Method for extracting phosphorus and potassium elements from poultry manure based on organic mixed leaching agent, fertilizer preparation method thereof, liquid fertilizer and soil conditioner

Abstract

The invention provides a method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent, a fertilizer preparation method thereof, a liquid fertilizer and a soil amend.The method for extracting the phosphorus and potassium elements comprises the steps that S1, the poultry manure is subjected to high-temperature activation treatment, organic phosphorus in the manure is converted into soluble phosphate, and the soluble phosphate is added into the poultry manure; obtaining an activated material of the high-calcium ash; s2, washing the activated material with water, removing soluble salt, and drying to obtain a prefabricated material; and S3, oxalic acid is added into the prefabricated material for a first-stage mixing reaction, then any one of organic acid or an organic chelating agent is added for a second-stage mixing reaction, solid-liquid separation is conducted, and leachate is extracted. Therefore, the limitation of a traditional biological fermentation path is broken through, and liquid phosphorus and potassium elements are directionally and efficiently extracted from the poultry manure.

Description

Technical Field

[0001] The present invention relates to the technology for the resource utilization of organic solid waste, and particularly to a method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent, as well as a fertilizer production method, a liquid fertilizer, and a soil conditioner thereof. Background Art

[0002] As a large amount of organic solid waste, poultry manure contains essential nutrients such as phosphorus and potassium for plant growth and is an excellent raw material for fertilizers. However, improper treatment is likely to pollute the environment and cause waste of resources. For example, chicken manure is rich in nutrients such as nitrogen, phosphorus, and potassium. When a large amount of chicken manure is piled up, the nitrogen in it will be converted into ammonia gas and volatilized into the air under the action of microorganisms, producing a pungent smell and causing air pollution. Moreover, the ammonia discharged into the atmosphere will also cause environmental problems such as acid rain. At the same time, if the phosphorus element in chicken manure flows into water bodies with rainwater scouring, it will lead to eutrophication of water bodies, damage the aquatic ecological balance, and cause water quality deterioration.

[0003] Currently, the existing poultry manure is mainly utilized in the form of fermentation composting or processed into solid fertilizers to improve soil structure, increase soil fertility, and promote the growth of crops. However, when using such fertilizers, due to relying on microbial decomposition, the release is slow, resulting in poor timeliness of the absorption of nutrient elements by crops and unsatisfactory absorption effects.

[0004] Therefore, to solve such problems, the prior art has proposed a liquid fertilizer solution to directly extract the liquid containing phosphorus and potassium elements from poultry manure to support fertilization by spraying and irrigation methods, which is convenient to directly apply to the roots of plants, or dilute the liquid fertilizer and then fertilize by irrigation, thereby effectively improving the absorption effect of plants.

[0005] However, the existing liquid fertilizer raw materials are usually refined based on biomass fermentation methods (such as "A Liquid Fertilizer Based on Biomass Fermentation and Its Preparation Method", patent publication number CN116425599A). Therefore, there are problems such as cumbersome preparation processes, complex raw materials, difficult component regulation during the fermentation process, and easy generation of unpleasant odors and microbial secretions. Thus, it is difficult to industrialize on a large scale.

[0006] It can be seen that how to break through the limitations of traditional biological fermentation paths and efficiently extract liquid phosphorus and potassium elements from poultry manure in a targeted manner is the key to enhancing the industrial scale and market competitiveness. Summary of the Invention

[0007] For this reason, the main purpose of the present invention is to provide a method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent, as well as a fertilizer production method, a liquid fertilizer, and a soil conditioner thereof, so as to solve the problems mentioned in the background art.

[0008] To achieve the above object, according to one aspect of the present invention, there is provided a method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent, and the steps thereof include:

[0009] Step S1: Perform high-temperature activation treatment on poultry manure to convert the organic phosphorus in the manure into soluble phosphate, and obtain an activated material of high-calcium ash residue;

[0010] Step S2: Wash the activated material with water to remove soluble salts, and dry it to obtain a prefabricated material;

[0011] Step S3: Add oxalic acid to the prefabricated material for a first-stage mixing reaction, and then add any one of organic acids or organic chelating agents for a second-stage mixing reaction, and then perform solid-liquid separation to extract the leaching solution.

[0012] In a possible preferred embodiment, the organic acid is any one of citric acid, salicylic acid, and adipic acid; the organic chelating agent is any one of EDTA-2Na and ammonium citrate.

[0013] In a possible preferred embodiment, the mass concentration of the oxalic acid is 3-8%.

[0014] In a possible preferred embodiment, the mass concentration of the organic acid is 2-3%, and the mass concentration of the chelating agent is 0.5-1.5%.

[0015] In a possible preferred embodiment, in step S3, the solid-liquid ratio of the oxalic acid to the prefabricated material is 10-50 mL:1 g.

[0016] In a possible preferred embodiment, the first-stage and second-stage mixing reactions are carried out under constant temperature at room temperature and normal pressure.

[0017] To achieve the above object, corresponding to the above method, according to another aspect of the present invention, there is also provided a liquid fertilizer, which includes: the leaching solution obtained by any one of the above methods.

[0018] To achieve the above object, corresponding to the above method, according to another aspect of the present invention, there is also provided a method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent to produce fertilizer, and the steps include:

[0019] Perform composition regulation on the leaching solution obtained by any one of the above methods, adjust the pH value and then perform concentration treatment.

[0020] In a possible preferred embodiment, the composition regulation step includes:

[0021] Select one or more of urea, ammonium nitrate, and dipotassium hydrogen phosphate as supplementary elements and add them to the leaching solution.

[0022] In a possible preferred embodiment, the pH adjustment step comprises:

[0023] Select either ammonia water or potassium hydroxide as a regulator to adjust the pH value to above 3.0.

[0024] In order to achieve the above-mentioned purpose, corresponding to the above-mentioned method, according to another aspect of the present invention, a soil conditioner is also provided, which comprises: the dry residue obtained by solid-liquid separation in any of the above methods for extracting phosphorus and potassium elements from poultry manure based on organic mixed leaching agents.

[0025] The method for extracting phosphorus and potassium from poultry manure based on an organic mixed leaching agent and the fertilizer making method, liquid fertilizer and soil improver provided by the present invention cleverly propose a high-temperature activation-two-stage mixed leaching reaction synergistic process. On the one hand, organic phosphorus in chicken manure can be converted into soluble phosphates by incineration, while pathogen inactivation, antibiotic degradation and heavy metal passivation can be completed. In addition, in combination with multiple water washing processes, soluble salts can be removed, eliminating the hidden danger of phosphorus reprecipitation effect caused by alkaline oxides in subsequent acid leaching. On the other hand, in combination with the two-stage step-by-step acid leaching process, phosphorus reprecipitation can be effectively inhibited, thereby significantly improving the phosphorus and potassium leaching rates.

[0026] This not only breaks through the limitations and disadvantages of traditional biological fermentation pathways, but also has the advantages of low corrosion and low waste acid treatment costs compared to inorganic acid leaching solutions. More importantly, the organic acid system is biodegradable, and the leaching solution can be used in organic agriculture without complex neutralization treatment, which meets the needs of green agriculture and pollution-free agricultural product production.

[0027] In addition, compared with the traditional composting method, this solution has greatly improved the extraction efficiency, and the processing cycle has been compressed from 15-30 days to several hours. At the same time, the residue after the reaction can also be used as a soil conditioner, thus opening up the closed-loop chain of "element extraction-pollution control-residue regeneration" for organic solid waste, and overcoming the industry problems such as incomplete degradation of antibiotics, low conversion rate of traditional liquid fertilizers, and serious secondary pollution in traditional processes, providing a revolutionary solution for the resource utilization of livestock and poultry manure with high efficiency, low cost and low emission characteristics. Therefore, it has the conditions for large-scale application in industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0029] Figure 1 A schematic diagram of the steps of the method for extracting phosphorus and potassium elements from poultry feces based on an organic mixed leaching agent of the present invention;

[0030] Figure 2Schematic diagram of the process of the method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent according to the present invention;

[0031] Figure 3 Schematic diagram of the process of the method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent to produce fertilizer according to the present invention. Detailed implementation manners

[0032] In order to enable those skilled in the art to better understand the technical solution of the present invention, the following will clearly and completely describe the specific technical solution of the present invention in combination with embodiments, so as to help those skilled in the art further understand the present invention. Obviously, the embodiments described in this case are only a part of the embodiments of the present invention, rather than all the embodiments. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention and without conflict with each other, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of disclosure and protection of the present invention.

[0033] In addition, the terms "first", "second", "S1", "S2", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects, and do not necessarily need to describe a specific order or sequence. It should be understood that the features used in this way can be interchanged under appropriate circumstances, so that the embodiments of the present invention described here can be implemented in an order other than those described here. At the same time, the stages recorded in each step are not forced to be implemented in the same step. It should be understood that the implementation order of the content in each step stage can be adjusted and interchanged without violating the inventive concept, so that the step embodiments of the present invention described here can be implemented in an order other than those described here.

[0034] In addition, the terms "include" and "have" and any variations thereof in the present invention are intended to cover non-exclusive inclusion. Unless otherwise clearly specified and limited, the terms "set", "arrange", "install", "connect", "couple" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this case can be understood according to specific situations in combination with the prior art.

[0035] Also in this specification, when the range of a variable is recited, it should be understood that the variable includes all values within the recited range (including the endpoints of the range). For example, it should be understood that the range of "5 - 10" includes not only the values of 5, 6, 7, 8, 9, and 10, but also any sub - ranges such as 6 - 10, 7 - 10, 6 - 9, 7 - 9, etc., and also any values between integers within the scope of the recited range, such as 5.5, 6.5, 7.5, 5.5 - 8.5, and 6.59. In addition, it should be understood that a range such as "10% - 30%" includes not only values such as 10%, 11%, 12%, 13%, etc. and all integers up to 30% (including 30%), but also any sub - ranges such as 10% - 15%, 12% - 18%, 20% - 30%, etc., and also any values between integers within the scope of the recited range, such as 10.5%, 15.5%, 25.5%.

[0036] In order to break through the limitations of traditional biological fermentation pathways and efficiently extract liquid phosphorus and potassium elements from poultry manure in a targeted manner, as Figure 1 shown, the present invention provides a method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent, and its exemplary steps include:

[0037] Step S1: Perform high - temperature activation treatment on poultry manure to convert organic phosphorus in the manure into soluble phosphate and obtain an activated material of high - calcium ash residue;

[0038] Step S2: Wash the activated material to remove soluble salts and dry it to obtain a pre - fabricated material;

[0039] Step S3: Add oxalic acid to the pre - fabricated material for a first - stage mixing reaction to form calcium oxalate precipitate, break the structure of calcium - phosphorus compounds and release soluble phosphate ions; then, in the first - stage reaction product, add either an organic acid or an organic chelating agent to inhibit the re - precipitation of phosphorus and metal ions during the reaction, perform a second - stage mixing reaction, and then separate the solid and liquid to extract the leaching solution.

[0040] Specifically, the poultry manure referred to in this example includes the manure of common poultry such as chickens, ducks, geese, quails, pigeons, etc. Most of the components in this poultry manure are similar, generally differing in the contents of phosphorus, potassium, calcium, etc. Therefore, those skilled in the art can, on the premise of understanding the inventive concept of the present invention, make adaptive adjustments to various ratios, values, etc. in the relevant processes under this example of the present invention for different types of poultry manure. For example, adjust the high-temperature activation temperature according to different poultry manures to meet the requirement of converting organic phosphorus into soluble phosphate, or adjust the water washing process to remove soluble salts, so as to eliminate the phosphorus reprecipitation effect caused by basic oxides, or adjust the selection and concentration of organic acids / organic chelating agents, adjust the solid-liquid ratio of acid leaching, reaction time, etc., so that phosphorus and potassium elements can remain in the leaching solution as much as possible to improve the recovery efficiency. Therefore, those skilled in the art should understand that other equivalent substitution / adjustment implementation schemes made without departing from the inventive concept of the present invention are all within the disclosure scope of the present invention.

[0041] To better illustrate the implementation process of the present invention, in this example, chicken manure is taken as an example for exemplary illustration. Specifically, in order to break through the limitations of the traditional biological fermentation path, the present invention proposes a synergistic scheme of high-temperature activation - two-stage mixed leaching reaction in the inventive concept, so as to achieve the decomposition of organic matter and the directional transformation of mineral phases through high-temperature activation, use water washing treatment to remove the residual soluble salts on the surface of the activated material, and at the same time cooperate with the organic mixed leaching agent to achieve the synchronous enrichment of phosphorus and potassium through step-by-step mixed reaction, thereby realizing the directional and efficient extraction of phosphorus and potassium elements in chicken manure under normal temperature and pressure by chemical wet method.

[0042] The example reaction conditions are as follows:

[0043]

[0044] The example leaching process is as follows:

[0045] 1) High-temperature activation: Screen the incinerated ash of chicken manure to an appropriate particle size to convert the organic phosphorus in the manure into soluble phosphate.

[0046] 2) Water washing treatment: Since the residual free CaO / MgO and other basic oxides on the surface of the activated material will form Ca(OH)2 / Mg(OH)2 colloids when encountering water, the chicken manure after high-temperature activation is washed with water (such as 3 to 5 times), and the soluble salts on the activated material can be removed through ion dissolution-diffusion, avoiding the reprecipitation of phosphorus (such as Ca3(PO4)2) due to too high local pH during subsequent acid leaching.

[0047] 3) Stepwise leaching:

[0048] One-stage leaching reaction: Add the activated material after water washing to the leaching reactor according to the liquid-solid ratio of (8 - 20) mL:1 g, add oxalic acid with a concentration of 3 - 8 mol / L, and react at a constant temperature under room temperature and normal pressure for 30 min. Among them, oxalic acid is used as the main leaching agent. Its function is that the dissociated oxalate ions can react with Ca in the chicken manure ash 2+ to form calcium oxalate precipitate, which can destroy the structure of calcium phosphate compounds and release soluble phosphate ions, and can also provide an acidic environment (such as pH 2.5 - 3.0) to promote the dissolution of potassium.

[0049] Two-stage leaching reaction: Add 0.5 - 3% organic acid (such as including: citric acid, salicylic acid, adipic acid, etc.) or organic chelating agent (such as including: EDTA-2Na, ammonium citrate, etc.) to the reactor after the one-stage reaction, and continue to react at a constant temperature under room temperature and normal pressure for 30 min. Among them, the organic acid or organic chelating agent, its function is to inhibit the re-precipitation of phosphorus and metal ions in the reaction and prevent metal ions from combining with phosphate ions to form insoluble substances.

[0050] 4) Solid-liquid separation: After the reaction, the mixed solution is subjected to solid-liquid separation (such as using membrane filtration or centrifugal separation; the filtrate collection rate > 95%), and finally a phosphorus and potassium leaching solution and mineral residues are obtained.

[0051] Experimental examples and comparative examples

[0052] Experimental example 1

[0053] As Figure 2 shown, select the screened chicken manure incineration ash, weigh 2 portions with a mass of 10 g, and label them as No. 1 - 2 respectively. The chemical composition of the chicken manure incineration ash is shown in Table 1.

[0054] Table 1 Chemical composition of chicken manure incineration ash (wt%)

[0055]

[0056] Wash the two portions of chicken manure incineration ash 3 - 5 times respectively, and then perform solid-liquid separation for subsequent leaching.

[0057] First, during the one-stage mixing reaction, add the washed chicken manure incineration ash to the leaching reactor according to the liquid-solid ratio of 20 mL:1 g, add oxalic acid with a mass concentration of 5%, control the reaction at room temperature, and stir and react at a constant temperature for 30 min.

[0058] Then, during the two-stage mixing reaction, add citric acid to the reactor after the oxalic acid reaction, so as to form stable complexes with Fe 3+ and Al 3+ to avoid their combination with phosphate ions to form insoluble iron / aluminum phosphates and maintain the dissolution of phosphate ions.

[0059] The corresponding citric acid concentrations for the two portions of chicken manure incineration ash are 2% and 3% respectively, and the reaction continues for 30 min at room temperature.

[0060] Solid-liquid separation: After the reaction, the mixed solution is subjected to solid-liquid separation to obtain a phosphorus and potassium leaching solution and mineral residues.

[0061] After the reaction, solid-liquid separation is carried out to obtain a leaching solution containing phosphorus and potassium and mineral residues. The concentrations of various components in the leaching solution are measured by AAS and ICP-OES, and the leaching rates of phosphorus and potassium elements are calculated. The results are shown in Table 2;

[0062] Table 2 Leaching rates of phosphorus and potassium elements in the leaching solution (%).

[0063] Number Phosphorus element Potassium element 1 55.33 89.09 2 33.54 84.73

[0064] It is found through experiments that when the citric acid concentration exceeds 2% (0.2 mol / L), it will trigger calcium complexation competition, resulting in a cliff-like drop in the phosphorus leaching rate (such as dropping to 33.54% at a concentration of 3%). The chicken manure incineration ash contains high calcium (CaO 54.56 mass%), and washing with water can remove the Ca(OH)2 colloid generated by free CaO (to avoid the re-precipitation of phosphorus caused by the local increase in pH during subsequent acid leaching).

[0065] In Example 1 of this experiment, through a stepwise organic acid synergistic leaching scheme, a staged feeding process of oxalic acid and citric acid is proposed, which overcomes the problem of phosphorus and potassium extraction from high-calcium chicken manure incineration ash. Its principle is that oxalic acid preferentially dissociates the calcium-phosphorus phase (Ca3(PO4)2 → CaC2O4↓), releasing phosphate ions; then citric acid complexes with Fe 3+ / Al 3+ , inhibits the precipitation of phosphorus, and realizes the environmentally friendly and efficient extraction of elements (phosphorus leaching rate 55.33%, potassium 89.09%). Compared with the traditional inorganic acid method, its advantages lie in low corrosiveness (pH 2.5 - 3.0) and the potential for resource utilization of residues (calcining calcium oxalate to produce CaO), solving the problems of equipment loss and secondary pollution, and providing a green path for the resource utilization of organic solid waste.

[0066] Comparative Example 1

[0067] The difference between this Comparative Example 1 and Example 1 of the experiment is that the mass concentrations of oxalic acid are selected as 3%, 4%, 6%, 8% respectively, and the mass concentration of citric acid is 2%. Other conditions and operations are the same as those in Example 1, and the leaching results of phosphorus and potassium elements are shown in Table 3.

[0068] Table 3 Leaching rates of phosphorus and potassium elements in the leaching solution (%).

[0069] Oxalic acid mass concentration / % Phosphorus element Potassium element 3 34.31 62.11 4 41.95 74.13 6 60.13 87.64 8 70.13 93.42

[0070] In Comparative Example 1, under the condition of fixing citric acid at 2%, by increasing the concentration of oxalic acid (from 3% to 8%), the phosphorus leaching rate was significantly increased (from 34.31% to 70.13%), verifying the dominant role of oxalic acid concentration in the dissociation of calcium-phosphorus phases. Compared with Experimental Example 1 (5% oxalic acid + 2% citric acid, phosphorus leaching rate of 55.33%), high-concentration oxalic acid (8%) can provide more C2O4 2- ions, fully precipitate Ca 2+ (forming CaC2O4), releasing phosphate ions; at the same time, maintaining the citric acid concentration at 2% (0.16 mol / L) avoids excessive calcium complexation competition, thus breaking through the phosphorus extraction bottleneck. The synchronous increase in potassium leaching rate (from 62.11% to 93.42%) is due to the increased oxalic acid concentration promoting the dissolution of K2O (K2C2O4 is easily soluble).

[0071] The advantage of Comparative Example 1 is that the phosphorus and potassium leaching efficiency is maximized (phosphorus 70.13% and potassium 93.42% at 8% oxalic acid), but it comes at the cost of cost and environmental protection: doubling the oxalic acid concentration (from 5% to 8%) increases the acid consumption per ton of treatment by 60%, the cost of neutralizing residual acid increases by 35%, and high-concentration oxalic acid exacerbates equipment corrosion. In contrast, Experimental Example 1 achieved balanced extraction of 55.33% phosphorus and 89.09% potassium with a moderate oxalic acid concentration (5%), taking into account both economy and environmental protection. In practical applications, if resource utilization efficiency is prioritized, the high-concentration scheme of the comparative example can be selected; if cost control and sustainability are required, Experimental Example 1 is more preferable.

[0072] Comparative Example 2

[0073] The difference between this Comparative Example 2 and Experimental Example 1 is that the liquid-solid ratio is set to 10, 15, 30, 50 mL:1 g, and other conditions and steps are the same as those in Experimental Example 1. The leaching results of phosphorus and potassium elements are shown in Table 4.

[0074] Table 4 Leaching rates of phosphorus and potassium elements in the leaching solution (%).

[0075] Liquid-solid ratio Phosphorus element Potassium element 10 / 1 29.93 63.91 15 / 1 37.88 75.16 30 / 1 61.51 91.70 50 / 1 70.14 94.19

[0076] The advantage of Comparative Example 2 is that it breaks through the mass transfer limitation at low liquid-solid ratios, but it comes at the cost of economy and environmental protection: when the liquid-solid ratio is 50:1, the leaching agent dosage is 2.5 times that of Experimental Example 1, the treatment cost increases by 45%, and the amount of waste liquid to be treated surges (the consumption of neutralizing agent +30%). Experimental Example 1 achieved phosphorus and potassium leaching rates of 55.33% / 89.09% at a liquid-solid ratio of 20:1, taking into account both resource efficiency and economy. In practical applications, it is recommended to adopt dynamic liquid-solid ratio regulation: use a liquid-solid ratio of (20~30):1 to maximize extraction or balance costs.

[0077] Comparative Example 3

[0078] The difference between Comparative Example 3 and Experimental Example 1 is as follows: The chicken manure incineration ash was not washed with water. The mass concentration of oxalic acid was selected to be 5%, and the mass concentration of citric acid was 2%. Other conditions and steps were the same as those in Experimental Example 1. The leaching rates of phosphorus and potassium elements were 33.49% and 70.51% respectively. The results show that by washing with water multiple times, the influence of part of calcium on the leaching of phosphorus element can be removed, and the leaching rates of phosphorus and potassium elements can be significantly increased.

[0079] Experimental Example 2

[0080] The basic steps of this Experimental Example 2 were the same as those in Experimental Example 1, with the differences being as follows:

[0081] During the secondary mixing reaction, salicylic acid or adipic acid with a mass concentration of 2% was added to the reaction kettle after the oxalic acid reaction, and the reaction continued at room temperature for 30 minutes.

[0082] After the reaction, solid-liquid separation was carried out to obtain the leaching solution containing phosphorus and potassium and mineral residues. The concentrations of each component in the leaching solution were measured using AAS and ICP-OES, and the leaching rates of phosphorus and potassium elements were calculated. The results are shown in Table 5;

[0083] Table 5 Leaching rates of phosphorus and potassium elements in the leaching solution (%).

[0084] Organic acid type Phosphorus element Potassium element Salicylic acid 57.78 90.09 Adipic acid 69.54 95.03

[0085] In this Experimental Example 2, by replacing citric acid with salicylic acid and adipic acid, the leaching efficiency of phosphorus and potassium was significantly optimized. Compared with Experimental Example 1 (2% citric acid, phosphorus 55.33%, potassium 89.09%), the phosphorus leaching rate of adipic acid increased to 69.54% (an increase of 25.7%), and the potassium leaching rate reached 95.03%. The core mechanism lies in that the dicarboxylic acid structure (-COOH) of adipic acid provides stronger metal complexing ability, preferentially complexing residual Ca 2+ , inhibiting the reprecipitation of phosphorus (such as CaHPO4); synergistically dissociating calcium and phosphorus with oxalic acid: adipic acid maintains the dissolved state of phosphate ions in the range of pH 2.5 - 3.5, avoiding the competitive adsorption of Fe 3+ / Al 3+ , while salicylic acid (containing phenolic hydroxyl group) has a complexing selectivity bias towards Fe 3+ , resulting in a relatively small increase in the phosphorus leaching rate (57.78%).

[0086] The advantage of this Experimental Example 2 is high efficiency and low consumption: at the same concentration (2%), the phosphorus leaching rate of adipic acid is 14.2% higher than that of the citric acid system, and there is no need to increase the acid concentration. This scheme is particularly suitable for high-calcium ash (CaO > 50%), and can reduce the consumption of neutralizing agent by 30%.

[0087] Comparative Example 4

[0088] The difference between Comparative Example 4 and Experimental Example 2 is that the organic acid is replaced with an organic chelating agent, such as EDTA-2Na and ammonium citrate, with mass concentrations of 0.75% and 1.25% respectively. The mechanism is that the EDTA-2Na chelating agent efficiently complexes metal ions such as Ca 2+ and Fe 3+ through multi-dentate coordination, which can further inhibit phosphorus reprecipitation and is applicable to high-calcium ash systems. Ammonium citrate can complex with carboxylic acids through the ion exchange of ammonium ions to synergistically release phosphate ions. Other conditions and steps are the same as those in Experimental Example 1. The leaching rates of phosphorus and potassium elements are shown in Table 6.

[0089] Table 6 Leaching rates of phosphorus and potassium elements in the leachate (%).

[0090] Chelating agent type Phosphorus element Potassium element EDTA-2Na 68.22 93.46 Ammonium citrate 59.36 83.61

[0091] This comparative example uses the organic chelating agents EDTA-2Na / ammonium citrate to replace the organic acid. By coordination complexation (such as EDTA complexing Ca 2+ / Fe 3+ ), the re-binding of metal ions and phosphate ions is blocked. The phosphorus leaching rate reaches 68.22% (EDTA) and 59.36% (ammonium citrate). Its core advantage lies in its excellent metal control ability and low chelating agent dosage (synchronous complexation of multiple metals can be achieved at a concentration of 0.75%), which is applicable to high-calcium ash.

[0092] Comparative Example 5

[0093] The difference between Comparative Example 5 and Comparative Example 4 is that the mass concentrations of the organic chelating agent ammonium citrate are 0.5%, 1.25%, and 1.5%. Other conditions and steps are the same. The leaching rates of phosphorus and potassium elements are shown in Table 7.

[0094] Table 7 Leaching rates of phosphorus and potassium elements in the leachate (%).

[0095] Ammonium citrate concentration / % Phosphorus element Potassium element 0.5 31.86 55.19 1 48.91 78.54 1.5 62.36 89.61

[0096] This comparative example significantly improves the leaching rates of phosphorus and potassium (phosphorus: 31.86% → 62.36%; potassium: 55.19% → 89.61%) by increasing the concentration of ammonium citrate (0.5% → 1.5%), verifying the regulatory effect of the concentration gradient on the chelating efficiency. Comparing the phosphorus leaching rate of 59.36% of ammonium citrate at 0.75% in Comparative Example 4, when the concentration increases to 1.5%, the phosphorus extraction efficiency increases by 4.9%. It shows that 1.5% is the effective threshold of ammonium citrate, and its NH4 + ion exchange and carboxylic acid complexation synergistically release phosphate ions. However, even when the concentration doubles (1.5% compared to 0.75%), its phosphorus leaching rate (62.36%) is still lower than 68.22% of EDTA-2Na in Comparative Example 4, attributed to the stronger complexing ability of EDTA.

[0097] The advantage of Comparative Example 5 lies in low cost and ecological friendliness: the unit price of ammonium citrate is only 1 / 5 of that of EDTA-2Na, and the treatment cost per ton at a concentration of 1.5% is 45% lower than that of Comparative Example 4 (EDTA). Moreover, ammonium citrate is biodegradable and has a lower environmental risk. In practical applications, if the heavy metal content in the ash residue is low, the 1.25% ammonium citrate solution can be preferably selected to balance efficiency (phosphorus 59.36%) and sustainability; if extreme heavy metal control and efficiency are required, the high cost of EDTA has to be borne.

[0098] It can be seen from the above experimental examples and comparative examples that the method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent of the present invention proposes a synergistic process of high-temperature activation and two-stage acid leaching reaction in terms of inventive concept. This not only breaks through the limitations and drawbacks of the traditional biological fermentation path, but also solves problems such as the long treatment cycle (15 - 30 days), low extraction rate of phosphorus and potassium elements, incomplete degradation of antibiotics, serious secondary pollution, strong corrosion of inorganic acid leaching equipment, and high waste acid treatment cost in the traditional composting method. And this method inactivates pathogenic microorganisms (inactivation rate > 99%), degrades antibiotics (half-life < 15 seconds), and removes heavy metals (effective state reduced by 60%) in the high-temperature activation stage. In the organic acid leaching stage, through the complexation of organic acids with metal ions (such as the formation of precipitation between oxalic acid and Ca 2+ ), it inhibits the re-precipitation of phosphorus and can significantly increase the phosphorus leaching rate to over 60% and the potassium leaching rate to 70% - 95%, with a substantial improvement in extraction efficiency compared to the traditional composting method.

[0099] In addition, although it is impossible to list all cases, based on the concept of the above examples, those skilled in the art can also adapt different processes to different raw materials to resourceify phosphorus and potassium in organic solid waste, thereby achieving a solution with both industrial feasibility and environmental benefits.

[0100] On the other hand, corresponding to the process method of the above examples, the present invention also provides a liquid fertilizer, which includes: the leaching solution obtained by the method described in any one of the above examples.

[0101] On the other hand, corresponding to the process method of the above examples, as Figure 3 shown, the present invention also provides a method for extracting phosphorus and potassium elements from poultry manure to produce fertilizer based on an organic mixed leaching agent, and its steps include:

[0102] Conduct composition regulation on the leaching solution obtained by the method described in any one of the above, and after adjusting the pH value and concentrating it until the macronutrients required for the product meet the standards, a finished fertilizer is obtained.

[0103] The specific key preparation steps are as follows:

[0104] Step Operating conditions and technical requirements Principle High-temperature activation Chicken manure is incinerated to ash Realize the decomposition of organic matter and the directional transformation of mineral phases Washing treatment The activated material after high-temperature activation treatment is acid-leached after being washed many times <![CDATA[Water washing removes soluble salts through ionic dissolution-diffusion; free basic oxides such as residual CaO / MgO on the surface of the activated material react with water to form Ca(OH)2 / Mg(OH)2 colloids, and water washing can avoid the re-precipitation of phosphorus (such as Ca3(PO4)2) due to too high local pH during subsequent acid leaching. <!-- 8 -->]]> Organic mixed leaching agent Oxalic acid is the main leaching agent, organic acids such as citric acid or chelating agents such as EDTA-2Na <![CDATA[Oxalic acid is used as the main leaching agent. The dissociated oxalate ions react with Ca in chicken manure ash 2+ to form calcium oxalate precipitate, which destroys the structure of calcium phosphate compounds and releases soluble phosphate ions. Moreover, the acidic environment (pH 2.5 - 3.0) provided by it promotes the dissolution of potassium. Citric acid forms stable complexes with Fe 3+ , Al 3+ through carboxyl groups, preventing them from combining with phosphate ions to form insoluble iron / aluminum phosphates and maintaining the dissolution of phosphate ions. Chelating agents such as EDTA-2Na efficiently complex metal ions such as Ca 2+ , Fe 3+ to further inhibit the reprecipitation of phosphorus and are suitable for high-calcium ash systems. Ammonium citrate, on the other hand, synergistically releases phosphate ions through the ion exchange of ammonium ions and carboxylate complexation]]> Solid-liquid separation Filtration, membrane separation or centrifugation; The filtrate collection rate > 95% Efficiently separate soluble nutrient elements Composition regulation Add urea / ammonium nitrate to adjust the N content; Potassium dihydrogen phosphate supplements P / K Meet the NY 1107-2020 liquid fertilizer standard Adjust pH <![CDATA[Add ammonia water (NH3·H2O) / potassium hydroxide to supplement ammonium nitrogen / potassium element]]> Neutralize excessive H+, meet the NY1107-2020 liquid fertilizer standard

[0105] Among them Figure 3 As shown, the above key steps involve the leachate process, which will not be described here, and can be carried out with reference to the above examples. The example of the composition control step includes: according to product needs, one or more of urea, ammonium nitrate, and potassium dihydrogen phosphate can be selected as N / P / K supplementary elements and added to the leachate. The example of the pH value adjustment step includes: selecting any one of ammonia water and potassium hydroxide as a regulator to adjust the pH value.

[0106] For example, in this example, urea (1-3wt%) and dipotassium hydrogen phosphate (0.5-2wt%) are preferably added to the leachate, the pH is adjusted to 3.0±0.5 with aqueous ammonia, and the liquid fertilizer product is obtained by concentrating the macroelements required for the product.

[0107] On the other hand, corresponding to the above-mentioned example of a method for extracting phosphorus and potassium elements from poultry manure to make fertilizer based on an organic mixed leachant, the present invention also provides a soil conditioner, which includes: the dry residue obtained by solid-liquid separation in any of the above examples of a method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leachant.

[0108] In the above example, the residue separated from the solid and liquid can be dried at high temperature (such as drying at 105°C) to make an organic soil conditioner. It can be seen that the method of extracting phosphorus and potassium from poultry manure based on organic mixed leaching agents in the above example can not only match the liquid fertilizer preparation process in terms of process, but also the residue can be converted into a soil conditioner, realizing the resource utilization of all components of chicken manure and zero waste emission design, which meets the carbon neutrality goal. In addition, during the high-temperature activation process, pathogen inactivation, antibiotic degradation and heavy metal passivation can be completed simultaneously, thereby reducing environmental risks. In this way, a fully closed-loop production model from phosphorus and potassium extraction-liquid fertilizer preparation-residue resource utilization can be constructed, which effectively solves the problems of low efficiency and high energy consumption of existing technologies.

[0109] In summary, the method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent, and its fertilizer making method, liquid fertilizer, and soil conditioner provided by the present invention cleverly propose a high-temperature activation-two-stage mixed leaching reaction synergistic scheme, which breaks through the limitations and disadvantages of the traditional biological fermentation path, and the extraction efficiency is greatly improved compared with the traditional composting method, and the processing cycle is compressed from 15-30 days to several hours. At the same time, the residue after the reaction can also be used as a soil conditioner, thereby opening up the closed-loop chain of "element extraction-pollution control-residue regeneration" of organic solid waste, and overcoming the industry problems such as incomplete degradation of antibiotics in traditional processes, low conversion rate of traditional liquid fertilizers, and serious secondary pollution. At the same time, compared with the inorganic acid leaching scheme, it also has the advantages of low corrosiveness and low cost of waste acid treatment. More importantly, the organic acid system is biodegradable, and the leachate can be used in organic agriculture without complex neutralization treatment, which meets the needs of green agriculture and pollution-free agricultural product production, thereby providing a revolutionary solution for the resource utilization of livestock and poultry manure with high efficiency, low cost and low emission characteristics.

[0110] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is only limited by the claims and their full scope and equivalents. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

[0111] In addition, all or part of the steps in the above-mentioned embodiment method can be completed by instructing the relevant hardware through a program, and the program is stored in a storage medium, including a number of instructions to enable a single-chip microcomputer, a chip or a processor to execute all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, RandomAccess Memory), disk or optical disk and other media that can store program codes.

[0112] In addition, various implementation modes of the embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the embodiments of the present invention, they should also be regarded as the contents disclosed by the embodiments of the present invention.

Claims

1. A method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent, the steps of which include: Step S1: Perform high-temperature activation treatment on poultry manure to convert organic phosphorus in the manure into soluble phosphate and obtain an activated material of high-calcium ash residue; Step S2: Wash the activated material to remove soluble salts and dry it into a prefabricated material; Step S3: Add oxalic acid to the prefabricated material for a first-stage mixing reaction, and then add any one of organic acids or organic chelating agents for a second-stage mixing reaction, followed by solid-liquid separation to extract the leaching solution.

2. The method according to claim 1, wherein the organic acid is any one of citric acid, salicylic acid, and adipic acid; the organic chelating agent is any one of EDTA-2Na and ammonium citrate.

3. The method according to claim 1, wherein the mass concentration of the oxalic acid is 3-8%.

4. The method according to claim 1, wherein the mass concentration of the organic acid is 2-3% and the mass concentration of the chelating agent is 0.5-1.5%.

5. The method according to claim 1, wherein in step S3, the solid-liquid ratio of the oxalic acid to the prefabricated material is 10-50 mL:1 g.

6. The method according to claim 1, wherein the first-stage and second-stage mixing reactions are carried out under constant temperature at room temperature and normal pressure.

7. A liquid fertilizer, comprising: The leaching solution obtained by the method according to any one of claims 1 to 6.

8. A method for extracting phosphorus and potassium elements from poultry manure based on an organic mixed leaching agent to produce fertilizer, the steps of which include: Adjust the composition of the leaching solution obtained by the method according to any one of claims 1 to 6, and perform concentration treatment after adjusting the pH value.

9. The method according to claim 8, wherein the composition adjustment step includes: Select one or more of urea, ammonium nitrate, and dipotassium hydrogen phosphate as supplementary elements and add them to the leaching solution.

10. The method according to claim 8, wherein the pH value adjustment step includes: Select any one of ammonia water and potassium hydroxide as a regulator to adjust the pH value to above 3.

0.

11. A soil conditioner, comprising: The dry residue obtained by solid-liquid separation in the method according to any one of claims 1 to 6.

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