A three-dimensional simulation system and method for the migration, transformation and remediation of pollutants in underground environments

Abstract

The present invention discloses a three-dimensional simulation system and method for the migration, transformation and restoration of pollutants in an underground environment, including a water supply system, an experimental box, a water storage system, a pollution injection system, a sampling system, a real-time monitoring component and a central control system, wherein the water supply system, the experimental box and the water storage system are connected in sequence. The present invention takes a large-scale experimental box as the main body, and can simulate the underground environment of a contaminated site to the maximum extent by filling porous media and regulating the groundwater flow field; it is equipped with an online monitoring component and a diversified sampling method, and can realize sampling monitoring in a three-dimensional space; the simulation system is a semi-automatic interactive mode, and can realize automatic regulation of parameters such as groundwater flow rate, sampling cycle, and sampling volume, and can also store monitoring data regularly and perform simple visualization processing on it, which can effectively save labor costs and reduce the difficulty of operating simulation experiments.

Description

Technical Field

[0001] The present invention relates to the technical field of contaminated soil and groundwater remediation, and in particular to a three-dimensional simulation system and method for the migration, transformation and remediation of pollutants in an underground environment. Background Art

[0002] Soil and groundwater are important foundations for human survival and development, and are of great significance to environmental protection and the maintenance of human health. However, with the acceleration of my country's urbanization process and the pace of industrial structure adjustment, the problem of soil and groundwater pollution has become increasingly serious. Soil and groundwater pollution control and remediation are inseparable from the study of the pollution characteristics and remediation laws of pollutants in the underground environment. At present, field tracing and laboratory simulation experiments are generally used for research. Field tracing experiments are restricted by the conditions of the site itself, are difficult to operate, have high operating costs, and have great limitations. Therefore, most studies still use indoor experimental research, basically based on one-dimensional experimental columns, two-dimensional experimental troughs and three-dimensional experimental boxes.

[0003] The seepage field of one-dimensional and two-dimensional simulation devices is small and lacks the ability to simulate three-dimensional flow, making it difficult to reflect the actual situation of the contaminated site, making the experimental results unrepresentative. Large-scale three-dimensional devices have the potential to restore the underground environment, but existing three-dimensional devices are limited to simulating a single vadose zone or aquifer environment, lacking the function of simulating an environment that includes both the vadose zone and the saturated zone, making it difficult to reflect the migration, transformation and remediation laws of pollutants in complex sites. Different remediation technologies are deeply restricted by hydrogeological conditions in actual application, and it is also necessary to build scientifically feasible three-dimensional devices to verify the remediation effects of various remediation technologies on contaminated soil and groundwater, and provide key technical parameters for subsequent engineering applications.

[0004] In addition, continuous monitoring of parameters such as pH, conductivity, and pollutant concentration in the simulation area is an important step in revealing the migration, transformation, and remediation laws of pollutants during the experiment. However, when using a three-dimensional simulation device for experiments, there are problems such as difficulty and time-consuming sampling and monitoring. Summary of the invention

[0005] The purpose of the present invention is to provide a three-dimensional simulation system and method for the migration, transformation and remediation of pollutants in an underground environment to solve the problems raised in the above-mentioned background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A three-dimensional simulation system and method for the migration, transformation and remediation of pollutants in an underground environment, comprising a water supply system, an experimental box, a water storage system, a pollution injection system, a sampling system, a real-time monitoring component and a central control system, wherein the water supply system, the experimental box and the water storage system are connected in sequence;

[0008] The experimental box is a rectangular box with a detachable box cover, and two parallel detachable porous partitions are vertically placed in the experimental box, and the lower edges of the porous partitions are in contact with the bottom plate of the experimental box;

[0009] The water supply system comprises a water supply tank and a water supply pump, wherein the water supply tank is connected to the water supply pump and the water inlet through a connecting pipe;

[0010] The water storage system comprises a flow meter, a water storage tank and a lifting device, wherein the water storage tank is connected to the flow meter and the water outlet in sequence through a connecting pipe, and the water storage tank is installed on the lifting device;

[0011] The pollution injection system comprises a medicine bottle, an injection pump and an injection well which are connected in sequence, wherein the injection well is vertically inserted into the porous medium in the soil tank, and the injection well is connected to the injection pump and the medicine bottle in sequence through a connecting pipeline;

[0012] The sampling system includes a soil sampler and a monitoring well group that can be uprightly inserted into the porous medium in the soil tank, the monitoring well group includes monitoring wells of different lengths, the monitoring wells are equipped with sealing covers, and the monitoring wells have sampling tubes inserted into the bottom thereof, and the sampling tubes are connected to the sampling pump through a connecting pipeline;

[0013] The real-time monitoring component includes a pH sensor, a conductivity sensor, a temperature sensor, a humidity sensor, a water level sensor, and a dissolved oxygen sensor; the monitoring component is placed in the monitoring well or plugged into the sampling / monitoring port;

[0014] The water level meter, water supply pump, lifting device, injection pump, sampling pump and monitoring component are connected to the central control system through a data transmission line.

[0015] The central control system is a PLC (Programmable logic Controller) control system, which controls the start and stop and operating parameters of equipment such as water supply pumps, flow meters, lifting devices, injection pumps and sampling pumps on the one hand, and converts the signals collected by real-time monitoring components into data for visualization and storage on the other hand.

[0016] As a further solution of the present invention: the upper edge of the porous partition is flush with the upper opening of the experimental box, the porous partition divides the space in the experimental box into a water supply trough, a soil trough and a water storage trough, the bottom plate of the experimental box is provided with a drainage and mud discharge port and casters, the casters are provided with a braking device, the water inlet is layered on the side plate at one end of the experimental box, the water outlet is layered on the side plate at the other end, the sampling / monitoring ports are layered on the side plates on both sides of the soil trough, a number of water level communicating vessels are arranged on the side plates on both sides of the soil trough, the water level communicating vessels are connected to the soil trough through a hose, and a water level meter is placed in the water supply trough.

[0017] As a further solution of the present invention: multiple layers of clay or sand are filled in the soil trough, and the water level and flow rate in the experimental box are adjusted to simulate a hydrogeological unit containing both a heterogeneous aeration zone and a saturated zone, wherein the particle size of the clay is <0.005 mm, and the particle size of the sand is 0.1-1.0 mm.

[0018] As a further solution of the present invention: the number of soil filling layers of the hydrogeological unit is 2 to 7 layers, and the height ratio of the heterogeneous aeration zone and the saturated zone in the hydrogeological unit is 5:1 to 1:5.

[0019] As a further solution of the present invention: the lifting device is composed of a lifting frame, a motor and a guide rail, and an overflow port is arranged on a side wall of one side of the water tank.

[0020] As a further solution of the present invention: the experimental box is made of stainless steel, the length×width×height of the experimental box is 200cm×100cm×110cm, and the length ratio of the water supply trough, soil trough and water storage tank is 1:18:1.

[0021] A handle is arranged on the top plate of the box cover, and a plurality of reserved openings with covers having an inner diameter of 3 to 5 cm are arranged on the top plate of the box cover.

[0022] The porous partition is a perforated stainless steel plate with a thickness of 0.5 cm and a pore size of 1 cm. Both sides of the porous partition are wrapped with a metal screen of 100 to 300 meshes.

[0023] The aperture of the water inlet and the water outlet is 1 cm, the horizontal hole spacing is 20 cm, and the vertical hole spacing is 20 cm. The sampling / monitoring port is a stainless steel threaded port with an aperture of 0.8 cm, a horizontal hole spacing of 10 cm, and a vertical hole spacing of 10 cm. The water inlet, water outlet and sampling / monitoring port are equipped with sealing covers.

[0024] The water level communicating vessel is a graduated glass tube with an opening at the upper end.

[0025] The monitoring wells are stainless steel pipes of different lengths, ranging from 45 to 90 cm in length and 2 to 3 cm in inner diameter. The 0 to 5 cm portion of the bottom of the monitoring well is opened with a hole diameter of 2 mm and a hole spacing of 1 mm. The outside of the monitoring well is wrapped with a 100 to 300 mesh metal screen.

[0026] The soil sampler is a stainless steel original soil sampler with scale marks (accuracy of 1 cm) and a length of 110 cm.

[0027] The injection well is a stainless steel tube with an inner diameter of 1 cm and a length of 5 to 30 cm. A hole is opened at a portion of 0 to 5 cm from the bottom of the injection well, with a hole diameter of 2 mm and a hole spacing of 1 mm.

[0028] As a further solution of the present invention: the simulation method steps are as follows:

[0029] a. Prepare soil: Collect clean clay and sand samples, remove impurities, air-dry and refine (clay through 200 mesh sieve, sand through 10 mesh sieve), and prepare mixed soil with different hydraulic conductivity according to experimental requirements (clay and sand mass ratio is 1:10 to 10:1);

[0030] b. Filling the soil: Connect the water supply system, test box and water storage system in sequence, and continuously inject water into the box to test the sealing of the test box. After the test is completed, fill the soil trough with clay, sand or mixed soil layer by layer to simulate the heterogeneous underground medium. Add clay or mixed soil to the bottom and side walls of the test box to prevent pollutants from flowing along the box wall. Add some clay to the sand layer or mixed soil layer to simulate the clay lens. After filling 5 to 10 cm of soil, tamp and sprinkle water, and continue filling after standing for 5 to 10 minutes. The final filling height is 5 to 10 cm lower than the top of the test box;

[0031] c. Install the monitoring and sampling system: Determine the location and layout of monitoring and sampling according to the experimental requirements. Start installing the monitoring well group when the soil filling height is 20-30 cm. Continue to fill the soil while installing the monitoring well group. After completing the filling and installation of the monitoring well group, place the real-time monitoring components and sampling tubes into the monitoring well.

[0032] d. Regulate the groundwater flow field: Turn on the water inlet pump to continuously inject water into the experimental box, observe the water head of the water inlet tank and the groundwater flow rate in the box through the water level meter and flow meter, adjust the flow of the water inlet pump and the height of the water storage tank through the central control system, and then adjust the water level or groundwater flow rate required for the experiment. The groundwater level range is 0-80cm, the head difference between the water supply tank and the water storage tank ranges from 0 to 40cm, and the groundwater flow rate ranges from 0 to 1.0m / d;

[0033] e. Injection of pollutants or tracers: Prepare pollutants or tracers of corresponding concentrations before the experiment begins. Determine the type of pollution (point source / non-point source, temporary / continuous) and pollution depth according to the experimental requirements. Install the injection well at the corresponding position during the filling process. Turn on the injection pump to transport pollutants or tracers into the medium. The injection volume and flow rate are controlled by adjusting the start and stop and flow rate of the injection pump.

[0034] f. Sampling monitoring and data recording: while the pollutants are being injected, start monitoring and recording various parameters (pH, dissolved oxygen, conductivity, temperature, etc.) in the groundwater in different areas of the experimental box at regular intervals (10s / time to 10h / time), and regularly collect soil and groundwater samples at different locations and depths for testing. The sampling time can be determined based on the groundwater flow rate, which is measured by a flow meter. Groundwater is collected by inserting a sampling tube into the monitoring well, and soil is collected by a soil sampler. After sampling and testing, the interpolation method is used to draw the isoconcentration curves of the monitored pollutants or tracers, and their migration distribution and remediation laws in complex strata are analyzed.

[0035] As a further solution of the present invention: under the premise of steps af, repair modules such as electric-permeable reaction wall, microbial remediation, chemical oxidation and electric remediation modules can be installed in the experimental box according to experimental requirements to verify the application effect of in-situ remediation technology under complex geological conditions.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The simulation system provided by the present invention is mainly composed of a large experimental box, equipped with a water level communication device, which can be filled with homogeneous or heterogeneous strata, and can observe and control the groundwater level and groundwater flow rate in real time to form a hydrogeological unit containing both heterogeneous aeration zones and saturated zones, which can simulate the underground environment of the contaminated site to the maximum extent;

[0038] 2. The simulation system provided by the present invention has a real-time monitoring function, can monitor various parameters in the soil tank regularly, is equipped with diversified sampling methods, is provided with a monitoring / sampling port located on the side wall of the soil tank and is equipped with a soil sampler that can be inserted from above the soil, and can realize sampling monitoring in three-dimensional space. It is suitable for the study of pollutant transmission characteristics under complex hydrogeological conditions, and is also suitable for verifying the application effects of various in-situ remediation technologies (microbial enhancement technology, chemical oxidation technology, electric remediation technology, permeable reaction wall, etc.);

[0039] 3. The simulation system provided by the present invention is a semi-automatic interactive system, which can realize the automatic control of some test parameters (such as groundwater flow rate, sampling volume, and sampling period), and can also store monitoring data regularly and perform simple visualization processing on it, which can effectively save labor costs and reduce the difficulty of simulation experiment operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the structure of a three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments.

[0041] Figure 2 This is a diagram of the layered porous media filling effect in the experimental box in the three-dimensional simulation system and method for the migration, transformation and remediation of pollutants in the underground environment.

[0042] Figure 3 This is a schematic diagram of the layout of monitoring wells and injection wells in the experimental box in the three-dimensional simulation system and method for the migration, transformation and remediation of pollutants in the underground environment.

[0043] Figure 4 Schematic diagram of the monitoring well group and soil sampler in the three-dimensional simulation system and method for the migration, transformation and remediation of pollutants in the underground environment.

[0044] As shown in the figure: 1-experimental box, 1a-box cover, 1aa-handle, 1ab-reserved port, 1b-porous partition, 1c-water supply tank, 1d-soil tank, 1e-water storage tank, 1f-drainage and mud outlet, 1g-castor, 1h-castor, 1i-water inlet, 1j-water outlet, 1k-sampling / monitoring port, 1l-water level connecting vessel, 2-water supply system, 3-water storage system, 4-pollution injection system, 5-sampling system, 6-real-time monitoring component, 7-central control system, 8-water level meter, 9-water supply tank, 10-water supply pump, 11-flow meter, 12-water storage tank, 12a-overflow port, 13-lifting device, 13a-lifting frame, 13b-motor, 13c-guide rail, 14-medicine bottle, 15-injection pump, 16-injection well, 17-soil sampler, 18-monitoring well group, 18a-monitoring well, 18b-sealing cover, 19-sampling tube, 20-sampling pump, A-hydrogeological unit, A1-vadose zone, A2-saturated zone. DETAILED DESCRIPTION

[0045] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] See also Figures 1 to 4 In an embodiment of the present invention, a three-dimensional simulation system for the migration, transformation and remediation of pollutants in an underground environment includes a water supply system 2, an experimental box 1, a water storage system 3, a pollution injection system 4, a sampling system 5, a real-time monitoring component 6 and a central control system 7, and the water supply system 2, the experimental box 1 and the water storage system 3 are connected in sequence.

[0047] The experimental box 1 is a rectangular box with a length × width × height of 200 cm × 100 cm × 110 cm. The experimental box 1 is provided with a detachable box cover 1a to reduce the volatilization of pollutants during the experiment. For easy disassembly, the box cover is composed of 4 parts, each of which is provided with a handle 1aa. The box cover 1a is provided with a number of reserved openings 1ab with a covered inner diameter of 3 to 5 cm, which are convenient for the pipelines in the box to pass through. Two parallel porous partitions 1b are set in the experimental box 1. The porous partitions 1b are perforated stainless steel plates with a thickness of 0.5 cm and an aperture of 1 cm. Both sides are wrapped with metal screens with an aperture of 100 to 300 meshes to facilitate soil and water seepage. The lower edge of the porous partition 1b is in contact with the bottom plate of the experimental box 1, and the upper edge is flush with the upper opening of the experimental box 1, dividing the space in the experimental box into a water supply tank 1c, a soil tank 1d and a water storage tank 1e. The length ratio of the water supply tank 1c, the soil tank 1d and the water storage tank 1e is 1:18:1. The bottom plate of the experimental box 1 is provided with a drainage and mud discharge port 1f and a caster 1g, and the caster 1g is provided with a brake device 1h, which is convenient for replacing the porous medium and moving the box. A water level gauge 8 is provided in the water supply tank, one end of which is placed at the bottom of the water supply tank 1c, and the other end of which is connected to the central control system 7, which is convenient for observing and regulating the water head of the water inlet tank 1c.

[0048] The water inlet 1i is arranged in layers on the side plate at one end of the experimental box 1, and the water outlet 1j is arranged in layers on the side plate at the other end. The sampling / monitoring port 1k is arranged in layers on the side plates on both sides of the soil groove 1d. The aperture of the water inlet 1i and the water outlet 1j is 1 cm, the horizontal hole spacing is 20 cm, and the vertical hole spacing is 20 cm. The aperture of the sampling / monitoring port 1k is 0.8 cm, the horizontal hole spacing is 10 cm, and the vertical hole spacing is 10 cm. The water inlet 1i, the water outlet 1j and the sampling / monitoring port 1k are equipped with sealing covers. Several glass water level connectors 1l with scales are arranged on the side plates on both sides of the soil groove 1d. The water level connector 1l is connected to the soil groove 1d through a hose and is used to observe the water level in the experimental box 1 and control the water inlet head.

[0049] The water supply system 2 includes a water supply tank 9 and a water supply pump 10. The water supply tank 9 is connected to the water supply pump 10 and the water inlet 1i through a connecting pipeline. The water supply pump 10 is connected to the central control system 7 to facilitate the adjustment of the water supply flow rate and water volume.

[0050] The water storage system 3 includes a flow meter 11, a water tank 12 and a lifting device 13. The water tank 12 is connected to the flow meter 11 and the water outlet 1j in sequence through a connecting pipe. The flow meter is used to observe the groundwater flow rate in the experimental box. The water tank 12 is installed on the lifting device 13. The lifting device 13 consists of a lifting frame 13a with scale marks, a motor 13b and a guide rail 13c. The lifting device 13 is connected to the central control system 7 to facilitate the control of the height of the water tank 12, which can be adjusted to 0 to 100 cm from the bottom of the experimental box. An overflow port 12a is set on the side wall of one side of the water tank to facilitate fixing the water outlet head.

[0051] The pollution injection 4 system includes a medicine bottle 14, an injection pump 15 and an injection well 16 connected in sequence. The injection well 16 is vertically inserted into the porous medium in the soil tank 1d. The injection well 16 is a stainless steel pipe with an inner diameter of 1 cm and a length of 5 to 30 cm. The 0 to 5 cm portion of the bottom of the injection well 16 is opened with a hole diameter of 2 mm and a hole spacing of 1 mm. The injection well 16 is connected to the injection pump 15 and the medicine bottle 14 in sequence through a connecting pipeline. The injection pump 15 is connected to the central control system 7 to facilitate control of start and stop and flow adjustment.

[0052] The sampling system 5 includes a soil sampler 17 and a monitoring well group 18 that can be inserted upright in the porous medium in the soil tank 1d. The monitoring well group 18 includes monitoring wells 18a of different lengths. The monitoring wells 18a are stainless steel pipes of different lengths, with a length of 45 to 90 cm and an inner diameter of 2 to 3 cm. The bottom 0 to 5 cm of the monitoring well 18a is opened, with a hole diameter of 2 mm and a hole spacing of 1 mm. The outside of the monitoring well 18a is wrapped with a 100 to 300 mesh metal screen. The monitoring well is equipped with a sealing cover 18b, which is sealed when the monitoring well is not in use. There is a sampling tube 19 inserted into the bottom of the monitoring well 18a. The sampling tube 19 is connected to the sampling pump 20 through a connecting pipeline. The sampling pump 20 is connected to the central control system 7 to facilitate control of start and stop and flow adjustment. The soil sampler 17 is a stainless steel original soil sampler with a scale mark accuracy of 1 cm, and the length is 110 cm.

[0053] The real-time monitoring component 6 includes a pH sensor, a conductivity sensor, a temperature sensor, a humidity sensor, a water level sensor, and a dissolved oxygen sensor; the monitoring component 6 is placed in the monitoring well 18a or plugged into the sampling / monitoring port 1k to monitor relevant parameters of groundwater in different areas. Each sensor is connected to the central control system 7 to facilitate start and stop control and timed monitoring and data recording.

[0054] The soil tank 1d is filled with multiple layers of clay or sand, and clean water is injected into the experimental box and the water level and flow rate are adjusted to simulate the hydrogeological unit A containing both the heterogeneous aeration zone A1 and the saturated zone A2. The particle size of the clay is <0.005mm, and the particle size of the sand is 0.1-1.0mm. The number of soil layers filled in the hydrogeological unit A is 2-7 layers, and the height ratio of the aeration zone A1 and the saturated zone A2 is 5:1-1:5.

[0055] The central control system 7 adopts a PLC (Programmable logic Controller) control system. On the one hand, it controls the start and stop and operating parameters of equipment such as the water supply pump 10, flow meter 11, lifting device 13, injection pump 15 and sampling pump 20, and realizes automatic regulation of parameters such as groundwater flow rate, sampling volume, and sampling period; on the other hand, it converts the signals collected by the real-time monitoring component 6 into data storage and presentation, realizes timed storage of monitoring data and simple visualization of it.

[0056] The three-dimensional simulation system is based on a large experimental box, which can simulate the underground environment of the contaminated site to the greatest extent. By injecting pollutants or tracers into the simulated environment, real-time monitoring of groundwater-related parameters, and regular collection of soil and groundwater samples for testing, it can realize the simulation study of the migration and transformation laws of pollutants in complex strata; by combining with the supporting pollution remediation module, it can verify the application effect of various in-situ remediation technologies (such as electric-permeable reaction wall technology, microbial remediation technology, chemical oxidation technology, etc.) in complex geological conditions.

[0057] A three-dimensional simulation method for the migration, transformation and remediation of pollutants in an underground environment, the simulation method steps are as follows:

[0058] a. Collect clean clay and sand samples, air-dry and refine them after removing impurities. Clay is sieved through a 200-mesh sieve, and sand is sieved through a 10-mesh sieve. At the same time, mixed soils with different hydraulic conductivity are prepared according to experimental requirements. The mass ratio of clay to sand is 1:10 to 10:1;

[0059] b. Connect the water supply system, test box and water storage system in sequence, and continuously inject water into the box to test the sealing of the test box. After the test is completed, fill the soil trough with clay, sand or mixed soil evenly layer by layer to simulate the heterogeneous underground medium, fill the bottom and side walls of the test box with clay or mixed soil to prevent pollutants from flowing along the box wall, and add some clay to the sand layer or mixed soil layer to simulate the clay lens. After filling 5 to 10 cm of soil, tamp and sprinkle water, and continue filling after standing for 5 to 10 minutes. The final filling height is 5 to 10 cm lower than the top of the test box;

[0060] c. Determine the location and layout of monitoring and sampling according to the experimental requirements (such as 4 rows and 4 columns, 3 rows and 6 columns, etc.), start installing the monitoring well group when the soil filling height is 20-30 cm, and continue to fill the soil while installing the monitoring well group. After completing the filling and installation of the monitoring well group, place the real-time monitoring component and sampling tube into the monitoring well;

[0061] d. Turn on the water inlet pump to continuously inject water into the experimental box, observe the water head of the water inlet tank and the groundwater flow rate in the box through the water level meter and flow meter, adjust the flow of the water inlet pump and the height of the water storage tank through the central control system, and then adjust the water level or groundwater flow rate required for the experiment. The groundwater level range is 0-80cm, the head difference between the water supply tank and the water storage tank ranges from 0 to 40cm, and the groundwater flow rate ranges from 0 to 1.0m / d;

[0062] e. Prepare the pollutants or tracers of corresponding concentration before the experiment begins, determine the pollution type (point source / area source, temporary / continuous and pollution depth) according to the experimental requirements, install the injection well at the corresponding position during the filling process, turn on the injection pump to transport the pollutants or tracers into the medium, and control the injection volume and flow rate by adjusting the start and stop and flow rate of the injection pump;

[0063] f. While the pollutants are being injected, start monitoring and recording various parameters (pH, dissolved oxygen, conductivity, temperature, etc.) in groundwater in different areas of the experimental box at regular intervals (10s / time ~ 10h / time), and regularly collect soil and groundwater samples at different locations and depths for testing. The sampling time can be determined according to the groundwater flow rate, which is measured by a flow meter. Groundwater is collected by inserting a sampling tube into the monitoring well, and soil is collected by a soil sampler. After sampling and testing, the interpolation method is used to draw the isoconcentration curve of the monitored pollutants or tracers to analyze their migration and transformation laws in complex formations.

[0064] g. On the premise of steps af, install remediation modules in the experimental box according to experimental requirements, such as electric-permeable reaction wall, microbial remediation, chemical oxidation and electric remediation modules, evaluate the application effect of in-situ remediation technology under complex geological conditions, obtain key technical parameters of each technology, and provide technical support for subsequent remediation projects.

[0065] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments, characterized by: It comprises a water supply system (2), an experimental box (1), a water storage system (3), a pollution injection system (4), a sampling system (5), a real-time monitoring component (6) and a central control system (7), wherein the water supply system (2), the experimental box (1) and the water storage system (3) are connected in sequence; The experimental box (1) is a rectangular box with a detachable box cover (1a), and two parallel detachable porous partitions (1b) are vertically placed in the experimental box (1), and the lower edges of the porous partitions (1b) are in contact with the bottom plate of the experimental box (1); The water supply system (2) comprises a water supply tank (9) and a water supply pump (10), wherein the water supply tank (9) is connected to the water supply pump (10) and the water inlet (1i) via a connecting pipe; The water storage system (3) comprises a flow meter (11), a water storage tank (12) and a lifting device (13); the water storage tank (12) is connected to the flow meter (11) and the water outlet (1j) in sequence through a connecting pipe, and the water storage tank (12) is installed on the lifting device (13); The contamination injection system (4) comprises a medicine bottle (14), an injection pump (15) and an injection well (16) which are connected in sequence, wherein the injection well (16) is vertically inserted into the porous medium in the soil tank (1d), and the injection well (16) is connected in sequence with the injection pump (15) and the medicine bottle (14) through a connecting pipeline; The sampling system (5) comprises a soil sampler (17) which can be inserted upright into the porous medium in the soil tank (1d) and a monitoring well group (18), wherein the monitoring well group (18) comprises monitoring wells (18a) of different lengths, the monitoring wells are equipped with sealing covers (18b), and the monitoring wells (18a) have sampling tubes (19) inserted into the bottom thereof, and the sampling tubes (19) are connected to a sampling pump (20) via a connecting pipeline; The real-time monitoring component (6) includes a pH sensor, a conductivity sensor, a temperature sensor, a humidity sensor, a water level sensor, and a dissolved oxygen sensor; the monitoring component (6) is placed in the monitoring well (18a) or plugged into the sampling or monitoring port (1k); The upper edge of the porous partition (1b) is flush with the upper opening of the test box (1). The porous partition (1b) divides the space in the test box into a water supply trough (1c), a soil trough (1d) and a water storage trough (1e). The bottom plate of the test box (1) is provided with a drainage and mud discharge port (1f) and a caster (1g). The caster (1g) is provided with a braking device (1h). A water inlet (1i) is arranged in layers on the side plate at one end of the test box (1), and a water outlet (1j) is arranged in layers on the side plate at the other end. Sampling or monitoring ports (1k) are arranged in layers on the side plates on both sides of the soil trough (1d). A plurality of water level communicating devices (1l) are arranged on the side plates on both sides of the soil trough (1d). The water level communicating devices (1l) are connected to the soil trough (1d) through a hose. A water level meter (8) is placed in the water supply trough (1c); The water level meter (8), water supply pump (10), lifting device (13), injection pump (15), sampling pump (20) and monitoring component (6) are connected to the central control system (7) via a data transmission line; The central control system (7) is a PLC control system, which controls the start and stop and operating parameters of the water supply pump (10), flow meter (11), lifting device (13), injection pump (15) and sampling pump (20) on the one hand, and converts the signals collected by the real-time monitoring component (6) into data for storage and presentation on the other hand.

2. The three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments according to claim 1, characterized in that: The soil trough (1d) is filled with multiple layers of clay or sand, and the water level and flow rate in the experimental box are adjusted to simulate a hydrogeological unit (A) containing both a heterogeneous aeration zone and a saturated zone. The particle size of the clay is <0.005 mm, and the particle size of the sand is 0.1-1.0 mm.

3. The three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments according to claim 2, characterized in that: The number of soil filling layers of the hydrogeological unit (A) is 2 to 7 layers, and the ratio of the height of the heterogeneous aeration zone (A1) to the saturated zone (A2) in the hydrogeological unit (A) is .

4. The three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments according to claim 1, characterized in that: The lifting device (13) is composed of a lifting frame (13a), a motor (13b) and a guide rail (13c), and an overflow port (12a) is arranged on a side wall of one side of the water storage tank (12).

5. The three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments according to claim 1, characterized in that: The experimental box (1) is made of stainless steel, and the length×width×height of the experimental box (1) is 200cm×100cm×110cm. The length ratio of the water supply tank (1c), the soil tank (1d) and the water storage tank (1e) is 1:18:1; The top plate of the box cover (1a) is provided with a handle (1aa), and the top plate of the box cover (1a) is provided with a plurality of reserved openings (1ab) with covered portions and an inner diameter of 3 to 5 cm; The porous partition (1b) is a perforated stainless steel plate with a thickness of 0.5 cm and a pore size of 1 cm. Both sides of the porous partition (1b) are wrapped with a metal screen of 100-300 meshes; The water inlet (1i) and the water outlet (1j) have a hole diameter of 1 cm, a horizontal hole spacing of 20 cm, and a vertical hole spacing of 20 cm. The sampling or monitoring port (1k) is a stainless steel threaded port with a hole diameter of 0.8 cm, a horizontal hole spacing of 10 cm, and a vertical hole spacing of 10 cm. The water inlet (1i), the water outlet (1j), and the sampling or monitoring port (1k) are equipped with sealing covers; The water level communicating vessel (11) is a graduated glass tube with an opening at the upper end; The monitoring well (18a) is a stainless steel pipe of different lengths, with a length of 45-90 cm and an inner diameter of 2-3 cm. A hole is opened at a portion of 0-5 cm from the bottom of the monitoring well (18a), with a hole diameter of 2 mm and a hole spacing of 1 mm. The outside of the monitoring well (18a) is wrapped with a metal screen of 100-300 meshes; The soil sampler (17) is a stainless steel original soil sampler with a scale mark and an accuracy of 1 cm, and a length of 110 cm; The injection well (16) is a stainless steel tube with an inner diameter of 1 cm and a length of 5 to 30 cm. The 0 to 5 cm portion at the bottom of the injection well (16) is opened with a hole diameter of 2 mm and a hole spacing of 1 mm.

6. The three-dimensional simulation method of the three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments according to claim 1, characterized in that: The simulation steps are as follows: a. Soil preparation: Collect clean clay and sand samples, remove impurities, air-dry and refine them, pass clay through a 200-mesh sieve, and pass sand through a 10-mesh sieve. At the same time, prepare mixed soils with different water conductivity coefficients according to experimental requirements. The mass ratio of clay to sand is 10; b. Filling the soil: Connect the water supply system, test box and water storage system in sequence, and continuously inject water into the box to test the sealing of the test box. After the test is completed, fill the soil trough with clay, sand or mixed soil evenly layer by layer to simulate the heterogeneous underground medium, fill the bottom and side walls of the test box with clay or mixed soil to prevent pollutants from flowing along the box wall, and add some clay to the sand layer or mixed soil layer to simulate the clay lens. After filling 5~10cm of soil, tamp and sprinkle water, and continue filling after standing for 5~10min. The final filling height is 5~10cm lower than the top of the test box; c. Install the monitoring and sampling system: Determine the location and layout of monitoring and sampling according to the experimental requirements. Start installing the monitoring well group when the soil filling height is 20-30 cm. Continue to fill the soil while installing the monitoring well group. After completing the filling and installation of the monitoring well group, place the real-time monitoring components and sampling tubes into the monitoring well; d. Regulate the groundwater flow field: Turn on the water inlet pump to continuously inject water into the experimental box, observe the water head of the water inlet tank and the groundwater flow rate in the box through the water level meter and flow meter, adjust the flow of the water inlet pump and the height of the water storage tank through the central control system, and then adjust the water level or groundwater flow rate required for the experiment. The groundwater level range is 0~80cm, the head difference between the water supply tank and the water storage tank ranges from 0~40cm, and the groundwater flow rate ranges from 0~1.0m / d; e. Inject pollutants or tracers: Prepare pollutants or tracers of corresponding concentration before the experiment begins, determine the type and depth of pollution according to the experimental requirements, install injection wells at corresponding positions during the filling process, turn on the injection pump to transport pollutants or tracers into the medium, and control the injection volume and flow rate by adjusting the start and stop and flow rate of the injection pump; f. Sampling monitoring and data recording: While the pollutants are being injected, start to regularly monitor and record various parameters in the groundwater in different areas of the experimental box, and regularly collect soil and groundwater samples at different locations and depths for testing. The sampling time can be determined based on the groundwater flow rate, which is measured by a flow meter. Groundwater is collected by inserting a sampling tube into the monitoring well, and soil samples are collected by a soil sampler. After sampling and testing, the interpolation method is used to draw the concentration curve of the monitored pollutants or tracers, and their migration distribution and remediation laws in complex strata are analyzed.

7. The three-dimensional simulation method of the three-dimensional simulation system for the migration, transformation and remediation of pollutants in underground environments according to claim 6, characterized in that: Under the premise of steps af, a repair module can be installed in the experimental box according to experimental requirements to verify the application effect of the in-situ repair technology under complex geological conditions.

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