A method for remediating polluted soil in environmental governance

Abstract

The invention relates to the field of contaminated soil technical restoration, and discloses an environmental governance contaminated soil restoration method, comprising the steps of: performing in-situ mixing on a contaminated site, using a mechanical mixing device to fully turn over and mix the soil to form a uniform soil mixing system; adding a slender solid auxiliary agent to the mixed soil system, wherein the surface of the slender solid auxiliary agent has a large number of hydroxyl groups; using a sprinkler irrigation system to spray a 1-5wt% multifunctional crosslinking agent solution to the mixed soil system; the crosslinking agent undergoes a crosslinking reaction with clay minerals and hydroxyl groups on the surface of the slender solid auxiliary agent in the soil, and rapidly forms a three-dimensional crosslinked polymer network in the soil solid phase; adsorbing and capturing pollutants in the formed polymer network, and combining the pollutants with soil minerals; achieving efficient fixation and aggregation of pollutants, greatly improving the restoration effect of the contaminated soil, avoiding large-scale soil excavation and transportation, having little interference with the surrounding environment during the restoration process, and having a simple process, convenient operation, and low restoration cost.

Description

Technical Field

[0001] The present invention relates to the field of contaminated soil restoration technology, and in particular to a method for restoring contaminated soil for environmental governance. Background Art

[0002] With the acceleration of industrialization, soil pollution is becoming increasingly serious. At present, soil refers to the loose surface layer of the land surface that is fertile and can grow plants. Its thickness is generally about 2m. Soil not only provides mechanical support for plant growth, but also provides the fertility elements such as water, fertilizer, air, and heat required for plant growth and development. Due to the rapid growth of population and the rapid development of industry, solid waste is constantly piled and dumped on the soil surface, harmful wastewater is constantly infiltrating into the soil, and harmful gases and floating dust in the atmosphere are constantly falling into the soil with rain, leading to soil pollution. Any substance that hinders the normal function of the soil, reduces crop yield and quality, and indirectly affects human health through food, vegetables, fruits, etc. is called soil pollutants. With the development of my country's economy, the soil condition in my country is deteriorating day by day, and its pollution situation is generally severe. Soil pollution is serious in some areas. However, the causes of soil pollution are complex and difficult to control. There is no solution to classify soil pollution and carry out effective remediation.

[0003] Conventional methods for remediating contaminated soil, such as excavation and replacement and stabilization and solidification, require large amounts of excavated contaminated soil for disposal, which is costly and has a significant impact on the surrounding ecological environment. They also have low R&D efficiency, high costs, and great impact on the environment. Therefore, it is necessary to design a corresponding technical solution to address this problem. Summary of the invention

[0004] In view of the shortcomings of the prior art, the present invention provides a method for environmental governance and contaminated soil remediation, which solves the technical problems of requiring large-scale excavation of contaminated soil and disposal, high governance costs and significant interference to the surrounding ecological environment, low R&D efficiency, high costs, and significant interference to the environment.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: a method for remediating contaminated soil in environmental governance, the method steps include the following:

[0006] S1. Mix the contaminated site in situ and use a mechanical mixing device to fully mix the soil to form a uniform soil mixing system;

[0007] S2, adding a slender solid additive to the mixed soil system, wherein the slender solid additive has a large number of hydroxyl groups on the surface and is a natural cotton fiber or a magnetic nanorod, and adding the slender solid additive to the soil at a mass fraction of 0.5-2wt%, and continuing to mix to make it evenly dispersed;

[0008] The natural cotton fiber auxiliary agent has an average diameter of 15-20 μm, an average length of 0.5-1 mm, and an addition amount of 0.8% by mass;

[0009] The magnetic nanorod auxiliary agent has an average diameter of 50-80 nm, an average length of 600-800 nm, and an added amount of 1.2% by mass;

[0010] S3, using a sprinkler system to spray 1-5wt% of a multifunctional crosslinking agent solution onto the mixed soil system, so that the crosslinking agent solution infiltrates the soil system, wherein the crosslinking agent comprises an acrylate having a diene bond or resorcinol having a hydroxyl group and an aldehyde group;

[0011] S4, the cross-linking agent undergoes a cross-linking reaction with the surface hydroxyl groups of clay minerals and elongated solid additives in the soil, and quickly forms a three-dimensional cross-linked polymer network in the soil solid phase;

[0012] The cross-linking reaction comprises the following steps:

[0013] The cross-linker molecule has two or more reactive groups, and acrylic cross-linkers usually contain two carboxyl groups;

[0014] The crosslinker molecules react with the hydroxyl groups on the surface of clay minerals and additives, and the carboxyl group at one end reacts with the hydroxyl group as follows:

[0015] R-COOH+HO-R'→R-COO-R';

[0016] The other end carboxyl group of the same cross-linking agent molecule continues to react with the hydroxyl groups of other clay surfaces or auxiliary agent molecules to form a covalent chain:

[0017] R-COO-R'-COOH+HO-R"→R-COO-R'-COO-R";

[0018] One crosslinker molecule can react with multiple clay surface hydroxyl groups and additive surface hydroxyl groups at the same time to form a three-dimensional crosslinked network:

[0019] R-COO-R'-COO-R"-COOH+HO-R"'→R-COO-R'-COO-R"-COO-R"';

[0020] S5, adsorbs and captures pollutants in the formed polymer network, binding them to soil minerals;

[0021] S6, starting the vibration device to apply vibration to the treated soil to promote the adsorption and sedimentation of pollutants on the surface of mineral particles;

[0022] S7. Finally, a simple circular arch project is used to solidify the settlement phase in situ, or to backfill and seal it.

[0023] Preferably, in step S1, the mechanical mixing device includes a six-axis independent stirring mechanism, a variable direction propulsion system driven by a control algorithm, a herringbone mixing chamber, a high-density intermittent pulse vibration system and a retractable movable sealing cover;

[0024] The six-axis independent stirring mechanism includes multiple independently rotatable stirring shafts, each shaft is provided with multiple layers of staggered blades, the variable direction propulsion system driven by the control algorithm is combined with GPS positioning, the herringbone mixing chamber includes multiple sections of mutually hinged chambers, the stirring shaft is inserted from one end and transmitted section by section to achieve progressive mixing, the high-density intermittent pulse vibration system strongly vibrates the mixing chamber during the stirring process, and the retractable movable sealing cover is connected to the negative pressure system.

[0025] Preferably, in step S3, the sprinkler irrigation system includes an independent injection system, a spiral flat spray nozzle, a pneumatic elastic cantilever bracket, a drone, a soil moisture detection device, a liquid flow regulating device of the nozzle, and an adapter;

[0026] The independent spraying system includes a plurality of spray heads that can rotate freely 360 degrees;

[0027] The spiral flat spray nozzle enables the rotating liquid flow to sweep across the soil surface in a spiral manner;

[0028] The pneumatic elastic cantilever bracket enables the spiral flat spray nozzle to bounce up and down to adapt to the height difference of the terrain;

[0029] In the UAV cooperative operation mode, the independent injection system can automatically follow the UAV flight through program control;

[0030] Using pressure pulse technology, the crosslinker solution is sprayed in alternating high and low pressure modes;

[0031] The soil moisture detection device detects soil moisture online during the spraying process, and realizes variable rate spraying according to the liquid flow regulating device of the nozzle to reduce overflow;

[0032] The spiral flat spray nozzle is connected to an adapter to automatically change different nozzle types.

[0033] Preferably, the liquid flow regulating device of the nozzle includes regulating pressure and regulating opening;

[0034] The spiral flat spray nozzle uses a variable frequency pressure regulating pump to supply liquid. The pressure of the liquid supply pipeline is changed through the PLC or human-machine interface, so as to accurately control the liquid injection pressure and flow rate of the nozzle. Increasing the pressure can increase the spray volume, while reducing the pressure can reduce the spray volume.

[0035] The spiral flat spray nozzle adopts an electrically controlled needle valve as a terminal control element. By adjusting the opening of the needle valve, the liquid flow area can be continuously changed, thereby adjusting the flow of the nozzle. The precise control of the needle valve opening can be achieved by a stepper motor.

[0036] Preferably, in step S3, spraying 1-5wt% of the multifunctional cross-linking agent solution can improve the physical and chemical properties, and the improved physical and chemical properties include the permeability of soil particles, the water retention of soil particles, the aggregation structure of soil particles, the adhesion / cohesion of the soil, the partial energy released by the cross-linking reaction, the buffering capacity of the soil, the micromorphology of the soil, the fertilizer retention capacity of the soil, the adsorption effect of the soil, the temperature and humidity state of the soil, the electrochemical activity of the soil and the dielectric constant of the soil.

[0037] Preferably, in step S5, the pollutants adsorbed and captured by the polymer network include: heavy metal pollutants, organic pollutants, radionuclides, pathogenic microorganisms, nutrient salt pollution and various types of particulate pollution.

[0038] Preferably, the heavy metal pollutants include but are not limited to one or more of lead, cadmium, copper, chromium, and mercury; the organic pollutants include but are not limited to petroleum hydrocarbons, pesticides, and polycyclic aromatic hydrocarbons; the radioactive nuclides include but are not limited to uranium, rubidium, and strontium; the pathogenic microorganisms include but are not limited to bacteria, viruses, and parasites; the nutrient salt pollution includes but is not limited to nitrogen and phosphorus compounds; and the various types of particulate pollution include but are not limited to dust, soot, and microplastic particles.

[0039] Preferably, in step S5, the cross-linked polymer network processes the adsorbed and captured pollutants in the following ways: physical fixation, chemical binding, promoting decomposition, promoting transformation, enriching pollution, slowing release, shielding pollution and improving detection efficiency.

[0040] Preferably, in step S6, the vibration device includes a vibration generator, a closed-loop feedback control algorithm, a magnetic suspension bearing system, a conical vibration head, an ultrasonic attachment device, an air compression pulse device, and an independent power supply and voltage stabilization system;

[0041] The vibration mode of the vibration device is:

[0042] The vibration intensity should be properly controlled and not too high to avoid damaging the soil particle structure;

[0043] Use progressive vibration, from weak to strong, to allow the soil to gradually adapt;

[0044] Monitor soil deformation and settlement parameters and adjust vibration intensity;

[0045] Intermittent vibration and spraying technology to maintain a certain humidity in the soil;

[0046] Repair is carried out after vibration, and a binder is added to restore the soil structure;

[0047] Mainly uses low-frequency vibration, and high-frequency ultrasound only plays an auxiliary role;

[0048] Avoid using high-intensity vibration on liquefiable or cohesive soils;

[0049] Set a reasonable vibration time, not too long;

[0050] Adopt novel design of vibration head to produce progressive vibration waves;

[0051] Later, the physical and chemical properties of the soil are tested to assess the impact of vibration;

[0052] In summary, the risk of soil damage caused by the vibration device can be minimized through reasonable parameter design and control.

[0053] Preferably, in step S6, the simple engineering method for in-situ solidification treatment of the sedimentation phase by the simple dome engineering comprises:

[0054] Use local materials at the polluted site, such as solid waste coal ash and curing agent cement, to prepare simple embankment materials;

[0055] Use simple embankment materials to enclose a dome-shaped area at the contaminated site, and seal the sedimentation phase within the dome-shaped area;

[0056] The height of the dome depends on the depth of the pollution. It can be formed as an above-ground dome or buried underground, with a waterproof cover on the top;

[0057] The settled phase in the dome area is solidified in situ, with excessive application of curing agent or microbial reduction solidification;

[0058] The area of ​​a dome is determined according to the pollution range, and multiple dome areas can be set;

[0059] The round arch structure itself can play the role of a cofferdam and is also convenient for later monitoring;

[0060] The solidified body can be covered and sealed for a second time after repair.

[0061] Compared with the prior art, the present invention has the following beneficial effects: a wide range of chemical polymer networks are constructed in the contaminated soil system, which can effectively fix pollutants and achieve good remediation effects; the formation of the polymer network can promote the sedimentation and precipitation of pollutants and soil minerals, thereby achieving efficient fixation and aggregation of pollutants, and the pollutant removal rate reaches more than 58%, which greatly improves the remediation effect of contaminated soil; pollutants are aggregated by precipitation, which is convenient for subsequent treatment; at the same time, since the entire process is carried out directly at the contaminated site, large-scale soil excavation and transportation is avoided; the in-situ remediation process has little interference with the surrounding environment; the process is simple, the operation is convenient, and the remediation cost is low. DETAILED DESCRIPTION

[0062] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0063] The embodiment of the present invention provides a technical solution: a method for remediating contaminated soil in environmental governance, the method steps comprising the following:

[0064] S1. Mix the contaminated site in situ and use a mechanical mixing device to fully mix the soil to form a uniform soil mixing system;

[0065] S2, adding a slender solid additive to the mixed soil system, wherein the slender solid additive has a large number of hydroxyl groups on the surface and is a natural cotton fiber or a magnetic nanorod, and adding the slender solid additive to the soil at a mass fraction of 0.5-2wt%, and continuing to mix to make it evenly dispersed;

[0066] The natural cotton fiber additive has an average diameter of 15-20 μm, an average length of 0.5-1 mm, and an addition amount of 0.8% by mass (equivalent to adding 8 grams of natural cotton fiber per kilogram of soil);

[0067] The magnetic nanorod additive has an average diameter of 50-80 nm, an average length of 600-800 nm, and an addition amount of 1.2% by mass (equivalent to adding 12 mg of magnetic nanorods per kilogram of soil);

[0068] Selecting additives with slender structures can build a network in the soil matrix and increase the contact interface of pollutants.

[0069] Cotton fibers are millimeter-long and can wrap around soil particles. Magnetic nanorods are submicron-long and can enter soil pores. The two complement each other in size and work together to improve the remediation effect of contaminated soil.

[0070] The added amount is controlled within the mass fraction range of 0.5%-2%, which, on the one hand, provides sufficient hydroxyl groups to react with the cross-linking agent, and on the other hand, avoids excessive effects on soil physical properties.

[0071] Provides a large number of hydroxyl groups, which can undergo polymerization reaction with cross-linking agents to build a polymer network to fix pollutants;

[0072] The slender structure can wrap around and cover soil particles, increasing the contact interface between pollutants and soil, which is beneficial to the adsorption of pollutants;

[0073] Improve soil porosity to a certain extent, increase soil permeability and aeration, which is beneficial to subsequent polymerization reactions and volatilization of pollutants;

[0074] Some additives, such as magnetic nanorods, can also give the soil magnetic responsiveness, making it easier to separate polluted particles using magnetic force later;

[0075] Some natural fiber additives can provide nutrients, promote the growth of soil microorganisms, and promote the biodegradation of pollutants;

[0076] Longer fiber additives can play a role in skeleton support by entangling soil particles, improving soil stability and promoting the effectiveness of other pollution control measures;

[0077] In summary, adding an appropriate amount of slender solid additives can synergistically improve the treatment effect of contaminated soil in many aspects.

[0078] S3, using a sprinkler system to spray 1-5wt% of a multifunctional crosslinking agent solution onto the mixed soil system, so that the crosslinking agent solution infiltrates the soil system, wherein the crosslinking agent comprises an acrylate having a diene bond or resorcinol having a hydroxyl group and an aldehyde group;

[0079] S4, the cross-linking agent undergoes a cross-linking reaction with the surface hydroxyl groups of clay minerals and elongated solid additives in the soil, and quickly forms a three-dimensional cross-linked polymer network in the soil solid phase;

[0080] The cross-linking reaction comprises the following steps:

[0081] The cross-linking agent molecule has two or more reactive groups, such as acrylic cross-linking agents usually contain two carboxyl groups;

[0082] The crosslinker molecules react with the hydroxyl groups on the surface of clay minerals and additives, and the carboxyl group at one end reacts with the hydroxyl group as follows:

[0083] R-COOH+HO-R'→R-COO-R';

[0084] The other end carboxyl group of the same cross-linking agent molecule continues to react with the hydroxyl groups of other clay surfaces or auxiliary agent molecules to form a covalent chain:

[0085] R-COO-R'-COOH+HO-R"→R-COO-R'-COO-R";

[0086] One crosslinker molecule can react with multiple clay surface hydroxyl groups and additive surface hydroxyl groups at the same time to form a three-dimensional crosslinked network:

[0087] R-COO-R'-COO-R"-COOH+HO-R"'→R-COO-R'-COO-R"-COO-R"';

[0088] Through the formation of the above multi-point covalent bonds, the cross-linking agent achieves cross-linking between clay minerals and additives and within their own molecules, thereby forming a three-dimensional cross-linked polymer network structure in the solid phase soil.

[0089] S5, adsorbs and captures pollutants in the formed polymer network, binding them to soil minerals;

[0090] S6, starting the vibration device to apply vibration to the treated soil to promote the adsorption and sedimentation of pollutants on the surface of mineral particles;

[0091] S7. Finally, a simple circular arch project is used to solidify the settlement phase in situ, or to backfill and seal it.

[0092] Effects of spraying 1-5wt% multifunctional crosslinker solution:

[0093] Providing reactive functional groups - the crosslinker molecules have polymerizable diene bonds (acrylates) or mutually reactive hydroxyl and aldehyde groups (resorcinol), which can undergo crosslinking reactions with the hydroxyl groups of minerals in the soil;

[0094] Controlling the network structure - the amount of cross-linking agent added is 1-5wt%. This concentration range can form a cross-linked network structure that is dense enough but not over-polymerized, avoiding the soil structure being too dense or too loose;

[0095] Fixed pollutants - the formed polymer network can fix pollutants in the network structure to prevent them from continuing to migrate and spread;

[0096] Improve physical and chemical properties - the formation of the network can partially improve the physical and chemical properties of the soil, such as permeability and water retention, which is beneficial to the subsequent repair reaction;

[0097] Uniform distribution - Sprinkler irrigation can evenly distribute the cross-linking agent in the soil to be treated, avoiding local aggregation, thereby achieving comprehensive treatment of the contaminated site; controlling the concentration and spraying of the cross-linking agent is the key to building an ideal soil remediation network, which not only plays a remediation role but also avoids excessive changes to soil properties.

[0098] Further improved, in step S1, the mechanical mixing device includes a six-axis independent stirring mechanism, a variable direction propulsion system driven by a control algorithm, a herringbone mixing chamber, a high-density intermittent pulse vibration system and a retractable movable sealing cover;

[0099] It uses a six-axis independent mixing mechanism, which includes multiple independently rotating mixing shafts. Each shaft is equipped with multiple layers of staggered blades. This complex power system can perform three-dimensional flip mixing on the soil from multiple directions to ensure uniform mixing.

[0100] A variable direction propulsion system driven by a control algorithm is set up to enable the entire device to move in different directions on the site, fully covering the contaminated area for mixing operations. The system, combined with GPS positioning, can automatically plan the best mixing path;

[0101] The uniquely designed herringbone mixing chamber consists of multiple sections of mutually hinged chambers. The mixing shaft is inserted from one end and driven section by section to achieve progressive mixing, which is conducive to the progressive mixing of soil from coarse mixing to fine mixing.

[0102] The high-density intermittent pulse vibration system is used to strongly vibrate the mixing chamber during the mixing process, breaking the soil cohesion, enhancing the gas-solid exchange rate, and further improving the mixing uniformity;

[0103] A retractable movable sealing cover is set up to adjust and cover the mixing system according to the size of the site to form a closed operating environment. The cover is connected to the negative pressure system to reduce dust pollution.

[0104] The rapid, uniform and closed mechanical mixing of the contaminated soil is achieved, which is beneficial to the subsequent cross-linking polymerization fixation reaction and improves the efficiency of pollution control.

[0105] Further improved, in step S3, the sprinkler irrigation system includes an independent injection system, a spiral flat spray nozzle, a pneumatic elastic cantilever bracket, a drone, a soil moisture detection device, a liquid flow regulating device of the nozzle, and an adapter;

[0106] Adopt an independent spraying system, including multiple nozzles that can rotate 360 ​​degrees freely, to achieve multi-angle three-dimensional spraying of the soil and improve the uniformity of spraying;

[0107] The nozzle is equipped with a special spiral flat spray nozzle, and the rotating liquid flow can sweep across the soil surface in a spiral to avoid dead corners;

[0108] A pneumatic elastic cantilever bracket is set up, so that the nozzle can bounce up and down to adapt to the height difference of the terrain and ensure that all polluted areas are covered;

[0109] Using the drone collaborative operation mode, the sprinkler system can automatically follow the drone through program control to expand the range of liquid spraying;

[0110] Using pressure pulse technology, the crosslinker solution is sprayed in alternating high and low pressure modes, which can both penetrate and stir the soil;

[0111] The soil moisture is detected online during the spraying process, and the liquid flow rate of the nozzle is intelligently adjusted accordingly to achieve variable rate spraying and reduce overflow;

[0112] The nozzle connection adapter can automatically change different nozzle types to adapt to working conditions in real time;

[0113] It can realize efficient, uniform and intelligent cross-linking agent spraying on contaminated soil, which is beneficial to improving the subsequent pollution remediation effect.

[0114] In a further improvement, the liquid flow regulating device of the nozzle includes a pressure regulating device and an opening regulating device.

[0115] Adjusting the pressure: The nozzle can be supplied with a variable frequency pressure regulating pump. The pressure of the liquid supply pipeline can be changed through the PLC or human-machine interface to accurately control the liquid injection pressure and flow rate of the nozzle. Increasing the pressure can increase the spray volume, while reducing the pressure can reduce the spray volume.

[0116] Adjust the opening: The nozzle can use an electrically controlled needle valve as the terminal control element. By adjusting the opening of the needle valve, the liquid flow area can be continuously changed, thereby adjusting the flow of the nozzle. The precise control of the needle valve opening can be achieved by a stepper motor.

[0117] The flow rate of the nozzle can be changed by adjusting the throttling device in the nozzle liquid pipeline. Combined with pressure control and valve adjustment, closed-loop control and precise adjustment of the nozzle flow rate can be achieved.

[0118] Further improved, in step S3, spraying 1-5wt% of the multifunctional cross-linking agent solution can improve the physical and chemical properties, and the improved physical and chemical properties include the permeability of soil particles, the water retention of soil particles, the aggregation structure of soil particles, the adhesion / cohesion of the soil, the partial energy released by the cross-linking reaction, the buffering capacity of the soil, the micromorphology of the soil, the fertilizer retention capacity of the soil, the adsorption effect of the soil, the temperature and humidity state of the soil, the electrochemical activity of the soil and the dielectric constant of the soil.

[0119] Improve the aggregation structure of soil particles and increase the stability and anti-erosion ability of the soil to a certain extent;

[0120] Increase the bonding and cohesion of the soil, which is beneficial to the fixation of pollutants;

[0121] The release of some energy through cross-linking reactions can promote the transformation or degradation of pollutants;

[0122] Increase the buffering capacity of the soil to resist the effects of pH fluctuations;

[0123] Change the microscopic morphology of the soil, increase its specific surface area, and facilitate the attachment of microorganisms;

[0124] Improve the soil's ability to retain fertilizer and reduce the loss of nutrients;

[0125] Partially change the adsorption of soil, such as increasing the adsorption capacity of heavy metals;

[0126] Adjust the temperature and humidity of the soil to make it more suitable for microbial growth and pollutant degradation;

[0127] Enhance the electrochemical activity of the soil, which is conducive to the application of electrodynamic remediation technology;

[0128] Changing the dielectric constant of the soil is beneficial to the absorption of microwaves in electromagnetic repair technology.

[0129] In summary, spraying cross-linking agents can regulate the physical and chemical properties of soil in many aspects and play a positive role in pollution remediation.

[0130] As a further improvement, in step S5, the pollutants that the polymer network is used to adsorb and capture include: heavy metal pollutants, organic pollutants, radioactive nuclides, pathogenic microorganisms, nutrient salt pollution and various types of particulate pollution.

[0131] In a further improvement, the heavy metal pollutants include, but are not limited to, one or more of lead, cadmium, copper, chromium, and mercury, all of which are soil heavy metal pollutants in the form of heavy metal ions or particles;

[0132] Organic pollutants include, but are not limited to, petroleum hydrocarbons, pesticides, and polycyclic aromatic hydrocarbons, which are widely found in industrial and agricultural contaminated sites;

[0133] Radionuclides include but are not limited to radioactive elements such as uranium, rubidium, strontium and their isotopes. These radioactive contaminations from nuclear facilities or nuclear accidents also require soil remediation;

[0134] Pathogenic microorganisms include but are not limited to bacteria, viruses, and parasites. Contaminated soil may contain various pathogenic microorganisms;

[0135] Nutrient pollution includes, but is not limited to, nitrogen and phosphorus compounds. Soil salinization caused by excessive fertilizer application also needs to be treated;

[0136] Various types of particulate pollution include but are not limited to dust, soot, and microplastic particles, all of which are solid suspended pollutants.

[0137] The cross-linked polymer network captures these pollutants through adsorption and entanglement.

[0138] Further improved, in step S5, the cross-linked polymer network processes the adsorbed and captured pollutants in the following ways: physical fixation, chemical binding, promoting decomposition, promoting transformation, enriching pollution, slowing release, shielding pollution and improving detection efficiency.

[0139] Physical fixation: the cross-linked network can act like a macromolecular cage, fixing the pollutants through physical adsorption to prevent their migration and diffusion;

[0140] Chemical binding, the functional groups in the network can react chemically with the pollutants and fix the pollutants by covalent bonding;

[0141] Promote decomposition. The microenvironment provided by the network is conducive to the growth of some microorganisms and can promote the biodegradation of pollutants;

[0142] Promote transformation. Some pollutants can be transformed into low-toxic or non-toxic species in the microenvironment formed by the network;

[0143] After the pollutants are concentrated in the network, they can be easily recycled and processed, or they can be sealed and solidified on site;

[0144] Slowing down release, the rate at which fixed pollutants are released from the network into the environment will be greatly slowed;

[0145] Shielding pollution: the network can block the contact between pollutants and the external environment to a certain extent;

[0146] Improve detection efficiency. After network enrichment pollution, it is beneficial for various detection technologies to detect pollutants.

[0147] In summary, the cross-linked network can synergistically treat pollutants from multiple aspects to achieve soil remediation.

[0148] As a further improvement, in step S6, the vibration device includes a vibration generator, a closed-loop feedback control algorithm, a magnetic suspension bearing system, a conical vibration head, an ultrasonic attachment device, an air compression pulse device, and an independent power supply and voltage stabilization system.

[0149] The vibration generator contains multiple vibration motors that can be controlled individually to achieve multi-directional vibration of the soil;

[0150] Design a closed-loop feedback control algorithm that can intelligently adjust the vibration waveform, frequency and amplitude based on real-time detected soil density, liquid content and other parameters to achieve the best vibration effect;

[0151] The magnetic suspension bearing system is used, and the vibration device does not directly contact the ground, which reduces the self-vibration interference of the system and improves the output vibration control accuracy;

[0152] The cone-shaped vibration head with diameters from small to large can generate progressive particle sorting vibration waves, which is conducive to the aggregation and sedimentation of pollutants;

[0153] The vibration head is equipped with an ultrasonic attachment, which can simultaneously apply high-frequency ultrasonic waves to further improve the desorption efficiency of pollutants from soil particles;

[0154] Design an air compression pulse device that can intermittently apply compressed air shock to the soil to loosen the soil structure and enhance the vibration effect;

[0155] Adopt independent power supply and voltage stabilization system to ensure stable and reliable power during vibration.

[0156] The vibration mode of the vibration device is:

[0157] The vibration intensity should be properly controlled and not too high to avoid damaging the soil particle structure;

[0158] Use progressive vibration, from weak to strong, to allow the soil to gradually adapt;

[0159] Monitor soil deformation and settlement parameters and adjust vibration intensity;

[0160] Intermittent vibration and spraying technology to maintain a certain humidity in the soil;

[0161] Repairs are performed after vibration, such as adding adhesives to restore the soil structure;

[0162] Mainly uses low-frequency vibration, and high-frequency ultrasound only plays an auxiliary role;

[0163] Avoid using high-intensity vibration on liquefiable or cohesive soils;

[0164] Set a reasonable vibration time, not too long;

[0165] Adopt novel design of vibration head to produce progressive vibration waves;

[0166] Later, the physical and chemical properties of the soil are tested to assess the impact of vibration;

[0167] In summary, the risk of soil damage caused by the vibration device can be minimized through reasonable parameter design and control.

[0168] Specifically, in step S6, the simple engineering method for in-situ solidification treatment of the sedimentation phase of the simple dome engineering comprises:

[0169] Use local materials at the polluted site, such as solid waste coal ash and curing agent cement, to prepare simple embankment materials;

[0170] Use simple embankment materials to enclose a dome-shaped area at the contaminated site, and seal the sedimentation phase within the dome-shaped area;

[0171] The height of the dome depends on the depth of the pollution. It can be formed as an above-ground dome or buried underground, with a waterproof cover on the top;

[0172] The settled phase in the dome area is solidified in situ, with excessive application of curing agent, or microbial reduction solidification;

[0173] The area of ​​a dome is determined according to the pollution range, and multiple dome areas can be set;

[0174] The round arch structure itself can play the role of a cofferdam and is also convenient for later monitoring;

[0175] The structure is easy and fast to build, low cost, and is conducive to on-site emergency response;

[0176] The cured body can also be covered and sealed for a second time after repair.

[0177] Example 1, selection of contaminated soil samples:

[0178] The soil from a nearby chemical plant that has been in production for many years was selected as the research object. Pollutants such as petroleum hydrocarbons and heavy metals were detected in the soil, and the degree of pollution was relatively high. About 100 kg of surface contaminated soil was collected, mixed in situ, and used for method verification.

[0179] Example 2, polymerization-precipitation coupling treatment:

[0180] Three groups of samples, 30 kg each, were taken for treatment. One group was the control group, and the other two groups had 2% fiber additives and 3% diene acrylate crosslinker solution added to the soil respectively. After mixing, crosslinking, vibration and other treatment steps, the residual pollutant content in each group of soil was tested.

[0181] Example 3, treatment effect evaluation:

[0182] After testing, the pollutant removal rate of the control group was 20%, and the pollutant removal rates of the two groups of samples with added additives and cross-linking agents reached 62% and 58% respectively. The addition of the polymerization-precipitation coupling system significantly improved the remediation effect of contaminated soil.

[0183] Example 4, soil structure analysis:

[0184] Scanning electron microscopy and infrared spectroscopy were used to analyze the microstructural changes of the contaminated soil, confirming that the cross-linking agent formed an extensive polymer network in the soil, effectively fixing the pollutants.

[0185] In summary, constructing a broad chemical polymer network in the contaminated soil system can effectively fix pollutants and achieve good remediation effects. The formation of the polymer network can promote the sedimentation of pollutants and soil minerals, thereby achieving efficient fixation and aggregation of pollutants. The pollutant removal rate reaches more than 58%, which greatly improves the remediation effect of contaminated soil. Pollutants are aggregated with the help of precipitation, which is convenient for subsequent treatment. At the same time, since the entire process is carried out directly at the contaminated site, large-scale soil excavation and transportation is avoided. The in-situ remediation process has little interference with the surrounding environment, the process is simple, the operation is convenient, and the remediation cost is low.

[0186] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0187] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for remediating contaminated soil in environmental governance, characterized in that: The method steps include the following: S1. Mix the contaminated site in situ and use a mechanical mixing device to fully mix the soil to form a uniform soil mixing system; S2, adding a slender solid additive to the mixed soil system, wherein the slender solid additive has a large number of hydroxyl groups on the surface, and is a natural cotton fiber additive or a magnetic nanorod additive, and adding the slender solid additive to the soil at a mass fraction of 0.5-2wt%, and continuing to mix to make it evenly dispersed; Natural cotton fiber additives: average diameter 15-20μm, average length 0.5-1mm, added amount 0.8% by mass; Magnetic nanorod additive: average diameter is 50-80nm, average length is 600-800nm, and the added amount is 1.2% by mass; S3, using a sprinkler system to spray 1-5wt% of a multifunctional crosslinking agent solution onto the mixed soil system, the multifunctional crosslinking agent solution infiltrates the soil system, the multifunctional crosslinking agent solution having a diene acrylate or a resorcinol having a hydroxyl group and an aldehyde group; S4, the cross-linking agent undergoes a cross-linking reaction with the surface hydroxyl groups of clay minerals and elongated solid additives in the soil, and quickly forms a three-dimensional cross-linked polymer network in the soil solid phase; The cross-linking reaction comprises the following steps: The crosslinker molecule has two or more reactive groups, and acrylic crosslinkers usually contain two carboxyl groups; The crosslinker molecules react with the hydroxyl groups on the surface of clay minerals and additives, and the carboxyl group at one end reacts with the hydroxyl group as follows: R-COOH+HO-R'→R-COO-R'; The other end carboxyl group of the same crosslinker molecule continues to react with the hydroxyl groups of other clay surfaces or additive molecules to form a covalent chain: R-COO-R'-COOH+HO-R"→ R-COO-R'-COO-R"; One crosslinker molecule reacts with multiple clay surface hydroxyl groups and additive surface hydroxyl groups simultaneously to form a three-dimensional crosslinked polymer network: R-COO-R'-COO-R"-COOH+HO-R'''→ R-COO-R'-COO-R"-COO-R'''; S5, adsorbs and captures pollutants in the formed three-dimensional cross-linked polymer network, allowing them to bind to soil minerals; S6, starting the vibration device to apply vibration to the treated soil to promote the adsorption and sedimentation of pollutants on the surface of mineral particles; S7. Finally, a simple circular arch project is used to solidify the settlement phase in situ, or to backfill and seal it.

2. The method for remediating contaminated soil according to claim 1, characterized in that: In step S1, the mechanical mixing device includes a six-axis independent stirring mechanism, a variable direction propulsion system driven by a control algorithm, a herringbone mixing chamber, a high-density intermittent pulse vibration system and a retractable movable sealing cover; The six-axis independent stirring mechanism includes multiple independently rotating stirring shafts, each shaft is provided with multiple layers of staggered blades, the variable direction propulsion system driven by the control algorithm is combined with GPS positioning, the herringbone mixing chamber includes multiple sections of mutually hinged chambers, the stirring shaft is inserted from one end and transmitted section by section to achieve progressive mixing, the high-density intermittent pulse vibration system strongly vibrates the mixing chamber during the stirring process, and the retractable movable sealing cover is connected to the negative pressure system.

3. The method for remediating contaminated soil according to claim 1, characterized in that: In step S3, the sprinkler irrigation system includes an independent injection system, a spiral flat spray nozzle, a pneumatic elastic cantilever bracket, a drone, a soil moisture detection device, a liquid flow regulating device of the nozzle, and an adapter; The independent spraying system includes a plurality of spray heads that can rotate freely 360 degrees; The spiral flat spray nozzle enables the rotating liquid flow to sweep across the soil surface in a spiral manner; The pneumatic elastic cantilever bracket enables the spiral flat spray nozzle to bounce up and down to adapt to the height difference of the terrain; In the UAV cooperative operation mode, the independent jet system automatically follows the UAV through program control; Using pressure pulse technology, the crosslinker solution is sprayed in alternating high and low pressure modes; The soil moisture detection device detects soil moisture online during the spraying process, and realizes variable rate spraying according to the liquid flow regulating device of the nozzle to reduce overflow; The spiral flat spray nozzle is connected to an adapter to automatically change different nozzle types.

4. The method for remediating contaminated soil according to claim 3, characterized in that: The liquid flow regulating device of the nozzle includes a pressure regulating device and an opening regulating device; The spiral flat spray nozzle uses a variable frequency pressure regulating pump to supply liquid. The pressure of the liquid supply pipeline is changed through the PLC or human-machine interface, so as to accurately control the liquid injection pressure and flow rate of the nozzle. Increasing the pressure increases the spray volume, while reducing the pressure reduces the spray volume. The spiral flat spray nozzle adopts an electrically controlled needle valve as a terminal control element, and the liquid flow area is continuously changed by adjusting the opening of the needle valve, thereby adjusting the flow of the nozzle. The precise control of the needle valve opening is achieved by a stepping motor.

5. The method for remediating contaminated soil for environmental management according to claim 1, characterized in that: In step S3, spraying 1-5wt% of the multifunctional cross-linking agent solution can improve the physical and chemical properties, and the improved physical and chemical properties include the permeability of soil particles, the water retention of soil particles, the aggregation structure of soil particles, the adhesion / cohesion of the soil, the partial energy released by the cross-linking reaction, the buffering capacity of the soil, the micromorphology of the soil, the fertilizer retention capacity of the soil, the adsorption effect of the soil, the temperature and humidity state of the soil, the electrochemical activity of the soil and the dielectric constant of the soil.

6. The method for remediating contaminated soil for environmental management according to claim 1, characterized in that: In step S5, the pollutants adsorbed and captured by the polymer network include heavy metal pollutants, organic pollutants, radioactive nuclides, pathogenic microorganisms, nutrient salt pollution and various types of particle pollution.

7. The method for remediating contaminated soil for environmental management according to claim 6, characterized in that: The heavy metal pollutants include but are not limited to one or more of lead, cadmium, copper, chromium, and mercury; the organic pollutants include but are not limited to petroleum hydrocarbons, pesticides, and polycyclic aromatic hydrocarbons; the radioactive nuclides include but are not limited to uranium, rubidium, and strontium; the pathogenic microorganisms include but are not limited to bacteria, viruses, and parasites; the nutrient salt pollution includes but is not limited to nitrogen and phosphorus compounds; the various types of particulate pollution include but are not limited to dust, soot, and microplastic particles.

8. The method for remediating contaminated soil for environmental management according to claim 1, characterized in that: In step S5, the three-dimensional cross-linked polymer network processes the adsorbed and captured pollutants in the following ways: physical fixation, chemical binding, promoting decomposition, promoting transformation, enriching pollution, slowing release, shielding pollution and improving detection efficiency.

9. The method for remediating contaminated soil for environmental management according to claim 1, characterized in that: In step S6, the vibration device includes a vibration generator, a closed-loop feedback control algorithm, a magnetic suspension bearing system, a conical vibration head, an ultrasonic attachment device, an air compression pulse device, and an independent power supply and voltage stabilization system; The vibration mode of the vibration device is: The vibration intensity should be properly controlled and not too high to avoid damaging the soil particle structure; Use progressive vibration, from weak to strong, to allow the soil to gradually adapt; Monitor soil deformation and settlement parameters and adjust vibration intensity; Intermittent vibration and spraying technology to maintain a certain humidity in the soil; Repair is carried out after vibration, and a binder is added to restore the soil structure; Mainly uses low-frequency vibration, and high-frequency ultrasound only plays an auxiliary role; Avoid using high-intensity vibration on liquefiable or cohesive soils; Set a reasonable vibration time, not too long; Adopt novel design of vibration head to produce progressive vibration waves; Later, the physical and chemical properties of the soil are tested to assess the impact of vibration; In summary, the risk of soil damage caused by the vibration device can be minimized through reasonable parameter design and control.

10. The method for remediating contaminated soil for environmental management according to claim 1, characterized in that: In step S6, the simple engineering method for in-situ solidification treatment of the sedimentation phase by the simple round arch engineering includes: Use local materials at the polluted site, such as solid waste coal ash and curing agent cement, to prepare simple embankment materials; Use simple embankment materials to enclose a dome-shaped area at the contaminated site, and seal the sedimentation phase within the dome-shaped area; The height of the dome depends on the depth of the pollution. It can be formed as an above-ground dome or buried underground, with a waterproof cover on the top; The settled phase in the dome area is solidified in situ, with excessive application of curing agent or microbial reduction solidification; The area of ​​a dome is determined according to the pollution range, and multiple dome areas can be set; The round arch structure itself can play the role of a cofferdam and is also convenient for later monitoring; The solidified body can be covered and sealed for a second time after repair.