Micro-nano bubble liquid targeted injection system suitable for in-situ remediation of contaminated groundwater

Abstract

The present application relates to a kind of micro-nano bubble liquid targeting injection system suitable for contaminated groundwater in-situ remediation, injection subsystem is prepared with micro-nano bubble liquid preparation mechanism Micro-nano bubble liquid, micro-nano bubble liquid is injected into injection well, with targeting injection device Micro-nano bubble liquid is targeted to injection into injection well, injection site adjusting mechanism Micro-nano bubble liquid is targeted to injection into injection site;Extraction subsystem includes extraction well.The present application is directly acted on specified injection site with micro-nano bubble liquid, effectively constructs underground oxidation environment, promotes microbial action, the energy generated by the breakage of micro-nano bubble promotes the generation of hydroxyl radical in groundwater, oxidizes and degrades pollutants, and the toxicity of byproduct is low, clean and green;Promote the effective contact of micro-nano bubble liquid and pollutants and its mass transfer in formation, improve the action efficiency of micro-nano bubble liquid;Overcome the shortcoming that different depth soil layer character is not the same, save engineering cost;Real-time monitoring is injection control feedback information.

Description

Technical Field

[0001] This invention relates to the field of contaminated site remediation technology, and in particular to a micro-nano bubble liquid targeted injection system suitable for in-situ remediation of contaminated groundwater. Background Technology

[0002] Groundwater is an irreplaceable and vital resource for social development. However, groundwater resources are often affected by pollution to varying degrees, making the remediation and risk management of polluted groundwater an urgent matter. Unlike surface water pollution, groundwater, due to its location within underground aquifers, has relatively weak mobility and self-purification capabilities. Consequently, groundwater pollution is typically characterized by its hidden and irreversible nature, making remediation often quite challenging.

[0003] In-situ remediation technologies for contaminated groundwater offer advantages such as thorough remediation, treatment of a wide range of pollutants, and relatively low cost. Environmentally friendly in-situ aeration technology is a popular groundwater remediation technique, commonly used for treating contaminated groundwater. This technology primarily injects air into the saturation zone to promote the volatilization and degradation of pollutants or to create an aerobic environment that enhances the degradation and removal of pollutants by microorganisms. However, the application of existing in-situ aeration technology has the following drawbacks:

[0004] 1) Conventional bubbles are significantly affected by buoyancy, rise rapidly, and burst quickly on the liquid surface. They have poor stability in groundwater, which is not conducive to their mass transfer in groundwater, thus affecting their ability to construct an oxidizing environment and inhibit anaerobic bacteria.

[0005] 2) Due to the inconsistency of soil properties, pollutants are unevenly distributed in groundwater. Areas with better permeability are prone to forming dominant channels, resulting in unsatisfactory airflow distribution and affecting the implementation effect.

[0006] 3) The aeration position is determined only by the opening position of the injection tube, which makes directional aeration impossible and results in poor flexibility;

[0007] 4) The slit length of conventional flower tubes is too large, resulting in a smaller planar diffusion speed and a smaller radius of influence;

[0008] 5) In-situ aeration technology mainly promotes the volatilization or degradation of pollutants by creating an aerobic environment. However, due to the short residence time of conventional millimeter-sized bubbles in water, the degradation and removal effect on pollutants is limited.

[0009] 6) When the contamination layer is thick, layered injection requires the construction of injection cluster wells, which results in high construction costs.

[0010] These drawbacks affect the effectiveness of in-situ groundwater remediation and treatment, and restrict the development and application of in-situ aeration technology.

[0011] Patent No. CN 207435076 U provides a combined in-situ injection and in-situ aeration system. This system includes in-situ injection equipment and in-situ aeration equipment. It can simultaneously perform injection oxidation and aeration treatments, improving pollutant removal rates. However, it does not achieve precise injection of reagents or long-term effectiveness and stability of oxygen bubbles. Patent No. CN 110759490 A provides an ozone micro-nano aeration biological contact oxidation water purification method and device. It uses ozone as a gas source, generating micro-nano ozone through a micro-nano aerator for the removal of ammonia nitrogen, total phosphorus, COD, and algae from water. However, this invention does not specifically address how to inject micro-nano ozone into complex underground environments, and the system cannot be directly applied to in-situ groundwater remediation. Summary of the Invention

[0012] This invention solves the problems existing in the prior art and provides a micro-nano bubble liquid targeted injection system suitable for in-situ remediation of contaminated groundwater.

[0013] The technical solution adopted in this invention is a micro-nano bubble liquid targeted injection system suitable for in-situ remediation of contaminated groundwater, the system comprising an injection subsystem and an extraction subsystem configured in conjunction.

[0014] Any of the injection subsystems includes:

[0015] One or more micro / nano bubble liquid preparation mechanisms for preparing micro / nano bubble liquid;

[0016] One or more injection wells, located below the horizontal ground, are used for the injection of micro / nano bubble fluid;

[0017] One or more targeted injection devices, in conjunction with a micro / nano bubble liquid preparation mechanism and configured one-to-one with injection wells, are used to target and inject micro / nano bubble liquid into preset injection wells;

[0018] Each injection well is equipped with an injection position adjustment mechanism for targeted injection of micro-nano bubble liquid into the injection position within the injection well;

[0019] Each of the extraction subsystems includes one or more extraction wells located below the horizontal ground surface for the extraction of groundwater.

[0020] Preferably, the micro / nano bubble liquid preparation mechanism includes a gas supply unit, a water supply unit, and a preparation unit arranged in combination, wherein the gas supply unit and the water supply unit are connected to the preparation unit through an adjustment unit.

[0021] Preferably, the preparation unit is equipped with a storage unit, and the micro / nano bubble liquid is output through the storage unit.

[0022] Preferably, the targeted injection device includes a targeted injection tube, which is configured in conjunction with an injection well; the micro / nano bubble liquid preparation mechanism is spatially connected to the targeted injection tube via a high-pressure pump and an output conduit; and the targeted injection tube is equipped with an injection position adjustment mechanism.

[0023] Preferably, the output conduit is provided with a control component.

[0024] Preferably, the injection position adjustment mechanism includes positioning airbags arranged in pairs with the targeted injection device, and the positioning airbags are connected to an air compressor via air tubes.

[0025] Preferably, any of the positioning airbags is connected to an air compressor via an air tube.

[0026] Preferably, a plurality of directional airbag groups are provided between the two positioning airbags, and all the directional airbag groups are evenly distributed on the outer wall of the targeted injection device.

[0027] Preferably, the system further includes a monitoring well located below the horizontal ground level and sensors installed within it. The monitoring well is configured in conjunction with the injection subsystem and the extraction subsystem for online monitoring of groundwater indicators.

[0028] This invention relates to a micro / nano bubble liquid targeted injection system suitable for in-situ remediation of contaminated groundwater, comprising an injection subsystem and an extraction subsystem arranged in conjunction. In any injection subsystem, micro / nano bubble liquid is prepared by one or more micro / nano bubble liquid preparation mechanisms, and one or more injection wells located below the horizontal ground surface are used for injecting the micro / nano bubble liquid. One or more targeted injection devices, which cooperate with the micro / nano bubble liquid preparation mechanisms and are correspondingly located in the injection wells, are used to target and inject the micro / nano bubble liquid into the preset injection wells. Each injection well is equipped with an injection position adjustment mechanism for targeting the injection of the micro / nano bubble liquid to the injection position within the injection well. Any extraction subsystem includes one or more extraction wells located below the horizontal ground surface for extracting groundwater.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) Compared with conventional aeration, micro-nano bubble liquid is directly applied to the designated injection site. Micro-nano bubbles have the characteristics of small particle size, large specific surface area and good mass transfer. They have a long residence time in groundwater, which can effectively construct the underground oxidation environment and promote the action of microorganisms. Moreover, the energy generated by the rupture of micro-nano bubbles can promote the generation of hydroxyl radicals in groundwater and directly oxidize and degrade pollutants. Using micro-nano bubble liquid as a reaction material makes the byproducts in the pollutant degradation process less toxic and the reaction process cleaner and greener.

[0031] (2) This system improves the effective contact between micro-nano bubble liquid and pollutants and its mass transfer in the formation by constructing a micro-nano bubble liquid remediation system and process method of "layered injection and pulse extraction coupling and multi-round intermittent operation", which overcomes the problem of pollutant rebound in groundwater and has high remediation efficiency.

[0032] (3) During the implementation of this system, the layered injection function can be realized without the need to construct cluster wells or layered wells, thus saving engineering costs;

[0033] (4) This system injects micro-nano bubble liquid by matching a targeted injection device with stable injection pressure, which is more conducive to injecting micro-nano bubble liquid at different pressures, especially in low-permeability clay layers, silty clay layers or aquifers with deep burial depth.

[0034] (5) The injection position adjustment mechanism ensures the selectivity and sealing of the injection section, promotes the migration and diffusion of micro-nano bubble liquid, enhances the effect of micro-nano bubbles on pollutants in groundwater, overcomes the disadvantage of different soil properties at different depths, and achieves targeted injection.

[0035] (6) While performing precise injection in the targeted injection device and injection well, a reasonable opening position can be set for the perforated pipe of the extraction well, and negative pressure extraction can be used to further enhance the mass transfer of micro-nano bubbles in groundwater and improve the efficiency of micro-nano bubble liquid.

[0036] (7) The system is configured with monitoring wells and sensors (probes) as needed, which can monitor the redox environment in groundwater in real time and provide feedback information for the injection control of micro-nano bubble liquid. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the structure of the present invention;

[0038] Figure 2 This is a schematic diagram of the micro / nano bubble liquid preparation mechanism in this invention, with the arrow indicating the output direction;

[0039] Figure 3 A schematic diagram of the structure of the targeted injection tube of the present invention, which simultaneously provides a positioning airbag and a directional airbag assembly;

[0040] Figure 4 The figures shown are numerical simulation results under continuous injection conditions in the embodiments of the present invention, wherein (a) is the result of injection + extraction for 1 hour, (b) is the result of injection + extraction for 1 day, (c) is the result of injection + extraction for 2 days, and (d) is the result of injection + extraction for 3 days. Detailed Implementation

[0041] The present invention will be further described in detail below with reference to embodiments, but the scope of protection of the present invention is not limited thereto.

[0042] This invention relates to a micro / nano bubble liquid targeted injection system suitable for in-situ remediation of contaminated groundwater, the system comprising an injection subsystem and an extraction subsystem configured in conjunction;

[0043] Any of the injection subsystems includes:

[0044] One or more micro / nano bubble liquid preparation mechanisms 1 are used to prepare micro / nano bubble liquid;

[0045] One or more injection wells 2, located below the horizontal ground, are used for the injection of micro-nano bubble liquid;

[0046] One or more targeted injection devices, in conjunction with the micro / nano bubble liquid preparation mechanism and configured one-to-one with the injection wells 2, are used to target and inject the micro / nano bubble liquid into the preset injection wells 2;

[0047] Each injection well 2 is equipped with an injection position adjustment mechanism for targeted injection of micro-nano bubble liquid into the injection position within the injection well 2;

[0048] Each of the extraction subsystems includes one or more extraction wells 3, located below the horizontal ground surface, for the extraction of groundwater.

[0049] In this invention, the technical process involves constructing a site conceptual model based on the distribution of pollutants and hydrogeological information within the site. Based on indoor and field tests of micro-nano bubble liquid, a micro-nano bubble liquid remediation system is constructed, employing a reaction mechanism of "in-situ degradation, volatilization, and extraction removal" coupled with "layered injection and pulse extraction coupling and multi-round intermittent operation." The removal rate of target pollutants in actual groundwater and the required amount of micro-nano bubble liquid under this remediation system are analyzed and calculated. Then, relying on an injection-extraction-monitoring well group system, and through the coordination of a targeted injection device and an injection position adjustment mechanism, the micro-nano bubble liquid is specifically injected into the contaminated strata via injection wells to degrade and remove target pollutants from the groundwater.

[0050] In this invention, the injection subsystem and the extraction subsystem work together. The injection subsystem is used to inject micro-nano bubble liquid into the target area, so that it can act precisely on the contaminated stratum that needs to be remediated. The extraction subsystem is used to extract groundwater, enhance the mass transfer of the micro-nano bubble liquid so that it can better contact the contaminated groundwater in the stratum, and further remove pollutants from the groundwater through extraction coupling, thereby achieving effective removal of target pollutants from the groundwater.

[0051] In this invention, it is obvious that the injection well 2 and the extraction well 3 are perforated pipes, which can allow liquid to pass through the well wall. However, precisely because they are perforated pipes, the injection position needs to be optimized with an injection position adjustment mechanism and a targeted injection device to achieve the purpose of injecting micro-nano bubble liquid into the required contaminated formation and degrading and removing pollutants in the groundwater.

[0052] The micro / nano bubble liquid preparation mechanism 1 includes a gas supply unit, a water supply unit, and a preparation unit arranged in a coordinated manner. The gas supply unit and the water supply unit are connected to the preparation unit through an adjustment unit.

[0053] The preparation unit is equipped with a storage unit, through which the micro-nano bubble liquid is output.

[0054] In this invention, the micro-nano bubble liquid preparation mechanism 1 can also be regarded as a micro-nano bubble liquid generating device. It outputs gas and liquid to the preparation unit through the cooperation of the gas supply unit, the water supply unit and the adjustment unit, respectively, to realize the preparation of micro-nano bubble liquid. The adjustment unit is generally a control valve structure, the gas supply unit is generally oxygen, and the water supply unit is generally external water. The preparation operation is completed in the preparation unit.

[0055] In this invention, since the interior of the micro-nano bubble liquid preparation mechanism 1 is a closed structure, the prepared micro-nano bubble liquid can be stored in the storage unit and output from the storage unit without affecting the operation of the preparation unit, thus realizing the separation of micro-nano bubble liquid preparation and output.

[0056] The targeted injection device includes a targeted injection tube 4, which is configured in conjunction with the injection well 2; the micro-nano bubble liquid preparation mechanism 1 is spatially connected to the targeted injection tube 4 through a high-pressure pump 5 and an output conduit 6; the targeted injection tube 4 is equipped with an injection position adjustment mechanism.

[0057] The output conduit 6 is equipped with a control component.

[0058] The injection position adjustment mechanism includes a positioning airbag 7 arranged in pairs with the targeted injection device, and the positioning airbag 7 is connected to the air compressor 9 through an air tube 8.

[0059] In this invention, the targeted injection device achieves targeted injection by inserting the targeted injection tube 4 into the injection well 2 or adjusting the position of the injection position adjustment mechanism. The micro-nano bubble liquid preparation mechanism 1 is spatially connected to the targeted injection tube 4 through the high-pressure pump 5 and the output conduit 6. Specifically, the micro-nano bubble liquid in the mechanism is pressurized by the high-pressure pump 5 and output to the targeted injection tube 4 through the output conduit 6. In practical applications, different output states of the micro-nano bubble liquid can be achieved by adjusting the pressure of the high-pressure pump 5.

[0060] In this invention, the output conduit 6 is equipped with control components, including but not limited to flow meter 10, solenoid valve 11, etc., which can be used to adjust the output through remote control or manual on-site control.

[0061] In this invention, the injection position adjustment mechanism includes a pair of positioning airbags 7 that are arranged in conjunction with the targeted injection device. Specifically, it is at least one pair of positioning airbags 7 that are sleeved outside the targeted injection tube 4. The positioning airbags 7 are connected to the air compressor 9 through the air tube 8, which can realize the inflation or depressurization of their inner cavity. In this way, when inflated, the positioning airbags 7 fill the space between the targeted injection tube 4 and the injection well 2, complete the local position sealing, and finally achieve the purpose of limiting the injection area by the position of the pair of positioning airbags 7 and limiting the injection range by the distance between the pair of positioning airbags 7.

[0062] In this invention, in order to facilitate control and implementation of different injection scenarios, each positioning airbag 7 is connected to an air compressor 9 through an air tube 8, and a barometer 12 is used to obtain the pressure data inside the air tube 8, so as to facilitate better control.

[0063] In this invention, several directional airbag groups are provided between the two positioning airbags 7, and all directional airbag groups are evenly distributed on the outer wall of the targeting injection tube 4.

[0064] In this invention, given that the limitations of the injection area and injection range can already be achieved, the injection range area and range can be further subdivided through the directional airbag assembly;

[0065] Specifically, 2 to 8 independent airbags 71 are set between the two positioning airbags 7. The 2 to 8 independent airbags 71 can evenly divide the outer periphery of the targeting injection tube 4 between the two positioning airbags 7, such as setting 2 to 8 columns vertically or 2 to 8 rows horizontally. Each independent airbag 71 has evenly distributed gaps. By controlling the inflation volume of the independent airbags 71, the gaps can be completely sealed or partially opened for injection of drugs, thereby achieving targeted injection of drugs.

[0066] The system also includes a monitoring well 13 located below the horizontal ground and a sensor 14 installed inside it. The monitoring well 13 is configured in conjunction with the injection subsystem and the extraction subsystem to monitor groundwater indicators online.

[0067] In this invention, injection well 2 is used in conjunction with a targeted injection device to inject micro-nano bubble liquid, and extraction well 3 is used in conjunction with an extraction pump (not shown in the figure) to extract groundwater from the site, thereby improving the mass transfer and diffusion effect of the injected micro-nano bubble liquid. In order to better achieve the expected remediation, monitoring well 13 can also be set on the injection subsystem and extraction subsystem side, generally on the injection well 2 and extraction well 3 side, in conjunction with online monitoring sensor 14 to monitor indicators such as DO and ORP in groundwater in real time, and to provide feedback on the migration and diffusion effect of micro-nano bubble liquid.

[0068] In this invention, the sensor 14 includes, but is not limited to, an ORP and DO online monitoring sensor (probe) 14.

[0069] In this invention, the control method of the system includes the following steps:

[0070] Step 1: Based on the survey information, clarify the distribution information of pollutants and hydrogeological information of the site, construct a conceptual model of the site, and conduct simulation analysis on the migration path of polluted groundwater;

[0071] Step 2: Based on the survey information, analyze and calculate the total mass of target pollutants that need to be degraded and removed from the groundwater of each aquifer within the remediation area to achieve the remediation target;

[0072] Define the contaminated area A (m²) of the remediation and treatment zone. 2 The following parameters are considered within the remediation area: the number of strata with different characteristics n (positive integers from 1 to N), the corresponding thickness h (m) of different strata, the porosity θ of different strata, and the initial concentration P of the target pollutant. I (mg / L), target pollutant remediation target P T (mg / L);

[0073] Based on the above information, the total mass of pollutants that need to be degraded and removed when the concentration of the target pollutants in the groundwater of each aquifer reaches the remediation target can be calculated.

[0074]

[0075] In the formula, h n θ is the thickness of the nth stratum; n Let A be the porosity of the nth stratum. n P represents the area of ​​the contaminated region in the nth stratum. nI P nT These represent the initial concentration and target concentration of the target pollutant in the nth formation, respectively.

[0076] Step 3: Conduct indoor and field tests on micro-nano bubble liquid to construct a micro-nano bubble liquid repair system and process method with "layered injection and pulse extraction coupling and multi-round intermittent operation" as the reaction mechanism of "in-situ degradation, volatilization and extraction removal".

[0077] In this invention, the established micro / nano bubble liquid remediation system and process, characterized by "layered injection coupled with pulse extraction and multi-round intermittent operation," allows micro / nano bubbles to remain in groundwater for a longer period, effectively creating an underground oxidizing environment, promoting microbial activity, and generating highly oxidizing hydroxyl radicals in the groundwater. Using micro / nano bubble liquid as the core, layered injection enables precise delivery of the liquid to contaminated formations, improving remediation efficiency. Simultaneously with the injection, extraction coupling enhances the mass transfer of the injected liquid within the formation and extracts a certain amount of contaminated groundwater, reducing the existing pollution load. Through multiple rounds of intermittent operation, pollutants in the groundwater are gradually degraded and removed, effectively overcoming the problem of pollutant rebound.

[0078] Specifically, step 3 includes the following steps:

[0079] Step 3.1: Conduct indoor and field tests of micro-nano bubble liquid. First, determine the removal rate of target pollutants in groundwater per unit volume of micro-nano bubble liquid. Second, determine the removal rate of target pollutants in groundwater per unit volume of micro-nano bubble liquid under the synergistic effect of volatilization. Finally, determine the removal rate of target pollutants in groundwater per unit volume of micro-nano bubble liquid under the synergistic effect of extraction and volatilization.

[0080] Step 3.2: Construct a micro-nano bubble liquid remediation system with "layered injection and pulse extraction coupling and multi-round intermittent operation" as the reaction mechanism of "in-situ degradation, volatilization and extraction removal". Clarify key process parameters such as injection flow rate and extraction flow rate, and further optimize the well spacing design by combining numerical simulation. Finally, determine the removal rate of target pollutants in groundwater in actual formations by unit volume micro-nano bubble liquid under the optimal process parameters.

[0081] Step 4: Based on the removal rate η (mg / L) of the target pollutant in the actual formation groundwater per unit volume of micro / nano bubble liquid under the optimal process parameters, and combined with the total mass of the target pollutants to be removed, calculate the injection dosage of the micro / nano bubble liquid. And prepare micro-nano bubble liquid rich in micro-nano oxygen bubbles;

[0082] Step 5: For the polluted area, based on the constructed well group system, micro-nano bubble liquid is injected into different aquifers intermittently in multiple rounds using a targeted injection device in a staggered batch and zoned manner on the plane and a layered and segmented manner on the vertical plane. The mass transfer and coupling removal of pollutants by the micro-nano bubble liquid are enhanced by extraction. The extraction flow rate is flexibly adjusted according to the water level fluctuation.

[0083] Step 6: During the injection-extraction process, water samples from the current aquifer are collected and analyzed to monitor indicators such as COD, ammonia nitrogen, DO, and ORP. Based on the monitoring results, subsequent processing is carried out.

[0084] The present invention provides an embodiment:

[0085] An informal landfill has suffered a leak of leachate due to damage to its bottom impermeable membrane, which is polluting the surrounding groundwater.

[0086] According to the survey information, the main pollutant in groundwater is COD. mn The area of ​​the pollution plume is 500m² 2 The strata contain two aquifers: an upper aquifer of miscellaneous fill soil with an average thickness of 5m, and a lower aquifer of silty fine sand with an average thickness of 7m. The porosity of the miscellaneous fill soil is 0.5, and the porosity of the silty fine sand is 0.4. The COD in the miscellaneous fill soil is... mn The initial concentration was 150 mg / L, and the COD in the fine sand layer was... mn The initial concentration was 90 mg / L;

[0087] COD mn The target value for repair is 10 mg / L;

[0088] Based on the above information, the COD in the groundwater of each aquifer can be calculated. mn When the remediation goal is achieved, it is necessary to degrade and remove COD from the impurity fill layer and the fine sand layer. mn The total mass (mg) is shown in the table below:

[0089] Table 1. CODmn Degradation and Removal Amount in Different Aquifers

[0090] Serial Number aquifer <![CDATA[COD mn Degradation removal amount (mg) 1 Miscellaneous fill 175000000 2 Fine sand layer 112000000

[0091] In this invention, the micro-nano aeration technology can use air, oxygen, ozone, etc. as gas sources to produce micro-nano bubbles. In this embodiment, oxygen is used as the gas source.

[0092] The millimeter-sized air bubbles generated by conventional aeration rise and dissipate quickly in water due to buoyancy. In contrast, oxygen micro-nano bubbles have even smaller particle sizes and decay more slowly in water, resulting in longer residence time and slower rising speed. Using oxygen as the gas source, the generated micro-nano bubble liquid can effectively increase the DO and ORP values ​​in groundwater, with peak values ​​of 20.4 mg / L and 144.8 mv, respectively. Compared with conventional aeration, the peak DO concentration increased by 204%, and the peak ORP concentration increased by 46.3%.

[0093] Indoor and field experiments were conducted on micro / nano bubble fluid to establish a micro / nano bubble fluid remediation system based on the reaction mechanism of "in-situ degradation, volatilization, and extraction removal," which involves "layered injection coupled with pulse extraction and multiple rounds of intermittent operation." The injection flow rate was determined to be 1 m³ / s. 3 / h, extraction flow rate is 1m 3 / h.

[0094] Based on the groundwater numerical simulation software GMS, with an injection flow rate of 1 m³ / s... 3 / h, extraction flow rate 1m 3 / h, continuous intermittent injection-extraction for 3 days, with 12 hours per day as the working condition. The model results show that with a COD reduction of 40% as the control boundary, the influence radius of the deep well injection combined with extraction process can reach 4.3m, so the injection well spacing is designed to be 7m.

[0095] like Figure 4 The figure shown is a numerical simulation result under continuous injection conditions in this embodiment.

[0096] Based on the above process parameters, the final removal rate of target pollutants in groundwater per unit volume of micro-nano bubble liquid was determined to be 55 mg / L. Therefore, the COD in complex fill soil and silty sand aquifers can be calculated. mn The required micro / nano bubble liquid volume is 2536 m³. 3 and 1623m 3 This leads to the preparation of micro / nano bubble liquids.

[0097] Based on the constructed micro / nano bubble fluid remediation system and process method of "layered injection coupled with pulse extraction and multi-round intermittent operation", the combination of technical process parameters such as injection well spacing, injection flow rate, injection time, and injection rounds is clearly defined. Using a zoned, layered, and multi-well synchronous extraction-injection implementation method, micro / nano bubble fluid is injected into the target aquifer through a micro / nano bubble fluid targeted injection system. In this embodiment, for injection wells with an inner diameter of 53mm, to effectively ensure sealing and achieve targeted injection, the positioning airbag of the targeted injection device has a diameter of 45mm before inflation and can reach 60mm after inflation.

[0098] After 150 days of operation of the injection-extraction method, samples of the remediated groundwater were taken and tested. The results showed that the COD in the remediated area was... mn The concentrations were all below 10 mg / L.

Claims

1. A micro / nano bubble liquid targeted injection system suitable for in-situ remediation of contaminated groundwater, characterized in that: The system includes an injection subsystem and an extraction subsystem configured in conjunction; Any of the injection subsystems includes: One or more micro / nano bubble liquid preparation mechanisms for preparing micro / nano bubble liquid; One or more injection wells, located below the horizontal ground, are used for the injection of micro / nano bubble fluid; One or more targeted injection devices, in conjunction with a micro / nano bubble liquid preparation mechanism and configured one-to-one with injection wells, are used to target and inject micro / nano bubble liquid into preset injection wells; Each injection well is equipped with an injection position adjustment mechanism for targeted injection of micro-nano bubble liquid into the injection position within the injection well. The injection position adjustment mechanism includes positioning airbags arranged in pairs to cooperate with the targeted injection device. The positioning airbags are connected to an air compressor via air pipes. Several directional airbag groups are arranged between the two positioning airbags, and all the directional airbag groups are evenly distributed on the outer wall of the targeted injection device. The micro-nano bubble liquid is injected into different aquifers intermittently in multiple rounds using a staggered batch and section injection method on the plane and a layered and segmented injection method on the vertical plane. Each of the extraction subsystems includes one or more extraction wells located below the horizontal ground surface for the extraction of groundwater.

2. The micro / nano bubble liquid targeted injection system for in-situ remediation of contaminated groundwater according to claim 1, characterized in that: The micro / nano bubble liquid preparation mechanism includes a gas supply unit, a water supply unit, and a preparation unit arranged in a coordinated manner. The gas supply unit and the water supply unit are connected to the preparation unit through an adjustment unit.

3. The micro / nano bubble liquid targeted injection system for in-situ remediation of contaminated groundwater according to claim 2, characterized in that: The preparation unit is equipped with a storage unit, through which the micro-nano bubble liquid is output.

4. The micro / nano bubble liquid targeted injection system for in-situ remediation of contaminated groundwater according to claim 1, characterized in that: The targeted injection device includes a targeted injection tube, which is configured in conjunction with an injection well; the micro / nano bubble liquid preparation mechanism is spatially connected to the targeted injection tube via a high-pressure pump and an output conduit; and the targeted injection tube is equipped with an injection position adjustment mechanism.

5. The micro / nano bubble liquid targeted injection system for in-situ remediation of contaminated groundwater according to claim 4, characterized in that: The output conduit is equipped with a control component.

6. The micro / nano bubble liquid targeted injection system for in-situ remediation of contaminated groundwater according to claim 1, characterized in that: Each of the aforementioned positioning airbags is connected to an air compressor via an air tube.

7. The micro / nano bubble liquid targeted injection system for in-situ remediation of contaminated groundwater according to claim 1, characterized in that: The system also includes a monitoring well located below the horizontal ground level and sensors installed within it. The monitoring well is configured in conjunction with the injection subsystem and the extraction subsystem to monitor groundwater indicators online.

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