Heavy metal contaminated soil electrokinetic remediation simulation test device and method thereof

Abstract

The invention discloses a heavy metal contaminated soil electrokinetic remediation simulation test device and method, the device comprises a data acquisition assembly and a test box, one end of a soil sample tank of the test box is provided with an anode electrically connected with a direct current power supply of an electric field, and the other end is provided with a cathode electrically connected with the direct current power supply of the electric field; the anode tank is arranged on the outer side of the anode and is communicated with water in the soil sample tank; the cathode tank is arranged on the outer side of the cathode and is communicated with water in the soil sample tank; the water supply device is used for continuously supplying water to the anode tank; the vacuumizing assembly is used for continuously vacuumizing the cathode tank so that the water continuously keeps a seepage effect from the whole soil body and the soil body is always in contact with the cathode; the anode and soil body anchoring structure enables the anode and the soil body to be in contact all the time; and a sealing cover plate is arranged on the top surface of the cathode tank. The electric field and flow field coupling effect can be achieved, the repairing effect and repairing efficiency are greatly improved, and the engineering characteristics of the repaired soil body are effectively improved.

Description

Technical Field

[0001] The present invention relates to the technical field of contaminated soil remediation, in particular to a heavy metal contaminated soil electric remediation simulation test device and method. Background Art

[0002] Heavy metal contamination of soil has become one of the most concerning ecological and environmental issues. As an emerging soil remediation technology, electroremediation is considered one of the most promising techniques for separating heavy metal contaminants from soil. It primarily relies on electromigration and electroosmosis to remove heavy metals from contaminated soil, and is suitable for remediating soils with poor permeability, such as clay.

[0003] As an emerging technology, electric remediation technology is still in the initial exploration and development stage. In particular, since on-site electric remediation of heavy metal contaminated soil is a huge project, once implemented, it must be supported by high voltage and complete construction safety facilities, high investment in various large-scale instruments and equipment, and large energy consumption costs and labor costs during the construction process. Therefore, in order to ensure the maturity and the highest possible success rate of on-site electric remediation technology for heavy metal contaminated soil, many universities and research institutions have adopted a scientific and pragmatic attitude, starting with indoor simulation test equipment and test methods. After countless simulation tests, they have provided scientific, practical and rigorous data support and technical guidance to improve the efficiency of electric remediation of heavy metal soil, and ultimately to apply it to on-site electric remediation of heavy metal contaminated soil and achieve the predetermined remediation goals.

[0004] For example, the patent discloses a simulation test device and test method for the electrokinetic remediation of heavy metal-contaminated soil. The simulation test device includes a soil sample test box, which includes a sealed soil sample trough lid. The trough has an anode electrically connected to a DC power supply at one end and a cathode electrically connected to a DC power supply at the other end. The device is also equipped with a liquid injection device, a barometer, a temperature sensor, a humidity sensor, a moisture content sensor, a pH sensor, and data recording, storage, and timing devices. Heavy metal-contaminated soil samples that meet actual conditions can be prepared based on actual needs. The device can monitor soil moisture content, cathode soil pH, ambient temperature, ambient humidity, and air pressure changes, as well as soil current changes during the electrokinetic remediation process of heavy metal-contaminated soil in real time, providing reliable data support and technical guidance for on-site electrokinetic remediation of heavy metal-contaminated soil.

[0005] However, the existing simulation test devices and test methods for electrokinetic remediation of heavy metal contaminated soil still have the following deficiencies: 1. Basically, it belongs to pure electrokinetic remediation. During the remediation process, liquid injection provides the function of water replenishment. During the remediation process, only the electric field acts. It is difficult to achieve the activation and migration of insoluble heavy metals in the soil or soil mass during the electrokinetic remediation process, and it is difficult to achieve an ideal remediation effect; its remediation efficiency is also affected. 2. Due to the only electric field acting as described above, the electrokinetic remediation process causes greater damage to the soil mass. Under the action of electrode heating and electrophoresis, uneven settlement of the soil mass will occur, the moisture content distribution will be uneven, and the soil pores will change, resulting in soil cracking and changes in soil properties. 3. In indoor model tests, since the inner surface of the test tank is generally relatively smooth, the contact friction between the soil mass and the inner surface is low. During the electrokinetic remediation process, the soil mass on both sides sometimes detaches from the side plates. Instead of flowing uniformly through the entire soil mass and the water containing heavy metal ions being carried away from the cathode, the water flows away from the detachment points on both sides, thereby reducing the uniformity and accuracy of the electrokinetic remediation process and being unfavorable for improving the engineering properties of the soil mass after remediation. Summary of the Invention

[0006] One technical problem to be solved by the present invention is to provide a simulation test device for electrokinetic remediation of heavy metal contaminated soil that can exert the coupling effect of the electric field and the flow field, can greatly improve the remediation effect and efficiency, and effectively improve the engineering properties of the soil mass after remediation.

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

[0008] The simulation test device for electrokinetic remediation of heavy metal contaminated soil of the present invention further includes a device for constituting a flow field coupled with the electric field: an anode tank provided outside the anode and in water communication with the soil sample tank, a cathode tank provided outside the cathode and in water communication with the soil sample tank, a water supply device for continuously supplying water to the anode tank, and a vacuum pumping component for continuously pumping the cathode tank to keep the water continuously percolating through the entire soil mass and keep the soil mass in contact with the cathode all the time;

[0009] The simulation test device for electrokinetic remediation of heavy metal contaminated soil of the present invention further includes an anchoring structure for the anode and the soil mass to keep the anode in contact with the soil mass all the time;

[0010] The top surface of the cathode tank has a sealing cover plate.

[0011] After adopting the above structure, the simulation test device for electrokinetic remediation of 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 leaching solutions, different types of electrodes, etc. It can comprehensively obtain data such as the drainage volume, settlement amount, cracking degree, current, energy consumption, regional resistance and potential value, and interface resistance of the soil mass, calculate different relationships, draw different relationship diagrams, and select the optimal parameters to provide reliable data support and technical guidance examples for the in-situ remediation of heavy metal contaminated soil on-site.

[0013] The present invention overcomes the limitations of the existing electrokinetic remediation technology and provides a test device for remediation under the coupled action of an electric field and a flow field. Different from the existing technology that uses a peristaltic pump to drip and replenish water, the water supply device such as a Mariotte bottle can control the water surface height of the anode tank to always be flush with the soil; different from the completely vacuum-sealed situation of the existing technology, the present invention only completely seals the cathode tank and the soil sample tank, and does not seal the anode tank, always keeping the water flow in one direction to ensure the one-dimensional seepage effect of the leaching solution from the anode to the cathode. And the vacuum pumping assembly continuously pumps vacuum to keep the water continuously seeping through the entire soil mass and keep the soil in contact with the cathode all the time, forming a pressure difference, thus changing the function of pre-injecting water or replenishing water during the test in the existing technology into a continuous seepage effect all the time. This makes the soil moisture content and the soil settlement amount more uniform under the action of the flow field, reduces the cracks to a certain extent, increases the seepage velocity of the leaching solution, improves the remediation efficiency of leaching, and solves the problem that it is difficult to activate and migrate insoluble heavy metals in the soil mass by single electrokinetic remediation. Under the action of water flow, heavy metal ions are absorbed and desorbed, realizing the instant separation and drainage of pollutants, greatly enhancing the remediation effect of the coupled remediation of the electric field and the flow field; effectively improving the engineering properties of the soil mass after remediation.

[0014] Furthermore, the anode is an anode made of hydrophilic carbon energy carbon cloth that always adheres to one end of the soil mass; the cathode is a cathode made of hydrophilic graphite carbon felt that always adheres to the other end of the soil mass. After adopting the above structure, during the remediation process, both the anode and the cathode can always be in contact with the soil mass, effectively overcoming the defects of current drop, increased energy consumption, and current instability caused by the disconnection of the soil mass from the electrodes, that is, it can maintain a normal and stable current and can relatively reduce energy consumption.

[0015] Furthermore, there is a connection structure on the inner surfaces of the two side plates of the soil sample tank to prevent the soil mass from detaching from the side plates. After adopting the above structure, it is beneficial to reduce the situation of detachment on the side during the test, can reduce the boundary effect, make the remediation process uniform, continuous and accurate, and further improve the engineering properties of the soil mass after remediation.

[0016] Furthermore, the inner surfaces of both side plates have continuous sawteeth, which are distributed perpendicular to the length direction and extend along the height direction. There are also several pits for bonding the soil body on the inner surfaces of both side plates. After adopting the above specific structure for the connection structure to prevent the soil body from detaching from the side plates, the side plates can be printed using 3D printing technology, which is convenient and fast to manufacture, and further ensures the technical effects of reducing the situation of side detachment during the test, reducing the boundary effect, making the repair process uniform, continuous and accurate, and further improving the engineering properties of the repaired soil body.

[0017] Furthermore, the water supply device for continuously supplying water to the anode tank is a Mariotte bottle. The bottom end of the Mariotte bottle is connected to the bottom end of the anode tank through a water supply pipe, and the height of the water outlet of the Mariotte bottle is controlled so that the water surface height of the anode tank always remains level with the top surface height of the soil body. After adopting the above structure, the water supply device adopts the water supply principle of the Mariotte bottle to maintain a certain water head height, ensuring that the water flow can cover the entire soil body. Coupled with the method of pumping vacuum to create a pressure difference, it further ensures the technical effects of transforming the water replenishment effect into a seepage effect, improving the repair efficiency, repair effect, and engineering properties of the repaired soil body.

[0018] Furthermore, the vacuum pumping assembly includes a water pumping pipe connecting the bottom end of the cathode tank to the top end of the gas-water separation tank, a gas pipe connecting the top end of the gas-water separation tank to the top end of the negative pressure tank, a vacuum pumping pipe connecting the top end of the negative pressure tank to the intake port of the vacuum pump, and a proportional valve is connected in series on the vacuum pumping pipe. After adopting the above specific structure for the vacuum pumping assembly, its structure is simple, the working process is stable and reliable, and the vacuum degree can be adjusted through the proportional valve according to the actual needs of the repair process, thereby further ensuring the technical effects of continuous seepage leaching, improving the repair efficiency, repair effect, and engineering properties of the repaired soil body.

[0019] Furthermore, the anode and soil body anchoring structure for keeping the anode in contact with the soil body all the time is that several anchoring longitudinal rods, also known as multiple plastic nails, pass through the anode made of hydrophilic carbon energy carbon cloth and are anchored to the soil body. There is a limiting cross bar at the outer end of each anchoring longitudinal rod of the plastic nails outside the anode. After adopting the above specific structure for the anode and soil body anchoring structure for keeping the anode in contact with the soil body all the time, its structure is simple, the cost is low, the installation is convenient, and it has a good anchoring effect, which can effectively overcome the defects of increased interface resistance, decreased current, increased energy consumption, and unstable current caused by the detachment of the soil body from the electrode, that is, it can maintain normal and stable resistance and current, and can relatively reduce energy consumption.

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

[0021] Another technical solution of the present invention is to provide a method for simulating the electrokinetic remediation of heavy metal contaminated soil. The simulation test is carried out by using the electrokinetic remediation simulation test device for heavy metal contaminated soil described in the above technical solution, and the method includes the following steps:

[0022] 1). Use clay, add heavy metal solution, stir well to form saturated slurry, then pour it into the soil sample tank, vibrate and compact it, and pre-press the soil body. A sealing film that is sealed with the four walls is pasted on the top surface of the soil body. It is not difficult to understand that the function of pre-pressing the soil body is to make the soil body have a certain strength, and the so-called certain strength is to simulate the strength of the soil body with a certain depth at the actual remediation 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 leaching solution, and the vacuum extraction component continuously extracts vacuum. The soil body in the soil sample tank is always in a saturated state, and a flow field is formed in which the leaching solution always seeps unidirectionally 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 body along with the water flow. The anode made of hydrophilic carbon cloth always contacts the soil body, and the cathode made of hydrophilic graphite carbon felt also always contacts the soil body.

[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 examples for the in-situ electrokinetic remediation of heavy metal contaminated soil at the site.

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

[0027] The present invention overcomes the limitations of the existing electrokinetic remediation technology and provides a test method for remediation under the coupled action of an electric field and a flow field. Different from the existing technology that uses a peristaltic pump to drip water for replenishment, a water supply device such as a Mariotte bottle is used to control the water level in the anode tank to always be flush with the soil mass. Different from the completely vacuum-sealed situation in the existing technology, in the present invention, only the cathode tank and the soil sample tank are completely sealed, and the anode tank is not sealed. The water flow is always in one direction to ensure the one-dimensional seepage effect of the leaching solution from the anode to the cathode. Moreover, a vacuum pumping assembly is used to continuously pump vacuum to enable the water to continuously seep through the entire soil and keep the soil mass in contact with the cathode all the time, forming a hydraulic gradient, thus turning the function of injecting water before the test or replenishing water during the test in the existing technology into a continuously seeping function all the time. The properties such as the water content of the soil mass and the settlement of the soil mass become more uniform under the action of the flow field, the cracks are reduced to a certain extent, the seepage velocity of the leaching solution is increased, the remediation efficiency of leaching is improved, and the problem that it is difficult to activate and migrate the insoluble heavy metals in the soil mass by single electrokinetic remediation is solved. The convection-dispersion effect of the water flow promotes the migration of heavy metal ions, realizing the instant separation and drainage of pollutants, greatly enhancing the remediation effect of the coupled remediation of the electric field and the flow field, and effectively improving the engineering properties of the soil mass after remediation.

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

[0029] Furthermore, the two side plates of the soil sample tank adopt side plates with a connection structure on the inner surface to prevent the soil mass from detaching from the side plates, so as to improve the uniformity and accuracy of the coupled remediation process of the electric field and the flow field. After adopting the above steps, the situations of side detachment and cracking during the test are effectively reduced, the boundary effect is alleviated, the remediation process is made more uniform, continuous and accurate, and the engineering properties of the soil mass after remediation are further improved.

[0030] Further, the saturated soil slurry containing heavy metals is poured into the soil sample tank in layers, compacted and preloaded in three layers, and the soil body is evenly divided into five regions along the length direction. A displacement sensor for monitoring the settlement of each region is provided on the top surface of the soil body in each region, and a potential measuring needle for monitoring the potential difference is provided between the soil bodies in adjacent two regions, at the soil body near the anode and at the soil body near the cathode respectively. After adopting the above steps, through layer-by-layer compaction and preloading, the soil body is made to have as few air bubbles as possible. Because the test requires that the pores of the saturated soil must be filled with water and no air, the repair effect will be better in this way. In the present invention, the length direction is divided into regions, such as five regions. By means of the potential measuring needles and displacement sensors provided in different regions, the change amount of each region can be obtained, and then the data of each region changing with time can be analyzed in the length direction, rather than only being able to analyze the overall situation of the soil body, making the collected data more accurate and more practical, and having a stronger practical guiding significance for the in-situ heavy metal contaminated soil repair on site. Brief Description of the Drawings

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

[0032] Figure 2 is a schematic diagram of the soil sample tank of the preferred embodiment of the test device of the present invention divided into five regions along the length direction.

[0033] Figure 3 is an exploded structure schematic diagram of the heightening frame, the sealing cover plate, the box body, the anode drainage plate and the anode, the plastic nails and the cathode drainage plate and the cathode in the test device of the present invention (the bolts and nuts are not shown; the anode drainage plate and the anode, the cathode drainage plate and the cathode are shown at different angles for showing relevant structures; the connection structure of the side plate is not shown but is separately shown Figure 6 separately; the plastic nails are schematic and only several of them are shown; the screw through holes or bolt through holes are not marked).

[0034] Figure 4 is Figure 3 an enlarged structure schematic diagram of A in

[0035] Figure 5 is Figure 3 an enlarged structure schematic diagram of B in

[0036] Figure 6 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. Serrations, 1112. Pit, 12. Anode tank, 13. Cathode tank, 14. Sealing cover, 141. Wire hole, 15. Malvern flask, 151. Water outlet, 16. Water supply pipe, 17. Water extraction pipe, 18. Air pipe, 19. Soil, 1011. Air-water separator tank, 1012. Extraction pipe, 1013. Vacuum pump, 10131. Air inlet, 1014. Proportional valve, 1015. Cathode drain plate, 10151. Cathode drain hole, 1016. Sealing membrane, 1017. Anode drain plate, 10171. Anode drain hole, 1018. Horizontal polished rod;

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

[0040] 3. Data acquisition component, 31. Displacement sensor, 32. Potential measuring needle, 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 rod, 42. Limiting cross bar;

[0042] 5. Raise the frame, 51. Raise the flange plate. DETAILED DESCRIPTION

[0043] The following is a further description of specific embodiments of the present invention with reference to the accompanying drawings. It should be noted that the description of these specific embodiments is intended to facilitate understanding of the present invention and does not constitute a limitation of the present invention. Furthermore, the technical features involved in the various specific embodiments of the present invention described below may 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 shown.

[0045] A preferred embodiment of the present invention's simulated test device for electrokinetic remediation of heavy metal-contaminated soil includes a data acquisition component 3 and a test chamber. The test chamber's soil sample trough 11 includes an anode 22 electrically connected to an electric field DC power source, such as a 60V DC power source 21, at one end and a cathode 23 electrically connected to an electric field DC power source, such as a 60V DC power source 21, at the other end. The present invention may also be referred to as a simulated test device for electrokinetic remediation of heavy metal-contaminated soil or a simulated test device for electrokinetic remediation of heavy metal-contaminated soil.

[0046] Preferred embodiment of the electric remediation simulation test device for heavy metal contaminated soil of the present invention further includes a device for forming a flow field coupled with the electric field: an anode tank 12 provided outside the anode 22 and in water communication with the soil sample tank 11, a cathode tank 13 provided outside the cathode 23 and in water communication with the soil sample tank 11, a water supply device for continuously supplying water to the anode tank 12, and a vacuum extraction assembly for continuously evacuating the cathode tank 13 to enable water to continuously maintain a seepage effect on the entire soil or soil mass 19 and keep the soil mass 19 in contact with the cathode 23 at all times. It is not difficult to understand that the vacuum is always extracted from the cathode. Therefore, both water and the soil mass 19 are attracted, the water is pumped away, and the soil mass 19 always adheres to and contacts the cathode 23. It is not difficult 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 referred to as a soil mass tank or a soil tank. The so-called "water communication" means that the water in the anode tank 12 can flow into the soil sample tank 11, and the water in the soil sample tank 11 can flow into the cathode tank 13.

[0047] Preferably, the anode 22 can be an anode 22 made of hydrophilic carbon energy carbon cloth that always adheres to one end of the soil mass 19; the cathode 23 can be a cathode 23 made of hydrophilic graphite carbon felt that always adheres to the other end of the soil mass 19.

[0048] Preferred embodiment of the electric 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 mass 19 that keeps the anode 22 in contact with the soil mass 19 at all times.

[0049] The preferred anchoring structure between the anode and the soil mass that keeps the anode 22 in contact with the soil mass 19 is that the anchoring longitudinal rods 41 of several or multiple plastic nails 4 pass through the anode 22 made of hydrophilic carbon energy carbon cloth and are anchored to the soil mass 19, and there is a limiting cross bar 42 at the outer end of each anchoring longitudinal rod 41 of the plastic nail 4 outside the anode 22. Multiple, such as a dozen, dozens, etc.

[0050] Of course, this anchoring structure can also be other structures, such as several elongated magic tapes fixed on the anode and facing into the soil sample tank; or several plastic wires fixed on the anode and facing into the soil sample tank, etc.

[0051] The top surface of the cathode tank 13 has a sealing cover plate 14. The sealing cover plate 14 can be fixed to the flange plate on the top surface of the cathode tank 13 by multiple screws and nuts, and 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] On the inner surfaces of the two side plates 111 of the soil sample tank 11, there are connection structures for preventing the soil body 19 from detaching from the side plates 111. For example, on the inner surfaces of both side plates 111, there are continuous sawteeth 1111. The sawteeth 1111 are distributed perpendicular to the length direction and extend along the height direction. There are also several pits 1112 for bonding the soil body 19 on the inner surfaces of the two side plates 111.

[0053] The specific shape of this connection structure is allowed to vary. For example, the sawteeth can extend in the horizontal direction; there can be only individual sawteeth; there can be only individual pits; or there can be several convex columns, and each convex column can have multiple grooves, etc.

[0054] The water supply device for continuously supplying water to the anode tank 12 is preferably a Mariotte bottle 15. The bottom end of the Mariotte bottle 15 is connected to the bottom end of the anode tank 12 through a water supply pipe 16. The height of the water outlet 151 of the Mariotte bottle 15 is controlled so that the water surface height of the anode tank 12 always remains level with the top surface height of the soil body 19. Generally, the Mariotte bottle 15 can be manually replenished with water.

[0055] The specific structure of the water supply device for continuously supplying water to the anode tank is allowed to vary. There can be a water pipe for continuously supplying water to the Mariotte bottle. The water pipe can be connected to a water source such as a tap water pipe. An electromagnetic valve can be installed on the water pipe, and the electromagnetic valve can be electrically connected to a central controller such as a computer. There can also be a water level sensor in the Mariotte bottle, and the water level sensor can also be electrically connected to the central controller.

[0056] The vacuum extraction assembly can include a water extraction pipe 17 connecting the bottom end of the cathode tank 13 to the top end of the gas-water separation tank 1011. An air pipe 18 connects the top end of the gas-water separation tank 1011 to the top end of the negative pressure tank 1010. A suction pipe 1012 connects the top end of the negative pressure tank 1010 to the intake port 10131 of the vacuum pump 1013. A proportional valve 1014 is connected in series on the suction pipe 1012. The proportional valve 1014 can control the vacuum degree according to the actual needs of the repair to ensure the dynamic balance of the vacuum degree. The gas-water separation tank 1011 can be placed on a gravity sensor, and the gravity sensor is used for weighing. The gravity sensor can be electrically connected to a central controller such as a computer 34 to monitor the ratio of the extracted water to the water supplied by the water supply device. It is not difficult to understand that a solenoid valve and a drain pipe for discharging water can be provided at the bottom end of the gas-water separation tank 1011. The solenoid valve can be electrically connected to a central controller such as 34 to discharge the heavy metal-containing sewage as needed.

[0057] On the top surface of the soil body in the soil sample tank 11, there can be a sealing film 1016, and the four sides of the sealing film 1016 are sealed with the inner wall of the rectangular soil sample tank 11.

[0058] Next, the preferred embodiment of the above-mentioned heavy metal-contaminated soil electrokinetic remediation simulation test device of the present invention will be further supplemented and described as follows.

[0059] The test device of the present invention can be used for different types of clay, different types of electrodes, different types of pollutants and different types of leaching solutions, and can comprehensively obtain data such as the drainage volume, settlement amount, cracking degree, current, energy consumption, regional resistance and potential value, and interface resistance of the soil body.

[0060] The test device of the present invention can be summarized into several major parts, namely a test box and a vacuum seepage device 1 or a flow field device, an electric device 2 or an electroosmosis device or an electric field device, and a data acquisition component 3 or a data acquisition device.

[0061] As Figure 1 and Figure 3 shown in the figure, the test box includes an anode tank 12, a soil sample tank 11 and a cathode tank 13. The outer shape of the box body of the test box can be a rectangular box with length, width and height dimensions of 350 mm × 175 mm × 100 mm, and can be made of transparent acrylic board. The front and back can be symmetrical, and along the length direction, it can be divided into left, middle and right parts. The left is the anode tank 12 or the anode electrolytic tank, and the leaching solution such as water can be supplied through a Mariotte bottle 15. The middle part is the soil sample tank 11 or the soil area. There can be an anode drainage plate 1017, also called the first partition plate, between the anode tank 12 and the soil sample tank 11. There can be several water passing holes such as anode drainage holes 10171, also called the first water passing holes, on the anode drainage plate 1017. The right is the cathode tank 13 or the cathode electrolytic tank. There can be a cathode drainage plate 1015, also called the second partition plate, between the soil sample tank 11 and the cathode tank 13. There can be several water passing holes such as cathode drainage holes 10151, also called the second water passing holes, on the cathode drainage plate 1015. There is a sealing cover plate 14 for sealing the cathode tank 13 on the top of the cathode tank 13. A wire through hole 141 for passing the wire 24 can be provided on the sealing cover plate 14, and the wire through hole 141 and the wire 24 can be sealed with a sealant. The inside of the cathode tank 13 can be in a state of a mixture of water and vacuum or in a pure vacuum state. Therefore, the cathode tank 13 can also be called a vacuum chamber. The test box is also called a model box or an experimental box.

[0062] The electric device 2 includes a DC power supply such as a 60V DC power supply 21. If a MS605D type DC power supply such as a 60V DC power supply 21 of Maisheng Company 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 such as a 60V DC power supply 21 through the wire 24; the direct current can be electrically connected to the following current collector 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 pouring into the soil body 19. For example, two horizontal smooth rods 1018 are provided at the upper part of the side of the anode drainage plate 1017 close to the soil sample tank 11, and two horizontal smooth rods 1018 are provided at the lower part. The anode 22 made of hydrophilic carbon energy carbon cloth is temporarily hung on the anode drainage plate 1017 through two holes in the upper part and two holes in the lower part, and is in an unfolded state up and down. After pouring the soil body 19 into the soil sample tank 11 and vibrating and preloading it, the anode 22 made of hydrophilic carbon energy carbon cloth is attached to the soil body 19, and under the anchoring action of multiple plastic nails 4, it is always in contact with the soil body 19. The cathode 23 and the cathode drainage plate 1015 are also only temporarily connected before pouring into the soil body 19. For example, two horizontal smooth rods 1018 are provided at the upper part of the side of the cathode drainage plate 1015 close to the soil sample tank 11, and two horizontal smooth rods 1018 are provided at the lower part. The cathode 23 made of hydrophilic graphite carbon paste is temporarily hung on the cathode drainage plate 1015 through two holes in the upper part and two holes in the lower part, and is in an unfolded state up and down. After pouring the soil body 19 into the soil sample tank 11 and vibrating and preloading it, the cathode 23 made of hydrophilic graphite carbon paste is attached to the soil body 19, and under the vacuum pumping action in the cathode direction, it is always in contact with the soil body 19. During the repair process, the cathode 23 is in close contact with both the soil body 19 and the cathode drainage plate 1015, while the anode 22 is in close contact with the soil body 19 and is in a separated state from the anode drainage plate 1017.

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

[0065] The vacuum seepage device has been introduced in detail above, and only supplementary explanations are given here: a 4L Mariotte bottle 15 can be used; a 750w vacuum pump 1013 can be used; the air pipe 18 can be a PU pipe; the air-water separation tank 1010 can be made of transparent acrylic plate, and a scale can be provided on the surface.

[0066] The data acquisition component 3, also known as the data acquisition device, or the data acquisition component, or the data acquisition system. The data acquisition component 3 can be electrically connected by a displacement sensor 31, a tungsten alloy potential measuring probe 32 or a potential probe, a pH meter sensor 33, an acquisition module 35, an RS485 communication module, a current collector, etc. to a host computer such as 34, and the computer 34 functions as a central controller. The displacement sensor 31 is fixed on the test box through a magnetic bracket. The data collected by sensors, probes, etc. are converted into software signals of a host computer such as the computer 34 through the acquisition module 35 and the communication module to calibrate the required digital quantity. The pH meter sensor 33 simultaneously measures the pH changes in the cathode discharged water and the anode electrolytic cell. A high-definition camera can be installed on the top of the transparent soil sample tank 11 to record the development law of the cracks in the soil mass 19, and the high-definition camera is also electrically connected to the computer 34. The above-mentioned electrical connection is electrically connected through a 24V DC power supply 34 via a wire 24. The pH meter sensor 33 can be connected to a pH composite electrode 331, and the pH composite electrode 331 can be placed in the gas-water separation tank 1011.

[0067] In a preferred embodiment of the method for simulating the electrokinetic remediation of heavy metal contaminated soil of the present invention, a simulation test is carried out using the electrokinetic remediation simulation test device for heavy metal contaminated soil described in the above technical solution, including the following steps:

[0068] 1), Use clay, add a heavy metal solution, stir well to form a saturated slurry, then pour it into the soil sample tank 11, vibrate and compact it, and pre-press the soil mass 19, and then stick a sealing film 1016 that is sealed with the four walls on the top surface of the soil mass 19; at this time, both the anode 22 and the cathode 23 are in close contact with the soil mass 19. It is not difficult to understand that, as described above, the function of pre-pressing the soil mass 19 is to make the soil mass 19 have a certain strength, and the certain strength is the strength of the soil mass with a certain depth in the actual remediation site.

[0069] Clay, also known as clay, can be understood as soil with poor water permeability, such as kaolin, dewatered river sludge, and dewatered beach sludge. Heavy metal solutions include metal solutions 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 14, and start a 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 a leaching solution, the vacuum extraction component continuously extracts vacuum, the soil mass 19 in the soil sample tank 11 is always in a saturated state, and a flow field of unidirectional seepage of the leaching solution from the anode 22 to the cathode 23 is formed. The coupling effect of the electric field and the flow field separates and drains the heavy metal ions in the soil mass 19 with the water flow; the anchoring structure of the anode 22 and the soil mass 19 makes the anode 22 always in contact with the soil mass 19. It is not difficult to understand that the vacuum extraction makes the soil mass 19 always in contact with the cathode 23.

[0072] 4) The data acquisition component 3 collects various data in real time. The computer 34 calculates different relationships, draws different relationship diagrams, and selects the optimal parameters, providing reliable data support and technical guidance examples for the in-situ electrokinetic remediation of heavy metal contaminated soil on-site.

[0073] The two side plates 111 of the soil sample tank 11 adopt side plates 11 with a connection structure on the inner surface to prevent the soil mass 19 from detaching from the side plates 111, so as to improve the uniformity and accuracy of the electrokinetic remediation process of the electric field and flow field coupling.

[0074] The saturated soil slurry containing heavy metals is poured into the soil sample tank 11 in layers, vibrated and pre-compressed in three layers, and the soil mass 19 is divided into five regions along the length direction. A sealing film 1016 that is sealed with the four walls is attached to the top surface of the soil mass 19. Here, it refers to the top surface of the topmost layer being attached with the sealing film 1016. A displacement sensor 31 for monitoring the settlement amount of each region is provided on the top surface of the soil mass 19 in each region. Figure 2 Among the five different regions A, B, C, D, and E shown, a potential measuring needle 32 for monitoring the potential difference is provided between the soil masses 19 in adjacent two regions, and at the soil mass 19 near the anode 22 and at the soil mass 19 near the cathode 23 respectively.

[0075] The test is also called an experiment.

[0076] The following is a supplementary description of the preferred embodiment of the electrokinetic remediation simulation test method for heavy metal contaminated soil described above in the present invention.

[0077] The soil mass 19 is pre-compressed to make the soil mass 19 have a certain strength. Mainly, the soil contaminated by heavy metals in-situ is a former working area or living area, so it all has a certain strength. Pre-compression makes it closer to the remediation site. The pre-compression can be implemented by using a heightening frame 5 made of a single acrylic plate. The shape and external dimensions of the heightening frame 5 can match the shape and internal dimensions of the soil sample tank 11. The heightening frame 5 is fixed to the top surface of the soil sample tank 11 through two symmetrical flange plates 51 and a plurality of screws. The soil slurry is poured into the heightening frame 5, and then the soil slurry higher than the top surface of the soil sample tank 11 is vibrated with an external force from top to bottom until it is filled, compacted and the top surface of the soil mass 19 is lower than the top surface of the soil sample tank 11. After disassembling the heightening frame 5, the remediation test of the soil mass 19 is carried out.

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

[0079] Insert potential measuring needles 32 between different regions of the soil mass 19 in pairs, at the soil mass 19 near the anode 22, and at the soil mass 19 near the cathode 23 to obtain the change of potential in real time. Place displacement sensors 31 on the top surface at the middle positions of different regions of the soil mass 11 to obtain the change of settlement in real time. The water pumped out from the soil mass 19 flows into the gas-water separation tank 1011 through the water extraction pipe 17 and is measured in real time on the gravity sensor. During the test process or experimental process, the following parameters are recorded in real time by the acquisition instrument: drainage volume, current, potential, settlement, pH value, etc.

[0080] In the anode tank 12, a Mariotte bottle 15 is used to control the head difference for water supply, and a vacuum pump 1013 is used to pump vacuum to simulate the corresponding head difference. An electrokinetic combined leaching test, that is, an electrokinetic and flow field coupling remediation test, is carried out on the soil mass 19 containing heavy metals in the soil sample tank 11 of the test box. Tests can be carried out on the soil mass 19 with different leaching solutions, different heavy metal solutions, and different heavy metal concentrations. By adjusting different voltage gradients and vacuum degrees or hydraulic gradients, comparative experimental data with different factors can be obtained. By monitoring indicators such as current, potential, pH values of the anode and cathode, drainage volume, water content, settlement, and energy consumption during the test process.

[0081] After the test, level the top surface of the soil mass 19, see Figure 2 and use a mini penetrometer electrically connected to the computer 34 to measure the soil strength at the middle positions of the above-mentioned five different regions, such as regions A, B, C, D, and E.

[0082] Completely shovel out the soil mass 19 of each partition, that is, the five different regions, and take samples in three layers, upper, middle, and lower, for water content determination.

[0083] Read the monitoring data and draw control analysis diagrams of the relationship between current and time for different groups, the relationship between potential and time and position, the relationship between pH values of the two electrodes and time, the relationship between drainage volume and makeup water volume and time, the relationship between settlement distance and time and position, the relationship between water content and position, the relationship between soil strength and position, the crack development law, the microscopic mechanism, etc.

[0084] Calculate the relationship between electroosmotic coefficient and time, energy consumption relationship, etc.

[0085] Select the optimal parameters for subsequent use to provide reliable data support and technical guidance examples for in-situ electrokinetic remediation of heavy metal contaminated soil on site.

[0086] Moreover, compared with the results of single electrokinetic remediation in the prior art, in addition to the above-mentioned advantages, the soil consolidation of the present invention is more uniform, its consolidation and drainage effect is more obvious, and the cracks are correspondingly reduced; there will be no heavy metal ion pollution and no secondary pollution, the corrosion of the anode electrode is reduced, and at the same time, many problems existing in single electrokinetic remediation are solved, such as long remediation time, low remediation efficiency, soil alkalization, uncertain validity period of remediation effect, and damage to soil structure, etc., and it has outstanding stability.

[0087] The components, structures, quantities, etc. not marked above are not shown in the drawings, and some components are not marked in the drawings. The drawings are only schematic. If there are inconsistencies between the drawings and the written description or between the drawings themselves, the written description shall prevail.

[0088] The above is only the preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A simulated test device for electrokinetic remediation of heavy metal-contaminated soil, comprising a data acquisition component and a test chamber, wherein one end of the soil sample chamber of the test chamber has an anode electrically connected to a DC power supply of an electric field, and the other end has a cathode electrically connected to the DC power supply of the electric field; characterized in that: The device also includes a flow field coupled with the electric field: an anode tank located outside the anode and communicating with the water in the soil sample tank, a cathode tank located outside the cathode and communicating with the water in the soil sample tank, a water supply device for continuously supplying water to the anode tank, and a vacuum pumping assembly for continuously evacuating the cathode tank so that the water continuously seeps through the entire soil and keeps the soil in constant contact with the cathode. It also includes an anode and soil anchoring structure that keeps the anode and soil in constant contact; The top surface of the cathode tank is provided with a sealing cover plate.

2. The heavy metal contaminated soil electrokinetic remediation simulation test device according to claim 1 is characterized by: The anode is always attached to one end of the soil and is made of hydrophilic carbon cloth; the cathode is always attached to the other end of the soil and is made of hydrophilic graphite carbon felt.

3. The electrokinetic remediation simulation test device for heavy metal contaminated soil according to claim 1, characterized in that: The inner surfaces of the two side plates of the soil sample trough are provided with connection structures for preventing the soil from being separated from the side plates.

4. The electrokinetic remediation simulation test device for heavy metal contaminated soil according to claim 3, wherein: 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 soil.

5. The electrokinetic remediation simulation test device for heavy metal contaminated soil according to claim 1, characterized in that: The water supply device for continuously supplying water to the anode tank is a Marg flask. The bottom end of the Marg flask is connected to the bottom end of the anode tank through a water supply pipe. The height of the water outlet of the Marg flask is controlled so that the water level of the anode tank is always level with the top surface of the soil.

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

7. The electrokinetic remediation simulation test device for heavy metal contaminated soil according to claim 1, characterized in that: The anode and soil anchoring structure that keeps the anode and soil in constant contact is that a plurality of plastic nail anchoring rods pass through the anode made of hydrophilic carbon cloth and are anchored to the soil, and a limiting cross bar is provided at the outer end of the anchoring rod of each plastic nail outside the anode.

8. A method for simulating the electrokinetic remediation of heavy metal contaminated soil, which uses the heavy metal contaminated soil electrokinetic remediation simulation test device described in claims 1-7 for simulation tests, is characterized in that, The following steps are involved: 1) Use clay, add heavy metal solution, stir thoroughly to form saturated soil slurry, then pour into the soil sample tank, vibrate and pre-press the soil, and stick a sealing film on the top surface of the soil to seal with the four walls; 2) Seal the top surface of the cathode tank with a sealing cover and start the DC power supply to form an electric field; 3) The water supply device continuously supplies water as the eluent, and the vacuum assembly continuously draws the vacuum. The soil in the soil sample tank is always in a saturated state, and a flow field is formed in which the eluent always flows in a unidirectional manner 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 along 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, and the computer calculates different relationships, draws different relationship diagrams, and selects the optimal parameters to provide reliable data support and technical guidance examples for on-site in-situ electric remediation of heavy metal contaminated soil.

9. The method for simulating electrokinetic remediation of heavy metal contaminated soil according to claim 8, wherein: The two side plates of the soil sample trough have connection structures on the inner surface to prevent the soil from being separated from the side plates, so as to improve the uniformity and accuracy of the electric field and flow field coupling repair process.

10. The method for simulating electrokinetic remediation of heavy metal contaminated soil according to claim 8, characterized in that: The saturated soil slurry containing heavy metals is poured into the soil sample tank in layers, compacted and preloaded in three layers, and the soil body is evenly divided into five regions along the length direction. A displacement sensor for monitoring the settlement of each region is provided on the top surface of the soil body in each region, and an electric potential probe for monitoring the potential difference is provided between the soil bodies in two adjacent regions, at the soil body near the anode and at the soil body near the cathode respectively.

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