JP2005270695A - Method for cleaning contaminated material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for efficiently decomposing organic chlorine compounds such as dioxins by using micro-organisms and cleaning soil, or the like, contaminated with organic chlorine compounds. <P>SOLUTION: In the method for cleaning a material contaminated with organic chlorine compounds, micro-organisms are allowed to act on the organic chlorine compounds in the material to be treated and the organic chlorine compounds are biologically decomposed. Therein, the conditions of the water activity for suppressing the growth of methane formation bacteria is controlled to be ≤0.97 and it is preferable that the biological decomposition is performed by adding a composite micro-organismic agent comprising anaerobic micro-organisms and aerobic micro-organisms to the material to be treated. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for purifying a substance contaminated with an organic chlorine compound, and more specifically, an organic chlorine compound for purifying a substance such as soil or ash contaminated with an organic chlorine compound such as dioxins by the action of microorganisms. It is related with the purification method of the substance polluted by.

  Examples of microorganisms used for the decomposition treatment of organochlorine compounds such as dioxins include aerobic bacteria, anaerobic bacteria, basidiomycetes and the like. These microorganisms have different mechanisms for decomposing organochlorine compounds, and there are advantages and disadvantages in decomposing treatment due to their characteristics. For example, with regard to the degradation of dioxins, in certain aerobic bacteria, dioxygenase, which is an oxidase, can act on dioxins having a trichlorine value or less to degrade the skeletal structure. However, this kind of aerobic bacteria cannot act on high chlorine dioxins and cannot cope with all dioxins.

  In addition, certain anaerobic bacteria can dechlorinate dioxins harmlessly by reductively dechlorinating chlorine bound to the skeleton structure of dioxins using hydrogen. However, the dechlorination rate is slow and there is a concern that the treatment period may be prolonged.

  On the other hand, basidiomycetes, especially white-rot fungi, have high oxidative activity because the oxidase lignin peroxidase degrades the skeleton structure of dioxins. However, in the treatment of contaminated soil and the like, the indigenous bacteria in the soil have priority, so that the growth of basidiomycetes is suppressed and an effective decomposition treatment cannot be realized.

As a technique using aerobic bacteria, anaerobic bacteria, basidiomycetes, etc., in Patent Document 1 (dioxin reducing agent and dioxin reducing method using the same), dioxin by aerobic compost with an optimum temperature of 85 ° C. A class of decomposition processes has been proposed. In Patent Document 2 (composite effective microbial group-containing material), a large number of microorganisms that envisage the decomposition of dioxins are listed, and it is described that they are sprayed on soil or the like as a composite effective microbial group-containing material.

As a method for decomposing dioxins using basidiomycetes and incorporating pretreatment, Patent Document 3 (Method for purifying dioxin-contaminated soil) proposed a method for decomposing dioxins using wood composted with basidiomycetes. ing. Patent Document 4 (Purification Method of Chlorinated Dioxins Contaminated Soil) proposes a dioxins decomposition method in which basidiomycetes are added after suppressing the growth of indigenous bacteria in dioxins contaminated soil.

Further, in Patent Document 5 (water or soil purification method and microorganism group used in the method) and Patent Document 6 (organochlorine compound contaminated soil microorganism treatment method), anaerobic treatment is performed after anaerobic treatment. A method for purifying soil contaminated with an organic chlorine compound such as tetrachlorethylene has been proposed. These are devised as a method for decomposing volatile organic chlorine compounds having a relatively small number of chlorines (4 or less chlorine atoms) and cannot be applied to the decomposition of dioxins having 1 to 8 chlorine atoms.

JP 2001-29915 A Japanese Unexamined Patent Publication No. 2000-232728 JP 2000-107742 A JP 2001-162263 A JP 2000-102377 A Japanese Patent Laid-Open No. 10-34128

  As mentioned above, many proposals have been made for the biodegradation of dioxins. However, there are many types of microorganisms involved in the degradation and studies on the degradation mechanism, and the existence of microorganisms that compete with the microorganisms involved in the degradation. Consideration has not been made. For this reason, the conventional method for decomposing dioxins by microorganisms cannot be said to be sufficiently efficient, and a large part depends on the state of the target substance to be treated, and it takes a long time for processing. There was a problem.

  Accordingly, an object of the present invention is to provide a method for efficiently decomposing organic chlorine compounds such as dioxins using microorganisms and purifying soil contaminated with organic chlorine compounds.

  In order to solve the above-mentioned problem, the first aspect of the present invention is a water activity in which the growth of methanogens is suppressed in a method in which a microorganism is allowed to act on an organochlorine compound in a material to be treated and biologically decomposed. A method for purifying a substance contaminated with an organochlorine compound, characterized in that the treatment is performed in a controlled manner.

  According to this first aspect, by controlling the water activity conditions to suppress the growth of methanogens, the utilization of hydrogen by microorganisms having the ability to dechlorinate organochlorine compounds is promoted, and the efficiency of dechlorination Can be increased.

  In the second aspect of the present invention, the substance contaminated with an organic chlorine compound according to the first aspect is characterized in that the water activity at which growth of the methanogen is suppressed is 0.97 or less. It is a purification method.

  In the second aspect, the effect of the first aspect can be reliably obtained by adjusting the water activity to 0.97 or less.

  Further, the third aspect of the present invention is characterized in that, in the first aspect or the second aspect, the compound to be treated is added with a complex microbial agent containing an anaerobic microorganism and an aerobic microorganism. This is a purification method for substances contaminated with organochlorine compounds.

  In this third aspect, by adding the complex microbial agent, it is possible to increase the initial number of microorganisms involved in the decomposition of the organochlorine compound and shorten the treatment period.

  ADVANTAGE OF THE INVENTION According to this invention, the biological treatment of the organochlorine compound in to-be-processed substances, such as soil, can be performed efficiently by control of water activity conditions.

<Purification target>
Examples of substances to be treated by the method of the present invention include soil containing organic chlorine compounds, incineration ash, sludge and the like. Organochlorine compounds to be decomposed / removed are mainly dioxins such as polychlorinated dibenzodioxins (PCDD) and polychlorinated dibenzofurans (PCDF), including, for example, coplanar PCB (Co-PCB). Organic chlorinated solvents such as PCBs, tetrachlorethylene and trichlorethylene can also be targeted.

<Microorganism> The microorganism used for purification is not particularly limited as long as it has a resolution for an organic chlorine compound. The anaerobic microorganism or aerobic microorganism having a resolution of organochlorine compounds is not limited to a single species, and a group of microorganisms including a plurality of species and strains can also be used. These microorganism groups can be collected from soil contaminated with organochlorine compounds by a known screening method, so that they can be cultured and used as seeds. Needless to say, known microbial species, strains, fungal groups and the like that are known to have a decomposing activity for dioxins and the like can be used within a range compatible with the method of the present invention.

Representative examples of anaerobic microorganisms with the ability of organochlorine compounds are anaerobic archaea such as the genus Methanobacterium, Methanosarcina, and Methanolobus, and Acetobacterium. Genus, Desulfobacterium genus, Desulfomonile genus, Dehalospirillum genus, Dehalobacter genus, Dehalobacterium genus, Dehalococcoides genus, Clostridium ) In addition to anaerobic bacteria such as genus, Citrobacter genus, Escherichia genus, Enterobacter genus, Serratia genus, Proteus genus, Shewanella genus, staphylo Coccus (Staphylococcus) genus Mention may be made of facultative anaerobic bacteria.

Representative examples of aerobic microorganisms capable of decomposing organochlorine compounds include the genus Sphingomonas, Burkholderia, Ralstonia, Pseudomonas, Nocardioides. ) Genera, Rhodococcus genera, Terrabacter genera and the like.

In addition, for example, Escherichia, Enterobacter, Citrobacter, Clostridium, and the like are acid-fermenting bacteria that produce acid from organic substances such as glucose.

<Water activity>
Water activity (Aw) is one of relative humidity display methods and is defined by the following equation.
Aw = P / P ₀
Where Aw: water activity,
P: water vapor pressure of the object,
P ₀ : Saturated water vapor pressure at the same temperature as P.

  Water is indispensable for microorganisms to maintain their survival. On the other hand, microbial cells are separated from the surrounding environment by a cell membrane, and live and act while maintaining an appropriate pressure balance with the surrounding environment. However, when the solute is dissolved in the water present in the surrounding environment, the osmotic pressure outside the microbial cell increases, causing protoplasm separation and failing to maintain vital activity. The state of water in the surrounding environment (the ratio of free water that can be used by microorganisms) can be expressed by water activity, and the water activity suitable for maintaining life activity differs depending on the microorganism species.

The present invention allows the dechlorination of the anaerobic microorganisms to proceed efficiently by controlling the water activity conditions under which the growth of methanogens is suppressed, thereby effectively increasing the dechlorination rate. Can be improved. It is considered that dechlorination of organochlorine compounds by anaerobic bacteria is mainly a reductive dechlorination reaction using molecular hydrogen as an electron donor. Although this molecular hydrogen can be supplied by gas, hydrogen generated by the action of acid-fermenting bacteria or the like can be used practically. That is, it is desirable to add an organic substance to a mixture of microorganisms involved in the decomposition of a substance to be treated and an organochlorine compound, to produce hydrogen by metabolic activities such as acid-fermenting bacteria under anaerobic conditions, and to use this hydrogen.

For example, when the organic substance is glucose, hydrogen is produced by acid-fermenting bacteria as shown below under anaerobic conditions.
3C ₆ H ₁₂ O ₆ → 4CH ₃ CH ₂ COOH + 2CH ₃ COOH + CO ₂ + 3H ₂
CH ₃ CH ₂ COOH + 2H ₂ O → CH ₃ COOH + CO ₂ + 3H ₂
C ₆ H ₁₂ O ₆ → CH ₃ (CHOH) ₂ CH ₃ + 2CO ₂ + H ₂
C ₆ H ₁₂ O ₆ → CH ₃ (CH ₂ ) ₂ COOH + 2CO ₂ + 2H ₂
Anaerobic bacteria having a dechlorination function use this hydrogen to desorb chlorine from organochlorine compounds. That is, dechlorination of organochlorine compounds by anaerobic microorganisms can be achieved by generating hydrogen by acid fermentation of organic matter or the like under anaerobic conditions and using this effectively.

On the other hand, under anaerobic conditions, methanogens produce methane from the metabolites of acid-fermenting bacteria as follows.
CH ₃ COOH → CH ₄ + CO ₂
4H ₂ + CO ₂ → CH ₄ + 2H ₂ O
Here, the methanogen is, for example, a microorganism such as Methanobacterium, Methanococcus, Methanospillium, or Methanosarcina.

  As a result, the hydrogen produced by the acid-fermenting bacteria is used competitively between the dechlorination of the organochlorine compound and the methane production. This is considered to be one of the causes of the slow dechlorination rate in the conventional biological treatment. Therefore, in order to efficiently advance the dechlorination reaction of the organic chlorine compound under anaerobic conditions, it is necessary to inhibit methane production, which is a competitive reaction of the dechlorination reaction.

  The present invention has been made by paying attention to the knowledge that the methanogen does not grow well under a water activity of 0.97 or less. For this purpose, by reducing the water activity to 0.97 or less under anaerobic conditions in the solid phase system containing the substance to be treated, the organic chlorine is not consumed by methane fermentation without consuming hydrogen produced by acid fermentation of organic matter. It is actively used for dechlorination of compounds to promote biodegradation.

  The cell membrane of the methanogen that competes with the dechlorination reaction is based on the ether skeleton of glycerol and isoprenoid alcohol. On the other hand, the cell membrane of acid-fermenting bacteria (for example, Escherichia) has an ester bond between glycerol and a fatty acid as a basic skeleton. Therefore, the cell membrane structure of methanogens has the characteristic of being less resistant to osmotic pressure than acid-fermenting bacteria.

  In addition, methanogens do not have a peptidoglycan layer (murein cell wall) which is one of the bacterial cell surface layers. On the other hand, since acid-fermenting bacteria have a peptidoglycan layer, and this layer wraps cells, it can withstand strong osmotic pressure and maintain its form.

  For these reasons, methanogens are considered to be a very sensitive group for osmotic pressure, and when water activity is low, methanogens with low tolerance to high osmotic pressure cannot grow. As a result, methane fermentation is suppressed, and hydrogen is accumulated without being used for methane fermentation. Even if the water content in the material to be treated is high, the osmotic pressure increases as the water activity decreases.

  On the other hand, acid-fermenting bacteria involved in dechlorination have a peptidoglycan layer (murein cell wall) even with a low water activity (eg, Aw ≦ 0.97) that suppresses the production of methanogens, so Not easily affected. For this reason, there is no influence on the growth activity of the bacteria involved in dechlorination, and the dechlorination reaction proceeds by contact with hydrogen. Thus, dechlorination of an organic chlorine compound can be achieved efficiently by utilizing the difference in water activity conditions that differ depending on the microorganism.

  The water activity can be controlled to a predetermined level by, for example, an organic acid (including an organic acid generated by metabolic activity of a microorganism), NaOH added for the purpose of pH adjustment, calcium carbonate, or the like. In other words, in this case, organic acids, NaOH, etc. act as solutes, reducing the amount of free water in the reaction field where biodegradation of organochlorine compounds occurs (where contact between microorganisms and organochlorine compounds occurs), resulting in water activity Acts to lower the Therefore, by adjusting the water content of the reaction field and the amount of solutes such as organic acids, the desired water activity level can be controlled.

  In addition, for example, the water activity can be controlled by adding a substance capable of reducing the amount of free water in the reaction field to the material to be treated as a water activity control agent.

<Composite microbial agent>
In the purification method of the present invention, it is preferable to add a group of microorganisms containing anaerobic microorganisms and aerobic microorganisms to the substance to be treated. By adding the microorganism group and increasing the number of initial bacteria and the type of bacteria, the decomposition of the organic chlorine compound can be accelerated and the purification time can be shortened.

  As the microorganism group, a mixture of the above-exemplified microorganism species can be used, and a complex microorganism agent produced by alternately repeating anaerobic conditions and aerobic conditions can be used. Complex microorganism agents by culturing and growing anaerobic microorganisms and aerobic microorganisms with organic chlorine compounds such as organic matter and dioxins in a cycle (anaerobic-aerobic cycle) that switches between anaerobic and aerobic conditions alternately Anaerobic microorganisms and aerobic microorganisms contained in can be used in a fully acclimatized state.

<Outline of Process> In a preferred embodiment of the purification method of the present invention, a composite microorganism agent containing an anaerobic microorganism, an aerobic microorganism, an organic matter derived from an organic waste, or the like is added to a material to be treated contaminated with an organic chlorine compound. Mix and place under micro-aerobic conditions while controlling to water activity conditions (eg 0.97 or less) that suppress the growth of methanogens, or alternately repeat anaerobic and aerobic conditions As a result, an anaerobic microorganism and an aerobic microorganism are allowed to act on the organochlorine compound to perform a decomposition treatment. The water activity is preferably controlled to a water activity condition (for example, 0.97 or less) in which the growth of the methanogen is suppressed from the start of the treatment, but from the time when the water activity is reached after a certain time has elapsed from the start of the treatment. The water activity may be controlled over a predetermined period.

The outline of the process of the present invention is shown in FIG. 1 together with the preparation procedure of the complex microbial agent. I. Preparation of complex microbial agent: First, the complex microbial agent used in the process is to place anaerobic and aerobic microorganisms in microaerobic conditions in the presence of organic matter, or anaerobic and aerobic conditions. It is obtained by acclimatizing while alternately repeating. Preparation of a complex microbial agent can be performed using a microbial agent production apparatus. The microbial agent production apparatus is composed of a single tank or a tank divided into a plurality of tanks, and continuously composts organic matter such as garbage and dock food that are periodically added and fed by a composting method. For the preparation of this complex microbial agent, soil contaminated with dioxins, bottom mud, compost, etc. or soil, bottom mud, compost etc. not contaminated with dioxins were collected and adapted to organic matter such as garbage Can be used as an inoculum.

During the composting process, the atmosphere in the microbial agent production apparatus is placed in slightly aerobic conditions, or alternately anaerobic and aerobic conditions, and both anaerobic microorganisms and aerobic microorganisms are proliferated. Make it.

The microaerobic condition can be maintained by ventilating N ₂ gas, controlling the stirring frequency, or opening the sealed device periodically (for example, once a day). For example, the microaerobic condition can be realized by blowing N ₂ gas with moderate stirring and adjusting the oxygen concentration in the microbial agent production apparatus to 0.05 to 0.1 v / v%. Even at this concentration, an oxygen concentration sufficient for the metabolic activity of aerobic microorganisms can be supplied.

In order to make it an anaerobic condition, deaeration may be performed, but an anaerobic state can be usually created by standing for a certain period of time. On the other hand, aerobic conditions can be created by operations such as stirring and aeration. Therefore, by performing the operation for creating the aerobic condition intermittently, it is possible to create a processing environment in which the anaerobic condition and the aerobic condition are repeated alternately. More specifically, for example, an environment in which anaerobic conditions and aerobic conditions are alternately repeated can be created by stirring for about 5 minutes per hour and allowing the remaining 55 minutes to stand.

The water content of the mixture to be treated in the microbial agent production apparatus is preferably set to be 30 to 60% by weight, and the optimum range is 35 to 45% by weight. Moreover, it is preferable to make it the temperature in a microorganism agent manufacturing apparatus become 10-70 degreeC during a process, and the optimal range is 25-55 degreeC. Furthermore, it is preferable to adjust the pH of the mixture to be treated in the microbial agent production apparatus to be pH 6 to 9, and the optimum range is pH 7.5 to 8.5. In addition, while adding organic substance, pH fall (about pH 6) is seen at the initial stage, but it becomes stable between pH 7 and 9 as the number of days elapses. Therefore, although it is not necessary to adjust the pH in particular, if the pH changes beyond the range of pH 6-9, the pH can be appropriately adjusted with 6N-dilute sulfuric acid, 4N-caustic soda solution, or the like. Active growth and metabolic activity can be maintained by adjusting the water, temperature, and pH, which are basic conditions for microbial growth, to the above ranges.

The above operation has the effect of culturing and proliferating a large amount of anaerobic and aerobic microorganisms, which are inoculums, in complex microbial agents. Can be increased. In addition, since the inoculum uses a complex microbial system in nature or contaminated soil, it is not driven out by indigenous bacteria in the soil.

In addition, by controlling the water activity to a level (0.97 or less) in which the growth of methanogenic bacteria is suppressed in the preparation process of the complex microbial agent, the ratio of methane bacteria in the complex microbial agent may be reduced. It is valid.

II. Purification of substance to be treated: In the process of FIG. 1, the composite microbial agent obtained as described above is sent to a pollutant purification device. As the pollutant purification device, a device composed of a single tank or a plurality of divided tanks can be used as in the microbial agent production apparatus.

In the pollutant purification device, the complex microbial agent and the material to be treated such as soil contaminated with dioxins are mixed, and the water activity is controlled to a level (0.97 or less) at which the growth of methanogens is suppressed. While processing. Moreover, it is also possible to add an appropriate amount of a neutralizing agent, a decomposition base material such as a wood chip that serves as a base material for microbial activity, and an organic substance such as garbage or a dock food that can serve as a carbon source, if necessary.

Moreover, when the to-be-processed substance is incineration ash, since it is alkaline fundamentally, it is preferable to adjust to pH 9 or less, for example, pH 7.5-8.5 before addition.

During the treatment in the pollutant purification apparatus, anaerobic microorganisms and aerobic microorganisms are allowed to act on the organochlorine compound while being placed in slightly aerobic conditions or alternately repeating anaerobic conditions and aerobic conditions. In addition, it is preferable to set so that the moisture content of the mixture processed in a contaminant purification apparatus may be set to 30 to 60 weight%, and the optimal range is 35 to 45 weight%.

The setting of the microaerobic condition or the anaerobic condition and the aerobic condition in the treatment with the pollutant purification apparatus can be performed in the same manner as the treatment with the microbial agent production apparatus. That is, the microaerobic condition can be maintained by ventilating N ₂ gas, controlling the stirring frequency, or opening the sealed device periodically (for example, once a day). For example, the microaerobic condition can be realized by blowing N ₂ gas with moderate stirring and adjusting the oxygen concentration in the pollutant purification apparatus to 0.05 to 0.1 v / v%. Even at this concentration, an oxygen concentration sufficient for the metabolic activity of aerobic microorganisms can be supplied.

Further, the atmosphere setting, the water content and pH of the contents, the treatment temperature, etc. in the pollutant purification device can be carried out in the same manner as in the treatment with the microbial agent production device.

By continuing the above operation until the water activity is controlled to 0.97 or less until the concentration of the pollutant in the material to be treated is below the environmental standard, the organic chlorine compound is decomposed and the material to be treated is removed. It can be reliably purified.

  In the present invention, anaerobic conditions are required in the process of causing microorganisms to act on organochlorine compounds. However, this does not necessarily mean that the substance to be treated is placed in a completely anaerobic atmosphere. For example, when adding a compost-like complex microbial agent containing bacteria having the ability to dechlorinate dioxins to soil contaminated with dioxins, the water content is preferably set to 30 to 60% In addition, this mixture is in a solid phase, and even in an air atmosphere, the portion away from the portion in contact with air and the inside of the lump are in an anaerobic state in which oxygen is extremely limited, and dechlorination proceeds.

EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in more detail, this invention is not restrict | limited at all by this.
Example 1
The soil contaminated with dioxins, compost (composite microbial agent) whose dioxins were decomposed in advance, and wood chips were mixed at a weight ratio of 1: 1: 1, and the content was adjusted to 40%. . Thereafter, 1200 g of the mixture is put into a 5 L container having a gas phase outlet and a stirring blade for stirring the object to be processed, and a stirring operation is performed as appropriate, and nitrogen gas is passed through at 1 L · min ^−1. However, dog food was added as an organic substance at a load of 5 g · day ⁻¹ , and the treatment was performed for 3 months while maintaining a temperature of 25 ° C.

  During the 3 month treatment period, 3N NaOH was added in a timely manner to maintain the pH at 6-8. The water activity was adjusted with an organic acid produced by the input organic substance and NaOH added for pH adjustment. At the start of the treatment, the value of water activity 0.988 was less than 0.97 after 10 days, so this point was taken as the experiment start point. Thereafter, the water activity changed within the range shown in Table 1 and FIG.

  As a result of analyzing the residual dioxin concentration in the treated material based on "Soil Survey and Measurement Manual for Dioxins" (Environment Agency, Water Quality Conservation Bureau, Soil Agricultural Chemicals Division; issued in January 2000) became. Three months later, the initial value of 53.0% of dioxins was decomposed.

Comparative Example 1
Mixing soil contaminated with dioxins, pre-composted dioxin decomposition ability, and wood chips at a weight ratio of 1: 1: 1, and maintaining a moisture content of 55% to maintain high water activity after adjusting the mixture 1200 g, inlet and outlet opening of the gas phase, and treated stirring blade was placed in a container having an inner volume of 5L having an organic matter to 5 g · ^{day -1} with a stream of nitrogen gas at 1L · ^{min -1} And the treatment was carried out for 3 months while maintaining a temperature of 25 ° C. During this time, 3N NaOH was added in a timely manner to maintain the pH at 6-8.

  Although the water activity was 0.993 at the start of the experiment, it decreased with the generation of organic acid and the addition of NaOH with the start of the experiment, and was 0.975 after 3 months. However, in Comparative Example 1 in which the water activity was performed without control, the water activity did not fall below 0.97 during the experiment period. The transition of water activity is also shown in Table 1 and FIG.

  As a result of analyzing the residual dioxin concentration in the treated product based on “Soil Survey and Measurement Manual for Dioxins” (Environment Agency, Water Quality Conservation Bureau, Soil Agricultural Chemicals Section; issued in January 2000), the results are shown in Table 3. there were. After 3 months, the initial value of 36.6% of dioxins was decomposed.

Reference example Correlation between water activity and methane production:
6 kg of wood chips were put into the garbage processing machine, 0.7 kg (wet weight) of garbage was put in every day, and it was operated for several months. After 7 days, 14 days, 30 days and 60 days from the start of operation, 500 g of the object to be processed in the processing machine was collected and cultured in an anaerobic bottle for 1 week. The temperature at this time was 37 ° C., and the gas phase in the upper part of the anaerobic bottle was replaced with a gas of 20% hydrogen and 80% nitrogen.

  Methane generated in the upper gas phase in the anaerobic bottle after 1 week of culture was measured by gas chromatography, and expressed as a relative ratio with the generation amount of the 7-day sample as 100%. The results are shown in Table 4.

  From this test result, it can be seen that the amount of generated methane is greatly influenced by the water activity, and when the value falls below 0.97, it rapidly decreases.

  The present invention has been described above with reference to various embodiments. However, the present invention is not limited to the above embodiments, and can be applied to other embodiments within the scope of the invention described in the claims. It is.

  INDUSTRIAL APPLICABILITY The present invention can be used for purification of soil or ash contaminated with organochlorine compounds such as dioxins.

It is drawing which shows the outline | summary of a soil purification process. It is a graph which shows transition of the water activity in Example 1 and Comparative Example 1.

Claims (3)

In a method of causing a microorganism to act on an organochlorine compound in a material to be treated and biologically decomposing it,
A method for purifying a substance contaminated with an organochlorine compound, wherein the treatment is performed by controlling the water activity so that the growth of methanogens is suppressed.   2. The method for purifying a substance contaminated with an organochlorine compound according to claim 1, wherein the water activity that suppresses the growth of the methanogen is 0.97 or less.   The method for purifying a substance contaminated with an organochlorine compound according to claim 1 or 2, wherein the substance to be treated is treated by adding a complex microbial agent containing anaerobic microorganisms and aerobic microorganisms. .

Images