JP2002282834A - Soil purification agent and soil purification method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a soil purification method that can remove organic halogen compounds from a soil that is contaminated by organic halogen compounds directly and quickly and a soil purification agent that can be advantageously used for this method. SOLUTION: This invention relates to a soil purification agent in order to purify a contaminated soil. The soil purification agent comprises an aqueous suspension where an amino acid and a fine metal powder having a reducing action are dispersed in water and the purification method that uses it.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a soil contaminant used for removing contaminants from soil contaminated with organic halides, hexavalent chromium and the like, and to purify contaminated soil. About the method.

[0002]

2. Description of the Related Art Organic halides such as trichloroethylene have been used in large quantities for industrial cleaning such as removing oils from machinery. From the viewpoint of environmental pollution, the use of such organic halides has recently been regulated. However, a large amount of organic halides has already been used, so that soil pollution or water pollution has been progressing. That is, organic halides such as trichloroethylene are stable and hard to be decomposed by microorganisms, and organic halides dumped in the natural environment not only pollute soil, but also eventually pollute rivers and groundwater, which is It can be a source of water, which is a problem. It is known that such pollution of the natural environment is also caused by hexavalent chromium left on the site of a factory such as a plating factory.

As a method for purifying soil contaminated with volatile organic compounds such as the above-mentioned organic halides, a soil gas suction method, a groundwater pumping method, a soil excavation method and the like are known. The soil gas suction method forcibly sucks the target substance present in the unsaturated zone.A suction well is installed in the ground by boring, the inside of the suction well is depressurized by a vacuum pump, and Compounds are collected in a suction well, guided underground, and treated by a method such as adsorption of organic compounds in soil gas to activated carbon. In the case where the contamination by the organic compound reaches the aquifer, a method of installing a submersible pump in the suction well and pumping the water together with the soil gas for treatment is adopted.

[0004] The underground pumping method is a method in which a pumping well is installed in soil, and contaminated groundwater is pumped and treated. Further, the soil excavation method is a method in which contaminated soil is excavated, and the excavated soil is subjected to wind drying and heat treatment to remove and recover organic compounds.

As a method of purifying contaminated water such as collected contaminated water or groundwater as described above, for example, Japanese Patent Publication No. 2636171 discloses a method of removing dissolved oxygen in contaminated water and then removing contaminated water such as iron. A method of contacting a metal surface to reduce and remove an organic halide contained in contaminated water is disclosed. Such a method of purifying contaminated water using the reducing action of iron is disclosed in JP-A-3-106496, JP-A-3-30895, JP-A-6-501521, JP-A-8-257570, JP-A-10-26
It is also described in Japanese Patent No. 3522 and the like. Each of these methods is a method of treating contaminated water by passing it through a fixed portion such as a layer containing iron or a filter.

However, these methods do not purify soil directly, but purify contaminated water collected by the above-mentioned soil gas suction method, groundwater pumping method, or contaminated water such as rivers and groundwater. Since the number of objects is extremely large and the processing speed is not high, the processing often takes a long time. Another drawback is that the processing steps are often complicated.

[0007] A method of purifying soil contaminated with hexavalent chromium with a reducing agent such as ferrous sulfate is known. However, such soil is contaminated with trivalent and hexavalent chromium like chromium slag. In the presence of ferrous sulfate, sufficient reduction cannot be performed because ferrous sulfate has a short reducing action time.
Therefore, it cannot be said that the purifying agent exhibits a reducing action over a long period of time.

[0008] WO / 01-08825 is a purifying agent which can be directly applied to the soil, easily penetrates into the soil, and can be rapidly purified. Aqueous suspensions have been proposed. By using this purifying agent, this contaminant can be directly and efficiently reduced and detoxified or removed after detoxification, thereby improving the drawbacks of the conventional soil purifying agent.

[0009]

However, for example, when iron fine particles having a large particle size of several tens to several hundreds of micrometers, such as those conventionally used, are used.
Not only does the permeability of the soil become slower, but its surface area also decreases sharply, reducing the rate of purification. Therefore, it is necessary to improve the contaminants such as organic halides so as to exhibit an action of reductively decomposing them more rapidly (a so-called dehalogenation action).

[0010] It is an object of the present invention to provide a soil which can be detoxified or removed after detoxification from soil contaminated with contaminants such as organic halides and hexavalent chromium by efficiently reducing the contaminants. It is to provide a purification agent and a purification method using the soil purification agent. In particular,
A soil purification agent that can be obtained from general-purpose materials, can be directly or quickly detoxified by reducing this contaminant, or can be removed after detoxification, and a purification method using this soil purification agent. To provide.

[0011]

Means for Solving the Problems The present inventors have developed a soil purifying agent based on a metal such as iron which exhibits an action of reducing and decomposing an organic halide (so-called dehalogenation action).
Investigations have been repeated to enhance the purifying action. As a result, it has been clarified that the purifying action is remarkably improved by adding an amino acid to an aqueous suspension of reducing metal particles, particularly iron particles. Although the action of the amino acid is not clear, for example, it is considered that the amino acid is first adsorbed on the surface of the iron fine particles, thereby facilitating contact with contaminants such as organic halides and promoting the reduction reaction.

It has also been found that the reducing action by the metal fine particles and the amino acid is effective as long as it is a contaminant which can be reduced, in addition to the organic halide, and is particularly effective against hexavalent chromium.

[0013] The above object is achieved by a soil purifying agent for purifying contaminated soil, comprising a metal fine particle having a reducing action and an aqueous suspension in which amino acids are dispersed in water. can do.

As the above-mentioned metal fine particles, iron fine particles are preferable because of a quick reduction reaction and easy availability. The average particle size of the metal fine particles is generally in the range of 0.1 to 500 μm, preferably 0.1 to 200 μm, and more preferably 0.1 to 200 μm.
50 μm, particularly preferably 0.1 to 15 μm. Further, the content of the metal fine particles in the entire aqueous suspension is 0.1 to 4%.
Considering the viscosity, stability, and effectiveness of the suspension, the fact that it is in the range of 0% by mass and the content of the amino acid with respect to the whole aqueous suspension is in the range of 0.01 to 5% by mass. preferable. Further, the pH of the aqueous suspension is preferably in the range of 6 to 13 from the viewpoint of preventing oxidation of the metal fine particles. It is effective for organic halides and / or hexavalent chromium among the pollutants of the contaminated soil, particularly for organic halides.

[0015] Further, the object is to provide the above soil purifying agent,
It can be achieved by a method of detoxifying, detoxifying, or removing contaminants (eg, organic halides, hexavalent chromium, etc., especially organic halides) from contaminated soil, by infiltrating the contaminated soil. . Preferably, a method of permeating the soil-purifying agent by spraying the soil-purifying agent on substantially the entire surface of the soil; applying the soil-purifying agent to contaminated soil (particularly soil contaminated with an organic halide). Inserting an injection pipe for supply and injecting the soil purifying agent into the injection pipe can be mentioned. In such a purification method, the surface of the soil contaminated with the organic halide can be further covered with a sheet (generally, the cover of the sheet is provided after the cleaning agent is injected).

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The soil purifying agent of the present invention rapidly detoxifies a soil contaminated with a contaminant such as an organic halide or hexavalent chromium by reduction or the like, or removes the pollutant after detoxification. This is an aqueous suspension in which metal fine particles and amino acids are dispersed in water.

As the pollution source to be purified according to the present invention,
Organic halides, hexavalent chromium, and cyanide can be mentioned, and organic halides and hexavalent chromium are suitable, and organic halides are particularly suitable. Examples of organic halides include 1,1-dichloroethylene, 1,2
-Dichloroethylene, trichloroethylene, tetrachloroethylene, dichloromethane, carbon tetrachloride, 1,2-dichloromethane, 1,1,1-trichloroethane, 1,
Examples thereof include 1,2-trichloroethane, 1,1,2,2-tetrachloroethane, and dichlorodifluoroethane. It is considered that these organic halides lose halogens and become corresponding hydrocarbons due to the dehalogenating action (reducing action) of iron, and are removed from soil.
As an organic halide, it is particularly effective for an organic chloride (organic chlorine-substituted compound). Hexavalent chromium can be efficiently reduced to trivalent chromium by an effective iron reducing action over a long period of time, and then can be removed from the soil if necessary. Furthermore, cyanide (cyan ion) forms a complex with iron ion and is detoxified.

In the present invention, fine metal powder is used as the metal powder so that the soil purifying agent can be directly applied to the contaminated soil, that is, can penetrate into the soil after application. The average particle diameter of the metal fine particles is generally in the range of 0.1 to 500 μm,
The range is preferably from 0.1 to 200 μm, more preferably from 0.1 to 5 μm.
A range of 0 μm, particularly a range of 0.1 to 15 μm is preferable.

The metal is a metal having a reducing action.
For example, Fe, Mn, Mg, Zn, Al, Ti and the like can be mentioned, but iron is preferable because of a quick reduction reaction and easy availability. The shape of the iron fine particles is generally indefinite, but a spherical one can also be used, which is preferable.

Incidentally, the iron fine particles preferably used in the present invention means fine particles containing pure iron as a component. However, pure iron in which a part of pure iron has been changed to iron oxide or a component other than iron is used in a small amount. May be included. The shape of the iron fine particles is generally indefinite, but spherical ones can be used. Spherical ones are preferable because they have a higher specific surface area and thus have a high reduction action efficiency. The average particle size of the iron fine particles is also preferably in the range of 0.1 to 500 μm, as described above.
It is more preferably in the range of 1 to 200 μm, more preferably in the range of 0.1 to 50 μm, and particularly preferably in the range of 0.1 to 15 μm.

The average particle size can be measured using a laser diffraction type particle size distribution measuring device (for example, Mastersizer 2000, manufactured by Malvern). In addition, volume%
Is multiplied by the average density of the metal fine particles to obtain the mass%, so that the distribution of the volume% can be regarded as the distribution of the mass% as it is. If the average particle size of the iron fine particles is larger than 500 μm, the specific surface area of iron is small and the reduction action efficiency is reduced. Further, the permeability into the soil is reduced, and the workability of injecting into the soil is unfavorably deteriorated. The mixing amount of the metal fine particles is 0.1 to 40% by weight, preferably 1 to 20% by weight, and more preferably 3 to 10% by weight based on the whole aqueous suspension. If the amount is less than 0.1% by weight, the reducing action is hardly exhibited, and if it is more than 40% by weight, the permeability into the soil decreases, and the workability of pouring into the soil deteriorates.

When iron is used as the metal fine particles,
Metals other than the above-mentioned irons can be used in combination.

The metal fine particles such as iron fine particles used in the present invention may be pulverized using a media-less pulverizer, a media pulverizer or the like. For example, various pulverizers such as a roll mill, a sand mill, a ball mill, an attritor, a kneader, and a jet mill can be used. Further, by using a pulverizer, the surface of the metal fine particles can be activated by grinding, and the reducing action can be enhanced.

The amino acid used in the present invention is a compound having an amino group and a carboxyl group in the molecule, and is not particularly limited. For example, glycine,
Alanine, valine, leucine, isoleucine, serine,
Threonine, cysteine, methionine, asparagine,
Glutamine, aspartic acid, glutamic acid, lysine,
Α-amino acids such as arginine, phenylalanine, tyrosine, histidine, tryptophan, proline and oxyproline, β-amino acids such as β-aminopropionic acid, γ-amino acids such as γ-aminobutyric acid, anthranilic acid and m-aminobenzoic acid Aromatic amino acids. In addition, salts of the above-mentioned amino acids with various metals, acids and / or alkalis such as monosodium glutamate can also be mentioned. Of these, amino acids containing no sulfur atom are preferred. These may be used alone or in combination of two or more. The amount of the amino acid to be added is 0.01 to the entire aqueous suspension.
5 mass% is common, and 0.1 to 1 mass% is preferable.
In addition, it has been confirmed by the present inventors that the effects of the present invention can be seen only in the above-mentioned amino acids, and cannot be seen in so-called amino acid-type surfactants obtained by modifying amino acids.

The pH of the aqueous suspension used as the soil purifying agent of the present invention is preferably adjusted. The pH adjustment method used in the present invention can be carried out by adding various acidic or alkaline substances to an aqueous liquid as a purifying agent, or using carbonated water used for adjusting the purifying agent. The pH of the aqueous suspension is generally in the range of 6 to 13, and preferably in the range of 7 to 10. If the pH is less than 6, the surface oxidation of the iron fine particles proceeds rapidly and is passivated, so that the decomposition effect of the organic halogen compound is reduced.
On the other hand, when the pH is higher than 13, the reducing action of iron decreases, and it takes a long time to detoxify the organic halogen compound, which is not preferable.

As the water for dispersing the metal fine particles and the water used for adjusting the purifying agent, reducing electrolyzed water (preferably pH = 6 to 13) is preferable from the viewpoint of minimizing the oxidation of iron.

The metal fine particles and the amino acid are dispersed in water or carbonated water by mixing water or carbonated water, and the metal fine particles with the amino acid, and it is preferable to use a disperser. As the disperser, a mixer usually used for suspension or emulsification is used. For example, a batch mixer such as a homomixer, a toothed disk mixer, a homomixer, a combimix, a Keddy mill, a Shaflow, or a continuous mixer such as a pipeline mixer, a colloid mill, a high line mill, a homomic line flow, a high-pressure homogenizer, and the like. A mixer can be used. In order to stabilize the dispersion of the aqueous suspension, it is also effective to form bubbles around the metal fine particles at the time of dispersion, or to add an additive such as a dispersant. Since the metal fine particles used in the present invention are fine, there is a possibility that some aggregates will be formed during long-term storage or during the process of dispersing in water, so that they can be redispersed before use.

In order to form bubbles around the metal fine particles, a foaming agent is added to a mixture of iron fine particles and water and mixed (preferably strongly mixed), or a mixture of iron fine particles and water is mixed with air or the like. A gas may be introduced or a combination of the two may be used. If desired, a blowing agent may be used. It is preferable to use a foaming agent because it is necessary to attach bubbles to the iron fine particles and stabilize the particles in water.

Examples of the foaming agent include decomposed products of animal proteins [eg, trade name: Escort K (manufactured by Manol Co., Ltd.)], saponified pine resin (sodium abientate) [trade names: Vinsol, Sanei] Chemical Co., Ltd.] and higher alcohol sulfates (trade name: Fineform, manufactured by NMB Corporation) are preferred. The foaming agent is preferably used in the range of 0.1 to 10% by weight, particularly 0.5 to 5% by weight based on the metal fine particles.

The fine metal powder such as iron powder used in the present invention has a large surface area and is easily oxidized (passivated) on the surface. Therefore, a hydrophilic binder and / or a metal halide are used in combination to prevent this. You may.

The metal halide is NaCl, KCl,
MgCl ₂ , CaCl _2, etc.
aCl is preferred. Metal halides have the function of reducing iron hydroxides and oxides to metallic iron. The amount used is generally 10 to 200% by weight, preferably 10 to 50% by weight, based on the metal fine particles.

The hydrophilic binder has a function of covering the surface of the metal fine particles and protecting the organic halide from being oxidized before exhibiting a reducing action. Examples of the hydrophilic binder include disaccharides such as sucrose, sucrose derivatives (eg, higher fatty acid esters of sucrose), monosaccharides such as glucose, alginic acid; pullulan, PVA (polyvinyl alcohol), CMC (carboxymethylcellulose), polyacrylamide, Water-soluble resins such as guar gum, methyl cellulose, hydroxyethyl cellulose and the like can be mentioned. Pullulan (having a particularly low viscosity in aqueous solution), hydroxyethylcellulose, sucrose, glucose and PVA are preferred. The use of a biodegradable polymer as a hydrophilic binder is particularly effective against secondary environmental pollution. The amount used is generally 10 to 200% by weight with respect to the metal fine particles, and 10 to 100% by weight.
% By weight is preferred.

The use of a biodegradable polymer (eg, biodegradable polycaprolactone) in place of the hydrophilic binder is particularly effective against secondary environmental pollution.

It is preferable that the soil purifying agent of the aqueous suspension further contains a metal sulfate (particularly, ferrous sulfate) as a reducing agent. Since this reacts with oxygen in the air, oxidation of the surface of the metal fine particles can be prevented.

The aqueous suspension preferably further contains an inorganic carbonate or a carbonate mineral. Examples of these are calcium carbonate, precipitated calcium carbonate,
Examples thereof include magnesium carbonate, coral fossil limestone, limestone, and dolomite, and sedimentable calcium carbonate is particularly preferable. Since the soil purifying agent of the present invention uses fine-particle iron, it can be injected into the gap between the soil particles in the soil. However, since the possibility of elution into groundwater or the like is increased by making the particles fine, in the present invention, it is preferable to fix the eluted iron ions by using the above-mentioned carbonate and prevent this.

The soil purifying agent of the aqueous suspension of the present invention is obtained by mixing the above metal fine particles, amino acid and water as described above. In this case, as the water used for dispersion, from the viewpoint of minimizing oxidation of iron or the like, reducing electrolyzed water (pH = 6 to 13 is preferable) as described above.
It is preferable to use As the dispersant, naphthalene sulfonic acid or the like may be used. The amount of the dispersant used is generally 0.01 to 10% by weight based on the iron fine particles.
1-5% by weight is preferred. Organic acids (eg, ascorbic acid, citric acid, malic acid, erythorbic acid) and salts thereof can be used as antioxidants. The amount of the antioxidant used is generally 0.01 to 10% by weight, preferably 0.1 to 3% by weight, based on the iron fine particles.

The method for purifying contaminated soil according to the present invention using a soil purifying agent is carried out by applying the above soil purifying agent to soil (ground) contaminated with an organic halide or the like. Preferably, the method of permeating the soil purifying agent by spraying the soil purifying agent (1); or inserting an injection pipe for supplying the above soil purifying agent into soil contaminated with an organic halide or the like. Then, a method (2) comprising injecting the soil purifying agent into the injection pipe can be mentioned.

The above purification method (2) can be performed, for example, as follows.

The above method (2) can be performed, for example, as follows.

An injection pipe for supplying a soil purifying agent by boring is provided on the surface contaminated with the organic halide. A plurality of injection tubes can be provided at intervals as needed. Inject the soil cleanser into the supply inlet. As a result, the fine metal particles penetrate into the contaminated soil and gradually come into contact with the organic halide to decompose and remove the organic halide. Before injecting with an injection pipe, groundwater may be drained from an injection pipe and then a soil purifying agent may be injected. The soil surface may be covered with a water-impermeable sheet (eg, bentonite sheet) so that the injection liquid does not overflow from the soil surface. Alternatively, a sheet may be embedded in the soil.

The above purification method may be performed, for example, as follows. That is, as shown in FIG.
Blocked by an impermeable layer 12 leading to the impermeable underground ground 11,
An injection pipe 9, if necessary, a gas-permeable columnar portion 2 and a horizontal gas-permeable layer 4 are installed in the soil inside, and an impermeable sheet 6 (eg, high-density polyethylene, polyvinyl chloride,
(A sheet made of a polymer compound such as polyurethane), and the periphery thereof can be blocked by an impermeable layer 7 made of backfilled earth and sand mixed with a glue material outside the impermeable layer. In the horizontal ventilation layer 4, an intake pipe 5, which is a perforated pipe composed of many holes having a size that does not allow the gas-permeable material 3 to pass through, is embedded.

In the purification treatment, for example, drainage is performed through a water injection pipe, the cleaning agent of the present invention is injected from an injection pipe, and the pressure is reduced as necessary. Can be removed.

Covering the surface of soil contaminated with organic halides with an impermeable sheet, as in the method described above (generally, the sheet covering is installed after injecting the purifying agent)
Preferably, a gas-permeable columnar portion (useful for removing the generated substance) can be provided as necessary.

The soil purifying agent of the present invention is basically composed of fine metal particles, amino acids and water. That is, it is considered to be present by adhering to the periphery of the metal fine particles, and therefore has relatively low viscosity and excellent fluidity. Therefore, as described above, it is easy to be injected into the soil, metal fine particles penetrate deep into the soil,
Immediately, a rapid purification action is exhibited.

Soil contaminated with contaminants other than organic halides can be carried out in the same manner as described above. In addition, contaminated soil (especially soil contaminated with hexavalent chromium)
Excavated soil can be introduced into a reaction tank or the like by the soil excavation method and treated with the soil purification agent of the present invention, and it may be advantageous to remove the treated chromium compound or the like.

The amount of fine metal particles to be injected into the soil is generally in the range of 1 to 40 iron fine particles per m ³ of soil.
0 kg, preferably 10-200 kg.

Further, the injection of the soil purifying agent includes the injection of a soil purifying agent comprising an aqueous suspension containing fine metal particles,
The injection of another material may be performed separately. Also, the combination of the materials can be appropriately performed. For example, after injecting a soil purifying agent composed of an aqueous suspension containing iron fine particles, an aqueous solution or dispersion of an amino acid or a carbonate may be injected.

[0048]

EXAMPLES The present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.

The measurement of the particle size distribution of the iron fine particles used in the examples and the measurement of the organic halide in the treated wastewater were carried out as follows.

(I) Method for Measuring Particle Size Distribution of Iron Fine Particles Laser diffraction type particle size distribution measuring device (Mastersizer 20
00; manufactured by Malvern Co., Ltd.). (II) Method for measuring organic halide The measurement was carried out in accordance with JIS K0125 (Testing method for volatile organic compounds in water and wastewater).

The organic halide was extracted by a solvent extraction method using n-decane as an extraction solvent, and quantified using a gas chromatograph (HP-5890 Series II; manufactured by Hewlett-Packard Company).

The materials used in the examples and their abbreviations are as follows.

Iron Fine Particles A: Average Particle Size = 144 μm, Shape = Amorphous Iron Fine Particles B: Average Particle Size = 1 μm, Shape = Spherical Glycine: Gly Leucine: Leu Monosodium Glutamate: GluNa Amino Acid Surfactant (Azispar PW- 111 (aqueous), Ajinomoto Co., Ltd.): AP The particle shape was determined by SEM (scanning electron microscope) observation. [Examples 1 to 6, Comparative Examples 1 to 5] Iron fine particles, amino acids,
The reduced electrolyzed water was mixed at a ratio (mass ratio) shown in Table 1 using a stirrer to obtain an aqueous suspension (soil purification agent).

[0054] The obtained soil purifying agent was injected into the soil contaminated with trichloroethylene (TCE) under the conditions of an injection amount of 40 m ³ and an injection pitch (interval between injection pipes) of 2 m with respect to 200 m ³ of the contaminated soil. After the injection, the sample was allowed to stand for two weeks, and samples sampled from four places in the soil were measured in accordance with JIS K0125. Table 2 shows the results.

[0055]

From the above results, it can be seen that the purification rate was significantly improved by using the iron fine particles and the amino acid together. It can also be seen that the purification rate is significantly improved by using amino acids even for iron fine particles having a relatively large particle size (iron fine particles A) having a low purification rate (Example 1 and Comparative Example 1). . In addition, when iron fine particles having a fine particle size are used, effective contamination is possible by using extremely low concentration of iron, and the amount of iron used can be significantly reduced (Example 2 and Comparative Example 2).

Further, from Comparative Example 5, it can be seen that even when the same amino acid as that of the present invention is used, the purification action is hardly obtained when the modified amino acid derivative surfactant is used.

The environmental standard for soil contamination of TCE is 0.03 mg or less per 1 L of test solution (the environmental standard value for protection of human health is 0.03 mg / L or less).
It can be seen that the soil purifying agent of the present invention can significantly lower such a value.

[0059]

According to the present invention, this contaminant can be detoxified by reducing it efficiently or removed after detoxification. The use of the amino acid of the present invention enables a high-speed purification treatment, so that metal particles such as iron particles having a relatively small purification speed and relatively large particle size can be used, and the use of low-concentration metals such as iron. Thus, high-speed purification can be performed, and the amount of metal used for purification can be significantly reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an example of an embodiment of the method of the present invention.

[Explanation of symbols]

 2 Air-permeable columnar part 3 Air-permeable material 4 Horizontal air-permeable layer 5 Intake pipe 6 Impermeable sheet 7 Impermeable layer 9 Injection pipe 11 Underground impermeable ground 12 Impermeable layer

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasunori Kimura 2-3-13 Kyobashi, Chuo-ku, Tokyo Inside Toyo Ink Manufacturing Co., Ltd. (72) Inventor Masami Kuwahara 2-3-1 Kyobashi, Chuo-ku, Tokyo Toyo Ink Manufacturing Co., Ltd. (72) Inventor Terunobu Maeda 2-5-8 Kitaaoyama, Minato-ku, Tokyo F-term (reference) 2D040 AA00 AB01 AC00 CA10 CB03 CC05 2E191 BA02 BA12 BB01 BC01 BC05 BD11 4D004 AA41 AB03 AB06 CA35 CA37 CC11 CC15 DA03 DA10 DA20

Claims (12)

[Claims] 1. A soil purifying agent for purifying contaminated soil, comprising an aqueous suspension in which fine metal particles and amino acids are dispersed in water. 2. The soil purifying agent according to claim 1, wherein the metal fine particles are iron fine particles. 3. The metal fine particles have an average particle size of 0.1-5.
The soil purifying agent according to claim 1 or 2, which is in a range of 00 µm. 4. The content of the metal fine particles in the whole aqueous suspension is in the range of 0.1 to 40% by mass, and the content of the amino acid in the whole aqueous suspension is 0.04% by mass.
The soil purifying agent according to any one of claims 1 to 3, which is in a range of 1 to 5% by mass. 5. The soil purifying agent according to claim 1, wherein the pH of the aqueous suspension is in the range of 6 to 13. 6. The contaminant of the contaminated soil is an organic halide and / or hexavalent chromium.
5. The soil purifying agent according to any one of 5. 7. A soil purification method comprising permeating contaminated soil with the soil purification agent according to claim 1. 8. The soil purification method according to claim 7, wherein the contaminants in the contaminated soil are organic halides and / or hexavalent chromium. 9. The soil purification method according to claim 7, wherein the injection of the soil purification agent is performed by spraying the soil purification agent on substantially the entire surface of the soil. 10. An injection pipe for supplying the soil purifying agent according to claim 1 is inserted into the contaminated soil, and the soil purifying agent is injected into the injection pipe. Becomes a soil purification method. 11. The soil purification method according to claim 10, wherein the contaminant in the contaminated soil is an organic halide. 12. The soil purification method according to claim 10, wherein the surface of the contaminated soil is further covered with a sheet.