JP2003334061A - Organochlorine compound decomposing material, method for producing the same and soil cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an organochlorine compound decomposing material for effectively decomposing organic chlorine compounds in soil, especially dioxins and to provide a method for producing the same. <P>SOLUTION: The decomposing material is obtained by firstly mixing cow manure with sawdust, etc., adding a soil microorganism group to the mixture, fermenting the mixture to prepare a mushroom bed, then mixing the mushroom bed with about 1 wt.% of a medium containing a basidiomycete such as Coriolus versicolor, etc., growing mycelia and composting the mixture while keeping the mushroom bed at about 70% water content at about 28°C for 20-25 days to prepare the decomposing material. Soil contaminated with the dioxins is excellently mixed with the decomposing material and allowed to stand so that the dioxins in the soil are decomposed in a high decomposition ratio to make the dioxins harmless. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organic chlorine compound,
In particular, it relates to an organic chlorine compound decomposing material for decomposing dioxins and a method for producing the same. Further, the present invention provides
The present invention relates to a method for purifying organic chlorine compound-contaminated soil, particularly dioxins-contaminated soil, using the above-mentioned organic chlorine compound decomposition material.

[0002]

2. Description of the Related Art Organic chlorine compounds, particularly dioxins, are said to be highly toxic, and are chemically stable and difficult to decompose naturally, so they are regarded as environmental pollutants. Dioxins may be contained in industrial waste, combustion ash thereof, or the like, because dioxins may be produced in the process of manufacturing chemical substances or the process of burning waste. If these are discarded in soil, for example, the soil may be contaminated with dioxins, which may have a large impact on the environment.

In recent years, various measures have been taken to prevent the generation of dioxins as described above. For example, in a combustion furnace, it is a means of sufficiently mixing a combustion product with air and burning it for a long time while maintaining a high combustion temperature. However, if soil has already been contaminated with dioxins, it is difficult to decompose it effectively. For example, there is a method of decomposing using an oxidizing agent, but it cannot be said to be sufficiently safe and effective.

On the other hand, as a method for decomposing environmental pollutants to render them harmless, a method called bioremediation (or bioremediation) has recently been attracting attention. This method can be used, for example, in filamentous fungi (molds), bacteria,
This is a method of degrading the pollutants by using microorganisms such as fungi to render them harmless. Since no chemical is used, the cost is low and the safety is high.

In order to decompose dioxins, it is considered to be particularly effective to utilize a microorganism having a lignin degrading ability. Lignin is naturally contained in large amounts as a substance constituting the cell wall, especially in the xylem of plants. Lignin is not as toxic as dioxins, but has a chemical structure similar to dioxins and is persistent. In fact, an example of decomposing dioxins in a liquid using a microorganism having a lignin degrading property has been reported (JP-A-11-341978, etc.).

Basidiomycetes are a typical microorganism having a lignin degrading ability, and among them, white wood decay fungi have a high lignin degrading ability. A method for decomposing dioxins has been disclosed in which basidiomycetes, particularly white wood-destroying fungi, are grown on a bed of wood or the like to be composted, and the compost is brought into contact with contaminated soil (JP-A-11-319786 and JP-A-2000). -107742). Since the fungus bed contains nutrients of white wood-rotting fungi, it has been shown to be advantageous for growth in soil rather than mixing only white wood-rotting fungi into soil.

[0007] However, specific experimental data showing that the decomposition of dioxins in soil has reached a level sufficient for practical use in the field is not yet included in the above-mentioned documents. It is considered that this is because the growth of white wood-destroying fungi is hindered by soil microbial groups, especially bacteria, in the soil. In fact, as a cause of failure in culturing a strain of white wood-destroying fungus collected outdoors, there are many cases where the hybrid bed and the like are mixed in the fungus bed.

Under the above circumstances, there is a strong demand for a method of effectively decomposing dioxins in soil to render them harmless.

[0009]

Therefore, an object of the present invention is to provide an organochlorine compound decomposing material for effectively decomposing organochlorine compounds, especially dioxins in soil, and a method for producing the same. .

[0010]

In order to solve the above problems, the method for producing an organochlorine compound decomposing material of the present invention is a production method including the following steps. (1) A step of producing a fungus bed by fermenting a composition containing at least animal feces and dead plant tissue with a soil microorganism group and setting the C / N ratio to 30 to 35. (2) A step of growing basidiomycetes in the fungal bed.

The organic chlorine compound decomposing material of the present invention (hereinafter sometimes simply referred to as "decomposing material") is produced by composting a composition containing at least animal feces and dead plant tissue by the above method. As a result, organic chlorine compounds, especially dioxins, can be effectively decomposed in the soil. The term “compost” is a general term for products produced by fermenting animal feces, wood, straw, hay and the like with microorganisms, and is a term commonly used by those skilled in the art. Further, in the present invention, the term “proliferation” means that, with regard to basidiomycetes, the hyphae mainly extend and spread in the fungal bed or the soil.

If the C / N ratio of the fungal bed is higher than the above range, the soil microorganisms do not sufficiently act and the fermentation rate is slow, which is unsuitable. Further, if the C / N ratio is smaller than the above range, the activity of the soil microbial group becomes excessive, the ammonia odor becomes strong, and the composition is decomposed in some cases, and harmful amines are generated, which is inappropriate. Is.

In the present invention, the C / N ratio is measured as follows. That is, first, the total carbon content R _C (% by weight) in the sample is determined by the so-called Thuring method. The Turin method is a method in which a sample is heated by oxidation with potassium sulfate chromate and oxidized, and the amount of consumed chromate ion is determined by redox titration. Next, the total nitrogen content _RN (% by weight) of the same sample as above is determined. That is, first, a nitrogen-containing organic substance in a sample is decomposed with sulfuric acid to generate ammonia nitrogen, and the ammonia nitrogen is quantified using a distillation method. Rate R
_{Calculate N1} (% by weight). Next, for similar samples,
By extracting nitrate nitrogen with water, decolorizing the extract, and quantifying the nitrate nitrogen, the nitrate nitrogen content R _N2
(% By weight) is calculated. Then, the target C / N ratio R _CN is obtained by the following equation (1). R _CN = R _C / R _N = R _C / (R _N1 + R _N2 ) (1)

Further, in the present invention, "dioxins"
And polychlorinated dibenzoparadioxins (PCDD
s), at least one compound selected from the group consisting of polychlorinated dibenzofurans (PCDFs) and coplanar PCBs (Co-PCBs). It has been reported from animal experiments that many of these compounds cause a decrease in thyroid function, a decrease in reproductive organ weight or spermatogenesis, a decrease in immune function, and the like. Furthermore, compounds having the same toxicity as the isomers and homologues of the above dioxins are also included in the scope of the present invention.

The basidiomycetes are preferably white wood-destroying fungi because they have a high lignin degrading ability.

The present inventor makes the basidiomycete and the soil microorganism group coexist in the degrading material in advance by the method of the present invention, and even if the degrading material is mixed in the soil, the basidiomycete and the soil microbial group become It was found that they can grow while coexisting.

In addition, the white wood-destroying fungus normally grows only in wood in its natural state, but a composition containing the animal feces and dead plant tissue is fermented with a soil microbial group to use a fungal bed. The present inventor has confirmed that it is possible to grow effectively. Moreover, the decomposed material of the present invention thus produced, when mixed in the soil, is less likely to be hindered by the soil microbial community to inhibit the growth of white wood-destroying fungi, as compared with the conventional compost using only wood. . Therefore, organic chlorine compounds, especially dioxins, can be decomposed and detoxified in soil very effectively.

The white wood-destroying fungus is of the genus Kawaratake ( Co
riolus ) is at least one selected from
It is more preferable because the lignin resolution is particularly high. Examples of white wood-destroying fungi belonging to the genus Kawaratake include Coriolus hirsutus .

The basidiomycete used in the present invention may be a natural strain or a strain which has been genetically modified so as to enhance the ability to decompose dioxins.
Even if a natural strain is used, sufficient dioxin-decomposing ability can be obtained. In addition, if a natural strain is used, there is no risk of the genetic modification affecting the environment. Regarding natural strains, vegetation may differ due to differences in latitude and the like, so that the effect may slightly vary, but normally, natural strains of the land can be used.

As the animal dung, livestock dung is preferable because it is easily available and suitable for the growth of basidiomycetes.
More preferably, it is at least one selected from the group consisting of pig dung and chicken dung. Particularly preferred is cow dung.

The dead plant tissue is preferably at least one selected from the group consisting of wood, straw and hay, and it is more preferable to contain wood because it is suitable for the growth of white wood-destroying fungi. . In addition, it is preferable to use these plant tissues in a finely pulverized state (that is, in the case of wood, in a state of sawdust) because the basidiomycete growth in the fungal bed becomes faster. In addition, it is preferable that the type of wood is appropriately selected according to the type of basidiomycete, and if it is of the genus Kawara, a broad-leaved tree is preferable. The type of hardwood is not particularly limited.

In the step (1), the content of animal feces in the composition is 80 to 90% by weight, and the content of dead plant tissue is 10 to 20% by weight until completion of preparation of the bacterial bed. Is preferable because the time is short and the step (2) can be smoothly performed. Further, the composition may contain an optional component other than the above components within a range in which the object of the present invention can be achieved. The content of this optional component is preferably 0 to 10% by weight.

In the step (2), the basidiomycete is proliferated after mixing the stem tissue of the plant into the fungal bed,
It is preferable because the growth of basidiomycetes is further promoted. The plant is preferably a wild plant. The type of wild plant is not particularly limited, but in general, a stem tissue having a high physical strength, that is, a cell wall having a strong cell wall is preferable because of a high lignin content.

It is preferable that the soil microorganism group includes bacteria, filamentous fungi and actinomycetes. The filamentous fungi have the same meaning as molds.

The decomposing material of the present invention has a high organochlorine compound decomposing ability by being manufactured by the above manufacturing method, but may be manufactured by a manufacturing method other than the above. Also,
Since the decomposing material of the present invention has a particularly high resolution of dioxin, it is preferably used for decomposing dioxin.

The decomposing material of the present invention can effectively decompose the organochlorine compound in the soil by contacting it with the soil contaminated with the organochlorine compound, particularly dioxins. At this time, it is preferable to mix the decomposing material of the present invention with soil contaminated with an organic chlorine compound. Also,
At this time, it is preferable to mix the plant tissue with the soil because the growth of basidiomycetes in the soil is further promoted. The plant is preferably a wild plant. The type of wild plant is not particularly limited, but in general, a stem tissue having a high lignin content as described above is preferred because the hyphae extend at a high rate and spread uniformly. In addition, hay strips, various tree twigs, rice straw, etc. can also be used.

The method for purifying contaminated soil according to the present invention is a method including decomposing organic chlorine compounds in soil by the method for decomposing organic chlorine compounds using the decomposing material according to the present invention. With this configuration, the method for purifying contaminated soil according to the present invention can effectively purify soil contaminated with organic chlorine compounds.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described.

The method for producing a decomposed material of the present invention can be carried out, for example, as follows. First, basidiomycetes are cultured. This culture method is not particularly limited, flask culture, sawdust medium culture, agar culture using a petri dish, etc.
Known methods can be used. Flask culture and sawdust medium culture are suitable for practical-level culture, and agar culture is suitable for experimental-level culture, for example, enzyme activity measurement of basidiomycetes. The culture temperature and period depend on the kind of basidiomycete, but are, for example, 25 to 30 ° C. and 2 to 6 weeks.
The method for obtaining the basidiomycetes is not particularly limited, but for example, when the basidiomycetes are to be used for the soil remediation work for dioxins, it is preferable to collect them in a forest as close as possible to the construction site.

Next, a composition containing animal feces and the like is prepared and further fermented with a soil microorganism group to prepare a basidiomycete growth fungal bed. That is, first, animal feces are mixed with dead plant tissue, such as sawdust, and, if necessary, optional components to prepare the composition. The content ratio of each component is preferably within the above range. Here, as animal feces, new ones may be used, but sawdust may be added in advance and left still for about 3 to 4 months, for example.

In the composition just after mixing, the C / N ratio is not particularly limited, but is preferably 20 to 40. The water content is not particularly limited, but is, for example, 60 to 7
It is 0% by weight, preferably 65% by weight. This water content can be adjusted mainly by increasing or decreasing dead plant tissue, for example, sawdust, and water may be added if necessary. The water content is measured as follows. That is, 2 to 5 g of a sample is precisely weighed and its weight M ₁ is determined. Next, the moisture content was completely removed by circulation drying with warm air, and the weight M ₂ after cooling for 30 minutes in a desiccator was measured, and the moisture content W was calculated by the following formula (2).
(% By weight) is calculated. W = ((M ₁ −M ₂ ) / M ₁ ) × 100 (2)

The optional component is not particularly limited as long as it is a substance that does not inhibit fermentation by soil microorganisms and growth of basidiomycetes, and any substance may be added, including nutrients of those microorganisms, particularly carbohydrates. It is preferable. As the optional component, for example, raw garbage (food waste) from households, rice, rice cake, rice porridge and the like can be used. If these are added excessively, it is not preferable because the C / N ratio is increased, the input is agglomerated (becomes a solid and large lump), or sludge is made (a mucous liquid) and the fermentation does not proceed. There is usually no problem if it is within the range of rates. Further, since the salt content and the lipid are not essential for the reproduction of the above-mentioned microorganisms, it is preferable that their content rates are as low as possible. If the content of salt or lipid in the optional component is too high, the growth of microorganisms is inhibited, but it is usually no problem if the content is 2.5% or less and 3% or less of the optional component, respectively. In addition, when the composition contains a fragment having a large component to be mixed, it is preferable to pulverize the composition with a crusher or the like before mixing.

Then, an inoculum containing a soil microbial group is further added to the above composition, and the mixture is sufficiently stirred using an apparatus for treating garbage, for example, BGD-10 (trade name) manufactured by Hitachi Ltd. The amount of inoculum added is not particularly limited, but for example, 10 to 30% by weight of the composition is preferable because the fermentation by the soil microorganisms is carried out smoothly. The addition amount may be less than 10% by weight, but if the addition amount is too low, fermentation is difficult to carry out, which is not preferable. The inoculum is not particularly limited,
Any substance containing an appropriate microbial group may be used, but it can be obtained as follows, for example. That is, first,
Cow dung and the garbage as described above are mixed and stirred at a weight ratio of 80:20, for example. The C / N ratio of this mixture is not particularly limited, but is preferably about 25, for example, because the propagation of microbial groups proceeds smoothly. The water content is not particularly limited, but is adjusted to 65% by weight, for example. Then, the mixture is deposited in the field soil and allowed to stand for about 2 months, and the cow dung-derived microorganism group and the soil-derived microorganism group are propagated in the mixture in a well-balanced manner to form a compost.

The inoculum preferably contains bacteria, filamentous fungi and actinomycetes as a soil microorganism group. The rotation speed at the time of stirring is not particularly limited, but usually 5 to 6
Rotations / minute. If the rotation speed is too high, the hyphae of the filamentous fungus may be cut off, and the composition may not be fermented. Further, if the rotation speed is too slow, stirring cannot be performed effectively. The stirring time is also not particularly limited, but stirring for 20 minutes or more is usually sufficient. The temperature inside the container at the time of stirring is not particularly limited, but is usually room temperature of 10 ° C. or higher. If the temperature is too low, for example, at 7 ° C. or lower, it becomes difficult to perform fermentation by soil microorganisms,
In winter, it is preferable to stir while appropriately heating with a heater.

Next, the composition is fermented. First,
The composition is transferred into a fermenter prepared in advance.
This device will be described with reference to FIG. Figure 1 (c)
Is a top view of this device. 1 (a) and (b)
[Fig. 3] is a cross-sectional view of the device cut along cutting planes AA 'and BB'. As shown in the figure, this device mainly comprises a container 1 having a floor and a wall for enclosing the composition, an air pump 2, and an air introduction pipe 3. The air introduction pipe 3 is arranged near the floor surface in the container 1,
An air discharge port 4 is provided on the upper surface thereof. The positions of the air introduction pipe 3 and the air discharge port 4 are appropriately determined so that the air can be easily spread evenly inside the composition when the composition is sealed in the container 1. One end of the air introduction pipe 3 projects outside the container 1 and is connected to the air pump 2. The air pump 2 is not particularly limited, but, for example, a diaphragm blower MD-40 (trade name) manufactured by Seiko Sangyo Co., Ltd. can be used. Also,
The material of the container 1 is not particularly limited, but is, for example, wooden plywood. Next, FIG. 2 shows an outline of the use of this device.
It should be noted that this figure is a cross-sectional view taken along the same cross section as FIG. As shown, the canopy 5, the panel heater 6 and the thermostat 7 are installed when the device is used. The canopy 5 is installed so that the container 1 is in a substantially sealed state, but an escape path for air is created by providing a slight gap or the like. The panel heater 6 and the thermostat 7 are
They are installed on the floor surface and wall surface of the container 1, respectively, and these are connected to a power source (not shown), respectively.
Although these are installed to adjust the temperature inside the container 1, they may be omitted depending on the case. Although the size of the container 1 is not particularly limited, for example, the height is 700 to 800 mm.
(700 mm in the figure), 600-700 mm width (700 mm in the figure), 900-1000 mm length (90 in the figure)
0 mm). The cross-sectional area of the air discharge port 4 is not particularly limited, but is, for example, about 0.8 cm ² for smooth air discharge.

When the composition is sealed in the container 1, a space of about 100 mm is provided near the wall surface in order to secure an escape area for air from the composition and the inside of the container 1.

Next, the air pump 2 is started, and the fermentation is advanced while air is discharged into the container 1. The amount of air discharged at this time is not particularly limited, but is, for example, 40 liters / minute. If the air is constantly discharged, the composition may be dried and the fermentation may be difficult to proceed. Therefore, it is preferable to discharge the air intermittently. At this time, the air ejection time and the stop time are not particularly limited, but they are appropriately determined while observing the water content of the composition.
For example, air is discharged for 2 to 3 days, then stopped for 3 to 4 days, and further discharged for 1 to 2 days, and then stopped for 5 to 6 days. By doing so, if the water content of the composition is, for example, 65% at the start of fermentation, it is unlikely that it will be 60% or less at the end of fermentation.

When the fermentation proceeds, the temperature inside the container usually rises to about 60 to 70 ° C. in 1 to 2 days after the start of fermentation. There are cases where weed seeds and the like are mixed in the composition, but they die at 59 ° C. or higher. Further, if the offensive odor is strong, it is preferable to deodorize by means such as a deodorizing tank.

As the fermentation further progresses, the temperature inside the container gradually decreases. Then, the discharge of air is stopped when the temperature inside the container becomes 32 ° C. or lower. If air is continuously discharged until a too late stage, the water content of the composition will be too low, which is not preferable. Then, the composition is left to stand for an appropriate time, and the fermentation is further continued to prepare a bacterial bed. Although it changes depending on the conditions such as the outside temperature, normally, when the temperature inside the container is 30 ° C. or less for about one week, it is a standard at the end of fermentation.
Although the time from the start of fermentation to the end of fermentation also varies depending on the conditions, it is usually about 3 to 6 weeks. The difference in water content between the start of fermentation and the end of fermentation is not particularly limited, but is preferably 10% or less, more preferably 5% or less.

Next, the basidiomycete is proliferated in the fungus bed in the container 1 to produce the organochlorine compound decomposing material of the present invention. That is, first, the bacterial bed is once taken out of the container 1. Then, the cultivated basidiomycete is mixed with the culture medium into the fungal bed. At this time, in order to promote the growth of basidiomycetes, it is preferable to mix the stem tissues of the plants together. Particularly preferable plant stem tissue is as described above. If the water content of the bacterial bed is insufficient, the water content may be adjusted by adding a small amount of water. The mixing amount of the basidiomycete and the medium is not particularly limited, but is, for example, 10 to 20% by weight based on the bacterial bed.
Is. The mixing amount of the stem of the wild plant is not particularly limited, but is, for example, 5 to 7% by weight, preferably 5% by weight based on the fungal bed.

Then, the bacterial bed is returned to the container 1 to grow basidiomycetes. During the basidiomycete growth period, the water content of the fungus bed and the temperature inside the container are maintained at values suitable for basidiomycete growth.
The water content varies depending on the type of basidiomycete,
For example, it is about 70%. The temperature inside the container also varies depending on the type of basidiomycetes, but is, for example, 25 ° C. around 28 ° C.
Keep at ~ 30 ° C. A panel heater 6 and a thermostat 7 may be used to maintain the temperature inside the container. During the basidiomycete growth period, it is usually unnecessary to discharge air.

Although the state of basidiomycete growth depends on the conditions,
For example: That is, after mixing basidiomycetes, 3
From about the 4th day, the growth of hyphae can be visually confirmed. At the same time, the odor characteristic of basidiomycetes can be confirmed. Around 10 to 15 days, hyphae spread over almost the entire surface of the fungal bed, and the odor of basidiomycetes becomes large. After the 15th day,
Furthermore, the thickness of the hypha layer increases, and depending on the location, the hypha swells up like a cotton and almost completely covers the entire surface of the fungal bed. Around 20 to 25 days after that, the elongation of hyphae and the odor of basidiomycete become maximum, and it becomes an optimal decomposing material for use. Thirty
The hyphal growth almost stopped around the day, and after the 35th day, the hyphae contracted, and the odor of basidiomycetes was not felt.
The time required from the start of preparation of the bacterial bed to the completion of preparation of the decomposed material varies depending on the conditions, but is, for example, about 60 days.

Although the decomposing material of the present invention can be manufactured as described above, the present invention is not limited to this and may be manufactured by other methods. For example, when a larger amount of decomposed material is manufactured at one time, the height, width and length of the container 1 can be further increased. However, if the deposition height of the composition is too high, it becomes difficult for the air from the air pump 2 to reach the entire composition. The deposition height depends on the performance of the air pump 2, but when the diaphragm blower MD-40 is used, it is preferably 1.3 m or less, more preferably 1 m or less.

It should be noted that, once the above-mentioned decomposed material is produced, this can be used in place of the above-mentioned inoculum to produce a bacterial bed. That is, a decomposing material is added instead of the inoculum to the composition containing the animal feces and the like. At this time, the mixing ratio of the animal dung (eg, cow dung), the dead plant tissue, and the decomposed material is not particularly limited, but for example, the weight ratio is 80: 1.
It is 0:10. Although the water content is not particularly limited, it is adjusted to be, for example, 65%. The fermentation period is not particularly limited, but is, for example, 30 to 45 days. Otherwise, the bacterial bed can be prepared in the same manner as above. Further, the decomposed material used here can be sufficiently used even after about one year has passed after the production, but the decomposed material immediately after the production is particularly preferable because the fermentation progresses more smoothly.

Further, once the above-mentioned decomposed material is produced, the basidiomycete culture by the sawdust medium culture or the like can be omitted. That is, first, a bacterial bed is manufactured in the same manner as above. Then, the same decomposing material can be regenerated in the same manner as above except that the decomposing material is added instead of adding the basidiomycete culture medium to the fungal bed. The amount of the decomposing material added at this time is not particularly limited, for example,
It is 20 to 30% by weight of the bacterial bed.

Next, the method for decomposing dioxins in soil using the decomposing material of the present invention can be carried out as follows, for example.

That is, first, for example, about 100 liters of the decomposing material of the present invention is added to 1 m ^{3 of} dioxin-contaminated soil and mixed well. At this time, it is preferable to mix the plant tissues together in order to promote the growth of basidiomycetes in the soil. The particularly preferable plant tissue is as described above. The amount of the plant tissue added is not particularly limited, but is, for example, about 30 liters per 1 m ^{3 of} dioxin-contaminated soil.

Next, the contaminated soil is allowed to stand. The soil may be returned to the place where it was collected and allowed to stand still, for example, it may be placed in a tank having a depth of 15 to 20 cm and allowed to stand still. Although it depends on temperature, humidity, etc., usually, most dioxins are decomposed after 15 to 20 days or more. During this period, it is preferable to appropriately perform heating, humidification, pH adjustment, etc., and to maintain the conditions suitable for the growth of basidiomycetes, because the dioxin decomposition can be carried out more quickly. After that, if you want to further reduce the dioxin content,
The same operation may be repeated two to three times, and more times in some cases.

In order to confirm the secreted state of the lignin-degrading enzyme in the soil, it is preferable to perform the test, for example, by the brilliant blue enzyme activity measuring method. This measurement can be carried out by a method commonly used by those skilled in the art. It depends on the temperature and humidity of the soil, but usually 1 to 7
Around the day, there is almost no secretion of lignin-degrading enzyme, and only hyphae grow. Secretion of the lignin-degrading enzyme starts from about the 10th day, and hyphal elongation and secretion of the lignin-degrading enzyme reach a maximum around the 15th to 25th days. In particular,
About 10 days after the initial secretion of lignin-degrading enzyme, it is preferable to appropriately perform heating, humidification, pH adjustment and the like while measuring the enzyme activity, because more effective and stable decomposition of dioxins can be performed.

The mechanism of decomposition of dioxins in soil is not entirely clear, but can be generally considered as follows. That is, first, the basidiomycete grows using a carbohydrate that is relatively easily decomposed as a nutrient source.
It is considered that the stem tissue of the wild plant, the strips of hay and the like act as a source of supply of the carbohydrate to promote the growth of basidiomycetes. Further, it is considered that ammonia nitrogen, nitrate nitrogen, organic nitrogen, etc. in the decomposed material also act as a nutrient source for this initial growth. When the basidiomycete grows to a certain extent and the carbohydrate is consumed, the basidiomycete tries to utilize the cellulose and hemicellulose existing in the dead plant tissue in the decomposed material as a nutrient source. Basidiomycetes attempt to decompose cellulose, hemicellulose and the like with enzymes, but for this purpose, the hyphae of basidiomycetes must deeply penetrate into the plant tissue. There, ligninase, which is a lignin-degrading enzyme, is secreted from the hyphae of basidiomycetes, and the hyphae decompose lignin in the plant tissue and invade into the tissue. When ligninase or the like is thus secreted, it is considered that dioxins having a structure similar to lignin are also decomposed at the same time. There are several types of enzymes secreted by the hyphae, such as lignin peroxidase and manganese peroxidase. For example, manganese peroxidase is considered to have a function of decomposing lignin.

Incidentally, it is preferable to conduct a soil investigation prior to carrying out the method for decomposing dioxins in the soil. As a result of the investigation, if the soil quality is not suitable for the growth of basidiomycetes, pretreatment such as adjusting the temperature, water content and pH of the soil may be necessary. At the same time, it is more preferable to conduct a dioxin decomposition test at the laboratory level.
This test may be carried out by collecting a small amount of sample soil, mixing about 10 to 20% by volume of the decomposing material, and allowing it to stand while adjusting water content and temperature.

The decomposing material of the present invention uses a substance that can be naturally decomposed and has a low nitrogen content, so that it is harmless to the environment. It is known that lignin is a persistent substance, but it is a harmless substance, and is usually carbonized in soil after 10 years. In addition, if you use natural strains of basidiomycetes,
There is no concern about the environmental impact of genetic recombination. Further, the decomposing material of the present invention usually has almost no bad odor, and produces only an odor characteristic of basidiomycetes when basidiomycetes are active.

[0053]

EXAMPLES Next, examples of the present invention will be described.

(Preparation of Bacterial Bed) First, a basidiomycete growth bacterial bed was prepared. That is, first, an inoculum containing bacteria, filamentous fungi and actinomycetes as a soil microorganism group was prepared by the method described in the above embodiment.

Next, a composition containing cow dung and the like was prepared.
That is, first, 9 kg of cow dung was prepared. This cow dung
Sawdust of about 10% by weight was added in advance and left standing for 3 months. And 400 more on this cow dung
The above composition was prepared by mixing g of sawdust and 0.2 kg of food waste. The C / N ratio of this composition was measured and found to be 35. The water content is 70% by weight
Met.

Then, the composition is supplemented with 800 ml of the inoculum.
In addition to g, garbage processing machine (Hitachi BGD-10)
Was stirred at 6 rpm for 20 minutes.

Next, the composition was fermented according to the method described in the above embodiment. That is, first, the device shown in FIGS. 1 and 2 was manufactured. Wooden plywood was used for the container 1 and the canopy 5. As an air pump, the Seiko Sangyo diaphragm blower MD-40 (caliber VP-1
3) was used. The cross-sectional area of the air outlet 4 is 0.8c
It was set to m ² .

Then, the composition was placed in the container 1. At this time, the deposition height of the composition was 0.7 m. Then, fermentation was performed while intermittently discharging air as described above. The discharge air pressure is 0.2 kgf / cm ² ,
The amount of discharged air was 40 liters / minute. 20 after starting fermentation
After about 30 days, the discharge of air was stopped when the temperature inside the container reached 32 ° C or lower. Then, the mixture was left to stand for 10 to 14 days and slowly fermented. About 10 days later,
The fermentation was terminated when the reproduction of the actinomycetes group was visually confirmed, and a bacterial bed was prepared. The water content of this fungal bed is 65
The weight% and the pH were 7.8.

(Preparation of Organochlorine Compound Decomposing Material) Next, basidiomycetes were grown in the above-mentioned fungus bed to prepare an organochlorine compound decomposing material. That is, first, sterilized sawdust and rice bran were mixed at a volume ratio of 8: 2, and the water content was adjusted to 70% to obtain a medium. Next, by mixing agaricus collected in the field into the medium, the depth is about 15 cm, and the length and width are about 4 cm each.
The cells were allowed to stand and cultured in a 0 cm styrene foam container with a lid for about 1 month to sufficiently extend the hyphae. Then, the medium after hyphal elongation, the sawdust and the plant stem tissue are mixed at a volume ratio of 1: 4: 3, and the mixture and the fungal bed are mixed at a volume ratio of 1: 9, and the container 1 I put it in.

The water content of the bacterial bed is maintained at about 70% by adding water appropriately, and the temperature inside the container 1 is set to about 28 ° C. (25 to 30 ° C.) by the panel heater 6 and the thermostat 7. ), The hyphae were elongated to produce the target degrading material. 20 after initiation of hyphal elongation
By the 25th day, the hyphal elongation reached the maximum, and it became the optimum degradable material. 10 days after initiation of hyphal elongation and 2
On day 0, an appropriate amount of the bacterial bed was collected and used for the following dioxin decomposition test.

(Dioxin Decomposition Test in Soil) Next, a dioxin decomposition test in soil using the organic chlorine compound decomposing material of the present invention was conducted. First, the soil quality of the sample soil was analyzed. The results are shown in Table 1 below. In Table 1, the dioxin content was measured by a so-called official method. This method is a method stipulated in the Act on Special Measures Against Dioxins, which is a method in which dioxins are extracted from sample soil by the Soxhlet method, purified by column chromatography, and then analyzed by GC / MS.

[0062] (Table 1) states air dry weight (g) 100 particle size (mm) <2.0 water content (%) 2.0 PCDDs (pg / g) 1.6 × 10 5 PCDFs (pg / g) 5 1.9 × 10 ⁵ Co-PCBs (pg / g) 8.7 × 10 ³ DXNs (pg / g) 7.6 × 10 ⁵ PCDDs (pg-TEQ / g) 1.7 × 10 ³ PCDFs (pg-TEQ) / G) 8.7 × 10 ³ Co-PCBs (pg-TEQ / g) 9.4 × 10 DXNs (pg-TEQ / g) 1.0 × 10 ⁴ * PCDDs: Parachlorodibenzodioxin content rate PCDFs: Parachlorodibenzofuran content rate Co-PCBs: coplanar PCB content rate DXNs: (PCDDs) + (PCDFs) + (Co-PCBs)

Next, to 100 g of the sample soil in Table 1, 5 g of the bacterial bed (that is, the organic chlorine compound decomposing material of the present invention) collected on the 20th day (by volume, about 20% of the sample soil). Was added and mixed well. This mixture was placed in a glass container to make an open system, and the water content was about 70%.
The mixture was allowed to stand for 13 days while maintaining the weight% and the soil temperature at about 28 ° C. During this period, when the measurement was carried out by the brilliant blue method, the secretion of lignin-degrading enzyme was confirmed.

After that, soil analysis was conducted again by competitive immunoassay to determine DXNs. This measurement method uses a high-speed solvent extraction method (ASE) for dioxins from sample soil.
Method) and then purified by column chromatography, and then Hybrizyme's TCDD test kit (trade name)
Is measured. Since this method detects only molecules with a relatively low number of chlorine atoms among dioxins, the correlation between the measured value and DXNs is obtained by preliminary measurement, and the value is 10 times the measured value (pg / g). DXNs (pg
-TEQ / g).

As a result of the above measurement, the DXNs value is 1.0 × 1.
From 0 ⁴ pg-TEQ / g to 6.3 × 10 ² pg-TEQ /
was reduced to g. This means that the decomposing material of the present invention showed a remarkable dioxin decomposition rate of about 94% with respect to soil highly contaminated with dioxins.

As sample soil, DXNs were 1.
Using the low concentration contaminated soil of 3 × 10 ² pg-TEQ / g, the same dioxin decomposition test as described above was performed.
As the concentration measuring method, the competitive immunoassay method was used. After the test, DXNs decreased from 1.3 × 10 ² pg-TEQ / g to 3.7 × 10 pg-TEQ / g. That is, the decomposing material of the present invention showed a high dioxins decomposition rate of about 71% even for low-dioxin-contaminated soil.

The dioxin content ratio of 1.0 × 10 pg-TEQ / g was used using the bacterial bed collected on the 10th day.
Was tested in the same manner as described above except that the soil of No. 1 and the soil of 6.0 × 10 ² pg-TEQ / g were used, respectively, but no decomposition of dioxins was observed.
Further, according to the Brilliant Blue method, secretion of lignin-degrading enzyme was not confirmed. From this, it is considered that in the mycelial elongation process during the production of the degrading material, only mycelia that decompose cellulose or hemicellulose grows until about the 15th day, and lignin-degrading mycelia grow actively from about the 20th day. .

[0068]

As described above, according to the organic chlorine compound decomposing material of the present invention, the organic chlorine compound in the soil,
Particularly, dioxins can be effectively decomposed.
The decomposing material of the present invention exhibits a high dioxin decomposition rate both in soils highly contaminated with dioxins and in soils contaminated with low concentrations of dioxins. Further, the decomposed material of the present invention can be produced using only naturally-occurring raw materials and naturally-occurring microorganism groups. Therefore, the dioxin can be decomposed safely and at low cost without adversely affecting the environment during and after use.

[Brief description of drawings]

FIG. 1 is a view showing an example of an apparatus used for producing an organochlorine compound decomposing material of the present invention, (a) and (b) are cross-sectional views, and (c) is a top view.

FIG. 2 is a schematic view of the device of FIG. 1 in use.

[Explanation of symbols]

1 container 2 air pump 3 Air introduction pipe 4 Air outlet 5 canopy 6 panel heater 7 thermostat

Claims (15)

[Claims] 1. A method for producing an organochlorine compound decomposing material, which comprises the following steps. (1) A step of producing a fungus bed by fermenting a composition containing at least animal feces and dead plant tissue with a soil microorganism group and setting the C / N ratio to 30 to 35. (2) A step of growing basidiomycetes in the fungal bed. 2. The method according to claim 1, wherein the animal dung is at least one selected from the group consisting of cow dung, pig dung, and chicken dung. 3. The method according to claim 1, wherein the dead plant tissue is at least one selected from the group consisting of wood, straw and hay. 4. The method according to claim 1, wherein in the step (1), the content of animal feces in the composition is 80 to 90% by weight and the content of dead plant tissue is 10 to 20% by weight. The production method described in Crab. 5. The production method according to claim 1, wherein in the step (2), the basidiomycete is grown after mixing the stem tissue of the plant into the fungal bed. 6. The method according to claim 1, wherein the soil microorganism group contains bacteria, filamentous fungi (molds) and actinomycetes. 7. The basidiomycete is a white wood-destroying bacterium.
7. The manufacturing method according to any one of 1 to 6. 8. The white wood-destroying fungus is of the genus Coriol.
The manufacturing method according to claim 7, which is at least one selected from us ). 9. An organochlorine compound decomposing material manufactured by the manufacturing method according to claim 1. 10. The organochlorine compound decomposing material according to claim 9, which is used for decomposing dioxins. 11. A method for decomposing an organochlorine compound, which comprises contacting the organochlorine compound decomposing material according to claim 9 or 10 with soil contaminated with the organochlorine compound. 12. A method for decomposing an organochlorine compound, which comprises mixing the organochlorine compound decomposing material according to claim 9 or 10 with soil contaminated with the organochlorine compound. 13. The method according to claim 11, wherein the plant tissue is mixed with soil.
Or the method for decomposing an organochlorine compound according to item 12. 14. The method according to claim 11, wherein the organic chlorine compound is a dioxin. 15. A method for purifying contaminated soil, which comprises decomposing organic chlorine compounds in soil by the method according to any one of claims 11 to 14.