JP2013043134A - In-situ insoluble treatment method for soil contaminated by heavy metal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an effective and appropriate method capable of efficiently performing the insoluble treatment of soil contaminated by a heavy metal.SOLUTION: The method is provided for performing insoluble treatment in situs of contaminated soil 1 contaminated by the heavy metal. A gel-like treatment material 2, formed by adding a granular polymer-based filler to an insolubilized liquid in the form of a liquid, is pressurized and injected to a treatment target area in the ground. Thereby, the insolubilized liquid in the treatment material is brought into contact with the contaminated soil 1 in the state of making the treatment material stay in the treatment target area, and contaminants are insolubilized. It is preferable to pressurize and inject the treatment material toward the treatment target area, by forming a drilling hole to reach the depth of the treatment target area by a drilling means 3 such as a boring machine or a mechanical agitation type ground improvement machine and jetting the treatment material into the ground from a nozzle 4 provided on the distal end part of the drilling means.

Description

  The present invention relates to a technique for cleaning contaminated soil, and more particularly to a method for insolubilizing contaminants in situ for soil contaminated with heavy metals.

  As is well known, the insolubilization treatment method for contaminated soil is generally a drilling treatment method that excavates the contaminated soil to be treated, mixes it with the insolubilizing solution on the ground, insolubilizes the contaminants, and then backfills the soil. In recent years, however, in-situ insolubilization treatment methods in which an insolubilizing solution is directly injected into a contaminated region and insolubilized as shown in Patent Documents 1 and 2, for example, are becoming common.

  Patent Document 3 proposes a method of insolubilizing oil as a pollutant with an oil adsorbing gelling material as a method for insolubilizing soil contaminated with oil.

JP-A-11-207314 JP 2008-279360 A JP 2003-340447 A

  However, the conventional excavation method requires much more cost for excavation and backfilling than the insolubilization process itself, especially when the contaminated area is located deep in the ground, the amount of excavation and backfilling is enormous. It is not rational and realistic.

  In that respect, the in-situ insolubilization method shown in Patent Documents 1 and 2 is advantageous in terms of cost compared to the excavation method, but sufficient effects cannot be obtained depending on the condition of the ground where contaminated soil exists. In some cases. For example, in the ground where there are a lot of gravel and cobblestone, the injected insolubilized liquid may diffuse quickly without staying in the contaminated area. In this case, not only a large amount of insolubilized liquid is wasted. There is also a concern that the insolubilization treatment cannot be reliably performed.

  Furthermore, in the method disclosed in Patent Document 3, a ground is excavated to form a groove in order to form a wall-like or columnar soil layer containing an oil-adsorbing gelling material around the contaminated area, and the oil content is formed in the groove. Adsorbed gelling material is mixed with excavated soil and backfilled, so that excavation and backfilling are necessary as in the conventional excavation processing method, which is disadvantageous in terms of cost.

  As mentioned above, in the past, it could not be said that an effective method for insolubilizing contaminated soil has been established, and therefore, without requiring extensive excavation or backfilling of contaminated soil with heavy metals, In fact, there is a demand for the development of an effective and appropriate method that can be insolubilized efficiently and reliably without being affected by the ground.

  In view of the above circumstances, the present invention is a method for insolubilizing soil contaminated with heavy metals in situ, and is a gel-like product obtained by adding a granular polymer filler to a liquid insolubilized liquid. By injecting the treatment material into the area to be treated under pressure, the insolubilized liquid in the treatment material is brought into contact with the contaminated soil in a state where the treatment material is retained in the area to be treated, thereby insolubilizing the contaminant. It is characterized by doing.

  In the present invention, a hole that reaches the depth of the region to be treated is formed by a hole drilling means such as a boring hole drill or a mechanical stirring blade type ground improvement machine, and the processing is performed from a nozzle provided at the tip of the hole drilling means. It is preferable that the processing material is injected under pressure toward the processing target region by injecting the material into the ground.

According to the insolubilization processing method of the present invention, the processing material is directly injected into the processing target region and insolubilization processing is performed in-situ, so that large-scale excavation and backfilling are not required unlike the conventional excavation processing method. Excellent workability and much more advantageous in terms of cost.
In particular, in the present invention, instead of using the liquid insolubilized liquid as it is as in the conventional general in-situ insolubilizing method, a gel-like process in which a granular polymer filler is added to the liquid insolubilized liquid. Since the material is used, even if the treatment target area is ground with a lot of gravel and cobblestone, the treatment material will not stay in the injection position and will not be diffused to the surroundings. Compared with the treatment method, it is less affected by the ground and can be reliably and efficiently insolubilized. It is extremely rational and effective as a method for insolubilizing soil contaminated with heavy metals in situ.

The embodiment of the insolubilization processing method of this invention is shown, and is a figure which shows a series of process steps.

FIG. 1 shows a series of processing steps in the insolubilization processing method according to the embodiment of the present invention.
This is for insolubilizing the pollutant in situ for the contaminated soil 1 due to heavy metal in the deep underground as shown in (a). In this embodiment, in order to insolubilize the pollutant, The main purpose is to use a special treatment material 2 and to inject the treatment material 2 under pressure into the region to be treated by spraying it into the ground.

  The treatment material 2 used in the present embodiment was prepared so as to form a gel by adding a granular polymer filler as an additional component to the liquid insolubilization liquid as a main component for insolubilization treatment. Is.

  As the insolubilizing liquid which is the main component of the treatment material 2, the same insolubilizing liquid as used in the conventional in-situ insolubilizing method shown in Patent Document 1 or Patent Document 2 may be used. In the case of hexavalent chromium, ferrous salts, sulfites, and polysulfides can be suitably used, and when the contaminant is selenium, ferrous chloride can be suitably employed.

  The polymer filler as an additive component is also used as a component of an oil-adsorbing gelling material for adsorbing oil in the insolubilization processing method shown in Patent Document 3, but the processing used in this embodiment is used. In the material 2, the main component for insolubilizing the pollutant is only the insolubilizing liquid, and the polymer filler itself does not have a function of adsorbing or insolubilizing the pollutant, and this polymer filler is treated. The material 2 is added to the insolubilizing solution so as to exhibit a stable gel form.

That is, in the conventional general in-situ insolubilization treatment method as shown in Patent Document 1 and Patent Document 2, since the liquid insolubilized liquid is injected into the ground as a liquid, depending on the ground conditions as described above. The injected insolubilized liquid diffuses in a wide range from the injection point to its surroundings due to its own fluidity and does not stay for a long time in the contaminated area. By adding a granular polymer filler to the liquid insolubilized liquid and mixing, the liquid insolubilized liquid is stably gelled without impairing its original insolubilizing function, thereby processing The fluidity as the material 2 is moderately suppressed.
Therefore, by injecting the treatment material 2 prepared in such a gel state into the ground, the injected treatment material 2 stays stably at that position for a long time without vainly spreading around, In this state, the insolubilizing liquid, which is the main component of the treatment material, comes into contact with the contaminant and can reliably and sufficiently exhibit the insolubilizing function.

  In order to inject the treatment material 2 into the ground, it is possible to divert the insolubilizing liquid injection means in the conventional method as it is, but the treatment material 2 in the form of a gel is merely a liquid insolubilization. Since it is naturally harder to flow than the liquid, in order to inject it into the ground, as shown in FIG. 1 (b), for example, a hole drilling means such as a boring hole drill or a mechanical stirring blade type ground improvement machine 3, a hole that reaches the depth of the region to be treated is formed, and the gel-like treatment material 2 is jetted into the ground as a jet jet from the nozzle 4 provided at the tip of the hole means 3 as shown in FIG. By doing so, it is preferable to perform pressure injection toward the region to be processed.

  In this way, by forming a hole in the ground by the hole drilling means 3 and injecting the treatment material 2 from the nozzle 4 into the ground, it is possible to reliably inject the treatment material 2 under pressure to a desired position. In addition, the treatment material 2 injected therein stays stably at that position for a long time, and the insolubilized liquid, which is the main component of the treatment material 2 in that state, comes into contact with the contaminants. Thus, the insolubilization process with respect to the pollutant proceeds at that position, and finally the pollutant is reliably insolubilized as shown in (e).

According to the treatment method of the present embodiment, the pollutant is insolubilized in the same manner as in the conventional general in-situ insolubilization method, so large-scale excavation and backfilling are not required as in the conventional excavation method. It has excellent workability and is much more advantageous in terms of cost.
In particular, instead of using the liquid insolubilized liquid as it is as in the conventional general in-situ insolubilizing method, a gel-like processing material is used in which a granular polymer filler is added to the liquid insolubilizing liquid. Therefore, even if the treatment target area is a ground with a lot of gravel and cobblestone, the treatment material does not stay in the injection position stably and does not diffuse to the surroundings. Therefore, the conventional in-situ insolubilization treatment method is used. Compared to this, it is less affected by the ground and enables reliable and efficient insolubilization, and is extremely rational and effective as a method for insolubilizing heavy metal contaminated soil in situ.

1 Contaminated soil 2 Treatment material 3 Drilling means 4 Nozzle

Claims (2)

A method for insolubilizing soil contaminated with heavy metals in situ,
A gel-like treatment material obtained by adding a granular polymer filler to a liquid insolubilized liquid is injected under pressure to the treatment target area in the ground, thereby retaining the treatment material in the treatment target area. In situ insolubilization treatment method for heavy metal contaminated soil, wherein the insolubilized liquid in the treatment material is brought into contact with the contaminated soil in a wet state to insolubilize the contaminant. In-situ insolubilization treatment method of heavy metal contaminated soil according to claim 1,
A hole reaching the depth of the region to be processed is formed by a hole drilling means such as a boring hole drill or a mechanical stirring blade type ground improvement machine, and the processing material is introduced into the ground from a nozzle provided at the tip of the hole drilling means. An in-situ insolubilization treatment method for heavy metal-contaminated soil, wherein the treatment material is injected under pressure toward the treatment target region by spraying.

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