Permeable reactive system for organic fluorine-contaminated soil and method of operating the same

Abstract

The present application provides a kind of for the permeability reaction system of organic fluorine compound contaminated soil, including permeability reaction barrier, upstream monitoring well and downstream monitoring well;Permeability reaction barrier includes several permeability reaction modules, permeability reaction module includes hollow shell, and shell is provided with water-permeable screen relative to two hollow sides respectively;Hollow shell is loaded with granular filler, and granular filler is internally provided with ultraviolet light band;Granular filler includes light-transmitting glass ball and the ceramicite of surface load titanium dioxide;Upstream monitoring well is located in the upstream of permeability reaction barrier, and downstream monitoring well is located in the downstream of permeability reaction barrier;Upstream monitoring well and downstream monitoring well are equipped with detection component in it.The present application provides a kind of for the permeability reaction system of organic fluorine compound contaminated soil, improves the operating efficiency of permeability reaction barrier in organic fluorine compound contaminated layer soil, reduces cost.

Description

Technical Field

[0001] This invention belongs to the field of water pollution control and treatment technology. Specifically, it relates to a permeable reaction system for the remediation of groundwater in soil contaminated with organic fluorides and its operation method. Background Technology

[0002] Industries such as chemical, electroplating, metallurgy, and fire protection may experience leaks of organic fluoride (Ofluorinolates) during production or use, which can enter groundwater through wastewater discharge or soil infiltration. Ofluoride is difficult to degrade and easily accumulates; long-term exposure may cause liver toxicity, reproductive disorders, and thyroid diseases. Once contaminated with groundwater, it can accumulate through the food chain, threatening ecosystems and human health. Furthermore, numerous industrial projects are built along rivers and streams, resulting in typical layered distribution of floodplain strata on both banks. These layered strata often contain numerous contaminant migration channels, posing a significant challenge to the risk management and remediation of contaminated groundwater.

[0003] A permeable reactive barrier (PRB) is a device used for in-situ remediation of contaminated groundwater. It involves filling a strip of permeable material downstream of the groundwater flow, causing a series of physical and chemical reactions between the flowing contaminated groundwater and the material, thereby removing or degrading pollutants and controlling the spread of the contamination plume. It has been successfully applied in an increasing number of groundwater remediation projects at contaminated sites. However, for industrial sites in floodplains, the concentration of organic fluoride compounds in the groundwater is low, and the concentration of groundwater pollutants varies significantly with seasonal and climatic changes. Typically, to ensure effective removal of groundwater pollutants in such sites, the selection of PRB filler type and the design optimization of filler replacement cycle are often based on the highest monitored groundwater pollutant concentration. This directly leads to increased operating costs and lower operational efficiency of supporting facilities. Therefore, there is an urgent need to improve the operational efficiency of PRBs in sites with significant spatial and temporal variations in groundwater pollutants through novel structural design and maintenance methods. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a permeable reaction system and its operation method for organic fluoride contaminated soil layers, so as to improve the operating efficiency of the permeable reaction barrier in organic fluoride contaminated layered soil layers and reduce costs.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] On one hand, the present invention provides a permeable reaction system for soil contaminated with organofluorine compounds, comprising a permeable reaction barrier, an upstream monitoring well, and a downstream monitoring well; the permeable reaction barrier includes several permeable reaction modules, each comprising a hollow shell, with permeable mesh on two oppositely perforated sides of the shell; the shell contains granular filler, the granular filler having an internal ultraviolet light band; the granular filler includes translucent glass spheres and ceramic particles with titanium dioxide loaded on their surface; the upstream monitoring well is located upstream of the permeable reaction barrier, and the downstream monitoring well is located downstream of the permeable reaction barrier; both the upstream and downstream monitoring wells are equipped with detection components.

[0007] As a further improvement of the present invention, in each of the permeable reaction modules, the embedding length of the ultraviolet light band is determined according to equations (1) and (2):

[0008] Equation (1)

[0009] Equation (2)

[0010] In the formula, This indicates the embedment length of the ultraviolet band, in cm. This indicates the length of the permeability reaction barrier module, in cm. This indicates the width of the permeability reaction barrier module, in cm. This indicates the height of the permeability barrier module, in cm. This represents the radial effective irradiation area of ​​a UV band, expressed in cm². 2 ; The reduction factor representing the radial effective irradiation area of ​​the ultraviolet band is dimensionless. This represents the bulk volume of a transparent glass sphere, expressed in cm³. 3 ; This represents the bulk volume of expanded clay aggregate, expressed in cm³. 3 ; The volume ratio of transparent glass spheres to ceramsite is a reference value, dimensionless; The value range is 0.8 to 2.3.

[0011] As a further improvement of the present invention, the permeability reaction barrier includes N The permeable reaction units are arranged sequentially along the direction of groundwater flow. Each permeable reaction unit includes... K The system consists of vertically arranged permeable reaction layers, each layer comprising several permeable reaction modules arranged sequentially along the direction of the permeable reaction barrier on a vertical plane. Within the same permeable reaction unit, the ultraviolet light bands of all permeable reaction modules in the same permeable reaction layer are connected in series.K The ultraviolet bands of the permeable reactive layers are connected in parallel; N The ultraviolet bands of the sheet-penetrating reaction units are connected in parallel; N It is an integer greater than or equal to 3.

[0012] As a further improvement of the present invention, each detection component includes K A series of monitoring devices are spaced out along the height direction of the monitoring well. K Each monitoring component is used for data collection. K Monitoring parameters of groundwater in each soil layer; K This refers to the number of soil layers in the contaminated site that the groundwater level passes through to the maximum burial depth of the groundwater.

[0013] As a further improvement of the present invention, the splicing gaps between the permeable reaction modules of two adjacent permeable reaction units are arranged in an alternating manner.

[0014] As a further improvement of the present invention, the upstream monitoring well has M indivual, M The upstream monitoring wells are spaced apart along the direction of the permeability reaction barrier; the downstream monitoring wells have M indivual, M The downstream monitoring wells are arranged at intervals along the direction of the permeability reaction barrier; M One upstream monitoring well and M Each downstream monitoring well is deployed in a corresponding manner; M It is an integer greater than or equal to 3.

[0015] As a further improvement of the present invention, the distance between two adjacent upstream monitoring wells is 10~30m.

[0016] On the other hand, the present invention also provides an operation method for the above-mentioned permeable reaction system for organic fluoride contaminated soil layers, wherein during operation, the opening and closing of the ultraviolet light band in the permeable reaction barrier is adjusted according to the monitoring parameter data of the upstream and downstream groundwater collected.

[0017] As a further improvement of the present invention, all ultraviolet light bands in the two permeable reaction units located at the upstream and downstream ends are always in the open state; the opening and closing states of ultraviolet light bands in other permeable reaction units are adjusted according to the collected monitoring parameter data of upstream and downstream groundwater.

[0018] As a further improvement of the present invention, the opening and closing state of the ultraviolet light band in the permeable reaction unit is controlled by formulas (3) to (6):

[0019] Equation (3)

[0020] Equation (4)

[0021] Equation (5)

[0022] Equation (6)

[0023] In the formula, Indicates the first n The first of the sheet permeable reaction units The state of all ultraviolet bands in the permeable reaction layer, 0 indicates the off state and 1 indicates the on state; Indicates the first The maximum ratio of monitoring parameters of groundwater upstream and downstream of the soil layer, dimensionless; Indicates the first j The first upstream monitoring well k The first monitoring device collected upstream groundwater samples. Each monitoring parameter value; Indicates the first j The first downstream monitoring well k The first monitoring device collected downstream groundwater samples. Each monitoring parameter value; It can take the value 1 or 2; This represents the response threshold, which is dimensionless. This represents the monitoring well distance adjustment coefficient, which is dimensionless and ranges from 0.1 to 0.3. This indicates the distance between two adjacent monitoring wells located on the same side of the permeability reaction barrier, in meters (m).

[0024] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0025] (1) The present invention provides a permeable reaction system for organic fluoride contaminated soil and its operation method. It employs prefabricated permeable reaction modules to form a permeable reaction barrier. The permeable reaction module contains surface-loaded titanium dioxide ceramic particles that adsorb pollutants and degrade them through photocatalysis. An ultraviolet light band is provided to introduce an external light source. When the ultraviolet light band is closed, polluted groundwater flows through the permeable reaction module, and the organic fluorides are adsorbed and fixed within the permeable reaction module through the adsorption of the filler material. When the ultraviolet light band is open, polluted groundwater flows through the permeable reaction module... In the permeable reaction module, on the one hand, the organic fluoride is adsorbed and fixed in the permeable reaction module through the adsorption of the packing material; on the other hand, the organic fluoride released by the desorption of the packing material is catalytically degraded through photocatalysis. After degradation, the organic fluoride adsorbed in the packing material diffuses back into the groundwater. When the concentration of organic fluoride in the groundwater changes frequently, the opening and closing state of the ultraviolet light band in the permeable reaction barrier can be adjusted according to the monitoring parameters of the upstream and downstream groundwater, thereby improving the permeability reaction effect, reducing the frequency of packing material replacement, improving the operating efficiency of the permeable reaction barrier, and reducing operating costs.

[0026] (2) The present invention provides a permeable reaction system and its operation method for organic fluoride contaminated soil layers. By setting the burial length of the ultraviolet light strip, it can provide quantitative data support for optimizing the service performance of the permeable reaction barrier. For example, when the granular filler changes, the length of the ultraviolet light strip should also be adjusted accordingly. This can maximize the catalytic effect of the ultraviolet lamp and reduce energy input.

[0027] (3) The present invention provides a permeable reaction system for soil contaminated with organic fluoride and its operation method. The permeable reaction barrier is designed in sections and layers. On the one hand, it improves the mobility of on-site construction and maintenance of the permeable reaction barrier. On the other hand, it can adjust the opening and closing state of the ultraviolet light band of each layer in each section according to the changes in the concentration of organic fluoride in the upstream and downstream groundwater in different soil layers, thereby further improving the remediation efficiency of contaminated groundwater and reducing the economic cost of remediation projects. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a permeable reaction system for organic fluoride contaminated soil provided in an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of the permeability reaction module in an embodiment of the present invention;

[0030] Figure 3 This is a comparison chart of the changes in perfluorooctanoic acid concentration in Example 1, Comparative Example 1, and Comparative Example 2.

[0031] In the diagram: 1. Permeable reaction barrier; 101. Shell; 102. Permeable mesh; 103. Ultraviolet light strip; 104. Transparent glass sphere; 105. Ceramsite; 2. Upstream monitoring well; 3. Downstream monitoring well; 231. Monitoring component; 232. Enclosed base; 4. Cohesive soil layer; 5. Monitor; 6. Pollution source; 71. Ground surface; 72. Second soil layer; 73. Third soil layer; 74. Fourth soil layer; 8. Groundwater level. Detailed Implementation

[0032] The technical solution of the present invention will be described in detail below.

[0033] This invention provides a permeable reaction system for soil contaminated with organofluorine compounds, located downstream of the contamination source 3. For example... Figure 1 As shown, the permeability reaction system includes a permeability reaction barrier 1, an upstream monitoring well 2, and a downstream monitoring well 3. The upstream monitoring well 2 is located upstream of the permeability reaction barrier 1, and the downstream monitoring well 3 is located downstream of the permeability reaction barrier 1. Both the upstream and downstream monitoring wells 2 and 3 have a sealed base 232 at their bottom, and their walls have through-holes for groundwater to pass through. Both the upstream and downstream monitoring wells 2 and 3 are equipped with monitoring components used to collect monitoring parameters of the upstream and downstream groundwater.

[0034] Preferably, the monitoring parameters include at least one of pH, conductivity, and redox potential. Organofluoride compounds inhibit the characteristics and quantity of microbial communities in groundwater, and changes in the characteristics and quantity of microbial communities can cause changes in pH, conductivity, and redox potential. Therefore, monitoring parameters such as pH, conductivity, and redox potential can characterize the concentration of organofluoride compounds in groundwater.

[0035] The permeability reaction barrier 1 includes several permeability reaction modules, such as... Figure 2 As shown, the permeable reaction module includes a hollow shell 101, with permeable mesh 102 on each of the two oppositely hollowed-out sides of the shell 101. The shell 101 contains granular filler, with an ultraviolet light strip 103 installed inside the granular filler. The granular filler includes translucent glass spheres 104 and ceramic particles 105 with titanium dioxide loaded on their surface.

[0036] The top of the permeable reactive barrier 1 is successively covered with a geomembrane and a cohesive soil layer 4. The geomembrane can prevent the fine particles of the overburden from entering the monitoring well and clogging the permeable reactive barrier, while the compacted cohesive soil layer can prevent rainwater infiltration and damage to the stability of the permeable reactive barrier and the trench sidewall.

[0037] During the operation of the permeable reaction system in the above embodiment, the opening and closing of the ultraviolet light band in the permeable reaction barrier 1 is controlled according to the collected monitoring parameter data of upstream and downstream groundwater. When polluted groundwater passes through the permeable reaction module of the permeable reaction barrier 1, it passes through the permeable mesh 102 on one side and flows into the inner cavity of the shell 101. It flows through the granular packing and flows out from the permeable mesh 102 on the other side. During this process, the granular packing adsorbs the organic fluorides in the polluted groundwater, thereby purifying the groundwater. When the ultraviolet light band 103 is turned on, the granular packing includes transparent glass spheres 104 and ceramic particles 105 with titanium dioxide loaded on their surface. After the ultraviolet light band 103 emits ultraviolet light, the ultraviolet light irradiates the surface of the titanium dioxide loaded on the ceramic particles 105, generating electron-hole pairs, which react with the water molecules in contact to generate hydroxyl radicals. These hydroxyl radicals gradually degrade the organic fluorides into small molecule intermediates through oxidation, and finally mineralize them into CO2, H2O and fluorides. Because the ceramsite 105 is an opaque material, the propagation distance of ultraviolet light within the permeable reaction barrier is very short, with a maximum effective distance approximately five times the diameter of the granular filler. Therefore, in this embodiment of the invention, by adding transparent glass spheres 104 to the filler, ultraviolet light can pass through the transparent glass spheres 104 and be refracted on their surface, thereby greatly increasing the irradiation area of ​​the ultraviolet light and the ceramsite 105. For example, after mixing ceramsite 105 and transparent glass spheres 104 at a volume ratio of 1:1, the axial irradiation area of ​​a single ultraviolet light band 103 can be increased by approximately seven times, significantly improving the catalytic efficiency of the light source.

[0038] This invention, through the addition of a packing material to a permeable reaction module that adsorbs and photocatalytically degrades pollutants, introduces an external light source. When the ultraviolet light band 103 is closed, as contaminated groundwater flows through the permeable reaction module, organic fluorides are adsorbed and fixed within the module by the packing material. When the ultraviolet light band 103 is open, as contaminated groundwater flows through the module, organic fluorides are adsorbed and fixed within the module, and simultaneously, photocatalytic degradation of the organic fluorides released from the desorption of the packing material occurs. The degraded organic fluorides adsorbed on the packing material diffuse back into the groundwater, reducing the frequency of packing material replacement. In particular, when used in sites where groundwater organic fluoride levels fluctuate frequently, the permeable reaction system of this embodiment improves the operational efficiency of the permeable reaction barrier.

[0039] The permeable reactive barrier in this invention serves two purposes: first, it adsorbs organic fluorides from groundwater; second, it degrades and removes organic fluorides that were previously adsorbed on the packing material and might be released back into the groundwater through ultraviolet light catalysis. In other words, to prevent released organic fluorides from migrating downstream again, this invention proposes a permeable reactive barrier with photocatalytic regulation function. After the organic fluorides are desorbed from the packing material, they are catalytically degraded, preventing them from returning to the water flow. Thus, the packing material in the permeable reactive barrier unit can not only adsorb organic fluorides polluting groundwater but also degrade them and prevent their release back into the groundwater.

[0040] In this embodiment of the invention, the concentration of organofluorine compounds in groundwater is 3 to 6 orders of magnitude lower than that of traditional heavy metal pollutants, halogenated hydrocarbons, and petroleum hydrocarbons. To improve the monitoring accuracy of organofluorine compound concentration, upstream monitoring well 2 and downstream monitoring well 3 are constructed adjacent to the permeability reaction barrier 1.

[0041] Preferably, in each permeable reaction module, the embedding length of the ultraviolet light band 103 is determined according to equations (1) and (2):

[0042] Equation (1)

[0043] Equation (2)

[0044] In the formula, This indicates the embedment length of the ultraviolet band 103, in cm; This indicates the length of the permeability reaction barrier module, in cm. Indicates the width of the permeability reaction barrier module, in cm; This indicates the height of the permeability reaction barrier module, in cm. This represents the radial effective irradiation area of ​​a 103-ultraviolet band, expressed in cm². 2 ; The reduction factor representing the radial effective irradiation area of ​​the ultraviolet band 103 is dimensionless. This represents the bulk volume of a 104-cell transparent glass sphere, expressed in cm³. 3 ; This represents the bulk volume of 105 ceramsite particles, in cm³. 3 ; The reference value representing the bulk volume ratio of transparent glass sphere 104 and ceramsite 105 is dimensionless. The value range is 0.8 to 2.3.

[0045] In the above preferred embodiment, by setting the embedding length of the ultraviolet light strip 103, quantitative data support can be provided for optimizing the service performance of the permeable reaction barrier. For example, when the particulate filler changes, the length of the ultraviolet light strip must also be adjusted accordingly. This can maximize the catalytic effect of the ultraviolet lamp and reduce energy input.

[0046] Preferably, the permeability reaction barrier 1 includes N The permeable reaction units are arranged sequentially along the direction of groundwater flow. Each permeable reaction unit includes... K The permeable reaction layers are sequentially assembled vertically, and each permeable reaction layer includes several permeable reaction modules sequentially assembled along the direction of the permeable reaction barrier on a vertical plane. N It is an integer greater than or equal to 3. K This refers to the number of soil layers in the contaminated site that the groundwater level passes through to the maximum burial depth of the groundwater. K Each layer of permeable reactive layer is set up to correspond one-to-one with the soil layer of the contaminated site through which the groundwater reaches its maximum depth to the groundwater level.

[0047] Preferably, the joints between the permeable reaction modules of two adjacent permeable reaction units are staggered. This effectively prevents contaminated groundwater from flowing through the joints without passing through the permeable reaction modules.

[0048] In the preferred embodiment described above, several permeable reaction modules are spliced ​​together along the direction of the permeable reaction barrier and along the vertical surface to form a permeable reaction layer. The permeable reaction layer is then... K Layers of permeable reactive layers are sequentially assembled to form permeable reactive units, which are then applied along the direction of groundwater flow. N The permeable reaction units are connected to form a permeable reaction barrier. The permeable reaction barrier is designed in sections, layers, and modules. On the one hand, it improves the mobility of on-site construction and maintenance of the permeable reaction barrier. On the other hand, it can adjust the opening and closing state of the ultraviolet light band according to the changes in the concentration of organic fluoride in the groundwater, based on sections, layers, or modules, thereby improving the efficiency of contaminated groundwater remediation and reducing the economic cost of remediation projects.

[0049] Preferably, in the same permeable reactive reaction unit, the ultraviolet light bands of all permeable reactive modules in the same permeable reactive layer are connected in series. K The ultraviolet bands of the permeable reactive layers are connected in parallel. N The ultraviolet bands of the permeable reaction units are connected in parallel. That is, the opening or closing of the ultraviolet bands of all permeable reaction modules in the same permeable reaction layer of the permeable reaction unit is consistent; while the opening or closing of the ultraviolet bands in different permeable reaction layers is controlled separately, and the states may be different; the opening or closing of the ultraviolet bands in different permeable reaction units is also controlled separately, and the states may be different.

[0050] Preferably, each monitoring component includes K A number of monitoring elements 231 are arranged at intervals along the height of the monitoring well, and each monitoring element 231 is located in a different soil layer. K Each monitoring component is used for data collection. K Monitoring parameters of groundwater in each soil layer. For example, if the contaminated site has four soil layers, from top to bottom: the first soil layer (top surface 71), the second soil layer (72), the third soil layer (73), and the fourth soil layer (74), with the groundwater level 8 located in the first soil layer and the maximum groundwater depth located in the third soil layer, then... K The number is 3. The monitoring component includes three monitoring elements 231 arranged at intervals along the height direction of the monitoring well. The three monitoring elements 231 are used to collect monitoring parameters of groundwater in the first soil layer, the second soil layer, and the third soil layer, respectively.

[0051] In this preferred embodiment, the opening and closing of the ultraviolet (UV) light band is controlled on a layer-by-layer basis. Firstly, layer-by-layer control allows for precise control of the UV light band's embedment length within the filler, facilitating construction quality control. Secondly, setting and installing permeable reaction barriers along the groundwater flow direction on a sheet-by-sheet basis enables tiered control of UV photocatalysis, i.e., quantitatively controlling the number of UV lights activated based on the concentration differences of upstream and downstream pollutants. Furthermore, setting and installing permeable reaction units along the soil layer distribution direction on a layer-by-layer basis within a single sheet enables hierarchical control of UV photocatalysis, i.e., quantitatively controlling the number of UV lights activated based on the concentration differences of upstream and downstream pollutants in the corresponding soil layer. In addition, during the operation of the permeable reaction barrier, changes in ground pressure, groundwater level, and other factors can cause filler blockage and damage. The segmented, layered, and modular design and installation allows for the partial replacement of damaged permeable reaction modules, avoiding damage to the UV light band caused by the excavation of the entire permeable reaction barrier.

[0052] Preferably, upstream monitoring well 2 has M indivual, M The upstream monitoring wells are spaced apart along the direction of the permeability reaction barrier. The downstream monitoring wells have 3... M indivual, M The downstream monitoring wells are spaced apart along the direction of the permeability reaction barrier. M One upstream monitoring well and M Each downstream monitoring well is deployed in a corresponding manner. M It is an integer greater than or equal to 3. Preferably, the distance between two adjacent upstream monitoring wells is 10~30m.

[0053] The concentration of organic fluoride in groundwater will change to some extent along the direction of the permeability reaction barrier. In order to ensure monitoring accuracy and operational effectiveness, it is necessary to monitor through multiple monitoring wells, and an appropriate spacing should be set between adjacent monitoring wells.

[0054] This invention also provides an operating method for a permeable reaction system for soil contaminated with organic fluorides. During operation, the opening and closing of the ultraviolet light band in the permeable reaction barrier 1 is adjusted according to the monitoring parameter data of the upstream and downstream groundwater.

[0055] Preferably, all ultraviolet light bands in the two upstream and downstream permeable reaction units are always in the open state; the opening and closing states of ultraviolet light bands in other permeable reaction units are adjusted according to the collected monitoring parameter data of upstream and downstream groundwater.

[0056] Groundwater flow is typically slow, and organofluorine compounds (OFCs) in the groundwater migrate within the pores of permeable reactive barriers via convection and diffusion. Convective migration of OFCs follows the direction of groundwater flow, while diffusion migration is random, meaning it can occur in the same, perpendicular, or opposite direction to the groundwater flow. When the concentration of OFCs in the groundwater entering the permeable reactive barrier decreases, the OFCs adsorbed on the packing material desorb and are released back into the groundwater, thus releasing the adsorbed OFCs into the downstream groundwater environment. Therefore, to degrade OFCs that have migrated upstream via diffusion, the ultraviolet (UV) light band of the upstream permeable reactive barrier unit is always kept on. Furthermore, short-term concentrated rainfall can cause short-term changes in the groundwater flow field, even resulting in flow opposite to the main flow direction. Therefore, to reduce the risk of reverse groundwater flow caused by rainfall leading to the released OFCs migrating upstream again, the UV light band of the upstream permeable reactive barrier unit is always kept on. The reason for keeping the ultraviolet light band of the downstream permeable reaction unit always on is to prevent the desorbed organic fluorides on the packing material from being released back into the downstream groundwater environment when the groundwater is not flowing.

[0057] Preferably, the opening and closing state of the ultraviolet light band in the permeable reaction unit is controlled using equations (3) to (6):

[0058] Equation (3)

[0059] Equation (4)

[0060] Equation (5)

[0061] Equation (6)

[0062] In the formula, Indicates the first n The first of the sheet permeable reaction units The state of all ultraviolet bands in the permeable reaction layer, 0 indicates the off state and 1 indicates the on state; Indicates the first The maximum ratio of monitoring parameters of groundwater upstream and downstream of the soil layer, dimensionless; Indicates the first j The first upstream monitoring well k The first monitoring device collected upstream groundwater samples. Each monitoring parameter value; Indicates the first j The first downstream monitoring well k The first monitoring device collected downstream groundwater samples. Each monitoring parameter value; This represents the response threshold, which is dimensionless. This represents the monitoring well distance adjustment coefficient, which is dimensionless and ranges from 0.1 to 0.3. This indicates the distance between two adjacent monitoring wells located on the same side of the permeability reaction barrier, in meters (m). It can take the value 1 or 2. If If the value is 1, the first monitoring parameter can be pH, conductivity, or redox potential; if If the value is 2, then the first monitoring parameter is pH and the second monitoring parameter is conductivity; or, the first monitoring parameter is redox potential and the second monitoring parameter is conductivity.

[0063] This invention adjusts the opening and closing of the ultraviolet (UV) light bands in the corresponding permeable reaction layers of the 2nd to N-1th permeable reaction units based on monitoring parameters of upstream and downstream groundwater in different soil layers. When the concentration of organic fluoride (Ofluoride) in the upstream groundwater increases, the adsorption effect of the packing material in the permeable reaction barrier decreases. Opening an appropriate number of UV light bands allows the catalytic effect of the UV light to compensate for the insufficient physical adsorption of the packing material. When the concentration of Ofluoride in the upstream groundwater decreases again, the Ofluoride adsorbed by the packing material in the permeable reaction barrier is released back into the groundwater. At this time, opening an appropriate number of UV light bands degrades the adsorbed Ofluoride through the catalytic effect of the UV light, thus overcoming the limitation of traditional permeable reaction barriers in completely removing Ofluoride. This invention adjusts the number of UV light bands opened based on the concentration of upstream pollutants, improving the performance of the permeable reaction barrier, saving energy, and reducing costs. Because the groundwater moisture content and pollutant concentration vary greatly in layered soil layers, and the permeability coefficient of the strata can differ by 2 to 3 orders of magnitude, the embodiments of the present invention control the opening and closing of the ultraviolet light band on a layer-by-layer basis according to the distribution of soil layers. This can fully realize the optimal catalytic efficiency of the ultraviolet light band in each soil layer and achieve energy optimization.

[0064] An embodiment and two comparative examples are provided to verify the performance of the method of the embodiment of the present invention. The embodiment and comparative examples are all simulation experiments conducted in the laboratory. Example

[0065] In the experiment, the concentration of perfluorooctanoic acid (PFOA) in the upstream contaminated groundwater was set at 100 μg / L, and the solid-liquid ratio of the expanded clay aggregate (ECA) to the contaminated groundwater was 1:10. The particle size of the ECA ranged from 1 to 2.5 cm. The volume of the transparent glass spheres was the same as that of the ECA, with a diameter of 1.5 cm. Titanium dioxide powder was uniformly loaded onto the surface of the ECA, and the mass ratio of titanium dioxide to ECA was 1:100. After the ECA and transparent glass spheres were mixed evenly, the mixture was poured into a polyethylene bottle and placed in an opaque shaker. During the experiment, three ultraviolet (UV) light strips were evenly installed inside the polyethylene bottle and turned on to ensure that the UV light could fully irradiate the surface of the ECA. Each UV light strip was 10 cm long and had a power of 0.1 W.

[0066] Solution samples were collected at 3-hour intervals, and the perfluorooctanoic acid (PFOA) concentration was tested. After 12 hours of adsorption, PFOA reached adsorption saturation on the ceramic particle surface. Then, the simulated groundwater, after partial removal of contaminants from the polyethylene bottle, was removed and replaced with simulated contaminated groundwater containing 30 μg / L PFOA, and placed on a shaker. Solution samples were collected at 3-hour intervals, and the PFOA concentration was tested. This experiment simulated the removal effect of PFOA from groundwater under the condition that the ultraviolet light bands of the upstream, second, and downstream permeable reaction units along the groundwater flow direction were open, using a permeable reaction barrier with four permeable reaction units. The simulated downstream groundwater PFOA concentration changes are shown in [Figure showing the PFOA concentration changes]. Figure 3 .

[0067] Comparative Example 1

[0068] The expanded clay particles in Example 1 were replaced with expanded clay particles without titanium dioxide powder loading (i.e., the expanded clay particles used in the conventional method), and no ultraviolet light strip was installed inside the polyethylene bottle during the experiment. The pollutant concentration, sampling time, and pollutant testing methods in all other steps of the experiment were the same as in Comparative Example 1. This experiment simulated the removal effect of a conventional perfluorooctanoic acid (PFOA) from contaminated groundwater under the same conditions as the thickness of the permeable reaction barrier with four permeable reaction units as in Example 1 (without an ultraviolet light strip). The simulated changes in downstream groundwater PFOA concentration are shown in [Figure 1]. Figure 3 .

[0069] Comparative Example 2

[0070] During the experiment, four ultraviolet (UV) light strips were uniformly installed inside a polyethylene bottle and all were turned on. The contaminant concentration, sampling time, and contaminant testing methods were identical to those in Comparative Example 1 for all other steps of the experiment. This experiment simulated the removal effect of perfluorooctanoic acid (PFOA) from groundwater under the condition that the UV light strips of all four permeable reaction units were turned on, using a permeable reaction barrier with four permeable reaction units. The simulated changes in downstream groundwater PFOA concentration are shown in [Figure showing the effect]. Figure 3 .

[0071] from Figure 3 The changes in perfluorooctanoic acid (PFOA) concentration in Comparative Example 1 and Example 1 show that, in Example 1, by turning on three ultraviolet light bands (corresponding to the ultraviolet light bands of three units within the four permeable reaction units being in the on state), the PFOA concentration in the groundwater can be changed from high to low, and the PFOA adsorbed on the packing material will no longer migrate to the downstream groundwater, resulting in a significant removal effect.

[0072] from Figure 3 The changes in pollutants observed in Comparative Example 2 and Example 1 show that when the concentration of perfluorooctanoic acid (PFOA) in the upstream groundwater is constant, the optimal number of UV lamps activated within the permeable reaction unit is found. As the number of activated lamps increases further, the PFOA concentration in the groundwater no longer changes significantly. Therefore, this embodiment of the invention optimizes the number of UV lamps activated within the permeable reaction unit based on the difference in PFOA concentration between upstream and downstream groundwater, achieving both excellent removal efficiency and reduced energy consumption.

[0073] The foregoing 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 to the specific embodiments described above. The specific embodiments and descriptions in the specification are merely for further illustrating the principles of the present invention. Various changes and modifications can be made to the present invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed.

Claims

1. A permeable reaction system for organic fluoride contaminated soil layers, characterized in that, The system includes a permeable reaction barrier (1), an upstream monitoring well, and a downstream monitoring well. The permeable reaction barrier (1) includes several permeable reaction modules, each including a hollow shell (101). The shell (101) has permeable mesh (102) on its two relatively open sides. The shell (101) is filled with granular filler, and the granular filler has an ultraviolet light strip (103) inside. The granular filler includes a transparent glass ball (104) and ceramic particles (105) with titanium dioxide loaded on their surface. The upstream monitoring well is located upstream of the permeable reaction barrier (1), and the downstream monitoring well is located downstream of the permeable reaction barrier (1). Both the upstream and downstream monitoring wells are equipped with detection components. In each of the aforementioned permeable reaction modules, the embedding length of the ultraviolet light band (103) is determined according to equations (1) and (2): Equation (1) Equation (2) In the formula, The buried length of the ultraviolet band (103) is indicated in cm; This indicates the length of the permeability reaction barrier module, in cm. Indicates the width of the permeability reaction barrier module, in cm; This indicates the height of the permeability reaction barrier module, in cm. This represents the radial effective irradiation area of ​​a UV band (103), expressed in cm². 2 ; The reduction factor representing the radial effective irradiation area of ​​the ultraviolet band (103) is dimensionless; This represents the bulk volume of the transparent glass sphere (104), in cm³. 3 ; This represents the bulk volume of expanded clay aggregate (105), in cm³. 3 ; The reference value representing the bulk volume ratio of transparent glass spheres (104) and ceramsite (105) is dimensionless; The value range is 0.8 to 2.3; The permeability reaction barrier (1) includes N The permeable reaction units are arranged sequentially along the direction of groundwater flow. Each permeable reaction unit includes... K The system consists of vertically arranged permeable reaction layers, each layer comprising several permeable reaction modules arranged sequentially along the direction of the permeable reaction barrier on a vertical plane. Within the same permeable reaction unit, the ultraviolet light bands of all permeable reaction modules in the same permeable reaction layer are connected in series. K The ultraviolet bands of the permeable reactive layers are connected in parallel; N The ultraviolet bands of the sheet-penetrating reaction units are connected in parallel; N It is an integer greater than or equal to 3; the splicing gaps between the permeable reaction modules of two adjacent permeable reaction units are staggered; Each detection component includes K 231 monitoring units are arranged at intervals along the height direction of the monitoring well. K Each monitoring component is used for data collection. K Monitoring parameters of groundwater in each soil layer; K This refers to the number of soil layers in the contaminated site that the groundwater level passes through to the maximum burial depth of the groundwater.

2. The permeable reaction system for organic fluoride contaminated soil layers according to claim 1, characterized in that, The upstream monitoring well (2) has M indivual, M The upstream monitoring wells are spaced along the direction of the permeability reaction barrier; the downstream monitoring wells (3) have M indivual, M The downstream monitoring wells are arranged at intervals along the direction of the permeability reaction barrier; M One upstream monitoring well and M Each downstream monitoring well is deployed in a corresponding manner; M It is an integer greater than or equal to 3.

3. The permeable reaction system for organic fluoride contaminated soil layers according to claim 2, characterized in that, The distance between two adjacent upstream monitoring wells is 10~30m.

4. A method for operating a permeable reaction system for organic fluoride contaminated soil as described in any one of claims 1 to 3, characterized in that, During operation, the opening and closing of the ultraviolet light band in the permeable reaction barrier (1) is adjusted according to the monitoring parameter data of the upstream and downstream groundwater collected.

5. The method for operating a permeable reaction system for organic fluoride contaminated soil as described in claim 4, characterized in that, In the two upstream and downstream permeable reaction units, all ultraviolet light bands are always on; based on the collected monitoring parameters of upstream and downstream groundwater, the opening and closing states of the ultraviolet light bands in other permeable reaction units are adjusted.

6. The method for operating a permeable reaction system for organic fluoride contaminated soil as described in claim 5, characterized in that, The opening and closing states of the ultraviolet light band in the permeable reaction unit are controlled by equations (3) to (6): Equation (3) Equation (4) Equation (5) Equation (6) In the formula, Indicates the first n The first of the sheet permeable reaction units The state of all ultraviolet bands in the permeable reaction layer, 0 indicates the off state and 1 indicates the on state; Indicates the first The maximum ratio of monitoring parameters of groundwater upstream and downstream of the soil layer, dimensionless; Indicates the first j The first upstream monitoring well k The first monitoring device collected upstream groundwater samples. Each monitoring parameter value; Indicates the first j The first downstream monitoring well k The first monitoring device collected downstream groundwater samples. Each monitoring parameter value; It can take the value 1 or 2; This represents the response threshold, which is dimensionless. This represents the monitoring well distance adjustment coefficient, which is dimensionless and ranges from 0.1 to 0.

3. This indicates the distance between two adjacent monitoring wells located on the same side of the permeability reaction barrier, in meters (m).

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