JP2004041924A - Method and apparatus for improving contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve residual soil even when a replacement rate with contaminated soil is not 100% and detoxification efficiency. <P>SOLUTION: After soil contaminated with organic chlorine compounds is bored, cement milk mixed with an oxidizing agent is injected from the tip part of the hole. The contaminated soil in the ground is replaced with the cement milk to form a cement plug. The organic chlorine compounds in the residual contaminated soil are decomposed by oxidation with the oxidizing agent left in the cement plug to clean the soil. The oxidizing agent is charged into slime recovered by the injection of the cement milk, and the organic chlorine compounds are decomposed by oxidation to clean the soil. <P>COPYRIGHT: (C)2004,JPO

Description

トリクレンを分解するための過マンガン酸カリウムの消費量はトリクレンの量に比例する。また、過マンガン酸カリウムは土壌中の有機物によっても消費される。そのため、残留トリクレンを分解するためセメントミルクに添加する過マンガン酸カリウムの必要量は実測して確認する必要がある。その結果、図４に示されるように、セメントミルクに残留するトリクレン含有量が３０ｍｇ／Ｌの時、過マンガン酸カリウムの必要添加量は３５Ｋｇ／ｍ^３であることが分かった。
【００２０】
このように本実施形態では、地盤改良の手法を利用し、汚染領域の土壌を硬化剤で置換するものの、置換率は１００％にならないことから、注入した硬化剤に混入している残留汚染土壌を硬化剤そのものに過マンガン酸カリウムなどの酸化剤を入れて地中に残留させるようにしている。このため、残留汚染物質である有機溶剤が硬化剤中に残留している過マンガン酸カリウム等の酸化剤により酸化分解されて無害化させることができる。分解剤である過マンガン酸カリウム等は硬化剤としてのセメントミルクが硬化したセメントプラグ５４に保持され、地盤中に流出することは無く、同時に、有機溶剤の酸化分解に利用されて二酸化マンガンの状態となるので、安全である。
【００２１】
【発明の効果】
以上説明したように、本発明では、有機塩素化合物で汚染された土壌を削孔した後、削孔先端部から酸化剤を添加混練したセメントミルクを注入し、このセメントミルクと地中汚染土壌と置換してセメントプラグを形成するとともに、セメントプラグ内に残留している酸化剤により残留汚染土壌の有機塩素化合物の酸化分解をなして浄化する構成としたので、浄化効率が高く、汚染土壌との置換率が１００％でない場合であっても、残留土壌の改質を行うことができて、無害化効率を大幅に改善できる。
【図面の簡単な説明】
【図１】本発明の実施形態に係る汚染土壌改良装置の構成図である。
【図２】同装置の土壌置換マシンによる土壌置換状態を示す掘削部断面図である。
【図３】汚染土壌改良エリアの掘削領域の作業手順を説明する平面図である。
【図４】過マンガン酸カリウム投入量とセメントミルク中のトリクレン残留率の説明図である。
【符号の説明】
１０………土壌置換マシン、１２………地盤、１４………ガイドホール、１６………回転ロッド、１８………ジェット流、２０………スライム、２２………スライムピット、２４………セメントスラリープラント、２６………セメントサイロ、２８………混練機、３０………水槽、３２………超高圧ポンプ、３４………コンプレッサ、３６………発電機、３８………改良剤混和手段、４０、４０Ａ………スライム収容タンク、４２………ポンプ、４４………過マンガン酸塩供給手段手段、４６、４６Ａ………ポンプ、４８………バキューム車、５０………汚染領域、５２………掘削円、５４………セメントプラグ。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for improving contaminated soil, and more particularly to a method and an apparatus for improving contaminated soil by replacing soil in which an organic chlorine compound solvent such as trichlorene (trichloroethylene) remains with cement milk.
[0002]
[Prior art]
Conventionally, as a method of purifying soil contaminated with an organic chlorine compound such as trichlene, a method of decomposing an organic chlorine compound in soil by injecting an oxidizing agent into the contaminated soil has been performed. For example, a method of adding water to soil contaminated with an organic chlorine compound and aerating ozone (JP-A-9-99281) or a method of injecting hydrogen peroxide into contaminated soil (JP-A-7-75772) Or a method of adding hypochlorous acid to benzyl chloride-contaminated soil (Japanese Patent Application Laid-Open No. 9-174032). However, in any of the above methods, the stability of the oxidizing agent added to the soil is low, and the oxidizing agent self-decomposes. As a result, especially when the purification target area is large, it is difficult to spread the oxidizing agent over the entire area. there were.
[0003]
From such a viewpoint, a method of injecting a permanganate as a stable oxidizing agent has been proposed (JP-A-2002-126713). This involves drilling an injection well and a pumping well in the contaminated soil area, injecting a permanganate solution (1 to 4% concentration) from the injection well, collecting the solution in contact with the contaminated soil from the pumping well, and removing pollutants. It is oxidatively decomposed.
[0004]
However, in such a method, the permanganate remains in the ground, and the drinking water pumped downstream may become a permanganate solution. There is. Moreover, what is collected is the permanganate solution and not the contaminated soil, and contaminated soil that has not been oxidized and decomposed may remain. In particular, when the concentration of contamination is high, it is necessary to increase the amount of the aqueous solution of permanganate, but in many cases, contaminated soil remains without being completely treated.
[0005]
Therefore, in order to clean soil in which an organic chlorine compound solvent such as trichlene remains, it is conceivable to apply a high-pressure soil creation method. This is a technique generally used for soil improvement, but instead of using cement milk to inject cement milk into the ground to build cement pillars, this technique is used to suppress contaminated soil with injected cement milk. Raised and collected, and instead of the collected soil, cement plugs are formed to make the ground. The soil removed from the ground by replacement with cement milk is put into a special treatment tank, and aeration or addition of potassium permanganate is performed to remove tricrene from the soil.
[0006]
[Problems to be solved by the invention]
However, in the above-mentioned conventional method, when the soil is replaced with the cement milk, a part of the cement milk and the soil are mixed, so that an organic chlorine compound such as trichlene has not been completely removed. In addition, the replacement ratio between the contaminated soil and the cement milk is not always 100%, but the replacement ratio is 20 to 80%, so that the contaminated soil has not been rendered harmless.
[0007]
The present invention pays attention to the above-mentioned conventional problems, and provides a method and an apparatus for improving contaminated soil with high purification efficiency in a case where soil in which an organic chlorine compound solvent remains is replaced with cement milk to improve contaminated soil. With the goal. It is another object of the present invention to provide a method and an apparatus for improving contaminated soil, in which the residual soil can be modified even when the replacement ratio with the contaminated soil is not 100%, and the detoxification efficiency is greatly improved. And
[0008]
[Means for Solving the Problems]
In this method, it is inevitable that cement milk and a part of soil are mixed, and as a means for decomposing tricrene remaining in the ground, the present invention uses potassium permanganate or peroxide An oxidizing agent such as hydrogen water was mixed to decompose the remaining trichlorene.
[0009]
That is, the method for improving contaminated soil according to the present invention comprises, after drilling soil contaminated with an organochlorine compound, injecting cement milk to which an oxidizing agent is added and kneaded from a drilling tip, and contaminating the cement milk with ground contamination. While replacing the soil to form a cement plug, the oxidizing agent remaining in the cement plug purifies the residual contaminated soil by oxidative decomposition of the organochlorine compound, and purifies the slime recovered by injecting the cement milk. The present invention is characterized in that an oxidizing agent is introduced to oxidatively decompose and purify an organic chlorine compound.
[0010]
In addition, the soil area contaminated with organochlorine compounds is mesh-divided and drilled to check the degree of contamination of the collected soil and create a contamination distribution, which is spirally cut from the outer edge of the set contamination area. Injecting cement milk to which oxidizer was added and kneading while drilling, repeating this cement milk and subterranean contaminated soil to form a cement plug, leaving cement plug with oxidizer remaining in the entire contaminated soil area May be arranged to replace the soil.
[0011]
The contaminated soil improvement apparatus according to the present invention is a grout injection means for injecting a hardening agent by drilling in a soil area contaminated with an organochlorine compound, a cement slurry plant for producing cement milk to be supplied to the excavation means, Pumping means for injecting cement milk to which an oxidizing agent has been added and kneaded from the drilling tip of the excavating means into the drilling tip, and wherein the soil improver containing at least an oxidant is mixed into the slurry plant. A mixing means, and a storage means for replacing soil which is ejected to the slime pit formed above the drilling, and a means for supplying a soil conditioner containing an oxidizing agent is connected to the storage means. This enables an improved treatment by oxidative decomposition.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, specific embodiments of a method and an apparatus for improving contaminated soil according to the present invention will be described in detail with reference to the drawings.
FIG. 1 shows a specific configuration of a contaminated soil improvement device according to the embodiment. This apparatus has grout injection means for drilling a soil area contaminated with an organochlorine compound and injecting a hardening agent into the ground. This is a method of loading a hydraulic cement-based hardener while replacing the soil with a hardener while cutting the soil with the jetting force of air and liquid.In the embodiment, a hardening material is used as a typical cutting jet as a grout injection means. A soil replacement machine 10 using a soil replacement method using liquid and air is used. As shown in FIG. 2, the soil displacement machine 10 includes a rotary rod 16 composed of a double pipe inserted into a guide hole 14 (having a hole diameter of 115 to 150 mm) which is a boring hole in the ground 12. From the tip, a jet stream 18 consisting of an ultra-high pressure hardening material liquid (usually 20 MPa) and compressed air (usually 0.7 MPa) is rotated and injected into the ground 12 to cut the ground 12 and generate slime 20. The slime pit 22 formed on the ground surface is discharged through the guide hole 14.
[0013]
Further, the contaminated soil improvement device is provided with a cement slurry plant 24 for producing cement milk as a hardening agent for the soil replacement machine 10 as the grout injection means. The cement slurry plant 24 has a cement silo 26 and a kneader 28, and is kneaded with water supplied from a separately installed water tank 30 to produce cement milk. Further, an ultrahigh-pressure pump 32 for supplying the produced cement milk and water to the soil replacement machine 10 is provided, and functions as a jet jet source. Further, a compressor 34 for producing compressed air is provided so that the compressed air can be supplied to the soil replacement machine 10. In addition, a generator 36 for supplying operating power to the device is provided.
[0014]
In such a facility, in this embodiment, in particular, the slurry plant 24 is provided with an improver mixing means 38 for mixing a soil improver containing at least an oxidizing agent. Potassium permanganate or hydrogen peroxide solution is used as an oxidizing agent to be added to the curing agent, and the mixing agent and the mixing agent are supplied to the kneading machine 28. Therefore, the cement slurry plant 24 is supplied to the subsequent ultrahigh-pressure pump 32 in a state where, for example, potassium permanganate is already kneaded in the produced cement milk. Then, cement milk to which potassium permanganate is added and kneaded from the tip of the rotating rod 16 of the soil displacement machine 10 obtains pressure from the ultrahigh pressure pump 32 as a pumping means and is injected into the underground tip of the guide hole 14. Is done. A slime pit 22 is formed in the upper part of the guide hole 14, and the displacement soil pushed up by the grout injection and ejected is temporarily accumulated as slime.
[0015]
A plurality of storage tanks (reservoir means) 40 for the ejected soil stored in the slime pit 22 are arranged in a row, and the ejected soil is sent to the immediately following storage tank 40 by a pump 42 installed in the slime pit 22. Then, potassium permanganate is introduced from the permanganate supply means 44 as a purifying agent so as to oxidize and decompose trichlene contained in the ejected soil. Then, it is sent to the subsequent storage tank 40A by the pump 46, and further from this storage tank 40A to the transport vehicle by the pump 46A. As a transport vehicle, a vacuum truck 48 transports the waste as general industrial waste to a treatment plant.
[0016]
The contaminated soil improvement method performed using the contaminated soil improvement device described above is performed as follows. First, the soil area contaminated with the organochlorine compound is mesh-divided and drilled, and the pollution degree of the collected soil is examined to create a pollution distribution. Thus, the contaminated area 50 is determined. It is presumed that the hardening agent injected by the soil displacement machine 10 is hardened into a cylindrical shape. Although it depends on the amount of grouting agent, the equivalent diameter is about 1.8 m, so that the arrangement of the excavated circles 52 where the circles overlap each other at a minimum and gaps are eliminated (FIG. 3 (2) ). This has a configuration in which the excavation circles 52 are arranged in a matrix as shown in FIG. Then, as shown by an arrow W in FIG. 3A, the cement kneaded with permanganate while kneading the permanganate from the outer peripheral edge of the contaminated region 50 composed of the group of excavated circles thus determined. By repeatedly injecting milk and replacing this cement milk with the underground contaminated soil to form a cement plug 54, the cement plug 54 containing permanganate is spread over the entire contaminated soil area to replace the soil. I am trying to do it.
[0017]
By the way, cement milk used when replacing contaminated soil is made by kneading cement and water. The fluidity of cement milk changes by changing the ratio of cement to water in the cement milk. Taking into account the work efficiency in soil replacement work, it was the cement concentration in the cement milk and 200~600Kg / ^{m 3.}
[0018]
Assuming that the replacement ratio of the cement milk injected into the soil at the time of replacing the soil is 100%, 100% of the organic chlorine compounds such as trichlene in the soil are removed. However, since the soil and a part of the cement milk are mixed during the soil replacement work, trichlene and the like remain in the cement milk. Therefore, it is necessary to decompose trichlene and the like in the replaced cement milk. Therefore, in the embodiment, in order to oxidatively decompose trichlene remaining in the cement milk, an oxidizing agent such as potassium permanganate or hydrogen peroxide is mixed with the cement milk.
[0019]
The reaction of tricrene with potassium permanganate is according to the following equation.
Embedded image

The consumption of potassium permanganate to decompose trichlene is proportional to the amount of trichlene. Potassium permanganate is also consumed by organic matter in the soil. Therefore, the necessary amount of potassium permanganate to be added to the cement milk to decompose the residual trichlene needs to be measured and confirmed. As a result, as shown in FIG. 4, it was found that when the content of tricrene remaining in the cement milk was 30 mg / L, the required addition amount of potassium permanganate was 35 kg / m ³ .
[0020]
As described above, in the present embodiment, the soil in the contaminated area is replaced with the hardening agent by using the soil improvement method. However, since the replacement rate does not become 100%, the residual contaminated soil mixed in the injected hardening agent. An oxidizing agent such as potassium permanganate is added to the hardening agent itself to remain in the ground. For this reason, the organic solvent that is a residual contaminant can be oxidized and decomposed by the oxidizing agent such as potassium permanganate remaining in the curing agent, and can be rendered harmless. Potassium permanganate as a decomposing agent is retained in the cement plug 54 in which cement milk as a hardening agent is hardened, and does not flow out into the ground. At the same time, it is used for oxidative decomposition of an organic solvent to form manganese dioxide. It is safe.
[0021]
【The invention's effect】
As described above, in the present invention, after drilling a soil contaminated with an organochlorine compound, a cement milk to which an oxidizing agent is added and kneaded is injected from a drilling tip, and the cement milk and the underground contaminated soil are removed. Replacement to form cement plugs and oxidizing agent remaining in the cement plugs to purify the remaining contaminated soil by oxidative decomposition of organic chlorine compounds. Even when the replacement ratio is not 100%, the residual soil can be modified, and the detoxification efficiency can be greatly improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a contaminated soil improvement device according to an embodiment of the present invention.
FIG. 2 is a sectional view of an excavated portion showing a soil replacement state by a soil replacement machine of the same device.
FIG. 3 is a plan view illustrating an operation procedure of an excavation area in a contaminated soil improvement area.
FIG. 4 is an explanatory diagram of the amount of potassium permanganate charged and the residual ratio of tricrene in cement milk.
[Explanation of symbols]
10 soil replacement machine, 12 ground, 14 guide hole, 16 rotating rod, 18 jet stream, 20 slime, 22 slime pit, 24 ……………………………………………………………………………………………………………………………………………………………………………………………………………………………………………………. ... improving agent mixing means, 40, 40A ... slime storage tank, 42 ... pump, 44 ... permanganate supply means means, 46, 46A ... pump, 48 ... vacuum car, 50 …… Contaminated area, 52 …… Drilled circle, 54 …… Cement plug.

Claims (3)

After drilling the soil contaminated with the organochlorine compound, inject cement milk kneaded with an oxidizing agent from the drilling tip and replace this cement milk with the underground contaminated soil to form a cement plug, The oxidizing agent remaining in the cement plug purifies by oxidatively decomposing the organic chlorine compound in the residual contaminated soil, and oxidizes the organic chlorine compound by oxidizing the slime collected by injecting the cement milk. A method for improving contaminated soil, comprising purifying the soil. The soil area contaminated with organochlorine compounds is mesh-divided and drilled by examining the degree of contamination of the collected soil by boring, and drilling a spiral from the outer edge of the set contaminated area. The oxidizing agent is added and the cement milk is added and mixed, and the cement milk is replaced with the underground contaminated soil to form a cement plug.The cement plug containing the oxidizing agent is spread over the entire contaminated soil area. A method for improving contaminated soil, characterized in that the soil is replaced by soil. Grouting means for drilling and injecting a hardening agent in a soil area contaminated with organochlorine compounds, a cement slurry plant for producing cement milk to be supplied to the drilling means, and an oxidizing agent from a drilling tip of the drilling means. A pressurizing means for injecting cement milk kneaded with kneading into the drilling tip portion, comprising an improving agent mixing means for mixing a soil improving agent containing at least an oxidizing agent into the slurry plant; Storage tank means for squirting into the slime pit that has been provided, and a supply means for a soil conditioner containing an oxidizing agent is connected to the storage means to enable improvement treatment by oxidative decomposition of the replaced soil. A contaminated soil improvement device characterized by the following.

Images