Dual-mode in-situ underground water well repairing device driven by aerodynamic force

Abstract

An aerodynamic force-driven dual-mode in-situ underground water well repairing device is characterized in that an upper flange is fixed at the top of an outer well casing, a bracket is arranged between gaskets of the upper flange, the lower section of the outer well casing is an upper screen pipe, a lower-end rubber sleeve is connected between the upper screen pipe and the lower screen pipe, a lower flange is fixed at the lower end of the lower screen pipe, and an inner well casing is arranged in the outer well casing; the upper end of the inner well pipe is located above the upper screen pipe, the lower end of the inner well pipe is flush with the lower end of the rubber sleeve and is in sealed connection with the bottom of the rubber sleeve, the inner well pipe is communicated with the lower screen pipe, the aeration pipe penetrates through the inner well pipe, penetrates out of the upper flange and is fixed to the upper half portion of the upper flange, and the lower end of the aeration pipe is connected with the aeration head; the aerator pipe on the upper portion of the inner well pipe is sleeved with a fixed rubber plug and a fixed water blocking partition plate, and the pipe wall of the outer well pipe is provided with and communicated with a tail gas pipe. The aeration mode and the circulation mode are flexibly switched, so that the repairing efficiency of volatile organic pollutants in the underground aquifer is effectively improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of groundwater pollution remediation, and relates to a well device for in-situ remediation of contaminated groundwater, in particular, a dual-function in-situ remediation well capable of switching between an aeration mode and a circulation enhancement mode based on pneumatic power driving. BACKGROUND

[0002] In the field of groundwater pollution remediation, pneumatic remediation technology is widely used and has become one of the most important remediation methods. As one of the earliest groundwater remediation technologies, aeration technology can effectively promote the volatilization of pollutants by enhancing gas exchange in groundwater, and has the advantages of high efficiency, economy, and simple operation. This technology injects air or oxygen into the groundwater saturated zone to form bubbles, causing volatile pollutants to degas from the water phase to the gas phase, while increasing the dissolved oxygen in the water, thereby promoting aerobic biodegradation reactions. It has been widely used in the removal of volatile organic pollutants in soil and groundwater.

[0003] A groundwater circulation well (GCW) is a technology that accelerates the removal of pollutants in groundwater by circulating water flow through well aeration. According to the different circulation methods, the groundwater circulation well can be divided into hydrodynamic circulation well and pneumatic circulation well. The pneumatic circulation well adopts a "double-layer well" structure, which generates a density difference of gas-water mixture through bottom aeration, causing water flow to form an upward flow in the well, thereby forming a closed circulation path of "upward in the well and downward outside the well". This structure does not rely on mechanical power underground, has low energy consumption, and can continuously supply oxygen to activate indigenous microorganisms, forming a physical-biological synergistic remediation effect.

[0004] The prior art has the problems of single function, poor synergy, and high engineering cost of aeration wells and circulation wells, SUMMARY The present application proposes a dual-mode in-situ groundwater remediation well device driven by pneumatic power to solve the problems of single function, poor synergy, and high engineering cost of aeration wells and circulation wells in the prior art. Through unique structural design, the present application can quickly and conveniently switch between "in-situ aeration remediation" and "pneumatic circulation enhancement" according to remediation requirements, thereby realizing the dual function of stripping volatile pollutants and driving chemicals to migrate and diffuse in the aquifer with one set of device, ultimately achieving the goal of improving remediation efficiency, reducing engineering cost and complexity.

[0005] This invention enables rapid and convenient switching between two working modes: external aeration and internal aeration, depending on the remediation needs. In external aeration mode, the invention removes volatile pollutants by blowing air into the well. In internal aeration mode, the invention uses pneumatic aeration within the well to drive the migration and diffusion of solute agents within the aquifer, further enhancing the pollutant removal effect. The synergistic effect of these two modes allows the invention to remove not only volatile pollutants but also non-volatile pollutants, improving remediation efficiency, reducing engineering costs and complexity, and providing an innovative solution for groundwater pollution remediation.

[0006] A pneumatically driven dual-mode in-situ groundwater remediation well device includes an aeration pipe, an upper flange, a tailpipe, a support, a water-blocking baffle, an outer well pipe, an upper screen pipe, a rubber plug, an inner well pipe, a rubber sleeve, a lower flange, a lower screen pipe, and an aeration head. The upper flange is fixed to the top of the outer well pipe, and the support is positioned between the gaskets of the upper flange. The lower section of the outer well pipe is the upper screen pipe, the lower end of which is connected to the rubber sleeve, and the lower end of the rubber sleeve is connected to the upper end of the lower screen pipe. The lower end of the lower screen pipe is fixed to the lower flange. The inner well pipe is placed inside the outer well pipe, with its upper end above the upper screen pipe. The lower end of the inner well pipe is flush with the lower end of the rubber sleeve and sealed to the bottom of the rubber sleeve. The inner well pipe communicates with the lower screen pipe, and the aeration pipe passes through the inner well pipe, with its upper end extending out of the upper flange. It is fixed together with the upper part of the upper flange. The lower end of the aeration pipe is located in the lower screen pipe and is connected to the aeration head. The aeration pipe at the top of the inner well pipe is fitted with a fixed rubber plug. When the support is in the middle of the upper flange, it supports and lifts the upper part of the upper flange. The upper part of the flange drives the aeration pipe to move upward. The aeration pipe drives the rubber plug to disengage from the seal on the top opening of the inner well pipe. After the support is removed, the upper part and the lower part of the upper flange are bolted together. The aeration pipe moves downward with the upper part of the upper flange. The aeration pipe drives the rubber plug to seal the top opening of the inner well pipe. The aeration pipe at the top of the rubber plug is fitted with a fixed water-blocking baffle. The water-blocking baffle can prevent water from overflowing from the top opening of the outer well pipe. The outer well pipe wall below the water-blocking baffle is equipped with and connected to a tail gas pipe.

[0007] The bracket is arc-shaped.

[0008] Features of this invention: This invention integrates groundwater circulation and aeration functions into one unit, allowing for flexible switching between the two functions depending on the pollution situation. For example, when dealing with heterogeneous strata, aeration is first used to remove pollutants from the main area, followed by switching to circulation mode to carry out pollutants from the lens or hard-to-penetrate areas, and then aeration is used again to further accelerate the volatilization and removal of pollutants. Through this mode switching, the removal effect can be optimized according to the distribution characteristics of pollutants in groundwater and the stratum characteristics, ensuring the best remediation effect under different stratum conditions.

[0009] The working process and principle of this invention: When the upper flange is open, the rubber plug does not block the inner well opening. The aeration pipe is connected to the aeration pump, and the aeration head is located in the middle of the lower screen pipe and aerates. Water flows in from the lower screen pipe, rises through the inner well pipe, and flows out from the upper screen pipe. This is the circulation well mode. When the upper flange is closed, the screws are tightened. Without the support bracket, the rubber plug blocks the top opening of the inner well pipe. The airflow cannot overflow from the inner well pipe but instead starts to diffuse from the lower screen pipe to the well perimeter. This is the aeration mode.

[0010] The beneficial effects of this invention are: This invention effectively improves the remediation efficiency of volatile organic pollutants (VOCs) in groundwater aquifers by flexibly switching between aeration and circulation modes. It can adopt the most suitable remediation strategy based on the distribution characteristics of pollutants in different strata. When pollutants are concentrated, aeration promotes the transfer of pollutants from the aqueous phase to the gas phase; when pollutants are widely distributed or exist in heterogeneous strata, circulation mode achieves pollutant redistribution, further enhancing the remediation effect. Furthermore, by introducing remediation agents into the well and combining them with the circulation process, the agents can be more evenly distributed in the polluted area, thereby strengthening the removal effect. In addition, the synergistic effect of circulation and aeration can significantly improve the removal efficiency of VOCs and reduce the tailing rebound phenomenon commonly found in traditional remediation methods. This invention not only provides an innovative solution for groundwater pollution remediation but also provides important theoretical basis and practical support for the future development of groundwater remediation technology, while reducing engineering costs. Attached Figure Description

[0011] Figure 1 This is a three-dimensional perspective structural diagram of the present invention in loop mode; Figure 2 This is a three-dimensional perspective structural diagram of the present invention in aeration mode; Figure 3 This is a three-dimensional schematic diagram of the present invention in loop mode; Figure 4 This is a three-dimensional schematic diagram of the invention in aeration mode; Figure 5 This is a cross-sectional view of the aeration mode of the present invention; Figure 6 This is a cross-sectional view of the cyclic mode of the present invention; Figure 7 The figures show the solute transport trajectory and velocity vector diagram for a coarse sand aquifer under individual circulation conditions, with aeration flow rates from top to bottom of 0.2 m³ / s. 3 / h, 0.4m 3 / h, 0.6m 3 / h; Figure 8 This diagram shows the airflow influence range when coarse sand is aerated alone, with aeration flow rates of 0 m³ / s. 3 / h, 0.1m 3 / h, 0.2m 3 / h, 0.24m 3 / h, 0.3m 3 / h, 0.4m 3 / h, 0.5m 3 / h, 0.6m 3 / h and 0.7m 3 / h; Figure 9 The diagram shows the solute transport trajectory and flow field velocity vector diagram under coarse sand medium with initial aeration followed by circulation. The aeration flow rates from top to bottom are 0.2 m³ / s. 3 / h, 0.4m 3 / h and 0.6m 3 / h; Figure 10 This is a distribution map of benzene pollutant concentrations in a gravel-based treatment method involving pre-aeration followed by circulation. Figure 10 (a) represents the initial concentration of benzene contaminant; Figure 10 (b) is a distribution diagram of benzene pollutant concentration with an aeration time of 0.5 h; Figure 10 (c) is a distribution diagram of benzene pollutant concentration when the aeration time is 1 hour, at which point the aeration mode is switched to the circulation mode; Figure 10 (d) is a distribution chart of benzene pollutant concentration after switching from aeration to circulation at 1 hour and after 1 hour of circulation, with a total running time of 2 hours; Figure 11 The graph shows the dynamic changes in the degradation of benzene pollutants in gravel media over 0-4 hours under different treatment modes. Different treatment modes refer to single circulation, single aeration, and aeration followed by circulation. Figure 12 This is a distribution diagram of benzene pollutant concentration in a coarse sand medium treatment method involving pre-aeration followed by circulation. Figure 12 (a) represents the initial concentration of benzene contaminant; Figure 12 (b) is a distribution diagram of benzene pollutant concentration with an aeration time of 1 hour; Figure 12 (c) is a distribution diagram of benzene pollutant concentration after 2 hours of aeration, at which point the aeration mode is switched to the circulation mode; Figure 12 (d) is a distribution of benzene pollutant concentration after switching to circulation mode for 1 hour after 2 hours of aeration. The total running time is 3 hours. Figure 12 (e) is a distribution of benzene pollutant concentration after switching to circulation mode for 2 hours after 2 hours of aeration. That is, aeration for the first two hours and circulation for the next two hours. The total running time is 4 hours. Figure 13 This is a dynamic graph showing the degradation of benzene pollutants in coarse sand media over 0-6 hours under different treatment modes. Different treatment modes refer to single circulation, single aeration, and aeration followed by circulation.

[0012] In the diagram: 1-Aeration pipe; 2-Upper flange; 3-Tail gas pipe; 4-Support; 5-Water-blocking baffle; 6-Outer well pipe; 7-Upper screen pipe; 8-Rubber plug; 9-Inner well pipe; 10-Rubber sleeve; 11-Lower flange; 12-Lower screen pipe; 13-Aeration head. Detailed Implementation

[0013] Please see Figures 1 to 6 As shown, a pneumatically driven dual-mode in-situ groundwater remediation well device includes an aeration pipe 1, an upper flange 2, a tailpipe 3, a support 4, a water-blocking baffle 5, an outer well pipe 6, an upper screen pipe 7, a rubber plug 8, an inner well pipe 9, a rubber sleeve 10, a lower flange 11, a lower screen pipe 12, and an aeration head 13. The upper flange 2 is fixed to the top of the outer well pipe 6, and the support 4 is arranged between the gaskets of the upper flange 2. The lower section of the outer well pipe 6 is the upper screen pipe 7. The lower end of 7 is connected to the rubber sleeve 10, and the lower end of the rubber sleeve 10 is connected to the upper end of the lower screen pipe 12. The lower end of the lower screen pipe 12 is fixed with the lower flange 11. The inner well pipe 9 is installed in the outer well pipe 6. The upper end of the inner well pipe 9 is located above the upper screen pipe 7. The lower end of the inner well pipe 9 is flush with the lower end of the rubber sleeve 10 and is sealed to the bottom of the rubber sleeve 10. The inner well pipe 9 is connected to the lower screen pipe 12. The aeration pipe 1 passes through the inner well pipe 9, and the upper end of the aeration pipe 1 passes through the upper flange 2. It is fixed together with the upper half of the upper flange 2. The lower end of the aeration pipe 1 is located in the lower screen pipe 12. The lower end of the aeration pipe 1 is connected to the aeration head 13. The aeration pipe 1 on the upper part of the inner well pipe 9 is fitted with a fixed rubber plug 8. When the bracket 4 is located in the middle of the upper flange 2, it supports and lifts the upper half of the upper flange 2. The upper half of the flange 2 drives the aeration pipe 1 to move upward. The aeration pipe 1 drives the rubber plug 8 to disengage from the seal on the top opening of the inner well pipe 9. After the bracket 4 is removed, the upper half and the lower half of the upper flange 2 are connected together with bolts. The aeration pipe 1 moves downward with the upper half of the upper flange 2. The aeration pipe 1 drives the rubber plug 8 to seal the top opening of the inner well pipe 9. The aeration pipe 1 on the upper part of the rubber plug 8 is fitted with a fixed water-blocking baffle 5. The outer periphery of the water-blocking baffle 5 is sealed with the outer well pipe 6. The water-blocking baffle 5 can prevent water from overflowing from the top opening of the outer well pipe 6. The outer well pipe 6 wall below the water-blocking baffle 5 is provided with and connected to the tail gas pipe 3.

[0014] The bracket 4 is arc-shaped.

[0015] In this embodiment, the outer well pipe 6 is 56cm long and 6cm in diameter; the inner well pipe 9 is 33cm long and 2cm in diameter; the upper flange 2 and the lower flange 11 are both 4cm thick; the outer well pipe 6 and the inner well pipe 9 form a casing, with the inner well pipe 9 located 13-46cm inside the outer well pipe 6 (from bottom to top). The casing is vacuum-sealed and fixed at the 13-33cm position. The outer well pipe has uniformly perforated holes at 0-8cm and 33-41cm to form a sieve-like upper sieve pipe 7 and a lower sieve pipe 12; the aeration pipe 1 is 65cm long and connected to the aeration head 13. The aeration pipe 1 is fixed at the center of the upper flange 2, and the aeration head 13 is located in the middle of the lower sieve pipe 12. The rubber plug 8 and the water-blocking baffle 5 are fixed on the aeration pipe 1. When the upper flange 2 is open, two 2cm high arc-shaped brackets 4 are fixed between the two pieces of the upper flange 2. At this time, the rubber plug 8 does not block the top opening of the inner well pipe 9, which is the circulation well mode. When the brackets 4 are removed, the two pieces of the upper flange 2 are closed, the screws are tightened, and the rubber plug 8 blocks the top opening of the inner well pipe 9. At this time, it is the aeration mode. The exhaust pipe 3 is located below the water-blocking baffle 5 and is mainly used for exhaust during circulation. The water-blocking baffle 5 is located above the rubber plug 8 and is mainly used to prevent water from spraying out of the well opening due to excessive flow during circulation. The rubber cylinder 10 is located between the upper screen pipe 7 and the lower screen pipe 12. The wall thickness of the rubber cylinder 10 is 2cm. The purpose is to prevent the airflow from flowing along the well wall during aeration, forming a side wall effect, which would cause uneven airflow diffusion.

[0016] The working process of this embodiment: 1. This embodiment is in loop mode: like Figure 1 and Figure 3 As shown, this embodiment is placed in an experimental tank, which is filled with experimental medium and saturated with water. At this time, the support 4 is positioned between the gaskets of the upper flange 2, and the rubber plug 8 is positioned above the inner well pipe 9. The rubber plug 8 does not seal the top opening of the inner well pipe 9. The aeration pipe 1 is connected to an external aeration pump. Gas overflows from the aeration head 13 through the aeration pipe 1. Since the top opening of the inner well pipe 9 is not sealed by the rubber plug 8 at this time, and the pressure at the lower screen pipe 12 is reduced due to the large amount of gas, water flows in from the lower screen pipe 12, rises along the inner well pipe 9, and flows out from the upper screen pipe 7, completing the circulation.

[0017] 2. This embodiment is in aeration mode: like Figure 2 and Figure 4 As shown, at this time there is no support from bracket 4, the upper flange 2 is tightened and sealed, the rubber plug 8 moves down to block the top of the inner well pipe 9, the water flow cannot rise along the inner well pipe 9 during aeration, so the gas starts to escape from the lower screen pipe 12 to both sides of the well, thus completing the aeration.

[0018] 3. In addition to the above-described implementation methods, the following implementation methods may also be used in this embodiment: ① Aeration followed by circulation, then aeration again: In some cases, especially when pollutants are concentrated and the formation is relatively homogeneous, aeration mode can be used first for preliminary pollutant volatilization and removal. During aeration, pollutants are transferred from the aqueous phase to the gas phase and are initially removed through gas dispersion. Subsequently, the circulation mode is switched to, and the pollutants are redistributed through water flow disturbance, carrying out pollutants that are difficult to remove. Finally, the aeration mode is switched back to further enhance the volatilization and removal of pollutants, ensuring the thoroughness of the removal effect.

[0019] ② First aeration, then chemical addition and circulation, then aeration again: Under certain special pollution conditions, especially when the pollutant types are more complex or there is a strong demand for biodegradation, the pollutants can be initially removed in aeration mode; then, the remediation agent is added and switched to circulation mode, so that the agent can be more evenly distributed and react with the pollutants or enhance the degradation process; through circulation, the agent can be effectively transported to the pollution source area, thereby enhancing the remediation effect; finally, switch back to aeration mode to accelerate the volatilization of pollutants and complete the entire remediation process.

[0020] ③ Staged multiple aeration and circulation alternation: For situations where pollutant distribution is complex or there are multiple layers of pollutants, a multi-stage aeration and circulation alternation mode can be designed. Each stage removes pollutants of different properties through aeration, and then the pollutants are redistributed through circulation to ensure that pollutants at different levels can be effectively repaired. This method can achieve the best effect in the removal of different pollution layers and different types of pollutants through multiple alternating aeration and circulation.

[0021] These implementation methods can be flexibly adjusted according to the specific type of groundwater pollution, the distribution characteristics of pollutants, and the geological structure to ensure the maximization of remediation effects.

[0022] I. Experimental Verification Process: The experimental tank was placed in the middle of the experimental tank, which was filled with fused silica sand (coarse sand) with a particle size of 0.45-0.85 mm and saturated with water. The experiment included four modes: single circulation, single aeration, circulation followed by aeration, and aeration followed by circulation, in order to observe the differences in the repair effect and the coupling effect under different operating conditions.

[0023] like Figure 7 The figure shows the solute transport trajectory and velocity vector diagram when the coarse sand aquifer is circulated alone. The aeration flow rate from top to bottom is 0.2 m³ / s. 3 / h, 0.4m 3 / h, 0.6m 3 / h, inject brilliant blue staining agent into the middle of each pair of sampling points from both the upper and lower parts to observe the solute transport. The solute transport traces are shown in the figure on the left. 3Taking an aeration flow rate of / h as an example, after starting the GCW, the bright blue liquid rapidly migrates towards the lower perforated pipe of the GCW under the drive of the hydraulic gradient. The bright blue liquid on the lower right can enter the well through the lower perforated pipe in 4 minutes, and at the same time, it also clearly migrates back into the main medium in 4 minutes. The bright blue liquid on the upper right migrates more slowly due to the weaker water circulation intensity, but it has completely entered the lower perforated pipe in 9 minutes. Due to the asymmetry of the flow rates on the left and right sides, the overall flow field is slightly biased to the left. The length of the vector arrow increases and gradually changes from blue to red, indicating that the groundwater velocity is higher at this location. Therefore, the groundwater velocity near the GCW is much greater than that on both sides of the simulated tank, and the velocity at the bottom is greater than that at the top. As the aeration flow rate increases, the groundwater velocity also gradually increases, and the solute transport speed also accelerates.

[0024] like Figure 8 The diagram shown illustrates the airflow influence range when coarse sand is aerated alone. Figure 8 The changes observed show that as the aeration flow rate increases, the diffusion range of the airflow in the coarse sand medium gradually increases. Initially, the aeration flow rate was 0.1 m³ / s. 3 At a flow rate of 0.4 m³ / h, the influence range of the airflow is relatively small, with only slight bubble diffusion occurring in localized areas. However, this effect increases over time, especially when the aeration flow rate reaches 0.4 m³ / h. 3 / h, 0.5m 3 At a flow rate of 0.6 m³ / h, the bubbles gradually expand, covering a wider area, and the disturbance effect of the airflow on the medium becomes more pronounced; when the aeration flow rate reaches 0.6 m³ / h... 3 / h, 0.7m 3 At a flow rate of 0.4-0.5 m³ / h, some of the original small channels are broken up by the bubbles, forming large dominant channels around the well. Therefore, it is determined that when the aeration flow rate is 0.4-0.5 m³ / h, the optimal flow rate is... 3 The airflow influence range is greatest and most uniform when the airflow reaches a certain speed ( / h).

[0025] These images show that, within a certain flow rate range, the higher the flow rate, the wider the diffusion range of bubbles in the medium, forming a more uniform airflow disturbance field, especially under higher aeration flow rate conditions (e.g., 0.4-0.5 m). 3 The bubble aggregation area expanded significantly and gradually diffused into the deeper layers and outer edges of the medium ( / h), indicating that higher flow rates of aeration can more effectively promote bubble dispersion and the formation of air channels.

[0026] Based on the current experimental results, the study further explored the coupling between aeration and circulation modes. It was found that in experiments involving circulation after aeration, the solute transport trajectory changed significantly. Taking coarse sand as an example, the operation of aeration followed by hydraulic circulation... Figure 9 As shown, the aeration flow rates from top to bottom are 0.2 m³ / s. 3 / h, 0.4m 3 / h, 0.6m 3 / h, significant differences in solute transport trajectories and flow field velocity vectors can be observed between single circulation and circulation after aeration.

[0027] exist Figure 7 In the single-cycle experiment shown, the solute transport trajectory exhibited a relatively uniform diffusion pattern, the flow field velocity vector was relatively stable, and the solute distribution expansion path was relatively dispersed. Experimental images show that solute migration was mainly concentrated near the lower perforated tube, maintaining a relatively broad diffusion trend over a large area; however... Figure 9 In the experiment showing recirculation after aeration, the solute transport trajectory changed significantly. The gas channels generated by aeration guided the preferential flow of the solute, making the solute transport trajectory sharper and concentrated within the aeration channel region. The flow velocity vector exhibited stronger flow directionality, and the solute migration speed was significantly accelerated; compared with... Figure 7 Compared to the standalone cycle shown, the cycle after aeration allows the solute to migrate along the airway more quickly, forming a more concentrated flow path.

[0028] II. Pollutant removal effect: 1) In the experiment using gravel media with a particle size of 5-10 mm, an aeration-following-circulation treatment method was adopted. The degradation effect of benzene pollutants under different aeration and circulation conditions at different time periods was analyzed in detail. The benzene pollutant concentration at the initial stage of the experiment was as follows: Figure 10 As shown in (a), Figure 10 (b) and Figure 10 (c) The concentration degradation of benzene pollutants under aeration conditions is shown respectively, with aeration times of 0.5h and 1h and an aeration flow rate of 0.7m³ / h. Under the aeration condition of 0.5h, the concentration of pollutants is significantly reduced, but not completely removed, and the concentration drops to 45mg / L. After 1 hour of aeration, the concentration of pollutants further decreases to 12mg / L. At this point, a tailing phenomenon appears, indicating that the benzene pollutants have not been completely degraded.

[0029] To further improve the remediation effect, after 1 hour of aeration, the system was switched to circulation mode with a circulation flow rate of 0.3 m³ / h. Under circulation conditions, the water flow disturbance effectively distributed and migrated the pollutants, and ultimately, after 2 hours, the concentration of benzene pollutants dropped to almost zero. Figure 10 As shown in (d), this result indicates that although aeration can effectively remove pollutants in gravel media, there is still a certain degree of tailing phenomenon. By combining aeration with circulation, not only can the removal of pollutants be accelerated, but the tailing phenomenon that occurs during aeration can also be overcome, thus achieving a more thorough degradation of benzene pollutants.

[0030] Figure 11The study demonstrated the dynamic changes in the overall average benzene pollutant degradation of the tank under different treatment modes (single circulation, single aeration, and aeration followed by circulation) within 0-4 hours. The results showed that although the degradation rate was slower in the initial stage of circulation degradation, the benzene pollutant concentration almost dropped to zero after 3 hours, indicating a more thorough degradation effect, but the overall degradation time was longer. In contrast, the degradation rate was faster in the initial stage of aeration degradation, but the benzene pollutant concentration tended to stabilize at about 15 mg / L after 1.5 hours, showing a slight tailing phenomenon. The aeration followed by circulation mode switched to circulation mode after 1 hour of aeration, and after 2 hours of treatment, the benzene pollutant concentration almost dropped to zero, showing a relatively rapid and thorough degradation effect.

[0031] 2) In the experiment using coarse sand media, a treatment method of aeration followed by circulation was adopted to study the degradation effect of benzene pollutants under different aeration and circulation conditions over different time periods. The initial concentration distribution of benzene in the experiment is shown below. Figure 12 As shown in (a); Figure 12 (b) Figure 12 (c) shows the concentration degradation of benzene pollutants under aeration conditions, with aeration times of 1 h and 2 h and an aeration flow rate of 0.6 m³ / h. Under 2 h of aeration, the pollutant concentration decreased and was mainly concentrated in the well perimeter area, but the pollutants showed tailing and rebound phenomena in the two sides, indicating that the degradation effect was incomplete.

[0032] To further enhance the repair effect, switch to circulation mode after 2 hours of aeration. Figure 12 (d) Figure 12 (e) shows the concentration degradation of benzene pollutants under circulating conditions, with circulating times of 3h and 4h and a circulating flow rate of 0.6m³ / h. Under circulating conditions, water flow disturbance helps pollutants to be more evenly distributed and migrated in the well perimeter area. Finally, at 4h, the concentration of benzene pollutants dropped to almost zero, showing a significant degradation effect. This experiment shows that in coarse sand media, aeration is prone to tailing and rebound phenomena. However, by combining aeration and circulation alternately, the tailing and rebound phenomena that occur during aeration can be effectively overcome, achieving a more thorough degradation of benzene pollutants.

[0033] Figure 13This study demonstrates the dynamic changes in the overall average benzene pollutant degradation in the experimental tank over 0-6 hours using different treatment methods (single circulation, single aeration, and aeration followed by circulation). The results show that although the degradation rates of aeration and circulation are similar initially, the efficiency of aeration gradually decreases and a tailing phenomenon occurs later, especially after 4 hours, when the pollutant concentration remains around 50 mg / L. In contrast, in circulation degradation, the benzene pollutant concentration almost drops to zero by 6 hours, showing higher degradation efficiency, but the time required is relatively longer. The aeration followed by circulation mode degrades pollutants through aeration for the first two hours, then switches to circulation mode after 2 hours. After 4 hours of treatment, the benzene pollutant concentration almost drops to zero, demonstrating a faster and more thorough removal effect than aeration or circulation alone.

[0034] Based on the experimental results, it is speculated that the degradation effect of aeration followed by circulation is better. This is because pore channels are formed in the coarse sand medium during the aeration process, which accelerates the water flow rate in the subsequent circulation stage. The circulation also redistributes pollutants and removes them from the well. In addition, the degradation effect in the early stage of aeration also helps to remove pollutants. Therefore, the aeration followed by circulation mode shows higher pollutant removal efficiency and more thorough degradation effect.

Claims

1. A device for a pneumatically driven dual-mode in-situ groundwater remediation well, characterized in that: The system includes an aeration pipe (1), an upper flange (2), an exhaust pipe (3), a support (4), a water-blocking baffle (5), an outer well pipe (6), an upper screen pipe (7), a rubber plug (8), an inner well pipe (9), a rubber sleeve (10), a lower flange (11), a lower screen pipe (12), and an aeration head (13). The upper flange (2) is fixed to the top of the outer well pipe (6), and the support (4) is placed between the gaskets of the upper flange (2). The lower section of the outer well pipe (6) is the upper screen pipe (7), and the lower end of the upper screen pipe (7) is connected to the rubber sleeve (11). 0) Connection: The lower end of the rubber sleeve (10) is connected to the upper end of the lower screen pipe (12). The lower end of the lower screen pipe (12) is fixed with the lower flange (11). The inner well pipe (9) is set in the outer well pipe (6). The upper end of the inner well pipe (9) is located above the upper screen pipe (7). The lower end of the inner well pipe (9) is flush with the lower end of the rubber sleeve (10) and is sealed to the bottom of the rubber sleeve (10). The inner well pipe (9) is connected to the lower screen pipe (12). The aeration pipe (1) passes through the inner well pipe (9). The upper end of the aeration pipe (1) passes through the upper screen pipe (7). The flange (2) is fixed together with the upper half of the upper flange (2). The lower end of the aeration pipe (1) is located in the lower screen pipe (12). The lower end of the aeration pipe (1) is connected to the aeration head (13). The aeration pipe (1) at the top of the inner well pipe (9) is fitted with a rubber plug (8). When the support (4) is located in the middle of the upper flange (2), the upper half of the upper flange (2) is supported and lifted. The upper half of the flange (2) drives the aeration pipe (1) to move upward. The aeration pipe (1) drives the rubber plug (8) to disengage from the top of the inner well pipe (9). After the support (4) is removed, the upper and lower parts of the upper flange (2) are bolted together. The aeration pipe (1) moves down with the upper part of the upper flange (2). The aeration pipe (1) drives the rubber plug (8) to seal the top of the inner well pipe (9). The aeration pipe (1) above the rubber plug (8) is fitted with a fixed water-blocking baffle (5). The water-blocking baffle (5) can prevent water from overflowing from the top of the outer well pipe (6). The outer well pipe (6) below the water-blocking baffle (5) is equipped with and connected to a tail gas pipe (3).

2. The device for a pneumatically driven dual-mode in-situ groundwater remediation well according to claim 1, characterized in that: The bracket (4) is arc-shaped.

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