Livestock and poultry manure biochar base fertilizer and preparation method thereof

Abstract

The invention discloses a livestock and poultry manure biochar base fertilizer, which is prepared from the following raw materials in parts by weight: 10 to 42 percent of diluted protein liquid and collagenase modified livestock and poultry manure biochar, 20 to 40 percent of urea, 7 to 25 percent of diammonium phosphate, 7 to 24 percent of potassium chloride or potassium sulfate, 0.5 to 1 percent of modified starch and 6 to 23 percent of bentonite, after the biochar is modified by collagenase, the surface has more phenolic hydroxyl groups, carboxyl groups, aldehyde groups and hydroxyl functional groups and has a stronger adsorption effect on NH4 < + >, PO4 < 3-> and K < + >, protein distribution is more uniform through collagenase modification, and meanwhile, stable chemical combination is formed between the generated groups and the surface of the biochar, so that the dispersity of the modified biochar in an aqueous solution is improved, and the biochar has a better adsorption effect on NH4 < + >, PO4 < 3-> and K < + >. The agglomeration phenomenon is reduced; better chemical stability is realized in an acid-base environment.

Description

Technical Field

[0001] The invention belongs to the technical field of fertilizers, and specifically relates to a livestock and poultry excrement biochar-based fertilizer and a preparation method thereof. Background Art

[0002] The biochar in the existing charcoal-based fertilizers mainly comes from plants such as straw and rice husks. They have a high carbon content, strong adsorption, and a certain slow-release effect. However, they are light in texture, low in nutrients, and difficult to granulate when making charcoal-based fertilizers or easily agglomerate or turn into powder after granulation. At the same time, the nutrient content in charcoal-based fertilizers is low. Compared with chemical fertilizers, more fertilizers are needed to ensure the nutrient input per unit area of ​​the field. In addition, biochar is alkaline and may cause ammonia volatilization and reduce the effectiveness of phosphorus. The revised version of the "Law on the Prevention and Control of Environmental Pollution by Solid Waste" in 2020 stipulates that agricultural solid wastes such as straw and livestock excrement are included in the new management targets. In the future, in order to protect the environment, relevant enterprises have the obligation and responsibility to reasonably dispose of and effectively utilize waste. Against this background, the popularization of proper treatment technologies to achieve resource recycling is urgent. In view of the current shortcomings in the harmless treatment and resource utilization of livestock and poultry manure in China, such as long composting time, incomplete harmlessness, low production capacity, high cost investment, and difficulty in promotion, the development of a new livestock and poultry manure biochar-based fertilizer and its preparation method is a technical problem that needs to be urgently solved. Summary of the invention

[0003] In view of the deficiencies in the prior art, the present invention provides a new livestock and poultry manure biochar-based fertilizer and a preparation method thereof. After the livestock and poultry manure biochar in the present invention is modified by collagenase, the organic matter and structure on the surface of the biochar can be effectively changed to make it more active, because collagenase is a protease that can specifically catalyze the hydrolysis reaction of protein. There is a modified layer of protein or other nitrogen-containing organic matter on the surface of proteinized biochar. When collagenase acts on it, it will decompose the surface-modified protein into smaller polypeptides or amino acids by cutting specific peptide bonds. This decomposition process will expose more functional groups (such as carboxyl, hydroxyl and phenolic hydroxyl), thereby enhancing the chemical activity of the surface.

[0004] Furthermore, during the enzyme treatment, due to the decomposition of macromolecules and the exposure of functional groups, local structural reorganization may occur on the surface of biochar. For example, protein decomposition can make the molecular arrangement of the modified layer more loose or regular, thereby changing the surface roughness and pore characteristics of biochar. This structural reorganization helps to increase the specific surface area and the accessibility of active sites. Collagenase treatment allows small molecules (such as amino acids) produced by protein decomposition to further react chemically with active groups on the surface of biochar to generate new functional groups. At the same time, these small molecules are also retained on the surface of biochar due to adsorption, changing its surface hydrophilicity, polarity and charge distribution. This change in chemical properties can enhance the adsorption performance or catalytic activity of biochar. After the surface of biochar is treated with collagenase, the newly added functional groups and more active chemical bonds (such as carboxyl, hydroxyl and phenolic hydroxyl) increase the surface free energy. This means that the treated biochar has a stronger chemical reaction ability to other molecules or ions, thereby showing higher activity.

[0005] That is, collagenase can significantly change the surface chemical properties and structure of proteinized biochar by specifically catalyzing protein decomposition and indirectly modifying the surface. The treated biochar exhibits a higher specific surface area, more abundant active functional groups, and stronger chemical reactivity, thus becoming "more active" with more phenolic hydroxyl, carboxyl, aldehyde, and hydroxyl functional groups on the surface, which is more sensitive to NH4 + ,PO4 3- , K + , has a stronger adsorption effect.

[0006] Specifically, the livestock and poultry manure biochar-based fertilizer provided by the present invention includes the following raw materials in parts by weight: 10-42% of dilute protein solution and collagenase-modified livestock and poultry manure biochar, 20-40% of urea, 7-25% of diammonium phosphate, 7-24% of potassium chloride or potassium sulfate, 0.5-1% of modified starch, and 6-23% of bentonite, and the livestock and poultry manure is selected from one of chicken manure, cow manure, and pig manure.

[0007] Further, the steps of modifying livestock and poultry manure biochar with dilute protein solution and collagenase are as follows:

[0008] Step S1, crushing the agricultural and livestock waste into an average particle size of 2-5 mm using a crusher, and drying in an oven at 60-70° C. for 24-48 hours to obtain pretreated biomass;

[0009] Step S2, placing the pretreated biomass into a high-temperature furnace, carbonizing it under anaerobic conditions, and gradually increasing the temperature to obtain preliminary biochar;

[0010] Step S3, mixing the preliminary biochar and the dilute protein solution, ultrasonically treating for 20-30 minutes, standing for 24-48 hours, drying and solidifying, washing with 500-3000 ml of deionized water for 3-5 times to remove unadsorbed protein, and finally drying in an oven at 60-80° C. to constant weight to obtain proteinized biochar;

[0011] Step S4, mixing the proteinized biochar with the collagenase solution, stirring or oscillating the mixture in a constant temperature stirrer, terminating the enzyme reaction, and drying it in an oven at 60-80°C to constant weight to obtain finished biochar, i.e., collagenase-modified livestock and poultry manure biochar.

[0012] Furthermore, the gradual heating in step S2 is specifically as follows: firstly maintaining the temperature at 200-300°C for 1-2h, then increasing the temperature to 400-500°C and maintaining the temperature for 2-3h, and finally increasing the temperature to 600°C and maintaining the temperature for 1h.

[0013] Furthermore, the drying and curing in step S3 is specifically drying in an oven at 40-50°C for 24 hours, and then heating and curing at 80-100°C.

[0014] Furthermore, the dilute protein solution in step S3 is prepared by dissolving the protein in a buffer solution, such as PBS buffer solution, with a protein concentration of 1-5 mg / mL. The protein solution is ensured to be uniform and avoid aggregation. The protein is selected from collagen or gelatin with a molecular weight of 30,000-50,000 KD.

[0015] Furthermore, the step S3 of mixing the preliminary biochar and the dilute protein solution specifically includes adding the biochar to the protein solution at a liquid-to-solid ratio of 1:5-10, and stirring for 24-48 hours at 30-40°C and a stirring speed of 120-150rpm. This process helps protein molecules to adsorb or bind to the surface of the biochar, forming a hydrophilic protein film, and enhancing the functionality of the biochar.

[0016] Furthermore, the concentration of the collagenase solution in step S4 is 1-5 U / mL, where U represents the enzyme activity unit, and a buffer is used to maintain the pH of the mixture of the proteinized biochar and the collagenase solution at 6.5-7.0, at which the optimal activity of the collagenase can be maintained.

[0017] Furthermore, in step S4, the biochar and collagenase solution are mixed at a liquid-to-solid ratio of 1:5-10, and the mixture is stirred or oscillated in a constant temperature stirrer at 30-40°C for 24-48 hours at a stirring speed of 120-150 rpm.

[0018] Furthermore, the enzyme reaction in step S4 is terminated by filtering to remove the collagenase solution, or by washing the biochar with 500-3000 ml of deionized water for 3-5 times to remove unreacted collagenase.

[0019] The present invention also provides a method for preparing the livestock and poultry manure biochar-based fertilizer as described above, placing the mixed powder in a disc granulator, evenly spraying the modified starch solution, rolling granulation in the disc granulator, screening fertilizer particles with a particle size of 3.35 to 4.75 mm through a screening machine with a 4-6 mesh screen, and drying at 40° C. to 50° C. to obtain the final product.

[0020] After the biochar is modified by collagenase, the surface of the biochar has more phenolic hydroxyl, carboxyl, aldehyde and hydroxyl functional groups, which is beneficial to NH4 + ,PO4 3- , K + , has a stronger adsorption effect, and the enhancement of this effect is based on the following reasons:

[0021] First, protein hydrolysis. Collagenase is a specific protease that can hydrolyze peptide bonds in proteins and decompose proteins into smaller peptides and amino acid molecules. In this process, the following functional groups will be exposed or generated: carboxyl (-COOH) - in the amino acid molecules generated by protein decomposition, the structure with the carboxyl end will be released and attached to the surface of biochar; phenolic hydroxyl (-OH) - the phenolic hydroxyl on the side chain of certain amino acids (such as tyrosine) is exposed after decomposition; hydroxyl (-OH) - after the decomposition of certain hydroxyl-containing amino acids in proteins (such as serine and threonine), their hydroxyl groups are retained and distributed on the surface of biochar.

[0022] Second, the chemical modification of the biochar surface. During the enzymatic hydrolysis process of proteinized biochar, its surface modification layer will undergo a series of chemical changes and modifications, which will further enhance the generation of oxygen-containing groups and expose the intrinsic groups of biochar. While the protein is being degraded, the protein layer covering the biochar surface is partially peeled off, and the previously hidden hydroxyl, phenolic hydroxyl and carboxyl groups are re-exposed, and the aldehyde and hydroxyl groups generated by the oxidation process. The protein degradation process may be accompanied by oxidation reactions, especially the surface of biochar rich in carbon skeletons is prone to generate aldehyde and hydroxyl groups under oxidative conditions.

[0023] Third, the secondary effect of the enzymatic hydrolysis products. The small molecule products (such as peptides and amino acids) generated after the protein is degraded by collagenase will adsorb and chemically react with the biochar surface, thereby further introducing new oxygen-containing functional groups, such as carboxyl and phenolic hydroxyl groups; some amino acids (such as glutamic acid and tyrosine) contain more carboxyl and phenolic hydroxyl groups, and their degradation products may adhere to the biochar surface, further generating aldehyde groups; amino acids or peptides may undergo oxidative deamination reactions (removal of amino groups) during the enzymatic hydrolysis process, and part of the carbon skeleton in their structure will form aldehyde groups.

[0024] Fourth, the indirect effect of collagenase on the structure of biochar. The effect of collagenase is not only limited to the degradation of proteins, but also indirectly affects the structure and surface chemical properties of the biochar itself; exposure of surface pores. After the protein layer is removed, the porous structure of the biochar is exposed, increasing the specific surface area and active sites; local oxidation reaction. Enzymatic degradation may trigger oxidation reactions in the microenvironment, converting the original carbon skeleton structure on the biochar surface into oxygen-containing functional groups such as aldehydes and hydroxyls.

[0025] Fifth, the synergistic effect of ultrasound and static process. During the ultrasonic treatment and static process, the interaction between protein and biochar accelerated the generation and distribution optimization of groups. The mechanical action of ultrasound made the protein more evenly attached to the surface of biochar and promoted the adequacy of enzyme reaction. The static process enhanced the bonding between the biochar surface and the enzymatic hydrolysis products, further increasing the density of phenolic hydroxyl, carboxyl, aldehyde and hydroxyl groups.

[0026] Compared with the prior art, the present invention has the following advantages:

[0027] 1. After the biochar is modified with collagenase, the surface of the biochar has more phenolic hydroxyl, carboxyl, aldehyde and hydroxyl functional groups, which are more effective for NH4 + ,PO4 3- , K + , has a stronger adsorption effect;

[0028] 2. The specific gravity of biochar from livestock and poultry manure is relatively large, and when making carbon-based fertilizer, it can completely overcome the shortcomings of making carbon-based fertilizer from plant-based biochar;

[0029] 3. Advantages of livestock and poultry manure biochar after enzyme modification and activation:

[0030] 3.1. Rich functional groups and improved chemical activity

[0031] The modified biochar surface has more oxygen-containing functional groups (such as phenolic hydroxyl, carboxyl, aldehyde, hydroxyl, etc.). These groups have the following functions: enhance the adsorption of ions, provide active sites for catalytic reactions, and are beneficial to chemical processes such as redox reactions and esterification reactions; improve the hydrophilicity of biochar, making it more dispersible in the aqueous environment;

[0032] 3.2. Increased specific surface area and enhanced adsorption capacity

[0033] During the collagenase modification process, the degradation and reorganization of proteins make the surface modification layer thinner and more uniform, and some of the covered pores are exposed again, resulting in a significant increase in the specific surface area, providing more contact sites for adsorption reactions; the optimization of the pore structure enhances the physical adsorption capacity of ions;

[0034] 3.3. Green and environmentally friendly modification process

[0035] Collagenase is a biocatalyst with mild and efficient characteristics: the modification process is carried out under low temperature, weak acid or neutral conditions, without high temperature or strong acid and alkali conditions, reducing environmental pollution; the enzyme itself is biodegradable, avoiding the secondary pollution problem that may be caused by traditional chemical modifiers;

[0036] 3.4. Improved selective adsorption capacity

[0037] Through collagenase modification, the surface of proteinized biochar has more polar and oxygen-containing groups, showing higher selective adsorption performance for specific molecules or ions;

[0038] 3.5. Enhanced mechanical strength and stability

[0039] Collagenase modification makes the protein distribution more uniform, and the generated groups form a stable chemical bond with the surface of biochar: the dispersibility of modified biochar in aqueous solution is improved, and agglomeration is reduced; it has better chemical stability in acidic and alkaline environments;

[0040] 4. Compared with plant-derived charcoal-based fertilizers, livestock and poultry manure itself contains a higher nutrient content, so less chemical fertilizer is added to livestock and poultry manure biochar-based fertilizers, reducing production costs. In addition, livestock and poultry manure charcoal-based fertilizers have a higher nutrient content than plant-derived biochar-based fertilizers, which can reduce the amount of application per unit area of ​​land, making it easier for farmers to accept;

[0041] 5. Carbon-based fertilizer equipment is commonly used disc granulator or drum granulator, screening machine, oven, etc. The production equipment cost is low and can be produced in a separate factory with low investment and production cost. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0043] Example 1

[0044] The present embodiment provides a livestock and poultry manure biochar-based fertilizer, comprising the following raw materials in parts by weight: 27% of dilute protein solution and collagenase-modified livestock and poultry manure biochar, 34% of urea, 11% of diammonium phosphate, 8% of potassium chloride, 1% of modified starch, and 19% of bentonite, wherein the livestock and poultry manure is selected from chicken manure.

[0045] The steps of modifying livestock and poultry manure biochar with diluted protein solution and collagenase are as follows:

[0046] Step S1, crushing the agricultural and livestock waste into an average particle size of 3 mm using a crusher, and drying in an oven at 60° C. for 48 hours to obtain pretreated biomass;

[0047] Step S2, placing the pretreated biomass in a high-temperature furnace, carbonizing it under anaerobic conditions, and obtaining preliminary biochar by gradually increasing the temperature; the gradual temperature increase is specifically: first keeping it at 200°C for 2 hours, then heating it to 450°C and keeping it for 2 hours, and finally heating it to 600°C and keeping it for 1 hour;

[0048] Step S3, mixing the preliminary biochar and the dilute protein solution, ultrasonically treating for 20-30 minutes, standing for 24-48 hours, drying and curing, washing with 2000 ml of deionized water for 5 times, and finally drying in an oven at 60-80°C to constant weight to obtain proteinized biochar; drying and curing specifically comprises drying in an oven at 45°C for 24 hours, and then heating and curing at 90°C, and the dilute protein solution is collagen dissolved in PBS buffer, and the protein concentration is 3 mg / mL.

[0049] The step S3 of mixing the preliminary biochar and the dilute protein solution specifically involves adding the biochar to the protein solution at a liquid-to-solid ratio of 1:10, and stirring for 48 hours at 40° C. and a stirring speed of 150 r / min.

[0050] Step S4, mixing the proteinized biochar with the collagenase solution, stirring or oscillating the mixture in a constant temperature stirrer, terminating the enzyme reaction, and drying it in an oven at 60° C. to constant weight to obtain finished biochar, i.e., collagenase-modified livestock and poultry manure biochar.

[0051] The concentration of the collagenase solution in step S4 is 3 U / mL, and a buffer is used to maintain the pH of the mixture of proteinized biochar and collagenase solution at 7.0.

[0052] In step S4, the biochar and collagenase solution are mixed at a liquid-to-solid ratio of 1:10, and the mixture is stirred or oscillated in a constant temperature stirrer at 40° C. for 48 hours at a stirring speed of 150 rpm.

[0053] The enzyme reaction in step S4 is terminated by filtering out the collagenase solution to remove unreacted collagenase.

[0054] Example 2

[0055] This embodiment provides a method for preparing the livestock and poultry manure biochar-based fertilizer as described in Example 1, specifically, placing the mixed powder in a disc granulator, evenly spraying the modified starch solution, rolling granulation in the disc granulator, screening the fertilizer granules with a particle size of 4.75 mm through a screening machine with a 4-mesh sieve, and drying at 40°C to obtain the final product.

[0056] Performance Test:

[0057] Weigh 1.0 g of diluted protein solution and collagenase-modified biochar and unmodified biochar, add them into 100 mL of ammonium sulfate, potassium dihydrogen phosphate, and potassium sulfate solution, respectively, where the concentrations of ammonium sulfate, potassium dihydrogen phosphate, and potassium sulfate are 1000 mg / L, 2000 mg / L, and 2000 mg / L, respectively. Oscillate the mixture on a constant temperature oscillator for 24 h. After the oscillation is completed, centrifuge and determine the NH4 + ,PO4 3- , K + The concentration of biochar was calculated, and the adsorption amount of each biochar was calculated. The group with modified biochar was recorded as the experimental group, and the group with unmodified biochar was recorded as the experimental group control group. The results are shown in the table:

[0058] project Experimental Group Control group <![CDATA[NH4 after adsorption + Concentration (mg / L)]]> 53.12 86.16 <![CDATA[PO4 after adsorption 3- Concentration (mg / L)]]> 116.60 224.69 <![CDATA[K after adsorption + Concentration (mg / L)]]> 451.20 492.25 <![CDATA[Adsorption capacity (NH4 + mg / g)]]> 6.36 4.81 <![CDATA[Adsorption capacity (PO4 3- mg / g)]]> 13.48 9.16 Adsorption capacity (K+mg / g) 18.82 17.16

[0059] From the test results, it can be seen that after biochar is modified with collagenase, the surface has more phenolic hydroxyl, carboxyl, aldehyde and hydroxyl functional groups, which is beneficial to NH4 + ,PO4 3- , K + , has a stronger adsorption effect.

[0060] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A livestock and poultry manure biochar-based fertilizer, characterized in that: The invention comprises the following raw materials in parts by weight: 10-42% of dilute protein solution and collagenase-modified livestock and poultry manure biochar, 20-40% of urea, 7-25% of diammonium phosphate, 7-24% of potassium chloride or potassium sulfate, 0.5-1% of modified starch and 6-23% of bentonite, wherein the livestock and poultry manure is selected from chicken manure, cow manure and pig manure.

2. The livestock and poultry manure biochar-based fertilizer according to claim 1, characterized in that: The steps for modifying livestock and poultry manure biochar with diluted protein solution and collagenase are as follows: Step S1, crushing the agricultural and livestock waste into an average particle size of 2-5 mm using a crusher, and drying in an oven at 60-70° C. for 24-48 hours to obtain pretreated biomass; Step S2, placing the pretreated biomass into a high-temperature furnace, carbonizing it under anaerobic conditions, and gradually increasing the temperature to obtain preliminary biochar; Step S3, mixing the preliminary biochar and the dilute protein solution, ultrasonically treating for 20-30 minutes, standing for 24-48 hours, drying and solidifying, washing with 500-3000 ml of deionized water for 3-5 times, and finally drying in an oven at 60-80° C. to constant weight to obtain proteinized biochar; Step S4, mixing the proteinized biochar with the collagenase solution, stirring or oscillating the mixture in a constant temperature stirrer, terminating the enzyme reaction, and drying in an oven at 60-80° C. to constant weight to obtain finished biochar.

3. The livestock and poultry manure biochar-based fertilizer according to claim 2, characterized in that: The gradual heating in step S2 is specifically as follows: firstly keep the temperature at 200-300°C for 1-2h, then heat up to 400-500°C and keep it for 2-3h, and finally heat up to 600°C and keep it for 1h.

4. The livestock and poultry manure biochar-based fertilizer according to claim 2, characterized in that: The drying and curing in step S3 is specifically drying in an oven at 40-50°C for 24 hours, and then heating and curing at 80-100°C.

5. The livestock and poultry manure biochar-based fertilizer according to claim 2, characterized in that: The diluted protein solution in step S3 is prepared by dissolving the protein in a buffer solution, and the protein concentration is 1-5 mg / mL.

6. The livestock and poultry manure biochar-based fertilizer according to claim 2, characterized in that: The step S3 of mixing the preliminary biochar and the dilute protein solution specifically involves adding the biochar to the protein solution at a liquid-to-solid ratio of 1:5-10, and stirring for 24-48 hours at 30-40°C and a stirring speed of 120-150rpm.

7. The livestock and poultry manure biochar-based fertilizer according to claim 2, characterized in that: The concentration of the collagenase solution in step S4 is 1-5 U / mL, and a buffer is used to maintain the pH of the proteinized biochar and the collagenase solution at 6.5-7.0 after mixing.

8. The livestock and poultry manure biochar-based fertilizer according to claim 2, characterized in that: In step S4, the biochar and collagenase solution are mixed at a liquid-to-solid ratio of 1:5-10, and the mixture is stirred or oscillated in a constant temperature stirrer at 30-40°C for 24-48 hours at a stirring speed of 120-150 rpm.

9. The livestock and poultry manure biochar-based fertilizer according to claim 2, characterized in that: The enzyme reaction in step S4 is terminated by filtering to remove the collagenase solution, or by washing the biochar with 500-3000 ml of deionized water for 3-5 times to remove unreacted collagenase.

10. The method for preparing the livestock and poultry manure biochar-based fertilizer according to any one of claims 1 to 9, characterized in that: The mixed powder is placed in a disc granulator, and the modified starch solution is evenly sprayed. After rolling granulation in the disc granulator, the fertilizer granules with a particle size of 3.35 to 4.75 mm are screened by a 4-6 mesh sieve, and dried at 40°C to 50°C to obtain the final product.