Green intelligent fertilizer production process

Abstract

The application discloses a kind of green intelligent fertilizer production process, after being crushed and slurrying to organic waste, in SO4 2‑ Under the catalytic oxidation system of SO4 / TiO2-Fe2O3 solid superacid and peroxymonosulfate, it is preliminarily depolymerized at 150 to 160 DEG C and 0.5 to 0.6 MPa, then passes in ozone-containing air to deeply depolymerize, to obtain hydrothermal conversion liquid; after cooling, add biogas liquid or fermentation waste liquid and inorganic nutrient salt to carry out low-temperature chelation, then use citric acid-sodium citrate buffer pair and polyaspartic acid sodium with weight average molecular weight of 4000 to 12000 Da to stabilize, filter to obtain liquid fertilizer with water-soluble organic carbon ratio of ≥70%, small-molecule organic carbon ratio of ≥60%, which can also be spray dried to prepare solid fertilizer. The product is stored at room temperature for 180 days, and the water-insoluble substance is ≤1.5wt%, the nutrients are comprehensive, the stability is good, and the high-value utilization of organic waste is realized.

Description

Technical Field

[0001] This invention belongs to the field of green and intelligent fertilizer production technology, specifically relating to a green and intelligent fertilizer production process. Background Technology

[0002] Water-soluble fertilizers have advantages such as rapid dissolution, easy absorption by crops, and applicability to sprinkler and drip irrigation, leading to increasing demand in modern agriculture. Utilizing organic waste such as crop straw, soybean meal, and biogas slurry to produce water-soluble fertilizers not only achieves resource utilization of waste but also provides organic active substances and mineral nutrients. However, the large molecular structures of lignocellulose and protein in organic waste are stable, and conventional physical crushing, acid-base hydrolysis, or single hydrothermal treatment are insufficient to efficiently convert them into water-soluble small-molecule organic matter. This results in products with high water-insoluble content, low effective organic carbon utilization, and a tendency to flocculate and precipitate during storage, severely affecting the quality and application performance of liquid fertilizers.

[0003] Some existing technologies attempt to depolymerize using methods such as high-temperature hydrothermal methods, acid catalysis, or oxidants, but these methods generally suffer from problems such as incomplete depolymerization, insufficient retention of active functional groups, and poor product stability. For example, when using only oxidants such as ozone or hydrogen peroxide, the oxidation rate is slow and the selectivity is poor. Using homogeneous acid or base catalysts can introduce impurity ions and corrode equipment. At the same time, if the active functional groups in the hydrothermal depolymerization products cannot effectively chelate with nutrients, the nutrients will crystallize or precipitate during long-term storage.

[0004] On the other hand, modern green agriculture not only requires fertilizers to be highly water-soluble and have comprehensive nutrients, but also demands that fertilizers possess "intelligent" characteristics—that is, the ability to actively adjust the nutrient release rate according to crop growth needs or changes in the rhizosphere environment, while simultaneously activating the crop's own stress resistance and absorption efficiency. Currently, most so-called intelligent fertilizers on the market rely on coating controlled-release technology, which is complex and costly, making it difficult to achieve a balance between the resource utilization of organic waste and intelligent functions.

[0005] Therefore, there is an urgent need to develop a new fertilizer production process that combines green and low-carbon features with intelligent crop response capabilities. Summary of the Invention

[0006] The purpose of this invention is to provide a green and intelligent fertilizer production process to solve the problems of incomplete depolymerization of macromolecular organic matter, low proportion of water-soluble organic carbon, high content of water-insoluble matter, poor product storage stability, and lack of intelligent response function in the existing technology.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A green and intelligent fertilizer production process includes the following steps:

[0009] (1) Raw material pretreatment: The organic waste is crushed to a pumpable particle size ≤2mm, and water is added to adjust the solid content to 8 to 15wt% to obtain a slurry raw material; the organic waste is selected from fibrous, protein / slurry or combination thereof, wherein the fibrous is selected from at least one of straw, rice husk, and sugarcane bagasse, and the protein / slurry is selected from at least one of soybean meal, rapeseed meal, and slaughter waste slurry;

[0010] (2) Stepwise enhanced hydrothermal depolymerization: The slurry raw material prepared in step (1) is transferred to a pressure-resistant reactor equipped with a bottom gas distributor. First, SO4 is added. 2- A catalytic oxidation system consisting of a TiO2-Fe2O3 solid superacid catalyst and potassium persulfate composite salt is initiated for 10 to 20 minutes under conditions of 150 to 160°C, 0.5 to 0.6 MPa, and 100 to 300 rpm. Subsequently, while maintaining constant temperature and pressure, air with an ozone content of 2 to 8 mg / L is continuously introduced through the bottom gas distributor, and the reaction continues for 25 to 50 minutes. Through the synergistic effect of the oxidative active species generated by the catalyst-activated potassium persulfate and ozone, the directional deep depolymerization of macromolecular organic matter is achieved, yielding the first hydrothermal conversion liquid.

[0011] (3) Low-temperature nutrient fortification: Cool the first hydrothermal conversion liquid obtained in step (2) to 25 to 35°C, add ① biogas slurry or fermentation waste liquid and ② inorganic nutrients to it, and control the amount of inorganic nutrients added so that the total N+P2O5+K2O content of the prepared fertilizer is 300 to 500 g / L; carry out the chelation reaction at a temperature of 40 to 60°C and a stirring speed of 80 to 150 rpm for 20 to 40 minutes to obtain a mineral-organic composite chelate liquid;

[0012] (4) Staged stabilization treatment: First, add a citrate-sodium citrate buffer pair to the chelate solution in step (3) to adjust the pH to 5.0 to 6.5, then add sodium polyaspartate with a weight average molecular weight of 4000 to 12000 Da, and age and stabilize at 15 to 35°C for 2 to 6 hours to obtain the aged solution.

[0013] (5) Post-processing: After filtering the aging liquid from step (4) to remove unreacted solid impurities, catalyst residues and particulate matter, a nutrient-type water-soluble liquid fertilizer with a water-soluble organic carbon content of ≥70% of the total organic carbon and a water-insoluble content of ≤1.5wt% after 180 days of sealed storage at room temperature is obtained, or optionally spray-dried and granulated to obtain a solid fertilizer product.

[0014] Preferably, the SO4 in step (2) 2-The amount of the TiO2-Fe2O3 solid superacid catalyst added is 1.0 to 3.0 wt% of the solid mass in step (1), and the amount of potassium persulfate complex salt added is 0.5 to 2.0 wt% of the solid mass; the SO4 2- In the / TiO2-Fe2O3 solid superacid catalyst, the molar ratio of TiO2 to Fe2O3 is 15:1 to 25:1, the acid strength H0 ≤ -13.0, and the specific surface area is 80 to 150 m² / g.

[0015] Preferably, the activation of the potassium persulfate complex salt in step (2) and the introduction of ozone have a time-synergistic effect, specifically: in the preliminary depolymerization reaction, SO4 is used... 2- / TiO2-Fe2O3 solid superacid catalyzes potassium persulfate complex salt, generating in situ SO4• - Primary oxidizing active species, mainly •OH, are introduced; then ozone-containing air is introduced, and the ozone works synergistically with the primary oxidizing active species and the active sites on the catalyst surface to initiate a chain reaction to enhance the deep depolymerization of macromolecular organic matter.

[0016] Preferably, in step (2), the volumetric flow rate of the ozone-containing air corresponds to 0.2 to 0.5 L / min·kg of the unit solids in the slurry raw material, and the ozone is introduced in the form of microbubbles through the bottom gas distributor to enhance the mass transfer efficiency between the gas, liquid and solid phases.

[0017] Preferably, in step (3), the molar ratio of the organic active functional groups exposed in the first hydrothermal conversion solution to the metal ions in the added inorganic nutrients is 1:0.5 to 1.0, and the chelation reaction is carried out in a weakly acidic to neutral environment with a pH of 5.5 to 7.0.

[0018] Preferably, the amount of the citric acid-sodium citrate buffer pair added in step (4) is 1.5 to 3.0% of the mass of the chelate obtained in step (3); the amount of the polyaspartic acid sodium added is 0.5 to 1.5% of the mass of the chelate; and the mass ratio of the citric acid-sodium citrate buffer pair to the polyaspartic acid sodium is 1:0.3 to 1.0.

[0019] Furthermore, in the product obtained in step (5), the proportion of water-soluble organic carbon to total organic carbon is ≥70%, and the content of water-insoluble matter is ≤1.5wt% after being stored in a sealed container at room temperature for 180 days; in the water-soluble liquid fertilizer, the proportion of small molecule organic carbon with a molecular weight ≤1000Da to water-soluble organic carbon is ≥60%.

[0020] This invention also provides a green intelligent fertilizer prepared by the above-mentioned production process, wherein water-soluble organic carbon accounts for ≥70% of the total organic carbon content, small molecule organic carbon with a molecular weight ≤1000Da accounts for ≥60% of the water-soluble organic carbon content, and the water-insoluble matter content is ≤1.5wt% after 180 days of sealed storage at room temperature. The fertilizer achieves intelligent fertilization through the nutrient chelation and slow release and root absorption promotion functions of sodium polyaspartate, the crop stress resistance activation function of small molecule organic active substances generated by hydrothermal depolymerization, and the rhizosphere environment response release function of organic-mineral chelates.

[0021] Preferably, the organic waste is a combination of fibrous waste and protein / slurry waste, wherein the fibrous waste is straw, the protein / slurry waste is soybean meal, and the dry weight ratio of straw to soybean meal is 1:0.8 to 1.5.

[0022] Preferably, the SO4 in step (2) 2- The TiO2-Fe2O3 solid superacid catalyst is a heterogeneous particulate with a particle size of 0.1 to 1.0 mm. It is separated and recovered by filtration in step (5), and regenerated by washing with dilute sulfuric acid and calcining at 400 to 500 °C. It is recycled for step (2) at least 5 times, and the catalytic activity retention rate is ≥90%. In step (5), if the target product is a liquid water-soluble fertilizer, water is added or concentrated to adjust to the specified nutrient concentration before precision filtration and filling. If the target product is a solid water-soluble fertilizer, the aged liquid is spray-dried and granulated. The inlet air temperature of the spray drying is 160 to 190 °C and the outlet air temperature is 85 to 100 °C.

[0023] Beneficial effects

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. This invention enhances hydrothermal depolymerization through a stepwise approach. First, it utilizes a solid superacid to catalyze potassium persulfate to generate primary oxidizing active species such as sulfate radicals and hydroxyl radicals in situ, which initially break down organic macromolecules. Then, it introduces ozone-containing air, where the ozone synergistically interacts with the aforementioned free radicals and the active sites on the catalyst surface to form a chain oxidation reaction. This achieves deep depolymerization of stubborn macromolecules such as lignocellulose and proteins, significantly increasing the proportion of water-soluble organic carbon and small-molecule organic carbon.

[0026] 2. This invention uses heterogeneous SO4. 2- The TiO2-Fe2O3 solid superacid catalyst not only has high catalytic activity, but is also easy to separate, recover and regenerate from the product, and can be recycled more than 5 times with a catalytic activity retention rate of ≥90%, which reduces production costs and the risk of secondary pollution.

[0027] 3. This invention chelates hydrothermal conversion liquid with biogas slurry or fermentation waste liquid and inorganic nutrients at low temperature, which not only replenishes endogenous organic active substances and trace elements, but also promotes the coordination and chelation of organic active functional groups with metal ions, effectively "anchoring" the fast-acting nutrients in the organic molecular skeleton and avoiding crystallization.

[0028] 4. This invention uses a citric acid-sodium citrate buffer to controllably adjust the pH and performs aging stabilization treatment in the presence of sodium polyaspartate of a specific molecular weight. Through the synergistic effect of the buffer system and the polymer dispersant, a protective layer is formed on the surface of the colloidal particles, which effectively inhibits the formation and aggregation of water-insoluble matter. After 180 days of sealed storage at room temperature, the water-insoluble matter content of the product is ≤1.5wt%, which greatly extends the shelf life of the water-soluble fertilizer. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the process flow for the green and intelligent fertilizer production process of this invention.

[0030] Figure 2 This is a performance comparison chart of green intelligent fertilizers according to embodiments of the present invention. Detailed Implementation

[0031] The present invention will be further described in detail below through specific embodiments and comparative examples, but the scope of protection of the present invention is not limited thereto.

[0032] In the following examples and comparative examples, the SO4 used 2- The TiO2-Fe2O3 solid superacid catalyst was prepared in the laboratory, with a TiO2 to Fe2O3 molar ratio of 20:1, an acid strength H0≈-13.5, a specific surface area of ​​approximately 120 m² / g, and a particle size of 0.2 to 0.8 mm. Potassium persulfate (Oxone) was purchased commercially. Ozone-containing air was generated by an ozone generator and mixed with air to the required concentration. The biogas slurry was taken from the anaerobic digester of a normally operating pig farm and filtered through an 80-mesh sieve before use; the fermentation waste liquid was the waste liquid after separating the bacterial cells from glutamic acid fermentation. Inorganic nutrients were prepared according to the target nutrient concentration using urea, potassium dihydrogen phosphate, potassium sulfate, and appropriate trace elements. The proportion of water-soluble organic carbon was determined using a TOC analyzer. The total organic carbon content of the whole solution and the filtrate passing through a 0.45 μm filter membrane were measured after the fertilizer was diluted, and the proportion was calculated. The molecular weight distribution was determined by gel permeation chromatography, and the peak area percentage of fractions ≤1000 Da was statistically analyzed. The water-insoluble matter was weighed according to the total mass of the fertilizer, and the weight was calculated after centrifugation and drying.

[0033] Example 1

[0034] (1) Mix corn stalks and soybean meal at a dry weight ratio of 1:1, crush them to a particle size of ≤2mm, add water to adjust the solid content to 12wt%, and obtain a slurry raw material.

[0035] (2) Add the slurry raw material to a pressure-resistant reactor equipped with a bottom gas distributor, add 2.0 wt% of the above-mentioned solid superacid catalyst and 1.2 wt% of potassium persulfate composite salt, seal the reactor, heat to 155°C and maintain the pressure at 0.55 MPa, and carry out the initial depolymerization reaction for 15 minutes at a stirring speed of 200 rpm; then keep the temperature and pressure constant, introduce air with an ozone content of 5 mg / L in the form of microbubbles from the bottom gas distributor, with an air volume flow rate of 0.35 L / min·kg·solids, and continue the reaction for 35 minutes to obtain the first hydrothermal conversion liquid.

[0036] (3) Cool the first hydrothermal conversion liquid to 30°C, add 15% of its mass of biogas slurry, and add inorganic nutrients until the total nutrient content (N+P2O5+K2O) is 400g / L; determine the total amount of organic active functional groups in the conversion liquid by potentiometric titration, control the molar ratio of functional groups to metal ions to be about 1:0.75, adjust the pH to 6.0, and carry out the chelation reaction for 30 minutes at a temperature of 50°C and a stirring speed of 120rpm to obtain a mineral-organic composite chelate liquid.

[0037] (4) Add 2.0% of the chelate mass of the chelate solution to the citric acid-sodium citrate buffer pair, mix thoroughly, and measure the pH to be 5.8; then add 1.0% of the chelate mass of sodium polyaspartate with a weight average molecular weight of about 8000 Da (buffer pair to sodium polyaspartate mass ratio 1:0.5), and age at 25°C for 4 hours to obtain the aged solution.

[0038] (5) The aged liquid is filtered through a plate and frame filter to remove unreacted solid impurities and catalyst residues. The collected filtrate is green intelligent liquid fertilizer, and various indicators are tested by sampling.

[0039] The liquid fertilizer obtained in this embodiment was diluted 500 times and used in a hydroponic experiment on maize seedlings, compared with an inorganic nutrient solution of equal nutrient content. After 14 days of cultivation, the results showed that the root dry weight of maize in the treatment group increased by 27.3%, the total nitrogen uptake increased by 19.5%, and under simulated drought stress (PEG6000, -0.5MPa), the relative water content of seedling leaves was 18.6% higher than that of the control, and the malondialdehyde content decreased by 22.4%, confirming that the small molecule active substances of the fertilizer have stress-resistant activation functions. The slow-release characteristics of nutrients were verified by soil culture: after the fertilizer was applied to the soil, its available nitrogen was released continuously and steadily over 28 days, without an initial explosive release peak, which is consistent with the crop's S-shaped absorption curve.

[0040] Example 2

[0041] (1) Mix sugarcane bagasse and rapeseed meal at a dry basis mass ratio of 1:1.2, crush to ≤2mm, and add water to adjust to a solid content of 10wt%.

[0042] (2) Add 2.5wt% solid superacid catalyst and 1.5wt% potassium persulfate composite salt to the slurry raw material, and stir at 250rpm for 20 minutes at 160℃ and 0.6MPa for initial depolymerization. Then introduce air with an ozone content of 8mg / L at a flow rate of 0.5 L / min·kg·solids for deep reaction for 25 minutes.

[0043] (3) Cool to 32°C, add fermentation waste liquid (glutamic acid), add inorganic nutrients to the total nutrient content of 450g / L, control the molar ratio of functional groups to metal ions to 1:0.8, chelate pH 6.5, temperature 55°C, and react for 25 minutes.

[0044] (4) Add 2.5% of the chelating solution of citric acid-sodium citrate buffer to adjust the pH to 6.2, then add 1.2% of sodium polyaspartate with a weight average molecular weight of 10,000 Da, and age at 30°C for 3 hours.

[0045] (5) After filtration, a green intelligent liquid fertilizer was obtained. A corn seedling experiment was conducted using the same method as in Example 1. Root dry weight increased by 24.6%, total nitrogen uptake increased by 17.2%, and relative leaf water content under drought stress increased by 16.8%.

[0046] Example 3 (Catalyst Regeneration)

[0047] Following the process described in Example 1, a fresh catalyst was used for the first time. After each reaction, the catalyst residue retained by filtration was collected, washed with 2wt% dilute sulfuric acid, then washed with deionized water until neutral, and regenerated by calcination at 450°C for 2 hours. The regenerated catalyst was reused in step (2) for a total of 5 cycles, and the product indicators for each cycle are shown in Table 2. The results showed that the catalytic activity retention rate was still 90.8% after 5 cycles, and the proportion of water-soluble organic carbon and small molecules in the product met the requirements. The product obtained from the 5th catalyst cycle maintained stable intelligent functions, and the root-promoting effect on corn seedlings was still more than 96% of that of the fresh catalyst, demonstrating reliable intelligent characteristics.

[0048] Comparative Example 1

[0049] The process is basically the same as in Example 1, except that SO4 is not added in step (2). 2- The process involves using a TiO2-Fe2O3 solid superacid catalyst and a potassium persulfate composite salt, with ozone-containing air introduced separately, while the other steps remain the same.

[0050] Comparative Example 2

[0051] The process is basically the same as in Example 1, except that: in step (2), only the initial depolymerization reaction is carried out for 20 minutes, and then ozone-containing air is not introduced for deep depolymerization, and the temperature is directly reduced to proceed to the subsequent steps.

[0052] Comparative Example 3

[0053] The process is basically the same as in Example 1, except that: in step (4), citric acid-sodium citrate buffer and sodium polyaspartate are not added, and dilute nitric acid / potassium hydroxide is used to adjust the pH of the chelating solution to 5.8, and then the solution is directly aged at 25°C for 4 hours.

[0054] Comparative Example 4

[0055] The process is basically the same as in Example 1, except that: in step (3), biogas slurry is not added, and temperature-controlled chelation reaction at 40 to 60°C is not carried out. Instead, inorganic nutrients are simply stirred and mixed with cooled hydrothermal conversion liquid at room temperature, and then directly proceeded to step (4).

[0056] The main performance test results of the liquid fertilizers obtained in Examples 1 to 3 and Comparative Examples 1 to 4 are listed in Table 1; the catalyst cycle performance and corresponding product indicators of Example 3 are listed in Table 2.

[0057] Table 1. Performance comparison of liquid fertilizers prepared in each embodiment and comparative example.

[0058] Example 1 76.5 65.2 1.2 400 Example 2 73.8 62.5 1.4 450 Example 3 (5th cycle) 74.2 63.1 1.3 400 Comparative Example 1 46.3 31.7 4.5 400 Comparative Example 2 58.7 42.1 3.2 400 Comparative Example 3 75.8 64.5 2.8 400 Comparative Example 4 67.4 53.8 2.1 400

[0059] Table 2 Catalyst Recycling Performance in Example 3

[0060] 1 (Fresh) 100.0 76.5 65.2 2 98.5 76.0 64.8 3 96.8 75.3 64.1

[0061] Conclusion Analysis

[0062] As shown in Table 1, through the synergistic effects of stepwise enhanced depolymerization using "solid superacid / potassium peroxymonosulfate + ozone", low-temperature nutrient fortification, and stabilization treatment with citric acid-sodium citrate / sodium polyaspartate, the liquid fertilizers obtained in Examples 1 to 3 all had a water-soluble organic carbon content of over 70%, a small molecule organic carbon content of ≤1000Da of over 60%, and a water-insoluble matter content of no more than 1.5wt% after 180 days of sealed storage at room temperature, demonstrating excellent water solubility and storage stability, while also possessing significant intelligent growth-promoting and stress-resistance functions;

[0063] Comparative Example 1, lacking a catalytic oxidation system and relying solely on ozone oxidation, suffered from insufficient depolymerization of large organic molecules, resulting in a water-soluble organic carbon content of only 46.3% and a low proportion of small molecules, leading to a high water-insoluble content of 4.5 wt% after storage. Comparative Example 2, without ozone introduction for deep depolymerization, exhibited significantly insufficient depolymerization, with water-insoluble content far exceeding 1.5 wt%.

[0064] Comparative Example 3 omitted the buffer pair and sodium polyaspartate stabilization treatment. Although the initial water-soluble organic carbon ratio was still relatively high, due to the lack of polymer dispersion and colloidal protection, the active components re-flocculated during storage. After 180 days, the water-insoluble matter content increased to 2.8 wt%, which could not meet the requirements for long-term storage of the product. Furthermore, due to the lack of sodium polyaspartate, the product lost its slow-release and absorption-promoting intelligence, resulting in the product not possessing complete intelligent fertilizer supply characteristics.

[0065] Comparative Example 4 did not add biogas slurry and did not perform temperature-controlled chelation. The organic active functional groups and metal ions failed to bind effectively. Not only did the proportion of water-soluble organic carbon decrease to 67.4% and the proportion of small molecules decrease, but the storage stability also deteriorated to 2.1 wt%. Furthermore, it lacked an organic-mineral chelation response release mechanism, resulting in the product not having complete intelligent fertilizer supply characteristics.

[0066] As can be seen from Table 2, SO4 2- The TiO2-Fe2O3 solid superacid catalyst can be recycled more than 5 times through simple dilute sulfuric acid washing and calcination regeneration, and its catalytic activity retention rate is still higher than 90%. Moreover, the key indicators and intelligent characteristics of the prepared products continue to meet the requirements.

[0067] In summary, the method provided by this invention efficiently transforms organic waste into a green and intelligent fertilizer with high water-soluble organic carbon content, a large proportion of small molecules, and excellent storage stability through a comprehensive approach of stepwise enhanced hydrothermal depolymerization, low-temperature chelation nutrient enhancement, and staged stabilization. This achieves synergistic effects of nutrient slow release, stress resistance activation, and rhizosphere response. At the same time, the catalyst is recyclable and regenerable, making the process green and economical, and it has significant prospects for industrial application.

[0068] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A green and intelligent fertilizer production process, characterized in that, Includes the following steps: (1) Raw material pretreatment: The organic waste is crushed to a pumpable particle size ≤2mm, and water is added to adjust the solid content to 8 to 15wt% to obtain a slurry raw material; the organic waste is selected from fibrous, protein / slurry or combination thereof, wherein the fibrous is selected from at least one of straw, rice husk, and sugarcane bagasse, and the protein / slurry is selected from at least one of soybean meal, rapeseed meal, and slaughter waste slurry; (2) Stepwise enhanced hydrothermal depolymerization: The slurry raw material prepared in step (1) is transferred to a pressure-resistant reactor equipped with a bottom gas distributor. First, SO4 is added. 2- A catalytic oxidation system consisting of a TiO2-Fe2O3 solid superacid catalyst and potassium persulfate composite salt is initiated for 10 to 20 minutes under conditions of 150 to 160°C, 0.5 to 0.6 MPa, and 100 to 300 rpm. Subsequently, while maintaining constant temperature and pressure, air with an ozone content of 2 to 8 mg / L is continuously introduced through the bottom gas distributor, and the reaction continues for 25 to 50 minutes. Through the synergistic effect of the oxidative active species generated by the catalyst-activated potassium persulfate and ozone, the directional deep depolymerization of macromolecular organic matter is achieved, yielding the first hydrothermal conversion liquid. (3) Low-temperature nutrient fortification: Cool the first hydrothermal conversion liquid obtained in step (2) to 25 to 35°C, add ① biogas slurry or fermentation waste liquid and ② inorganic nutrients to it, and control the amount of inorganic nutrients added so that the total N+P2O5+K2O content of the prepared fertilizer is 300 to 500 g / L; carry out the chelation reaction at a temperature of 40 to 60°C and a stirring speed of 80 to 150 rpm for 20 to 40 minutes to obtain a mineral-organic composite chelate liquid; (4) Staged stabilization treatment: First, add a citrate-sodium citrate buffer pair to the chelate solution in step (3) to adjust the pH to 5.0 to 6.5, then add sodium polyaspartate with a weight average molecular weight of 4000 to 12000 Da, and age and stabilize at 15 to 35°C for 2 to 6 hours to obtain the aged solution. (5) Post-processing: After filtering the aging liquid from step (4) to remove unreacted solid impurities, catalyst residues and particulate matter, a green intelligent liquid fertilizer with water-soluble organic carbon accounting for ≥70% of the total organic carbon and water-insoluble matter content ≤1.5wt% after 180 days of sealed storage at room temperature is obtained, or optionally spray-dried and granulated to obtain a solid fertilizer product.

2. The production process according to claim 1, characterized in that, The SO4 mentioned in step (2) 2- The amount of the TiO2-Fe2O3 solid superacid catalyst added is 1.0 to 3.0 wt% of the solid mass in step (1), and the amount of potassium persulfate complex salt added is 0.5 to 2.0 wt% of the solid mass; the SO4 2- In the / TiO2-Fe2O3 solid superacid catalyst, the molar ratio of TiO2 to Fe2O3 is 15:1 to 25:1, the acid strength H0 ≤ -13.0, and the specific surface area is 80 to 150 m2 / g.

3. The production process according to claim 1, characterized in that, The activation of the potassium persulfate complex salt in step (2) and the introduction of ozone have a time-dependent synergistic effect, specifically: in the preliminary depolymerization reaction, SO4 is used... 2- / TiO2-Fe2O3 solid superacid catalyzes potassium persulfate complex salt, generating in situ SO4• - Primary oxidizing active species, mainly •OH; Ozone-containing air is then introduced, and the ozone works synergistically with the primary oxidizing active species and the active sites on the catalyst surface to trigger a chain reaction that enhances the deep depolymerization of macromolecular organic matter.

4. The production process according to claim 3, characterized in that, In step (2), the volumetric flow rate of ozone-containing air corresponds to 0.2 to 0.5 L / min·kg of unit solids in the slurry raw material, and the ozone is introduced in the form of microbubbles through the bottom gas distributor to enhance the mass transfer efficiency between the gas-liquid-solid three phases.

5. The production process according to claim 1, characterized in that, In step (3), the molar ratio of the organic active functional groups exposed in the first hydrothermal conversion solution to the metal ions in the added inorganic nutrients is 1:0.5 to 1.0, and the chelation reaction is carried out in a weakly acidic to neutral environment with a pH of 5.5 to 7.

0.

6. The production process according to claim 1, characterized in that, The amount of the citric acid-sodium citrate buffer pair added in step (4) is 1.5 to 3.0% of the mass of the chelate obtained in step (3); the amount of the polyaspartic acid sodium added is 0.5 to 1.5% of the mass of the chelate; and the mass ratio of the citric acid-sodium citrate buffer pair to the polyaspartic acid sodium is 1:0.3 to 1.

0.

7. The production process according to any one of claims 1 to 6, characterized in that, In the product obtained in step (5), the proportion of water-soluble organic carbon to total organic carbon is ≥70%, and the content of water-insoluble matter is ≤1.5wt% after 180 days of sealed storage at room temperature; in the water-soluble liquid fertilizer, the proportion of small molecule organic carbon with a molecular weight ≤1000Da to water-soluble organic carbon is ≥60%.

8. A green and intelligent fertilizer, characterized in that, It is prepared by the production process described in any one of claims 1 to 7; the proportion of water-soluble organic carbon in the fertilizer is ≥70% of the total organic carbon content, the proportion of small molecule organic carbon with a molecular weight ≤1000Da is ≥60% of the water-soluble organic carbon content, and the content of water-insoluble matter is ≤1.5wt% after 180 days of sealed storage at room temperature. Furthermore, the fertilizer achieves intelligent fertilization through the nutrient chelation and slow release and root absorption promotion function of sodium polyaspartate, the crop stress resistance activation function of small molecule organic active substances generated by hydrothermal depolymerization, and the rhizosphere environment response release function of organic-mineral chelates.

9. The production process according to claim 1, characterized in that, The organic waste is selected as a combination of fibrous waste and protein / slurry waste, wherein the fibrous waste is straw and the protein / slurry waste is soybean meal, and the dry weight ratio of straw to soybean meal is 1:0.8 to 1.

5.

10. The production process according to claim 1, characterized in that, The SO4 mentioned in step (2) 2- The TiO2-Fe2O3 solid superacid catalyst is a heterogeneous particulate catalyst with a particle size of 0.1 to 1.0 mm. It is separated and recovered by filtration in step (5), and regenerated by washing with dilute sulfuric acid and calcining at 400 to 500 °C. It is recycled for step (2) at least 5 times, and the catalytic activity retention rate is ≥90%. In step (5), if the target product is a liquid water-soluble fertilizer, water is added or concentrated to adjust to the specified nutrient concentration before precision filtration and filling. If the target product is a solid water-soluble fertilizer, the aged liquid will be spray-dried and granulated. The inlet air temperature for spray drying is 160 to 190°C, and the outlet air temperature is 85 to 100°C.

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