Adsorbent for removing perfluorinated compounds from groundwater and method for laying the same

Abstract

The present application relates to a kind of adsorbent for removing groundwater perfluorinated compounds and its layout method, according to the non-uniform characteristics of pollution plume concentration distribution, make global layout of adsorbent in the area to be repaired, different distribution characteristics presented based on pollutant concentration is different way discrete to repair wall, based on target hydraulic retention time determine the thickness constraint of reaction wall that meets the repair target, and under its constraint, the bivariate trade-off optimization and selection of anion exchange resin adsorbent layout in each section is carried out, based on the thickness and density determined, set adsorbent and its proportioning, improve adsorption efficiency by the advantage of different PFAS adsorption kinetics, while ensuring repair effect and adsorption performance, optimize material usage, reduce construction cost and avoid local penetration risk.Continuous section is adjusted by filling density, presents the same external characteristics while actually having different adsorption capacity, meet the needs of actual engineering simplification.

Description

[Technical Field] This invention belongs to the field of groundwater remediation, and particularly relates to an adsorbent for removing perfluorinated compounds from groundwater and its deployment method. [Background Technology] Currently, the mainstream technologies for PFAS adsorption in groundwater can be divided into three categories: cutting-edge porous materials represented by MOFs, engineered soil immobilizers represented by RemBind, and water treatment adsorbents represented by anion exchange resins. Metal-organic frameworks (MOFs) achieve anchoring through strong coordination between metal nodes and PFAS head groups, while enhancing affinity for fluorocarbon chains through fluorinated ligand modification or hydrophobic channel design. However, the water stability, large-scale synthesis cost, and regeneration process of MOFs remain the main bottlenecks restricting their in-situ PRB application, and they are currently mostly limited to the laboratory or pilot-scale stages. Engineered soil immobilizers have low immobilization efficiency for extremely low concentrations of short-chain PFAS, and excessive material dosage can affect permeability, requiring differentiated placement based on concentration gradients. Anion exchange resins achieve selective adsorption through electrostatic ion exchange between quaternary ammonium groups and PFAS anion head groups. They exhibit better kinetic rates for short-chain PFAS (C<4) than long-chain PFAS and can be regenerated and recycled through salt solutions, making them a relatively mature technology in current water treatment facilities. Permeable reactive barrier (PRB) technology is an in-situ remediation method for groundwater pollution that has been developed since the 1990s. It offers significant advantages such as requiring no land occupation, long-term continuous operation, and minimal environmental impact. A wall filled with reactive materials is installed along the path of contaminated groundwater. Pollutants are removed through adsorption, sedimentation, oxidation-reduction, or biodegradation. It has been widely used globally to treat various pollutants, including heavy metals, halogenated hydrocarbons, and aromatic hydrocarbons.

[0001] Traditional PRB design often assumes a uniform spatial distribution of pollutant concentrations within the same site, leading to the use of uniform thickness and homogeneous material for the wall filling. However, in reality, due to factors such as spatial differences in pollutant source locations, heterogeneity of aquifer media and hydrogeochemical conditions, and directional differences in groundwater flow velocities, pollutant concentrations in the plume exhibit significant three-dimensional spatial heterogeneity. The difference between high-concentration core areas and low-concentration edge areas is typically more than an order of magnitude. Under a homogenization design paradigm, because the plume concentration varies along the length of the wall, traditional uniform thickness and homogeneous filling designs easily lead to premature penetration in high-concentration areas and material idleness in low-concentration areas, making it difficult to balance economy and stability. Anion exchange resin synthesis costs are also high; while RemBind is a low-cost route, increasing the dosage still drives up the total material cost. The concentration of PFAS in the pollutant plume exhibits significant spatial variation along the length of the wall. Traditional homogeneous PRB cannot simultaneously match the design requirements of various locations from high to low concentrations in terms of thickness and material packing density, leading to severe material waste. Furthermore, the regeneration efficiency of anion exchange resins varies with chain length, and the immobilization rate of RemBind differs across concentration ranges. These differences in chemical behavior cannot be precisely matched, resulting in low local adsorption efficiency or misallocation of resources. Therefore, how to accurately deploy adsorbents based on their adsorption capacity and the differences in pollutant plume concentration distribution is a technical problem to be solved. This invention proposes a method that, based on the non-uniform characteristics of the pollutant plume concentration distribution, performs a multi-wall overall layout in the area to be remediated. Different discretization methods are used based on the different distribution characteristics of pollutant concentrations across the cross-section. Under the constraint of the target thickness of the reactive wall, a bivariate trade-off optimization and comparison is performed for the placement of adsorbents in each segment. Based on the determined thickness and density, the adsorbent and its ratio are set, leveraging the adsorption kinetics of different PFAS to improve adsorption efficiency. This ensures remediation effectiveness while optimizing material usage, reducing construction costs, and avoiding the risk of localized penetration. [Summary of the Invention] To address the aforementioned problems in the prior art, this invention proposes an adsorbent for removing perfluorinated compounds from groundwater and its deployment method, the method comprising: Step S1: Site investigation and plume characterization to determine the location of the reactive barrier; Step S2: Determine the feasible region function relationship of the reaction rate constant under different packing densities. Relationship between feasible region function and effective porosity ; Step S3: Determine the target thickness for each reactive barrier; Step S4: Discretize each reaction wall into Each section; Step S5: Under the constraint of the target thickness of the reactive wall, perform bivariate trade-off optimization and comparison of the segment layout; determine the feasible region of each segment i of the reactive wall j that satisfies the remediation objective. The feasible region includes a binary pair of section wall thickness and infill density. After optimizing and comparing all sections of reactive wall j, a binary pair is selected from the feasible region of each section to form a sequence of binary pairs that satisfy the target thickness or target thickness range constraint of reactive wall j. ; Step S6: Construct the reactive wall using the determined fill density and wall thickness.

[0002] Furthermore, step S1 specifically involves: obtaining the three-dimensional spatial distribution of hydrogeological parameters and / or pollutant concentrations of the contaminated site through drilling, monitoring well deployment, high-density passive flux meter monitoring, and / or groundwater sampling and analysis methods; establishing a three-dimensional spatial distribution map of pollutant concentrations in the pollutant plume; identifying the geometric morphology of the outer edge of the pollutant plume; determining the location of the reaction wall at the front end of the possible pollutant diffusion zone based on the migration and diffusion mode and range of the pollutants; and numbering the reaction walls.

[0003] Furthermore, step S3 specifically involves: determining the reaction rate constant based on the target hydraulic residence time, then determining the filling density based on the feasible domain function relationship of the reaction rate constant, and finally determining the target thickness of the reaction wall based on the filling density or the range of filling density.

[0004] Furthermore, step S4 specifically involves: for the same wall orientation, setting up no fewer than three parallel monitoring profiles to obtain the spatial distribution of pollutant concentration and groundwater flow velocity on the cross-section, and discretizing the wall orientation according to the horizontal / vertical direction. Each section.

[0005] Furthermore, based on the different distribution characteristics of pollutant concentrations across the cross section, different discretization methods are adopted; when the pollutant concentrations exhibit stratified characteristics across the cross section, horizontal discretization is performed; when the pollutant concentrations exhibit segmented characteristics across the cross section, vertical discretization is performed; considering the superimposed flow velocity, the segments with large flow velocity differences are further subdivided into different segments.

[0006] Furthermore, for section i of reactive wall j, use and The feasible region functional relationship is shown in equation (3) in the bivariate space. In the process, determine the feasible region for each segment i that satisfies the repair objective. :in: These are the minimum fill density and the critical fill density, respectively. These are the minimum thickness and the maximum thickness, respectively. It is the actual groundwater flow velocity at section i of the reaction wall j; It is the effective porosity at section i; where: ; (3).

[0007] Furthermore, the step of selecting a sequence of binary pairs that satisfy the target thickness constraint of reactive wall j from the feasible domain of each segment is specifically: calculating the average thickness of all segments of reactive wall j based on the thickness of each segment; if the average thickness is equal to or approximately equal to the target thickness of reactive wall j, then the constraint is determined to be satisfied; otherwise, it is determined to be unsatisfied.

[0008] An adsorbent for removing perfluorinated compounds from groundwater, wherein the adsorbent is used in the adsorbent deployment method for removing perfluorinated compounds from groundwater, and the adsorbent is anion exchange resin, colloidal activated carbon, modified bentonite, zero-valent iron, zeolite, or any combination thereof.

[0009] Furthermore, when selecting each tuple in the binary sequence, different adsorbent settings are adopted for different sections to determine the wall thickness and filling density, thus corresponding to different filling densities and wall thicknesses.

[0010] Furthermore, for each section, a trade-off can be made between packing density and wall thickness. When the packing density is in the second density range, a gel-type highly hydrophobic resin is used, with a ratio of [A600: colloidal activated carbon = 1:0.3~1:0.5]; the wall is thicker, and the packing density is moderate, ensuring sufficient contact of long-chain PFAS. When the packing density is in the first density range, a macroporous resin mixed with A600 is selected, with a ratio of [A860:A600:colloidal activated carbon = 1:1:0.4]; short-chain adsorption kinetics are faster. When the packing density is in the third density range, a new type of monodisperse or fluorinated modified resin is used, with a ratio of [resin:colloidal activated carbon = 1:0.8~1:1]; where the first density range is greater than the second density range, and the second density range is greater than the third density range.

[0011] The beneficial effects of this invention include: (1) Based on the non-uniformity of the concentration distribution of the pollution plume, the adsorbent is deployed globally in the area to be remediated. The remediation wall is discretized in different ways based on the different distribution characteristics of the pollutant concentration. The thickness constraint of the reaction wall that meets the remediation target is determined based on the target hydraulic residence time. Under this constraint, the half-life principle of pollutants is coupled with the adsorption kinetic model to carry out bivariate trade-off optimization and selection of the anion exchange resin adsorbent deployment in each section. This breaks through the industry standard of traditional uniform design and realizes the precise matching of the gradient distribution and efficiency of materials, rather than maximizing the adsorption capacity.

[0012] (2) Based on the determined thickness and density, the adsorbent and its ratio are set, and the adsorption efficiency is improved by taking advantage of the adsorption kinetics of different PFAS. While ensuring the repair effect and adsorption performance, the amount of material is optimized, the construction cost is reduced and the risk of local penetration is avoided. This avoids the oversaturation design of the low concentration area and the underestimation of the adsorption risk of the high concentration area in the traditional design. It significantly reduces the local oversaturation range and the frequency of material replacement, and reduces the overall operation and maintenance cost.

[0013] (3) By adjusting the filling density of continuous sections, different adsorption capacities are actually present despite having the same external characteristics. For sections with high pollutant concentration, medium density filling is used; for sections with medium pollutant concentration, high density filling is used; and for sections with low pollutant concentration, low density filling is used. Thus, the overall adsorption capacity of the reaction wall is maintained or improved through wall thickness compensation. [Attached Image Description] The accompanying drawings, which are provided to further illustrate the invention and form part of this application, are not intended to unduly limit the invention. In the drawings: Figure 1 This is a schematic diagram of the adsorbent deployment method for removing perfluorinated compounds from groundwater according to the present invention.

[0014] Figure 2 This is a schematic plan view of the continuous layout of the permeable reactive wall of the present invention. Figure 3 This is a schematic diagram of the horizontal discrete segmentation method of the permeable reactive wall of the present invention.

[0015] Figure 4 This is a schematic diagram of the vertically discrete segmentation method of the permeable reactive wall of the present invention.

[0016] Figure 5 This is a schematic diagram showing the segmented cubic Bézier curve setup for the water-facing surface in this invention.

[0017] Figure 6 The figures show the Langmuir isotherm adsorption fitting curves for different concentration ranges in the embodiments of the present invention.

Detailed Implementation Methods

[0018] This invention proposes an adsorbent for removing perfluorinated compounds from groundwater and its deployment method. A permeable reactive wall is installed downstream of the pollution plume according to a predetermined thickness. Pre-mixed adsorbent material is then filled into the reactive wall at a predetermined filling density. Alternatively, impermeable funnel walls can be constructed on both sides of the pollution plume to collect the dispersed polluted groundwater into the permeable reactive wall. When deploying the reactive wall, the shape of the reactive wall at each location and its filling method must be determined. For details, see attached. Figure 1 As shown, the deployment method for removing perfluorinated compounds from groundwater includes the following steps; in these steps, it is necessary to determine the thickness of the reaction wall and the density of the adsorbent packing. Step S1: Site investigation and plume characterization to determine the location of the reactive barrier; specifically: through drilling, well deployment, high-density passive flux meter monitoring, and / or groundwater sampling and analysis, obtain the three-dimensional spatial distribution of hydrogeological parameters and / or pollutant concentrations of the contaminated site, establish a three-dimensional spatial distribution map of pollutant concentrations in the plume, identify the geometric morphology of the plume's outer edge, and determine the location of the reactive barrier at the front end of the potential pollutant diffusion zone based on the migration and diffusion mode and range of the pollutants, and number the reactive barriers; further, determine the pollutant concentration value C(j) at the cut-off section perpendicular to the groundwater flow direction at the reactive barrier location, where: j is the reactive barrier number or the cut-off section location number; the larger the j value, the farther away from the pollution source direction, and the smaller the j value, the closer to the pollution source direction; the pollutant concentration value at the cut-off section location is the representative value of the pollutant concentration at that section; Preferred: When setting up the reactive barrier, in addition to considering the morphology of the pollution plume, it is also necessary to consider the ease and feasibility of construction; in addition, the concentration of pollutants in the cross-sectional plane where the corresponding cross-section of the reactive barrier is located may vary greatly, so multiple locations can be monitored and a representative concentration value can be obtained as the concentration value at the corresponding cross-section j of the reactive barrier. For large-area pollution plumes, several reactive barriers need to be installed based on the plume's diffusion and the size of the adsorption area. These permeable reactive barriers are positioned on the plume's cross-section perpendicular to the groundwater flow direction. Reactive barriers closer to the pollution source are located in high-concentration areas, while those farther away are located in low-concentration areas. For example, the primary goal of high-concentration reactive barriers is to rapidly reduce the load and ensure the effluent meets acceptable standards; low-concentration reactive barriers aim for deep purification, reducing the concentration to even lower levels. (See attached diagram) Figure 2 As shown, this illustrates the differential distribution of wall thickness and filling density along the direction of groundwater flow, while also displaying the changing trends of pollutant concentrations upstream and downstream of the wall. Step S2: Determine the feasible region function relationship of the reaction rate constant under different packing densities. Relationship between feasible region function and effective porosity Specifically, this involves conducting indoor column tests and calibrating reaction kinetic parameters and material property functions at different fill densities. Based on this, a basic column test was conducted. The adsorbent was mixed evenly with the site's water-containing medium at a preset mass ratio and filled into the experimental column to simulate the on-site wall filling structure. A breakthrough test was carried out under constant flow rate and influent concentration conditions, and the pollutant concentration at the inlet was recorded. Pollutant concentration at the outlet at different times t Furthermore, the concentration decay curve was fitted using a first-order reaction kinetic model, and for each filling density level, the corresponding filling density was obtained by fitting the first-order kinetic model. The reaction rate constant at the following values At the same time, the effective porosity at this density was measured. ; Preferably, the adsorbent is selected from anion exchange resin, colloidal activated carbon, modified bentonite, zero-valent iron, zeolite, or any combination thereof; further, the main adsorbent is selected from anion exchange resin, and the framework auxiliary material is selected from colloidal activated carbon; the batch test includes testing the adsorption kinetic parameters of PFAS with different chain lengths, including perfluorooctanoic acid (PFOA), perfluorooctanoic acid (PFOS), perfluorobutyric acid (PFBA), perfluorobutyric acid (PFBS), and their substitutes GenX. Preferred: with a standard filler density of 0.35 g / cm³ 3 Based on the feasible region Different filling densities within the range An attempt; for example: taking at least 5 density levels, Decomposition yielded concentrations of 0.20, 0.35, 0.50, 0.65, and 0.80 g / cm³. 3 A series of column tests are required here, through continuous fixing Flow rate Change the fill density Determine different filling densities The apparent reaction rate constant is obtained by fitting the first-order kinetic model to obtain the corresponding reaction rate constant. The feasible domain function relationship and the effective porosity at this filling density When anion exchange resin is used as the main adsorbent, this relationship... It exhibits characteristics of three stages; Similarly, relationships It also exhibits three stages; Preferably, the step further includes: determining the equilibrium adsorption capacity of the adsorbent for the target pollutant through an isothermal adsorption test. The maximum adsorption capacity was obtained by fitting the model using Langmujr or Freundljch. ; Step S3: Determine the target thickness of the reaction wall at section position j; specifically: determine the reaction rate constant based on the target hydraulic residence time, and then determine the reaction rate constant based on the feasible domain function relationship. Determine the packing density or packing density range, and based on the packing density or packing density range, determine the target thickness or target thickness range of the reactive wall; it is important to note here that the feasible region function relationship of the reaction rate constant... When it is a non-linear function, the obtained value may be a continuous value, such as the range of fill density; it is advisable to preferentially select a value within this range of fill density. Smaller or less difficult to construct The determined fill density can be used as a reference; other optimal values ​​can also be selected based on design requirements. Alternative: The target thickness of the reactive wall at section location j is determined based on actual surveys; in actual engineering, the target thickness of the reactive wall is not only related to the feasibility of construction, but also to various factors such as cost, and needs to be calculated according to actual needs; that is to say, the target thickness of the reactive wall can be set to a preset value; The determination of the reaction rate constant based on the target hydraulic residence time specifically involves: obtaining the target hydraulic residence time and the target influent concentration at section j. and target effluent concentration The reaction rate constant k is calculated based on the following equation (1); (1); The acquisition of the target hydraulic residence time specifically involves: determining the target hydraulic residence time based on the pollutant with the longest half-life; a slightly larger value can be selected. The value has a margin; it is replaceable, and the target hydraulic retention time is determined according to the preset value in the removal requirements. The determination of the target thickness or target thickness range of the reactive wall based on the filling density or filling density range specifically involves: determining the effective porosity or effective porosity range based on the feasible domain function relationship of the effective porosity; obtaining the actual groundwater flow velocity; estimating the target thickness or target thickness range of the reactive wall based on the effective porosity or effective porosity range and the actual groundwater flow velocity; furthermore: calculating the target thickness or target thickness range of the reactive wall based on the following formula (2); where: It is the actual flow velocity of groundwater at section position j; It is the reaction rate constant at that location; It is the effective porosity at that location; when a filling density range is determined, the corresponding target thickness range is obtained. (2); Preferred: When multiple pollutants are present, take the calculated value. The maximum value is taken as the design dwell time for that section.

[0019] Step S4: Discretize the reactive wall at section position j into I segments; specifically: for the same wall orientation, set up no less than 3 parallel monitoring profiles to obtain the spatial distribution of pollutant concentration and groundwater flow velocity on the cross section, and discretize the wall orientation into I segments according to the horizontal / vertical direction, with each segment having the same or different width / height. Preferred method: Different discretization methods are used based on the different distribution characteristics of pollutant concentrations across the cross section; specifically: when the pollutant concentrations exhibit stratified characteristics across the cross section, horizontal discretization is performed. Figure 3 In the horizontal discretization case, the reactive barrier is discretized into three sections. Section I, at the top, has the highest pollutant concentration, while section III, at the bottom, has the lowest. To better illustrate the differences in cross-sectional thickness and filling density, schematic diagrams of the three sections are laid out flat. Layered characteristics are a common feature; when groundwater is deep, there are often differences in pollutant concentrations between the upper and lower groundwater layers. When pollutant concentrations exhibit segmented characteristics across the cross-section, vertical discretization is performed. Figure 4 The middle case is the vertical discrete case; when using funnel walls for auxiliary guidance, vertical discreteness is consistent with the distribution characteristics of pollutant concentration in many scenarios. Further steps include: obtaining local inflection points of pollutant concentration in the horizontal / vertical direction and dividing the area into sections; considering the superimposed flow velocity, sections with large flow velocity differences can be further subdivided into different sections; finally, if the width of a section is too small, the sections can be merged. Preferred: The number of segments is 3 to 7; Preferred: It can discretize in both horizontal and vertical directions simultaneously, but this will significantly increase the complexity of construction; Step S5: Under the constraint of the target thickness or target thickness range of the reactive wall j, perform bivariate trade-off optimization and comparison for the layout of each segment; determine the feasible region of each segment i of the reactive wall j that satisfies the remediation objective. The feasible region includes a binary pair of section wall thickness and infill density. After optimizing and comparing all sections of reactive wall j, a binary pair is selected from the feasible region of each section to form a sequence of binary pairs that satisfy the target thickness or target thickness range constraint of reactive wall j. The selection method involves combining feasible regions. As long as the sequence of binary tuples is unique, binary tuples within the feasible region of a segment i can be repeatedly selected. Specifically, for segment i of the reaction wall j, the following method is used: and The feasible region function relationship is shown in equation (3) in the bivariate space. In the process, the feasible domain that meets the repair objectives is determined. :in: These are the minimum fill density and the critical fill density, respectively. These are the minimum thickness and the maximum thickness, respectively. It is the actual groundwater flow velocity at section i of the reaction wall j; It is the effective porosity at section i; where: ; (3); In the feasible region This is the minimum fill density required to ensure sufficient mechanical strength in the wall, typically approximately 0.15 g / cm³. 3 ; The critical filling density was determined experimentally. This refers to the minimum wall thickness achievable during construction, typically approximately 0.5m. The maximum thickness is limited by construction equipment and is usually less than or equal to 10 m, but can reach 15 m with special processes. Preferred: for repairing the target To constrain the remediation, a target effluent pollutant concentration or target pollutant concentration range is set for the reactive wall j, which is then used as a unified remediation target for all sections i of the reactive wall j. Obviously, for different sections i, the inlet pollutant concentration may be the same or different; the theoretical outlet pollutant concentration is the same. The method further includes, within the feasible region of segment i of the reactive wall j. When the solution is divided into multiple sets or continuous values, the adsorption breakthrough curve is determined by column experiments at different packing densities. Adsorption capacity under certain conditions Determine the adsorbent utilization rate When the threshold is greater than or equal to the preset threshold As the optimal filling density ; and use one or more optimal fill densities The corresponding optimal solution serves as the determined filling density and wall thickness; continuous values ​​can be discretized to obtain the feasible region composed of discrete values; when the optimal solution is an exact value, engineering feasibility interpolation is performed based on this exact value to construct multiple effective solutions and expand the feasible region; subsequently, a binary sequence can be constructed based on this expanded feasible region. Preferred: in binary sequence When multiple or continuous values ​​are involved, selection is further based on the principle of apparent isomorphism. For multiple continuous segments, the filling density can be adjusted to ensure that multiple continuous segments have a uniform width setting, so that they have the same external characteristics but different actual adsorption capacities; achieving different adsorption capacities and reaction kinetics characteristics per unit volume, with uniform external morphology and differentiated internal functions; or selection can be based on the principle of spatial gradient matching, setting a smaller filling density for thicker segments. That is, high-concentration segments have a greater wall thickness than low-concentration segments, while having a lower adsorbent filling density than low-concentration segments. In other words, wall thickness is positively correlated with pollutant concentration, and adsorbent filling density is negatively correlated with pollutant concentration; different functional segments have different purification targets; thus, the groundwater flow rate is not significantly reduced, and the impact of the permeable wall on groundwater flow is minimized; Preferred: in binary sequence Once determined, the wall thickness and filling density of all sections, or all sections of all reactive walls, are determined. Further adjustments to the determined filling density are then made based on the ratio of pollutant concentration to the maximum concentration. Fine-tuning: to obtain the fill density used in the final implementation process. The adjustments here are for consistency across all sections of the reactive wall. Preferred method: Use (4) for fine-tuning; (4); in The maximum concentration of the pollutant plume. Let be the concentration normalization function, and when At higher levels, The lower the value, the lower the fill density is used in high concentration areas and the higher the fill density is used in low concentration areas; after adjusting the fill density, the thickness may need to be adjusted accordingly for consistency. The step of selecting a sequence of binary pairs from the feasible region of each segment that satisfies the target thickness or thickness range constraint of reactive wall j involves: calculating the average thickness of all segments based on the thickness or thickness range of each segment; if the average thickness is equal to or approximately equal to the target thickness of reactive wall j (belonging to the target thickness range of reactive wall j), then the constraint is satisfied; otherwise, it is determined that the constraint is not satisfied. The average thickness can be calculated using an equivalent method when the segment is discrete in a horizontal direction, as shown in the attached figure. Figure 3 As shown, the groundwater is layered according to its flow direction. The average thickness is calculated by weighting the thickness of each section with its spatial height. When the section is discretized vertically (divided from the bottom of the water body to the surface), as shown in the attached figure... Figure 4As shown, the average thickness is calculated by weighting the thickness of each segment with its spatial width; the figure shows a schematic diagram of the wall being discretized into 3 segments in the vertical direction; the high-concentration area on the left (segment 1) has the largest width, and the low-concentration area on the right (segment 3) has the smallest width; Preferred: The wall thickness in each section must meet the matching condition between the wall permeability coefficient and the aquifer permeability coefficient, so as to control the deviation of hydraulic residence time within the allowable deviation range agreed upon by the civil engineering.

[0020] Step S6: In-situ wall construction is carried out using the filling density and wall thickness determined by the binary sequence; specifically, deep mixing method, high-pressure jet injection method, hydraulic fracturing method, or a combination thereof is used to inject the mixed slurry formed by mixing the adsorbent and the slurry material according to the filling density into sections to the predetermined depth and the determined wall thickness, forming an integrated zoned wall; a gradual transition zone with varying thickness and filling material ratio is set at the boundary of each section; Preferred method: While keeping the overall cross-sectional area of ​​the wall basically unchanged, the local adsorption effectiveness is adjusted by the inward curvature of the water-facing side, the back water-facing side is fixed as a vertical line, the water-facing side is a variable curve, and the water-facing side curves between all sections are smoothly transitioned to avoid sudden hydraulic changes and local scouring.

[0021] Furthermore, the physical boundaries between each section are connected by a gradual transition zone to ensure the continuity of the hydraulic permeability coefficient. Alternative: As shown in the attached diagram, within each segment, the water-facing surface profile is a concave circular arc, the depth of which is inversely proportional to the target thickness of that segment, with adjacent arcs transitioning tangentially; as shown in the attached diagram. Figure 4 As shown; Alternatives: For a smoother and easier-to-manufacture surface, the water-facing profile can be achieved using piecewise cubic Hermite interpolation or a Bézier curve, as shown in the attached diagram. Figure 5 As shown, Figure 5 As shown on the left, within each segment, the curve is either a circular arc or a quadratic parabola; furthermore: as... Figure 5 As shown on the right, when the thickness values ​​at both ends of a section differ significantly, a third-order cubic Bézier curve is used to determine the upstream curve; conversely, when the difference is small, a second-order quadratic Bézier curve is used. Clearly, regardless of the final curve determined, it is generally concave to allow water flow to adhere without creating cavities or eddies. The concave surface typically increases local head loss slightly. After determining the final section, the thickness B value can be recalculated segment by segment to determine if the hydraulic residence time at that point meets the requirements. The method also includes: post-maintenance and regeneration of the reactive wall: when monitoring data indicates that pollutants have penetrated the wall, fresh adsorbent slurry is injected into the target section through the reserved regeneration grouting channel set on the wall to restore the function of the target area; Preferred method: When selecting each tuple in the binary sequence, different adsorbent settings are used for different wall thicknesses and filling densities determined for different segments; thus, for each segment, a trade-off can be made between filling density and wall thickness for different filling densities and wall thicknesses. One selection method is to use gel-type highly hydrophobic resin (Purolite A600) when the filling density is in the second density range, with a ratio of A600:colloidal activated carbon = 1:0.3~1:0.5; for thicker walls and moderate filling densities, priority is given to ensuring sufficient contact of long-chain PFAS; when the filling density is in the first density range, macroporous resin (Purolite A860) is selected. Mixed with A600; ratio: A860:A600:colloidal activated carbon = 1:1:0.4; at this point, the density is slightly higher than the second density range, and the short-chain adsorption kinetics are faster; when the filling density is in the third density range, a new type of monodisperse resin (LewatitTP108DW) or fluorinated modified resin is used, with a ratio: resin:colloidal activated carbon = 1:0.8~1:1; nano-sized particles, fast kinetics; where: the first density range is greater than the second density range, and the second density range is greater than the third density range; that is to say, the filling density in the high concentration section can be reduced and compensated by the wall thickness; the reduction of filling density increases the adsorption time, which is beneficial to the reduction of pollutants in the high concentration section; Example A simulation was conducted on a shallow unconfined aquifer contaminated with AFFF fire-fighting foam. The aquifer medium was mainly medium-coarse sand with a permeability coefficient K=4.8, groundwater flow velocity v=0.12m / d, and effective porosity n=0.30. The main pollutants were PFOA and PFHxS. The PFOA concentration distribution along the cross-section of the proposed wall is as follows: Anion exchange resin (quaternary ammonium groups, particle size 0.5–1.0 mm) was mixed with sand in the site at a volume ratio of 1:4. Column tests were conducted to determine the PFOA reaction rate constant k and effective porosity n under different packing densities. Using the inverse method of target residence time, the target residence time for each section was set to 1.3–1.5 times the theoretical minimum. The total wall length was 100 m, the wall height was 8 m, and the section thicknesses were 3.3 m, 2.0 m, and 0.5 m, with packing densities of 0.31, 0.34, and 0.20, respectively. Simulation data from downstream monitoring wells showed that PFOA downstream of section I was ≤55 ng / L, downstream of section II was ≤18 ng / L, and downstream of section III was ≤8 ng / L, all meeting the target of ≤70 ng / L. Backwater in front of the wall was <0.1 m, and no localized bypass flow was observed. The section design met the simplification requirements of the actual project and the target outlet concentration requirements. Figure 6Langmuir isotherm adsorption fitting curves for different concentration ranges are shown; all fitting correlation coefficients are 0.97, indicating that the adsorption behavior conforms to the monolayer adsorption model, and are used to demonstrate the adsorption performance of each material at the actual design concentration. The three curves correspond to three ranges: range 1 uses A600 type resin as the main adsorbent with medium-density filling, which has a high adsorption capacity for long-chain PFOA; range 2 uses a mixed ratio with high-density filling; and range 3 uses low-density filling, which has high adsorption efficiency for low-concentration PFAS. The terms "data processing apparatus," "data processing system," "user equipment," or "computing device" encompass all kinds of apparatus, devices, and machines for processing data, including, for example, programmable processors, computers, systems-on-a-chip, or a combination thereof. The apparatus may include special-purpose logic circuitry, such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits). In addition to hardware, the apparatus may also include code that creates an execution environment for the computer program, such as code constituting processor firmware, protocol stacks, database management systems, operating systems, cross-platform runtime environments, virtual machines, or combinations thereof. The apparatus and execution environment can implement various computing model infrastructures, such as web services, distributed computing, and grid computing infrastructures.

[0022] A computer program (also referred to as a program, software, software application, script, or code) can be written in any form of programming language, including assembly or interpreted languages, declarative or procedural languages, and can be deployed in any form, including as a standalone program or as a module, component, subroutine, object, or other unit suitable for use in a computing environment. A computer program may, but does not necessarily, correspond to a file in a file system. A program can be stored as part of a file that holds other programs or data (e.g., one or more scripts stored in a markup language document), in a single file dedicated to said program, or in multiple co-located files (e.g., a file storing one or more modules, subroutines, or code portions). A computer program can be deployed to execute on a single computer or on multiple computers located at a single site or distributed across multiple sites and interconnected by a communications network.

[0023] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0024] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations and / or block diagrams. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0025] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0026] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0027] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for deploying an adsorbent to remove perfluorinated compounds from groundwater, characterized in that, include: Step S1: Site investigation and plume characterization to determine the location of the reactive barrier; Step S2: Determine the feasible region function relationship of the reaction rate constant under different packing densities. Relationship between feasible region function and effective porosity ; Step S3: Determine the target thickness for each reactive barrier; Step S4: Discretize each reactive wall into Each section; Step S5: Under the constraint of the target thickness of the reactive wall, perform bivariate trade-off optimization and comparison of the segment layout; determine the feasible region of each segment i of the reactive wall j that satisfies the remediation objective. The feasible region includes a binary pair of section wall thickness and infill density. After optimizing and comparing all sections of reactive wall j, a binary pair is selected from the feasible region of each section to form a sequence of binary pairs that satisfy the target thickness or target thickness range constraint of reactive wall j. ; Step S6: Construct the reactive wall using the determined fill density and wall thickness.

2. The adsorbent deployment method for removing perfluorinated compounds from groundwater according to claim 1, characterized in that, Step S1 specifically involves: obtaining the three-dimensional spatial distribution of hydrogeological parameters and / or pollutant concentrations of the contaminated site through drilling, well deployment, high-density passive flux meter monitoring, and / or groundwater sampling and analysis; establishing a three-dimensional spatial distribution map of pollutant concentrations in the pollutant plume; identifying the geometric morphology of the outer edge of the pollutant plume; determining the location of the reaction wall at the front end of the potential pollutant diffusion zone based on the migration and diffusion mode and range of the pollutants; and numbering the reaction walls.

3. The adsorbent deployment method for removing perfluorinated compounds from groundwater according to claim 2, characterized in that, Step S3 specifically involves: determining the reaction rate constant based on the target hydraulic residence time, then determining the filling density based on the feasible domain function relationship of the reaction rate constant, and finally determining the target thickness of the reaction wall based on the filling density or the range of filling density.

4. The adsorbent deployment method for removing perfluorinated compounds from groundwater according to claim 2, characterized in that, Step S4 specifically involves: for the same wall orientation, setting up no fewer than three parallel monitoring profiles to obtain the spatial distribution of pollutant concentration and groundwater flow velocity on the cross-section, and discretizing the wall orientation according to the horizontal / vertical direction. Each section.

5. The adsorbent deployment method for removing perfluorinated compounds from groundwater according to claim 4, characterized in that, Different discretization methods are used based on the different distribution characteristics of pollutant concentrations on the cross section; when the pollutant concentrations exhibit stratified characteristics on the cross section, horizontal discretization is performed; when the pollutant concentrations exhibit segmented characteristics on the cross section, vertical discretization is performed. Taking into account the superimposed flow velocity, the sections with large differences in flow velocity are further subdivided into different sections.

6. The adsorbent deployment method for removing perfluorinated compounds from groundwater according to claim 5, characterized in that, For section i of reactive wall j, use and The feasible region functional relationship is shown in equation (3) in the bivariate space. In the process, determine the feasible region for each segment i that satisfies the repair objective. :in: These are the minimum fill density and the critical fill density, respectively. These are the minimum thickness and the maximum thickness, respectively. It is the actual groundwater flow velocity at section i of the reaction wall j; It is the effective porosity at section i; where: ; （3）。 7. The adsorbent deployment method for removing perfluorinated compounds from groundwater according to claim 6, characterized in that, The step of selecting a sequence of binary pairs that satisfy the target thickness constraint of reactive wall j from the feasible domain of each segment is as follows: based on the thickness of each segment, the average thickness of all segments of reactive wall j is calculated. If the average thickness is equal to or approximately equal to the target thickness of reactive wall j, the constraint is determined to be satisfied; otherwise, it is determined not to be satisfied.

8. An adsorbent for removing perfluorinated compounds from groundwater, characterized in that, The adsorbent is used in the adsorbent deployment method for removing perfluorinated compounds from groundwater as described in any one of claims 1-7, wherein the adsorbent is anion exchange resin, colloidal activated carbon, modified bentonite, zero-valent iron, zeolite, or any combination thereof.

9. The adsorbent for removing perfluorinated compounds from groundwater according to claim 8, characterized in that, When selecting each tuple in the binary sequence, different adsorbent settings are used for different sections with different wall thicknesses and filling densities, thus corresponding to different filling densities and wall thicknesses. For sections with high pollutant concentrations, medium-density filling is used; for sections with medium pollutant concentrations, high-density filling is used; and for sections with low to medium pollutant concentrations, low-density filling is used.

10. The adsorbent for removing perfluorinated compounds from groundwater according to claim 9, characterized in that, For each section, a trade-off can be made between filler density and wall thickness; when the filler density is in the second density range, a gel-type highly hydrophobic resin is used with a ratio of [A600: colloidal activated carbon = 1:0.3~1:0.5]; when the wall is thicker, the filler density is moderate to ensure sufficient contact of long-chain PFAS; when the filler density is in the first density range, a macroporous resin mixed with A600 is selected. Mixing ratio: [A860:A600:colloidal activated carbon = 1:1:0.4]; Short-chain adsorption kinetics are faster; when the packing density is in the third density range, a new type of monodisperse or fluorinated modified resin is used, with a ratio of [resin: colloidal activated carbon = 1:0.8~1:1]; wherein: the first density range is greater than the second density range, and the second density range is greater than the third density range.

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