JP2005074297A - Cleaning method for hardly-gas/water-permeable contaminated soil and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cleaning method for hardly-gas/water-permeable contaminated soil capable of certainly and efficiently recovering the contaminated substance existing in a hardly gas/water permeation layer, and a system. <P>SOLUTION: The cleaning system 1 for the hardly water permeable contaminated soil is provided with a high pressure air pressure-introduction mechanism 5 for intermittently feeding high pressure air to a contaminated area 4 contaminated with the contaminant 3 such as oil and dioxins or volatile organic chlorine compounds of an unsaturated hardly gas/water permeation layer 2 existing above underground water level; and a gas treatment facility 13 for sucking the contaminant 3 with air after the air intermittently introduced is raised through an unsaturated gas permeation layer 7 while the air carries the contaminant 3. The high pressure air pressure-introduction mechanism 5 intermittently introduces the high pressure air from an air compressor 12 to the contaminated area 4 through a pressure-introduction pipe 9 and can impart vibration to soil particles in the contaminated area. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a purification method and system for recovering and purifying contaminants present in hardly permeable and air permeable 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 pollutants 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 it is 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, which sends air in and entrains the 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 purification method and system for hardly permeable and air permeable contaminated soil capable of reliably and efficiently recovering contaminants present in the hardly permeable and air permeable layer. For the purpose.

  In order to achieve the above object, the method for purifying hardly permeable and air permeable contaminated soil according to the present invention is as described in claim 1, wherein in the unsaturated hardly permeable and air permeable layer, a contaminated area contaminated with a contaminant. High pressure air is intermittently fed to the soil, and then the soil particles in the contaminated region are vibrated by intermittent press-fitting of the high-pressure air, and then the contaminants are entrained while entraining the contaminants in the intermittently-pressurized air. A purification process is performed by suction with the air.

  In addition, the system for purifying hardly permeable and air permeable contaminated soil according to the present invention intermittently applies high-pressure air to a contaminated area contaminated with a contaminant in the unsaturated permeable and air permeable layer. A high-pressure pneumatic injection mechanism that applies vibrations to the soil particles in the contaminated area by intermittently injecting the high-pressure air, and sucking out contaminants entrained in the intermittently injected air together with the air to perform unloading processing. Gas treatment equipment to be performed.

  Further, in the purification system for hardly permeable and air permeable contaminated soil according to the present invention, the high pressure / pneumatic injection mechanism is press-fitted so that a high pressure air discharge port is located in a contaminated region of the unsaturated hardly permeable and air permeable layer. And an air compressor connected to the press-fitting pipe through a pressure vessel and an air tank, and the gas treatment facility is formed into an unsaturated air permeable layer extending above the unsaturated hardly air permeable water layer. A buried suction pipe, a gas-liquid separation tank connected to the suction pipe, a suction blower connected to the gas phase space of the gas-liquid separation tank, and a harmful substance removing device connected to the suction blower And a water treatment facility connected to the liquid phase space of the gas-liquid separation tank.

  In the method and system for purifying hardly permeable and air permeable contaminated soil according to the present invention, high-pressure air is intermittently supplied to a contaminated area contaminated with the pollutant in the unsaturated permeable and air-permeable permeable layer by a high-pressure pneumatic injection mechanism. By feeding and intermittently injecting the high-pressure air, vibration is imparted to the soil particles in the contaminated area.

  In this way, unlike the conventional method of simply entering air pressure, the soil particles collide with each other to create a new gap between the soil particles, the gap becomes larger than the original size, While the skeleton is destroyed, the soil particles are rubbed against each other, so that contaminants attached to the surface of the soil particles are peeled off from the surface.

  In such a state, when the intermittently injected air flows through the gap between the soil particles, the flow resistance is greatly reduced, and the contaminants attached to the soil particles are released into the gap between the soil particles. Therefore, contaminants are also easily taken to the air.

  Therefore, if the contaminants are taken into the intermittently injected air and the contaminants are sucked together with the air in the gas treatment facility and purified, the impermeable air permeation that is impossible with the conventional air sparging method, etc. It is possible to reliably and efficiently purify soil with soil contamination.

  Contaminants mainly include oil and volatile organic compounds (including volatile organic chlorine compounds), but any substance that can be air-entrained, such as dioxins, is included in the contaminants referred to in the present invention. .

  The hardly permeable air permeable layer in the unsaturated permeable air permeable layer mainly means a silt layer or a clay layer, but because of poor air permeability and water permeability, conventional methods such as water washing, gas suction, air sparging method, etc. If the pollutant cannot be recovered by the law, a soil layer containing sand in addition to silt or clay is naturally included in the hardly permeable air permeable layer referred to in the present invention.

  If intermittent press-fitting of high-pressure air can exert the above-mentioned action on the soil particles by applying vibration to the soil particles in the contaminated area, the magnitude of the pressure and the duration of the intermittent are, for example, difficult to unsaturated. What is necessary is just to determine suitably according to the air permeability coefficient of an air permeation-permeable layer, and its distribution condition.

  Here, it should be reiterated that the air pressure insertion in the present invention is not a mere press-fitting as in the prior art but an intermittent press-fitting. That is, it is difficult to improve the air permeability of the hardly permeable water permeable layer by simply introducing air pressure. Rather, the gap between the soil particles becomes smaller than the original size, and the air permeability may be lowered. It is done.

  The present applicant has newly found that the soil particles are vibrated by intermittent press-fitting of high-pressure air, thereby causing the above-described action, and thus improving the air permeability of the hardly permeable air permeable layer. This is a very useful knowledge in the industry and has a remarkable effect as compared with the prior art.

  The configuration of the high pressure / pneumatic injection mechanism and the gas processing equipment is arbitrary. For example, the high pressure / pneumatic injection mechanism is press-fitted so that the high pressure air discharge port is located in the contaminated region of the unsaturated hardly permeable air permeable layer. And an air compressor connected to the press-fitting pipe through a pressure vessel and an air tank, and the gas treatment facility is formed into an unsaturated air permeable layer extending above the unsaturated hardly air permeable water layer. A buried suction pipe, a gas-liquid separation tank connected to the suction pipe, a suction blower connected to the gas phase space of the gas-liquid separation tank, and a harmful substance removing device connected to the suction blower A water treatment facility connected to the liquid phase space of the gas-liquid separation tank can be considered.

  In particular, it is possible to divert an apparatus used in the Biopster construction method for the press-fitting pipe and the pressure vessel. The biopster method is a method in which pulsed high-pressure air is sent into the ground at regular intervals to activate the aerobic microorganisms in the ground, and its use or purpose is completely different from the present invention. To.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a purification method and system for hardly permeable and air permeable contaminated soil 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.

  FIG. 1 is a view showing a purification system for hardly air permeable and contaminated soil according to the present embodiment. As shown in the figure, the hardly permeable and air permeable contaminated soil purification system 1 according to the present embodiment includes an oil or an oil permeable layer of the unsaturated permeable and air permeable layer 2 existing above the groundwater level located in the saturated layer 6. Unsaturation while intermittently injected air entrains the pollutant 3 and the high-pressure air injection mechanism 5 that intermittently sends high-pressure air to the contaminated area 4 that is contaminated with the pollutant 3 such as dioxins or volatile organic chlorine compounds After the air-permeable layer 7 is raised, a gas processing facility 13 that performs a purification process by sucking the contaminant 3 together with air is provided.

  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 high-pressure / pneumatic injection mechanism 5 includes an air compressor 12, an air tank 11 that intermediately stores high-pressure air sent from the air compressor, and a pressure that adjusts the pressure of the high-pressure air sent from the air tank 11. It is composed of a container 10 and a press-fit pipe 9 that is connected to the pressure container and embedded so that the high-pressure air discharge port 8 is located in the contaminated region 4 of the unsaturated hardly permeable air permeable layer 2. The high-pressure air is intermittently pressed into the contaminated area 4 through the press-fit pipe 9, and vibration can be imparted to the soil particles in the contaminated area.

  Here, as the press-fitting pipe 9 and the pressure vessel 10, it is possible to divert an apparatus used in the Biopster construction method.

  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 communicatively connected to the gas phase space of the separation tank, an activated carbon filter tank 17 as a harmful substance removal device connected to the suction blower, and a water treatment communicatively connected to the liquid phase space of the gas-liquid separation tank It is composed of equipment 18.

  In order to install the purification system 1 of the hardly permeable and air permeable contaminated soil according to the present embodiment, first, a high-pressure pneumatic mechanism is installed in the contaminated region 4 of the unsaturated permeable and air permeable layer 2 that is contaminated with the contaminant. 5 press-fit pipes 9 are installed.

  When the press-fit pipe 9 is installed, the corresponding position is bored in advance, and then the press-fit pipe 9 is inserted into the bore hole, and then the press-fit pipe 9 and the bore are prevented from being blocked. In order to ensure air permeability by pre-filling a predetermined amount of sand between the holes, the mortar is placed in a space shallower than the high-pressure air discharge port 8 in the gap with the bore hole to prevent the press-fitting pipe 9 from shaking. Fill with bentonite and so on.

  Next, the pressure vessel 10 is attached to the upper end of the press-fit pipe 9, and the air tank 11 and the air compressor 12 are sequentially connected.

  On the other hand, a suction pipe 14 is embedded in the unsaturated gas permeable layer 7 and a gas-liquid separation device 15 is connected to the suction pipe. Thereafter, as described above, the suction blower 16 and activated carbon are communicated with the gas phase space. The filter tank 17 is sequentially connected, and the water treatment facility 18 is connected so as to communicate with the liquid phase space.

  In order to purify the hardly permeable and air permeable contaminated soil, in this embodiment the contaminated region 4 of the unsaturated permeable and permeable water permeable layer 2 using the purification system 1 installed in this way, first, an air compressor 12 and an air tank 11 and the pressure vessel 10 are appropriately operated to intermittently send high-pressure air into the contaminated region 4 of the unsaturated hardly permeable air permeable layer 2, and impart vibration to the soil particles in the contaminated region 4 by intermittent press-fitting of the high-pressure air. To do.

  In this way, unlike the conventional simple air pressure insertion, the intermittent press-fitting of high-pressure air causes the soil particles to collide with each other, resulting in a new gap between the soil particles, or a gap larger than the original size. As the soil becomes larger or the skeleton of the clay soil is destroyed, the soil particles are rubbed against each other, so that 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 a skeletal fracture of cohesive soil occurs. Fig. 2 (a) shows intermittent press-fitting of high-pressure air, and Fig. 2 (b) Fig. 2 (c) shows the state of the viscous soil skeleton after intermittent high-pressure air injection.

  As can be seen from these figures, the clay skeleton is broken by intermittent press-fitting of high-pressure air and the soil particles are separated, and voids 21 are newly generated, and the contaminant 3 attached to the surface of the soil particles is Peel from the soil particles.

  Even when the skeleton is not destroyed, there is no change in that a new gap is generated by the intermittent press-fitting of high-pressure air, or the original gap is increased. Thus, the intermittently press-fitted air 22 is a gap 21 between soil particles. The flow resistance is greatly reduced when flowing through the soil, and it becomes easy to flow, and the contaminant 3 adhering to the soil particles is released in the gap 21 between the soil particles, so the contaminant 3 is also entrained in the air 22. It becomes easy to be done.

  Next, after the intermittently injected air 22 moves up the unsaturated air permeable layer 7 while entraining the pollutant 3, the pollutant 3 is sucked together with the air 22 by the gas treatment facility 13 to perform a purification process. 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 gas 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 purification method and system for hardly permeable and air permeable contaminated soil according to the present embodiment, unlike the conventional method of simply entering air pressure, the soil particles collide with each other, Contaminant 3 attached to the surface of the soil particles due to the formation of a new gap, the gap becoming larger than the original size, the skeleton of the soil particles being destroyed, and the soil particles rubbing against each other Peels from the surface.

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

  For this reason, if the intermittently injected air 22 moves up the unsaturated air permeable layer 7 while entraining the pollutant 3, and if the pollutant 3 is sucked together with the air 22 to perform the purification process, the conventional air sparging method is performed. Thus, it becomes possible to reliably and efficiently purify the unsaturated hardly permeable air permeable layer 2 that could not be obtained by the above method.

  In the present embodiment, the high-pressure / pneumatic injection mechanism 5 includes an air compressor 12, an air tank 11 that intermediately stores high-pressure air supplied from the air compressor, and high-pressure air supplied from the air tank 11. The pressure vessel 10 is configured to adjust the pressure, and the press-fit pipe 9 is connected to the pressure vessel and embedded so that the high-pressure air discharge port 8 is located in the contaminated region 4 of the unsaturated hardly permeable air permeable layer 2. Any configuration may be used as long as vibration can be imparted to the soil particles in the contaminated region 4 by intermittent injection of high-pressure air.

Schematic of the purification system of the hardly air permeable water-contaminated soil which concerns on this embodiment. The schematic diagram which showed an example of the effect | action of the purification method of the hardly air permeable permeation | contamination soil which concerns on this embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Purification system of hardly air permeable permeability contaminated soil 2 Unsaturated hardly air permeable water layer 3 Pollutant 4 Contaminated area 5 High-pressure pneumatic injection mechanism 7 Unsaturated air permeable layer 9 Press-in pipe 10 Pressure vessel 11 Air tank 12 Air compressor 13 Gas Treatment equipment 14 Suction tube 15 Gas-liquid separation tank 16 Suction blower 17 Activated carbon filter tank (Toxic substance removal device)
18 Water treatment facilities

Claims (3)

High pressure air is intermittently sent to the contaminated area contaminated with the pollutant among the unsaturated hardly permeable air permeable layer, and then vibration is imparted to the soil particles in the contaminated area by intermittent injection of the high pressure air. Next, a method for purifying hardly air-permeable and permeable contaminated soil, wherein the pollutant is sucked together with the air while the pollutant is entrained in intermittently injected air, and the purification process is performed. A high-pressure pneumatic injection mechanism that intermittently feeds high-pressure air to a contaminated area contaminated with a pollutant in the unsaturated hardly permeable air-permeable layer and applies vibration to the soil particles in the contaminated area by intermittent injection of the high-pressure air. And a gas treatment facility for performing a purification treatment by sucking together with the air the pollutant entrained in the intermittently injected air, and a purification system for hardly permeable and air permeable contaminated soil. The high-pressure air-injection mechanism was connected to the press-in pipe through a pressure-in pipe and an air tank embedded in such a manner that a high-pressure air discharge port is located in the contaminated region of the unsaturated hardly permeable air permeable layer. A suction pipe embedded in the unsaturated gas permeable layer extending above the unsaturated hardly permeable gas permeable layer, and a gas-liquid separation tank connected to the suction pipe. A suction blower connected to the gas phase space of the gas-liquid separation tank, a harmful substance removing device connected to the suction blower, and a water treatment facility connected to the liquid phase space of the gas-liquid separation tank The purification system for hardly permeable and air permeable contaminated soil according to claim 2, comprising:

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