JP3458688B2 - Method and apparatus for repairing groundwater contamination - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for repairing groundwater contaminated by permeation of organic compounds by decomposing and removing pollutants by aerobic microbial activity of aerobic microorganisms or facultative anaerobic microorganisms, and therefore Repair device.

[0002]

2. Description of the Related Art As a method for repairing groundwater pollution by organic compounds, a physical repair method such as a combination method of pumping aeration and adsorption of activated carbon, a simple pumping method, or an air sparging method is generally used. There is. Recently, in addition to these physical repair methods, biological repair methods utilizing the decomposition of pollutants by microorganisms, that is, purification treatment by bioremediation have been investigated.

In particular, without pumping polluted groundwater to the ground,
Bioremediation as an in-situ treatment for underground treatment aims to permanently decompose and remove pollutants in groundwater in-situ. Unlike the combined method of pumped water aeration and activated carbon adsorption, this method does not decrease the repair speed after the repair progresses to a low concentration range, and is a simpler system than the air sparging method and has a wider range. It is excellent in that it can cover the area to be restored.

[0004]

In the above-mentioned in-situ treatment bioremediation, it is necessary to grow microorganisms capable of decomposing pollutants in the underground area, which is a contaminated site. Need to be replenished.

However, when injecting water containing nutrients required by microorganisms into the ground, the nutrients injected into the groundwater and the injecting substances such as oxygen generally diffuse naturally in all four directions, and If there is a flow, it will spread along the flow and spread. Therefore, the concentration of the injected substance is highest at the injection point, but generally becomes lower as the distance from the injection point increases, and if the diffusivity is good, it decreases in proportion to the square of the distance or more.

Further, in addition to the concentration decrease of the injected substance due to such diffusion, the injected substance is ingested by microorganisms widely distributed in the ground. Therefore, the rate of decrease in the concentration of the injected substance depending on the distance from the injection point is further increased due to the addition of this intake amount. As a result, pollutants are decomposed due to active growth of microorganisms near the injection point where the concentration of injected nutrients is high, but there is a drawback that the decomposition of pollutant decomposition by microorganisms rapidly decreases as the distance from the injection point increases. .

[0007] Such a decrease in the concentration of the injected substance in the ground is reduced to make it easier for the injected substance to reach far from the injection point, and the injected substance is kept at a certain concentration or more in a predetermined restoration target range. As a method for doing so, the following method can be considered.

The first method is to increase the concentration of nutrients in the injected water or increase the amount of injected water itself.
However, even if the amount of the injected substance is increased by these methods, it is easily inferred that the concentration distribution of the injected substance gradually decreases with distance from the injection point as the apex due to the above reasons. Therefore, in order to reach a certain concentration of the injected substance to a distant place, when setting the amount of the injected substance, set an amount that is considerably excessive over the equivalent amount calculated on the assumption that the substance is uniformly dispersed in the restoration target range. Need to be injected. Since this excess amount increases as the scale of pollution restoration increases, the increase in running cost due to this becomes more apparent as the scale of restoration increases.

More importantly, the growth of microorganisms tends to occur earlier in the region near the injection point, but the growth of the microorganisms near the injection point causes a great adverse effect. Generally, in the underground environment, the flow velocity of groundwater is a few meters or less per day even in a fast place,
It can be said that the spatial movement velocity of groundwater flow when considering the underground environment as a microbial reaction tank is sufficiently smaller than that of any type of microbial reaction tank on the ground. In other words, considering as a comparison of water treatment capacity, the underground environment near the injection point is
The reduction efficiency is ideal when the concentration of nutrients input from the injection point is reduced.

Therefore, when the microbial concentration rises near the injection point in advance, for example, in the aquifer within a radius of 2 m, the number of aerobic heterotrophic bacteria is 10 9 / ml.
When the above microbial concentration is reached, no matter how much nutrient material is injected, as long as it is at an extremely low mass transfer rate in groundwater, it will be sufficiently far from the injection point to the surrounding area. Before the diffusion, the nutrients are supplementally absorbed by the grown microorganisms with sufficient time margin in a region relatively close to the injection point, for example, within 2 m. As a result, it may even happen that most of the injected material is already exhausted within a few meters of the injection point.

The second solution is to disperse the injection points. If it is possible to disperse and inject from a large number of injection points, it should be easy to achieve a uniform injection material concentration in almost the entire region to be repaired. However, it is not always the solution that can be adopted because it depends greatly on the location conditions of the restoration site whether the number of injection points can be increased. In particular, when performing in-situ repair by using microorganisms in places where buildings are densely built, such as in urban areas of Japan, secure a place for the injection well that is the entrance of the injection substance. At that time, construction is often difficult due to the large positional restrictions of existing buildings.

The present invention has been made in view of such conventional circumstances.
It promotes diffusion of injected substances such as oxygen and nutrients that are injected into the ground to a long distance from the injection point, and maintains the concentration of injected substances necessary for microbial growth activity in almost all areas to be repaired and pollutants. It is an object of the present invention to provide a method for repairing groundwater pollution that can cause efficient decomposition of water, and an apparatus therefor.

[0013]

In order to achieve the above object, the present invention provides a method of injecting water containing a nutrient composition for microorganisms into a contaminated groundwater zone from an injection well to decompose pollutants by microorganisms. In the restoration method, ozone is dissolved in the injected water to inject it, or the injected water and dissolved ozone water is injected.

In this groundwater pollution remediation method, the injection water and the dissolved ozone water can be injected from another injection well, or can be injected alternately from the injection well at time intervals. The initial dissolved ozone concentration when water is injected from the injection well is preferably 0.2 to 10 mg / l.

The apparatus of the present invention for carrying out the method for repairing groundwater pollution comprises a dissolved ozone generator for dissolving ozone in the injected water or water other than the injected water, and at least the injected water in which ozone is dissolved or The water supply equipment for supplying the dissolved ozone water to the injection well has an airtight structure.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The pollutants to be restored by the present invention are not particularly limited, and examples thereof include gasoline, light oil, kerosene, heavy oil, crude oil, machine oil, lubricating oil, and organic chlorine-based cleaning agents. There are petrochemical products, and their components are non-chlorine organic compounds such as benzene, toluene, ethylbenzene, xylene, ketones, or trichloroethylene, tetrachloroethylene, dichloroethylene, dioxins, PCBs, PCP (pentachlorophenol).
Chlorine-based organic compounds such as

The nutritional composition for microorganisms may be a nutritional composition conventionally used in a microbiological remediation method for groundwater contamination, and it may be a salt containing an inorganic compound serving as a nitrogen source or a phosphorus source, pH. Contains regulators. In the case of decomposing the pollutant to be restored by co-metabolic action by microorganisms, in addition to the above-mentioned nitrogen source, phosphorus source, etc., hydrocarbons mainly metabolized by the microorganisms are also included.

In the present invention, in addition to injecting water containing the nutrient composition for microorganisms, dissolved ozone is contained in this injecting water or is injected as polluted groundwater as dissolved ozone water. for that reason,
A dissolved ozone generator will be installed above the ground, and water will be injected from the injection well using an airtight water supply system so that dissolved ozone does not escape to the outside air. The dissolved ozone generator may be equipped with an ozone generator and a dissolved ozonization tank. There are three ozone generation methods of the dissolved ozone generator or the ozone generator, that is, an ultraviolet method, a discharge method, and a water electrolysis method, but any method can be adopted. A relatively low-cost ultraviolet type may be used, or a large-scale discharge type ozonizer may be used.

When injecting the injecting water containing the nutritional composition and the dissolved ozone water, both may be infused at the same time, or a method of injecting them into the ground alternately with a time interval as required. It can also be taken. In addition, when two or more injection points can be set, it is possible to inject the dissolved ozone water and the injection water into the ground through separate injection wells. In addition, when the injection of the dissolved ozone water and the injection water are performed separately, the conditions regarding the injection interval, etc. are the optimum mixing state of the individual injection substances in the subterranean aquifer in the pollution remediation target area. In order to realize the above, it is preferable to determine in advance by using analysis of underground data, simulation, or the like.

When all the nutrients necessary for the microorganisms that decompose the pollutant to be restored are of a type that does not cause a chemical reaction by dissolved ozone, the dissolved ozone and those nutrients are injected separately. It is not necessary that the injected water containing the nutritional composition and the dissolved ozone water can be simultaneously injected from the same injection well, or the injected water can further contain dissolved ozone.

Oxygen is required in addition to the above nutritional composition for the growth of microorganisms in groundwater. Of the injected water that is sent to the groundwater, it is desirable to artificially increase the dissolved oxygen concentration in advance for the injected water that is injected separately from the dissolved ozone water in order to secure the oxygen amount necessary for the growth of microorganisms. . However, in the water tank for the injected water, the oxygen partial pressure from the atmosphere may be only naturally saturated.

When the dissolved ozone water or the injected water containing the dissolved ozone is produced by a method in which gaseous ozone generated by various ozonizers is dissolved by a dissolved ozonization tank, depending on the capacity of the ozonizer, aeration is performed. In some cases, the dissolved oxygen concentration at that time may be lower than that before aeration. Even in that case, the dissolved ozone, which is replaced with the dissolved oxygen, is gradually decomposed into oxygen in the process of being diffused after being injected into the groundwater, so that the actual amount of oxygen supplied does not decrease.

As a specific example of the restoration device of the present invention, FIG.
The case where the injection water containing the nutrient composition and the dissolved ozone water are injected into the injection well is shown in FIG. The injection well 1 reaching the unsaturated aquifer A or the saturated aquifer B under the ground is provided.
A water injection pipe 2 for injecting injected water and dissolved ozone water is inserted into the. A dissolved ozone generator 4 and a water storage tank 5 are installed on the ground, together with an injection water storage tank 3 for adjusting and storing injection water in which a nutrient composition is dissolved, and ozone is added to water supplied from the water storage tank 5. Dissolved ozone water is produced by dissolving it. The injected water and the dissolved ozone water pass through the water supply pipes 7a and 7b by the water supply pumps 6a and 6b, respectively, and the water injection pipe 2
And is injected into the groundwater from the injection well 1.
In this apparatus, the water supply equipment such as the water supply pipe 7b through which the dissolved ozone water passes has an airtight structure.

In the present invention, by injecting the dissolved ozone together with the nutrient composition and the usual injecting substances such as oxygen, the decrease in the dissolved oxygen concentration is suppressed even in the region away from the injection point. That is, the dissolved oxygen concentration generally decreases as it moves away from the injection point due to diffusion in the ground, but since ozone gradually decomposes with diffusion, oxygen is generated so as to be offset by the oxygen that decreases due to diffusion. . Therefore, compared to the dissolved oxygen distribution obtained by the conventional method, it is possible to create a distribution state in which the decrease in the dissolved oxygen concentration is suppressed in the peripheral portion away from the injection point.

At the same time, in the range where ozone concentration exists underground, microorganisms are affected by the strong oxidizing action of ozone and their growth activity is suppressed, and naturally, intake of nutrients such as nitrogen and phosphorus is also suppressed. . This tendency is greater as the diffusion point of dissolved ozone is closer to the injection point, so that the consumption of oxygen and nutrients is suppressed closer to the injection point. This may sound paradoxical in the practice of bioremediation, but in the present invention, by utilizing this property, oxygen derived from the infused water and long-range reachability of the nutritional composition contained in the infused water are obtained. It can enhance the decomposition of pollutants by microorganisms in a wide range.

The dissolved ozone concentration at the time of injection into the injection well can be arbitrarily changed according to the restoration environment and restoration scale, but the initial dissolved ozone concentration is 0.2 to 10 mg.
It is desirable to be in the range of / l. When the dissolved ozone concentration at the time of injection is less than 0.2 mg / l, the above-mentioned ozone injection effect is hardly obtained, and conversely, at a high concentration of more than 10 mg / l, depending on the amount of water injected, the injection point is centered in the ground. This is because the range of completely stopping the microbial activity of the above is excessively expanded, which may rather reduce the repair efficiency. In addition, the higher the setting of the initial dissolved ozone concentration, the higher the equipment cost of necessary ozone-related equipment, which is uneconomical.

In groundwater kept at a water temperature of about 15 ° C. throughout the year, the half-life of ozone conversion to oxygen is more stable than in the surface environment where temperature changes greatly, but the pH of injected water or dissolved ozone water is low. By adjusting as low as possible even in the neutral range, the half-life of dissolved ozone is further extended,
It is possible to further improve long-distance reachability of oxygen and nutritional compositions. On the contrary, when it is desired to promote the ozone decomposition in the vicinity of the injection well, the pH of the injected water or the dissolved ozone water should be adjusted to the alkaline side as much as possible. In any of these cases, the pH needs to be adjusted within a range compatible with the physiological conditions of the microorganism.

The dissolved ozone injected into the groundwater will be completely converted into oxygen in the ground, so that it will not affect the subsequent microbial activity in the watershed or the underground environment outside the pollution remediation target area. . In addition, the decomposition reaction of ozone into oxygen does not induce a large pH change like the reaction with other types of oxidizing agents.

Further, in the present invention, ozone dissolved in water is allowed to act on the environment, so that ozone as a gas is not released on the ground. Therefore, the ozone concentration in the surface air near the polluted site is set to 0.1 ppm, which is set in the Japan Work Safety Standard, or the WHO standard, which is 0.0 ppm.
It is easy to keep below 5 ppm. In addition, compared to ozone as a gas, dissolved ozone dissolved in water decomposes faster than atmospheric air due to the presence of surrounding water, so dissolved ozone in groundwater again rises to the surface as ozone gas. There is no adverse effect.

In some repair cases, it can be expected that the pollutant itself will be directly subjected to a chemical action by ozone and will be transformed into a readily decomposable substance. For example, when unsaturated hydrocarbons having an ethylene bond are pollutants, ozone is added to the double bond part and then this part is broken by the action with water to produce a ketone or aldehyde. . However, for example, in some types of polycyclic aromatic compounds, a more toxic water-soluble intermediate substance may be secondarily generated by the chemical action of ozone. In such a case, the application of the method of the present invention should be carried out carefully, but this is not the case when the intermediate product rapidly changes to the next step by chemical reaction.

In the repair of groundwater pollution of the present invention, the underground region near the injection well may remain unrepaired. In such a case, after the restoration of the peripheral portion is completed, the injection of the dissolved ozone water is stopped or the concentration of the injected dissolved ozone is reduced to restart the microbial activity in the vicinity of the injection well. Since a permanent toxic substance is not originally injected into the ground, it is possible to easily restore the microbial growth environment in the vicinity of the injection point by only these operations.

After the completion of the repairing treatment, the nutrients of microorganisms grown underground are also cut off, and the number of microorganisms is reduced to the original state in about 1 to 3 months. However, if for some reason you want to quickly kill the proliferated microorganisms immediately after the completion of the repair work, it is possible to deal with it to some extent by putting the dissolved ozone concentration at the end of the repair into the injection well. Is.

[0033]

Example 1 In a lysimeter experimental facility for forming an aquifer at a full depth, simulating a site in which an aquifer part 4 m underground is contaminated with a saturated hydrocarbon compound, Such an experiment was conducted. That is, an injection water prepared by adding inorganic salts containing nitrogen and phosphorus at a predetermined concentration as a nutritional composition for microorganisms is prepared, and ozone is further dissolved in the injection liquid, and then an injection well installed in the center of the pollution source is used. We tried to remediate the groundwater contamination by microbiologically injecting water continuously.

The composition of the injected water was such that the dissolved ozone concentration was 2.0 mg / l in the initial concentration and the potassium nitrate concentration was 25 mg / l.
1 and the concentration of dipotassium hydrogen phosphate was 40 mg / l.
The injected water containing this dissolved ozone was continuously injected into the aquifer 4 m underground from the injection well at a water injection rate of 20 liters per hour, and the degree of diffusion of each injected component was regularly set around the injection well. The water was collected from the observation well.
The average dissolved oxygen concentration in groundwater before injection is 1.8m.
It was g / l. The numbers of aerobic heterotrophic bacteria in the injection well and the observation well were measured by the plate dilution medium method using standard agar medium, which was separately performed by collecting sample water from each.

Before the start of the experiment, the total number of aerobic heterotrophic bacteria in each observation well 4 m underground was 1 ml in each of the three observation wells at the horizontal distances of 1 m, 3 m and 6 m from the injection well. There was a match of 10 6 per unit.

As a result of the experiment, the total number of aerobic heterotrophic bacteria in each observation well at 4 weeks after the start of injection was three observations at the horizontal distances of 1 m, 3 m, and 6 m from the injection well, respectively. 10 in each well, 6 per ml
The number of units was 10 8 units, 10 7 units. Similarly, the dissolved oxygen concentration was 4.0 mg each.
/ L, 4.5 mg / l, 4.0 mg / l were almost even. As a result, it was found that the decomposition of pollutants by microorganisms proceeded almost uniformly within a radius of 6 m from the injection well, which is the underground area to be repaired.

Example 2 The pollutant was an organochlorine compound, and therefore methane was added to the nutrient composition to be injected, and dissolved ozone was separated from the injected water containing the nutrient composition so that ozone would not directly oxidize methane. The water was adjusted, and the injected water and the dissolved ozone water were alternately poured every 8 hours at different times. A repair experiment was conducted again in the same manner as in Example 1 except that these conditions were changed. The dissolved oxygen concentration in the injected water was 8.5 mg / l on average due to saturation with atmospheric oxygen.

The measurement of the microorganism concentration in the injection well and the observation well was carried out according to Example 1 for the total number of aerobic heterotrophic bacteria.
The plate-diluted culture medium method was used in the same manner as described above. For methanotrophic bacteria, the methanotrophic growth in each serially diluted sample was determined and then measured by the 5-5-5 MPN method.

The total number of aerobic heterotrophic bacteria in the groundwater of 4 m underground in each observation well before the start of the experiment was 1 m, 3 m, and 6 m horizontally from the injection well. The agreement was on the order of 10 6 per 1 ml. Regarding the methanotrophic bacteria, similarly, at each of the horizontal distances of 1 m, 3 m, and 6 m, the detection limit was not more than 10 1 per 1 ml, respectively.

As a result of the experiment, the maximum number of total aerobic heterotrophic bacteria in each observation well at 4 weeks after the start of injection was 1 m, 3 m, and 6 m in horizontal distance from the injection well, respectively. Then, 10 6 units per 1 ml, 10
It was the 8th power unit and the 10th power unit. In addition, the number of methane-utilizing bacteria in each observation well at 2 weeks after the start of the injection was the same as that of 1m, 3m, and 6m at 10 3 powers per 1 ml, and 10 4 powers. It was an individual unit, 10 4th unit.

Similarly, the dissolved oxygen concentration is 4 m below the observation wells with horizontal distances of 1 m, 3 m, and 6 m from the injection well.
With water, 4.5 mg / l, 5.0 mg / l, 4.5, respectively
It was mg / l, which was almost uniform. From these results, it was found that the decomposition of the pollutants by the microorganisms proceeded almost uniformly within the radius of 6 m, which is the underground area to be repaired.

Comparative Example 1 Under the conditions of Example 1 described above, only the oxygen was dissolved in the injected water containing the nutritional composition without dissolving ozone, and other conditions were restored in the same manner as in Example 1. An experiment was conducted.
The dissolved oxygen concentration in the ground water before injection was 1.8 mg / l on average in the same 4 m underground as in Example 1, and the dissolved oxygen concentration in the injected water before injection was 8.5 mg / l on average. .

Before the start of the experiment, the total number of aerobic heterotrophic bacteria at 4 m underground in each observation well was 1 m, 3 m, and 6 m horizontally from the injection well. The agreement was in the 10 6 power range per 1 ml, which was also the same condition as in Example 1.

As a result of the experiment, the total number of aerobic heterotrophic bacteria in the 4m underground part of each observation well at 4 weeks after the start of the injection was as follows: 10 8 powers per 10 ml, 10 6
The number of units is 10 6 units and the horizontal distance is 3m.
The biodegradation activity was not increased at each of the above-mentioned points.

Similarly, the dissolved oxygen concentration was 4.0 mg / l, 1.9 mg / l and 1.8 mg / l at each point.
The dissolved oxygen concentration in the background remained at each point with a horizontal distance of 3 m or more. From this result, it was found that the decomposition of pollutants by microorganisms proceeded only within a radius of about 1 m from the injection well.

Comparative Example 2 Under the conditions of Comparative Example 1, the oxygen concentration was raised to an initial concentration of 20 mg / l by using pure oxygen gas when adjusting the injection water on the ground, and other conditions were completely the same as in Example 1. A repair experiment was conducted in the same manner.

The dissolved oxygen concentration of groundwater before the injection was 1.8 mg / l on average in the 4 m portion underground as in Example 1 and Comparative Example 1. In addition, the total aerobic heterotrophic bacteria number 4m underground in each observation well before the start of the experiment was 10 6 per 1 ml for each observation well at horizontal distances of 1 m, 3 m, and 6 m from the injection well. It was a unit and was the same as Example 1 and Comparative Example 1.

As a result of the experiment, the total number of aerobic heterotrophic bacteria in the 4 m underground part of each observation well at 4 weeks after the start of injection was 1 m and 3 m at the horizontal distance from the injection well, respectively.
In each observation well 6 m apart, there were 10 8 powers, 10 7 powers, 10 6 powers per ml, and the microbial degrading activity did not increase at the horizontal distance of 6 m. .

Similarly, the dissolved oxygen concentration was 8.0 mg / l, 2.8 mg / l and 1.8 mg / l at each point.
That is, at a point with a horizontal distance of 6 m, it was in agreement with the dissolved oxygen concentration in the background and did not increase further. From these results, it was found that the decomposition of pollutants by microorganisms was promoted only within the range of a radius of about 3 m from the injection well.

To make matters worse, the total number of aerobic heterotrophic bacteria in the injection well was 10 per ml during the experiment.
Since the number of soils in the aquifer increased to more than the 9th power, the soil blockage phenomenon, which is considered to be the cause, progressed in the soil in the aquifer near the injection well. As a result, the non-uniform flow of the injected water occurred, such as once the injected water rose to the uppermost basin of the aquifer and then flowed, which adversely affected the underground dispersion of the injected water thereafter.

[0051]

EFFECTS OF THE INVENTION According to the present invention, since dissolved ozone injected into the ground is gradually decomposed with diffusion, generation of dissolved oxygen can be obtained at a point apart from the injection well, and microorganisms possessed by ozone can be obtained. Due to the growth inhibitory effect, an increase in the microbial concentration is suppressed closer to the injection point, and an extreme increase in oxygen consumption at the injection point is prevented. Similarly, due to the effect of ozone to suppress the growth of microorganisms, it is possible to suppress the relatively early ingestion of nutrient compositions such as nutrient salts, which is an injecting substance other than oxygen, by the microorganisms in the vicinity of the injecting point.

Therefore, according to the present invention, it is possible to prevent the dissolved oxygen concentration and the nutrient composition concentration from rapidly decreasing with distance from the injection well, and to greatly improve the reachability of these underground underground. be able to. as a result,
In a wider underground area, it becomes possible to apply bioremediation, which decomposes and removes pollutants by utilizing microorganisms. Moreover, even if only a small number of injection wells can be installed due to the location restrictions such as ground obstacles, a wide repair range can be easily secured.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a specific example of a groundwater pollution restoration device of the present invention.

[Explanation of symbols]

1 injection well 2 Water injection pipe 3 Infused water storage tank 4 Dissolved ozone maker 5 water tank 6a, 6b Water pump 7a, 7b Water pipe

Front page continued (58) Fields surveyed (Int.Cl. ⁷ , DB name) C02F 3/12 C02F 3/00 C02F 7/00 B09C 1/10 WPI (DIALOG)

Claims (4)

(57) [Claims] 1. A method of repairing groundwater pollution, in which injected water containing a nutritional composition for microorganisms is injected from an injection well into a contaminated groundwater zone to decompose pollutants by microorganisms, and ozone is dissolved in the injected water for injection. Alternatively, a method for repairing groundwater contamination, which comprises injecting the injected water and dissolved ozone water. 2. The groundwater according to claim 1, wherein the injection water and the dissolved ozone water are injected from different injection wells or alternately from the injection wells at time intervals. How to remediate pollution. 3. The method for repairing groundwater contamination according to claim 1, wherein the initial dissolved ozone concentration when water is injected from the injection well is 0.2 to 10 mg / l. 4. An apparatus for decomposing pollutants by microorganisms by injecting injecting water containing a nutrient composition for microorganisms into an injured contaminated groundwater zone from an injecting well, wherein ozone is added to the infused water or water other than the infused water. An apparatus for repairing groundwater pollution, comprising a dissolved ozone generator for dissolving water, and at least an injectable water in which ozone is dissolved or a water supply facility for supplying dissolved ozone water to an injection well has an airtight structure.