Process for converting animal manure into liquid organic fertilizer

Abstract

The application discloses a kind of animal manure conversion liquid organic fertilizer process, belong to organic fertilizer processing technical field, comprising the following steps: S1, fresh chicken manure is mixed with pH 5.0~6.0 citric acid-sodium phosphate buffer solution according to mass ratio 1:1.5~2.5, beating pulp 15~30 minutes, obtain pulping liquid;S2, to pulping liquid, add waste molasses to adjust carbon-nitrogen ratio to 20~25:1, inoculate anaerobic fermentation inoculant, and add 1.0~2.0% of the mass of pulping liquid urease-urease co-immobilized multi-amino attapulgite, anaerobic fermentation 48~72 hours at 30~37 DEG C;S3, after anaerobic fermentation, inoculate aerobic fermentation inoculant, and add 0.5~2.0% of the mass of pulping liquid carboxymethyl-beta-glucan grafting polyphosphate copolymer, aerobic fermentation 24~36 hours at 28~33 DEG C, dissolved oxygen 1.5~2.5 mg / L;S4, after aerobic fermentation, seal aging 24~36 hours at 25~30 DEG C, pass 80~120 mesh screen, obtain chicken manure source liquid organic fertilizer.The application can improve the content of water-soluble phosphorus in organic fertilizer.

Description

Technical Field

[0001] This invention belongs to the field of organic fertilizer processing technology, and relates to a process for converting animal manure into liquid organic fertilizer. Background Technology

[0002] Chicken manure is the most significant solid waste generated in large-scale egg-laying hen farming. Fermenting it into liquid organic fertilizer is a crucial way to utilize its resources. However, the large amounts of limestone powder (mainly calcium carbonate) added to egg-laying hen feed to meet egg production requirements result in high endogenous calcium content in the chicken manure. During fermentation, due to microbial metabolism, the pH of the fermentation liquid fluctuates greatly, causing some calcium carbonate to dissolve and release highly reactive free calcium ions. These calcium ions undergo an irreversible precipitation reaction with water-soluble phosphate ions in the liquid phase, forming stable calcium phosphate salts that are difficult for plants to absorb and utilize. Ultimately, this leads to a significant decrease in the available phosphorus (water-soluble phosphorus) content in the liquid organic fertilizer product, resulting in water-soluble phosphorus degradation. Furthermore, nitrogen loss and foul odor also occur during chicken manure fermentation. Summary of the Invention

[0003] The purpose of this invention is to provide a process for converting animal manure into liquid organic fertilizer, which solves the problems of water-soluble phosphorus degradation, nitrogen loss and odor that occur during the fermentation process of chicken manure to prepare liquid organic fertilizer.

[0004] The technical solution adopted in this invention is as follows: A process for converting animal manure into liquid organic fertilizer includes the following steps: S1. Mix fresh chicken manure with citrate-disodium hydrogen phosphate buffer solution with pH 5.0~6.0 at a mass ratio of 1:1.5~2.5, and beat for 15~30 minutes to obtain a pulped solution; S2. Add waste molasses to the slurry to adjust the carbon-nitrogen ratio to 20-25:1, inoculate with anaerobic fermentation agent, and add 1.0-2.0% of urate oxidase-urease co-immobilized polyaminoattapulgite by mass of slurry. Perform anaerobic fermentation at 30-37℃ for 48-72 hours. S3. After anaerobic fermentation, inoculate with aerobic fermentation agent and add 0.5-2.0% (by weight of slurry) of carboxymethyl-β-glucan-grafted polyphosphate copolymer. Perform aerobic fermentation for 24-36 hours at 28-33℃ and dissolved oxygen of 1.5-2.5 mg / L. S4. After aerobic fermentation, the mixture is sealed and aged at 25-30℃ for 24-36 hours, and then passed through an 80-120 mesh sieve to obtain chicken manure-based liquid organic fertilizer.

[0005] Further, the urate oxidase-urease co-immobilized polyaminoattapulgite was prepared by the following method: attapulgite was added to an ethanol solution containing 3-aminopropyltriethoxysilane and refluxed at 70-80°C for 4-8 hours to obtain aminated attapulgite; the aminated attapulgite was reacted with polyethyleneimine with a molecular weight of 600-1800 Da under glutaraldehyde crosslinking to obtain polyaminoattapulgite; the polyaminoattapulgite was added to a glutaraldehyde solution and stirred for activation; after activation, it was filtered and washed with water until no free glutaraldehyde was found to obtain an activated carrier; the activated carrier was dispersed in a pH 6.8 buffer solution, urate oxidase and urease were added, and the reaction was carried out at 4-10°C for 12-18 hours; the mixture was centrifuged, washed, and freeze-dried to obtain urate oxidase-urease co-immobilized polyaminoattapulgite.

[0006] Furthermore, the amount of polyethyleneimine added is 9 to 11% of the mass of the aminated attapulgite.

[0007] Furthermore, the carboxymethyl-β-glucan-grafted polyphosphate copolymer is prepared by the following method: a. β-glucan was extracted from brewer's waste yeast and then subjected to carboxymethylation reaction with monochloroacetic acid in isopropanol aqueous solution to obtain carboxymethyl-β-glucan; b. Carboxymethyl-β-glucan is subjected to a dry thermal esterification grafting reaction with sodium tripolyphosphate and phosphoric acid at 120~140℃ for 2~4 hours to obtain a carboxymethyl-β-glucan grafted polyphosphate copolymer.

[0008] Further, in step a, the mass ratio of β-glucan to monochloroacetic acid is 1:0.5~1.2, the reaction temperature is 50~60℃, and the reaction time is 3~5 hours; in step b, the mass ratio of carboxymethyl-β-glucan, sodium tripolyphosphate, and phosphoric acid is 1:0.3~0.8:0.05~0.15.

[0009] Furthermore, in step S2, the anaerobic fermentation agent is a compound bacterial solution of Candida utilis and Enterococcus faecalis, with a live cell ratio of Candida utilis to Enterococcus faecalis of 1:0.8~1.2.

[0010] Furthermore, the aerobic fermentation agent mentioned in step S3 is a compound bacterial solution of Bacillus subtilis and Streptomyces flavus, with a live bacteria ratio of Bacillus subtilis to Streptomyces flavus of 1:0.5~1.

[0011] Further, the concentration of the citrate-disodium hydrogen phosphate buffer solution in step S1 is 0.05~0.2 mol / L, and the molar ratio of citrate to disodium hydrogen phosphate is 1:1~2.

[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This invention discloses a process for converting animal manure into liquid organic fertilizer. The process uses carboxymethyl-β-glucan-grafted polyphosphate copolymer as a phosphorus protectant. During the aerobic stage, the carboxymethyl-β-glucan-grafted polyphosphate copolymer is introduced. Calcium ions coordinate with the carboxyl groups on the β-glucan backbone, causing the molecular chains to fold and coil, triggering a polymer conformational change. After the conformational change, the polyphosphate side chains are tightly arranged, forming a high-density negative charge barrier that repels free phosphate ions and adsorbs calcium ions, thus achieving the separation of calcium ions from free phosphate ions. Compared to existing methods that do not add carboxymethyl-β-glucan... The fermentation process of β-glucan-grafted polyphosphate copolymer can increase the water-soluble phosphorus content in organic fertilizer. The carboxymethyl-β-glucan-grafted polyphosphate copolymer and the polyelectrolyte complex microdomains formed with calcium ions exist in a water-dispersed state in the fermentation broth. After passing through an 80-120 mesh sieve, it is retained in the liquid phase product. During normal liquid phase storage, it does not release calcium ions or produce phosphate precipitates. After being applied to the soil, it gradually dissociates under the ion competition environment and the action of phosphatases, and the side chain polyphosphates themselves hydrolyze into orthophosphates, providing a slow-release phosphorus supply. 2. In the anaerobic fermentation stage, this invention introduces uric acid oxidase-urease co-immobilized polyaminoattapulgite. The uric acid oxidase-urease co-immobilized polyaminoattapulgite gradually converts uric acid in chicken manure into ammonium ions, eliminating the explosive release of ammonia nitrogen during the aerobic stage. Additionally, it addresses the issue of metal ions (such as Cu) originating from feed additives in the fermentation system. 2+ Zn 2+ It has a certain coordination adsorption capacity, which can fix some metal cations to the solid phase surface, thereby reducing their competitive coordination occupation of subsequent carboxymethyl-β-glucan-grafted polyphosphate copolymers, and indirectly ensuring the calcium-responsive protection effect of carboxymethyl-β-glucan-grafted polyphosphate copolymers; at the same time, the anchoring of heavy metals to the insoluble solid phase also helps to reduce the content of free heavy metals in the finished liquid organic fertilizer. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 This is a process flow diagram for converting animal manure into liquid organic fertilizer. Detailed Implementation

[0014] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0015] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0016] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0017] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0018] like Figure 1 As shown, the present invention provides a process for converting animal manure into liquid organic fertilizer, comprising the following steps: S1. Mix fresh chicken manure with citrate-disodium hydrogen phosphate buffer solution with pH 5.0~6.0 at a mass ratio of 1:1.5~2.5, and beat for 15~30 minutes to obtain a pulped solution; S2. Add waste molasses to the slurry to adjust the carbon-nitrogen ratio to 20-25:1, inoculate with anaerobic fermentation agent, and add 1.0-2.0% of urate oxidase-urease co-immobilized polyaminoattapulgite by mass of slurry. Perform anaerobic fermentation at 30-37℃ for 48-72 hours. S3. After anaerobic fermentation, inoculate with aerobic fermentation agent and add 0.5-2.0% (by weight of slurry) of carboxymethyl-β-glucan-grafted polyphosphate copolymer. Perform aerobic fermentation for 24-36 hours at 28-33℃ and dissolved oxygen of 1.5-2.5 mg / L. S4. After aerobic fermentation, the mixture is sealed and aged at 25-30℃ for 24-36 hours, and then passed through an 80-120 mesh sieve to obtain chicken manure-based liquid organic fertilizer.

[0019] In the following embodiments, the urate oxidase-urease co-immobilized polyaminoattapulgite was prepared by the following method: attapulgite was added to an ethanol solution containing 3-aminopropyltriethoxysilane and refluxed at 70-80°C for 4-8 hours to obtain aminated attapulgite; the aminated attapulgite was reacted with polyethyleneimine with a molecular weight of 600-1800 Da under glutaraldehyde crosslinking to obtain polyaminoattapulgite; the polyaminoattapulgite was added to a glutaraldehyde solution and stirred for activation; after activation, it was filtered and washed with water until no free glutaraldehyde was found to obtain an activated carrier; the activated carrier was dispersed in a pH 6.8 buffer solution, urate oxidase and urease were added, and the reaction was carried out at 4-10°C for 12-18 hours; the mixture was centrifuged, washed, and freeze-dried to obtain urate oxidase-urease co-immobilized polyaminoattapulgite.

[0020] In the following examples, the amount of polyethyleneimine added is 9 to 11% of the mass of aminated attapulgite.

[0021] In the following embodiments, the carboxymethyl-β-glucan-grafted polyphosphate copolymer was prepared by the following method: a. β-glucan was extracted from brewer's waste yeast and then subjected to carboxymethylation reaction with monochloroacetic acid in isopropanol aqueous solution to obtain carboxymethyl-β-glucan; b. Carboxymethyl-β-glucan is subjected to a dry thermal esterification grafting reaction with sodium tripolyphosphate and phosphoric acid at 120~140℃ for 2~4 hours to obtain a carboxymethyl-β-glucan grafted polyphosphate copolymer.

[0022] In the following examples, in step a, the mass ratio of β-glucan to monochloroacetic acid is 1:0.5~1.2, the reaction temperature is 50~60℃, and the reaction time is 3~5 hours; in step b, the mass ratio of carboxymethyl-β-glucan, sodium tripolyphosphate, and phosphoric acid is 1:0.3~0.8:0.05~0.15.

[0023] In the following embodiments, the anaerobic fermentation agent in step S2 is a compound bacterial solution of Candida utilis and Enterococcus faecalis, with a live count ratio of Candida utilis to Enterococcus faecalis of 1:0.8~1.2.

[0024] In the following embodiments, the aerobic fermentation agent in step S3 is a compound bacterial solution of Bacillus subtilis and Streptomyces flavus, with a live bacteria ratio of Bacillus subtilis to Streptomyces flavus of 1:0.5~1.

[0025] In the following embodiments, the concentration of the citrate-disodium hydrogen phosphate buffer solution in step S1 is 0.05~0.2mol / L, and the molar ratio of citrate to disodium hydrogen phosphate is 1:1~2.

[0026] The specific implementation is as follows: Example 1:

[0027] This invention provides a process for converting animal manure into liquid organic fertilizer, comprising the following steps: S1. Take 100 kg of fresh laying hen manure (75% moisture content, dry basis nitrogen 3.2%, phosphorus 1.8%, calcium 4.5%), add 200 kg of pH 5.5 citrate-disodium hydrogen phosphate buffer (0.1 mol / L, citrate to disodium hydrogen phosphate molar ratio 1:1.2), place in a stainless steel pulping tank, and stir at 300 rpm for 25 minutes to obtain 300 kg of pulp. S2. Add waste molasses to the slurry obtained in step S1, adjust the carbon-to-nitrogen ratio to 22:1, stir evenly to obtain the fermentation liquid; inoculate the fermentation liquid with 8 kg of anaerobic fermentation agent (the anaerobic fermentation agent is a compound bacterial solution of Candida utilis CICC 1422 and Enterococcus faecalis CMCC 140623, with an effective viable count ratio of 1:1 and a total effective viable count ≥5×10⁻⁶). 8 (CFU / mL), anaerobic fermentation was carried out at 33℃ for 60 hours; at the beginning of anaerobic fermentation, 4.5 kg of polyaminoattapulgite co-immobilized with urate oxidase-urease was added; The preparation method of the uricase-urease co-immobilized polyaminoattapulgite is as follows: (a) Take 10 g of purified attapulgite and disperse it in 200 mL of ethanol solution containing 5% (v / v) 3-aminopropyltriethoxysilane (APTES). Reflux the reaction at 78 °C for 6 hours, filter, wash with ethanol 3 times, and dry under vacuum at 60 °C to obtain aminated attapulgite. (b) Disperse 5 g of the aminated attapulgite obtained in step (a) in 100 mL of deionized water, add 0.5 g of polyethyleneimine (PEI, molecular weight 1200 Da), stir evenly, and then add 10 mL of 2.5% glutaraldehyde aqueous solution. Stir and crosslink at 25°C for 3 hours, filter, wash 3 times with deionized water, and dry at 60°C to obtain polyaminated attapulgite; (c) Disperse 5 g of the polyaminated attapulgite obtained in step (b) in 100 mL of 2.5% glutaraldehyde aqueous solution, stir and activate at 25°C for 2 hours, filter, wash with deionized water until no free glutaraldehyde is present in the washing solution, and redisperse in 100 mL of 0.05 mol / L phosphate buffer solution at pH 6.8 to obtain a dispersion. (d) Add 1.5 g of urease (enzyme activity 200 U / mg) and 0.6 g of uricase (enzyme activity 50 U / mg) to the above dispersion, and stir slowly at 6℃ for 16 hours for cross-linking reaction; after the reaction is completed, centrifuge at 8000 rpm for 15 minutes, collect the precipitate, wash 3 times with pH 6.8 phosphate buffer, and freeze dry at -50℃ for 24 hours to obtain uricase-urease co-immobilized polyaminoattapulgite.

[0028] S3. After anaerobic fermentation, inoculate the fermentation system with 6 kg of aerobic fermentation inoculant (the inoculant is a compound bacterial solution of Bacillus subtilis CAS No. 68038-70-0 and Streptomyces flavus CICC 11006, with an effective viable count ratio of 1:0.8 and a total effective viable count ≥3×10⁻⁶). 8 CFU / mL), and added 4.5 kg of carboxymethyl-β-glucan-grafted polyphosphate copolymer; aerobic fermentation for 30 hours at 30℃ and dissolved oxygen 2.0 mg / L (intermittent aeration, stirring, aeration rate of 0.5 vvm, aeration for 30 minutes and stop for 15 minutes); The method for preparing the carboxymethyl-β-glucan-grafted polyphosphate copolymer is as follows: (a) 10 g of β-glucan (purity ≥85%, molecular weight approximately 80 kDa) was extracted from brewer's waste yeast and dispersed in 150 mL of isopropanol / water mixed solvent (isopropanol to water volume ratio 4:1). The mixture was stirred and swollen for 30 minutes. 5 g of 30% NaOH solution was added to the reaction system, and the reaction was carried out at 55 °C for 30 minutes. 8 g of monochloroacetic acid was added, and the reaction was continued at 55 °C for 1.5 hours. Then, another 5 g of 30% NaOH solution was added dropwise, and the reaction was continued for 2.0 hours. After the reaction was completed, the pH of the solution was adjusted to 7.0, and 3 times the volume of anhydrous ethanol was added to precipitate the precipitate. The precipitate was filtered, washed twice with 80% ethanol aqueous solution, and dried at 60 °C to constant weight to obtain carboxymethyl-β-glucan. The degree of carboxymethyl substitution was determined to be 0.55 by titration. (b) Take 10 g of carboxymethyl-β-glucan from step (a), grind and mix it thoroughly with 5 g of sodium tripolyphosphate and 1 g of phosphoric acid, and place it in an oil bath at 130°C for dry thermal esterification reaction for 3 hours; after cooling to room temperature, wash it 3 times with 80% ethanol aqueous solution to remove unreacted sodium tripolyphosphate and phosphoric acid, and then dialyze it in deionized water for 48 hours with a dialysis bag with a molecular weight cutoff of 3500 Da (changing the water once every 8 hours), and freeze dry at -50°C to obtain carboxymethyl-β-glucan grafted polyphosphate copolymer; S4. After aerobic fermentation, transfer the fermentation liquid to a sealed aging tank and let it stand at 28°C for 30 hours. After aging, filter the liquid through a 100-mesh stainless steel sieve and collect the filtrate to obtain the chicken manure-based liquid organic fertilizer product.

[0029] Example 2:

[0030] This embodiment is based on Embodiment 1, and the process steps are basically the same as in Embodiment 1. The difference is that in step S2, 3 kg of urate oxidase-urease co-immobilized polyaminoattapulgite is added at the beginning of anaerobic fermentation; and in step S3, 1.5 kg of carboxymethyl-β-glucan-grafted polyphosphate copolymer is added. All other steps are the same.

[0031] Example 3:

[0032] This embodiment is based on Embodiment 1, with the process steps being basically the same as in Embodiment 1. The difference lies in the following: in step S2, 6 kg of urate oxidase-urease co-immobilized polyaminoattapulgite is added at the start of anaerobic fermentation; and in step S3, 6 kg of carboxymethyl-β-glucan-grafted polyphosphate copolymer is added. All other steps are the same.

[0033] Comparative Example 1 Using a traditional aerobic fermentation process without adding any of the modified components described in this invention: 100 kg of fresh laying hen manure was mixed with 200 kg of water and slurried to obtain a slurry. The carbon-nitrogen ratio of the slurry was adjusted to 22:1 using waste molasses. 6 kg of aerobic fermentation agent (a compound bacterial solution of Bacillus subtilis CAS No. 68038-70-0 and Streptomyces flavus CICC 11006, with an effective viable count ratio of 1:0.8 and a total effective viable count ≥3×10⁸ CFU / mL) was inoculated and aerobic fermentation was carried out continuously for 8 days at 30℃ and dissolved oxygen 2.0 mg / L. After fermentation, the product was filtered through a 100-mesh sieve to obtain a liquid organic fertilizer product.

[0034] Comparative Example 2 Using a traditional anaerobic fermentation process without adding any of the modified components described in this invention: Take 100 kg of fresh laying hen manure, add 200 kg of water, mix and slurry to obtain a slurry liquid. Adjust the carbon-to-nitrogen ratio of the slurry liquid to 22:1 with waste molasses. Inoculate with 8 kg of anaerobic fermentation inoculant (the anaerobic fermentation inoculant is a compound bacterial solution of *Candida utilis* CICC 1422 and *Enterococcus faecalis* CMCC 140623, with an effective viable count ratio of 1:1 and a total effective viable count ≥5×10⁻⁶). 8 The product (CFU / mL) was anaerobic fermented at 33℃ for 8 days. After fermentation, it was filtered through a 100-mesh sieve to obtain a liquid organic fertilizer product.

[0035] Comparative Example 3 Based on Example 1, the difference from Example 1 is that uricase-urease co-immobilized polyaminoattapulgite is not added in step S2; and carboxymethyl-β-glucan-grafted polyphosphate copolymer is not added in step S3. All other steps are the same.

[0036] Comparative Example 4 Based on Example 1, the difference from Example 1 is that uricase-urease co-immobilized polyaminoattapulgite is not added in step S2; all other steps are the same.

[0037] Comparative Example 5 Based on Example 1, the difference from Example 1 is that carboxymethyl-β-glucan-grafted polyphosphate copolymer is not added in step S3. All other steps are the same.

[0038] Experimental Example 1 The contents of ammonium nitrogen (refer to standard GB / T3600-2000 Determination of Ammonia Nitrogen Content in Fertilizers - Formaldehyde Method), total nitrogen (refer to standard NY / T 1977-2010), water-soluble phosphorus (refer to standard NY / T 1977-2010), and total phosphorus (refer to standard NY / T 1977-2010) in the organic fertilizers prepared in Examples 1-3 and Comparative Examples 1-5 were tested. The contents of total nitrogen (refer to standard NY / T 1977-2010), water-soluble phosphorus (refer to standard NY / T 1977-2010), and total phosphorus (refer to standard NY / T 1977-2010) in the fresh slurry of laying hen manure in Examples 1-3 and Comparative Examples 1-5 were also tested. Based on the above calculations, we can obtain: ; The results are the average of the three parallel samples, as shown in Table 1.

[0039] Table 1. Nitrogen and phosphorus performance testing of organic fertilizers

[0040] The ammonium nitrogen content in organic fertilizer should be moderate. Too high a content will inhibit the absorption of calcium, magnesium and potassium by crops, while too low a content will not meet the growth needs of crops. In this application, the degradation rate of water-soluble phosphorus is reduced, and phosphorus is effectively protected during the preparation of organic fertilizer.

[0041] Experimental Example 2 The basic properties of the organic fertilizers prepared in Examples 1-3 were tested, including appearance, pH, hygienic indicators (refer to GB / T 36195), organic matter content, total nutrient content (N+P2O5+K2O), and safety indicators (for toxic and harmful substances, refer to the standard "Limits of Toxic and Harmful Substances in Fertilizers" (GB 38400-2019)). The average value of the three parallel samples was taken, and the results are shown in Table 2.

[0042] Table 2. Basic Performance Testing of Organic Fertilizer

[0043] As shown in Table 2, the chicken manure-based liquid organic fertilizers prepared in Examples 1-3 of this invention are all uniform liquids with no obvious stratification or sedimentation. Their pH values ​​are stable within the weakly acidic range of 6.4-6.5, meeting the product form requirements for liquid organic fertilizers. The hygienic indicators meet the requirements for anaerobic treatment of liquid livestock and poultry manure in GB / T 36195-2018, and the safety indicators meet the basic limits for other fertilizers in Table 1 of GB38400-2019 "Limits of Toxic and Hazardous Substances in Fertilizers," indicating that the product has undergone thorough harmless treatment and is safe to use. This process effectively retains nitrogen and inhibits phosphorus degradation while obtaining a liquid organic fertilizer product with suitable nutrients and stable properties.

[0044] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for converting animal manure into liquid organic fertilizer, characterized in that: Includes the following steps: S1. Mix fresh chicken manure with citrate-disodium hydrogen phosphate buffer solution with pH 5.0~6.0 at a mass ratio of 1:1.5~2.5, and beat for 15~30 minutes to obtain a pulped solution; S2. Add waste molasses to the slurry to adjust the carbon-nitrogen ratio to 20-25:1, inoculate with anaerobic fermentation agent, and add 1.0-2.0% of urate oxidase-urease co-immobilized polyaminoattapulgite by mass of slurry. Perform anaerobic fermentation at 30-37℃ for 48-72 hours. S3. After anaerobic fermentation, inoculate with aerobic fermentation agent and add 0.5-2.0% (by weight of slurry) of carboxymethyl-β-glucan-grafted polyphosphate copolymer. Perform aerobic fermentation for 24-36 hours at 28-33℃ and dissolved oxygen of 1.5-2.5 mg / L. S4. After aerobic fermentation, the mixture is sealed and aged at 25-30℃ for 24-36 hours, and then passed through an 80-120 mesh sieve to obtain chicken manure-based liquid organic fertilizer.

2. The process for converting animal manure into liquid organic fertilizer according to claim 1, characterized in that: The urate oxidase-urease co-immobilized polyaminoattapulgite was prepared by the following method: attapulgite was added to an ethanol solution containing 3-aminopropyltriethoxysilane and refluxed at 70-80°C for 4-8 hours to obtain aminated attapulgite; the aminated attapulgite was then reacted with polyethyleneimine with a molecular weight of 600-1800 Da under glutaraldehyde crosslinking to obtain polyaminoattapulgite. Polyamined attapulgite was added to a glutaraldehyde solution and stirred for activation. After activation, the mixture was filtered and washed with water until no free glutaraldehyde remained, yielding the activated carrier. The activated carrier was then dispersed at pH [missing value]. Uric acid oxidase and urease were added to a 6.8 buffer solution and reacted at 4-10°C for 12-18 hours. The mixture was then centrifuged, washed, and freeze-dried to obtain uricase-urease co-immobilized polyaminoattapulgite.

3. The process for converting animal manure into liquid organic fertilizer according to claim 2, characterized in that: The amount of polyethyleneimine added is 9-11% of the mass of the aminated attapulgite.

4. The process for converting animal manure into liquid organic fertilizer according to claim 1, characterized in that: The carboxymethyl-β-glucan-grafted polyphosphate copolymer was prepared by the following method: a. β-glucan was extracted from brewer's waste yeast and then subjected to carboxymethylation reaction with monochloroacetic acid in isopropanol aqueous solution to obtain carboxymethyl-β-glucan; b. Carboxymethyl-β-glucan is subjected to a dry thermal esterification grafting reaction with sodium tripolyphosphate and phosphoric acid at 120~140℃ for 2~4 hours to obtain a carboxymethyl-β-glucan grafted polyphosphate copolymer.

5. The process for converting animal manure into liquid organic fertilizer according to claim 4, characterized in that: In step a, the mass ratio of β-glucan to monochloroacetic acid is 1:0.5~1.2, the reaction temperature is 50~60℃, and the reaction time is 3~5 hours; in step b, the mass ratio of carboxymethyl-β-glucan, sodium tripolyphosphate, and phosphoric acid is 1:0.3~0.8:0.05~0.

15.

6. The process for converting animal manure into liquid organic fertilizer according to claim 1, characterized in that: In step S2, the anaerobic fermentation agent is a compound bacterial solution of Candida utilis and Enterococcus faecalis, with a live cell ratio of Candida utilis to Enterococcus faecalis of 1:0.8~1.

2.

7. The process for converting animal manure into liquid organic fertilizer according to claim 1, characterized in that: The aerobic fermentation agent mentioned in step S3 is a compound bacterial solution of Bacillus subtilis and Streptomyces flavus, with a live bacteria ratio of Bacillus subtilis to Streptomyces flavus of 1:0.5~1.

8. The process for converting animal manure into liquid organic fertilizer according to claim 1, characterized in that: The concentration of the citrate-disodium hydrogen phosphate buffer solution in step S1 is 0.05~0.2 mol / L, and the molar ratio of citrate to disodium hydrogen phosphate is 1:1~2.

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