A method for degrading and reusing waste cellulose products

Abstract

This invention relates to a method for degrading and reusing waste cellulose products, comprising the following steps: Step A, pre-sorting and crushing the recycled waste cellulose products to tear the fabric into fabric fragments; Step B, treating the fabric fragments in a 2%-6% (w / w) H2SO4 solution for 12 to 16 hours; Step C, adding wheat bran and / or soybean meal as a nitrogen source to the solution from Step B, adding 20-60 mL of nutrient solution per kilogram of fabric fragments, and mixing thoroughly to form a mixture; Step D, adjusting the moisture content of the mixture to 55%-65% and sterilizing it; Step E, inoculating the mixture with a 5%-10% (w / w) mixed microbial culture, wherein the mixed microbial culture is a culture of two or more of Trichoderma viride, Trichoderma reesei, Aspergillus niger, and Trichoderma simonii; Step F, subjecting the mixture treated in Step E to aerobic fermentation to obtain a crude cellulase product. This invention can improve the degradation efficiency of cellulose products and reduce costs.

Description

Technical Field

[0001] This invention relates to a method for degrading and reusing waste cellulose products. Background Technology

[0002] Cellulose is a large polysaccharide insoluble in organic solvents and water, widely found in plant cell walls in nature. Due to the abundant natural source of cellulose, it has been extracted directly or through various chemical processes, and then spun into cellulose fibers with diverse crystalline structures. These fibers are widely used in clothing and home furnishings due to their excellent mechanical properties, moisture permeability, dyeing properties, and low cost. However, with the widespread use of cellulose fibers, the waste disposal problem of cellulose products has become increasingly serious. Currently, the main methods are incineration and landfill, both of which pose corresponding environmental safety hazards and have low utilization rates. Biodegradation of cellulose products refers to the process by which these products, after being discarded, decompose naturally using microorganisms in the environment, such as bacteria, molds, and algae, to lose their original form. However, natural degradation is expected to take more than a year to completely degrade. Currently, there are five main methods for evaluating the biodegradability of textile materials: activated sludge method, soil decomposition method, aerobic composting method, specific microbial or enzymatic action method, and anaerobic test. Studies by Niu Jiantao et al. showed that after two weeks of biodegradation by Aspergillus oryzae, washed cotton, flax, and viscose fibers did not produce new substances according to infrared spectroscopy; only the internal structure of the fibers was somewhat damaged. Lin Yanping's research showed that after three months of high-temperature composting with pulverized cellulose products, the degradation rate of the cellulose products was greater than 50%. Other studies have shown that recycling 1 kg of waste clothing can reduce carbon dioxide emissions by 3.6 kg and save 6000 L of industrial water.

[0003] Based on the above issues, the applicant conducted research on these issues and thus this case came into being. Summary of the Invention

[0004] The purpose of this invention is to provide a method for the degradation and reuse of waste cellulose products that can improve the degradation efficiency of cellulose products and reduce costs.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for degrading and reusing waste cellulose products includes the following steps:

[0007] Step A: The recycled waste cellulose products are pre-sorted and crushed to tear the fabric into fabric fragments.

[0008] Step B: Place the fabric fragments in an H2SO4 solution with a mass fraction concentration of 2%-6% for 12 to 16 hours, with the mass ratio of H2SO4 solution to fabric fragments being (1-2):(2-4).

[0009] Step C: Add wheat bran and / or soybean meal as a nitrogen source to the solution in step B. The mass ratio of nitrogen source to fabric fragments is (1-2):(8-9). Add 20-60 mL of nutrient solution per kilogram of fabric fragments and mix well to form a mixture.

[0010] Step D: Adjust the moisture content of the mixture to 55%-65% and the pH to 4.5-6.5, and then perform sterilization.

[0011] Step E: Inoculate the mixture with a mixed microbial culture of 5%-10% by mass, wherein the mixed microbial culture is a culture medium of two or more of Trichoderma viride, Trichoderma reesei, Aspergillus niger, and Trichoderma simonii.

[0012] Step F: The mixture processed in step E is subjected to aerobic fermentation at a temperature of 20-35℃ for 20-30 days. Cellulase activity is monitored, and when the enzyme activity reaches its peak, the enzyme koji is air-dried to obtain crude cellulase product.

[0013] As a preferred embodiment of the present invention, the waste cellulose products include cotton fiber, hemp fiber, and sugarcane fiber.

[0014] In a preferred embodiment of the present invention, the nitrogen source is a mixture of wheat bran and soybean meal, wherein the mass ratio of wheat bran to soybean meal is 2-4.

[0015] As a preferred embodiment of the present invention, the nutrient solution comprises 0.5-4 g / L ammonium sulfate, 1-3 g / L potassium dihydrogen phosphate, 1-3 g / L magnesium sulfate, and the balance being water.

[0016] As a preferred embodiment of the present invention, the concentration of mycelium in the culture medium is controlled at 3-8 g / L.

[0017] As a preferred embodiment of the present invention, the culture medium is prepared as follows: 200g of potato is added to 1000mL of water, boiled for 30min, filtered with gauze, and water is added to 1000mL.

[0018] As a preferred embodiment of the present invention, the culture time of the strain is 45-50 hours and the culture temperature is 28-32℃.

[0019] As a preferred embodiment of the present invention, the diameter of the fabric fragment is ≤10cm or the length is ≤10cm.

[0020] As a preferred embodiment of the present invention, the processing temperature in step B is room temperature, and the processing is carried out in a sealed environment.

[0021] In a preferred embodiment of the present invention, the sterilization temperature in step D is 121°C and the sterilization time is 30 min.

[0022] By adopting the technical solution of this invention, some auxiliary agents in cellulose products are modified and separated from the cellulose material in advance using a dry dilute acid pretreatment method. Voids are formed inside the cellulose products, which facilitates subsequent microbial degradation. This invention uses mixed strains for synergistic degradation, which makes up for the deficiencies of single strains such as incomplete enzyme systems and low enzyme production, thereby improving the efficiency of microbial degradation. This invention adds nitrogen source auxiliary materials such as wheat bran and soybean meal, and adds nutrient solution to fully reuse the cellulose raw materials and produce crude cellulase. Crude cellulase can turn waste cellulose products into treasure. The enzyme production cost is lower than that of traditional methods, and its social and economic benefits will be very obvious. The crude cellulase obtained by this invention can be applied to the straw cellulose pretreatment process, which can reduce some of the cellulase usage costs. Detailed Implementation

[0023] To better understand the technical solution of the present invention, a more detailed description is provided below with reference to the embodiments.

[0024] Example 1

[0025] The recycled waste cellulose products (taking cotton fiber products as an example, the same below) are pre-sorted and crushed, and then torn into fabric fragments with a diameter ≤10cm using a twin-shaft shredder; 2% by mass of dilute sulfuric acid is added, with the mass ratio of dilute sulfuric acid to fiber products being 2:2, and the mixture is sealed at room temperature for 16 hours; nitrogen sources bran and soybean meal are added, with a mass ratio of bran:soybean meal = 2, and the addition amount is 1:9 with the dry weight of the fabric; 20mL / kg of nutrient solution is added, and the mixture is mixed evenly to obtain a mixture; the water content of the mixture is adjusted to 55%, and then the pH of the mixture is adjusted to 6.5; 5% by mass of mixed inoculum (Trichoderma viride: Trichoderma reesei: Aspergillus niger: Trichoderma simonii culture medium volume ratio 1:2:1:1) is inoculated, and the mycelial concentration of the inoculum is controlled at 5g / L; the mixture is fermented at 30℃ with aerobic fermentation (i.e., aerobic fermentation, using conventional technology in the biochemical field) for 30 days to obtain crude cellulase with a filter paper enzyme activity of 200IU / g dry koji.

[0026] Example 2

[0027] The recycled waste cellulose products were pre-sorted and crushed, and then torn into fragments with a diameter ≤10cm using a twin-shaft shredder. 4% (w / w) dilute sulfuric acid was added, with a sulfuric acid to fiber product mass ratio of 2:3, and the mixture was sealed at room temperature for 14 hours. Nitrogen sources bran and soybean meal were added, with a bran:soybean meal mass ratio of 3 and an addition amount to the dry basis of the fabric of 2:8. Nutrient solution of 20mL / kg dry basis was added and mixed thoroughly to obtain a mixture. The moisture content of the mixture was adjusted to 60%, and the pH was adjusted to 5.5. 8% of a mixed inoculum (Trichoderma viride: Trichoderma reesei: Aspergillus niger: Trichoderma simonii culture liquid volume ratio 1:1:1:2) was inoculated, with the mycelial concentration of the inoculum controlled at 8g / L. Aerobic fermentation was carried out at 30℃ for 25 days to obtain crude cellulase with a filter paper enzyme activity reaching 220 IU / g dry koji.

[0028] Example 3

[0029] The recycled waste cellulose products were pre-sorted and crushed, and then torn into fragments with a diameter ≤10cm using a twin-shaft shredder. 6% dilute sulfuric acid was added, with a mass ratio of sulfuric acid to fiber products of 1:4, and the mixture was sealed at room temperature for 12 hours. Nitrogen sources bran and soybean meal were added, with a mass ratio of bran:soybean meal = 4 and an addition amount to the dry basis of the fabric of 1:8. Nutrient solution of 20mL / kg dry basis was added and mixed evenly to obtain a mixture. The moisture content of the mixture was adjusted to 65%, and then the pH of the mixture was adjusted to 4.5. 10% of a mixed inoculum (Trichoderma viride: Trichoderma reesei: Aspergillus niger: Trichoderma simonii culture medium volume ratio 2:1:1:1) was inoculated, and the mycelial concentration of the inoculum was controlled at 3g / L. The mixture was fermented at 30℃ with oxygen for 20 days to obtain crude cellulase with a filter paper enzyme activity of 210IU / g dry koji.

[0030] Comparative Examples

[0031] In each comparative example, the conditions were the same as in Example 1, except that a single strain of bacteria was used for fermentation.

[0032] The crude cellulase was produced by fermentation with a single strain of Trichoderma viride, and the filter paper enzyme activity reached 45 IU / g dry koji.

[0033] The crude cellulase was obtained by fermentation with a single strain of Trichoderma reesei, and the filter paper enzyme activity reached 70 IU / g dry koji.

[0034] The crude cellulase was obtained by fermentation with a single strain of Trichoderma koningii, and the filter paper enzyme activity reached 170 IU / g dry koji.

[0035] The crude cellulase was obtained by fermentation with a single strain of Aspergillus niger, and the filter paper enzyme activity reached 62 IU / g dry koji.

[0036] In this application, IU refers to the amount of enzyme required to degrade filter paper and release 1 μmol of glucose per minute under the conditions of 37°C, pH 5.5, and 60 min of reaction, which is one enzyme activity unit.

[0037] In each example and comparative example, *Trichoderma viride*, *Trichoderma reesei*, *Aspergillus niger*, and *Trichoderma simonii* were cultured in a culture medium prepared as follows: 200g of potato was added to 1000mL of water, boiled for 30min, filtered through four layers of gauze, and water was added to 1000mL. The culture time was 45-50h, and the culture temperature was 28-32℃.

[0038] In this application: *Trichoderma viride* (AS 3.3711),

[0039] Trichoderma reesei ATCC 56764,

[0040] Trichoderma mapseudokoningii 3.3002,

[0041] Aspergillus niger (CGMCC 3.316) can be purchased directly from the market.

[0042] Of course, the scope of protection of this invention is not limited to this embodiment. Any similar modifications made to it are considered to be within the scope of patent protection of this invention.

Claims

1. A method for degrading and reusing waste cellulose products, characterized in that, Includes the following steps: Step A involves pre-sorting and crushing the recycled waste cellulose products to tear the fabric into fabric fragments. Step B: Place the fabric fragments in an H2SO4 solution with a mass fraction concentration of 2%-6% for 12 to 16 hours, with the mass ratio of H2SO4 solution to fabric fragments being (1-2):(2-4). Step C: Add wheat bran and / or soybean meal as a nitrogen source to the solution in step B. The mass ratio of nitrogen source to fabric fragments is (1-2):(8-9). Add 20-60 mL of nutrient solution per kilogram of fabric fragments and mix well to form a mixture. Step D: Adjust the moisture content of the mixture to 55%-65% and the pH to 4.5-6.5, and then sterilize it. Step E: Inoculate the mixture with a mixed microbial culture of 5%-10% by mass, wherein the mixed microbial culture is a culture medium of Trichoderma viride, Trichoderma reesei, Aspergillus niger and Trichoderma simonii; Step F involves aerobic fermentation of the mixture processed in Step E at a temperature of 20-35°C for 20-30 days. Cellulase activity is monitored, and when the enzyme activity reaches its peak, the enzyme koji is air-dried to obtain crude cellulase product.

2. The method for degrading and reusing waste cellulose products as described in claim 1, characterized in that, The waste cellulose products include cotton fiber, hemp fiber, and sugarcane fiber.

3. The method for degrading and reusing waste cellulose products as described in claim 2, characterized in that, The nitrogen source is a mixture of wheat bran and soybean meal, with a mass ratio of wheat bran to soybean meal of 2-4.

4. The method for degrading and reusing waste cellulose products as described in claim 3, characterized in that, The nutrient solution comprises 0.5-4 g / L ammonium sulfate, 1-3 g / L potassium dihydrogen phosphate, 1-3 g / L magnesium sulfate, and the remainder water.

5. The method for degrading and reusing waste cellulose products as described in claim 4, characterized in that, The concentration of mycelium in the culture medium is controlled at 3-8 g / L.

6. The method for degrading and reusing waste cellulose products as described in claim 5, characterized in that, The culture medium was prepared as follows: 200g of potato was added to 1000mL of water, boiled for 30 minutes, filtered with gauze, and water was added to bring the total volume to 1000mL.

7. The method for degrading and reusing waste cellulose products as described in claim 6, characterized in that, The culture time for the strain is 45-50 hours, and the culture temperature is 28-32℃.

8. The method for degrading and reusing waste cellulose products as described in claim 7, characterized in that, The fabric fragment has a diameter ≤10cm or a length ≤10cm.

9. A method for degrading and reusing waste cellulose products as described in claim 8, characterized in that, Step B involves processing at room temperature in a sealed environment.

10. The method for degrading and reusing waste cellulose products as described in claim 9, characterized in that, The sterilization temperature in step D is 121℃, and the sterilization time is 30 minutes.