Electrokinetic remediation simulation device for heavy metal contaminated soil and method thereof

Abstract

This invention discloses a simulation test device and method for electrodynamic remediation of heavy metal contaminated soil. The device includes a data acquisition component and a test chamber. One end of the soil sample tank in the test chamber has an anode electrically connected to a DC power supply for the electric field, and the other end has a cathode electrically connected to the DC power supply for the electric field. It also includes a device for forming a flow field coupled with the electric field: an anode tank located outside the anode and connected to water in the soil sample tank; a cathode tank located outside the cathode and connected to water in the soil sample tank; a water supply device for continuously supplying water to the anode tank; and a vacuuming component for continuously evacuating the cathode tank to maintain continuous seepage of water throughout the soil and to keep the soil in constant contact with the cathode. It also includes an anode-soil anchoring structure to ensure constant contact between the anode and the soil. The top surface of the cathode tank has a sealing cover. This invention can leverage the coupling effect of the electric field and the flow field, significantly improving the remediation effect and efficiency, and effectively improving the engineering properties of the remediated soil.

Description

Technical Field

[0001] This invention relates to the field of contaminated soil remediation technology, specifically to an electrodynamic remediation simulation test device and method for heavy metal contaminated soil. Background Technology

[0002] Heavy metal contamination of soil has become one of the most concerning ecological and environmental issues for humankind. As an emerging soil remediation technology, electroremediation is considered one of the most promising technologies for separating heavy metal pollutants from soil. It mainly relies on electromigration and electroosmosis processes to remove heavy metals from contaminated soil and is suitable for the remediation of poorly permeable soils such as clay.

[0003] Electrokinetic remediation (EMR) technology, as an emerging technology, is still in the initial exploration and development stage. Especially since in-situ EMR of heavy metal contaminated soil is a massive project, its implementation requires robust support from high-voltage and construction safety facilities, significant investment in large-scale equipment, and substantial energy and labor costs. Therefore, to ensure the maturity and high success rate of EMR technology for in-situ heavy metal contaminated soil, many universities and research institutions have adopted a pragmatic approach, starting with indoor simulation devices and methods. Through numerous simulation experiments, they have provided scientific, practical, and rigorous data support and technical guidance to improve the efficiency of EMR for heavy metal contaminated soil and ensure its ultimate application in in-situ remediation to achieve predetermined remediation goals.

[0004] For example, the patent discloses a simulation test device and method for electroremediation of soil contaminated with heavy metals. The simulation test device includes a soil sample test chamber, which includes a sealed cover for a soil sample tank. One end of the soil sample tank has an anode electrically connected to a DC power supply, and the other end has a cathode electrically connected to a DC power supply. It is also equipped with a liquid injection device, a barometer, a temperature sensor, a humidity sensor, a moisture content sensor, a pH sensor, a data recording, storage, and timing device, etc. It can prepare heavy metal contaminated soil samples that conform to actual conditions according to actual needs, and can monitor in real time the changes in soil moisture content, cathode soil pH, ambient temperature, ambient humidity and air pressure, and soil current during the electroremediation process of heavy metal contaminated soil, providing reliable data support and technical guidance for in-situ electroremediation of heavy metal contaminated soil.

[0005] However, the existing simulation devices and methods for electrokinetic remediation of heavy metal-contaminated soil still have the following shortcomings: 1. They are essentially pure electrokinetic remediation methods. The injection of liquid provides water replenishment during the remediation process, and the process relies solely on the electric field. The electrokinetic remediation process struggles to address the activation and migration of insoluble heavy metals in the soil, making it difficult to achieve the desired remediation effect; its remediation efficiency is also affected. 2. Due to the reliance solely on the electric field, the electrokinetic remediation process causes significant damage to the soil. Electrode heating and electrophoresis can lead to uneven soil settlement, uneven moisture content distribution, changes in soil porosity, resulting in soil cracking and altered soil properties. 3. In indoor model tests, because the inner surface of the test tank is generally smooth, the friction between the soil and the inner surface is low. During the electrokinetic remediation process, the soil on both sides sometimes detaches from the side plates. This causes water, containing heavy metal ions, to flow away from the detached areas instead of flowing evenly throughout the soil. This reduces the uniformity and accuracy of the electrokinetic remediation process and is detrimental to improving the engineering properties of the remediated soil. Summary of the Invention

[0006] One technical problem to be solved by the present invention is to provide an electrodynamic remediation simulation test device for heavy metal contaminated soil that can leverage the coupling effect of electric field and flow field, significantly improve the remediation effect and efficiency, and effectively improve the engineering properties of the remediated soil.

[0007] One technical solution of the present invention is to provide a simulation test device for electrodynamic remediation of heavy metal contaminated soil, including a data acquisition component and a test chamber. One end of the soil sample tank of the test chamber has an anode electrically connected to a DC power supply of the electric field, and the other end has a cathode electrically connected to a DC power supply of the electric field.

[0008] The present invention provides an electrodynamic remediation simulation test device for heavy metal contaminated soil, which further includes a device for forming a flow field coupled with an electric field: an anode tank located outside the anode and connected to the water in the soil sample tank; a cathode tank located outside the cathode and connected to the water in the soil sample tank; a water supply device for continuously supplying water to the anode tank; and a vacuuming component for continuously evacuating the cathode tank to ensure that water continuously seeps into the entire soil and keeps the soil in constant contact with the cathode.

[0009] The present invention provides an electrodynamic remediation simulation test device for heavy metal contaminated soil, which further includes an anode-soil anchoring structure that ensures that the anode is always in contact with the soil.

[0010] The top surface of the cathode tank is covered with a sealing cover.

[0011] With the above structure, the electrodynamic remediation simulation test device for heavy metal contaminated soil of the present invention has the following advantages:

[0012] This indoor simulation test device can be used for different types of clay, different heavy metal pollutants, different types of leachate, and different types of electrodes. It can comprehensively obtain data such as soil drainage, settlement, cracking degree, current, energy consumption, regional resistivity and potential value, and interface resistance, calculate different relationships, draw different relationship diagrams, and select the optimal parameters to provide reliable data support and technical guidance for in-situ remediation of heavy metal contaminated soil.

[0013] This invention overcomes the limitations of existing electric remediation technologies and provides an experimental device for remediation under the coupling effect of electric and flow fields. Unlike existing technologies that use peristaltic pumps for drip-feeding water supply, this invention uses a water supply device such as a Marshall bottle to control the water level in the anode tank to remain level with the soil. Unlike existing technologies that employ complete vacuum sealing, this invention only completely seals the cathode and soil sample tanks, leaving the anode tank unsealed. This ensures that the water flow is always in one direction, guaranteeing one-dimensional seepage of the leaching solution from the anode to the cathode. Furthermore, the vacuum pump continuously evacuates the vacuum to maintain continuous seepage of water throughout the soil and to keep the soil and cathode level. The contact creates a pressure difference, transforming the pre-test water injection or mid-test water replenishment of existing technologies into a continuous seepage effect. This makes the soil moisture content and soil settlement more uniform under the action of the flow field, reducing cracks to a certain extent, increasing the seepage rate of the leaching solution, improving the leaching repair efficiency, and solving the problem that single electric field repair is difficult to achieve in the activation and migration of refractory heavy metals in the soil. Under the action of water flow, heavy metal ions are absorbed and decomposed, realizing the immediate separation and discharge of pollutants, greatly enhancing the repair effect of electric field and flow field coupled repair; and effectively improving the engineering properties of the repaired soil.

[0014] Furthermore, the anode is always attached to one end of the soil and is made of hydrophilic carbon fiber cloth; the cathode is always attached to the other end of the soil and is made of hydrophilic graphite carbon felt. With this structure, both the anode and cathode remain in constant contact with the soil during the repair process, effectively overcoming the defects of current drop, increased energy consumption, and current instability caused by the soil separating from the electrodes. In other words, it maintains a normal and stable current and relatively reduces energy consumption.

[0015] Furthermore, the inner surfaces of the two side plates of the soil sampling tank have connecting structures to prevent the soil from detaching from the side plates. This structure helps reduce the likelihood of detachment during testing, mitigates boundary effects, ensures a uniform, continuous, and accurate repair process, and further improves the engineering properties of the repaired soil.

[0016] Furthermore, the inner surfaces of both side plates have continuous serrations, distributed perpendicular to the length direction and extending along the height direction. The inner surfaces of both side plates also have several pits for bonding the soil. With this specific structure, the side plates can be printed using 3D printing technology, which is convenient and quick to manufacture. This further ensures that the side plates are less likely to detach during testing, reduces boundary effects, ensures a uniform, continuous, and accurate repair process, and further improves the engineering properties of the repaired soil.

[0017] Furthermore, the water supply device for continuously supplying water to the anode tank is a Marvin bottle. The bottom end of the Marvin bottle is connected to the bottom end of the anode tank via a water supply pipe. The height of the outlet of the Marvin bottle is controlled so that the water level in the anode tank is always level with the top surface of the soil. With the above structure, the water supply device uses the water supply principle of the Marvin bottle to maintain a certain water head height, ensuring that the water flow can cover the entire soil. In addition, the vacuum method creates a pressure difference, which further ensures that the water replenishment is transformed into a seepage effect, thereby improving the repair efficiency, repair effect, and engineering properties of the repaired soil.

[0018] Furthermore, the vacuum assembly includes a water extraction pipe connecting the bottom of the cathode tank to the top of the gas-water separator, an air pipe connecting the top of the gas-water separator to the top of the negative pressure tank, and an air extraction pipe connecting the top of the negative pressure tank to the air inlet of the vacuum pump. A proportional valve is connected in series on the air extraction pipe. With the above specific structure, the vacuum assembly is simple in structure, stable and reliable in operation, and the vacuum level can be adjusted according to the needs of the actual repair process via the proportional valve. This further ensures continuous seepage and rinsing, thereby improving repair efficiency, repair effect, and the technical effect of improving the engineering properties of the repaired soil.

[0019] Furthermore, the anode-soil anchoring structure that ensures constant contact between the anode and the soil comprises several anchoring longitudinal rods, also known as multiple plastic nails, passing through the anode made of hydrophilic carbon fiber cloth and anchoring it to the soil. Each plastic nail's anchoring longitudinal rod on the outer side of the anode has a limiting crossbar at its outer end. This anode-soil anchoring structure, ensuring constant contact between the anode and the soil, is simple in structure, low in cost, easy to install, and has a good anchoring effect. It effectively overcomes the defects of increased interface resistance, decreased current, increased energy consumption, and unstable current caused by the separation of the soil from the electrode. In other words, it maintains normal and stable resistance and current, and relatively reduces energy consumption.

[0020] Another technical problem to be solved by the present invention is to provide a simulation test method for electrodynamic remediation of heavy metal contaminated soil that can leverage the coupling effect of electric field and flow field, significantly improve the remediation effect and efficiency, and effectively improve the engineering properties of the remediated soil.

[0021] Another technical solution of the present invention is to provide a simulation test method for electrokinetic remediation of heavy metal contaminated soil, which uses the electrokinetic remediation simulation test device for heavy metal contaminated soil described in the above technical solution to conduct simulation tests, including the following steps:

[0022] 1) Use clay, add heavy metal solution, stir thoroughly to form saturated soil slurry, pour into soil sample tank, vibrate and pre-compact the soil, and attach a sealing film to the top surface of the soil to seal the four walls; it is easy to understand that the purpose of pre-compacting the soil is to give the soil a certain strength, that is, to simulate the strength of soil at a certain depth in the actual repair site.

[0023] 2) Seal the top surface of the cathode tank with a sealing cover plate and start the DC power supply to form an electric field;

[0024] 3) The water supply device continuously supplies water as the rinsing fluid, and the vacuum assembly continuously evacuates the vacuum, so that the soil in the soil sample tank is always saturated and forms a unidirectional flow field from the anode to the cathode. The coupling effect of the electric field and the flow field separates and conducts heavy metal ions in the soil with the water flow. The anode made of hydrophilic carbon cloth is always in contact with the soil, and the cathode made of hydrophilic graphite carbon felt is also always in contact with the soil.

[0025] 4) The data acquisition component collects various data in real time, the computer calculates different relationships, draws different relationship diagrams, and selects the optimal parameters to provide reliable data support and technical guidance for in-situ electrokinetic remediation of heavy metal contaminated soil.

[0026] After adopting the above steps, the electrokinetic remediation simulation test method for heavy metal contaminated soil of the present invention has the following advantages:

[0027] This invention overcomes the limitations of existing electro-hydraulic remediation technologies and provides an experimental method for remediation under the coupling effect of electric and flow fields. Unlike existing technologies that use peristaltic pumps for drip-feeding, this invention employs a water supply device, such as a Marshall bottle, to control the water level in the anode tank to remain flush with the soil. Unlike existing technologies that use complete vacuum sealing, this invention only completely seals the cathode and soil sample tanks, leaving the anode tank unsealed. This ensures that the water flow is always in one direction, guaranteeing one-dimensional seepage of the leaching solution from the anode to the cathode. Furthermore, a vacuum pumping assembly continuously creates a vacuum to maintain continuous seepage of water throughout the soil and to keep the soil and cathode level. The contact creates a hydraulic gradient, transforming the existing technology's pre-test water injection or mid-test water replenishment into a continuous seepage effect. This makes the soil's moisture content and settlement more uniform under the influence of the flow field, reducing crack size to some extent, increasing the seepage rate of the leaching solution, improving the leaching repair efficiency, and solving the problem of single-electro-mechanical repair failing to activate and migrate refractory heavy metals in the soil. The convection-dispersion effect of the water flow promotes the migration of heavy metal ions, achieving immediate separation and discharge of pollutants, significantly enhancing the repair effect of electric field and flow field coupled repair; and effectively improving the engineering properties of the repaired soil.

[0028] This indoor simulation test method can be used for different types of clay, different heavy metal pollutants, different types of leachate, and different types of electrodes. It can comprehensively obtain data such as soil drainage, settlement, cracking degree, current, energy consumption, regional resistivity and potential value, and interface resistance, calculate different relationships, draw different relationship diagrams, and select the optimal parameters, providing reliable data support and technical guidance for in-situ remediation of heavy metal contaminated soil.

[0029] Furthermore, the side plates of the soil sampling tank are designed with connecting structures on their inner surfaces to prevent the soil from detaching from the side plates, thereby improving the uniformity and accuracy of the electric field and flow field coupling repair process. These steps effectively reduce side detachment and cracking during the test, mitigate boundary effects, make the repair process more uniform, continuous, and accurate, and further improve the engineering properties of the repaired soil.

[0030] Furthermore, saturated soil containing heavy metals is poured into a soil sampling tank in layers, and compacted and pre-loaded in three layers. The soil is divided into five equal regions along its length. A displacement sensor is installed on the top surface of the soil in each region to monitor the settlement of that region. A potential probe is installed between adjacent regions, near the anode, and near the cathode to monitor the potential difference. After these steps, the layered compaction and pre-loading ensure that the soil is as free of air bubbles as possible, because the test requires that the pores of the saturated soil be filled with water and free of air for better remediation results. The present invention uses zoning along the length, such as dividing the soil into five regions, to obtain the changes in each region through the potential probes and displacement sensors installed in different regions. This allows for analysis of the changes in each region over time along the length, rather than just analyzing the overall soil condition. This makes the collected data more accurate and practical, and provides stronger guidance for the in-situ remediation of heavy metal contaminated soil. Attached Figure Description

[0031] Figure 1 This is a front view schematic diagram of the positional and connection relationships of a preferred embodiment of the experimental device of the present invention.

[0032] Figure 2 This is a schematic diagram of a preferred embodiment of the test apparatus of the present invention, showing the soil sample tank divided into five regions along its length.

[0033] Figure 3 This is an exploded structural diagram of the heightened frame, sealing cover, box body, anode drainage plate and anode, plastic nails, and cathode drainage plate and cathode in the experimental device of this invention (bolts and nuts are not shown; the anode drainage plate and anode, cathode drainage plate and cathode are shown at different angles to show the relevant structures; the side plates do not show the connecting structure but are used separately). Figure 6 The connection structure is shown separately; the plastic nails are schematic and only a few are shown; screw or bolt through holes are not labeled.

[0034] Figure 4 yes Figure 3 A magnified structural diagram of A in the diagram.

[0035] Figure 5 yes Figure 3 A magnified structural diagram of B in the diagram.

[0036] Figure 6 This is a schematic diagram of the connection structure on the inner surface of the side plate.

[0037] As shown in the figure:

[0038] 1. Test chamber and vacuum seepage device; 11. Soil sample tank; 111. Side plate; 1111. Serrated edge; 1112. Pits; 12. Anode tank; 13. Cathode tank; 14. Sealing cover plate; 141. Wire through hole; 15. Marshall bottle; 151. Water outlet; 16. Water supply pipe; 17. Pumping pipe; 18. Gas pipe; 19. Soil; 1011. Gas-water separator; 1012. Pumping pipe; 1013. Vacuum pump; 10131. Air inlet; 1014. Proportional valve; 1015. Cathode drainage plate; 10151. Cathode drainage hole; 1016. Sealing membrane; 1017. Anode drainage plate; 10171. Anode drainage hole; 1018. Horizontal smooth rod;

[0039] 2. Electric actuator; 21. 60V DC power supply; 22. Anode; 23. Cathode; 24. Wire;

[0040] 3. Data acquisition components; 31. Displacement sensor; 32. Potential probe; 33. pH meter sensor; 331. pH composite electrode; 34. Computer; 35. Acquisition module; 36. 24V DC power supply.

[0041] 4. Plastic nails; 41. Anchoring longitudinal bars; 42. Limiting crossbars;

[0042] 5. Increase the height of the frame; 51. Increase the height of the flange plate. Detailed Implementation

[0043] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that these descriptions of specific embodiments are for the purpose of aiding understanding the present invention, but do not constitute a limitation thereof. Furthermore, the technical features involved in the various specific embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0044] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 As shown.

[0045] A preferred embodiment of the electrodynamic remediation simulation test device for heavy metal contaminated soil of the present invention includes a data acquisition component 3 and a test chamber. One end of the soil sample tank 11 of the test chamber has an anode 22 electrically connected to a DC power supply for the electric field, such as a 60V DC power supply 21, and the other end has a cathode 23 electrically connected to the DC power supply for the electric field, such as a 60V DC power supply 21. The present invention may also be described as an electrodynamic remediation simulation test device for heavy metal contaminated soil, or an electrodynamic remediation simulation test device for heavy metal contaminated soil.

[0046] A preferred embodiment of the electrodynamic remediation simulation test device for heavy metal contaminated soil of the present invention further includes a device for forming a flow field coupled with an electric field: an anode tank 12 located outside the anode 22 and communicating with water in the soil sample tank 11; a cathode tank 13 located outside the cathode 23 and communicating with water in the soil sample tank 11; a water supply device for continuously supplying water to the anode tank 12; and a vacuuming component for continuously evacuating the cathode tank 13 to maintain continuous seepage of water to the entire soil, or soil body 19, and to keep the soil body 19 in constant contact with the cathode 23. It is easy to understand that since the vacuum is always drawn from the cathode, both water and soil body 19 are attracted, water is drawn away, and the soil body 19 remains in close contact with the cathode 23. It is also easy to understand that the anode drainage plate 1017 divides the test chamber into the anode tank 12 and the soil sample tank 11; the cathode drainage plate 1015 divides the test chamber into the cathode tank 13 and the soil sample tank 11. The soil sample tank 11 can also be called a soil tank or soil trough. The water flow refers to the fact that water in the anode tank 12 can flow into the soil sample tank 11, and water in the soil sample tank 11 can flow into the cathode tank 13.

[0047] Preferably, the anode 22 can be made of hydrophilic carbon cloth and always attached to one end of the soil 19; the cathode 23 can be made of hydrophilic graphite carbon felt and always attached to the other end of the soil 19.

[0048] A preferred embodiment of the electrodynamic remediation simulation test device for heavy metal contaminated soil of the present invention further includes an anchoring structure between the anode 22 and the soil 19, which ensures that the anode 22 is always in contact with the soil 19.

[0049] The preferred anode-soil anchoring structure that ensures the anode 22 remains in constant contact with the soil 19 consists of several or more plastic nails 4 anchoring longitudinal rods 41 passing through the hydrophilic carbon fiber cloth anode 22 and anchoring it to the soil 19. Each plastic nail 4 anchoring longitudinal rod 41 on the outer side of the anode 22 has a limiting crossbar 42 at its outer end. The number of anchoring longitudinal rods can be as many as a dozen or several dozen.

[0050] Of course, the anchoring structure can also be other structures, such as several elongated Velcro fasteners fixed to the anode and facing into the soil sample trench; or several plastic wires fixed to the anode and facing into the soil sample trench, etc.

[0051] The top surface of the cathode tank 13 has a sealing cover plate 14. The sealing cover plate 14 can be fastened to the flange plate on the top surface of the cathode tank 13 by multiple screws and nuts. There can be a sealing gasket, such as a rubber gasket, between the sealing cover plate 14 and the top surface of the flange plate of the cathode tank 13.

[0052] The inner surfaces of the two side plates 111 of the soil sample tank 11 have a connection structure to prevent the soil 19 from detaching from the side plates 111. For example, the inner surfaces of the two side plates 111 have continuous serrations 1111, which are distributed perpendicular to the length direction and extend along the height direction. The inner surfaces of the two side plates 111 also have several pits 1112 for bonding the soil 19.

[0053] The specific shape of the connection structure can vary. For example, the serrations can extend horizontally; there can be only a single serration; there can be only a single recess; or there can be several protrusions, each of which can have multiple grooves, etc.

[0054] The preferred water supply device for continuously supplying water to the anode tank 12 is a Marshall bottle 15. The bottom end of the Marshall bottle 15 is connected to the bottom end of the anode tank 12 via a water supply pipe 16. The height of the outlet 151 of the Marshall bottle 15 is controlled so that the water level in the anode tank 12 is always level with the top surface of the soil 19. Water can generally be added to the Marshall bottle 15 manually.

[0055] The specific structure of the water supply device for continuously supplying water to the anode tank can vary. It may include a water pipe that continuously supplies water to the Marshall bottle. The water pipe may be connected to a water source such as a tap water pipe. A solenoid valve may be installed on the water pipe. The solenoid valve may be electrically connected to a central controller such as a computer. There may also be a water level sensor inside the Marshall bottle. The water level sensor may also be electrically connected to the central controller.

[0056] The vacuum assembly may include a water extraction pipe 17 connecting the bottom of the cathode tank 13 to the top of the gas-water separator 1011, an air pipe 18 connecting the top of the gas-water separator 1011 to the top of the negative pressure tank 1010, and an air extraction pipe 1012 connecting the top of the negative pressure tank 1010 to the air inlet 10131 of the vacuum pump 1013. A proportional valve 1014 is connected in series on the air extraction pipe 1012. The proportional valve 1014 can control the vacuum level according to the actual needs of the repair to ensure dynamic balance of the vacuum level. The gas-water separator 1011 may be placed on a gravity sensor, which serves as a weighing device. The gravity sensor may be electrically connected to a central controller, such as a computer 34, to monitor the ratio of extracted water to water supplied by the water supply device. It is easy to understand that the bottom of the gas-water separator 1011 may be equipped with a solenoid valve and a drain pipe for draining water. The solenoid valve may be electrically connected to the central controller, such as 34, to discharge wastewater containing heavy metals as needed.

[0057] A sealing membrane 1016 may be placed on the top surface of the soil in the soil sample tank 11, and the four sides of the sealing membrane 1016 are sealed to the inner wall of the rectangular soil sample tank 11.

[0058] The preferred embodiment of the electrodynamic remediation simulation test device for heavy metal contaminated soil described above in this invention will be further described below.

[0059] The experimental device of this invention can be used for different types of clay, different types of electrodes, different types of pollutants and different types of leaching liquids, and can comprehensively obtain data such as soil drainage, settlement, cracking degree, current, energy consumption, regional resistance and potential value, and interface resistance.

[0060] The experimental apparatus of this invention can be summarized into several main parts: a test chamber and a vacuum permeation device 1 or flow field device, an electric device 2 or electroosmosis device or electric field device, and a data acquisition component 3 or data acquisition device.

[0061] like Figure 1 and Figure 3 As shown, the test chamber includes an anode tank 12, a soil sample tank 11, and a cathode tank 13. The test chamber can be a rectangular box with dimensions of 350mm × 175mm × 100mm and can be made of transparent acrylic sheet. The structure is symmetrical from front to back and can be divided into three parts along its length: left, middle, and right. The left part is the anode tank 12, also known as the anode electrolysis tank, which can be supplied with rinsing solution such as water through the Marshall bottle 15. The middle part is the soil sample tank 11, also known as the soil zone. There can be an anode drainage plate 1017, also known as the first partition, between the anode tank 12 and the soil sample tank 11. The anode drainage plate 1017 can have several water passage holes, such as anode drainage holes 10171, also known as the first water passage holes. The right part is the cathode tank 13, also known as the cathode electrolysis tank. There can be a cathode drainage plate 1015, also known as the second partition, between the soil sample tank 11 and the cathode tank 13. The cathode drainage plate 1015 can have several water passage holes, such as cathode drainage holes 10151, also known as the second water passage holes. The top of the cathode tank 13 has a sealing cover plate 14 for sealing the cathode tank 13. The sealing cover plate 14 can be provided with a wire through hole 141 for passing through the wire 24. The wire through hole 141 and the wire 24 can be sealed with sealant. The cathode tank 13 can be in a mixed state of water and vacuum, or in a pure vacuum state; therefore, the cathode tank 13 can also be called a vacuum chamber. The test chamber is also called a model chamber or experimental chamber.

[0062] The electric device 2 includes a DC power supply such as a 60V DC power supply 21. For example, if a Maxtor MS605D DC power supply 21 is used, the maximum output can be 60V 5A. Both the anode 22 and the cathode 23 are electrically connected to the DC power supply 21 via wires 24. The DC power supply can be electrically connected to the current acquisition instrument described below to record real-time data.

[0063] It is not difficult to understand that the anode 22 and the anode drainage plate 1017 are only temporarily connected before the soil 19 is poured in. For example, two horizontal smooth rods 1018 are set on the upper part and the lower part of the side of the anode drainage plate 1017 facing the soil sample tank 11. The anode 22 made of hydrophilic carbon fiber cloth is temporarily hung on the anode drainage plate 1017 through the two holes at the top and the two holes at the bottom, and is in an up-and-down unfolded state. After the soil 19 is poured into the soil sample tank 11 and compacted and pre-pressed, the anode 22 made of hydrophilic carbon fiber cloth is attached to the soil 19 and is always in contact with the soil 19 under the anchoring effect of multiple plastic nails 4. The cathode 23 and the cathode drainage plate 1015 are only temporarily connected before the soil 19 is poured in. For example, two horizontal rods 1018 are set on the upper part and the lower part of the side of the cathode drainage plate 1015 facing the soil sample tank 11. The cathode 23, made of hydrophilic graphite carbon, is temporarily hung on the cathode drainage plate 1015 through the two holes at the top and the two holes at the bottom, and is in an up-and-down unfolded state. After the soil 19 is poured into the soil sample tank 11 and compacted and pre-pressed, the cathode 23 made of hydrophilic graphite carbon adheres to the soil 19 and is always in contact with the soil 19 under the vacuum action in the cathode direction. During the repair process, the cathode 23 is in a tight adhered state with the soil 19 and the cathode drainage plate 1015, while the anode 22 is in a tight adhered state with the soil 19, but is detached from the anode drainage plate 1017.

[0064] The anode 22 may be provided with the same number and diameter of anode drainage holes 10171 as the anode drainage holes 10171 on the anode drainage plate 1017, and the cathode 23 may be provided with the same number and diameter of cathode drainage holes 10151 as the cathode drainage holes 10151 on the cathode drainage plate 1015.

[0065] The vacuum percolation device has been described in detail above, and only supplementary explanations are provided here: a 4L Marsh bottle 15 can be used; a 750W vacuum pump 1013 can be used; the gas pipe 18 can be made of PU tubing; the gas-water separator 1010 can be made of transparent acrylic sheet, and the surface can be equipped with scale markings.

[0066] Data acquisition component 3, also known as data acquisition device, data acquisition apparatus, or data acquisition system, can be composed of a displacement sensor 31, a tungsten alloy potential probe 32 (or potential probe), a pH meter sensor 33, an acquisition module 35, an RS485 communication module, a current acquisition instrument, etc., all electrically connected to a host computer 34, which acts as the central controller. The displacement sensor 31 is fixed to the test chamber via a magnetic bracket. Data acquired by the sensors and probes is converted into software signals for the host computer 34 via the acquisition module 35 and the communication module, calibrating the required digital quantities. The pH meter sensor 33 simultaneously measures the pH changes in the cathode discharge water and the anolyte electrolysis cell. A high-definition camera can be mounted on the top of the transparent soil sample tank 11 to record the development of cracks in the soil 19; the high-definition camera is also electrically connected to the computer 34. The electrical connections described above can be made using a 24V DC power supply 34 connected via wire 24. The pH sensor 33 can be connected to the pH composite electrode 331, which can be placed inside the gas-liquid separator 1011.

[0067] A preferred embodiment of the electrokinetic remediation simulation test method for heavy metal contaminated soil of the present invention uses the electrokinetic remediation simulation test device for heavy metal contaminated soil described in the above technical solution to conduct a simulation test, including the following steps:

[0068] 1) Clay is mixed with a heavy metal solution to form a saturated slurry, which is then poured into the soil sample tank 11, compacted, and pre-loaded onto the soil body 19. A sealing film 1016, which seals the four walls, is then attached to the top surface of the soil body 19. At this point, both the anode 22 and the cathode 23 are in close contact with the soil body 19. It is easy to understand that, as described above, the purpose of pre-loading the soil body 19 is to give it a certain strength, which simulates the strength of soil at a certain depth in the actual repair site.

[0069] Clay, also known as clay, can be understood as soil with poor permeability, such as kaolin, dewatered river sludge, and dewatered tidal flat silt. Heavy metal solutions include solutions containing metals such as lead, cobalt, nickel, cadmium, mercury, copper, and zinc.

[0070] 2) Seal the top surface of the cathode tank 13 with a sealing cover plate 14, and start the DC power supply such as a 60V DC power supply 21 to form an electric field.

[0071] 3) The water supply device continuously supplies water as the leaching fluid, and the vacuum assembly continuously creates a vacuum, ensuring that the soil 19 in the soil sample tank 11 remains saturated. This creates a unidirectional flow field where the leaching fluid continuously flows from the anode 22 to the cathode 23. The coupling effect of the electric field and the flow field separates and removes heavy metal ions from the soil 19 with the water flow. The anchoring structure between the anode 22 and the soil 19 ensures that the anode 22 and the soil 19 remain in constant contact. It is easy to understand that the vacuum ensures that the soil 19 remains in constant contact with the cathode 23.

[0072] 4) Various data are collected in real time by the data acquisition component 3, and the computer 34 calculates different relationships, draws different relationship diagrams, and selects the optimal parameters to provide reliable data support and technical guidance for in-situ electrodynamic remediation of heavy metal contaminated soil.

[0073] The two side plates 111 of the soil sample tank 11 are equipped with a connection structure on the inner surface to prevent the soil 19 from separating from the side plate 111, so as to improve the uniformity and accuracy of the electric field and flow field coupling repair process.

[0074] Saturated soil slurry containing heavy metals is poured into soil sample tank 11 in layers, and compacted and pre-pressed in three layers. The soil body 19 is divided into five regions along its length. The top surface of the soil body 19 is covered with a sealing film 1016 that seals the four walls. Here, it means that the top surface of the top layer is covered with a sealing film 1016. A displacement sensor 31 for monitoring the settlement of each region is installed on the top surface of the soil body 19. Figure 2 In the five different regions A, B, C, D, and E shown, a potential probe 32 for monitoring the potential difference is installed between the soil bodies 19 of two adjacent regions, as well as at the soil body 19 near the anode 22 and the soil body 19 near the cathode 23.

[0075] An experiment is also called a test.

[0076] The preferred embodiments of the electrodynamic remediation simulation test method for heavy metal contaminated soil described above in this invention will be further explained below.

[0077] Pre-compacting the soil 19 gives it a certain strength. This is because the soil contaminated with heavy metals in situ already possesses some strength due to its location within a former work or living area; pre-compacting makes it more closely resemble the remediation site. A raised frame 5, made of a separate acrylic sheet, can be used for pre-compacting. The shape and dimensions of the raised frame 5 can match the shape and internal dimensions of the soil sampling tank 11. The raised frame 5 is secured to the top surface of the soil sampling tank 11 using two symmetrical flange plates 51 and multiple screws. Soil slurry is poured into the raised frame 5, and the slurry above the top surface of the soil sampling tank 11 is then vibrated using a downward external force until it is compacted and the top surface of the soil 19 is lower than the top surface of the soil sampling tank 11. After disassembling the raised frame 5, the soil 19 remediation test is then conducted.

[0078] The sealing film 1016 on the top surface of the compacted soil 19 can be made of plastic wrap.

[0079] Potential probes 32 are inserted between each pair of soil sections 19, and at points on soil sections 19 near the anode 22 and the cathode 23, respectively, to acquire real-time potential changes. Displacement sensors 31 are placed on the top surface at the midpoint of different areas of soil section 19 to acquire real-time settlement changes. Water pumped from soil section 19 flows through pumping pipe 17 into gas-water separator 1011, where it is measured in real-time by a gravity sensor. During the experiment, the following parameters are recorded in real-time over time using a data acquisition device: drainage volume, current, potential, settlement, and pH value.

[0080] In the anode tank 12, a Martens bottle 15 is used to control the head difference for water supply. A vacuum pump 1013 is used to simulate the corresponding head difference. In the soil sample tank 11 of the test chamber, a combined electric and fluid field coupled rinsing test was conducted on soil 19 containing heavy metals under different conditions. The test can be conducted by applying different rinsing solutions, different heavy metal solutions, and different concentrations of heavy metals to the soil 19. By adjusting different voltage gradients and vacuum degrees or hydraulic gradients, comparative experimental data with different factors can be obtained. During the test, indicators such as current, potential, pH value of anode and cathode, drainage volume, water content, settlement, and energy consumption are monitored.

[0081] After the test, level the top surface of the soil (19), see [reference]. Figure 2 The soil strength was measured at the midpoint of the five different regions mentioned above, namely A, B, C, D, and E, using a miniature penetrator electrically connected to a computer 34.

[0082] Each section, i.e., the soil from five different areas, was completely excavated and sampled from three layers (upper, middle, and lower) for moisture content determination.

[0083] By reading monitoring data, comparative analysis was conducted on the following graphs: current over time, potential over time and location, pH over time, drainage and water replenishment over time, settlement distance over time and location, moisture content over location, soil strength over location, crack development patterns, and microscopic mechanisms.

[0084] The relationship between the electroosmotic coefficient and time and energy consumption was calculated.

[0085] Selecting the optimal parameters for subsequent use provides reliable data support and technical guidance for in-situ electrokinetic remediation of heavy metal contaminated soil.

[0086] Furthermore, compared with the results of single electric remediation in the prior art, the results of this invention, in addition to the advantages mentioned above, show more uniform soil consolidation, more obvious consolidation and drainage effects, and a corresponding reduction in cracks; it does not produce heavy metal ion pollution, has no secondary pollution, reduces anodic electrode corrosion, and solves many problems of single electric remediation such as long remediation time, low remediation efficiency, soil alkalization, uncertain duration of remediation effectiveness, and damage to soil structure, thus exhibiting outstanding stability.

[0087] Components, structures, or quantities not marked above are not shown in the drawings, and some components are not marked in the drawings. The drawings are for illustrative purposes only. In case of any inconsistency between the drawings and the text description, or between the drawings themselves, the text description shall prevail.

[0088] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A simulation test device for electrodynamic remediation of heavy metal contaminated soil, comprising a data acquisition component and a test chamber, wherein one end of the soil sample tank of the test chamber has an anode electrically connected to a DC power supply for an electric field, and the other end has a cathode electrically connected to a DC power supply for an electric field; further comprising an anode-soil anchoring structure to ensure that the anode is always in contact with the soil; characterized in that: It also includes devices that form a flow field coupled with an electric field: an anode tank located outside the anode and connected to the water in the soil sample tank, a cathode tank located outside the cathode and connected to the water in the soil sample tank, a water supply device that continuously supplies water to the anode tank, and a vacuuming component that continuously evacuates the cathode tank to keep the water continuously seeping into the entire soil and to keep the soil in constant contact with the cathode. The top surface of the cathode tank is covered with a sealing cover, the anode tank is not sealed, and the top surface of the soil in the soil sample tank is provided with a sealing membrane that seals with the four walls of the soil sample tank. The water supply device uses a Marshall bottle to continuously supply water as the rinsing fluid, and the vacuum assembly continuously evacuates the vacuum. The soil in the soil sample tank is always saturated, and a unidirectional flow field is formed in which the rinsing fluid always flows from the anode to the cathode. The coupling effect of the electric field and the flow field separates and drains the heavy metal ions in the soil with the water flow. The anode made of hydrophilic carbon cloth is always in contact with the soil, and the cathode made of hydrophilic graphite carbon felt is also always in contact with the soil. The two side plates of the soil sample tank are made of side plates with a connection structure on the inner surface to prevent the soil from separating from the side plate. This reduces the possibility of the side plates separating during the test, mitigates the boundary effect, and makes the repair process more uniform, continuous and accurate.

2. The heavy metal contaminated soil electrokinetic remediation simulation test device according to claim 1, characterized in that: The inner surfaces of both side plates have continuous serrations, which are distributed perpendicular to the length direction and extend along the height direction. The inner surfaces of both side plates also have several pits for bonding the soil. 3.The heavy metal contaminated soil electrokinetic remediation simulation test device according to claim 1, characterized in that: The water supply device that continuously supplies water to the anode tank is a Marshall bottle. The bottom end of the Marshall bottle is connected to the bottom end of the anode tank via a water supply pipe. The height of the outlet of the Marshall bottle is controlled so that the water level in the anode tank is always level with the top surface of the soil.

4. The heavy metal contaminated soil electrokinetic remediation simulation test device according to claim 1, characterized in that: The vacuum assembly includes a water extraction pipe connecting the bottom of the cathode tank to the top of the gas-water separator, an air pipe connecting the top of the gas-water separator to the top of the negative pressure tank, an air extraction pipe connecting the top of the negative pressure tank to the air inlet of the vacuum pump, and a proportional valve connected in series on the air extraction pipe.

5. The electrokinetic remediation simulation test device for heavy metal contaminated soil according to claim 1, characterized in that: The anode-soil anchoring structure that ensures the anode remains in constant contact with the soil consists of several anchoring rods made of hydrophilic carbon fiber cloth passing through the anode and anchoring it to the soil. Each anchoring rod on the outer side of the anode has a limiting crossbar at its outer end.

6. A method for simulating electrokinetic remediation of heavy metal contaminated soil, comprising using the electrokinetic remediation simulation apparatus for heavy metal contaminated soil as described in any one of claims 1-5, characterized in that, Includes the following steps: 1) Use clay, add heavy metal solution, stir thoroughly to form saturated soil slurry, pour into soil sample tank, vibrate and pre-press the soil, and attach a sealing film to the top surface of the soil to seal the four walls. 2) Seal the top surface of the cathode tank with a sealing cover plate and start the DC power supply to form an electric field; 3) The water supply device continuously supplies water as the rinsing fluid, and the vacuum assembly continuously evacuates the vacuum. The soil in the soil sample tank is always saturated, and the rinsing fluid always flows in a unidirectional flow from the anode to the cathode. The coupling effect of the electric field and the flow field separates and drains the heavy metal ions in the soil with the water flow. The anode made of hydrophilic carbon cloth is always in contact with the soil, and the cathode made of hydrophilic graphite carbon felt is also always in contact with the soil. 4) The data acquisition component collects various data in real time, the computer calculates different relationships, draws different relationship diagrams, and selects the optimal parameters to provide reliable data support and technical guidance for in-situ electrodynamic remediation of heavy metal contaminated soil.

7. The method for simulating electrokinetic remediation of heavy metal contaminated soil according to claim 6, characterized in that: Saturated soil slurry containing heavy metals was poured into the soil sample tank in layers and compacted and pre-pressed in three layers. The soil was divided into five equal regions along its length. A displacement sensor was installed on the top surface of the soil in each region to monitor the settlement of each region. A potential probe was installed between the soil in two adjacent regions, as well as near the anode and near the cathode to monitor the potential difference.

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