A method for reducing plant biomass of agricultural and forestry waste and its application

Abstract

The present invention discloses a method for degrading plant biomass of agricultural and forestry waste and its application. In the present invention, plant biomass of agricultural and forestry waste, trivalent iron minerals and nutrient solution are mixed, and a hydrolysis microbial bacterial liquid is selectively added, and the obtained reaction system A is anaerobically cultured to obtain a hydrolysis solution. The hydrolysis solution contains hydrolysis products of lignocellulose and has a low chromaticity, and can be used as a denitrification carbon source. This method has low energy consumption and cost, and can significantly improve the carbon source utilization rate of lignocellulose; the obtained hydrolysis solution has a low chromaticity and high denitrification potential, and can be used as a liquid carbon source to supply sewage treatment plants for use as an external denitrification carbon source. It can be seen that this method can not only effectively degrade plant biomass of agricultural and forestry waste, but also the obtained hydrolysis solution can be used as a denitrification carbon source for sewage treatment.

Description

Technical Field

[0001] The present invention belongs to the field of environmental protection, and particularly relates to a method for reducing plant biomass of agricultural and forestry waste and its application. Background Art

[0002] Currently, the mainstream denitrification method in sewage treatment plants is still denitrification. However, the organic carbon concentration in sewage is often low. It is reported that the carbon-nitrogen ratio of the influent of about 80% of sewage treatment plants in China is lower than 3.6, which cannot provide sufficient carbon source for denitrification, so additional organic carbon sources need to be added. Among various external carbon sources, although small molecule compounds such as sodium acetate can quickly improve the denitrification efficiency, the cost and dosage are two thorny problems. In contrast, agricultural and forestry waste has relatively good economy and sustainability and has become one of the research hotspots. Agricultural and forestry waste such as wheat straw, corn cob, dead branches and leaves, etc., is rich in various organic carbon compounds, and will release a large amount of organic carbon in water, thereby improving the denitrification efficiency. This conclusion has been widely studied and confirmed. However, the problem of the release of chromogenic substances (generally unsaturated aromatic organic compounds) from agricultural and forestry waste into water has received less attention.

[0003] The chromogenic substances released from agricultural and forestry waste into water mainly come from lignin and its hydrolysis products in the plant biomass of agricultural and forestry waste. Lignin is a macromolecule polymerized by multiple phenylpropane aromatic compounds, and three corresponding monomers - coniferyl alcohol, sinapyl alcohol and p - coumaryl alcohol will be released during hydrolysis. These monomers and the rest of the hydrolysis products of lignin are collectively called lignin phenols, which are electron donors that are difficult to be utilized by denitrifying bacteria. They not only increase the COD and chromaticity of water, but also inhibit the activity of various hydrolases and hinder the further hydrolysis of plant biomass of agricultural and forestry waste. Summary of the Invention

[0004] The primary object of the present invention is to overcome the deficiencies of the prior art and provide a method for reducing plant biomass of agricultural and forestry waste.

[0005] Another object of the present invention is to provide the application of the above method for reducing plant biomass of agricultural and forestry waste.

[0006] The object of the present invention is achieved by the following technical solutions: A method for reducing plant biomass of agricultural and forestry waste, comprising the following steps:

[0007] (1) Mix the plant biomass of agricultural and forestry waste, trivalent iron minerals and nutrient solution, and selectively add hydrolysis microbial bacterial liquid to obtain reaction system A;

[0008] (2) Anaerobically culture reaction system A to obtain a hydrolyzate.

[0009] The agricultural and forestry waste plant biomass described in step (1) includes, but is not limited to, agricultural waste plants, fallen leaves of garden plants, and wetland plants.

[0010] The agricultural and forestry waste plant biomass described in step (1) is preferably the treated agricultural and forestry waste plant biomass.

[0011] The steps of the pretreatment are as follows: The collected agricultural and forestry waste plant biomass is dried at 35 - 40 °C for 3 - 4 days and pulverized with a pulverizer to a particle size less than 0.5 - 1 cm.

[0012] The trivalent iron minerals described in step (1) include, but are not limited to, at least one of hematite, goethite, lepidocrocite, and ferrihydrite.

[0013] The dosage of the trivalent iron minerals described in step (1) is preferably calculated according to the mass ratio of 0.5 - 1.5:1 with the agricultural and forestry waste plant biomass; preferably calculated according to the mass ratio of 1:1.

[0014] The nutrient solution described in step (1) is a solution that is beneficial to the growth and reproduction of microorganisms, which is beneficial to the growth of hydrolysis microorganisms, and thus beneficial to the degradation of agricultural and forestry waste plant biomass.

[0015] The nutrient solution described in step (1) is a liquid containing 1 - 5 mg / L of ammonia nitrogen (NH 4 + -N) and 1 - 2 mg / L of phosphorus (TP), with a pH of 6.5 - 7.0. Its composition is preferably as follows: MnSO 4 ·4H 2 O 2 - 2.5 g / L, ZnSO 4 ·7H 2 O 0.8 - 0.9 g / L, H 3 BO 3 0.6 - 0.7 g / L, KI 0.08 - 0.09 g / L, CuSO 4 ·5H 2 O 0.02 - 0.03 g / L, NH 4 Cl 0.01 - 0.02 g / L, KH 2 PO 4 0.008 - 0.01 g / L, with a pH of 6.5 - 7.0; more preferably as follows: MnSO 4 ·4H 2 O 2.23 g / L, ZnSO 4 ·7H 2 O 0.86 g / L, H 3 BO 3 0.62 g / L, KI 0.083 g / L, CuSO 4·5H 2 O 0.025 g / L, NH 4 Cl 0.015 g / L, KH 2 PO 4 0.009 g / L, with the pH value being 6.5 - 7.0; the solvent is water, preferably deionized water.

[0016] The dosage of the nutrient solution described in step (1) is preferably calculated as agricultural and forestry waste plant biomass: nutrient solution = 1 g: 40 - 600 mL.

[0017] The hydrolytic microbial bacterial liquid described in step (1) is preferably a paddy soil extract or a sludge extract.

[0018] The dosage of the hydrolytic microbial bacterial liquid described in step (1) when added is preferably calculated as hydrolytic microbial bacterial liquid: agricultural and forestry waste plant biomass = 2 mL: 1 - 2 g.

[0019] The conditions for anaerobic cultivation described in step (2) are preferably dark cultivation at 25 - 35 °C; more preferably dark cultivation at 30 °C.

[0020] The anaerobic cultivation described in step (2) is carried out in a batch mode. After each hydrolysis reaction, the overlying water in the reaction system is discharged, and then new nutrient solution is supplemented to continue the reaction.

[0021] The time for each hydrolysis reaction is 4 - 6 days;

[0022] The number of batches of the reaction is preferably 4 - 8 batches.

[0023] The overlying water becomes the hydrolyzate after suction filtration. This hydrolyzate contains lignocellulose hydrolysis products and has a low chromaticity, and can be used as a denitrifying carbon source.

[0024] The application of the above method for reducing agricultural and forestry waste plant biomass in the environmental protection field can not only effectively degrade agricultural and forestry waste plant biomass, but also the obtained hydrolyzate can be used as a denitrifying carbon source for sewage treatment.

[0025] The present invention has the following advantages and effects compared with the prior art:

[0026] (1) The method for reducing agricultural and forestry waste plant biomass provided by the present invention can effectively reduce the chromaticity of the hydrolyzate, and the obtained hydrolyzate has a high denitrification potential and can be used as a liquid carbon source to supply sewage treatment plants as an external denitrifying carbon source.

[0027] (2) The method for reducing agricultural and forestry waste plant biomass provided by the present invention has low energy consumption and cost, and can significantly improve the carbon source utilization rate of lignocellulose. Description of the Drawings

[0028] Figure 1 Schematic structural diagram of the hydrolysis system of Example 1.

[0029] Figure 2 Physical photo of the hydrolysis solution in the first hydrolysis cycle of the hydrolysis system of Example 1; among them, the left figure is the hydrolysis solution obtained by PB, and the right figure is the hydrolysis solution obtained by HPB.

[0030] Figure 3 Chromaticity comparison diagram of the hydrolysis solution at the end of each hydrolysis cycle of the two hydrolysis experimental systems in Example 1; among them, PB is the hydrolysis system without adding hematite, and HPB is the hydrolysis system adding hematite.

[0031] Figure 4 Comparison result diagram of the filter paper enzyme activity of the cellulase solution prepared from the hydrolysis solution with different total phenol concentrations in Example 1. Detailed implementation mode

[0032] The present invention will be further described in detail below in conjunction with the examples and the accompanying drawings, but the implementation modes of the present invention are not limited thereto.

[0033] In the following examples, the selected agricultural and forestry waste is the withered leaves of the garden plant Ficus virens Aiton. The withered leaves are washed, dried at 35 - 40 °C for 3 - 4 days, ground and sieved through a 1 mm sieve for standby to obtain pretreated Ficus virens. The cattail is processed in the same steps to obtain pretreated cattail.

[0034] In the following examples, the selected iron mineral is hematite, purchased from Macklin Company, with the main component being Fe 2 O 3 , with a purity > 99.95% and a particle size < 1 μm.

[0035] In the following examples, a nutrient solution containing trace ammonia nitrogen and trace elements is used for hydrolysis, and the formula is shown in Table 1.

[0036] Table 1 Nutrient solution formula

[0037]

[0038] In the following examples, the cellulase used to prepare the cellulase solution is derived from Trichoderma reesei (theoretical enzyme activity is 5000 U / g), purchased from Sigma - Alidrich (USA) Company.

[0039] In the following examples, the concentration of the nitrate nitrogen standard stock solution (calculated as sodium nitrate) is 56.00 g / L: Weigh 0.7218 g of analytical - grade sodium nitrate dried at 105 - 110 °C for 2 h, dissolve it in deionized water, transfer it into a 1000 mL volumetric flask, and dilute it to the mark.

[0040] Example 1

[0041] Select the withered leaves of the garden plant Ficus virens Aiton as the original plant biomass and hematite as the iron mineral to construct a co-anaerobic degradation system of hematite and lignocellulose in pretreated withered leaves of Ficus virens Aiton, and obtain the anaerobic hydrolysis solution of Ficus virens lignocellulose.

[0042] (1) Anaerobic hydrolysis of pretreated Ficus virens lignocellulose: The anaerobic hydrolysis process was carried out in a 2.5 L water discharge bottle (as Figure 1 shown). A total of 6 reactors were set up, divided into 2 groups, and each group had 3 parallel systems. Mix 20 g of hematite and 20 g of pretreated withered leaves of Ficus virens in a 100-mesh filter bag, put it into one of the above 2.5 L water discharge bottles, add 1.2 L of nutrient solution and 2 mL of rice soil extract (mix the soil taken from a Guangzhou paddy field and distilled water according to a solid-liquid ratio of 1 g: 2 mL, let it stand and layer, and the upper layer is the rice soil extract) to construct a hematite co-anaerobic system. After purging with nitrogen to remove oxygen to create an anaerobic environment, it was placed in a constant temperature incubator at 30 °C for dark cultivation, which was the HPB-1 system. Synchronously construct a control hydrolysis system without adding hematite, which is the PB-1 system. Among them, take water samples from the lower outlet every 3 days to measure the pH, COD, Fe 2+ and UV 254 . Take 6 days as a reaction cycle. After draining the overlying water in the bottle at the end of each cycle, supplement new nutrient solution and continue the reaction. The hydrolysis solution drained at the end of each cycle was filtered through a 0.45 μm filter membrane, and the filtrate obtained was the hydrolysis solution. The anaerobic hydrolysis was carried out for 8 cycles.

[0043] (2) Exploration of the denitrification performance of the anaerobic hydrolysis solution: The denitrification reaction based on the anaerobic hydrolysis solution was carried out in a 250 mL airtight glass reaction bottle. Select sodium nitrate to prepare a stock solution with a nitrate nitrogen equivalent concentration of 180 mg / L as the nitrogen source for denitrification. Add 200 mL of anaerobic hydrolysis solution (i.e., the hydrolysis solution obtained in step (1)), 4 mL of nitrate nitrogen standard stock solution, sludge from the secondary sedimentation tank of a sewage treatment plant in Guangdong and ferrous-oxidizing nitrate-reducing bacteria solution (which has been published in the literature "Xie Xiaolan, Yu Guangwei, Zhong Yunxiao, Long Xinxian. Isolation and metabolic characteristics of ferrous-oxidizing nitrate-reducing bacteria from polluted river sediment [J]. China Environmental Science, 2015, 35(05): 1554-1562.", that is, strain FX-Fe5; the bacteria were cultured in a liquid medium until the logarithmic growth phase and used. The liquid medium formula is (g / L): KH 2 PO 4 0.1, K 2 HPO 4 0.1, NaNO 3 2.72, CH 3COONa 1.64, MgSO 4 ·7H 2 O 0.2) 0.5 mL each to construct a denitrification system with a reaction cycle of 6 days. Among them, pH, NO 3 - -N, NO 2 - -N, UV 254 were measured every 2 days, and the COD and TN before and after denitrification and their removal rates were compared. The remaining solution after the reaction was filtered through a 0.45 μm filter membrane to obtain the denitrification liquid for subsequent determination and analysis. Denitrification and anaerobic hydrolysis were carried out synchronously for 8 cycles.

[0044] (3) Chromaticity of the hydrolyzate:

[0045] The hydrolyzate obtained from the anaerobic hydrolysis S1 cycle is as Figure 2 shown. Figure 2 The left figure in it is the hydrolyzate obtained by PB, and the right figure is the hydrolyzate obtained by HPB. It can be seen that the color of the hydrolyzate obtained by HPB is significantly lighter, that is, the pigment is lower.

[0046] The chromaticity of the hydrolyzate at the end of each hydrolysis cycle of the two hydrolysis experimental systems was detected by the platinum-cobalt colorimetric method, and the results are as Figure 3 shown. From Figure 3 it can be seen that the chromaticity of the hydrolyzate produced by the hydrolysis system added with hematite is significantly lower than that of the control group. Especially in the early stage of hydrolysis (S1 and S2 cycles), the chromaticity of the hydrolyzate of the HPB system is (250.00 ± 28.87) Hazen units and (108.33 ± 8.33) Hazen units respectively, while the chromaticity of the hydrolyzate of the PB system is more than 2 times higher (p < 0.01).

[0047] (4) Adsorption of the hydrolyzate and its effect on cellulase activity:

[0048] Take a part of the hydrolyzate of the PB system in the S1 cycle and add hematite (25 g / L), and oscillate overnight in a constant temperature oscillator at 150 r / min to fully adsorb the polyphenolic substances in the hydrolyzate. After filtering through a 0.45 μm filter membrane, the adsorbed hydrolyzate is obtained. Cellulase solutions with a concentration of 100 mg / L were prepared using the original hydrolyzate and the above-mentioned adsorbed hydrolyzate as solvents (named enzyme solution B and C), and an enzyme solution prepared with distilled water (named enzyme solution A) was used as a control. The cellulase activities of the three enzyme solutions were measured and compared, and the results are as Figure 4 shown.

[0049] (5) The results show that:

[0050] 1) The TN removal rate of the hydrolyzate in the hydrolysis system added with hematite was significantly higher than that of the control group. The former was 49.22% - 80.43%, while the latter was only 26.25% - 66.20%. Moreover, the removal rates of UV and chromaticity by denitrification for the former were both significantly higher than those for the latter. The former were 5.75% - 63.09% and 20.56% - 58.33% respectively, while the latter were only - 12.78% - 13.38% and 6.01% - 41.67%. 254 2) Hematite can adsorb the chromaticity substances generated during the hydrolysis of plant biomass in agricultural and forestry waste. Most of these chromaticity substances belong to the hydrolysis products of lignin, namely lignin phenols.

[0051] 3) Compared with the filter paper enzyme activity of cellulase solution A prepared with distilled water (0.4174 ± 0.0022) FPU, the activities of enzyme solutions B and C prepared with plant anaerobic hydrolyzate were significantly reduced (p < 0.05), being (0.3006 ± 0.0054) FPU and (0.3357 ± 0.0076) FPU respectively. The corresponding total phenol concentrations were (44.76 ± 0.55) mg / L and (8.77 ± 0.11) mg / L respectively. Among them, the reduction amplitude of the filter paper enzyme activity of enzyme solution B without adsorption treatment exceeded 25%, which should be caused by the inhibition of cellulase by lignin - derived phenolic compounds in the hydrolyzate. Although the filter paper enzyme activity of enzyme solution C prepared with the hydrolyzate after hematite adsorption was also significantly lower than that of enzyme solution A, compared with enzyme solution B without adsorption treatment, its filter paper enzyme activity increased by 11.68%, with a significant difference (p < 0.05), indicating that the adsorption and removal of polyphenols in the hydrolyzate by hematite can alleviate its inhibitory effect on cellulase activity.

[0052] 3) Compared with the filter paper enzyme activity of cellulase solution A prepared with distilled water (0.4174 ± 0.0022) FPU, the activities of enzyme solutions B and C prepared with plant anaerobic hydrolyzate were significantly reduced (p < 0.05), being (0.3006 ± 0.0054) FPU and (0.3357 ± 0.0076) FPU respectively. The corresponding total phenol concentrations were (44.76 ± 0.55) mg / L and (8.77 ± 0.11) mg / L respectively. Among them, the reduction amplitude of the filter paper enzyme activity of enzyme solution B without adsorption treatment exceeded 25%, which should be caused by the inhibition of cellulase by lignin - derived phenolic compounds in the hydrolyzate. Although the filter paper enzyme activity of enzyme solution C prepared with the hydrolyzate after hematite adsorption was also significantly lower than that of enzyme solution A, compared with enzyme solution B without adsorption treatment, its filter paper enzyme activity increased by 11.68%, with a significant difference (p < 0.05), indicating that the adsorption and removal of polyphenols in the hydrolyzate by hematite can alleviate its inhibitory effect on cellulase activity.

[0053] Table 2

[0054]

[0055] Example 2

[0056] Select Typha orientalis Presl as the original plant biomass and hematite as the iron mineral to construct a co - anaerobic degradation system of hematite and lignocellulose in pretreated cattail withered leaves, and obtain cattail lignocellulose anaerobic hydrolyzate.

[0057] (1) Anaerobic hydrolysis of cattail leaf lignocellulose: 10 g of hematite and 10 g of pretreated cattail leaves were mixed in a 100-mesh filter bag, placed in a 500 mL wide-mouth bottle, 400 mL of nutrient solution and 2 mL of paddy soil extract (same as in Example 1) were added to construct a hematite co-anaerobic system, which was placed in a constant temperature incubator at 30 °C for dark cultivation, designated as the HPB-2 system. A control system without adding hematite was constructed simultaneously, designated as the PB-2 system. Among them, water samples were taken every 3 days to measure the pH, COD, Fe 2+ and UV 254 . Taking 6 days as a reaction cycle, after discharging the overlying water in the bottle at the end of each cycle, new nutrient solution was supplemented, and nitrogen gas was passed for 30 min before continuing the reaction. The hydrolyzate discharged at the end of each cycle was filtered through a 0.45 μm filter membrane, and the filtrate obtained was the hydrolyzate. The anaerobic hydrolysis was carried out for 2 cycles.

[0058] (2) Exploration of the denitrification performance of anaerobic hydrolyzate: The denitrification reaction based on the anaerobic hydrolyzate was carried out in a 250 mL airtight glass reaction bottle. A stock solution with a nitrate nitrogen equivalent concentration of 180 mg / L was prepared using sodium nitrate as the nitrogen source for denitrification. In a 250 mL glass bottle, 200 mL of anaerobic hydrolyzate, 4 mL of nitrate nitrogen stock solution, 0.5 mL each of sludge from the secondary sedimentation tank of a sewage treatment plant in Guangdong and ferrous-oxidizing nitrate-reducing bacteria solution (which has been published in the literature "Xie Xiaolan, et al. Isolation and metabolic characteristics of ferrous-oxidizing nitrate-reducing bacteria from polluted river sediment [J]. China Environmental Science, 2015, 35(05): 1554 - 1562.") were added to construct a denitrification system. The reaction cycle was 6 days, during which the pH, NO 3 - -N, NO 2 - -N, UV 254 were measured every 2 days, and the COD and TN before and after denitrification and their removal rates were compared. The remaining solution after the reaction was filtered through a 0.45 μm filter membrane to obtain the denitrified solution for subsequent determination and analysis. Denitrification and anaerobic hydrolysis were carried out synchronously for 2 cycles.

[0059] (3) The results showed that: Although the removal rate of NO 3 - -N in the hydrolyzate of the hydrolysis system with added hematite and the control group both reached over 99%, the accumulation amount of NO 2 - -N in the former was much lower than that in the latter, which led to the TN removal rate in the former being over 90%, while that in the latter was only 50% - 60%.

[0060] Table 3

[0061]

[0062] Example 3

[0063] The PB-1 system in Example 1 was selected to hydrolyze the hydrolysis solution of Ficus virens var. sublanceolata in the second cycle, and four iron minerals, namely hematite, goethite, lepidocrocite and ferrihydrite, were used as experimental materials for adsorption experiments to explore and compare the removal effects of the four iron minerals on lignin phenols in the hydrolysis solution, so as to infer the removal rate of the colority of the hydrolysis solution.

[0064] (1) Adsorption of lignin phenols in the hydrolysis solution by four iron minerals: Using a 150 mL conical flask as the adsorption container, hematite, goethite and ferrihydrite were added to the conical flask containing the hydrolysis solution at a solid-liquid ratio of 1:400 (g:mL), and lepidocrocite was added to the conical flask containing the hydrolysis solution at a solid-liquid ratio of 1:1000 (g:mL). An adsorption kinetics experiment was carried out, and samples were taken regularly to measure the total phenol content of the hydrolysis solution.

[0065] (2) Finally, the results obtained from the adsorption data are as follows: All four iron minerals can adsorb phenolic substances in the hydrolysis solution of Ficus virens var. sublanceolata. The adsorption capacity ranking of the four iron minerals is: lepidocrocite > goethite > hematite > ferrihydrite (as shown in Table 4 below). The results show that trivalent iron minerals represented by hematite used in Examples 1 and 2 exhibit potential adsorption capacity for phenolic substances in the hydrolysis solution of agricultural and forestry waste plants represented by Ficus virens var. sublanceolata and can be applied to the co-anaerobic hydrolysis of agricultural and forestry waste. In practical applications, the dosing ratio can be determined according to the adsorption capacity of several iron minerals.

[0066] Table 4

[0067]

[0068] The experimental results of the present invention show that: adding iron oxide during the hydrolysis process of agricultural and forestry waste plant biomass can effectively reduce the concentration of lignin phenols in the hydrolysis solution, thereby reducing the colority of the hydrolysis solution and alleviating the inhibition of the activity of hydrolase in the hydrolysis solution by lignin phenols.

[0069] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited by the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. Application of a hydrolysate obtained by a method of degrading plant biomass of agricultural and forestry waste as a denitrifying carbon source, characterized in that: The method of degrading plant biomass of agricultural and forestry waste includes the following steps: (1) Mix agricultural and forestry waste plant biomass, trivalent iron minerals and nutrient solution, and add a hydrolysate microbial bacterial solution to obtain reaction system A; (2) Anaerobically culture reaction system A to obtain a hydrolysate; The trivalent iron minerals described in step (1) are at least one of hematite, goethite, lepidocrocite and ferrihydrite; The dosage of the trivalent iron minerals described in step (1) is calculated according to the mass ratio of 0.5-1.5:1 to agricultural and forestry waste plant biomass; The nutrient solution described in step (1) is a liquid containing 1-5 mg / L of ammonia nitrogen and 1-2 mg / L of phosphorus, with a pH of 6.5-7.0; The hydrolysate microbial bacterial solution described in step (1) is a rice paddy soil extract or a sludge extract.

2. The application according to claim 1, characterized in that: The agricultural and forestry waste plant biomass described in step (1) is at least one of agricultural waste plants, garden plant leaves and wetland plants.

3. The application according to claim 2, characterized in that: The composition of the nutrient solution described in step (1) is as follows: MnSO 4 ·4H 2 O 2 - 2.5 g / L, ZnSO 4 ·7H 2 O 0.8 - 0.9 g / L, H 3 BO 3 0.6 - 0.7 g / L, KI 0.08 - 0.09 g / L, CuSO 4 ·5H 2 O 0.02 - 0.03 g / L, NH 4 Cl 0.01 - 0.02 g / L, KH 2 PO 4 0.008 - 0.01 g / L, and the pH is 6.5 - 7.

0.

4. The application according to claim 1, characterized in that: The dosage of the nutrient solution described in step (1) is calculated as agricultural and forestry waste plant biomass: nutrient solution = 1 g: 40-600 mL; The dosage of the hydrolysate microbial bacterial solution when added in step (1) is calculated as hydrolysate microbial bacterial solution: agricultural and forestry waste plant biomass = 2 mL: 1-2 g.

5. The application according to claim 1, characterized in that: The anaerobic culture described in step (2) is achieved by introducing nitrogen to discharge oxygen; The conditions for the anaerobic culture described in step (2) are dark culture at 25-35 °C.

6. The application according to claim 1, characterized in that: The anaerobic culture described in step (2) is carried out in a batch mode. After each hydrolysis reaction, the overlying water in the reaction system is discharged, and then new nutrient solution is added to continue the reaction for the next batch of reactions.

7. The application according to claim 6, characterized in that: The time for each hydrolysis reaction is 4-6 days; The number of batches of the reaction is 4-8 batches.

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