacteria of the genera Bacillus, Lactobacillus, Acetobacter, Escherichia, Clostridium, and Zymomonas. Preferably, the fermentation process is carried out using a Saccharomyces yeast, preferably Saccharomyces cerevisiae. The bacteria can be selected from Clostridium acetobutylicum or Escherichia coli. In one particular embodiment, the yeast or bacteria is selected based on its ability to obtain alcoholic fermentation.

[0087] The fermentation process of the present invention can be carried out by yeast and / or bacteria capable of fermenting both hexoses and pentoses.

[0088] This fermentation process enables the conversion of sugars derived from both the cellulose and hemicellulose fractions into biofuels and, in particular, ethanol.

[0089] This fermentation process can be carried out before subsequent so-called "downstream processing" steps, specifically before clarification (e.), purification (f.), or concentration (h.).

[0090] In a particular embodiment of the present invention, the fermentation process is carried out in a reactor separate from that used in the enzymatic hydrolysis process (SHF process), or simultaneously in the same reactor (SSF, SSCF, CBP process), preferably in a reactor separate from that used in the enzymatic hydrolysis process (SHF process).

[0091] If the fermentation process is carried out simultaneously in the same reactor used for the enzymatic hydrolysis process, the method of the present invention does not include step d.

[0092] In one embodiment, after the fermentation step, the method may include a step to purify the biosource molecules or biofuels, particularly for ethanol, by distillation, for example. A clarification step may or may not precede the distillation step.

[0093] All of the embodiments described above can be combined with one another. [Examples]

[0094] The following examples are provided for illustrative purposes only and should not be construed as limiting the invention.

[0095] Example 1. Sugar syrup obtained after the heat pretreatment step and the enzymatic hydrolysis step. The sugar syrup obtained after the enzymatic hydrolysis step c of the method of the present invention has the following characteristics: - Total dry matter (TDM) content of 6.1%, - 70.7% free glucose, - Ratio of glucose to total sugars: 84.7%

[0096] The composition of this sugar juice is shown in Table 1 below. [Table 1]

[0097] Example 2. Sugar syrup obtained after the steps of solid-liquid separation (clarification), purification, and concentration. The sugar syrup obtained after step i of the method of the present invention has the following characteristics: - 59.79% total dry matter content, - 70.8% free glucose, - Ratio of glucose to total sugars: 80.5%

[0098] The composition of this sugar juice is shown in Table 2 below. [Table 2]

[0099] Example 3. Various tests related to the pretreatment process. The acid content of the pretreatment phase was tested. The results showed that optimal mass yield can be obtained by digestion without the use of acid (Table 3).

[0100] [Table 3]

[0101] These tests reveal the following: - The best digestion rate is obtained from paper treated at 120°C / 60 minutes without the use of acid. - The next best pretreatment is phosphoric acid, followed by sulfuric acid.

[0102] The results are shown in Table 4. [Table 4]

[0103] Example 4. Study of pH sensitivity We investigated the pH sensitivity of the flow of digested paper and cardboard. The results are shown in Table 5.

[0104] [Table 5]

[0105] Example 5. Study of dose-effect (enzyme concentration) A study was conducted on the dose-effect relationship between the flow of paper and cardboard after digestion. The results are shown in Table 6.

[0106] [Table 6]

[0107] Example 6. Tests using different enzyme cocktails. Three different cocktails were used on repulped pre-treated paper in the presence of 20 mg of enzyme protein / cellulose (g). The results are shown in Table 7.

[0108] [Table 7]

[0109] Example 7. Test using different activated carbons Four types of activated charcoal were tested to purify the sugar syrup after hydrolysis and clarification: - Colorsorb 620 in powder form by Jacobi - BGX in granular form by Chemviron - CPW in powder form by Chemviron - CXV (the previous carbon, frequently used in ARD).

[0110] The results are shown in Table 8. [Table 8]

[0111] Example 8. Fermentation alone We tested the propagation of wild-type strains of Saccharomyces cerevisiae capable of converting free glucose to ethanol using two unpurified and unconcentrated sugar syrups. In the first stage, the test was performed after clarification (SHF) of the sugar syrup, and in the second stage, yeast was added directly during or at the end of the hydrolysis process so that fermentation could be carried out in the same reactor (SSF#2 and SSF#1, respectively). The results obtained are shown in Table 9.

[0112] [Table 9]

[0113] Example 9: Comparison of fermentation of the sugar syrup according to the present invention with a reference syrup containing the same amounts of glucose and xylose derived from a conventional channel.

[0114] Sugar-containing syrups (called sugar syrups) produced from paper and cardboard could be tested with the yeast strain Saccharomyces cerevisiae (Cellux 4 strain), which is commercially available from Lesaffre for ethanol production. Fermentation tests were performed in Erlenmeyer or Schott flasks at two given sugar concentrations: 140 and 210 g / kg of medium (corresponding to the accumulation of glucose and xylose), which were named TAV8 and TAV12, respectively. A reference sugar syrup (called 1G) containing the same amounts of glucose and xylose was prepared and tested under the same conditions.

[0115] The purpose of comparing fermentation results was to demonstrate the quality of the sugar syrups obtained from the present invention and the absence of inhibitory effects during fermentation, compared to the use of glucose and xylose syrups obtained from conventional channels, i.e., 1G resources (i.e., first generation) consisting particularly of beet root, wheat, and sugarcane sugar.

[0116] Ethanol production was monitored by mass loss related to CO2 production, which is directly correlated with ethanol production. The actual final concentration was verified by HPLiC at the end of the experiment.

[0117] The results are shown in Table 10 below. The observed conversion yields demonstrate very high performance, highlighting the potential of these sugars, produced from paper and cardboard, to integrate into the industrial channel for ethanol production.

[0118] [Table 10]

[0119] [References] Nizami et al.,Bioresource Technol.2017,241,1101-1117; Soltanian et al.Energy Conversion and Management 2020,212,112792; Parisutham et al.Bioresource Technol.2014,161,431-440; Xu et al.Bioresource Technol.2014,153,23-29; Yadav et al.Bioresource Technol.2020,11,100423; Kondo et al.J.Ferment.Technol.1996,81(1),42-46; Fu et al.Bioresource Technol.2017,234,389-396; Wang et al.Bioresource Technol.2013,137,116-123; Ong et al.,Biochem Eng.J.2019,148,108-115; Ferreira dos Santos Vieira et al.Fuel 2020,263,116708; Cheng et al. Bioresource Technol. 2019, 284, 415-423; Birgen et al. Biochem Eng. J. 2019, 147, 110-117.

Claims

1. A method for producing a sugar syrup containing fermentable sugars from lignocellulosic biomass including paper waste selected from the group consisting of printing paper, printed paper, and cardboard, comprising the following steps b, c, and d, namely, b. i. An impregnation step of the lignocellulosic biomass, including paper waste, in an aqueous medium; and ii. A heat pretreatment step to obtain a pretreatment product, carried out without the addition of acid at a temperature between 80°C and 150°C and a pH between 6.5 and 8.5, wherein the impregnation and heat pretreatment steps are performed simultaneously, or i. is followed by ii; c. Enzymatic hydrolysis of the pretreatment product obtained after step b, for converting cellulose and hemicellulose into a sugar syrup containing fermentable sugars; and, d. Recovery of the sugar syrup containing fermentable sugar obtained after step c; A method that includes the following:

2. The method according to claim 1, characterized in that the lignocellulosic biomass before impregnation has a total dry matter content of 70% to 100% by weight of the biomass and is composed of paper waste, or has a total dry matter content of 45% to 96% by weight of the biomass and is composed of waste consisting of a mixture of paper waste and a co-substrate.

3. The method according to claim 1 or 2, characterized in that the heat pretreatment step b. ii. is performed at a pressure between 1 and 5 bar (0.1 and 0.5 MPa).

4. The method according to any one of claims 1 to 3, characterized in that the heat pretreatment step b. ii. is performed for 10 to 120 minutes.

5. The method according to any one of claims 1 to 4, characterized in that the enzymatic hydrolysis step c is carried out by a mixture of a cellulose-degrading enzyme and / or a hemicellulose-degrading enzyme.

6. The sugar syrup containing fermentable sugars recovered after step d has the following characteristics: - The total dry matter content must be between 5% and 25% by weight; - The free glucose content is between 60% and 75% by dry weight; - The ratio of glucose to total sugars is between 60% and 90% by dry weight; The method according to any one of claims 1 to 5, characterized in that it has at least one of the features of the above.

7. The following steps, namely, e. A clarification step of the sugar syrup containing fermentable sugars recovered after step d, in order to separate the solid residue from the liquid residue; f. Purification step of the sugar syrup containing fermentable sugar obtained after step e; and g. Recovery of the purified sugar syrup containing fermentable sugars obtained after step f; The method according to any one of claims 1 to 6, further comprising the following:

8. After the purification step f, h. Concentration step of the purified sugar syrup containing fermentable sugar obtained after step f; and i. A step to recover the purified and concentrated sugar syrup containing the fermentable sugar obtained after step h; The method according to claim 7, further comprising:

9. The method according to claim 7, characterized in that the purification step f is carried out by filtration on activated carbon.

10. The method according to any one of claims 1 to 9, wherein the lignocellulosic biomass is provided in the form of paper waste.

11. The method according to any one of claims 1 to 9, wherein the lignocellulosic biomass is provided in the form of a fermentable fraction (FFHW) of household waste.

12. The sugar syrup containing fermentable sugars recovered after step g. or i. has the following characteristics: - The total dry matter content must be between 50% and 75% by weight; - The free glucose content is between 60% and 75% by dry weight; - The ratio of glucose to total sugars is between 70% and 90% by dry weight; The method according to any one of claims 7 to 9, characterized in having at least one of the features of the above.

13. The method according to any one of claims 1 to 12, characterized in that the sugar syrup containing fermentable sugar is a syrup containing glucose.

14. A method according to any one of claims 1 to 12, The method further includes step a before step b, wherein step a is a pulverization step of lignocellulosic biomass including paper waste.

15. The method according to any one of claims 1 to 12 for producing a biosource molecule selected from the group consisting of lactic acid, acetic acid, butyric acid, propionic acid, succinic acid, isopropanol, and isobutene.

16. A method according to any one of claims 1 to 12 for producing biofuel.

17. A method for producing ethanol, Each step of the method according to claim 7 or 8, A subsequent fermentation step to convert the sugar syrup containing fermentable sugars recovered after step g. or i. into ethanol, Methods that include...

18. The method according to claim 17, characterized in that the fermentation step is carried out by yeast and / or bacteria.

19. The method according to claim 17 or 18, wherein ethanol is produced in a yield greater than 40% as measured by HPLC relative to sugar.

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