JP4657008B2 - Contaminated ground purification system and purification method of contaminated ground - Google Patents

Description

  The present invention relates to a system and method for cleaning soil contaminated with volatile organic compounds (VOC).

  VOCs such as trichlorethylene, tetrachloroethylene, formaldehyde, toluene, benzene, and xylene have been widely used as ideal cleaning agents since around 1970 because of their high ability to dissolve oils and fats, and they are difficult to decompose, stable and difficult to burn. ing. However, this VOC causes headache and dizziness by inhalation, and has been pointed out as harmful and carcinogenic, such as kidney injury, and soil contamination and groundwater contamination due to disposal of this detergent into soil and rivers has become a problem. ing.

  As a method for purifying groundwater contaminated by VOCs, a groundwater pumping method is adopted. In this groundwater pumping method, a well is dug or a suction pipe is inserted, groundwater melted by the VOC is pumped up using a submersible pump, blown up using a blower, etc., and dissolved in the groundwater. Is gasified and separated and adsorbed on an adsorbent such as activated carbon and recovered.

  Further, a gas suction method is adopted as a method for purifying soil contaminated with VOCs. This gas suction method is a method in which a well is dug or a suction pipe is inserted, and a gas existing between soil particles or a gas attached to the soil particles is sucked using a vacuum pump.

  In the groundwater pumping method using the submersible pump described above, a dynamic water gradient is generated on the groundwater surface due to the difference between the groundwater level around the borehole or suction pipe and the water level in the well or suction pipe. Or, because water is collected in the suction pipe and sucked up, the range and amount of water that can be collected by only one well or suction pipe is limited, and it is necessary to install a large number of wells or suction pipes. There is. In addition, the water collection rate also decreases with a decrease in the water level, and there is a problem that it takes a long time of 1 to 10 years to pump up and purify everything. In addition, there are long-term maintenance and cost problems associated with pumps such as submersible pumps. In this groundwater pumping method, the groundwater level in the ground is lowered by lowering the groundwater surface in the ground to expand the unsaturated ground area, especially when suctioned using a vacuum well. Becomes larger and expands the unsaturated ground area more. This unsaturated ground region contains a large amount of VOC gas, and in order to remove this VOC gas, a gas suction method must be used in combination. Further, in the groundwater pumping method, since only contaminated groundwater is purified, in order to remove VOC gas in the soil and purify the soil, a gas suction method must be used.

  In the ground contaminated by VOC, both soil and groundwater are often contaminated, and in order to purify both of them, a method using a groundwater pumping method and a gas suction method has been proposed (for example, patent document). 1). In this method, a pumping well and a gas suction well are provided on the contaminated ground, the groundwater is pumped up, and the gas is sucked from the soil gap.

  Although this method of simultaneously pumping groundwater and sucking gas can simultaneously purify contaminated groundwater and contaminated soil, it can collect water with an underwater pump as described above. There is a problem that the range and the amount of water are limited, and it takes a long time. Therefore, a gas-liquid mixed extraction method has been proposed in which gas in soil and groundwater are simultaneously pumped and sucked using a vacuum pump (see, for example, Patent Document 2).

  FIG. 1 is a diagram illustrating an apparatus for performing a gas-liquid mixed extraction method. This apparatus is connected to a plurality of suction wells 11 provided on the ground 10, a gas-liquid separator 12 connected to the suction well 11, a vacuum pump 13 connected to the gas-liquid separator 12, and a vacuum pump 13. And an adsorption tower 14. The ground 10 has an impermeable layer 15 and an aquifer thereon, and the suction well 11 is provided so as to extend to the impermeable layer 15. When the vacuum pump 13 is activated, the groundwater 16 and gas in the aquifer in the ground 10 are sucked through the suction well 11. In the suction well 11, the ground water 16 and the gas are mixed and sent to the gas-liquid separator 12, where the gas-liquid separator 12 separates the gas and water containing VOC.

  The separated water contains a small amount of dissolved VOC, heavy metal, and the like, and is sent to a water treatment device (not shown) in order to treat these. The separated gas containing VOC is sent to the adsorption tower 14 through the vacuum pump 13. The adsorption tower 14 is filled with an adsorbent 17 such as activated carbon, and contaminants such as VOC in the gas are adsorbed and removed and diffused into the atmosphere.

Although the gas-liquid mixed extraction method has the advantage that VOC contained in groundwater and VOC contained in soil can be simultaneously removed by suction, there is a limitation on the head of the vacuum pump 13, and in general, groundwater The depth is 6-7m. In the case of groundwater contamination, there are many cases where the contamination by VOC reaches a depth of 7 m or more, and there is a problem that groundwater and gas cannot be sucked simultaneously at a depth of 7 m or more.
JP 2002-119951 A JP 2001-54784 A

  In view of the above problems, an object of the present invention is to provide a system and method capable of efficiently purifying a groundwater and soil range contaminated by VOCs over a wide area and in a short period of time.

The said subject is achieved by providing the ground purification method of this invention. That is, according to the invention of claim 1 of the present invention, the suction means for sucking the gas,
Pumping means for pumping groundwater contaminated by VOCs;
The upper end is connected to the suction means, the lower end opening is closed, the first pipe having a gas suction port on the side, the upper end is connected to the suction means, the lower end opening is closed, and the first pipe is closed A second pipe having a groundwater suction port on the exposed lower side surface, and a third pipe installed in the second pipe and connected to the pumping means at the lower end. A triple pipe installed in the ground contaminated by the VOC,
The suction means sucks the inside of the second pipe, allows the ground water contaminated by the VOC to flow into the second pipe through the ground water suction port, sucks the inside of the first pipe, and A polluted ground purification system is provided, in which gas contaminated with the VOC flows into the first pipe through a suction port.

  According to the second aspect of the present invention, there is provided a contaminated ground purification system including an aeration treatment device for aeration treatment of the groundwater pumped by the pumping means.

  According to the third aspect of the present invention, there is provided a contaminated ground purification system including an adsorption device filled with an adsorbent that adsorbs the VOC contained in the gas introduced into the first pipe.

  According to the fourth aspect of the present invention, there is provided a contaminated ground purification system including a gas-liquid separation device for separating moisture contained in the gas flowing into the first pipe.

  According to the invention of claim 5 of the present invention, the gas suction port is composed of a plurality of air holes, and the open area ratio of the side surface of the first pipe is 10 to 20%. A system is provided.

  According to the invention of claim 6 of the present invention, the groundwater suction port is composed of a plurality of water holes, and is provided on the lower end side surface of the second pipe, and the opening ratio of the lower end side surface. A contaminated ground purification system is provided in which 10 to 20%.

  According to the seventh aspect of the present invention, there is provided a contaminated ground purification system including a detecting means disposed on the outer surface of the first pipe and detecting a groundwater surface.

  According to the eighth aspect of the present invention, there is provided a contaminated ground purification system including a strainer pipe which is disposed so as to cover the lower side surface of the second pipe and is capable of passing water and blocking gas. Provided.

According to the invention of claim 9 of the present invention, in the ground contaminated by VOC, the upper end is connected to the suction means, the lower end opening is closed, the first pipe having the gas suction port on the side surface, and the upper end is A second pipe connected to the suction means, having a lower end opening closed, penetrating the closed lower end of the first pipe, and having a groundwater suction port on a lower side surface exposed to the ground; and the second pipe A step of installing a triple pipe having a third pipe installed in the pipe and having a third pipe with a pumping means connected to the lower end;
A step of sucking the inside of the second pipe by the suction means, and allowing the groundwater contaminated by the VOC to flow into the second pipe through the groundwater suction port;
Pumping the groundwater by the pumping means;
And a step of sucking the inside of the first pipe by the suction means and causing the gas contaminated by the VOC to flow into the first pipe through the gas suction port.

  According to invention of Claim 10 of this invention, the purification method of the contaminated ground which further includes the process of carrying out the aeration process of the discharged | emitted groundwater is provided.

  According to the eleventh aspect of the present invention, there is provided a method for purifying contaminated ground, further comprising a step of adsorbing the VOC contained in the gas flowing into the first pipe onto an adsorbent.

  According to the twelfth aspect of the present invention, there is provided a method for purifying a contaminated ground, comprising a step of separating moisture contained in the gas flowing into the first pipe before the step of adsorbing to the adsorbent. Provided.

  According to a thirteenth aspect of the present invention, the outer surface of the first pipe is provided with a detecting means for detecting a groundwater surface, and the gas is introduced after the detecting means no longer detects the groundwater surface. There is provided a method for purifying contaminated ground, which performs the step of causing the contamination to occur.

  By providing the contaminated ground purification system and method of the present invention, not only groundwater contaminated by VOC but also VOC staying in the soil as gas can be recovered at the same time, and purification of soil contaminated by VOC can be performed. Efficient and short-term construction is possible. Since the inside of the pipe is decompressed by the suction means and pumped by the pumping means, deeper formation can be purified. In addition, since the gas suction port is provided on the side surface of the first pipe, a wide range of purification is possible, the number of injection wells can be reduced, and the ground water suction port is provided on the lower side surface of the second pipe. It is possible to reduce the inflow of gas that lowers the pumping efficiency of the pumping means, and pump and discharge efficiently.

  The present invention will be described in detail with reference to the drawings, but the system and method of the present invention are not limited to the embodiments shown in the drawings. FIG. 2 shows an outline of the contaminated ground purification system of the present invention. The contaminated ground purification system of the present invention is a system particularly suitable for purifying soil contaminated with VOCs.

  Examples of VOCs include trichloroethylene, tetrachloroethylene, formaldehyde, toluene, benzene, xylene and the like. This VOC exists in groundwater and soil, and pollutes groundwater and soil. The system of the present invention can simultaneously purify contaminated groundwater and soil by sucking VOCs present in a wide range of soils, pumping and discharging groundwater, and enabling deeper formations. In addition, it enables construction in a short period of time.

  The system of the present invention includes a suction means 20 for sucking air, steam, carbon dioxide gas, VOC and other gases, a pumping means 22 for pumping groundwater 21 contaminated by VOC to the ground, and a ground 23 contaminated by VOC. It is comprised including the triple tube installed in. The triple pipe can be installed by drilling the ground 23 using a drilling machine or a drilling machine, and inserting it into the hole.

  The triple tube has a first tube 27 having an upper end connected to the suction means 20 via a line 24, a lower end opening closed by an adhesive, a solidifying material 25, and the like, and a gas suction port 26 on a side surface. 28, the lower end opening is closed by a closing member 29 such as a cap, passes through the closed lower end of the first pipe 27, and sucks groundwater into the lower side surface exposed to the ground 23. It is comprised from the 2nd pipe | tube 31 provided with the opening | mouth 30, and the 3rd pipe | tube 32 which is installed in the 2nd pipe | tube 31 and the pumping means 22 is connected to a lower end.

  The gas suction port 26 provided on the side surface of the first pipe 27 is composed of a plurality of holes, and allows gas contained in the adjacent soil to flow in. More specifically, the gas inside the first pipe 27 is sucked by the suction means 20 connected to the first pipe 27 and the inside of the first pipe 27 is decompressed, so that the outside of the first pipe 27 is removed. The gas contained in the soil is sucked into the side surface of the first tube 27 and flows through the plurality of holes. Similarly to the gas suction port 26, the groundwater suction port 30 provided on the lower side surface of the second pipe 31 is composed of a plurality of holes, but the groundwater suction port 30 is located at a deeper position than the gas suction port 26. Since it arrange | positions in a layer, the groundwater 21 in the ground 23 can be made to flow in.

  In the present invention, a hole is not provided in the side surface of the second pipe 31 that overlaps the first pipe 27, and the second pipe 31 that is longer than the first pipe 27 does not overlap with each other. By providing a hole only in the lower side surface of the deep position, it is possible to reduce the inflow of gas through the hole and prevent the pumping efficiency of the pumping means 22 from being lowered.

  The suction means 20 that sucks the gas may be a vacuum pump, for example. The pumping means 22 can be a submersible pump capable of pumping water by being immersed in the groundwater 21. These pumps can be used with appropriate capacities according to the diameter of each pipe, the amount of water to be treated, and the amount of gas. The triple tube has a diameter in the order of the third tube 32, the second tube 31, and the first tube 27, and the first tube 27, the third tube 32, and the second tube 31 in this order. Each of the lengths is adopted, the second pipe 31 is disposed so as to be inserted into the first pipe 27, and the third pipe 32 connected with the pumping means 22 is inserted into the second pipe 31. It is assumed that it was set up.

  The triple tube can be formed as follows. For example, after digging, first, the second pipe 31 whose lower end opening is closed with a cap is inserted, and the lower end side surface is filled with earth and sand, preferably bean gravel. Next, the solidified material 25 such as an adhesive or mortar is filled on the earth and sand, and the first tube 27 is embedded around the second tube 31 and the lower end is embedded in the adhesive or the solidified material 25. Place. The adhesive or solidifying material 25 hardens or solidifies over time, and completely closes the lower end opening of the first tube 27. Next, the lower end of the third pipe 32 and the nozzle of the pumping means 22 are connected and inserted into the second pipe 31. The upper end of the second pipe 31 is provided with a nozzle for enabling connection to the suction means 20 and is closed by a closing plate 33 on which the third pipe 32 is disposed, and the upper end of the first pipe 27 is , The nozzle connected to the nozzle, the nozzle connected to the third pipe 32, and the two nozzles connected to the lines 24 and 28, are closed by a closing plate 34 having a total of four nozzles. The closing plates 33 and 34 are placed on the upper end of the second tube 31 and the flange portion at the upper end of the first tube 27, and fastened by using fastening means such as bolts and nuts. The tube 27 and the second tube 31 can be closed. Thus, the upper end of each pipe | tube is closed with the closing plates 33 and 34, a triple pipe can be formed and installed in a hole. In the embodiment shown in FIG. 2, a flange portion is provided at the upper end of the second pipe 31 and is closed by the closing plate 33. In order to accommodate the flange portion and the closing plate 33, The upper portion of the tube 27 is expanded, and a ridge 35 is formed to accommodate the upper portion. The nozzles provided on the closing plate 33 and the nozzles provided on the closing plate 34 can be connected to each other, for example, by fitting them. When the nozzles are connected to each other, one nozzle can be in close contact with the other nozzle, so that one can be made of steel or plastic material and the other can be made of rubber.

  The first tube 27, the second tube 31, and the third tube 32 can be a steel tube, an aluminum tube, a vinyl chloride tube, and the like, respectively. The size of the hole provided on the side surface of the first pipe 27 and the side surface on the lower end side of the second tube 31 may be any size as long as the gas and the groundwater 21 can be appropriately introduced. The shape is not limited to a circle, and may be any shape such as a slit shape, a spiral shape, and a mesh. If the opening ratio of this side surface is too small, an appropriate amount of gas and groundwater 21 cannot be allowed to flow in. If it is too large, not only groundwater 21 but also gas, and earth and sand will also flow in, An appropriate aperture ratio is desirable, and in the present invention, it is preferably about 10 to 20%. Moreover, the closing plates 33 and 34 may be integrally formed including the third pipe 32, and both the second pipe 31 and the first pipe 27 can be closed simultaneously. A rubber packing or the like is sandwiched between each flange portion and the closing plates 33 and 34 to prevent gas leakage such as from the first tube 27 to the second tube 31.

  In the present invention, the treated groundwater can also be drained into rivers, etc., but the gap in the ground where the groundwater was present is reduced, considering the possibility of causing ground subsidence due to consolidation, after construction, Groundwater from which VOC has been separated and removed can also be returned to the ground.

  Here, with reference to the system shown in FIG. 2, a method for purifying the contaminated ground will be described. First, the ground 23 is excavated and a triple pipe is installed in the ground 23. That is, after excavating the ground 23 to form an excavation hole extending to the impermeable layer through the aquifer, a ridge 35 is formed on the upper portion of the excavation hole, and a cap is applied to the lower end of the second pipe 31 for excavation. Insert into the hole. The part is filled so that the lower end side surface of the 2nd pipe | tube 31 is covered with earth and sand, and the lower part of the 2nd pipe | tube 31 is fixed. In addition to earth and sand, a material having air permeability and water permeability such as foamed concrete can be filled. The adhesive or solidifying material 25 is filled on the earth and sand, the first pipe 27 is placed thereon, the adhesive or solidifying material 25 is hardened or solidified, and the lower end opening of the first pipe 27 is closed. Thereafter, the periphery of the first pipe 27 is filled with earth and sand. Next, the third pipe 32 having the lower end connected to the pumping means 22 is inserted into the second pipe 31, and the closing plate 33 disposed on the third pipe 32 is placed on the upper end of the second pipe 31. It mounts on a flange part and the upper end opening of the 2nd pipe | tube 31 is closed using a fastening means. Further, the closing plate 34 is placed on the flange portion at the upper end of the first tube 27, and the upper end opening of the first tube 27 is closed using fastening means, thereby completing the installation of the triple tube. When the upper end opening of the first pipe 27 is closed with the closing plate 34, the nozzle provided on the closing plate 33 and the nozzle provided on the closing plate 34 are connected by fitting or the like. The lower end of the second pipe 31 is installed so as to be immersed in the groundwater 21.

  Two nozzles provided on the closing plate 34 are connected to each of the lines 24 and 28, and a nozzle communicating with the third pipe 32 is connected to an aeration processing apparatus (not shown) via the line 47. The lines 24 and 28 are provided with valves 36 and 37, respectively. First, the valve 37 of the line 24 connected to the first pipe 27 is closed, the valve 36 of the line 28 connected to the second pipe 31 is opened, and the suction means 20 is activated. The suction means 20 sucks the gas in the second pipe 31 and depressurizes the second pipe 31. A groundwater suction port 30 composed of a plurality of holes is provided on the lower side surface of the second pipe 31, and the groundwater 21 flows through the groundwater suction port 30. When the groundwater 21 flows into the second pipe 31, the pumping means 22 installed in the second pipe 31 is immersed in the flowing groundwater 21.

  For example, when the pumping means 22 is immersed in the groundwater 21, the pumping means 22 is activated to pump the groundwater 21. The pumped ground water 21 is sent to an aeration processing device (not shown), and VOCs contained in the ground water 21 are separated and removed.

  When the groundwater surface in the ground 23 falls and comes below the lower end of the first pipe 27, the valve 37 is opened, the gas in the first pipe 27 is sucked, and provided on the side surface of the first pipe 27. A gas containing VOC contained in the soil is caused to flow through the gas suction port 26 including a plurality of holes. The gas that has flowed into the first pipe 27 passes through the suction means 20, and after being subjected to appropriate processing, is diffused into the atmosphere. In order to determine that the water surface has come below the lower end of the first pipe 27, in the present invention, a detecting means for detecting the groundwater surface is provided on the outer surface of the first pipe 27. Can do. As the detection means, for example, a liquid level gauge can be used. With this liquid level gauge, the position of the ground water level is measured, and when the ground water level falls below 0 of the liquid level gauge, The inside of the first tube 27 can be sucked by the suction means 20 by determining that the lower end has come to the lower side. As a result, the groundwater 21 is not sucked into the first pipe 27, the load applied to the suction means 20 can be reduced, and the suction efficiency of the suction means 20 can be prevented from being lowered.

  FIG. 3 is a diagram showing a second embodiment of the system of the present invention. The system shown in FIG. 3 has the same configuration as the system shown in FIG. 2 and is included in an aeration treatment device 38 for aeration treatment of groundwater discharged by the pumping means 22 and a gas introduced into the first pipe 27. It is configured to include an adsorption device 40 filled with an adsorbent 39 that adsorbs VOC. In addition, a gas-liquid separator 41 that separates moisture contained in the gas that has flowed into the first tube 27 is further included between the first tube 27 and the suction means 20. In the system shown in FIG. 2, since the triple pipe, the pumping means 22 and the suction means 20 have been described above, the aeration treatment device 38, the adsorption device 40, and the gas-liquid separation device 41 will be described here.

  The aeration treatment device 38 includes a container for retaining contaminated groundwater pumped by the pumping means 22 and an air compressor connected to a nozzle provided on the lower side surface of the container and supplying air. The container includes an air nozzle provided at the lower part of the container, a groundwater supply nozzle for supplying groundwater, a drain nozzle provided at the bottom of the container, and a gas nozzle provided at the top of the container. The container has a capacity capable of retaining contaminated groundwater for a predetermined time. The air jetted from the air nozzle expels VOC contained in the contaminated groundwater into a gas phase, and is discharged as VOC gas from the gas nozzle at the top of the container together with the air.

  The pressure of the compressed air supplied from the air compressor can be about 0.7 MPa, for example. In the present invention, in addition to sending air, an agitating means for agitating the staying contaminated groundwater is provided, and by agitating the contaminated groundwater, VOC can be expelled to the gas phase and aeration treatment can be performed.

  The adsorption device 40 can be configured to include a container having a plurality of nozzles and an adsorbent 39 filled in the container. The container has a supply nozzle provided on the lower side surface of the container for supplying the gas sucked by the suction means 20 into the container, and an exhaust nozzle provided on the upper part of the container, which is discharged through the adsorbent 39. I have. The gas discharged from the suction means 20 is supplied into the container through the supply nozzle, and is diffused into the atmosphere from the upper exhaust nozzle through the adsorbent 39 filled in the container.

  The adsorbent 39 is formed by laying a porous plate in a container and filling the porous plate with a predetermined amount. The adsorbent 39 may be any material as long as it can adsorb VOC and remove VOC from the gas. For example, a porous material such as activated carbon or zeolite can be used.

  The gas-liquid separator 41 is used to separate moisture contained in the gas in a mist form or contaminated groundwater sucked together with the gas. The gas-liquid separation device 41 is configured to include a container having a plurality of nozzles similarly to the above-described aeration processing device and adsorption device, and in order to improve separation efficiency, a demister formed by laminating a metal mesh in the container A separation member can be provided. The gas-liquid separation device 41 can expand the supplied gas and separate the condensed water and the supplied fluid including both the gas and the groundwater.

  The aeration treatment device 38, the adsorption device 40, and the gas-liquid separation device 41 have been illustrated and described. However, the present invention is not limited to these, and VOC is generated by ultraviolet rays, ozone, electricity, ultrasonic waves, microorganisms, and the like. It can also be decomposed and recovered.

  FIG. 4 is a diagram illustrating a first tube used in the triple tube used in the system of the present invention. The first tube 27 includes a gas suction port 26 including a plurality of ventilation holes on the side surface, and the lower end is closed with an adhesive or a solidifying material as described above. A flange portion 42 is provided at the upper end, and the closing plate 34 shown in FIGS. 2 and 3 can be fastened and closed by fastening means. The gas is allowed to flow in or out through the gas suction port 26, and is contained in the soil outside the first pipe 27 by sucking the gas inside by the suction means 20 shown in FIGS. Gas is sucked into the first tube 27. This is because the gas in the first pipe 27 is sucked by the suction means 20 and the pressure in the first pipe 27 is reduced.

  In the present invention, the opening ratio of the side surface by the gas suction port 26 is preferably 10 to 20%. This is because if it is larger than this, the earth and sand in the soil is sucked into the first pipe 27, and if it is less than this, the amount of gas to be sucked decreases and the efficiency is lowered. The vent hole is not limited to a circle, and may be an ellipse or a rectangle. A spiral tube is formed by spirally winding a single linear steel member. It is also possible to have a structure with a slight gap between them. Moreover, not only a steel pipe but you may form from plastic materials, such as a vinyl chloride.

  FIG. 5 is a diagram illustrating a second tube used for the triple tube used in the system of the present invention. The second pipe 31 has a structure in which an upper end is closed by a closing plate 34, a lower end is closed by a closing member 29 such as a cap, and a groundwater suction port 30 including a plurality of water passage holes is provided only on a lower end side surface 44. It is said that. Similarly to the first tube 27, the second tube 31 is provided with a flange portion 43 for fastening the closing plate 34, and is manufactured from a steel or plastic material. The second pipe 31 is longer than the first pipe 27, and the lower side surface 44 protrudes so as to penetrate the lower end of the first pipe 27 when the first pipe 27 is disposed, It can be the part exposed to the aquifer. In addition, the lower end side surface 44 can be a region of a portion separated from the lower end of the first tube 27 when the first tube 27 is provided. In this case, if the length of the first tube 27 is about 10 m and the length of the second tube 31 is about 15 m, the first tube 27 is inserted through the lower end of the first tube 27. A portion of the second tube 31 protruding from the surface about 13 m to 15 m from the ground surface can be a lower end side surface 44. In the present invention, the lower side 1/5 to 1/2 of the length protruding from the lower end of the first tube 27 can be the lower end side surface 44. Thus, by separating the first pipe 27 and the lower end side surface 44 and providing the groundwater suction port 30 at a deep position in the ground 23, the gas sucked by the groundwater suction port 30 is sufficiently reduced. This is preferable because it can prevent the pumping efficiency of the pumping means 22 from being lowered.

  The second pipe 31 is sucked by the suction means 20 connected via the nozzles provided on the closing plates 33 and 34 and the line 28 shown in FIGS. Groundwater can be made to flow through the groundwater suction port 30 including a plurality of water holes provided. In the present invention, in this water passage hole, in order to allow groundwater to flow into the second pipe 31, the lower end opening is closed by the closing member 29 and installed in the aquifer. The opening ratio of the lower end side surface 44 by the plurality of water holes is preferably about 10 to 20%, which is the same as the opening ratio of the side surface of the first pipe 27 by the gas suction port. By setting this opening ratio, groundwater can be efficiently sucked without sucking gas. The shape of the plurality of water passage holes may be any shape such as a circle, an ellipse, and a rectangle.

  FIG. 6 is a diagram showing another embodiment of the second tube used in the triple tube used in the system of the present invention. FIG. 6 shows an enlarged view of the lower end side of the second pipe 31. The second pipe 31 shown in FIG. 6 has the same structure as that of the second pipe 31 shown in FIG. 5 and is capable of passing water so as to cover the lower end side surface 44 of the second pipe 31. A strainer tube 45 that shuts off the gas is provided. Since the structure of the second tube 31 shown in FIG. 6 is the same as the structure of the second tube 31 shown in FIG. 5, the description thereof is omitted here, and only the strainer tube 45 is described. The strainer tube 45 can be formed by spirally winding a linear member made of steel wire or carbon fiber. The strainer pipe 45 is configured to allow groundwater to pass through a slight gap between the linear members. The strainer pipe 45 can be permeated so that the groundwater oozes out due to the liquid level difference between the outside and the second pipe 31. On the other hand, the gas has a small gap and acts only with a small suction force. As a result, only groundwater can be passed.

  In the present invention, not only the strainer pipe 45 having this structure, but any member can be used as long as it can pass only groundwater. The contaminated groundwater that has flowed in through the strainer pipe 45 passes through the wall of the second pipe 31 as shown by the arrow, and passes through the groundwater suction port 30 formed of a plurality of water holes provided in the lower side surface 44. It flows into the second pipe 31. The groundwater flows in with a gradient by reducing the difference between the water level in the second pipe 31 and the water level of the groundwater in the aquifer and the pressure in the second pipe 31. Normally, it flows in only by the above difference, but in the present invention, the gas in the second pipe 31 is sucked by the suction means 20 and the inside of the pipe is depressurized. Thus, groundwater existing in the aquifer can be sufficiently introduced and pumped up, and the construction period can be shortened.

  FIG. 7 is a diagram illustrating a third tube used for the triple tube used in the system of the present invention. The third tube 32 includes a nozzle 46 for connecting to a nozzle provided on the closing plate 34, and a closing plate 33 that closes the second tube 31. The lower end is shown as a simple opening, but may be threaded to connect the pumping means 22. The third pipe 32 is a line for supplying groundwater in the second pipe 31 sucked by the pumping means 22 connected to the lower end to the aeration treatment device 38. The third tube 32 is shorter than the second tube 31 and longer than the first tube 27. The closing plate 33 is provided with a plurality of holes through which bolts as fastening means (not shown) are passed. Similarly to the first tube 27 and the second tube 31, the third tube 32 can be manufactured from a plastic material such as steel or vinyl chloride.

  As described above, the method of the present invention removes contaminated groundwater from the contaminated ground by pumping contaminated groundwater to remove the contaminated groundwater from the contaminated ground and sucking gas in the soil. The construction according to the method of the present invention can be terminated when, for example, there is no groundwater to be pumped and no gas to be sucked. In addition, since soil is a structure including many voids and air in the atmosphere may be sucked through the soil, for example, a gas-liquid separation device or a line connected thereto, suction means and adsorption device It can be judged by providing a sampling tube in the line between and measuring the VOC concentration. The VOC concentration for ending the construction can be set to an environmental standard value related to water pollution of groundwater, for example, 0.03 mg / L or less for trichlorethylene and 0.01 mg / L or less for tetrachloroethylene. .

The figure which showed the system for enforcing the conventional gas-liquid mixed extraction method. The figure which illustrated the pollution ground purification system of the present invention. The figure which showed another embodiment of the contaminated ground purification system of this invention. The figure which illustrated the 1st pipe | tube of the triple pipe used for the contaminated ground purification system of this invention. The figure which illustrated the 2nd pipe of the triple pipe used for the pollution ground purification system of the present invention. The figure which showed another embodiment of the 2nd pipe | tube of the triple pipe used for the contaminated ground purification system of this invention. The figure which illustrated the 3rd pipe of the triple pipe used for the contaminated ground purification system of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Ground 11 ... Suction well 12 ... Gas-liquid separator 13 ... Vacuum pump 14 ... Adsorption tower 15 ... Impervious layer 16 ... Ground water 17 ... Adsorbent 20 ... Suction means 21 ... Ground water 22 ... Pumping means 23 ... Ground 24 ... Line 25 ... Adhesive or solidifying material 26 ... Gas suction port 27 ... First tube 28 ... Line 29 ... Closing member 30 ... Groundwater suction port 31 ... Second tube 32 ... Third tube 33, 34 ... Closing plate 35 ...桝 36, 37 ... Valve 38 ... Aeration treatment device 39 ... Adsorbent 40 ... Adsorption device 41 ... Gas-liquid separation device 42, 43 ... Flange 44 ... Lower end side 45 ... Strainer tube 46 ... Nozzle 47 ... Line

Claims (13)

A system for purifying soil contaminated with volatile organic compounds (VOC),
A suction means for sucking gas;
Pumping means for pumping groundwater contaminated by the VOC;
An upper end is connected to the suction means via a first valve , a lower end opening is closed, a first pipe having a gas suction port on a side surface, and an upper end is connected to the suction means via a second valve. A second pipe having a ground water suction port on a lower side surface exposed through the closed lower end of the first pipe and exposed at the lower side, and is provided in the second pipe, A third pipe to which the pumping means is connected, and a triple pipe installed in the ground contaminated by the VOC,
The suction means sucks the second pipe by closing the first valve and opening the second valve, and is contaminated by the VOC through the groundwater suction port into the second pipe. The groundwater in the second pipe is pumped by the pumping means, and the first valve is opened when the groundwater surface is below the lower end of the first pipe, A contaminated ground purification system that sucks the inside of the first pipe and causes the gas contaminated by the VOC to flow into the first pipe through the gas suction port.   The contaminated ground purification system according to claim 1, comprising an aeration treatment device for aeration treatment of the groundwater pumped by the pumping means.   3. The contaminated ground purification system according to claim 1, further comprising an adsorption device filled with an adsorbent that adsorbs the VOC contained in the gas flowing into the first pipe.   The contaminated ground purification system according to any one of claims 1 to 3, further comprising a gas-liquid separator that separates moisture contained in the gas that has flowed into the first pipe.   The contaminated ground according to any one of claims 1 to 4, wherein the gas suction port includes a plurality of ventilation holes, and an opening ratio of a side surface of the first pipe is 10 to 20%. Purification system.   The groundwater suction port includes a plurality of water holes, is provided on the lower side surface of the second pipe, and an opening ratio of the lower side surface is 10 to 20%. The contaminated ground purification system of any one of -5. Wherein disposed on the outer surface of the first tube, including a sensing means for sensing the water table, Contaminated Land purifying system according to any one of claims 1 to 6.   The contaminated ground purification system according to any one of claims 1 to 7, further comprising a strainer pipe disposed so as to cover the lower side surface of the second pipe, capable of passing water, and blocking gas. . A method for purifying soil contaminated with volatile organic compounds (VOC),
In the ground, the upper end is connected to the suction means via the first valve , the lower end opening is closed, the side is provided with a gas suction port, and the upper end is connected to the suction via the second valve. A second pipe having a ground water suction port on a lower side surface exposed to the ground, the lower pipe opening being closed, the lower end opening being closed, penetrating the closed lower end of the first pipe, and the second pipe inside Installing a triple pipe provided with a third pipe with a lower end connected to the pumping means;
Closing the first valve, the opening of the second valve, and sucking the second pipe by the suction means, the inflow of contaminated groundwater by the VOC to the second pipe through the ground water suction port A process of
Pumping the groundwater by the pumping means;
Open the first valve where the water table becomes lower than the lower end of the first tube, by sucking the first tube by said suction means, said first pipe through the gas suction port A method for purifying contaminated ground, comprising a step of introducing a gas contaminated by the VOC.   The method for purifying contaminated ground according to claim 9, further comprising an aeration process on the discharged groundwater.   The method for purifying contaminated ground according to claim 9 or 10, further comprising a step of adsorbing the VOC contained in the gas flowing into the first pipe onto an adsorbent.   The method for purifying contaminated ground according to claim 11, comprising a step of separating moisture contained in the gas flowing into the first pipe before the step of adsorbing the adsorbent. An outer surface of the first tube, comprising a detection means for detecting the water table, after the water table is not detected by said detecting means, the step of flowing said gas, according to claim 9 to 12 The method for purifying contaminated ground according to any one of the above.

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