A soil remediation improver, a soil remediation method, and a soil maintenance method

Abstract

The application provides a soil remediation modifier, a soil remediation method and a soil maintenance method, and belongs to the technical field of soil remediation.The soil remediation modifier is prepared from the following raw materials in parts by weight: modified silt 40-50 parts, humic acid 10-15 parts, bioactive components 5-10 parts, inorganic components 10-15 parts and organic components 10-15 parts.The soil remediation modifier can increase the total porosity of soil, improve the water-stable aggregates of soil, improve the soil structure, improve the soil fertility, improve the pH value of soil and passivate heavy metal ions, so that the remediated soil can meet the needs of plant growth, the silt and traditional Chinese medicine residue are recycled and utilized, waste is turned into treasure, and the soil remediation modifier has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of soil remediation, in particular to a soil remediation modifier, a soil remediation method and a soil maintenance method. BACKGROUND

[0002] Current soil remediation technologies mainly include in-situ remediation and ex-situ remediation. In-situ remediation gradually becomes the mainstream technology because it disposes pollutants on site, does not need long-distance transportation and construction of expensive engineering infrastructure, and is easy to operate and maintain. Chemical remediation and physical remediation are often used in in-situ soil remediation technology.

[0003] Chemical oxidation in chemical remediation is a low-cost and relatively simple remediation technology, which is suitable for soil remediation technology of organic contaminated sites with good permeability. The technology injects chemical oxidants into the ground, and through the contact between the oxidants and the underground pollutants, the organic pollutants in the soil are destroyed and degraded into non-toxic or less harmful substances. Soil gas extraction technology in physical remediation is a technology that uses vacuum equipment to extract gas from pre-installed extraction wells, generates negative pressure in the contaminated soil, drives air to flow through soil pores, forces pollutants to be extracted with soil gas, and then discharges after treatment, so as to achieve the purpose of soil remediation.

[0004] In physical remediation, it is greatly affected by the permeability of the soil. In the soil with poor permeability, even under negative pressure, the overflow speed of volatile organic compounds is slow, and the required treatment time is long, resulting in low treatment efficiency. In addition, when volatile organic compounds are extracted under negative pressure, there is a risk of accidental leakage, and when volatile organic compounds are adsorbed under negative pressure, their concentration is high, which can cause great safety hazards to the surrounding environment and organisms. SUMMARY

[0005] The present application aims to provide a soil remediation modifier, a soil remediation method and a soil maintenance method, which can not only increase the total porosity of the soil, improve the soil water stability aggregate, and improve the soil structure, but also improve the soil fertility, improve the soil pH value, and passivate heavy metal ions, so that the remediated soil can adapt to the needs of plant growth. At the same time, the sludge and traditional Chinese medicine residue are resourcefully utilized, turning waste into treasure, which has a broad application prospect.

[0006] The technical solution of the present invention is achieved as follows: The present invention provides a soil remediation improver, which is prepared from the following raw materials in parts by weight: 40-50 parts of modified sludge, 10-15 parts of humic acid, 5-10 parts of biologically active ingredients, 10-15 parts of inorganic ingredients, and 10-15 parts of organic ingredients; the modified sludge is silicon oxide modified with tannic acid, which is then deposited on the surface with graphene oxide and chitosan, and in situ reduced to obtain a nano-Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite, which is then modified with a silane coupling agent containing a mercapto group and mixed with riverbed sludge and traditional Chinese medicine residue to obtain the composite; the biologically active ingredient is obtained by reacting diatomaceous earth modified with tannic acid with chitosan, adding the reacted reactants to a bacterial suspension and an enzyme solution, and evaporating the solvent.

[0007] As a further improvement of the present invention, the modified sludge preparation method is as follows: S1. Preparation of modified silica: Dissolve tetraethyl orthosilicate in ethanol, add hydrochloric acid and water, stir to react, dry, calcine, add Tris-HCl solution and tannic acid to the solid, heat and stir to react, filter, wash, and dry to produce modified silica; S2. Preparation of graphene oxide / chitosan-modified silica composite: Add modified silica to acetic acid solution, add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, stir to activate, add chitosan, stir to react, add graphene oxide, stir to react, and spray dry to produce graphene oxide / chitosan-modified silica composite; S3. Preparation of nano-Fe / Ni@graphene oxide / chitosan-modified silica composite: Add the graphene oxide / chitosan-modified silica composite to water. Under inert gas, add iron salt and nickel salt. Stir and mix thoroughly. Then, dropwise add sodium borohydride solution. Stir and react. Centrifuge, wash, and dry to obtain nano-Fe / Ni@graphene oxide / chitosan-modified silica composite. S4. Preparation of modified nano-Fe / Ni@graphene oxide / chitosan-modified silica composite: Add the nano-Fe / Ni@graphene oxide / chitosan-modified silica composite to ethanol. Add a silane coupling agent with a mercapto group. Heat and stir to react. Centrifuge, wash, and dry to obtain modified nano-Fe / Ni@graphene oxide / chitosan-modified silica composite. S5. Preparation of modified sludge: riverbed sludge and Chinese medicine residue are mixed evenly, dried, ground, and evenly mixed with modified nano-Fe / Ni@graphene oxide / chitosan-modified silica composite, soaked in nutrient solution, and the solvent is evaporated to obtain modified sludge.

[0008] As a further improvement of the present application, the mass ratio of tetraethyl orthosilicate, ethanol, hydrochloric acid and water in step S1 is 10-12:100-150:15-20:7-10, the stirring reaction time is 7-10h, the calcination temperature is 400-500℃, the time is 2-3h, the mass ratio of the solid and tannic acid is 10:3-4, the pH value of the Tris-HCl solution is 8.5-9.5, the heating stirring reaction temperature is 35-45℃, and the time is 2-4h; the mass ratio of the modified silicon oxide, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, chitosan and graphene oxide in step S2 is 10:2-3:1-3:12-15:3-5.

[0009] As a further improvement of the present application, the mass ratio of the graphene oxide / chitosan-modified silicon oxide composite, iron salt, nickel salt and sodium borohydride in step S3 is 8-10:1.2-1.4:0.7-1:1.8-2.2, the iron salt is selected from at least one of ferric chloride, ferric sulfate, ferric nitrate, the nickel salt is selected from at least one of nickel chloride, nickel sulfate, nickel nitrate; the mass ratio of the nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite and the silane coupling agent with thiol group in step S4 is 10:1-2, the silane coupling agent with thiol group is selected from at least one of KH580, KH590, and the heating stirring reaction temperature is 45-55℃, and the time is 2-4h.

[0010] As a further improvement of the present application, the mass ratio of the river bottom sludge, traditional Chinese medicine residue, modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite and nutrient solution in step S5 is 10-15:3-5:7-10:100, the ratio of the nutrient solution is: carbon source 10-15g / L, nitrogen source 7-10g / L, inorganic salt 1-2g / L, the carbon source is selected from at least one of glucose, fructose, sucrose, citric acid, the nitrogen source is selected from at least one of urea, ammonium nitrate, ammonium phosphate, fish meal, and the inorganic salt is selected from at least one of sodium chloride, potassium chloride, magnesium sulfate, manganese sulfate, zinc sulfate, calcium chloride.

[0011] As a further improvement of the present application, the preparation method of the bioactive ingredient is as follows: T1. Add nitrogen-fixing bacteria, oxalic acid mold, Bacillus subtilis and Trichoderma harzianum into nutrient solution to prepare a bacterial suspension; T2. Add urease, phosphatase, catalase and cellulase into water to prepare an enzyme solution; T3. Add diatomite into Tris-HCl solution, add tannic acid, heat and stir to react, filter, wash, and dry to prepare modified diatomite; T4. Add the modified diatomite into acetic acid solution, add N-hydroxy succinimide and 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, stir to activate, add chitosan, stir to react, filter, wash, and dry to prepare chitosan-diatomite compound; and T5. Mix the bacterial suspension and the enzyme solution uniformly, add the chitosan-diatomite compound, and evaporate the solvent to prepare the bioactive ingredient.

[0012] As a further improvement of the present application, the mass ratio of the nitrogen-fixing bacteria, oxalic acid mold, Bacillus subtilis and Trichoderma harzianum in step T1 is 2-3:1-2:4-7:2-3; the mass ratio of the urease, phosphatase, catalase, cellulase and water in step T2 is 1-2:0.5-1:0.3-0.5:0.2-0.5:50; the pH value of the Tris-HCl solution in step T3 is 8.5-9.5, the mass ratio of the diatomite and tannic acid is 10:2-3, the temperature of the heat and stirring reaction is 40-50℃, and the time is 2-4h; the mass ratio of the modified diatomite, N-hydroxy succinimide, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and chitosan in step T4 is 10:2-3:1-2:5-7; and the mass ratio of the bacterial suspension, enzyme solution and chitosan-diatomite compound in step T5 is 10:3-5:5-7.

[0013] As a further improvement of the present application, the inorganic component is selected from at least one of sodium silicate, potassium silicate, calcium carbonate, bentonite, montmorillonite and diatomite, and the organic component is selected from at least one of chitosan, lignin, cellulose and hemicellulose.

[0014] The present application further protects a soil remediation method, which comprises the following steps: (1) first, dig a plurality of cavities in the soil to be remediated, and perform a drying and dredging pretreatment on the soil; (2) uniformly apply the soil remediation modifier described above in the cavities, and mix uniformly by turning and stirring; (3) detect the content of organic matter, heavy metal ions and pH value in the soil, and complete the soil remediation when the values are within the safety range.

[0015] The present application further protects a soil maintenance method, which comprises the following steps: uniformly apply the soil remediation modifier described above in the soil, mix uniformly by turning and stirring, and repeat the application every 6-12 months to complete the soil maintenance.

[0016] The present invention has the following beneficial effects: Riverbed silt is an excellent soil remediation material, containing a large amount of organic matter and nutrients. These substances can be decomposed by microorganisms under appropriate conditions, releasing nutrients such as nitrogen and phosphorus, effectively improving the physical and chemical properties of the soil.

[0017] Sandy soil has strong permeability but poor water and fertilizer retention. Modified silt is rich in organic matter and clay, which can improve the structure of sandy soil and enhance its water and fertilizer retention capacity. Clay soil has poor aeration and is prone to compaction. Modified silt can improve the aeration of clay soil, increase its organic matter content, and promote the formation of aggregate structure. Saline-alkali soil has high salt content, which affects plant growth. The organic matter and calcium and magnesium ions in modified silt can neutralize the salt in saline-alkali soil and improve its structure. Poor soil is nutrient-deficient and has low productivity. Modified silt with a high organic matter content can replenish nutrients in poor soil and improve soil fertility.

[0018] Modified sludge is rich in organic matter and trace elements, effectively improving the physical and chemical properties of the soil. Humic acid enhances the soil's ability to retain water and nutrients and promotes the formation of aggregate structures. Bioactive ingredients, including nitrogen-fixing bacteria, oxalic acid molds, and enzymes, promote nutrient conversion and enhance soil fertility. Inorganic components, such as silicates and calcium carbonate, improve soil structure and pH, enhancing soil stability. Organic components, such as lignin, increase soil organic matter content and improve soil structure.

[0019] The present invention prepares a modified sludge. After a sol-gel reaction, silicon oxide powder is prepared. The surface is modified with tannic acid and coupled with chitosan to form a swollen chitosan-tannic acid composite cross-linked network on the silicon oxide surface. Graphene oxide is added and spray-dried to form a wrinkled graphene oxide-chitosan composite on the surface. The specific surface area, cation exchange capacity and the number of oxygen-containing functional groups are significantly increased. The composite has a good adsorption effect on organic pollutants and can adsorb iron and nickel ions. Under the reducing action of sodium borohydride, nano-iron / nickel is prepared in situ. Hydrogen is generated during the reaction of the nano-zero-valent iron. The hydrogen has a strong destructive ability on C-Cl bonds and double bonds, exerting its reducing effect. Therefore, the metal-modified nano-zero-valent iron can be better used for removing organic pollutants. After further modification of its surface with a silane coupling agent containing a mercapto group, the mercapto group reacts with metallic iron to form various iron sulfides. The electrons generated by the sulfided nano-iron tend to be transferred to organic pollutants rather than water molecules, which can also inhibit the hydrogen evolution rate of iron to a certain extent, overcoming the defects of nano-zero-valent iron such as easy agglomeration, easy oxidation, and poor electron selectivity. At the same time, there will be no secondary pollution that may be caused by the release of metal.

[0020] In addition, the prepared modified nano Fe / Ni@ graphene oxide / chitosan-modified silicon oxide composite is more easy to adsorb and fix the dried modified sludge and traditional Chinese medicine residues with the help of silane coupling agent, and can adsorb nutrients through complexation and hydrogen bonding, so that the total porosity of soil is increased, the soil bulk density is reduced, the water holding capacity is increased, the soil capillary porosity, non-capillary porosity and aeration degree are all increased, and the soil organic matter, total N, hydrolyzed N, available P, available K content of the sludge, the sludge and the nutrients are increased, and the soil pH value is adjusted, and the soil buffering capacity is enhanced. Meanwhile, the chitosan-tannic acid composite crosslinking network can improve the soil water stable aggregate, the soil structure is improved, the soil water erosion resistance is increased, the soil loss is reduced, and the soil heavy metal ions are fixed, and the heavy metal is passivated, so that the soil has a good repair effect.

[0021] The bioactive ingredient prepared in the application includes various active bacteria and various active enzymes, can effectively increase the number of soil microorganisms, improve the enzyme activity, plays a very key role for plants, and can inhibit the activities of fungi, bacteria and actinomycetes, so that the soil disease transmission is greatly reduced, and the soil fertility is greatly improved. The microbial activity can further repair the soil and improve the stability of the soil.

[0022] The soil repair agent prepared in the application can not only increase the total porosity of soil, improve the soil water stable aggregate, and improve the soil structure, but also improve the soil fertility, improve the soil pH value, passivate heavy metal ions, so that the repaired soil can adapt to the needs of plant growth, the sludge and traditional Chinese medicine residues are resourceized and utilized, waste is turned into treasure, and has a wide application prospect. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the application will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0024] Azotobacter, ATCC9046, brown azotobacter, 100 billion cfu / g; oxalic acid mold, ATCC10476, oxalic acid penicillium, 200 billion cfu / g; Bacillus subtilis, ATCC6633, 200 billion cfu / g; Trichoderma harzianum, ATCC52310, 100 billion cfu / g.

[0025] Urease, 1000U / g; phosphatase, acid phosphatase, 400U / g; catalase, 2000U / g; cellulase, 10,000U / g.

[0026] Graphene oxide, carbon content: 60-65%, sheet size: 10-15μm, number of layers: 1-2.

[0027] Preparation Example 1 Preparation of modified sludge

[0028] The method comprises the following steps: S1. Preparation of modified silicon oxide: dissolving 10 g of tetraethyl orthosilicate in 100 g of ethanol, adding 15 g of hydrochloric acid and 7 g of water, stirring and reacting for 7 h, drying, and calcining at 400° C. for 2 h to obtain a solid; adding 10 g of the solid to 100 mL of Tris-HCl solution with a pH of 8.5, adding 3 g of tannic acid, heating to 35° C., stirring and reacting for 2 h, filtering, washing, and drying to obtain modified silicon oxide; S2. Preparation of graphene oxide / chitosan-modified silicon oxide composite: adding 10 g of modified silicon oxide to 200 mL of 2 wt% acetic acid solution, adding 2 g of N-hydroxysuccinimide and 1 g of 1-Ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride was stirred and activated for 30 minutes. 12g of chitosan was added and stirred for 10 hours. 3g of graphene oxide was added and stirred for 2 hours. The mixture was then spray-dried to obtain a graphene oxide / chitosan-modified silica composite. S3. Preparation of a nano-Fe / Ni@graphene oxide / chitosan-modified silica composite: 8g of the graphene oxide / chitosan-modified silica composite was added to 150mL of water. Under nitrogen, 1.2g of ferric nitrate and 0.7g of nickel nitrate were added and stirred for 10 minutes. 20mL of an aqueous solution containing 1.8g of sodium borohydride was added dropwise and stirred for 30 minutes. The mixture was centrifuged, washed, and dried to obtain a nano-Fe / Ni@graphene oxide / chitosan-modified silica composite. S4. Preparation of modified nano-Fe / Ni@graphene oxide / chitosan-modified silica composite: 10 g of nano-Fe / Ni@graphene oxide / chitosan-modified silica composite was added to 100 mL of ethanol, 1 g of a silane coupling agent with a mercapto group was added, the mixture was heated to 45°C, stirred for 2 h, centrifuged, washed, and dried to obtain a modified nano-Fe / Ni@graphene oxide / chitosan-modified silica composite. S5. Preparation of modified sludge: 10 g of riverbed sludge and 3 g of traditional Chinese medicine residue were mixed evenly, dried, ground, and stirred with 7 g of modified nano-Fe / Ni@graphene oxide / chitosan-modified silica composite for 20 min. The mixture was then soaked in 100 g of nutrient solution, and the solvent was evaporated to obtain modified sludge.

[0029] The ratio of the nutrient solution is: glucose 7g / L, fructose 6g / L, urea 8g / L, sodium chloride 1g / L, and calcium chloride 0.5g / L.

[0030] Preparation of modified sludge

[0031] comprising the following steps: S1. Preparation of modified silicon oxide: 12 g of tetraethyl orthosilicate is dissolved in 150 g of ethanol, 20 g of hydrochloric acid and 10 g of water are added, the reaction is stirred for 10 h, dried, calcined at 500°C for 3 h, 10 g of solid is added to 100 mL of Tris-HCl solution with pH=9.5, 4 g of tannic acid is added, heated to 45°C, stirred for 4 h, filtered, washed, dried, and modified silicon oxide is prepared; S2. Preparation of graphene oxide / chitosan-modified silicon oxide composite: 10 g of modified silicon oxide is added to 200 mL of 2 wt% acetic acid solution, 3 g of N-hydroxysuccinimide and 3 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride are added, stirred for 30 min, 15 g of chitosan is added, stirred for 10 h, 5 g of graphene oxide is added, stirred for 2 h, and the graphene oxide / chitosan-modified silicon oxide composite is prepared by spray drying; S3. Preparation of nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite: 10 g of graphene oxide / chitosan-modified silicon oxide composite is added to 150 mL of water, 1.4 g of iron sulfate and 1 g of nickel sulfate are added under nitrogen protection, stirred for 10 min, 20 mL of aqueous solution containing 2.2 g of sodium borohydride is added dropwise, stirred for 30 min, centrifuged, washed, dried, and the nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite is prepared; S4. Preparation of modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite: 10 g of nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite is added to 100 mL of ethanol, 2 g of thiol-containing silane coupling agent is added, heated to 55°C, stirred for 4 h, centrifuged, washed, dried, and the modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite is prepared; S5. Preparation of modified sludge: 15 g of river bottom sludge and 5 g of traditional Chinese medicine residue are mixed uniformly, dried, ground, stirred with 10 g of modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite for 20 min, soaked in 100 g of nutrient solution, and the solvent is evaporated to prepare the modified sludge.

[0032] The ratio of the nutrient solution is: glucose 7 g / L, fructose 6 g / L, urea 8 g / L, sodium chloride 1 g / L, calcium chloride 0.5 g / L.

[0033] Preparation of modified sludge

[0034] comprising the following steps: S1. Preparation of modified silicon oxide: 11 g of tetraethyl orthosilicate is dissolved in 125 g of ethanol, 17 g of hydrochloric acid and 8 g of water are added, the reaction is stirred for 8 h, dried, calcined at 450℃ for 2.5 h to obtain a solid, 10 g of the solid is added to 100 mL of Tris-HCl solution with pH = 9, 3.5 g of tannic acid is added, heated to 40℃, stirred for 3 h, filtered, washed, dried to obtain modified silicon oxide; S2. Preparation of graphene oxide / chitosan-modified silicon oxide composite: 10 g of modified silicon oxide is added to 200 mL of 2 wt% acetic acid solution, 2.5 g of N-hydroxysuccinimide and 2 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride are added, stirred for 30 min, 13 g of chitosan is added, stirred for 10 h, 4 g of graphene oxide is added, stirred for 2 h, spray dried to obtain graphene oxide / chitosan-modified silicon oxide composite; S3. Preparation of nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite: 9 g of graphene oxide / chitosan-modified silicon oxide composite is added to 150 mL of water, 1.3 g of iron chloride and 0.8 g of nickel chloride are added under nitrogen protection, stirred for 10 min, 20 mL of aqueous solution containing 2 g of sodium borohydride is added dropwise, stirred for 30 min, centrifuged, washed, dried to obtain nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite; S4. Preparation of modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite: 10 g of nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite is added to 100 mL of ethanol, 1.5 g of silane coupling agent with mercapto is added, heated to 50℃, stirred for 3 h, centrifuged, washed, dried to obtain modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite; S5. Preparation of modified silt: 12 g of river bottom silt and 4 g of traditional Chinese medicine residue are mixed uniformly, dried, ground, stirred with 8 g of modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite for 20 min, soaked in 100 g of nutrient solution, the solvent is evaporated to obtain modified silt.

[0035] The ratio of the nutrient solution is: glucose 7 g / L, fructose 6 g / L, urea 8 g / L, sodium chloride 1 g / L, calcium chloride 0.5 g / L.

[0036] Comparative Preparation Example 1

[0037] Compared with Preparation Example 3, the difference is that tannic acid modification is not carried out in step S1.

[0038] Specifically as follows: S1. Preparation of silicon oxide: 11 g of tetraethyl orthosilicate is dissolved in 125 g of ethanol, 17 g of hydrochloric acid and 8 g of water are added, the reaction is stirred for 8 h, dried, calcined at 450℃ for 2.5 h to obtain a solid, which is silicon oxide.

[0039] Comparative Preparation Example 2

[0040] The difference compared with Preparation Example 3 is that no chitosan is added in step S2.

[0041] Specifically as follows: S2. Preparation of graphene oxide-modified silica composite: 10 g of modified silica is added to 200 mL of water, 4 g of graphene oxide is added, stirring for 2 h, spray drying to obtain graphene oxide-modified silica composite.

[0042] Comparative Preparation Example 3

[0043] The difference compared with Preparation Example 3 is that no graphene oxide is added in step S2.

[0044] Specifically as follows: S2. Preparation of chitosan-modified silica composite: 10 g of modified silica is added to 200 mL of 2 wt% acetic acid solution, 2.5 g of N-hydroxysuccinimide and 2 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride are added, stirring for 30 min of activation, 13 g of chitosan is added, stirring for 10 h of reaction, centrifugation, washing, drying to obtain chitosan-modified silica composite.

[0045] Comparative Preparation Example 4

[0046] The difference compared with Preparation Example 3 is that no iron chloride is added in step S3.

[0047] Specifically as follows: S3. Preparation of nano Ni@graphene oxide / chitosan-modified silica composite: 9 g of graphene oxide / chitosan-modified silica composite is added to 150 mL of water, 2.1 g of nickel chloride is added under nitrogen protection, stirring for 10 min of mixing, 20 mL of aqueous solution containing 2 g of sodium borohydride is added dropwise, stirring for 30 min of reaction, centrifugation, washing, drying to obtain nano Ni@graphene oxide / chitosan-modified silica composite.

[0048] Comparative Preparation Example 5

[0049] The difference compared with Preparation Example 3 is that no nickel chloride is added in step S3.

[0050] Specifically as follows: S3. Preparation of nano Fe@graphene oxide / chitosan-modified silica composite: 9 g of graphene oxide / chitosan-modified silica composite is added to 150 mL of water, 2.1 g of iron chloride is added under nitrogen protection, stirring for 10 min of mixing, 20 mL of aqueous solution containing 2 g of sodium borohydride is added dropwise, stirring for 30 min of reaction, centrifugation, washing, drying to obtain nano Fe@graphene oxide / chitosan-modified silica composite.

[0051] Comparative Preparation Example 6

[0052] The difference compared with Preparation Example 3 is that step S4 is not performed.

[0053] S1. Preparation of modified silica: 11 g of tetraethyl orthosilicate was dissolved in 125 g of ethanol, 17 g of hydrochloric acid and 8 g of water were added, and the reaction was stirred for 8 h, dried, calcined at 450℃ for 2.5 h to obtain a solid, 10 g of the solid was added to 100 mL of Tris-HCl solution with pH=9, 3.5 g of tannic acid was added, heated to 40℃, stirred for 3 h, filtered, washed, and dried to obtain the modified silica; S2. Preparation of chitosan-modified silica composite: 10 g of modified silica was added to 200 mL of 2wt% acetic acid solution, 2.5 g of N-hydroxysuccinimide and 2 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride were added, and the mixture was stirred for 30 min to activate, then 13 g of chitosan was added, and the mixture was stirred for 10 h, 4 g of graphene oxide was added, and the mixture was stirred for 2 h, and then spray dried to obtain the graphene oxide / chitosan-modified silica composite; S3. Preparation of nano Fe / Ni@graphene oxide / chitosan-modified silica composite: 9 g of graphene oxide / chitosan-modified silica composite was added to 150 mL of water, and 1.3 g of iron chloride and 0.8 g of nickel chloride were added under nitrogen protection, and the mixture was stirred for 10 min, then 20 mL of aqueous solution containing 2 g of sodium borohydride was added dropwise, and the mixture was stirred for 30 min, then centrifuged, washed, and dried to obtain the nano Fe / Ni@graphene oxide / chitosan-modified silica composite; S4. Preparation of modified silt: 12 g of river bottom silt and 4 g of traditional Chinese medicine residue were mixed uniformly, dried, ground, and stirred with 8 g of nano Fe / Ni@graphene oxide / chitosan-modified silica composite for 20 min, then soaked in 100 g of nutrient solution, and the solvent was evaporated to obtain the modified silt.

[0054] Comparative Preparation Example 7

[0055] The difference compared with Preparation Example 3 is that no modified nano Fe / Ni@graphene oxide / chitosan-modified silica composite is added in step S5.

[0056] Specifically as follows: S5. Preparation of modified silt: 12 g of river bottom silt and 4 g of traditional Chinese medicine residue were mixed uniformly, dried, ground, and soaked in 100 g of nutrient solution, and the solvent was evaporated to obtain the modified silt.

[0057] The ratio of the nutrient solution is: glucose 7 g / L, fructose 6 g / L, urea 8 g / L, sodium chloride 1 g / L, and calcium chloride 0.5 g / L.

[0058] Preparation Example 4 Preparation of bioactive ingredients

[0059] comprising the following steps: T1. adding 2 g of nitrogen-fixing bacteria, 1 g of oxalic acid mold, 4 g of Bacillus subtilis, and 2 g of Trichoderma harzianum into 100 mL of nutrient solution, stirring and mixing for 10 min to prepare a bacterial suspension; the nutrient solution is prepared as follows: adding 10 g of glucose, 3 g of fructose, 8 g of ammonium nitrate, 2 g of sodium chloride, 0.5 g of magnesium sulfate, 0.2 g of zinc sulfate, and 0.1 g of ferric chloride into 200 mL of water, stirring and mixing for 15 min to prepare the nutrient solution; T2. adding 1 g of urease, 0.5 g of phosphatase, 0.3 g of catalase, and 0.2 g of cellulase into 50 mL of water, stirring and mixing for 10 min to prepare an enzyme solution; T3. adding 10 g of diatomite into a Tris-HCl solution with a pH value of 8.5, adding 2 g of tannic acid, heating to 40℃, stirring and reacting for 2 h, filtering, washing, and drying to prepare modified diatomite; T4. adding 10 g of modified diatomite into 200 mL of 2wt% acetic acid solution, adding 2 g of N-hydroxy succinimide and 1 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, stirring and activating for 30 min, adding 5 g of chitosan, stirring and reacting for 10 h, filtering, washing, and drying to prepare a chitosan-diatomite composite; T5. stirring and mixing 10 g of the bacterial suspension and 3 g of the enzyme solution for 10 min, adding 5 g of the chitosan-diatomite composite, and evaporating the solvent to prepare a bioactive ingredient.

[0060] Preparation Example 5 Preparation of a bioactive ingredient

[0061] The method comprises the following steps: T1. 3 g of azotobacter, 2 g of oxalic acid mold, 7 g of bacillus subtilis, and 3 g of trichoderma harzianum are added into 100 mL of nutrient solution, and stirred and mixed for 10 min to prepare a bacterial suspension; the preparation method of the nutrient solution is as follows: 10 g of glucose, 3 g of fructose, 8 g of ammonium nitrate, 2 g of sodium chloride, 0.5 g of magnesium sulfate, 0.2 g of zinc sulfate, and 0.1 g of ferric chloride are added into 200 mL of water, and stirred and mixed for 15 min to prepare the nutrient solution; T2. 2 g of urease, 1 g of phosphatase, 0.5 g of catalase, and 0.5 g of cellulase are added into 50 mL of water, and stirred and mixed for 10 min to prepare an enzyme solution; T3. 10 g of diatomite is added into a Tris-HCl solution with a pH value of 9.5, 3 g of tannic acid is added, heated to 50 DEG C, stirred and reacted for 4 h, filtered, washed, and dried to prepare modified diatomite; T4. 10 g of modified diatomite is added into 200 mL of 2wt% acetic acid solution, 3 g of N-hydroxy succinimide and 2 g of 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride are added, stirred and activated for 30 min, 7 g of chitosan is added, stirred and reacted for 12 h, filtered, washed, and dried to prepare a chitosan-diatomic compound; T5. 10 g of the bacterial suspension and 5 g of the enzyme solution are stirred and mixed for 10 min, 7 g of the chitosan-diatomic compound is added, and the solvent is evaporated to prepare a bioactive ingredient.

[0062] Preparation example 6 Preparation of a bioactive ingredient

[0063] The method comprises the following steps: T1. adding 2.5 g of nitrogen-fixing bacteria, 1.5 g of oxalic acid mold, 5.5 g of Bacillus subtilis, and 2.5 g of Trichoderma harzianum to 100 mL of nutrient solution and stirring for 10 minutes to prepare a bacterial suspension; the nutrient solution is prepared by adding 10 g of glucose, 3 g of fructose, 8 g of ammonium nitrate, 2 g of sodium chloride, 0.5 g of magnesium sulfate, 0.2 g of zinc sulfate, and 0.1 g of ferric chloride to 200 mL of water and stirring for 15 minutes to prepare a nutrient solution; T2. adding 1.5 g of urease, 0.7 g of phosphatase, 0.4 g of catalase, and 0.35 g of cellulase to 50 mL of water and stirring for 10 minutes to prepare an enzyme solution; T3. adding 10 g of diatomaceous earth to a Tris-HCl solution with a pH of 9, adding 2.5 g of tannic acid, heating to 45°C, stirring for 3 hours, filtering, washing, and drying to prepare a modified diatomaceous earth; and T4. 10 g of modified diatomaceous earth was added to 200 mL of 2 wt% acetic acid solution, along with 2.5 g of N-hydroxysuccinimide and 1.5 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride. The mixture was stirred and activated for 30 minutes. 6 g of chitosan was then added and stirred for 11 hours. The mixture was filtered, washed, and dried to obtain a chitosan-diatomaceous earth complex. T5. 10 g of the bacterial suspension and 4 g of the enzyme solution were stirred for 10 minutes. 6 g of the chitosan-diatomaceous earth complex was then added, and the solvent was evaporated to obtain the bioactive component.

[0064] Comparative Preparation Example 8

[0065] Compared with Preparation Example 6, the difference is that steps T3 and T4 are not performed.

[0066] Specifically as follows: T1. Add 2.5g of nitrogen-fixing bacteria, 1.5g of oxalic acid mold, 5.5g of Bacillus subtilis, and 2.5g of Trichoderma harzianum to 100mL of nutrient solution, stir and mix for 10 minutes to prepare a bacterial suspension; the preparation method of the nutrient solution is as follows: add 10g of glucose, 3g of fructose, 8g of ammonium nitrate, 2g of sodium chloride, 0.5g of magnesium sulfate, 0.2g of zinc sulfate, and 0.1g of ferric chloride to 200mL of water, stir and mix for 15 minutes to prepare a nutrient solution; T2. Add 1.5g of urease, 0.7g of phosphatase, 0.4g of catalase, and 0.35g of cellulase to 50mL of water, stir and mix for 10 minutes to prepare an enzyme solution; T3. Stir and mix 10g of the bacterial suspension and 4g of the enzyme solution for 10 minutes, evaporate the solvent, and prepare the bioactive component.

[0067] Comparative Preparation Example 9

[0068] Compared with Preparation Example 6, the difference is that no bacterial suspension is added in step T5.

[0069] Specifically as follows: T5. 6 g of chitosan-diatomite compound is added to 14 g of enzyme solution, and the solvent is evaporated to obtain the bioactive ingredient.

[0070] Comparative Preparation Example 10

[0071] Compared with Preparation Example 6, the difference is that no enzyme solution is added in step T5.

[0072] Specifically as follows: T5. 6 g of chitosan-diatomite compound is added to 14 g of enzyme solution, and the solvent is evaporated to obtain the bioactive ingredient.

[0073] Example 1

[0074] In this example, a soil remediation modifier is prepared by mixing 40 parts by weight of the modified silt obtained in Preparation Example 1, 10 parts by weight of humic acid, 5 parts by weight of the bioactive ingredient obtained in Preparation Example 4, 10 parts by weight of sodium silicate, and 10 parts by weight of lignin for 15 minutes to obtain the soil remediation modifier.

[0075] Example 2

[0076] In this example, a soil remediation modifier is prepared by mixing 50 parts by weight of the modified silt obtained in Preparation Example 2, 15 parts by weight of humic acid, 10 parts by weight of the bioactive ingredient obtained in Preparation Example 5, 15 parts by weight of calcium carbonate, and 15 parts by weight of cellulose for 15 minutes to obtain the soil remediation modifier.

[0077] Example 3

[0078] In this example, a soil remediation modifier is prepared by mixing 45 parts by weight of the modified silt obtained in Preparation Example 3, 12 parts by weight of humic acid, 7 parts by weight of the bioactive ingredient obtained in Preparation Example 6, 6 parts by weight of potassium silicate, 6 parts by weight of calcium carbonate, and 12 parts by weight of cellulose for 15 minutes to obtain the soil remediation modifier.

[0079] Comparative Example 1

[0080] Compared with Example 3, the difference is that the modified silt is obtained in Comparative Preparation Example 1.

[0081] Comparative Example 2

[0082] Compared with Example 3, the difference is that the modified silt is obtained in Comparative Preparation Example 2.

[0083] Comparative Example 3

[0084] Compared with Example 3, the difference is that the modified silt is obtained in Comparative Preparation Example 3.

[0085] Comparative Example 4

[0086] The difference compared with Example 3 is that the modified silt is prepared from Comparative Preparation Example 4.

[0087] Comparative Example 5

[0088] The difference compared with Example 3 is that the modified silt is prepared from Comparative Preparation Example 5.

[0089] Comparative Example 6

[0090] The difference compared with Example 3 is that the modified silt is prepared from Comparative Preparation Example 6.

[0091] Comparative Example 7

[0092] The difference compared with Example 3 is that the modified silt is prepared from Comparative Preparation Example 7.

[0093] Comparative Example 8

[0094] The difference compared with Example 3 is that the bioactive ingredient is prepared from Comparative Preparation Example 8.

[0095] Comparative Example 9

[0096] The difference compared with Example 3 is that the bioactive ingredient is prepared from Comparative Preparation Example 9.

[0097] Comparative Example 10

[0098] The difference compared with Example 3 is that the bioactive ingredient is prepared from Comparative Preparation Example 10.

[0099] Comparative Example 11

[0100] The difference compared with Example 3 is that no modified silt is added.

[0101] Comparative Example 12

[0102] The difference compared with Example 3 is that no bioactive ingredient is added.

[0103] The soil to be repaired in the following examples is collected from a low-fertility sandy soil plot in the Huang-Huai-Hai Plain. The soil sample is air-dried before the test, sieved through a 24-mesh sieve, and impurities such as plant roots and small stones are removed.

[0104] Example 4

[0105] This embodiment provides a soil remediation and maintenance method, comprising the following steps: (1) first, digging holes in the soil to be remediated, with 10 holes per square meter and a depth of 10 cm, and drying and dredging the soil for 2 days; (2) evenly applying the soil remediation and improvement agent prepared in Example 1 to the holes, applying an amount of 10 g / kg, stirring and mixing evenly, and treating for 1 month; (3) detecting the organic matter, heavy metal ion content and pH value in the soil, and completing the soil remediation if they are within the safe value range; (4) evenly applying the soil remediation and improvement agent to the soil, applying an amount of 2 g / kg, stirring and mixing evenly, and repeating the application every 6 months to complete the soil maintenance.

[0106] Example 5

[0107] This embodiment provides a soil remediation and maintenance method, comprising the following steps: (1) first, digging holes in the soil to be remediated, with 10 holes per square meter and a depth of 10 cm, and drying and dredging the soil for 2 days; (2) evenly applying the soil remediation and improvement agent prepared in Example 2 to the holes, applying an amount of 10 g / kg, stirring and mixing evenly, and treating for 1 month; (3) detecting the organic matter, heavy metal ion content and pH value in the soil, and completing the soil remediation if they are within the safe value range; (4) evenly applying the soil remediation and improvement agent to the soil, applying an amount of 2 g / kg, stirring and mixing evenly, and repeating the application every 6 months to complete the soil maintenance.

[0108] Example 6

[0109] This embodiment provides a soil remediation and maintenance method, comprising the following steps: (1) first, digging holes in the soil to be remediated, with 10 holes per square meter and a depth of 10 cm, and drying and dredging the soil for 2 days; (2) evenly applying the soil remediation and improvement agent prepared in Example 3 to the holes, applying an amount of 10 g / kg, stirring and mixing evenly, and treating for 1 month; (3) detecting the organic matter, heavy metal ion content and pH value in the soil, and completing the soil remediation if they are within the safe value range; (4) evenly applying the soil remediation and improvement agent to the soil, applying an amount of 2 g / kg, stirring and mixing evenly, and repeating the application every 6 months to complete the soil maintenance.

[0110] Comparative Example 13

[0111] Compared with Example 6, the difference is that the soil remediation improver is prepared by Comparative Example 1.

[0112] Comparative Example 14

[0113] Compared with Example 6, the difference is that the soil remediation improver is prepared by Comparative Example 2.

[0114] Comparative Example 15

[0115] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 3.

[0116] Comparative Example 16

[0117] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 4.

[0118] Comparative Example 17

[0119] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 5.

[0120] Comparative Example 18

[0121] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 6.

[0122] Comparative Example 19

[0123] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 7.

[0124] Comparative Example 20

[0125] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 8.

[0126] Comparative Example 21

[0127] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 9.

[0128] Comparative Example 22

[0129] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 10.

[0130] Comparative Example 23

[0131] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 11.

[0132] Comparative Example 24

[0133] The difference compared with Example 6 is that the soil remediation improver is prepared from Comparative Example 12.

[0134] Test Example 1

[0135] The soil remediated in Examples 4-6 and Comparative Examples 13-24 is detected and compared with the original soil, and various indexes are determined, and the results are shown in Table 1 and Table 2.

[0136] 2,4-dichlorophenol removal amount (mg / m 2) = the content of 2,4-dichlorophenol in the original soil - the content of 2,4-dichlorophenol in the soil after remediation

[0137] Table 1

[0138]

[0139] Table 2

[0140]

[0141] From the above table, it can be seen that the soil remediation improver prepared in Examples 1-3, after being added into the soil and remediated by the method of Examples 4-6, the remediated soil can obviously improve the soil quality, adjust the pH value of the soil, improve the soil fertility, adjust the bacterial flora and passivate the heavy metal ions in the soil.

[0142] The above description is merely preferred embodiments of the present application, but not to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A soil remediation amendment, characterized in that, Prepared from the following raw materials by weight parts: modified sludge 40-50 parts, humic acid 10-15 parts, bioactive ingredients 5-10 parts, inorganic ingredients 10-15 parts, organic ingredients 10-15 parts; the inorganic ingredients are selected from at least one of sodium silicate, potassium silicate, calcium carbonate, bentonite, montmorillonite, diatomite, and the organic ingredients are selected from at least one of chitosan, lignin, cellulose, hemicellulose; the preparation method of the modified sludge is as follows: S1. Preparation of modified silicon oxide: tetraethyl orthosilicate is dissolved in ethanol, hydrochloric acid and water are added, stirring reaction, drying, calcination, solid is added to Tris-HCl solution and tannic acid, heating stirring reaction, filtration, washing, drying, to obtain modified silicon oxide; S2. Preparation of graphene oxide / chitosan-modified silicon oxide composite: modified silicon oxide is added to acetic acid solution, N-hydroxy succinimide and 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride are added, stirring activation, chitosan is added, stirring reaction, graphene oxide is added, stirring reaction, spray drying, to obtain graphene oxide / chitosan-modified silicon oxide composite; S3. Preparation of nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite: graphene oxide / chitosan-modified silicon oxide composite is added to water, under the protection of inert gas, iron salt and nickel salt are added, after stirring and mixing uniformly, sodium borohydride solution is added dropwise, stirring reaction, centrifugation, washing, drying, to obtain nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite; S4. Preparation of modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite: nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite is added to ethanol, silane coupling agent with mercapto is added, heating stirring reaction, centrifugation, washing, drying, to obtain modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite; S5. Preparation of modified sludge: river bottom sludge and traditional Chinese medicine residues are mixed uniformly, dried, ground, mixed uniformly with modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite, soaked in nutrient solution, solvent is evaporated, to obtain modified sludge; the preparation method of the bioactive ingredients is as follows: T1. Nitrogen-fixing bacteria, oxalic acid fungi, bacillus subtilis, and trichoderma harzianum are added to nutrient solution, to obtain bacterial suspension; T2. Urease, phosphatase, catalase, and cellulase are added to water, to obtain enzyme solution; T3. Diatomite is added to Tris-HCl solution, tannic acid is added, heating stirring reaction, filtration, washing, drying, to obtain modified diatomite; T4. Modified diatomite is added to acetic acid solution, N-hydroxy succinimide and 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride are added, stirring activation, chitosan is added, stirring reaction, filtration, washing, drying, to obtain chitosan-diatomite composite; T5. Bacterial suspension and enzyme solution are mixed uniformly, chitosan-diatomite composite is added, solvent is evaporated, to obtain bioactive ingredients.

2. The soil remediation amendment of claim 1, wherein, The mass ratio of tetraethyl orthosilicate, ethanol, hydrochloric acid and water in step S1 is 10-12:100-150:15-20:7-10, the stirring reaction time is 7-10h, the calcination temperature is 400-500℃, the time is 2-3h, the mass ratio of the solid and tannic acid is 10:3-4, the pH value of the Tris-HCl solution is 8.5-9.5, the heating and stirring reaction temperature is 35-45℃, and the time is 2-4h; the mass ratio of the modified silicon oxide, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride, chitosan and graphene oxide in step S2 is 10:2-3:1-3:12-15:3-5.

3. The soil remediation amendment of claim 1, wherein, The mass ratio of the graphene oxide / chitosan-modified silicon oxide composite, iron salt, nickel salt and sodium borohydride in step S3 is 8-10: 1.2-1.4:0.7-1:1.8-2.2, the iron salt is selected from at least one of ferric chloride, ferric sulfate, ferric nitrate, the nickel salt is selected from at least one of nickel chloride, nickel sulfate, nickel nitrate; the mass ratio of the nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite and the silane coupling agent with thiol group in step S4 is 10:1-2, the silane coupling agent with thiol group is selected from at least one of KH580, KH590, the heating and stirring reaction temperature is 45-55℃, and the time is 2-4h.

4. The soil remediation amendment of claim 1, wherein, The mass ratio of the river bottom sludge, traditional Chinese medicine residue, modified nano Fe / Ni@graphene oxide / chitosan-modified silicon oxide composite and nutrient solution in step S5 is 10-15:3-5:7-10:100, the ratio of the nutrient solution is: carbon source 10-15g / L, nitrogen source 7-10g / L, inorganic salt 1-2g / L, the carbon source is selected from at least one of glucose, fructose, sucrose, citric acid, the nitrogen source is selected from at least one of urea, ammonium nitrate, ammonium phosphate, fish meal, and the inorganic salt is selected from at least one of sodium chloride, potassium chloride, magnesium sulfate, manganese sulfate, zinc sulfate, calcium chloride.

5. The soil remediation amendment of claim 1, wherein, The mass ratio of the nitrogen-fixing bacteria, oxalic acid mold, bacillus subtilis and trichoderma harzianum in step T1 is 2-3:1-2:4-7:2-3; the mass ratio of the urease, phosphatase, catalase, cellulase and water in step T2 is 1-2:0.5-1:0.3-0.5:0.2-0.5:50; the pH value of the Tris-HCl solution in step T3 is 8.5-9.5, the mass ratio of the diatomite and tannic acid is 10:2-3, the heating and stirring reaction temperature is 40-50℃, and the time is 2-4h; the mass ratio of the modified diatomite, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl) carbodiimide hydrochloride and chitosan in step T4 is 10:2-3:1-2:5-7; the mass ratio of the bacterial suspension, enzyme solution and chitosan-diatomite composite in step T5 is 10:3-5:5-7.

6. A method of soil remediation, characterized by, It comprises the following steps: (1) firstly dig a plurality of holes in the soil to be repaired, and pre-treat the soil by drying and dredging; (2) uniformly apply the soil repair modifier according to any one of claims 1-5 in the holes, and mix uniformly by turning and stirring; (3) detect the content of organic matter, heavy metal ions and pH value in the soil, and complete the soil repair when the values are within the safety range.

7. A soil maintenance method characterized by, It comprises the following steps: uniformly apply the soil repair modifier according to any one of claims 1-5 in the soil, and mix uniformly by turning and stirring, and repeat the application every 6-12 months to complete the soil maintenance.

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