JP3491963B2 - Suppression of diffusion of underground pollutants and purification method thereof - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention is a method of injecting a high-molecular water-absorbing resin in a dry state, a degradable microorganism and a surviving / proliferating / active material into a stratum in a contaminated area, and swelling the high-polymer water-absorbing resin in soil particles The present invention relates to a soil treatment method in which the diffusion of pollutants is suppressed by closing the gaps and the pollutants are decomposed by degradable microorganisms.

[0002]

2. Description of the Related Art In recent years, environmental pollution caused by hydrocarbons such as aromatic hydrocarbons, paraffins and naphthenes, and organic chlorine compounds such as trichloroethylene, tetrachloroethylene and tetrachloroethane has become a problem. Most of these penetrate into the soil layer, are not decomposed, and gradually dissolve in the groundwater to expand the contaminated area through the groundwater.

There is a strong demand for the establishment of a technique for preventing the recurrence of these serious environmental pollutions and for purifying an already polluted environment or preventing the diffusion of a polluted area.

[0004] Conventionally, as an example of the environmental restoration technique, a polluted groundwater is pumped up to separate volatile organic substances, and aeration treatment for adsorbing them on activated carbon, exposing the contaminated soil layer to the sun or a heat source to heat the volatile organic substances. Heat treatment to evaporate by, the boring hole in the polluted soil layer and vacuum extraction to suck the pollutants in vacuum, and the vacuum pot processing to put the polluted soil layer into the vacuum pot and heat it to extract by suction. There is.

In order to prevent the diffusion of pollution, movement of contaminated groundwater is carried out by shielding with steel sheet pile, soil coagulant, concrete wall, etc., and by installing a pumping well (barrier well) in the downstream area of groundwater flow. There are known methods for preventing the above.

In the case of high concentration and local pollution, these physicochemical treatments may be effective, but the problems of processing speed and cost when pollution is low concentration and wide range, and collected pollutants are further There was a problem that a treatment for making it harmless was required. As a method for solving these problems of physicochemical treatment, a soil remediation method using the biodegradability by microorganisms, so-called bioremediation has been studied in recent years.

According to this purification method using microorganisms, the input energy is small, and the decomposition is performed with water, carbon dioxide, oxygen,
It can be completely advanced to nitrogen gas.

A large number of microorganisms are known that decompose persistent compounds that cause soil layer pollution, such as aromatic hydrocarbons and organic chlorine compounds. However, when these degrading microorganisms are directly applied to the actual contaminated soil layer, the growth and degrading activity of the microorganisms are usually not sufficient.

One of the reasons for this is that the distribution of bacteria and the distribution of contaminants are different, and the survival of the bacteria and the conditions for the activity are insufficient.

In order to overcome these problems, conventionally, a method of spraying microorganisms together with a chemical that supplies nutrients and oxygen, and a method of pumping microorganisms underground have been used. However, it cannot be expected that the sprayed microorganisms will have the same distribution as the distribution of already polluted harmful substances. The reason is that there is a difference in specific gravity with the pollutant, a difference in chemical affinity with the soil layer, and a difference in the diffusion time of the contaminant and the microorganism. In many cases, even if the microorganisms are directly applied to the contaminated soil layer, the microorganisms cannot adapt to the soil layer and die. It is considered that this is due to lack of nutrients required by microorganisms, presence or absence of water and oxygen, competition with other microorganisms that live in the past, predation, and incompatibility of other physical conditions such as pH and temperature.

On the other hand, in order to prevent the diffusion of the pollutants, a steel sheet pile or a physical shielding agent such as a soil coagulant can temporarily prevent the diffusion of the pollutants. Leakage of contaminated groundwater always occurs from a part. Enormous work is required to completely prevent the leak, which causes problems in cost, time, place, and the like. In addition, if the water is completely blocked, there will be secondary problems such as the inability to use groundwater in the downstream area of groundwater and ground subsidence.

Conventionally, as a short-term impermeable construction, one using a polymer water-absorbing gel is known. Impermeable walls made of polymer water-absorbing gel are effective for temporarily slowing the movement of water, and are extremely effective for temporarily mitigating water leaks in river construction, tunnels, and underground passages. However, this impermeable capacity is not sustainable and therefore could not be used to permanently prevent the spread of pollutants.

[0013]

The route by which underground pollution substantially affects the environment varies depending on the nature of the pollutant and the pollution state. However, in the case of underground pollution due to organic chlorine compounds, which has been a particular problem in recent years, organic solvents that leaked underground penetrate rapidly deep into the ground due to its specific gravity, dissolve into groundwater, and this groundwater moves. Along with that, it causes a serious problem of expanding the contaminated area.

On the other hand, the above-mentioned impermeable wall is often constructed perpendicularly to the stratum and is effective in preventing lateral migration of pollutants, but the pollutants are not It is not effective in suppressing the penetration of
In order to deal with this, it is necessary to construct an impermeable wall horizontally to the stratum, but it is extremely difficult to construct such an impermeable wall in the ground, and it is also difficult to construct contaminated water. As the water is stored, there is also a problem that pollutants leak from around the impermeable walls.

A method for purifying pollutants that have permeated from the upper layer by decomposing microorganisms that have been injected into the lower layer of soil that has already been contaminated is also commonly used in bioremediation, but fine sand that allows easy permeation of the substance is used. In the formations such as coarse sand and gravel, the permeation speed of the pollutant into the lower layer is high, and it often diffuses to the lower layer before it is decomposed by degrading microorganisms.

[0016]

In order to solve the above problems, the present inventors have combined a water-swellable polymeric water-absorbent resin with harmful substance-degrading microorganisms to simultaneously contaminate the formation or contaminated formation. The present invention has been made based on the idea of suppressing the diffusion of pollutants and effectively purifying the pollutants by injecting horizontally into the lower layer of the stratum. That is, when a fine particulate water-absorbent resin in a dry state is injected into the formation, the polymer water-absorbent resin absorbs water in the soil at the injection point and expands, thereby narrowing the gap between soil particles. Controls the migration rate of contaminants to the lower layer. Further, it becomes possible to contact with the decomposable microorganisms injected at the same time for a long time, and the permeated water is purified and gradually drained to the lower layer. The first soil treatment method of the present invention is
Vertical migration of polluted chemicals and groundwater
Can be contaminated by potentially harmful formations or hazardous chemicals
Flow of toxic chemicals below and above the strata
In areas with formations that may be contaminated by
Formation of dry polymer water absorbent resin and biodegradable material
Place it horizontally with respect to the
Characterized by biological purification while suppressing movement
It is a soil treatment method. The second soil treatment method of the present invention is
Under the stratum contaminated with hazardous chemicals, and
Polymers in a dry state in the stratum where groundwater migration is observed below
Water absorbent resin and biodegradable material horizontal to the formation
Placed in place to prevent downward movement of harmful chemical substances
A soil treatment method characterized by biological purification
It The present invention will be described in detail below.

The polymer water-absorbent resin (polymer water-absorbent gel) used in the present invention is preferably one having high gel strength and excellent salt resistance since it is used by being put into soil. Those used in the field of agriculture and horticulture can be used. Specifically, starch acrylonitrile graft polymer hydrolyzate, starch acrylic acid graft polymer, starch styrene sulfonic acid graft polymer, starch vinyl sulfonic acid graft polymer, starch acrylamide graft polymer,
Cellulose acrylonitrile graft polymer, cellulose styrene sulfonic acid graft polymer, carboxymethyl cellulose crosslinked body, hyaluronic acid, agarose, polyvinyl alcohol crosslinked polymer, sodium polyacrylate crosslinked body, sodium acrylate vinyl alcohol copolymer, polyacrylonitrile-based heavy polymer Such as combined saponification.

These polymeric water-absorbent resins preferably have a particle size as small as possible in order to rapidly move and diffuse in soil. In particular, it is preferable that the particles have a particle size of 20 μm or less when dried and swell 400 to 500 times at the time of water absorption to form a gel-like particle of 1 to 4 mm. However, when it is 500 μm or less when dried, it becomes practical. Of course, it is also effective to grind to make the particle size fine if the particle size is large in the dry state.

This polymer water-absorbent resin is easy to move in soil because it is minute when it is dried, but it becomes extremely difficult to move when it swells. Therefore, if it is a polymeric water-absorbent resin that requires a relatively long time from contact with water to swell,
Swelling is suppressed for a while even when injected into the soil, and after being transported to the intended location, it is gradually swollen, and the gaps between soil particles can be filled. It is also important to keep the injection time as short as possible. There is no problem if the injection time can be suppressed to 1 to 2 minutes if the polymer water absorbent resin has a slow expansion rate. In addition, when injecting into a stratum with a large gap between soil particles, a relatively long injection time does not cause a big problem.

When a high-molecular water-absorbent resin having a high expansion rate is used, when it takes a long time to inject it into the formation, or when the soil particle gap is small, the resin does not reach the intended location or is injected at the injection port. It may cause clogging. Therefore, it is effective to lightly subject the resin surface to ozone treatment, formaldehyde treatment, or the like to prolong the time from contact with water to expansion.

In order to shorten the contact time of the resin with water at the time of injection, as shown in FIG. 1, a polymer water-absorbent resin 1 is filled in a water-impermeable membrane or bag 2 in a dry state. Then, it is installed in the vicinity of the injection hole 4 of the digging pit 3 (for example, by attaching a weight 5 and dropping it in the digging hole), and it is ruptured by the pressure applied to the injection liquid 6 at the time of injection, and the resin etc. are momentarily in the formation. We have also devised a method of sending it to (Fig. 1).

The swollen polymeric water-absorbent resin is flexible and deforms to fill voids between soil particles in soil. By adjusting the amount of the polymer water-absorbent resin to be injected with respect to the void volume, the permeation rate of the contaminated water that permeates the expanded resin layer can be controlled. The permeation rate may be adjusted arbitrarily according to the concentration of the pollutant, the permeation rate of contaminated water, the ability of the degrading microorganisms to decompose the pollutant, and the like.

Next, the decomposition of pollutants by degrading microorganisms will be described. Hazardous chemical substances causing soil pollution which is a problem in the present invention are persistent compounds, for example,
They are aromatic hydrocarbon compounds and organic chlorine hydrocarbon compounds. Although some microorganisms that decompose these are known, even if these microorganisms are directly sprayed on the actual contaminated stratum, a sufficient effect on harmful chemical substances in soil cannot be expected. One of the reasons is that it is difficult to efficiently contact these degrading microorganisms and pollutants in the soil, and the concentration of microorganisms after injecting into the formation decreases rapidly with time, compared to the initial concentration of microorganisms. . Therefore, it is necessary to take measures such as frequent and large-scale seeding of microbial material, which is inconvenient in processing time and cost. Therefore, keeping contact with pollutants for a long time, survival and growth of microorganisms,
It is necessary to devise a method of maintaining activity.

In the present invention, in the ground, degradable microorganisms are held in a carrier suitable for inhabiting microorganisms, and this is mixed with a polymer water-absorbing resin (hereinafter, this polymer water-absorbing resin and the microorganism-holding carrier are These problems have been solved by the method in which the mixture is called a purifying agent), and at the same time, it is placed in the formation. That is,
A morphology in which a microorganism holding carrier is mixed between expanded polymer water-absorbent resins in a target formation is created. As a result, the contaminants retained by the polymer water-absorbent resin come into contact with degradable microorganisms for a long time, and the purification ability is promoted. Further, by retaining the microorganisms on the carrier, the survival / proliferation of the microorganisms is improved, the supply of new microorganisms becomes unnecessary, and the microorganisms adapted to the soil environment are maintained. Of course, for microorganisms that can maintain their survival and growth in the soil without being retained by a carrier, suspend the free microorganisms in the medium (for example, solution) used when injecting the purifying agent and put them in the soil. May be injected. Further, the growth / decomposition activity can be maintained by holding a material for maintaining the growth / activity of microorganisms on this carrier or by adding it to the solution at the time of injecting the cleaning agent.

Regarding the soil remediation method using only the carrier for holding microorganisms, the present inventors have already developed a technique using microhabitat (Japanese Patent Application No. 5-26086).
6).

[0026] The micro habitat means a microscopic living of microbes in pores of about several µm, and has a function of protecting the microbes from a harsh external environment. For example, even when the outside of the pores is in a dry state where it affects the survival of the microorganisms, the water supply to the microorganisms is maintained because the capillary water is retained in the microhabitat. Microorganisms in the microhabitat can also avoid predation by protozoa in the soil. Therefore, the microhabitat of the microorganism to be administered is artificially formed in a carrier, and this carrier is administered into the soil to improve the survival of the microorganism. The retention of microorganisms on the carrier in the present invention brings about a further effect of improving the survival property by the microhabitat.

The type of carrier is not particularly limited,
To facilitate movement in soil, several μm to several hundred μ
It is preferably about m. Around 300 μm is the easiest to handle. If it is large, crush it. Further, a carrier having a pore structure or a carrier having an ion exchange group on the surface and excellent in ion adsorption is suitable for adsorption and growth of microorganisms.
Examples of such carriers include porous ceramics, porous glass, inorganic materials such as calcium silicate and silica, activated carbon, anion exchange resins, organic materials such as cellulose, lignin, chitin and chitosan. An inexpensive one is preferable in consideration of a large amount of administration in soil.

The growth material corresponds to a culture medium of microorganisms. Microbes grow with nutrients and contribute to the degradation of pollutants. In addition to nutrients required for growth directly, aerobic bacteria require oxygen, and many other microorganisms also require trace amounts of inorganic salts, and these are referred to as nutrients. The activity-maintaining material is intended to substantially promote the decomposition of pollutants and may be indistinguishable from nutrients. It is widely known that, when a microorganism cannot directly act on a specific substance, an inducing substance (inducer) produces a degrading enzyme to decompose the specific substance and promotes the decomposition. Degradation of pollutants is often enabled by the enzymes thus produced by microorganisms. In the present invention, the material required for producing this contaminant-degrading enzyme is used as the activity maintaining material.

The type of microorganism is not particularly limited as long as it has a degrading activity, but it is practical from the viewpoint of growth and degradation of bacteria, yeast and the like. In addition, as the microorganism, only one kind may be used, or two or more kinds of microorganisms may be mixed and used. Indigenous microorganisms that have not been isolated or identified can also be used as they are.

As the growth material, those used in the medium for culturing microorganisms can be used. For example, broth medium, M9 medium, L medium, Malt extract
t, MY medium, nitrifying bacteria selective medium and the like are effective.

As the activity maintaining material, there are materials known as inducers when the degrading bacteria are specified. As an inducer that can be identified, methane is used in methane-utilizing bacteria, and toluene, phenol, o,
In the case of nitrifying bacteria, there are ammonium salts and the like.

Now, taking as an example the bacteria known to be capable of degrading trichlorethylene (TCE), more than ten species have been discovered and isolated so far. Of these, the representative ones can be roughly divided into two depending on the type of the substrate.

That is, methane-utilizing bacteria and aromatic genus such as phenol
It is a compound-assimilating bacterium. The representative of the former is methane
Has nooxygenaseMethylocystis sp.strain M
(Agri.Biosci.Biotech.Biochem., 56,486 (1992), 56,
736 (1992)),Methylosinus trichosporium OB3b (Am.Ch
em.Soc.Natl.Meet.Div.Environ.Chem., 29,365 (1989), A
ppl.biochem.Biotechnol., 28,877 (1991)), the latter
Is toluene monooxygenase or toluenedio
Have xygenaseAcinetobactor sp.strain G4(App
l.Environ.Microbiol., 52,383 (1986), 53, 949 (198)
7), 54,951 (1989), 56,279 (1990), 57,1935 (199)
1)),Pseudomonas putida F1(Appl.Environ.Microbio
l., 54,1703 (1988) and 54,2578 (1988)) are typical examples.
is there. Of these, aromatic compounds assimilating TCE-degrading bacteria
With respect to, the enzyme that degrades TCE is phenol,
Inducible enzyme induced by aromatic compounds such as ruene
Yes, and therefore cause these microorganisms to degrade TCE
In order to contain aromatic compounds or
A material that is decomposed into things is used.

The method for retaining the microorganisms on the carrier may be an ordinary method, for example, culturing the microorganisms by mixing the carrier with a medium.
It may be retained by a method such as encapsulating microorganisms in the pores under reduced pressure.

The disposing of the purifying agent is generally injection by a medium, and is carried out so that a layer of the purifying agent is formed horizontally in the contaminated formation or in a lower region of the contaminated formation. Therefore, the type of soil constituting the stratum to which the present invention is applied is particularly effective for fine sand, coarse sand, gravel, etc., in which groundwater can easily penetrate in the lateral direction. Also with regard to injecting decontamination agents, these are soils to which the invention is readily applicable. The method of injecting the purifying agent may be the same as the conventional method of injecting microorganisms into the soil. For example, there is a method in which an excavation hole is provided and a purifying agent is pumped together with water by a water supply pump. Since the cleaning agent contains particles having a particle size larger than that of microbial cells, it is necessary to increase the pressure of the injection pump or guide the injection port to the vicinity of the contaminated site. Other than that, there is no particular limitation.

Further, the purifying agent also deals with the diffusion of the pollutant in the lower layer, but even if the layer of the purifying agent is formed vertically with respect to the stratum, the pollutant reaches the groundwater and the horizontal direction. It will not be a waste even if the movement of people comes to be done.

Further, by injecting and installing the source so as to surround the source in the moving direction of the contaminant, it is not necessary to consider the distance from the source.

The configuration of the present invention will be schematically described in FIG.
In the stratum of FIG. 2, there are a sandy layer, a coarse sand layer, and a gravel layer 12 below the topsoil or loam layer 11, and the impermeable layer or impermeable layer 13
There is. And the groundwater layer 14 is formed in the upper layer. The purifying agent according to the present invention is a sand layer, a coarse sand layer, a gravel layer 1
Of the two strata, the stratum reaching the pollutant or the lower stratum of the pollutant is injected from the injection hole 4 of the excavation pit 3 to swell the polymer water-absorbent resin 1 and then to the microbial materials 16 and 1
A layer like No. 7 is formed. The pollutant layer 19 diffused from the pollution source 18 permeates underground and flows in the A direction. Contaminants are reduced by the layer 17 while reducing the flow velocity.
, The pollutants are decomposed by the microorganisms contained in 16 in this process, and purified water is released to B.

In the practice of soil remediation, a survey of the contaminated area is carried out prior to injecting the remedial agent into the soil for a specific plan of disinfectant placement. In many cases, the source of pollution can be identified from past materials such as ground facilities and the land where pollutants are buried. Boring is performed in a grid pattern centering on the source of pollution to map the state of pollution that spreads toward the downstream side of groundwater. If this is not the case, it is necessary to carry out the drilling survey from the location where the contamination was found to the upstream side of the groundwater flow in a grid pattern. At the time of this boring survey,
Data such as the direction of groundwater flow is also accumulated.

Once the area of contamination and the diffusion direction of the pollutants have been analyzed, generally possible physical cleaning measures are implemented there. However, the present invention is also effectively used to remove residual contaminants when physical purification measures cannot be implemented or after possible measures have been taken.

Examples of the present invention will be shown below, but these do not limit the scope of the present invention.

[0042]

【Example】

Reference Example 1 Investigation of Mobility of Purifying Agent in Soil Here, whether or not a purifying agent composed of a polymeric water absorbent resin and a microbial material can be injected into soil was examined.

First, fine sand (particle size 0.2 to 0.12 m
m), coarse sand (particle size 1.8 to 0.9 mm), gravel (particle size 2.
(5 mm or more) was gradually packed into a glass column having an inner diameter of 30 mm and a length of 800 mm, and the glass column was packed to a length of 500 mm. From the upper end of this soil column, 100 ml of a suspension simulating a purifying agent was injected. 10 simulated agents
Polyacrylic acid cross-linked polymer water absorbent resin selected by particle size of 0 to 200 μm (Sunwet IM-5 manufactured by Sanyo Kasei Co., Ltd.
000S) 1 g, and a cellulose carrier (microcarrier manufactured by Asahi Kasei Co., Ltd.) 0.5 g having a particle size of 180 to 210 μm. In addition, the injection method was performed by pouring the purifying agent pseudo suspension from the upper end of a vertically standing column with a beaker, using a rubber stopper with a glass tube attached, and then sending compressed air from the glass tube.

Twenty-four hours after the injection, the column was cut at each point of 50, 150, 250, 350, and 450 mm from the upper end of the column, and 10 g of soil at that point was sampled. 50g of distilled water was added to 10g of this soil sample.
After adding 10 ml to the solution and gently suspending it, the supernatant was taken after standing for 10 seconds, and the volume of the polymer water-absorbent resin sieved with a sieve having a diameter of 250 μm was measured.

The results are shown in FIG.

As a result, the purifying agent can be injected into the soil having a grain size smaller than that of fine sand, and the mobility of the purifying agent is particularly good in the order of gravel, coarse sand, and fine sand having a coarse grain size. I understood. Example 1 Purification Experiment of Contaminated Soil A purification experiment of a pollutant with a purifying agent was actually conducted using a lysimeter.

FIG. 4 (a) is a side view of the experimental model, showing the bottom.
5 drains 35 (diameter 20 mm) and one note on the side
In the inlet hole 31 (10 mm × 50 mm) and the injection hole 31
500ml syringe 32 for injecting purifying agent connected
1m square and 1.2m deep soil tank 33 with sand
(Particle size 0.2 to 0.12 mm), coarse sand (particle size 1.8 to
0.9 mm), gravel (particle size 2.5 mm or more) 2: 2: 1
The soil 34 mixed in was filled up to a depth of 1 m. This test
Soil tank 33 contains phenol 100ppm from injection hole
Then, 10 l of the purifying agent suspension was pumped. Purifier suspension is poly
Acrylic acid cross-linked polymer water absorbent resin 100g, TCE content
It is composed of 50 g of a cellulosic carrier which holds lysate. Poly
Acrylic acid crosslinked polymer water absorbent resin is 100-200μ
SANWET IM-5 manufactured by Sanyo Kasei Co., Ltd. in which the particle size of m is selected
000S was used, and as a TCE-degrading bacterium, pheno
As an inducer of TCE degradationPseudomonas cepacia 
Using KK01 (deposit number FERM BP-4235)
It was The phenol added to the purification agent suspension isP.cepaci
a It was used for the induction of. For the method of holding on a cellulose carrier,
WithoutP.cepacia To 500 ml of medium (0.2% glutamine
Sodium acid, M9 medium (Na₂ HPO_Four 6.2g, K
H₂ PO_Four 3.0 g, NaCl 0.5 g, NH _Four Cl
  1.0 g / l)) and inoculated at 30 ° C.
O. of the culture solution. D. When the solution reaches about 0.7, the solution is
Add 5 g of roulose carrier (Asahi Kasei Microcarrier)
Evacuate in the pressure bottle to recover the bacteria in the micropores.
Was introduced. Use this with filter paper (Whatman NO.44)
Then, only the carrier was recovered and used as a purifying agent.

The purifying agent is injected into the soil 34 by filling the syringe with the purifying agent and using a piston to obtain about 150 ml /
It was pumped from the injection hole so that the speed was 2 seconds.

Twenty-four hours after the cleaning agent was injected, 10 ppm of TCE solution was applied to 5 points of the soil surface immediately above the drain 35.
The solution was added dropwise at a rate of 0 ml / hour, and the TCE concentration of the liquid leaked from the lower drain was measured every 2 hours from the start of the addition. The TCE concentration was 5 ml of the leaked liquid in a 20 ml vial bottle, sealed with a rubber stopper and an aluminum cap, and then set to 1 at 20 ° C.
The temperature was maintained for 0 minutes, and 0.1 ml of the gas phase was analyzed by gas chromatography using an FID detector.

The results are shown in FIG. Comparative Example 1 Contaminant Permeation Control Experiment Polymeric water absorbent resin (Sunwet IM-5000S) simulated in a test soil tank prepared as in Example 1 with a purifying agent.
Inject only TCE solution and NO. Only on the soil surface directly above the drain of 3. After that, as in Example 1,
Drain NO. The volume of leaked liquid from 3 and the TCE concentration were measured. The results are shown in FIGS. Comparative Example 2 Purification experiment using only microbial material P. was used as a purifying agent in a test soil tank prepared in the same manner as in Example 1 .
Only the cellulose carrier that holds cepacia KK01 (Microcarrier manufactured by Asahi Kasei Corp.) is injected, and TCE dropping is N
O. It was dripped only on the soil surface just above the drain of 3. After that, as in the first embodiment, the drain NO. The volume of leaked liquid from 3 and the TCE concentration were measured. The results are shown in FIGS. Comparative Example 3 Nothing was injected from the injection hole into the test soil tank prepared in the same manner as in the target Example 1, and thereafter, TCE and distilled water were dropped in the same manner as in Example 1, and the volume of the leaked liquid from the drain and The TCE concentration was measured. The results are shown in FIGS.

From the above results, first, regarding the decomposition of TCE, from Example 1 and Comparative Examples 1, 2 and 3, the effect of introducing the decomposing microorganisms was observed, and the effect of improving the decomposing activity by the polymer water-absorbing resin was found. Has been revealed. It is considered that this is because the polymer water-absorbing resin suppressed the permeation rate of TCE as seen from Comparative Examples 1, 2, and 3. The decrease in TCE in the blank of Comparative Example 3 was due to the effect of volatilization of TCE.

[0052]

The present invention suppresses the diffusion of soil pollution, especially the downward diffusion of harmful chemical substances, and further promotes the action of degrading microorganisms, thereby improving the efficiency of decomposing and detoxifying harmful chemical substances. I was able to improve.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing an example of disposing a purifying agent according to the present invention.

FIG. 2 is a schematic diagram of an implementation status of the present invention.

FIG. 3 is a graph showing the measured mobility of the cleaning agent in Reference Example 1.

FIG. 4 shows a model of a purification experiment, (a) is a side view and (b) is a bottom view.

FIG. 5 is a graph showing changes over time in the TCE concentration of the leaked liquid.

FIG. 6 is a graph showing changes over time in the TCE concentration of the leaked liquid.

FIG. 7 is a graph showing changes over time in the amount of leaked liquid.

[Explanation of symbols]

1 Polymer water absorbent resin 2 membranes or bags 3 drilling holes 4 injection holes 5 weights 6 injection liquid 11 Topsoil or loam layer 12 Sandy layer, coarse sand layer or gravel layer 13 difficult (un) permeable layer 14 Groundwater layer 16 Microbial material 17 layers 18 pollution sources 19 layers of pollutants A Groundwater flow direction B purified water 31 injection hole 32 syringes 33 soil tank 34 soil 35 drain

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-5-115862 (JP, A) JP-A-1-142119 (JP, A) JP-A-2-164936 (JP, A) JP-A-6- 55153 (JP, A) Special Tables 4-502277 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 3/00 B09C 1/10 E02D 19/16 E02D 3/12

Claims (16)

(57) [Claims] 1. A formation or toxic chemical that is contaminated by toxic chemicals and may have vertical movement of groundwater .
Polymeric water-absorbent resin in a dry state and biological decomposition in the area below the quality-contaminated strata and in the strata where the inflow of harmful chemicals from the upper layer may cause pollution. Place the material horizontally to the formation and
A soil treatment method characterized by biologically purifying while suppressing the movement of harmful chemical substances . 2. Under the stratum contaminated with hazardous chemicals
Yes, and a high molecular water-absorbent resin and the biological degradation materials in a dry state into the formation observed movement of groundwater under which the formation
Horizontally, the downward movement of hazardous chemicals
A soil treatment method characterized by biologically purifying while suppressing soil. 3. The method according to claim 2, wherein the movement of groundwater is vertical. 4. The method according to claim 2 or 3, wherein the formation layer to be arranged is composed of sand, coarse sand or gravel. 5. After injecting the polymer water-absorbing resin into the formation, and expands by absorbing moisture in the soil, claims 1, characterized in that to form the layer by the polymer water-absorbing resin 4 The method described in either. 6. The method according to claim 1, wherein the polymer water absorbent resin in a dry state has a particle size of 500 μm or less. 7. The biodegradable material is a combination of a microorganism degradable by a harmful chemical substance and at least one selected from the group consisting of a microbial carrier, a microbial growth material and a microbial active material. Item 7. The method according to any one of Items 1 to 6. 8. The method according to claim 7, wherein the microorganism is a bacterium. 9. The method according to claim 8, wherein the microorganism belongs to the genus Pseudomonas. 10. The method according to claim 9, wherein the microorganism is Seedmonas cepacia. 11. The method according to claim 10, wherein the Pseudomonas cepacia is Pseudomonas cepacia KK01 strain. 12. The method according to claim 1, wherein the harmful chemical substance is an organic chlorine compound. 13. The method according to claim 12, wherein the harmful chemical substance is trichlorethylene. 14. The polymeric water-absorbent resin and the biodegradable material are placed in a water-impermeable packaging material in a dry state, provided in a predetermined position in advance, and then the packaging material is pressed by a post-injection medium. 14. A method according to any of claims 1-13, wherein the burst caulking fill is fed into the formation. 15. The method according to claim 7, wherein the carrier has a particle size of 1 μm to 300 μm. 16. The method according to claim 7, wherein the carrier has a pore structure.