JP4001020B2 - Contamination treatment method and contamination treatment agent - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a pollution treatment method and a pollution treatment agent applied to contaminated soil containing a halogenated organic compound such as tetrachloroethylene.
[0002]
[Prior art]
As one of the causes of soil contamination and water pollution, halogenated organic compounds such as tetrachloroethylene and trichlorethylene discharged from various factory facilities can be mentioned. Water quality once contaminated with a halogenated organic compound is generally treated by an aeration method using a packed tower, an adsorption method using activated carbon, or the like. In addition, soil contaminated with a halogenated organic compound is treated by removing moats, incineration, pumping water, and the like. In recent years, a method (bioremediation) has also been proposed in which microorganisms having a degradability of pollutants act on contaminated soil and contaminated water and the contaminated soil and contaminated water are purified by the microorganisms.
[0003]
Among bioremediation techniques, biostimulation is a technique that promotes decomposition and removal of pollution by growing and activating specific microorganisms that live in the field of pollution. In biostimulation, since foreign microorganisms are not supplied to the contaminated environment, it is attracting attention as an easy-to-accept environmental purification method. For example, by promoting the growth and activation of anaerobic microorganisms, the dechlorination reaction of tetrachloroethylene and trichlorethylene contained in the contaminated soil can be advanced.
[0004]
In general, when purifying contaminated environments by biostimulation, materials necessary to promote the growth and activation of specific microorganisms are supplied to the contaminated site, or suitable for the growth and activation of specific microorganisms. Therefore, it is necessary to supply a substance necessary for adjusting the environment (for example, see Patent Document 1). However, in order to promote the growth and activation of anaerobic microorganisms and advance the dechlorination reaction of tetrachlorethylene and trichlorethylene, substances that should be supplied to the contaminated environment have not been sufficiently studied.
[0005]
[Patent Document 1]
JP 2000-42525 A [Non-Patent Document 1]
7th Lecture Meeting on Groundwater / Soil Contamination and Prevention Measures, 275-278, December 2000 【0006】
[Problems to be solved by the invention]
For example, it has been reported that electrons necessary for dechlorination of tetrachlorethylene and trichlorethylene can be supplied by adding an electron donor such as ethanol and a nutrient salt to a contaminated site (non-patented). Reference 1). However, the method of adding a flammable substance such as ethanol to the contaminated site has a problem in terms of work safety, and it cannot be considered that it can be carried out for actual decontamination.
Therefore, in view of the above-described problems, an object of the present invention is to provide a contamination treatment method and a contamination treatment agent that can be safely carried out in work.
[0007]
[Means for Solving the Problems]
As a result of intensive studies by the present inventors to achieve the above-described object, anaerobic microorganisms contained in the contamination treatment target are converted into halogenated organic compounds by supplying yeast and a yeast growth substrate to the contamination treatment target. The present inventors have found that the dehalogenation reaction of can proceed efficiently, and have completed the present invention.
That is, the present invention includes the following.
[0008]
(1) A contamination treatment method in which yeast and a yeast growth substrate are supplied to a treatment target containing a halogenated organic compound to dehalogenate the halogenated organic compound.
(2) The contamination treatment method according to (1), wherein the treatment target is subjected to conditions under which anaerobic microorganisms can act.
(3) The contamination treatment method according to (1), wherein the growth substrate is a carbon source.
(4) The contamination treatment method according to (2), wherein the anaerobic microorganism is included in the treatment target.
(5) The contamination treatment method according to (1), wherein the halogenated organic compound is tetrachloroethylene and trichloroethylene.
(6) A contamination treating agent mainly comprising yeast and a yeast growth substrate and dehalogenating a halogenated organic compound contained in the treatment target.
(7) The contamination treatment agent according to (6), wherein the treatment target is in a condition where anaerobic microorganisms can act.
(8) The contamination treating agent according to (6), wherein the growth substrate is a carbon source.
(9) The contamination treatment agent according to (6), wherein the anaerobic microorganism is contained in the treatment target.
(10) The contamination treatment method according to (6), wherein the halogenated organic compound is tetrachloroethylene and trichloroethylene.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail.
The contamination treatment method to which the present invention is applied can dehalogenate a halogenated organic compound contained in a treatment target. Here, the treatment target means the soil and water quality collected from the contaminated environment, or the contaminated environment itself. The contaminated environment is not particularly limited as long as it may contain a halogenated organic compound, and examples thereof include soil and water environments. Examples of the soil include sludge, cutting soil, bottom sediment, dry soil, wet soil, sand and humus. Examples of the water environment include groundwater, industrial wastewater, domestic wastewater, rivers, ponds and lakes.
[0010]
The halogenated organic compound is meant to include volatile polyhalogenated organic compounds (VOCs) such as tetrachloroethylene and trichlorethylene. In addition to VOCs, examples of the halogenated organic compound include substances such as chlorofluorocarbon, polychlorinated biphenyls (PCBs), DDT, aldrin, endrin, and dieldrin.
[0011]
In the contamination treatment method, first, yeast and a yeast growth substrate are supplied to the treatment target. Here, the yeast is not particularly limited as long as it produces alcohol such as ethanol and carbon dioxide by alcohol fermentation reaction. For example, yeasts include Saccharomyces cerevisiae, Saccharomyces bayanus, Debaryomyces polymorphus, Pichia anomala, Zichiaccharomyces sci. Candida salmanticesis and the like can be used.
[0012]
In order to supply the yeast to the treatment target, either a method of directly feeding the yeast into the contaminated environment or a method of separating a part or all of the contaminated environment and throwing the yeast into the separated contaminated environment may be used. . Whichever method is used, the yeast may be added to the medium with yeast that has been cultured in advance to the logarithmic growth phase, or the yeast suspension in which the yeast in the logarithmic growth phase is collected and suspended in a predetermined solution. A liquid may be added.
[0013]
The amount of yeast is preferably added in the range of 1.0 to 10 mg-wet per 10 g of soil, and more preferably in the range of 2.5 to 5 mg-wet per 10 g of soil. Yeast may be added simultaneously with the growth substrate, but may be added at any timing before or after the growth substrate is added.
[0014]
The growth substrate means a nutrient that contributes to the growth of yeast accompanied by alcohol fermentation. Specifically, the growth substrate is meant to include carbon sources such as glucose, sucrose, fructose, galactose and maltose.
[0015]
The growth substrate may be supplied to the processing target at the same time as the yeast is supplied to the processing target, or may be supplied to the processing target regardless of before and after supplying the yeast. When supplying the growth substrate together with the yeast, for example, an appropriate amount of the growth substrate may be added to the yeast culture solution to prepare a contamination treatment agent, and the contamination treatment agent may be added to the treatment target.
[0016]
Moreover, when using glucose as a growth substrate, it is preferable to input in the range of 1-20 mg per 10 g of soil, and it is more preferable to input in the range of 5-10 mg per 10 g of soil.
[0017]
In this contamination treatment method, ethanol and carbon dioxide are produced in the treatment target by alcohol fermentation by yeast using a growth substrate. Alcohol fermentation by yeast using a growth substrate starts after supplying yeast and yeast growth substrate and continues until the growth substrate is depleted or the yeast dies. Here, examples of the anaerobic microorganisms include conventionally known microorganisms.
[0018]
For example, as anaerobic microorganisms, heterotrophic anaerobic microorganisms are preferable, and as main heterotrophic anaerobic microorganisms present in soil, methanogenic bacteria (for example, Methanosarcina genus, Methanothrix genus, Methanobacterium genus, Methanobrevibacter genus) ), Sulfate-reducing bacteria (eg, Desulfovibrio, Desulfotomaculum, Desulfobacterium, Desulfobacter, Desulfococcus), acid-producing bacteria (eg, Clostridium, Acetivibrio, Bacteroides, Ruminococcus), facultative anaerobes ( For example, Bacillus genus, Lactobacillus genus, Aeromonas genus, Streptococcus genus, Micrococcus genus) and the like can be mentioned.
These anaerobic microorganisms may be included in advance in the processing target, or may be added separately to the processing target.
[0019]
These anaerobic microorganisms can dehalogenate a halogenated organic compound under anaerobic conditions using an alcohol such as ethanol as an electron donor. In this method, by supplying yeast and a yeast growth substrate to the treatment target, alcohols that serve as electron donors in the treatment target can be produced by the yeast. Therefore, according to this method, tetrachlorethylene can be dechlorinated using an electron donor produced by an anaerobic microorganism that is preliminarily present in the contaminated environment to be treated or an anaerobic microorganism that has been introduced into the contaminated environment. .
[0020]
When tetrachlorethylene in the treatment target is dechlorinated, it may stop with trichlorethylene, but mainly becomes dichloroethylene, which triggers dechlorination to detoxifying ethylene. As a result, the processing target is purified. In other words, when the soil and water quality collected from the contaminated environment are treated, tetrachloroethylene, etc. can be removed from the collected soil and water quality, and there is no problem even if the treated soil or water quality is reduced to any environment. It becomes the original. On the other hand, when the contaminated environment itself is a processing target, the contaminated environment itself can be purified.
[0021]
The halogenated organic compound that has been dehalogenated is then further decomposed by other microorganisms or the like included in the object to be treated, or by being subjected to a decomposition treatment by a known method, to water and carbon dioxide. Sometimes it is broken down.
[0022]
As described above, in this contamination treatment method, it is not necessary to supply ethanol or the like as an electron donor to the treatment object, and the halogenated organic compound contained in the treatment object can be dehalogenated. According to this pollution treatment method, since flammable substances such as ethanol are not used, safety to the operator and the surrounding environment can be ensured.
[0023]
【Example】
Hereinafter, the present invention will be described in more detail with reference to examples. However, the technical scope of the present invention is not limited to these examples.
[0024]
[Example 1]
In this example, the dechlorination of tetrachloroethylene was examined when a soil treatment containing tetrachloroethylene was allowed to act on a soil treatment agent composed of commercially available dry baker's yeast and glucose. In addition, the used baker's yeast is marketed and the safety | security has been confirmed.
[0025]
First, the obtained baker's yeast was cultured with shaking in a DIFCO “YM BROTH” medium at 30 ° C. overnight. Next, the cultured baker's yeast, 100 mM glucose solution, tetrachloroethylene saturated water and soil were put into a vial, and then the vial was sealed. In this example, 100 μl of tetrachloroethylene saturated water, 100 μl of 100 mM glucose solution, and 2 g of soil were used. In addition, baker's yeast was collected after culturing as described above, washed with sterilized water, and then suspended in sterile water.
[0026]
The vial was allowed to stand for 79 days in a chamber maintained at 30 ° C. Thereafter, the gas components in the headspace were analyzed by gas chromatography mass spectrometry. G1800A GCD SYSTEM manufactured by HEWLETT PACKARD was used for gas chromatography mass spectrometry analysis. The result of measuring the GC peak area for each gas component contained in the head space is shown in FIG. In FIG. 1, PCE represents tetrachloroethylene, TCE represents tetrachloroethylene, DCE represents dichloroethylene, and VC represents vinyl chloride.
[0027]
From the results of FIG. 1, it was revealed that by supplying baker's yeast and glucose to the soil, tetrachlorethylene contained in the soil decreased and dichloroethylene increased. From this, it was found that by supplying baker's yeast and glucose to the soil, the dechlorination of tetrachlorethylene contained in the soil can be promoted and the soil contamination can be purified.
[0028]
[Example 2]
In this example, dechlorination of tetrachlorethylene was examined when edible bacteria other than baker's yeast and sterilized yeast were used.
[0029]
In this example, dechlorination of tetrachloroethylene contained in soil was performed in the same manner as in Example 1 except that natto (Bacillus natto IFO 3009), yogurt (Lactobacillus bulgaricus IFO 13953) and sterilized yeast were used instead of baker's yeast. Was evaluated.
[0030]
The sterilized yeast used in this example was prepared by autoclaving at 120 ° C. for 20 minutes. Further, as a medium for Bacillus natto, IFO medium 203 (see LIST OF CULTURES 10 ^th edition (Luminescence Research Foundation)) was used. The medium yoghurt bacteria was used medium IFO 205 (see LIST OF CULTURES 10 ^th edition (Foundation emitting Research)).
[0031]
FIG. 2 shows the results of evaluating the dechlorination of tetrachlorethylene contained in the soil when using live baker's yeast and when using sterile yeast. In FIG. 2, G indicates the case where only glucose is added, Y indicates the case where only live baker's yeast is input, YG indicates the case where live baker's yeast and glucose are input, and D indicates sterile yeast. DG shows the case where sterilized yeast and glucose are added.
[0032]
From the results of FIG. 2, it was revealed that dechlorination of tetrachlorethylene contained in soil can be promoted even when sterilized yeast and glucose are added. Moreover, from the result of FIG. 2, it was revealed that the use of live baker's yeast efficiently promotes the dechlorination of tetrachlorethylene contained in the soil as compared with the case of using sterilized yeast.
[0033]
FIG. 3 shows the results of evaluating the dechlorination of tetrachlorethylene contained in the soil when baker's yeast, yogurt bacteria, and natto bacteria are used. In FIG. 3, Y indicates the case where only baker's yeast is added, YG indicates the case where baker's yeast and glucose are input, N indicates the case where only natto bacillus is input, and NG indicates natto bacteria and glucose. In this case, L indicates a case where only yogurt bacteria are input, and LG indicates a case where yogurt bacteria and glucose are input.
[0034]
From the results of FIG. 3, it was revealed that natto and yogurt bacteria cannot promote the dechlorination of tetrachlorethylene contained in soil even when they are added together with glucose. On the other hand, when baker's yeast and glucose were added, it became clear that the dechlorination of tetrachlorethylene contained in the soil can be promoted.
[0035]
Example 3
In this example, the dechlorination of tetrachlorethylene when a soil treatment agent composed of baker's yeast and glucose was applied to soil mined from different places (referred to as KGHO soil) was examined.
[0036]
In this example, the gas components in the headspace were analyzed by gas chromatography in the same manner as in Example 1 except that 4 g of soil was used. In this example, in order to easily weigh HO soil, it was air-dried and weighed in a vial, and then an appropriate amount of water was added to restore the original state. The results of evaluating the dechlorination of tetrachlorethylene contained in KGHO soil are shown in FIG. In FIG. 4, G shows the case where only glucose is added, Y shows the case where only baker's yeast is added, and YG shows the case where baker's yeast and glucose are added.
[0037]
From the results of FIG. 4, it was revealed that dechlorination of tetrachlorethylene contained in soil can be promoted when baker's yeast and glucose are added regardless of the type of soil.
[0038]
【The invention's effect】
As described above in detail, according to the present invention, a halogenated organic compound contained in a treatment target can be dehalogenated, and a simple contamination treatment method and a contamination treatment agent can be provided. In addition, according to the present invention, since it is not necessary to introduce a flammable substance to the object to be treated, it is possible to provide a contamination treatment method and a contamination treatment agent that are excellent in safety.
[Brief description of the drawings]
FIG. 1 is a characteristic diagram showing a result of measuring a GC peak area for each gas component contained in a head space as a result of Example 1;
FIG. 2 is a characteristic diagram showing the results of evaluating the dechlorination of tetrachlorethylene contained in soil when live baker's yeast is used and when sterile yeast is used.
FIG. 3 is a characteristic diagram showing the results of evaluating the dechlorination of tetrachlorethylene contained in soil when baker's yeast, yogurt bacteria, and natto bacteria are used.
FIG. 4 is a characteristic diagram showing the results of evaluating the dechlorination of tetrachlorethylene contained in KGHO soil.

Claims (8)

Supplying yeast and yeast growth substrate to an anaerobic microorganism that dehalogenates a halogenated organic compound under anaerobic conditions and a treatment target containing the halogenated organic compound, or a treatment target containing a halogenated organic compound On the other hand , a contamination treatment method in which yeast, a yeast growth substrate and the anaerobic microorganism are supplied, and the halogenated organic compound is dehalogenated by the anaerobic microorganism . The contamination treatment method according to claim 1, wherein the treatment target is subjected to anaerobic conditions .   The contamination treatment method according to claim 1, wherein the growth substrate is a carbon source.   2. The contamination treatment method according to claim 1, wherein the halogenated organic compound is tetrachloroethylene and trichloroethylene. Mainly the growth substrate of yeast and yeast, are applied to the processing target containing anaerobic microorganisms dehalogenating halogenated organic compounds in anaerobic conditions, dehalogenation of halogenated organic compounds contained in the processing target pollution processing accelerators to promote. 6. The contamination processing accelerator according to claim 5 , wherein the growth substrate is a carbon source. The said anaerobic microorganism is previously contained in the said process target, The pollution process promoter of Claim 5 characterized by the above-mentioned. 6. The pollution processing accelerator according to claim 5, wherein the halogenated organic compound is tetrachloroethylene and trichloroethylene.

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