JP2003236519A - Contaminated soil decontaminating material for soil contaminated with organic halogen compound and decontaminating method of contaminated soil using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem of an unstable factor in a microbiological method, low working efficiency in a vacuum extraction method and large consumption of limestone in a method for blending soil with slaked lime and/or calcium aluminate powder in a method for decontaminating soil contaminated with organic halogen compounds. <P>SOLUTION: A decontaminating material for the soil contaminated with the organic halogen compounds is characterized by containing calcium aluminates and water. A method for injecting the contaminated soil decontaminating material into ground is also provided. Since organic halogen compounds such as fluorocarbon, trichloroethylene, carbon tetrachloride, tetrachloroethylene and methylene chloride can be effectively decontaminated by a small quantity of calcium aluminates, this method is effective for decontaminating the soil widely contaminated with a solvent of dry cleaning, a dewaxing agent of electronic parts and metallic products, a refrigerant or the like. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polluted soil purification material and a purification method therefor capable of effectively purifying soil polluted mainly with organic halogen compounds and the like. The parts and% used in the present invention are based on mass unless otherwise specified.

[0002]

2. Description of the Related Art Organic halogen compounds such as trichloroethylene, tetrachloroethylene, freon, and methylene chloride are widely used as solvents for dry cleaning, degreasing agents for electronic parts and metal products, and refrigerants.

However, it is said that these organic halogen compounds not only remain in the soil but also cause pollution of drinking water through groundwater, rivers, well water and the like. Since these organohalogen compounds are suspected to be carcinogenic and seriously affect human health, it has been desired to clean soil contaminated with the organohalogen compounds.

Therefore, microorganisms capable of decomposing organochlorine compounds (Saccharomyces) in polluted soil,
A method of injecting a liquid containing Hansenula, Candida, etc. (hereinafter referred to as “microorganism method”)
-277045), a method for purifying contaminated soil by a vacuum extraction method (hereinafter referred to as "vacuum extraction method", Japanese Patent Laid-Open No. 2000-2
No. 02425), a method of mixing powder of slaked lime and / or calcium aluminate with contaminated soil (JP-A-10-427).
No. 32) is proposed.

However, in the microbial method, there are many unclear points about the effects of microorganisms on the human body and the environment, and in addition to temperature,
There are instability factors such as humidity and microbial breeding conditions, the vacuum extraction method is inefficient in treating a large amount of soil, and there is a problem that the effect is weak for soil with low water permeability. In the method of mixing powder of calcium aluminate with contaminated soil, since a large amount of alkaline slaked lime and / or powder of calcium aluminate of 150 kg per 1 m ³ of soil is used, there is concern about environmental impact. It Further, the raw material of slaked lime and calcium aluminate is limestone, and it is not preferable to consume a large amount of limestone, which is a limited and valuable resource, for purposes other than the cement raw material.

As a result of intensive studies in view of such problems, the present inventors have solved the problems of unstable factors in the microbial method and inefficiency in the vacuum extraction method by using a specific contaminated soil purification material. At the same time, they have found that they can solve the problems of environmental impact and the large consumption of limestone in the method of mixing powder of slaked lime and / or calcium aluminate with soil, and have completed the present invention.

[0007]

That is, the present invention is a polluted soil remediation material for soil contaminated with organohalogen compounds, characterized by containing calcium aluminates and water and containing sulfate. The method for purifying contaminated soil is the method for purifying contaminated soil, which is the method for purifying contaminated soil containing a retarder, wherein the method for purifying contaminated soil comprises injecting the contaminated soil purification material into the ground.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.

The polluted soil purifying material purifies polluted soil mainly composed of organic halogen compounds. Examples of the organic halogen compound include trichloroethylene, tetrachloroethylene, trans-1,2-dichloroethylene, cis-1,2-dichloroethylene, carbon tetrachloride, chloroethane, methylene chloride, chloroform, vinyl chloride monomer, 1,1-dichloroethane, 1,2. -Dichloroethane, 1,2-dichloropropane, dichlorobromoethylene, 1,1,1-trichloroethane, PCB,
And organic chlorine compounds such as dioxins, bromodichloromethane, chlorodibromomethane, and organic bromine compounds such as bromoform, organic iodine compounds such as iodoform,
Examples thereof include organic fluorine compounds such as fluorinate and liquid fluorocarbon compounds.

The polluted soil purification material of the present invention has a high efficiency of purification of polluted soil when the pollutant is one or more of organic chlorine compounds.

The calcium aluminates of the present invention are
Mix the raw material containing calcia with the raw material containing alumina.
Heat treatment such as firing in a kiln or melting in an electric furnace.
Is a compound obtained by CaO and Al₂O₃And
As a component, CaO is C, Al ₂O₃Where A is chemistry
Formula C_mA_nOf the oxides represented by (m and n are positive real numbers), water
It is a general term for substances that have a Japanese activity and includes crystalline and amorphous substances.
Although both exist, for example, in a crystalline compound, C
₃A, C₁₂A₇, CA, etc. are known.

CaO in calcium aluminates
If the content is less than 40%, the composition is similar to that of alumina cement.

Further, a part of these calcium aluminates is an alkali metal oxide, an alkaline earth metal oxide, silicon oxide, titanium oxide, iron oxide, an alkali metal halogen compound, an alkaline earth metal halogen compound, an alkali metal. It is also possible to use a solid solution in which a sulfate, an alkaline earth metal sulfate or the like is substituted.

Among the calcium aluminates, both crystalline and amorphous can be used, but amorphous is preferable because the polluted soil can be purified with a small amount of the polluted soil purifying material.

The CaO content and the Al ₂ O ₃ content in the calcium aluminates are such that the CaO content is 5 to 65%, the Al
₂ O ₃ content of 95 to 35% is preferable, CaO content of 40
It is more preferable that the Al ₂ O ₃ content is 60 to 50% at 50%. If the CaO content or the Al ₂ O ₃ content is outside this range, the efficiency of cleaning the contaminated soil may decrease.

The specific surface area of calcium aluminates is
A large amount is preferable because it can be purified with a small amount of soil purification material. The Blaine specific surface area of calcium aluminates is preferably 3,000 cm ² / g or more,
cm ² / g or more is more preferable, 8,000 to 10,000
Most preferred is 0 cm ² / g. If it is less than 3,000 cm ² / g, the contaminated soil may not be sufficiently purified.
This is because if it exceeds 000 cm ² / g, crushing power is required, which causes a cost increase.

Further, in the present invention, it is preferable to use a sulfate together with calcium aluminate in order to increase the efficiency of soil purification.

The sulfates of the present invention include alums,
Hydrated aluminum sulfate such as hexahydrate, 10-hydrate, 16-hydrate and 18-hydrate, anhydrous aluminum sulfate, hydrous calcium sulfate such as 0.5-hydrate and 2-hydrate, anhydrous calcium sulfate, 7-hydrate and 10-hydrate Hydrous sodium sulfate such as hydrate, anhydrous sodium sulfate, monohydrate, hexahydrate, and hydrous magnesium sulfate such as heptahydrate, anhydrous magnesium sulfate, trihydrate, 6
Hydrous salt, 7-hydrated salt, 7.5-hydrated salt, 9-hydrated salt, 10-hydrated salt, and 1
Examples include hydrous iron sulfate such as dihydrate, anhydrous iron sulfate (II), anhydrous iron sulfate such as anhydrous iron sulfate (III), lithium sulfate monohydrate, and anhydrous lithium sulfate. Among these, anhydrous aluminum sulfate and aluminum sulfate 18-hydrate are preferable in terms of soil purification efficiency.

The amount of sulfate to be used is preferably 50 to 300 parts per 100 parts of calcium aluminate, 10
0 to 200 parts is more preferable. If it is less than 50 parts, the efficiency of soil purification may be reduced, and if it exceeds 300 parts, the sulfate may not be sufficiently dissolved in water. .

The mixing ratio of water and calcium aluminate changes depending on the concentration of pollutants and the method of injecting into the soil. For example, a method of injecting a small amount of the present polluted soil purification material having a high concentration of calcium aluminate into the soil, There are various spraying forms such as a method of spraying a large amount of this polluted soil purification material with low calcium aluminate concentration, and the optimum value differs depending on the soil, so the mixing ratio cannot be uniquely determined, but in general Is preferably 100 to 100,000 parts of water per 100 parts of calcium aluminate.
0 to 10,000 parts is more preferable.

A retarder may be used in combination for the purpose of sufficiently permeating the mixture of the polluted soil purifying material and water into the soil.

Examples of the retarder include oxycarboxylic acids such as citric acid, tartaric acid, gluconic acid and malic acid,
Examples thereof include oxycarboxylic acid salts which are salts of these oxycarboxylic acids. These retarders may be used alone or in combination of two or more. Among these, citric acid and salts of citric acid are preferable, and citric acid and sodium citrate are more preferable, because of their large delaying effect.

The amount of the retarder used cannot be uniquely determined because the effect varies depending on the type, but it is preferably 0.01 to 10 parts, and preferably 0.05 to 100 parts with respect to 100 parts of calcium aluminate. 5 parts is more preferred. If it is less than 0.01 part, the retarding effect may be small, and if it is added in excess of 10 parts, not only the efficiency of soil purification decreases but it is uneconomical.

The amount of the polluted soil purification material used is not particularly limited and cannot be uniquely determined because it varies depending on the penetration depth of the organic halogen compound, the type of soil, etc.
when m contaminants during ³ is contained about 10 to 100 g, to the soil 1 m ^3, preferably 0.1~1,000g calcium aluminates terms, 10 to 100 g
Is more preferable. If it is less than 0.1 g, the efficiency of purification of contaminated soil may decrease, and if it exceeds 1,000 g, the efficiency of purification of contaminated soil does not change, which is not economically preferable.

As a method of mixing the present contaminated soil purification material with soil, in addition to a method of mixing the soil and the present contaminated soil purification material with a mixer, pump injection, jet injection, or simply spraying on the soil surface, And spraying with a sprinkler, etc., but an injection method by pressurization such as pump injection and jet injection is preferable.

[0026]

EXAMPLES The present invention will be further described below with reference to experimental examples of the present invention, but the present invention is not limited thereto.

Experimental Example 1 Trichlorethylene was used as a pollutant, and a contaminated soil was prepared so that the amount of trichlorethylene in the soil would be 50 mg / liter. Next, calcium aluminates 10
0 parts and 2,000 parts of water were mixed to prepare a polluted soil purification material.

Subsequently, the mixture was pumped into 1 m ³ of the contaminated soil so that the amount of the contaminated soil purification material shown in Table 1 was obtained. After standing for 1 day, the amount of trichlorethylene in the soil was measured. The results are also shown in Table 1.

<Materials used> Calcium aluminates a: 12CaO · 7Al ₂ O ₃
Amorphous corresponding to the composition, Blaine specific surface area of 8,500c
m ² / g, synthetic product. Calcium aluminates a: CaO.Al ₂ O ₃ crystalline, Blaine specific surface area of 8,500 cm ² / g, synthetic product. Calcium aluminates C: 8CaO ・ Na ₂ O ・ 3
Amorphous corresponding to Al ₂ O ₃ composition, Blaine specific surface area 8,
500 cm ² / g, synthetic product. Trichlorethylene: Wako Pure Chemical Industries, Ltd. first-grade reagent

<Test method> Trichlorethylene amount: Japanese Industrial Standard K0125, 5.1, 5.
Follow the method specified in 2, 5.3.1, 5.4.1 or 5.5.

[0031]

[Table 1]

Experimental Example 2 Carbon tetrachloride was used as a pollutant, and the concentration of carbon tetrachloride was 30%.
The same procedure as in Experimental Example 1 was carried out except that mg / liter was used. The results are also shown in Table 2.

<Materials used> Soil: Himekawa, Niigata Prefecture Carbon tetrachloride: Wako Pure Chemical Industries, Ltd. first-grade reagent

<Test method> Carbon tetrachloride amount: 5.1, 5.2, 5.3 of Japanese Industrial Standard K0125.
Follow the method specified in 1, 5.4.1 or 5.5.

[0035]

[Table 2]

Experimental Example 3 100 parts of calcium aluminate, sulphate of the amounts shown in Table 3 and 2,000 parts of water were mixed to prepare a polluted soil purifying material, and the amount of calcium aluminate used was 1 m ^{3 of} soil. The same procedure as in Experimental Example 1 was carried out except that 100 g of the solution was pumped. The results are also shown in Table 3.

[0037]

[Table 3]

Experimental Example 4 As a pollutant for polluted soil, calcium aluminate 10
0 part, 2,000 parts of water, 150 parts of sulfate shown in Table 4 and retarder A
The same procedure as in Experimental Example 1 was carried out except that the soil purifying material consisting of 1 part was used in the amount shown in Table 2. The results are also shown in Table 4.

<Material used> Sulfate α: Aluminum sulfate 18-hydrate, average particle diameter 0.3 m
m, commercial product. Sulfate β: anhydrous calcium sulfate, average particle size 0.3 mm, commercial product. Retarder A: citric acid, a commercial product.

[0040]

[Table 4]

Experimental Example 5 Carbon tetrachloride was used as a pollutant, and a contaminated soil was prepared so that the amount of carbon tetrachloride in 1 m ^{3 of} soil was 30 g / m ³ .
Next, 100 parts of calcium aluminate, sulfate α150
Parts and the retardant A1 part were used in the same manner as in Experimental Example 1 except that the amount of the contaminated soil purifying material shown in Table 5 was used. The results are also shown in Table 5.

[0042]

[Table 5]

[0043]

As described above, by using the polluted soil remediation material, a small amount of calcium aluminates can be used to effectively bring out organic halogen compounds such as CFCs, trichloroethylene, carbon tetrachloride, tetrachloroethylene, and methylene chloride. Because it can be purified, it is a solvent for dry cleaning,
In addition, it is effective for cleaning soil contaminated over a wide range with degreasing agents for electronic parts and metal products, refrigerants and the like.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 17/14 B09B 3/00 ZAB // C09K 101: 00 F term (reference) 4D004 AA41 AB05 AB06 AB08 AC07 CA34 CC03 CC11 CC15 4H026 AA01 AA03 AA07 AB04

Claims (4)

[Claims] 1. A soil remediation material for soil contaminated with organic halogen compounds, which comprises calcium aluminates and water. 2. The polluted soil remediation material according to claim 1, which contains a sulfate. 3. The polluted soil remediation material according to claim 1, which contains a retarder. 4. A method for purifying contaminated soil, comprising injecting the contaminated soil purifying material according to claim 1 into the ground.