Waste wood material recycling method

Abstract

The invention relates to the field of waste resource utilization, and discloses a waste wood material recycling method which comprises the following steps: S1, preparing and primarily treating a waste wood material; s2, performing low-temperature solvent treatment and hot reflux method combined treatment on the primarily treated wood material; s3, carrying out enzyme catalytic degradation on the wood material subjected to the combination treatment; s4, performing solid-liquid separation and wastewater treatment on a product subjected to enzyme catalytic degradation; and S5, respectively carrying out product extraction and post-treatment on the waste liquid and the solid after wastewater treatment. According to the method, low-temperature solvent treatment and a hot reflux method are combined, and a mixed solvent of ethyl acetate and ethanol is adopted, so that the recovery efficiency of lignin is effectively improved, the lignin is dissolved and extracted more sufficiently, efficient recovery of the lignin is ensured, and meanwhile, the solvent consumption and the energy consumption are reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of waste resource utilization, in particular to a method for regenerating and utilizing waste wood materials. BACKGROUND

[0002] Waste wood materials generally refer to waste materials, wood boards, waste furniture and other wood materials generated in the process of wood processing. With the increasing utilization of wood, the amount of waste wood materials is increasing year by year. Because wood contains a large amount of organic components such as lignin and cellulose, if these wastes are not effectively treated, not only a large amount of land resources will be occupied, environmental pollution will be increased, but also valuable recyclable substances will be wasted. Therefore, the regeneration and utilization of waste wood materials has become an important problem in the field of current environmental protection and resource recycling.

[0003] At present, the regeneration and utilization methods of waste wood materials mainly include physical treatment, chemical treatment and biological degradation. However, in use, the traditional wood material regeneration technology usually relies on high temperature or strong acid, strong alkali and other chemical solvent treatment, and the recovery efficiency is low, the solvent consumption is large, and the energy use is not economical. SUMMARY

[0004] In view of the defects of the prior art, the present application provides a method for regenerating and utilizing waste wood materials, which solves the problems of large solvent consumption and uneconomical energy use.

[0005] To achieve the above purpose, the present application is realized by the following technical scheme: a method for regenerating and utilizing waste wood materials, comprising the following steps:

[0006] S1: preparing and preliminarily treating the waste wood materials;

[0007] S2: combining low-temperature solvent treatment with hot reflux method to treat the wood materials after preliminary treatment;

[0008] S3: enzyme catalytic degradation of the wood materials after combined treatment;

[0009] S4: solid-liquid separation and wastewater treatment of the products after enzyme catalytic degradation;

[0010] S5: product extraction and post-treatment of the waste liquid and solid after wastewater treatment.

[0011] By adopting the above technical scheme, firstly, the waste wood materials are prepared and preliminarily treated by S1 step, which improves the treatment efficiency of the wood materials;

[0012] In the S2 step, the low-temperature solvent treatment is combined with the hot reflux method to treat the lignocellulosic material. By using a low-temperature solvent and combining the hot reflux method, the lignin and other organic components in the lignocellulosic material are effectively dissolved, improving the recovery efficiency of lignin. At the same time, the use of low-temperature solvent can reduce solvent consumption and reduce the impact on the environment, while the hot reflux method further improves the extraction rate of lignin through a staged extraction process;

[0013] The S3 step uses enzyme catalysis to degrade the lignocellulosic material, optimizing the degradation efficiency of lignin and cellulose; it can decompose lignin and cellulose in the lignocellulosic material into more easily recovered and utilized chemicals, improving the conversion rate of raw materials;

[0014] In the S4 step, impurities in the reaction process are removed by solid-liquid separation and wastewater treatment. Solid-liquid separation is performed to obtain incompletely degraded cellulose and waste liquid containing dissolved substances such as lignin. After treatment, the waste liquid effectively removes impurities and harmful components in the water, making the recovered lignin more pure and allowing the wastewater to meet the reusable standard;

[0015] In the S5 step, the waste liquid after wastewater treatment and solid residue are subjected to product extraction and post-treatment. The waste liquid is subjected to lignin extraction to further improve the concentration of recovered lignin and sugar, and the solid residue is converted into usable biochar or soil conditioner through post-treatment, realizing the resource utilization of waste.

[0016] Through the above steps, the recovery efficiency of waste lignocellulosic material is improved, the solvent consumption and wastewater discharge are reduced, and the efficient recovery of lignin and sugar is realized, which has high industrial application potential.

[0017] Preferably, the waste wood in the S1 step includes waste lignocellulosic material from wood processing, old furniture, and wood boards;

[0018] The preliminary treatment includes the following steps:

[0019] A wood crusher is used to mechanically crush the waste wood to obtain lignocellulosic particles with a particle size of 2-5 mm and uniform distribution;

[0020] A vacuum drying device is used to dry the wood with high moisture content. The drying temperature is set to 50-70℃, and the drying time is 6-8 hours until the moisture content of the wood is 10-15%.

[0021] By adopting the above technical scheme, the preliminary treatment of the waste wood is to crush the waste wood material into uniformly distributed wood particles through mechanical crushing, so that the wood particles have a suitable particle size, which is beneficial to the uniformity and effect of subsequent low-temperature solvent treatment. The crushing process is carried out by a wood crusher, which ensures the physical crushing of the waste wood and the formation of loose structure, provides a larger surface area, and promotes the reaction efficiency of subsequent chemical solvent and enzyme catalytic degradation.

[0022] For waste wood with high water content, a vacuum drying device is used for drying treatment to reduce the water content of the wood to 10-15%. Through vacuum drying, the evaporation of water can be accelerated, and the direct contact of hot air with the wood is avoided, thereby reducing the mass loss of the wood, controlling the reduction of water content, and helping to optimize the subsequent treatment, reduce the interference of water on the solvent and enzyme catalytic reaction, and ensure the effective use of the wood material in the subsequent steps.

[0023] Preferably, the low-temperature solvent in S2 is a mixture of ethyl acetate and ethanol with a mass ratio of (70-90%): (10-30%), and the amount of the low-temperature solvent is 3-5 times the mass of the wood particles. The crushed wood particles are added to the low-temperature solvent and soaked at a temperature of 20-30℃ for 12-24 hours.

[0024] By adopting the above technical scheme, the use of low-temperature solvent is to soak the wood particles in a mixed solvent of ethyl acetate and ethanol, which effectively increases the contact area between the solvent and the wood particles, promotes the dissolution and separation of lignin and other components, and effectively extracts lignin without damaging the wood material, while avoiding excessive damage to the wood structure caused by high temperature.

[0025] Preferably, the steps of the heat reflux method in S2 are as follows:

[0026] Ethanol, ethyl acetate, and dimethyl sulfoxide are used in sequence for fractional extraction, and the contact time between the solvent and the wood is 1-3 hours.

[0027] By adopting the above technical scheme, the heat reflux method is used to treat the wood material, and ethanol, ethyl acetate, and dimethyl sulfoxide are used in sequence for fractional extraction. Each solvent can effectively separate different components in the wood by contacting the wood. By using fractional solvents, lignin, hemicellulose, and other organic substances in the wood material can be gradually dissolved, thereby improving the extraction efficiency of lignin. The heat reflux method utilizes the heating and evaporation characteristics of the solvent, so that the solvent can repeatedly contact the wood in a short time, increasing the dissolution capacity and treatment efficiency of the solvent, ensuring the efficient separation of valuable components in the wood, and avoiding excessive damage to the wood material caused by high temperature.

[0028] Preferably, the step S3 comprises using white rot fungus ligninase and Trichoderma reesei cellulase, wherein the concentration of the ligninase is 1-2% (w / v) and the concentration of the cellulase is 0.5-1% (w / v).

[0029] By using the above technical solution, the ligninase and the cellulase are used to catalytically degrade the lignocellulosic material, wherein the ligninase and the cellulase synergistically act to effectively degrade the lignin and cellulose components in the lignocellulosic material. The ligninase can specifically decompose the lignin structure to expose the cellulose part of the wood, providing conditions for the further action of the cellulase. The cellulase can degrade the cellulose into soluble sugars, improving the recovery rate of the available organic matter in the wood, ensuring effective degradation of the lignocellulosic material and allowing the valuable components in the wood to be separated and recovered, thereby achieving efficient degradation of the lignocellulosic material and reducing damage to other components of the wood, ensuring efficient extraction of lignin and sugar in subsequent steps.

[0030] Preferably, the order of adding the white rot fungus ligninase and the Trichoderma reesei cellulase is as follows:

[0031] First, the ligninase is added and reacted at 25-30°C for 12-24 hours, and then the cellulase is added and reacted at 30-35°C for 24 hours. During the reaction, the pH value is controlled at 4.5-5.5 by adding a buffer solution, and the mixture is continuously stirred using a stirrer.

[0032] By using the above technical solution, the ligninase and the cellulase are used to catalytically degrade the lignocellulosic material, wherein the ligninase and the cellulase synergistically act to effectively degrade the lignin and cellulose components in the lignocellulosic material. The ligninase can specifically decompose the lignin structure to expose the cellulose part of the wood, providing conditions for the further action of the cellulase. The cellulase can degrade the cellulose into soluble sugars, improving the recovery rate of the available organic matter in the wood, ensuring effective degradation of the lignocellulosic material and allowing the valuable components in the wood to be separated and recovered, thereby achieving efficient degradation of the lignocellulosic material and reducing damage to other components of the wood, ensuring efficient extraction of lignin and sugar in subsequent steps.

[0033] Preferably, the step S4 of solid-liquid separation comprises the following steps:

[0034] The solid-liquid separation is performed by centrifugation at a speed of 3000-5000 rpm for 10-20 minutes, and the separated solid is the incompletely degraded cellulose.

[0035] By adopting the technical scheme, the solid-liquid separation is performed in a centrifugal manner, the reaction mixture is subjected to high-speed centrifugal treatment during centrifugation, and the solid components after enzymatic degradation can be effectively separated from the dissolved substances through the centrifugal action. The undegraded cellulose in the solid part is concentrated at the bottom of the centrifugal tube, and the supernatant is rich in dissolved lignin, sugars and other water-soluble products, thereby ensuring efficient separation of the solid and the liquid, providing purer liquid for subsequent lignin extraction and sugar recovery, and accelerating the precipitation process through high centrifugal force to improve the separation efficiency and ensure complete separation of the solid and the liquid, which is helpful to improve the overall recovery efficiency of the subsequent steps.

[0036] Preferably, the wastewater treatment in the S4 step comprises the following steps:

[0037] The lignin dissolved products in the waste liquid are recovered by using a liquid-liquid extraction method according to a waste liquid to water volume ratio of 1:1 to 2:1;

[0038] Then, the wastewater after recovery of the lignin dissolved products is purified by using a reverse osmosis membrane, wherein during the membrane separation process, the membrane assembly is cleaned periodically with a 0.1-0.5 mol / L sodium hydroxide solution.

[0039] The purified wastewater is introduced into a biofilm reactor and treated at 20-30°C for 12-24 hours.

[0040] By adopting the technical scheme, the wastewater treatment is combined by the liquid-liquid extraction method and the reverse osmosis membrane purification method. The lignin dissolved products in the waste liquid are recovered by using the liquid-liquid extraction method, and the wastewater after recovery of the lignin dissolved products is purified by using the reverse osmosis membrane, which can remove dissolved salts, impurities and unextracted substances in the wastewater, ensure that the water quality meets the reuse requirements, and periodically clean the membrane assembly with the sodium hydroxide solution during the membrane separation process to avoid membrane pollution and performance degradation, maintain efficient operation of the membrane, and finally, the purified wastewater is further treated by the biofilm reactor to effectively remove residual organic matter and microbial contamination, thereby ensuring that the wastewater meets the safe discharge or reuse standards.

[0041] Preferably, in the S5 step, the product extraction comprises the following steps:

[0042] The lignin in the waste liquid treated by the biofilm reactor is extracted by using a mixed solvent of ethanol and water with a mass ratio of 70-90:10-30, the mixed solvent is added in an amount of 5 times the volume of the waste liquid treated by the biofilm reactor, the reaction temperature is 40-60°C, the extraction time is 2-4 hours, and the lignin after extraction is subjected to solvent evaporation;

[0043] The liquid after lignin extraction is concentrated to 1 / 3 of the original volume under a vacuum degree of 0.06-0.08 MPa, and 0.5-1% of calcium chloride by mass of the concentrated liquid is added for sugar extraction, with the extraction temperature controlled at 40-60 DEG C and the extraction time being 6-8 hours.

[0044] By using the above technical scheme, the product extraction is carried out by using a mixed solvent of ethanol and water with a mass ratio of 70-90:10-30 to extract lignin, the mixed solvent is added to the waste liquid treated by the biological membrane reactor, the solvent can effectively dissolve the lignin in the waste liquid and separate the lignin from other water-soluble components, the liquid after lignin extraction is concentrated under vacuum, which further improves the concentration of lignin and reduces the residue of the solvent, then, calcium chloride is added for sugar extraction, the calcium chloride can combine with the sugar to improve the recovery rate of the sugar, ensuring the sufficient extraction and separation of the sugar, and by combining the solvent extraction with concentration, the recovery efficiency of lignin and sugar is improved, and the effective utilization of the waste liquid is ensured.

[0045] Preferably, the post-treatment comprises the following steps:

[0046] The solid residue after solid-liquid separation is pyrolyzed at 300-500 DEG C for 1-2 hours, or the solid residue is composted at a composting temperature of 40-60 DEG C for 4-6 weeks.

[0047] By using the above technical scheme, the solid residue after solid-liquid separation is further treated by pyrolysis or composting, which can convert the incompletely degraded solid residue into biochar and release volatile gases, thereby reducing the volume of waste and converting the waste into biochar with certain economic value, which can be used for soil improvement or other industrial purposes.

[0048] Another treatment method is composting, which can convert organic waste into humus through the action of microorganisms, increase the organic matter content of the soil, and inhibit the growth of pathogenic bacteria.

[0049] Both treatment methods effectively treat the solid residue, not only reducing the environmental burden of waste, but also realizing efficient treatment and reuse of the solid residue through resource utilization.

[0050] The present application provides a method for regenerating and utilizing waste wood materials.

[0051] 1、The present application combines low-temperature solvent treatment with hot reflux method, uses mixed solvent of ethyl acetate and ethanol, effectively improves the recovery efficiency of lignin, makes lignin more fully dissolved and extracted, ensures efficient recovery of lignin, and reduces solvent consumption and energy consumption.

[0052] 2、The present application uses white rot fungus ligninase and Trichoderma reesei cellulase for combined catalysis, effectively degrades lignin and cellulose in lignocellulosic materials, improves the degradation rate of wood, and improves the recovery efficiency of lignin and sugar.

[0053] 3、In the wastewater treatment process, the present application combines liquid-liquid extraction method with reverse osmosis membrane purification technology, effectively removes dissolved substances and harmful components in wastewater, ensures that the wastewater meets the reusable standard, and further treats the wastewater by a biofilm reactor, providing a wastewater recycling and reuse way.

[0054] 4、The solid residue in the present application is resourceized by pyrolysis or composting treatment, the pyrolysis treatment converts the solid residue into biochar, and the composting treatment converts it into organic fertilizer, both of which effectively reduce the volume of waste and realize the resourceization and environmentally friendly treatment of waste. BRIEF DESCRIPTION OF DRAWINGS

[0055] Figure 1 The flow chart of the method of the present application. DETAILED DESCRIPTION

[0056] The technical solutions of the present application will be described in detail below in combination with the drawings of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0057] Example 1

[0058] The present embodiment provides a method for regenerating and utilizing waste wood materials, which adopts the following technical solutions:

[0059] A method for regenerating and utilizing waste wood materials, comprising the following steps:

[0060] S1: preparing and preliminarily treating the waste wood materials;

[0061] Among them, the waste wood materials include waste wood materials of wood processing, waste furniture, and wood board;

[0062] The preliminary treatment comprises the following steps:

[0063] Waste wood is mechanically crushed using a wood shredder to obtain wood particles with a particle size of 2 mm and uniform distribution.

[0064] For wood with high moisture content, use vacuum drying equipment to dry it. Set the drying temperature to 50℃ and the drying time to 6 hours until the wood moisture content is 10%.

[0065] S2: The pre-treated wood material is subjected to a combination of low-temperature solvent treatment and heat reflux treatment;

[0066] The low-temperature solvent is a mixture of ethyl acetate and ethanol in a mass ratio of 70%:30%, and the amount of low-temperature solvent is 3 times the mass of the wood particles. The crushed wood particles are added to the low-temperature solvent and soaked at 20°C for 12 hours.

[0067] The steps of the hot reflux method are as follows: fractional extraction is performed sequentially using ethanol, ethyl acetate, and dimethyl thionamide, with the solvent in contact with the wood for 1 hour;

[0068] S3: Enzymatic degradation of the treated wood materials;

[0069] The enzymes used were white-rot fungus ligninase and Trichoderma reesei cellulase, with the concentration of ligninase being 1% (w / v) and the concentration of cellulase being 0.5% (w / v).

[0070] The enzymes were added in the following order: first, ligninase was added and reacted at 25°C for 12 hours, then cellulase was added and reacted at 30°C for 24 hours. During the reaction, the pH was adjusted to 4.5 by adding buffer solution, and the mixture was continuously stirred with a stirrer during the reaction.

[0071] S4: Solid-liquid separation and wastewater treatment of the products after enzyme-catalyzed degradation;

[0072] The solid-liquid separation process includes the following steps: solid-liquid separation is performed by centrifugation at a speed of 3000 rpm for 10 minutes, and the separated solid is incompletely degraded cellulose.

[0073] Wastewater treatment includes the following steps: using liquid-liquid extraction to recover lignin dissolution products from the waste liquid at a volume ratio of 1:1 between centrifuged waste liquid and water;

[0074] The wastewater after recovering the lignin dissolution products was then purified using a reverse osmosis membrane. During the purification process, the pressure was 0.5 MPa and the temperature was 20 °C. The membrane module was cleaned periodically with a 0.1 mol / L sodium hydroxide solution during the membrane separation process.

[0075] The purified wastewater was fed into a biofilm reactor and treated at 20°C for 12 hours.

[0076] S5: Extract and post-process the waste liquid and solids after wastewater treatment, respectively;

[0077] The product extraction process includes the following steps: using a mixed solvent of ethanol and water at a mass ratio of 70:30 to extract lignin from the waste liquid after treatment by the biofilm reactor. The amount of mixed solvent added is 5 times the volume of the waste liquid after treatment by the biofilm reactor. The reaction temperature is 40°C and the extraction time is 2 hours. The extracted lignin is then evaporated to remove the solvent.

[0078] The liquid after lignin extraction was concentrated to 1 / 3 of its original volume under a vacuum of 0.06 MPa. 0.5% calcium chloride by weight of the concentrate was added for sugar extraction. The extraction temperature was controlled at 40℃ and the extraction time was 6 hours.

[0079] The post-processing includes the following steps: pyrolyzing the solid residue after solid-liquid separation at 300°C for 1 hour, or composting the solid residue at 40°C for 4 weeks.

[0080] Example 2

[0081] This embodiment provides a method for recycling waste wood materials, employing the following technical solution:

[0082] A method for recycling waste wood materials includes the following steps:

[0083] S1: Preparation and preliminary treatment of waste wood materials;

[0084] Among them, waste wood includes waste wood materials from wood processing, waste furniture, and wood boards;

[0085] The initial treatment includes the following steps:

[0086] Waste wood is mechanically crushed using a wood shredder to obtain wood particles with a particle size of 3.5 mm and uniform distribution.

[0087] For wood with high moisture content, use vacuum drying equipment to dry it. Set the drying temperature to 60℃ and the drying time to 7 hours until the wood moisture content is 12.5%.

[0088] S2: The pre-treated wood material is subjected to a combination of low-temperature solvent treatment and heat reflux treatment;

[0089] The low-temperature solvent is a mixture of ethyl acetate and ethanol at a mass ratio of 80%:20%, and the amount of low-temperature solvent is 4 times the mass of the wood particles. The crushed wood particles are added to the low-temperature solvent and soaked at 25°C for 18 hours.

[0090] The steps of the hot reflux method are as follows: fractional extraction is performed sequentially using ethanol, ethyl acetate, and dimethyl thionamide, with the solvent in contact with the wood for 2 hours;

[0091] S3: Enzymatic degradation of the treated wood materials;

[0092] The enzymes used were white-rot fungus ligninase and Trichoderma reesei cellulase, with the concentration of ligninase being 1.5% (w / v) and the concentration of cellulase being 0.75% (w / v).

[0093] The enzymes were added in the following order: first, ligninase was added and reacted at 27.5℃ for 18 hours, then cellulase was added and reacted at 32.5℃ for 24 hours. During the reaction, the pH was adjusted to 5.0 by adding buffer solution, and the mixture was continuously stirred with a stirrer during the reaction.

[0094] S4: Solid-liquid separation and wastewater treatment of the products after enzyme-catalyzed degradation;

[0095] The solid-liquid separation includes the following steps: solid-liquid separation is carried out by centrifugation at a speed of 4000 rpm for 15 minutes, and the separated solid is incompletely degraded cellulose;

[0096] Wastewater treatment includes the following steps: using liquid-liquid extraction to recover lignin dissolution products from the waste liquid at a volume ratio of 1.5:1 between centrifuged waste liquid and water.

[0097] The wastewater after recovering the lignin dissolution products was then purified using a reverse osmosis membrane. During the purification process, the pressure was 1.0 MPa and the temperature was 30℃. The membrane module was cleaned periodically with a 0.3 mol / L sodium hydroxide solution during the membrane separation process.

[0098] The purified wastewater was fed into a biofilm reactor and treated at 25°C for 18 hours.

[0099] S5: Extract and post-process the waste liquid and solids after wastewater treatment, respectively;

[0100] The product extraction process includes the following steps: using a mixed solvent of ethanol and water at a mass ratio of 80:20 to extract lignin from the waste liquid after treatment by the biofilm reactor. The amount of mixed solvent added is 5 times the volume of the waste liquid after treatment by the biofilm reactor. The reaction temperature is 50°C and the extraction time is 3 hours. The extracted lignin is then evaporated to remove the solvent.

[0101] The liquid after lignin extraction was concentrated to 1 / 3 of its original volume under a vacuum of 0.07 MPa. 0.75% calcium chloride by weight of the concentrate was added for sugar extraction. The extraction temperature was controlled at 50℃ and the extraction time was 7 hours.

[0102] The post-processing includes the following steps: pyrolyzing the solid residue after solid-liquid separation at 400°C for 1.5 hours, or composting the solid residue at 50°C for 5 weeks.

[0103] Example 3

[0104] This embodiment provides a method for recycling waste wood materials, employing the following technical solution:

[0105] A method for recycling waste wood materials includes the following steps:

[0106] S1: Preparation and preliminary treatment of waste wood materials;

[0107] Among them, waste wood includes waste wood materials from wood processing, waste furniture, and wood boards;

[0108] The initial treatment includes the following steps:

[0109] Waste wood is mechanically crushed using a wood shredder to obtain wood particles with a particle size of 5 mm and uniform distribution.

[0110] For wood with high moisture content, use vacuum drying equipment to dry it. Set the drying temperature to 70℃ and the drying time to 8 hours until the wood moisture content is 15%.

[0111] S2: The pre-treated wood material is subjected to a combination of low-temperature solvent treatment and heat reflux treatment;

[0112] The low-temperature solvent is a mixture of ethyl acetate and ethanol at a mass ratio of 90%:10%, and the amount of low-temperature solvent is 5 times the mass of the wood particles. The crushed wood particles are added to the low-temperature solvent and soaked at 30°C for 24 hours.

[0113] The steps of the hot reflux method are as follows: fractional extraction is performed sequentially using ethanol, ethyl acetate, and dimethyl thionamide, with the solvent in contact with the wood for 3 hours;

[0114] S3: Enzymatic degradation of the treated wood materials;

[0115] The enzymes used were white-rot fungus ligninase and Trichoderma reesei cellulase, with the concentration of ligninase being 2% (w / v) and the concentration of cellulase being 1% (w / v).

[0116] The enzymes were added in the following order: first, ligninase was added and reacted at 30°C for 24 hours, then cellulase was added and reacted at 35°C for 24 hours. During the reaction, the pH was adjusted to 5.5 by adding buffer solution, and the mixture was continuously stirred with a stirrer during the reaction.

[0117] S4: Solid-liquid separation and wastewater treatment of the products after enzyme-catalyzed degradation;

[0118] The solid-liquid separation process includes the following steps: solid-liquid separation is performed by centrifugation at a speed of 5000 rpm for 20 minutes, and the separated solid is incompletely degraded cellulose.

[0119] Wastewater treatment includes the following steps: using liquid-liquid extraction to recover lignin dissolution products from the waste liquid at a volume ratio of 2:1 between centrifuged waste liquid and water.

[0120] The wastewater after recovering the lignin dissolution products was then purified using a reverse osmosis membrane. During the purification process, the pressure was 1.5 MPa and the temperature was 40 °C. The membrane module was cleaned periodically with a 0.5 mol / L sodium hydroxide solution during the membrane separation process.

[0121] The purified wastewater is fed into a biofilm reactor and treated at 30°C for 24 hours.

[0122] S5: Extract and post-process the waste liquid and solids after wastewater treatment, respectively;

[0123] The product extraction process includes the following steps: using a mixed solvent of ethanol and water at a mass ratio of 90:10 to extract lignin from the waste liquid after treatment by the biofilm reactor. The amount of mixed solvent added is 5 times the volume of the waste liquid after treatment by the biofilm reactor. The reaction temperature is 60℃ and the extraction time is 4 hours. The extracted lignin is then evaporated to remove the solvent.

[0124] The liquid after lignin extraction was concentrated to 1 / 3 of its original volume under a vacuum of 0.08 MPa. 1% calcium chloride by weight of the concentrate was added for sugar extraction. The extraction temperature was controlled at 60℃ and the extraction time was 8 hours.

[0125] The post-processing includes the following steps: pyrolyzing the solid residue after solid-liquid separation at 500°C for 2 hours, or composting the solid residue at 60°C for 6 weeks.

[0126] Comparative Example 1

[0127] The only difference from Example 2 is that the treatment method combining low-temperature solvent and hot reflux was not used.

[0128] Comparative Example 2

[0129] The only difference from Example 2 is that the combined catalysis of white rot fungus ligninase and Trichoderma reesei cellulase was not used.

[0130] Comparative Example 3

[0131] The only difference from Example 2 is that the treatment method combining liquid-liquid extraction and reverse osmosis membrane purification was not performed.

[0132] Comparative Example 4

[0133] The only difference from Example 2 is that vacuum concentration technology was not used.

[0134] Comparative Example 5

[0135] The only difference from Example 2 is that no biofilm reactor treatment was performed.

[0136] Comparative Example 6

[0137] The only difference from Example 2 is that only a single solvent, ethanol, is used to extract the wood material.

[0138] Comparative Example 7

[0139] The only difference from Example 2 is that only ligninase is used for catalysis.

[0140] I. Testing of Utilization Indicators for Wood Materials

[0141] 1. Lignin recovery rate: According to "LY / T 1281-2011 Method for Determination of Moisture Content of Wood Raw Materials", the alkali dissolution and acid precipitation method was used to extract all forms of lignin in each treatment system: First, the reaction solution and solid residue were combined, and a 10% sodium hydroxide solution was added. The mixture was stirred and extracted at 80℃ for 2 hours. After centrifugation and filtration, the pH of the extract was adjusted to 2.0 with hydrochloric acid, and the mixture was allowed to stand for 4 hours to precipitate. The precipitate was collected, washed with deionized water until neutral, and dried in a vacuum drying oven to constant weight. The mass of lignin (m2) was then weighed. The recovery rate was calculated using the formula: Lignin recovery rate = m2 / (m0 × initial lignin content) × 100%.

[0142] 2. Sugar recovery rate

[0143] The total sugar content (m3) extracted from each system was determined using the anthrone colorimetric method: A quantitative extract was taken, anthrone-sulfuric acid reagent was added, and the mixture was boiled in a water bath for 10 minutes. After cooling, the absorbance was measured at 620 nm using a UV spectrophotometer. The sugar concentration and total mass were calculated using the glucose standard curve. The recovery rate was calculated using the formula: Sugar recovery rate = m3 / (m0 × initial cellulose content × 0.9) × 100%.

[0144] II. Detection of Solvent Consumption Related Indicators

[0145] 1. Total Solvent Consumption and Recovery Rate: Before the experiment, accurately weigh the total mass (m4) of ethyl acetate and ethanol initially added to each experimental / control group, and record the solvent type and ratio. During the experiment, all solvents collected in the solvent recovery process were stored uniformly. After settling and separating to remove water, the total mass (m5) of the recovered solvent was accurately weighed again. The relevant indicators were calculated using the following formulas: Solvent Consumption = m4 - m5; Solvent Recovery Rate = m5 / m4 × 100%.

[0146] 2. Solvent Purity Testing: To verify the feasibility of reusing the recovered solvent, the impurity content in the recovered solvent was determined using a high-performance liquid chromatograph (HPLC-1260). The chromatographic column was C18, the mobile phase was methanol-water, the flow rate was 1.0 mL / min, the detection wavelength was 254 nm, and the column temperature was 30℃. A quantitative amount of the recovered solvent was injected, and the impurity content was calculated using the peak area normalization method. When the impurity content was ≤0.5%, the solvent purity was deemed to meet the requirements for reuse.

[0147] III. Testing of Wastewater Discharge Related Indicators

[0148] Wastewater pollutant content: COD value and vanillin content (an intermediate in lignin degradation) were selected as the core pollutant indicators. COD value was measured using a rapid COD analyzer, and the value was directly read colorimetrically based on the potassium dichromate digestion method. Vanillin content was measured using an ultraviolet spectrophotometer at a wavelength of 280 nm, and the concentration was calculated using a vanillin standard curve. All pollutant detection data were compared with the Class I discharge standard (COD ≤ 100 mg / L) in GB 8978-1996 Integrated Wastewater Discharge Standard to determine the compliance status of wastewater discharge.

[0149] Table 1. Detection data of wood material utilization indicators

[0150]

[0151] Table 2. Detection data of solvent consumption related indicators

[0152]

[0153]

[0154] Table 3. Data on wastewater discharge related indicators

[0155]

[0156]

[0157] Experimental conclusion:

[0158] Combining Examples 1-3 and Comparative Example 1 with Tables 1 and 3, it can be seen that the treatment method combining low-temperature solvent soaking and hot reflux plays a decisive role in the utilization efficiency of waste wood materials and the control of wastewater discharge. Comparative Example 1, lacking this process, had lignin and sugar recovery rates that were only about half that of Example 2. By softening the wood structure through low-temperature solvent soaking and enhancing component separation through hot reflux fractional extraction, the accessibility of lignin and cellulose was improved, and the migration of degradation products into wastewater was reduced, achieving a dual optimization of resource utilization and environmental performance.

[0159] Combining Examples 1-3 and Comparative Example 2 with Tables 1 and 3, it can be seen that the combined catalytic system of white-rot fungus ligninase and Trichoderma reesei cellulase is the core of improving the conversion efficiency of woody material components. In Comparative Example 2, due to the elimination of the combined catalysis, the lignin recovery rate was lower than in Example 2, the sugar recovery rate was only 46.5% of that in Example 2, and the wastewater COD value was significantly increased. The synergistic effect of the two enzymes is manifested in the following ways: ligninase preferentially degrades the lignin barrier, creating a channel for cellulase action, while cellulase directionally converts cellulose into usable sugars. This stepwise catalytic mechanism significantly improves the product recovery rate while reducing the emission of undegraded organic matter.

[0160] Based on Examples 1-3 and Comparative Example 3, and referring to Tables 1 and 3, it can be seen that the wastewater treatment process combining liquid-liquid extraction and reverse osmosis membranes is crucial for lignin recovery and wastewater reduction. In Comparative Example 3, lacking this process, the lignin recovery rate decreased compared to Example 2, and the wastewater discharge was 3.6 times that of Example 2. Liquid-liquid extraction can efficiently recover dissolved lignin from wastewater, while reverse osmosis membranes achieve wastewater purification and concentration. The combined use of both improves resource utilization and reduces the total amount of pollutants and wastewater volume at the source.

[0161] Based on Examples 1-3 and Comparative Example 4, and referring to Tables 1 and 3, it can be seen that vacuum concentration technology is a key step in ensuring efficient sugar extraction and reducing wastewater pollution load. Comparative Example 4, which did not use vacuum concentration, had a lower sugar recovery rate than Example 2, and its wastewater COD value was 2.4 times that of Example 2. Vacuum concentration reduces the volume of the extract liquid at low temperatures, which not only increases the sugar concentration for subsequent extraction but also avoids sugar degradation caused by high temperatures, reducing organic pollutants discharged with the wastewater and lowering subsequent treatment energy consumption.

[0162] Combining Examples 1-3 and Comparative Example 5 with Tables 2 and 3, it can be seen that the biofilm reactor treatment process is significantly effective in deeply degrading pollutants in wastewater. In Comparative Example 5, without this process, the COD value of the wastewater was higher than in Example 2, and the vanillin content was 3.97 times that of Example 2. The biofilm reactor, through the targeted degradation of lignin intermediates and small molecule organic matter in wastewater by microbial metabolism, is the core guarantee for achieving deep reduction of wastewater pollutants, without affecting solvent recovery efficiency.

[0163] Based on Examples 1-3 and Comparative Example 6, and referring to Tables 1 and 2, it can be seen that the extraction effect of the ethyl acetate / ethanol mixed solvent system is better than that of a single ethanol solvent. In Comparative Example 6, using a single ethanol solvent, the lignin recovery rate and sugar recovery rate were lower than in Example 2, while the solvent recovery rate was similar to that of Example 2. The mixed solvent achieves selective extraction of lignin and cellulose by adjusting polarity, and its synergistic effect improves the extraction efficiency. In contrast, a single solvent has limitations in polarity matching and cannot simultaneously achieve optimal extraction effects for both components.

[0164] Combining Examples 1-3 and Comparative Example 7 with Tables 1 and 3, it can be seen that the combined catalysis of ligninase and cellulase has a significant advantage over single ligninase catalysis in improving sugar recovery rate. In Comparative Example 7, when only ligninase was used, the sugar recovery rate was only 35.9% of that in Example 2, and the wastewater COD value was higher than in Example 2. Single ligninase can only degrade lignin and cannot convert cellulose, resulting in a large amount of cellulose being discharged with the wastewater, which reduces resource utilization and increases wastewater pollution load. Combined catalysis, however, achieves comprehensive and efficient conversion of the main components in woody materials.

[0165] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for recycling waste wood materials, characterized in that, Includes the following steps: S1: Preparation and preliminary treatment of waste wood materials; S2: The pre-treated wood material is subjected to a combination of low-temperature solvent treatment and heat reflux treatment; S3: Enzymatic degradation of the treated wood materials; S4: Solid-liquid separation and wastewater treatment of the products after enzyme-catalyzed degradation; S5: Extract and post-process the waste liquid and solids after wastewater treatment.

2. The method for recycling waste wood materials according to claim 1, characterized in that, The waste wood in step S1 includes waste wood materials from wood processing, waste furniture, and wood boards; The initial treatment includes the following steps: Waste wood is mechanically crushed using a wood shredder to obtain wood particles with a particle size of 2-5 mm and uniform distribution. For wood with high moisture content, use vacuum drying equipment to dry it. Set the drying temperature to 50-70℃ and the drying time to 6-8 hours until the wood moisture content is 10-15%.

3. The method for recycling waste wood materials according to claim 1, characterized in that, In step S2, the low-temperature solvent is a mixture of ethyl acetate and ethanol in a mass ratio of (70-90%):(10-30%), and the amount of low-temperature solvent is 3-5 times the mass of the wood particles. The crushed wood particles are added to the low-temperature solvent and soaked at 20-30°C for 12-24 hours.

4. The method for recycling waste wood materials according to claim 1, characterized in that, The steps of the hot reflux method in step S2 are as follows: Fractional extraction was performed sequentially using ethanol, ethyl acetate, and dimethyl thionamide, with the solvent in contact with the wood for 1-3 hours.

5. A method for recycling waste wood materials according to claim 1, characterized in that, Step S3 includes selecting ligninase from white-rot fungi and cellulase from Trichoderma reesei, wherein the concentration of ligninase is 1-2% (w / v) and the concentration of cellulase is 0.5-1% (w / v).

6. A method for recycling waste wood materials according to claim 5, characterized in that, The order in which the white-rot fungus ligninase and Trichoderma reesei cellulase were added was as follows: First, add ligninase and react at 25-30℃ for 12-24 hours, then add cellulase and react at 30-35℃ for 24 hours. During the reaction, adjust the pH value to 4.5-5.5 by adding buffer solution, and continuously stir the mixture with a stirrer during the reaction.

7. A method for recycling waste wood materials according to claim 1, characterized in that, The solid-liquid separation in step S4 includes the following steps: Solid-liquid separation is performed by centrifugation at a speed of 3000-5000 rpm for 10-20 minutes. The separated solids are incompletely degraded cellulose.

8. A method for recycling waste wood materials according to claim 1, characterized in that, The wastewater treatment in step S4 includes the following steps: The lignin dissolution products in the waste liquid were recovered by liquid-liquid extraction with a volume ratio of 1:1 to 2:1 between the centrifuged waste liquid and water. The wastewater after recovering the lignin dissolution products was then purified using a reverse osmosis membrane. During the purification process, the pressure was 0.5-1.5 MPa and the temperature was 20-40℃. The membrane module was cleaned periodically with a 0.1-0.5 mol / L sodium hydroxide solution during the membrane separation process. The purified wastewater is fed into a biofilm reactor and treated at 20-30℃ for 12-24 hours.

9. A method for recycling waste wood materials according to claim 1, characterized in that, In step S5, product extraction includes the following steps: Lignin was extracted from the waste liquid after treatment by the biofilm reactor using a mixed solvent of ethanol and water at a mass ratio of 70-90:10-30. The amount of mixed solvent added was 5 times the volume of the waste liquid after treatment by the biofilm reactor. The reaction temperature was 40-60℃ and the extraction time was 2-4 hours. The solvent was removed by evaporation after extraction. The lignin-extracted liquid is concentrated to 1 / 3 of its original volume under a vacuum of 0.06-0.08 MPa. 0.5-1% calcium chloride is added to the concentrate for sugar extraction. The extraction temperature is controlled at 40-60℃ and the extraction time is 6-8 hours.

10. A method for recycling waste wood materials according to claim 1, characterized in that, The post-processing includes the following steps: The solid residue after solid-liquid separation is pyrolyzed at 300-500℃ for 1-2 hours, or it is composted at 40-60℃ for 4-6 weeks.

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