JP4254431B2 - Purification method and system for contaminated soil - Google Patents

Description

  The present invention relates to a purification method and system for collecting and purifying contaminants present in contaminated soil.

  Various pollutants such as volatile organic chlorine compounds such as trichlorethylene, fuel oils and machine oils, dioxins, and heavy metals such as cadmium, lead, copper, zinc, nickel and chromium are found in the soil of the factory site. May be in the soil.

  If the contaminated soil contaminated with such contaminants is left as it is, the contaminants mixed in the soil will diffuse to the surroundings, hindering the lives of the surrounding residents, and if they are released from the soil particles by rainwater In addition, it may cause contamination of groundwater by contaminating water quality. Therefore, the soil contaminated with the above-mentioned pollutants must be cleaned using various methods.

  Various methods have been developed to purify pollutants in the soil in-situ, so-called water-cleaning methods that use the soil gas suction method, injecting water into the contaminated soil, pumping it up, and treating it on the ground. Various methods, such as the so-called bubble entrainment purification method, in which air is introduced and entrained pollutants in the bubbles, the air sparging method that combines pneumatic injection and gas suction, and the bioremediation method that utilizes the microbial activity of soil fungi The method is known.

JP 2002-119952 A JP 2001-205248 A

  However, when the pollutant is present in a hardly air permeable water permeable layer such as a clay layer or a silt layer, the above-described method cannot be employed. That is, since these hardly permeable air permeable layers have poor air permeability and water permeability, there is relatively little concern about the entry of contaminants. However, once the contaminants are mixed into the hardly permeable air permeable layer, as described above. On the other hand, the poor tempering and water permeability impeded purification, which caused the problem that it was very difficult to recover the pollutants from the hardly permeable air permeable layer.

  The present invention has been made in consideration of the above-described circumstances, and provides a method and a system for purifying contaminated soil capable of reliably and efficiently recovering pollutants present in a predetermined layer in the ground, particularly a hardly permeable air permeable layer. The purpose is to do.

In order to achieve the above object, the method for purifying contaminated soil according to the present invention imparts vibration to soil particles in a contaminated area contaminated with a pollutant in a predetermined layer in the ground above the groundwater level. Then, the pollutant is collected together with the air or water from the suction pipe provided above the contaminated area while the pollutant is entrained in the air or water by ventilating or passing water through the contaminated area. Features.
Further, in the method for purifying contaminated soil according to the present invention, the predetermined layer is a hardly air permeable water permeable layer.

The contaminated soil purification system according to the present invention includes a vibration imparting mechanism that imparts vibration to soil particles in a contaminated area contaminated with a pollutant in a predetermined layer in the ground above the groundwater level , and the contamination A recovery mechanism that ventilates or passes water to the area and collects the air or water entrained in the air or water from a suction pipe provided above the contaminated area together with the air or water. It is characterized by that.
In the contaminated soil purification system according to the present invention, the predetermined layer is a hardly air permeable water permeable layer.

In the method for purifying contaminated soil according to the present invention, a shaft is excavated into a contaminated area contaminated with a pollutant in a predetermined layer in the ground, a vibrator is installed on the excavation bottom of the shaft, An injection well and a pumping well are buried at opposite positions sandwiching the contaminated area, and vibrations are applied to the soil particles in the contaminated area by the vibrator, and then water is passed through the contaminated area through the injected well. And collecting the pollutant together with the water from the pumping well while entraining the pollutant in water.
Further, in the method for purifying contaminated soil according to the present invention, the predetermined layer is a hardly air permeable water permeable layer.

A polluted soil purification system according to the present invention includes a shaft formed by excavating a contaminated area contaminated with a pollutant in a predetermined layer in the ground, and a vibrator installed on the excavation bottom of the shaft. a has a vibration applying mechanism for applying vibration to the soil particles in the contaminated area, the injection wells and pumping wells embedded in opposing positions sandwiching the contaminated area by the exciter machine, via the injection wells And a recovery mechanism for recovering the pollutant entrained in the passed water from the pumping well together with the water.
In the contaminated soil purification system according to the present invention, the predetermined layer is a hardly air permeable water permeable layer.

  In the contaminated soil purification method and system according to the present invention, vibration is imparted to soil particles in a contaminated area contaminated with a contaminant using a predetermined vibration imparting mechanism in a predetermined layer in the ground.

  In this way, the applied vibration causes the soil particles to collide with each other, resulting in a new gap between the soil particles, the gap becoming larger than the original size, or the skeleton of the soil particles being destroyed. At the same time, the soil particles rub against each other, so that the contaminants attached to the surface of the soil particles are peeled off from the surface.

  In such a state, when air or water that has been ventilated flows through the gaps between the soil particles, the flow resistance is greatly reduced, and contaminants attached to the soil particles are released into the gaps between the soil particles. Therefore, pollutants are easily taken to air and water.

  Therefore, if the pollutant is collected with the air and water while the pollutant is entrained in the air or water that is ventilated, the conventional gas suction method, groundwater pumping method, air Contaminants can be recovered with much higher efficiency than the sparging method, etc., and it exerts a remarkable effect on the hardly permeable air permeable layer that was impossible with the conventional method. It becomes possible to perform the purification of the water permeable layer reliably and efficiently.

  Contaminants are mainly oils and volatile organic compounds (including volatile organic chlorine compounds), but any substance that can be entrained in air or water, such as dioxins, is used in the present invention. Contained in pollutants.

  The hardly permeable air permeable layer mainly means a silt layer or a clay layer, but due to poor air permeability and water permeability, conventional methods such as water flow cleaning, gas suction, and air sparging methods can collect contaminants. If it is not possible, a soil layer containing sand in addition to silt or clay is naturally included in the hardly air permeable water layer referred to in the present invention.

  The vibration imparting mechanism may have any configuration as long as the above-described action can be exerted on the soil particles by imparting vibrations to the soil particles in the contaminated region. For example, a publicly known mechanism capable of generating ground vibration is known. It can be appropriately selected from the technologies or can be newly configured.

  Specifically, a shaft is excavated from the ground to a predetermined layer to be purified, which propagates air vibrations (sound waves of a predetermined frequency, particularly ultrasonic waves) from the ground to the contaminated area, and a vibrator is installed at the bottom of the excavation. In addition, the vibration region is vibrated using the vibrator, and a vibration transmission material is used as a pile, a sheet pile, etc., and the vibration transmission material is driven from the ground so that the lower end of the vibration transmission material reaches the contamination region. Exciting force is transmitted to the contaminated area by oscillating the upper end of the ground, and air pressure input and forced exhaust are repeated in a certain cycle, and a drilling hole is excavated from the ground up to a predetermined layer to be purified. Various methods are conceivable, such as installing dynamite on the surface and generating vibration in the layer.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a contaminated soil purification method and system according to the present invention will be described with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.

(First embodiment)

  FIG. 1 is a diagram showing a contaminated soil purification system according to the present embodiment. As shown in the figure, the contaminated soil purification system 1 according to the present embodiment includes oil, dioxins or volatile organic chlorine in the unsaturated hardly permeable air permeable layer 2 as a predetermined layer existing above the groundwater level. A ventilation air pressure input mechanism 5 for sending ventilation air to the contaminated area 4 contaminated with the pollutant 3 such as a compound, a vibration applying mechanism 41 for applying vibration to the contaminated area 4, and a contamination entrained in the aerated air. A gas processing facility 13 is provided as a recovery mechanism that sucks the substance 3 together with the air and performs a purification process.

  The unsaturated hardly permeable air permeable layer 2 is composed of soil mainly composed of silt, clay, or clay soil, and therefore is poor in air permeability, and is a soil layer in which gas suction is difficult as it is. The air permeable layer 7 is a soil layer made of sandy soil having air permeability, for example.

  The air pressure insertion mechanism 5 for ventilation includes an air compressor 12, an air tank 11 for intermediate storage of air sent from the air compressor, and a press-fit pipe 9 connected to the air tank 11. Can discharge air for ventilation from an air discharge port 8 provided at the lower end thereof.

  The gas treatment facility 13 includes a suction pipe 14 embedded in the unsaturated gas permeable layer 7 extending above the unsaturated hardly gas permeable water layer 2, a gas-liquid separation tank 15 connected to the suction pipe, and the gas liquid A suction blower 16 connected to the gas phase space of the separation tank, an activated carbon filter tank 17 connected to the suction blower, and a water treatment facility 18 connected to the liquid phase space of the gas-liquid separation tank. It is.

  The vibration imparting mechanism 41 includes a shaft 42 excavated up to the unsaturated hardly-permeable air permeable layer 2 and an exciter 43 installed on the excavation bottom of the shaft. A desired frequency is obtained by driving the exciter. Can be imparted to the contaminated region 4 of the unsaturated hardly permeable air permeable layer 2.

  In order to purify the contaminated region 4 of the unsaturated hardly permeable air permeable layer 2 using the contaminated soil purification system 1 according to the present embodiment, first, the unsaturated hardly permeable air permeable layer is driven by driving the exciter 43. In addition to applying vibration to the soil particles in the contaminated area 4, the air for air introduction is discharged from the air discharge port 8 provided at the lower end of the press-fitting pipe 9 by operating the air pressure inlet mechanism 5.

  In this way, the soil particles collide with each other to create a new gap between the soil particles, the gap becomes larger than the original size, the skeleton of the viscous soil is destroyed, and the soil particles are By rubbing, the contaminants attached to the surface of the soil particles are peeled off from the surface.

  FIG. 2 shows an example of the case where the skeletal fracture of the viscous soil occurs. FIG. 2A shows the skeleton of the viscous soil before the excitation by the vibrator 43. Figure (b) shows the skeleton of the cohesive soil after vibration.

  As can be seen from these drawings, the skeleton of the viscous soil is broken by the vibration imparted by the vibration exciter 43, and the soil particles are separated, the voids 21 are newly generated, and the contaminants adhered to the surface of the soil particles. 3 peels from the soil particles.

  Even when the skeleton is not destroyed, there is no change in that a new gap is generated or the original gap is increased due to the application of vibration by the above-described vibrator 43, and thus the aerated air 22 is between the soil particles. When the fluid flows through the gap 21, the flow resistance is greatly reduced and the flow becomes easier, and the contaminant 3 adhering to the soil particles is released in the gap 21 between the soil particles. 22 is easily taken.

  Next, while the pollutant 3 is entrained in the aerated air 22, the pollutant is sucked together with the air 22 by the gas processing equipment 13 and purified. Suction is performed by operating the suction blower 16.

  Next, the sucked pollutant entrained air is separated into liquid and gas in the gas-liquid separation tank 15, and the gas is passed through the activated carbon filter tank 17 to adsorb the pollutant 3 on the activated carbon, and then released to the atmosphere. At the same time, for the liquid, the pollutant 3 is removed by the water treatment facility 18 and then discharged into a river or the like.

  Even in the case of the unsaturated air permeable layer 7, the substance to be sucked is not only gas but also moisture is sucked in some amounts depending on weather conditions such as rainfall, and therefore the gas-liquid separation tank 15 is interposed. Needless to say, it is desirable to install the water treatment facility 18.

  As described above, according to the contaminated soil purification method and system according to the present embodiment, the soil particles in the contaminated area collide with each other due to the vibration imparted to the contaminated area 4 by the vibrator 43. Contamination that has adhered to the surface of the soil particles as a result of new gaps between the particles, the gap being larger than the original size, the skeleton of the soil particles being destroyed, and the soil particles rubbing against each other Material 3 is peeled from the surface.

  In such a state, when the aerated air 22 flows through the gap between the soil particles, the flow resistance is greatly reduced, and the contaminant 3 attached to the soil particles is released into the gap between the soil particles. Therefore, the contaminant 3 is also easily taken to the air 22.

  Therefore, if the pollutant 3 is sucked together with the air 22 and the purification process is performed, it is possible to reliably and efficiently purify the unsaturated hardly permeable air permeable layer 2 that was impossible by the conventional air sparging method or the like. It becomes.

(Second Embodiment)

  Next, a second embodiment will be described. In this embodiment, instead of the ventilation cleaning of the first embodiment, a configuration for performing water cleaning is adopted, and the same parts and the like as those of the first embodiment are denoted by the same reference numerals. Description is omitted.

  FIG. 3 is a diagram showing a purification system for contaminated soil according to the second embodiment. As can be seen from the figure, the contaminated soil purification system 31 according to the present embodiment includes oil, dioxins or volatile organic chlorine compounds in the saturated hardly permeable air permeable layer 2a as a predetermined layer, as shown in the figure. The vibration imparting mechanism 41 for imparting vibration to the contaminated area 4 contaminated with the pollutant 3, the water injection well 32 and the pumped well 33 that are buried in opposed positions across the contaminated area 4, and the pumped water through the pumped well 33. And a water treatment facility 8 for purifying the purified water and circulatingly feeding the purified treated water to the water injection well 32.

  Here, the pumping well 33 has a pumping pump (not shown) disposed at the bottom, and functions as a recovery mechanism capable of recovering pollutant entrained water.

  The saturated hardly air permeable water-permeable layer 2a is made of soil mainly composed of silt, clay, or clay soil, and therefore has poor water permeability and is difficult to pass through with water as it is.

  The vibration imparting mechanism 41 includes a shaft 42 excavated to the saturated hardly-permeable air permeable layer 2a and an exciter 43 installed on the excavation bottom of the shaft, and has a desired frequency by driving the exciter. Vibration can be applied to the contaminated region 4 of the saturated hardly permeable air permeable layer 2a.

  In order to purify the contaminated region 4 of the saturated hardly permeable air permeable layer 2a using the contaminated soil purification system 31 according to the present embodiment, first, as in the first embodiment, it is not possible to drive the exciter 43. Vibration is imparted to the soil particles in the contaminated region 4 of the saturated hardly permeable air permeable layer 2 and the treated water from which the pollutants 3 have been removed is pumped from the water treatment facility 18 to the water injection well 32 as wash water. Is pumped through a pumping pump (not shown) installed at the bottom of the pumping well 33.

  In this way, unlike the conventional air sparging method and bubble entrainment purification method, the soil particles collide with each other due to the vibration imparted to the contaminated region 4 by the vibrator 43, and the soil particles are newly opened. A gap is generated, the gap is larger than the original size, the skeleton of the clay soil is destroyed, and the soil particles rub against each other so that contaminants attached to the surface of the soil particles are removed from the surface. Peel off.

  As a result, when the wash water poured from the water injection well 32 flows through the gaps between the soil particles in the contaminated region 4 of the saturated hardly permeable air permeable layer 2, the flow resistance is greatly reduced and the flow becomes easy to flow. Since the pollutant 3 adhering to the soil particles is released in the gap between the soil particles, the pollutant 3 is also easily taken to the injected water.

  That is, in such water injection and pumping, the water injection well 32 and the water pumping well 33 are embedded in the opposite positions across the contaminated area 4 as described above, and the contaminated area 4 is washed with water. Contaminant 3 in the contaminated area 4 is included.

  Next, after the water pumped from the pumping well 33 is purified by the water treatment facility 18, the treated water is returned to the water injection well 32, and the surplus is discharged appropriately.

  As described above, according to the contaminated soil purification method and system according to the present embodiment, unlike the conventional air sparging method and bubble entrainment purification method, vibration to the contaminated area 4 by the exciter 43 is performed. By applying, the soil particles collide with each other and a new gap is generated between the soil particles, the gap becomes larger than the original size, the skeleton of the soil particles is destroyed, and the soil particles rub against each other. Thus, the contaminant 3 attached to the surface of the soil particles is peeled off from the surface.

  In such a state, when the injected water flows through the gaps between the soil particles, the flow resistance is greatly reduced, and the contaminant 3 attached to the soil particles is released into the gaps between the soil particles. For this reason, the pollutant 3 is also easily taken to the injected water.

  Therefore, by pumping water from the pumping well 33 while entraining the pollutant 3 in the water poured from the water pouring well 32, it is possible to surely purify the saturated hardly permeable air permeable layer 2 that was impossible with the conventional air sparging method and the like. It becomes possible to carry out efficiently. In this case, it goes without saying that heavy metals such as cadmium, lead, copper, zinc, nickel, and chromium can also be recovered.

  In the first embodiment and the second embodiment, the vibration imparting mechanism of the present invention is installed on the shaft 42 excavated to the unsaturated hardly air permeable permeable layer 2 or the saturated hardly permeable air permeable layer 2a and the excavation bottom of the shaft. The vibration imparting mechanism of the present invention is not limited to such a configuration, and the above-described action may be exerted on the soil particles by imparting vibrations to the soil particles in the contaminated region. Any configuration can be used as long as it can be performed. For example, the configuration can be appropriately selected from known techniques capable of generating ground vibration or can be newly configured.

  Specifically, a drilling hole is drilled up to a predetermined layer to be purified, particularly a hardly permeable air permeable layer (hereinafter, the predetermined layer will be described as an example of a hardly permeable air permeable layer), and an air pipe is inserted into the bore hole. Then, air vibrations (including sound waves of a predetermined frequency and ultrasonic waves) may be transmitted from the ground to the contaminated region of the hardly permeable air permeable layer via the air pipe.

  In addition, vibration is imparted by combining a high-pressure pneumatic injection device used in the Biopster construction method (a method that increases the microbial activity in the ground by pressing air into the ground) and a forced exhaust device equipped with a vacuum pump. A mechanism may be configured so that vibration is imparted to the contaminated region of the hardly permeable air permeable layer by repeating the press-fitting of high-pressure air by the high-pressure air-fitting device and the forced exhausting by the forced-exhaust device in a constant cycle.

  Further, a boring hole may be excavated from the ground up to the hardly air-permeable permeable layer, dynamite may be installed in the boring hole, and vibration may be generated in the layer.

  Further, in each of the above-described embodiments, the predetermined layer is a hardly air permeable water permeable layer, but the present invention is not limited to such a layer. For example, the air permeable layer or the water permeable layer made of sandy ground is predetermined. It is good also as a layer.

  Such sandy ground can be purified by conventional gas washing or water washing, but in the present invention, the vibration imparting mechanism can cause the action of peeling off contaminants adhering to the surface of the soil particles. Therefore, the purification efficiency is greatly improved as compared with the conventional method.

Schematic of the purification system of the contaminated soil which concerns on 1st Embodiment. The schematic diagram which showed an example of the effect | action of the purification method of the contaminated soil which concerns on this embodiment. Schematic of the purification system of the contaminated soil which concerns on 2nd Embodiment.

Explanation of symbols

1,31 Contaminated soil purification system 2 Unsaturated air permeable layer (predetermined layer)
2a Saturated hardly permeable air permeable layer (predetermined layer)
3 Contaminant 4 Contaminated Area 5 Pneumatic Inlet Mechanism 13 Gas Processing Equipment (Recovery Mechanism)
32 Water injection well 33 Pumping well (recovery mechanism)

Claims (8)

Among the predetermined layers in the ground above the groundwater level , vibration is applied to soil particles in the contaminated area contaminated with the pollutant, and then the pollutant is ventilated or passed through the contaminated area. A method for purifying contaminated soil, wherein the pollutant is collected together with the air or water from a suction pipe provided above the contaminated area while being entrained in air or water.   The method for purifying contaminated soil according to claim 1, wherein the predetermined layer is a hardly air permeable water permeable layer. A vibration imparting mechanism that imparts vibrations to soil particles in a contaminated area contaminated with a pollutant in a predetermined layer in the ground that exists above the groundwater level ;
A collection mechanism for ventilating or passing water through the contaminated area, and collecting the air or water entrained in the vented or passed air from a suction pipe provided above the contaminated area together with the air or water;
A system for purifying contaminated soil, comprising:   The contaminated soil purification system according to claim 3, wherein the predetermined layer is a hardly air permeable water permeable layer. A shaft is formed by excavating a contaminated area contaminated with contaminants in a predetermined layer in the ground, an exciter is installed at the excavation bottom of the shaft, and an injection well and While burying a pumping well, applying vibration to the soil particles in the contaminated area by the vibrator, then passing the contaminated area through the injection well and entraining the pollutant in water A method for purifying contaminated soil, comprising collecting the pollutant together with the water from the pumping well .   The method for purifying contaminated soil according to claim 5, wherein the predetermined layer is a hardly air permeable water permeable layer. Have exciter installed pit formed by drilled to contaminate the area that is contaminated with contaminants, and drilling the bottom of the standing pit out of the ground within a given layer, said contaminated region by said exciter machine A vibration imparting mechanism that imparts vibration to the soil particles in the interior;
An injection well and a pumping well embedded at opposite positions sandwiching the contaminated area, passing water through the contaminated area through the injection well, and supplying the pollutant entrained in the passed water to the water And a recovery mechanism for recovering from the pumping well ,
A system for purifying contaminated soil, comprising:   The contaminated soil purification system according to claim 7, wherein the predetermined layer is a hardly air permeable water permeable layer.

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