JP2000279966A - Device for cleaning polluted underground water by electrolysis and light irradiation and cleaning method using same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently decompose pollutants in underground water by forming a well reaching a polluted underground water layer, installing a pair of electrodes in the underground water in the wall, and also providing a means for continuously feeding electrolyte into the underground water in the well and a means for irradiating the underground water in the well with light. SOLUTION: A well l2 is constructed so as to reach an underground water layer, and an underground water storing part 8 in the wall 2 is provided with an agitator 10, and an anode 3 and a cathode 4. Furthermore, solution of high concentration of electrolyte is fed by a pump 7 through a pipe 6 to make the underground water of an underground storing part 8 in the well 2 electrolytic solution. When power is fed to the anode 3 and the cathode 4 for electrolysis from a power source 5, acidic water and alkaline water are formed on the anode 3 side and on the cathode 4 side respectively, and they are mixed by a miser 10 together with the underground water which has not been electrolyzed to turn the total into functional water. And while power is fed to the electrodes 3, 4, the functional water is irradiated with light from a light source 9 installed in the well 2, thereby decomposing organic compounds in the functional water.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to the remediation of soil pollution by organic compounds. For more details,
The present invention relates to an apparatus for remediation of soil contamination in situ, more precisely, to a purification apparatus for groundwater contaminated by soil contamination and a purification method using the purification apparatus.

[0002]

2. Description of the Related Art In recent years, environmental pollution by hydrocarbons such as aromatic hydrocarbons, paraffins and naphthenes, and organic chlorine compounds such as trichloroethylene, tetrachloroethylene and tetrachloroethane has become a problem. Many of these penetrate into the soil and remain undissolved, gradually dissolving in groundwater and expanding the contaminated area through groundwater. It is strongly desired to establish a technique for preventing the reoccurrence of these serious environmental pollutions and for purifying the already-polluted environment and returning it to its original state.

[0003] As an example of this environmental restoration technique, there is a method of removing or decomposing contaminants by digging and heating contaminated soil. However, these physicochemical treatments may be effective, especially at high concentrations and local contamination, but at enormous costs when the contamination is extensive.

A method called vacuum extraction, in which a boring hole is provided in contaminated soil and a contaminant is sucked by vacuum, is used.
It is often used as a physical purification method for soil in u, but the problem is that the purification rate is low when the concentration of contamination is low, and there are parts where the suction of contaminants is impossible due to the structure and properties of the soil. There is.

[0005] As a method for solving these problems of physicochemical treatment, biological treatment with microorganisms has been studied. However, it is difficult to spread microorganisms having a certain particle size in the contaminated soil.If a method of mixing the microorganisms by slurrying the soil is used, it is possible to maintain low cost, which is an advantage of the microorganism treatment. There have been problems such as disappearance and difficulty in post-treatment of the slurried soil.

On the other hand, when only groundwater is to be purified, there is a problem that the purification period is prolonged because the soil itself is not purified. Has the advantage of being able to use groundwater at low cost and to prevent the diffusion of pollutants. As a method for purifying groundwater, there is a method in which contaminated groundwater is pumped and purified on-site.

However, when the flow rate of groundwater is high, the cost for pumping water increases, and there are restrictions on returning groundwater once pumped to the groundwater layer. Problems such as exhaustion occur. Therefore, when such a problem occurs, in-situ
There is a need for purification of groundwater in the country.

[0008] Groundwater purification methods in-situ include:
A method of purifying groundwater by charging activated carbon into a groundwater layer and adsorbing contaminants on the activated carbon has been used. However, even if activated carbon can absorb contaminants,
There was a problem that a treatment for further detoxifying this was necessary.

As a method of decomposing contaminants in-situ, there has been proposed a microbial treatment such as injecting contaminant-decomposing microorganisms into a groundwater layer or introducing microorganisms fixed on a carrier (Biotreatment News: Vol. 3, No.9, August 199
3, p1, Soil & Groundwater Cleanup: December 1995, p36
-43, JP-A-07-096289).

When injecting microorganisms into a groundwater layer, there is a problem of secondary contamination by microorganisms. When microorganisms are immobilized on a carrier, the problem of contamination of groundwater by microorganisms is avoided, but the decomposition activity decreases over time,
Degradation ability does not continue in the state as it is, and it is necessary to re-activate the decomposition activity, and if the fixed microorganisms die and lyse, the microbial cell components leak to the groundwater. There was a problem.

[0011]

As described above, in-situ
Not many techniques have been studied as a method for purifying groundwater at the same time, and the methods studied have also had practical problems. The present invention has been made in view of the above,
It is an object of the present invention to provide more practical and efficient
An object of the present invention is to provide a -situ purification device and a purification method using the purification device.

[0012]

Investigations have been conducted with the aim of achieving the above-mentioned problems, and as a result, a sterilizing effect (see Japanese Patent Application Laid-Open No. 1-180293) and a cleaning effect of contaminants on semiconductor wafers (see, for example, Japanese Patent Application Laid-open No. (See Kaihei 7-51675) The fact that functional water obtained by electrolysis of water, which is reported to have water, is produced in contaminated groundwater and then irradiated with light to purify the groundwater in-situ And led to the present invention.

That is, in one embodiment of the present invention,
The -situ groundwater purification device is a well that reaches a contaminated groundwater layer, a pair of electrodes installed in the groundwater in the well, and a means for applying an electric potential to the electrodes, and continuously supplies an electrolyte to the groundwater in the well. Means, means for irradiating the groundwater in the well with light, producing functional water in the groundwater by electrolyzing the groundwater containing the electrolyzed water, and irradiating the groundwater with the light. Characterized in that it has a function of decomposing contaminating organic compounds. Also,
The in-situ groundwater purification method according to one embodiment of the present invention includes drilling a well reaching a contaminated groundwater layer, continuously supplying electrolyte to groundwater in the well, and electrolyzing groundwater containing the electrolyte. To generate functional water,
By irradiating the groundwater containing the functional water with light, the pollutants in the groundwater are decomposed in the groundwater layer.

The reason why the organic compound is decomposed by irradiation of functional water and light as described above is not clear. However, for example, water generated by electrolysis of water containing an electrolyte such as sodium chloride contains hypochlorous acid or hypochlorite ion, and this hypochlorous acid or hypochlorite ion is acted upon by the action of light. It is thought that they induce chlorine radicals, hydroxyl radicals and superoxide, and act on decomposition.

Japanese Patent Application Laid-Open No. 8-281271 discloses a technique for decomposing a dye in a dyeing wastewater in an electrolytic cell by hypochlorous acid and / or hypochlorite ions generated by electrolysis.

Further, the magazine "Water Treatment Technology": Vol. 37, No. 5 (1996)
P.33 describes the treatment of dyeing wastewater using an electrochemical reaction.In the indirect electrolysis method as a method of decomposing the coloring component molecules of the dye by electrolysis, an oxidizing agent is generated by electrolysis, and the Mostly, hypochlorous acid is used as an oxidizing agent, and chlorine gas generated at the anode when sodium chloride is added to wastewater and electrolysis is performed at the cathode. It is described that it is generated by a reaction with generated hydroxyl ions.

However, there is no description in these documents (patent publications and magazines) suggesting that the contaminated groundwater of halogenated aliphatic hydrocarbon compounds and aromatic compounds is purified in-situ by these methods. I can't. Further, the publication does not describe irradiation with light to promote decomposition.

In the example disclosed in Japanese Patent Application Laid-Open No. 9-234486, an electrode is installed in a contaminated groundwater layer to perform electrolysis, but instead of directly decomposing pollutants, hydrogen generated by electrolysis is used. This is an on-site treatment in which groundwater is introduced into a bioreactor that has been made anaerobic by introducing it, and there is no description about the purpose of in-situ purification of groundwater.

[0019]

Embodiments of the present invention will be specifically described below with reference to the drawings. First, in the present invention, a well is constructed to reach contaminated groundwater. A well-drilling method may be a commonly used method. The diameter of the well is preferably large, but is appropriately selected from the viewpoints of boring technology and cost. When a well with a small diameter is used, it is necessary to increase the number of wells. When installing multiple wells,
It is effective to place it across the contaminated groundwater aquifer when viewed from above.

It is desirable that the well wall does not impede the inflow of groundwater into the well, and that the permeation rate of the groundwater into the well be as close as possible to the flow rate of the original groundwater as long as the structural strength of the well is maintained. Is desirable. Therefore, the well wall is made of a water-permeable material, such as a large number of small holes. Also,
In order to prevent the well from being filled with earth and sand, it is desirable if the water-permeable wall can be limited to only a portion in contact with the groundwater layer.

In the present invention, an electrolyte is dissolved in contaminated groundwater,
This is electrolyzed to produce functional water from the groundwater itself. Since the groundwater continuously flows into the well pit, it is necessary to continuously supply the electrolyte to the groundwater in the well pit and perform the electrolysis continuously.

The functional water in the present invention is, for example, an electrolyte
(For example, sodium chloride or potassium chloride) is dissolved in water, and this water is electrolyzed by a pair of electrodes to mix acidic water obtained on the anode side and alkaline water obtained on the cathode side. In order to decompose organic compounds, it is more efficient to use only acidic water obtained on the anode side, but for that purpose, it is necessary to shut off between the anode and the cathode with a porous membrane. It is not suitable for in-situ purification of groundwater flowing continuously. Therefore, the apparatus and method of the present invention do not use a diaphragm, and thus the acidic water and the alkaline water produced in the well are mixed to some extent.

When the purified groundwater is discharged out of the well, it is desirable that the pH returns to near neutrality. Therefore, it is preferable to mix the acidic water and the alkaline water more positively.

Desirable functional water properties include a hydrogen ion concentration (pH value) of 4 to 10 and an oxidation-reduction potential of 300 to 1100 mV when the working electrode is a platinum electrode and the reference electrode is silver-silver chloride. Range and chlorine concentration 2-11
It will be in the range of 00 mg / l.

When the functional water is adjusted to have the above-mentioned properties, the concentration of the electrolyte in the groundwater in the well before the electrolysis is preferably in the range of 20 to 2000 mg / l for sodium chloride, for example. The electrolytic current value at that time is 2
It is desirable to be in the range of 20A.

The properties of the functional water generated according to the inflow rate of the groundwater can vary, but the amount of the electrolyte supplied to the groundwater and the voltage applied to the electrodes are adjusted so that the concentration of the electrolyte and the electrolytic current value fall within the above ranges. By maintaining the properties, the properties of the functional water can be maintained.

As a method of supplying an electrolyte such as sodium chloride or potassium chloride to the groundwater in the well, any method may be used, but a method of supplying a high-concentration electrolyte solution by a liquid feed pump may be used. .

The concentration of the electrolyte in the groundwater in the well varies depending on the inflow speed of the groundwater, and in some cases, the concentration of the functional water that can decompose the organic compound in the groundwater cannot be maintained. Therefore, the supplied electrolytic mass may be controlled by monitoring the concentration of the electrolyte in the groundwater in the well, and the characteristics of the functional water generated by the electrolysis may be controlled to be in the above-described range.

The above-mentioned various functional waters generated by electrolysis are all decomposed by irradiating light. At this time, as described in the previous section, the functional water generated by the electrolysis of water containing an electrolyte such as sodium chloride contains hypochlorous acid or hypochlorite ions. It is considered that chloric acid or hypochlorite ion induces a chlorine radical, a hydroxyl radical or a superoxide by the action of light to accelerate a decomposition reaction of an organic compound.

As the light to be irradiated when the organic compound is decomposed by the functional water, light having a wavelength in the range of 300 to 400 nm may be used. As the light irradiation intensity, for example, a light source having a peak in a wavelength range of 365 nm is 0.1 mW / cm ² (3
(Measured between 00 and 400 nm), the decomposition proceeds, and 1 mW / cm ² or more is practically sufficient.

As a light source of such light, a mercury lamp,
Artificial light such as a black light or a color fluorescent lamp may be used, and sunlight may be used if the light is condensed and guided to a decomposition tank by an optical fiber or the like.

Since the efficiency of light irradiation is highest when the functional water is in contact with the organic compound, a light source is installed so that as much light as possible is irradiated to a region where the concentration of the functional water generated in the groundwater is high. I do. If there is sufficient mixing of groundwater and functional water in the well, such as when the well has a stirring function, any portion of the groundwater in the well may be irradiated with light. It is desirable to increase the area irradiated with the light.

Mixing the groundwater other than the groundwater used for the production of the functional water with the functional water enhances the purification efficiency. Therefore, it is effective to stir the groundwater in the well.

As the stirring means, any method such as rotating a stirring blade by a motor may be used.
In order to reduce costs and equipment, a method of stirring using a groundwater flow may be adopted without introducing external power.
For example, by installing a plurality of rod-shaped piles in the decomposition tank, or by installing a U-shaped cross section opening to the upstream side of the groundwater and causing a turbulent flow in the groundwater flow flowing in the decomposition tank, It is also possible to carry out stirring.

It is conceivable that the decomposition rate may decrease due to changes in the flow rate of groundwater or the concentration of pollutants in groundwater. By controlling the supply speed, the voltage supplied to the electrodes, and the light irradiation intensity, it is possible to maintain the decomposition efficiency to some extent while keeping the cost for the electrolyte and electric power low.

The organic compounds to be decomposed include, for example, halogenated aliphatic hydrocarbon compounds and biphenyl compounds. Examples of halogenated aliphatic hydrocarbon compounds include trichloroethylenecrene and tetrachloroethylene, and examples of biphenyl compounds include PCB.
Is mentioned.

In the functional water after the decomposition of the various compounds described above, no new generation of organic compounds which is considered to have a bad influence on the environment at present is not observed, for example, by mass spectrum or the like.

An embodiment of the in-situ purification apparatus for contaminated groundwater according to the present invention will be described with reference to FIG.
In FIG. 1, groundwater 1 flows in the direction of the arrow, and a well 2 is constructed so as to reach the groundwater layer. Groundwater 1
Is continuously supplied to the groundwater storage portion 8 in the well from a hole formed in the outer wall of the well 2.

The groundwater storage portion 8 in the well is stirred by a stirrer 10 installed. The anode 3 and the cathode 4 are provided at an appropriate interval in the groundwater storage portion 8 in the well, and a high concentration solution of the electrolyte is supplied through a pipe 6 by a pump 7 to make the groundwater storage portion 8 in the well an electrolyte solution. .

Power supply 5 is connected to anode 3 and cathode 4 for electrolysis.
When electric power is supplied from the apparatus, acidic water is generated on the anode 3 side and alkaline water is generated on the cathode 4 side, and mixed with the ground water that has not been electrolyzed by the stirring device 10 to form the entire functional water in the present invention. The functional water contains organic compounds to be decomposed which are brought in from contaminated groundwater.

At the same time as supplying power to the electrodes, the functional water is irradiated with light by the light source 9 installed in the well 2. Thereby, the organic compounds contained in the functional water are decomposed. The purified functional water is discharged to the groundwater layer outside the well 2 through a hole formed in the outer wall of the well.

In addition, a tube 11 and a pump 12 for sampling the groundwater in the well are provided to monitor the concentration of the electrolyte or the concentration of the pollutant in the groundwater in the well. If the flow rate of groundwater increases the concentration of electrolyte in the wells and makes it impossible to create functional water of the required capacity to decompose contaminants in groundwater, increase the feed rate of the electrolyte.

When the flow rate of groundwater is increased, or the concentration of contaminants in groundwater is increased, and the processing load of contaminants is increased, the speed of supplying chemicals and the intensity of light irradiation are increased to increase the functional water. To reduce the decomposition efficiency to some extent. Although various embodiments according to the present invention have been specifically described above, it is needless to say that the present invention is not limited to these embodiments.

[0044]

[Example 1] (Purification test of trichlorethylene) [Example 1-A] (Description of the apparatus used for the test) As shown in FIG. 2 (overall view of the test apparatus), a width of 100 cm, a depth of 20 cm, As shown in the figure, a stainless steel partition plate 52 was provided at a position 5 cm from both ends of a sealable stainless steel tank 51 having a height of 50 cm. A hole having a diameter of 3 mm is formed in a portion 30 cm from the bottom of the partition plate.
At one end of the tank, a drain 53 is provided at a height of 30 cm from the bottom, and the space separated by the wall of the tank with the drain and the partition plate is a model groundwater discharge chamber 54, and the wall of the tank on the opposite side and the partition plate. The partitioned space was used as a model groundwater supply chamber 55. Two stainless steel tubes having a diameter of 10 cm were arranged side by side in the center of the tank, and this was used as a model well 56.

A hole having a diameter of 3 mm is formed in a portion 30 cm from the bottom of the model well. Gravel with a particle size of about 5 mm was filled around the model well between the two partition plates to form a model groundwater layer. When pure water is injected into the groundwater supply chamber as model groundwater by the tube pump 55, the model groundwater penetrates into the model groundwater layer, the inside of the model well 51, and the groundwater discharge chamber 54, raises the water level, and eventually from the drain 53 of the groundwater discharge chamber 54. Is discharged. When the model groundwater is discharged from the drain 53, the groundwater supply chamber 5
The model groundwater injected into 5 flows as a laminar flow through the model groundwater layer, and is discharged into the groundwater discharge chamber 54 in a planar manner. The above modeled the movement of groundwater in the ground and the wells provided in it.

Next, as shown in FIG. 3 (enlarged view of the model well), two 5 cm × 10 cm platinum electrodes (60) with cords were placed near the center of the well at intervals of about 3 cm in the two model wells. A black light fluorescent lamp (trade name: EFD15BLB) at a position 5 cm above the groundwater surface to illuminate the entire groundwater surface in the well so that the stirring blade 61 comes under the electrode. ; Toshiba Corporation, 15W, wavelength 300 ~ 4
(00 nm) 63 was installed.

Then, power is supplied from the power source 69 to the electrode 60 and the black light fluorescent lamp 63.
Further, a tube 64 for dropping a sodium chloride solution as an electrolyte into groundwater in the well was provided. Also, Teflon (registered trademark) for sampling groundwater in wells
The tube 81 and the pump 82 made from the product were installed.

(Confirmation of generation of functional water) Flow rate of groundwater was 2 to 4
cm / hr, supply 10% sodium chloride solution as an electrolyte to the well so that the concentration in the well is in the range of 0.002 to 0.2% at the time when the electrolysis is not performed, and the groundwater in the well is 60 rpm Apply voltage to the electrode while stirring with
Current was applied in the range of A. When the production conditions of the functional water were variously changed, the pH of the water in the well was changed to 4 to 10, the oxidation-reduction potential was changed to 300 to 1100 mV, and the chlorine concentration was changed to 2 mg / l to 100 mg / l.

(Purification test) The flow rate of groundwater containing 5 ppm of trichlorethylene was adjusted every 2 days to a range of 2 to 4 cm / hr.
Raised every 1 cm / hr. Meanwhile, as an electrolyte in the well
A 10% sodium chloride solution was supplied at 2.5 ml / hr, and a voltage of 5 A was applied to the electrode 60 while agitating the groundwater in the well at 60 rpm. Further, light was irradiated by a black light fluorescent lamp 63. At this time, the fluorescent lamp 6 was adjusted so that the irradiation light amount on the groundwater surface was 0.2 mW / cm ^2.
The voltage applied to 3 was adjusted. Thereafter, the concentration of trichlorethylene in the groundwater was measured every 24 hours. The trichlorethylene concentration should be measured by sampling 1 ml of groundwater in the well from a sampling tube, immediately placing it in a container containing 10 ml of n-hexane, stirring for 3 minutes, separating the n-hexane layer, and measuring by ECD gas chromatography. Asked by. FIG. 4 shows the results.

When a similar test was performed using no electrolyte, no electrolysis, and no light irradiation as a control test, no decomposition of trichloroethylene was observed. FIG. 4 also shows the results when light irradiation was not performed (control test). From this test, it can be seen that trichlorethylene in groundwater can be decomposed by electrolyzing groundwater and further irradiating light.

[Example 1-B] The groundwater in the well was sampled every 24 hours, and the sodium chloride concentration in the sample was measured by a salt concentration meter to monitor the sodium chloride concentration in the groundwater in the well. And
The same test as in Example 1-A was performed except that the supply rate of the sodium chloride solution was changed so that the concentration of sodium chloride in the groundwater was 0.005%. FIG. 4 shows the results.

This test shows that by measuring the concentration of the electrolyte in the groundwater and controlling the rate of supplying the electrolyte according to the concentration, the decomposition efficiency of trichlorethylene in the groundwater is improved.

[Example 1-C] The concentration of trichlorethylene in the groundwater in the monitored well was lower than that in the previous measurement.
The same test as in Example 1-A was performed except that the supply rate of sodium chloride was doubled when the rate increased by 10% or more. FIG. 4 shows the results.

This test shows that by measuring the concentration of trichlorethylene in groundwater and controlling the rate of supplying the electrolyte according to the concentration, the decomposition efficiency of trichlorethylene in groundwater is improved.

[Example 1-D] The concentration of trichlorethylene in the groundwater in the monitored well was lower than that in the previous measurement.
When the voltage increased by 10% or more, the same test as in Example 1-A was performed except that the voltage supplied to the electrode for performing electrolysis was increased and the current was increased by 3 A. FIG. 4 shows the results.

This test shows that by measuring the concentration of trichlorethylene in groundwater and controlling the voltage supplied to the electrodes according to the concentration, the decomposition efficiency of trichlorethylene in groundwater is improved.

[Example 1-E] The concentration of trichlorethylene in the groundwater in the monitored well was lower than that in the previous measurement.
When the voltage rises by 10% or more, the voltage supplied to the fluorescent lamp is increased, and the irradiation light amount on the groundwater surface is 0.15 mW
The same test as in Example 1-A was performed, except that / cm ^{2 was} increased.
FIG. 4 shows the results.

This test shows that by measuring the concentration of trichlorethylene in groundwater and controlling the intensity of light irradiation in accordance with the concentration, the decomposition efficiency of trichlorethylene in groundwater is improved.

[Example 2] (Purification test of tetrachloroethylene) [Example 2-A] The same test as in Example 1-A was conducted except that the contaminant in groundwater was changed to 5 ppm of tetrachloroethylene. FIG. 5 shows the results. In addition, when a similar test was performed using no electrolyte, no electrolysis, and no light irradiation as a control test, no decomposition of tetrachloroethylene was observed.
This test shows that groundwater can be decomposed by electrolyzing groundwater and further irradiating light with tetrachloroethylene.

Example 2-B Groundwater in a well was sampled, and the concentration of sodium chloride in the well was monitored by measuring the concentration of sodium chloride in the sample with a salt concentration meter. The same test as in Example 2-A was performed except that the supply rate of the sodium chloride solution was changed so that the concentration of sodium chloride became 0.005%. The result is shown in FIG.

From this test, it can be seen that the efficiency of decomposition of tetrachlorethylene in groundwater is improved by measuring the concentration of the electrolyte in the groundwater and controlling the rate of supplying the electrolyte according to the concentration.

[Example 2-C] When the monitored tetrachloroethylene concentration in the groundwater in the wells increased by 10% or more from the previous measurement, the supply rate of sodium chloride was doubled. The same test as in Example 2-A was performed. The result is shown in FIG.

From this test, it can be understood that the efficiency of decomposition of tetrachlorethylene in groundwater is improved by measuring the concentration of tetrachlorethylene in groundwater and controlling the rate of supplying the electrolyte according to the measured concentration.

[Example 2-D] When the monitored tetrachloroethylene concentration in the groundwater in the well increased by 10% or more from the previous measurement, the voltage supplied to the electrode for performing electrolysis was increased and the current was increased. The same test as in Example 2-A was performed except that the current was increased by 3A. The result is shown in FIG.

From this test, it can be seen that by measuring the concentration of tetrachlorethylene in groundwater and controlling the voltage supplied to the electrodes according to the concentration, the decomposition efficiency of tetrachlorethylene in groundwater is improved.

[Example 2-E] When the concentration of tetrachloroethylene in the groundwater in the monitored well increased by 10% or more from the time of the previous measurement, the voltage supplied to the fluorescent lamp was increased and the irradiation light amount on the groundwater surface was increased. 0.15 than before
The same test as in Example 2-A was performed except that mW / cm ^{2 was} increased. The result is shown in FIG.

This test shows that the tetrachloroethylene concentration in groundwater is measured, and the decomposition efficiency of tetrachlorethylene in groundwater is improved by controlling the light irradiation intensity according to the concentration.

[Example 3] (Purification test of PCB) [Example 3-A] The same test as in Example 1-A was conducted except that the contaminant in groundwater was changed to 5 ppm of PCB. Fig. 6 shows the results.
Shown in

When a similar test was carried out using no electrolyte, no electrolysis, and no light irradiation as a control test, no decomposition of PCB was observed. This test shows that PCB in groundwater can be decomposed by electrolyzing groundwater and irradiating light.

Example 3-B The groundwater in the well was sampled, and the concentration of sodium chloride in the sample was measured by a salt concentration meter to monitor the concentration of sodium chloride in the groundwater in the well. The same test as in Example 3-A was performed except that the supply rate of the sodium chloride solution was changed so that the sodium chloride concentration of the solution was 0.005%. FIG. 6 shows the result.

This test shows that the decomposition efficiency of PCB in groundwater is improved by measuring the concentration of the electrolyte in the groundwater and controlling the rate of supplying the electrolyte according to the concentration.

[Example 3-C] When the PCB concentration in the groundwater in the monitored wells increased by 10% or more from the previous measurement, the supply rate of sodium chloride was doubled. The same test as in Example 3-A was performed.

FIG. 6 shows the result. With this test,
By measuring the PCB concentration in the groundwater and controlling the rate of supplying the electrolyte according to the concentration, the PCB concentration in the groundwater can be controlled.
It can be seen that the decomposition efficiency of is improved.

[Example 3-D] When the PCB concentration in the groundwater in the monitored well increased by 10% or more from the previous measurement, the voltage supplied to the electrode for performing electrolysis was increased, and the current was increased. Example 3-
The same test as in A was performed.

FIG. 6 shows the results. With this test,
It can be seen that by measuring the PCB concentration in groundwater and controlling the voltage supplied to the electrodes according to the concentration, the decomposition efficiency of PCB in groundwater is improved.

[Example 3-E] When the PCB concentration in the groundwater in the monitored well increased by 10% or more from the previous measurement, the voltage supplied to the fluorescent lamp was increased and the irradiation light amount on the groundwater surface was increased. other raised 0.15mW / cm ² than up to it,
The same test as in Example 3-A was performed.

FIG. 6 shows the result. With this test,
By measuring the PCB concentration in the groundwater and controlling the light irradiation intensity according to the concentration, it can be seen that the decomposition efficiency of the PCB in the groundwater is improved.

[0078]

According to the present invention, organic compounds, especially halogenated aliphatic hydrocarbon compounds such as tetrachloroethylene and trichloroethylene, and groundwater contaminated with PCBs and the like can be abiotically treated in-situ at normal temperature and normal pressure. In addition, a groundwater purifying apparatus capable of purifying water effectively and a purifying method using the apparatus are provided, and a remarkable effect is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic explanatory view showing an outline of an embodiment of an in-situ purification apparatus for contaminated groundwater according to the present invention.

FIG. 2 is a schematic explanatory view showing an outline of the entire test apparatus according to the present invention.

FIG. 3 is a schematic enlarged explanatory view showing an outline of a model well in the present invention.

FIG. 4 is a graph showing test results in Examples 1-A to 1-E of the present invention (trichloroethylene purification test).

FIG. 5 is a graph showing test results in Examples 2-A to 2-E (purification test of tetrachloroethylene) of the present invention.

FIG. 6 is a graph showing test results in Examples 3-A to 3-E (PCB purification test) of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Groundwater 2 Well 3 Anode 4 Cathode 5 Power supply 6 Dripping pipe 7 Dripping pump 8 Groundwater storage part 9 Light source 10 Stirrer 11 Sampling tube 12 Pump 51 Stainless steel tank 52 Partition plate 53 Drain 54 Discharge chamber 55 Supply chamber 56 Model well 60 Electrode 61 Stirrer blade 62 Stirrer 63 Fluorescent lamp 64 Dripping tube 65 Tube pump 68 Gravel 69 Power supply 81 Teflon tube for sampling 82 Pump

Continued on the front page F term (reference) 4D004 AA41 AB05 AB06 AC07 CA15 CA43 CA44 DA02 DA03 DA20 4D037 AB14 AB16 BA16 BB01 BB02 BB09 CA04 4D061 DA02 DB07 DC09 EA03 EA04 EB19 EB30 EB31 EB37 EB39 ED12 GC06

Claims (32)

[Claims] An apparatus for purifying groundwater contaminated with organic compound pollutants, comprising: a well reaching a groundwater layer;
A pair of electrodes installed in the groundwater in the well and a means for supplying power to the electrodes, a means for continuously supplying electrolyte to the groundwater in the well, and a means for irradiating light to the groundwater in the well , A groundwater purification device comprising: 2. A method for measuring the concentration of a contaminant in groundwater in the well, and controlling at least one of a voltage supplied to an electrode, a rate of supplying an electrolyte, and a light irradiation intensity according to the concentration. The purification device according to claim 1, wherein: 3. The purification apparatus according to claim 1, wherein the concentration of the electrolyte in the groundwater in the well is measured, and the speed of supplying the electrolyte is controlled according to the concentration. 4. The electrolyte according to claim 1, wherein the electrolyte is at least one of sodium chloride and potassium chloride.
The purification device according to claim 1. 5. The light according to claim 1, wherein the light includes light in a wavelength range of 300 nm or more.
Purification device according to any one of the above. 6. The purification apparatus according to claim 1, wherein the irradiation amount of the light is 10 mW / cm ² or more. 7. The purification device according to claim 1, wherein the light source of the light is a black light. 8. The purification apparatus according to claim 1, wherein the decomposition of the pollutant is caused by functional water generated by electrolysis of water containing an electrolyte. 9. The purification apparatus according to claim 8, wherein the functional water is a mixed water of a specific ratio of acidic water generated near the anode and alkaline water generated near the cathode. 10. The functional water having a hydrogen ion concentration (pH
Value) in the range of 4 to 10, oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) of 300 to 1
100mV range and chlorine concentration 2-100mg / l
10. A characteristic having a characteristic in the range of
Purification device according to the above. 11. The purification device according to claim 1, wherein at least a portion of the wall surface of the well that contacts the groundwater layer has water permeability. 12. The well according to claim 1, further comprising means for stirring groundwater in the well.
Purification device according to any one of the above. 13. The purifying apparatus according to claim 1, wherein the contaminant is a halogenated aliphatic hydrocarbon compound. 14. The method according to claim 13, wherein the halogenated aliphatic hydrocarbon compound is at least one of tetrachloroethylene and trichloroethylene.
Purification device according to the above. 15. The purification device according to claim 1, wherein the contaminant is a biphenyl compound. 16. The purification device according to claim 15, wherein the biphenyl compound is PCB. 17. A method for purifying groundwater contaminated with a pollutant of an organic compound, a step of constructing a well reaching a groundwater layer, a step of continuously supplying an electrolyte to the groundwater in the well, A method for purifying groundwater, comprising the steps of: electrolyzing groundwater containing water to generate functional water; and irradiating light to the groundwater containing the functional water. 18. A method of measuring the concentration of a contaminant in groundwater in the well, and controlling a voltage supplied to an electrode, a rate of supplying an electrolyte, and a light irradiation intensity according to the concentration. The purification method according to claim 17. 19. The purification method according to claim 17, wherein the concentration of the electrolyte in the groundwater in the well is measured, and the rate of supplying the electrolyte is controlled according to the concentration. 20. The purification method according to claim 17, wherein the electrolyte is at least one of sodium chloride and potassium chloride. 21. The purification method according to claim 17, wherein the light is light including light in a wavelength range of 300 nm or more. 22. The decomposition method according to claim 17, wherein the irradiation amount of the light is 10 mW / cm ² or more. 23. The cleaning method according to claim 17, wherein the light source of the light is a black light. 24. The purification method according to claim 17, wherein the decomposition of the pollutant is performed by functional water generated by electrolysis of water containing an electrolyte. 25. The purification method according to claim 24, wherein the functional water is a mixed water of a specific ratio of acidic water generated near the anode and alkaline water generated near the cathode. 26. The functional water has a hydrogen ion concentration (pH value).
Is in the range of 4 to 10, and the oxidation-reduction potential (working electrode: platinum electrode, reference electrode: silver-silver chloride electrode) is 300 to 11
26. The composition according to claim 25, characterized in that it has a property in the range of 00 mV and a chlorine concentration in the range of 2 to 100 mg / l.
Purification method as described. 27. The purification method according to claim 17, wherein at least a portion of the wall surface of the well that contacts the groundwater layer has water permeability. 28. The purification method according to claim 17, wherein a means for stirring groundwater is used in the well. 29. The purification method according to claim 17, wherein the contaminant is a halogenated aliphatic hydrocarbon compound. 30. The method according to claim 29, wherein the halogenated aliphatic hydrocarbon compound is at least one of tetrachloroethylene and trichloroethylene.
Purification method as described. 31. The purification method according to claim 17, wherein the contaminant is a biphenyl compound. 32. The purification method according to claim 31, wherein the biphenyl compound is PCB.