JP2014104425A - Soil purification method and soil purification apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil purification method which promotes vaporization of a contaminated material by sufficiently heating the contaminated material in soil, and also can efficiently remove the contaminated material.SOLUTION: In the soil purification method which purifies soil S by sucking a contaminated material that vaporizes in soil from a sucking well 2 provided in the soil, the soil S is heated by a heater 10 inserted into a heating well 3 provided in the soil, and air is injected into the soil through an injection well 4 provided in the soil.

Description

  The present invention relates to a soil purification method and a soil purification apparatus for purifying contaminated soil.

  When pollutants (VOC, oil, etc.) leaked from factory wastes flow into the groundwater, the groundwater is contaminated. In this case, contaminants often exist in the unsaturated zone soil above the groundwater surface at the same time as the groundwater contamination. Contaminants such as VOC present in the soil adversely affect the human body, so the soil must be purified by removing the contaminant as much as possible.

  As a conventional soil purification method, there is a method in which the soil is heated by a heat source provided in a heating well in the soil, and contaminants vaporized in the soil are removed by suction (Patent Document 1). There is also a method of injecting compressed air heated on the ground into unsaturated zone soil and removing the evaporated pollutants by suction (Patent Document 2).

JP-A-11-57685 JP-A-9-174033

  However, in the soil purification method described in Patent Document 1, when there is a poorly breathable part in the soil, it is not possible to suck all the pollutants evaporated in the soil and efficiently remove the pollutants. I couldn't.

  Moreover, since the soil purification method described in patent document 2 heats soil using the compressed air heated on the ground, when there is a variation in air permeability in the soil, a part with good air permeability and a bad part It was difficult to heat the soil uniformly due to the difference in the amount of air that was heated in. As a result, in the part with poor air permeability, the soil could not be heated sufficiently and the pollutants could not be sufficiently vaporized.

  In addition to this, in order to heat the air to a temperature at which the pollutants in the soil can be sufficiently vaporized, there is a problem that the air heating equipment installed on the ground becomes large. Depending on the installation location of the heating equipment, it may be difficult to increase the size of the equipment. In such a case, the air injected into the soil could not be heated sufficiently. As a result, the contaminants could not be sufficiently vaporized, and the soil contaminants could not be removed sufficiently.

  For example, in the soil purification method described in Patent Document 2, it is also conceivable that the medium injected into the soil is steam instead of air. However, when high-pressure steam is injected into the soil, there is a risk that the steam will erupt to the ground, or the pressure of the steam accumulated in the soil will rise and explode.

  In order to solve the above problems, the object of the present invention is to sufficiently heat the pollutants in the soil to promote vaporization of the pollutants and to efficiently remove the pollutants and the soil. It is to provide a purification device.

  In order to solve the above problems, according to the present invention, there is provided a soil purification method for purifying soil by sucking contaminants vaporized in the soil from a suction well provided in the soil, which is provided in the soil. There is provided a soil purification method characterized in that the soil is heated by a heater inserted into the heated well, and air is injected into the soil through an injection well provided in the soil.

  Moreover, you may immerse the lower end part of the said heating well in groundwater. Moreover, you may immerse the lower end part of the said injection well in groundwater.

  Further, a plurality of the heating wells may be provided, and each heating well may be arranged so as to surround the suction well. At this time, the distance between the hole center of each heating well and the hole center of the suction well may be made equal. Further, the angles formed by the straight lines connecting the hole centers of the respective heating wells and the hole centers of the suction wells may be equalized.

  Further, a plurality of the injection wells may be provided, and each injection well may be arranged so as to surround the suction well. At this time, the distance between the hole center of each injection well and the hole center of the suction well may be made equal. Further, the angles formed by the straight lines connecting the hole centers of the respective injection wells and the hole centers of the suction wells may be equalized.

  In addition, the ground surface may be covered with a shield that prevents the vaporized contaminants from flowing out.

  Moreover, in order to solve the said subject, according to this invention, it is a soil purification apparatus provided with the suction well which has the structure which can attract | suck the contaminant vaporized in soil, Comprising: The heating well provided in the soil, An injection well provided in the soil and configured to inject air into the soil, a suction pipe connected to the suction well for sucking the atmosphere in the suction well, and provided to be inserted into the heating well There is also provided a soil purification apparatus comprising a heater and an injection pipe for injecting air into the injection well.

  Moreover, the said soil purification apparatus WHEREIN: The lower end part of the said heating well may be provided so that it may be immersed in groundwater. Moreover, the lower end part of the said injection well may be provided so that it may be immersed in groundwater.

  Moreover, the said heating well may be provided with two or more, and each heating well may be arrange | positioned so that the said suction well may be enclosed. At this time, each heating well may be arranged so that the distance between the hole center of each heating well and the hole center of the suction well is equal. In addition, each heating well may be arranged so that the angles formed by the straight lines connecting the hole center of each heating well and the hole center of the suction well are equal.

  A plurality of the injection wells may be provided, and each injection well may be disposed so as to surround the suction well. At this time, each injection well may be arranged so that the distance between the hole center of each injection well and the hole center of the suction well is equal. Further, the respective injection wells may be arranged so that the angles formed by the straight lines connecting the hole centers of the respective injection wells and the hole centers of the suction wells are equal.

  In addition, a shield that prevents the vaporized contaminants from flowing out is provided, the shield is disposed so as to cover the ground surface, and the suction pipe and the injection tube are provided so as to penetrate the shield. Also good.

  According to the present invention, by providing a heater in the heating well, the soil is sufficiently heated to promote the vaporization of the pollutant, and the atmosphere in the soil is moved by injecting air into the injection well. Can be promoted. Thereby, the vaporized contaminant can be attracted | sucked reliably and the purification | cleaning efficiency of soil can be improved.

It is a schematic plan view which shows arrangement | positioning of each well in the soil purification apparatus which concerns on embodiment of this invention. It is AA sectional drawing in FIG. It is a figure which shows the modification of this invention. It is a figure which shows the investigation method of the heating range of a heating well. It is a result which shows the heating range of a heating well. It is a figure which shows the change of groundwater temperature at the time of making the lower end part of a heating well immersed in groundwater. It is a figure which shows the collection | recovery capability of the contaminant which concerns on the modification of this invention. It is a figure which shows the removal state of the simulated contaminated soil and simulated contaminated water with respect to the air flow.

  Hereinafter, an embodiment of the present invention will be described based on a soil purification apparatus 1 that purifies soil S contaminated with a pollutant. Note that the contaminant in the present embodiment is oil (for example, kerosene or light oil), VOC, or the like. In the present specification and drawings, elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description is omitted.

  As shown in FIGS. 1 and 2, the soil purification apparatus 1 includes a suction well 2 that sucks an atmosphere in the soil, a heating well 3 that heats the soil S, and an injection well 4 that injects compressed air into the soil. Is done. Here, the “well” in the present invention refers to a material in which a tubular (for example, circular or rectangular) metal member is inserted into a hole formed in soil. In addition, the shape of the well in this Embodiment employ | adopted the thing of the circular tube shape as an example. Further, as the material of the metal member, it is preferable to employ a corrosion-resistant material such as stainless steel.

  As shown in FIG. 1, six heating wells 3 and six injection wells 4 are provided so as to surround the periphery of the suction well 2. Each heating well 3 and each injection well 4 are arranged on the top and sides of a regular hexagon centering on the suction well 2 in plan view, and each heating well 3 is placed on the top of the regular hexagon, Each injection well 4 is arranged at the midpoint of the side of the regular hexagon.

  That is, the distance between the hole center of each heating well 3 and the hole center of the suction well 2 is equal, and the angles formed by the straight lines connecting the hole center of each heating well 3 and the hole center of the suction well 2 are equal to each other. Are arranged as follows. In addition, it is preferable that the distance of the hole center of each heating well 3 and the hole center of the suction well 2 is 1.5 m or less. Similarly, the distance between the hole center of each injection well 4 and the hole center of the suction well 2 is equal, and the angles formed by the straight lines connecting the hole center of each injection well 4 and the hole center of the suction well 2 are equal to each other. It is arranged to be. The center of the hole refers to the central axis of the circular tube if the well shape is a circular tube shape, and the tube axis passing through the intersection of diagonal lines if the shape of the well is a rectangular tube shape.

  As shown in FIG. 2, the suction well 2 is provided so as to be embedded in the soil along a substantially vertical direction, and a suction pipe 5 that sucks the atmosphere in the suction well is connected to the suction well 2. Yes. This suction pipe 5 is connected via a vacuum pump 6 to a contaminant treatment device 7 that purifies the contaminant. The suction well 2 has an airtight structure except for the lower end 8. A small-diameter hole (not shown) through which the atmosphere in the soil can pass is formed at the lower end 8 of the suction well 2, and the periphery of the hole is covered with a strainer 9. In addition, although the suction pressure of the vacuum pump 6 is changed as appropriate, it is, for example, −0.1 MPa to −0.4 MPa.

  Each heating well 3 is provided so as to be embedded in the soil along a substantially vertical direction, and a heater 10 for heating the soil S is inserted into each heating well 3 in each heating well 3. Is provided. The installation depth of the heater 10 is configured to be arbitrarily changed, and the electric wire 11 connected to the heater 10 is connected to the temperature controller 12. A thermocouple 13 is provided at the lower end of the heater 10 to measure the temperature of the heater 10. Each heating well 3 has an airtight structure in the soil.

  In addition, the length of the heater 10 and the electric wire 11 inserted in the heating well 3 is appropriately changed according to the depth of the heating well 3. Moreover, although the capability of the heater 10 is also suitably changed according to the purification time of the soil S, the arrangement state of each well, etc., it is 2.5 kwh / m, for example, and the heater 10 is about 300 ° C. to 600 ° C. It is preferable that heat can be generated.

Each injection well 4 is provided so as to be embedded in soil along a substantially vertical direction, and an injection tube 14 for injecting compressed air into each injection well 4 is provided in the vicinity of the ground surface GL in each injection well. Is provided. The injection pipe 14 is connected to a compressor 17 via a regulator 15 and a flow meter 16. Each injection well 4 has an airtight structure except for the lower end 18 in the soil. A small-diameter hole (not shown) through which compressed air can pass is formed in the lower end portion 18 of each injection well 4, and the periphery of the hole is covered with a strainer 9. The air injection amount is appropriately changed depending on the air permeability of the soil S to be purified, the arrangement state of each well, and the like, for example, 30 L / min to 50 L / min with respect to 1 m ^{3 of} soil. .

  A soil purification method using the soil purification apparatus 1 configured as described above will be described.

  First, the atmosphere in the suction well 2 is sucked from the suction pipe 5 connected to the suction well 2 by operating the vacuum pump 6 shown in FIG. Thereby, since the pressure in the suction well becomes a negative pressure with respect to the atmosphere of the soil S around the suction well 2, the small diameter hole (not shown) formed in the lower end portion 8 of the suction well 2 is used. Thus, the atmosphere in the soil flows into the suction well. That is, the atmosphere in the soil is sucked by the suction well 2. The suction range of the atmosphere in the soil at this time is not limited to the atmosphere in the vicinity of the lower end portion 8 of the suction well 2, but extends to the entire soil to be purified.

  Next, the heater 10 inserted in each heating well 3 is operated. The heat of the heater 10 is transmitted to the whole heating well and raises the temperature of the soil S around each heating well 3. At this time, as shown in FIG. 1, each heating well 3 is provided on the top of a regular hexagon centering on the suction well 2 in a plan view, so that the soil S surrounded by each heating well 3 is , Uniformly heated. At this time, depending on the depth of the soil to be purified, there may be a portion that is not sufficiently heated. In that case, the installation depth of the heater 10 may be changed. Thereby, the soil S to be purified can be sufficiently heated.

  Moreover, since the range (heating range) in which the heat generated from each heating well 3 affects is expanded in a circle around each heating well 3, the heating range of each heating well 3 arranged so as to surround the suction well 2 is Duplicate. Thereby, a heating capability increases in the part which a heating range overlaps, and the soil S enclosed by each heating well 3 can be heated efficiently. As a result of heating the soil S by each heating well 3, the contaminant contained in the soil S is vaporized.

  Next, the compressor 17 is operated. The pressure of the air compressed by the compressor 17 is adjusted by the regulator 15 and is injected from the injection pipes 14 to the injection wells 4. The injected compressed air flows through the gaps in the soil S regardless of whether the air permeability of the soil S is good or bad. Thereby, the movement of the atmosphere of the poorly breathable portion in the soil can be promoted, and the vaporized contaminant does not stay in the poorly breathable portion of the soil. As a result, all the pollutants evaporated in the soil can be sucked by the suction well 2, and the pollutants can be efficiently removed.

  Moreover, as shown in FIG. 1, since each injection well 4 is arrange | positioned so that the suction well 2 may be enclosed, compressed air can be uniformly inject | poured with respect to the soil S enclosed by each injection well 4. As shown in FIG. Thereby, the atmosphere in soil can be moved efficiently.

  The contaminant sucked into the suction well 2 flows into the contaminant treatment device 7 through the suction pipe 5. In this pollutant processing apparatus 7, the pollutant is rendered harmless and released to the atmosphere. As described above, the contaminated soil S is purified.

  As described above, according to the present invention, by providing a heater in each heating well, the soil is sufficiently heated to promote the vaporization of pollutants, and by injecting compressed air into each injection well, The movement of the atmosphere can be promoted. Thereby, the vaporized contaminant can be attracted | sucked reliably and the purification | cleaning efficiency of soil can be improved.

  Moreover, in the conventional purification apparatus which inject | pours heated air, it was difficult to heat the temperature of heated air to 300 to 600 degreeC which is the heat_generation | fever temperature of the heater which this invention illustrates. In addition to this, when heated air is injected into the heated well, the temperature of the heated air decreases in the heated well, and the soil may not be heated sufficiently. On the other hand, in the present invention, the heater having a temperature that cannot be reached by heated air is provided in the heating well, so that the soil temperature after heating can be made higher than before, and the temperature in the heating well The decrease can also be suppressed. As a result, the soil can be sufficiently heated and the vaporization of the pollutant can be promoted.

  Moreover, in this invention, since the heater was provided in the heating well, the conventional large-sized heating equipment for injecting heated air becomes unnecessary. Furthermore, since the heater can be reused, the soil purification apparatus can be easily moved. For this reason, the removal of the soil purification apparatus after completion of purification, and the re-installation to a different soil which cannot be achieved with the conventional soil purification apparatus can be easily performed.

  As mentioned above, although preferred embodiment of this invention was described, this invention is not limited to this example. It is obvious for those skilled in the art that various changes or modifications can be conceived within the scope of the technical idea described in the claims. It is understood that it belongs to.

  For example, in the embodiment of the present invention, six heating wells and six injection wells are provided, but the number of each well is not limited to this, depending on the size of the soil to be purified, etc. It is changed as appropriate. In the embodiment of the present invention, the heating wells and the injection wells are arranged on the apexes and sides of the regular hexagon centering on the suction well, but the arrangement of the wells is not limited to this. If it is the structure which arrange | positions a heating well and an injection well so that a suction well may be enclosed, the effect demonstrated in this Embodiment can be enjoyed. The shape of each well is not limited to a circular tube shape, and may be a square tube shape or other shapes. That is, what inserts a tubular metal member in the hole formed in soil belongs to the technical scope of the present invention.

  In addition, for example, in the embodiment of the present invention, each heating well 3 is provided in the soil, but the installation depth of each heating well 3 is further reduced, and as shown in FIG. You may immerse a lower end part in groundwater GW. In this case, the temperature of the groundwater GW can also be raised by the heat generated from each heating well 3. Thereby, the contaminant in groundwater can be vaporized together with the contaminant in soil. That is, according to the present invention having such a configuration, not only soil but also groundwater contamination can be purified.

  Moreover, as shown in FIG. 3, you may immerse the lower end part 18 of each injection well 4 in the groundwater GW. In this case, since the injection depth of the compressed air is lowered, the diffusion range of the injected air is expanded, and the compressed air can be fed into a wider range of soil S. In addition, when compressed air is injected into the groundwater, the effect of purifying contaminants due to the microbial activity can be expected.

  Moreover, as shown in FIG. 3, you may make it cover the ground surface GL of the soil S used as the purification | cleaning object using the shielding 20 which prevents the outflow of the vaporized contaminant. In this case, the suction pipe 5 and the injection pipe 14 are connected to the suction well 2 and the injection well 4 so as to penetrate the shield 20. When the ground surface GL is covered with the shield 20 in this way, it is possible to prevent the vaporized pollutant that has flowed out of the ground surface GL during the soil purification from flowing out to the atmosphere. The vaporized contaminants existing between the ground surface GL and the shield 20 return to the soil through the ground surface GL or the injection well 4 and are sucked from the suction well 2. Moreover, the shielding object 20 is concrete, for example.

  Moreover, it is preferable that the outer surface of the metal member which comprises each well and the inner surface of the hole formed in soil are closely_contact | adhered. When the outer surface of the metal member constituting the suction well is in close contact with the inner surface of the hole, when the atmosphere in the soil is sucked from the lower end of the suction well, the space between the outer surface of the metal member and the inner surface of the hole is The atmospheric atmosphere from the ground surface does not enter the formed gap. As a result, only the atmosphere in the soil can be efficiently sucked by the suction well. Further, when the outer surface of the metal member constituting the heating well is in close contact with the inner surface of the hole, the atmospheric atmosphere from the ground surface does not enter the gap formed between the outer surface of the metal member and the inner surface of the hole. . As a result, the heat of the heating well can be directly transmitted to the soil, and the soil can be efficiently heated. In addition, when the outer surface of the metal member constituting the injection well is in close contact with the inner surface of the hole, the air injected into the soil from the lower end of the injection well is between the outer surface of the metal member and the inner surface of the hole. It will not leak to the ground surface through the formed gap. As a result, air can be efficiently injected into the soil by the injection well.

Example 1
The heat transfer range (heating range) generated by the heating well according to the present invention was investigated. As shown in FIG. 4, the investigation was conducted in the field by providing measurement wells at positions 0.5 m, 1.0 m, 2.0 m, and 3.0 m from the hole center of the heating well. In each measurement well, 0.2 m (GL.-0.2 m), 1.0 m (GL.-1.0 m), 2.0 m (GL.-2.0 m), 3.0 m from the ground surface. A thermocouple is attached at the position (GL.-3.0 m). The heater in the heating well was operated with such a configuration, and the relationship between elapsed time and soil temperature was measured. The results are shown in FIG. In addition, the heater used for the field survey used the capacity | capacitance of 2.5 kwh / m and a length of 1.0 m.

  According to FIG. 5, it can be seen that as the distance from the heating well increases, the influence of the heating well heat decreases. When the distance from the heating well is 2.0 m and 3.0 m, there is almost no difference in the measurement results. Therefore, when the distance from the heating well is 2.0 m, it is not already affected by the heat of the heating well. It is considered a thing. For this reason, the upper limit of the heating range of the heating well is determined by considering the attenuation of the effect of heat on the soil when the measurement results of the distance from the heating well are 0.5 m, 1.0 m, and 2.0 m are compared. It can be said that the distance from is 1.5 m.

(Example 2)
Next, the temperature change of the groundwater when the heated well was immersed in the groundwater was investigated. The investigation was conducted in the field, and as shown in FIG. 6, the heating well 3 was arranged on the apex of the equilateral triangle so as to surround the suction well 2. As a result of heating the heating well, the groundwater surrounded by the three heating wells could be heated almost uniformly.

(Example 3)
Next, kerosene was collected at the site where kerosene leaked into the groundwater. In the initial stage of recovery, recovery was performed only with pumped water, and then recovery was performed according to the present invention. The results are shown in FIG. In addition, arrangement | positioning of each well was the same as that of Example 2, and the suction pressure of the suction well 2 was made into -0.2MPa. As shown in FIG. 7, in the recovery using only pumped water, the recovery amount of kerosene decreased with the elapsed days, and after 100 days, the recovery amount of kerosene was almost flat. Thereafter, the heating well 3 was heated to raise the groundwater temperature, and then suctioned by the suction well 2, the amount of kerosene recovered increased, and after 200 days, all kerosene could be recovered. That is, according to the present invention, it is possible to remove contaminants that cannot be removed by the conventional purification apparatus.

Example 4
Next, the relationship between the air flow rate of the air injected into the simulated test soil and the TCE concentration was investigated using simulated test soil and simulated test groundwater containing TCE (trichlorethylene). The simulated test soil and the simulated test groundwater are obtained by curing soil and water containing TCE for one month. The aeration time was 3 hours, and the temperature of the simulated test soil during the test and the temperature of the simulated test groundwater were constant. Such a test was performed three times while changing the temperature conditions.

The change in the TCE concentration in the soil is shown in FIG. 8A, and the change in the TCE concentration in the simulated test groundwater is shown in FIG. 8B. The vertical axis shown in FIG. 8 is the ratio between the concentration C of TCE remaining in the simulated test soil or the simulated test ground water and the initial concentration C _{0 of} TCE. The horizontal axis shown in FIG. 8 is the ratio of the volume of air to be injected and the volume of the simulated test soil. Means that.

  According to FIG. 8A and FIG. 8B, it can be seen that the TCE concentration rapidly decreases by increasing the air flow rate. The tendency becomes more prominent as the temperature is higher. That is, it can be seen that if the soil is sufficiently heated as in the present invention and compressed air is injected into the soil, the pollutants can be efficiently removed.

  The present invention can be applied to a soil purification method and a soil purification apparatus for purifying soil contaminated with pollutants.

DESCRIPTION OF SYMBOLS 1 Soil purification apparatus 2 Suction well 3 Heating well 4 Injection well 5 Suction pipe 6 Vacuum pump 7 Contaminant processing apparatus 8 Suction well lower end part 9 Strainer 10 Heater 11 Electric wire 12 Temperature controller 13 Thermocouple 14 Injection pipe 15 Regulator 16 Flow meter 17 Compressor 18 Lower end of injection well 19 Lower end of heating well 20 Shield S Soil GL Ground surface GW Groundwater

Claims (20)

A soil purification method for purifying soil by sucking contaminants vaporized in the soil from a suction well provided in the soil,
The soil is heated by a heater inserted in a heating well provided in the soil,
A soil purification method comprising injecting air into soil through an injection well provided in the soil.   The soil purification method according to claim 1, wherein a lower end portion of the heating well is immersed in groundwater.   The soil purification method according to claim 1 or 2, wherein a lower end portion of the injection well is immersed in groundwater.   The soil purification method according to any one of claims 1 to 3, wherein a plurality of the heating wells are provided, and each heating well is disposed so as to surround the suction well.   The soil purification method according to claim 4, wherein the distance between the hole center of each heating well and the hole center of the suction well is made equal.   The soil purification method according to claim 4 or 5, wherein angles formed by straight lines connecting the hole center of each heating well and the hole center of the suction well are made equal to each other.   The soil purification method according to any one of claims 1 to 6, wherein a plurality of the injection wells are provided and the injection wells are arranged so as to surround the suction well.   The soil purification method according to claim 7, wherein the distance between the center of each injection well and the center of the suction well is made equal.   The soil purification method according to claim 7 or 8, wherein angles formed by straight lines connecting the hole centers of the injection wells and the hole centers of the suction wells are made equal to each other.   The soil purification method according to any one of claims 1 to 9, wherein the ground surface is covered with a shield that prevents the vaporized pollutant from flowing out. A soil purification apparatus comprising a suction well having a configuration capable of sucking contaminants vaporized in soil,
A heating well provided in the soil;
An injection well provided in the soil and having a configuration capable of injecting air into the soil;
A suction pipe connected to the suction well for sucking the atmosphere in the suction well;
A heater provided to be inserted into the heating well;
A soil purification apparatus comprising an injection pipe for injecting air into the injection well.   The soil purification apparatus according to claim 11, wherein a lower end portion of the heating well is provided so as to be immersed in groundwater.   The soil purification apparatus according to claim 11 or 12, wherein a lower end portion of the injection well is provided so as to be immersed in groundwater.   The soil purification apparatus according to any one of claims 11 to 13, wherein a plurality of the heating wells are provided, and each heating well is disposed so as to surround the suction well.   The soil purification apparatus according to claim 14, wherein each heating well is disposed so that a distance between a hole center of each heating well and a hole center of the suction well is equal.   16. Each heating well is arrange | positioned so that the angle | corner which the straight line which ties the hole center of each heating well and the hole center of the said suction well makes becomes equal, respectively. Soil purification device.   The soil purification apparatus according to any one of claims 11 to 16, wherein a plurality of the injection wells are provided, and each injection well is disposed so as to surround the suction well.   18. The soil purification apparatus according to claim 17, wherein each of the injection wells is disposed so that a distance between a hole center of each injection well and a hole center of the suction well is equal.   19. The injection wells according to claim 17, wherein the injection wells are arranged so that angles formed by straight lines connecting the hole centers of the injection wells and the hole centers of the suction wells are equal to each other. Soil purification device. It is provided with a shield that prevents the vaporized pollutant from flowing out, the shield is disposed so as to cover the ground surface, and the suction pipe and the injection tube are provided so as to penetrate the shield. The soil purification apparatus according to any one of claims 11 to 19, characterized in that