JP2003245649A - Pollution purification method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pollution purification method which enables cleaning treatment in situ, improvement in the treatment efficiency of a polluted object such as polluted soil or the like, shortening of the treatment period and lowering the cost of the treatment. <P>SOLUTION: The pollution treatment method comprises steps of forming a dug hole reaching polluted soil 10 by digging the ground 12 in which the polluted soil 10 exists, freezing the peripheral part of the dug hole 16 by injecting liquefied carbon dioxide 20 in the dug hole 16 so as to draw pollutants 22 in the peripheral part of the dug hole 16 to the surrounding of the dug hole 16 by the freezing, and removing the pollutants 22 drawn in the surrounding of the dug hole 16. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning pollution, and more particularly to a method for cleaning pollution for cleaning the environment such as soil and groundwater contaminated by contaminants such as trichlorethylene and tetrachloroethylene.

[0002]

BACKGROUND ART In recent years, environmental pollution such as soil and groundwater due to pollutants, particularly organic chlorine compounds such as trichlorethylene and tetrachloroethylene (hereinafter referred to as VOC) has been pointed out.

Therefore, various measures have been taken against environmental pollution.

For example, as a measure against a polluted environment, a method of isolating or removing a pollutant from the polluted environment to restore the environment to its original state is used.

[0005] Such methods are roughly classified into a containment method of forming a containment tank and containing contaminated soil therein, and a method of excavating a target site to separate and decompose pollutants in the target site or outside the target site. There are external treatment methods to be performed, in-situ purification methods to decompose and extract pollutants in-situ in the target area.

[0006] Containment methods include isolation of pollution sources, prevention of diffusion,
Although it is possible to cope with low to high concentrations, there is a problem that residual pollution sources, reinsolubilization of chemicals, damage to the containment tank, appropriate maintenance, semi-permanent monitoring, etc. are required.

Examples of external treatment methods include classification cleaning for separating contaminants, heat treatment, drying treatment, hot soil method, chemical decomposition for decomposing contaminants, thermal decomposition, bioremediation and the like.

[0008] However, when processing is carried out in the target area, a site for provision of temporary equipment is required, and when processing is carried out outside the target area, labor and transportation costs are required. However, there is a problem that measures such as decomposition, neutralization precipitation and adsorption are required.

In-situ purification methods include bioremediation for decomposing pollutants, soil reduction, iron powder method,
There are groundwater pumping to extract pollutants, suction of soil gas, electric treatment, etc., and since the pollutants are rendered harmless, there is no residual pollutant source and effective land use can be achieved.

However, there are problems that the concentration of pollutants is limited, the purification efficiency is lowered due to the influence of soil characteristics, and the construction period is prolonged, resulting in high running costs.

An object of the present invention is to provide a method for pollution purification which can perform in-situ purification and can improve the efficiency of purification of contaminated objects such as contaminated soil, shorten the construction period, and reduce the cost. To do.

[0012]

In order to achieve the above-mentioned object, a method for purifying pollution according to the present invention comprises a step of excavating a ground where an object to be polluted exists to form a drilling hole reaching the object to be polluted, Injecting a freezing agent into the drilling hole to freeze the periphery of the drilling hole, the step of attracting the contaminants around the drilling hole to the periphery of the drilling hole by this freezing, and the contaminants attracted to the periphery of the drilling hole. And a removing step.

According to the present invention, when a drilling hole reaching a contaminated object is formed and the drilling side surface layer is frozen using a freezing agent, water and contaminants around the frozen soil are attracted, and the antifreezing water is obtained. A pollutant layer such as VOCs and VOCs will be formed, and the antifreeze water and pollutants attracted to the periphery of the drilled hole will be treated by normal gas suction and pumping aeration. Pollutants can be removed.

Therefore, the contaminated object can be easily purified at the original position, and the structure can be simplified.

Further, as compared with the usual gas suction / pumping aeration process and the like, contaminants can be attracted to the periphery of the drilled hole, so that the number of treatment points is small and the purification efficiency is improved.
The construction period can be greatly shortened.

Further, compared with other purification methods such as decomposition and extraction, the running cost is low and a rapid treatment can be performed.

In the present invention, liquefied carbonic acid or solid carbonic acid can be used as the freezing agent.

With such a structure, frozen contaminated soil is thawed, and liquefied carbonic acid or solid carbonic acid reacts with water in the soil, and carbon dioxide generated at that time is used to produce antifreeze water or pollution. The rate of volatilization and elution of substances can be promoted.

In the present invention, a step of inserting a pipe for preventing direct contact between the freezing agent and the inner wall of the drilled hole into the drilled hole after forming the drilled hole and before injecting the cryogen. May be included.

With such a structure, the freezing agent does not directly contact the inner wall of the drilled hole by the pipe to freeze around the drilled hole, and the freezing agent is frozen through the pipe.
The freezing time around the drilled hole can be adjusted by the tube.

When liquefied carbonic acid or solid carbonic acid is used as the freezing agent, when the liquefied carbonic acid or solid carbonic acid is injected, it reacts by directly contacting the water on the inner wall of the drilled hole to generate carbon dioxide gas. Can be prevented.

In the present invention, the pipe can be pulled out from the inside of the drilled hole, the contaminated object frozen around the drilled hole can be thawed, and the pollutants inside and around the drilled hole can be collected and removed. .

With such a structure, the pipe can be extracted from the drilled hole and thawed, so that the cryogen and the inner wall of the drilled hole can be efficiently thawed.

In particular, when liquefied carbonic acid or solid carbonic acid is used as the defrosting agent, carbon dioxide gas generated from liquefied carbonic acid or solid carbonic acid during thawing of frozen contaminated soil is directly acted on the inner wall of the drilling hole to volatilize the pollutants and The elution rate can be accelerated.

In the present invention, when the pipe is inserted into the drilled hole, after freezing with the freezing agent, the pipe, the freezing agent in the pipe and the soil around the pipe can be taken out to collect and remove contaminants. .

With such a structure, the pipe, the freezing agent in the pipe and the soil around the pipe are taken out to collect and remove the pollutants, which is suitable for the case where heavy metals, oil, etc. are contained in the pollutants. Become.

In the present invention, when the pipe is inserted into the drilled hole, a step of withdrawing the pipe and the cryogen in the pipe from the drilled hole can be included after freezing with the cryogen.

In this case, after removing the pipe and the cryogen in the pipe, the contaminants around the drilled hole can be decomposed and removed.

With such a structure, it is possible to decompose and remove the contaminants by inserting a means for decomposing and removing the contaminants, such as an ultraviolet lamp, into the pipe and the drilling hole in which the cryogen in the pipe is extracted. it can.

This method is suitable for purification of pollutants including oil and VOC.

[0031]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 to FIG. 5 are views showing a pollution purifying method according to an embodiment of the present invention.

In the present embodiment, this pollution purification method is
The method for cleaning contaminated soil will be explained, but it can also be applied to contaminated groundwater.

First, as shown in FIG. 1, the ground 12 on which the polluted soil 10 as the polluted object exists is excavated by the excavator 14 to form the drilled holes 16 reaching the polluted soil 10.

In this case, prior to excavation, boring or the like is performed to investigate the range and depth of the contaminated soil 10, and the drilling hole 16 is excavated accordingly.

Then, as shown in FIG. 2, a pipe 18 having a diameter substantially the same as that of the drilled hole 16 is inserted into the drilled hole 16.

The tube 18 may be made of metal or synthetic resin.

In the case of the metal tube 18, various tubes having different thermal conductivity can be selected and used.

With this, the freezing time around the drilled hole 16 can be adjusted.

Next, as shown in FIG. 3, liquefied carbonic acid 20 as a freezing agent is injected into the drilled hole 16, specifically, the pipe 18 to freeze the periphery (side surface layer) of the drilled hole 16.

Due to this freezing, the contaminants 22 around the drilled hole 16 are attracted to the periphery of the drilled hole 16.

This contaminant 22 is drilled 16 by freezing.
The phenomenon of being attracted to the surrounding area is known as a phenomenon in which the surface of the soil freezes when the temperature falls below 0 ° C. in cold regions, and the surrounding soil water moves to the freezing surface, forming an ice layer.

It has been ascertained that this frost heave phenomenon is caused by the movement of soil water to the freezing surface, but at present it is not clear why the soil water moves to the freezing surface. is there.

It is considered that antifreeze water, which does not freeze even if it is desired to be frozen, remains on the surface of soil particles in frozen soil, and it is thought that it is attracted to the frozen surface.

Using this phenomenon, the contaminated soil 10 is excavated, liquefied carbonic acid 20 is injected into the drilled hole 16 and the side surface layer of the drilled hole 16 is frozen, so that water and VOCs around the soil are contaminated. The substance 22 is attracted to the antifreeze water and the pollutant layer 2
4 will be formed.

Next, as shown in FIG. 4, the liquefied carbonic acid 20 is left in the soil, and the pipe 18 is pulled out from the drilled hole 16.

In this case, the bottom of the pipe 18 is in an open state.

In this state, the frozen contaminated soil 10 is thawed, and the carbon dioxide gas generated from the liquefied carbon dioxide 20 at that time is used to accelerate the elution rate of the antifreeze water and the pollutant layer 24, as shown in FIG. So that the vacuum pump 26
The contaminant 22 in 6 is sucked into the gas-liquid separation layer 28, further sent to the activated carbon adsorbing device 30, cleaned, and then exhausted.

When the groundwater is contaminated, a pumping pump (not shown) is used to take it out to the aeration processing device 32, and to discharge the treated water which has been purified by the aeration process and to blow the contaminated gas to the blower 34. It is sent to the activated carbon adsorption device 30 for purification and exhaust.

In this way, the contaminated soil 10 is excavated, the side layer of the drilled hole 16 is frozen by using the liquefied carbonic acid 20, and the antifreeze water and the pollutant 22 are attracted to the surrounding antifreeze water and the pollutant 2.
By accelerating the elution rate of No. 2 and performing gas suction and pumping aeration for pumping, the number of treatment points, construction period, and cost can be greatly reduced as compared with ordinary gas suction and pumping for pumping aeration.

FIG. 6 shows a pollution purifying method according to another embodiment of the present invention.

This pollution purification method is common until the step of injecting the liquefied carbon dioxide 20 into the pipe 18 of FIG. 3 and freezing the side surface layer of the excavation 16 in the above-described embodiment. After freezing by the method, the pipe 18, the liquefied carbon dioxide 20, and the contaminated soil 10 around the pipe 18 are taken out to collect and remove the contaminant 22.

By doing so, oil, heavy metal, VO
It can be made suitable for purifying the contaminant 22 containing C and the like.

7 and 8 show a pollution purifying method according to still another embodiment of the present invention.

In this pollution control method, a hole 16 is drilled as shown in FIGS. 1 to 3, a pipe 18 is inserted into the hole 16, and liquefied carbon dioxide 20 is injected into the hole 16. After freezing the side surface layer of the drilled hole 16 and pulling the antifreeze liquid and the contaminants 22 around the drilled hole 16, as shown in FIG.
8 and the liquefied carbon dioxide 20 in the pipe 18 are extracted.

In this case, the bottom of the pipe 18 is closed.

Next, the ultraviolet lamp 42 is inserted into the drilled hole 16 from which the pipe 18 and the liquefied carbon dioxide 20 are removed, and the drilled hole 16 is drilled.
The contaminants 22 attracted to the surrounding area are decomposed and removed by ultraviolet rays.

The present invention is not limited to the above embodiment, but can be modified into various forms within the scope of the gist of the present invention.

For example, although liquefied carbonic acid is used as the freezing agent in the above-mentioned embodiment, solid carbonic acid may be used,
Alternatively, if it is not necessary to use carbon dioxide gas, a freezing agent such as liquid nitrogen can be used.

If it is not necessary to consider the reaction between the liquefied carbonic acid and the water in the hole, it is possible to omit inserting the pipe into the hole.

Further, in FIG. 8, an ultraviolet lamp is inserted into the drilled hole to decompose and remove contaminants, but other means for decomposition and removal, such as chemical decomposition and removal, iron powder decomposition and removal, and nanocarbon are used. It is also possible to use decomposition removal by bioremediation, thermal decomposition removal, and the like.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a state of forming a hole in an embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a pipe is inserted into the drilled hole formed in FIG.

FIG. 3 is a cross-sectional view showing a state in which liquefied carbonic acid is injected into the tube and frozen from the state of FIG.

FIG. 4 is a cross-sectional view showing a state in which a tube is taken out from the state of FIG.

FIG. 5: Thaw frozen liquefied carbonic acid from the state of FIG.
It is sectional drawing which shows the state which is performing gas suction and pumping aeration.

FIG. 6 is a cross-sectional view showing a pollution purifying method according to another embodiment of the present invention.

FIG. 7 is a cross-sectional view showing a state in which a pipe and frozen liquefied carbonic acid are taken out after freezing in a method for cleaning pollution according to still another embodiment of the present invention.

8 is a cross-sectional view showing a state in which an ultraviolet lamp is inserted into the drilled hole for purification from the state of FIG. 7.

[Explanation of symbols]

10 contaminated soil 12 ground 16 Drilling 18 tubes 20 Liquefied carbonic acid 22 pollutants 28 Gas-liquid separation layer 30 Activated carbon adsorption device 32 Aeration processing device 42 UV lamp

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Chiba             Toda Ken 1-7-1 Kyobashi, Chuo-ku, Tokyo             Inside the corporation (72) Inventor Toshiro Itaya             Toda Ken 1-7-1 Kyobashi, Chuo-ku, Tokyo             Inside the corporation (72) Inventor Takeo Kanazawa             2-13-1, Peony, Koto-ku, Tokyo Stock market             Shamaegawa Works (72) Inventor Kim Ishikura             2-13-1, Peony, Koto-ku, Tokyo Stock market             Shamaegawa Works (72) Inventor Shinichi Yamagami             2-13-1, Peony, Koto-ku, Tokyo Stock market             Shamaegawa Works F-term (reference) 4D004 AA41 AB06 CA01 CA32 CA43                       CA50 CC12                 4D037 AA11 AB14 BA21

Claims (7)

[Claims] 1. A step of excavating a ground in which a polluted object exists to form a drill hole reaching the polluted object, and a freezing agent is injected into the drill hole to freeze the periphery of the drill hole. A pollution purification method comprising: a step of attracting contaminants around the drilled hole to the periphery of the drilled hole by freezing; and a step of removing the contaminants drawn around the drilled hole. 2. The method according to claim 1, wherein liquefied carbonic acid or solid carbonic acid is used as the freezing agent. 3. The pipe according to claim 1 or 2, which prevents direct contact between the freezing agent and the inner wall of the drilling hole in the drilling hole after the drilling hole is formed and before the cryogen is injected. A method for decontaminating pollution, which comprises a step of inserting. 4. The pipe according to claim 1, wherein the pipe is extracted from the hole, the contaminated object frozen around the hole is thawed, and the contaminants inside and around the hole are collected. A method for purifying pollution, which is characterized in that 5. The method according to claim 3, wherein after freezing with the freezing agent, the pipe, the freezing agent in the pipe, and the soil around the pipe are taken out to collect and remove contaminants. 6. The method according to claim 3, further comprising a step of extracting the pipe and the freezing agent in the pipe from the drilled hole after freezing with the freezing agent. 7. The method according to claim 6, wherein the pipe and the cryogen in the pipe are extracted, and then the contaminants around the hole are decomposed and removed.