JP2010188220A - Contaminated soil cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a contaminated soil cleaning method, in which a fluid (gas or liquid) for decomposing and removing contaminants by one injection well is injected to a plurality of stratums of different depths even when the stratum of a low permeability coefficient is present. <P>SOLUTION: The contaminated soil cleaning method includes: a process of forming one injection well (10) using a well material (1) provided with a plurality of injection parts (11, 12) for the fluid (gas or liquid); and a process of supplying the fluid to each of the plurality of fluid injection parts (11, 12) through fluid injection pipes (8, 9) and injecting the fluid (B: gas or liquid) from each of the plurality of fluid injection parts (11, 12) into soil G. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention supplies gas or liquid into soil contaminated with, for example, volatile organic compounds (VOC), heavy metals, agricultural chemicals, etc., and decomposes or removes contaminants, thereby purifying the contaminated soil. Related to technology.

As such a soil purification technique, for example, as shown in FIG. 16, gas or liquid is injected into the ground, and soil or groundwater contaminated by pollutants (volatile organic compounds, heavy metals, agricultural chemicals, etc.) is removed. Purifying.
Examples of gases injected into the soil include air, oxygen, and hydrogen. Examples of liquids injected into the soil include nutrient solutions containing dissolved nitrogen and phosphorus, and microorganisms that decompose pollutants. Liquids that generate oxygen, sustained-release oxygen supplies that generate oxygen, sustained-release hydrogen supplies that generate hydrogen, insolubilizers for heavy metals and agricultural chemicals, and the like.

In the prior art shown in FIG. 16, first, a boring hole 2 is dug into the ground containing the contaminated soil Gp below the groundwater level Lw from the ground side Gf by a boring machine (not shown), that is, the soil G, and the well material 1 Place.
An injection part (screen) 11 is formed at the tip of the well material 1.
Then, the nutrient solution stored in the nutrient solution tank 3 installed on the ground side Gf is supplied to the inside of the well material 1 through the fluid injection pipe 6 by the pump 4. Further, compressed air is supplied into the well material 1 through the fluid injection pipe 7 by the air compressor 5 installed on the ground side Gf.

The mixed fluid of the nutrient solution and the compressed air supplied to the well material 1 becomes fine bubbles B from the injection portion 11 at the lower end of the well material 1 and is diffused to the ground G. And the biological effect like the following (a)-(e) is exhibited, and the contaminated soil Gp is purified.
(A) By injecting oxygen, the concentration of dissolved oxygen in the groundwater increases, and purification is performed by activating microorganisms that decompose pollutants.
(B) By injecting nutrient salts, microorganisms that decompose pollutants are activated and purified.
(C) By injecting microorganisms that decompose pollutants, the pollutants are decomposed and purified.
(D) By injecting a chemical that generates oxygen (sustained release oxygen supply agent), the dissolved oxygen concentration in the groundwater rises, and microorganisms (such as fungi) that decompose pollutants are activated, thereby purifying. Done.
(E) By injecting a drug that generates hydrogen (sustained release hydrogen supply agent), the microorganism decomposes the reaction product between the drug and groundwater, generates hydrogen, and is purified by reductive dechlorination. .

And in addition to the biological effect (a)-(e) by underground microorganisms, the volatile organic compound in soil and groundwater volatilizes with the inject | poured air, and purification | cleaning of soil advances.
Alternatively, reductive dechlorination reaction is caused by injecting hydrogen, and the chlorine-based volatile organic compound is decomposed to promote purification.

However, in such prior art, the injected gas or liquid penetrates and diffuses into geological materials having a high hydraulic conductivity such as sandy soil (for example, about 1.0 × 10 ⁻⁶ m / sec or more). It does not permeate and diffuse into geology with a low hydraulic conductivity (for example, less than about 1.0 × 10 ⁻⁶ m / sec).
Therefore, as shown in FIG. 17, in the soil G in which the formations Gs1 and Gs2 having a high permeability coefficient sandwich the formation Gc having a low permeability coefficient in a sandwich shape, the formation is above the formation Gc having a low permeability coefficient (on the ground). Gas or liquid (mixed fluid B thereof) is not sufficiently supplied to the side layer Gs1.
Therefore, there is a problem in that gas or liquid (B) does not reach the contaminated area Gp1 and does not purify the contaminated area Gp1 existing above (on the ground side) the formation Gc having a low hydraulic conductivity. Yes.

In addition, since only one portion for injecting gas or liquid into the soil is provided, if the depth of the contaminated area to be purified is deep, the gas and liquid are sufficiently contained in all the contaminated areas. There is a risk of not being supplied.
If the gas or liquid is not sufficiently supplied, the speed of purifying the pollutants present in the contaminated area is reduced, and in some cases, the pollutants may not be decomposed.

  Alternatively, even if the entire formation is the same soil, it may not always have a constant hydraulic conductivity, and the injected gas or liquid may not diffuse uniformly throughout the formation. Therefore, the pollutant purification rate differs at each depth, and the period necessary for purification as a whole formation may become longer.

Further, as shown in FIG. 18, there is a case where a formation Gc having a low hydraulic conductivity exists in a part of the contaminated region Gp.
In the case as shown in FIG. 18, gas or liquid is not sufficiently supplied to the region (region surrounded by the broken line in FIG. 18) Gpp above (on the ground side) the formation Gc having a low hydraulic conductivity. Therefore, in the region E, there is a possibility that the contaminants remain without being purified.

Further, for example, as shown in FIG. 19, when a contaminated region Gp having a particularly high concentration (high concentration contaminated region) Gpx exists in the contaminated region Gp, the highly contaminated region Gpx is not purified for purification. More gas (oxygen and hydrogen) and liquids (nutrients, microorganisms) are required than parts with low concentrations.
However, as shown in FIG. 19, the injection part 11 for injecting gas or liquid into the ground is below the deepest part of the soil G contaminated region deepest part Gpy and the deepest part of groundwater contamination (the deeper side). It is often installed in.

Therefore, there is a case where the distance between the injection position of the gas or liquid and the high concentration contamination region Gpx becomes long. In such a case, the gas or liquid injected into the soil G is not sufficiently supplied to the high concentration contaminated area.
As a result, a sufficient amount of oxygen or hydrogen for purifying the high-concentration contaminated region Gpx is not supplied, and the purification rate in the high-concentration contaminated region Gpx is slow compared to the low-concentration contaminated portion Gp. As a result, there arises a problem that the purification period becomes longer.

In order to cope with the problem described with reference to FIGS. 17 to 19, it is conceivable to excavate a plurality of injection wells having different depths for injecting gas or liquid and perform purification on a case-by-case basis.
However, drilling a well requires a lot of time, various efforts, and costs (material costs, labor costs, etc.), and excavating multiple wells increases the cost for soil purification. Resulting in.

As another conventional technique, for example, a technique has been proposed in which a nutrient enrichment agent for microorganisms is added directly above a contaminated area above (on the ground side) a formation having a low hydraulic conductivity (see Patent Document 1).
However, in the related art (Patent Document 1), the nutrient enrichment agent for microorganisms cannot be added to the contaminated area located below the formation with a low permeability coefficient, so that it has been described with reference to FIGS. On the other hand, it is not possible to purify the contaminated area below the formation with a low permeability coefficient.

  In addition, as described with reference to FIG. 19, when the high concentration contaminated region Gpx exists in the contaminated region Gp, when the distance from the portion where the nutrient enrichment agent of the microorganism is added to the high concentration contaminated region Gpx is long, There is a problem that the high concentration contaminated region Gpx is not sufficiently purified.

JP 2008-272553 A

  The present invention has been proposed in view of the above-described problems of the prior art, and even if there is a formation with a low hydraulic conductivity, a single injection well can contaminate a plurality of formations at different depths. The purpose is to provide a contaminated soil remediation method that can inject fluids (gases and liquids) that decompose and remove water.

The contaminated soil purification method of the present invention includes a step of creating one injection well (10) using a well material (1) having a plurality of fluid (gas and liquid) injection parts (screens 11 and 12). The fluid is supplied to each of the plurality of fluid injecting portions (screens 11 and 12) via the fluid injecting pipes (8, 9), and the fluid is transferred from each of the plurality of fluid injecting portions (11, 12) into the soil G And (B: a gas or a liquid).
Here, as the fluid (B), a gas (air, oxygen, hydrogen, etc.) or a liquid (a nutrient solution containing dissolved nitrogen, phosphorus, etc., a microorganism containing microorganisms that decompose pollutants, a gradual oxygen generating agent, etc. A release oxygen supply agent, a sustained release hydrogen supply agent for generating hydrogen, an insolubilizing agent for heavy metals and agricultural chemicals, etc.).

  In carrying out the present invention, it is preferable that a partition member (20) is provided between a plurality of liquid injection portions (screens 11 and 12) provided adjacent to each other in the longitudinal direction of the well material (1) ( Claim 2).

  And the said fluid injection pipe (9) is arrange | positioned inside the well material (1), and it is preferable to pass the said partition material (20), and to arrange | position (Claim 3).

  Alternatively, the fluid injection pipe (90) is preferably disposed outside the well material (1) (Claim 4).

  In addition, in the present invention, the fluid injection pipes (8, 9) and a fluid supply source (for example, an air compressor 5 that is an air supply source, for example, a nutrient salt solution pump 4 that is a liquid supply source) are provided. Each of the communicating lines (Lm1, Lm2, Lm3: La1, La2, La3) is provided with a flow control device (40, 50: for example, a flow control device, a regulator, a flow meter), and the soil (G ) In the step of injecting the fluid into the fluid flow rate, it is preferable that the flow rate of the fluid in each fluid injection pipe (8, 9) is individually controlled (Claim 5).

  The well material (1) used in the contaminated soil purification method of the present invention (contaminated soil purification method of claims 1 to 5) has a plurality of fluid (gas and liquid) injection parts (screens 11 and 12), and a well. A partition material (20) is provided between the liquid injection portions (screens 11 and 12) provided adjacent to each other in the longitudinal direction of the material (1), and a well material (1) partitioned by the partition material (20). ) The liquid injection portions (screens 11 and 12) provided at one place in each of the regions in the inside are connected to a fluid supply source (for example, a compressor as an air supply source) via one fluid injection pipe (8, 9). 5. For example, it is characterized in that it communicates with a nutrient salt solution pump 4) which is a liquid supply source (Claim 6).

According to the present invention having the above-described configuration, a single injection well (10) is provided with portions (injection portions: screens 11 and 12) for injecting a plurality of gases and liquids. Decompose gas (air, oxygen, hydrogen, etc.) and liquid (nitrogen, phosphorus, etc. dissolved nutrient solution and pollutants to multiple different depths through injection pipes (8, 9) Those containing microorganisms, sustained release oxygen supply agents that generate oxygen, sustained release hydrogen supply agents that generate hydrogen, insolubilizers for heavy metals and agricultural chemicals) can be injected.
And by injecting gas or liquid, the contaminated soil can be purified (purified by microorganisms) by the biological effects described above in (a) to (e).
At the same time, it is possible to purify the VOC by volatilizing it by injecting air.
Furthermore, by injecting hydrogen, the chlorine-based volatile organic compound can be decomposed and purified by reductive dechlorination reaction.

According to the present invention, a single injection well (10) can inject a gas or liquid into a plurality of formations or regions of different depths, so that contamination with contaminants can be achieved without drilling a plurality of wells. The entire soil (contaminated area) and groundwater can be purified uniformly and in a short period of time.
Therefore, it is possible to greatly reduce the cost related to well drilling.

According to the present invention, as shown in FIG. 17, even if the strata (Gs1, Gs2) with high permeability are sandwiched between the strata (Gc) with low permeability in sandwich form, If the injection part (screen 11) is provided above the ground layer (Gc) with a low coefficient (the ground side), the gas and liquid injected from there into the soil (G) are from the ground layer (Gc) with a low water permeability coefficient. Is sufficiently supplied to the contaminated area (Gp1) existing above (on the ground side), and the effects (biological effects) described above in (a) to (e) and volatilization by injected air. VOC is decomposed and purified by the action and reductive dechlorination reaction by injected hydrogen.
On the other hand, for the contaminated region (Gp2) existing below the formation (Gc) having a low hydraulic conductivity, an injection part (12) is provided below the contaminated region, and if gas or liquid is injected therefrom, The gas and liquid are sufficiently supplied to the contaminated area (Gc) below the formation (Gc) having a low water permeability coefficient, and the pollutants are decomposed and purified.

In addition, since gas and liquid are supplied from a plurality of injection parts (screens 11 and 12), even if the depth to be purified is deep, the gas and liquid injected from a plurality of locations are sufficient for all contaminated regions (Gp). Go around and clean up the pollutants.
Furthermore, even if the entire formation does not have a constant hydraulic conductivity, the gas or liquid supplied from the plurality of injection parts (screens 11 and 12) diffuses throughout the formation, so that only the pollutant purification rate in some areas is obtained. Is prevented, and the period necessary for purification is prevented from becoming longer as the entire formation.

  Furthermore, according to the present invention, as shown in FIG. 18, even if a formation (Gc) having a low hydraulic conductivity exists in a part of the contaminated area (Gp), the formation is higher than the formation (Gc) having a low water coefficient ( If the injection part (screen 11) is provided on the ground side, the gas or liquid injected into the soil from there is sufficiently in the contaminated area (Gpp) existing above the ground layer with a low hydraulic conductivity (on the ground side). The VOCs in the contaminated area above the formation with a low hydraulic conductivity are decomposed by the biological effects, the volatility caused by the injected air, and the reductive dechlorination reaction caused by the injected hydrogen. And purified.

According to the present invention, as shown in FIG. 19, even in the case where there is a particularly high concentration contamination region (high concentration contamination region Gpx) in the contamination region (Gp), the vicinity of the high concentration contamination region (Gpx). By providing the injection part (screen 11), gas (oxygen or hydrogen) or liquid (nutrient salt, microorganisms) injected from the injection part (Gpx) also reaches the high concentration contamination region (Gpx). A large amount of gas or liquid is supplied to Gpx).
Therefore, in the high-concentration contaminated region (Gpx), the biological action effect, the volatilization action by the injected air, and the reductive dechlorination reaction by the injected hydrogen are performed beyond the range where the pollutant concentration is low. . Accordingly, it is possible to prevent the purification rate in the high concentration contaminated region (Gpx) from being slowed down and the purification period of the entire contaminated region (Gp) from being prolonged as compared with the low concentration contaminated portion. is there.

Sectional drawing which shows an outline | summary and an effect in embodiment of this invention. The front view which shows the well material in the injection well used by embodiment. Sectional drawing which shows typically the soil before implementing embodiment. Sectional drawing which shows a boring hole drilling process. Sectional drawing which shows the state which embed | buried the injection well of FIG. Sectional drawing which shows the state which connected the nutrient solution tank and the compressor to the injection well. Sectional drawing different from FIG. 1 which shows the effect of embodiment. Sectional drawing different from FIG.1 and FIG.7 which shows the effect of embodiment. The fragmentary sectional view which shows an injection | pouring part. The fragmentary sectional view which shows a partition part. The fragmentary sectional view which shows the 1st modification of a partition part. The fragmentary sectional view which shows the 2nd modification of a partition part. The fragmentary sectional view which shows the 3rd modification of a partition part. The fragmentary sectional view which shows the 4th modification of a partition part. The fragmentary sectional view which shows the modification which concerns on arrangement | positioning of a fluid injection pipe. Sectional drawing which shows the outline | summary of a prior art. Sectional drawing which shows the outline | summary of the problem of a prior art. FIG. 18 is a cross-sectional view showing an outline of problems different from FIG. Sectional drawing which shows the outline | summary of the problem different from FIG. 17, FIG.

Embodiments of the present invention will be described below with reference to FIGS.
First, an outline of an embodiment of the present invention will be described with reference to FIG.
In FIG. 1, as shown in FIG. 17, below the groundwater level Lw in the ground, the formations (permeable layers) Gs1 and Gs2 having a high permeability coefficient are changed to the formations (hardly permeable layer) Gc having a low permeability coefficient. They are stacked so as to be sandwiched between them.
In the present specification, the upper and lower permeable layers Gs1, Gs2 and the hardly permeable layer Gc may be collectively referred to as “soil G”. In addition, the formations (water-permeable layers) Gs1 and Gs2 having a high water-permeability coefficient may be comprehensively displayed with the symbol Gs.

In FIG. 1, regions (contaminated regions) Gp1 and Gp2 contaminated with, for example, VOC exist in the formation layers (permeable layers) Gs1 and Gs2 having a high permeability coefficient.
The contaminated area Gp1 exists above the hardly water-permeable layer Gc. Further, the contaminated region Gp2 exists below the hardly water-permeable layer Gc.
In the present specification, the contaminated area may be collectively referred to as a symbol Gp.

In FIG. 1, a well material 1 is installed in a borehole 2 excavated so as to penetrate through a contaminated region Gp with a poorly permeable layer Gc sandwiched in soil G, and an injection well 10 is configured.
In the injection well 10, a fluid injection part 11 (upper screen) is provided immediately above the hardly water-permeable layer Gc.
Further, a fluid injection portion 12 (lower screen) is provided at a position deeper than the bottom portion of the lower contaminated region Gp2 at the tip of the injection well 10.
Two fluid injection pipes 8 and 9 are inserted into the injection well 10. The tip of the injection tube 8 opens above the screen 11, and the tip of the injection tube 9 opens in a region between the screen 11 and the screen 12. The fluid injection pipes 8 and 9 are composed of, for example, a vinyl hose, a vinyl chloride pipe, a metal pipe, or the like.

A nutrient solution tank 3 equipped with a supply pump 4 and an air compressor 5 are installed in the vicinity of the injection well 10 on the ground side Gf.
The supply pump 4 is connected to the fluid injection pipe 8 by a line detailed in FIG. The air compressor 5 is connected to the fluid injection pipe 9 through a line described in detail in FIG.

Although shown in FIG. 2 and not shown in FIG. 1, an injection amount adjusting device 40 is interposed between the supply pump 4 and the fluid injection pipes 8 and 9. An injection amount adjusting device 50 is interposed between the air compressor 5 and the fluid injection pipes 8 and 9.
In the illustrated example, only two fluid injection pipes (fluid injection pipes 8 and 9) are provided, but it is also possible to provide three or more fluid injection pipes and three or more screens.

In FIG. 2, the supply pump 4 and the flow control device 40 are connected by a line Lm1, the flow control device 40 and the fluid injection pipe 8 are connected by a line Lm2, and the flow control device 40 and the fluid injection pipe 9 are connected by a line Lm3. Connected with.
The air compressor 5 and the flow rate adjusting device 50 are connected by a line La1, the flow rate adjusting device 50 and the fluid injection pipe 8 are connected by a line La2, and the flow rate adjusting device 50 and the fluid injection pipe 9 are connected by a line La3. Has been.

In the embodiment of FIGS. 1 and 2, the two fluid injection pipes 8 and 9 directed to the injection well 10 are provided with lines La2 and La3 for supplying gas (for example, air) and a liquid (for example, nutrient solution). Supply lines Lm2 and Lm3 communicate with each other in pairs.
A gas such as air and a liquid such as a nutrient solution supplied to each of the two injection parts (screens 11 and 12) are lined by flow control devices 40 and 50 (regulators, flow meters, valves not shown). Each supply amount is individually controlled.

In the injection well 10, a partition material 20 is provided in a region between the upper screen 11 and the lower screen 12.
The fluid injection tube 9 passes through both the upper screen 11 and the partition member 20 and opens below the partition member 20.
The partition material 20 divides the inside of the injection well 10 into a plurality of regions (two regions in FIG. 2), and a gas such as air and a liquid such as a nutrient solution supplied to each region are supplied to other regions. Prevents leakage.
The screens 11 and 12 will be described later with reference to FIG. The configuration of the partition member 20 will be described in detail with reference to FIGS.

As described above, in the embodiment shown in FIG. 1, a plurality of (for example, two) screens 11 and 12 are provided in one injection well 10, and a plurality of depth regions (for example, two locations) in the soil are provided. Injecting gas or liquid.
That is, for example, a nutrient solution and air are supplied from the lower screen 12 to the contaminated region Gp2 below the hardly water-permeable layer Gc. Then, for example, a nutrient solution and air are supplied from the upper screen 11 to the contaminated region Gp1 above the hardly water-permeable layer Gc. And by supplying air and a nutrient solution, the dissolved oxygen concentration in groundwater rises, the microbe which decomposes | disassembles a pollutant is activated, and purification is performed.

As a result, even in a contaminated area (contaminated area Gp1 existing above the hardly water-permeable layer Gc) that could not be purified by the prior art of FIG. Microorganisms that decompose pollutants are activated and the contaminated area is purified.
At the same time, VOC can be volatilized by the injected air to promote purification.
Furthermore, reductive dechlorination reaction is caused by injecting hydrogen, and the chlorine-based volatile organic compound is decomposed for purification.

On the other hand, in the contaminated area Gp2 below the hardly water-permeable layer Gc, microorganisms that decompose pollutants such as VOC are activated by the air or nutrient solution supplied from the lower screen 12, and the contaminated area Is purified.
At the same time, VOC is volatilized by the injected air, and reductive dechlorination reaction occurs by injecting hydrogen to decompose the chlorine-based volatile organic compound, so that purification is performed.

Next, with reference to FIGS. 3-6, the construction procedure of embodiment shown in the drawing is demonstrated.
In the construction, a layer with a low hydraulic conductivity such as a clay layer (for example, a layer with a hydraulic conductivity of less than about 1.0 × 10 ⁻⁶ m / sec: a hardly-permeable layer) by means of survey boring or survey well drilling in advance. The position and depth where a region having a high Gc or high concentration of contamination exists is grasped.

3 to 6, the distribution of the poorly permeable layer Gc and the contaminated regions Gp1 and Gp2 in the soil to be constructed is in a state as shown in FIG.
That is, the water-permeable layer is divided into an upper water-permeable layer Gs1 and a lower water-permeable layer Gs2 by the hardly water-permeable layer Gc, and the contaminated region in the water-permeable layer is also difficult to contaminate the contaminated region Gp1 above the hardly water-permeable layer Gc. Divided into two contaminated regions Gp2 below the water permeable layer Gc.

As shown in FIG. 4, the boring hole 2 is excavated by a boring machine (not shown) so as to penetrate the contaminated region Gp1, the hardly permeable layer Gc, and the contaminated region Gp2.
Then, as shown in FIG. 5, the well material 1 as described in FIG. 2 is arranged in the drilled borehole 2. Here, as described with reference to FIG. 2, the well material 1 has the screen 12 at the lowermost end and the screen 11 at a position corresponding to the upper end of the hardly water-permeable layer Gc.

Although illustration is omitted, as will be described later with reference to FIG. 8, when there is a portion Gpx having a high contamination concentration in the soil G, the screen 11 may be installed at a depth corresponding to the region immediately below the high concentration contamination region Gpx. good.
Although not shown, when the contaminated area extends over a wide range in the vertical direction, a screen can be installed every several meters in the longitudinal direction of the well material 1.

If the well material 1 is installed as shown in FIG. 5, as shown in FIG. 6, the supply pump 4 equipped in the nutrient solution tank 3 and the air compressor 5 are connected to the fluid injection pipe inside the well material 1. Communicate with 8 and 9.
Here, the piping procedure shown in FIG. 6 is the same as that described above with reference to FIG.
That is, the nutrient solution lines Lm1, Lm2, and Lm3 that connect the nutrient solution supply pump 4 and the fluid injection pipes 8 and 9 inside the well material 1 have a flow rate adjustment device 40 that is a nutrient solution injection adjustment device. And controls the amount of nutrient solution solution to be supplied to the fluid injection pipes 8 and 9 inside the well material 1. Similarly, the air supply lines La1, La2, La3 that connect the air compressor 4 and the fluid injection pipes 8, 9 in the well material 1 are also provided with a flow rate adjusting device 50 for compressed air. The amount of air supplied to the fluid injection pipes 8 and 9 is controlled.

If the nutrient solution supply pump 4 and the air compressor 5 are operated in the state shown in FIG. 6 and the amount of nutrient solution and air supplied to the ground is controlled by the flow control devices 40 and 50, the flow shown in FIG. As shown in the figure, an appropriate amount of air and an appropriate amount of nutrient solution are supplied to both the contaminated region Gp1 above the hardly permeable layer Gc and the contaminated region Gp2 below the hardly permeable layer Gc to decompose the VOC. By activating microorganisms that contaminate, contaminated soil can be purified by biological reactions.
At the same time, VOC is volatilized by the injected air to promote purification, and if hydrogen is injected to cause a reductive dechlorination reaction, the chlorine-based volatile organic compound is decomposed and the contaminated soil Gp is purified. The

As shown in FIG. 7, even when the hardly permeable layer Gc exists at a part of the depth of the contaminated region Gp, the region Gpp above the hardly permeable layer Gc (region shown by a dotted line in FIG. 7). Is sufficiently supplied with a gas such as air or a liquid such as a nutrient solution through the upper screen 11.
Therefore, the pollutants present in the contaminated area Gpp are also decomposed and purified by microorganisms activated by air, nutrient solution or the like.
At the same time, VOC is volatilized by the injected air. Further, when hydrogen is injected to cause a reductive dechlorination reaction, the chlorine-based volatile organic compound is decomposed and purified.

Further, as shown in FIG. 8, even when the high-concentration contaminated region Gpx is present at a position separated vertically upward from the lower screen 12 (see FIG. 19 of the prior art), the high-concentration contamination is present. The region Gpx is sufficiently supplied with a gas such as air or a liquid such as a nutrient solution via the upper screen 11.
Therefore, it becomes possible to activate the microorganisms present in the region Gpx to such an extent that a large amount of contaminants present in the high concentration region Gpx can be sufficiently decomposed. Is purified in a short period of time.
At the same time, the VOC is volatilized by the injected air to promote purification. And when hydrogen is inject | poured, reductive dechlorination reaction is started, a chlorine-type volatile organic compound decomposes | disassembles, and the contaminated soil Gp is purified.

Next, the fluid injection part (screen) 11 will be described with reference to FIG.
In FIG. 9, a large number of circumferential slits 11 s are formed on the outer peripheral surface corresponding to the screen 11 of the well material 1, and the cylindrical portion is made of stainless steel in the portion where the slits 11 s are formed. 11 m is provided so as to surround the well material 1. And between the well material 1 and the net-like member 11m made of stainless steel, for example, silica sand 11k is filled.
The air and the nutrient solution supplied through the fluid injection pipe 8 pass through the slit 11s and pass through the space filled with the cinnabar 11k, become fine bubbles and are supplied into the soil.
The screen 12 has the same structure as the screen 11 except that the lower end of the well material 1 is closed.
However, it is added that the structures of the screens 11 and 12 are not limited to those shown in FIG.

Next, the partition part 20 is demonstrated with reference to FIGS.
As shown in FIGS. 1 and 2, the partition 20 is provided in a region between the screen 11 and the screen 12. The material of the partition material is, for example, rubber, resin, metal or the like.
As described above, by providing the partition material 20, the interior of the injection well 1 is divided into a plurality of regions, and gases such as air and nutrients injected into the screens 11 and 12 (or the divided regions in the injection well). Liquids such as salt solutions are prevented from leaking to other areas. Appropriate amounts of air and nutrient solution are supplied from the screens 11 and 12 to the underground G, and air and nutrient solution required for purification are also supplied to the contaminated area Gp, which was difficult to supply with the conventional technology. This is to supply an appropriate amount of.

In the example shown in FIGS. 1, 2, and 10, the partition member 20 is made of an elastic body such as rubber packing, for example, and has a through hole 20 h having an inner diameter smaller than the outer diameter of the fluid injection tube 9. The fluid injection pipe 9 is inserted into the through hole 20h. In the example of FIG. 10, the fluid injection tube 9 is made of metal.
Since the inner diameter of the through hole 20h is smaller than the outer diameter dimension of the injection tube 9, the elastic body of the partition member 20 presses the injection tube 9 by the elastic repulsive force and completely seals it. Therefore, it is possible to prevent the gas or liquid above the partition material 20 from leaking downward from the partition material 20.

Here, as in the modification shown in FIG. 11, a material having rigidity, for example, a resin such as vinyl chloride, may be selected as the material of the partition member 20A. In that case, a male screw (not shown in FIG. 11) is formed on the outer peripheral portion (the portion indicated by the symbol O in FIG. 11) of the partition member 20A, and a female screw (in FIG. 11) formed on the inner peripheral surface of the fluid injection tube 9. The partition member 20A can be positioned and fixed by being screwed together.
In FIG. 11, reference numeral 20Ah denotes a hole for penetrating the fluid injection pipe formed in the partition member 20A.

  Other configurations and operational effects of the modified example shown in FIG. 11 are the same as those of the partition member of FIG.

A modification in which the partition member is made of a material that does not elastically deform is shown in FIG. In other words, the partition member 20 shown in FIG. 10 and the partition member 20B shown in FIG. 12 are configured similarly except that the materials are different.
Here, in the modified example of FIG. 12, when the fluid injection tube 9 is inserted into the through hole 20Bh of the partition member 20B, the gas or liquid existing in the region above the partition member 20B moves along the fluid injection tube 9. In order to prevent leakage into the region below the partition member 20B, the through hole 20Bh formed in the partition member 20B and the fluid injection tube 9 are configured to be a so-called “tight fit”.
Other configurations and operational effects of the modification shown in FIG. 12 are the same as those of the partition member 20 of FIG.

As shown in FIG. 13, a hose sleeve 30 may be installed on the partition member 20 </ b> C, and the fluid injection pipe 9 may be connected to the hose sleeve 30.
In the modification of FIG. 13, the fluid injection tube 9 is a resin hose, for example.
The male thread portion 30t of the hose sleeve 30 is screwed with a female screw (not shown) formed on the partition member 20C, whereby the fluid injection tube 9 is fixed to the partition member 20C via the hose sleeve 30. Here, since the hose sleeve 30 is provided with a flow path (hollow part: not shown) in the central portion over the entire length in the longitudinal direction (vertical direction in FIG. 13), the fluid injection pipe 9A is partitioned. The fluid that communicates with the region below the material 20C and flows through the fluid injection pipe 9A is supplied to the region below the partition material 20C.

  About the other structure and effect of a modification shown in FIG. 13, it is the same as that of the partition material of FIGS.

In the modification shown in FIG. 14, a sealing material 25 is injected into the well material 1 to form a disk-shaped partition material 20 </ b> D. Here, the sealing material 25 is injected into the well material 1 using, for example, an injection device 27.
The partition material 20D configured by the sealing material 25 prevents gas and liquid from leaking between the region above the partition material 20D and the downstream region.
Here, examples of the sealing material 25 include silicon-based, modified silicon-based, urethane-based, acrylic-based, partial chill rubber-based, polysulfide-based, pre-urethane-based, and next-generation isobutylene-based.

  Other configurations and operational effects of the modification shown in FIG. 14 are the same as those of the modification of FIGS.

FIG. 15 shows a modification regarding the arrangement of the fluid injection pipe 90.
1 to 14, all of the fluid injection pipes 9 for injecting gas or liquid are arranged in the internal space of the well material 1, whereas in the modification shown in FIG. 15, the fluid injection pipe 90 is a well. It is arranged outside the material 1.
In FIG. 15, the fluid injection pipe 90 arranged outside the well material 1 communicates with the inside of the well material 1 below the partition material 20 </ b> E.
Since the fluid injection pipe 90 is disposed outside the well material 1, the fluid inflow pipe 90 does not need to penetrate the partition member 20E in the modification of FIG. Therefore, unlike the partition material of FIGS. 1-14, the partition material 20E does not have the through-hole which penetrates the fluid inflow tube 90. FIG.

  Other configurations and operational effects of the modification shown in FIG. 15 are the same as those of the modification shown in FIGS.

According to the illustrated embodiment, a gas or a liquid that contributes to the purification of contaminants can be injected from each of the screens 11 and 12 into the contaminated region Gp (Gp1, Gp2) having different depths.
By injecting such a gas or liquid, the biological effects described in the above items (a) to (e) are exhibited, and the contaminated soil can be purified (purified by microorganisms).
At the same time, it is possible to promote purification by volatilizing the VOC by injecting air.
Furthermore, if hydrogen is injected, a reductive dechlorination reaction occurs, and the chlorine-based volatile organic compound can be decomposed and purified.

Further, according to the illustrated embodiment, the single injection well 10 can uniformly purify the entire soil (contaminated region) Gp contaminated with the pollutant and the groundwater in a short period of time.
That is, it is not necessary to drill a plurality of injection wells, and the cost related to well drilling can be greatly reduced.

According to the illustrated embodiment, when the contaminated regions Gp1 and Gp2 exist so as to sandwich the formation (non-permeable layer) Gc having a low permeability coefficient, the gas or liquid injected from the screen 11 is less than the hardly-permeable layer Gc. Is sufficiently supplied to the upper contaminated region Gp1, so that it exists in the upper contaminated region Gp1 due to biological action, volatility by injected air, and reductive dechlorination reaction by injected hydrogen. Contaminants such as VOC are decomposed and purified.
On the other hand, with respect to the contaminated region Gp2 existing below the formation Gc having a low water permeability coefficient, the gas or liquid injected from the lower screen 12 is sufficiently supplied (to the contaminated region Gp2 below the hardly permeable layer Gc). Therefore, pollutants are decomposed and purified.

Even if the contaminated area Gp to be purified is distributed over a wide range in the vertical direction, the gas or liquid injected from the screens 11 and 12 is supplied to the entire contaminated area Gp. The whole is fully purified.
Furthermore, even if the entire formation is not of a constant hydraulic conductivity, the gas or liquid supplied from the screens 11 and 12 is supplied to the entire formation, so that only the pollutant purification rate in some areas is slow. Absent. Therefore, the period required for purification as the entire formation is shortened, and the construction period can be shortened and the cost can be reduced.

  Further, according to the illustrated embodiment, even if the hardly permeable layer Gc exists in a part of the contaminated region Gp, the gas or liquid injected into the soil from the upper screen 11 is higher than the hardly permeable layer Gc. It is sufficiently supplied to the contaminated area Gpp. Therefore, pollutants such as VOC in the contaminated region Gpp above the hardly water-permeable layer Gc are decomposed by biological action effects, volatilization action by injected air, and reductive dechlorination reaction by injected hydrogen. And purified.

According to the illustrated embodiment, even when the high concentration contaminated region Gpx exists in the contaminated region Gp, the upper screen 11 is provided in the vicinity of the high concentration contaminated region Gpx to purify the high concentration contaminated region Gpx. A large amount of necessary gas or liquid is supplied.
Therefore, it is possible to prevent the purification rate in the high concentration contaminated region Gpx from being slowed down and the purification period of the contaminated region Gp as a whole from becoming long.

The illustrated embodiment is merely an example, and is not intended to limit the technical scope of the present invention.
For example, in the illustrated embodiment, the injection well is provided with two fluid injection pipes and has only one partition part, but three or more fluid injection pipes are installed, and the partition part is divided into two parts. You may provide in more than a location.

DESCRIPTION OF SYMBOLS 1 ... Well material 2 ... Boring hole / boring hole 3 ... Nutrient solution tank 4 ... Discharge pump 5 ... Air compressor 8, 9 ... Fluid injection pipe 10 ... For injection Well 11, 12 ... screen (fluid injection / injection)
20 ... partitioning material 40, 50 ... flow control device G ... soil / ground Gc ... formation / low permeability layer with small permeability coefficient Gf ... ground side Gs, Gs1, Gs2 ... permeability Geologic layer with large coefficient / permeable layer Gp, Gp1, Gp2, Gpp, Gpx ... contaminated area

Claims (6)

  Forming a single well for injection using a well material having a plurality of fluid injection portions, supplying fluid to each of the plurality of fluid injection portions via a fluid injection pipe, A method for purifying contaminated soil, comprising the step of injecting a fluid into the soil.   The contaminated soil purification method according to claim 1, wherein a partition material is provided in a region between the liquid injection portions provided adjacent to each other in the longitudinal direction of the well material.   The contaminated soil purification method according to claim 2, wherein the fluid injection pipe is disposed inside a well material and is disposed through (or penetrating) the partition material.   The contaminated soil purification method according to claim 2, wherein the fluid injection pipe is disposed outside a well material.   Each line connecting the fluid injection pipe and the fluid supply source is provided with a flow rate adjusting device. In the step of injecting the fluid into the soil, the flow rate of the fluid in each fluid injection pipe is individually The contaminated soil purification method according to any one of claims 1 to 4, which is controlled.   In the well material used in the contaminated soil purification method according to claims 1 to 5, the well material has a plurality of fluid injection parts, and a partition material is provided between the liquid injection parts provided adjacent to the longitudinal direction of the well material. The well is characterized in that the liquid injection portion provided in each of the regions in the well material partitioned by the partition material communicates with the fluid supply source through one fluid injection pipe. Wood.

Images