JPH10258266A - Method for repairing original position of polluted ground and pollutant treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for repairing the original position of the polluted ground by efficiently recovering oil being a pollutant from the polluted ground to achieve the repairing of the ground and a suitable pollutant treatment apparatus used in the execution of this method. SOLUTION: A water impermeable layer 6 is formed to the ground 2B of a saturated region under a polluted region 4 caused by a pollutant and the sheet pile 18 reaching the ground 2B of the saturated region is arranged around the polluted region 4 to partition the ground containing the polluted region 4 by the water impermeable layer 6 and the sheet pile 8 to be separated from the peripheral ground and washing water is supplied to the water impermeable layer 6 under pressure from the excavated hole 5 formed to the partitioned ground to form the flow of washing water toward ground surface and the washing water is allowed to flow out while oil in the ground is taken in the washing water to recover the oil.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-situ restoration method for contaminated ground and an apparatus for treating contaminants.

[0002]

2. Description of the Related Art In recent years, soil pollution by organic waste such as oil has become a problem. Such soil oil contamination is often found, for example, in connection with land modification when reusing a factory site.

In reusing such ground, as a method of repairing contaminated ground, a pumping well is provided near the area where oil, which is a pollutant, is most concentrated, and groundwater is pumped from the pumping well. Accordingly, a method of recovering oil present near the groundwater table has been generally used.

[0004]

By the way, the kinematic viscosity of oil is generally larger than that of water, and groundwater flows more easily than oil. There was a problem that only easy groundwater was collected, and most of the oil remained in the ground and oil recovery did not proceed.

Moreover, the conventional method is intended for oil contamination of the ground saturated with groundwater, and it has been difficult to recover oil from the ground which is not saturated.

The present invention has been made in view of the above circumstances, and an in-situ restoration method of a contaminated ground for efficiently recovering oil as a contaminant from the contaminated ground and repairing the ground, and a method of repairing the in-situ. It is an object of the present invention to provide a contaminant treatment apparatus suitable for use in the implementation.

[0007]

As a first means for solving the above-mentioned problems, an impermeable layer is formed on the ground below an area contaminated with contaminants, and a water blocking wall is provided around the contaminated area. , The ground containing the contaminated area is separated by the impermeable layer and the water blocking wall to separate it from the surrounding ground, and the washing water is pressurized onto the impermeable layer from the drilling holes provided in the separated ground. An in-situ restoration method of contaminated ground, in which the supply of the cleaning water toward the ground surface by supplying the water, the contaminants in the ground are taken in by the cleaning water, and the contaminated soil flows out to the ground surface to be collected.

[0008] As a second means, the contaminated area is included by forming an impermeable layer on the ground below the area contaminated with contaminants and installing a water blocking wall around the contaminated area. The ground is partitioned by an impermeable layer and a water blocking wall, separated from the surrounding ground, and the high-pressure jet of cleaning water is injected into the contaminated area of the separated ground to stir the contaminated soil, and contaminate the cleaning water with contaminants. In-situ restoration method of contaminated ground that is collected by flowing out to the surface while taking in.

[0009] As a third means, the ground including the area contaminated with pollutants is partitioned by an impermeable layer and a water blocking wall to be separated from the surrounding ground, and penetrated through the contaminated area of the separated ground. A pumping well is provided, and washing water is supplied to the ground surrounding the pumping well and the contaminants are taken into the washing water by passing through the contaminated area and flow into the pumping well, and the washing water is pumped from the pumping well. In-situ restoration method of contaminated ground to be collected by recovery. In the case of this restoration method, the contaminated area may be divided into an impermeable layer and a cutoff wall as in the first and second means, but the contaminated groundwater and the cleaning liquid containing the contaminants may be used. If it does not flow to the surrounding ground, it is not necessary to provide a water blocking wall or an impermeable layer.

[0010] Further, as the contaminant treatment apparatus used in carrying out the first, second and third means, there are provided a washing water supply means for supplying washing water to the contaminated ground, and a cleaning water containing the contaminant. Separation means for collecting water and separating it into contaminants and water, contaminant treatment means for treating contaminants separated from water, and adding cleaning liquid to the water separated from contaminants to regenerate washing water And a washing water supply unit for supplying the regenerated washing water into the ground again.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG. In FIG. 1, oil as a contaminant is present in a part of the ground 2 </ b> A in an unsaturated region which is located above the underground water table 1 and is not saturated with the groundwater. Figure 2 shows a cross section of a contaminated ground with oil present. Drilling holes 5 penetrating the contaminated area 4 are provided in the ground 2A, and a plurality of similar excavating holes 5 are provided outside the contaminated area 4 so as to surround the contaminated area 4. It is assumed that these excavation holes 5 reach the ground 2B in the saturated area saturated with the groundwater located below the contaminated area 4, and the number of the excavated holes 5 is determined in consideration of the range in which the water glass penetrates to form the impermeable layer 6. Is determined, and excavation is performed at appropriate intervals in consideration of the planar extent of the contaminated area 4.

A chemical injection pipe 7 is inserted into these excavation holes 5, and a water glass chemical mainly containing sodium silicate is injected from the lower end of the chemical injection pipe 7 toward the ground 2 B. An impermeable layer 6 is formed below the contaminated area 4 and the surrounding ground 2B. Furthermore, the contaminated area 4
A sheet pile (water blocking wall) 8 is installed on the ground 2A around the surrounding area so as to surround the contaminated area 4. The sheet pile 8 is cast to a depth such that its lower end reaches the water-impermeable layer 6, whereby the ground 2A including the contaminated area 4 is partitioned by the water-impermeable layer 6 and the sheet pile 8, and the surrounding ground is And groundwater flow is cut off. The order of formation of the water-impermeable layer 6 and installation of the sheet pile 8 may be reversed.

Next, the chemical injection pipe 7 inserted into each of the drilling holes 5 is slightly lifted up, and washing water is supplied under high pressure from the lower end onto the impermeable layer 6.
Is filled with the washing water, and a flow of the washing water toward the surface of the ground is generated. Here, the washing water is obtained by mixing a washing solution such as a sodium silicate aqueous solution or a highly biodegradable ester-type nonionic surfactant aqueous solution with water, and the oil is taken into the washing water containing these washing solutions. The kinematic viscosity of the cleaning liquid containing the oil is smaller than the kinematic viscosity of the oil, and the fluidity of the cleaning water is increased. As a result, not only the oil contained in the ground 2B in the saturated region, but also the oil contained in the ground 2A in the unsaturated region located above it is taken into the washing water and separated from the soil, and is separated from the soil with the washing water. leak. The means for pressurizing and supplying the cleaning water to the contaminated ground will be described later.

The washing water containing oil which has flowed out to the ground surface is stored in the pits 9 provided on the ground surface. Therefore, the washing water containing oil is collected in the pollutant treatment device 10 and the oil is treated.

The contaminant treatment apparatus 10 includes a separation apparatus (separation means) 11 for collecting washing water containing oil and separating the same into oil and water, and a bioreactor (contaminated substance) for biologically treating the oil separated from water. A substance treating means) 12 for performing oil treatment. In addition, a washing liquid adding apparatus (washing liquid adding means) 13 for adding a washing liquid to water separated from the oil to regenerate the washing water, and A washing water supply device (washing water supply means) 14 for supplying the washed washing water to the contaminated ground is provided.

The bioreactor 12 is a device for decomposing oil by bacteria grown inside. Further, the bioreactor 12 is provided with an addition device 15 for supplying oxygen, nitrogen, phosphorus, and the like to the inside of the reactor in order to activate bacteria and promote oil decomposition.

The cleaning water supply device 14 is a device for supplying regenerated cleaning water or newly created cleaning water to the contaminated ground. The cleaning water supply device 14 is provided with a mechanism (not shown) for supplying the cleaning water under pressure so that the cleaning water permeates the contaminated ground.

The washing water containing oil recovered from the pit is
After passing through the pre-filter 16, it is taken into the separation device 11 and separated into oil and water saturated with the washing liquid. The oil separated from the water is sent to the bioreactor 12, where it is decomposed by bacteria.

On the other hand, the water separated from the oil is sent to the washing water supply unit 14, and in the process, the washing liquid is added to the water from the washing liquid supply unit 13 to be regenerated as washing water. The regenerated cleaning water is supplied with pressure from the chemical liquid injection pipe 7 to the contaminated ground after the newly created cleaning water is added.

When the contaminated ground is repaired as described above, the following effects can be obtained. Filling the contaminated ground separated from the surrounding ground with wash water will result in a contaminated area 4
The washing water is forced to flow from below to the surface of the ground, and the ground is washed by incorporating oil into the washing water. Therefore, not only the oil contained in the ground 2B in the saturated area but also the oil located above The oil contained in the ground 2A in the saturated region can also be collected and decomposed. Since the chemical liquid injection pipe 7 for forming the water-impermeable layer 6 is used in the pipeline for pressurizing and supplying the cleaning water into the ground, it is not necessary to newly provide a drilling hole, and the construction can be simplified. . The oil is separated from the surrounding ground by the impervious layer and the sheet pile, and the groundwater flow is cut off. Therefore, the washing water that reaches the ground 2A in the saturated area flows out to the surrounding healthy ground and spreads the contamination. Nothing to do. Since the contaminant oil can be treated on the spot, an extra step of transporting the separated oil to another treatment facility for treatment can be omitted, and the repair work can be performed efficiently. In addition, the washing water containing oil can be separated into oil and water, and the oil can be decomposed locally and reused as washing water. For example, the cost of equipment can be reduced.

In this embodiment, the bioreactor 12 is employed as a device for treating oil.
Other processing devices may be employed. An example is an incinerator. In this incineration treatment device, oil is adsorbed on activated carbon or biological activated carbon, and then incinerated and disposed of. Further, the separated oil may be collected and removed as waste.

The cleaning liquid used when preparing the cleaning water is not limited to the above-mentioned aqueous solution, but it is desirable to employ a chemical liquid suitable for cleaning the contaminant of interest.

Next, a second embodiment of the present invention will be described with reference to FIG. Note that components already described in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.
In the present embodiment, the steps up to partitioning the ground 2A including the contaminated area 4 with the impermeable layer 6 and the sheet pile 8 and separating the ground 2A from the surrounding ground are the same as those in the first embodiment.

The cleaning water is supplied from the contaminant treatment apparatus 10 to the contaminated area 4 of the divided ground at a high pressure and is injected toward the contaminated area 4. As a result, the contaminated soil is agitated and the separated contaminated ground is filled with the wash water, and a flow of the wash water toward the ground surface is generated. Then, not only the oil contained in the ground 2B in the saturated area, but also the oil contained in the ground 2A in the unsaturated area located above it is taken into the wash water, separated from the soil, and spilled to the surface with the wash water. I do.

The washing water containing oil that has flowed out to the ground surface is stored in the pits 9 provided on the ground surface. Therefore, the washing water containing oil is collected in the pollutant treatment device 10 and the oil is treated. Subsequent processes are the same as those described in the first embodiment.

When the contaminated ground is repaired as described above, the cleaning effect can be enhanced by injecting the washing water to the ground 2A including the contaminated area 4 and stirring the contaminated soil. The ground can be cleaned more clearly.

Next, a third embodiment of the present invention will be described with reference to FIG. The components already described in the first and second embodiments are denoted by the same reference numerals, and description thereof is omitted. In the present embodiment, the steps up to partitioning the ground 2A including the contaminated area 4 with the impermeable layer 6 and the sheet pile 8 and separating the ground 2A from the surrounding ground are the same as those in the first embodiment.

A pumping well 30 is provided to penetrate the contaminated area 4 of the divided ground. It is assumed that the pumping well 30 reaches the ground 2 </ b> B in the saturated area located below the contaminated area 4 and is excavated immediately before the impermeable layer 6.

Wash water is supplied from the contaminant treatment device 10 to the ground around the pumping well 30. As a result, the washing water permeates the contaminated area 4 and creates a flow of the washing water from the surface to the underground. Then, the oil contained in the ground 2A in the unsaturated region that is not saturated with the groundwater is taken into the washing water and separated from the soil. When the washing water reaches the ground 2B in the saturated region, it flows into the pumping well 30 together with the groundwater.

The washing water that has flowed into the pumping well 30 is pumped up by a pump (not shown), collected in the pollutant treatment device 10, and treated with oil. Subsequent processes are the same as those described in the first embodiment.

When the contaminated ground is repaired as described above, the contaminated ground can be efficiently and clarified, and in addition to being restored to its original state, the ground water can be distributed using natural phenomena. Therefore, since the equipment such as the cleaning water supply mechanism can be relatively small, the cost required for the repair work can be reduced.

In the case of this restoration method, if the ground in the contaminated area is in such a state that the contaminated groundwater or the cleaning liquid containing the contaminants does not flow to the surrounding ground, the water-impermeable layer 6 and the sheet pile 8 may be used. May not be provided. In addition, since the water-impermeable layer 6 and the sheet pile 8 are not necessarily required,
It is also effective when the groundwater table is quite deep from the surface and the unsaturated layer is thick, or when the polluted area is wide.

[0033]

As described above, according to the in-situ restoration method of the contaminated ground according to the first aspect, the contaminated ground separated from the surrounding ground is filled with the washing water to thereby reduce the contaminated area. Forcing flushing water from below toward the ground,
Since the ground is washed by incorporating contaminants into the cleaning water, contaminants present in the unsaturated area of the ground, which were not possible in the past, can be collected and treated in situ, and contaminated ground can be removed. It can be efficiently and clarified and restored to its original state.

According to the in-situ restoration method of the contaminated ground described in claim 2, it is possible to enhance the cleaning effect of the contaminated soil by injecting the washing water into the contaminated area of the ground and stirring the contaminated soil. Thus, the contaminated ground can be cleaned more clearly.

According to the in-situ restoration method of the contaminated ground described in claim 3, the cleaning water is infiltrated from the surface of the ground, and is collected from the pumping well together with the groundwater in the saturated region of the ground, so that the cleaning water utilizing the natural phenomenon is used. Ground distribution is possible, and the equipment such as a washing water supply mechanism can be relatively small-sized, so that the cost for repair work can be reduced.

According to the contaminant treatment apparatus of the fourth aspect, since the contaminant can be treated on the spot, an extra step such as transporting the contaminant to another treatment facility for treatment is carried out. The restoration work can be performed efficiently by omitting the above. In addition, it is possible to separate the cleaning water containing the contaminants into contaminants and water, and to reuse the water as cleaning water while treating the contaminants. For example, the cost of equipment can be reduced.

[Brief description of the drawings]

FIG. 1 is an elevational sectional view showing a first embodiment of an in-situ restoration method for contaminated ground according to the present invention.

FIG. 2 is an elevational sectional view showing a second embodiment of the in-situ restoration method of the contaminated ground according to the present invention.

FIG. 3 is an elevational sectional view showing a third embodiment of an in-situ restoration method for contaminated ground according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Groundwater surface 2A Unsaturated ground 2B Saturated ground 4 Contaminated area 5 Drilling hole 6 Impervious layer 7 Chemical liquid injection pipe 8 Sheet pile (water stop wall) 10 Pollutant treatment device 11 Separation device (separation means) 12 Bio Reactor (Contaminant treatment means) 13 Cleaning liquid addition device (Cleaning liquid addition device) 14 Cleaning water supply device (Cleaning water supply device) 30 Pumping well

Claims (4)

[Claims] 1. An impermeable layer is formed on the ground below an area contaminated with pollutants, and a water blocking wall is installed around the contaminated area, so that the ground including the contaminated area is stopped by the impermeable layer. Wash water heading from the bottom of the contaminated area to the surface by separating the contaminated ground with the water wall, separating the contaminated ground with the clean water, supplying wash water over the impermeable layer under pressure, and filling the separated contaminated ground with the wash water. A method for in-situ restoration of contaminated ground, characterized by creating a stream of water, and allowing the contaminants to flow into the surface of the washing water and collecting the contaminants. 2. An impervious layer is formed on the ground below an area contaminated with pollutants, and a water blocking wall is installed around the contaminated area. Separate with the water wall to separate from the surrounding ground, and inject cleaning water at high pressure into the contaminated area of the divided ground to agitate the contaminated soil and fill the separated ground with the cleaning water. A method for restoring in-situ contaminated ground, comprising: creating a flow of washing water from the lower side of the contaminated area to the surface of the soil, and allowing the contaminants to flow into the washing water and recovering the contaminated soil. 3. A pumping well is provided through an area contaminated with contaminants, and washing water is supplied to the surface around the pumping well and permeated through the contaminated area so that the contaminants are taken into the washing water. And recovering the in-situ contaminated ground by pumping the washing water from the pumping well and collecting it from the pumping well. 4. A contaminant treatment apparatus used in the method for repairing contaminated ground in situ according to claim 1, wherein cleaning water supply means for supplying cleaning water to the contaminated ground. A separation means for collecting and cleaning water containing pollutants and separating the pollutants into water; a pollutant treatment means for decomposing and treating the water and the separated pollutants; and a cleaning solution for the water separated from the pollutants. A contaminant treatment apparatus comprising: a cleaning liquid adding means for adding water to the cleaning water to regenerate the cleaning water; and a cleaning water supply means for supplying the regenerated cleaning water into the ground again.