JP2009279498A - Method and system of rendering polluted soil harmless - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of easily making harmless organic pollutants such as POPs or dioxines contained in soil at low cost without causing deleterious effects on the environment, and a system intended for this purpose. <P>SOLUTION: This method for making harmless polluted soil containing organic pollutants such as POPs or dioxines comprises: a cleaning process (S101) to add a mixed solvent composed of a hydrofluorocarbon and an organic solvent to polluted soil and clean the polluted soil at least once using the mixed solvent; a first separation process (S102) to separate the mixed solvent containing the organic pollutant from the soil; a second separation process (S103) to separate the organic pollutant from the mixed solvent containing the organic pollutant; and a process to make the polluted soil harmless (S105) by decomposing the separated organic pollutant. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for detoxifying contaminated soil and its system for eluting organic pollutants from soil contaminated with organic pollutants such as POPs or dioxins.

  In recent years, a problem has been pointed out that soils at sites of various manufacturing factories and adjacent sites thereof are contaminated with organic pollutants such as POPs or dioxins. Since there are concerns about adverse effects on human bodies due to pollutants such as organic pollutants such as POPs or dioxins, an effective treatment method for detoxifying the contaminated soil is desired.

  Conventionally, cement solidification treatment has been proposed as a detoxification treatment method for soil contaminated with organic pollutants such as POPs or dioxins. However, since organic contaminants such as POPs or dioxins are contained in the cement, there is a risk that the organic contaminants such as POPs or dioxins will elute from the cement after a long period of time. It is not a safe processing method.

  In view of such problems, as a detoxification treatment method, a treatment for incinerating soil contaminated with organic pollutants such as POPs or dioxins has been studied. Specifically, for example, in a method for purifying soils contaminated with organic halogen compounds such as dioxins containing large and small stone solids, the soils are introduced into a separator and large solids are removed from the soils. After the separation, the soil containing the organic halogen compound is transported with stirring in a low oxygen atmosphere, and the soil is heated by an external heat treatment means to decompose the existing organic halogen compound. A soil purification method has already been disclosed in which an organic halogen substance is removed from soils and exhaust gas by contact-reacting the components of the above and the added treatment agent to produce harmless compounds (see, for example, patents). Reference 1).

  There is also known a detoxification method for cleaning soil contaminated with organic pollutants such as POPs or dioxins using an organic chlorine-based solvent or an aromatic solvent such as toluene or benzene.

  Furthermore, the contaminated soil is harmless by adopting the melting and fixing detoxification method, filling contaminated soil contaminated with organic pollutants such as POPs or dioxins in the buried pit, inserting electrodes, and energizing. Techniques for the conversion process are also known.

JP 2002-205049 A (Claims)

  However, the conventional detoxification method for soil contaminated with organic pollutants such as POPs or dioxins has the following problems. In the case of incineration treatment, there is a problem that dioxins generated by organochlorine compounds in the treatment object are contained in the exhaust gas during the incineration treatment and diffused widely, contaminating the soil around the incineration plant. is there. Moreover, since organic pollutants are scattered and mixed in the soil, they must be treated together with a large amount of soil. For this reason, there is also a problem that enormous energy is required and the operating cost is increased.

  On the other hand, the method for cleaning contaminated soil with an organic chlorinated solvent or aromatic solvent is excellent in detergency, but because the organic chlorinated solvent or aromatic solvent is carcinogenic to the human body, There is a problem. In addition, since organic chlorinated solvents or aromatic solvents are likely to remain in the soil, there is a problem that new secondary contamination occurs.

  In addition, when adopting the melt-fixed detoxification method, the center temperature of the contaminated material in the buried pit becomes high, so a large amount of power is required, and both the equipment introduction cost and the processing cost are expensive. There is.

  The present invention has been made to solve the above-described problems, and the object of the present invention is to provide POPs or dioxins in soil easily and at low cost without adversely affecting the environment. It is an object of the present invention to provide a method and system for detoxifying organic pollutants such as the like.

  In order to achieve the above object, the present invention is a method for detoxifying contaminated soil containing organic pollutants such as POPs or dioxins, wherein a mixed solvent composed of a hydrofluorocarbon and an organic solvent is added to the contaminated soil. A washing step of washing the contaminated soil at least once with a mixed solvent, a first separation step of separating the mixed solvent containing organic pollutants and the soil, a mixed solvent containing organic pollutants and organic It is a detoxification treatment method for contaminated soil, which has a second separation step for separating the pollutant and a detoxification step for decomposing the separated organic pollutant.

  For this reason, organic pollutants such as POPs or dioxins in soil can be rendered harmless easily at low cost and without adversely affecting the environment. By adding a mixed solvent composed of a hydrofluorocarbon and an organic solvent to the contaminated soil and washing it once or a plurality of times, the organic pollutant can be efficiently eluted from the soil. Further, by separating the organic pollutant and the soil, the detoxification target can be significantly reduced in volume. For example, 1 ton of 1 ppb dioxin contaminated soil contains only 1 mg of dioxin. The energy for decomposing 1 mg of dioxin is little compared to the incineration method in which all 1 t of contaminated soil is incinerated. In addition, since hydrofluorocarbon is very volatile, it can be efficiently separated from organic pollutants in the second separation step, and since it does not contain chlorine, the ozone depletion coefficient is zero. For this reason, decontamination treatment of organic pollutants with low energy consumption, low environmental load, and economic efficiency can be expected.

  Another aspect of the present invention is a method for detoxifying contaminated soil, including performing a second separation step and further including a regeneration step of regenerating the mixed solvent so that the mixed solvent is circulated and used. By regenerating the mixed solvent, the solvent can be recycled. For this reason, waste of the solvent can be eliminated, and the operating cost of the detoxification process can be reduced.

  In another aspect of the present invention, the detoxification process for decomposing organic pollutants is a detoxification method for contaminated soil, which is performed by supercritical water oxidation. For this reason, organic pollutants can be efficiently and completely decomposed and rendered harmless.

  Another aspect of the present invention is a detoxification method for contaminated soil in which the mixed solvent contains 5 volumes of organic solvent with respect to 100 volumes of hydrofluorocarbon. For this reason, organic pollutants such as POPs or dioxins by the mixed solvent can be more efficiently eluted from the soil.

  Another aspect of the present invention is a detoxification method for contaminated soil in which the organic solvent is acetone, hexane, methanol, or ethanol. For this reason, organic pollutants such as POPs or dioxins by the mixed solvent can be more efficiently eluted from the soil.

  Another aspect of the present invention is a detoxification method for contaminated soil in which organic pollutants are polychlorinated biphenyls. For this reason, the organic pollutant which is polychlorinated biphenyls can be detoxified more effectively.

  Further, the present invention is a system for detoxifying contaminated soil containing organic pollutants such as POPs or dioxins, and mixing contaminated soil by adding a mixed solvent composed of hydrofluorocarbon and organic solvent to the contaminated soil A cleaning means for cleaning at least once with a solvent, a first separation means for separating the mixed solvent containing organic pollutants and the soil, and a mixed solvent containing organic pollutants and the organic pollutants are separated. The decontamination treatment system for contaminated soil is provided with second separation means for detoxification and detoxification means for decomposing the separated organic pollutants. For this reason, decontamination treatment of organic pollutants with low energy consumption, low environmental load, and economic efficiency can be expected.

  Another aspect of the present invention is a detoxification treatment system for contaminated soil, further comprising storage means for storing the mixed solvent regenerated so that the mixed solvent is circulated and used when performing the second separation means. By having means for regenerating and storing the mixed solvent, the solvent can be recycled. For this reason, waste of the solvent can be eliminated, and the operating cost of the detoxification process can be reduced.

  Another aspect of the present invention is a detoxification treatment system for contaminated soil, in which the elution means includes an oscillation means for generating ultrasonic waves. For this reason, when the ultrasonic wave is transmitted into the solution, the organic pollutant adhering to or mixing with the soil is peeled off and can be eluted more efficiently in the mixed solvent.

  In the method for detoxifying contaminated soil according to the present invention, the contaminated soil to be treated is soil containing organic pollutants such as POPs or dioxins. Specific examples of the organic pollutant include polychlorinated biphenyl (PCB), DDT, BHC, endrin, sportac, trifmine, dioxins, and the like. Suitable for treating soil. However, the organic pollutants to be decomposed are merely examples, and soil contaminated with other types of organic pollutants may be treated. In addition, the contaminated soil that can be detoxified by the present invention refers to the soil contaminated by the above-mentioned organic pollutants leaked or sprayed on factory grounds, general residential areas or public land for some reason. Agricultural land, earth and sand, bottom sediment and sludge.

  Examples of the organic solvent that is selectively used in the detoxification method for contaminated soil according to the present invention include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 1-pentanol, and 3-pentanol. Alcohols, acetone, hexane, methyl ethyl ketone and the like. Of these organic solvents, it is preferable to use a low molecular weight hydrophilic organic solvent having a low boiling point and easily recoverable. In particular, it is more preferable to use ethanol. However, the above organic solvents can be used alone or in combination of two or more. It is preferable to change the type and blending amount of the organic solvent according to the type of the organic contaminant.

  According to the present invention, organic pollutants such as POPs or dioxins in soil can be rendered harmless easily at low cost and without adversely affecting the environment.

  Hereinafter, preferred embodiments of a method for detoxifying contaminated soil and a system thereof according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described below.

  FIG. 1 is a schematic diagram of a treatment system that performs a detoxification process for contaminated soil according to an embodiment of the present invention.

  The processing system 1 includes a cleaning device means 10 as cleaning, a first separator 20 as first separation means, a second separator 30 as second separation means, and a reservoir 40 as storage means, A detoxifying device 50 as a detoxifying means is provided.

  The cleaning device 10 is a device that efficiently elutes organic pollutants from the soil. As shown in FIG. 1, a cleaning tank 5 for mainly introducing and cleaning contaminated soil is provided. The washing tank 5 is a strong iron or stainless steel container that varies depending on the amount of soil to be treated, and has a lid that can be sealed at an appropriate position. The reason for using the sealed cleaning tank 5 is that the mixed solvent can be prevented from being exerted. A stirring device 6 is provided at the bottom of the cleaning tank 5. This is because the dispersion of the contaminated soil in the cleaning solvent can be increased, and the elution efficiency of the organic pollutants contained in the contaminated soil can be increased.

  The first separator 20 separates the mixed solvent containing organic pollutants and the soil. As shown in FIG. 1, a filtration device 7 is provided below the cleaning tank 5. The mixed solvent containing organic pollutants by the elution means and the soil can be separated through the filtering device 7 using a method such as pressure filtration, suction filtration, or centrifugal separation. The first separation device may be performed after the mixed solvent phase and the solid phase of the soil are suspended or after being allowed to stand for a certain time.

  The second separator 30 separates the mixed solvent containing the organic pollutant and the organic pollutant. As shown in FIG. 1, a cleaning liquid trap 8 is disposed outside the cleaning tank 5. A heating device 9 is provided to evaporate the mixed solvent. Since the mixed solvent containing the organic pollutant obtained by the first separator 20 stored in the cleaning liquid trap 8 is evaporated by a process such as heat evaporation, the organic pollutant is separated. For this reason, the detoxification target can be significantly reduced in volume.

  The reservoir 40 stores the mixed solvent regenerated so that the mixed solvent evaporated in the second separator can be circulated and used. As shown in FIG. 1, it is preferable to arrange a cooling device 11 for cooling the evaporated mixed solvent. By providing the cooling device 11, the mixed solvent can be regenerated, and the solvent can be recycled. For this reason, waste of the solvent can be eliminated, and the operating cost of the detoxification process can be reduced.

  The detoxifying device 50 is a device that decomposes the separated organic pollutant. Organic pollutants are preferably detoxified by supercritical water oxidation. As a result, the organic pollutant can be efficiently and completely decomposed and rendered harmless. However, the supercritical water oxidation method described above is only an example, and the organic pollutant is decomposed by a detoxification treatment method of other organic pollutants such as a thermal decomposition method or a dechlorination method. Also good.

  FIG. 2 is a flowchart showing the procedure of the detoxification method for contaminated soil according to the embodiment of the present invention.

  Hereinafter, the process procedure for detoxifying contaminated soil will be described with reference to FIG.

(1) Organic pollutant cleaning process (step S101)
This step is a step of eluting organic pollutants into a mixed solvent composed of hydrofluorocarbon (hydrofluorocarbon, hereinafter referred to as HFC) and an organic solvent. First, soil contaminated with organic pollutants such as POPs or dioxins is put into a washing tank. Subsequently, a mixed solvent composed of HFC and an organic solvent is added and stirred. In the treatment of soil contaminated with organic pollutants, the mixed solvent contains 5 volumes of organic solvent for 100 volumes of HFC. By adjusting the mixed solvent in this way, it is possible to more efficiently elute organic pollutants from the soil. Here, as the organic solvent, acetone, hexane, or alcohols such as methanol or ethanol can be preferably used. In particular, it is more preferable to use ethanol. The mixing method of the contaminated soil and the mixed solvent may be other methods such as ultrasonic treatment in addition to the stirring using the stirring blade. In addition, depending on the nature of the contaminated soil to be treated and the type and content of organic pollutants contained in the soil, the amount of mixed solvent added and the type of organic solvent selected, the contaminated soil efficiently Is preferably processed. Further, for the purpose of further improving the elution efficiency of organic pollutants, mixing and stirring may be performed in a heated state in a washing tank as necessary.

  Moreover, the contaminated soil may be washed several times in the mixed solvent as necessary. As a result, the elution efficiency of organic pollutants can be improved. However, it is not always necessary to perform multiple cleanings.

(2) First separation step (step S102)
This step is a step of separating the mixed solvent containing organic pollutants obtained by the washing step and the soil. In this embodiment, the organic pollutant can be efficiently removed from the soil by separating the mixed solvent containing the organic pollutant and the soil. In addition, the separation method of soil and mixed solvent may be other separation methods such as centrifugal separation in addition to filtration methods such as pressure filtration and suction filtration. Further, the mixed solvent phase and the solid phase of the soil may remain suspended, or may be performed after standing for a certain time.

(3) Second separation step (step S103)
This step is a step of separating the mixed solvent containing the organic pollutant obtained in the first separation step and the organic pollutant. In this embodiment, only organic pollutants adhered to and mixed with contaminated soil were obtained by separating mixed solvents containing organic pollutants and organic pollutants. For this reason, the detoxification target can be greatly reduced in volume, and the energy for decomposing organic pollutants is very small compared to conventional incineration methods. The result is an economical and efficient detoxification process for organic pollutants. In the present embodiment, any known method capable of evaporating the organic solvent can be adopted as a method for separating the mixed solvent and the organic contaminant. For example, it is usually heated at 60-100 ° C., preferably 60-80 ° C. with a heater. The heating method is not particularly limited, but it may be a continuous type or a batch type, and may be heated at normal pressure or reduced pressure. Moreover, according to the kind of organic solvent, you may perform a heating process at still higher temperature.

(4) Mixed solvent regeneration step (step S104)
This step is a step of regenerating so that the mixed solvent evaporated in the second separation step is circulated and used. In this embodiment, by regenerating the mixed solvent, the regenerated mixed solvent can be circulated and used in a detoxification treatment system for soil contaminated with organic pollutants. For this reason, waste of the solvent can be eliminated, and the operating cost of the detoxification process can be reduced. As the method for regenerating the mixed solvent in the present embodiment, a known method that can be changed to a liquid state from the evaporated state of the organic solvent can be employed. For example, using a cooling device, the HFC and organic solvent constituting the mixed solvent are cooled below the boiling point. The method is not particularly limited, but it is preferable to cool by pressurization.

(5) Pollutant detoxification process (step S105)
This step is a step of detoxifying the organic pollutant obtained in the second separation step. In this embodiment, it is preferable to detoxify organic pollutants using supercritical water oxidation. Specifically, for example, using a pressure-resistant trap made of stainless steel, putting an appropriate amount of sodium nitrate into the trap, sealing, putting it in an electric furnace at 450 ° C., and letting it stand for 1 hour, the inside of the trap becomes a supercritical state. Therefore, organic pollutants such as PCBs are completely decomposed and detoxified. However, the supercritical water oxidation method described above is merely an example, and the organic pollutant may be decomposed by a detoxification method for other organic pollutants, such as a thermal decomposition method or a dechlorination method. .

  The preferred embodiments of the method for detoxifying contaminated soil and the system thereof according to the present invention have been described above. As a result, it is possible to efficiently detoxify contaminated soil containing organic pollutants such as POPs or dioxins using a simple apparatus in a short time, and the processing cost can be reduced.

  Next, the Example of the detoxification processing method of the contaminated soil which concerns on this invention is described. However, the present invention is not limited to the following examples. Note that, in each of the following embodiments, overlapping description is omitted for each common implementation method. In each Example described below, the cleaning status of the organic chlorine compound contained in the contaminated soil and the residual status of the organic chlorine compound were grasped from a GC / MS spectrum measured using a GC / MS QP5000 manufactured by Shimadzu Corporation.

A. Procedure
(Example 1)
First, a mixed solvent containing 5 volumes of acetone was prepared for 100 volumes of HFC. Next, 10 g of soil contaminated with 100 ppm of PCB and 30 ml of the above mixed solvent were placed in a sealed container. Subsequently, after stirring at room temperature for 30 minutes, suction filtration was performed to perform solid-liquid separation. Thereafter, the filtrate (mixed solvent) was evaporated with an evaporator, the residue was dissolved with 2 ml of hexane, and this was used as a sample for GC / MS spectrum measurement for confirming the washing status of PCB contained in the contaminated soil.

  Further, the filtered residue was dried, and 5 g of the dried residue was weighed, mixed with 50 ml of hexane, and stirred by ultrasonic for 30 minutes. After separating the solid by filtration, the entire amount of the filtrate is evaporated by an evaporator, the residue is dissolved with 2 ml of hexane, and this is GC / MS for confirming the PCB concentration remaining in the soil after washing. A sample for spectrum measurement was obtained.

(Example 2)
In this example, hexane was used in place of the solvent acetone to prepare a mixed solvent. The processing procedure was the same as that in Example 1. Samples for GC / MS spectrum measurement for confirming the state of washing of PCB contained in the contaminated soil after treatment and the concentration of PCB remaining in the soil after washing were obtained.

Example 3
In this example, methanol was used in place of the solvent acetone to prepare a mixed solvent. The processing procedure was the same as that in Example 1. Samples for GC / MS spectrum measurement for confirming the state of washing of PCB contained in the contaminated soil after treatment and the concentration of PCB remaining in the soil after washing were obtained.

Example 4
In this example, ethanol was used instead of the solvent acetone to prepare a mixed solvent. The processing procedure was the same as that in Example 1. Samples for GC / MS spectrum measurement for confirming the state of washing of PCB contained in the contaminated soil after treatment and the concentration of PCB remaining in the soil after washing were obtained.

(Comparative Example 1)
First, 10 g of soil contaminated with 100 ppm of PCB and 30 ml of HFC were placed in a sealed container. Subsequently, after stirring at room temperature for 30 minutes, suction filtration was performed to perform solid-liquid separation. Thereafter, the filtrate (mixed solvent) was evaporated with an evaporator, the residue was dissolved with 2 ml of hexane, and this was used as a sample for GC / MS spectrum measurement for confirming the washing status of PCB contained in the contaminated soil.

  Further, the filtered residue was dried, and 5 g of the dried residue was weighed, mixed with 50 ml of hexane, and stirred by ultrasonic for 30 minutes. After separating the solid by filtration, the entire amount of the filtrate is evaporated by an evaporator, the residue is dissolved with 2 ml of hexane, and this is GC / MS for confirming the PCB concentration remaining in the soil after washing. A sample for spectrum measurement was obtained.

B. Analysis Results FIG. 3 shows the results of GC / MS measurement of a 100 pmm PCB standard solution diluted with hexane. 4 to 7 are GC / MS spectra for confirming the cleaning status of PCB contained in the contaminated soil under the conditions of Examples 1 to 4, respectively. Moreover, FIGS. 8-11 is a GC / MS spectrum for confirming the PCB density | concentration which remains in the soil after wash | cleaning on the conditions of Examples 1-4, respectively. FIG. 12 is a GC / MS spectrum for confirming the cleaning status of PCB contained in the contaminated soil under the conditions of Comparative Example 1. FIG. 13 is a GC / MS spectrum for confirming the PCB concentration remaining in the soil after washing under the conditions of Comparative Example 1.

  As shown in FIG. 3, peaks 1 to 3 are PCBs (molecular weight 222) containing 2 chlorines, peaks 4 to 11 are PCBs (molecular weight 256) containing 3 chlorines, and peaks 11 to 21 are PCB containing 4 chlorines (molecular weight 290). Peak 9 at a retention time of 9.15 min was clearly detected as the strongest peak.

  The numerical value in the upper right part of each spectrum shown in FIGS. 4 to 7 and FIG. 12 is proportional to the concentration of the strongest peak 9. As shown in FIG. 4 to FIG. 7 and FIG. 12, compared with Comparative Example 1, the cleaning efficiency of PCB contained in the contaminated soil under the conditions of Examples 1 to 4 is 1.18 times and 1.17 times, respectively. 1.36 times and 1.61 times. From these results, it was found that by adding an organic solvent to HFC, the cleaning efficiency of PCB contained in the contaminated soil is improved, and practical use as a method for detoxifying the contaminated soil can be expected.

  Moreover, as shown in FIGS. 8 to 11 and FIG. 13, the height of the peak 9 of PCB remaining in the soil after washing under the conditions of Comparative Example 1 is 3.2. Compared with the height of the peak 9, the height of the peak 9 of PCB remaining in the soil after washing under the conditions of Examples 1 to 4 is 2.9, 3.1, and 2.2, respectively. 2.4. From these results, it was determined that by adding an organic solvent to the HFC, the cleaning efficiency of the PCB contained in the contaminated soil was improved, and the PCB could be removed efficiently.

  Next, another embodiment of the method for detoxifying water contaminated with benzene will be described. However, the present invention is not limited to the following examples. In the examples described below, the cleaning status of benzene contained in water and the residual status of benzene were grasped from NMR spectra measured using a nuclear magnetic resonance apparatus (JEOL GX-500 NMR Spectrometer).

A. Treatment procedure First, water contaminated with 0.05% benzene and HFC were put into a 100 ml separatory funnel at a volume ratio of 5: 1 (mixed with 50 ml of contaminated water and 10 ml of HFC) and shaken sufficiently. Left for 10 minutes. As a result, the HFC phase was separated into two layers, and the aqueous phase was separated into two layers. Thereafter, the lower HFC phase was collected. Further, the aqueous phase close to the separation interface was discarded so that HFC was not mixed into the aqueous phase, and the upper aqueous phase was separated. For this reason, benzene contained in the contaminated water was selectively extracted into HFC by the separation treatment. Further, in order to confirm the extraction status of benzene, 5 ml of each of the collected HFC phase and aqueous phase was collected, named HFC-1 and water-1, and used as a sample for measurement.

  Subsequently, 10 ml of HFC is added to the collected aqueous phase, and the mixture is again put into a separatory funnel. After performing the same liquid separation treatment as described above, in order to confirm the extraction state of benzene, 5 ml of the collected HFC phase and water phase were collected, named HFC-2 and water-2, and a sample for measurement. It was.

B. Analysis results Table 1 is a table showing the extraction effect of benzene under the conditions of the examples in the method for detoxifying water contaminated with benzene.

  In the results of the examples, as shown in Table 1, when water (stock solution) contaminated with 0.05% benzene was extracted once with 1/5 volume of HFC, it was contained in water-1 compared to the stock solution. Benzene was reduced to about 1/5. At the same time, a high concentration of benzene was detected in HFC-1. When the same liquid separation operation was repeated twice, a peak of benzene from water-2 was not detected in the second extraction. In addition, about 1/10 of the benzene was detected in the second extract (HFC-2) in the first extract (HFC-1).

  From the results as described above, it was possible to effectively remove benzene contained in the contaminated water by performing extraction only once using HFC, and high extraction ability of HFC with respect to benzene was demonstrated. The method for detoxifying water contaminated with benzene according to the present invention is a conventional harmless treatment method, for example, harmless treatment such as treatment in which an oxidizing agent or a reducing agent is added to an aqueous solution contaminated with benzene and irradiated with electromagnetic waves. Compared with the chemical treatment method, the contaminated water can be purified in a short time, at a low cost and with little influence on the surrounding environment.

  INDUSTRIAL APPLICATION This invention can be utilized in the industry which processes soil contaminated with organic pollutants, such as POPs or dioxins, detoxifying.

It is the schematic of the processing system which performs the detoxification process of the contaminated soil which concerns on embodiment of this invention. It is a flowchart which shows the procedure of the detoxification processing method of the contaminated soil which concerns on embodiment of this invention. It is a result of GC / MS measurement of a PCB standard solution having a concentration of 100 pmm diluted with hexane. It is a GC / MS spectrum for confirming the washing condition of PCB contained in the contaminated soil under the conditions of Example 1. It is a GC / MS spectrum for confirming the washing condition of PCB contained in the contaminated soil under the conditions of Example 2. It is a GC / MS spectrum for confirming the washing condition of PCB contained in the contaminated soil under the conditions of Example 3. It is a GC / MS spectrum for confirming the washing condition of PCB contained in the contaminated soil under the conditions of Example 4. 2 is a GC / MS spectrum for confirming the PCB concentration remaining in the soil after washing under the conditions of Example 1. It is a GC / MS spectrum for confirming the PCB density | concentration which remains in the soil after wash | cleaning on the conditions of Example 2. FIG. 4 is a GC / MS spectrum for confirming the PCB concentration remaining in the soil after washing under the conditions of Example 3. 4 is a GC / MS spectrum for confirming the PCB concentration remaining in the soil after washing under the conditions of Example 4. It is a GC / MS spectrum for confirming the washing condition of PCB contained in the contaminated soil under the conditions of Comparative Example 1. 4 is a GC / MS spectrum for confirming the PCB concentration remaining in the soil after washing under the conditions of Comparative Example 1.

Claims (9)

A method for detoxifying contaminated soil containing organic pollutants such as POPs or dioxins,
A washing step of adding a mixed solvent composed of a hydrofluorocarbon and an organic solvent to the contaminated soil, and washing the contaminated soil with the mixed solvent at least once;
A first separation step of separating the mixed solvent containing the organic pollutant and soil;
A second separation step of separating the mixed solvent containing organic contaminants and the organic contaminants;
A detoxification process for decomposing the separated organic pollutants,
A detoxification method for contaminated soil, comprising:   The method for detoxifying contaminated soil according to claim 1, further comprising a regeneration step of performing the second separation step and regenerating the mixed solvent so that the mixed solvent is circulated and used.   The method for detoxifying contaminated soil according to claim 1 or 2, wherein the detoxification step for decomposing the organic pollutant is performed by a supercritical water oxidation method.   The method for detoxifying contaminated soil according to any one of claims 1 to 3, wherein the mixed solvent contains 5 volumes of an organic solvent with respect to 100 volumes of the hydrofluorocarbon.   The method for detoxifying contaminated soil according to any one of claims 1 to 4, wherein the organic solvent is acetone, hexane, methanol, or ethanol.   The method for detoxifying contaminated soil according to any one of claims 1 to 5, wherein the organic pollutant is polychlorinated biphenyls. A system for detoxifying contaminated soil containing organic pollutants such as POPs or dioxins,
A washing means for adding a mixed solvent composed of hydrofluorocarbon and an organic solvent to the contaminated soil, and washing the contaminated soil with the mixed solvent at least once;
First separation means for separating the mixed solvent containing the organic pollutant and soil;
A second separation means for separating the mixed solvent containing the organic pollutant and the organic pollutant; a detoxification means for decomposing the separated organic pollutant;
A detoxification treatment system for contaminated soil, comprising:   The decontamination of contaminated soil according to claim 7, further comprising storage means for storing the mixed solvent regenerated so as to circulate and use the mixed solvent when performing the second separation means. Processing system.   The decontamination processing system for contaminated soil according to claim 7 or 8, wherein the cleaning unit includes an oscillation unit that generates ultrasonic waves.

Images