JP2009136767A - Groundwater remediation method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a groundwater remediation method which enables the decomposition of contaminants using microorganisms, and diffusion injected substances, such as oxygen, nutritive substances, and the like, promotion of the growth of the microorganisms to far from an injection point in an injection well. <P>SOLUTION: Ozone-dissolved water and nutrient water containing a nutrient composition for microorganisms are fed into one injection well 2 through respective injection pipes 14, 24 to be injected into contaminated ground water in an aquifer from discharge ports 14a, 24a separated from each other in the depth direction. Preferably, the distance between both discharge ports 14a, 24a is 1-3 m in the depth direction. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for repairing groundwater contaminated by infiltration of organic compounds by decomposing and removing contaminants by aerobic microbial activity of aerobic microorganisms or facultative anaerobic microorganisms.

  As a method for repairing groundwater contamination by organic compounds, a physical repairing method such as a combination of pumping aeration and activated carbon adsorption, a simple pumping treatment method, or an air sparging method is generally used. However, in the combined method of pumped water aeration and activated carbon adsorption, the repair proceeds efficiently until the contamination reaches a low concentration range, but thereafter, the repair speed decreases. In addition, the air sparging method has a problem that the system is complicated and the repairable area is narrow.

  Recently, biological repair methods utilizing biodegradation of contaminants by microorganisms, ie, bioremediation methods, have been studied. In particular, in bioremediation in which contaminated groundwater is treated in an underground aquifer without pumping to the ground, the goal is to almost completely decompose and remove contaminants in the groundwater in situ. To that end, it is necessary to grow microorganisms capable of degrading pollutants in the underground area (hereinafter referred to as the area to be repaired), which is a contaminated location, and therefore contain nutrient compositions, oxygen, etc. that the microorganisms require. Injected water is replenished to the underground aquifer from the ground through an injection well.

  However, when injected water is injected into the ground in this way, the injected substances such as nutrients and oxygen contained in the injected water generally diffuse three-dimensionally using groundwater as a medium, and there is a groundwater flow. In some cases, it spreads around the flow and spreads. Therefore, the concentration of the injected substance is highest at the injection point, but decreases as the distance from the injection point increases, and the concentration decreases in proportion to the cube of the distance.

  Furthermore, in addition to the decrease in the concentration of the injected substance due to such diffusion, the injected substance is ingested by existing microorganisms widely distributed in the ground, so the concentration of the injected substance at a certain distance from the injection point is reduced. The rate is even greater with the addition of this microbial uptake, as well as the diffusion described above. As a result, the pollutant is decomposed by the active growth of microorganisms near the injection point where the injection substance concentration is high, but there is a drawback that the ability of the microorganisms to decompose pollutants decreases rapidly as the distance from the injection point increases.

  To solve the problem of degradation of the pollutant decomposing capability at a point away from the injection position, the injection material reaches far from the injection point, and the injection material is kept at a predetermined concentration or more in a predetermined repair target region. It is thought that it can be coped with by making it spread. As a method for that purpose, the following methods can be considered.

  That is, there is a countermeasure for increasing the amount of injected material by increasing the concentration of the injected material in the injected water or increasing the amount of injected water per unit time. However, this method is not a drastic solution to the above degradation of decomposition ability, and it is still presumed that the concentration distribution of the injected substance still decreases rapidly as the distance from the injection point increases. The Furthermore, in this method, the growth of microorganisms becomes more prominent near the injection point. Therefore, in the vicinity of the injection point, clogging of the soil by the grown microorganisms, so-called biofouling occurs, and the diffusion of the injected water is inhibited. Prone to harmful effects.

  Even if it does not lead to biofouling, microorganisms proliferate in the vicinity of the injection point, for example, the number of aerobic heterotrophic bacteria in the underground aquifer within a radius of 2 m is 10 9 or more per milliliter However, no matter how many nutritional compositions or nutrient waters are injected, most of them are consumed by the grown microorganisms within a few meters from the injection point. It will be exhausted. This is due to the fact that the mass transfer rate is generally very low in groundwater. That is, since it takes time for the injected nutrients to diffuse to the surrounding area away from the injection point, in the middle of the diffusion, for example, in the region relatively close to the injection point within the above 2 m. The substance is almost supplementarily absorbed by microorganisms grown in the area.

  Therefore, it is next considered to cope with a decrease in decomposition capability by increasing the number of injection wells. If dispersed from a large number of implantation wells, it is theoretically possible to achieve a uniform implantation material concentration in almost the entire region to be repaired. However, increasing the number of injection wells directly increases the cost, and this method cannot always be adopted depending on the location conditions of the area to be repaired. Particularly in places where buildings are densely built, such as in urban areas of Japan, it is often difficult to secure a place for the injection well, which is the entrance of the injection material.

As a method for overcoming such problems of the conventional technique, Japanese Patent Application Laid-Open No. 11-207375 discloses that the injected substance can diffuse to a long distance from the injection point, and microorganisms are almost entirely in the repair target region. A method for remediation of groundwater contamination is described that can maintain the concentration of infused material required for the breeding activity of the plant and cause efficient degradation of the pollutant. In this repair method, ozone dissolved water is injected into one injection well simultaneously with nutrient water simultaneously or alternately to control the growth of microorganisms and to supply oxygen derived from dissolved ozone into the ground. Yes.
Japanese Patent Laid-Open No. 11-207375

  However, when ozone-dissolved water and nutrient water were injected at the same time, depending on the type of nutrient composition contained in the nutrient water, it was decomposed by the oxidizing action of ozone, and the nutrient composition did not diffuse to a long distance. . On the other hand, even if ozone-dissolved water and nutrient water are injected alternately to avoid decomposition of the nutrient composition by ozone, concentric layers are formed from the same injection position, and the groundwater is expanded. However, there is a problem that contact between nutrient water and ozone water occurs near the injection position, the nutrient composition is decomposed by ozone, and the nutrient composition does not diffuse to a long distance.

  In view of such conventional circumstances, the present invention is a groundwater contamination remediation method for decomposing pollutants using microorganisms, and the growth of microorganisms without particularly controlling the nutrient composition concentration and oxygen / ozone concentration in the ground. It is an object of the present invention to provide a method of diffusing an injection substance such as oxygen or a nutritional composition that promotes the above to a long distance from the injection point in the injection well.

  In order to achieve the above object, the groundwater contamination remediation method provided by the present invention injects ozone-dissolved water and nutrient water containing a microbial nutrient composition into a contaminated groundwater zone from one injection well, and pollutants are removed by microorganisms. In the groundwater contamination remediation method that decomposes, ozone-dissolved water and nutrient water are sent into the injection well by separate injection pipes and injected into the injection well from outlets that are spaced apart from each other in the depth direction. And

  In the groundwater contamination repairing method of the present invention, it is preferable that a distance in which the discharge ports of the ozone-dissolved water injection pipe and the nutrient water injection pipe are separated in the depth direction is 1 to 3 m.

  In the groundwater contamination repairing method of the present invention, it is preferable that the injection amounts per unit time of the ozone-dissolved water and the nutrient water are substantially equal.

  In the groundwater contamination remediation apparatus for carrying out the above groundwater contamination remediation method, ozone-dissolved water and nutrient water containing a nutrient composition are injected into a contaminated groundwater zone from one injection well, and the contaminants are decomposed by microorganisms. Ozone dissolved water injection mechanism that supplies ozone dissolved water produced by an ozone dissolved water production device into an injection well through an injection pipe, and nutrition that supplies nutrient water into the injection well through an injection pipe A water injection mechanism, the ozone-dissolved water injection pipe and the nutrient water injection pipe are configured independently of each other, and the position of the discharge port of the ozone-dissolved water injection pipe and the discharge of the nutrient water injection pipe The position of the outlet is spaced apart in the depth direction within the injection well.

  In the groundwater contamination repair apparatus of the present invention, at least one of the position of the discharge port of the ozone-dissolved water injection pipe and the position of the discharge port of the nutrient water injection pipe is changed in the depth direction in the injection well. You can do it.

  According to the present invention, since the injection position of ozone-dissolved water and the injection position of nutrient water are separated in the depth direction in one injection well, the time until ozone and the nutritional composition come into contact with each other is gained. Is possible. Therefore, the situation where the nutrient composition is decomposed at an early stage by ozone is avoided, and the reachability of the nutrient composition and oxygen over a long distance can be greatly improved. As a result, it is possible to shorten the repair period in a wider repair target area, and easily repair a wide repair target area with one injection well without being restricted by obstacles on the ground. Can do.

  The organic pollutant to be repaired by the present invention (hereinafter referred to as the pollutant to be repaired) is not particularly limited. For example, gasoline, light oil, kerosene, heavy oil, crude oil, machine oil, lubricating oil, organic There are petrochemical products such as chlorinated detergents. These components include non-chlorine organic compounds such as benzene, toluene, ethylbenzene, xylene, and ketones, or chlorine-based organic compounds such as trichloroethylene, tetrachloroethylene, dichloroethylene, dioxin, PCB, and PCP (pentachlorophenol). included.

  In addition, as a nutrient composition for microorganisms, a general nutrient composition that has been conventionally used for the microbiological repair method of contaminated groundwater can be used, for example, salts containing inorganic compounds that serve as a nitrogen source or a phosphorus source. , PH adjusters and the like. In addition, when decomposing | disassembling the pollutant to be repaired by the co-metabolism action by microorganisms, in addition to said nitrogen source, a phosphorus source, etc., the hydrocarbons which the microorganisms mainly metabolize are also contained in the said nutrition composition. In addition, oxygen is required in addition to the above nutritional composition in order for microorganisms to grow in groundwater. Therefore, it is desirable to dissolve oxygen in the nutrient water containing the nutrient composition.

  In the present invention, ozone-dissolved water is injected into the contaminated groundwater zone from the same injection well separately from the nutrient water containing the nutrient composition and the like. Even when oxygen is dissolved in nutrient water, the dissolved oxygen concentration in the nutrient water generally decreases as the distance from the injection point increases due to diffusion in the ground. However, in addition to nutrient water containing dissolved oxygen, when ozone-dissolved water is injected into the contaminated groundwater zone, the ozone gradually decomposes into oxygen as it diffuses, so that dissolved oxygen that decreases due to diffusion is offset. Oxygen is produced. For this reason, even in the peripheral part away from the injection point, it is possible to create a distribution state in which the decrease in the dissolved oxygen concentration is suppressed as compared with the conventional dissolved oxygen distribution in which the dissolved ozone water is not injected.

  Furthermore, in the range where ozone of a predetermined concentration exists, the microorganisms in the ground are influenced by the strong oxidizing action of ozone, and as a result, the intake of nutrient components such as nitrogen and phosphorus is suppressed. Since this tendency is greater as the dissolved ozone is less diffused, that is, closer to the injection point of ozone-dissolved water, the consumption of oxygen and nutrient composition is suppressed closer to the injection point. In this way, intentionally suppressing the growth activity of microorganisms may seem paradoxical from the viewpoint of bioremediation, but it is an effective method for uniformly growing bacteria over a wide range. That is, by using this method, it is possible to increase the long-range reach of the nutritional composition contained in oxygen and nutrient water derived from ozone-dissolved water, and to promote the degradation of pollutants by microorganisms in a wide area to be repaired. it can.

  Depending on the type of pollutant to be repaired, it can be expected that the pollutant itself will be directly subjected to chemical action by ozone and converted into a readily degradable substance. For example, in the case where unsaturated hydrocarbons having an ethylene bond are pollutants to be repaired, ozone is added to the double bond portion, and then this portion is cut by the action of water to produce a ketone or an aldehyde. However, for example, in some types of polycyclic aromatic compounds, water-soluble intermediate products with higher toxicity may be generated as a secondary by the chemical action of ozone. Therefore, the ozone-dissolved water should be poured carefully, but this is not the case when the intermediate product changes rapidly to the next stage in a chemical reaction.

  In the present invention, dissolved ozone water and nutrient water are injected into the contaminated groundwater zone from the same injection well through separate injection pipes. At that time, the discharge port of the ozone-dissolved water injection tube and the discharge port of the nutrient water injection tube are separated in the depth direction (vertical direction) within the injection well. That is, ozone-dissolved water and nutrient water are separately injected into the contaminated groundwater zone at different depths. The ozone-dissolved water and the nutrient water may be injected continuously or intermittently at the same time, or alternatively in time.

  Thereby, the number of injection wells to be excavated can be reduced, and ozone-dissolved water and nutrient water injected at different injection positions in the injection well are injected into the contaminated groundwater zone without substantially mixing with each other. As a result, ozone-dissolved water and nutrient water diffuse into the contaminated groundwater zone while avoiding mixing and contact with each other, so the nutrient components of the nutrient composition contained in the nutrient water may be oxidized and decomposed at an early stage by ozone. Avoided. Therefore, it becomes possible to make ozone dissolved water and nutrient water reach the point far from the injection point. Here, the fact that ozone-dissolved water and nutrient water do not substantially mix with each other is not only assumed to be a state in which they are not mixed with each other, but rather is diffused to some extent in the vicinity of each boundary surface. It also includes the state.

  It is desirable that the ozone-dissolved water injection position (discharge port position) and the nutrient water injection position (discharge port position) be separated by 1 to 3 m in the depth direction. The reason for this is that if the distance between the two in the depth direction is less than 1 m, it differs depending on the amount of injection, etc., but ozone dissolved water and nutrient water are likely to come into contact within about 48 hours after being injected into the contaminated groundwater zone. Because. That is, normally, when ozone-dissolved water is left in a cool and dark place, the ozone concentration drops to about 20% of the initial ozone concentration after about 48 hours due to natural decomposition. Therefore, since it is presumed that the oxidative degradation power also decreases and the nutritional composition becomes difficult to be decomposed thereafter, 1 m, which is an interval that requires at least 48 hours to contact each other, was determined as the minimum distance. On the other hand, if the distance in the depth direction of both exceeds 3m, it takes about one week or more for the ozone-dissolved water and nutrient water to diffuse and come into contact with each other. The effect of water cannot be demonstrated. Therefore, the maximum distance of 3 m, which is a distance that can be contacted with each other until one week has passed since the injection into the contaminated groundwater zone, was determined. The values of 1 m and 3 m shown here include an error of about plus / minus 20%.

  The injection amount per unit time of ozone-dissolved water and nutrient water is appropriately determined according to the type of contaminant to be repaired, the size of the region to be repaired, and the like. In general, it is desirable that the injection amounts of ozone-dissolved water and nutrient water are substantially equal. Thereby, it becomes possible to arrange | equalize the diffusion rate of ozone dissolved water and nutrient water. Note that the value of the injection amount per unit time shown here includes an error of about plus or minus 20%. Moreover, the injection amount per unit time is a value measured in each water pump described later.

  Although there is no restriction | limiting in particular in the dissolved ozone density | concentration in the ozone dissolved water at the time of injection | pouring, It is preferable to adjust suitably according to the surrounding environment of the restoration object area | region, and the scale of the restoration object area | region. In the present invention, the injection depth of ozone-dissolved water is different from the injection depth of nutrient water, so even if the dissolved ozone concentration is high to some extent, microorganisms near the injection well are not completely killed, and about half of the microorganisms It is thought that it is possible to expand the groundwater with the nutritional composition. Therefore, considering that ozone gradually decomposes into oxygen, it is preferable that the dissolved ozone concentration at the time of injection is high. However, it should be noted that when the concentration of dissolved ozone at the time of injection is increased, the related equipment costs such as the ozone dissolved water production apparatus increase.

  In groundwater, which is maintained at a water temperature of about 15 ° C throughout the year, the half-life in which ozone is converted to oxygen is more stable than the surface environment where the temperature changes greatly. By adjusting as low as possible even in the neutral range, it is possible to further extend the half-life of dissolved ozone and further improve the long-range reachability of oxygen and nutritional compositions. Conversely, when ozonolysis near the injection well is to be promoted, the pH of the injection water or ozone-dissolved 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 ozone in the ozone-dissolved water injected into the groundwater will eventually be completely converted into oxygen in the ground, and will not affect the subsequent microbial activity in the basin and the underground environment outside the area to be repaired. Also, the decomposition reaction of ozone to oxygen does not induce the large pH change as seen in reactions with other types of oxidants.

  In the present invention, ozone is not released as a gas to the ground because it acts in the underground environment as ozone-dissolved water in a state where ozone is dissolved in water. Compared with ozone gas in the atmosphere, dissolved ozone dissolved in water undergoes a decomposition reaction faster than in the atmosphere due to the presence of water in the surroundings, so dissolved ozone in groundwater rises again to the surface as ozone gas. And will not adversely affect it. Therefore, it is easy to keep the ozone concentration in the surface air near the pollution site at 0.1 mass ppm set by the work safety standard in Japan or 0.05 mass ppm or less of the standard by WHO. .

  In addition, various operating conditions, such as the depth from the ground of the discharge port (injection position) of ozone-dissolved water and nutrient water, the respective injection amounts, and the interval when ozone-dissolved water and nutrient water are alternately injected, It is preferable to determine in advance using analysis and simulation of underground data so that individual injected materials can achieve optimal behavior and diffusion / mixing in the aquifer in the target area .

  As described above, in the present invention, by injecting nutrient water and ozone-dissolved water into the contaminated groundwater zone at different injection depths, avoiding mixing and contact at an early stage of both to suppress decomposition of nutrient components, Therefore, the nutritional composition can be delivered to a place away from the injection point. Moreover, since ozone is not consumed for decomposition | disassembly of a nutrient component at an early stage, ozone can be delivered with the high density | concentration in the place away from the injection | pouring point. As a result, the activity of microorganisms can be moderately suppressed over a wide range, so the range in which the intake of nutritional components by microorganisms can be moderately increased is widened, and the reachability of the nutritional composition to a long distance can be increased. It becomes possible.

  Next, the repair device of the present invention will be described with reference to FIG. In FIG. 1, a groundwater contamination remediation apparatus 1 for injecting ozone-dissolved water and nutrient water containing a nutrient composition into an injection well includes one injection well 2, an unsaturated aquifer A around it, and saturated aquifer. Shown with layer B. Moreover, the injection well 2 is provided so as to reach the saturated aquifer B located below the unsaturated aquifer A.

  The groundwater contamination repairing apparatus 1 includes an ozone-dissolved water injection mechanism 10 and a nutrient water injection mechanism 20. The ozone-dissolved water injection mechanism 10 includes an ozone-dissolved water production apparatus 12 that produces ozone-dissolved water, a water tank 11 that stores water to be supplied to the ozone-dissolved water production apparatus 12, and ozone produced by the ozone-dissolved water production apparatus 12. It is comprised from the water supply pump 13 which pressurizes dissolved water, and the ozone dissolved water injection pipe 14 which has the discharge port 14a in the front-end | tip part.

  The ozone-dissolved water production mechanism 10 has an overall airtight structure so that the dissolved ozone does not escape to the outside air. The ozone generation method of the ozone-dissolved water production apparatus 10 includes an ultraviolet method, a discharge method, a water electrolysis method, and the like, which are appropriately selected in consideration of the scale of equipment, cost, and the like. In general, an ultraviolet type is adopted to reduce the equipment cost, and a discharge type ozonizer is adopted for a large-scale equipment. In addition, materials such as the ozone-dissolved water injection pipe 14 that contacts the ozone-dissolved water and the water pump 13 for ozone-dissolved water must have chemical resistance that can withstand the ozone-dissolved water. For example, Teflon (registered trademark) or chloride It is desirable to use vinyl or the like.

  On the other hand, the nutrient water injection mechanism 20 adjusts and stores the nutrient water in which the nutrient composition or the like is dissolved, a water supply pump 23 that boosts the nutrient water in the nutrient water reservoir 21, and a tip portion. It is comprised from the nutrient water injection pipe 24 which has the discharge port 24a.

  The ozone-dissolved water injection pipe 14 and the nutrient water injection pipe 24 inserted in the injection well 2 are provided with discharge ports 14a and 24a spaced apart in the depth direction in the injection well 2. In addition, the distance between the discharge ports 14a and 24a that are separated in the depth direction is preferably within a range of about 1 to 3 m. The position in the depth direction of the outlets 14a and / or 24a may be fixed or changeable. Even when the depth of the discharge port is changed, the positions of the discharge port of the ozone-dissolved water injection tube and the discharge port of the nutrient water injection tube should always be about 1 to 3 m apart in the depth direction. Is desirable.

  Furthermore, when continuously injecting while changing the depth of the discharge port, the position of one discharge port at any point in time moves from 48 hours before that point to 48 hours after that point. It is desirable that it is always 1 m or more away from any position of the discharge port. In addition, when alternately injecting while changing the depth of the discharge port, the injection position at an arbitrary injection point of one discharge port is between 48 hours before the injection point and 48 hours after the injection point. When injection is performed from the other discharge port, it is desirable that the injection position is always 1 m or more away. This is because if this distance is shorter than 1 m, the nutrient component is decomposed by ozone for the reason described above.

  The change of the depth direction position of the discharge port 14a of the ozone-dissolved water injection tube 14 and the discharge port 24a of the nutrient water injection tube 24 is the insertion depth of the ozone-dissolved water injection tube 14 and the nutrient water injection tube 24 into the injection well 2. It becomes possible by changing the height. At this time, as shown in FIG. 1, by providing flexible pipes 14b, 24b such as bellows or a fluororesin hose between each of the injection pipes 14, 24 and each of the water supply pumps 13, 23, the outlet 14a, It becomes possible to change the position of 24a. Further, for each ozone-dissolved water injection mechanism 10 and / or nutrient water injection mechanism 20, a plurality of injection pipes having different positions in the depth direction of the discharge port are provided in the injection well 2, and a switching valve, the flexible pipe described above, etc. The depth of the discharge port can be changed by appropriately switching using the switching means.

  With the above structure, ozone-dissolved water and nutrient water are supplied by independent injection pipes to outlets located at different depths in one injection well, from which contaminated groundwater zone of the aquifer Injected into. This makes it possible to prevent mixing of ozone-dissolved water and nutrient water in and near the injection well, and diffuses injection substances such as oxygen and nutrients that promote the growth of microorganisms into the ground at a distance from the injection point. It becomes possible to make it.

  As shown in FIG. 1, a sealing member 3 such as Teflon (registered trademark) packing is provided at the opening of the injection well 2, and ozone gas that has escaped from the ozone-dissolved water passes through the opening of the injection well 2 into the atmosphere. You may make it not leak. In addition, a separator (not shown) such as a circular baffle substantially matching the inner diameter of the injection well 2 is provided between the discharge ports 14a and 24a, so that ozone-dissolved water and nutrient water are reliably separated from each other. You may make it inject | pour into a contaminated groundwater zone in a state.

  Using a lysimeter experimental facility that forms an aquifer at all depths, the following experiment was conducted, simulating a site where the aquifer portion at 4 m underground was contaminated with saturated hydrocarbon compounds. That is, nutrient water to which inorganic salts containing nitrogen and phosphorus are added at a predetermined concentration as a nutrient composition for microorganisms, and ozone-dissolved water in which ozone is dissolved are prepared, respectively. A microbiological remediation experiment for groundwater contamination was conducted by continuously injecting from one injection well installed in the area.

  At that time, the ozone-dissolved water was adjusted so that the initial concentration of ozone was 9.1 mg / liter. On the other hand, the nutrient water was adjusted so that the concentration of potassium nitrate was 3.0 mg / liter and the concentration of dipotassium hydrogen phosphate was 35 mg / liter. The ozone-dissolved water and nutrient water were separately injected into the same injection well. At that time, the injection position of ozone-dissolved water was 3 m underground, the injection position of nutrient water was 5 m underground, and each injection amount was 30 hours per hour. Liters.

  Several observation wells were set up around the injection well, and water was collected periodically to investigate the degree of diffusion of each injection component. In addition, the dissolved oxygen concentration in the groundwater before injection was 1.6 mg / liter on average. In addition, the number of aerobic heterotrophic bacteria in the observation wells was measured by collecting a sample water from each well and separately performing a plate dilution medium method using a standard agar medium.

  The total number of aerobic heterotrophic bacteria in the 4m underground of each observation well before the start of the experiment was 10 per milliliter for each of the three observation wells at 1m, 4m, and 8m horizontally from the injection well. Of the 6th power unit.

  As a result of the experiment, the total number of aerobic heterotrophic bacteria in each observation well at 8 weeks after the start of injection is within the three observation wells at a distance of 1 m, 4 m, and 8 m respectively from the injection well. , 10 milliliter units, 10 eighth units, and 10 eighth units per milliliter, respectively. Similarly, the dissolved oxygen concentrations were approximately equal to 5.0 mg / liter, 6.1 mg / liter, and 5.7 mg / liter, respectively. From this result, it was found that the decomposition of the pollutants by the microorganisms progressed almost evenly within a radius of 8 m from the injection well, which is the underground region to be repaired.

  As a comparative example, ozone is dissolved in nutrient water containing the same concentration of nutrient composition as in the above example so that the initial concentration is 3.5 mg / liter, and this nutrient water is injected at a rate of 60 liters per hour. The aquifer was continuously injected into the aquifer at an injection position 4 m below the well, and a microbiological repair experiment was performed under the same conditions as in the example. In addition, the dissolved oxygen concentration of the groundwater in the underground 4 m part before injection was 1.8 mg / liter on average.

  As a result of the experiment, the total number of aerobic heterotrophic bacteria in the 4m underground part of each observation well at 8 weeks after the start of injection was 1 at horizontal points of 1m, 4m and 8m respectively. Per 10 milliliters, 10 7 units, 10 8 units, 10 6 units, and the activity of degrading microorganisms increased at a horizontal distance of 4 m, but at 8 m away Degradation activity was not increased. Similarly, the oxygen concentrations were 4.2 mg / liter, 4.8 mg / liter, and 3.5 mg / liter, respectively, and the values were lower as compared with the above examples as the distance increased.

It is general | schematic sectional drawing which shows one specific example of the groundwater contamination repair apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Groundwater contamination repair apparatus 2 Injection well 10 Ozone dissolved water injection mechanism 11 Water storage tank 12 Ozone dissolved water manufacturing apparatus 13 Water supply pump for ozone dissolved water 14 Ozone dissolved water injection pipe 14a Outlet 20 Nutrition water injection mechanism 21 Nutrition water storage tank 23 Feeding pump for nutrient water 24 Nutrient water injection pipe 24a Discharge port A Unsaturated aquifer B Saturated aquifer

Claims (5)

  In the groundwater pollution remediation method in which ozone-dissolved water and nutrient water containing nutrient composition for microorganisms are injected into a contaminated groundwater zone from one injection well and the pollutants are decomposed by microorganisms, ozone-dissolved water and nutrient water are separated. A method for repairing groundwater contamination characterized by being injected into an injection well through an injection port which is sent into the injection well by an injection pipe and spaced apart in the depth direction.   The groundwater contamination repairing method according to claim 1, wherein a distance in which the discharge ports of the ozone-dissolved water injection pipe and the nutrient water injection pipe are spaced apart in the depth direction is 1 to 3 m.   The method for repairing groundwater contamination according to claim 1 or 2, wherein injection amounts per unit time of the ozone-dissolved water and the nutrient water are substantially equal.   Ozone dissolved water and nutrient water containing nutrient composition are injected into a contaminated groundwater zone from a single injection well and decomposed by microorganisms. An ozone-dissolved water injection mechanism for supplying dissolved water into the injection well through the injection pipe and a nutrient-water injection mechanism for supplying nutrient water into the injection well through the injection pipe, the ozone-dissolved water injection pipe and the nutrient water injection The tube is configured independently of each other, and the position of the discharge port of the ozone-dissolved water injection tube and the position of the discharge port of the nutrient water injection tube are separated in the depth direction within the injection well. Groundwater contamination repair device characterized by that.   The at least one of the position of the discharge port of the ozone-dissolved water injection pipe and the position of the discharge port of the nutrient water injection pipe can be changed in the depth direction within the injection well. Groundwater pollution repair equipment.

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