JPH09276836A - Cassette style reactor type polluted soil purifying apparatus and soil purifying method using the apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for purifying soil polluted by volatile pollutants which utilizes the merits of a vacuum extraction method and a microbial purification method, is simple, and does not increase reclamation costs. SOLUTION: A pile in which a cassette style reactor 15 having a reaction area holding microorganisms which decompose volatile pollutants is set is installed so that its tip part reaches the polluted region in soil 18, and by sucking from its exhaust port 11, the volatile pollutants in the polluted region 18 are introduced from a suction port formed at the tip part of the pile into the reaction area in the pile to be purified by decomposition.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for cleaning contaminated soil and an apparatus used for the method.

[0002]

2. Description of the Related Art The rapid progress of science and technology in recent years has produced a large amount of chemical substances and chemical products. Many of these pollute nature as they gradually accumulate in the environment. Above all, considering that the land area, where human beings live, is most likely to be affected by human pollution and environmental water circulates,
Environmental pollution in the land area is a serious problem that spreads to the global level. Well-known soil (terrestrial) pollutants include trichlorethylene (TCE), tetrachlorethylene (PCE), organic chlorine compounds such as dioxins, aromatic compounds such as toluene, xylene, benzene, and gasoline. Examples include fuel. Among them, organochlorine compounds such as trichlorethylene and tetrachloroethylene are once used in large amounts in the cleaning of precision parts and dry cleaning, and their leakage reveals large-scale contamination of soil and groundwater. Furthermore, since teratogenicity and carcinogenicity of these organochlorine compounds have been pointed out and it has been found that they have a very serious impact on the living world, it is urgently necessary not only to cut off pollution sources but also to clean soils and groundwaters where pollution has already spread. It has become a problem to be solved.

As a method for cleaning soil contaminated with organic chlorine compounds, a method of excavating the contaminated soil and heat treatment, a method of vacuum extraction from the contaminated soil, or a method of injecting a microorganism capable of decomposing the pollutant, etc. Is mentioned.

Although the heat treatment method can almost completely remove pollutants from soil, soil excavation is necessary, so that purification treatment under a building is difficult, and the cost required for excavation and heat treatment is high. Since it is huge, it is difficult to apply it to the purification of a wide range of contaminated soil. Further, since the organic chlorine compound that is heated and evaporated from the soil causes air pollution, it is necessary to adsorb it on activated carbon or the like to recover it, but it is necessary to further treat this used activated carbon.

On the other hand, the vacuum extraction method and the microbial utilization method are inexpensive and simple because there is no need to excavate contaminated soil, and repair work is carried out even on soil where the ground surface is being used in a building or the like while using the ground surface. There is an advantage that can be done. But,
The vacuum extraction method has a low efficiency of removing low-concentration organic chlorine compounds of several ppm or less, and it is necessary to treat the recovered organic chlorine compounds again as in the heat treatment. Therefore, Japanese Patent Laid-Open Publication No. 7-185252 proposes a compact ground facility by adsorbing the sucked gas to be treated with activated carbon and using a fluidized bed to retreat the activated carbon. Is still necessary. On the other hand, the method for microbial purification is divided into a method of using the degrading microorganisms of the soil originally inhabiting the soil and a method of using an exogenous degrading microorganism not originally inhabiting the soil. In the former case,
Nutrients, inducers, oxygen to enhance decomposition activity,
Purification is performed by injecting bacteria activating substances such as growth stimulants into the soil. Specifically, as a report isolated as a microorganism degrading an organochlorine compound, for example, a TCE-degrading bacterium, Welchia alkenophila sero 5 (USP 4877736, ATCC
53570), Welchia alkenophila sero 33 (USP 4877736,
ATCC 53571), Methylocystis sp. Strain M (Agric. B
iol. Chem., 53, 2903 (1989), Biosci. Biotech. Bioc
hem., 56, 486 (1992), ibid. 56, 736 (1992)), Methylosi
nus trichosprium OB3b (Am. Chem. Soc. Natl. Meet.
Dev. Environ. Microbiol., 29, 365 (1989), Appl. En
viron. Microbiol., 55, 3155 (1989), Appl. Biochem.
Biotechnol., 28, 877 (1991), JP 02-92274 A, JP 03-292970 A), Methylomonas sp.MM2
(Appl. Environ. Microbiol., 57, 236 (1991)), Alc
aligenes denitrificans ssp.xylosoxidans JE75 (Arc
h. microbiol., 154, 410 (1990)), Alcaligenes eutr
ophus JMP134 (Appl. Environ. Microbiol., 56, 1179
(1990)) Mycobacterium vaccae JOB5 (J. Gen. Microbi
ol., 82, 163 (1974), Appl. Environ. Microbiol., 5
4, 2960 (1989), ATCC 29678), Pseudomonas putida B
H (Sewer Society Journal, 24, 27 (1987)), Acinetobactor sp.
strain G4 (Appl. Environ. Microbiol., 52, 383 (198
6), 53, 949 (1987), 54, 951 (1989), 56, 279.
(1990), 57, 193 (1991), USP 4925802, ATCC 5361
7, this strain was originally classified as Pseudomonas cepacia, but was changed to Acinetobactor sp.), Pseudomonas me
ndocina KR-1 (Bio / Technol., 7, 282 (1989)), Pseudo
monas putidaF1 (Appl. Environ. Microbiol., 54, 1703
(1988), ibid. 54, 2578 (1988)), Pseudomonas fluoresce
ns PFL12 (Appl. Environ. Microbiol., 54, 2578 (198
8)), Pseudomonas putida KWI-9 (JP 06-70753 A), Pseudomonas cepacia KK01 (JP 06-227769 A), Nitrosomonas europaea (Appl. Environ. Micr)
obiol., 56, 1169 (1990)), Lactobacillus vaginalis
sp.nov (Int. J. Syst. Bacteriol., 39, 368 (1989),
ATCC 49540) etc. are known. All of these degrading bacteria require chemical substances such as aromatic compounds and methane as degrading inducers for degrading TCE. In the latter case, in addition to injecting foreign microorganisms into the soil,
Inject a fungal activator to enhance the decomposition activity. At this time, it is economically desirable to inject a small amount of microorganisms or chemical substances as much as possible into the intended repair area, thereby decomposing pollutants and performing soil purification. For this reason, the microbial purification treatment is carried out by injecting into the soil a sufficient amount of the chemical liquid to fill the soil voids in the repair region, and there is a disadvantage that a huge amount of the chemical liquid is required for a wide repair region.

[0006] In any of the microorganism utilization methods, the injected microorganisms and microbial activator are contained in a certain area, and the decomposing bacteria grown in the soil after the treatment work and the microbial active substance remaining in the soil are recovered. However, there is a problem of secondary pollution of soil due to these problems.

Thus, although the vacuum extraction method and the microbial purification method have advantages over the heat treatment method, they still have points to be improved in order to perform more efficient treatment.

Therefore, in JP-A-6-254537 and JP-A-7-112176, a vacuum extraction method and a microbial purification method are combined to vacuum suck air or groundwater contaminated with organic chlorine compounds in contaminated soil. A method has been proposed in which a bioreactor on the ground is introduced and decomposed in the bioreactor. This is because the microbial decomposition of the organic chlorine compound eliminates the need for reprocessing of the recovered organic chlorine compound, which is a drawback of the vacuum extraction method, and the installation of a microbial decomposition reactor is a drawback of the microbial purification method. It aims to solve injection problems and cross-contamination problems.

[0009]

However, the above-mentioned method combining the vacuum extraction method and the microbial purification method requires an on-ground facility including a microbial decomposition reactor, and has the same problem as the vacuum extraction method in this respect. There is no change in being there. Also, since the decomposition activity of microorganisms changes depending on the temperature, in order to obtain a certain decomposition efficiency, a device for maintaining the microbial reactor at a constant temperature and equipment for protecting it from the outside temperature are required. There is also the problem that ground equipment will be larger than in some cases.

That is, since these methods require large-scale equipment, the construction, operation, and maintenance costs of the above-ground equipment are required, which generally increases the repair processing cost, and the above-ground equipment is huge. In that case, even the advantage of performing the restoration while utilizing the shape of the soil and the ground surface, which is an advantage over the heat treatment method of the vacuum extraction method and the microbial purification method, may be lost.

An object of the present invention is to provide a method for purifying soil contaminated with volatile pollutants, which utilizes the advantages of the vacuum extraction method and the microbial purification method, is simpler, and does not increase the cost of remediation treatment. Especially.

[0012]

In the method for purifying contaminated soil of the present invention which can achieve the above object, volatile pollutants in the soil are detachably arranged in a pile-shaped body installed in the soil. It is characterized in that it is sucked and induced to decompose in a reaction region holding a microorganism capable of decomposing volatile pollutants in the cassette type reactor.

A purifying apparatus suitable for use in this method is a hollow tubular part, a suction port to the hollow part, a pile-shaped body having an exhaust port from the hollow part, and openings at both ends to allow ventilation. It consists of a combination with a cassette type reactor provided with a reaction region for purification for holding microorganisms capable of decomposing volatile pollutants in a partitioned tubular body, and the cassette type reactor in the hollow tubular portion of the pile-shaped body. The inner wall of the hollow portion and the outer wall of the cassette-type reactor can be detachably inserted in a sealed state.

The pile-shaped body has an intake port to the reaction region at its tip in the direction of driving into the soil,
It is preferable that the rear end portion has an exhaust port for sucking the reaction region.

According to the present invention, when a volatile pollutant in contaminated soil is vacuum-suctioned, a cassette (cleaning cassette type reactor) having a reaction region for holding decomposing microorganisms from the surface of the contaminated soil is provided. The pile-shaped body that is detachably mounted is driven into the contaminated area, and the inside of the contaminated area is decompressed, and the volatile pollutants in the contaminated area are sucked into the reaction area and decomposed to contaminate the contaminated soil. Purification is performed. In the present invention, the contaminated region is a region containing the pollutant to be decomposed and a region in which the pollutant can be introduced into the purification device by suction, for example, the vicinity of the region containing the pollutant.

According to the present invention, it is not necessary to separately provide a reactor on the ground, and the effective space of the ground space is not damaged. In other words, since only the pile-shaped exhaust port is exposed on the surface of the contaminated soil, the ground is not occupied by a large-scale treatment device. For example, if a tubular body is driven under the floor of the building, it is possible to perform the processing work while using the building without changing the appearance on the ground.

Further, since the temperature inside the soil does not change much as compared with the air temperature and is in the range of 15 to 25 ° C. which is the optimum temperature of soil microorganisms, special heating, cooling and heat retaining equipment should be used. It can easily provide a constant temperature microbial environment throughout the year. That is, since the temperature conditions in the soil are almost constant, it is possible to reduce the cost for equipment and operation required for temperature control of the reactor.

Further, it is possible to stably maintain a desired microorganism having a strong decomposition activity in the reaction region formed in the pile shape, and a more effective purification treatment can be achieved.
Moreover, the piles suck the gas phase in the soil, and the exhaust air is discharged toward the ground.Therefore, there is a concern that the chemicals in the piles and the pollutant-degrading microorganisms that have proliferated leak to the outside and cause secondary pollution. Moreover, the post-treatment of the treatment work only needs to remove the piles.

Further, since the reaction area in the purifying device is formed in the detachable cassette, it is possible to exchange the reaction area or remove only the reaction area. Furthermore, by using a plurality of cassettes and differently degrading the substances to be decomposed by the microorganisms held in each cassette, it becomes possible to decompose a plurality of types of contaminants.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION In order to form a reaction region containing degrading microorganisms in a tubular portion of a pile, for example, a method of holding the degrading microorganisms by immobilizing them or attaching them to an appropriate carrier is used. It can be used suitably. The method using such a carrier is also suitable in the case where a nutrient, an inducer, a growth stimulant or the like, which is a substance that enhances the decomposing activity of the degrading microorganism, is retained in the reaction region.

As a carrier for holding microorganisms, that is, for immobilizing and / or adhering, microorganisms have excellent ability to retain microorganisms,
Those that do not impair breathability are desirable. For example, various microbial carriers that have been used in bioreactors conventionally used in the pharmaceutical industry, food industry, wastewater treatment system, etc. can be used as materials that provide a habitat for microorganisms. More specifically, porous glass, ceramics, metal oxides, activated carbon, kaolinite, bentonite, zeolite, silica gel, alumina, an endless particulate carrier such as anthracite, starch, agar, chitin, chitosan, polyvinyl alcohol, alginic acid. Gel carriers such as polyacrylamide, carrageenan, agarose and gelatin, polymer carriers such as ion exchangeable cellulose, ion exchange resins, cellulose derivatives, glutaraldehyde, polyacrylic acid, polyurethane and polyester,
Examples include natural products carriers such as grain straw, sawdust, rice bran, okara, sugar cane dregs, and crab and shrimp shells.

Further, when the purifying ability of the pile-shaped body falls below a certain level, the purifying ability can be easily recovered only by replacing the cassette type reactor with a substance having a high decomposition activity.

In the present invention, a plurality of types of degrading microorganisms may be placed in the reactor, or a plurality of reactors may be connected in series and inserted into the apparatus. Not only is it possible to utilize the degrading activity of multiple types of microorganisms, it is possible to deal with complex pollutants of two or more types.

The microorganisms that can be used in the present invention include bacteria, microalgae, molds, actinomycetes, and protozoa, and particularly industrially useful are bacteria. As such a microorganism, the microorganisms having the ability to decompose various organic chlorine compounds mentioned in the section of the prior art can be used, and further, the J1 strain and J
The M1 strain can be mentioned as a suitable microorganism. Especially,
The J1 strain and the JM1 strain are isolated from soil and have high applicability to soil and are suitable for the present invention.

The J1 and JM1 strains are obtained from the Ministry of International Trade and Industry, the Agency of Industrial Science and Technology, and the Institute of Biotechnology and Industrial Technology (1 east of Tsukuba City, Ibaraki Prefecture).
It has been deposited as an international deposit under the Budapest Treaty. The deposit numbers and dates of these deposits are as follows. J1; FERM BP-5102; Deposit Date: May 25, 1994 (transferred from FERMP-14332 to International Deposit on May 17, 1995) JM1; FERM BP-5352; Deposit Date: 1995
January 10, (from FERMP-14727 to 1995 January
Transferred to international deposit on February 22) The JM1 strain was obtained by mutating the J1 strain that oxidizes aromatic compounds and organic chlorine compounds with oxygenase, and expresses oxygenase constitutively without an inducer. The mycological properties of the J1 strain and the JM1 strain, which are mutants, are as follows. Bacteriological characteristics of J1 strain and JM1 strain; Gram stainability and morphology: Growth in each medium of Gram-negative bacilli BHIA: Good growth MacConkey: Viable Colony color: Cream Optimal temperature: 25 ° C> 30 ° C> 35 ° C motility: negative (semi-fluid medium) TSI (slant / butt): alkali / alkali, H ₂ S (-) oxidase: positive (weak) catalase: fermentation glucose positive sugar: negative sucrose: negative raffinose: negative galactose: Negative Maltose: Negative Urease: Positive Esculin hydrolysis (β-glucosidase): Positive Nitrate reduction: Negative Indole production: Negative Glucose acidification: Negative Arginine dihydrolase: Negative Gelatin hydrolysis (protease): Negative β-galactosidase: Negative Assimilation of: glucose Negative L-arabinose: Negative D-mannose: Negative D- Mannitol: Negative N-Acetyl-D-glucosamine: Negative Maltose: Negative Potassium gluconate: Negative n-Capric acid: Positive Adipic acid: Negative dl-Malic acid: Positive Quen Sodium acid: positive Phenyl acetate: negative Therefore, at the time of deposit, these were tentatively classified as Corynebacterium sp., But thereafter, the identification labels of the deposited strains were changed to J1 and JM1 strains.

Hereinafter, an example of the present invention will be described in detail along with specific working steps. First, one or more hollow piles are driven into the surface of the contaminated soil to be treated, and the inside of the piles are decomposed microorganisms and, if necessary, nutrients such as citric acid for growing the microorganisms and decomposition. Degradation bacterium solution containing one or more of an inducer expressing activity, a growth stimulant composed of fine particles such as bentonite stimulating the growth of microorganisms, and / or a carrier on which the degradation bacterium solution is immobilized or /
And, a detachable reactor filled with a carrier to which the degrading bacteria solution is attached is inserted.

After that, after preventing the ground air from flowing into the pile body from the upper portion of the pile body, a vacuum pump is attached to the upper portion of the pile body to suck the underground air in the lower portion of the pile body. However, if the moving speed is set too high, the contact time between pollutants and soil microorganisms will be too short, and the pollutants that could not be decomposed into the air discharged from the exhaust port will remain. It is necessary to control the suction amount of the vacuum pump so that the substance concentration is always below the target value. In addition, the decomposition activity of soil microorganisms may be low for several days after the start of inhalation, and therefore the amount of inhalation must be reduced to control the concentration of pollutants in the exhaust air below the target value.

After the purification work is carried out in this way, if the pile-shaped body is removed together with the cassette-type reactor inside, secondary contamination due to infiltration of the inducer or the like from the pile-shaped body due to infiltration of rainwater or the like is a problem. Never be. Also,
Even if only the vacuum pump and the cassette type reactor above the pile shape are collected and the pile body is left in the ground, there is no problem with secondary pollution.

To install the purification apparatus of the present invention in soil, hollow piles, for example, piles are first driven into the ground,
In addition to the method of inserting the cassette type reactor into the pile after removing the soil that has entered the inside, various methods such as driving the cassette type reactor in the pile in the ground in advance. Can be appropriately selected.

[0030]

EXAMPLES The present invention will be described below with reference to examples, but these do not limit the scope of the present invention. Example 1 Two glass columns having an inner diameter of 30 mm and a length of 1000 mm and having both ends processed with screw holes, and five screw lids were prepared. Teflon-coated rubber packing was placed inside the four screw lids, and a needle hole was opened in the center of the lid and the packing, and a 0.7 mm diameter silicon tube was passed through. The remaining one was a temporary lid.

The composition of the packing material in the column is as follows. (Per column) 1) Medium + inducer: 200 ml Composition: ・ Na ₂ HPO ₄ 12.4 g / l ・ KH ₂ PO ₄ 6.0 g / l ・ NaCl 1.0 g / l ・ NH ₄ Cl 2.0 g / l ・Sodium citrate 10.0 g / l-Phenol 0.3 g / l 2) Decomposing bacterium dispersion liquid (J1 strain: bacterial count 2 × 10 ⁸ cells / ml): 2.0
ml 3) Activated carbon (particle size: about 5 mm): 350 g (about 860 ml) The above-mentioned packing material was filled in a glass column having a temporary cover at the lower end, and a cap with a Teflon tube passed through at the upper end. Then, the temporary lid at the lower end of the column was changed to a lid through which a Teflon tube was passed. Fix the fabricated column on a tripod in an upright position,
Pump (FURUE SCIENCE Co.Ltd Roller pump RP-MRF
Connected to 1). In addition, a tank containing clean water was connected to the air intake port in order to avoid contamination of bacteria from the outside and change of the liquid amount. The device is shown in FIG. In this state, it was left at room temperature for 48 hours while sending air at 2 ml / min. (Growth period of degrading bacteria) Next, add 10 ml to a vial with a capacity of 27 ml.
A reservoir tank containing 15 ml of a 00 ppm trichlorethylene aqueous solution was prepared, a lid with a Teflon-coated rubber packing was attached, two needle holes were further provided in the lid, and two Teflon tubes were passed through.

A TCE reservoir tank was connected to the column left for 48 hours as shown in FIG. 2, and air containing TCE vapor was sent at 3 ml / min for 24 hours. The air discharged from the upper end of the column was sampled every hour 30 minutes after the air containing the TCE vapor was sent, and the TCE concentration was measured by a gas chromatograph (detector: FID). The TCE concentration in the air layer is
It was below the detection limit throughout. After the TCE decomposition experiment was completed, the packing material in the column was recovered, and the amount of TCE adsorbed in the activated carbon was measured by the purge trap method. As a result, it was not detected.

Comparative Example 1 The same packing material as in Example 1 (except decomposing bacteria) was packed in a glass column, and the same apparatus as in Example 1 was assembled. This column was fixed to a tripod in the same manner as in Example 1, and after sending air at 2 ml / min for 48 hours at room temperature, a TCE reservoir tank was connected and a TCE decomposition experiment was conducted for 24 hours. TCE
Was measured in the same manner as in Example 1. The TCE concentration in the air layer is
It was below the detection limit throughout. After the TCE decomposition experiment was completed, the packing material in the column was collected and the amount of TCE adsorbed in the activated carbon was measured by the purge trap method. As a result, an average value of about 40 μg / g (dry activated carbon) was detected. Was done. This corresponds to about 93% of the amount of TCE loaded in the column.

Example 2 An artificial artificial soil for experiment was prepared in the experimental tank shown in FIG. 3 (internal dimension: width 3 m × depth 3 m × depth 3 m, inner surface coated with vinyl ester).

Specifically, first, a gravel layer (average particle size: 3 cm) was laid down at the bottom of the experimental tank to a thickness of about 30 cm. Next, as a fine sand layer (average water content ratio: 13%), four spreading layers (average wet pressure density: 1.8 g / cm ³ ) having a thickness of about 60 cm were prepared. Furthermore, a gravel layer was formed on the uppermost part in the same manner as the lowermost part to a thickness of about 30 cm, and used as an experimental artificial soil. During the preparation of the artificial soil, a stainless pipe having an inner diameter of 50 mm was installed so as to reach the lower gravel layer.

Next, a stainless steel pipe having an inner diameter of 200 mm and a length of 3 m was installed in the artificial soil (from the upper surface of the artificial soil).
2.4m) and removed the soil inside. A cassette type reactor for purification was set inside the stainless pipe after soil removal as shown in FIG. The size of the reactor cassette and the composition of the packing material in the cassette are as follows. Reactor cassette: 150 mm inner diameter x 2000 mm length Filler volume: 35 liters 1) Medium + inducer: 9.2 liters Composition: ・ Na ₂ HPO ₄ 12.4 g / l ・ KH ₂ PO ₄ 6.0 g / l ・ NaCl 1.0 g / l・ NH ₄ Cl 2.0 g / l ・ Sodium citrate 10.0 g / l ・ Phenol 0.3 g / l 2) Dispersion solution of degrading bacteria (J1 strain, number of bacteria: 2 × 10 ⁸ cells / ml): 100
ml 3) Activated carbon (particle size: about 5 mm): 14.2 kg After installing the above purification device, a lid was made of concrete on the top of the experimental tank. This is because the test tank was sealed, and urethane resin was further applied to the upper layer of the concrete lid to completely seal it.

When this lid was produced, two stainless pipes (a valve can be installed at the upper end, flow rate can be adjusted, and sealed, inner diameter: 50 mm) were installed as air intakes so as to reach the upper gravel layer. Next, a vacuum pump was installed above the installed purification device to prepare for the experiment.

After leaving the reactor cassette for 24 hours (soil temperature 16 ° C.), 50 l of a trichlorethylene aqueous solution having a concentration of 700 ppm as a pollutant was injected into the lower gravel layer of the experimental soil using the stainless pipe installed at the time of soil preparation. . (TCE amount: 35g) After leaving for 5 hours, operate the vacuum pump (open the air intake port), and thereafter periodically perform the TCE concentration in each air of the purification device upper exhaust port, the experimental tank lower gravel layer, and the purification device The amount of air exhausted from the upper exhaust port was recorded. FIG. 5 shows the measurement results. The TCE concentration was measured using a detector tube.

After the end of the experiment, the purifier was removed from the experimental tank, and the soil around the bottom of the purifier was collected. As a result of measuring the number of bacteria in the collected soil using the dilution plate method (using 2 × YT agar medium), the degrading bacteria (J1 strain) introduced into the purification device was not detected. In addition, phenol and sodium citrate were not detected, confirming that there was no secondary pollution of the environment due to the purification operation. 2 × YT agar medium composition: ・ Polypeptone 16.0g / l ・ Yeast extract 10.0g / l ・ NaCl 5.0g / l ・ Agarose 11.0g / l Also, the packing material in the column was collected and placed in activated carbon by the purge trap method. As a result of measuring the amount of TCE adsorbed, TCE
Was not detected.

As described above, as is clear from this example, it was confirmed that the present invention efficiently purifies pollutants without secondary pollution.

Comparative Example 2 An experimental tank was prepared in the same manner as in Example 2, and a purifying device and a ground facility were prepared. However, the composition of the reactor cassette packing material in the purification device did not include the degrading bacteria (J1 strain). twenty four
After being left for a time (soil temperature 16 ° C), 50 liters of a trichlorethylene aqueous solution having a concentration of 700 ppm as a pollutant was injected into the lower gravel layer of the experimental soil using the stainless pipe installed at the time of soil preparation.

After being left for 5 hours, the vacuum pump was operated (air intake opening was opened), and thereafter, the TCE concentration in each air in the upper purification device, the lower gravel layer of the experimental tank, and the upper exhaust port of the purification device were periodically changed. The amount of air discharged was recorded. The measurement result is shown in FIG. Similar to Example 2, the TCE concentration was measured using a detector tube.

After the experiment was completed, the device was removed from the experimental tank, and the soil around the bottom of the device was collected. Neither phenol nor sodium citrate was detected in the collected soil.

Further, as a result of collecting the packing material in the column and measuring the amount of TCE adsorbed in the activated carbon by the purge trap method, a value of about 2.1 mg / g (dry activated carbon) was detected on average. . This is approximately 85% of the total TCE amount put in the experimental tank.
% Means adsorbed on activated carbon.

From FIGS. 5 and 6, it was confirmed that the effect of the present invention is not the influence of adsorption or the like but the decomposition by microorganisms.

Example 3 A glass column was packed with a packing material similar to that in Example 1 (however, the degrading bacterium was JM1 strain, and phenol for an inducer was not added), and the same apparatus as in Example 1 was assembled. .
This column was fixed to a tripod in a standing state as in Example 1, and air was blown at 2 ml / min for 48 hours at room temperature.
A TCE reservoir tank was connected and a TCE decomposition experiment was conducted for 24 hours. Further, TCE measurement was performed in the same manner as in Example 1. The TCE concentration in the gas phase was below the detection limit throughout. After the completion of the TCE decomposition experiment, the packing material in the column was recovered, and the amount of TCE adsorbed in the activated carbon was measured by the purge trap method. As a result, it was not detected.

[0047]

As described above, according to the present invention, the volatile pollutants in the soil can be decomposed and purified very efficiently and without secondary pollution due to the cleaning work.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an operation using a column in Example 1.

FIG. 2 is a diagram for explaining an operation using a column in Example 1.

FIG. 3 is a diagram showing an outline of a configuration of an experimental tank used in Example 2.

FIG. 4 is a diagram showing an outline of a purifying device used in Example 2.

5 is a diagram showing changes in TCE in Example 2. FIG.

6 is a diagram showing changes in TCE in Comparative Example 2. FIG.

[Explanation of symbols]

 1 Glass Column 2 Teflon Tube 3 Pump 4 Clean Water Bottle 5 TCE Reservoir Tank 7 Air Intake Port 8 Purification Device 9 Sealing Lid 10 Experimental Tank (Soil Filling) 11 Exhaust Port 12 Vacuum Pump 13 Filter 14 Fixing Flange 15 Cassette Reactor 16 Piles (Steel Pipe) 17 Gravel Layer 18 Contaminated Area 19 Air Containing Pollution

Front page continued (72) Inventor Etsuko Sugawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Yoshiyuki Toke 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akira Watanabe 4-23, Kudankita 4-chome, Chiyoda-ku, Tokyo Light Industry Co., Ltd. (72) Masatoshi Iio 4-chome, Kudankita 4-chome, Chiyoda-ku, Tokyo Lait Kogyo Co., Ltd. (72) Inventor Yuri Chiaki 4-23, Kudankita 4-chome, Chiyoda-ku, Tokyo Light Industrial Co., Ltd.

Claims (18)

[Claims] 1. A reaction area for holding microorganisms capable of decomposing volatile pollutants in soil in a cassette-type reactor detachably arranged in a pile-shaped body installed in soil. A method for purifying contaminated soil, which comprises inhaling and decomposing it into the soil. 2. The pile-shaped body has an intake port to the reaction region at a tip end in the direction of driving into the soil,
The method for purifying contaminated soil according to claim 1, wherein the rear end portion has an exhaust port for sucking the reaction region. 3. The method for purifying contaminated soil according to claim 1, wherein a plurality of the cassette type reactors are arranged in the pile-shaped body. 4. The method for cleaning contaminated soil according to claim 1, wherein the volatile pollutant is a hydrocarbon. 5. The method for purifying contaminated soil according to claim 4, wherein the hydrocarbon is an organic chlorine compound or an aromatic compound. 6. The method for purifying contaminated soil according to claim 4, wherein the hydrocarbon is a fuel. 7. The method for cleaning contaminated soil according to claim 5, wherein the organic chlorine compound is trichloroethylene or tetrachloroethylene. 8. The method for purifying contaminated soil according to claim 1, wherein the microorganisms are held on a carrier in the reaction region. 9. The method for cleaning contaminated soil according to claim 8, wherein the carrier contains at least one of a nutrient, an inducer and a growth stimulant. 10. A hollow tubular part, an intake port to the hollow part, a pile-shaped body having an exhaust port from the hollow part, and a volatile contamination in the tubular body whose both end openings are partitioned to allow ventilation. It is composed of a combination with a cassette type reactor provided with a reaction region for purification for holding microorganisms capable of decomposing substances, and the cassette type reactor in the hollow tubular part of the pile-shaped body, the hollow part inner wall and the cassette type A device for purifying contaminated soil, which is detachably insertable with the outer wall of the reactor sealed. 11. The purifying apparatus according to claim 10, wherein the intake port is provided at a front end portion of the pile-shaped body in the direction of driving into the soil, and the exhaust port is provided at a rear end portion. 12. The purifying device according to claim 10, wherein the volatile pollutant is a hydrocarbon. 13. The purifying device according to claim 12, wherein the hydrocarbon is an organic chlorine compound or an aromatic compound. 14. The hydrocarbon is a fuel according to claim 1.
2. The purifying device according to 2. 15. The purifying device according to claim 13, wherein the organic chlorine compound is trichloroethylene or tetrachloroethylene. 16. The purifying device according to claim 10, wherein the microorganism is held on a carrier. 17. The purification device according to claim 16, wherein the carrier contains at least one of a nutrient, an inducer, and a growth stimulant. 18. The purification apparatus according to claim 10, wherein a plurality of cassette type reactors are inserted in the tubular portion.