A method for preparing recycled cow manure bedding based on microbial treatment

Abstract

This invention discloses a method for preparing recycled dairy cow manure bedding based on microbial treatment, belonging to the field of livestock and poultry manure treatment technology. The method of this invention combines ultrasonic assistance, three-stage relay fermentation of microorganisms, post-fermentation treatment, and expansion modification treatment to successfully prepare recycled dairy cow manure bedding. This significantly improves the fluffiness, durability, and sterilization performance of the recycled bedding, endows the bedding with high water absorption and a suitable humidity range, effectively avoids dust and caking during use, reduces the dust rate during use, gives the bedding elasticity, and extends its service life.

Description

Technical Field

[0001] This invention relates to the field of livestock and poultry manure treatment technology, and more specifically to a method for preparing recycled dairy cow manure bedding based on microbial treatment. Background Technology

[0002] Dairy manure recycled bedding refers to bedding produced on dairy farms that has been transformed into safe and hygienic bedding through processes such as solid-liquid separation, composting and fermentation, sterilization, and drying. This bedding is then reused in dairy cow bedding (such as free-row bedding and open-pen cattle sheds). It offers high economic benefits, reducing bedding procurement costs. Simultaneously, the recycling of manure reduces wastewater discharge, promoting the development of circular, ecological, and environmentally friendly agriculture. It also, to some extent, avoids dependence on forestry resources (such as sawdust).

[0003] While recycled cow manure bedding offers environmental and economic advantages, several technical challenges remain in practical application, potentially affecting its safety, stability, and widespread adoption. The main technical issues and challenges are as follows: Incomplete eradication of pathogens: Cow manure may carry pathogens such as E. coli, Salmonella, and parasite eggs. Insufficient fermentation temperature (<55℃) or time can lead to incomplete sterilization, posing a risk of animal infections (e.g., mastitis, hoof diseases) or milk contamination. Poor moisture control: High moisture content (>50%) in recycled bedding easily promotes mold growth, producing aflatoxins that negatively impact animal health. Furthermore, due to the preparation method, excessive ammonia nitrogen residue in the recycled bedding can lead to the release of harmful gases such as ammonia and hydrogen sulfide during decomposition, worsening the barn environment. Unstable physical properties: Recycled bedding may exhibit clumping, excessive dust, or insufficient fluffiness. Therefore, while using cow manure as a raw material for recycled bedding offers certain economic and environmental benefits, a series of technical problems persist, requiring further improvements to the preparation methods.

[0004] Therefore, how to provide a method for preparing a microbially treated recycled cow manure bedding material with better sterilization effect, better fluffiness and uniformity, and better water absorption is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides a method for preparing recycled cow manure bedding based on microbial treatment, which significantly improves the fluffiness, durability, and sterilization performance of the recycled bedding, gives the bedding high water absorption and a suitable humidity range, effectively avoids dust and caking during use, reduces the dust rate during use, gives the bedding elasticity, and extends its service life.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for preparing recycled cow manure bedding based on microbial treatment includes the following steps:

[0008] (1) Homogenization of fecal slurry: The fecal slurry to be treated is stirred and premixed to eliminate stratification and break up large impurities;

[0009] (2) Ultrasonic-assisted dissociation: The homogenized slurry from step (1) is passed through an ultrasonic treatment tank in a thin-layer flow state for ultrasonic-assisted dissociation;

[0010] (3) Addition of dispersant: Add sodium lignosulfonate solution to the fecal slurry after step (2) at 0.3-0.5% of the dry matter mass of the fecal slurry, and separate by eddy current to obtain solid material;

[0011] (4) Directed fermentation by compound microorganisms:

[0012] First stage 0-24h: Inoculate thermophilic actinomycetes into the solid material in step (3), and rapidly raise the temperature to 65℃ to kill pathogenic microorganisms;

[0013] Second stage 24-72h: After the first stage of fermentation is completed, cellulose-degrading bacteria are introduced to degrade stubborn fibers;

[0014] The third stage (72-120 hours): After the second stage of fermentation is completed, add Bacillus subtilis that produces extracellular polysaccharides to form a biofilm on the surface of the solid material particles.

[0015] (5) Post-fermentation treatment: The material after microbial treatment in step (4) is subjected to supercritical carbon dioxide puffing treatment. The carbon dioxide pressure is adjusted to 8-10 MPa, the temperature is 40-45℃, the pressure is maintained for 30 min, and then released to atmospheric pressure to prepare puffed material.

[0016] (6) Structural modification of expanded material: Nano-hydroxyapatite is dispersed in ethanol solution to prepare nano-hydroxyapatite suspension, which is then uniformly attached to the surface of expanded material by atomization spraying and hot air drying and curing; then graphene-modified biochar is added to expanded material and mixed by high-speed shearing to prepare dairy cow manure recycled bedding.

[0017] The beneficial effects of step (4) above are as follows: This invention uses a three-stage fermentation process to treat manure slurry. In the first stage, thermophilic actinomycetes are used to rapidly raise the temperature to 65°C, which can kill more than 99% of pathogens, such as Escherichia coli and Salmonella, significantly improving the hygiene and safety of the material. At the same time, the actinomycetes secrete heat-resistant cellulase, which initially softens the fiber structure and creates conditions for subsequent deep degradation. In the second stage, the pre-decomposition effect of the actinomycetes is synergistic, and the cellulose-degrading bacteria can convert stubborn fibers, such as straw and manure slurry fibers, into soluble sugars. The third stage involves using Bacillus subtilis, which produces extracellular polysaccharides (EPS), to process solid materials. EPS encapsulates bedding particles, forming a dense gel layer that blocks the attachment and invasion of pathogens such as E. coli and Streptococcus in the environment. Simultaneously, the Bacillus subtilis continuously secretes antimicrobial peptides, such as surfactants, giving the bedding a self-cleaning function and reducing the risk of bacterial colonization in cows' bedding. Furthermore, the network structure of EPS can absorb 10-15 times its own weight in water, far exceeding the 3-5 times absorption capacity of ordinary bedding, significantly improving water absorption. When the ambient humidity is >70%, the biofilm expands and locks in water; when the humidity is <50%, it slowly releases moisture, maintaining the optimal surface humidity of the bedding within the range of 30-40%, preventing excessive dryness leading to dust or excessive wetness causing caking. EPS acts as a natural binder, binding fine particles into uniform 3-5mm aggregates, reducing dust during use. The biofilm imparts elasticity to the bedding, improving pressure dispersion efficiency when cows are lying down and extending its service life.

[0018] Preferably, the stirring speed in step (1) is 30-50 rpm and the stirring time is 10-20 min.

[0019] Preferably, the thickness of the thin-layer flow state in step (2) is ≤10cm; the residence time of the fecal slurry in the ultrasonic treatment tank is 60-90s, and the flow rate of the fecal slurry is controlled at 2-3m³. 3 / h; the ultrasonic treatment frequency is 25-30kHz, the power is 300-350W, and the temperature is 25-30℃.

[0020] The beneficial effects of step (2) above are as follows: the fecal slurry is passed through an ultrasonic treatment tank in a thin-layer flow state, and the cavitation effect of ultrasound is used to achieve efficient physical breakage of the fiber bundles, which can effectively reduce the length of the fiber bundles, making them closer to the single fiber state, reducing bundle aggregation, and improving the degree of dissociation of fiber bundles in feces. In addition, relying on the mechanical force of cavitation bubble collapse rather than chemical corrosion, the natural mechanical properties of the fibers, such as tensile strength and modulus, can be preserved, protecting the strength and structural integrity of the fibers, and improving the fluffiness and durability of the recycled bedding.

[0021] Preferably, the concentration of the sodium lignosulfonate solution in step (3) is 8-12%; the rotation speed of the eddy current separation is 1500-2000 rpm, and the centrifugal force is 800×g; the moisture content of the solid material is 55-60%.

[0022] The beneficial effects of the above step (3) are as follows: Sodium lignosulfonate is an anionic surfactant. Its sulfonic acid group is adsorbed on the fiber surface. Through charge repulsion and spatial blocking of molecular chains, it prevents the fiber from re-aggregating due to van der Waals forces or hydrogen bonds, keeps the fiber in a monodisperse state, and avoids the formation of secondary agglomerates.

[0023] Preferably, the pressure relief rate during the puffing process in step (5) is ≤0.1MPa / min;

[0024] The beneficial effects of the above step (5) are: the use of supercritical CO2 expansion technology can increase the porosity of the material and improve the fluffiness of the bedding material, while also facilitating the loading of nano hydroxyapatite and graphene-modified biochar.

[0025] Preferably, the concentration of the nano-hydroxyapatite suspension in step (6) is 5-6% w / v;

[0026] Preferably, the nano-hydroxyapatite is prepared by the following method: under vigorous stirring, H3PO4 solution is added dropwise to Ca(OH)2 solution to adjust the pH to 10-11, and then heated in a water bath at 70-90℃ for 1-2 hours to form a white precipitate. After standing for 12-24 hours, the precipitate is centrifuged and washed until neutral, and then freeze-dried to obtain nano-hydroxyapatite.

[0027] Preferably, the spraying amount of the nano-hydroxyapatite suspension is 1.5-2.0% w / w of the weight of the expanded material;

[0028] The beneficial effect of the above operation is that the loading of nano-hydroxyapatite can enhance the ammonia absorption capacity of the bedding material.

[0029] Preferably, the hot air drying temperature is 50-60℃ and the drying time is 1-2 hours.

[0030] Preferably, the concentration of the Ca(OH)2 solution is 0.4-0.5M; the amounts of H3PO4 solution and Ca(OH)2 solution added are calculated as Ca:P = 1.67.

[0031] Preferably, the graphene-modified biochar in step (6) is prepared by the following method: rice husk is used as raw material and pyrolyzed at 600℃ under the condition of oxygen concentration <2% to obtain biochar; then the biochar is mixed with graphene oxide at a mass ratio of 10-8:1 and reduced at 800℃ for 2 hours under nitrogen protection to obtain graphene-modified biochar.

[0032] Preferably, the graphene-modified biochar is 2.0-3.0% w / w of the weight of the expanded material;

[0033] Preferably, the high-speed shearing speed is 2000 rpm and the time is 10-15 min.

[0034] The beneficial effects of the above operation are: the addition of graphene-modified biochar can form a three-dimensional water-absorbing network with the material, significantly improving the water absorption rate of the bedding material.

[0035] Another object of the present invention is to provide: a recycled cow manure bedding material prepared by the above method.

[0036] Another object of the present invention is to provide the application of the above method in the preparation of recycled cow manure bedding.

[0037] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects:

[0038] (1) This invention provides a method for preparing recycled cow manure bedding based on microbial treatment. The method uses ultrasonic-assisted treatment of manure slurry and utilizes the cavitation effect of ultrasonic waves to achieve efficient physical breakage of fiber bundles, effectively reducing the length of fiber bundles, reducing bundle aggregation, improving the degree of dissociation, protecting fiber strength and structural integrity, and improving the fluffiness and durability of recycled bedding to a certain extent.

[0039] (2) In addition, the present invention uses a three-stage strain relay fermentation method to treat the fecal slurry, which can kill more than 90% of pathogens, significantly improve the hygiene and safety of the material, give the material a self-cleaning function, and improve the water absorption rate of the material, so that the material can be effectively maintained within the optimal humidity range (30-40%), avoid excessive dryness and dust or excessive wetness and caking, reduce the dust rate during use, give the bedding material elasticity, and extend its service life. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] The thermoactinomyces vulgaris used in the embodiments of the present invention is a strain that has been disclosed in the prior art, with accession number ATCC 29680;

[0042] The exopolysaccharide-producing Paenibacillus sp. used was a strain already disclosed in the prior art, with accession number CCTCC No: M 2012463;

[0043] The cellulose-degrading bacterium used was Flavobacterium mizutaii LCD51, a strain already disclosed in the prior art, with accession number CCTCC NO: M 209100.

[0044] Example 1

[0045] A method for preparing recycled cow manure bedding based on microbial treatment includes the following steps:

[0046] (1) Homogenization of fecal slurry: The fecal slurry to be treated is premixed at 30 rpm for 10 min to eliminate stratification and break up large impurities;

[0047] (2) Ultrasonic-assisted dissociation: The homogenized slurry from step (1) is passed through an ultrasonic treatment tank in a thin-layer flow state (10cm thick) for ultrasonic-assisted dissociation. The residence time of the slurry in the ultrasonic treatment tank is 60s, and the flow rate is 2m³ / s. 3 / h; the ultrasonic treatment frequency is 25kHz, the power is 300W, and the temperature is 25℃;

[0048] (3) Addition of dispersant: Add sodium lignosulfonate solution to the fecal slurry after step (2) at 0.3% of the dry matter mass of the fecal slurry. The solution concentration is 8%. Vortex separation is carried out at 1500 rpm and centrifugal force of 800×g to obtain solid material with a moisture content of 55%.

[0049] (4) Directed fermentation by compound microorganisms:

[0050] First stage (0-24h): Inoculate the solid material in step (3) with thermophilic actinomycetes and rapidly raise the temperature to 65℃ to kill pathogenic microorganisms;

[0051] Second stage (24-72h): After the first stage of fermentation is completed, cellulose-degrading bacteria are introduced to degrade stubborn fibers;

[0052] Third stage (72-120h): After the second stage of fermentation is completed, add Bacillus subtilis that produces extracellular polysaccharides to form a biofilm on the particle surface;

[0053] (5) Post-fermentation treatment: The material after microbial treatment in step (4) is subjected to supercritical carbon dioxide puffing treatment. The carbon dioxide pressure is adjusted to 8 MPa, the temperature is 40℃, the pressure is maintained for 30 min, and then the pressure is released to atmospheric pressure. The pressure release rate is ≤0.1 MPa / min to prepare the puffed material.

[0054] (6) Structural modification of expanded material: Nano-hydroxyapatite was dispersed in an ethanol solution to prepare a 5% w / v nano-hydroxyapatite suspension. The suspension was then uniformly applied to the surface of the expanded material by atomization spraying at 1.5% w / w of the expanded material weight and cured by hot air drying at 50°C for 1 h. Then, graphene-modified biochar was added to the expanded material at 2.0-3.0% w / w of the expanded material weight and mixed by high-speed shearing at 2000 rpm for 10 min to prepare dairy cow manure recycled bedding.

[0055] The nano-hydroxyapatite was prepared by the following method: under vigorous stirring, H3PO4 solution was added dropwise to 0.4M Ca(OH)2 solution at a Ca:P ratio of 1.67, the pH was adjusted to 10, and then the mixture was heated in a water bath at 70-90℃ for 1 hour to form a white precipitate. After standing for 12 hours, the precipitate was centrifuged and washed until neutral, and then freeze-dried to obtain nano-hydroxyapatite.

[0056] The graphene-modified biochar was prepared by the following method: rice husks were pyrolyzed at 600℃ under conditions of high temperature and oxygen concentration <2% to obtain biochar; then the biochar and graphene oxide were mixed at a mass ratio of 10:1 and reduced at 800℃ for 2 hours under nitrogen protection to obtain graphene-modified biochar.

[0057] Example 2

[0058] A method for preparing recycled cow manure bedding based on microbial treatment includes the following steps:

[0059] (1) Homogenization of fecal slurry: The fecal slurry to be treated is premixed at 50 rpm for 20 min to eliminate stratification and break up large impurities;

[0060] (2) Ultrasonic-assisted dissociation: The homogenized slurry from step (1) is passed through an ultrasonic treatment tank in a thin-layer flow state (10cm thick) for ultrasonic-assisted dissociation. The residence time of the slurry in the ultrasonic treatment tank is 90s, and the flow rate is 3m³ / s. 3 / h; the ultrasonic treatment frequency is 30kHz, the power is 350W, and the temperature is 30℃;

[0061] (3) Addition of dispersant: Add sodium lignosulfonate solution to the fecal slurry after step (2) at 0.5% of the dry matter mass of the fecal slurry. The concentration of sodium lignosulfonate solution is 12%. Vortex separation is performed at 2000 rpm and centrifugal force of 800×g to obtain solid material with a moisture content of 60%.

[0062] (4) Directed fermentation by compound microorganisms:

[0063] First stage (0-24h): Inoculate the solid material in step (3) with thermophilic actinomycetes and rapidly raise the temperature to 65℃ to kill pathogenic microorganisms;

[0064] Second stage (24-72h): After the first stage of fermentation is completed, cellulose-degrading bacteria are introduced to degrade stubborn fibers;

[0065] Third stage (72-120h): After the second stage of fermentation is completed, add Bacillus subtilis that produces extracellular polysaccharides to form a biofilm on the particle surface;

[0066] (5) Post-fermentation treatment: The material after microbial treatment in step (4) is subjected to supercritical carbon dioxide puffing treatment. The carbon dioxide pressure is adjusted to 10 MPa, the temperature is 45℃, the pressure is maintained for 30 min, and then the pressure is released to atmospheric pressure. The pressure release rate is ≤0.1 MPa / min to prepare the puffed material.

[0067] (6) Structural modification of expanded material: Nano-hydroxyapatite was dispersed in an ethanol solution to prepare a 6% w / v nano-hydroxyapatite suspension. The suspension was then uniformly applied to the surface of the expanded material by atomization spraying at 2.0% w / w of the expanded material weight and cured by hot air drying at 60℃ for 2 hours. Then, graphene-modified biochar was added to the expanded material at 3.0% w / w of the expanded material weight and mixed by high-speed shearing at 2000 rpm for 15 minutes to prepare dairy cow manure recycled bedding.

[0068] The nano-hydroxyapatite was prepared by the following method: under vigorous stirring, H3PO4 solution was added dropwise to 0.5M Ca(OH)2 solution at a Ca:P ratio of 1.67, the pH was adjusted to 11, and then the solution was heated in a water bath at 70-90℃ for 2 hours to form a white precipitate. After standing for 24 hours, the precipitate was centrifuged and washed until neutral, and then freeze-dried to obtain nano-hydroxyapatite.

[0069] The graphene-modified biochar was prepared by the following method: rice husks were pyrolyzed at 600℃ under conditions of high temperature and oxygen concentration <2% to obtain biochar; then the biochar and graphene oxide were mixed at a mass ratio of 8:1 and reduced at 800℃ for 2 hours under nitrogen protection to obtain graphene-modified biochar.

[0070] Example 3

[0071] A method for preparing recycled cow manure bedding based on microbial treatment includes the following steps:

[0072] (1) Homogenization of fecal slurry: The fecal slurry to be treated is premixed at 40 rpm for 15 min to eliminate stratification and break up large impurities;

[0073] (2) Ultrasonic-assisted dissociation: The homogenized slurry from step (1) is passed through an ultrasonic treatment tank in a thin-layer flow state (10cm thick) for ultrasonic-assisted dissociation. The residence time of the slurry in the ultrasonic treatment tank is 80s, and the flow rate is 3m³ / s. 3 / h; the ultrasonic treatment frequency is 25kHz, the power is 300W, and the temperature is 28℃;

[0074] (3) Addition of dispersant: Add sodium lignosulfonate solution to the fecal slurry after step (2) at 0.4% of the dry matter mass of the fecal slurry. The concentration of sodium lignosulfonate solution is 10%. Vortex separation is performed at 1800 rpm and centrifugal force of 800×g to obtain solid material with a moisture content of 57%.

[0075] (4) Directed fermentation by compound microorganisms:

[0076] First stage (0-24h): Inoculate the solid material in step (3) with thermophilic actinomycetes and rapidly raise the temperature to 65℃ to kill pathogenic microorganisms;

[0077] Second stage (24-72h): After the first stage of fermentation is completed, cellulose-degrading bacteria are introduced to degrade stubborn fibers;

[0078] Third stage (72-120h): After the second stage of fermentation is completed, add Bacillus subtilis that produces extracellular polysaccharides to form a biofilm on the particle surface;

[0079] (5) Post-fermentation treatment: The material after microbial treatment in step (4) is subjected to supercritical carbon dioxide puffing treatment. The carbon dioxide pressure is adjusted to 10MPa and the temperature is 42℃. The pressure is maintained for 30min and then released to atmospheric pressure. The pressure release rate is ≤0.1MPa / min to prepare the puffed material.

[0080] (6) Structural modification of expanded material: Nano-hydroxyapatite was dispersed in an ethanol solution to prepare a 6% w / v nano-hydroxyapatite suspension. The suspension was then uniformly applied to the surface of the expanded material by atomization spraying at 1.8% w / w of the expanded material weight and cured by hot air drying at 55℃ for 1.5h. Then, graphene-modified biochar was added to the expanded material at 2.0% w / w of the expanded material weight and mixed by high-speed shearing at 2000rpm for 10min to prepare dairy cow manure recycled bedding.

[0081] The nano-hydroxyapatite was prepared by the following method: under vigorous stirring, H3PO4 solution was added dropwise to 0.5M Ca(OH)2 solution at a Ca:P ratio of 1.67, the pH was adjusted to 10, and then the mixture was heated in a water bath at 70-90℃ for 1 hour to form a white precipitate. After standing for 12 hours, the precipitate was centrifuged and washed until neutral, and then freeze-dried to obtain nano-hydroxyapatite.

[0082] The graphene-modified biochar was prepared by the following method: rice husks were pyrolyzed at 600℃ under conditions of high temperature and oxygen concentration <2% to obtain biochar; then the biochar and graphene oxide were mixed at a mass ratio of 10:1 and reduced at 800℃ for 2 hours under nitrogen protection to obtain graphene-modified biochar.

[0083] Comparative Example 1

[0084] It is basically the same as Example 3, except that step (2) ultrasonic-assisted dissociation is not involved.

[0085] Comparative Example 2

[0086] It is basically the same as Example 3, except that the directional fermentation in the third stage of step (4) is not involved.

[0087] Comparative Example 3

[0088] It is basically the same as Example 3, except that it does not involve the post-fermentation treatment in step (5).

[0089] Comparative Example 4

[0090] It is basically the same as Example 3, except that it does not involve the structural modification of the puffed material in step (6).

[0091] Comparison with traditional preparation methods:

[0092] (1) Solid-liquid separation: Solid-liquid separation is carried out using a common screw extrusion solid-liquid separator;

[0093] (2) Composting: Use Bacillus subtilis alone or natural fermentation, pile up to a height of 1.5-2m, in open windrows, turn over every 3-4 days, and maintain at 50-55℃ for 48 hours.

[0094] (3) Drying treatment: air dry naturally, requiring 5-7 sunny days.

[0095] (4) Bedding material forming: Add 10-15% sawdust or rice husks to improve fluffiness, and spray with 5% potassium persulfate solution for disinfection.

[0096] Bedding material performance verification

[0097] To verify the performance of the recycled bedding materials prepared by Examples 1-3, Comparative Examples 1-4, and conventional preparation methods, the following technical effects were measured:

[0098] Table 1. Determination of the performance of different groups of recycled bedding materials

[0099]

[0100]

[0101] Results Analysis: As shown in Table 1, the recycled bedding materials prepared in Examples 1-3 of this invention are superior to those prepared by comparative examples 1-4 and traditional methods in terms of sterilization effect, fluffiness, particle uniformity and water absorption rate.

[0102] Meanwhile, to further verify the performance of the recycled bedding materials prepared by Examples 1-3, Comparative Examples 1-4, and the conventional preparation method, the service life of different groups of recycled bedding materials and the concentration of ammonia gas during use were measured. The experimental results are shown in Table 2.

[0103] Table 2. Determination of the performance of different groups of recycled bedding materials

[0104] Performance indicators Service life (d) Ammonia concentration (ppm) Example 1 20 3 Example 2 21 4 Example 3 22 2 Comparative Example 1 10 14 Comparative Example 2 9 12 Comparative Example 3 14 10 Comparative Example 4 16 13 Traditional methods 7 16

[0105] Results Analysis: As shown in Table 2, the service life of the recycled bedding materials prepared in Examples 1-3 of the present invention is significantly longer than that of the bedding materials prepared by comparative examples 1-4 and traditional methods. Furthermore, the method of the present invention can effectively reduce the concentration of ammonia gas during the use of bedding materials and improve the safety of bedding material use.

[0106] Based on the above research, the incidence of mastitis in different groups of bedding materials was further studied. Healthy dairy cows were selected for the experiment, and the specific incidence of mastitis is shown in Table 3.

[0107] Table 3. Incidence of mastitis in different groups using recycled padding

[0108]

[0109]

[0110] As shown in Table 3, the recycled bedding material of this invention can significantly reduce the incidence of mastitis in dairy cows and improve the safety of bedding use.

[0111] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0112] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing recycled dairy cow manure bedding based on microbial treatment, characterized in that, Includes the following steps: (1) Homogenization of fecal slurry: The fecal slurry to be treated is stirred and premixed to eliminate stratification and break up large impurities; (2) Ultrasonic-assisted dissociation: The homogenized slurry from step (1) is passed through an ultrasonic treatment tank in a thin-layer flow state for ultrasonic-assisted dissociation; (3) Addition of dispersant: Add sodium lignosulfonate solution to the fecal slurry after step (2) at 0.3-0.5% of the dry matter mass of the fecal slurry, and separate by eddy current to obtain solid material; (4) Directed fermentation by compound microorganisms: First stage 0-24h: Inoculate thermophilic actinomycetes into the solid material in step (3), and rapidly raise the temperature to 65℃ to kill pathogenic microorganisms; Second stage 24-72h: After the first stage of fermentation is completed, cellulose-degrading bacteria are introduced to degrade stubborn fibers; The third stage (72-120 hours): After the second stage of fermentation is completed, add Bacillus subtilis that produces extracellular polysaccharides to form a biofilm on the surface of the solid material particles. (5) Post-fermentation treatment: The material after microbial treatment in step (4) is subjected to supercritical carbon dioxide puffing treatment. The carbon dioxide pressure is adjusted to 8-10 MPa, the temperature is 40-45℃, the pressure is maintained for 30 min, and then released to atmospheric pressure to prepare puffed material. (6) Structural modification of expanded material: Nano hydroxyapatite is dispersed in ethanol solution to prepare nano hydroxyapatite suspension, which is then uniformly attached to the surface of expanded material by atomized spraying and hot air drying and curing. Then, graphene-modified biochar is mixed with expanded materials and subjected to high-speed shearing and mixing to prepare recycled cow manure bedding.

2. The method for preparing recycled cow manure bedding based on microbial treatment according to claim 1, characterized in that, The stirring speed in step (1) is 30-50 rpm, and the stirring time is 10-20 min.

3. The method for preparing recycled dairy cow manure bedding based on microbial treatment according to claim 1, characterized in that, The thickness of the thin layer flow is ≤10 cm; the residence time of the slurry in the ultrasonic treatment tank is 60-90 s, and the flow rate of the slurry is controlled to be 2-3 m 3 / h; the frequency of the ultrasonic treatment is 25-30 kHz, the power is 300-350 W, and the temperature is 25-30℃.

4. The method for preparing recycled dairy cow manure bedding based on microbial treatment according to claim 1, characterized in that, The concentration of the sodium lignosulfonate solution in step (3) is 8-12%; the rotation speed of the eddy current separation is 1500-2000 rpm, and the centrifugal force is 800×g; the moisture content of the solid material is 55-60%.

5. The method for preparing recycled dairy cow manure bedding based on microbial treatment according to claim 1, characterized in that, The pressure relief rate during the puffing process described in step (5) is ≤0.1MPa / min.

6. The method for preparing recycled cow manure bedding based on microbial treatment according to claim 1, characterized in that, The concentration of the nano-hydroxyapatite suspension in step (6) is 5-6% w / v; The nano-hydroxyapatite was prepared by the following method: H3PO4 solution was added dropwise to Ca(OH)2 solution under vigorous stirring to adjust the pH to 10-11. Then, it was heated in a water bath at 70-90℃ for 1-2 hours to form a white precipitate. After standing for 12-24 hours, it was centrifuged and washed until neutral, and then freeze-dried to obtain nano-hydroxyapatite. The spraying amount of the nano-hydroxyapatite suspension is 1.5-2.0% w / w of the weight of the expanded material; The hot air drying temperature is 50-60℃, and the drying time is 1-2 hours.

7. The method for preparing recycled cow manure bedding based on microbial treatment according to claim 6, characterized in that, The concentration of Ca(OH)2 solution is 0.4-0.5M; the amount of H3PO4 solution and Ca(OH)2 solution added is calculated as Ca:P = 1.

67.

8. The method for preparing recycled cow manure bedding based on microbial treatment according to claim 1, characterized in that, The graphene-modified biochar in step (6) is prepared by the following method: rice husk is used as raw material and pyrolyzed at 600℃ under the condition of oxygen concentration <2% to obtain biochar; then the biochar is mixed with graphene oxide at a mass ratio of 10-8:1 and reduced at 800℃ for 2 hours under nitrogen protection to obtain graphene-modified biochar. The graphene-modified biochar is 2.0-3.0% w / w of the weight of the expanded material; The high-speed shearing speed is 2000 rpm, and the time is 10-15 min.

9. The recycled cow manure bedding material prepared by the method according to any one of claims 1-8.

10. The application of the method according to any one of claims 1-8 in the preparation of recycled cow manure bedding.

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