Ecological organic fertilizer and preparation method thereof

Abstract

The invention provides an ecological organic fertilizer and a preparation method thereof, and belongs to the technical field of resource recycling and organic fertilizer preparation. The method comprises the following six steps: grading pretreatment of raw materials, pile construction and fermentation, nitrogen control regulation, delayed release of functional bacteria, nutrient compounding and stabilization of a finished product. A peroxide-metal complex catalyst is adopted to perform normal-temperature pre-oxidation cracking on a refractory carbon source, and an organic acid or a complexing agent is matched to realize oxidation self-termination, so that the wood raw material depolymerization efficiency is remarkably improved; a dual-phase nitrogen control structure composed of organic acid salt-mineral adsorbent is constructed in a pile body, and efficient retention and reutilization of nitrogen are realized by combining reverse-flow back-spraying ammonia-containing liquid; the functional microbial inoculum embedded by the degradable polysaccharide matrix microcapsule is introduced, so that the functional microbial inoculum is stably activated and continuously plays a role in the cooling stage. The finished product is coated with a film and has the advantages of balanced nutrients, slow release and loss control, stable storage and transportation and the like.

Description

Technical Field

[0001] This invention relates to the field of resource recycling and organic fertilizer preparation technology, specifically to an ecological organic fertilizer and its preparation method. Background Technology

[0002] Organic fertilizer, as a crucial resource for green agricultural development, plays an irreplaceable role in improving soil quality, enhancing soil fertility, and promoting healthy crop growth. With the advancement of policies promoting the resource utilization of agricultural waste, various organic resources such as livestock and poultry manure, straw, garden waste, and kitchen waste are widely used in the fermentation production of organic fertilizer. However, existing technologies still face several prominent problems in practical engineering applications: 1. Woody raw materials degrade slowly and have a long fermentation cycle.

[0003] Straw, sawdust, and other recalcitrant carbon sources contain a large amount of lignin and hemicellulose structures. Traditional aerobic composting processes rely on natural microbial systems for their decomposition, resulting in low enzymatic hydrolysis efficiency, long high-temperature maintenance time, and uncontrollable maturation time, which affects the process cycle and resource turnover efficiency.

[0004] 2. Nitrogen loss is severe during the high-temperature stage, and ammonia emission pressure is high.

[0005] During high-temperature fermentation, the organic nitrogen in the raw materials, which is proteinaceous, is converted into ammonium nitrogen and easily volatilizes into ammonia. This not only causes nutrient loss but also increases the load on the tail gas acid washing system, which can easily lead to odor pollution and environmental complaints. Therefore, it is urgent to build an efficient nitrogen control and nitrogen recovery mechanism.

[0006] 3. The activity of functional bacteria is significantly reduced, making it difficult for them to play a role during the ripening stage.

[0007] Traditional functional bacteria are often mixed and used during the initial stage of soil compaction. However, their activity is easily reduced or even deactivated due to environmental stress in the early stage of high temperature. This makes it difficult to realize the soil conditioning and disease resistance and growth promotion functions in the later maturation stage, thus affecting the quality of the final product.

[0008] 4. The finished product has a simple nutrient ratio and a loose structure with poor stability.

[0009] Some processes focus only on increasing nitrogen, phosphorus, and potassium content, neglecting the balance of trace elements and the improvement of organic matter structure. They also lack reasonable mineral regulation and particle stabilization treatment, resulting in high volatilization loss, poor storage and transportation stability, and low field utilization efficiency of the finished fertilizer.

[0010] 5. Lack of systematic process closed-loop design, resulting in large fluctuations in key indicators.

[0011] Currently, most organic fertilizer production processes still rely on empirical control, lacking dynamic feedback mechanisms for key parameters such as redox state, pH regulation, and gas-liquid mass transfer. This makes it difficult to standardize the process, resulting in significant batch-to-batch differences and hindering large-scale and stable promotion.

[0012] Chinese patent CN108383629A discloses an ecological organic fertilizer and its preparation method, but it cannot simultaneously meet the multi-dimensional requirements of degradation efficiency, nitrogen retention, microbial activity and terminal stability.

[0013] In summary, existing technologies still have significant room for improvement in enhancing the pyrolysis efficiency of woody raw materials, constructing nitrogen closed-loop pathways, delaying the activation of functional bacteria, and optimizing the final product performance. Therefore, there is an urgent need to develop an eco-friendly organic fertilizer preparation method that integrates an oxidation self-termination mechanism, a biphasic nitrogen control pathway, and a functional bacteria microcapsule slow-release system. This method aims to achieve synergistic goals of improved degradation efficiency, nitrogen resource utilization, precise release of microbial agents, and multidimensional stability of the finished product, fundamentally optimizing the organic fertilizer production process and final product quality.

[0014] Therefore, this invention proposes an ecological organic fertilizer and its preparation method to solve the problems mentioned above. Summary of the Invention

[0015] In view of the shortcomings of the prior art, the present invention provides an ecological organic fertilizer and its preparation method to solve the problems mentioned in the background art.

[0016] To achieve the above objectives, the present invention provides the following technical solution: S1 raw material classification and pretreatment: The raw materials were classified into readily available carbon sources and recalcitrant carbon sources according to their degradation characteristics. The readily available carbon sources were subjected to short-term anaerobic pre-fermentation to activate the microbial activity; the recalcitrant carbon sources were subjected to room temperature pre-oxidation pyrolysis using a peroxide-metal complex catalyst, with the oxidation-reduction potential controlled at 250–350 mV and the pH at 5.6–6.2 during the pre-oxidation stage.

[0017] The fast-acting carbon source and the recalcitrant carbon source are selected from the following raw materials: the fast-acting carbon source is livestock and poultry manure and kitchen waste, and the recalcitrant carbon source is straw and wood chips; the carbon-nitrogen ratio is adjusted by blending the above two types of raw materials.

[0018] The peroxide-metal complex catalyst includes hydrogen peroxide complexes with iron, copper, or manganese.

[0019] When the residual oxidant content drops to ≤5 mg / kg and the pH returns to 6.4-6.8, immediately spray with organic acid or complexing agent to quench the residual oxidant and complete the pre-oxidation self-termination.

[0020] The organic acid is at least one of citric acid, oxalic acid, or tartaric acid; the complexing agent includes ethylenediaminetetraacetic acid (EDTA) or citrate.

[0021] S2 feedstock mixing and pile construction: The fast-acting carbon source treated with S1 is mixed with a recalcitrant carbon source, and the carbon-nitrogen ratio of the mixture is adjusted to 25-28, with a moisture content of 55%-60%. The particle size of the recalcitrant carbon source is controlled in the range of 15-25 mm.

[0022] The reactor body is constructed using a layered filling method, consisting of a three-layer structure: an acidification and nitrogen reversion layer, a fermentation core layer, and a nitrogen-locking and adsorption layer, from bottom to top. The thickness ratio of the three layers is 1:3–5:1. A directional blowing system is installed at the bottom of the reactor body to form an upward airflow path.

[0023] S3 dual-phase nitrogen control and high-temperature fermentation: Adding organic acid-mineral dual slow-release nitrogen-locking agent to the reactor body creates a nitrogen-controlling channel with early adsorption and late slow release.

[0024] The nitrogen-locking agent is composed of an organic acid salt and a mineral adsorbent, mixed in a mass ratio of 1:1 to 1:3. The organic acid salt is preferably a lactate or acetate; the mineral adsorbent is preferably bentonite or zeolite.

[0025] During the fermentation stage, the pile temperature is maintained at ≥55℃ for no less than 3 days, and the oxygen volume fraction in the gas phase of the pile is no less than 8%. The ammonia in the tail gas is absorbed by acid washing to generate an ammonia-containing solution, which is then injected back into the bottom acidification and nitrogen return layer in a countercurrent manner, i.e., in the opposite direction to the blast airflow.

[0026] S4 Cooling and Curing and Delayed Activation of Functional Bacteria: When the temperature of the reactor core drops to 40±3℃, the pH rises to 7.5~8.0, and the ammonia partial pressure in the reactor core or exhaust gas is below 100 ppm, the release of functional bacteria is triggered.

[0027] The functional bacteria include nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and antagonistic bacteria, mixed in a mass ratio of 1:1:1. The functional bacteria are microencapsulated using a biodegradable polysaccharide matrix, with a membrane thickness of 5–50 μm.

[0028] The biodegradable polysaccharide matrix is ​​selected from at least one of alginate, modified starch, chitosan, or a combination thereof. This microcapsule exhibits responsive characteristics to temperature, pH, and humidity, enabling delayed activation and sustained release of functional bacteria.

[0029] S5 Late-Stage Nutrient Compound: During the later stages of stable maturation of the compost pile, natural mineral powder is added to the upper third of the core layer of the intermediate fermentation layer. The natural mineral powder contains humic acid and at least one trace element selected from silicon, zinc, and boron.

[0030] After replenishment, the moisture content of the pile is maintained at 45% to 50%, and it is continuously matured until the temperature difference between the pile and the ambient temperature is ≤ ±3℃, the pH is stable, the odor is light, the structure is clump-like, the moisture content is moderate, and there is no sticking.

[0031] S6 Finished Product Stabilization Treatment: After maturation, the material is crushed and sieved to the target particle size. A thin film liquid composed of soluble starch and sodium alginate is sprayed on the material at a temperature ≤45℃ to form a dense protective film.

[0032] The film solution is composed of soluble starch and sodium alginate, with a preferred ratio of 200 g: 100 g, dissolved in 20 L of deionized water.

[0033] After spraying, the product is dried at room temperature until the moisture content is ≤20%. Then, it is sealed and packaged with packaging materials that have good moisture-proof and gas-barrier properties to complete the finished product processing.

[0034] This invention provides an eco-friendly organic fertilizer and its preparation method. It has the following beneficial effects: 1. By introducing pre-oxidative pyrolysis technology catalyzed by peroxide-metal complexation, combined with the subsequent quenching self-termination mechanism, the initial decomposition efficiency of lignocellulose raw materials is effectively improved, and the entire composting maturation cycle is significantly shortened.

[0035] 2. A two-phase nitrogen control system composed of organic acid salts and minerals was constructed, and a countercurrent back-spray path of blower and pickling liquid was superimposed. This not only suppressed the ammonia escape during the high-temperature fermentation stage, but also improved the nitrogen refixation and resource recovery capabilities in the pile.

[0036] 3. A functional bacteria delayed release system based on biodegradable polysaccharide microcapsules was designed to achieve timed release and continuous effect of the bacteria during the ripening stage, avoiding the inactivation of active bacteria caused by early release at high temperatures, and enhancing the ecological conditioning and nutrient conversion capabilities during the post-ripening process.

[0037] 4. In the later stage of maturation, natural mineral powder rich in humic acid and trace elements such as silicon, zinc, and boron is introduced, and combined with biological coating treatment that can form a protective film, so as to achieve a dual improvement in the synergistic compounding of nutrient structure and physical stability of the finished organic fertilizer.

[0038] 5. The overall process is constructed with a closed-loop approach of "graded regulation, staged activation, and element recycling". Key parameters are easy to monitor and adjust. It can be adapted to the high-value conversion and utilization of various organic resources such as poultry and livestock manure, crop straw, and fruit and vegetable waste, and has good prospects for promotion and application. Attached Figure Description

[0039] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0040] To enable those skilled in the art to understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0041] The present invention will now be described in detail with reference to the accompanying drawings: Example 1 provides an ecological organic fertilizer and its preparation method, the specific implementation of which is as follows: S1 Raw Material Grading and Pretreatment (1) Take 400 kg of kitchen waste slurry and cow manure filtrate as fast-acting carbon sources, and take 600 kg of wheat straw and poplar wood chips as recalcitrant carbon sources. The particle size D50 of wheat straw and poplar wood chips is controlled at 15–20 mm, and the excess part is recycled.

[0042] (2) Inoculate lactic acid bacteria with a fast-acting carbon source. The inoculation amount of lactic acid bacteria is 0.5% of the mass of the fast-acting carbon source, which is 2 L. The lactic acid bacteria are in liquid culture with an effective viable count of 1×10⁻⁶. 9 CFU / mL. Anaerobic pre-fermentation at 35℃ for 36 h, with low-speed stirring for 5 min every 4 h during the process; and a one-way pressure relief valve at the top to prevent gas accumulation, resulting in a pre-fermentation broth containing low molecular weight organic acids.

[0043] (3) Uniformly spray the recalcitrant carbon source with hydrogen peroxide-iron complex catalyst (H2O2-Fe). The preparation method is as follows: Dilute 30% H2O2 to 3% according to C1V1=C2V2, adding it while stirring and cooling, at a dosage of 10 L / ton of material. Separately weigh FeSO4·7H2O to make the amount of metallic iron added to the wet base material 0.05%, equivalent to 2.5 kg / ton of FeSO4·7H2O, dissolve it in water to make a 5% solution, i.e., 50 L. Use immediately after preparation, spraying it alternately onto the material, first spraying the Fe solution and letting it stand for 10 minutes, then spraying the H2O2 working solution, turning and stirring once at low speed in between. It is not recommended to store H2O2 and iron salts in the same tank beforehand.

[0044] (4) When the unreacted H2O2 in the system is ≤5 mg / kg and the pH returns to 6.4–6.8, spray 25 L of 0.5% citric acid solution onto the recalcitrant carbon source, let it stand for 15 min, and retest to confirm that the unreacted H2O2 in the system is ≤5 mg / kg and the pH returns to 6.4–6.8 before proceeding to the mixing pile. Maintain pH 5.7–6.0 and ORP value 300–340 mV throughout the process.

[0045] A 0.5% citric acid solution refers to a mass fraction of 0.5%, which means that 100 g of solution contains 0.50 g of citric acid, calculated as anhydrous citric acid. Take 10 g of wet material and 90 mL of deionized water to prepare a 1:10 slurry, stir for 1 minute and let stand for 2 minutes. The unreacted H2O2 is measured by measuring the supernatant with hydrogen peroxide test paper with a range of 0–25 ppm. A reading ≤0.5 ppm is equivalent to ≤5 mg / kg in the raw material.

[0046] S2 Raw Material Mixing and Stack Construction (1) Mix the fast-acting / recalcitrant carbon sources according to the trade-off ratio, and adjust the C / N ratio to 26 and the moisture content to 58%.

[0047] (2) The three layers are filled in layers, with the thickness ratio of the bottom acidification and nitrogen return layer, the middle fermentation core layer and the top nitrogen-locking adsorption layer being 1:4:1.

[0048] (3) A directional blower system is arranged below the pile body to form an airflow from bottom to top. The blower volume is 0.3 m³ / (min·m³). When the pile body volume is V (m³), the air supply volume is 0.3×V m³ / min. A gas collection hood and an exhaust branch pipe are installed above the pile body. The exhaust is connected in parallel to the citric acid pickling spray tower. The pickling system starts and stops synchronously with the blower.

[0049] S3 dual-phase nitrogen control and high-temperature fermentation (1) Add lactate to zeolite in a mass ratio of 1:2, at a dosage of 1.5% of the wet mass of the pile, i.e., 5 kg of lactate and 10 kg of zeolite. Solid sodium lactate is used as lactate; Na-type clinoptilolite is used as zeolite. After premixing the lactate and zeolite, spread them on the surface and shallowly plow to a depth of 5 cm.

[0050] (2) Turn on the blower and ferment at high temperature until the pile temperature is ≥55℃. At the same time, perform tail gas back spraying operation and use a portable exhaust oxygen analyzer to monitor the oxygen volume fraction of the gas phase at the top, middle and bottom of the pile in turn, and maintain it in the optimal fermentation oxygen supply range of 8-12%.

[0051] Air flows upwards through the reactor core, carrying the generated volatile NH3 gas, which is collected in the exhaust pipe from the top hood to form tail gas. This tail gas then enters a spray absorption device, or acid washing tower, containing a 0.5% (by mass) citric acid solution. This device neutralizes and absorbs the ammonia in the tail gas with citric acid. The absorbent is maintained at pH 3-4 to improve absorption efficiency. To prevent droplets or acid mist from being discharged with the tail gas, a demister is installed at the top of the tower to intercept fine liquid mist particles, ensuring that the tail gas meets emission standards. The device continuously absorbs NH3 to generate an ammonium-containing solution; subsequently, a metering pump uses 2% of the total wet mass of the reactor core as the daily total return spray volume, quantitatively spraying this ammonia-containing solution back onto the spray pipes above the reactor core, allowing the solution to penetrate from top to bottom to the bottom acidification and nitrogen recovery layer. Because the airflow direction in the reactor core is from bottom to top, and the return spray liquid is from top to bottom, a counter-current return spray is formed; the return spray is completed by the metering pump and nozzles, without relying on blower air to transport the liquid. Ammonia-containing solution, accounting for 2% of the total wet mass of the reactor core, can be injected back into the reactor core in four equally spaced intervals per day, with each interval being 5 L, to avoid localized over-wetting. The exhaust gas back-injection should continue for four days. Once the reactor core temperature begins to drop to ≤42℃, the back-injection should be stopped, and the next step should begin.

[0052] S4 Cooling and Curing and Delayed Activation of Functional Bacteria (1) When the temperature of the stack drops to 39–42℃, the pH rises to 7.6–7.8, and the NH3 concentration in the tail gas is <100 ppm, the release of functional bacteria is triggered. The NH3 concentration is measured using color-changing test paper for NH3 detection.

[0053] (2) A functional bacterial suspension was prepared by mixing nitrogen-fixing bacteria, phosphate-solubilizing bacteria, and antagonistic bacteria in a mass ratio of 1:1:1. The suspension was then uniformly dispersed in a 2% sodium alginate solution. Subsequently, the suspension was dropped into a 2% CaCl2 solution to form gel beads, followed by two surface coatings in a 1% chitosan solution at pH 5.5, resulting in a 20 μm thick composite microcapsule structure. After drying, the microcapsules were added to the fermentation pile after fermentation and cooling to 39–42°C. The gradual degradation of the membrane was triggered by the ambient pH and temperature / humidity, achieving delayed activation and continuous release of the functional bacteria.

[0054] Each gram of freeze-dried powder contains 1×10¹¹ CFU / g of live bacteria, and the dosage of each bacterial agent is 5 g; the dosages of 2% sodium alginate solution, 2% CaCl2 solution, and 1% chitosan solution are 1 L, 2 L, and 2 L, respectively.

[0055] When the temperature of the reactor pile drops to 39–42°C and the pH stabilizes at 7.6–7.8, the NH3 concentration in the exhaust gas remains below 100 ppm for 48 consecutive hours, and the total number of functional bacteria colonies in the reactor pile reaches a stable plateau, it indicates that the microcapsule degradation is complete, the functional bacteria have been largely released, and the nutrient replenishment and final maturation stage can begin. This typically takes 4–6 days, and the NH3 concentration is measured using color-changing test strips for NH3 detection.

[0056] S5 mature stage nutrient compound (1) After the microencapsulated functional bacteria in the pile are released, ventilation and humidity control should be maintained, and weathered lignite humic acid mineral powder should be evenly added to the upper 1 / 3 of the core layer of the intermediate fermentation. The amount added should be 1.0% of the wet base mass of the pile, that is, 10 kg of weathered lignite humic acid mineral powder should be added. This mineral powder contains humic acid and zinc, which helps to improve the mineral balance and soil conditioning function of the final product.

[0057] (2) After the mineral powder is added, the moisture content of the pile is controlled and stabilized at 47%. The pile is then aged for another 10 days under normal temperature and forced air conditions. During this period, the pile temperature, pH, odor, and structural state are continuously monitored. The aging is considered complete according to the following criteria: the pile temperature differs from the ambient temperature by no more than ±3℃, the pH is stable between 7.5 and 8.0, the material is granular, dry, and non-sticky, there is no obvious pungent odor, the moisture content is maintained at 47%, and the seed germination index (GI) is ≥0.8. Once the above conditions are met, the aging is considered complete, and the product stabilization treatment stage begins.

[0058] S6 Finished Product Stabilization Treatment After the reactor body completes curing and reaches a stable state in the S5 stage, it enters the finished product processing stage: (1) The stockpile material is crushed and screened to control the particle size within the range of 2–5 mm. Then, when the material temperature is ≤45℃, a soluble starch-sodium alginate film liquid is evenly sprayed to form a preliminary dense protective film on the particle surface to enhance the product's antioxidant properties and storage and transportation stability.

[0059] Soluble starch-sodium alginate film solution is prepared according to the following ratio: 200 g of soluble starch and 100 g of sodium alginate are added sequentially to 60°C warm deionized water, and dissolved while stirring. The total mass is then increased to 20 L. After stirring to form a homogeneous and transparent solution, it is cooled to room temperature and used as a spraying solution.

[0060] (2) After the spraying is completed, continue to dry the product under normal temperature conditions until the moisture content of the finished product drops to ≤18%; then immediately seal it with moisture-proof and gas-barrier packaging materials and store it in the warehouse according to the standard to prevent it from getting damp and deteriorating or losing nutrients.

[0061] Example 2 provides an ecological organic fertilizer and its preparation method, the specific implementation of which is as follows: S1 Raw Material Grading and Pretreatment (1) The kitchen wastewater after oil-water separation and the recycled poultry and livestock manure were mixed at a mass ratio of 7:3 as a readily available carbon source, and 400 kg was used; corn stalks and hardwood chips were used as a recalcitrant carbon source, and 600 kg was used, while controlling the particle size D of the wood raw materials. 50 The particle size should be 20–25 mm, and any portion exceeding this limit should be re-grinded until it meets the particle size requirements.

[0062] (2) Inoculate the above-mentioned fast-acting carbon source into lactic acid bacteria. The inoculation amount is 0.5% of the mass of the fast-acting carbon source, i.e., 2 L of lactic acid bacteria solution. The viable bacteria count is 1 × 10⁻⁶. 9 The concentration of CFU / mL was anaerobic pre-fermented at 35°C for 24 hours, with stirring for 5 minutes every 4 hours during the process. A one-way pressure relief valve was installed at the top to prevent gas accumulation.

[0063] (3) Spraying the recalcitrant carbon source with H2O2–Mn complex catalyst: Dilute 30% H2O2 to 3% according to the C1V1=C2V2 method, and control the spraying amount to 10 L / ton of wet material; Meanwhile, weigh out MnSO4·H2O powder, add Mn at 0.05% wet basis equivalent to 1.5 kg / ton of MnSO4·H2O, prepare a 5% mass fraction solution, and spray it onto the surface of the material.

[0064] The spraying sequence is as follows: first apply Mn solution, let stand for 10 minutes, then spray H2O2 solution, turning and stirring once in between. Maintain pH 5.7–6.0 and ORP value 300–340 mV throughout the process.

[0065] (4) When the residual H2O2 in the material is ≤5 mg / kg and the pH is adjusted back to 6.5–6.7, spray with oxalic acid + EDTA combined quenching solution: Oxalic acid and EDTA are mixed at a 1:1 mass ratio to prepare a 0.5% mass fraction combined solution (anhydrous), with a spraying rate of 25L / ton of wet material.

[0066] After spraying, let it stand for 15 minutes, and retest to confirm that the pH has stabilized to 6.5–6.7 and the H2O2 residue is ≤5 mg / kg before proceeding to the next step.

[0067] S2 Raw Material Mixing and Stack Construction (1) Mix the readily available carbon source and the recalcitrant carbon source in a balanced ratio, and adjust the C / N ratio to 25–27 and the water content to 56–60%.

[0068] (2) The pile body is constructed as a three-layer structure: bottom acidification and nitrogen return layer, middle fermentation core layer, and upper nitrogen-locking adsorption layer, with a thickness ratio of 1:5:1.

[0069] (3) A directional blower system is installed at the bottom of the stack to form an airflow channel from bottom to top. The blower volume is controlled at 0.25 m³ / (min·m³) and can be dynamically adjusted within the range of 0.1–0.6 according to the ORP feedback signal. A gas collection hood and exhaust pipe are installed at the top of the stack, and the exhaust gas is connected in parallel to the pickling spray tower and started and stopped synchronously.

[0070] S3 dual-phase nitrogen control and high-temperature fermentation (1) After the pile body is constructed, a dual slow-release nitrogen-locking agent composed of acetate and bentonite is uniformly added to the upper nitrogen-locking adsorption layer at a mass ratio of 1:3. The total amount of the additive is 1.2% of the wet base mass, i.e., 3 kg of acetate and 9 kg of bentonite. After premixing, the additive is spread on the surface and lightly mixed to a depth of 5 cm.

[0071] (2) After the blower is started, the high-temperature fermentation stage begins. When the pile temperature is ≥55℃, it is maintained for 4 days. At the same time, the oxygen volume fraction of the gas phase at the upper, middle and lower points of the pile is monitored by a portable exhaust oxygen analyzer. The optimal oxygen supply range for fermentation is maintained at 8–12%.

[0072] (3) The NH3 produced during fermentation enters the acid washing tower with the tail gas and is absorbed to form an ammonium-containing solution. The solution is used as 2% of the wet basis mass as the total daily re-spraying volume using a metering pump and is re-sprayed to the top of the pile. The spraying is carried out from top to bottom and forms a counter-current contact with the blower. The re-spraying cycle is 4 days.

[0073] S4 Cooling and Curing and Delayed Activation of Functional Bacteria (1) When the pile temperature drops to <40℃, the pH stabilizes at 7.5–7.7, and the NH3 concentration in the tail gas is <100 ppm, the delayed release mechanism of functional bacteria is activated. The NH3 concentration is measured using color-changing test paper for NH3 detection.

[0074] (2) The selected functional bacteria were prepared into modified starch microcapsule encapsulation agents: Three functional bacteria, nitrogen-fixing bacteria, phosphate-solubilizing bacteria and antagonistic bacteria, are compounded in a mass ratio of 1:1:1, with a total dosage of 15 g of freeze-dried powder, containing a live bacteria count ≥1×10¹¹CFU / g. The bacterial culture was dispersed in a 3% (w / v) cationic modified starch solution and then added dropwise to a crosslinking solution containing 5% calcium chloride to form gel beads. The beads were then coated twice in a 1.5% (w / v) chitosan solution at pH 5.5 to form microcapsule structures with an embedding layer thickness of 25 μm.

[0075] After drying, the microcapsule-structured bacterial agent is evenly added to the surface of the pile. Under changes in temperature, humidity and pH, the coating gradually degrades, achieving slow release of the bacterial agent, which usually takes 4 to 6 days.

[0076] S5 mature stage nutrient compound (1) After confirming that the microcapsule agent has been released, the number of viable functional bacteria in the pile has reached a stable plateau, the odor has been milded, and the indicators have been stable, weathered lignite humic acid mineral powder is added to the upper 1 / 3 area of ​​the middle fermentation core layer. The amount added is 1.0% of the wet base mass, that is, 10 kg of weathered lignite humic acid mineral powder is added.

[0077] (2) Thereafter, maintain the moisture content of the pile at 45–50% and continue maturation for 10 days until: the difference between the pile temperature and the ambient temperature is ≤ ±3℃; the pH is stable at 7.5–8.0; the odor is non-irritating, the material has formed a granular structure, does not stick together, and is moderately dry; the moisture content is stable at 47%; and the germination index (GI) is ≥ 0.8. Once the above standards are met, maturation is considered complete, and the product processing stage begins.

[0078] S6 Finished Product Stabilization Treatment (1) Crush and screen the stockpile material to a particle size of 2–5 mm, and spray it when the material temperature is controlled to be ≤45℃.

[0079] (2) Preparation of soluble starch-sodium alginate film solution: Weigh 200 g of soluble starch and 100 g of sodium alginate, add them to 60℃ deionized water and stir to dissolve. Make up to 20 L. After cooling, spray evenly on the surface of the material to form a protective film.

[0080] (3) After the spraying is completed, dry the finished product at room temperature with a forced air until the moisture content is ≤20%, and immediately put it into a moisture-proof and gas-barrier package for sealing and storage.

[0081] Applicability notes: This embodiment achieves mild chain scission and antioxidant activation of recalcitrant carbon sources in the pretreatment stage through the combined quenching of oxalic acid and EDTA and the synergistic effect of H2O2–Mn pre-oxidation. In the fermentation stage, a dual-phase nitrogen control strategy using acetate and bentonite and a high ORP-linked oxygen supply strategy is adopted to effectively control the peak ammonia level. Functional bacteria activation is incorporated into the ORP and gas-phase ammonia linkage criterion to avoid premature release. The chitosan system is selected as the microcapsule encapsulation material to achieve good responsiveness and slow-release control, which is suitable for solid waste systems with high protein content and drastic fluctuations in organic nitrogen.

[0082] Comparative Example 1 aims to verify the effect of extending the high-temperature composting time on the overall nitrogen cycle and bacterial release process without H2O2-Fe pre-oxidation and citric acid quenching. The specific implementation method is as follows: S1 Raw Material Grading and Pretreatment (1) Fast-acting carbon source: Same as in Example 1.

[0083] (2) Inoculation of lactic acid bacteria with fast-acting carbon source: Same as in Example 1, the inoculation amount is 0.5%, and the inoculation method and pre-fermentation process are the same.

[0084] (3) Different treatment methods for recalcitrant carbon sources: H2O2-Fe catalytic oxidation and citric acid quenching treatment are not used.

[0085] 600 kg of wheat straw and poplar sawdust were directly sprayed with water to adjust the moisture content, without oxidative modification, and then mixed and stirred slightly before proceeding to the next stage.

[0086] S2 Raw Material Mixing and Stack Construction (1)(2)(3): Same as Example 1, C / N is adjusted to 26, water content is 58%, the layered structure is acidification and nitrogen return layer: fermentation core layer: nitrogen lock adsorption layer = 1:4:1; the arrangement of the blower system is the same as the tail gas acid washing system, and the blower volume is 0.3 m³ / (min·m³).

[0087] S3 High-Temperature Fermentation Stage (1) Lactate-zeolite nitrogen control method and dosage: Same as in Example 1, lactate: zeolite = 1:2, dosage 1.5%.

[0088] (2) Blowering heating logic and tail gas re-injection mechanism: Same as in Example 1, the tail gas is re-injected after ammonia absorption in a 0.5% citric acid washing tower.

[0089] (3) The only difference: the high temperature stage is extended to 7 days, which is 3 days longer than in Example 1, in order to make up for the slow degradation caused by the lack of pre-oxidation treatment.

[0090] S4 Cooling and Curing and Functional Microbial Release (1) Triggering conditions, types of bacterial agents added, microcapsule process, etc.: exactly the same as in Example 1.

[0091] (2) However, due to the extended high temperature time, delayed cooling of the pile and the delayed recovery of pH, the release time of the microbial agent was delayed by 2 days, and the release duration was significantly shortened, resulting in a decrease in the recovery rate of live bacteria.

[0092] S5 mature stage nutrient compound Same as in Example 1, but with the addition of 10 kg of natural mineral powder, using weathered lignite humic acid mineral powder, maintaining a moisture content of 47%, and aging in an air-blown environment for 10 days.

[0093] Observe the differences: Due to insufficient bacterial release activity in the early stage, the degree of granulation of the pile during the maturation period was low, the pH fluctuated greatly, and the seed germination index (GI) was only 0.62~0.68, which did not meet the standard of ≥0.8 set in the example.

[0094] S6 Finished Product Stabilization Treatment Same as in Example 1, 2–5 mm crushing and sieving, sprayed with 20 L of soluble starch-sodium alginate film solution, dried by forced air to ≤18%, and sealed in packaging.

[0095] Comparative Example 2 was used to verify the impact on nitrogen volatilization control, microbial agent triggering, and overall ripening quality when only mineral adsorbents were retained and no organic acid salts were used as buffer adsorbents. The specific implementation method is as follows: S1 Raw Material Grading and Pretreatment Exactly the same as Example 2: S2 Raw Material Mixing and Stack Construction Completely consistent with Example 2: S3 High-Temperature Fermentation and Nitrogen Control Mechanism Adjustment The main differences from Example 2 are as follows: (1) Do not use acetate: Bentonite is uniformly added only to the upper nitrogen-locking adsorption layer, with the dosage maintained at 1.2% of the wet basis mass, i.e., 12 kg of bentonite is added per ton of material, without adding acetate components.

[0096] (2) Keep all other fermentation conditions consistent: S4 Cooling and Curing and Functional Microbial Release Consistent with Example 2: However, due to the instability of the nitrogen control mechanism, the release window may be premature or misaligned, resulting in incomplete degradation of some microcapsules.

[0097] S5 mature stage nutrient compound Consistent with Example 2: However, due to the weak synergy between the initial back spray and the release window, the granule structure was not fully formed, the GI fluctuated greatly, and the maturity of the finished product was lower than that of Example 2.

[0098] S6 Finished Product Stabilization Treatment Consistent with Example 2: To further verify the advantages of the ecological organic fertilizer prepared by this invention in terms of nutrient retention, ammonia volatilization control, functional bacteria survival, and plant growth promotion, fertilizer samples prepared in Examples 1 and 2, as well as Comparative Examples 1 and 2, were selected for the following tests: Total nitrogen retention rate test: Weigh 100 g of each sample, and let it stand in a sealed container at a constant temperature of 60℃ for 7 days to determine the nitrogen loss rate.

[0099] Functional microbial activity assay: Samples were taken from the middle of the compost pile immediately after S5 maturation to determine the viable count (CFU / g) of functional microorganisms at the end of maturation. The survival count (CFU / g) of functional microorganisms in the matured fertilizer was determined using the dilution coating method.

[0100] Odor control capability test: During the third day of the S3 fermentation stage, the tail gas of the pile was sampled and monitored using a PID gas sensor, and the ammonia concentration in the tail gas of the pile was measured by a professional gas sensor (PID type).

[0101] Plant growth promotion experiment: A pot experiment was conducted on tomato seedlings. After applying each sample for 30 days, the plant height and dry matter weight were recorded.

[0102] index Example 1 Example 2 Comparative Example 1 Comparative Example 2 Total nitrogen retention rate (%) 93.5 95.2 81.3 84 Functional bacterial activity assay (CFU / g) −0.00029 <![CDATA[6.2×10 7 ]]> <![CDATA[1.3×10 7 ]]> <![CDATA[2.4×10 7 ]]> Ammonia concentration in exhaust gas (ppm) 68 59 178 152 Table 1 Plant growth promotion experiment sample Plant height (cm) Dry matter mass (g) Plant height increase rate (%) Dry weight gain rate (%) No fertilizer 22.1 1.88 0 0 Example 1 25.8 2.36 16.7 25.6 Example 2 26.7 2.41 20.6 28.2 Comparative Example 1 23.2 2.01 5.0 6.9 Comparative Example 2 23.8 2.06 7.7 9.6 Table 2 This invention provides a composite process route for ecological organic fertilizer and its preparation method, systematically solving the following key problems existing in the traditional composting process: Nitrogen is easily lost through volatility: Traditional methods rely on natural pH buffering and mineral adsorption, which lack precise control and easily lead to large-scale volatilization of ammonia under high temperature and high pH conditions. This invention uses a dual-channel nitrogen control system of organic acid salts and mineral adsorbents, combined with tail gas acid absorption and reinjection technology, to achieve the slow and dynamic release and replenishment of nitrogen, effectively locking in nitrogen.

[0103] Early inactivation or mismatched release timing of functional bacteria: Traditional methods involve direct addition of bacterial agents, which results in low survival rates when subjected to temperature and humidity shocks or drastic pH fluctuations. This invention employs a responsive microencapsulation process, combined with NH3 concentration and ORP multi-signal linkage triggering, to precisely release functional bacteria, ensuring activity and sustainability.

[0104] Low pretreatment efficiency and low utilization rate of recalcitrant substances: Traditional methods involve direct mixing and composting, which makes lignin difficult to degrade, resulting in carbon source waste and prolonged composting cycles. This invention introduces H2O2-Fe / Mn complexation pre-oxidation and quenching regulation technology with citric acid or oxalic acid and EDTA to activate the wood matrix and improve degradability and carbon source utilization efficiency.

[0105] Regarding nitrogen retention, Examples 1 and 2 achieved total nitrogen retention rates of 93.5% and 95.2%, respectively, which were significantly better than Comparative Example 1's 81.3% and Comparative Example 2's 84.0%. This advantage is mainly attributed to the nitrogen control strategy adopted in this invention, which suppresses ammonia volatilization during fermentation and reuses volatile ammonia through tail gas acid adsorption and re-spray technology, thereby achieving a highly efficient closed-loop nitrogen cycle.

[0106] Regarding the activity of functional bacteria, the viable count of functional bacteria in the fertilizer prepared in Example 2 reached 6.2 × 10⁻⁶. 7 The CFU / g was significantly higher than that of Comparative Example 1 (1.3 × 10⁻⁶). 7 And Comparative Example 2's 2.4 × 10 7 This study verified that the "microbial agent microcapsule structure" constructed in this invention can effectively delay the release of microbial agents, avoid the inactivation of microorganisms under high temperature or high ammonia conditions, ensure the precise release of microbial agents in the post-ripening stage, and enhance the subsequent soil improvement and growth promotion capabilities of fertilizers.

[0107] Regarding odor control, the ammonia concentrations in the tail gas of Example 1 and Example 2 on the third day of fermentation were 68 ppm and 59 ppm, respectively, which were significantly better than 178 ppm in Comparative Example 1 and 152 ppm in Comparative Example 2. This fully demonstrates that the "tail gas backflow injection" mechanism proposed in this invention can effectively reduce ammonia emissions, improve the environmental friendliness of the fermentation system, and significantly alleviate the problem of odor nuisance during the organic fertilizer production process.

[0108] Regarding the plant growth-promoting effect, pot experiments showed that the average plant height of tomatoes in the treatment groups of Example 1 and Example 2 was 25.8 cm and 26.7 cm, respectively, which were 16.7% and 20.6% higher than the control group (22.1 cm) without fertilizer. The dry matter weight was 2.36 g and 2.41 g, respectively, which were 25.6% and 28.2% higher than the control group (1.88 g). In contrast, the plant height and dry matter improvement effects of Comparative Examples 1 and 2 were only 5.0% and 7.7% and 6.9% and 9.6%, respectively, verifying the comprehensive advantages of this invention in terms of fertilizer bioactivity and nutrient release efficiency.

[0109] In summary, this invention breaks through the bottlenecks of existing technologies at multiple key process nodes, from the precision of pretreatment strategies, the integration of nitrogen control mechanisms, the intelligent protection of functional bacteria, to the meticulous stabilization of finished products. It achieves systematic optimization of problems such as large nitrogen loss, high inactivation rate of microbial agents, serious odor nuisance, and weak nutrient promotion in traditional composting processes, and has significant technological advancements and application promotion value.

[0110] The product has poor stability and is prone to deterioration: conventional products lack airtight packaging, making them susceptible to moisture absorption, dampness, or volatile deterioration. This invention uses a soluble starch-sodium alginate film sprayed onto the seal to enhance the finished product's antioxidant properties and storage and transportation stability.

[0111] It should be particularly noted that the various embodiments listed in this specification and accompanying drawings are intended to illustrate the technical solutions and advantages of the present invention, and not to limit the scope of protection of the present invention. Without departing from the core ideas and technical effects of the present invention, those skilled in the art can make any form of improvement, substitution, combination, or modification to the structural arrangement, process parameters, material selection, control logic, etc., of the described embodiments; any obvious changes based on the same concept should be considered equivalent solutions of the present invention and should be included within the scope of protection defined by the claims of the present invention. The actual scope of protection of the present invention is determined by the appended claims and should be correctly understood in conjunction with the specification and accompanying drawings.

Claims

1. A method for preparing an ecological organic fertilizer, characterized in that, Includes the following steps: S1. Raw material classification and pretreatment: Organic raw materials are classified into readily available carbon sources and recalcitrant carbon sources according to their degradation characteristics; the readily available carbon sources are subjected to short-term anaerobic pre-fermentation; the recalcitrant carbon sources are sprayed with a peroxide-metal complex catalyst for room temperature pre-oxidation and pyrolysis, controlling the oxidation-reduction potential of the pre-oxidation stage to be 250-350 mV and the pH to be 5.6-6.2; when the residual oxidant content is detected to be ≤5 mg / kg and the pH returns to 6.4-6.8, organic acid or complexing agent is sprayed to quench the residual oxidant, completing the self-termination of pre-oxidation; S2. Raw material mixing and pile construction: The fast-acting carbon source and the recalcitrant carbon source treated in step S1 are mixed, and the carbon-nitrogen ratio of the mixture is adjusted to 25-28 and the moisture content is 55%-60%. The pile is constructed by layering, forming a three-layer structure from bottom to top: the bottom layer is the acidification and nitrogen recovery layer, the middle layer is the fermentation core layer, and the top layer is the nitrogen-locking and adsorption layer. The thickness ratio of the three layers is 1:5:1-1:3:

1. A directional blowing system is arranged below the pile to form an airflow path from bottom to top. S3. Dual-phase nitrogen control and high-temperature fermentation: An organic acid-mineral dual slow-release nitrogen-locking agent is added to the pile. The nitrogen-locking agent is composed of organic acid salts and mineral adsorbents in a mass ratio of 1:1 to 1:3, wherein the organic acid salts are lactates or acetates, and the mineral adsorbents are bentonite or zeolite. When the pile temperature reaches and is maintained at ≥55℃ for no less than 3 days, the tail gas is collected and acid washed to absorb ammonia. The resulting ammonia-containing solution is then sprayed back to the bottom acidification and nitrogen return layer. S4. Cooling and ripening and delayed activation of functional bacteria: When the temperature of the pile body drops to 40±3℃, the pH rises to 7.5~8.0 and the ammonia partial pressure in the pile body or tail gas is lower than 100 ppm, the release of functional bacteria is triggered; the functional bacteria are encapsulated in microcapsules of degradable polysaccharide matrix with an encapsulation layer thickness of 5~50μm, and are gradually released after the triggering conditions are met. S5. Nutrient compounding in the later stage of maturation: In the later stage of maturation, natural mineral powder containing humic acid and at least one trace element among silicon, zinc and boron is added to the pile. The addition location is in the upper 1 / 3 area of ​​the core layer of the middle fermentation, and the moisture content is maintained at 45% to 50%. Continue maturation until it is stable. S6. Finished product stabilization treatment: Crush and screen the matured material, spray a soluble starch-sodium alginate film solution at a material temperature ≤45℃, dry it at room temperature with forced air until the moisture content is ≤20%, and immediately seal and package it.

2. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, The peroxide-metal complex catalyst described in step S1 includes a complex of hydrogen peroxide with iron, copper, or manganese.

3. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, The organic acid used for quenching in step S1 includes at least one of citric acid, oxalic acid, or tartaric acid, and the complexing agent includes EDTA or citrate.

4. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, The particle size of the recalcitrant carbon source in step S2 is controlled to be 15–25 mm.

5. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, The fast-acting carbon source and the recalcitrant carbon source are selected from the following raw materials: the fast-acting carbon source is livestock and poultry manure and kitchen waste, and the recalcitrant carbon source is straw and wood chips; the carbon-nitrogen ratio is adjusted by blending the above two types of raw materials.

6. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, In step S3, the volume fraction of oxygen in the gas phase of the reactor body is maintained at no less than 8%.

7. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, The ammonia-containing solution in step S3 is sprayed back in a counter-current manner, which is opposite to the direction of the blower airflow.

8. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, The biodegradable polysaccharide matrix microcapsules described in step S4 are selected from at least one of alginate, modified starch, chitosan, or a combination thereof.

9. The method for preparing an ecological organic fertilizer according to claim 1, characterized in that, The sealed packaging described in step S6 uses moisture-proof and gas-barrier packaging materials.

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