Microbial compound fertilizer for improving soil pollution as well as preparation method and application of microbial compound fertilizer

Abstract

The invention discloses a microbial compound fertilizer for improving soil pollution, which is prepared by mixing a matrix fertilizer, alginic acid, cellulase, modified bentonite, biochar, a microbial agent, nano zero-valent iron and monopotassium phosphate according to a mass ratio of (30-40): (6-10): (5-8): (20-25): (15-20): (3-5): (4-6): (4-8), the microbial agent comprises pseudomonas, bacillus and silicate bacteria; heavy metal ions in soil can be effectively neutralized through the nanoscale zero-valent iron and the phosphate, pollutants in the soil can be effectively degraded through the microbial flora, meanwhile, nutrients needed by plant growth are provided, the modified bentonite is added, the soil structure can be changed, meanwhile, phosphorus and potassium fertilizers are provided for the soil, and the soil quality is improved. By adding alginic acid and cellulase, the activity of microorganisms is effectively enhanced, the fertility conversion efficiency of the microorganisms is improved, and soil improvement and remediation are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of soil remediation, and in particular to a microbial compound fertilizer for improving soil pollution, and a preparation method and application thereof. Background Art

[0002] With the rapid development of industrialization and urbanization, solid waste is continuously piled up and dumped on the soil surface, hazardous wastewater is continuously infiltrating into the soil, and harmful gases and floating dust in the atmosphere are continuously falling into the soil with rainwater, leading to increasingly serious soil pollution problems, especially heavy metals and organic pollutants, which have had a great impact on soil quality.

[0003] Since heavy metal pollution and organic pollutants are completely different types, traditional remediation methods adopt different remediation methods and measures for different types of soil pollution, such as chemical remediation and physical remediation. Both of these are often costly and may cause secondary damage to the soil ecosystem. At the same time, they cannot provide fertility for the repaired soil, which seriously affects the growth of crops or plants. Therefore, the present invention proposes a microbial compound fertilizer for improving soil pollution and a preparation method and application thereof to solve the problems existing in the prior art. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to propose a microbial compound fertilizer for improving soil pollution, a preparation method and an application thereof. The microbial compound fertilizer for improving soil pollution, a preparation method and an application thereof can effectively neutralize heavy metal ions in the soil through nano zero-valent iron and phosphate, and can effectively degrade pollutants in the soil through microorganisms, while providing nutrients required for plant growth. The addition of modified bentonite can change the soil structure, and the absorbed phosphate can further reduce the heavy metal ion content and provide phosphorus and potassium fertilizers for the soil. The addition of alginate and cellulase effectively enhances the activity of microorganisms, improves the fertility conversion efficiency of microorganisms, and realizes soil improvement and restoration.

[0005] To achieve the purpose of the present invention, the present invention is achieved through the following technical scheme: a microbial compound fertilizer for improving soil pollution, comprising a matrix fertilizer, alginate, cellulase, modified bentonite, biochar, microbial agent, nano zero-valent iron and potassium dihydrogen phosphate mixed in a mass ratio of 30-40:6-10:5-8:20-25:15-20:3-5:4-6:4-8, the matrix fertilizer is mixed with poultry and livestock manure and crop straw in a mass ratio of 1:2, and the microbial agent includes Pseudomonas, Bacillus and silicate bacteria.

[0006] A further improvement is that the biochar is made by pyrolysis and carbonization of rice husks and crop straws, and the modified bentonite is made by mixing and drying bentonite with a mixed aqueous solution of potassium salt and phosphate salt.

[0007] A method for preparing a microbial compound fertilizer for improving soil pollution comprises the following steps:

[0008] Step 1: Preparation and mixing of base fertilizer: firstly, the crop straw and livestock manure are crushed and then composted to obtain base fertilizer; then, alginic acid and cellulase are added to the base fertilizer, stirred and mixed, and dried and granulated to obtain base fertilizer;

[0009] Step 2: symbiotic culture of bacterial strains, crushing and drying the crop straw and mixing it with rice husk to form biochar by pyrolysis and carbonization, then mixing the bacterial strain culture medium and the biochar to form a symbiotic culture medium, and then inoculating the bacterial strain into the symbiotic culture medium for cultivation to form symbiotic biochar;

[0010] Step 3, preparation of modified bentonite, firstly prepare a mixed aqueous solution of potassium salt and phosphorus salt in a molar ratio of potassium element to phosphorus element of 1:1, then add the nano-ground bentonite thereto and stir to prepare a slurry, finally divide the slurry into two parts, and dry and grind one part;

[0011] Step 4: preparing the outer packaging material, mixing the modified bentonite obtained by dry grinding in step 3 with nano zero-valent iron, potassium dihydrogen phosphate and symbiotic biochar to prepare the outer packaging powder;

[0012] Step 5: Package, dry and shape the base fertilizer, add the undried bentonite slurry in step 3 and immerse it, then filter it out and put it in the outer powder for mixing and stirring, and finally sieve out the particles and dry them to obtain the bio-compound fertilizer.

[0013] A further improvement is that in the step 1, the composting treatment uses a vertical silo reactor for mechanical composting treatment, after which the base fertilizer is added to a mixer and stirred, and alginate and cellulase are added separately for mixing and stirring, followed by granulation and drying at 120-180° C. for 5-6 hours to obtain the base fertilizer.

[0014] A further improvement is that in the step 2, the pyrolysis carbonization of rice husks and crop straws is specifically to first crush the crop straws and dry them, then mix them with the rice husks for 3 to 5 minutes, and then place them in a pyrolysis furnace at 350 to 400° C. for pyrolysis reaction to generate solid biochar.

[0015] A further improvement is that in step 2, the mass ratio of the culture medium to the biochar is 75-80:20-25; after the culture medium components are completely consumed, it is placed at 40-50° C. for drying for 16-18 hours and then crushed to obtain symbiotic biochar.

[0016] Further improvements are: in step 3, the mass ratio of the mixed aqueous solution to bentonite is 30:70; the drying conditions are 280-300° C. for 1-2 hours, and then ground and passed through a 200-mesh sieve.

[0017] A further improvement is that in step 4, the nano zero-valent iron is prepared by adding iron salt to sodium borohydride for reduction reaction, then adding hexadecyltrimethylammonium bromide and polyvinylpyrrolidone for mixed reaction, and then centrifugally separating and washing and drying with deionized water.

[0018] A further improvement is that the drying condition in step 5 is 40-45° C. for 10-12 hours.

[0019] The invention discloses an application of a microbial compound fertilizer for improving soil pollution in heavy metal polluted and organic polluted soil.

[0020] The beneficial effects of the present invention are as follows: the present invention can effectively neutralize heavy metal ions in the soil through nano zero-valent iron and phosphate, can effectively degrade pollutants in the soil through microorganisms, and provide nutrients required for plant growth; the addition of modified bentonite can change the soil structure; the absorbed phosphate can further reduce the heavy metal ion content and provide phosphorus and potassium fertilizers for the soil; the addition of alginate and cellulase effectively enhances the activity of microorganisms, improves the fertility conversion efficiency of microorganisms, realizes soil improvement and restoration, and has important application value and broad market prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a flow chart of the preparation method of Example 2 of the present invention. DETAILED DESCRIPTION

[0022] In order to deepen the understanding of the present invention, the present invention will be further described in detail below in conjunction with examples. The examples are only used to explain the present invention and do not constitute a limitation on the protection scope of the present invention.

[0023] The embodiment of the present invention provides a microbial compound fertilizer for improving soil pollution, comprising a matrix fertilizer, alginate, cellulase, modified bentonite, biochar, a microbial agent, nano zero-valent iron and potassium dihydrogen phosphate mixed in a mass ratio of 30-40:6-10:5-8:20-25:15-20:3-5:4-6:4-8, the matrix fertilizer is mixed with poultry and livestock manure and crop straw in a mass ratio of 1:2, and the microbial agent includes Pseudomonas, Bacillus and silicate bacteria.

[0024] The modified bentonite is prepared by mixing bentonite with a mixed aqueous solution of potassium salt and phosphate salt, drying and grinding. In some preferred embodiments, the potassium salt and the phosphate salt are mixed in an equimolar ratio, and the concentrations of the potassium salt and the phosphate salt in the mixed aqueous solution are both 1M, and the mass ratio of the mixed aqueous solution to the bentonite is 30:70.

[0025] The present invention also discloses a method for preparing a microbial compound fertilizer for improving soil pollution, comprising the following steps:

[0026] Step 1: Preparation and mixing of base fertilizer: firstly, the crop straw and livestock manure are crushed and then composted to obtain base fertilizer; then, alginic acid and cellulase are added to the base fertilizer, stirred and mixed, and dried and granulated to obtain base fertilizer;

[0027] Step 2: symbiotic culture of bacterial strains, crushing and drying the crop straw and mixing it with rice husk to form biochar by pyrolysis and carbonization, then mixing the bacterial strain culture medium and the biochar to form a symbiotic culture medium, and then inoculating the bacterial strain into the symbiotic culture medium for cultivation to form symbiotic biochar;

[0028] Step 3, preparation of modified bentonite, firstly prepare a mixed aqueous solution of potassium salt and phosphorus salt in a molar ratio of potassium element to phosphorus element of 1:1, then add the nano-ground bentonite thereto and stir to prepare a slurry, finally divide the slurry into two parts, and dry and grind one part;

[0029] Step 4: preparing the outer packaging material, mixing the modified bentonite obtained by dry grinding in step 3 with nano zero-valent iron, potassium dihydrogen phosphate and symbiotic biochar to prepare the outer packaging powder;

[0030] Step 5: Package, dry and shape the base fertilizer, add the undried bentonite slurry in step 3 and immerse it, then filter it out and put it in the outer powder for mixing and stirring, and finally sieve out the particles and dry them to obtain the bio-compound fertilizer.

[0031] In some preferred embodiments, the composting treatment in step 1 is performed by mechanical composting using a vertical silo reactor, and after the treatment, the base fertilizer is added to a mixer and stirred, and alginic acid and cellulase are added respectively for mixing and stirring, followed by granulation and drying at 120-180° C. for 5-6 hours to obtain a base fertilizer. In a more preferred embodiment, the drying condition after granulation is 180° C. for 5.5 hours.

[0032] In some preferred embodiments, the pyrolysis carbonization of rice husk and crop straw in step 2 is to first crush the crop straw and dry it, then mix it with the rice husk for 3 to 5 minutes, and then place it in a pyrolysis furnace at 350 to 400° C. to perform pyrolysis reaction to generate solid biochar. In a more preferred embodiment, the pyrolysis temperature is 400° C.

[0033] In some preferred embodiments, in step 2, the mass ratio of the culture medium to the biochar is 75-80:20-25; after the culture medium components are completely consumed, the culture medium is placed at 40-50°C for drying for 16-18 hours and then crushed to obtain the symbiotic biochar. As an example, the mass ratio of the culture medium to the biochar is 80:20.

[0034] In some preferred embodiments, the mass ratio of the mixed aqueous solution to bentonite in step three is 30:70; the drying conditions are drying at 280-300° C. for 1-2 hours, and then grinding and passing through a 200-mesh sieve.

[0035] In some preferred embodiments, the nano zero-valent iron in step 4 is prepared by adding an iron salt to sodium borohydride for reduction reaction, then adding hexadecyltrimethylammonium bromide and polyvinylpyrrolidone for mixed reaction, and then centrifugally separating and washing and drying with deionized water. The specific preparation method is a conventional technical means in the art and will not be described in detail here.

[0036] In some preferred embodiments, the drying condition in step five is 40-45° C. for 10-12 hours.

[0037] In the following examples of the present invention, the microbial strains used were directly purchased, wherein Pseudomonas was purchased from China Type Culture Collection, Wuhan University, with a collection number of CCTCC AB 2012423; Bacillus was purchased from China Type Culture Collection, with a collection number of CCTCC AB 130020; and silicate bacteria was purchased from China Type Culture Collection, Wuhan University, with a collection number of CCTCC No.M200040.

[0038] The mass ratio parameter of the microbial agent is the total amount of all strains after mixed culture of the bacterial culture medium (NA solid culture medium) and biochar.

[0039] Example 1

[0040] The present embodiment provides a microbial compound fertilizer for improving soil pollution, comprising a mixture of matrix fertilizer, alginate, cellulase, modified bentonite, biochar, microbial agent, nano zero-valent iron and potassium dihydrogen phosphate in a mass ratio of 30:10:8:20:15:5:6:6, the matrix fertilizer is a mixture of poultry and livestock manure and crop straw in a mass ratio of 1:2, and the microbial agent includes Pseudomonas, Bacillus and silicate bacteria.

[0041] The biochar is made by pyrolysis and carbonization of rice husk and crop straw, and the modified bentonite is made by mixing and drying bentonite with a mixed aqueous solution of potassium chloride and diammonium phosphate.

[0042] according to Figure 1 As shown, this embodiment provides a method for preparing a microbial compound fertilizer for improving soil pollution, comprising the following steps:

[0043] Step 1: First, the crop straw and livestock manure are crushed and then mechanically composted using a vertical silo reactor. After the treatment, the base fertilizer is added to a mixer and stirred, and alginate and cellulase are added separately for mixing and stirring. Subsequently, granulation is performed and the base fertilizer is dried at 180° C. for 5.5 hours to obtain the base fertilizer.

[0044] Step 2: Crush and dry the crop straw, mix it with rice husk, and pyrolyze and carbonize it to make biochar. Then, mix the bacterial culture medium with the biochar to make a symbiotic culture medium. Then, inoculate the bacterial culture into the symbiotic culture medium for cultivation to make symbiotic biochar.

[0045] The pyrolysis carbonization process is to first crush the crop straw and dry it, then mix it with rice husk for 3 minutes, and then place it in a pyrolysis furnace at 400°C to generate solid biochar.

[0046] The mass ratio of the culture medium (NA solid culture medium) to the biochar was 80:20, and the culture medium was activated before inoculation. After the culture medium components were completely consumed, it was dried at 42°C for 16 hours and crushed to obtain the symbiotic biochar.

[0047] Step 3: first prepare a mixed aqueous solution (both concentrations are 1 M) of potassium salt and phosphate salt in a molar ratio of potassium to phosphorus of 1:1, then add the nano-ground bentonite and stir to form a slurry, wherein the mass ratio of the mixed aqueous solution to bentonite is 30:70, and finally divide the slurry into two parts, one of which is dried and ground at 300°C for 1.5 hours, and then ground and passed through a 200-mesh sieve.

[0048] Step 4: Mixing and stirring the modified bentonite obtained by dry grinding in step 3 with nano zero-valent iron, potassium dihydrogen phosphate and symbiotic biochar to obtain an outer packaging powder;

[0049] The nano zero-valent iron is prepared by adding iron salt to sodium borohydride for reduction reaction, then adding hexadecyltrimethylammonium bromide and polyvinylpyrrolidone for mixed reaction, and then centrifugally separating and washing and drying with deionized water.

[0050] Step 5: Add the base fertilizer into the undried bentonite slurry in step 3 and immerse it, then filter it out and put it into the outer powder for mixing and stirring, and finally sieve out the particles and dry them at 40° C. for 10 hours to obtain the bio-compound fertilizer.

[0051] Example 2

[0052] The difference from Example 1 is that the raw materials include substrate fertilizer, alginate, cellulase, modified bentonite, biochar, microbial agent, nano zero-valent iron and potassium dihydrogen phosphate in a mass ratio of 35:6:6:25:18:3:4:4, the substrate fertilizer is made by mixing poultry and livestock manure and crop straw in a mass ratio of 1:2, and the microbial agent includes Pseudomonas, Bacillus and silicate bacteria.

[0053] Example 3

[0054] The difference from Example 1 is that the raw materials include substrate fertilizer, alginate, cellulase, modified bentonite, biochar, microbial agent, nano zero-valent iron and potassium dihydrogen phosphate in a mass ratio of 40:8:5:25:15:5:6:8, the substrate fertilizer is made by mixing poultry and livestock manure and crop straw in a mass ratio of 1:2, and the microbial agent includes Pseudomonas, Bacillus and silicate bacteria.

[0055] Application Examples

[0056] This embodiment provides an application of a microbial compound fertilizer for improving soil pollution in heavy metal-contaminated and organic-contaminated soil.

[0057] The biological compound fertilizer prepared in Example 1-3 is spread on the soil polluted by heavy metals and organic pollution, and is spread according to the amount of 65kg / mu, and the plot is ploughed after spreading; At the same time, as a control, the soil is remediated by the traditional biological remediation method in the same contaminated soil, and the soil of the two plots is sampled on the 10th day, the 30th day and the 60th day, and the heavy metal content of the soil is detected using a heavy metal detector, and the content of difficult-to-decompose organic pollutants in the soil is detected using a soil analyzer, and the fertility of the soil (including organic matter content and total content of nitrogen, phosphorus and potassium) is detected using a soil fertilizer detector. After testing, the biological compound fertilizer effect of Examples 2 and 3 is slightly inferior to that of Example 1, but it is also significantly better than the effect of traditional biological remediation. Therefore, Table 1 only records the comparative data of the optimal embodiment (Example 1) and traditional biological remediation, as shown in the table below.

[0058] Table 1

[0059]

[0060] Note: Organic pollutants include organic pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls, volatile organic compounds, semi-volatile organic compounds, petroleum and their derivatives.

[0061] Traditional bioremediation uses microbial agents, which use microorganisms (such as bacteria, fungi, etc.) to convert heavy metals in the soil into less toxic forms, or remove heavy metals from the soil through the metabolism of microorganisms; use microorganisms to metabolize organic pollutants as carbon sources and convert them into low-toxic or non-toxic small molecule compounds, such as carbon dioxide, water, simple alcohols or acids, etc.

[0062] It can be seen from the above table that the use of the biofertilizer of the present application can better improve soil contaminated by heavy metals and organic pollutants. The heavy metal content of the soil after repair reaches the national secondary or even primary standard, and the repair effect is significantly better than that of traditional methods.

[0063] At the same time, through soil fertility testing, it can be seen that the biocompound fertilizer of the present application can provide a certain amount of fertility to the soil while repairing the soil, while traditional bioremediation only uses microbial metabolism to produce fertility, which is limited and has poor durability.

[0064] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A microbial compound fertilizer for improving soil pollution, characterized in that: The invention comprises a mixture of substrate fertilizer, alginate, cellulase, modified bentonite, biochar, microbial agent, nano zero-valent iron and potassium dihydrogen phosphate in a mass ratio of 30-40:6-10:5-8:20-25:15-20:3-5:4-6:4-8, wherein the substrate fertilizer is mixed with livestock manure and crop straw in a mass ratio of 1:2, and the microbial agent comprises pseudomonas, bacillus and silicate bacteria.

2. The microbial compound fertilizer for improving soil pollution according to claim 1, characterized in that: The biochar is prepared by pyrolysis and carbonization of rice husks and crop straws, and the modified bentonite is prepared by mixing, drying and grinding bentonite with a mixed aqueous solution of potassium salt and phosphate salt.

3. A method for preparing a microbial compound fertilizer for improving soil pollution, characterized in that: The following steps are involved: Step 1, preparation of base fertilizer: firstly, the crop straw and livestock manure are crushed and then composted to obtain base fertilizer, then alginic acid and cellulase are added to the base fertilizer, stirred and mixed, and dried and granulated to obtain base fertilizer; Step 2: symbiotic culture of bacterial strains: crushing and drying the crop straw and mixing it with rice husk to form biochar by pyrolysis and carbonization, then mixing the bacterial strain culture medium with the biochar to form a symbiotic culture medium, and then inoculating the bacterial strain into the symbiotic culture medium for cultivation to form symbiotic biochar; Step 3, preparation of modified bentonite: firstly, potassium salt and phosphate salt are prepared into a mixed aqueous solution in a molar ratio of potassium element to phosphorus element of 1:1, then the nano-ground bentonite is added thereto and stirred to prepare a slurry, and finally the slurry is evenly divided into two parts, and one of the parts is dried and ground; Step 4: Preparation of outer packaging material: Mixing and stirring the modified bentonite obtained by dry grinding in step 3 with nano zero-valent iron, potassium dihydrogen phosphate and symbiotic biochar to obtain outer packaging powder; Step 5: Package, dry and shape treatment: add the base fertilizer into the undried bentonite slurry in step 3 to immerse it, then filter it out and put it into the outer powder for mixing and stirring, and finally sieve out the particles and dry them to obtain the bio-compound fertilizer.

4. The method for preparing a microbial compound fertilizer for improving soil pollution according to claim 3, characterized in that: In the step 1, the composting treatment uses a vertical silo reactor for mechanical composting treatment. After the treatment, the base fertilizer is added to a mixer and stirred, and alginic acid and cellulase are added separately for mixing and stirring. Then, granulation is performed and the base fertilizer is placed at 120-180° C. and dried for 5-6 hours to obtain the base fertilizer.

5. The method for preparing a microbial compound fertilizer for improving soil pollution according to claim 3, characterized in that: In the step 2, the pyrolysis carbonization of rice husk and crop straw is specifically to first crush the crop straw and dry it, then mix it with the rice husk and dry mix it for 3 to 5 minutes, and then place it in a pyrolysis furnace at 350 to 400° C. to perform a pyrolysis reaction to generate solid biochar.

6. The method for preparing a microbial compound fertilizer for improving soil pollution according to claim 3, characterized in that: In the step 2, the mass ratio of the bacterial culture medium to the biochar is 75-80:20-25; after the bacterial culture medium components are completely consumed, the bacterial culture medium is placed at 40-50° C. for drying for 16-18 hours and then crushed to obtain the symbiotic biochar.

7. The method for preparing a microbial compound fertilizer for improving soil pollution according to claim 3, characterized in that: In the step 3, the mass ratio of the mixed aqueous solution to the bentonite is 30:70; the drying condition is 280-300° C. for 1-2 hours, and then ground and passed through a 200-mesh sieve.

8. The method for preparing a microbial compound fertilizer for improving soil pollution according to claim 3, characterized in that: In step 4, the nanometer zero-valent iron is prepared by adding iron salt to sodium borohydride for reduction reaction, then adding hexadecyltrimethylammonium bromide and polyvinylpyrrolidone for mixed reaction, and then centrifugally separating and washing and drying with deionized water.

9. The method for preparing a microbial compound fertilizer for improving soil pollution according to claim 1, characterized in that: The drying condition in step 5 is drying at 40-45° C. for 10-12 hours.

10. Application of a microbial compound fertilizer for improving soil pollution in heavy metal polluted and organic polluted soils.

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