Soil pollution prevention and treatment agent and application thereof in soil pollution assessment and remediation of construction land

Abstract

The invention discloses a soil pollution prevention treatment agent and application thereof in construction land soil pollution assessment and remediation, the treatment agent is a dry weight formula, and the treatment agent comprises the following components by mass: 40-60% of charcoal / activated carbon; 5-15% of film-forming agents such as sodium alginate and hydroxyethyl cellulose; 5-30% of a high-molecular polymer emulsion; 2-4% of a chelating agent (EDDS, a sub-exogenous organic chelating agent); 2-4% of nano iron oxide (Fe2O3 / Fe3O4 and the like) or nano oxide; 10-20% of clay modified filler such as bentonite / montmorillonite and the like; 1% of a microbial preparation (a beneficial microorganism mixture); 4-6% of silicate modified powder / mineral powder (such as dihydrate silicate, zeolite and the like); and 2-4% of other auxiliary components (humic acid / slow-release carrier and the like). The synergistic control of heavy metals and organic pollutants is realized, the physical and chemical properties of soil are improved, the microbial activity is recovered, and the plant growth is promoted.

Description

TECHNICAL FIELD

[0001] The present application relates to a soil pollution prevention and treatment agent and a preparation method thereof, and is especially suitable for application in soil pollution assessment and remediation of construction land. BACKGROUND

[0002] In the soil pollution assessment and remediation of construction land, common pollutants include heavy metals (such as lead, cadmium, chromium, etc.), organic pollutants (such as polycyclic aromatic hydrocarbons, volatile organic compounds, etc.) and their migration and diffusion risks. The existing remediation technologies are mainly single physical, chemical or biological treatment, which has the following disadvantages: poor adaptability to multi-component pollution scenes, great damage to soil microbial environment, high initial investment, long remediation period and potential risks to subsequent land reuse. Therefore, it is urgent to develop a soil pollution prevention and treatment agent with combined effect, compatibility to multiple pollutants, on-site application and long-term ecological benefits and a preparation process thereof.

[0003] Current construction land often suffers from multiple pollution loads (such as heavy metals, petroleum, organic pollutants, etc.) during development and reconstruction. Traditional treatment methods are either costly or have high risk of secondary environmental pollution.

[0004] Existing remediation strategies are mainly single approaches such as physical isolation, chemical stabilization and microbial degradation, which are difficult to balance treatment effect, sustainability and ecological friendliness.

[0005] Therefore, it is urgent to develop a soil pollution prevention and treatment agent with multi-component synergistic effect, which has wide applicability, good stability, strong operability, is friendly to on-site construction, and can improve soil microbial activity, improve nutrient and water conditions and reduce the migration of pollutants during remediation. SUMMARY

[0006] The present application aims to overcome the defects of the prior art and provide a soil pollution prevention and treatment agent and a preparation method thereof, which can realize the fixation / degradation of pollutants, improve soil physical and chemical properties and enhance microbial activity through multi-component synergistic effect, thereby improving the efficiency and sustainability of soil pollution assessment and remediation of construction land.

[0007] By stabilizing soil nutrients and microbial environment, reducing the bioavailability of heavy metals and organic pollutants and improving soil ecological function, comprehensive treatment of contaminated soil of construction land is realized.

[0008] The purpose of the present application and the technical problems are realized by using the following technical solutions. According to the present application, a soil pollution prevention and treatment agent is provided, which contains, by dry weight, the following components by mass fraction: Biochar / activated carbon: 40-60%; Film-forming agents such as sodium alginate and hydroxyethyl cellulose: 5-15%; High molecular polymer emulsion: 5-30%; Chelating agent (EDDS, exogenous organic chelating agent): 2-4%; Nano-iron oxide (Fe2O3 / Fe3O4, etc.) or nano-oxide: 2-4%; Bentonite / montmorillonite and other clay modified fillers: 10-20%; Microbial preparation (beneficial microbial mixture): 1%; Silicate modified powder / mineral powder (such as dihydrate silicate, zeolite, etc.): 4-6%; Other auxiliary components (humic acid / slow-release carrier, etc.): 2-4%.

[0009] Further, the preparation process of the treatment agent comprises the following steps: Mixing the carrier material, adding the film-forming agent and polymer emulsion, adding the chelating agent and nano-oxide, adding the microbial preparation, and silicate powder, mixing in proportion, and low-temperature drying.

[0010] Further, the treatment agent as described above is a dry weight formula, comprising the following by mass fraction: Biochar / activated carbon: 50%; Film-forming agent such as sodium alginate: 10%; High molecular polymer emulsion: 10%; EDDS: 3%; Nano-iron oxide: 3%; Montmorillonite / bentonite: 15%; Microbial preparation: 1%; Silicate powder: 5%; Other auxiliary components: 3%; Its preparation process comprises the following steps: 1) Dry mixing of biochar and inorganic carriers such as montmorillonite at room temperature to ensure uniform particle size; 2) Prepare the film-forming agent solution: dissolve sodium alginate and other film-forming agents in water, adjust the pH to 6-7; 3) Slowly add the polymer emulsion to the carrier mixture to form a uniform slurry; 4) Add EDDS, nano-iron oxide, microbial preparation and silicate powder in proportion, continue to mix until there is no particle agglomeration; 5) Formed by extrusion, granulation or direct laying and drying, dried at room temperature or below 60°C to moisture ≤8%.

[0011] Further, the treatment agent as described above is a dry weight formula, comprising the following by mass fraction: Biochar / activated carbon: 55%; Film forming agent such as sodium alginate: 8%; Polymer emulsion: 11%; EDDS: 2%; Nano-iron oxide: 4%; Montmorillonite / bentonite: 10%; Microbial preparation: 1%; Silicate powder: 5%; Other auxiliary components: 4%; The preparation process thereof comprises the following steps: 1) Mix the biochar, montmorillonite and silicate powder to ensure uniform dispersion; 2) Pretreat and mix the film forming agent and polymer emulsion to obtain a binding phase; 3) Add EDDS, nano-iron oxide and microbial preparation and continue to mix evenly; 4) Granulate, shape and dry at low temperature to keep the humidity below 8%.

[0012] Further, the treatment agent as described above is a dry weight formula comprising, by mass fraction: Biochar / activated carbon: 60%; Polymer emulsion: 8%; Film forming agent such as sodium alginate: 7%; EDDS: 4%; Nano-iron oxide: 2%; Montmorillonite / bentonite: 12%; Microbial preparation: 1%; Silicate powder: 4%; Other auxiliary components: 2%; The preparation process thereof comprises the following steps: 1) Dry mix the biochar as the main body with clay materials to ensure particle dispersion; 2) Mix the film forming agent and polymer emulsion to form a uniform binding system; 3) Add active components such as EDDS and nano-iron oxide and mix evenly; 4) Form granular, particulate or block-shaped products and dry at low temperature to ensure stable particle size.

[0013] The application provides an application of the soil pollution prevention and treatment agent as described above in construction land soil pollution assessment and remediation.

[0014] By means of the above technical solution, the soil pollution prevention and treatment agent and its application have at least the following advantages: 1) The soil pollution prevention and treatment agent of the present application is based on adsorption-stabilization components, microbial activity enhancement components, nutrient supply components, and bonding and controlled release systems as the core, and is prepared into granular or shellable and on-site spreadable forms through a certain preparation process, so as to facilitate on-site construction and subsequent maintenance.

[0015] 2) The present application realizes the synergistic control of heavy metals and organic pollutants, improves the physical and chemical properties of soil, restores microbial activity, and promotes plant growth. 3) The formula design of the present application considers the synergistic effect of various components, emphasizes the adsorption, stabilization of heavy metals and organic pollutants, and the improvement of microbial activity; the preparation process is simple and suitable for on-site operation, the particle size is controlled at 3-8 mm, which is convenient for construction; the monitoring index and test data simulate the significant improvement of the treatment effect. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 is the preparation process flow chart of the soil pollution prevention and treatment agent of the present application. DETAILED DESCRIPTION

[0017] The present application discloses a soil pollution prevention and treatment agent and a preparation method thereof, and application in construction land soil pollution assessment and repair. The soil pollution prevention and treatment agent realizes the synergistic control of heavy metals and organic pollutants, improves the physical and chemical properties of soil, restores microbial activity, and promotes plant growth.

[0018] The dry weight formula composition and content of the soil pollution prevention and treatment agent for construction land application in the embodiment of the present application are as follows (unit: mass percentage, %): Biochar / activated carbon: 40-60%; Sodium alginate + hydroxyethyl cellulose and other film forming agents: 5-15%; High molecular polymer emulsion: 5-30%; Chelating agent (EDDS, exogenous organic chelating agent): 2-4%; Nanometer iron oxide (Fe2O3 / Fe3O4, etc.) or nanometer oxide: 2-4%; Bentonite / montmorillonite and other clay modified fillers: 10-20%; Microbial preparation (beneficial microorganism mixture): 1%; Silicate modified powder / mineral powder (such as dihydrate silicate, zeolite, etc.): 5-6%; Other auxiliary components (humic acid / slow-release carrier, etc.): 3%.

[0019] The processing agent of the present application constructs a soil improvement system with low permeability, controllable slow release and high adsorption-stabilization capacity through the synergistic effect of carriers such as biochar, film-forming agents, polymer emulsions and chelating agents, and has the functions of pollutant fixation, microbial habitat improvement and plant growth promotion.

[0020] The processing agent is suitable for construction land with multi-component pollution, and can realize on-site customized application through selective combination scheme according to different pollution spectrum.

[0021] As shown in Figure 1 The preparation process of the processing agent of the present application can be expressed as follows: Step A: raw material preparation; The adsorption materials such as biochar and zeolite are dried to a water content of ≤5%; The active microbial inoculant is subjected to necessary pretreatment (such as recovery from low-temperature dormancy period and biomass statistics) to ensure that the activity reaches the expected CFU / unit mass; Organic-inorganic nutrient salts, binders and controlled-release carriers are prepared.

[0022] Step B: dry mixing and wet mixing; The dry materials are preliminarily dry mixed according to the above-mentioned ratio to ensure uniform dispersion of each component; The water-based binder / carrier system is added, and moderate stirring is carried out to achieve uniform wetting, and finally the water content of the granulated material (such as 10-15%) is reached.

[0023] Step C: granulation / molding; Pelletization, extrusion granulation or digging granulation equipment is used for granulation, and the particle size can be controlled within 3-8 mm (convenient for field spreading and mixing).

[0024] Step D: drying and curing; The granules after granulation are dried to the target moisture content (usually ≤5%) in an environmental temperature or controlled temperature drying environment; Moderate curing (such as 8-14 days of placement time) is carried out to allow the inoculant to stabilize and plant in the carrier and gradually improve the activity.

[0025] Step E: packaging and quality control; Particle size distribution, moisture, inoculant activity (CFU / g), adsorption performance and other quality detection are carried out; Packaging, transportation and storage conditions in accordance with local / national environmental remediation standards.

[0026] The preparation process of the present application is simple and suitable for on-site preparation or local production, and the dried product has a long storage stability.

[0027] Method for use: Soil pretreatment: Basic characteristics analysis (pH, EC, organic matter, particle size distribution, total and extractable metal, organic pollutant spectrum, etc.) is performed on the contaminated soil before applying the treatment agent.

[0028] Application method: Turnover mixing, zonal and layered injection, laying and mixing, etc. can be used, combined with on-site equipment conditions (rotary tiller, bulldozer, mixer, etc.).

[0029] Water management: Maintaining a certain amount of water after application is beneficial to the interaction and slow-release process of components and soil.

[0030] Subsequent monitoring: Regular tracking monitoring of pollutant extractability, microbial activity, plant biomass, etc. should be performed to evaluate long-term effects.

[0031] The actual site pollution spectrum and soil physical and chemical properties can be adjusted within the above range as appropriate to achieve the treatment goal of different sites.

[0032] Among them, the formula components used in the embodiments of the present application are all commercially available products, which can be specifically expressed as follows: Biochar: wood / straw pyrolysis carbon, particle size 3-8mm, rich in pores, high activity; Polymer emulsion: acrylate emulsion, chitosan emulsion, yue polymer or other commonly used soil improvement emulsion; Nano Fe2O3: nano-Fe2O3, particle size 10-20nm, superfine, magnetic; Nano Fe3O4: nano-Fe3O4, particle size 10-20nm, superfine, magnetic; Microbial preparation: containing rhizosphere nitrogen-fixing bacteria, phenol oxidizing bacteria, bacillus, etc. CFU≥10 8 CFU / g; Silicate powder: natural or synthetic zeolite, particle size 2-5mm, excellent adsorption capacity.

[0033] Example 1 The dry weight formula composition and content of the soil pollution prevention and treatment agent of the embodiments of the present application are as follows (unit: mass percentage, %): Biochar (wood / straw pyrolysis carbon): 50%; Montmorillonite: 15%; Sodium alginate and hydroxyethyl cellulose are mixed in a ratio of 1:1 (film forming agent): 10%; Polymer emulsion (acrylate emulsion): 10%; EDDS (chelating agent): 3%; Nano Fe2O3: 3%; Microbial preparation (bacillus probiotic bacteria, CFU≥108 CFU / g): 1%; Silicate powder (synthetic zeolite): 5%; Other auxiliary (humic acid): 3%; Preparation process: 1) First, dry the biochar and montmorillonite at room temperature, and mix them evenly to have uniform particle size (particle size 3-8 mm); 2) Prepare a sodium alginate + hydroxyethyl cellulose film former solution, dissolve the two in water, and adjust the pH to 6.5; 3) Slowly add the polymer emulsion to the carrier mixture while stirring, forming a uniform slurry; 4) Gradually add the screened EDDS, nano Fe2O3, microbial preparation, and silicate powder, and continue to stir evenly to ensure no clumping; 5) Extrude the mixture into granules (particle size 3-8 mm), and place it in an environment at room temperature for natural drying, or in a low temperature (≤60°C) environment for drying until the moisture content is ≤8%; 6) Finally, seal and package, and store for later use after testing.

[0034] Applicable scenarios: Suitable for construction land surface to middle layer soil containing multiple pollutants, especially heavy metals and organic pollutants.

[0035] Example 2 The dry weight formula composition and content of the soil pollution prevention and treatment agent of the embodiment of the application are as follows (unit: mass percentage, %): Biochar (wood / straw pyrolysis carbon): 55%; Clay modified material (montmorillonite): 10%; Film former (sodium alginate, hydroxyethyl cellulose, etc. in a proportion of 8%); Polymer emulsion (chitosan emulsion): 11%; EDDS: 2%; Nano Fe3O4: 4%; Microbial preparation (containing rhizosphere nitrogen-fixing bacteria and other probiotics, CFU≥10 8 CFU / g): 1%; Silicate powder (synthetic zeolite): 5%; Other auxiliary (humic acid): 4%; Preparation process: 1) Dry the biochar and montmorillonite at room temperature, and mix them evenly; 2) Prepare a film former solution with uniform texture, add it to the carrier, and stir at medium speed to evenly moisten; 3) Gradually add EDDS, nano Fe3O4, microbial preparations, and silicate powder, stirring continuously to ensure thorough mixing; 4) Particles with a diameter of 3-8 mm are produced using extrusion or pelletizing equipment; 5) Air dry the finished product at room temperature or at low temperature until the moisture content is ≤8%, then seal and store for later use.

[0036] Applicable scenarios: Suitable for sites with high levels of pollution that require strong adsorption and slow release, and also has a certain biological promotion effect.

[0037] Example 3 The dry weight formulation and content of the soil pollution control agent according to embodiments of the present invention are as follows (unit: mass percentage, %): Biochar: 60%; Montmorillonite: 12%; Film-forming agent (sodium alginate and hydroxyethyl cellulose mixed in a 1:1 ratio): 7%; Polymer emulsion: 8%; EDDS: 4%; Nano Fe2O3: 2%; Microbial preparations: 1%; Silicate powder (zeolite / dihydrate silicate): 4%; Other auxiliary agents (humic acid): 2%; Preparation process: 1) Prioritize drying and uniformly mixing biochar and montmorillonite; 2) Prepare the film-forming agent solution, add it to the carrier, and stir until it is homogeneous and wetted; 3) Slowly add various active ingredients (EDDS, nano iron oxides, microorganisms, mineral powder) to ensure full dispersion; 4) Particles with a diameter of 3–8 mm are produced by extrusion or pelletizing machinery; 5) Dry in a dry environment (room temperature or low temperature) until the moisture content is ≤5%, then store in a sealed container.

[0038] Applicable scenarios: Primarily used in sites with high pollutant loads, where a pollutant interception layer and a long-term stable soil matrix need to be formed quickly.

[0039] Application Example 1 Remediation of construction land soil pollution assessment Site and pollutants: A construction site in a certain city has significant levels of heavy metals (Pb, Cd) in the topsoil and a wide range of organic pollutants.

[0040] Treatment agent dosage and method: Use 3-5% of the dry soil mass as the initial input, mix it into the soil to a depth of 5-15 cm during tillage, and add it in layers if necessary to ensure uniform mixing.

[0041] Procedure: Mix the soil using rotary tillers or pushers, then cover it to retain moisture, keeping the soil moisture between 15% and 25% for 4–6 weeks.

[0042] Monitoring indicators and assessment: Soil DTPA-extractable heavy metals, total organic carbon, microbial activity (dehydrogenase activity), pH and EC were measured at 30, 60 and 90 days.

[0043] Effects: It can reduce the content of extractable heavy metals, inhibit pollutant migration, improve microbial activity, and promote plant growth and ecological restoration.

[0044] Table 1 Soil monitoring indicators (30, 60, 90 days)

[0045] Application Example 2 Remediation of construction waste soil / excavated soil secondary use Site and pollutants: Construction waste soil, with a mixed pollution spectrum mainly consisting of heavy metals and some petroleum pollutants.

[0046] Dosage and method of treatment agent: Mix the treatment agent into the excavated soil at a dry weight of 3-4%, mix in different areas, and then temporarily stockpile and manage it under natural temperature and humidity control.

[0047] Operation: Use a wheeled soil turner / self-propelled fertilizer top dressing machine to mix the soil. Cover the soil for a short period after mixing to avoid dust. Irrigate and cover the soil as needed in the middle and later stages to maintain the micro-ecological environment.

[0048] Monitoring indicators and assessment: oil pollutant residues and heavy metal extractability.

[0049] Effects: Stabilizes pollutants, reduces potential risks to the surrounding environment, and enhances land reuse potential.

[0050] Table 2: Changes in pollution indicators of construction waste soil / excavated soil

[0051] The formulation components and contents of Comparative Examples 1-10 are shown in Table 3 below.

[0052] Table 3. Control group component formulation (mass percentage, %)

[0053] Preparation method: The carrier material is mixed, and film-forming agents and polymer emulsions, chelating agents and nano-oxides, microbial preparations and silicate powder are added. After mixing in proportion, the mixture is shaped and dried at low temperature.

[0054] Verification Test Example 1 Comparison of adsorption and stabilization capacity (soil column / isothermal adsorption experiment) Objective: To verify the enhancement of the adsorption and stabilization capabilities of the treatment agent components for metal ions such as Pb and Cd between individual components, mixed components, and the composition of the present invention.

[0055] Methods: Static isothermal adsorption was performed in standard soil, and the adsorption amounts of Pb and Cd were compared among the control (untreated), single-component treatment, two-component treatment, and three-component treatment (the composition of the present invention).

[0056] Key indicators: adsorption capacity (mg / g), metal ion release rate after surface modification, and re-adsorption capacity after reboiling.

[0057] result: Pb adsorption capacity: Control = 28 mg / g; Single-component treatment = 45 mg / g; Two-component treatment = 68 mg / g; Composition of the present invention = 110 mg / g, an increase of approximately 1.6–2.0 times; Cd adsorption capacity: Control = 12 mg / g; Single-component treatment = 20 mg / g; Two-component treatment = 35 mg / g; Composition of the present invention = 66 mg / g, an increase of approximately 1.9 times; Table 4. Pollutant adsorption capacity (mg / g) test

[0058] As shown in Table 4 above, the adsorption capacity increases with the complexity of the material and the synergistic effect. In particular, the adsorption effect of the composition of the present invention (Example 1) is significantly better than that of the comparative group. Data from other ratio groups show that the adsorption capacity is in the medium range, slightly higher than that of the comparative group, showing a gradual increasing trend. The composition of the present invention has a significantly better adsorption / stabilization effect on heavy metals than single-component and two-component combinations, exhibiting a significant synergistic effect.

[0059] Verification Test Example 2 Soil column leaching and migration inhibition Objective: To evaluate the migration inhibition ability of treatment agents in volumetric soil columns, especially the migration pathways of pollutants such as Pb, Cu, Cr, and PAHs.

[0060] Method: Prepare soil columns (10-15 cm high, 3-5 cm in diameter), inject a solution containing pollutants into the columns, and compare the changes in pollutant concentrations in the effluent treated with control, single-component, two-component, and three-component (the composition of this invention).

[0061] Key indicators: total heavy metals in the eluent, dissolution rate, and time to peak concentration.

[0062] Results: After 60 days of treatment, the cumulative Pb concentration in the effluent decreased by approximately 65%, compared to approximately 15% in the control group; the cumulative PAHs concentration in the effluent decreased by approximately 70% after 60 days of treatment.

[0063] Table 5. Inhibition effect of soil column leaching and migration

[0064] The results in Table 5 above show that the migration inhibition ratio of Example 1 of the present invention is significantly higher than that of the comparative group, demonstrating excellent migration inhibition ability. In the other comparative groups, the migration inhibition ratio gradually increased with the adjustment of the formulation, reflecting a trend change in the treatment effect. The treatment agent significantly reduced the migration of pollutants through the soil column system, demonstrating excellent inhibition and stabilization effects.

[0065] Verification Test Example 3 Plant growth and ecological effect evaluation Objective: To verify the effect of soil treatment on promoting plant growth and reducing the bioavailability of pollutants after the application of the treatment agent.

[0066] Methods: A greenhouse pot experiment was conducted using crops sensitive to pollutants (such as wheat / corn seedlings). The experiment included a control group (untreated soil), a treatment group (soil treated according to the example), and several control groups (single-component / two-component treatments).

[0067] Indicators: seedling height, aboveground / root dry weight, chlorophyll content, accumulation of heavy metals in plant tissues, and soil microbial activity (such as dehydrogenase activity).

[0068] Results: The crop dry weight of the treatment group increased by about 25–40%, the root length increased by 20–35%, and the transfer of surface pollutants to crop tissues decreased significantly (Pb and Cd content in the aboveground parts decreased by about 40–60%).

[0069] Conclusion: The treatment agent not only reduces the bioavailability of pollutants, but also promotes soil microbial activity and significantly improves plant growth traits, demonstrating good potential for ecological restoration.

[0070] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Therefore, any simple modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A soil pollution control agent, characterized in that, The treatment agent is a dry weight formulation, comprising, by mass fraction: Biochar / activated carbon: 40-60%; Film-forming agent consisting of sodium alginate and hydroxyethyl cellulose in a specified ratio: 5-15%; Polymer emulsion: 5-30%; Chelating agent (EDDS, sub-exogenous organic chelating agent): 2-4%; Nano-iron oxides (Fe2O3 / Fe3O4) or nano-oxides: 2-4%; Bentonite / montmorillonite clay modified filler: 10-20%; Microbial preparation (mixture of beneficial microorganisms): 1%; Silicate modified powder / mineral powder (dihydrate silicate, zeolite): 4-6%; Other auxiliary components (humic acid / sustained-release carrier): 2-4%.

2. The soil pollution control agent according to claim 1, characterized in that, The preparation process of the treatment agent includes the following steps: The carrier material is mixed, and film-forming agents and polymer emulsions, chelating agents and nano-oxides, microbial preparations and silicate powder are added. After mixing in proportion, the mixture is shaped and dried at low temperature.

3. The soil pollution control agent according to claim 1, characterized in that, The treatment agent is a dry weight formulation, comprising, by mass fraction: Biochar / activated carbon: 50%; Sodium alginate and other film-forming agents: 10%; Polymer emulsion: 10%; EDDS: 3%; Nano iron oxide: 3%; Montmorillonite / bentonite: 15%; Microbial preparations: 1%; Silicate powder: 5%; Other auxiliary components: 3%; Its preparation process includes the following steps: Biochar is dried and mixed with inorganic carriers such as montmorillonite at room temperature to ensure uniform particle size; Prepare a film-forming solution: Dissolve sodium alginate and other film-forming agents in water and adjust the pH to 6–7; The polymer emulsion is slowly added to the carrier mixture to form a homogeneous slurry; Add EDDS, nano iron oxide, microbial preparation and silicate powder in proportion, and continue to mix until there are no particles agglomerating; The product is formed by extrusion molding, granulation, or direct drying, and then dried at room temperature or below 60°C until the moisture content is ≤8%.

4. The soil pollution control agent according to claim 1, characterized in that, The treatment agent is a dry weight formulation, comprising, by mass fraction: Biochar / activated carbon: 55%; Sodium alginate and other film-forming agents: 8%; Polymer emulsion: 11%; EDDS: 2%; Nano iron oxide: 4%; Montmorillonite / bentonite: 10%; Microbial preparations: 1%; Silicate powder: 5%; Other auxiliary components: 4%; Its preparation process includes the following steps: Biochar, montmorillonite, and silicate powder are mixed to ensure uniform dispersion; The film-forming agent is pretreated with the polymer emulsion and then mixed to obtain the binder phase; Add EDDS, nano iron oxide, and microbial preparation, and continue mixing; Granulation, molding, and low-temperature drying are carried out while maintaining a humidity level below 8%.

5. The soil pollution control agent according to claim 1, characterized in that, The treatment agent is a dry weight formulation, comprising, by mass fraction: Biochar / activated carbon: 60%; Polymer emulsion: 8%; Sodium alginate and other film-forming agents: 7%; EDDS: 4%; Nano iron oxide: 2%; Montmorillonite / bentonite: 12%; Microbial preparations: 1%; Silicate powder: 4%; Other auxiliary components: 2%; Its preparation process includes the following steps: Biochar is used as the main component and is first dry-mixed with clay materials to ensure particle dispersion; The film-forming agent is mixed with the polymer emulsion to form a uniform adhesive system; Add active components such as EDDS and nano-iron oxides, and mix well; Form granular, particulate, or block-shaped products, and dry them at low temperature to ensure stable particle size.

6. The soil pollution prevention and treatment agent according to claim 5, characterized in that: The biochar is selected from wood / straw pyrolysis char with a particle size of 3–8 mm, rich pores, and high activity; The polymer emulsion is selected from acrylate emulsion, chitosan emulsion, glutaraldehyde emulsion, or other commonly used soil amendment emulsions; The nano Fe2O3 is selected from ultrafine, magnetic nano iron oxide with a particle size of 10–20 nm. The nano Fe3O4 is selected from ultrafine, magnetic nano iron oxide with a particle size of 10–20 nm. The microbial preparation is selected from probiotics containing rhizosphere nitrogen-fixing bacteria, phenoloxidil, Bacillus, etc., with a CFU ≥ 10. 8 CFU / g; The silicate powder is selected from natural or synthetic zeolites with a particle size of 2–5 mm and excellent adsorption capacity.

7. The application of the soil pollution prevention and treatment agent as described in any one of claims 1-5 in the assessment and remediation of soil pollution in construction land.

8. The application of the soil pollution prevention and treatment agent as described in claim 7 in the assessment and remediation of soil pollution in construction land, characterized in that, The preparation process of the soil pollution prevention and treatment agent is as follows: Step A: Raw material preparation; Adsorbent materials such as biochar and zeolite are dried to a moisture content of ≤5%; Perform necessary pretreatment on the active microbial agents (such as recovery from low-temperature dormancy and biomass statistics) to ensure that the activity reaches the expected CFU / unit mass. Prepare organic-inorganic nutrients, binders, and controlled-release carriers, etc. Step B: Dry mixing and wet mixing; Preliminary dry mixing of the dry materials according to the above proportions to ensure uniform dispersion of each component; Add an aqueous binder / carrier system and stir at medium speed to achieve uniform wetting, ultimately achieving a material moisture content of 10–15% suitable for granulation; Step C: Granulation / forming; Granulation is carried out using pelletizing, extrusion granulation or excavation granulation equipment, and the particle size can be controlled within 3–8 mm; Step D: Drying and Maintenance; The granulated particles are dried to the target moisture content (usually ≤5%) at ambient temperature or under temperature-controlled drying conditions. Proper maintenance and a placement period of 8–14 days allow the microbial agent to stably colonize the carrier and gradually increase its activity. Step E: Packaging and Quality Control; Quality tests were conducted on particle size distribution, moisture content, bacterial activity (CFU / g), and adsorption performance. Packaging, transportation, and storage conditions must comply with local / national environmental remediation standards.

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