Method for producing biogas from fibrous substrates

Abstract

Disclosed is a method of producing biogas from a fibrous substrate, comprising biologically pre-treating woven, non-woven or agglomerated and comminuted fibrous substrate by solid state fermentation using one or more filamentous fungal strains, more particularly using one or more saprophytic filamentous strains, producing biogas from the pre-treated fibrous substrate, forming biogas residues, and collecting the biogas residues.

Description

TECHNICAL FIELD

[0001] The present invention relates to a method for producing biogas from a fibrous substrate, comprising:

[0002] - biologically pre-treating the fibrous substrate, forming a biologically pre-treated fibrous substrate,

[0003] - transferring the biologically pre-treated fibrous substrate to a biogas production plant,

[0004] - producing biogas from the pre-treated fibrous substrate, forming biogas residue,

[0005] - collecting the biogas residue. BACKGROUND

[0006] Such a biogas production method is well known in the prior art, such as the production of biogas from plant waste or wood waste.

[0007] In this case, a biological pre-treatment has been implemented instead of a mechanical or chemical pre-treatment and involves the use of enzymes to pre-treat the waste in order to facilitate the attack of methanogenic microorganisms in the biogas production plant.

[0008] Indeed, mechanical / physical pre-treatment or chemical pre-treatment is generally necessary to achieve a biogas production yield to make the plant profitable. Unfortunately, these pre-treatments still require energy (shredding, heating, pressurization) or products (such as bases, sometimes strong bases or acids) to attack the waste. In the case of chemical treatment, although a lot of efforts have been made to recover these alkaline and acidic liquid streams, these treatments still consume water and generate a liquid phase that also needs to be treated. Furthermore, the pre-treated waste generally needs further treatment (neutralization, heat treatment, etc.) before entering the biogas production plant. It is for these reasons, among others, that some authors have turned to biological pre-treatment using enzymes, which have proven quite effective in increasing the biogas yield of the waste, but at the cost of significant additional production costs. Enzymes are relatively expensive substances, and in order to function optimally, they also require quite stringent temperature and pH conditions, which make their industrial application risky and are not currently common for most substrates suitable for biogas production. Authors generally report them for complex substrates in which the carbonaceous material is not easily accessible to the bacteria in the biogas production plant.

[0009] Substrates that are difficult to exploit the carbonaceous material include wood waste, but also textile waste, which has become a major challenge in waste management.

[0010] In 2021, the global production of textiles exceeded 149 million tons. In Europe, textile consumption has grown by more than 40% over the past twenty years, with an estimated 11 kg of textiles being thrown away per resident per year on average. Only 38% of textile waste is collected and sorted for potential reuse, with an estimated 1% being recycled and 87% being incinerated or buried in landfills.

[0011] One of the main problems with textile waste is its diversity. Indeed, not only are there different types of waste, but there are also many types of textiles, with many types of fibers mixed together to form a textile.

[0012] While there are currently some solutions for textile production waste (cutting waste, defective materials, production leftovers, etc.), the nature of which is well known and controlled, some types of textile waste pose a major problem for recycling.

[0013] Currently, for textiles in clothing, the existing solutions include mechanical sorting to recover clothing that can be resold second-hand. For other textiles, more advanced sorting is done manually or by optical fiber based on the composition of the textile. Textile waste from furniture is currently not recycled, but its potential to generate heat is exploited.

[0014] In addition, although there are physical-chemical treatments to weaken natural fibers so that they can be spun, the mixtures of synthetic and natural fibers found in mattress covers and other net curtains are a source of plastic fibers that cannot be developed using existing technologies.

[0015] In addition, while in some cases the mattress cover is separated from the other parts of the mattress, this is not always the case, depending on the technology available to the waste recycling center responsible for the recycling. In addition, some centers shred the mattress with their mattress cover, removing the metal parts, thus producing a shredded material consisting of a mixture of shredded mattress cover and synthetic or natural foam. SUMMARY

[0016] The invention aims to overcome the drawbacks of the prior art by providing a method for producing biogas that provides a method for recycling complex waste such as mattress waste, interior decoration waste, end-of-life textile waste, textile waste produced from upholstery fabric, etc.

[0017] To address this problem, the present invention provides a method for producing biogas, as described at the outset, characterized in that the biological pretreatment of a fibrous substrate involves solid-state fermentation using one or more filamentous fungal strains, more specifically one or more saprophytic filamentous fungal strains, even more specifically selected from Basidiomycetes and Ascomycetes, to shred woven, non-woven, or aggregated fibrous substrates into fragments, wherein the biologically pretreated fibrous substrate is shredded fibrous substrate colonized by the at least one fungal strain.

[0018] As can be seen, the method according to the invention provides a biological pretreatment of fibrous substrates with several advantages. First, pretreatment using one or more fungal strains via solid-state fermentation does not require large amounts of water, chemicals, or expensive reagents, and provides a structural solution without the need for substantial investment in basic equipment. Fungal strains are known to digest compounds that are particularly difficult to utilize, or even particularly contaminated or toxic compounds, and their activity opens up the fibrous structure, facilitating the activity of methanogenic microorganisms. Furthermore, fungal strains feed on carbonaceous material, thus allowing them to grow and thereby reduce the proportion of complex and unusable fibers in the fibrous substrate by producing biomass more readily digestible by methanogenic microorganisms, namely mycelium and other fungal compounds. Therefore, after pretreatment with one or more fungal strains, the proportion of complex substrates available for digestion on the usable substrate is more favorable.

[0019] Advantageously, in the method according to the invention, one or more fungal strains include at least one fungal strain with high colonization capacity, which is selected from the genera *Ganoderma*, *Ganoderma*, *Ganoderma*, *Ganoderma*, *Ganoderma*, *Pleurotus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Sulphurella*, *Pterocarpus*, *Lentinula*, *Fusarium*, *Aspergillus*, *Trichoderma*, *Penicillium*, *Cladosporium*, *Chaetoceros*, and *Acer spp.* Specifically, the following species are preferred: *Agrocybe* sp., *G. anoderma* sp., *G. applanatum*, *G. boninense*, *G. lucidum*, *G. resinaceum*, *G. sessile*, *Trametes* sp.; *T. pubescens*, *T. suaveolens*, *T. versicolor*, *Pleurotus* sp., *P. albidus*, *P. citrinopileatus*, *P. djamor*, *P. eryngii*, *P. ostreatus*, *P. ostraceus florida*, and *P. ostraceus*. The fungal strains include *Pleurotus sajorcajucaju*, *Pleurotus salmoneostramineus*, *Fomitopsis pinicola*, *Fomitopsis pilosula*, *Fomitopsis thunbergii*, *Fomitopsis sulfida*, *Inonotus birchii*, *Lentinula dongzhiensis*, *Lentinula giganteus*, *Lentinula squarrosulus*, and *Lentinula tigrinus*, *Fusarium* sp., *Fusarium solani*, *Aspergillus* sp., *Aspergillus oryzae*, *Aspergillus niger*, *Aspergillus flavus*, *Aspergillus terreus*, *Trichoderma* sp., *Trichoderma reesei*, *Trichoderma viride*, *Trichoderma longipes*, *Cladosporum* sp., *Chaetomium* sp., and *Chaetomium globosum*. This provides a wide range of fungal strains and a large amount of biomass that can be used by methanogenic microorganisms for methane production or as a culture medium. Furthermore, during colonization, the fungal strain utilizes the carbonaceous material in the fibrous substrate and begins to digest it. In this way, at least one fungal strain can transform carbonaceous material that is difficult to utilize into carbonaceous material that is more readily available to methanogenic microorganisms.

[0020] Advantageously, according to the present invention, the one or more fungal strains include at least one enzyme-producing fungal strain selected from strains belonging to the genera *Leptochloa*, *Ganoderma*, *Ganoderma*, *Pleurotus*, *Fomitopsis*, *Pterocarpus*, *Fomitopsis*, *Pterocarpus*, *Sulphurella*, *Fomitopsis*, *Lentinula*, *Fusarium*, *Aspergillus*, *Trichoderma*, *Penicillium*, *Cladosporium*, *Chaetoceros*, and *Acer spp.*, more specifically selected from *Leptochloa*, *Ganoderma*, *Ganoderma lingulata*, *Ganoderma longifolia*, *Ganoderma lucidum*, *Ganoderma sinense*, *Ganoderma sinense*, *Ganoderma sinense*, *Pterocarpus ... Mushrooms such as *Pleurotus ostreatus*, *Tricholoma matsutake*, *Pleurotus eryngii*, *Pleurotus ostreatus*, *Pleurotus eryngii*, *Pleurotus ostreatus*, *Pleurotus ostreatus*, *Pleurotus ostreatus*, *Pleurotus ostreatus*, *Pleurotus ostreatus*, *Pleurotus ostreatus*, *Pleurotus ostreatus*, *Pleurotus eryngii ...

[0021] In some cases, according to the present invention, it is envisioned that the one or more fungal strains are a mixture of one or more strains with high colonization capacity and one or more enzyme-producing strains.

[0022] In the context of this invention, “biogas” preferably refers to biogas, preferably a gas comprising methane, other gases optionally usable as fuel, and carbon dioxide, the latter advantageously post-treated (capture, supercritical extraction, reaction to form other molecules).

[0023] In a preferred embodiment of the invention, the aggregated, woven or nonwoven shredded fiber substrate comprises fibers selected from natural plant or animal textile fibers, semi-synthetic textile fibers or polymer textile fibers and lignocellulose fibers.

[0024] In the context of this invention, the term "natural plant textile fiber" refers to natural textile fibers from plants such as Manila hemp (abaca), sugarcane bagasse, bamboo, coconut, cotton, flax, hemp, jute, raffia leaf fiber, ramie, rattan, wood, plants of the genus Furcraea andina (Asparagaceae family), Ceiba pentandra, Agave sisalana, kenaf, and pineapple hemp.

[0025] The term "natural animal textile fiber" refers to natural textile fibers from alpaca, Angora, foot silk, camel hair, cashmere, catgut, guanaco, hair or fur, llamas, mohair, pashmina, qiviuk, silk, which can be spider silk, silkworm silk, wool, llamas, yaks, etc.

[0026] For the purposes of this invention, the term "semi-synthetic fiber" refers to fibers made from cellulose acetate, cellulose diacetate, cellulose triacetate, lyocell, modal, etc.

[0027] The term "polymer textile fiber" refers to acrylic fiber, aramid fiber (Twaron, Kevlar, Nomex, Technora), microfiber, polyamide fiber, polyester fiber, polyolefin fiber, high molecular weight polyethylene fiber, elastic fiber, polyaryl ester fiber (vectran fibre), polyvinyl alcohol fiber (vinalon fibre), poly(p-phenylenebenzobisoxazole) fiber (zylon fibre), etc.

[0028] Weidmann published this classification in 2010.

[0029] For the purposes of this invention, the term "lignocellulose fiber" refers to a fiber composed of lignin, hemicellulose and cellulose in different proportions, derived from forestry, agricultural operations and waste (furniture wood, chipboard, etc.).

[0030] The terms "shredded fiber substrate formed from said fibers in an agglomerated, woven, or nonwoven form" or "fiber substrate in fragment or granular form formed from said fibers in an agglomerated, woven, or nonwoven form" refer to agglomerated, woven, or nonwoven fibers, typically textile or lignocellulose fibers, that have undergone a step of reducing their size to form fragments. This size reduction can include shredding using a shear shredder, guillotine cutter, pulverizer, jaw shredder, or even a shredder. This shredding step occurs before the fiber substrate is supplied. In some cases, the invention also contemplates performing an additional size reduction step before the wetting step, if this proves useful, for example when the size distribution of the fiber substrate in fragment or granular form formed from said fibers is too large, or when the average size of the fragments is too large.

[0031] Advantageously, the aggregated, woven or nonwoven fibrous substrate is the residue of pulverized recycled textiles, more specifically the residue of pulverized recycled furniture textiles, recycled mattresses, bathroom or bedding, clothing textiles, textile production waste or waste, interior decorations and mixtures thereof.

[0032] The term "upholstery" refers to products such as cushions, sofas, and soft furnishings, which typically consist of a mixture of textile materials and upholstery foam.

[0033] More specifically, according to the invention, the aggregated, woven or nonwoven fibrous substrate is a residue of shredded recycled textiles selected from furniture, mattresses and upholstery textiles, and has a synthetic foam content of 10% to 80%.

[0034] In another embodiment of the invention, the agglomerated, woven or nonwoven fibrous substrate is a residue of pulverized lignocellulose components, such as a residue of pulverized fiberboard.

[0035] In a preferred embodiment of the invention, the fiber substrate comprises a certain proportion of synthetic fibers, semi-synthetic fibers, synthetic foams (such as PU foam), and natural plant or animal fibers, and wherein the collected biogas residue is rich in synthetic fibers and plastic materials in proportions exceeding 85% by weight relative to the weight of the biogas residue.

[0036] In another preferred embodiment of the invention, the biological pretreatment step includes:

[0037] - The fiber substrate is adjusted to obtain an adjusted fiber substrate containing 60% to 80% by weight of water relative to the weight of the adjusted fiber substrate.

[0038] - The conditioned fiber substrate is sterilized to form a sterilized conditioned fiber substrate.

[0039] - Cool the sterilized and conditioned fiber substrate for 12 to 24 hours.

[0040] - Inoculating the sterilized and conditioned fiber substrate with mycelial strains of at least one seed-borne mycelium at a ratio of 0.5% to 10% by weight, even more particularly 1% to 7% by weight, and most particularly 3% to 5% by weight relative to the weight of the sterilized and conditioned fiber substrate, thereby obtaining an inoculated sterilized and conditioned fiber substrate; - Mixing the inoculated sterilized and conditioned fiber substrate to obtain a homogeneous inoculated sterilized and conditioned fiber substrate.

[0041] - In a closed environment with a relative humidity of 65% to 85%, more particularly 70% to 80%, the homogeneous, inoculated, sterilized, and conditioned fiber substrate was incubated for 1 to 6 weeks, more particularly 2 to 5 weeks, and

[0042] - Collect the fiber substrate colonized by the one or more fungal strains to form the biologically pretreated fiber substrate.

[0043] As a substitute or supplement to the mycelial strain, liquid cultures of one or more of the fungal strains are used for inoculation.

[0044] In this case, the inoculation concentration will be advantageously determined by those skilled in the art, taking into account the concentration of the initial liquid culture and the growth capacity of the strain on the fiber substrate to be treated. Typically, 1% to 5% (by weight) of liquid culture medium is used for inoculation of the sterilized, conditioned fiber substrate.

[0045] Advantageously, in the method according to the invention, the sterilization of the conditioned fiber substrate is pasteurization to obtain a conditioned fiber substrate sterilized at a temperature of 72°C or higher for at least 3 hours, preferably at least 4 hours, more preferably at least 5 hours.

[0046] More specifically, in the method according to the invention, pasteurization is performed at an elevated temperature until a peak temperature above 85°C, more particularly 88°C, more particularly 90°C is obtained, and maintained for 5 to 50 minutes, more particularly 30 to 40 minutes.

[0047] In one variation of the invention, the sterilization of the conditioned fiber substrate is a composting process comprising at least one composting cycle, the composting cycle comprising the steps of: increasing the temperature over a period of 6 hours to 5 days until a temperature of 55°C to 80°C is achieved, more preferably until a temperature of 58°C to 65°C is achieved, followed by ventilating the fiber substrate to maintain a temperature of 46°C to 49°C for 3 to 7 days, optionally by turning the fiber substrate.

[0048] In a preferred embodiment of the invention, the step of conditioning the fiber substrate to obtain the conditioned fiber substrate includes wetting the fiber substrate and / or washing the fiber substrate, optionally followed by draining or drying.

[0049] In another preferred embodiment of the invention, the step of conditioning the fibrous substrate includes the additional step of supplementing essential elements such as minerals (calcium, magnesium), phosphorus, carbon and nitrogen sources, for example, typically by adding particles to obtain a fibrous substrate with a carbon-to-nitrogen ratio of 10 to 30, preferably 15 to 20.

[0050] In another variation of the invention, the sterilization of the regulated fibrous substrate comprises at least two, three, four, five, six, seven, eight, or even ten consecutive composting cycles.

[0051] In an advantageous embodiment of the invention, the method includes simultaneously producing biomolecules during pretreatment and simultaneously collecting the resulting biomolecules, wherein the one or more fungal strains comprise at least one strain that produces biomolecules.

[0052] In an advantageous embodiment of the invention, the biomolecule is a sugar or polysaccharide, and the at least one fungal strain comprises at least one sugar- or polysaccharide-producing strain selected from strains of the genera *Leptochloa*, *Ganoderma*, *Ganoderma*, *Pleurotus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Sulphurella*, *Pterocarpus*, *Lentinula*, *Fusarium*, *Aspergillus*, *Trichoderma*, *Penicillium*, *Cladosporium*, *Chaetoceros*, and *Acer negundo*.

[0053] As a non-limiting example, the resulting polysaccharide may be α-glucan, β-glucan, lentinan, lipopolysaccharide, PSK (Yunzhi polysaccharide), PSP (polysaccharide peptide), β-d-glucan, or glucuronide glucan.

[0054] In an advantageous embodiment of the invention, the biomolecule is a biomolecule or its precursor (e.g., antibiotic, antimitotic agent, antiviral agent, biosorbent, biosurfactant) having therapeutic or pharmaceutical significance, and wherein the at least one fungal strain comprises at least one strain that produces therapeutic biomolecules or is suitable for pharmaceutical processes (e.g., antibiotic, antimitotic agent, antiviral agent, biosorbent, biosurfactant), and the strain is selected from strains of Aspergillus, Trichoderma, Penicillium, Fusarium, Pleurotus, Fungium, Corkia, and Ganoderma.

[0055] For example, fungi of the genus *Ganoderma* are composed of triterpenoids and polysaccharides. Triterpenoids have been reported to possess hepatoprotective, antihypertensive, cholesterol-lowering, and antihistamine effects, as well as antitumor, anti-angiogenic, antiplatelet aggregation, and complement-inhibiting activities. Examples of triterpenoids include ganoderic acid, ganoderic acid, tanshinone, ganoderic acid and ganoderic acid, ganoderol A and B, ganoderic diol, ganoderol F and ganoderic mascarpone, and ganoderic ketones. Polysaccharides have also been reported to exhibit antitumor effects through immunomodulation and anti-angiogenesis. Polysaccharides also possess protective effects against free radicals and can reduce cell damage induced by mutagens. Some polysaccharides have also been reported to have antidiabetic effects.

[0056] The thrombus species *Bacillus thuringiensis* possesses anti-free radical, antioxidant, antibacterial, and acetylcholinesterase inhibitory activities.

[0057] Extracts from Pleurotus ostreatus fungi possess therapeutic effects, such as lowering cholesterol, scavenging free radicals, antioxidation, anti-atherosclerosis, antitumor, and immunomodulatory effects. For example, Pleurotus ostreatus fungi have been reported to contain triterpenoids, such as 2,3,6,23-tetrahydroxy-12-arbutin-28-acid, 2,3,23-trihydroxyursin-12-en-28-acid, and lupeol.

[0058] Pigments from fungi of the genus *Phimosa* possess antiviral, antibacterial, and anti-inflammatory properties.

[0059] According to reports, fungi in the genera Aspergillus, Trichoderma, and Penicillium contain biosurfactants.

[0060] Fungi of the genera *Penicillium*, *Aquilaria*, and *Aspergillus* have been reported to secrete antibiotics such as penicillin and cephalosporins.

[0061] In another advantageous embodiment of the invention, the biomolecule is an enzyme, and the at least one fungal strain comprises at least one enzyme-producing strain selected from strains belonging to the genera *Leptochloa*, *Ganoderma*, *Ganoderma*, *Pleurotus*, *Fomitopsis*, *Pterocarpus*, *Fomitopsis*, *Pterocarpus*, *Sulphurella*, *Fomitopsis*, *Lentinula*, *Fusarium*, *Aspergillus*, *Trichoderma*, *Penicillium*, *Cladosporium*, *Chaetoceros*, and *Acer spp.*, more specifically selected from *Leptochloa*, *Ganoderma*, *Ganoderma lingulata*, *Ganoderma longifolia*, *Ganoderma lucidum*, *Ganoderma sinense*, *Ganoderma sinense*, and *Ganoderma*; *Ganoderma* *Pleurotus* species, including *Pleurotus* var. *velutipes*, *Pleurotus* var. *fragrant*, *Turkeytail*, *Pleurotus* var. *blood*, *Pleurotus* genus, *Pleurotus* genus, *Pleurotus* var. *white*, *Pleurotus* var. *golden*, *Pleurotus* var. *paleonis*, *King Oyster Mushroom*, *Pleurotus* var. *floribunda*, *Pleurotus* var. *pinna*, *Pleurotus* var. *peach*, *Pleurotus* var. *woodenia*, *Pleurotus* var. *red*, *Pleurotus* var. *milky*, *Pleurotus* var. *sulfur*, *Inonotus obliquus*, *Leptochloa* var. *birch*, *Leptochloa* var. *dongzhi*; *Leptochloa* var. *jieli*, *Leptochloa* var. *lei*, *Leptochloa* var. *qiaolin* and *Leptochloa* var. *tiger*, *Fusarium* genus, *Fusarium* var. *yanoides*, *Fusarium* var. *solanum*, *Aspergillus* genus, *Aspergillus oryzae*, *Aspergillus niger*, *Aspergillus fumigatus*, *Aspergillus terreus*, *Trichoderma* genus, *Trichoderma reesei*, *Trichoderma viride*, *Trichoderma longipes*, *Cladosporium* genus, *Chaetoceros* genus, *Chaetoceros* var. *globosum*.

[0062] More specifically, the enzymes are selected from proteases, laccases, amylases, cellulases, chitinases, xylanases, manganese peroxidases, lipases, and lignin peroxidases.

[0063] In another advantageous embodiment of the invention, the biomolecule is an active biomolecule (e.g., a UV filter, pigment, antioxidant, or free radical scavenger), and the at least one fungal strain includes at least one strain that produces an active biomolecule selected from strains belonging to the genera *Pleurotus*, *Pleurotus*, *Fusarium*, *Ganoderma*, or *Ganoderma*, such as *Pleurotus erythrorhizon*, *Pleurotus ostreatus*, *Fusarium scutellatus*, *Fusarium graminearum*, *Fusarium graminearum*, and *Fusarium graminearum*.

[0064] Examples of pigments include, but are not limited to, cinnabarin, cinnabarin, cinnabarin, PsPCP, carmine anthraquinone, yellow fusarin, and bicacolin.

[0065] Other embodiments of the method for producing biogas according to the invention are described by way of non-limiting example in the appended claims and the following description. Detailed Implementation

[0066] This invention relates to a method for producing biogas from a fibrous substrate, wherein the fibrous substrate is biologically pretreated by solid-state fermentation using one or more fungal strains to form a shredded fibrous substrate colonized by the at least one fungal strain, which is then transferred to a biogas production facility. Once transferred to the biogas production facility, microorganisms within the facility can digest (anaerobic digest) the fibrous substrate colonized by the one or more fungal strains.

[0067] Then collect the biogas residue produced after biogas production.

[0068] According to the present invention, the fungal strain can be a highly colonizing strain that rapidly grows on and utilizes the fibrous substrate. This makes it possible to convert carbonaceous materials that are difficult for methanogenic microorganisms to utilize into more readily usable carbonaceous substances. The fungal strain used can also be an enzyme-producing strain. In this case, enzyme production occurs concurrently with the growth of the fungal biomass, thereby synergistically digesting the fiber of the fibrous substrate. These enzymes facilitate the subsequent utilization of methanogenic microorganisms.

[0069] In some embodiments of the invention, a mixture of several strains will be selected to optimize the pretreatment of the fibrous substrate by the fungal strain.

[0070] Agglomerated, woven, or nonwoven shredded fiber substrates include fibers selected from natural plant or animal textile fibers, semi-synthetic or polymer textile fibers, and lignocellulose fibers. This preferably includes shredded residues of recycled textiles, more specifically shredded residues of recycled furniture textiles, recycled mattresses, recycled bathroom or bedding, recycled clothing textiles, recycled textile production waste or recycled textile production waste, recycled upholstery, and mixtures thereof. This is even more preferably including shredded residues of recycled textiles selected from furniture, mattresses, and upholstery textiles, and having a synthetic foam content of 10% to 80%. Such residues may also contain wood chip residues.

[0071] In the specific case of upholstery textiles, mattresses, and interior decorations, there is currently no recycling method because this waste contains too many different components. Typically, the fibrous substrate includes a certain proportion of synthetic fibers, semi-synthetic fibers, synthetic foams (such as PU foam), and natural plant or animal fibers.

[0072] While many stakeholders consider the presence of synthetic fibers or contamination from plastic foams (such as PU foam) a drawback, as this typically involves substrates that cannot be digested by methanogenic microorganisms, this invention represents a technological breakthrough because it selectively treats the fibrous substrate with synthetic contaminants to enrich the sludge with synthetic and plastic materials, thereby enabling its recycling in the plastics recycling industry. According to the invention, the collected sludge is enriched with synthetic fibers and plastic materials in a proportion exceeding 85% by weight relative to the weight of the sludge.

[0073] According to the present invention, the biological pretreatment step includes:

[0074] - The fiber substrate is adjusted to obtain an adjusted fiber substrate containing 60% to 80% by weight of water relative to the weight of the adjusted fiber substrate.

[0075] - The conditioned fiber substrate is sterilized to form a sterilized conditioned fiber substrate.

[0076] - Cool the sterilized and conditioned fiber substrate for 12 to 24 hours.

[0077] - Inoculating the sterilized and conditioned fiber substrate with mycelial strains of one or more seed-borne fungal strains at a ratio of 0.5% to 10% by weight, even more particularly 1% to 7% by weight, and most particularly 3% to 5% by weight relative to the weight of the sterilized and conditioned fiber substrate, thereby obtaining an inoculated sterilized and conditioned fiber substrate.

[0078] - Mix the inoculated sterilized and conditioned fiber substrate to obtain a homogeneous inoculated sterilized and conditioned fiber substrate.

[0079] - In a closed environment with a relative humidity of 65% to 85%, more particularly 70% to 80%, the homogeneous, inoculated, sterilized, and conditioned fiber substrate was incubated for 1 to 6 weeks, more particularly 2 to 5 weeks, and

[0080] - Collect the fiber substrate colonized by one or more fungal strains to form the biologically pretreated fiber substrate.

[0081] This allows the use of fiber substrates that are currently not being recycled due to the difficulty in utilizing carbon blocks.

[0082] According to the present invention, the sterilization of the treated fiber substrate is pasteurization to obtain a conditioned fiber substrate obtained by sterilization at a temperature of 72°C or higher for at least 3 hours, preferably at least 4 hours, and more preferably at least 5 hours.

[0083] More specifically, in the method of the present invention, pasteurization is performed at an elevated temperature until a peak temperature above 85°C, more particularly 88°C, more particularly 90°C is obtained, and maintained for 5 to 50 minutes, more particularly 30 to 40 minutes.

[0084] In one variation of the invention, the sterilization of the conditioned fiber substrate is a composting process comprising at least one composting cycle, the composting cycle comprising the steps of: increasing the temperature over a period of 6 hours to 5 days until a temperature of 55°C to 80°C is achieved, more preferably until a temperature of 58°C to 65°C is achieved, followed by ventilating the fiber substrate to maintain a temperature of 46°C to 49°C for 3 to 7 days, optionally by turning the fiber substrate.

[0085] Composting effectively sterilizes the fibrous substrate while eliminating the need for energy-intensive steps.

[0086] In a preferred embodiment of the invention, the step of conditioning the fiber substrate to obtain the conditioned fiber substrate includes wetting the fiber substrate and / or washing the fiber substrate, optionally followed by draining or drying.

[0087] In another preferred embodiment of the invention, the step of conditioning the fibrous substrate includes the additional step of supplementing essential elements such as minerals (calcium, magnesium), phosphorus, carbon and nitrogen sources, for example, typically by adding particles to obtain a fibrous substrate with a carbon-to-nitrogen ratio of 10 to 30, preferably 15 to 20.

[0088] In another variation of the invention, the sterilization of the regulated fibrous substrate comprises at least two, three, four, five, six, seven, eight, or even ten consecutive composting cycles.

[0089] The method according to the invention also aims to generate target biomolecules during biological pretreatment using one or more fungal strains. In fact, waste recycling can currently only be implemented on an industrial scale if it is economically viable, either in terms of energy returns because the cost of purchasing raw materials is negative (i.e., the waste producer funds those who process it), or because it produces materials of economic value.

[0090] To promote the recycling of textile waste, this invention enables the simultaneous production of high-value target biomolecules, which can provide additional incentives for operators of biogas production plants. These biomolecules can be used for industrial purposes (pigments, detergents, etc.) or for cosmetic, pharmaceutical, or therapeutic purposes, depending on the biological pretreatment conditions.

[0091] The biomolecules that can be produced have been described above.

[0092] Alternatively, these biomolecules are preferably selected from enzymes or biomolecules with a molecular weight of less than 5000 Da, preferably less than 1000 Da, such as flavoring agents, surfactants or coloring agents and / or terpene derivatives.

[0093] Preferably, these biomolecules are recovered before the bio-pretreated fiber substrate is transferred to the biogas production equipment.

[0094] It should be understood that the present invention is by no means limited to the above embodiments, and many modifications can be made thereto without departing from the scope of the appended claims.

Claims

1. A method for producing biogas from a fibrous substrate, comprising: - The fiber substrate is subjected to biological pretreatment to form a biologically pretreated fiber substrate. - Transfer the bio-pretreated fiber substrate to the biogas production equipment. - Biogas is produced from the pretreated fibrous substrate, forming biogas residue. - Collect the biogas residue; The method is characterized in that the biological pretreatment of the fiber substrate involves solid-state fermentation of woven, nonwoven, or aggregated fiber substrates using one or more filamentous fungal strains, more specifically one or more saprophytic filamentous strains, followed by chopping the woven, nonwoven, or aggregated fiber substrates into fragments, wherein the biologically pretreated fiber substrate is a chopped fiber substrate colonized by the one or more fungal strains.

2. The method for producing biogas from fibrous substrates according to claim 1, wherein the one or more fungal strains include at least one fungal strain with high colonization capacity, and the fungal strain is selected from strains belonging to the genera *Leptochloa*, *Ganoderma*, *Ganoderma*, *Pleurotus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Sulphurella*, *Pterocarpus*, *Lentinula*, *Fusarium*, *Aspergillus*, *Trichoderma*, *Penicillium*, *Cladosporium*, *Chaetoceros*, and *Acer negundo*.

3. The method for producing biogas from fibrous substrates according to claim 1 or 2, wherein the one or more fungal strains include at least one enzyme-producing fungal strain, the enzyme-producing fungal strain being selected from strains belonging to the genera *Lentinula*, *Ganoderma*, *Ganoderma*, *Pleurotus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Pterocarpus*, *Sulphurella*, *Pterocarpus*, *Lentinula*, *Fusarium*, *Aspergillus*, *Trichoderma*, *Penicillium*, *Cladosporium*, *Chaetoceros*, and *Acer negundo*.

4. The method for producing biogas from a fibrous substrate according to any one of claims 1 to 3, wherein the one or more fungal strains are a mixture of one or more strains with high colonization capacity and one or more enzyme-producing strains.

5. A method for producing biogas from a fibrous substrate according to any one of the preceding claims, wherein the aggregated, woven or nonwoven shredded fibrous substrate comprises fibers selected from natural plant fibers or animal textile fibers, semi-synthetic textile fibers or polymer textile fibers and lignocellulose fibers.

6. A method for producing biogas from a fibrous substrate according to any one of the preceding claims, wherein the aggregated, woven or nonwoven shredded fibrous substrate is a residue of the following substances after being crushed: recycled textiles, more specifically recycled furniture textiles, recycled mattresses, recycled bathroom products or recycled bedding, recycled clothing textiles, recycled textile production waste or recycled textile production waste, recycled interior decorations and mixtures thereof.

7. The method for producing biogas from a fibrous substrate according to any one of the preceding claims, wherein the aggregated, woven or nonwoven fibrous substrate is a residue of pulverized recycled textiles selected from furniture, mattresses and interior textiles, and has a synthetic foam content of 10% to 80%.

8. The method for producing biogas from a fibrous substrate according to any one of the preceding claims, wherein the agglomerated, woven or nonwoven fibrous substrate is a residue of pulverized lignocellulose components, such as a residue of pulverized fiberboard.

9. A method for producing biogas from a fibrous substrate according to any one of the preceding claims, wherein the fibrous substrate comprises a proportion of synthetic fibers, semi-synthetic fibers, synthetic foams such as PU foam, and natural plant or animal fibers, and wherein the collected biogas residue is rich in synthetic fibers and plastic materials in a proportion of more than 85% by weight relative to the biogas residue.

10. A method for producing biogas from a fibrous substrate according to any one of the preceding claims, wherein the biological pretreatment step comprises: - The fiber substrate is adjusted to obtain a conditioned fiber substrate, the conditioned fiber substrate containing 60% to 80% by weight of water relative to the weight of the conditioned fiber substrate. - The conditioned fiber substrate is sterilized to form a sterilized conditioned fiber substrate. - Cool the sterilized and conditioned fiber substrate for 12 to 24 hours. -Inoculating the sterilized and conditioned fiber substrate with mycelial strains of one or more fungal strains from seeds by adding at least one seed-borne mycelial strain to the sterilized and conditioned fiber substrate at a ratio of 0.5% to 10% by weight, more particularly 1% to 7% by weight, and most particularly 3% to 5% by weight relative to the weight of the sterilized and conditioned fiber substrate, or by inoculating from a liquid culture of the one or more fungal strains, to obtain an inoculated sterilized and conditioned fiber substrate. - Mix the inoculated sterilized and conditioned fiber substrate to obtain a homogeneous inoculated sterilized and conditioned fiber substrate. - In a closed environment with a relative humidity of 65% to 85%, more particularly 70% to 80%, the homogeneous, inoculated, sterilized, and conditioned fiber substrate was incubated for 1 to 6 weeks, more particularly 2 to 5 weeks, and - Collect the fiber substrate colonized by one or more fungal strains to form the biologically pretreated fiber substrate.

11. The method for producing biogas from a fibrous substrate according to claim 10, wherein the sterilization is steam pasteurization to obtain a conditioned fibrous substrate sterilized at a temperature of 72°C or higher for at least 3 hours, preferably at least 4 hours, more preferably at least 5 hours.

12. The method for producing biogas from a fibrous substrate according to claim 11, wherein pasteurization is performed at an elevated temperature until a peak temperature above 85°C, more particularly 88°C, more particularly 90°C is obtained, and maintained for 5 to 50 minutes, more particularly 30 to 40 minutes.

13. The method for producing biogas from a fibrous substrate according to any one of claims 10 to 12, wherein the sterilization of the conditioned fibrous substrate is composting comprising at least one composting cycle, the composting cycle comprising the steps of: increasing the temperature over a period of 6 hours to 5 days until a temperature of 55°C to 80°C is obtained, more preferably until a temperature of 58°C to 65°C is obtained, and then ventilating the fibrous substrate to maintain a temperature of 46°C to 49°C for 3 to 7 days, optionally ventilating by turning the fibrous substrate.

14. The method for producing biogas from a fiber substrate according to any one of claims 10 to 13, wherein the step of conditioning the fiber substrate to obtain a conditioned fiber substrate comprises wetting the fiber substrate and / or washing the fiber substrate, optionally followed by draining or drying.

15. The method for producing biogas from a fibrous substrate according to any one of claims 10 to 14, wherein the step of conditioning the fibrous substrate includes an additional step of supplementing essential elements such as minerals (calcium, magnesium), phosphorus, carbon and nitrogen sources, for example, typically by adding particles to obtain a fibrous substrate with a carbon-to-nitrogen ratio of 10 to 30, preferably 15 to 20.

16. A method for producing biogas from a fibrous substrate according to any one of the preceding claims, comprising simultaneously producing biomolecules during pretreatment and simultaneously collecting the resulting biomolecules, wherein the one or more fungal strains comprise at least one strain that produces biomolecules.

17. The method for producing biogas from a fibrous substrate according to claim 16, wherein the biomolecule is a sugar or polysaccharide, and wherein the at least one fungal strain comprises at least one sugar-producing strain or polysaccharide-producing strain selected from strains of the genera Ganoderma, Pleurotus, and Pleurotus, such as Ganoderma lucidum strain.

18. The method for producing biogas from a fibrous substrate according to claim 16, wherein the biomolecule is a biomolecule with therapeutic or pharmaceutical significance, such as antibiotics, antimitotic agents, antiviral agents, biosorbents, and surfactants, and wherein the at least one fungal strain includes at least one strain that produces therapeutic biomolecules or biomolecules suitable for pharmaceutical processes (e.g., antibiotics, antimitotic agents, antiviral agents, biosorbents, and surfactants), said strain being selected from strains of the genera *Aspergillus*, *Trichoderma*, *Penicillium*, *Fusarium*, *Pleurotus*, *Pleurotus*, *Pleurotus*, *Pleurotus*, *Ganoderma*, and *Pleurotus*.

19. The method for producing biogas from a fibrous substrate according to claim 16, wherein the biomolecule is an enzyme, and wherein the at least one fungal strain comprises at least one enzyme-producing strain selected from strains belonging to the genera *Leptochloa*, *Ganoderma*, *Ganoderma*, *Pleurotus*, *Pterocarpus ...

20. The method for producing biogas from a fibrous substrate according to claim 16, wherein the biomolecules are active biomolecules, such as UV filters, pigments, antioxidants, and free radical scavengers, and wherein the at least one fungal strain includes at least one strain that produces active biomolecules, the strain producing active biomolecules being selected from strains belonging to the genera *Pleurotus*, *Pleurotus*, *Fusarium*, *Ganoderma*, and *Ganoderma*, such as *Pleurotus erythrorhizon*, *Pleurotus ostreatus*, *Fusarium scutellatus*, *Fusarium graminearum*, *Fusarium graminearum*, and *Fusarium graminearum*.

21. The method for producing biogas from a fibrous substrate according to claim 16, wherein the biomolecule is a surfactant.

22. A method for producing biogas from a fibrous substrate according to any one of the preceding claims, wherein the collected biogas residue is deactivated, more particularly by thermal deactivation, and formed into, for example, blocks, modules or plates.