Testing equipment and method for photocatalytic regulation and control of service performance of permeable reaction barrier

Abstract

The invention belongs to the field of polluted groundwater remediation, discloses a test device and method for photocatalytic regulation and control of the service performance of a permeable reaction barrier, and aims to provide the test device for the service performance of the permeable reaction barrier and improve the test accuracy. The equipment comprises a polluted underground water simulation device, an underground water inlet device, a permeable reaction barrier, an underground water outlet device, a water catchment device, a metering device and a monitoring device, a water outlet of the polluted groundwater simulation device is connected with a water inlet of the groundwater inlet device, the groundwater inlet device, the permeable reaction barrier and the groundwater outlet device are sequentially connected, and a sealing plate capable of moving up and down is arranged on one side, close to the groundwater inlet device, of the permeable reaction barrier; a water outlet of the underground water outlet device is connected with the water catchment device, a water outlet of the water catchment device is connected with the metering device, and the monitoring device is respectively connected with the polluted underground water simulation device, the underground water inlet device, the underground water outlet device, the water catchment device and the metering device.

Description

Technical Field

[0001] The present invention relates to test equipment for repairing polluted groundwater. Specifically, it relates to a test equipment and method for photocatalytically regulating the service performance of a permeable reactive barrier. Background Art

[0002] A permeable reactive barrier is a device for in-situ remediation of polluted groundwater. By filling a strip of permeable filling material downstream of the groundwater flow, the flowing polluted groundwater undergoes a series of physical and chemical reactions with the filling material, thereby removing or degrading pollutants and achieving the purpose of controlling the spread of the pollution plume. For groundwater containing high concentrations of pollutants with a constant concentration, by improving and optimizing the adsorption efficiency of the filling material for pollutants and increasing the frequency of filling material replacement, the efficiency of the permeable reactive barrier in removing pollutants is significantly improved, and it has been successfully applied in more and more groundwater remediation projects at polluted sites.

[0003] However, for high-concentration organic polluted sites and in-production enterprise plots in the later stage of remediation, the concentration of groundwater pollutants shows typical fluctuating characteristics. To ensure the removal effect of groundwater pollutants in such sites, engineers often select the type of filling material for the permeable reactive barrier and optimize the design of the filling material replacement cycle based on the highest groundwater pollutant concentration within a certain period (for example, one year). This directly leads to an increase in the operating cost of the permeable reactive barrier and a low operating efficiency of the supporting facilities. To achieve the optimized design of the photocatalytically regulated permeable reactive barrier, there is an urgent need to develop a model test device that can simulate the service state of the permeable reactive barrier at the site under laboratory conditions and conduct optimized design. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to provide a test equipment and method for photocatalytically regulating the service performance of a permeable reactive barrier, which can provide test equipment for the service performance of the permeable reactive barrier and improve the accuracy of the test.

[0005] To solve the above technical problems, the present invention adopts the following technical solutions: On the one hand, the present invention provides a test device for photocatalytically regulating the service performance of a permeable reactive barrier. The device includes a contaminated groundwater simulation device, a groundwater inlet device, a permeable reactive barrier, a groundwater outlet device, a water collection device, a metering device, and a monitoring device. The permeable reactive barrier includes at least one permeable reactive barrier unit. Among them, the water outlet of the contaminated groundwater simulation device is connected to the water inlet of the groundwater inlet device, and the groundwater inlet device, the permeable reactive barrier, and the groundwater outlet device are connected in sequence. A seal plate that can move up and down is provided on the side of the permeable reactive barrier close to the groundwater inlet device. The seal plate is used to close or open the water flow channel between the groundwater inlet device and the permeable reactive barrier. The water outlet of the groundwater outlet device is connected to the water collection device, the water outlet of the water collection device is connected to the metering device, and the monitoring device is respectively connected to the contaminated groundwater simulation device, the groundwater inlet device, the groundwater outlet device, the water collection device, and the metering device.

[0006] As a preferred example, the contaminated groundwater simulation device includes a first water storage unit, a first flow controller, a first inlet valve, a second water storage unit, a second flow controller, and a second inlet valve. The first water storage unit is used to store the highest concentration of contaminated groundwater required for the test, and the second water storage unit is used to store the lowest concentration of contaminated groundwater required for the test. The first water storage unit is connected through the first inlet valve and the first flow controller, and the water outlet of the first flow controller is connected to the groundwater inlet device. The second water storage unit is connected through the second inlet valve and the second flow controller, and the water outlet of the second flow controller is connected to the groundwater inlet device. The monitoring device is respectively connected to the first inlet valve, the second inlet valve, the first flow controller, and the second flow controller.

[0007] As a preferred example, the groundwater inlet device includes a first housing and a first stirrer. The first stirrer is connected to the first housing, and a detection component is provided on the wall surface of the first housing. The detection component is connected to the monitoring device. A first drain port is provided at the lower part of the first housing, and a first exhaust and water stop valve is provided at the top of the first housing. The groundwater outlet device includes a second housing and a second stirrer. The second stirrer is connected to the second housing, a water inlet is provided on the top surface of the second housing, and a second exhaust and water stop valve is provided at the top of the second housing. The monitoring device is respectively connected to the first stirrer and the second stirrer.

[0008] As a preferred example, the water outlet of the groundwater outlet device is located on the side of the second housing away from the groundwater inlet device, and there are at least two water outlets, and at least two water outlets are at different heights.

[0009] As a preferred example, the permeable reactive barrier unit includes a hollow third housing. The two relatively hollowed sides of the third housing are respectively and hermetically connected to the first housing and the second housing. Permeable gauzes are respectively provided on the two relatively hollowed sides of the third housing. Granular fillers are contained in the third housing. An ultraviolet light band is arranged inside the granular fillers. Two power supply terminals of the ultraviolet light band are respectively connected to the positive and negative poles of an external power supply. The granular fillers include light-transmitting glass balls and ceramsite with titanium dioxide loaded on the surface.

[0010] As a preferred example, in each of the permeable reactive barrier units, the buried length of the ultraviolet light band is determined according to Formula (1) and Formula (2): Formula (1) Formula (2) In the formula, represents the buried length of the ultraviolet light band, with the unit of cm; represents the length of the permeable reactive barrier unit, with the unit of cm; represents the width of the permeable reactive barrier unit, with the unit of cm; represents the height of the permeable reactive barrier unit, with the unit of cm; represents the radial effective irradiation area of an ultraviolet light band, with the unit of cm 2 ; represents the reduction coefficient of the radial effective irradiation area of the ultraviolet light band, dimensionless; represents the stacking volume of the light-transmitting glass balls, with the unit of cm 3 ; represents the stacking volume of the ceramsite, with the unit of cm 3 ; represents the reference value of the stacking volume ratio of the light-transmitting glass balls and the ceramsite, dimensionless.

[0011] As a preferred example, the permeable reactive barrier includes N permeable reactive barrier units. The N permeable reactive barrier units are connected in series. The sealing plate is located on the side where the permeable reactive barrier unit is connected to the groundwater inlet device. The sealing plate is connected to the permeable reactive barrier unit through a guide rail. N is an integer greater than 1.

[0012] As a preferred example, the water collecting device includes a connecting pipe and a water outlet valve. One end of the connecting pipe is connected to the water outlet of the groundwater outlet device, and the other end is connected to the water outlet valve. The metering device includes a flowmeter and a collecting device. The water outlet of the water outlet valve is connected to the flowmeter, and the water outlet of the flowmeter is connected to the collecting device. The monitoring device is connected to the flowmeter.

[0013] In a second aspect, the present invention also provides a working method of the above test equipment for photocatalytically regulating the service performance of the permeable reactive barrier, including: S1. Determine the variation of the groundwater pollutant concentration at the location where the permeable reactive barrier is to be constructed within a set time period according to the groundwater investigation results of the test prototype contaminated site; establish a relationship function between the groundwater pollutant concentration and time based on the variation of the groundwater pollutant within the set time period, and obtain the highest concentration value of the contaminated groundwater required for the test and the lowest concentration value of the contaminated groundwater required for the test; S2. Prepare simulated contaminated groundwater with the same types of groundwater pollutants as those in the test prototype contaminated site and with the highest concentration value of the contaminated groundwater equal, and fill it into the first water storage unit; Prepare simulated contaminated groundwater with the same types of groundwater pollutants as those in the test prototype contaminated site and with the lowest concentration value of the contaminated groundwater equal, and fill it into the second water storage unit; S3. Close the first inlet valve, the second inlet valve, the outlet valve, and the sealing plate; open the second exhaust and water stop valve, and inject degassed clean distilled water into the groundwater outlet device through the water inlet until the clean distilled water fills the groundwater outlet device and the permeable reactive barrier. Exhaust the air in the groundwater outlet device and the permeable reactive barrier by vacuum pumping, and then close the water inlet and the second exhaust and water stop valve; S4. Open the first inlet valve, the second inlet valve, the first exhaust and water stop valve, and the first stirrer; adjust the first flow controller and the second flow controller according to a preset flow ratio to obtain simulated contaminated groundwater with a set concentration; introduce the simulated contaminated groundwater into the groundwater inlet device until the groundwater inlet device is filled with the simulated contaminated groundwater; close the first exhaust and water stop valve, and then evenly mix the simulated contaminated groundwater using the first stirrer; S5. Obtain the data measured by the detection component located in the groundwater inlet device through the monitoring device; when the data measured by the detection component is stable, open the outlet valve, the sealing plate, and the second stirrer, and turn off the ultraviolet light band to make the simulated contaminated groundwater flow through the permeable reactive barrier, the groundwater outlet device, the water collecting device, and the flowmeter in sequence and collect it in the collecting device; Through the monitoring device, record the flow indication of the flowmeter at set time intervals, thereby regulating the first flow controller and the second flow controller so that the difference between the flow measured by the flowmeter and the sum of the flows flowing out from the first flow controller and the second flow controller is less than or equal to a preset flow difference threshold; take samples from the collecting device to test the pollutant concentration until the set effluent volume is reached, so as to obtain the relationship between the effluent pollutant concentration and the effluent volume under the set concentration condition; S6. Close the first inlet valve, the second inlet valve, the sealing plate, the outlet valve, the first stirrer, and the second stirrer, drain the simulated contaminated groundwater in the groundwater inlet device through the first drain port, and close the first drain port after draining; S7. According to the simulated contaminated groundwater of the next set concentration, return to step S4, and in S5, turn on the ultraviolet light band; sample and test the pollutant concentration from the collection device until the set effluent volume is reached, so as to obtain the relationship between the effluent pollutant concentration and the effluent volume under the condition of the next set concentration, until the relationship between the effluent pollutant concentration and the effluent volume under the conditions of the simulated contaminated groundwater of all set concentrations is obtained.

[0014] As a preferred example, the method further includes: S8. Close the ultraviolet light band, the first inlet valve, the second inlet valve, the outlet valve, the first stirrer and the second stirrer, open the sealing plate, and drain the simulated contaminated groundwater in the groundwater inlet device, the permeable reactive barrier, the groundwater outlet device, and the water collection device through the first drain port; drain the simulated contaminated groundwater in the metering device through the drain holes on the collection device.

[0015] Compared with the prior art, the test equipment and method for regulating the service performance of a photocatalytic permeable reactive barrier in an embodiment of the present invention can provide test equipment for the service performance of a permeable reactive barrier and improve the accuracy of the test. The equipment includes a contaminated groundwater simulation device, a groundwater inlet device, a permeable reactive barrier, a groundwater outlet device, a water collection device, a metering device, and a monitoring device. The permeable reactive barrier includes at least one permeable reactive barrier unit. This equipment can complete the test of the service performance of the permeable reactive barrier indoors, providing data support for subsequent service performance evaluation and control parameter optimization. Description of the Drawings

[0016] Figure 1 It is a structural diagram of the equipment in an embodiment of the present invention; Figure 2 It is a schematic structural diagram of the permeable reactive barrier unit in the equipment of an embodiment of the present invention; Figure 3 It is a schematic structural diagram of the sealing plate and the permeable reactive barrier unit in the equipment of an embodiment of the present invention; Figure 4 It is a top view of the sealing plate and the permeable reactive barrier unit in the equipment of an embodiment of the present invention.

[0017] In the figure: there are a contaminated groundwater simulation device 1, a first water storage unit 111, a first flow controller 112, a first inlet valve 113, a second water storage unit 121, a second flow controller 122, a second inlet valve 123, a groundwater inlet device 2, a first housing 201, a first stirrer 202, a detection component 203, a first drain outlet 204, a permeable reactive barrier 3, a third housing 301, a permeable wire mesh 302, an ultraviolet light band 303, a light-transmitting glass sphere 3041, ceramsite 3042, a sealing plate 305, a guide rail 306, a groundwater outlet device 4, a second housing 401, a second stirrer 402, a water inlet 403, a water collecting device 5, an outlet valve 501, a metering device 6, a flowmeter 601, a collecting device 602, and a monitoring device 7. Detailed implementation mode

[0018] The technical solution of the present invention will be described in detail below. The reagents and materials can be obtained from commercial channels without special instructions.

[0019] As Figure 1 As shown, a test device for photocatalytically regulating the service performance of a permeable reactive barrier in an embodiment of the present invention includes a contaminated groundwater simulation device 1, a groundwater inlet device 2, a permeable reactive barrier 3, a groundwater outlet device 4, a water collecting device 5, a metering device 6, and a monitoring device 7. The permeable reactive barrier 3 includes at least one permeable reactive barrier unit. The water outlet of the contaminated groundwater simulation device 1 is connected to the water inlet of the groundwater inlet device 2. The groundwater inlet device 2, the permeable reactive barrier 3, and the groundwater outlet device 4 are connected in sequence. A sealing plate 305 that can move up and down is provided on the side of the permeable reactive barrier 3 close to the groundwater inlet device 2. The sealing plate 305 is used to close or open the water flow channel between the groundwater inlet device 2 and the permeable reactive barrier 3. The water outlet of the groundwater outlet device 4 is connected to the water collecting device 5. The water outlet of the water collecting device 5 is connected to the metering device 6. The monitoring device 7 is respectively connected to the contaminated groundwater simulation device 1, the groundwater inlet device 2, the groundwater outlet device 4, the water collecting device 5, and the metering device 6.

[0020] The test equipment of the above embodiments can complete the test of the service performance of the permeable reactive barrier indoors, providing a reference for optimizing the equipment parameters adopted in the actual application of the permeable reactive barrier. The above test equipment includes a contaminated groundwater simulation device 1, a groundwater inlet device 2, a permeable reactive barrier 3, a groundwater outlet device 4, a water collection device 5, a metering device 6, and a monitoring device 7. The contaminated groundwater simulation device 1 is used to simulate actual contaminated groundwater, including the types and concentrations of pollutants. The contaminated groundwater simulation device 1 injects simulated contaminated groundwater into the groundwater inlet device 2. In the groundwater inlet device 2, the simulated contaminated groundwater is stirred to make it mix evenly, improving the measurement accuracy. The simulated contaminated groundwater flowing out of the groundwater inlet device 2 passes through the permeable reactive barrier 3, and the permeable reactive barrier 3 adsorbs all or part of the pollutants in the simulated contaminated groundwater. The simulated contaminated groundwater flowing out of the permeable reactive barrier 3 flows into the groundwater outlet device 4. After the simulated contaminated groundwater is stirred in the groundwater outlet device 4, it flows into the metering device 6 through the water collection device 5, and the metering device 6 measures the flow rate of the simulated contaminated groundwater flowing out of the water collection device 5. The monitoring device 7 is used to control the opening or closing of the contaminated groundwater simulation device 1, the groundwater inlet device 2, the groundwater outlet device 4, and the water collection device 5. The monitoring device 7 is also used to obtain the flow rate value measured by the metering device 6.

[0021] Preferably, the contaminated groundwater simulation device 1 includes a first water storage unit 111, a first flow controller 112, a first inlet valve 113, a second water storage unit 121, a second flow controller 122, and a second inlet valve 123; the first water storage unit 111 is used to store the contaminated groundwater with the highest concentration required for the test, and the second water storage unit 121 is used to store the contaminated groundwater with the lowest concentration required for the test. The first water storage unit 111 is connected through the first inlet valve 113 and the first flow controller 112, and the outlet of the first flow controller 112 is connected to the groundwater inlet device 2. The second water storage unit 121 is connected through the second inlet valve 123 and the second flow controller 122, and the outlet of the second flow controller 122 is connected to the groundwater inlet device 2. The monitoring device 7 is respectively connected to the first inlet valve 113, the second inlet valve 123, the first flow controller 112, and the second flow controller 122.

[0022] In the above preferred example, according to the results of the groundwater environmental quality investigation of the prototype contaminated site, the change of the concentration of groundwater pollutants at the position where the permeable reactive barrier is to be constructed within a set time period is determined; according to the change of the groundwater pollutants within the set time period, the maximum value of the groundwater pollutant concentration and the minimum value of the groundwater pollutant concentration are obtained. The first water storage unit 111 is used to store the most concentrated contaminated groundwater required for the test. That is, the pollutant concentration of the simulated contaminated groundwater stored in the first water storage unit 111 is equal to the maximum value of the pollutant concentration in the actual contaminated groundwater. The second water storage unit 121 is used to store the least concentrated contaminated groundwater required for the test. That is, the pollutant concentration of the simulated contaminated groundwater stored in the second water storage unit 121 is equal to the minimum value of the pollutant concentration in the actual contaminated groundwater. In this way, by adjusting the flow rates of the first water storage unit 111 and the second water storage unit 121, contaminated groundwater with a set concentration can be obtained. The first inlet valve 113 controls the opening or closing of the first water storage unit 111. When the first inlet valve 113 is opened, the simulated contaminated groundwater flows out of the first water storage unit 111. When the first inlet valve 11 is closed, the simulated contaminated groundwater cannot flow out of the first water storage unit 111. The first flow controller 112 is used to control the flow rate of the simulated contaminated groundwater flowing out of the first water storage unit 111. The second inlet valve 123 controls the opening or closing of the second water storage unit 121. When the second inlet valve 123 is opened, the simulated contaminated groundwater flows out of the second water storage unit 121. The second flow controller 122 is used to control the flow rate of the simulated contaminated groundwater flowing out of the second water storage unit 121. The monitoring device 7 is used to control the opening and closing of the first inlet valve 113 and the second inlet valve 123, and to control the flow rates of the first flow controller 112 and the second flow controller 122.

[0023] Preferably, the groundwater inlet device 2 includes a first housing 201 and a first stirrer 202. The first stirrer 202 is connected to the first housing 201. A detection component 203 is provided on the wall surface of the first housing 201. The detection component 203 is connected to the monitoring device 7; a first drain port 204 is provided at the lower part of the first housing 201, and a first exhaust water stop valve is provided at the top of the first housing 2 at the top of the first housing 201. The groundwater outlet device 4 includes a second housing 401 and a second stirrer 402. The second stirrer 402 is connected to the second housing 401. A water inlet 403 is provided on the top surface of the second housing 401. A second exhaust water stop valve is provided at the top of the second housing 401. The monitoring device 7 is respectively connected to the first stirrer 202 and the second stirrer 402.

[0024] In the above preferred example, the simulated contaminated groundwater flowing out from the first water storage unit 111 and the second water storage unit 121 respectively flows into the groundwater inlet device 2. The first exhaust and water stop valve is opened so that the simulated contaminated groundwater can flow smoothly into the groundwater inlet device 2 and the gas in the groundwater inlet device 2 is discharged. Through the agitation of the first stirrer 202, the simulated contaminated groundwater is evenly mixed in the groundwater inlet device 2, more realistically simulating the actual contaminated groundwater. The detection component 203 is a combination of existing devices. For example, it can include at least two monitoring electrodes for testing pH value, conductivity, and redox potential. Preferably, the detection component 203 is arranged on at least two walls of the first housing 201. That is to say, there are multiple detection components 203, and the detection components 203 are arranged on different walls of the first housing 201. By arranging the detection components 203 at different positions on the first housing 201, the detection accuracy is improved. After the detection component 203 measures the detection value of the simulated contaminated groundwater in the groundwater inlet device 2, the data is transmitted to the monitoring device 7. The simulated contaminated groundwater flowing through the permeable reactive barrier 3 flows into the groundwater outlet device 4. Since the permeable reactive barrier is a porous medium, obvious dispersion phenomenon will occur to the simulated contaminated groundwater flowing through its pores, and there are significant differences in the pollutant concentration in the groundwater across the entire cross-section of the permeable reactive barrier. Therefore, in the embodiment of the present invention, through the agitation of the second stirrer 402, the simulated contaminated groundwater is more evenly mixed in the groundwater outlet device 4. After the pollutant concentration in the groundwater in the groundwater outlet device 4 is uniform, the accuracy of the test can be effectively improved. The conventional method is to increase the sampling volume to achieve the purpose of improving the test accuracy, but it requires a long water outlet collection time. Through comparison, it is found that when continuously collecting 10 samples, with the second stirrer 402 turned on, the coefficient of variation of the pollutant concentration of the 10 samples is 5.2%; when the second stirrer 402 is turned off, the coefficient of variation of the pollutant concentration of the 10 samples is 32.3%. If the coefficient of variation of the sample concentration needs to be 5.2% when the second stirrer 402 is turned off, the number of samples needs to be increased to 32. The water inlet 403 provided on the top surface of the second housing 401 is in a closed state when not in use. A second exhaust and water stop valve is provided at the top of the second housing 401. By opening the second exhaust and water stop valve, clean distilled water can be smoothly injected into the sealed body formed by the permeable reactive barrier 3 and the groundwater outlet device 4, and the gas in the sealed body is discharged. The monitoring device 7 is respectively connected to the first stirrer 202 and the second stirrer 402, and is used to control the operation of the first stirrer 202 and the second stirrer 402. Through the contaminated groundwater simulation device 1 and the groundwater inlet device 2, contaminated groundwater with a required pollution concentration can be simulated. By reasonably setting the flow rates of the first water storage unit 111 and the second water storage unit 121, it is possible to achieve the mixing of the simulated contaminated groundwater flowing out from the two in the groundwater inlet device 2 to form contaminated groundwater with a required pollution concentration.

[0025] In the above preferred example, the first stirrer 202 and the second stirrer 402 have the same structure. The first stirrer 202 includes a servo motor and stirring blades. The stirring blades are connected to the servo motor through a stirring shaft. The servo motor drives the stirring blades to rotate through the stirring shaft. The length of each stirring blade is between 35% and 45% of the minimum length among the length, width, and height of the groundwater inlet device 2. This can achieve uniform distribution of pollutants in the inner cavity of the groundwater inlet device 2. If the stirring blades are too short, pollutants will accumulate in the corners of the groundwater inlet device 2, increasing the concentration distribution difference; if the length of the stirring blades is too long, it will affect the groundwater flow, form turbulence, resulting in a large difference in the adsorption amount of pollutants in different spaces within the permeable reactive device, causing a large change in the concentration of the effluent pollutants and reducing the accuracy of the test.

[0026] Preferably, the water outlet of the groundwater outlet device 4 is located on the side of the second housing 401 away from the groundwater inlet device 2, and there are at least two water outlets, and at least two water outlets are at different heights. By setting the water outlets at different heights, the simulated polluted groundwater at different heights in the groundwater outlet device 4 flows out and converges into the same water collecting device 5 for mixing. Although there is a second stirrer 402 in the groundwater outlet device 4, it is impossible to ensure that the pollution concentrations of the simulated polluted groundwater at different heights in the groundwater outlet device 4 are the same. Therefore, water outlets are provided at different heights on the side of the groundwater outlet device 4, so that the simulated polluted groundwater at different heights converges to uniformly simulate the concentration of polluted groundwater.

[0027] As Figure 2 shown, preferably, the permeable reactive barrier unit includes a hollow third housing 301. The two relatively hollowed-out sides of the third housing 301 are respectively sealed and connected to the first housing 201 and the second housing 401. Permeable gauze meshes 302 are respectively provided on the two relatively hollowed-out sides of the third housing 301. Preferably, the porosity of the permeable gauze mesh 302 is greater than 80%. Granular fillers are installed inside the third housing 301, and an ultraviolet light band 303 is arranged inside the granular fillers. The two power supply terminals of the ultraviolet light band 303 are respectively connected to the positive and negative poles of an external power supply. The granular fillers include light-transmitting glass balls 3041 and ceramsite with titanium dioxide loaded on the surface 3042.

[0028] In the above preferred example, if the permeable reactive barrier 3 only includes one permeable reactive barrier unit, and the two relatively hollow sides of the third housing 301 are hermetically connected to the first housing 201 and the second housing 401 respectively, then the housings of the groundwater inlet device 2, the permeable reactive barrier 3, and the groundwater outlet device 4 form a sealed whole. Through the sealing of the three, the contact between the contaminated groundwater and the atmospheric environment can be cut off, preventing the atmosphere from entering the liquid. The formed bubbles will agglomerate in the filler of the permeable reactive barrier, affecting the contact area between the pollutants and the filler, thereby increasing the test error. In addition, after the simulated contaminated groundwater enters the groundwater inlet device 2, it flows through the permeable reactive barrier 3 and the groundwater outlet device 4 and flows out from the groundwater outlet device 4. During this process, the simulated contaminated groundwater will not overflow, ensuring the balance of the water inflow and outflow during the test and improving the test accuracy of the pollutant concentration. The simulated contaminated groundwater passes through the water-permeable gauze 302 on one side of the permeable reactive barrier unit and flows into the inner cavity of the third housing 301. It flows through the granular filler and flows out from the water-permeable gauze 302 on the other side of the permeable reactive barrier unit. During this process, the granular filler adsorbs the pollutants in the simulated contaminated groundwater, thereby purifying the groundwater. When the ultraviolet light band 303 is turned on, the granular filler includes light-transmitting glass balls 3041 and ceramsite 3042 with titanium dioxide loaded on the surface. After the ultraviolet light band 303 emits ultraviolet light, the ultraviolet light irradiates the surface of the titanium dioxide loaded on the ceramsite 3042 to generate electron-hole pairs, which react with the contacted water molecules to generate hydroxyl radicals. These hydroxyl radicals gradually degrade the organic pollutants into small molecule intermediate products through oxidation and finally mineralize them into CO2 and H2O. Since the ceramsite 3042 is an opaque material, the propagation distance of the ultraviolet light in the permeable reactive barrier is very short, and the maximum distance is about 5 times the diameter of the granular filler. Therefore, in the embodiment of the present invention, by adding the light-transmitting glass balls 3041 to the filler, the ultraviolet light can pass through the light-transmitting glass balls 3041 and refract on the surface of the light-transmitting glass balls 3041, thereby greatly increasing the irradiation area of the ultraviolet light and the ceramsite 3042. For example, after mixing the ceramsite 3042 and the light-transmitting glass balls 3041 with a volume ratio of 1:1, the axial irradiation area of a single ultraviolet light band 303 can be increased by about 7 times, greatly improving the catalytic efficiency of the light source.

[0029] By adding fillers with the ability to adsorb pollutants and photocatalytically degrade pollutants into the permeable reactive barrier unit and introducing an external light source. When the ultraviolet light band 303 is turned off, when simulating the flow of contaminated groundwater through the permeable reactive barrier, the pollutants are adsorbed and fixed in the permeable reactive barrier through the adsorption of the fillers. When the ultraviolet light band 303 is turned on, when simulating the flow of contaminated groundwater through the permeable reactive barrier, on the one hand, the pollutants are adsorbed and fixed in the permeable reactive barrier through the adsorption of the fillers, and on the other hand, the pollutants desorbed and released from the fillers are catalytically degraded through photocatalysis. After the pollutants adsorbed on the fillers are degraded, they diffuse reversely into the groundwater, reducing the frequency of filler replacement. In particular, in sites with high-frequency changes in groundwater organic pollutants, the operating efficiency of the permeable reactive barrier is improved through the permeable reactive barrier of this embodiment.

[0030] The permeable reactive barrier has two functions: one is to adsorb pollutants in groundwater; the other is to degrade and remove the pollutants that may be released into the groundwater again from the fillers adsorbed previously through the catalytic action of the ultraviolet light band. In other words, in order to prevent the released pollutants from migrating downstream again, the embodiment of the present invention proposes a permeable reactive barrier with photocatalytic regulation function, which catalytically degrades the pollutants after they are desorbed from the fillers, preventing the pollutants from returning to the water flow again. In this way, using the fillers in the permeable reactive barrier unit, not only can the pollutants in the simulated contaminated groundwater be adsorbed, but also the pollutants can be degraded and released into the groundwater again.

[0031] Preferably, in each of the permeable reactive barrier units, the buried length of the ultraviolet light band (303) is determined according to Formula (1) and Formula (2): Formula (1) Formula (2) In the formula, represents the buried length of the ultraviolet light band 303, with the unit of cm; represents the length of the permeable reactive barrier unit, with the unit of cm; represents the width of the permeable reactive barrier unit, with the unit of cm; represents the height of the permeable reactive barrier unit, with the unit of cm; represents the radial effective irradiation area of a single ultraviolet light band 303, with the unit of cm 2 ; represents the reduction coefficient of the radial effective irradiation area of the ultraviolet light band 303, dimensionless; represents the packed volume of the light-transmitting glass balls 3041, with the unit of cm 3 ; represents the packed volume of the ceramsite 3042, with the unit of cm 3 ; It represents the reference value of the bulk volume ratio of the light-transmitting glass balls 3041 and the ceramsite 3042, dimensionless. The value range is 0.8 to 2.3.

[0032] In the above preferred example, by setting the embedding length of the ultraviolet light band 303, quantitative data support can be provided for optimizing the service performance of the permeable reaction barrier. For example, when the granular filler changes, the length of the ultraviolet light band also needs to be adjusted accordingly. This can maximize the catalytic effect of the ultraviolet light and reduce the energy input.

[0033] Such as Figure 3 and Figure 4 As shown, preferably, the permeable reaction barrier 3 includes N permeable reaction barrier units, and the N permeable reaction barrier units are connected in series. The sealing plate 305 is located on the side where the permeable reaction barrier unit is connected to the groundwater inlet device 2, and the sealing plate 305 is connected to the permeable reaction barrier unit through the guide rail 306; N is an integer greater than 1.

[0034] In the above preferred example, when the permeable reaction barrier 3 includes multiple permeable reaction barrier units, the multiple permeable reaction barrier units are connected in series, that is, the third shells 301 of the multiple permeable reaction barrier units are sequentially sealed and connected, and granular filler is installed in the third shell 301 of each permeable reaction barrier unit. The third shell 301 of the outermost permeable reaction barrier unit at one end of the permeable reaction barrier 3 is sealed and connected to the first shell 201; the third shell 301 of the outermost permeable reaction barrier unit at the other end of the permeable reaction barrier 3 is sealed and connected to the second shell 401. In this way, the shells of the groundwater inlet device 2, the permeable reaction barrier 3, and the groundwater outlet device 4 form a sealed whole. Only one sealing plate 305 is provided for the entire device. The sealing plate 305 is connected to the third shell 301 of the permeable reaction barrier unit directly connected to the first shell 201. The sealing plate 305 is connected to the permeable reaction barrier unit through the guide rail 306. The sealing plate 305 can move up and down along the guide rail 306. By moving the sealing plate 305, the contaminated groundwater flow channel between the groundwater inlet device 2 and the permeable reaction barrier 3 is controlled to be opened or closed.

[0035] Such as Figure 1As shown, preferably, the water collecting device 5 includes a connecting pipe and a water outlet valve 501; one end of the connecting pipe is connected to the water outlet of the groundwater outlet device 4, and the other end is connected to the water outlet valve 501. The water collecting device 5 is used to converge the liquids flowing out of the water outlets at different positions of the groundwater outlet device 4 into one path and inject them into the metering device 6. The number of water outlets of the groundwater outlet device 4 is equal to the number of connecting pipes. One connecting pipe is connected to one water outlet of the groundwater outlet device 4. Through one water outlet valve 501, the simulated contaminated groundwater in all the connecting pipes is converged into one path. The concentrations of the simulated contaminated groundwater flowing out of the water outlets at different positions may be different. This preferred example can improve the uniformity of the concentration of the simulated contaminated groundwater flowing out of the groundwater outlet device 4. For example, the groundwater outlet device 4 is provided with 4 water outlets, which are respectively close to the four corners of the periphery. The metering device 6 includes a flowmeter 601 and a collecting device 602. The water outlet of the water outlet valve 501 is connected to the flowmeter 601, and the water outlet of the flowmeter 601 is connected to the collecting device 602. The flowmeter 601 is used to measure the flow rate data of the simulated contaminated groundwater flowing out of the water outlet valve 501 and transmit this data to the monitoring device 7.

[0036] The present invention also provides a working method of an experimental device for regulating the service performance of a photocatalytic permeable reactive barrier using the above-mentioned embodiment or preferred example, including: S1. According to the groundwater investigation results of the experimental prototype contaminated site, determine the change situation of the concentration of groundwater pollutants at the position where the permeable reactive barrier is planned to be built within a set time period; according to the change situation of the groundwater pollutants within the set time period, establish a relationship function between the concentration of groundwater pollutants and time, and obtain the highest concentration value of the contaminated groundwater required for the experiment and the lowest concentration value of the contaminated groundwater required for the experiment.

[0037] Before the test equipment operates, first obtain the groundwater investigation results of the contaminated site of the test prototype. Divide the proposed research time period into several sub-intervals, with each sub-interval being 0.5 to 1 month long. Take the average value of the pollutant concentrations measured each time within each sub-interval as the representative value of the pollutant concentration for that sub-interval. For example, in the most recent year, obtain the types and concentrations of groundwater pollutants at the prototype contaminated site on a monthly basis. Among them, take the arithmetic mean of the daily measured groundwater pollutant concentrations as the representative value of the monthly groundwater pollutant concentration. Based on the groundwater investigation results of the test prototype contaminated site, establish a relationship function between the groundwater pollutant concentration and time. This function represents the variation characteristics of the groundwater pollutant concentration within a certain time range. Usually, those skilled in the art design the permeable reactive barrier using a conservative design method, that is, design according to the maximum pollutant concentration value. This design method causes waste of the filler and increases the operating cost of the permeable reactive barrier. At a site where the groundwater pollutant concentration varies greatly, by dividing the pollutant concentration into several time periods through this function, the burial length of the ultraviolet light band 303 can be set according to the pollutant concentration value of each time period, thereby improving the service performance of the permeable reactive barrier.

[0038] Before the test equipment operates, install the test equipment. Fill the permeable reactive barrier unit with saturated granular filler. Connect the simulated contaminated groundwater device 1, the groundwater inlet device 2, the permeable reactive barrier 3, the groundwater outlet device 4, the water collection device 5, and the metering device 6 in sequence, and connect the monitoring device 7 to the simulated contaminated groundwater device 1, the groundwater inlet device 2, the groundwater outlet device 4, the water collection device 5, and the metering device 6 respectively.

[0039] S2. Prepare simulated contaminated groundwater with the same types of groundwater pollutants as those at the contaminated site of the test prototype and with the same maximum concentration value of the contaminated groundwater, and load it into the first water storage unit 111; prepare simulated contaminated groundwater with the same types of groundwater pollutants as those at the contaminated site of the test prototype and with the same minimum concentration value of the contaminated groundwater, and load it into the second water storage unit 121.

[0040] Step S2 is to prepare simulated contaminated groundwater based on the maximum value of the groundwater pollutant concentration and the minimum value of the groundwater pollutant concentration obtained in step S1. In the first water storage unit 111, prepare simulated contaminated groundwater with the same types of groundwater pollutants as those at the contaminated site of the test prototype and with the same maximum pollutant concentration value. In the second water storage unit 121, prepare simulated contaminated groundwater with the same types of groundwater pollutants as those at the contaminated site of the test prototype and with the same minimum pollutant concentration value. By regulating the flow rates of the first water storage unit 111 and the second water storage unit 121 in subsequent steps, simulated contaminated groundwater with the required pollution concentration and types of pollutants can be obtained at the groundwater inlet device 2.

[0041] S3. Close the first water inlet valve 113, the second water inlet valve 123, the water outlet valve 501, and the sealing plate 305; open the second exhaust water stop valve, and inject degassed clean distilled water into the groundwater outlet device 4 through the water inlet 403 until the clean distilled water fills the groundwater outlet device 4 and the permeable reactive barrier 3. Exhaust the air in the groundwater outlet device 4 and the permeable reactive barrier 3 by vacuuming, and then close the water inlet 403 and the second exhaust water stop valve.

[0042] S4. Open the first water inlet valve 113, the second water inlet valve 123, the first exhaust water stop valve, and the first stirrer 202. Adjust the first flow controller 112 and the second flow controller 122 according to the preset flow ratio to obtain simulated contaminated groundwater with a set pollutant concentration; introduce the simulated contaminated groundwater into the groundwater inlet device 2 until the groundwater inlet device 2 is filled with the simulated contaminated groundwater; close the first exhaust water stop valve, and then use the first stirrer 202 to uniformly mix the simulated contaminated groundwater.

[0043] S5. Obtain the data measured by the detection component 203 located in the groundwater inlet device 2 through the monitoring device 7; when the data measured by the detection component 203 is stable, open the water outlet valve 501, the sealing plate 305, and the second stirrer 402, and turn off the ultraviolet light band 303 to make the simulated contaminated groundwater flow through the permeable reactive barrier 3, the groundwater outlet device 4, the water collecting device 5, and the flowmeter 601 in sequence, and collect it in the collecting device 602; Through the monitoring device 7, record the flow indication of the flowmeter 601 at set time intervals, so as to adjust the first flow controller 112 and the second flow controller 122, so that the difference between the flow measured by the flowmeter 601 and the sum of the flows flowing out of the first flow controller 112 and the second flow controller 122 is less than or equal to the preset flow difference threshold; take samples from the collecting device 602 to test the pollutant concentration until the set effluent volume is reached, so as to obtain the relationship between the effluent pollutant concentration and the effluent volume under the set concentration conditions.

[0044] S6. Close the first water inlet valve 113, the second water inlet valve 123, the sealing plate 305, the water outlet valve 501, the first stirrer 202, and the second stirrer 402, and drain the simulated contaminated groundwater in the groundwater inlet device 2 through the first drain port 204. After emptying, close the first drain port 204.

[0045] S7. According to the simulated contaminated groundwater of the next set concentration, return to step S4. In S5, turn on the ultraviolet light band 303; sample and test the pollutant concentration from the collection device 602 until the set effluent volume is reached, so as to obtain the relationship between the effluent pollutant concentration and the effluent volume under the condition of the next set concentration, until the relationship between the effluent pollutant concentration and the effluent volume under the conditions of the simulated contaminated groundwater of all set concentrations is obtained.

[0046] In the above method, in step S3, close the first inlet valve 113, the second inlet valve 123, the outlet valve 501, and the sealing plate 305. In this way, the groundwater outlet device 4 and the permeable reactive barrier 3 form a closed body, and the groundwater inlet device 2 forms another closed body. Open the second exhaust water stop valve and fill the groundwater outlet device 4 and the permeable reactive barrier 3 with clean distilled water. In step S4, fill the groundwater inlet device 2 with the simulated contaminated groundwater. In step S5, when the sealing plate 305 is turned on, since both closed bodies on both sides of the sealing plate 305 are filled with liquid and there is no pressure difference between the two sides. Under the control of the first flow controller 112 and the second flow controller 122, the simulated contaminated groundwater flows uniformly from the groundwater inlet device 2 through the permeable reactive barrier 3, the groundwater outlet device 4, and into the water collection device 5. The permeable reactive barrier 3 is a porous medium, and the contaminated groundwater flowing through it will produce a dispersion phenomenon, resulting in a significant difference in the pollutant concentration in the groundwater across the entire cross-section of the permeable reactive barrier 3. The degree of dispersion and migration of groundwater pollutants is directly related to the groundwater flow velocity, that is: the greater the groundwater flow velocity, the greater the distribution difference of the pollutant concentration across the cross-section of the permeable reactive barrier 3. Therefore, during the test, it is necessary to strictly control the flow velocity of the simulated contaminated groundwater to minimize the negative impact of the dispersion and migration of pollutants in the contaminated groundwater on the test results. In the above method, in step S4, since the concentrations of the simulated contaminated groundwater simulated at different times are different, the first flow controller 112 and the second flow controller 122 are adjusted to control the flow rates of the first water storage unit 111 and the second water storage unit 121 to obtain the simulated contaminated groundwater with the set pollutant concentration.

[0047] In the above method, in step S5, through the monitoring device 7, the data measured by the detection component 203 located in the groundwater inlet device 2 is obtained. The detection component 203 measures the detection data of the simulated contaminated groundwater at different positions in the groundwater inlet device 2. When the data measured by each detection component 203 is stable, for example, the difference in the same parameter measured by each detection component 203 is less than a preset threshold, it can be considered that the simulated contaminated groundwater in the groundwater inlet device 2 is mixed evenly and is the simulated contaminated groundwater with the required concentration. Open the water outlet valve 501, the sealing plate 305, the second stirrer 402, and the ultraviolet light band 303, so that the simulated contaminated groundwater flows through the permeable reactive barrier 3, the groundwater outlet device 4, the water collecting device 5, and the flow meter 601 in sequence, and is collected in the collecting device 602. In the permeable reactive barrier 3, the filler adsorbs all or part of the pollutants in the simulated contaminated groundwater. Using the ultraviolet light band 303, the pollutants adsorbed by the filler are released from the filler and degraded. In the groundwater outlet device 4, the second stirrer 402 stirs the treated simulated contaminated groundwater to make the simulated contaminated groundwater mix more evenly. The water collecting device 5 converges the simulated contaminated groundwater flowing out of the groundwater outlet device 4 into one path and guides it to the flow meter 601. The flow meter 601 records the flow rate of the simulated contaminated groundwater flowing through it and transmits the flow rate data to the monitoring device 7. The monitoring device 7 records the flow rate indication of the flow meter 601 at a set time interval, thereby regulating the first flow controller 112 and the second flow controller 122, so that the difference between the flow rate measured by the flow meter 601 and the sum of the flow rates flowing out of the first flow controller 112 and the second flow controller 122 is less than or equal to a preset flow rate difference threshold, and the water flow is stable. This also ensures that the simulated contaminated groundwater flows evenly in the groundwater inlet device 2, the permeable reactive barrier 3, and the groundwater outlet device 4. If the difference between the two is greater than the preset flow rate difference threshold, the water flow is unstable, affecting the accuracy of the test. Take a sample from the collecting device 602 to test the pollutant concentration, and obtain the service performance test results of the permeable reactive barrier 3 under the set groundwater pollutant concentration conditions.

[0048] In step S6, since it is necessary to replace the simulated contaminated groundwater with different concentrations, it is necessary to drain the simulated contaminated groundwater simulated last time in the groundwater inlet device 2, but the simulated contaminated groundwater simulated last time still remains in the permeable reactive barrier 3 and the groundwater outlet device 4. In this way, the simulation is continuous in time and more truly reflects the real scenario.

[0049] In step S7, return to step S4 to configure the simulated polluted groundwater at the concentration required for this test. In S5, turn on the ultraviolet light band 303. Using the ultraviolet light band 303, release the pollutants adsorbed by the packing in the previous simulation and decompose the pollutants. In this way, the adsorption performance of the packing for pollutants is restored, and the pollutants are prevented from returning to the groundwater to pollute the downstream groundwater. Enter step S6, take samples from the collection device 602 to test the pollutant concentration until the set effluent volume is reached, so as to obtain the relationship between the effluent pollutant concentration and the effluent volume under the next set concentration condition. By changing the flow rates of the first flow controller 112 and the second flow controller 122, and changing the concentration of the simulated polluted groundwater, test the effluent pollutant concentration of the groundwater outlet device 4 at different flow rates, obtain the relationship between the effluent pollutant concentration of the groundwater outlet device 4 and the effluent volume, and obtain the service performance test results of the permeable reactive barrier 3. According to the corresponding relationship between the time and the groundwater pollutant concentration determined in the function of the relationship between the groundwater pollutant concentration and time obtained in step S1, perform the corresponding number of simulations according to the time. For each simulation, use the groundwater pollutant concentration corresponding to the time. Repeat steps S4 - S7 until the relationship between the effluent pollutant concentration and the effluent volume is obtained under the conditions of simulated polluted groundwater at all set concentrations.

[0050] After the test, preferably, the working method further includes: S8. Close the ultraviolet light band 303, the first inlet valve 113, the second inlet valve 123, the outlet valve 501, the first stirrer 202 and the second stirrer 402, open the sealing plate 305, and drain the simulated polluted groundwater in the groundwater inlet device 2, the permeable reactive barrier 3, the groundwater outlet device 4, and the water collecting device 5 through the first drain port 204; drain the simulated polluted groundwater in the metering device 6 through the drain hole on the collection device 602.

[0051] After the test, close the ultraviolet light band 303, the first inlet valve 113, the second inlet valve 123, the outlet valve 501, the first stirrer 202 and the second stirrer 402, and open the sealing plate 305. At this time, the groundwater inlet device 2, the permeable reactive barrier 3, and the groundwater outlet device 4 form an integral body, and drain the simulated polluted groundwater in the groundwater inlet device 2, the permeable reactive barrier 3, the groundwater outlet device 4, and the water collecting device 5 through the first drain port 204 located on the groundwater inlet device 2. [[ID=io]]

[0052] In the equipment and method of the above embodiment, through the design of a fully enclosed housing, that is, the first housing 201, the third housing 301, and the second housing 401 are connected to form a closed whole, precise control of the simulated contaminated groundwater flow rate is achieved, and it is possible to truly simulate the groundwater passing through the permeable reactive barrier at a constant speed. In the case of a non-closed housing, the flow process of groundwater is simulated through the water level difference upstream and downstream of the permeable reactive barrier. In this case, the groundwater flow velocity is in a dynamic change, and the variation in the concentration of the effluent pollutants collected is very large, which is quite different from the real environment, and the collected data is inaccurate.

[0053] In the equipment and method of the above embodiment, the processes of adsorption, desorption, and degradation of pollutants by ceramsite with titanium dioxide loaded on the surface are regulated through photocatalysis, and the service performance of the permeable reactive barrier under the condition of drastic changes in groundwater pollution concentration is tested through indoor experiments, providing data support for the optimized design of the service performance of the permeable reactive barrier.

[0054] The above has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above specific embodiments, and the descriptions in the above specific embodiments and the specification are only for further explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. An experimental device for photocatalytically regulating the service performance of a permeable reaction barrier, characterized in that, The device includes a contaminated groundwater simulation device (1), a groundwater inlet device (2), a permeable reactive barrier (3), a groundwater outlet device (4), a water collection device (5), a metering device (6), and a monitoring device (7). The permeable reactive barrier (3) includes at least one permeable reactive barrier unit. Among them, the water outlet of the contaminated groundwater simulation device (1) is connected to the water inlet of the groundwater inlet device (2). The groundwater inlet device (2), the permeable reactive barrier (3), and the groundwater outlet device (4) are connected in sequence. A movable sealing plate (305) is provided on the side of the permeable reactive barrier (3) close to the groundwater inlet device (2). The sealing plate (305) is used to close or open the water flow channel between the groundwater inlet device (2) and the permeable reactive barrier (3). The water outlet of the groundwater outlet device (4) is connected to the water collection device (5), and the water outlet of the water collection device (5) is connected to the metering device (6). The monitoring device (7) is respectively connected to the contaminated groundwater simulation device (1), the groundwater inlet device (2), the groundwater outlet device (4), the water collection device (5), and the metering device (6).

2. The test equipment for photocatalytically regulating the service performance of a permeable reaction barrier according to claim 1, characterized in that, The contaminated groundwater simulation device (1) includes a first water storage unit (111), a first flow controller (112), a first water inlet valve (113), a second water storage unit (121), a second flow controller (122), and a second water inlet valve (123). The first water storage unit (111) is used to store the most concentrated contaminated groundwater required for the test, and the second water storage unit (121) is used to store the least concentrated contaminated groundwater required for the test. The first water storage unit (111) is connected through the first water inlet valve (113) and the first flow controller (112), and the water outlet of the first flow controller (112) is connected to the groundwater inlet device (2). The second water storage unit (121) is connected through the second water inlet valve (123) and the second flow controller (122), and the water outlet of the second flow controller (122) is connected to the groundwater inlet device (2). The monitoring device (7) is respectively connected to the first water inlet valve (113), the second water inlet valve (123), the first flow controller (112), and the second flow controller (122).

3. The test equipment for photocatalytically regulating the service performance of a permeable reactive barrier according to claim 1, wherein The groundwater inlet device (2) includes a first housing (201) and a first stirrer (202). The first stirrer (202) is connected to the first housing (201). A detection component (203) is provided on the wall surface of the first housing (201), and the detection component (203) is connected to the monitoring device (7). A first drain port (204) is provided at the lower part of the first housing (201), and a first exhaust and water stop valve is provided at the top of the first housing (201). The groundwater outlet device (4) includes a second housing (401) and a second stirrer (402). The second stirrer (402) is connected to the second housing (401). A water inlet (403) is provided on the top surface of the second housing (401), and a second exhaust and water stop valve is provided at the top of the second housing (401). The monitoring device (7) is respectively connected to the first stirrer (202) and the second stirrer (402).

4. The test equipment for photocatalytically regulating the service performance of a permeable reactive barrier according to claim 3, characterized in that, The water outlet of the groundwater outlet device (4) is located on the side of the second housing (401) away from the groundwater inlet device (2), and there are at least two water outlets, and at least two water outlets are at different heights.

5. The test equipment for photocatalytically regulating the service performance of a permeable reactive barrier according to claim 3, characterized in that, The permeable reactive barrier unit includes a hollow third housing (301). The two relatively hollowed sides of the third housing (301) are respectively and hermetically connected to the first housing (201) and the second housing (401). Permeable gauzes (302) are respectively provided on the two relatively hollowed sides of the third housing (301); granular fillers are installed in the third housing (301), and an ultraviolet light band (303) is arranged inside the granular fillers. The two power supply terminals of the ultraviolet light band (303) are respectively connected to the positive and negative electrodes of an external power supply; the granular fillers include light-transmitting glass balls (3041) and ceramsite with titanium dioxide loaded on the surface (3042).

6. The test equipment for photocatalytically regulating the service performance of a permeable reactive barrier according to claim 5, characterized in that In each of the permeable reactive barrier units, the buried length of the ultraviolet light band (303) is determined according to formulas (1) and (2): Formula (1) Formula (2) In the formula, represents the embedded length of the ultraviolet light band (303), in cm; represents the length of the permeable reactive barrier unit, in cm; represents the width of the permeable reactive barrier unit, in cm; represents the height of the permeable reactive barrier unit, in cm; represents the radial effective irradiation area of one ultraviolet light band (303), in cm 2 ; represents the reduction coefficient of the radial effective irradiation area of the ultraviolet light band (303), dimensionless; represents the packed volume of the light-transmitting glass balls (3041), in cm 3 ; represents the packed volume of the ceramsite (3042), in cm 3 ; represents the reference value of the packed volume ratio of the light-transmitting glass balls (3041) and the ceramsite (3042), dimensionless.

7. The test equipment for photocatalytically regulating the service performance of a permeable reactive barrier according to claim 1, characterized in that, The permeable reactive barrier (3) includes N permeable reactive barrier units, and the N permeable reactive barrier units are connected in series. The sealing plate (305) is located on the side where the permeable reactive barrier unit is connected to the groundwater inlet device (2), and the sealing plate (305) is connected to the permeable reactive barrier unit through a guide rail (306); N is an integer greater than 1.

8. The test equipment for photocatalytically regulating the service performance of a permeable reactive barrier according to claim 1, characterized in that, The water collecting device (5) includes a connecting pipe and a water outlet valve (501); one end of the connecting pipe is connected to the water outlet of the groundwater outlet device (4), and the other end is connected to the water outlet valve (501); The metering device (6) includes a flow meter (601) and a collecting device (602). The water outlet of the water outlet valve (501) is connected to the flow meter (601), and the water outlet of the flow meter (601) is connected to the collecting device (602); The monitoring device (7) is connected to the flow meter (601).

9. A working method of a test device for photocatalytically regulating the service performance of a permeable reaction barrier according to any one of claims 1 to 8, characterized in that, The method includes: S1. According to the groundwater investigation results of the test prototype contaminated site, determine the change of the groundwater pollutant concentration at the location where the permeable reactive barrier is to be built within a set time period; according to the change of the groundwater pollutant within the set time period, establish a relationship function between the groundwater pollutant concentration and time, and obtain the highest concentration value of the contaminated groundwater required for the test and the lowest concentration value of the contaminated groundwater required for the test; S2. Prepare simulated contaminated groundwater with the same types of groundwater pollutants as those in the test prototype contaminated site and the same highest concentration value of the contaminated groundwater, and load it into the first water storage unit (111); Prepare simulated contaminated groundwater with the same types of groundwater pollutants as those in the test prototype contaminated site and the same lowest concentration value of the contaminated groundwater, and load it into the second water storage unit (121); S3. Close the first inlet valve (113), the second inlet valve (123), the outlet valve (501), and the sealing plate (305); open the second exhaust and water stop valve, and inject degassed clean distilled water into the groundwater outlet device (4) through the water inlet (403) until the groundwater outlet device (4) and the permeable reactive barrier (3) are filled with clean distilled water. Exhaust the air in the groundwater outlet device (4) and the permeable reactive barrier (3) by vacuum pumping, and then close the water inlet (403) and the second exhaust and water stop valve; S4. Open the first inlet valve (113), the second inlet valve (123), the first exhaust and water stop valve, and the first stirrer (202); adjust the first flow controller (112) and the second flow controller (122) according to the preset flow ratio to obtain simulated contaminated groundwater with a set concentration; introduce the simulated contaminated groundwater into the groundwater inlet device (2) until the groundwater inlet device (2) is filled with the simulated contaminated groundwater; close the first exhaust and water stop valve, and then use the first stirrer (202) to uniformly mix the simulated contaminated groundwater; S5. Obtain the data measured by the detection component (203) located in the groundwater inlet device (2) through the monitoring device (7); when the data measured by the detection component (203) is stable, open the outlet valve (501), the sealing plate (305), and the second stirrer (402), and close the ultraviolet light band (303) to make the simulated contaminated groundwater flow through the permeable reactive barrier (3), the groundwater outlet device (4), the water collecting device (5), the flowmeter (601) in sequence, and collect it in the collecting device (602); Through the monitoring device (7), record the flow indication of the flowmeter (601) at set time intervals, so as to adjust the first flow controller (112) and the second flow controller (122) to make the difference between the flow measured by the flowmeter (601) and the sum of the flows flowing out from the first flow controller (112) and the second flow controller (122) less than or equal to the preset flow difference threshold; take samples from the collecting device (602) to test the pollutant concentration until the set effluent volume is reached, so as to obtain the relationship between the effluent pollutant concentration and the effluent volume under the set concentration condition; S6. Close the first inlet valve (113), the second inlet valve (123), the sealing plate (305), the outlet valve (501), the first stirrer (202), and the second stirrer (402), drain the simulated contaminated groundwater in the groundwater inlet device (2) through the first drain port (204), and close the first drain port (204) after emptying; S7. According to the simulated contaminated groundwater with the next set concentration, return to step S4, and in S5, open the ultraviolet light band (303); take samples from the collecting device (602) to test the pollutant concentration until the set effluent volume is reached, so as to obtain the relationship between the effluent pollutant concentration and the effluent volume under the next set concentration condition until the relationship between the effluent pollutant concentration and the effluent volume under the conditions of all the simulated contaminated groundwater with set concentrations is obtained.

10. The working method of the test equipment for photocatalytically regulating the service performance of a permeable reactive barrier according to claim 9, characterized in that, It also includes: S8. Close the ultraviolet light band (303), the first inlet valve (113), the second inlet valve (123), the outlet valve (501), the first stirrer (202) and the second stirrer (402), open the sealing plate (305), and drain the simulated contaminated groundwater in the groundwater inlet device (2), the permeable reactive barrier (3), the groundwater outlet device (4), and the water collection device (5) through the first drain port (204); drain the simulated contaminated groundwater in the metering device (6) through the drain holes on the collection device (602).

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