JP3142007B2 - How to remove pollutants from contaminated soil - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing contaminants from contaminated soil, which is suitable particularly when harmful substances such as waste liquid contaminate underground soil over a considerably wide range.

[0002]

2. Description of the Related Art In industrial waste, particularly when harmful substances flow into the ground and contaminate underground soil, if the contaminated soil area is limited to a shallow and narrow area, the contaminated soil is dug up and renewed. Although it is possible to replace the soil with a new one, it is often not possible to use the soil when the depth is relatively deep or when the soil is contaminated over a relatively wide area due to economical factors.

[0003]

In the latter case, for example, an underground contaminated soil area is divided by a water-impervious wall penetrating to a predetermined depth from the ground surface, and a liquid is directed from the contaminated soil area toward the ground surface. A method of removing contaminants by providing a drainage means for sucking up the contaminated liquid by the drainage means is considered.
This method has the advantage that the contaminated area is partitioned by the impermeable wall and the expansion of the contaminated area due to groundwater or the like can be prevented, but even if multiple drainage means are provided or a pump with a large pumping capacity is used. Poor efficiency of sucking up contaminated liquid, which takes time. Therefore, the present applicant has repeatedly studied the above-described contaminant removing method, and as a result, has found a method capable of efficiently and rationally removing underground contaminants, and has accomplished the present invention.

[0004] An object of the present invention is to provide a method for removing contaminants, which makes it possible to remove underground contaminants easily and at low cost and greatly contributes to improvement of contaminated soil.

[0005] To achieve the above object, the present invention provides a method for removing contaminants, in which contaminated soil exists underground.
A method of removing the contaminants by sucking them up to the ground surface together with groundwater or the like, and covering the underground contaminated soil with a vertical impermeable wall penetrating to a predetermined depth from the ground surface to partition the area as a contaminated soil area. by installing a horizontal water-impervious wall surface side whole area of contaminated soil regions defined by the partition walls, as well as partition Ri by the contaminated soil zone to a vertical water-impervious wall and a horizontal water shield wall, contaminated soil region of the segment area Drainage means for sucking up liquid from the surface of the contaminated soil by the drainage means.
Sucks up the contaminated liquid in the area and forms
The groundwater outside the plot area is determined by the difference between the water level values inside and outside the plot area.
The contaminants by the infiltrated groundwater.
The gist is to dissolve and suck up as a contaminated liquid . Ma
In another method of the present invention, the contaminated soil is underground.
In this case, the contaminant is sucked up to the surface with groundwater, etc.
This is a method that removes water from the ground surface to a specified depth.
Vertical impermeable walls cover the underground contaminated soil
The soil is divided into dyed soil areas, and the vertical
Install horizontal impermeable walls on the entire surface side of the stained soil area to
The area is almost sealed with vertical and horizontal impermeable walls
Zoning, and from the contaminated soil area in the
Drain means for sucking up liquid toward the
Up the contaminated liquid in the contaminated soil area
Contamination by non-hazardous liquid introduced into the compartment from the side
Dissolving a substance and sucking it up as a contaminated liquid.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the method of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows an underground cross section when the present invention is implemented as a model. Under the ground, the contaminated soil area 1 is distributed at a deep place, and the contaminated soil area 1 is vertically shielded so as to cover the surrounding area. Water wall 2 is installed, and vertical impermeable wall 2
A horizontal impermeable wall 3 is laid on the entire area on the ground surface a side defined by the above, and drainage means 4 and 5 for sucking liquid from the contaminated soil area 1 toward the ground surface a are provided. Here, as the contaminated soil area 1, for example, a contaminant such as trichlorethylene permeates from the ground surface to the vicinity of an impermeable or poorly permeable clay layer b in the ground and contaminates the soil on the clay layer b. It indicates the area where the degree of contamination actually matters.

The vertical impermeable wall 2 is formed by sequentially arranging unit impermeable boards, and has a lower end positioned above the clay layer b to form a gap 6 with the clay layer b. The vertical water impervious wall 2 may be made of concrete or iron plate. However, in this case, the vertical impermeable wall 2 is made of synthetic resin, and is constructed by a method shown in Japanese Patent Application Laid-Open No. 64-29518. Install,
Good watertightness can be obtained. The horizontal impermeable wall 3 is made of a sheet made of polyvinyl chloride and has a surface a
The entire area defined by the vertical impermeable wall 2 is covered in a watertight state. As the horizontal impermeable wall 3, various impermeable members can be used, and when there is impermeable soil on site, it can be substituted. Drainage means 4,
Although 5 is shown only at one place in the figure, it is actually provided at a plurality of places. The drainage means 4 is located in the contaminated soil area 1 and sucks contaminated liquid or the like from the lower side. A pump 7 is buried in the contaminated soil area 1 and a pipe 8 is directed toward the ground surface a.
Plumbing. On the other hand, the drainage means 5 is set so as to mainly suck up the contaminated liquid or the like from the upper side of the contaminated soil area 1, the pump 9 is installed on the ground a side, and the pipe 1
Zero suction end is located above contaminated soil area 1. The type of the pumps 7 and 9 is determined with reference to the suction head, the groundwater pressure, and the like, and may be installed underground like the pump 7 due to the suction capacity. Each of the pipes 8 and 10 is led to a processing unit 11 provided on the ground a. The treatment unit 11 chemically and physically treats the contaminated liquid and the like sucked up from the contaminated soil area 1 to separate it into a harmful liquid, a non-hazardous liquid, dust, and the like. The liquid is led to the illustrated storage tank, and the non-hazardous liquid is led out of the compartment through the pipe 13. In addition, vertical impermeable wall 2
Water level gauges 14 and 15 are provided inside and outside of the
The water level inside and outside the area defined by the impermeable wall 2 can be detected as needed.

The operation and effect of the above configuration will be described in detail below. It is known that most of the contaminants adhere to soil particles and the like in the contaminated soil area 1 and some exist as undiluted liquid or contaminated liquid dissolved in groundwater.
Contaminants adhering to soil particles etc. were set to be actively dissolved in groundwater and eliminated. First, the contaminated liquid was sucked up through the pipe 8 by driving the pump 7 and supplied to the processing unit 11. Since the specific gravity of the contaminated liquid is larger than that of the groundwater and it is easy to collect in the lower part of the contaminated soil area 1, only the pump 7 is driven in the initial stage, and the pumps 7 and 9 are driven when the contaminated liquid is almost sucked up. hand,
Groundwater and the like in the area defined by the two impermeable walls 2 and 3 were sucked up over a predetermined time. In this process, both impermeable walls 2 and 3
As a result, since the inside of the area is almost closed, the water level value h1 in the area can be reduced to the design value in a relatively short time. This point was also remarkable from the result of comparison with the case where the horizontal impermeable wall 3 was omitted and the operation was performed under substantially the same conditions.
When the water level difference Δh between the water level values h1 and h2 inside and outside the defined area by the water level gauges 14 and 15 reaches the design value, the driving of the pumps 7 and 9 is stopped. In this state, groundwater outside the sectioned area has penetrated into the sectioned area in the direction of the arrow in the figure, and contaminants attached to soil particles and the like are partially dissolved by the infiltrated groundwater. Further, when the value of the water level difference Δh has dropped to the design value, the pump 9 is driven so as to suck up the contaminated liquid dissolved or washed with the groundwater that has invaded from outside the above-mentioned sectioned area. This was repeated several times as a cycle. In the implementation process, in order to examine the removal effect of the present invention, soil samples in the contaminated soil area 1 were collected at each cycle, and the contamination degree of each sample was examined. As a result, it was recognized that the degree of contamination was reduced sequentially in the order of the cycles, as expected, and the degree of contamination of the final sample was reduced to a level that was not a problem.

Therefore, in this embodiment, the contaminated soil area 1 under the ground is partitioned in a substantially sealed state by the two impermeable walls 2 and 3, and contaminated liquid or groundwater in the partitioned area is efficiently sucked up, and simultaneously, inside and outside the partitioned area. By forming a predetermined water level difference Δh and utilizing this water level difference Δh, it is possible to positively infiltrate the groundwater outside the sectioned area into the inside to increase the chance of dissolving pollutants attached to soil particles and the like. The feature makes it possible to remove contaminants efficiently, quickly and at low cost.

FIG. 2 shows another example of the method of the present invention. This embodiment is different from the first embodiment in that the penetration depth of the vertical impermeable wall 2 is changed and that the non-hazardous liquid is recirculated through the pipe 13 into the compartment.
Only the differences will be described. The vertical water-impervious wall 2 is formed by sequentially arranging unit water-impervious plates, and the lower end of the vertical water-impervious wall 2 reaches an impermeable or poorly permeable clay layer b. Accordingly, the inside of the partitioned area is completely sealed by the two impermeable walls 2 and 3 and the clay layer b. The pipe 13 is located outside the contaminated soil area 1 in the partitioned area, and its discharge port is located above the clay layer b.

In this embodiment, the pump 7 sucks up the contaminated liquid as described above. However, after the water level h1 in the partitioned area is reduced to the design value, the pipe 1
The non-hazardous liquid separated in the processing unit 11 is recirculated through 3 and the non-hazardous liquid is used as the infiltrated groundwater in the above embodiment. In other words, the introduced non-hazardous liquid partially dissolves or cleans contaminants attached to soil particles and the like, and pumps the dissolved or washed contaminated liquid through the pump 9.
The gist is to suck up with. In this case, the same operation and effect as those of the above embodiment can be obtained. In addition, for example, an effective cleaning or decomposing liquid is separately added to a non-hazardous liquid, or only a liquid for cleaning or decomposing contaminants is piped. 1
3 can be supplied, and the removal effect can be further improved. In this way, the method of the present invention can be made the best one that is more suited to the actual contamination situation and the like by variously changing the scope of the claims.

[0012]

As described above, in the method for removing contaminants according to the present invention, the efficiency of sucking up contaminated liquid or groundwater from within the partitioned area is significantly improved, and as a result, the soil adhering to the soil is improved. Opportunities to dissolve or wash the contaminants with groundwater or the like are more easily obtained, thereby enabling the contaminants to be economically removed in a relatively short time. Therefore, the present invention is a suitable method particularly in a case where the contaminated soil is deep and a wide area is used, and can greatly contribute to improvement of this type of contaminated soil.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a method for removing contaminants shown as one embodiment of the present invention.

FIG. 2 is a schematic sectional view of a method for removing contaminants according to another embodiment of the present invention.

[Explanation of symbols]

 1 is a contaminated soil area 2 is a vertical impermeable wall 3 is a horizontal impermeable wall 4, 5 is a drainage means a is the ground surface b is a clay layer

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kenzo Okuyama 385-1 Marubayashi, Ogi, Nogi-machi, Shimotsuga-gun, Tochigi (72) Inventor Kanshiro Hoki 970-77, Kujoyama-yama, Nara Prefecture Hei 3-36101 (JP, A) JP-A-52-482032 (JP, A) JP-A-52-60275 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B09B 3 / 00

Claims (2)

(57) [Claims] 1. A method for removing contaminants by drawing them up to the ground surface together with groundwater and the like when the contaminated soil is present underground, wherein the vertical impermeable walls penetrate from the ground surface to a predetermined depth. The surrounding area of the contaminated soil is covered and sectioned as a contaminated soil area, and a horizontal impermeable wall is installed on the entire surface side of the contaminated soil area divided by the vertical impermeable wall, and the contaminated soil area is vertically impermeable and horizontally impermeable. with partitioning Ri by the wall, a drainage means for sucking up liquid toward the ground from the contaminated soil region of said compartment area is provided, on suck contaminated liquid in the contaminated soil zone by the drainage means
And water inside and outside the compartment formed by the suction
The groundwater outside the plot area infiltrates into the plot area due to the difference
The contaminant is dissolved by the infiltrated groundwater and becomes a contaminated liquid.
A method for removing contaminants from contaminated soil, characterized by sucking up . 2. When the contaminated soil is underground,
Pollutants are sucked up to the surface with groundwater and removed.
A vertical impermeable wall penetrating from the ground surface to a predetermined depth.
Cover the area around the contaminated soil below and divide it as a contaminated soil area, and cover the entire surface side of the contaminated soil area divided by the vertical impermeable wall.
Install horizontal impermeable walls to contaminate the soil area with vertical impermeable walls and water.
It is partitioned almost flat by a flat impermeable wall, and
Pumps liquid from the contaminated soil area in the painting area to the ground surface
A drainage means is provided, and the drainage means sucks up the contaminated liquid in the contaminated soil area.
Non-hazardous liquid introduced into the compartment from the ground side
Dissolving the above contaminants and sucking it up as contaminated liquid
A method for removing contaminants from contaminated soil, characterized in that: