Underground water organic pollution remediation system and method based on ultrasonic waves

Abstract

The invention discloses a groundwater organic pollution remediation system and method based on ultrasonic waves, and belongs to the technical field of groundwater organic pollution remediation. The groundwater organic pollution remediation system comprises an injection well system and a monitoring well system which are arranged in a water pollution area; the injection well system comprises an injection well and a probe ultrasonic mechanism, the injection well is embedded into soil of a water pollution area, the probe ultrasonic mechanism is arranged in the injection well, and a medicament pipe is further arranged on the probe ultrasonic mechanism; the remediation agent is added into the injection well through an agent pipe on the probe ultrasonic mechanism to be mixed with the underground water to react, so that organic pollutants in the underground water are degraded; the monitoring well system comprises a monitoring well, a water quality monitor and a multifunctional water quality monitoring probe, the monitoring well is correspondingly arranged on one side of the injection well, the system is simple in structure and convenient to use, efficient transmission of a remediation agent in heterogeneous underground water is achieved by means of catalytic oxide and a probe ultrasonic mechanism, and the remediation efficiency is improved. Therefore, the removal efficiency of the organic pollutants is obviously improved.

Description

Technical Field

[0001] The present invention relates to the remediation of groundwater organic pollution, and in particular to an ultrasonic-based groundwater organic pollution remediation system and method, belonging to the technical field of soil and groundwater organic pollution remediation. Background Art

[0002] Remediation technology for contaminated groundwater at sites has gradually shifted from ex situ extraction to in situ disposal (Luo Yongming, Environmental Monitoring Management and Technology, 2011, 23, 1-6; Stroo HF, Environ. Sci. Technol., 2003, 37, 224-230; Tsitonaki A., Crit. Rev. Environ. Sci. Technol., 2010, 40, 55-91; Watts RJ, Waste Management, 2006, 10, 2-9; 21). Statistics were compiled of the technologies and proportions used to remediate groundwater contaminated sites in the United States from 1986 to 2008 (Pu M., Environ. Eng., 2017, 35, 6-10). Results show that between 1986 and 2008, the proportion of groundwater remediation using extraction and treatment decreased from 68% to 17%, while the proportion of groundwater remediation using in-situ remediation increased from 0% to 17% (Zhang S., Water Res., 2017, 119, 114-125). The adoption of in-situ remediation has significantly increased. In the U.S. Superfund program, 702 groundwater remediation decision documents were made between 2005 and 2008 (US EPA, Superfund Remedy Report, 13th Edition, 2010). Of these, 328 involved risk management and control systems and long-term monitoring, 140 involved monitoring natural attenuation, 119 involved in-situ remediation, and only 98 involved extraction and treatment (USEPA, Superfund Remedy Report, 13th Edition, 2010; Yin Y., Jiangxi Chem. Ind., 2013, 3, 28-31). Among various in situ remediation technologies, in situ microbial remediation and in situ chemical treatment technologies are the main ones (Kenneth C., Sci. Total Environ., 2024, 918, 170600; Stroo HF, Environ. Sci. Technol., 2012, 46, 6438-6447).

[0003] Advanced oxidation (AO) is currently a key technology for in-situ chemical treatment of groundwater (Wang JL, Crit. Rev. Environ. Sci. Technol., 2012, 42, 251-325; Wang JL, Radiat. Phys. Chem., 2016, 125, 56-64). Among these, the most representative in-situ chemical treatment technologies are Fenton and persulfate oxidation (Ao X., Chem. Eng. J., 2017, 313, 629-637; Ji Y., Chem. Eng. J., 2015, 263, 45-54). The Fenton reaction strongly depends on the acidic conditions of the water body. The most hydroxyl radicals are produced at around pH 3, and the reaction efficiency is the highest (Liang C., Water Res., 2008, 42, 4091-4100; von Sonntag C., Water Sci. Technol., 2008, 58 1015-1021). Persulfate / permonosulfate can be activated to produce strong oxidizing sulfate radicals through various methods, such as transition metal activation, thermal activation, and alkali activation (Johnson RL, Environ. Sci. Technol., 2008, 42, 9350-9356; Khan S., Chem. Eng. J., 2017, 318, 135-142; Liang CJ, Soil Sediment Contam. Int. J. 2003, 12, 207-228; Wang JL, Chem. Eng. J., 2018, 334, 1502-1517; Yang SY, J. Hazard. Mater., 2010, 179, 552-558). These advanced oxidation technologies are generally applicable in homogeneous surface water environments. These chemicals are typically injected into wells for in situ groundwater remediation (Tsitonaki A., Crit. Rev. Environ. Sci. Technol., 2010, 40, 55-91; Wei Z., Environ. Sci. Technol., 2017, 51, 3410-3417). However, for groundwater environments saturated with sediment and poor permeability, the low spatial mass transfer efficiency and high energy resource consumption greatly limit the practical application of these technologies in in situ groundwater remediation.

[0004] Patent CN212076722U "A system for ultrasonic combined electro-Fenton oxidation remediation of organically contaminated groundwater" is equipped with an ultrasonic vibration head at the bottom of the reaction tower to degrade organic matter in the water body by means of oscillation. The advantages of this design are reduced energy consumption, accelerated degradation rate, and ensured the uniformity of the water degradation process. At the same time, the vibration generated by the ultrasonic vibration head can effectively remove the gas generated during the reaction process, so that the cathode plate and the anode plate can be ionized normally. However, although the device uses an ultrasonic vibration head, its main purpose is to remove the gas generated in the reaction, and it is only suitable for ex situ groundwater treatment, and can only work on ex situ groundwater that has been precipitated, so the vibration requirements are relatively low. When faced with a groundwater environment saturated with sediment and poor permeability, due to the low spatial mass transfer efficiency and high energy resource consumption, the repair system is difficult to meet actual use needs, and its vibration intensity and method need to be further improved and optimized.

[0005] Therefore, developing an ultrasonic-based groundwater organic pollution remediation system and method that can overcome the above defects has become a technical problem that needs to be solved urgently by those skilled in the art. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the existing technology and provide an ultrasonic-based groundwater organic pollution remediation system and method. The system has a simple structure and is easy to use. By using the remediation agent and the probe ultrasonic mechanism, the efficient transmission of the remediation agent in heterogeneous groundwater is achieved, thereby significantly improving the removal efficiency of organic pollutants.

[0007] In order to solve the above technical problems, the present invention provides an ultrasonic-based groundwater organic pollution remediation system, comprising an injection well system and a monitoring well system set up in the water pollution area;

[0008] The injection well system includes an injection well and a probe ultrasonic mechanism. The injection well is embedded in the soil of the water contaminated area. The probe ultrasonic mechanism is set in the injection well. The probe ultrasonic mechanism is also provided with a reagent pipe. The remediation reagent is added to the injection well through the reagent pipe on the probe ultrasonic mechanism to mix and react with the groundwater. The probe ultrasonic mechanism accelerates the mixing and reaction of the remediation reagent and groundwater to complete the degradation of organic pollutants in the groundwater.

[0009] The monitoring well system includes a monitoring well, a water quality monitor and a multifunctional water quality monitoring probe. The multifunctional water quality monitoring probe is hung in the monitoring well and is electrically connected to the water quality monitor. A monitoring well is provided on one side of the injection well. The concentration of organic pollutants in the groundwater is measured by sampling from the monitoring well adjacent to the injection well.

[0010] The technical solution further defined in the present invention is:

[0011] Furthermore, in the aforementioned ultrasonic-based groundwater organic pollution remediation system, the injection well is composed of an injection well pipe, a well cover, a wellhead sleeve, a pipe plug and a filling layer. The upper end of the injection well pipe is connected to the wellhead sleeve, and the wellhead sleeve is rotatably connected to the well cover by an internal thread. The wellhead sleeve is filled with concrete to maintain stability. The lower end of the injection well pipe is sealed by a pipe plug. The injection well pipe is composed of a straight pipe section and a screen pipe section from top to bottom. The filling layer is arranged in a circumferential direction around the injection well pipe. The filling layer includes a bentonite and cement mixed layer, a granular bentonite layer and a quartz sand layer from top to bottom, wherein:

[0012] Preferably, the bentonite and cement mixed layer has a mass ratio of bentonite to cement of 1:1; the bentonite particles in the granular bentonite layer have a particle size of 0.5-1.5 mm; and the quartz sand in the quartz sand layer has a particle size of 0.5-1 mm.

[0013] The injection well pipe and the screen pipe section in the injection well pipe are made of PVC, and the wellhead sleeve is made of concrete.

[0014] Floor tiles are arranged around the drilling hole to facilitate the placement of power supply, dosing mechanism and elevator, etc., to ensure the setting of working equipment and the normal operation of work.

[0015] Technical effect: The present invention inserts the injection well pipe into the drill hole, and sets a filling layer of quartz sand, a filter material, around the injection well pipe to prevent soil particles from entering the injection well pipe. Cement or bentonite is used to seal the area around the well pipe, which can also ensure the stability of the well pipe and prevent the backflow of pollutants, and efficiently degrade organic matter in groundwater.

[0016] In the aforementioned ultrasonic-based groundwater organic pollution remediation system, a plurality of reagent tanks are provided at the injection wellhead for storing remediation reagents, and the reagent tanks are connected to the reagent pipes through injection pumps.

[0017] In the aforementioned ultrasonic-based groundwater organic pollution remediation system, a pressure sensor and a flow meter are respectively provided on the pipeline between the reagent tank and the injection pump.

[0018] Technical effect: The present invention is provided with a dosing mechanism, which is convenient for controlling the speed, flow rate and pressure of dosing. On the one hand, it can avoid the premature reaction of the two agents. In addition, the dosage of the agents can be adjusted according to the concentration to ensure better progress of the work. It is also convenient for manual control, improving efficiency and convenience of use.

[0019] In the aforementioned ultrasonic-based groundwater organic pollution remediation system, a pressure sensor and a flow meter are respectively provided on the pipeline between the reagent tank and the injection pump.

[0020] Technical effect: The repair agent solution is injected separately, and the pressure, flow and time during the injection process are recorded. Pressure sensors and flow meters are used to monitor parameter changes in the injection process in real time to ensure the stability and safety of the injection process.

[0021] In the aforementioned ultrasonic-based groundwater organic pollution remediation system, the flow rate of the injection pump during injection is controlled at 0.5-2 L / min, and the pressure of the injection pump is 0.05-0.2 MPa.

[0022] Technical effect: The present invention strictly controls flow and pressure, and the repair agent solution is pressurized and injected through the injection well, and avoids premature reaction between the two.

[0023] In the above-mentioned ultrasonic-based groundwater organic pollution remediation system, the probe ultrasonic mechanism includes a power supply, an horn, a probe, a transducer, a traction rope and a lift. The power supply is preferably high-frequency alternating current. The power supply is arranged at the injection wellhead to provide power for the probe ultrasonic mechanism. The horn is a hollow cylindrical structure with a receiving cavity in the middle. The transducer is embedded in the receiving cavity. The power supply is connected to the transducer through an electric wire. A plurality of threaded holes are provided on the surface along the circumference of the horn. The probe is detachably arranged on the outer surface of the horn through a thread. The horn is sealed by existing technology to prevent water from ingress and affecting the normal progress of the work. The lift is arranged at the injection wellhead. One end of the traction rope is wound around the lift, and the other end is connected to the horn to drive the vertical lifting of the probe.

[0024] The elevator preferably adopts an electric winch design, which drives the winch to rotate through the motor, so that the traction rope is wrapped around the winch, thereby generating tension to lift or lower the multi-directional matrix probe ultrasonic mechanism; the transducer converts the high-frequency electrical signal into mechanical vibration energy, and the amplitude transformer further amplifies the vibration amplitude generated by the transducer and concentrates the energy. The probe transmits the vibration mechanical energy to the groundwater liquid medium to generate ultrasonic waves. When the ultrasonic waves propagate in the groundwater, cavitation bubbles are formed by alternating positive and negative pressures, thereby accelerating the mixing and reaction of the agent and the pollutant.

[0025] Technical effect: The present invention adopts a probe ultrasonic mechanism. On the one hand, the cavitation effect of ultrasound enhances the activation performance of the agent, and on the other hand, it can accelerate the mixing and reaction of the repair agent and the pollutants. The multi-directional matrix probe ultrasonic mechanism is placed in the injection well pipe and connected to the elevator at the wellhead through a traction rope to realize the vertical lifting of the ultrasonic mechanism, thereby expanding the diffusion rate and diffusion range of the agent.

[0026] In the aforementioned ultrasonic-based groundwater organic pollution remediation system, the probes are arranged in a matrix pattern on the outer surface of the amplitude transformer.

[0027] Technical effect: The present invention adopts a matrix layout to improve the radiation range of the ultrasonic system, so that the probes are distributed 360 degrees around the outer surface of the amplitude transformer, ensuring that the mechanical vibration energy emitted by the ultrasonic mechanism can be received in all directions.

[0028] The present invention also designs a method for repairing organic pollution in groundwater based on ultrasound, which specifically includes the following steps:

[0029] (1) Based on the site survey results, the injection well location is selected, and the injection well is laid out by direct drilling using a drilling rig. The injection well pipe is inserted into the drilled hole, and the injection well pipe is filled with material to form a filling layer;

[0030] (2) Multiple reagent tanks and injection pumps are installed at the injection wellhead as needed. One end of the reagent tube is connected to the reagent tank through the injection pump, and the other end is installed on the probe and extends into the injection well pipe. The hoist suspends the horn equipped with the probe in the injection well pipe through a traction rope;

[0031] (3) Drill holes around the injection well and downstream of the contaminated area to ensure that the monitoring well can cover the target contaminated area, insert the monitoring well pipe into the drill hole, and fill the surrounding area of the monitoring well pipe with material to form a filling layer;

[0032] (4) A water quality monitor is installed at the monitoring wellhead, and a multifunctional water quality monitoring probe is placed in the monitoring well through an electric wire;

[0033] (5) Prepare the repair agent solution and fill it into the corresponding agent tank;

[0034] (6) Connect the repair agent solution to the injection pump, ensure that the system is leak-free, start the injection pump, and inject the repair agent into the injection well pipe separately according to the predetermined injection pressure and flow rate. Use the pressure sensor and flow meter on the pipeline to monitor the parameter changes during the injection process in real time, and record the pressure, flow rate and time during the injection process; Use the pressure sensor and flow meter on the pipeline to monitor the parameter changes during the injection process in real time to ensure the stability and safety of the injection process;

[0035] (7) After the reagent is injected, the multi-directional matrix probe ultrasonic mechanism is activated to accelerate the diffusion of the reagent in the groundwater layer, and to perform mixing and reaction to degrade the organic pollutants in the groundwater;

[0036] (8) Before, during and after the injection, groundwater samples are collected regularly through monitoring wells to analyze the concentration of pollutants and the residues of remediation agents to evaluate the remediation results.

[0037] In the aforementioned ultrasonic-based groundwater organic pollution remediation method, the remediation agent is a water-soluble compound.

[0038] In the aforementioned ultrasonic-based groundwater organic pollution remediation method, the power of the probe ultrasonic mechanism is above 1000W.

[0039] Technical effect: The ultrasonic device is equipped with a control system and a control panel. By adjusting the power value on the panel, the ultrasonic vibration intensity can be adjusted. The ultrasonic mechanism outputs continuous ultrasonic pulses. The present invention uses a piezoelectric transducer combined with a circuit to generate pulsed ultrasonic vibrations:

[0040] Principle: Piezoelectric transducers can convert electrical energy into mechanical vibration energy. By designing a suitable circuit to generate a pulse signal and applying it to the piezoelectric transducer, the transducer can generate pulsed ultrasonic vibrations.

[0041] Implementation steps: Select a suitable piezoelectric transducer, determine its model and specifications based on the desired pulsed ultrasonic vibration frequency, power, and other parameters, and design a circuit capable of generating a suitable pulse signal. Common circuits include rectangular wave pulse circuits and sawtooth wave pulse circuits. Connect the piezoelectric transducer to the circuit, ensuring that the circuit can stably output pulse signals to the transducer. By adjusting the parameters of components such as resistance, capacitance, and inductance in the circuit, the frequency, amplitude, and shape of the pulse signal can be changed, thereby controlling the characteristics of the pulsed ultrasonic vibration generated by the piezoelectric transducer.

[0042] The beneficial effects of the present invention are:

[0043] Chemical agents can be water-soluble compounds; for reaction systems where two or more compounds react to produce active species, separate dosing pipes should be set up to avoid ineffective drug reactions, improve reaction efficiency, and reduce agent costs.

[0044] The multi-directional matrix probe ultrasonic mechanism of the present invention needs to be placed on a matching automatic lift to increase the diffusion speed and range of the agent and improve the repair efficiency.

[0045] The present invention does not require additional configuration of a dosing system. Through the existing probe ultrasonic mechanism, a drug tube is installed on it to add the drug into the injection well to react with groundwater for reduction, which is low in cost and easy to use.

[0046] The filling layer of the present invention is a variety of compositions, including bentonite and cement, which seals the injection well pipe to ensure its stability and prevent pollutants from flowing back. The quartz sand used plays a filtering role to prevent soil particles from entering the well pipe.

[0047] The present invention accelerates the transmission of remediation agents in groundwater through a multi-directional matrix probe ultrasonic mechanism, significantly improving the removal efficiency of organic pollutants, and is particularly suitable for persistent organic pollutants that are difficult to degrade.

[0048] Compared with traditional high-energy consumption technologies such as extraction and treatment, the repair technology of the present invention has lower energy consumption and is in line with the green and low-carbon development concept. In addition, by optimizing the transmission and reaction process of the agent, the amount of agent used is reduced, thereby reducing the repair cost.

[0049] The novel in-situ remediation technology for organic groundwater pollution of the present invention is applicable to various types of organic pollutants and complex hydrogeological conditions and has wide applicability.

[0050] The present invention combines a repair agent with ultrasound. The vibration generated by ultrasound is generally used to remove the gas produced in the reaction. Groundwater, especially the groundwater in the eastern plains, is full of particles such as silt and clay, has low permeability, and water migration is very slow, which limits the diffusion and mass transfer of the agent in the groundwater. In addition, ordinary ultrasonic mechanisms cannot achieve the diffusion of the agent in the groundwater. Ordinary ultrasonic probes cannot be used for direct treatment of the in-situ groundwater environment. The problems of the groundwater environment lead to poor performance of the repair agent, which is generally known to those skilled in the art but has not been solved for a long time. The existing solution can only be extracted and then processed, which is the same as ordinary surface water treatment. It is easy to mix the agent and perform homogeneous oxidative degradation, but the process is cumbersome and the cost is high. The present invention reverses the thinking and does not extract but directly processes. The repair agent is combined with ultrasound. The ultrasonic mechanism can overcome the problem of continuous mass transfer of the agent through continuous ultrasonic pulse output, achieve agent diffusion, and accelerate the in-situ degradation of pollutants. The spatial mass transfer efficiency is low and the energy resource consumption is high. This repair system cannot meet the use requirements. The high vibration intensity can better meet the use requirements.

[0051] The Fenton system and persulfate oxidation system are applied to the in-situ remediation of organically contaminated groundwater on site. This technology uses a multi-directional matrix probe ultrasonic mechanism to increase the transmission rate of the Fenton system and persulfate oxidation system in groundwater, thereby significantly improving the removal efficiency of organic pollutants in groundwater. The multi-directional matrix probe ultrasonic mechanism can effectively overcome the heterogeneity and low permeability of groundwater in complex groundwater environments by utilizing the multi-directional propagation and focusing characteristics of ultrasound. In this way, chemical agents can diffuse more quickly and evenly into the contaminated area and fully contact and react with the pollutants, thereby significantly improving the remediation efficiency. In addition, the invention can also enhance the activation performance of the Fenton system and persulfate oxidation system through the cavitation effect of ultrasound, further promoting the degradation of pollutants. Research has shown that this technology has significant advantages in treating pollutants in heterogeneous media, can effectively improve the removal efficiency of pollutants, and effectively solve the problems of excessive agent addition, low mass transfer efficiency, and secondary contamination existing in-situ groundwater remediation technologies. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1This is a schematic diagram of the structure of the ultrasonic groundwater organic pollution remediation system according to an embodiment of the present invention;

[0053] Figure 2 for Figure 1 Schematic diagram of the structure of the ultrasonic mechanism of the probe;

[0054] Figure 3 for Figure 2 A top view of

[0055] Figure 4 for Figure 1 Schematic diagram of the injection well structure;

[0056] Figure 5 This is a stratigraphic information map of a chemical contaminated site;

[0057] Figure 6 Layout of injection wells and monitoring wells for in-situ remediation of organic groundwater contamination on site;

[0058] Figure 7 This is the effect diagram of in-situ remediation of typical organic pollutants in groundwater dominated by Fenton oxidation;

[0059] Figure 8 This is the in-situ remediation effect diagram of typical organic pollutants in groundwater dominated by persulfate oxidation;

[0060] In the figure: 1-injection well, 2-monitoring well, 5-well pipe, 6-well cover, 7-well head sleeve, 8-pipe plug, 9-bentonite and cement mixed layer, 10-granular bentonite layer, 11-quartz sand layer, 12-chemical tube, 13-injection pump, 14-amplifier, 15-probe, 16-transducer, 17-traction rope, 18-elevator. DETAILED DESCRIPTION

[0061] The present invention will be described clearly and completely below with reference to specific embodiments. It should be understood that the embodiments described are merely some, and not all, of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0062] The present invention provides an ultrasonic groundwater organic pollution remediation system, which provides mass transfer power through a multi-directional matrix probe ultrasonic mechanism and acts as an underground in-situ mixer to achieve full contact between the agent and the pollutant, thereby accelerating the diffusion of the chemical agent in heterogeneous groundwater. Figure 1 As shown, it specifically includes an injection well system and a monitoring well system set up in the water pollution area to be repaired;

[0063] The injection well system includes an injection well 1 and a probe ultrasonic mechanism;

[0064] like Figure 4 As shown, the injection well 1 is composed of an injection well pipe 5, a well cover 6, a wellhead sleeve 7, a pipe plug 8 and a filling layer. The upper end of the injection well pipe 5 is connected to the wellhead sleeve 7, and the wellhead sleeve 7 is internally threaded and rotatably connected to the well cover 6. The lower end of the injection well pipe 5 is sealed by the pipe plug 8. The injection well pipe 5 is composed of a straight pipe section and a screen pipe section from top to bottom. The filling layer is arranged in the circumferential direction of the injection well pipe 5. The filling layer includes a bentonite and cement mixed layer 9, a granular bentonite layer 10 and a quartz sand layer 11 from top to bottom. Figure 1 As shown, a plurality of chemical tanks are provided at the injection wellhead for storing corresponding repair chemicals. The chemical tanks are connected to the chemical pipe 12 through the injection pump to inject the repair chemicals into the injection well. Pressure sensors and flow meters are provided on the pipelines of the chemical tanks and the injection pump respectively.

[0065] like Figure 2-3 As shown, the probe ultrasonic mechanism includes a power supply, an horn 14, a probe 15, a transducer 16, a traction rope 17 and an elevator 18. The power supply is arranged at the injection well 1. The horn 14 is a hollow cylindrical structure with a receiving cavity in the middle. The transducer 16 is embedded in the receiving cavity. The power supply is connected to the transducer 16 through an electric wire. A plurality of threaded holes are provided on the surface along the circumference of the horn 14. The probe 15 is detachably arranged on the outer surface of the horn 14 through a thread. The probe 15 is arranged in a matrix on the outer surface of the horn 14. The horn is made into a sealing structure to prevent water from entering. For example, a sealing ring is provided between the probe and the horn to maintain sealing. The elevator 18 is arranged at the injection well 1. One end of the traction rope 17 is wound around the elevator 18, and the other end is connected to the horn 14 to drive the vertical lifting of the probe 15.

[0066] An injection well 1 is embedded in the soil of a water-contaminated area. A probe ultrasonic mechanism is disposed in the injection well 1. A reagent pipe 12 is provided on the probe ultrasonic mechanism. A remediation agent is added to the injection well 1 to mix and react with groundwater. The probe ultrasonic mechanism accelerates the mixing and reaction of the remediation agent and groundwater to degrade organic pollutants in the groundwater.

[0067] The monitoring well system includes a monitoring well 2, a water quality monitor and a multifunctional water quality monitoring probe. The multifunctional water quality monitoring probe is suspended in the monitoring well 2 and is electrically connected to the water quality monitor. A monitoring well is provided on one side of each injection well. After multiple injection wells and monitoring wells are arranged, the monitoring well is located at the center of the three adjacent injection wells. Figure 6 As shown in Figure 2, the concentration of organic pollutants in groundwater was measured by sampling from monitoring wells adjacent to the injection wells to evaluate the remediation effectiveness.

[0068] In order to facilitate use and make the operation more automated, a control system in the existing technology is also adopted, an intelligent control box, which is internally provided with a control unit, a wireless transmission module (3G or 4G module), and a storage unit. The control unit is electrically connected to the wireless transmission module and the storage unit respectively, and the control unit communicates or is electrically connected to the injection pump, the probe ultrasonic mechanism, and the water quality monitor to realize automatic control and perform adjustments according to actual needs. For example, the water quality monitor transmits the detected data to the control unit through a data transmission line for convenient analysis. The probe ultrasonic mechanism is controlled by the control unit to have a temperature of 25°C (an alarm temperature to prevent system overheating), a power of 50% (set according to the percentage of the maximum power of the ultrasonic equipment), a start-up time of 4s, and an intermittent working time of 2s, which is beneficial to the degradation effect of the treatment agent on groundwater.

[0069] The above-mentioned repair method of the groundwater organic pollution repair system specifically includes the following steps:

[0070] (1) Based on the site survey results, the injection well location is selected and the injection well is laid out by direct drilling. A drilling rig is used to drill a hole to the submerged layer on the site to be repaired, and a vertical injection well is built. The injection well pipe is inserted into the borehole. The inner diameter of the injection well pipe is not less than 200 mm, and the outer diameter of the injection well pipe is smaller than the size of the rotary drill hole. In order to ensure the smooth layout of the filling layer, the injection well pipe is filled with materials in sequence to form a filling layer;

[0071] (2) Multiple reagent tanks and injection pumps are installed at the injection wellhead as needed. One end of the reagent tube is connected to the reagent tank through the injection pump, and the other end is installed on the probe and extends into the injection well pipe. The hoist suspends the horn equipped with the probe in the injection well pipe through a traction rope;

[0072] (3) Drill holes around the injection well and downstream of the contaminated area to ensure that the monitoring well can cover the target contaminated area, insert the monitoring well pipe into the drill hole, and fill the area around the monitoring well pipe with material;

[0073] The monitoring well adopts the structure of the existing technology, including a monitoring well pipe, which includes a white pipe section, a screen pipe section and a sedimentation pipe from top to bottom. The bottom of the monitoring well pipe is sealed with a pipe plug. The outer circumference of the monitoring well pipe is filled with a bentonite layer and a quartz sand layer from top to bottom. The monitoring well pipe is made of UPVC.

[0074] (4) A water quality monitor is installed at the monitoring wellhead, and a multifunctional water quality monitoring probe is placed in the monitoring well through an electric wire;

[0075] (5) Prepare the repair agent solution separately and put it into the corresponding agent tank; use sulfuric acid or sodium hydroxide to adjust the pH value of the repair solution as needed to facilitate the optimal reaction;

[0076] (6) Connect the repair agent solution to the injection pump, ensure that there is no leakage in the system, start the injection pump, and release the chemical agent from the agent tube at the front of the probe according to the predetermined injection pressure (0.05-0.2MPa) and flow rate (0.5-2L / min), and record the pressure, flow rate and time during the injection process; use the pressure sensor and flow meter on the pipeline to monitor the parameter changes during the injection process in real time; ensure the stability and safety of the injection process.

[0077] (7) After the agent is injected and diffuses for a period of time, the multi-directional matrix probe ultrasonic mechanism is placed in the injection well by a lift and a traction rope, submerged in the groundwater, and the multi-directional matrix probe ultrasonic mechanism is started to accelerate the diffusion of the agent in the groundwater layer, and the ultrasonic effect is used to promote the fusion and reaction of the agent and the organic pollutants, thereby completing the degradation of organic pollutants in the groundwater;

[0078] (8) Before, during and after injection, groundwater samples were collected regularly through monitoring wells to analyze pollutant concentrations and remediation agent residues.

[0079] It should be noted that the water-soluble compounds of the repair agent can be selected from currently commonly used advanced oxidation technology materials, such as persulfate oxidation system, Fenton / Fenton-like system and high-valent iron oxidation system;

[0080] Examples include persulfates or permonosulfates with transition metals; variable-valence transition metal salts with hydrogen peroxide; oxidation systems that can generate tetravalent or higher-valent iron compounds; and transition metals that can be oxidized by persulfates and permonosulfates to form strong oxidizing species such as sulfate radicals. It should be noted that the injection well size should be selected based on the size of the probe's ultrasonic mechanism.

[0081] It should be noted that the advanced oxidants are injected separately under pressure to avoid premature reaction.

[0082] It should be noted that the reaction conditions should comply with the reaction conditions of relevant advanced oxidation technologies, such as pH, etc.

[0083] It should be noted that the vertical lifting height range of the probe ultrasonic mechanism should not be lower than the vertical height of the groundwater pollution, so as to ensure the full diffusion of the agent and the full mixing and reaction with the organic pollutants. The hydrogeological information of a block of land to be remediated at the selected chemical contaminated site is as follows: Figure 5 The permeability coefficients of various soil layers are shown in Table 1.

[0084] Table 1 Permeability coefficient of each soil layer

[0085]

[0086]

[0087] According to drilling data, the upper strata of the exploration site are fill, Quaternary Holocene (Q 4al ) silty clay, silt, silt sand, and silty clay. Combining field drilling, in-situ testing, and geotechnical test data, the distribution of strata within the depth range explored is as follows:

[0088] ① Layer of plain fill (Q 4ml Gray to grayish yellow, loose, slightly damp to wet, containing plant roots, with clay soil and a small amount of gravel at the bottom. 2.40-5.80 meters thick, widely distributed on the site.

[0089] ② Layer of silty clay mixed with silt (Q 4al+pl Gray to gray-brown, predominantly plastic, slightly lustrous, no shaking reaction, medium dry strength and toughness, and contains organic matter. Interbedded with silt, slightly dense, very wet, dull, with medium shaking reaction, low dry strength and toughness, and contains traces of Fe oxides. The top of the layer is 2.40-3.00 meters deep, 0.41-1.69 meters in elevation, and 1.00-3.10 meters thick. This layer is absent in KC1 and its surrounding areas within the site.

[0090] ③ Layer of silt interbedded with silty clay (Q 4al+pl ): Bluish-gray to gray, slightly dense, wet, with low dry strength and toughness, dull, moderate shaking reaction, and contains organic matter. Interbedded with silty clay, soft and plastic, slightly lustrous, no shaking reaction, with medium dry strength and toughness. The top of the layer is buried at a depth of 3.80-5.80 meters, with an elevation of -1.71 to 0.05 meters, and a thickness of 1.20-1.90 meters. It is widely distributed.

[0091] ④-1 layer of silt sand and silt soil (Q 4al+pl Gray to bluish-gray, slightly dense to medium dense, saturated, low dry strength and toughness, dull, moderate shaking reaction, contains mica fragments, and the main minerals are quartz and feldspar. Interbedded with silt, medium dense, low dry strength and toughness, dull, and moderate shaking reaction. The top of the layer is buried at a depth of 5.50 to 6.70 meters, with an elevation of -2.62 to -1.65 meters, and a thickness of 6.80 to 8.20 meters. It is widely distributed.

[0092] ④-2 layers of silty clay interbedded with silt (Q 4al+pl Gray to bluish-gray, soft-plastic, slightly moist, with medium dry strength and toughness, slightly lustrous, and no shaking reaction. Interspersed with silt, slightly dense, with low dry strength and toughness, dull, and moderate shaking reaction. The top of the layer is 13.4-13.70 meters deep, with an elevation of -10.00 to -9.31 meters, and a thickness of 1.20-2.40 meters. It is widely distributed.

[0093] ⑤ Layer of silt sand and silt soil (Q 4al+plGray to bluish-gray, medium-dense, saturated, low dry strength and toughness, dull, moderate shaking reaction, contains mica fragments, and the main minerals are quartz and feldspar. Interbedded with silt (locally high silt content), medium-dense to dense, low dry strength and toughness, dull, and moderate to rapid shaking reaction. Particle composition: 0.5-0.25 mm accounts for 1.1-5.6%, 0.25-0.075 mm accounts for 52.7-69.85%, and 0.075-0.005 mm accounts for 28.9-41.64%. The top of the layer is buried at a depth of 14.60-15.90 meters, with an elevation of -11.95 to -10.81 meters, and a thickness of 6.90 to 8.70 meters. It is widely distributed.

[0094] ⑥ Layer of silty clay interbedded with silt (Q 4al+pl ): Bluish-gray to gray, soft and plastic, with medium dry strength and toughness, slightly lustrous, and no shaking reaction. Interspersed with silt, slightly dense, with low dry strength and toughness, dull, and moderate to rapid shaking reaction. The top of the layer is 22.00 to 23.60 meters deep, with an elevation of -19.65 to -18.60 meters, and a thickness of 2.50 to 4.10 meters. It is widely distributed.

[0095] ⑦ Layer of silty clay (Q 4al+pl ): Bluish-gray to gray, soft to plastic, with medium dry strength and toughness, slightly lustrous, and no shaking reaction. The top of the layer is buried at a depth of 26.00-26.30 meters, with an elevation of -22.70 to -22.01 meters. The exposed thickness is 2.20-3.30 meters, unpenetrated, and widely distributed.

[0096] The main organic pollutant in the groundwater of the remediation site is chlorobenzene, and the concentration of chlorobenzene in the aquifer is as high as 21.9 mg L -1 , exceeding the Class IV water quality standard; the concentration of chlorobenzene in the micro-confined aquifer sample in the first micro-confined aquifer reached 13.5 mg L -1 , exceeding the Class IV water quality standard; the concentration of chlorobenzene in the sample of the II micro-confined aquifer reached 2.6 mg L -1 , exceeding the Class IV water quality standard, the specific data are shown in Table 2;

[0097] Table 2 Concentration of organic pollutants

[0098] aquifer <![CDATA[Detected concentration (mg L -1 )]]> diving 21.9 First micro-confined water 13.5 II Micro-confined water 2.6

[0099] The system and method of the present invention are used to repair organic pollution in groundwater.

[0100] Example 1

[0101] This embodiment provides a remediation method for groundwater organic pollution based on an ultrasonic remediation system. The above-mentioned remediation system is used, and the reagent is Fenton reagent (3% H2O2 solution and 0.5% FeSO4 solution). The method specifically includes the following steps:

[0102] (1) Based on the site survey results, the locations of injection wells and monitoring wells are selected and laid out by direct drilling to ensure the stability and sealing of the well pipes;

[0103] (2) According to the experimental design, prepare Fenton's reagent, specifically: 3% H2O2 solution and 0.5% FeSO4 solution; as needed, use sulfuric acid or sodium hydroxide to adjust the pH value of the injection solution to 3-5 (the appropriate pH range for the Fenton reaction);

[0104] (3) Inject the Fenton reagent into the corresponding reagent tank, connect the Fenton reagent to the injection pump, ensure that the system is leak-free, start the injection pump, and separate the FeSO4 solution and the H2O2 solution from the reagent pipe at the front of the probe according to the predetermined injection pressure of 0.05 MPa and flow rate of 0.5 L / min to release the chemical reagent in the injection well, and record the pressure, flow rate and time during the injection process; use a pressure sensor and flow meter to monitor the parameter changes during the injection process in real time to ensure the stability and safety of the injection process;

[0105] (4) After the reagents were injected, the multi-directional matrix probe ultrasonic mechanism was activated with a power of 4250 W to accelerate the diffusion of H2O2 and FeSO4 reagents in the groundwater layer. The injection well without the multi-directional matrix probe ultrasonic system was used as a control group.

[0106] (5) Before, during, and after the injection process, groundwater samples were collected regularly through monitoring wells to analyze pollutant concentrations and remediation agent residues. Pollutants (e.g., chlorobenzene), H2O2, and FeSO4 were measured using gas chromatography-mass spectrometry, UV-visible spectrophotometry, and atomic absorption spectroscopy, respectively. In addition, groundwater pH was also monitored simultaneously to provide data support for the dynamic remediation effect.

[0107] The in-situ remediation effect of typical organic pollutants in groundwater dominated by Fenton oxidation is as follows: Figure 7 As shown in the figure, the concentrations after 0.5, 1, 2, 3, 4, 5, 7, 9, 11, 13 and 15 days of reaction were reduced to 85.9%, 78.2%, 72.4%, 64.9%, 59.5%, 55.3%, 34.1%, 24.8%, 7.0%, 5.9% and 5.7% of the initial concentration, respectively. The removal rate of chlorobenzene was 0.19d -1In the blank group without Fenton's reagent, the concentrations after 0.5, 1, 2, 3, 4, 5, 7, 9, 11, 13, and 15 days of reaction were reduced to 95.9%, 96.4%, 91.8%, 92.9%, 96.7%, 91.3%, 95.8%, 92.2%, 96.3%, 93.7%, and 98.8% of the initial concentrations, respectively, indicating that the concentration of chlorobenzene did not change significantly. As for the control group without ultrasonic mechanism, the concentrations after 0.5, 1, 2, 3, 4, 5, 7, 9, 11, 13, and 15 days of reaction were reduced to 98.4%, 95.7%, 92.6%, 89.2%, 83.4%, 79.8%, 77.6%, 68.3%, 62.0%, 58.2%, and 52.5% of the initial concentrations, respectively, and the removal rate of chlorobenzene was 0.04d. -1 Therefore, a comparative analysis compared to the control group found that the introduction of the multi-directional matrix probe ultrasonic mechanism increased the removal rate of organic pollutants in groundwater by 4.75 times, significantly shortening the remediation time and reducing the cost of reagents. During the reaction, the pH value of the groundwater was always maintained at 3.0 ± 0.3.

[0108] Example 2

[0109] This embodiment provides a remediation method for groundwater organic pollution based on an ultrasonic remediation system, using the above-mentioned remediation system, and using Na2S2O8 solution and FeSO4 solution as reagents, specifically including the following steps:

[0110] (1) Based on the site survey results, the locations of injection wells and monitoring wells are selected and laid out by direct drilling to ensure the stability and sealing of the well pipes;

[0111] (2) According to the experimental design, a sulfate solution and an activator solution are prepared, specifically: 0.5-2% Na2S2O8 solution and 0.1-0.5% FeSO4 solution. As needed, sulfuric acid or sodium hydroxide is used to adjust the pH value of the injection solution to 3-6 (the optimal pH range for persulfate oxidation);

[0112] (3) Inject the persulfate solution and the activator solution into the corresponding reagent tanks, connect the persulfate solution and the activator solution to the injection pump, ensure that there is no leakage in the system, start the injection pump, and release the Na2S2O8 solution and FeSO4 solution from the reagent pipe at the front of the probe into the injection well according to the predetermined injection pressure of 0.2MPa and flow rate of 2L / min, and record the pressure, flow rate and time during the injection process; use pressure sensors and flow meters to monitor the parameter changes in real time during the injection process to ensure the stability and safety of the injection process;

[0113] (4) After the injection of the reagents, the multi-directional matrix probe ultrasonic mechanism was started with a power of 3400W to accelerate the diffusion of Na2S2O8 and FeSO4 reagents in the groundwater layer. The injection wells without the introduction of the multi-directional matrix probe ultrasonic system were used as the control group for comparison; (5) Before, during and after the injection, groundwater samples were collected regularly through monitoring wells to analyze the concentration of pollutants and the residues of the remediation agent. Pollutants (such as chlorobenzene), Na2S2O8 and FeSO4 were measured by gas chromatography-mass spectrometry, ultraviolet-visible spectrophotometry and atomic absorption spectroscopy, respectively. In addition, the pH value of the groundwater was also monitored synchronously to provide data support for the dynamic remediation effect.

[0114] The experimental results are as follows Figure 8 As shown in the figure, in the blank group without PMS reagent, the concentrations after 0.5, 1, 2, 3, 4, 5, 7, 9, 11, 13, and 15 days of reaction were reduced to 95.6%, 96.2%, 91.3%, 92.5%, 96.1%, 90.6%, 95.0%, 92.8%, 96.9%, 93.0%, and 98.5% of the initial concentration, respectively, indicating that ultrasound alone had no significant effect on the concentration of chlorobenzene in groundwater. In the control group without ultrasound, the concentrations after 0.5, 1, 2, 3, 4, 5, 7, 9, 11, 13, and 15 days of reaction were reduced to 95.8%, 90.6%, 86.9%, 71.6%, 66.0%, 58.1%, 45.9%, 23.6%, 13.1%, 8.0%, and 5.2% of the initial concentration, respectively, and the removal rate of chlorobenzene was 0.15d. -1 For the laboratory group treated with ultrasound + PMS, the concentrations decreased to 88.0%, 71.3%, 60.9%, 53.9%, 44.0%, 28.7%, 14.1%, 7.0%, 6.0%, 5.0% and 2.0% of the initial concentrations after 0.5, 1, 2, 3, 4, 5, 7, 9, 11, 13 and 15 days of reaction, respectively. The removal rate of chlorobenzene was 0.27d. -1 Therefore, compared with the control group, the introduction of the multi-directional matrix probe ultrasonic mechanism increased the removal rate of organic pollutants in groundwater by 1.8 times. Throughout the experiment, the pH value of the groundwater was maintained within the range of 3.0±0.2.

[0115] The present invention uses a Fenton system and a persulfate oxidation system to remove chlorobenzene, a typical organic pollutant in the groundwater of the site, in situ. A multi-directional matrix probe ultrasonic mechanism is used as a mass transfer power source and an underground in-situ mixer. The mechanism adopts a stainless steel shell and a titanium alloy probe. In the process of removing organic pollutants in the groundwater, the ultrasonic power and intermittent frequency are strictly controlled to achieve in-situ, efficient and precise removal of organic pollutants in the groundwater, overcoming the problems of high energy consumption, slow reagent mass transfer rate, and low reaction efficiency in existing treatment technologies.

[0116] In addition to the above embodiments, the present invention may also have other implementations. Any technical solution formed by equivalent replacement or equivalent transformation falls within the protection scope of the present invention.

Claims

1. An ultrasonic-based groundwater organic pollution remediation system, characterized by: Including injection well systems and monitoring well systems set up in water pollution areas; The injection well system comprises an injection well (1) and a probe ultrasonic mechanism, wherein the injection well (1) is embedded in the soil of a water-polluted area, the probe ultrasonic mechanism is arranged in the injection well (1), and a reagent pipe (12) is further provided on the probe ultrasonic mechanism. A repair reagent is added to the injection well (1) through the reagent pipe on the probe ultrasonic mechanism to mix and react with groundwater, and the probe ultrasonic mechanism accelerates the mixing and reaction of the repair reagent and groundwater to complete the degradation of organic pollutants in the groundwater; The monitoring well system comprises a monitoring well (2), a water quality monitor and a multifunctional water quality monitoring probe, wherein the multifunctional water quality monitoring probe is suspended in the monitoring well (2) and is electrically connected to the water quality monitor. A monitoring well is provided on one side of the injection well, and the concentration of organic pollutants in the groundwater is measured by sampling the monitoring well.

2. The ultrasonic groundwater organic pollution remediation system according to claim 1 is characterized by: The injection well (1) is composed of an injection well pipe (5), a well cover (6), a well head sleeve (7), a pipe plug (8) and a filling layer. The upper end of the injection well pipe (5) is connected to the well head sleeve (7), and the well head sleeve (7) is internally threaded and rotatably connected to the well cover (6). The lower end of the injection well pipe (5) is sealed by the pipe plug (8). The injection well pipe (5) is composed of a straight pipe section and a screen pipe section from top to bottom. The filling layer is arranged in a circumferential direction around the injection well pipe (5). The filling layer comprises, from top to bottom, a bentonite and cement mixed layer (9), a granular bentonite layer (10) and a quartz sand layer (11).

3. The ultrasonic groundwater organic pollution remediation system according to claim 1 is characterized by: The injection wellhead is also provided with a plurality of chemical tanks for storing repair chemicals, and the chemical tanks are connected to the chemical pipes through injection pumps.

4. The ultrasonic-based groundwater organic pollution remediation system according to claim 4 is characterized in that: A pressure sensor and a flow meter are respectively provided on the pipeline between the medicine tank and the injection pump (13).

5. The ultrasonic-based groundwater organic pollution remediation system according to claim 1 is characterized in that: The probe ultrasonic mechanism includes a power supply, a variable amplitude rod (14), a probe (15), a transducer (16), a traction rope (17) and an elevator (18). The power supply is arranged at the mouth of the injection well (1) to provide power for the probe ultrasonic mechanism. A receiving cavity is provided in the middle of the variable amplitude rod (14), and the transducer (16) is embedded in the receiving cavity. The power supply is connected to the transducer (16) through an electric wire. A plurality of threaded holes are provided along the surface of the circumference of the variable amplitude rod (14). The probe (15) is detachably arranged on the outer surface of the variable amplitude rod (14) through threads. The elevator (18) is arranged at the mouth of the injection well (1). One end of the traction rope (17) is wound around the elevator (18), and the other end is connected to the variable amplitude rod (14) to drive the probe (15) to rise and fall vertically.

6. The ultrasonic-based groundwater organic pollution remediation system according to claim 5 is characterized by: The probes (15) are arranged in a matrix pattern on the outer surface of the amplitude transformer (14).

7. A method for repairing groundwater organic pollution using the ultrasonic-based groundwater repair system according to any one of claims 1 to 6, characterized in that: The specific steps include: (1) Based on the site survey results, the injection well location is selected, and the injection well is laid out by direct drilling using a drilling rig. The injection well pipe is inserted into the borehole, and the injection well pipe is filled with material to form a filling layer; (2) A plurality of chemical tanks and injection pumps are provided at the injection wellhead. One end of the chemical pipe is connected to the chemical tank through the injection pump, and the other end is provided on the probe and extends into the injection well pipe. The hoist suspends the amplitude rod equipped with the probe in the injection well pipe through a traction rope; (3) Drill holes around the injection well and downstream of the contaminated area to ensure that the monitoring well can cover the target contaminated area, insert the monitoring well pipe into the drill hole, and fill the surrounding area of the monitoring well pipe with material to form a filling layer; (4) A water quality monitor is installed at the mouth of the monitoring well, and a multifunctional water quality monitoring probe is placed in the monitoring well through an electric wire; (5) Prepare the repair agent solution and put it into the corresponding agent tank; (6) Start the injection pump and inject the repair agent into the injection well pipe separately. Use the pressure sensor and flow meter on the pipe to monitor the parameter changes during the injection process in real time. (7) After the agent is injected, the multi-directional matrix probe ultrasonic mechanism is activated to accelerate the diffusion of the agent in the groundwater layer, and to mix and react to complete the degradation of organic pollutants in the groundwater; (8) Before, during and after injection, groundwater samples are collected regularly through monitoring wells to analyze pollutant concentrations and remediation agent residues.

8. The ultrasonic-based groundwater organic pollution remediation method according to claim 1, characterized in that: The repair agent is a water-soluble compound.

9. The ultrasonic-based groundwater organic pollution remediation method according to claim 1, characterized in that: The power of the probe ultrasonic mechanism is above 1000 W.

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