Patent Description:
In a soil purification method disclosed in Japanese Patent Application Laid-Open (<CIT>purification utilizing microorganisms is performed on contaminated soil. In such a soil purification method, a nitrate solution is injected into the contaminated soil as nutrient for the microorganisms, and the amount of nitrate solution injected is controlled by measuring the nitrate concentration in groundwater of the contaminated soil and determining when there is too much or too little of the nitrate solution.

<NPL>, discloses a ground injection agent concentration management method employed for the biodechlorination of tetrachloroethere to ethene in contaminated soils where dechlorinating microbial organisms from culture KB-<NUM> are used as purification agents and methanol or acetate play the role of activator by acting as electron donors to establish reducing conditions. A closed loop recirculation system is used such that the electron donors are delivered into the feed groundwater to maintain the desired concentration of electron donors in the amended groundwater.

<CIT> discloses directly measuring the concentration of the nitrate solution, which acts as nutrient for the microorganisms for purifying the contaminated soil, in the groundwater of the contaminated soil. However, it is sometimes difficult to measure a concentration of an injection agent for injection into the soil, such as a purification agent for injecting into the contaminated soil, an activator to promote a purification action of the purification agent, or the like.

In consideration of the above circumstances, an object of the present invention is to provide a ground injection agent concentration management method enabling a concentration of injection agent injected into ground to be appropriately managed.

The present invention provides therefore a ground injection agent concentration management method according to independent claim <NUM>. Preferred embodiments of the invention are set forth in the dependent claims.

In the ground injection agent concentration management method according to the present invention, at least one purification agent and at least one activator are injected into the ground through a water injection well, and markers include one marker exhibiting similar behavior to the purification agent, and another different type of marker exhibiting similar behavior to the activator.

In the ground injection agent concentration management method according to the present invention, the at least one purification agent and the at least one activator are injected into the ground. Different types of markers are then respectively employed for the purification agent and the activator. This accordingly enables the concentration of the purification agent and the activator to be estimated from these respective concentrations.

Thus even in cases in which the purification agent and the activator are mixed when injected into the ground, the respective concentrations thereof in the groundwater of the ground are able to be accurately estimated.

The ground injection agent concentration management method according to the present invention enables the estimation of a concentration of an injection agent injected into ground.

Explanation follows regarding exemplary embodiments of the present disclosure, with reference to the drawings. Note that explanation regarding common configuration elements represented by the same reference numerals in plural drawings is sometimes omitted.

An example of a ground injection agent concentration estimation system suitable to carrying out the method according to the present invention is applied to a contaminated ground purification system <NUM> illustrated in <FIG> and <FIG> for decomposing a contaminant contained in subsurface ground <NUM>. The contaminated ground purification system <NUM> includes water pumping wells <NUM>, water injection wells <NUM>, observation wells <NUM>, and a water-shielding wall <NUM> constructed in the subsurface ground <NUM>, a purification unit <NUM> that is constructed above ground level GL and that circulates groundwater between the subsurface ground <NUM>, the water pumping wells <NUM>, and the water injection wells <NUM>, and a measurement device <NUM> for analyzing groundwater sampled from the observation wells <NUM>.

The subsurface ground <NUM> is ground below the ground level GL, and includes an aquifer layer <NUM> through which groundwater flows, and an impermeable layer <NUM> through which groundwater does not flow. A portion of the subsurface ground <NUM> containing contaminant at a reference value or greater (for example a value set for each contaminant type) is referred to as contaminated ground E. The definition of "contaminant" includes organic substances such as tetrachloroethylene, trichloroethylene, cis-<NUM>,<NUM>-dichloroethylene, vinyl chloride monomers, benzene, and the like, inorganic compounds such as hexavalent chromium, cyan, and the like, and oils such as mineral oils like gasoline, diesel, and the like.

A groundwater level HL is indicated in <FIG> by a dotted-dashed line, and the direction of a flow of groundwater through the subsurface ground is indicated by dashed arrows. Note that the flow of groundwater is a flow generated by injecting an injection liquid containing a purification agent or the like, described later, into the subsurface ground <NUM> through the water injection wells <NUM>, and by also pumping groundwater from the water pumping wells <NUM>.

The water pumping wells <NUM> are water pumping means for pumping groundwater from the subsurface ground <NUM>. Groundwater in the aquifer layer <NUM> may be drawn up by water pump P and fed to the purification unit <NUM>. Although the water pump P is illustrated in <FIG> and <FIG> as being installed outside the water pumping wells <NUM> (water pumping wells 22a, 22b), this is merely for configuration explanation purposes, and the water pump P is actually installed inside the water pumping wells <NUM>. However, the water pump P may be installed outside the water pumping wells <NUM>. Moreover, the water pumping wells <NUM> are disposed between the contaminated ground E and the water-shielding wall <NUM>, and the water pumping wells <NUM> are buried in the subsurface ground <NUM> such that a depth of lower ends of the water pumping wells <NUM> are at the depth of the contaminated ground E or deeper.

Although, for convenience, only the two water pumping wells 22a, 22b are illustrated in <FIG>, exemplary embodiments of the present disclosure are not limited thereto, and any appropriate number of the water pumping wells <NUM> may be disposed, according to the size of the site and so on.

Note that the water pumping wells <NUM> may be disposed in the contaminated ground E. Specific methods for pumping water using the water pumping wells <NUM>, and the profile, size, and the like of the water pumping wells <NUM> are known, and so detailed explanation thereof is omitted.

The water injection wells <NUM> (water injection wells 24a, 24b) are injection means used to inject injection liquid produced in the purification unit <NUM> into the subsurface ground <NUM>. The injection liquid may be fed into the subsurface ground <NUM> using pumps and the like, not illustrated in the drawings. The water injection wells <NUM> are wells disposed between the contaminated ground E and the water-shielding wall <NUM> (on the opposite side to the water pumping wells <NUM> from the perspective of the contaminated ground E), and are buried in the subsurface ground <NUM> such that a depth of lower ends of the water injection wells <NUM> is at the depth of the contaminated ground E or deeper.

Although, for convenience, only the two water injection wells 24a, 24b are illustrated in <FIG>, exemplary embodiments of the present disclosure are not limited thereto, and any appropriate number of the water injection wells <NUM> may be disposed, according to the size of the site and so on.

Note that the water injection wells <NUM> may be disposed within the contaminated ground E. Specific methods for injecting the injection liquid using the water injection wells <NUM>, and the profile, size, and the like of the water injection wells <NUM> are known, and so detailed explanation thereof is omitted.

The observation wells <NUM> (observation wells 26a, 26b, 26c) are observation means for observing a subsurface state. Here, the "subsurface state" refers to a state in the subsurface ground <NUM> at positions where the observation wells <NUM> are buried. This includes, for example, a groundwater level, an in-ground temperature, a concentration in the groundwater of a later described purification agent, activator, and marker, and a concentration of a contaminant in the groundwater.

Various sensors, not illustrated in the drawings, are installed in the observation wells <NUM>. The groundwater level, the in-ground temperature, the concentration and the like of the marker, purification agent and the activator in the groundwater as mentioned above are measured by these sensors, and measured values thereof are transmitted as electrical signals to a controller <NUM> of the purification unit <NUM>.

Note that sensors are also installed inside the water pumping wells <NUM> and the water injection wells <NUM>. Namely, the respective water pumping wells <NUM> and water injection wells <NUM> also function as observation means. Signal lines connected to the respective sensors and to the controller <NUM> are omitted from illustration in <FIG> and <FIG>, in order to avoid increasing the complexity of the drawings.

Moreover, the non-illustrated water pump installed inside or outside the observation wells <NUM> is able to take a sample of groundwater at a predetermined depth in the observation wells <NUM>, and to pump the sampled groundwater to the measurement device <NUM> installed above ground.

The observation wells <NUM> are buried at plural locations in the subsurface ground <NUM> enclosed by the water-shielding wall <NUM> and, for convenience, only the three observation wells 26a, 26b, 26c are illustrated in <FIG>. However, exemplary embodiments of the present disclosure are not limited thereto, and any appropriate number of the observation wells <NUM> may be disposed, according to the size of the site and so on.

The water-shielding wall <NUM> is a water-shielding means made from steel poling plates (sheet pile) disposed in the subsurface ground <NUM> so as to enclose the periphery of the contaminated ground E and block the flow of groundwater between the inside and the outside of the water-shielding wall <NUM>. Namely, the water-shielding wall <NUM> is disposed so as to the flow of groundwater in the subsurface ground <NUM> at the "outside" of the water-shielding wall <NUM> and the flow of groundwater in the subsurface ground <NUM> at the "inside" of the water-shielding wall <NUM> do not affect one another.

As illustrated in <FIG>, a lower end of the water-shielding wall <NUM> is embedded in the impermeable layer <NUM>. The contaminated ground E is thus enclosed by the water-shielding wall <NUM> and the impermeable layer <NUM>, suppressing the flow of contaminant out into the subsurface ground <NUM> on the outside of the water-shielding wall <NUM>.

The purification unit <NUM> is a device to purify the groundwater pumped from the water pumping wells by adding at least one of a purification agent and an activator, described later, to the groundwater, and returning the groundwater to the subsurface ground <NUM>. The purification unit <NUM> is configured including a water treatment/warming device <NUM>, an addition tank <NUM>, and the controller <NUM>.

The water treatment/warming device <NUM> separates (and purges) volatile contaminants and oil from groundwater pumped from the water pumping wells. Moreover, the water treatment/warming device <NUM> warms the purified groundwater using a non-illustrated heater that is temperature-controlled by the controller <NUM>, described later. Warming the groundwater using the water treatment/warming device <NUM> promotes reproduction of a decomposer microorganism that biodegrades contaminants in the subsurface ground <NUM>, enabling the activity of the decomposer microorganism to be increased.

The addition tank <NUM> produces injection liquid by adding to the groundwater at least one out of the purification agent and the activator, and a marker. Specifically, at least one out of the purification agent and activator, and the marker, are added to the groundwater inside the addition tank <NUM> from a feeder (not illustrated in the drawings) controlled by the controller <NUM>, described later. This is then agitated to produce the injection liquid for injecting into the subsurface ground <NUM> through the water injection wells <NUM>.

Note that an injection agent according to the present invention comprises at least one purification agent and at least one activator. The "purification agent" is a substance that decomposes the contaminant in the subsurface ground <NUM>, and is, for example, a "decomposer microorganism" such as dehalococcoides, dehalosulphide, or the like for biodegrading the contaminant, or a "chemical decomposer" for chemically decomposing the contaminant. Specific examples of such a chemical decomposer include "reducing agents" such as an iron-based slurry or "oxidizing agents" such as hydrogen peroxide, a persulfate, Fenton's reagent, a permanganate, a percarbonate, or the like.

Note that in said example a decomposer microorganism (dehalococcoides) is employed as the purification agent. Moreover in the addition tank <NUM>, an activator is also added in addition to the purification agent, and detailed exemplary embodiments thereof are described below.

The "marker" is a substance exhibiting similar behavior in the subsurface ground <NUM> (including the contaminated ground E) to that of the purification agent or the activator, described later. The "marker" is also a substance whose concentration is easily measured in-situ (such as, for example, inside a building on or in the vicinity of the contaminated ground E) without employing bulky facilities, even when in a low concentration state. Examples thereof include a fluorescent dye, a halogen ion, a radioisotope, or the like. From among these, uranine, eosin, rhodamine B, rhodamine WT, pyranine, amino G acid, sodium naphthionate, sulforhodamine G, or the like may be employed as a fluorescent dye. A fluorescent dye (eosin) is employed in the first exemplary embodiment.

Reference here to "exhibiting similar behavior. to that of the purification agent or the activator" specifically means that the density, viscosity, adsorption/desorption characteristics, and the like of the marker with respect to the groundwater are about the same as those of the purification agent or the activator.

Moreover, "about the same as" includes cases in which there is a complete match, and cases in which a slight difference arises that is measurable in tests.

This means that the marker may be employed as a substance (tracer) to measure the concentration of the purification agent or the activator in the groundwater of the subsurface ground <NUM>. The concentration of the purification agent or the activator in the groundwater of the subsurface ground <NUM> can be estimated by measuring the concentration of the marker.

Note that although in the present exemplary embodiment the injection liquid is produced by adding the marker to the groundwater in the addition tank <NUM>, the concentration of the purification agent or the activator in the groundwater of the subsurface ground <NUM> can be estimated without employing the marker.

In such cases the temperature of the groundwater is measured. Namely, the injection liquid warmed in the water treatment/warming device <NUM> mixes with the groundwater of the subsurface ground <NUM> and raises the temperature thereof. The purification agent or the activator can accordingly be determined to have reached the location where the temperature is measured when the temperature of the groundwater becomes higher than before the start of injection of the injection liquid. Furthermore, the concentration of the purification agent or activator in the groundwater of the subsurface ground <NUM> can be estimated by measuring the change in this temperature.

Note that in temperature measurement the temperature of the groundwater does not necessarily always need to be measured in the observation well, and the temperature of the subsurface ground <NUM> may, for example, be measured by a thermocouple buried in the subsurface ground <NUM>. Such a method to estimate the concentration of injection agent from the temperature of the subsurface ground <NUM> or the groundwater without employing the marker may also be applied in other exemplary embodiments.

<FIG> illustrates a vertical cross-section to explain a relationship between the observation wells <NUM> and the measurement device <NUM>. The measurement device <NUM> is configured including a header <NUM> and a fluorescence measurement instrument <NUM>.

The groundwater inside the observation wells 26a, 26b, 26c is pumped by pumping water from a predetermined depth using a non-illustrated water pump installed inside each of the wells, and is fed to the fluorescence measurement instrument <NUM> through the header <NUM> of the measurement device <NUM>.

The header <NUM> is a consolidation pipe member to consolidate plural pipes into a single pipe. Opening or closing non-illustrated solenoid valves or valves therein enables selection of whichever groundwater is to be fed to the fluorescence measurement instrument <NUM> from out of the groundwater pumped from each of the observation wells 26a, 26b, 26c.

The fluorescence measurement instrument <NUM> is able to measure the intensity of light emitted from the fluorescent dye serving as the marker contained in the groundwater that has been fed in from the header <NUM>. More specifically, a light intensity C of fluorescence emitted by the fluorescent dye contained in the groundwater when excitation light has been illuminated from a light source device onto the groundwater can be measured. <FIG> illustrates a specific example of light intensities for the wavelengths of the excitation light and the wavelengths of the fluorescence.

The concentration of the fluorescent dye can be computed from the light intensity C. When the fluorescent dye concentration is expressed as a function of light intensity C, i.e. as F(C) (mg/l), then an estimated concentration X (mg/l) of the purification agent (decomposer microorganism) can be expressed in the following manner. <MAT> Wherein α is a coefficient.

The coefficient α is found from differences in adsorption/desorption characteristics measured by performing adsorption/desorption tests with the purification agent (decomposer microorganism) and the fluorescent dye. Note that although the adsorption/desorption characteristics of the marker with respect to the groundwater are, as stated above, about the same as those of the purification agent, there may be an amount of difference therebetween for which the coefficient α can be computed in this manner.

The controller <NUM> receives, as electric signals, information regarding the groundwater level, the in-ground temperature, the concentration and the like of the purification agent or activator in the groundwater, and so on measured by the sensors respectively installed in the observation wells <NUM>, the water injection wells <NUM>, and the water pumping wells <NUM>. The controller <NUM> controls driving of the water treatment/warming device <NUM>, the addition tank <NUM>, and the water pumps P according to the received information.

In the ground injection agent concentration estimation system of the first exemplary embodiment, as illustrated in <FIG>, first in the addition tank <NUM>, the decomposer microorganism (dehalococcoides) serving as the purification agent, and the fluorescent dye (eosin) serving as the marker, are added to the injection liquid for injection into the subsurface ground <NUM> through the water injection wells <NUM>. The concentration of the decomposer microorganism in the injection liquid and the fluorescent dye concentration in the injection liquid are made the same as each other in this case. Namely, the relationship between the respective concentrations in the injection liquid is expressed in the following manner.

Next, the injection liquid, to which the decomposer microorganism (dehalococcoides) and the fluorescent dye (eosin) have been added, is injected from the addition tank <NUM> into the water injection wells <NUM>. The injection liquid injected into the water injection wells <NUM> disperses from the water injection wells <NUM> into the subsurface ground <NUM> and the contaminated ground E at a target speed by generating a water gradient in the groundwater using the water pump P illustrated in <FIG> and <FIG> to pump groundwater from the water pumping wells <NUM>.

When this is performed, due to the decomposer microorganism (dehalococcoides) and the fluorescent dye (eosin) having densities, viscosities, adsorption/desorption characteristics, and the like with respect to the groundwater that are about the same as those of the purification agent or the activator, the speeds of dispersing are about the same as each other, as respectively illustrated by S and T in <FIG>.

However, the decomposer microorganism (dehalococcoides) and the fluorescent dye (eosin) have slightly different adsorption/desorption characteristics, and so differences arise in the concentration in the groundwater in the process of dispersing in the subsurface ground <NUM>. The relationship between the respective concentrations in the groundwater is accordingly estimated in the following manner by employing the coefficient α that accords with the adsorption/desorption characteristics.

Next, the water pumps (not illustrated in the drawings) provided inside the observation wells 26a, 26b, 26c, which are provided at locations spaced apart from the water injection wells <NUM> as illustrated in <FIG>, take samples of groundwater inside the observation wells 26a, 26b, 26c, and feed the groundwater to the fluorescence measurement instrument <NUM>. The light intensity C of the fluorescent dye (eosin) is measured by the fluorescence measurement instrument, and the fluorescent dye (eosin) concentration F(C) (g/l) is computed therefrom.

Substituting the estimated decomposer microorganism concentration X (g/l) and the fluorescent dye (eosin) concentration F(C) (g/l) for the left side of Equation (<NUM>-<NUM>) yields the following expressions.

The Equation (<NUM>) above is obtained by modifying Equation (<NUM>-<NUM>), and the decomposer microorganism concentration is computed therefrom.

Note that although in the present exemplary embodiment the decomposer microorganism concentration in the injection liquid and the fluorescent dye concentration in the injection liquid are the same as each other, exemplary embodiments of the present disclosure are not limited thereto. For example, when the ratio between the decomposer microorganism concentration in the injection liquid and the fluorescent dye concentration in the injection liquid is (a: <NUM>), then the estimated decomposer microorganism concentration is computed by multiplying the right hand side of Equation (<NUM>) by a.

The value of "a" may be freely selected, however, since a contaminant decomposing effect is not expected from the fluorescent dye, the fluorescent dye may be contained at an amount needed to compute the decomposer microorganism concentration, and may be set at a = <NUM>, for example.

When the injection liquid to which the decomposer microorganism has been added is diluted by the groundwater, the decomposer microorganism concentration in the groundwater becomes lower than a detection limit (of the order of <NUM><NUM> copies/ml) measureable using an ordinary measurement method (quantitative PCR method such as quantitative real-time PCR). This makes it difficult to measure the decomposer microorganism concentration in the groundwater in a diluted state.

In contrast thereto, even when the fluorescent dye is diluted to a low concentration state in the groundwater, the light intensity can still be measured using the fluorescence measurement instrument. The fluorescent dye concentration can then be computed from the light intensity.

Moreover, the decomposer microorganism having the densities, viscosities, adsorption/desorption characteristics, and the like with respect to the groundwater that are about the same as those of the fluorescent dye. The decomposer microorganism concentration can accordingly be estimated as long as the fluorescent dye concentration in the groundwater is known.

The contaminant can accordingly be effectively decomposed by appropriately managing the decomposer microorganism concentration in the subsurface ground <NUM> and the groundwater of the contaminated ground E.

Although in the first example a fluorescent dye (eosin) is employed as the marker, a halogen ion is employed as the marker in a second example. In such cases, the estimated purification agent (decomposer microorganism) concentration X (copies/ml) can be expressed in terms of a concentration G(D) (mg/l) of the marker (halogen ion) in the following manner. Note that the concentration G(D) (mg/l) of the marker (halogen ion) is a function of the electrical conductivity D (S/m) measured using an electrical conductivity meter instead of the fluorescence measurement instrument <NUM>. <MAT> Wherein β is a coefficient.

The coefficient β is, similarly to the coefficient α in Equation (<NUM>) of the first exemplary embodiment, found from differences in adsorption/desorption characteristics found by performing adsorption/desorption tests for the purification agent (decomposer microorganism) and the marker (halogen ion).

Note that the concentration G(D) (mg/l) of the halogen ion serving as the marker may be computed as an ion concentration (mol/l) measured using an ion meter instead of an electrical conductivity meter.

Furthermore, as well as a halogen ion, a radioisotope may also be employed as the marker. In such cases, the marker concentration G(D) (mg/l) in Equation (<NUM>) is computed from an amount of radiation (Bq) measured using a radiation measurement instrument.

Although in the first and second examples it is a "purification agent" that is added to the injection liquid in the addition tank <NUM>, in a third example an "activator" is added instead of the "purification agent".

The "activator" is a substance that stimulates bio-decomposition by a decomposer microorganism, and a hydrogen releasing agent, an organic substance, a pH adjuster, micronutrients, trace elements, or the like may be employed as the activator.

Examples of organic substances that may be employed therefor include formic acid, acetic acid, propionic acid, butyric acid, lactic acid, or citric acid, sodium salts, potassium salts, or calcium salts thereof, glucose, fructose, galactose, lactose, maltose, trehalose, peptone, triptone, yeast extract, humic acid, plant oils, and the like.

Examples of pH adjusters that may be employed include sodium or potassium carbonates or bicarbonates such as sodium bicarbonate, sodium carbonate, and the like, ammonium hydroxide, ammonium carbonate, sodium tripolyphosphate, sodium diphosphate, sodium triphosphate, and the like.

Examples of micronutrients that may be employed include vitamin B12, vitamin B1, pantothenic acid, biotin, folate, and the like.

Examples of trace elements that may be employed include Co, Zn, Fe, Mg, Ni, Mo, B, and the like.

Due to these activators also having about the same densities, viscosities, adsorption/desorption characteristics, and the like with respect to groundwater as those of the marker, similarly to with the purification agent in the first exemplary embodiment, the concentration of the activator can be estimated using the marker.

In the present exemplary embodiment a yeast extract is employed as the activator, and a fluorescent dye (eosin) is employed as the marker. The estimated activator (yeast extract) concentration Y (mg/l) can be expressed in terms of the fluorescent dye concentration F(C) (mg/l) in the following manner. <MAT> Wherein γ is a coefficient.

Although a fluorescent dye is employed as the marker in the third example, a halogen ion is employed as the marker in a fourth example. In such cases, the estimated activator (yeast extract) concentration Y (mg/l) can be expressed in the following manner using a concentration X(D) (mg/l) of the marker (halogen ion). Note that as well as halogen ions, a radioisotope may also be employed as the marker. <MAT> Wherein δ is a coefficient.

Although in the first to the fourth examples, one type of "purification agent" or "activator" is added as the "marker" to the injection liquid in the addition tank <NUM>, both "purification agent" and "activator" are added as the "marker" in a fifth example.

More specifically, a decomposer microorganism (dehalococcoides) and a chemical decomposer (hydrogen peroxide) are employed as the purification agent, and a yeast extract is employed as the activator. Moreover, a halogen ion is employed as the marker for the decomposer microorganism, a radioisotope is employed as the marker for the chemical decomposer, and a fluorescent dye is employed as the marker for the activator (yeast extract).

The concentration of the decomposer microorganism (dehalococcoides) and the chemical decomposer (hydrogen peroxide) serving as the purification agent are both estimated using Equation (<NUM>). However, the coefficient β in Equation (<NUM>) is replaced as appropriate according to the respective adsorption/desorption characteristics of the decomposer microorganism (dehalococcoides), the chemical decomposer (hydrogen peroxide), the halogen ion, and the radioisotope. Moreover, the concentration of the activator (yeast extract) is estimated using Equation (<NUM>).

In the fifth example, the respective concentrations of the decomposer microorganism, the chemical decomposer, and the activator can be estimated by measuring the concentration of the halogen ion, the amount of radiation of the radioisotope, and the light intensity of the fluorescent dye in the groundwater sampled from the observation wells <NUM>.

Thus in cases in which the contaminated ground E is contaminated by a contaminant such as tetrachloroethylene and a contaminant such as hexavalent chromium, effective decomposition of the contaminant can be achieved by appropriately managing the respective concentrations of the "decomposer microorganism" and the "chemical decomposer" employed as the purification agents appropriate for the respective contaminant, and by appropriately managing the concentration of the "activator" employed to raise the activity of the decomposer microorganism.

Moreover, plural fluorescent dyes may be employed alone as the marker without employing a halogen ion or a radioisotope.

For example, a yeast extract and a hydrogen releasing agent (polylactate ester) are added as activators to the injection liquid, and different types of fluorescent dye (eosin and uranine) are employed as respective markers therefor.

This thereby enables the respective concentrations of the yeast extract and the hydrogen releasing agent (polylactate ester) to be estimated. Moreover, employing only the fluorescent dyes as markers eliminates the need to use an electrical conductivity meter or a radiation measurement instrument, enabling the concentration of the plural types of activator to be estimated using the fluorescence measurement instrument alone.

Combinations of the above examples may also be employed. For example, the fifth example in which both "purification agents" and an "activator" and "markers" are added, may be combined with the other example in which different types of fluorescent dye are employed as markers. In such cases, the injection liquid may, for example, have a decomposer microorganism added as a purification agent, a yeast extract added as an activator, a fluorescent dye (uranine) added as a marker for the decomposer microorganism, and a fluorescent dye (eosin) added as a marker for the yeast extract.

Namely, purification agents, activators, and markers may be combined freely, and various combinations may be employed. These combinations include one type of purification agent together with one type of marker, plural types of purification agent together with plural types of marker, one type of activator together with one type of marker, plural types of activator together with plural types of marker, one type of purification agent and one type of activator together with two types of marker, plural types of purification agent and plural types of activator together with plural types of marker, etc. However, a reducing agent (for example, an iron-based slurry) serving as a purification agent is preferably not employed in combination with an activator.

Explanation follows regarding various modified examples of the ground injection agent concentration estimation system suitable for carrying out the method according to the present invention. For example, although in the first to the fifth examples, as illustrated in <FIG>, the contaminated ground E in the "single-layer" aquifer layer <NUM> formed above the impermeable layer <NUM> is purified, the present invention is not limited thereto. For example, as illustrated in <FIG>, the contaminated ground E1, E2 in "double-layer" aquifer layers 12A, 12B, formed by the aquifer layer <NUM> being interrupted in the vertical direction by an impermeable layer <NUM>, may be purified. Alternatively a "multilayer" aquifer layer of three or more layers may also be purified.

When purifying the contaminated ground E1, E2 of the "double-layer" aquifer layers 12A, 12B, in addition to water pumping wells <NUM> (water pumping wells 22a, 22b), water injection wells <NUM> (water injection wells 24a, 24b), and observation wells <NUM> (observation wells 26a, 26b, 26c) installed in the lower aquifer layer 12B, water pumping wells <NUM> (water pumping wells 62a, 62b), water injection wells <NUM> (water injection wells 64a, 64b), and observation wells <NUM> (observation wells 66a, 66b) are also installed in the upper aquifer layer 12A.

Then, as illustrated in <FIG>, in addition to a purification unit <NUM> for circulating groundwater between the aquifer layer 12B, the water pumping wells <NUM>, and the water injection wells <NUM>, a purification unit <NUM> is also provided for circulating groundwater between the aquifer layer 12A, the water pumping wells <NUM>, and the water injection wells <NUM>. This approach enables purification of the two aquifer layers 12A and 12B that are interrupted in the vertical direction by the impermeable layer <NUM>. Similarly to the purification unit <NUM>, the purification unit <NUM> also includes a water treatment/warming device <NUM>, an addition tank <NUM>, and a controller <NUM>. Note that the controller <NUM> of the purification unit <NUM> and the controller <NUM> of the purification unit <NUM> may be consolidated into a single unit.

However, in cases in which fluorescent dyes are employed as markers for the purification agents purifying the aquifer layers 12A, 12B, there is a possibility of a fluorescent dye flowing from the aquifer layer 12A to the aquifer layer 12B through portions where the thickness of the impermeable layer <NUM> is thin or there are cracks therein, resulting in two fluorescent dyes mixing in the aquifer layer 12B. There is also the possibility of a fluorescent dye flowing from the aquifer layer 12B to the aquifer layer 12A such that two fluorescent dyes mix in the aquifer layer 12A.

For example, as illustrated in <FIG>, when a fluorescent dye da and a fluorescent dye db have excitation wavelength bands and fluorescence wavelength bands that are mutually adjacent to each other, there is interference between the fluorescence wavelengths of the fluorescent dye da and the excitation wavelengths of the fluorescent dye db. This might accordingly make detection of the fluorescence wavelengths of the fluorescent dye da difficult.

Moreover, as illustrated in <FIG>, when the fluorescent dye da and a fluorescent dye dc that have excitation wavelength bands and fluorescence wavelength bands that overlap with each other are mixed together, there is interference between the fluorescence wavelengths of the fluorescent dye da and the excitation wavelengths of the fluorescent dye dc. Moreover, there is also interference between the fluorescence wavelengths of the fluorescent dye da and the fluorescence wavelengths of the fluorescent dye dc. This might accordingly make detection of the fluorescence wavelengths of the fluorescent dye da and the fluorescence wavelengths of the fluorescent dye dc difficult.

Thus in order to suppress interference between light such as that of the examples illustrated in <FIG> and <FIG>, the two fluorescent dyes employed in the aquifer layers 12A, 12B isolated from each other by the impermeable layer <NUM> are preferably selected such that there is sufficient separation between their respective excitation wavelength bands and fluorescence wavelength bands, such with the fluorescent dyes da, dd illustrated in <FIG>. Note that although examples illustrated in <FIG> and <FIG> show light interference that makes detection of the fluorescence wavelengths of the fluorescent dye da difficult, interference patterns are not limited thereto. For example, when there is interference between the excitation wavelengths of the fluorescent dye da and the fluorescence wavelengths or the excitation wavelength of a different fluorescent dye, then the fluorescence wavelengths of the fluorescent dye da is also sometimes affected so as to become difficult to detect.

Note that the same fluorescent dye may be employed as the marker for the purification agents to purify the aquifer layers 12A, 12B when the impermeable layer <NUM> illustrated in <FIG> is sufficiently thick, not cracked, etc. There is a low possibility of the fluorescent dye mixing in such cases even when the same fluorescent dye is employed therefor.

Moreover, although steel poling plates (sheet pile) is employed as the material of the water-shielding wall <NUM> illustrated in <FIG> and <FIG> in the first to the fifth exemplary embodiments, exemplary embodiments of the present disclosure are not limited thereto. For example, frozen earth, concrete, a cement-improved body, or the like may be employed therefor. Moreover, the water-shielding wall <NUM> does not necessarily need to be provided. In cases in which the water-shielding wall <NUM> is not provided, the water injection wells <NUM> are preferably disposed on an upstream side of a groundwater flow, and the water pumping wells <NUM> are preferably installed on the downstream side thereof. This enables injection liquid that has been injected into the subsurface ground <NUM> from the water injection wells <NUM> to be made to permeate smoothly into the subsurface ground <NUM>.

Although water quality improvement is performed in the first to the fifth examples by air being feed into the groundwater with the water treatment/warming device <NUM> illustrated in <FIG> and <FIG>, the present invention is not limited thereto. For example, a method to perform water quality improvement by adding a purification agent to the groundwater to cause a reaction, or a method designed to separate contaminants from the groundwater by adsorption of the contaminants contained in the groundwater, may be employed as methods to perform water quality improvement.

Nutrient salts and oxygen may be mixed in, or fresh decomposer microorganism may be mixed in, as the purification agent in cases in which groundwater is purified by employing a decomposer microorganism to biodegrade a contaminant. Moreover, a flocculant may be mixed in to achieve smooth injection of the injection liquid using the water injection wells <NUM>.

Although the groundwater purified in the water treatment/warming device <NUM> is warmed by a heater in the first to the fifth examples, the present invention is not limited thereto. For example, the groundwater may be warmed by causing heat exchange to take place between a heating medium in an air conditioner unit (not illustrated in the drawings) and the groundwater purified in the water treatment/warming device <NUM>. Furthermore, waste heat, steam or the like from a building on or in the vicinity of the contaminated ground E may be utilized for warming. Note that warming might not always be needed in cases such as those in which the decomposer microorganisms are already active at a predetermined activity level.

In an example outside the scope of the present invention, the ground injection agent concentration estimation system may be applied to a ground improvement system to counter liquefaction of the subsurface ground <NUM>. In such cases, a supercooled aqueous solution, air bubble infused water, a solidification agent, or the like may be employed as the injection agent, and similarly to in the contaminated ground purification system <NUM>, a fluorescent dye, halogen ion, radioisotope, or the like may be employed as the marker. Alternatively, the concentration of the injection agent may be estimated from temperature measurements of the groundwater instead of by using a marker.

Note that a supercooled aqueous solution is an aqueous solution such as erythritol, sodium acetate trihydrate, sodium acetate decahydrate, or the like for injection into the subsurface ground <NUM> in a super-cooled state. Crystals are then introduced or a shock is imparted thereto at the point in time when the concentration of the supercooled aqueous solution in the groundwater has reached a predetermined concentration, thereby inducing crystallization to occur. Ground improvement is thereby achieved by solidifying the subsurface ground <NUM>.

Moreover, air bubble infused water is a liquid resulting from infusing water with fine bubbles (air bubbles having a diameter of <NUM> or less), microbubbles (air bubbles having a diameter of <NUM> to <NUM>), or ultrafine bubbles (air bubbles having a diameter of <NUM> or less). The air bubble infused water is then injected into the subsurface ground <NUM> so as to achieve a state in which the groundwater does not saturate the subsurface ground <NUM> and contains air bubbles at a predetermined concentration. The water pressure in pores between particles of the subsurface ground <NUM> is thereby suppressed from rising during an earthquake, enabling liquefaction to be made less liable to occur.

Moreover, a material that may be employed as the solidification agent may be: a liquid suspension type non-waterglass based solidification agent such as a clay/cement based (such as bentonite, cement, or the like), an ultrafine particle based (such as Highbrid Silica (registered trademark)), or a special slag based (such as SILACSOL (registered trademark)- UF or the like) non-waterglass based solidification agent; a liquid suspension type waterglass based solidification agent such as an alkali (RMG-S5 or the like) or a neutral/acidic (Creanfarm or the like) liquid suspension type waterglass based solidification agent; a waterglass based liquid type inorganic solidification agent such as an alkali (ALSELICA (registered trademark) or the like), a neutral/acidic (HARDLIZER (registered trademark) or the like), a special neutral/acidic (Ecoryon(registered trademark) or the like), a special silica (ECOSILICA (registered trademark) or the like) waterglass based liquid type inorganic solidification agent; or an alkali (RSG-<NUM>) waterglass based liquid organic solidification agent.

Furthermore, the ground injection agent concentration estimation system may be applied to a heat storage system utilizing heat in the ground of the subsurface ground <NUM>. In such cases, a heat storage material such as a supercooled aqueous solution is employed as the injection agent, and similarly to in the contaminated ground purification system <NUM>, a fluorescent dye, halogen ion, radioisotope, or the like is employed as the marker.

Note that erythritol, sodium acetate trihydrate, sodium acetate decahydrate, or the like have a relatively large heat capacity when employed as a supercooled aqueous solution, in comparison to water or concrete, and accordingly readily exhibit the functionality of a heat storage material.

Claim 1:
A ground injection agent concentration management method, comprising:
injecting an injection liquid, to which an injection agent comprising at least one purification agent to decompose a contaminant, at least one activator to activate bio decomposition by the purification agent and markers comprising a first marker and a second different type of marker wherein the first marker is exhibiting similar behavior to the purification agent and the second different type of marker is exhibiting similar behavior to the activator have been added, into the ground through a water injection well (<NUM>);
measuring a concentration of the markers in groundwater at a location spaced apart from the water injection well (<NUM>);
estimating a concentration of the injection agent in the groundwater from the concentration of the markers;
receiving, as electric signals, information regarding the concentration of the at least one purification agent and the at least one activator in the groundwater, and
controlling driving of an addition tank (<NUM>) according to the received information, so as to produce the injection liquid for injecting into the ground through the water injection well (<NUM>), by adding the at least one purification agent, the at least one activator and the markers to the groundwater inside the addition tank (<NUM>).