JP3530588B2 - Method of forming in-situ microbial degradation region - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to soil remediation for biologically degrading pollutant chemicals. More specifically, it relates to the repair of soil contamination by in-situ treatment (IN SITU), more precisely, to a method for supplying a liquid microbial pollutant decomposing material to a contaminated underground to form an in-situ microbial decomposing area.

[0002]

2. Description of the Related Art In recent years, environmental pollution caused by hydrocarbons such as aromatic hydrocarbons, paraffin and naphthene, and organic chlorine compounds such as trichloroethylene, tetrachloroethylene and tetrachloroethane has become a problem. Many of these pollutants permeate into the soil, are not decomposed, and gradually dissolve in the groundwater, and the contaminated area only expands through the groundwater.

There is a strong demand for the establishment of a technique for preventing the recurrence of these serious environmental pollutions, cleaning the already polluted environment, and returning it to its original state.

Examples of this environmental restoration technology include aeration treatment in which polluted groundwater is pumped up to separate volatile organic substances and adsorbed on activated carbon, contaminated soil is exposed to the sun or a heat source, and volatile organic substances are evaporated by heat. Heat treatment to let. BACKGROUND OF THE INVENTION Contaminated soil is provided with a boring hole and subjected to vacuum extraction in which a contaminant is sucked in vacuum, and vacuum pot processing in which a contaminated soil is put into a vacuum pot and heated to be sucked and extracted.

These physicochemical treatments may be effective especially in the case of high concentration and local contamination, but when the contamination is low in concentration and in a wide range, the treatment speed and cost become problems. Moreover, even if these organic substances can be recovered by activated carbon,
Usually, there are many substances that are hardly decomposable, and there is a problem that a treatment for further detoxifying them is required. As a method capable of solving these problems of physicochemical treatment, a soil remediation method using biological treatment by microorganisms has been studied in recent years.

If microorganisms, especially microorganisms that can live in the soil, decompose pollutants, purification is carried out by natural energy, the input energy is small, and the decomposition can proceed to water or carbon dioxide.

A large number of microorganisms that decompose persistent compounds that cause soil pollution, such as aromatic hydrocarbons and organic chlorine compounds, are known. However, when these microorganism-decomposing materials are directly sprayed on the actual contaminated soil, the supply of the materials usually becomes excessive or deficient or uneven, and proper purification may not be performed.

This is because there is a time difference and a difference in physical properties between "distribution of pollutants" and "dispersion of microbial decomposition material", and it is difficult to match both.

In order to overcome these problems, a method of forcibly arranging the microbial decomposition material in the ground or a method of pumping the material with a pipe inserted into the soil layer has been used. Conventional USP-5120160 (Environ, Reclamation Sys. In
c.) and DE-3839093 C2 (Buaer Spezialitiefbau Gmbh), USP-
5080782 (Environ. Sci. & Eng. Inc.), USP5,032,042 (New
The Jersey Institute of Technology, etc. proposed to purify pollutants by supplying microorganisms and nutrients into the ground. However, these are not techniques for improving the precise distribution of the microbial degradation material, that is, the agreement of the concentration distribution of depth and spread.

Further, as known from USP 4,442,895 (S-Cubed, La Jolla), in the fields of oil and natural gas extraction in the technical fields different from the present invention, solidification of soft ground, etc. Is known to generate cracks,
The technique intended by the present invention was not aimed at water permeability as a means for supplying the decomposed material into the formation.

Although a method of pumping polluted groundwater and treating it physically or chemically or microbiologically has been attempted, such a method requires a large amount of energy for pumping and treating, and the above-mentioned ground for purification is required. There were many problems that required facilities, ground subsidence, hindrance to the downstream use of groundwater flow, and influence of downstream water change on the downstream ecosystem.

[0012]

Conventionally, in the method of directly supplying a so-called microbial decomposing material such as bacteria and its nutrients into the soil, a distribution corresponding to the distribution of pollutants can be artificially created on the ground surface. It was very difficult. Under such inadequate control of bacterial distribution, it is disadvantageous in that the efficiency of decomposition such as excessive supply of these is reduced and the economy is low. On the other hand, since the decomposed material is supplied to the ground, it is physically difficult to dig deep into the ground in a wide area, and it is difficult to solve the cost. In the case of natural diffusion simply by spraying from the ground surface, it is difficult to make the distribution state of both pollutants the same because of the time lag when the pollutants started to diffuse and the time lag in supplying the biological decomposition products. In particular, the difference in diffusivity, in addition to this time difference, causes a difference in distribution to be increased due to a difference in specific gravity between the two and a difference in chemical or biological affinity with soil. In particular, the conventional method has not shown any solution to the problem of different supply states in the unsaturated zone and the saturated aquifer.

Therefore, there has been proposed a method of forming a boring hole and injecting these microbial decomposing materials from the hole. However, in the simple injection from the boring hole, the position, distribution range, concentration, etc. of the decomposing material should be designed. It was difficult to expect more supply.

This was due to the heterogeneous nature of the soil layer, the supply to the water channel formed by nature, and the drooling without knowing the excess or deficiency of the supplied material. .

An object of the present invention is to solve the above-mentioned various problems in soil remediation, and to provide uniform supply in the depth direction, supply to a predetermined range on a line or plane, and a predetermined concentration. The purpose is to ensure the supply and to surely form the desired decomposition region.

[0016]

From the above viewpoints, the present inventors have proposed a material necessary for biological decomposition in a soil purification method for biologically decomposing harmful chemical substances contaminating a soil layer ( (Hereinafter sometimes referred to as decomposition material) in the method of injecting into the ground in its original position, at least a pair of injection pipes and suction pipes are inserted at a constant interval and depth
After supplying the decomposing material to the underground at that depth at that interval,
Gradually changing the insertion depth of the pipe and repeating the injection to find a supply method for supplying the decomposition material to a predetermined depth, and further studying a supplementary configuration for promoting the effect of the present invention. Based on achieving improvements.

The present invention will be described in detail below.

The route in which soil pollution substantially affects the environment varies depending on the nature of the pollutant and the pollution state. However, in the case of soil pollution due to an organic chlorine-based solvent, which has been particularly problematic in recent years, the solvent leaking underground penetrates deep into the ground and gradually dissolves in groundwater. In many cases, the problems occurred only when this groundwater was directly used in the groundwater downstream area, or when the groundwater spewed from the ground and outflowed to a river.

If the contaminated soil is local and is in the initial stage of contamination, the problem can be solved by directly treating the contaminated soil. However, in many of today's problems, organochlorine-based solvents have been widely used and more than 10 years have passed, and it is often the first time that problems are noticed. Is adsorbed on the groundwater and gradually dissolves in the groundwater passing through it.
The above-mentioned groundwater pollution affects the environment.

Here, a typical contamination mechanism of an organic chlorine solvent having a large specific gravity will be described. FIG. 1 is a schematic diagram of an underground cross section of a typical organochlorine-contaminated soil.

First, the solvent that has penetrated from the pollution source C to the soil I (top soil), H (loam layer), G (sand layer) and F (sand gravel layer) is adsorbed to the soil, and the excess solvent that cannot be adsorbed is successively admitted to the lower layer soil. And adsorption progresses. The distribution of pollutants at this time has a steep mountain shape, and as long as there is soil that can penetrate and adsorb, the distribution in the horizontal direction does not proceed so much.

When the solvent reaches the formation E (for example, silty clay layer) or the aquifer in the dense soil layer where the solvent cannot sufficiently permeate, the solvent stays in the vicinity. Next, rainwater or groundwater supplied from the ground takes a solvent adsorption equilibrium between soil and water, and with a certain distribution coefficient,
The solvent dissolves in water. Often with organochlorine solvents,
Solubility is low and several 1000 ppm or less. Although this value is physically low as a solubility, it is an extremely large value as environmental pollution.

Furthermore, when the adsorption equilibrium of the pollutants to the soil and groundwater (keeping a constant value by the distribution coefficient) shifts to the re-equilibrium due to the new inflow and supply of groundwater, the dissolved solvent passes through the water. Expand pollution. The groundwater flow J occurs below the groundwater level D, but the adsorption of the gravel layer is less than the adsorption of the solvent as compared with the loam layer and the silt layer. It will increase the expansion.

Further, the organic chlorine-based solvent that has penetrated into the ground evaporates in the ground as it diffuses in a liquid state and pollutes the ground air. This pollution often contaminates a wide area at a low concentration. Become.

It is an object of the present invention to provide a continuously effective pollution purifying means in consideration of such a structure of pollution. That is, in many cases, it is difficult to dig up and remove the contaminated solvent that has penetrated deep into the soil together with the soil. The depth of infiltrated soil varies from stratum to stratum, but can reach several meters to several tens of meters. In many cases, factories, facilities, houses, etc., that are in operation are located above the polluted land. Also, of course, the deeper the area, the wider the contaminated area. The slow movement of groundwater requires a long time before the contamination is detected, which also contributes to the expansion of the contaminated area. Therefore, in the conventional technique, complete purification of the entire contaminated region may be impractical.

The present invention aims to perform microbiological purification (bioremediation) on the contaminated structures of these aquifers and non-aquifers at appropriate positions and arrangements. Next, a method for decomposing biologically harmful chemical substances 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. A large number of microorganisms that decompose these are known, and some of them are known to have a degrading enzyme. However, even if these microorganisms or enzymes are directly applied to the actual contaminated soil as a practical technique, a sufficient effect on the harmful chemical substances in the soil cannot be expected.

One of the reasons is that the distribution characteristics of the microbial material and the chemical substance are different, and the time course of the distribution cannot be the same.

Another reason is that even if a decomposing activity is obtained under certain conditions on the ground such as an incubator, it is not always possible to obtain the same habitating conditions in the ground and exhibit the same activity. Because there is no.

When the microbial material is sprayed directly on the ground or in the ground, the fungus itself or the enzyme concentration of this microorganism is rapidly decreased in the soil with respect to the initial concentration at the time of spraying.

The reason for the decrease is not always clear, but it is considered to be due to competition with microorganisms existing in the soil, death from nutrition and other environmental incompatibility, predation by other organisms such as protozoa, etc.

Therefore, it is necessary to take countermeasures such as frequent and large-scale seeding of microbial material, which causes inconvenience in processing time cost and the like. Therefore, there is a strong demand for a method in which microorganisms grow in soil containing harmful substances and the activity is maintained.
Similarly, in the case of an enzyme, it is necessary to secure the conditions for maintaining the activity in the soil. Therefore, when supplying these microorganisms into the ground, it is necessary to simultaneously supply the microbial activator, the survival material, the growth material and the like.

In the present invention, these materials necessary for the decomposition of pollutants by microorganisms are put together and the required amount is accurately supplied to the intended place.

According to the present invention, when supplying the necessary material into the soil, at least a pair of pipes capable of injecting and aspirating, respectively, are inserted into a target place to form a channel at a position to be infused. The injection and suction are performed between the pipes, while the necessary amount is secured by detecting the pre-labeled attribute of the decomposition material and controlling the injection and suction operations based on the detected value. The present invention constitutes a specific method for easily realizing and repeating these unit operations. Next, the configuration will be specifically described in detail.

Microbial materials (decomposition materials) used in the present invention for decomposing pollutant chemical substances include materials derived from microorganisms capable of decomposing chemical substances causing pollution problems.
As a material to be added to this, a material having a growth function necessary for the growth of microorganisms, that is, a growth material, an activity maintaining material that functions to express decomposition by the microorganism, and a carrier that allows the microorganism to enter the ground and stably live Survival materials, in addition to these materials, in the present invention, in particular, it may be composed of a penetrating material for allowing these materials to easily penetrate into the ground, and an index material capable of easily confirming the penetration of these materials. it can. There may also be channel formers that enhance the penetration function. Each of the materials having these functions may be composed of a single material, but a single material having a plurality of functions is naturally used.

The growth material corresponds to the culture medium of the microorganism. Microbes grow with nutrients and contribute to the decomposition of harmful substances. The activity-maintaining material is for substantially promoting the decomposition of harmful substances, and in some cases, it cannot be distinguished from nutrients.
When a specific substance cannot directly utilize a specific substance as a nutrient, it decomposes this specific substance, so that an inducing substance (inducer) produces a degrading enzyme to promote the degradation. The decomposition of harmful substances is made possible here by enzymes produced by microorganisms. In the present invention, the material necessary for producing this harmful substance-degrading enzyme is used as the activity maintaining material.

This means that the harmful chemical substances can be decomposed without the direct use of the microorganisms themselves, only by the enzyme, which is a metabolite of the microorganisms. When an enzyme is used instead of the microorganism, a metal ion, a coenzyme, or the like may be required in order for the carrier holding the enzyme or the enzyme to exhibit degrading activity.

The survival material is one that provides a habitation space for protection from microorganisms when they are predated by other microorganisms or microbes in the ground or compete with each other. In some cases, it also serves as an immobilization carrier in order to prevent effective microorganisms from diffusing and disappearing in groundwater. It is also possible that the growth material, that is, the nutrient itself, fulfills this function.

As the material for providing a survival space for microorganisms as the survival material, various microorganism carriers used in bioreactors conventionally known in the pharmaceutical industry, food industry, wastewater treatment system and the like are used. For example, porous glass, ceramics, metal oxides, activated carbon, kaolinite, bentonite, zeolite, silica gel, alumina, particulate carriers such as anthracite, starch, agar,
Chitin, chitosan, polyvinyl alcohol, alginic acid, polyacrylamide, carrageenan, agarose,
Examples thereof include gel carriers such as gelatin, ion exchangeable cellulose, ion exchange resins, cellulose derivatives, polyglutaraldehyde, polyacrylic acid, urethane polymers and the like. Also, natural or synthetic polymer compounds are effective, and papers made of cellulose, cellulose, hemp, pulp materials, or polymer acetates obtained by modifying natural products are also effective. Cloths made of synthetic polymers such as polyester and polyurethane can also be used. It is preferable that these have good adhesion to microorganisms and have fine gaps. Further, a fine material is preferably used so that it can be easily permeated when it is prepared into a liquid material and injected.

[0039] As a material that provides a living space and a nutrient, many examples can be found in compost materials known in the agriculture and forestry industry. That is, dried plant remains such as straw and sawdust of cereals such as straw, rice bran, okara, sugar cane squeezing residue, crabs and shrimp shells also have micropores and become degradable nutrients by microorganisms,
In particular, a material that can be processed into a fine particle size is preferably used.

Next, the microorganisms applicable to the present invention will be specifically shown. As the microorganism, a material whose degrading activity has been confirmed is used as a material, and is selected from, for example, those belonging to the following genera. That is, Saccharomyces, Hansenula, Cand
ida, Micrococcus, Staphylococcus, Streptococcus, Leuco
nostoc, Lactobacillus, Corynebacterium, Arthrobacter,
Bacillus, Clostridium, Neisseria, Escherichia, Enterob
acter, Serratia, Achromobacter, Alcaligenes, Flavobact
erium, Acetobacter, Nitrosomonas, Nitrobacter, Thiobac
illus, Gluconobacter, Pseudomonas, Xanthomonas, Vibria
Etc.

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 those known as inducers when the degrading bacteria have been specified, but in natural materials, these are usually present in a mixed state and cannot be specified. There are many things. Particularly in the case of mixed microorganisms, the metabolite of one microorganism is often a symbiotic system that functions as an inducer of another microorganism. Therefore, when a mixed microorganism is used, a natural organic substance in which various substances coexist is effective. As an inducing substance that can be identified, methane is used in methane-utilizing bacteria, and toluene, phenol, o, m, p cresol, etc. in aromatic-assimilating bacteria.
Nitrifying bacteria include ammonium salts.

Here, taking as an example the bacteria known to be capable of degrading trichloroethane, which is the most serious problem in reality, 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, it is a methane-utilizing bacterium and an aromatic compound-utilizing bacterium such as phenol. The representative of the former is Methylocystis sp. Strain M, which has methane monooxygenase.
(Agri.Biosci.Biotech.Biochem., 56,486 (1992), 56,73
6 (1992)), Methylosinus trichosporium OB3b (Am.Chem.S
oc.Natl.Meet.Div.Environ.Chem., 29,365 (1989), Appl.b
iochem.Biotechnol., 28,877 (1991)), the latter of which is Acinetobactor sp.strain G4 (Appl.Envi) having toluene monooxygenase or toluene dioxygenase.
ron.Microbiol., 52,383 (1986), same 53,949 (1987), same 54,95
1 (1989) 56,279 (1990), 57 (1935) (1991)), Pseudomonas
putida F1 (Appl.Environ.Microbiol., 54,1703 (1988),
54,2578 (1988) is the representative. Of these,
Regarding an aromatic compound-assimilating trichloroethane (TCE) -degrading bacterium, the enzyme that decomposes TCE is an inducible enzyme that is induced by an aromatic compound such as phenol or toluene. Therefore, in order to decompose TCE in these microorganisms As the material, a material containing an aromatic compound or being decomposed into an aromatic compound is used.

When an enzyme material is used, no growth material such as nutrients is required, but it is necessary to mix minerals necessary for the enzyme to exhibit activity, such as Fe ²⁺ and NADH and other coenzymes. Sometimes there is. In principle, an enzyme should have a permanent degrading effect if it exists in the system, but it is actually inactivated depending on the conditions of use. Therefore, it is necessary to mix and integrate the materials necessary for maintaining the activity of this enzyme as long as possible. Examples of enzymes include toluene monooxygenase, toluene oxygenase, ammonia monooxygenase, methane monooxygenase, and the like.

The decomposition material utilizing the microorganism of the present invention is
An aqueous solution or suspension of all or part of the above substances,
Those with a label or a channel-forming agent added thereto are used.

The most convenient means of labeling is to use an indicator substance, which dissolves in a liquid decomposing material and moves with the decomposing material liquid when it flows in the soil layer. A substance that can be easily detected and is substantially harmless is used. The indicator substance is one that can be easily detected at the moving destination and is selected from substances with a physical or chemical composition that does not exist or cannot exist in contaminated groundwater.
Examples of indicator substances are pigments used in food additives and water-soluble organic pigments that can be decomposed relatively easily by soil microorganisms, water composed of stable isotopes with a composition ratio that cannot occur in nature,
A small amount of organic acid or a small amount of salt whose electric conductivity changes is used.

Further, at a detection position which can be reached in a relatively short time, the temperature of the injected water and the temperature in the soil layer can be made different from each other to serve as means for marking.

The indicator substance may be a change in the physical state of the substance as long as the permeation of the injection liquid can be easily detected.

Examples of water-soluble organic colorants used in food additives include tar-based dyes, food red Nos. 2, 3 and 102.
No. 104, 105, 106, Yellow No. 4, No. 5,
Green No. 3 and Blue No. 1 and 2 are available.
There are carotene, crocin, betanin, bixin, red magnolia pigment, and riboflavin.

Salts which change the electric conductivity include common salt, potassium chloride, magnesium chloride and the like, and organic acids include formic acid, acetic acid, propionic acid, butyric acid and the like.

The natural stable isotopes of hydrogen, which is a constituent atom of water, have a composition ratio in which ² H (deuterium) deviates by more than 0.015%, and in oxygen, ¹⁷ O (0.038%) and ¹⁸ O (0. 20
Water having a value different from the natural composition ratio shown in parentheses such as 0%) is used. Further, a material containing a carbon compound (for example, dissolved CO ₂ or CH ₄ ) ¹³ C (1.10%) can also be used.

The temperature difference between groundwater and infused water needs to be changed depending on the distance to be infused and the difference in hydraulic conductivity, but if temperature measurement with sufficient sensitivity is possible, it is 5 to a distance of 1 to 10 m.
Even at 10 ° C, the effect can be sufficiently enhanced.

These indicator substances are not only harmless to the survival of microorganisms or useful, but are selected from materials that are harmless to plants and animals even when they remain in the soil layer.

The detection of the label differs depending on the nature of the label applied, but it is a mass spectrometer when the isotope composition ratio is artificially changed, a photometer when the dye is used, and an electric conductivity when the organic acid or salt is used. For the meter and temperature, a physical or chemical detection means is selected and used according to a thermometer and other materials having different properties from the surroundings. However, all of them are selected from the means that can be detected immediately or in a short time with a simple portable measuring device.

Although air itself may be used as the channel forming agent, a volatile and harmless organic solvent such as alcohol or water in which alcohol is dissolved, or a surfactant such as water in which neutral detergent or soap is dissolved is used. Is used.

Next, the method for carrying out the present invention in an actual contaminated area will be described in detail.

In the usual purification of contaminated soil, after analyzing the contaminated area and the diffusion direction of the pollutant, generally possible physical purification measures are taken. The present invention is still effectively used when physical cleaning measures cannot be carried out or when residual contaminants are removed after possible measures have been taken.

FIG. 2 is an illustration of a cross-sectional view of each unit of the injection or suction pipe used for carrying out the present invention. 21
Is a hammer top, and the part 211 that is attached to the tip of the pipe and is in direct contact with the hammer etc. when hammering is a structure that can receive a strong pressing force without damaging the pipe, and the other side is fitted with a screw etc. that enables joining with the pipe It has a coupling means 212. Reference numeral 22 is an injection or suction pipe body. Two
Reference numeral 21 has fitting means 221 for fitting with the hammer top at the upper end, and fitting means 223 for connecting with the unit of the conical tip portion 23 at the other end. A strainer portion 224 for injecting or sucking is provided above the fitting means 223.
There is an opening such as a plurality of holes in the pipe. This part has an outer diameter slightly smaller than the maximum diameter of the conical tip so as to facilitate injection or suction. The conical tip unit 23 comprises a fitting means 231 and a conical tip 232. The tip is made of ceramics, cemented carbide or the like that can be driven into the ground. Reference numeral 24 is an extension pipe, and fitting portions 241 and 243 for joining are provided above and below the pipe 242. The extension pipe is used by inserting it between 21 and 22 in order to send the strainer part which enters according to the driving into the ground. The entire length of 24 is adjusted to an appropriate length within the range where the driving operation is easy, and a plurality of extension pipes are connected to drive to a predetermined depth. The outer diameter of the pipe is preferably thin for facilitating driving, but is preferably thick for fear of bending due to penetration into the ground. However, unlike basic pipes used in civil engineering and construction, narrow pipes are selected as long as the straightness is maintained to some extent. Generally, a thick-walled pipe having an inner diameter smaller than an outer diameter is used, but a pipe diameter of about 20 mm to 300 mm is appropriately selected according to soil quality and depth. The driving is performed by mechanically driving with a hammer or by hydraulically fixing the surroundings.

FIG. 3 is a view for explaining the state of injecting the decomposition liquid using a pipe in the practice of the present invention. Reference numeral 31 is an injection pipe, and 32 is a suction pipe. 324 is a suction device such as a suction pump, 312 is an injection device, and at least one detection means is provided in the vicinity of the strainer of the suction pipe. This detection signal is connected to the controller 34 to operate the suction or injection device.

In the present invention, for example, first, a pipe is driven to the depth of (1) in FIG. 3, and suction is performed from 32 here. In order to prevent air from leaking from the surface of the suction pipe, it is effective to cover the ground surface with a shielding material 35 such as a clay layer in advance. 32 strainer sections 322
To suck in water or air in the gap between the surrounding soil layers.
In particular, the distance L between the pipes is set so that this suction forms a channel communicating with the pipe 31 provided nearby. L depends on the geology to be purified, but is usually 1 m
The range of 10 m is preferable. Channel formation can be effectively applied by well-known means of generating cracks in the formation by pressure during oil drilling and natural gas extraction, which is performed by pressurizing air or an incompressible fluid from an injection pipe in the formation. Achieved by sending to. This allows the channel to be long and thus L to be large.

These channels can be expanded by continuing to suck the gas or liquid supplied from the injection pipe 31 into the formed channels for a predetermined time.
By doing so, the channel formation in the formation of the portion (1) of FIG. 3 develops, and the injection of the decomposition product into the formation becomes more reliable.

The channel may be formed only by air, but a volatile water-soluble organic solvent such as alcohol or water containing a surfactant can be easily used. Also, physical means can be added to the channel formation, for example,
High-pressure air, high-temperature, high-pressure steam, hot water, or the like may be used. Alcohol, its steam, and high-temperature medium can sterilize the soil and also have a secondary effect of suppressing microorganisms that compete with the injected microorganisms. In this description, the channel formation and the injection of the decomposition material are described as separate steps for the sake of understanding, but they may be continuous steps or do not prevent simultaneous execution. That is, it also includes directly putting the decomposing material into the liquid used for forming the channel.

The means for confirming the channel formation can be easily confirmed by detecting the fluid itself or by detecting the indicator substance added to the fluid. In any case, the material used to aid in the formation of these channels must be beneficial or harmless to the injecting microorganisms, and for the purposes of the present invention to be a material that has no environmental impact or is biodegradable. Meet.

Next, the liquid decomposition material is supplied to the injection pipe 31, and suction is performed from the suction pipe 32. The injection in which a neutral detergent or soap is added as a surfactant for the purpose of increasing the permeability to the decomposition material liquid is more effective, and the pressure injection is more effective.

Completion of the supply of the microorganism-derived decomposition material into the channel is also confirmed by detecting the above-mentioned indicator substance on the suction pipe side.

These “implantation” → “channel formation”
→ "Injection" → "Injection liquid detection" → "Injection stop" as one cycle, after one cycle is completed,
At least one injection / supply pipe of interest is driven to the next depth, for example, at the location indicated by (2) in FIG.

The depth of one-time driving varies depending on the soil quality, the length of the strainer portion of the pipe, the target injection concentration of microorganisms, etc., but is selected in the range of about 30 cm to 2 m.

After that, the same operation is repeated to a desired depth in a deeper formation (3) or more in FIG. 3, for example. Although the injection and suction pipes are shown separately in the description, they can be alternately inverted, and the injection and suction can be inverted at each depth, and the inversion operation can be performed every time the depth is changed step by step. Can be selected at any time as required.

FIG. 4 is a plan view showing an example of applying the injection / suction pipe of the present invention to a contaminated site. FIG. 4A is a map showing the concentration of pollutants such that the pollutant has a pollutant source C as its apex and the polluted region spreads radially in the direction J of the groundwater downstream.

Each curve from a to e is a pollution isoconcentration line, and the concentration is a>b>c>d> e. In FIG. 4 (b), the pipe according to the present invention is provided as a boring well for injection and pumping up to B _{1 to} B _{N + 1} , and a group of a plurality of wells (for example, wells with an even subscript) is used as a suction well. , Place the other remaining well (well with an odd subscript) as an injection well,
It is shown that a microbial decomposition barrier layer can be formed on the downstream side of the groundwater flow of the pollution source C by injecting the decomposition liquid.

Further, FIG. 4C shows the injection for microbial decomposition over the entire surface in the concentration range of equal concentration d or more. In this example, the site surrounding the equal concentration range d is cut into meshes and pipes are arranged at each intersection (black circle).
Injection and suction are performed between adjacent pipes, and these injection and suction are appropriately switched to achieve a uniform decomposition material distribution in the plane and in the depth direction. It is also possible to change the size of the mesh according to the size of the distribution concentration, or change the injection amount and concentration.

[0073]

【Example】

Example 1 As a model test soil in a 5 m square concrete container, from the bottom, a fine sand layer 1.5 m, Kanto rom layer 1.5 m, Kanuma soil 1
m, and 0.5 m of Kuroboku soil were laminated, and the surface was covered with a clay layer of about 20 cm kneaded and solidified.

An injection well was placed 1 m from one corner on the diagonal line of the container, and a similar pipe was placed 1 m from the other corner of the vessel to place the pumping well. Outer diameter 30 mm, inner diameter 20 mm, female thread is cut into the inner diameter of the lower part of the pipe with a total length of 5 m, and a conical part with a tip of 60 degrees is attached with a screw here, and the maximum diameter of the conical part is 3
It was 6 mm. 3 within 50 mm above the screw part
A large number of mm holes were provided as a strainer. A small electrical conductivity measurement terminal and a simple optical detection terminal using an optical fiber were installed near the strainer in the suction side pipe. First, the pipe is driven for 1.5 m, the periphery of the pipe and the boundary between the soil and the container are firmly solidified with clay, the suction pipe side is evacuated for 20 minutes, and water containing 0.6 g / l of acetic acid is added from the injection pipe. Was injected and the electrical conductivity was measured. The electrical conductivity changed after 10 minutes, and when the steady value was reached at 15 minutes, the injection of the acetic acid solution was stopped and the microbial solution was injected. Microbial liquid is strain KK01 ( Ministry of International Trade and Industry
To Gakuin Institute of Technology on March 11, 1992 (date of original deposit)
Deposit number: FERM P-12869
, Deposited number under the Budapest Treaty, deposit number: F
The microorganism of ERM BP-4235 ) was cultured in M9 medium to prepare a decomposition solution so that the bacterial concentration was 10 ⁸ cells / ml. In this decomposed solution, food red No. 106 was used as an indicator substance.
It was dissolved at a rate of g / ml. 8 minutes after the suction was started, a change in the light amount occurred at the light detection terminal, and when the steady value was reached in 16 minutes, the operation was stopped. Next, the injection pipe and the suction pipe were pushed down 1.2 m and the same operation was performed. The channel formation and injection were confirmed when the electrical conductivity and the light amount reached steady values. The time required to complete the injection in this layer was 240 minutes. Both pipes were driven again for 1.5 m and the same operation was performed. The time required was 90 minutes. Three
After two injection cycles were completed, it was left for 2 days, half of the injected soil on the diagonal was removed, and the distribution of indicator substances and the distribution of microorganisms were observed. 70 to 90 cm, and a distribution of about 20 to 30 cm in the width direction are observed, while in the Kanto loam layer, the depth direction is 60 cm.
And the width was 15 cm. Example 2 In the same injection as in Example 1, when 1% by weight of soap was added to the water for forming the channel and the decomposition solution, one cycle completion time was 42 minutes with Kanuma soil, 180 minutes with loam, and fine sand. It's been 60 minutes.

[0075]

EFFECTS OF THE INVENTION By carrying out the present invention, it is possible to surely inject the decomposing solution of pollutants even in a non-uniform soil layer, and at the same time, in accordance with the depth direction and the pollution concentration. It was possible to carry out injection appropriately. Using this method, it became easy to design the in-situ restoration of the contaminated site. Furthermore, the construction is simple, and it is possible to perform purification with low energy without disturbing the groundwater vein, and it was possible to provide an effective method for purifying pollutants in situ under conditions close to nature.

[Brief description of drawings]

[Figure 1] Schematic diagram of soil pollution

FIG. 2 is a diagram showing the configuration of each unit of the pipe.

FIG. 3 is an explanatory diagram of injection and suction.

FIG. 4 (a) is a diagram for explaining pipe arrangement in a polluted area. (B) Diagram for explaining the pipe arrangement in the contaminated area (C) Diagram for explaining pipe arrangement in a contaminated area

[Explanation of symbols]

C pollution source D groundwater level E silty clay layer F gravel layer G sand layer H ROHM layer I soil (top soil) J Groundwater flow direction

Continuation of the front page (56) Reference JP-A-57-209692 (JP, A) JP-A-6-7764 (JP, A) JP-A-6-55153 (JP, A) JP-A-6-315674 (JP , A) JP-A-5-231086 (JP, A) JP-A-2-164936 (JP, A) Special table 4-501231 (JP, A) Special table 4-502277 (JP, A) Special table 6-506631 (JP, A) US Patent 5032042 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 3/00-3/34 B09C 1/00-1/10

Claims (7)

(57) [Claims] 1. A method of biologically degrading pollutants in soil in-situ, the biological degradation of pollutants in-situ being required for said biological degradation. Decomposition material is supplied into the soil, the decomposition material, in the form of a liquid, when supplied into the soil, respectively at least a pair of pipes capable of injecting or sucking the liquid, a pair of pipes, And a step of setting a predetermined depth in the soil, selected from the at least one or more pairs of pipes, using one of the pair of pipes as an injection pipe, the soil from the injection pipe A step of injecting a liquid decomposing material into the inside, and using the other pipe as a suction pipe to suck the liquid substance from the soil; pie By the step of detecting the decomposition material contained in the liquid material sucked by, in the detection step, at the time when the decomposition material contained in the liquid material at a predetermined concentration level is detected, A method of decomposing pollutants in situ, comprising the steps of injecting a liquid decomposing material using a pair of pipes and stopping suction of the liquid material. 2. After the step of stopping the injection / suction by the pair of pipes set to a predetermined depth in the soil, the pair of pipes selected in the injection / suction step are moved to move the soil. Decomposition of liquid into the soil from the injection pipe using the pair of pipes that have been reset to another predetermined depth that is different from the predetermined depth inside A step of injecting a filling material and sucking a liquid substance from the soil through the suction pipe; and a step of sucking the liquid substance through the suction pipe at the time of performing the injection / suction. A step of detecting the decomposition material, and in the detection step, when the decomposition material contained in the liquid material at a predetermined concentration level is detected, a liquid decomposition material utilizing the pipe pair Injection and suction of liquids And a step of stopping provided, and re-set to another predetermined depth, said decomposition material, as a liquid form, and performing the supply of the soil,
The method of claim 1. 3. The step of performing the injection / suction between the step of setting the pipe pair to a predetermined depth in the soil and the step of performing the injection / suction with the pair of pipes thereafter. Between a pair of pipes,
The method according to claim 1 or 2, further comprising the step of forming channels. 4. In the step of forming a channel between the pair of pipes, the formation of the channel is performed by sucking gas or liquid in the soil existing between the pair of pipes. The method of claim 3 characterized. 5. In the step of forming a channel between the pair of pipes, the channel is formed by injecting and sucking a gas or a liquid into the soil existing between the pair of pipes. Method according to claim 3, characterized in that it is done. 6. The detecting step, wherein the decomposition material contained in the liquid material is detected by detecting a pre-marked indicator substance in the injected liquid decomposition material. And
The method according to any one of claims 1 to 5. 7. The injected degrading material is at least one of a material derived from a microorganism having an ability to decompose the pollutant, an activity maintaining material for the microorganism, a survival material, and a growth material. 7. The method according to any one of claims 1 to 6, characterized in that