JP2006281080A - Processing method of contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a processing method of contaminated soil which is capable of preventing the diffusion of contaminate soil without disposing the washed treated soil as industrial wastes and with good processability upon preventing the diffusion of contaminate soil by cleaning the contaminated soil. <P>SOLUTION: The processing method of the contaminated soil comprises washing the contaminated soil contaminated by a contaminant with water to form the treated soil 20 or mixing a contaminant insolubilizing agent added to water and the contaminated soil to form the treated soil 20, then storing the treated soil 20 by dividing it into a plurality of water permeable bags 10, dehydrating the water content in the treated soil 20 by causing it to penetrate the outside of the bag 10, and a plurality of bags 10 storing the treated soil 20 dehydrated as described above are back-filled. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a contaminated soil treatment method for excavating contaminated soil contaminated with a contaminant and backfilling the treated soil treated with the contaminated soil to prevent the diffusion of the contaminant.

  In recent years, waste from factories and the like has caused serious contamination of soil and groundwater by chemical substances such as heavy metals, dioxins, and organic chlorinated solvents. As a method for purifying the contaminated soil contaminated with such a contaminant, a method for removing the contaminant from the excavated contaminated soil is generally employed. According to this method, the contaminated soil can be removed from the contaminated soil by excavating the contaminated soil, transporting the excavated contaminated soil to the purification plant, and cleaning the contaminated soil.

  However, there is a problem that the treated soil washed in the purification plant contains a large amount of water by washing and cannot be refilled as it is. In this way, if the treated soil containing a large amount of moisture cannot be backfilled, it must be disposed of as industrial waste, resulting in a problem that a great amount of processing costs are required.

  On the other hand, conventionally, a method of adding an insolubilizing agent to contaminated soil to insolubilize, or a method of solidifying by mixing with a solidifying material has been proposed. In the case of the method of adding the insolubilizing agent, in order to uniformly mix the insolubilizing agent with the contaminated soil, it is necessary to disperse the insolubilizing agent in a large amount of water and then mix them. Accordingly, the treated soil contains a large amount of moisture, and when it cannot be backfilled, it is disposed as industrial waste, and thus a large treatment cost is required. Further, when solidifying by mixing with a solidifying material, the effect of preventing the diffusion of contaminants may be insufficient as compared with the above method. Therefore, in order to obtain a sufficient diffusion effect of pollutants, it is necessary to increase the addition amount of the solidifying material, and the strength of the treated soil becomes excessively large, which may be difficult to reuse. .

  The present invention has been made in view of the above problems, and in purifying contaminated soil to prevent the diffusion of pollutants, the cleaned treated soil is not disposed of as industrial waste and is contaminated with good workability. It aims at providing the processing method of the contaminated soil which can prevent the spreading | diffusion of a substance.

  Therefore, in the method for treating contaminated soil according to the present invention, the contaminated soil contaminated with the contaminant is washed with water to obtain treated soil, or the contaminant insolubilizer added to the water is mixed with the contaminated soil. Next, the treated soil is divided into a plurality of water-permeable bags and accommodated, and moisture in the treated soil is allowed to permeate out of the bags and dehydrated. A plurality of stored bags are used for backfilling.

  According to the method for treating contaminated soil, the treated soil can be divided into a plurality of water permeable bags, accommodated, dehydrated, and used for backfilling as it is. In preventing the diffusion of the pollutant, it is possible to prevent the diffusion of the pollutant with good workability without disposing of the treated soil as industrial waste. Moreover, by refilling the plurality of bags, the bags can be sequentially pressed from the lower bags and a stable ground can be formed.

  Further, in the method for treating contaminated soil according to the present invention, the contaminated soil contaminated with the contaminant is excavated to form an excavated portion, and a part of the contaminated soil is washed with water to obtain treated soil, Is divided into a plurality of water-permeable bags, dehydrated by allowing moisture in the treated soil to permeate out of the bags, and excavating the plurality of bags containing the dehydrated treated soil. After laying along the side surface and bottom surface of the part, the contaminated soil is backfilled inside the laid bag body.

  According to the method for treating contaminated soil, the contaminated soil is excavated to form an excavated portion, a part of the contaminated soil is washed into treated soil, and the treated soil is divided into a plurality of water-permeable bags. Since the plurality of bags containing the dehydrated treated soil are laid along the side and bottom surfaces of the excavation part and provided with water blocking walls, all the excavated contaminated soil is washed. Even if it does not, it is sufficient to wash only a part thereof, and it is possible to solidify the treated soil contained in the bag body and use it as a water blocking wall, thereby preventing the diffusion of contaminants.

  In the method for treating contaminated soil according to the present invention, the excavated contaminated soil is washed or mixed with a pollutant insolubilizing agent added to water to obtain treated soil, and then the treated soil is treated with a plurality of water-permeable bags. Since the plurality of bags containing the dehydrated treated soil are used for backfilling, the moisture contained in the treated soil is permeated to the outside of the bag and dehydrated. The soil can be prevented from being diffused with good workability without being disposed of as industrial waste.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

<First embodiment>
The processing method of the contaminated soil which concerns on 1st embodiment of this invention has the process of processing the contaminated soil containing a pollutant in a plant, and the process of spin-dry | dehydrating and refilling this processed treated soil so that it can be recycled. .

  First, the process of processing contaminated soil will be described with reference to FIG.

  In the contaminated soil treatment process of the contaminated soil treatment method according to the present embodiment, first, a soil washing process or an insolubilizing agent addition process is performed. In the soil washing process, the contaminated soil containing the pollutant is excavated, and the excavated contaminated soil is conveyed to the mixing agitator of the washing plant. Then, contaminated soil and washing water are added to the mixing stirrer, and the mixture is sufficiently mixed and stirred to perform washing (step 1a). As the washing water, pure water, acidic liquid or alkaline liquid can be used depending on the contaminant to be washed. As the acidic liquid, for example, a liquid containing one or more kinds of hydrochloric acid, sulfuric acid, boric acid, oxalic acid, carbonated water and the like can be used. As the alkaline liquid, for example, a sodium hydroxide solution A liquid containing one or more of sodium carbonate solution or sodium hydrogen carbonate solution can be used.

  In the insolubilizing agent addition step, the pollutant insolubilizing agent and water are added and mixed and stirred in order to reduce properties such as solubility, mobility and toxicity of the pollutant in the treated soil (step 1b). As the pollutant insolubilizing agent, sodium sulfide, ferrous sulfate, sodium hypochlorite, chelating agent or lime can be used depending on the pollutant to be insolubilized. In addition, both the process 1a and the process 1b can also be performed. In this case, what is necessary is just to perform in order of the process 1a and the process 1b.

  Next, a flocculant is added and stirred and mixed, and the treated soil in the washing water is agglomerated and separated by settling (step 2). As the flocculant, aluminum sulfate, PAC (polyaluminum chloride), ferric chloride, or the like can be used.

  Then, the supernatant liquid after the treated soil is settled and separated is removed (step 3). In Step 3, when there is a large amount of residual water, a polymer absorbent or hemihydrate gypsum may be added and mixed to remove the water.

  Next, the process of dehydrating and refilling the treated soil treated by the above-described treatment process so as to be recyclable will be described with reference to FIG.

  In the backfilling step constituting the contaminated soil treatment method according to the present embodiment, first, the treated soil 20 is divided into a plurality of water-permeable bags 10 and accommodated as shown in FIG. As the bag body 10 having water permeability, for example, a sandbag bag or a hemp bag made of synthetic fibers such as polypropylene and polyester can be used.

  Subsequently, as shown in FIG. 2B, the bag body 10 containing the treated soil is pressurized, the bag body 10 is compressed, and moisture is discharged from the permeation holes of the bag body 10. Specifically, for example, the pressure may be mechanically pressurized and dehydrated, or the bag bodies 10 may be sequentially stacked and dehydrated by being pressurized by the weight of the bag body 10.

  The moisture content of the treated soil when the bag body 10 is compressed is preferably 150% or less. If the water content of the treated soil exceeds 150%, the treated soil is disposed as waste because it contains a lot of moisture, and cannot be used for backfilling.

  And the several bag 10 which accommodates the processing soil 20 processed so that it can regenerate | regenerate by the said method is piled up in the excavation part 30 which excavated contaminated soil, and is refilled as shown in FIG.2 (c). . In addition, as needed, you may make it fill the space | gap which piled up the bag body 10 directly by filling the clearance gap between the bag bodies 10 with the processing soil 20. Moreover, after stacking the bag body 10 in the excavation part 30, the surface may be processed by embedding or paving the upper surface.

As described above, in the method for treating contaminated soil according to the present embodiment, the excavated contaminated soil is washed with water or mixed with a pollutant insolubilizer added to water to form treated soil, and the treated soil is a plurality of water permeable materials. A plurality of bags containing the dehydrated treated soil are used for backfilling. . Therefore, excess water in the treated soil can be removed, and the treated soil can be prevented from being diffused as industrial waste, and the diffusion of contaminants can be prevented with good workability. In addition, by stacking a plurality of bags, the bags can be sequentially pressed from the lower bags to form a stable ground, and the contaminated soil can be efficiently regenerated.
The treated soil described above is backfilled again at the place where the contaminated soil is excavated, but the present invention is not limited to this, and may be used for backfilling at places other than the excavated place.

<Second embodiment>
Next, a method for treating contaminated soil according to the second embodiment of the present invention will be described with reference to FIG.

  FIG. 3 is a diagram for explaining a contaminated soil treatment method according to the second embodiment of the present invention.

  In the contaminated soil treatment method according to the present embodiment, first, the excavated portion 30 is formed by excavating the contaminated soil 40 contaminated with the contaminant. Next, in the excavated contaminated soil 40, the contaminated soil 40 is washed as much as laid along the side surface and the bottom surface of the excavated part 30. The cleaned treated soil is divided and accommodated in a plurality of water-permeable bag bodies 50, and water in the treated soil is permeated out of the bag body 50 to be dehydrated. And the bag body 50 which accommodated the treated soil is laid along the side surface and bottom surface of the excavation part 30 without a gap. Subsequently, the contaminated soil 40 is backfilled inside the laid bag body 50. In addition, after dehydrating the treated soil, a solidifying material may be added to the bag body 50.

In the method for treating contaminated soil, the same method described in the first embodiment described above can be adopted for the step of excavating and cleaning the contaminated soil, and thus the description thereof is omitted here.
Moreover, since the method demonstrated by 1st embodiment mentioned above can also be employ | adopted also about the process of spin-dry | dehydrating process soil, description is abbreviate | omitted here.

When solidifying material is added, cements such as Portland cement, blast furnace cement and early strong cement, slags such as granulated slag, gypsum such as dihydrated gypsum, hemihydrate gypsum and anhydrous gypsum Further, limes such as quick lime and slaked lime can be used.
The addition amount of the solidifying material is preferably 5 to 50 parts by weight with respect to 100 parts by weight of the treated soil.

  Next, in the step of laying the bag body on the excavation part, the bag 50 containing the treatment soil is installed without gaps along the side surface and the bottom surface of the excavation part 30, so that the treatment soil in the bag body 50 is removed. It solidifies and a water barrier is formed.

  As described above, in the contaminated soil treatment method according to the present embodiment, the contaminated soil is excavated to form an excavated portion, a part of the contaminated soil is washed to become treated soil, and the treated soil is a plurality of water permeable materials. Since the plurality of bags containing the dehydrated treated soil were laid along the side and bottom surfaces of the excavation part and provided with water blocking walls, contaminated soil It is not necessary to clean all of the above, and the labor and cost of cleaning can be reduced. Moreover, even if the contaminated soil is backfilled, it is possible to prevent the diffusion of contaminants by the water blocking wall.

  The water blocking wall may be formed by stacking a bag body and a steel sheet pile other than the bag body. Specifically, a steel sheet pile is provided along the side surface of the excavation part, the bag body is laid along the side surface of the steel sheet pile and the bottom surface of the excavation part, and the contaminated soil is backfilled inside the laid bag body. You may do it. Thereby, since the steel sheet pile is provided adjacent to the bag body, the treated soil is restrained by the steel sheet pile, and the generation of a gap due to the displacement of the treated soil can be prevented. Further, even if a gap is generated between the bag bodies and the contaminants diffuse to the outside, diffusion of the contaminants can be prevented by the steel sheet pile covering the outer surface of the bag body.

  In addition to the above method, the water blocking wall may be installed in a manner that a bag body is laid along the side surface of the excavation part, a steel sheet pile is provided along the inside of the laid bag body, and then the bottom surface of the excavation part You may make it lay a bag body along. Thereby, the same effect as the installation method of the water stop wall mentioned above can be acquired.

  Furthermore, in addition to the above, the method of installing the water blocking wall is provided with a steel sheet pile along the side surface of the excavation part, laying a bag body along the side surface of the steel sheet pile, and along the inside of the laid bag body. After providing the steel sheet pile, the bag body may be laid along the bottom surface of the excavation part. Thereby, the water blocking wall forms a three-layer structure in which the bag body is sandwiched between the steel sheet piles facing each other, so that the diffusion of contaminants can be prevented more reliably.

A block diagram is shown in order to explain the washing process of the contaminated soil which constitutes the backfilling method of the treated soil concerning a first embodiment of the present invention. The figure for demonstrating the regeneration method of the processing soil which comprises the backfilling method of the processing soil which concerns on the embodiment is shown. The figure for demonstrating the processing method of the contaminated soil which concerns on 2nd embodiment of this invention is shown.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,50 ... Bag body 20 ... Treated soil 30 ... Excavation part 40 ... Contaminated soil

Claims (2)

  The contaminated soil contaminated with the pollutant is washed with water to form treated soil, or the contaminated soil insolubilizer added to water and the contaminated soil are mixed to form treated soil, and then the treated soil is treated with a plurality of water permeable materials. A plurality of bags containing the dehydrated treated soil are used for backfilling. A method for treating contaminated soil.   Excavating contaminated soil contaminated with pollutants to form excavated parts, washing a part of the contaminated soil with water to form treated soil, and dividing the treated soil into a plurality of water-permeable bags And dehydrating by allowing moisture in the treated soil to permeate outside the bag body, laying a plurality of bags containing the dehydrated treated soil along the side surface and the bottom surface of the excavation part, A method for treating contaminated soil, wherein the contaminated soil is backfilled inside a laid bag.

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