JP2006026553A - Decontaminating means deciding method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To judge whether or not an organic chlorine compound can be decomposed by anaerobic microorganisms and to decide a decontamination means to be applied according to the judgment in regard to the decontamination means for decontaminating soil and ground water or surface water contaminated with organic chlorine compounds that are decomposable by the anaerobic microorganisms. <P>SOLUTION: Testing soil is prepared by extracting a prescribed amount of soil from the soil to be treated and testing water is prepared by extracting a prescribed amount of water from ground water or surface water. Dichloroethylene is added to the testing soil and the testing water to respectively prepare dichloroethylene-spiked testing soil and dichloroethylene-spiked testing water. The dichloroethylene-spiked testing soil and the dichloroethylene-spiked testing water are blended with an anaerobic microorganism decomposition accelerator for promoting decomposition by the anaerobic microorganisms. Obtained mixture is kept at a predetermined temperature under anaerobic conditions. After the predetermined period, it is judged whether or not dichloroethylene contained in the mixture is decomposed. According to this judgement, decontamination means to be applied to the soil and the ground water or the surface water is decided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a purification means for purifying soil and groundwater or surface water contaminated with organochlorine compounds that can be decomposed by anaerobic microorganisms. Is it possible to decompose the organochlorine compounds by anaerobic microorganisms in the soil? The present invention relates to a purification means determination method for determining whether or not and determining the purification means based on the determination.

  Tetrachloroethylene and trichlorethylene, which are volatile organic chlorine compounds, are used for degreasing and washing of metals, washing for dry cleaning, refrigerants, etc., and they have high industrial utility value, but they cause liver damage and kidney damage for the human body. It becomes a harmful substance. Therefore, soil and groundwater contamination by these organochlorine compounds is a serious social problem.

Many techniques for decomposing these organic chlorine compounds and purifying contaminated soil and groundwater have been disclosed (see, for example, Patent Documents 1, 2, 3, 4, and 5). One of the techniques is a reductive dechlorination treatment method using anaerobic microorganisms. This is a method of decomposing organochlorine compounds using anaerobic microorganisms present in contaminated soil at the site. However, before this method is actually applied, an applicability evaluation test (treatability test) to confirm the presence of anaerobic microorganisms capable of decomposing organochlorine compounds in contaminated soil and groundwater may be conducted. is necessary.
JP-A-10-216694 JP 2000-263032 A JP 2003-53320 A JP 2004-9025 A JP 2004-130166 A

  Degradation of organic compounds by anaerobic microorganisms includes tetrachloroethylene (hereinafter referred to as “PCE”) to trichlorethylene (hereinafter referred to as “TCE”), dichloroethylene (hereinafter referred to as “DCE”), and vinyl chloride (hereinafter referred to as “VC”). The reaction proceeds in the order of ethylene (hereinafter referred to as “ETY”), ethane (hereinafter referred to as “ETA”) (see FIG. 1). Among these anaerobic microorganisms that decompose organic compounds, there are many anaerobic bacteria that decompose PCE and TCE, such as Desulfitobacterium sp. PCE1, Dehalospirillum multivorans, and Desulfitobacterium sp. Y51 strain. For example, Dehalococcoides ethenogenes 195 strain is very small. Therefore, the degradation of DCE by anaerobic microorganisms takes much longer than the degradation of PCE and TCE. Furthermore, since DCE temporarily increases with the decomposition of PCE or TCE, even if DCE is decomposed, its amount may not decrease. Therefore, it is difficult to determine whether there are anaerobic microorganisms that degrade DCE. Even if it can be determined, it may take several months. From this, it is difficult to determine whether or not the soil or groundwater to be inspected can be decomposed by anaerobic microorganisms by a known treatability test, and even if it can be determined, it took a considerable amount of time.

  However, when construction work is performed on contaminated soil or groundwater, it is necessary to quickly select a method for purifying the site.

  Accordingly, an object of the present invention is to provide a purification means determination method that determines whether or not a reductive dechlorination treatment method using anaerobic microorganisms can be applied to the site in a short period of time and determines the purification means based on the determination. And

  In order to solve the above problems, a purification means determination method according to the present invention provides a purification means for purifying soil contaminated with an organic chlorine compound that can be decomposed by anaerobic microorganisms. A purification means determination method for determining whether or not decomposition by anaerobic microorganisms is possible and determining the purification means based on the determination, wherein a predetermined amount of soil is collected from the soil, and organic chlorine such as dichloroethylene is collected from the soil A step of preparing a test soil by removing intermediate products in the compound formation / decomposition reaction pathway, a step of adding dichloroethylene to the test soil to prepare a dichloroethylene spike test soil, the dichloroethylene spike test soil, An anaerobic microbial degradation accelerator for promoting degradation by anaerobic microorganisms, and the mixture is placed under anaerobic conditions. A step of maintaining the temperature at a predetermined temperature, a step of determining whether or not the dichloroethylene contained in the mixture is decomposed after the predetermined period, and using the soil according to the determination Determining the purification means.

  Another aspect of the purification means determination method according to the present invention is a purification means for purifying ground water or surface water contaminated with an organic chlorine compound that can be decomposed by anaerobic microorganisms. It is a purification means determination method that determines whether or not decomposition by anaerobic microorganisms is possible, and determines the purification means based on the determination, wherein a predetermined amount of water is collected from the ground water or surface water, and dichloroethylene is collected from the water The step of preparing test water by removing intermediate products of the production / decomposition reaction pathway of organochlorine compounds, etc., the step of preparing dichloroethylene spike test water by adding dichloroethylene to the test water, and the dichloroethylene spike test Mixing water and an anaerobic microbial degradation promoter for promoting degradation by the anaerobic microorganisms, and mixing the mixture A step of maintaining the temperature at a predetermined temperature for a predetermined period under a gas state, a step of determining whether the dichloroethylene contained in the mixture is decomposed after the predetermined period, and the determination, Determining the purification means used for the ground water or surface water.

  Still another aspect of the purification means determination method according to the present invention relates to a purification means for purifying soil and groundwater or surface water contaminated with an organic chlorine compound that can be decomposed by anaerobic microorganisms. It is a purification means determination method for determining whether or not decomposition by anaerobic microorganisms is possible, and for determining the purification means based on the determination, collecting a predetermined amount of soil from the soil, such as dichloroethylene from the soil The step of preparing the test soil by removing intermediate products in the production / decomposition reaction path of the organic chlorine compound, collecting a predetermined amount of water from the ground water or surface water, and collecting an organic chlorine compound such as dichloroethylene from the water A step of preparing test water by removing intermediate products in the production / decomposition reaction path, and adding dichloroethylene to the test soil and test water to dichloroethylene Mixing the step of preparing spike test soil and test water, the dichloroethylene spike test soil and test water, and the anaerobic microbial degradation accelerator for promoting the degradation by the anaerobic microorganisms, and the mixture in an anaerobic state Holding at a predetermined temperature for a predetermined period below, determining whether or not the dichloroethylene contained in the mixture has decomposed after the predetermined period, and determining the soil by the determination And determining the purification means used for ground water or surface water.

  In any of the above purification means determination methods, the dichloroethylene is preferably cis-dichloroethylene, and the organic chlorine compound is selected from the group consisting of tetrachloroethylene, trichloroethylene, dichloroethylene, and vinyl chloride. Or two or more compounds may be sufficient. Furthermore, the anaerobic microbial degradation promoter is preferably a hydrogen donor that provides the hydrogen necessary to promote reductive dechlorination that replaces chlorine in the organochlorine compound with hydrogen.

  According to the present invention, there is provided a purification means determination method for determining whether a reductive dechlorination treatment method using anaerobic microorganisms in a short period of time can be applied to contaminated soil and groundwater or surface water, and for determining the purification means based on the determination. provide.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The objects, features, advantages, and ideas of the present invention will be apparent to those skilled in the art from the description of the present specification, and those skilled in the art can easily reproduce the present invention from the description of the present specification. it can. The embodiments and specific examples of the invention described below show preferred embodiments of the present invention and are shown for illustration or explanation, and the present invention is not limited to them. It is not limited. It will be apparent to those skilled in the art that various modifications and variations can be made based on the description of the present specification within the spirit and scope of the present invention disclosed herein.

=== Purification Procedure for Purifying Means ===
For soil and groundwater or surface water contaminated with organochlorine compounds degradable by anaerobic microorganisms of the present invention (for example, Dehalospirillum multivorans, Dehalococcoides ethenogenes 195 strain, etc.), the organochlorine compounds are decomposed by anaerobic microorganisms. A determination method for determining whether or not it is possible (hereinafter abbreviated as “determination method”) performs the following steps.

  First, a predetermined amount (for example, 5 to 50 g) of soil is sampled from the soil at the original position that is the target of the determination method. The present invention determines the presence of anaerobic microorganisms capable of decomposing DCE added to the soil, thereby determining whether the soil is suitable for purification of anaerobic microorganisms. Organochlorine compounds such as PCE, TCE, DCE, and VC, which are intermediate products in the reaction path, are previously removed to prepare a test soil free from organochlorine compounds. The purpose of the removal work is to remove all the organic chlorine compounds contained in the collected soil, so any known technique for removing the organic chlorine compounds may be used. Means for killing the contained microorganisms, for example, treatment for removing organochlorine compounds by heat treatment at 800 ° C. or higher should not be used.

  On the other hand, a predetermined amount of water is collected from in-situ ground water or surface water that is the object of the judgment method, and PCE, TCE, which are intermediate products of the production / decomposition reaction path of DCE contained in the water, Organochlorine compounds such as DCE and VC are previously removed to prepare test water. For example, an organic chlorine compound may be vaporized from water by aeration treatment. The vaporized organochlorine compound can be purified using activated carbon or the like. The gas used for the aeration treatment is preferably nitrogen because microbial decomposition is performed in an anaerobic state. Further, the organic chlorine compound may be removed by means other than aeration treatment, for example, chemical decomposition using iron powder, or a combination of these means and aeration treatment. This organic chlorine compound removal treatment is intended to quickly determine the presence of anaerobic microorganisms capable of decomposing DCE, similar to the preparation of the test soil, so that the microorganisms in the groundwater or surface water are killed. A removal process, for example, a method of removing an organic chlorine compound with an oxidizing compound such as aqueous hydrogen peroxide should not be used.

  DCE is added to the test soil or test water thus prepared to prepare a DCE spike test soil or test water. Only one of the test soil and the test water may be prepared, but it is preferable to prepare both.

  Since these test soils or test waters do not contain PCE and TCE, which are precursors of DCE, due to the removal treatment of organochlorine compounds, these test soils and test waters contain only DCE. Accordingly, DCE does not increase from the initial amount even during the decomposition of organochlorine compounds by microorganisms. Therefore, when there are microorganisms that decompose DCE in the DCE spike test soil or test water, the added DCE decreases or the VC increases. Can be detected quickly. DCE may be added by a mixing process described later, or may be added only to either the test soil or the test water.

  The DCE spike test soil or test water thus prepared is mixed with an anaerobic microbial degradation accelerator for promoting degradation by anaerobic microorganisms, and the mixture is maintained at a predetermined temperature under anaerobic conditions. The predetermined temperature may be the temperature of contaminated soil, groundwater or surface water in situ, but is preferably 25 to 30 ° C. When the mixture is supplemented with water for the purpose of promoting improvement of the mixed state, water containing no organic chlorine compound is used, or distilled water is preferably used. Examples of the anaerobic microbial degradation promoter include chemical reaction with a hydrogen donor or water that provides hydrogen necessary to promote reductive dechlorination to replace chlorine and hydrogen of an organic chlorine compound. There are iron powders that provide hydrogen. Examples of the hydrogen donor include alcohols such as methanol or ethanol, low-molecular organic substances such as glucose or sucrose, lower fatty acids such as acetic acid, propionic acid, lactic acid, or butyric acid, or hydrogen donor compounds such as polylactic acid esters (HRC). ; Hydrogen Release Compound).

  Furthermore, after a predetermined period (2 weeks to 1 month) (approximately 2 weeks or more, but can be changed as appropriate according to various conditions such as the amount or activity of microorganisms in the mixture, the total amount of the mixture), and maintained at a predetermined temperature It is determined whether DCE contained in the prepared mixture has decomposed.

  As one of the means, it is determined whether or not a DCE decomposition product is generated in the mixture. When the decomposition product is produced | generated, it shows that the anaerobic microbe required in order to perform anaerobic microbe decomposition | disassembly with respect to the soil and groundwater or surface water contaminated with the organochlorine compound exists. Examples of the decomposition product include VC, ETY (or ethene), and ETA produced by reductive dechlorination of DCE by anaerobic microorganisms. This reductive dechlorination is a reaction in which chlorine bonded to carbon is replaced with hydrogen by the action of an anaerobic microorganism, and the process is illustrated in FIG. As a method for measuring these decomposed products, there are gas chromatography or liquid chromatography, and it is only necessary to confirm the generation of any of the decomposed products or a combination thereof.

  As another means, it is possible to determine whether or not the DCE is decomposed by directly examining whether or not the DCE is decreasing. However, since DCE is volatile, it can be reduced by evaporation in addition to being decomposed by anaerobic microorganisms. Usually, the decrease due to evaporation is small compared to the decrease due to the decomposition of DCE, and it is unlikely to give a large decrease in the total amount of DCE. In order to investigate in detail whether it has decreased, the evaporated DCE is measured using gas chromatography or the like, and the amount of DCE added to the mixture may be compared. From this, when DCE is reduced by decomposition, it indicates that there are anaerobic microorganisms necessary for anaerobic microbial decomposition of soil and groundwater or surface water contaminated with organochlorine compounds. .

  Preferably, it is possible to more clearly determine whether or not the DCE added to the mixture has decomposed by examining the amount of decrease in DCE itself as well as the amount of DCE decomposition produced in the mixture maintained at a predetermined temperature.

=== Purification Means ===
It is determined whether or not anaerobic microorganisms necessary for anaerobic microbial degradation are present by the processing procedure of the purification means described above. If the required anaerobic microorganisms are present, reductive dechlorination treatment through the microorganisms is applied to the contaminated soil or groundwater or surface water. This treatment method involves excavating the contaminated soil to remove organochlorine compounds by performing wind drying, heat treatment, etc., or pumping up the contaminated groundwater to aeration and adsorbing activated carbon to the organic chlorine. Compared to pumping treatment that removes compounds, no equipment or energy is required, so there is no cost. Furthermore, since anaerobic microorganisms that are present in situ are used, administrative procedures such as procedures and applications required when using microorganisms that are not in situ are not generated, and can be easily performed.

  Moreover, even when the required anaerobic microorganism does not exist, the present invention is useful because a method for purification without using an anaerobic microorganism can be selected quickly.

  Furthermore, the present invention may be carried out in situ (referred to herein as “contaminated soil location”).

  To determine how many days the judgment method of the present invention can improve the efficiency of soil and groundwater contaminated with organochlorine compounds by measuring the number of days related to the test using a conventional applicability evaluation test. The following experiment was conducted.

  After adding 50 g of soil containing an organic chlorine compound and 100 ml of groundwater containing an organic chlorine compound to a 100 ml brown screw mouth bottle and adding 0.1 to 0.2% of a hydrogen donor (EDC, Ecocycle Co.), the screw mouth bottle An anaerobic state was created by injecting nitrogen gas into the gap in the upper part of the gas and replacing it with oxygen. Then, the screw mouth bottle was sealed with a Teflon-coated cap with a silicon septum, and the substances contained therein were mixed, followed by stationary culture at 25 ° C. After that, the gas in the gas phase portion in the screw bottle was sampled every few days, using a gas chromatograph (GC-8610, JEOL Datum) (detector: DELCD, separation column: stainless capillary column NBW-310SS30), Analysis of organochlorine compounds (PCE, TEC, cis-dichloroethylene (hereinafter referred to as “cis-DCE”)) was performed. The result is shown in FIG.

  The PCE decreased immediately after the start of the experiment, and became 10 μm or less after the start of the experiment. The TCE produced by the decomposition of PCE also decreased after 10 days and became less than the environmental standard value (0.03 mg / l) after 20 days. However, cis-DCE produced by decomposition of TCE gradually increased until the 35th day and finally began to decrease from the 35th day. Since it takes time to decompose all the PCE and TCE (including those attached to soil organic matter and not dissolved in water) used in the experiment into cis-DCE, It is thought that cis-DCE gradually increased. As can be inferred from this figure, it became clear that the number of days of 35 days can be improved by using the present invention. That is, it has been clarified that an operation that takes two months or more in the conventional method can be completed in about three weeks by using the present invention.

It is the figure which showed the reductive dechlorination reaction of an organic chlorine compound, and its product with the reaction process. In one Example of this invention, it is the graph which showed the process in which the organochlorine compound contained in soil and groundwater was decomposed | disassembled with time by the conventional applicability evaluation test.

Claims (6)

With regard to the purification means for purifying soil contaminated with organochlorine compounds that can be decomposed by anaerobic microorganisms, it is determined whether or not the organochlorine compounds can be decomposed by anaerobic microorganisms in the soil, A purification means determination method for determining a purification means,
Collecting a predetermined amount of soil from the soil, removing intermediate products of the production / decomposition reaction pathway of organochlorine compounds such as dichloroethylene from the soil, and preparing test soil;
Adding dichloroethylene to the test soil to prepare a dichloroethylene spike test soil;
Mixing the dichloroethylene spike test soil and an anaerobic microbial degradation promoter for promoting degradation by the anaerobic microorganisms, and maintaining the mixture at a predetermined temperature for a predetermined period under anaerobic conditions;
Determining whether the dichloroethylene contained in the mixture has decomposed after the predetermined period; and
A step of determining the purification means used for the soil by the determination;
The purifying means determination method characterized by including. Regarding purification means for purifying groundwater or surface water contaminated with organochlorine compounds that can be decomposed by anaerobic microorganisms, determine whether the organochlorine compounds can be decomposed by anaerobic microorganisms in the soil, and A purification means determination method for determining the purification means by determination,
Collecting a predetermined amount of water from the ground water or surface water, and preparing test water by removing intermediate products from the production / decomposition reaction path of organochlorine compounds such as dichloroethylene from the water;
Adding dichloroethylene to the test water to prepare dichloroethylene spike test water;
Mixing the dichloroethylene spike test water and an anaerobic microbial degradation promoter for promoting degradation by the anaerobic microorganisms, and maintaining the mixture at a predetermined temperature for a predetermined period under anaerobic conditions;
Determining whether the dichloroethylene contained in the mixture has decomposed after the predetermined period;
Determining the purification means to be used for the groundwater or surface water according to the determination;
The purifying means determination method characterized by including. Regarding purification means for purifying soil and groundwater or surface water contaminated with organochlorine compounds that can be decomposed by anaerobic microorganisms, it is determined whether the organochlorine compounds can be decomposed by anaerobic microorganisms in the soil. A purification means determination method for determining the purification means based on the determination,
Collecting a predetermined amount of soil from the soil, removing intermediate products of the production / decomposition reaction pathway of organochlorine compounds such as dichloroethylene from the soil, and preparing test soil;
Collecting a predetermined amount of water from the ground water or surface water, and preparing test water by removing intermediate products from the production / decomposition reaction path of organochlorine compounds such as dichloroethylene from the water;
Adding dichloroethylene to the test soil and test water to prepare dichloroethylene spike test soil and test water;
The dichloroethylene spike test soil and test water are mixed with an anaerobic microbial degradation accelerator for promoting degradation by the anaerobic microorganisms, and the mixture is maintained at a predetermined temperature for a predetermined period under anaerobic conditions. Process,
Determining whether the dichloroethylene contained in the mixture has decomposed after the predetermined period;
The step of determining the purification means used for the soil and groundwater or surface water by the determination;
The purifying means determination method characterized by including.   The said dichloroethylene is cis-dichloroethylene, The purification | cleaning means determination method in any one of Claims 1-3 characterized by the above-mentioned.   The said organic chlorine compound is 1 or 2 or more compounds chosen from the group which consists of tetrachloroethylene, trichloroethylene, dichloroethylene, and vinyl chloride, The purification | cleaning means determination method in any one of Claims 1-4 characterized by the above-mentioned.   2. The anaerobic microbial degradation promoter is a hydrogen donor that provides the hydrogen necessary to promote reductive dechlorination for replacing chlorine in the organochlorine compound with hydrogen. The purification | cleaning means determination method in any one of -5.

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