CN117102223A - Injection, monitoring and detection integrated repairing equipment and method for heavy metal pollution site - Google Patents

Injection, monitoring and detection integrated repairing equipment and method for heavy metal pollution site Download PDF

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Publication number
CN117102223A
CN117102223A CN202311087707.6A CN202311087707A CN117102223A CN 117102223 A CN117102223 A CN 117102223A CN 202311087707 A CN202311087707 A CN 202311087707A CN 117102223 A CN117102223 A CN 117102223A
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injection
monitoring
expansion body
heavy metal
repairing
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CN117102223B (en
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贺勇
魏贺
江钧
宋相志
黄艳凤
张可能
朱考飞
张召
金福喜
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Central South University
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Central South University
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B09DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09CRECLAMATION OF CONTAMINATED SOIL
    • B09C1/00Reclamation of contaminated soil
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B09DISPOSAL OF SOLID WASTE; RECLAMATION OF CONTAMINATED SOIL
    • B09CRECLAMATION OF CONTAMINATED SOIL
    • B09C2101/00In situ
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02ATECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/30Assessment of water resources

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  • Life Sciences & Earth Sciences (AREA)
  • Soil Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Environmental & Geological Engineering (AREA)
  • Working Measures On Existing Buildindgs (AREA)

Abstract

The application provides a device and a method for injecting, monitoring and detecting integrated restoration of a heavy metal polluted site, which relate to the field of polluted soil restoration and comprise the following steps: the injection device comprises a liquid storage tank and a plurality of layered injection units used for being placed in an injection well, wherein each layered injection unit comprises an upper expansion body and a lower expansion body, a flower pipe with a closed bottom end is arranged between the upper expansion body and the lower expansion body, and the top end of the flower pipe is communicated with the liquid storage tank; the real-time monitoring device comprises a plurality of temperature and humidity sensors, wherein the temperature and humidity sensors are used for being arranged in a monitoring well; the detection device is used for detecting the resistivity of the area to be repaired; the inner wall of the injection well is extruded by the two expansion bodies, so that the repairing agent can only be diffused in the stratum between the two expansion bodies when the repairing agent is injected into the flowtube, and uncontrollable migration of the repairing agent is avoided, and the diffusion range cannot be monitored.

Description

Injection, monitoring and detection integrated repairing equipment and method for heavy metal pollution site
Technical Field
The application relates to the field of polluted soil restoration, in particular to equipment and a method for restoring injection, monitoring and detection of a heavy metal polluted site.
Background
The existing large amount of heavy metal pollution sites in China seriously threatens the ecological environment safety and the human health. Heavy metals are the main pollutants affecting the soil environment quality of agricultural land nationwide, and the pollution conditions of cadmium, copper, lead, chromium, zinc and nickel are common, wherein the heavy metal pollution brought by the industrial industry is particularly remarkable. Since the industrial start of China is late, but the progress is faster, the enterprise types of the same industrial site are frequently changed, so that the industrial heavy metal pollution sites of China are mostly multi-metal composite pollution sites. Because of the characteristics of strong detention capability, poor degradability and the like of heavy metals in soil, the influence caused by heavy metal pollution can be tens or even hundreds of years. Meanwhile, heavy metals in the soil body continuously migrate under the action of groundwater seepage, the horizontal distance can reach several kilometers, the depth is nearly hundred meters, and the hazard range is continuously enlarged; and a series of physical and chemical reactions can occur in the migration process, so that morphological transformation is realized in the soil environment, and the removal becomes more difficult. In addition, heavy metals can also enter animals and plants through soil-water-plant systems, and then indirectly or directly enter human bodies through food chains, underground water and the like, so that chronic poisoning is caused. Thus, heavy metal contaminated site remediation is an urgent need for society.
The common repairing method for the heavy metal polluted site comprises the following steps: soil replacement landfill, cement kiln incineration, soil leaching, microbial phytoremediation, in-situ injection chemical remediation and the like. In-situ injection chemical remediation is one of the most widely used in many in-situ remediation methods, and is to inject an oxidant or a reducing agent into the soil in a polluted area, so that pollutants in the soil body are converted into non-toxic or relatively less toxic substances through oxidation or reduction, and the purpose of remediation is achieved.
Taking widely existing lead and zinc pollution sites in China as an example, the loaded nano zero-valent iron is injected into the underground pollution layer by an in-situ injection chemical repair method, and the nano zero-valent iron can effectively remove Pb in soil 2+ And Zn 2+ The removal rate is as high as 90%. However, the in-situ injection repairing of lead-zinc contaminated sites still has the following problems:
(1) When the repairing agent is injected into a stratum with a complex structure and larger difference, the repairing agent is easy to permeate along a dominant channel, and the ideal diffusion effect is not achieved;
(2) The migration and diffusion range of the repairing agent in the injection process are uncontrollable and cannot be monitored;
(3) After the injection is completed, the final diffusion radius of the repairing agent cannot be detected;
(4) The fixed-depth, fixed-quantity and fixed-point injection of the repairing agent can not be realized.
Aiming at the problems, an integrated device and method for preparing, injecting, monitoring and detecting the heavy metal pollution site load type repairing agent, which are convenient and easy to operate, low in maintenance cost and capable of being popularized in actual engineering, are required to be sought.
Disclosure of Invention
The application provides an integrated repairing device and method for heavy metal pollution site injection, monitoring and detection, and aims to solve the defects of the existing in-situ injection chemical repairing.
In order to achieve the above object, an embodiment of the present application provides an integrated repair device for injecting, monitoring and detecting a heavy metal contaminated site, including:
the injection device comprises a liquid storage tank and a plurality of layered injection units used for being placed in an injection well, wherein each layered injection unit comprises an upper expansion body and a lower expansion body, a flower pipe with a closed bottom end is arranged between the upper expansion body and the lower expansion body, and the top end of the flower pipe is communicated with the liquid storage tank;
the real-time monitoring device comprises a plurality of temperature and humidity sensors, wherein the temperature and humidity sensors are used for being arranged in a monitoring well;
and the detection device is used for detecting the resistivity of the area to be repaired.
Preferably, the injection device further comprises an air compressor and a gas pressure controller, the gas pressure controller is communicated with the air compressor through a gas pipeline, at least two independently controlled pressure outlets are arranged on the gas pressure controller, one of the pressure outlets is communicated with the liquid storage tank, the other pressure outlets are respectively communicated with a plurality of expansion pipelines, and each expansion pipeline is respectively communicated with an upper expansion body and a lower expansion body of one layered injection unit so as to control the expansion amplitude of the upper expansion body and the lower expansion body in the layered injection units;
an air bag is arranged in the liquid storage tank, and a pressure outlet communicated with the liquid storage tank discharges injection liquid in the liquid storage tank into the flower pipe by controlling the expansion of the air bag.
Preferably, a flowmeter is arranged between the liquid storage tank of the pressure gauge and the flower pipe on the expansion pipeline;
the detection device comprises a high-density resistivity meter and a measuring line connected with the high-density resistivity meter, wherein a plurality of electrodes perpendicular to the measuring line are arranged on the measuring line, the measuring line is arranged at the injection well, the center of the measuring line is positioned at the center of the injection well, and a plurality of measuring lines are arranged in a radial manner;
the integrated repairing equipment for heavy metal pollution site injection, monitoring and detection further comprises a central control device, wherein the central control device is in signal connection with the pressure gauge, the flowmeter, the temperature and humidity sensor, the gas pressure controller, the air compressor and the high-density resistivity meter.
The application also provides a repairing method, which adopts the integrated repairing equipment for injecting, monitoring and detecting the heavy metal pollution site, and is characterized by comprising the following steps:
s1, before repairing a polluted site, detecting a region to be repaired, and acquiring the initial resistivity of the region to be repaired;
s2, excavating an injection well and a monitoring well, and respectively lowering a temperature and humidity sensor and a layered injection unit into the monitoring well and the injection well;
s3, preparing a repairing agent;
s4, adjusting the expansion amplitude of the upper expansion body and the lower expansion body to enable the upper expansion body and the lower expansion body to be in close contact with the inner wall of the injection well respectively;
s5, injecting a repairing agent into a pollution layer between the upper expansion body and the lower expansion body through a flowtube, and acquiring the time-dependent changes of the temperature and the humidity of each monitoring well and the time-dependent changes of the injection quantity of the repairing agent in real time in the injection process;
s6, after the repairing agent is injected, detecting the area to be repaired to obtain the resistivity after the repairing.
Preferably, in step s2, the injection well is deep into the contaminated layer, several monitoring wells are laid around the injection well, and the diffusion depth and diffusion radius of the monitoring wells are different.
Preferably, the repairing agent is bentonite suspension carrying kaolin loaded with nano zero-valent iron, and the bentonite is sodium modified bentonite.
Preferably, the mass ratio of the nano zero-valent iron in the kaolin loaded nano zero-valent iron is 25% -33%.
Preferably, the bentonite in the suspension accounts for 3% by mass, and the K-nZVI accounts for 0.2% -0.4% by mass.
Preferably, before step s4, the gas tightness check is performed on the integrated repair equipment for injecting, monitoring and detecting the heavy metal contaminated site.
The scheme of the application has the following beneficial effects:
in the application, two expansion bodies are utilized to inflate and expand to extrude stratum around the expansion bodies (the inner wall of the injection well), and then the expansion bodies are closely contacted with the inner wall of the injection well, so that the repairing agent can only diffuse in the stratum between the two expansion bodies, and uncontrollable migration of the repairing agent is avoided, and the diffusion range cannot be monitored.
Simultaneously, two expansion bodies limit the depth position of the repair liquid in the injection well from the upper direction and the lower direction respectively, so that fixed-point, positioning and repair are realized.
Additional features and advantages of the application will be set forth in the detailed description which follows.
Drawings
FIG. 1 is a schematic illustration of the present application;
FIG. 2 is a schematic diagram of an assembly of a layered injection unit with an injection well;
FIG. 3 is a schematic diagram of an assembly of a temperature and humidity sensor and a monitoring well;
FIG. 4 is a schematic illustration of injection well and several monitoring wells;
fig. 5 is a schematic diagram of the steps of a repair method.
[ reference numerals description ]
11-a liquid storage tank, 121-an upper expansion body, 122-a lower expansion body, 123-a flower pipe, 124-an expansion pipeline, 125-a flowmeter 13-an air compressor, 14-a gas pressure controller,
21-temperature and humidity sensor
31-high density resistivity meter, 32-measuring line, 33-electrode,
4-central control device,
a-injection well, b-monitoring well,
Detailed Description
In order to make the technical problems, technical solutions and advantages to be solved more apparent, the following detailed description will be given with reference to the accompanying drawings and specific embodiments.
As shown in fig. 1 to 4, an embodiment of the present application provides an integrated repair apparatus for heavy metal contaminated sites, including an injection device, a real-time monitoring device and a monitoring device, wherein the injection device includes a liquid storage tank 11 and a plurality of layered injection units for being placed into an injection well a, the layered injection units including an upper expansion body 121 and a lower expansion body 122, a flowtube 123 is disposed between the upper expansion body 121 and the lower expansion body 122 in a longitudinal direction, and a top end of the flowtube 123 is communicated with the liquid storage tank 11, and a bottom end thereof is closed. The real-time monitoring device comprises a plurality of temperature and humidity sensors 21, wherein the temperature and humidity sensors 21 are buried in the monitoring well b. The detection device is used for detecting the resistivity of the area to be repaired.
In the application, an upper expansion body 121 and a lower expansion body 122 are respectively placed in an injection well a, and the upper expansion body 121 and the lower expansion body 122 are expanded and extruded with the inner wall of the injection well a to extrude soil body of a region to be repaired, when the repairing agent flows into a floral tube 123 from a liquid storage tank 11, the floral tube 123 horizontally sprays the repairing agent, the repairing agent flows in a stratum between the two expansion bodies, and the repairing of the polluted stratum of the region is realized; through moving the positions of the two expansion bodies in the vertical direction, the accurate control of the depth and the thickness of the repair layer is realized, and the fixed point, the fixed depth, the fixed quantity and the accurate repair of the heavy metal pollution site are convenient.
Simultaneously, two expansion bodies are utilized to inflate and expand and extrude stratum around the expansion bodies (the inner wall of the injection well), and then the expansion bodies are in close contact with the inner wall of the injection well, so that the repairing agent can only diffuse in the stratum between the two expansion bodies, uncontrollable migration of the repairing agent is avoided, and the diffusion range cannot be monitored.
Preferably, in the present embodiment, the upper expansion body 121 and the lower expansion body 122 are air bags, and the air bags can be inflated and deflated by inflation and deflation, so that construction and storage are facilitated.
Further, the injection device further comprises an air compressor 13 and a gas pressure controller 14, the air compressor 13 is communicated with the gas pressure controller 14 through a gas pipeline, at least two independently controlled pressure outlets are arranged on the gas pressure controller 14, one of the pressure outlets is communicated with the liquid storage tank 11, the other pressure outlets are respectively communicated with a plurality of expansion pipelines 124, and each expansion pipeline 124 is respectively communicated with an upper expansion body 121 and a lower expansion body 122 of one layer injection unit. The gas pressure control ensures that the two expansion bodies are fully extruded with the inner wall of the injection well a by controlling the inflation amount input into the two expansion bodies.
The liquid storage tank 11 is internally provided with another air bag, the air bag is positioned at the bottom of the liquid storage tank 11, and the repairing agent is filled in the liquid storage tank 11. Under the squeezing of the balloon, the healing agent flows into the flowtube 123 from the pipe above the reservoir 11 and is injected into the formation through the flowtube 123. Since the repairing agent is a suspension, precipitation is likely to occur, and therefore, when the gas pressure controller 14 controls the expansion of the airbag, the repairing agent can be agitated, which contributes to alleviating the phenomenon of precipitation and improving the repairing effect.
Further, the top of the liquid storage tank 11 is further provided with a charging valve and an exhaust hole, and the exhaust hole is in an open state during charging. The bottom of the liquid storage tank 11 is provided with a connecting flange, so that the liquid storage tank 11 is convenient to detach for cleaning.
Preferably, a pressure gauge and an expansion valve are provided on the expansion line 124 for sensing the gas pressure of the two expansion bodies to ensure that the two expansion bodies are in sufficient contact with the injection well a. A flow meter 125 and a flow valve and a flow pressure meter are provided between the reservoir 11 and the flowtube 123, the flow meter 125 being used to record the instantaneous flow and the cumulative flow of the restorative injection. The flow valve is used for controlling the on-off between the liquid storage tank 11 and the flower pipe 123, and the flow pressure gauge is closer to one side of the liquid storage tank 11 than the flow valve.
The foregoing detection device includes a high density resistivity meter 31 and a line 32, wherein the line 32 is in signal connection with the high density resistivity meter 31 and the line 32, and the line 32 is configured to be disposed at the injection well a, and ensures that the center of the line 32 is located at the center of the injection well a. The measuring line 32 is also provided with a plurality of electrodes 33 perpendicular to the measuring line 32, and the electrodes 33 are inserted into the soil layer of the area to be repaired during detection.
Preferably, a plurality of the measuring lines 32 are provided, and the plurality of measuring lines 32 are arranged radially at the center of the injection well a.
Preferably, the injection well a is circular in cross-section.
The integrated repairing equipment for heavy metal pollution site injection, monitoring and detection also comprises a central control device 4, wherein the central control device 4 is in signal connection with a pressure gauge, a flowmeter 125, a temperature and humidity sensor 21, a gas pressure controller 14, an air compressor 13 and a high-density resistivity meter 31.
The central control device 4 can control the power of each pressure outlet of the gas pressure sensor and record and plot the injection pressure as a function of time.
The central control device 4 can also record the instantaneous flow and the cumulative flow through the flow meter 125 and plot the flow over time.
Preferably, the diameter of the tube 123 is smaller than the diameter of the two expansion bodies before expansion, and the spray apertures on the sides of the tube 123 remain uniform and evenly distributed.
The temperature and humidity sensor 21 includes a probe and a wireless signal transmitter connected with the probe, and the wireless signal transmitter receives the signal of the probe and transmits the signal to the central control device 4. The probe is buried in the monitoring well b.
1-4 in combination with FIG. 5, the present application also provides a repair method, which adopts the foregoing repair device, comprising the following steps:
s1, before repairing a polluted site, detecting a region to be repaired, and obtaining the initial resistivity of the region to be repaired. The initial resistivity is obtained by a high density resistivity meter 31 and a wire 32.
S2, an injection well a and a monitoring well b are excavated, the injection well a and the monitoring well b are deep into a pollution layer, a plurality of monitoring wells b are distributed around the injection well a, the distances between the monitoring wells b and the injection well a are different, the depths of the monitoring wells b are different, and a temperature and humidity sensor 21 is buried in the monitoring well b to realize monitoring of all positions in a three-dimensional space around the injection well a.
The layered injection unit is lowered into injection well a.
S3, preparing a repairing agent. The repairing agent is bentonite suspension carrying kaolin loaded with nano zero-valent iron, and the bentonite is sodium modified bentonite.
In the conventional repairing agent, the kaolin loaded nano zero-valent iron is often mixed into water to form suspension serving as the repairing agent, but the repairing effect of the suspension prepared by water and the kaolin loaded nano zero-valent iron is poor.
And (5) checking the air tightness of the injection, monitoring and detection integrated repair equipment for the heavy metal pollution site. The detection of the air tightness comprises two aspects, namely the detection of the air tightness of the air circuit and the air tightness detection of the fluid pipeline. After the detection device is assembled, clear water is filled in the liquid storage tank 11, the air compressor 13 is opened, the two expansion bodies are inflated until the two expansion bodies are tightly extruded with the injection well a, the expansion valve is closed, the value change of the pressure gauge is observed, and after one end of time, the value of the pressure gauge is kept constant, so that the air tightness of the air channel is proved to be perfect. Further, maintaining the current pressure of the expansion body, closing the flow valve, and after a period of time, keeping the value of the flow pressure meter constant, so as to prove that the air tightness of the fluid pipeline is good.
After the repairing agent is prepared, the repairing agent is injected into the liquid storage tank 11 for standby.
S4, adjusting the expansion amplitude of the upper expansion body 121 and the lower expansion body 122 so that the upper expansion body 121 and the lower expansion body 122 are respectively in close contact with the inner wall of the injection well a, applying extrusion force to the inner wall of the injection well a, and maintaining the current extrusion force.
S5, injecting a repairing agent into a pollution layer between two expansion bodies through the pipe 123, and acquiring the time-dependent changes of the temperature and the humidity in each monitoring well b and the time-dependent changes of the injection quantity of the repairing agent in real time in the injection process.
S6, after the repairing agent is injected, detecting the area to be repaired to obtain the resistivity after the repairing.
After the injection is completed, the measuring lines 32 are respectively placed above the injection well a in 0h, 2h, 4h, 8h, 24h, 48h, 120h and 240h, the electrodes 33 are inserted into soil, the conductivity of the repair area is detected, the detection data before site repair are compared, and the diffusion and migration conditions of the loaded nano zero-valent iron are analyzed.
And periodically taking an underground water sample at the maximum influence range of the injection well a, and detecting the concentration of lead ions and zinc ions. And analyzing and evaluating the repairing effect by combining the monitoring data (pressure, flow and temperature and humidity change) with the detection data.
In the application, the mass ratio of the nano zero-valent iron in the kaolin loaded nano zero-valent iron is 25-33%. The mass ratio of bentonite in the suspension is 3%, and the mass ratio of K-nZVI is 0.2% -0.4%.
Example 1
In example 1, the restorative agent was prepared with bentonite and water in a mass ratio of 0%, 1%, 3%, 5%, and kaolin-loaded nano zero-valent iron (K-nZVI) and water in a mass ratio of 0.1%, 0.2%, 0.4%. Weighing water, bentonite and K-nZVI with corresponding masses according to a test scheme; adding bentonite into water for multiple times, and stirring the suspension at high speed for 5min; standing and hydrating the suspension for 24 hours; and finally, fully mixing the weighed K-nZVI with bentonite suspension, stirring at a high speed for 3min, carrying the bentonite suspension with the K-nZVI repairing agent to complete preparation, and then carrying out absorbance test. The stability of the restorative agent was evaluated in terms of the relative absorbance (absorbance at a certain time/initial absorbance) of the restorative agent for 4 hours of standing. The greater the relative absorbance, the more stable the healing agent system. The specific test protocols and results are shown in Table 1.
Table 1 relative absorbance of restoratives at different ratios after 4h
Note that: the bentonite to water ratio is zero, which means that no bentonite is added. The proportion of bentonite to water and the proportion of K-nZVI to water are independent of each other and do not affect each other.
As is clear from Table 1, K-nZVI settles faster in water without the addition of bentonite, and the absorbance drops to 30% of the initial value after about 4 hours. Through comparison, the dispersibility and stability of the K-nZVI particles can be effectively improved even though the bentonite is doped in a small amount, and the better the dispersibility and stability of the K-nZVI particles are, the more the bentonite is doped. According to Table 1, the bentonite content in the restoration agent should be 3% or more.
Example 2:
and carrying out viscosity test on the repairing agents with different proportions by adopting a rotational viscometer. Viscosity is an important index for representing rheological property of the repairing agent, and the lower the viscosity is, the stronger the injectability is. The specific test protocols and results are shown in Table 2.
TABLE 2 viscosity values of restoratives at different ratios
As can be seen from Table 2, both the bentonite and K-nZVI increase in the amount of the blended materials, which resulted in an increase in the viscosity of the restorative. The influence of bentonite on the viscosity of the repairing agent is more remarkable, and the influence of K-nZVI on the viscosity of the repairing agent is related to the blending amount of bentonite. When the bentonite doping amount is 5%, the viscosity of the repairing agent is increased by 1 time along with the increase of the K-nZVI doping amount; and when the bentonite mixing amount is 1% and 3%, the viscosity of the repairing agent increases smoothly along with the increase of the K-nZVI mixing amount, which shows that the K-nZVI has larger influence on the viscosity of the repairing agent with higher bentonite mixing amount. In addition, when the bentonite mixing amount is 5%, the repairing agent clay is suddenly increased, and the viscosity increasing rate is faster along with the increase of the K-nZVI mixing amount. In the method, the bentonite dosage in the repairing agent is preferably 3%, and the K-nZVI dosage is preferably 0.4%.
Example 3:
preparing 1000mg/L heavy metal lead and zinc ion solution according to bentonite: water 3%, K-nZVI: repair tests were performed with water at 0.4%. Wherein the ratio of nano zero-valent iron (nZVI) to Kaolin (Kaolin) in the K-nZVI is 1:0,1:4,1:3,1:2,2:3, respectively, and a set of control experiments with bentonite alone were set up. The pH of the test solution was not adjusted. The specific test protocols and results are shown in Table 3.
TABLE 3 heavy metal lead and zinc ion removal rate ((Re)
As can be seen from Table 3, the K-nZVI has a remarkable removal effect on heavy metal lead and zinc ions compared with pure bentonite and nZVI. The test results of comparing the ratios of nZVI and Kaolin to 1:0,1:4,1:3,1:2 and 2:3 show that the lead and zinc ions are removed more efficiently when the ratios of nZVI and Kaolin in the Kaolin-loaded nano zero-valent iron are 1:3 and 1:2. When the mass ratio of the two is 1:2, the removal rate is highest and is respectively 94.4% and 92.4%. In conclusion, the mass ratio of the nano zero-valent iron in the kaolin loaded nano zero-valent iron is preferably 25-33%.
The injection, monitoring and detection integrated repairing equipment and method for the heavy metal pollution site provided by the application have the advantages that 1) the injection, monitoring and repairing are automated by utilizing the injection device, the monitoring device detection device and the control device, the pressure, the flow and the temperature and humidity change of the stratum in the repairing agent injection process are stored and visually processed, the injection condition can be monitored remotely for 24 hours, and the injection parameters are adjusted according to the actual injection condition.
2) The injection, monitoring and detection integrated repair equipment for the heavy metal contaminated site can realize accurate control of the depth and thickness of a repair area through the combined use of the flower pipe 123 and the two expansion bodies, improves the controllability of the repair agent in the repair area, facilitates rapid detection after construction, and realizes fixed point, quantitative, depth fixing and accurate repair of the medium metal contaminated site.
3) The application also provides a proportioning of the repairing agent, which utilizes the bentonite suspension to have good carrying capacity, has the characteristics of heavy metal adsorption and reduction to configure the repairing agent, improves the stability of a repairing agent system, has a smaller viscosity value, reduces the resistance in the repairing injection process, can effectively increase the migration distance of nano zero-valent iron, reduces the deposition of nano zero-valent iron in an ocular soil layer, increases the diffusion radius of nano zero-valent iron in a polluted stratum, and achieves the purpose of strengthening transmission.
4) In the bentonite suspension carrying the kaolin loaded with the nano zero-valent iron, the sodium modification bentonite suspension carrying the kaolin loaded with the nano zero-valent iron is adopted, the kaolin loaded with the nano zero-valent iron can effectively solve the problem that the nano zero-valent iron is easy to agglomerate and oxidize, and the preparation of the sodium modification bentonite suspension carrying the nano zero-valent iron can reduce the sedimentation of the nano zero-valent iron in a repairing agent system. In addition, the sodium modified bentonite has a strong heavy metal adsorption effect, and the kaolin loaded with nano zero-valent iron has a strong reducibility, so that compared with the traditional nano zero-valent iron repairing agent, the method provided by the application has the advantages of higher heavy metal removal rate and better contaminated site repairing effect.
Compared with other nano zero-valent iron reinforced transmission materials, the sodium modified bentonite and kaolin used in the application are cheap and easy to obtain; compared with the traditional injection device, the device has high integration level, simple operation method and remote control; and the repairing effect is enhanced, and meanwhile, the repairing cost of a polluted site is saved.
While the foregoing is directed to the preferred embodiments of the present application, it will be appreciated by those skilled in the art that various modifications and adaptations can be made without departing from the principles of the present application, and such modifications and adaptations are intended to be comprehended within the scope of the present application.

Claims (9)

1. Injection, monitoring and detection integrated repair equipment for heavy metal contaminated sites, which is characterized by comprising:
the injection device comprises a liquid storage tank (11) and a plurality of layered injection units used for being placed in an injection well (a), wherein each layered injection unit comprises an upper expansion body (121) and a lower expansion body (122), a flower pipe (123) with a closed bottom end is arranged between the upper expansion body (121) and the lower expansion body (122), and the top end of the flower pipe (123) is communicated with the liquid storage tank (11);
the real-time monitoring device comprises a plurality of temperature and humidity sensors (21), wherein the temperature and humidity sensors (21) are used for being arranged in a monitoring well (b);
and the detection device is used for detecting the resistivity of the area to be repaired.
2. The integrated repair device for heavy metal contaminated site injection, monitoring and detection according to claim 1, wherein: the injection device further comprises an air compressor (13) and a gas pressure controller (14), wherein the gas pressure controller (14) is communicated with the air compressor (13) through a gas pipeline, at least two independently controlled pressure outlets are arranged on the gas pressure controller (14), one pressure outlet is communicated with the liquid storage tank (11), a plurality of expansion pipelines (124) are respectively communicated with the rest pressure outlets, and each expansion pipeline (124) is respectively communicated with an upper expansion body (121) and a lower expansion body (122) of one layered injection unit so as to control the expansion amplitude of the upper expansion body (121) and the lower expansion body (122) in the layered injection units;
an air bag is arranged in the liquid storage tank (11), and a pressure outlet communicated with the liquid storage tank (11) discharges injection liquid in the liquid storage tank (11) into the flower pipe (123) through controlling the expansion of the air bag.
3. The integrated repair device for heavy metal contaminated site injection, monitoring and detection according to claim 1, wherein: a pressure gauge is arranged on the expansion pipeline (124), and a flowmeter (125) is arranged between the liquid storage tank (11) and the flower pipe (123);
the detection device comprises a high-density resistivity meter (31) and a measuring line (32) connected with the high-density resistivity meter (31), wherein a plurality of electrodes (33) of vertical measuring lines (32) are arranged on the measuring line (32), the measuring line (32) is arranged at the injection well (a), the center of the measuring line (32) is positioned at the center of the injection well (a), and a plurality of measuring lines (32) are radially arranged;
the integrated repairing equipment for heavy metal pollution site injection, monitoring and detection further comprises a central control device (4), wherein the central control device (4) is in signal connection with the pressure gauge, the flowmeter (125), the temperature and humidity sensor (21), the gas pressure controller (14), the air compressor (13) and the high-density resistivity meter (31).
4. A repair method adopting the integrated repair equipment for heavy metal pollution site injection, monitoring and detection as claimed in claim 3, which is characterized by comprising the following steps:
s1, before repairing a polluted site, detecting a region to be repaired, and acquiring the initial resistivity of the region to be repaired;
s2, excavating an injection well (a) and a monitoring well (b), and respectively lowering a temperature and humidity sensor (21) and a layered injection unit into the monitoring well (b) and the injection well (a);
s3, preparing a repairing agent;
s4, adjusting the expansion amplitude of the upper expansion body (121) and the lower expansion body (122) so that the upper expansion body (121) and the lower expansion body (122) are respectively in close contact with the inner wall of the injection well (a);
s5, injecting a repairing agent into a pollution layer between the upper expansion body (121) and the lower expansion body (122) through a flowtube (123), and acquiring the change of the temperature and the humidity of each monitoring well (b) along with the time and the change of the injection quantity of the repairing agent along with the time in real time in the injection process;
s6, after the repairing agent is injected, detecting the area to be repaired to obtain the resistivity after the repairing.
5. The repair method according to claim 4, wherein: in step s2, the injection well (a) is deep to the contaminated layer, several monitoring wells (b) are laid around the injection well (a), and the diffusion depth and diffusion radius of the monitoring wells (b) are different.
6. The repair method according to claim 5, wherein: the repairing agent is bentonite suspension carrying kaolin loaded with nano zero-valent iron, and the bentonite is sodium modified bentonite.
7. The repair method according to claim 6, wherein: the mass ratio of the nano zero-valent iron in the kaolin loaded nano zero-valent iron is 25% -33%.
8. The repair method according to claim 6, wherein: the mass ratio of bentonite in the suspension is 3%, and the mass ratio of K-nZVI is 0.2% -0.4%.
9. The repair method according to claim 4, wherein: before step s4, the gas tightness inspection is carried out on the integrated repairing equipment for injecting, monitoring and detecting the heavy metal polluted site.
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