Method for preparing three independent organic liquid fertilizers of nitrogen, phosphorus and potassium by using liquid organic fertilizer

Abstract

The invention belongs to the technical field of organic fertilizer processing, and discloses a method for preparing three independent organic liquid fertilizers of nitrogen, phosphorus and potassium by using a liquid organic fertilizer. Targeted chelation and gradient membrane separation technologies are adopted, independent separation of three nutrients of nitrogen, phosphorus and potassium is achieved, the product can be precisely applied, the nutrient utilization rate is increased, the problem that traditional liquid organic fertilizers are mixed in nutrient is solved, and nitrogen, phosphorus and potassium organic liquid fertilizers are respectively and precisely provided according to the requirements of crops. The method meets the requirements of green agriculture, the recovery rate of the chelating agent is larger than or equal to 90%, the desorption agent is environmentally friendly and free of secondary pollution, meanwhile, the product retains organic active ingredients, and fertilizer efficiency and soil improvement are both considered.

Description

Technical Field

[0001] This invention belongs to the field of organic fertilizer processing technology, and specifically relates to a method for preparing nitrogen, phosphorus, and potassium liquid organic fertilizers using liquid organic fertilizer. Background Technology

[0002] Liquid organic fertilizers are increasingly widely used in agricultural production due to their wide range of raw material sources (livestock and poultry manure, straw, kitchen waste, etc.), short fermentation cycle, rapid fertilizer effect, and ability to improve soil structure. However, existing liquid organic fertilizers generally suffer from the problem of mixed coexistence of major nutrients such as nitrogen, phosphorus, and potassium. This makes it impossible to apply them precisely according to the nutrient requirements of different crops (e.g., leafy vegetables require more nitrogen, while fruit crops require more phosphorus and potassium) and different growth stages (seedlings need nitrogen, flowering stages need phosphorus, and fruit expansion stages need potassium). This results in the waste of some nutrients and the deficiency of others, with nutrient utilization rates typically below 30%. It may also lead to environmental problems such as soil salinization and water eutrophication.

[0003] Currently, the main methods for nutrient separation in liquid organic fertilizers include precipitation and extraction. However, precipitation methods suffer from poor specificity and low purity, while extraction methods are prone to introducing organic solvent contamination. Furthermore, neither method can achieve efficient and individual separation of nitrogen, phosphorus, and potassium. Therefore, developing a green and efficient organic liquid fertilizer processing method capable of separately separating nitrogen, phosphorus, and potassium is of great significance for improving the utilization value of liquid organic fertilizers and promoting green and sustainable agricultural development. Summary of the Invention

[0004] In view of this, the present invention provides a method for preparing nitrogen, phosphorus and potassium separate organic liquid fertilizers using liquid organic fertilizers, which can achieve precise separation and efficient utilization of nutrients.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing nitrogen, phosphorus, and potassium liquid organic fertilizers using liquid organic fertilizer includes the following steps: (1) Pretreatment: Take liquid organic fertilizer raw material, remove impurities by sedimentation and filtration, and then concentrate it at low temperature and vacuum to 10~25°Bé to obtain pretreated liquid; (2) Targeted chelation: Nitrogen chelating agent, phosphorus chelating agent and potassium chelating agent are added to the pretreatment solution in sequence, and the reaction is carried out stepwise at different temperatures and stirring rates to form nitrogen-chelating agent complex, phosphorus-chelating agent complex and potassium-chelating agent complex respectively. (3) Gradient separation: The chelated liquid is filtered through three ceramic membranes with different pore sizes in sequence to retain the nitrogen-chelating agent complex, phosphorus-chelating agent complex and potassium-chelating agent complex respectively, so as to achieve the individual separation of the three. (4) Desorption and purification: The three retained complexes are added to the desorption agent to desorb and release nitrogen, phosphorus and potassium elements. The chelating agent is recovered by filtration to obtain crude nitrogen fertilizer solution, crude phosphorus fertilizer solution and crude potassium fertilizer solution. They are then purified by ion exchange resin to obtain refined nitrogen organic solution, refined phosphorus organic solution and refined potassium organic solution. (5) Stabilization treatment: Stabilizers were added to the three types of refined organic liquids respectively, and after constant temperature aging, organic liquid nitrogen fertilizer, organic liquid phosphorus fertilizer and organic liquid potassium fertilizer were obtained separately.

[0006] Preferably, in step (1), the precipitation and impurity removal is selected from at least one of natural sedimentation, plate and frame filtration, and centrifugal sedimentation; the natural sedimentation time is 4~24h, the pressure of plate and frame filtration is 0.2~0.8MPa, and the centrifugal sedimentation speed is 3000~8000r / min; The temperature for the low-temperature vacuum concentration is 35~60℃, and the vacuum degree is -0.06~-0.095MPa.

[0007] Preferably, in step (2), the nitrogen chelating agent is selected from at least one of modified chitosan and polyaspartic acid, the amount added is 1-8% of the mass of the pretreatment liquid, the reaction temperature is 25-45℃, the stirring rate is 100-300r / min, and the reaction time is 30-120min.

[0008] Preferably, in step (2), the phosphorus chelating agent is selected from at least one of hydroxypropyl-β-cyclodextrin and phytic acid, and the amount added is 2 to 10% of the mass of the pretreatment liquid. The reaction temperature is 40 to 60°C, the stirring rate is 150 to 350 r / min, and the reaction time is 60 to 150 min.

[0009] Preferably, in step (2), the potassium chelating agent is selected from at least one of sodium alginate and sodium carboxymethyl cellulose, the amount added is 1.5~7% of the mass of the pretreatment liquid, the reaction temperature is 30~50℃, the stirring rate is 120~280r / min, and the reaction time is 40~120min.

[0010] Preferably, in step (3), the pore sizes of the three-stage ceramic membranes are 30~100nm, 10~50nm, and 2~20nm, respectively, the filtration pressure is 0.1~0.6MPa, and the transmembrane flow rate is 1~5m / s.

[0011] Preferably, in step (4), the eluent is selected from at least one of citric acid solution, aminosulfonic acid solution, and malic acid solution, the mass fraction of the eluent is 3~12%, the amount added is 0.5~5 times the mass of the complex, the eluent temperature is 35~70℃, and the eluent time is 20~90min.

[0012] Preferably, in step (4), the crude nitrogen fertilizer solution uses a strongly acidic cation exchange resin column, the crude phosphate fertilizer solution uses a weakly basic anion exchange resin column, and the crude potassium fertilizer solution uses a strongly basic anion exchange resin column.

[0013] Preferably, in step (5), the stabilizer is at least one of fulvic acid and humic acid, and the amount added is 0.1~1.0% of the mass of the refined organic liquid; The constant temperature curing temperature is 20~35℃, and the curing time is 12~72h.

[0014] This invention also provides three separate organic liquid fertilizers of nitrogen, phosphorus, and potassium prepared by the above method. The nitrogen content of the organic liquid nitrogen fertilizer is ≥60g / L, the phosphorus content of the organic liquid phosphorus fertilizer is ≥50g / L, and the potassium content of the organic liquid potassium fertilizer is ≥60g / L. All three separate organic liquid fertilizers retain the amino acids and humic acid organic active ingredients in the liquid organic fertilizer raw materials.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. This invention uses targeted chelation and gradient membrane separation technology to achieve the separate separation of nitrogen, phosphorus and potassium nutrients. The product can be precisely applied, improving nutrient utilization and solving the problem of nutrient mixing in traditional liquid organic fertilizers. It provides nitrogen, phosphorus and potassium organic liquid fertilizers precisely according to the needs of crops.

[0016] 2. This invention meets the requirements of green agriculture. The recovery rate of the chelating agent is ≥90%, the desorbent is green and environmentally friendly, and there is no secondary pollution. At the same time, the product retains organic active ingredients, taking into account both fertilizer efficiency and soil improvement.

[0017] 3. The process is simple to operate, the parameters are easy to control, the investment cost is low, it is suitable for large-scale production, and the application prospects are broad. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] A method for preparing nitrogen, phosphorus, and potassium liquid organic fertilizers using liquid organic fertilizer includes the following steps: (1) Pretreatment Take liquid organic fertilizer raw materials (such as pig manure fermentation liquid, chicken manure fermentation liquid, straw compost liquid), and allow them to settle naturally for 8 hours to remove large suspended solids; then filter them through a plate and frame filter press at a pressure of 0.4 MPa to obtain a clear filtrate; send the filtrate into a low-temperature vacuum concentrator and concentrate it to a Baume degree of 10~25°Bé at a temperature of 50℃ and a vacuum degree of -0.08 MPa to obtain a pretreated liquid, which increases the nutrient concentration to facilitate subsequent chelation reactions; (2) Targeted chelation Add 3% (by weight) of nitrogen chelating agent to the pretreatment solution, control the temperature at 35℃ and the stirring rate at 180 r / min, and react for 75 min to form a nitrogen-chelating agent complex. The temperature was raised to 50°C, and 4% (by weight) of phosphorus chelating agent was added to the pretreatment solution. The stirring rate was 200 r / min, and the reaction was carried out for 100 min to form a phosphorus-chelating agent complex. Cool down to 40℃, add 3.5% potassium chelating agent by mass of the pretreatment solution, stir at 160 r / min, react for 85 min to form potassium-chelating agent complex; (3) Gradient separation The chelated feed solution is pumped into a ceramic membrane separation system and passes through three stages of ceramic membranes sequentially. The first-stage ceramic membrane has a pore size of 30~100nm, a filtration pressure of 0.3MPa, a transmembrane flow rate of 2.5m / s, and retains the nitrogen-chelating agent complex. The permeate then enters the second-stage separation. The second-stage ceramic membrane has a pore size of 10~50nm, a filtration pressure of 0.35MPa, a transmembrane flow rate of 2m / s, and retains the phosphorus-chelating agent complex. The permeate then enters the third-stage separation. The third-stage ceramic membrane has a pore size of 2~20nm, a filtration pressure of 0.4MPa, a transmembrane flow rate of 1.8m / s, and retains potassium-chelating agent complex. (4) Analysis and purification The three complexes were separately fed into an analytical vessel, and an analytical agent (a mixture of 6% citric acid solution and 4% aminosulfonic acid solution at a volume ratio of 1:1) was added twice the mass of the complexes. The vessel was heated to 50°C and stirred for 50 minutes to release nitrogen, phosphorus, and potassium elements. The chelating agent was then recovered by filtration (recovery rate ≥90%) to obtain crude nitrogen fertilizer solution, crude phosphorus fertilizer solution, and crude potassium fertilizer solution. The crude nitrogen fertilizer solution is passed through a strongly acidic cation exchange resin column, the crude phosphate fertilizer solution is passed through a weakly basic anion exchange resin column, and the crude potassium fertilizer solution is passed through a strongly basic anion exchange resin column to remove impurity ions such as calcium, magnesium, and chloride, thereby obtaining refined nitrogen organic liquid, refined phosphate organic liquid, and refined potassium organic liquid. (5) Stabilization treatment Fulvic acid with a mass fraction of 0.3% was added to three different refined organic liquids, and the mixtures were aged at a constant temperature of 28℃ for 36 hours to obtain separate organic liquid nitrogen fertilizer, organic liquid phosphorus fertilizer, and organic liquid potassium fertilizer.

[0020] According to the above method, Examples 1 to 3 were carried out, and the specific parameters are shown in Table 1.

[0021] Table 1

[0022] The products were tested, and the results are shown in Table 2. It can be seen that this invention achieves the separate separation of nitrogen, phosphorus, and potassium nutrients, allowing for precise application of the products and improved nutrient utilization. Furthermore, all three individual organic liquid fertilizers retain the amino acids, humic acid, and other organic active ingredients found in the liquid organic fertilizer raw materials, with an organic active ingredient content ≥15g / L.

[0023] Table 2

[0024] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer, characterized in that, Includes the following steps: (1) Pretreatment: Take liquid organic fertilizer raw material, remove impurities by sedimentation and filtration, and then concentrate it at low temperature and vacuum to 10~25°Bé to obtain pretreated liquid; (2) Targeted chelation: Nitrogen chelating agent, phosphorus chelating agent and potassium chelating agent are added to the pretreatment solution in sequence, and the reaction is carried out stepwise at different temperatures and stirring rates to form nitrogen-chelating agent complex, phosphorus-chelating agent complex and potassium-chelating agent complex respectively. (3) Gradient separation: The chelated liquid is filtered through three ceramic membranes with different pore sizes in sequence to retain the nitrogen-chelating agent complex, phosphorus-chelating agent complex and potassium-chelating agent complex respectively, so as to achieve the individual separation of the three. (4) Desorption and purification: The three retained complexes are added to the desorption agent to desorb and release nitrogen, phosphorus and potassium elements. The chelating agent is recovered by filtration to obtain crude nitrogen fertilizer solution, crude phosphorus fertilizer solution and crude potassium fertilizer solution. They are then purified by ion exchange resin to obtain refined nitrogen organic solution, refined phosphorus organic solution and refined potassium organic solution. (5) Stabilization treatment: Stabilizers were added to the three types of refined organic liquids respectively, and after constant temperature aging, organic liquid nitrogen fertilizer, organic liquid phosphorus fertilizer and organic liquid potassium fertilizer were obtained separately.

2. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (1), the precipitation and impurity removal is selected from at least one of natural sedimentation, plate and frame filtration, and centrifugal sedimentation; the natural sedimentation time is 4~24h, the pressure of plate and frame filtration is 0.2~0.8MPa, and the centrifugal sedimentation speed is 3000~8000r / min; The temperature for the low-temperature vacuum concentration is 35~60℃, and the vacuum degree is -0.06~-0.095MPa.

3. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (2), the nitrogen chelating agent is selected from at least one of modified chitosan and polyaspartic acid, and the amount added is 1-8% of the mass of the pretreatment liquid. The reaction temperature is 25-45℃, the stirring rate is 100-300r / min, and the reaction time is 30-120min.

4. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (2), the phosphorus chelating agent is selected from at least one of hydroxypropyl-β-cyclodextrin and phytic acid, and the amount added is 2 to 10% of the mass of the pretreatment solution. The reaction temperature is 40 to 60°C, the stirring rate is 150 to 350 r / min, and the reaction time is 60 to 150 min.

5. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (2), the potassium chelating agent is selected from at least one of sodium alginate and sodium carboxymethyl cellulose, and the amount added is 1.5~7% of the mass of the pretreatment solution. The reaction temperature is 30~50℃, the stirring rate is 120~280r / min, and the reaction time is 40~120min.

6. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (3), the pore sizes of the three-stage ceramic membranes are 30~100nm, 10~50nm, and 2~20nm, respectively, the filtration pressure is 0.1~0.6MPa, and the transmembrane flow rate is 1~5m / s.

7. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (4), the eluent is selected from at least one of citric acid solution, aminosulfonic acid solution, and malic acid solution. The mass fraction of the eluent is 3-12%, the amount added is 0.5-5 times the mass of the complex, the eluent temperature is 35-70℃, and the eluent time is 20-90 min.

8. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (4), the crude nitrogen fertilizer solution uses a strongly acidic cation exchange resin column, the crude phosphate fertilizer solution uses a weakly basic anion exchange resin column, and the crude potassium fertilizer solution uses a strongly basic anion exchange resin column.

9. The method for preparing nitrogen, phosphorus, and potassium separate organic liquid fertilizers using liquid organic fertilizer according to claim 1, characterized in that, In step (5), the stabilizer is at least one of fulvic acid and humic acid, and the amount added is 0.1~1.0% of the mass of the refined organic liquid; The constant temperature curing temperature is 20~35℃, and the curing time is 12~72h.

10. The nitrogen, phosphorus, and potassium three-part organic liquid fertilizer prepared by the method according to any one of claims 1-9, characterized in that, Organic liquid nitrogen fertilizer has a nitrogen content ≥60g / L, organic liquid phosphate fertilizer has a phosphorus content ≥50g / L, and organic liquid potassium fertilizer has a potassium content ≥60g / L.

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