JPH0559716A - Method for disposing polluted soil, and its equipment - Google Patents

Abstract

PURPOSE:To purify and washing polluted soil at an original position as it is. CONSTITUTION:The periphery of polluted soil G is surrounded with a constructed impermeable wall 1, and in the polluted soil G, a plurality of metallic hollow pipes 2 to be served as positive electrodes and negative electrodes with a plurality of water- permeable holes 3 bored through are confronted with each other and are arranged as pipe lines A on positive electrode sides and pipe lines B on negative electrode sides. Then, on the polluted soil G, water is properly sprinkled and infiltrated into the soil, and DC voltage is applied to the pipe lines A, B. In the polluted soil G between the pipe lines A, B electroosmosis phenomenon during electrokinetic phenomenon is generated, and polluted substance in the polluted soil G is moved in the negative electrode side direction from the positive electrode side in a liquid phase state, and water is collected in the negative electrode side pipe lines B and is purified. After that, washing water is injected into the positive electrode side pipe lines A from a water tank 5 via a water conducting pipe 6, and the DC voltage is loaded on the pipe lines A, B, and in the polluted soil G, the electroosmosis phenomenon is generated, and the washing water is permitted to flow out of the positive electrode side pipe lines A to be diffused into the polluted soil and is collected in the negative electrode side pipe lines B and is washed with.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is directed to draining water contaminated with pollution-causing substances from the contaminated soil in its original in-situ state, and then discharging the soil from the contaminated soil. The present invention relates to a method for cleaning particles and treating contaminated soil and an apparatus therefor.

[0002]

2. Description of the Related Art Pollution pollutants leaked from the premises of various industries or from factory facilities are washed away around the factory or permeate underground to contaminate the soil in the surrounding area or leach from industrial waste. When the soil is contaminated by harmful substances, there is no conventional method to treat the contaminated soil at the current location, and the soil in the contaminated area is removed and replaced with new soil, or the contaminated water in the soil is removed by the vacuum method etc. The method was being constructed.

[0003]

However, as described above, conventionally, there is no method for treating the contaminated soil at the present position, and the soil in the contaminated area is removed and replaced with new soil, or by the vacuum method or the like. The method of removing contaminated water was used, but for example, in an industrial area such as a landfill composed of fine-grained soil,
An area of very small soil particles,
Therefore, the soil has a low hydraulic conductivity, and there is a problem that there are many soils to which the vacuum method is not applied.

Further, the replacement method has a problem in that a large amount of earth and sand is often carried out and brought in to cause secondary pollution to neighboring residents.

The present invention relates to a method for treating contaminated soil and an apparatus therefor for the purpose of solving the above conventional problems.

[0006]

According to the present invention, there is provided a first step of constructing an impermeable wall around a contaminated soil area from a depth of contaminated soil to a depth at which a permeation flow does not circulate, and an anode and a cathode electrode. A plurality of metal hollow tubes having a large number of water passage holes also serving as the deeper than the depth of the contaminated soil and forming a row of tubes facing each other for the anode and the cathode, and the anode. Installed so that the polarity of the cathode can be changed, water is appropriately sprinkled into the contaminated soil area to penetrate into the soil, and then a direct current is applied to each electrode to face each electrode. By applying a DC voltage to the row of pipes and causing an electroosmosis phenomenon in the contaminated soil between both electrodes, the pollutants in the soil are made to flow in the liquid phase from the anode direction to the cathode direction, and The second step of collecting water in the cathode tube through the pump and pumping it up for purification treatment. After injecting cleaning water into the anode side tube after pumping up the pollutants in the second step, applying DC current to each electrode, applying DC voltage to the tube row facing each electrode, and between both electrodes By causing the electroosmosis phenomenon in the contaminated soil of, the washing water in the anode tube permeates and flows into the soil through the water passage holes of the tube, and the contaminated pore water between the soil particles,
Alternatively, the pollutant can be dissolved or entrained to wash the contaminated soil and allowed to flow into the cathode side tube through the water passage hole, which is then pumped up for water quality inspection and washed until the prescribed water quality standard is reached. Method for treating contaminated soil by the third step of washing with water, and a plurality of bottomed hollow tubes having a large number of water holes formed on the outer peripheral surface are used as electrodes for the anode and the cathode in the contaminated soil. The anode and the cathode are arranged in series so as to face each other to form an anode tube row and a cathode tube row, and a water guide tube having one end communicating with a water tank is disposed in an upper middle portion of each tube row, and the water guide tube is provided. To the cocks projecting at the positions facing the respective hollow tubes of the respective tube rows on both side surfaces, while connecting and fixing the communicating tubes projecting from the upper portion of the respective hollow tubes to the anode side of the DC power source. The hollow tube of the anode tube row is connected, and the cathode tube row is connected to the cathode side of the DC power supply. With connecting each hollow tube, wherein the anode and cathode of each tube row by adopting the device the conversion of each polarity is installed such that free, it solved the above problems.

[0007]

According to the present invention having the above structure, by constructing the impermeable wall around the contaminated soil area, the contaminated underground water in the contaminated soil is prevented from permeating and flowing out of the contaminated area. After that, a direct current is applied to the anode side tube row and the cathode side tube row to utilize the electroosmosis phenomenon during the electrokinetic phenomenon,
Contaminated soil water and wash water in contaminated soil areas,
The soil particles permeate and flow in the direction from the anode side to the cathode side, collect water in the cathode side tube, and pump up the collected contaminated water.

[0008]

EXAMPLE The method of the present invention comprises three steps, and the first step is the step of constructing an impermeable wall, in which pollutants diffuse from the contaminated soil due to permeation of rainwater and the like, and the contaminated area is expanded. In order to prevent this from happening, it is the process of constructing the impermeable wall from the depth of the soil contaminated around the contaminated area to the depth at which the infiltration flow does not go around.

The second step is a step of purifying pollutants, which is made of metal having a large number of small holes or slits serving as both an anode and a cathode or a water passage hole composed of a combination of small holes and slits in the contaminated soil. The hollow tubes are installed in a plurality of rows deeper than the depth of the contaminated soil so that the anode and the cathode face each other, and then a direct current is applied to each electrode to face each electrode. When a DC voltage is applied to the row of tubes, electroosmosis during electrokinetic phenomenon occurs in the contaminated soil between the electrodes, and the soil water in the soil remains in the liquid phase with the pollutant still contained. This is a step of flowing from the direction of the anode to the direction of the cathode, causing it to flow into the tube on the cathode side from the water passage hole, pumping this, and purifying on the ground.

The third step is a washing step, in which cleansing water composed of fresh water for washing or water mixed with a solvent of the pollutant is injected into the anode side tube after pumping up the pollutant in the second step, When a direct current was applied to each electrode again, the liquid in the tube permeated and flowed into the soil from the water passage hole of the anode side tube due to the electroosmosis phenomenon in the electrokinetic phenomenon, and the soil particles were contaminated. Pore water or pollutants are dissolved or entrained to wash the contaminated soil and let it flow into the cathode side tube through the water passage hole.It is pumped up and the water quality is inspected and washed until the specified water quality standard is reached. Is performed, and then wastewater treatment is performed.

The above steps and apparatus will be described in detail below with reference to the drawings. In the step of constructing the impermeable wall of the first step, in order to prevent the pollutant from spreading from the contaminated soil G due to permeation of rainwater to the surroundings and expanding the contaminated area, the area around the contaminated soil G is contaminated. It is a step of constructing the impermeable wall 1 from the depth of the soil to a depth at which the permeation flow does not go around and surrounding the contaminated soil G with the impermeable wall 1. The impermeable wall 1 does not need to be particularly limited, but is preferably constructed by applying direct current electricity to the ground to inject a water-blocking solidifying agent from the anode side and evenly permeate between soil particles. Is recommended.

After the construction of the impermeable wall 1 by the first step is completed, the pollutant second step is started, but before that, the pollutants used in this second step and the next third step are collected. Water is pumped up for purification and cleaning, and at the same time, the hollow tube 2 which also serves as an anode and a cathode is used as a contaminated soil G.
It needs to be installed inside. That is, the soil engineering characteristics of the soil are investigated in the area of the contaminated soil G, and the metal made of a metal that also serves as an anode and a cathode is used based on the average hydraulic conductivity of the soil that constitutes the ground. A plurality of hollow tubes 2 each having a circular or polygonal shape and having a bottom are deeper than the depth of the contaminated soil G, and the hollow tubes 2 for the anode and the cathode are respectively piped into the ground so that they face each other. Set up in rows (see Figure 1). In order to collect contaminated water in the hollow tubes 2, the outer wall surface of each hollow tube 2 preferably has a small size of about 3 to 8 mm. Hole 3a
(FIG. 3), or slits 3b having a width of 5 mm and a length of about 5 cm (FIG. 4), or a combination of the small holes 3a and the slits 3b (FIG. 5), the water passage holes 3 having a certain opening ratio. The hollow tube 2 is provided with a connecting device 4 such as an electric connecting terminal at a portion projecting from the surface of the hollow tube 2.

In the contaminated soil G, two rows of tube rows A and B facing each other as electrodes for the anode and the cathode are installed as one set, and the tube rows A protruding from the surface of the hollow tube 2 are provided. A water conduit 6 whose one end communicates with the water tank 5 is arranged in the middle part of B,
Further, the communication pipes 8 projecting from the upper portion of each hollow pipe 2 are connected and fixed to the cocks 7 projecting at the positions facing the hollow pipes 2 on both sides of the water guide pipe 6. The lead wire 11 drawn from the connecting device 4 of each hollow tube 2 of the tube row A on one side is connected to the cord 10 on the anode side of the power source 9, and the other side is connected to the cord 12 on the cathode side of the DC power source 9. The lead wire 13 drawn from the connecting device 4 for each hollow tube of the tube row B on the side is connected. Although FIG. 1 and FIG. 2 show two sets of tube rows A and B, when the processing area is large, more tube rows are arranged.

After the installation of the hollow tubes 2, the second step of the pollutant purification step is started. Water is appropriately sprinkled into the area of the contaminated soil G by using a water sprinkler to infiltrate into the soil, and then direct current is supplied from the direct current power source 9 through the connection device 4 mounted on the portion of each hollow tube 2 protruding from the surface of the earth. A DC voltage is applied to the tube rows A and B of the hollow tubes 2 which are arranged so as to face each other and alternately serve as anode and cathode electrode tubes by passing a current. By applying a DC voltage to the anode-cathode tube rows A and B, the inside of the contaminated soil G surrounded by the anode-side tube row A and the cathode-side tube row B is subjected to the electrokinetic phenomenon. The electroosmosis phenomenon occurs, and the pollutant in the contaminated soil G flows and moves in a liquid phase in a certain direction from the anode direction to the cathode direction. In this case, the contaminated soil water between the soil particles
The adsorbed water containing pollutants adsorbed on the soil particles also moves between the soil particles from the direction of the anode tube row A to the cathode tube row B. Since both the cathode-side tube row B and the anode-side tube row A use the hollow tubes 2 having the water passage holes 3, these hollow tubes 2 of the cathode-side tube row B can be easily inserted into these hollow tubes 2. The contaminated water of the above flows in through the water passage hole 3 and is collected. And
The soil water collected in each hollow tube 2 of the cathode side tube row B, that is, the soil water containing the pollutant, closes the cock 7 and then opens the upper end opening 14 of each hollow tube 2. More specifically, it is pumped up to the ground by a pump or a vacuum device (not shown), accommodated in a fixed storage tank, and then purified by a known method.

In the step of collecting water in the soil, when the electrode polarity is the same for a long period of time, a polarization phenomenon occurs and the water collecting ability is deteriorated. By changing the polarity of each hollow tube 2, the conventional anode side tube row A becomes the cathode side, and the conventional cathode side tube row B.
To the anode side respectively. This change in polarity stimulates the electrical behavior in the soil, and the water collection capacity of the new cathode side tube row B is significantly improved. When this polarity conversion operation is repeated several times, the water content in the soil is almost reduced, the electric resistance of the contaminated soil G is increased, and almost no water is collected in the tube row B on the cathode side. At this point, it is determined that the electrokinetic phenomenon has ended, and the process for cleaning contaminated soil in the next third step is started.

In the third step of cleaning the contaminated soil G, each hollow tube 2 also used as the electrode used in the second step is used as it is. That is, the wash water consisting of fresh water or water mixed with a solvent of pollutant for washing the contaminated soil G is opened from the water tank 5 at the natural pressure by opening the cocks 7 of the hollow tubes 2 of the tube row A on the anode side. Water is injected into each hollow tube 2 of the tube row A on the anode side through the water conduit 6. The cleaning water injected into each hollow tube 2 permeates and flows into the soil through the water passage hole 3 formed in each hollow tube 2 by the electroosmotic phenomenon during the electrokinetic phenomenon. While passing between the particles, the particles flow in the direction of each hollow tube 2 of the tube row B on the cathode side. By passing the wash water through this soil, the contaminated interstitial water remaining between the soil particles or the Helmholtz layer of contaminants formed around the soil particles is separated and carried with the water. Then, in the liquid phase state, it flows into the tubes from the water passage holes 3 of each hollow tube 2 of the tube row B on the cathode side.

In the third step as well, for the same reason as in the second step, in order to prevent the water collecting ability from being deteriorated due to the polarization phenomenon, the tube rows A and B are set at regular intervals. The polarity of is changed and used. The washed water in the tubes collected in each hollow tube 2 of the cathode side tube row B is closed by a pump or vacuum device (not shown) with the cock 7 of the hollow tube 2 closed. Upper opening 14 of hollow tube 2
While repeatedly carrying out water quality inspection by pumping up from the above, the washing water is repeatedly discharged and collected, and when the prescribed water quality standard is reached, power supply is stopped, and the pumped washed dirty water is drained to contaminated soil G Complete the washing process.

After the treatment is completed, each hollow pipe 2, the water guiding pipe 6 and the communicating pipe 8 installed in the soil are removed.

[0019]

Since the present invention is as described above, it is possible to purify, wash and treat contaminated soil in its original position without affecting other work such as conventional soil replacement. It is also possible to install a hollow tube that also serves as an electrode in the area of the contaminated soil deeper than the depth of the pollution, and the electric conduction phenomenon acts on the soil only in the area surrounded by this hollow tube. Therefore, pollutants dissolved in water will not flow to areas outside this range. Further, since the present invention utilizes the electro-osmosis phenomenon, it is possible to easily use the water or liquid phase containing contaminants adsorbed to fine soil particles such as clayey soil in an electric double layer manner. It is possible to purify the contaminated soil by moving it into the cathode side tube and collecting water by a phenomenological action. Further, the contaminated soil can be cleaned very easily by repeatedly permeating and circulating the cleaning water into the contaminated soil, and the cleaning water after cleaning can be moved into the cathode tube by the electroosmosis phenomenon and collected.

[Brief description of drawings]

FIG. 1 is a schematic plan view of the entire device of the present invention.

FIG. 2 is a vertical sectional view of the device of the present invention.

FIG. 3 is an enlarged front view in which a hollow tube used in the device of the present invention is partially cut away.

FIG. 4 is a partially cutaway enlarged front view showing another embodiment of the hollow tube used in the device of the present invention.

FIG. 5 is a partially cutaway enlarged front view showing still another embodiment of the hollow tube used in the device of the present invention.

[Explanation of symbols]

1 impermeable wall, 2 hollow pipe, 3 water passage hole, 3a small hole, 3b slit, 4 connection device, 5 water tank,
6 water pipes, 7 cocks, 8 connecting pipes, 9 DC power supplies, 10 and 12 cords, 11 and 13 lead wires,
14 Top opening, A anode side tube row, B cathode side tube row, G contaminated soil.

Claims (10)

[Claims] 1. A first step of constructing an impermeable wall around a contaminated soil area from a depth of contaminated soil to a depth at which a permeation flow does not wrap around, and a large number of water passage holes also serving as an anode and a cathode. It is possible to form a row of a plurality of hollow tubes made of metal, which are deeper than the depth of the contaminated soil and face each other for the anode and the cathode, and change the polarity of the anode and the cathode. Installed in such a manner that water is sprayed into the contaminated soil area and penetrated into the soil, and then a direct current is applied to each of the electrodes, and a DC voltage is applied to the row of tubes facing each electrode. However, by causing an electroosmosis phenomenon in the contaminated soil between the two electrodes, the pollutants in the soil flow in the liquid phase state from the anode direction to the cathode direction, and collect in the cathode tube through the water passage hole. The second step of watering and pumping it up to purify it, and the pollutant in the second step After injecting washing water into the anode side tube after raising it, apply a DC current to each electrode, apply a DC voltage to the tube row facing each electrode, and electroosmosis into the contaminated soil between both electrodes. By causing a phenomenon, the washing water in the anode tube permeates and flows into the soil through the water passage holes of the tube, and the contaminated pore water between the soil particles or the pollutant is dissolved or entrained and contaminated. It comprises a third step of washing the soil, allowing it to flow into the cathode side tube through the water passage hole, pumping it up, performing a water quality inspection, and washing until it reaches a prescribed water quality standard. A method for treating contaminated soil, comprising: 2. The method for treating contaminated soil according to claim 1, wherein the water passage holes are small holes. 3. The method for treating contaminated soil according to claim 1, wherein the water passage holes are slits. 4. The method for treating contaminated soil according to claim 1, wherein the water passage holes are a combination of small holes and slits. 5. The method for treating contaminated soil according to claim 1, wherein the cleaning water is fresh water. 6. The method for treating contaminated soil according to claim 1, wherein the cleaning water is water mixed with a solvent of a pollutant. 7. A plurality of bottomed hollow tubes having a large number of water holes formed on the outer peripheral surface thereof are used as an anode and a cathode electrode, and are installed in series so as to face each other in contaminated soil so as to serve as an anode. A tube row and a tube row for cathode are formed, and a water guiding tube whose one end communicates with a water tank is disposed in an upper middle portion of each tube row, and each of the tube rows on both sides of the water guiding tube While connecting and fixing the communicating pipe protruding from the upper part of each hollow pipe to the cock provided at the position facing the empty pipe, each hollow pipe of the above-mentioned anode pipe row is connected to the anode side of the DC power source. The hollow tubes of the tube row for cathode are connected to each other and connected to the cathode side of the DC power source, and the anode and the cathode of each tube row are installed so that their polarities can be freely changed. Equipment for treating contaminated soil. 8. The apparatus for treating contaminated soil according to claim 7, wherein the water passage holes are small holes. 9. The treatment apparatus for contaminated soil according to claim 7, wherein the water passage holes are slits. 10. The treatment apparatus for contaminated soil according to claim 7, wherein the water passage holes are a combination of small holes and slits.