JP2004261767A - Recycling system of contaminated soil and storing device of contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that there has been no system for inexpensively recycling the soil containing persistent organic pollutants (POPs) instead of control-reclaiming of the POPs contained soil as industry waste. <P>SOLUTION: The contaminated soil containing the POPs is transferred to a treating vessel. Then after a solvent dissolving the POPs is injected into the treating vessel and is stored for a predetermined period of time, such cleaning processes are performed that part or all of the solvent dissolving the POPs in the treating vessel is discharged from the treating vessel and that the POPs to be dissolved in the solvent are eluted into the solvent and separated from the soil. Thereby, the concentration of the POPs in the contaminated soil is lowered to lower than a level to be accepted as a cement raw material, and then the soil containing the POPs is dried, removing the solvent remaining in the soil, to be used for the cement raw material as recycled soil. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to persistent organic pollutants (POPs),
(1) Hard to decompose in the environment (hard to decompose)
(2) Easily concentrated in living organisms due to food chains (high accumulation)
(3) It is easy to accumulate in polar regions, etc., by moving over long distances (long-distance mobility)
(4) Harmful to human health and ecosystem (toxic)
Since it is a chemical substance with the above properties and pollution has been reported on a global scale, it is necessary to respond in an international framework.
There are 12 kinds of target substances, aldrin, dieldrin, endrin, chlordane, heptachlor, toxaphen, mirex, hexachlorobenzene, PCB, DDT, dioxins, and furans.
Any one or more of these 12 types of substances are contained in soil, and soil contamination has been problematic.
The present invention relates to a soil containing POPs, in which a solvent is infiltrated into the soil and allowed to stand for a predetermined period of time, then the used solvent is removed, and particularly, POPs such as PCBs and dioxins are eluted into the solvent. The concentration of POPs remaining in the soil is a legal standard value that can be accepted as a cement raw material (for example, in the case of PCB, graduation from the treatment specified in the "Special Law on Promotion of Proper Treatment of Polychlorinated Biphenyl Waste") The standard is 0.003 ppm or less, or less than 0.0005 ppm described as an environmental standard) .After that, the solvent remaining in the solvent-containing soil is further removed by a soil drying device to obtain regenerated soil. A recycling system that reuses purified soil for the purpose of using this recycled soil as a raw material for cement. Is shall.
[0002]
[Prior art]
Conventionally, a soil containing POPs, for example, a soil containing PCB which is one of POPs, is used in place of a part of a clay constituting a raw material for producing cement clinker, and a soil containing PCB is replaced with another clinker. There is a method of completely decomposing and detoxifying PCBs by firing at 1300 ° C. to 1450 ° C. where clinker is produced in a cement kiln together with the raw materials. (Patent Document 1)
[0003]
[Patent Document 1]
JP-A-2000-247696 (pages 1 and 2)
[0004]
[Problems to be solved by the invention]
However, in the above-mentioned conventional method, since the soil containing PCB, which is one of POPs, is used as an alternative component of the clay constituting the cement clinker without being treated, the following (1) to (4) The problem of the characteristics of POPs remains,
(1) Hard to decompose in the environment (hard to decompose)
(2) Easily concentrated in living organisms due to food chains (high accumulation)
(3) It is easy to accumulate in polar regions, etc., by moving over long distances (long-distance mobility)
(4) Harmful to human health and ecosystem (toxic)
Actually, there is a problem in handling soil containing PCB, which is one of POPs, and soil containing PCB, which is one of POPs, comes into contact directly with the cement kiln for detoxification treatment and contaminates. I do.
[0005]
In general, the contaminated soil is temporarily stored and transported in a storage device that can be sealed, for example, before being transported to the treatment facility. At this time, the POPs are contaminated by direct contact of the inner wall of the storage device with the contaminated soil. This makes the storage device difficult to reuse.
[0006]
Also, PCB, which is one of POPs, is difficult to decompose as shown in (1), so the internal temperature of the kiln is also high (1450 ° C. or higher). If it is not incinerated, decomposition is not complete. The possibility of generating certain dioxins is high and requires careful treatment such as installing a secondary combustion device.
In other words, when incinerating PCB, which is one of the POPs, it is necessary to thoroughly investigate and confirm the PCB decomposition capacity, PCB emission concentration, surrounding environmental concentration, etc. of the PCB combustion facility (kiln) in advance. It is stated in the notice of the Director of Conservation (Environmental Regulation No. 141, December 22, 1972).
Also, in terms of energy, since the kiln internal temperature is high, the running cost is high because the amount of energy used is high as compared with a normal cement production process.
[0007]
Even in the construction of kilns, PCBs, which are one of the POPs that are harmful to human health and ecosystems, cannot be processed by ordinary kilns and are toxic to the treatment of exhaust gas and the like. It is indispensable to deal with a configuration that renders it harmless.
[0008]
An object of the present invention is to provide a recycling system in which a predetermined amount of POPs is removed from soil contaminated by POPs to obtain a reclaimed soil and reused as a cement raw material. It is another object of the present invention to provide a storage device for contaminated soil required for temporarily storing and transporting contaminated soil caused by POPs.
[0009]
[Means for Solving the Problems]
In order to solve the above-mentioned conventional problems, the present invention relates to a soil containing persistent organic pollutants (POPs), a solvent for dissolving POPs, a treatment tank for holding a solvent for dissolving POPs, and a soil drying method. Equipped with a device and a concentration monitoring device capable of measuring or estimating the amount of persistent organic pollutants contained in the soil, first transferring the soil containing POPs to the treatment tank, and then dissolving the POPs in the treatment tank And after leaving for a predetermined period of time, a part or all of the solvent for dissolving the POPs in the treatment tank is extracted from the treatment tank, and a washing step of eluting and separating the solvent into the solvent for dissolving the POPs is performed once or more. After confirming that the concentration of the persistent organic pollutants contained in the soil is lower than the standard accepted as a cement raw material by a concentration monitoring device, the soil is further dried by a soil drying device. Shimete, and playback soil by removing solvent which dissolves the POPs remaining in soil containing POPs, the reproduction soil is characterized in that recycled raw material for cement.
According to this configuration, the POPs-containing soil can be purified only by immersion in a solvent, so that the POPs-containing soil can be implemented at low cost without requiring a special device, and is reused industrially as a cement raw material to promote the purification treatment.
[0010]
Further, a solvent regenerating apparatus is provided for regenerating as a solvent for extracting and removing residual organic pollutants by separating and removing at least a part other than the solvent from the mixed solution, and water separated and recovered from the soil together with the solvent after immersing the soil. The solvent is separated from the solvent by a solvent regenerating device, and at least a part of the separated water is mixed with the regenerated soil and used as a cement raw material. With this additional configuration, the burden on the water treatment facility required to discharge the water separated from the soil can be reduced.
[0011]
When the regenerated soil has a shortage of constituent components as a cement raw material, the lacking components are mixed to form a cement raw material. With this additional configuration, the quality when used as a cement raw material can be stabilized, and the amount employed as a raw material can be increased.
[0012]
Furthermore, using a storage device that holds the soil containing the persistent organic contaminant in a biodegradable sheet or a biodegradable film, and from this storage device, the biodegradable sheet or the biodegradable film And removing the soil containing the residual organic pollutants and transferring the soil to a treatment tank. With this additional configuration, it is possible to prevent the working environment from being greatly contaminated by POPs together with dust generated when the soil is transferred to the processing tank, and the processing proceeds more safely.
[0013]
In addition, the storage device of the present invention is characterized in that, for contaminated soil containing persistent organic pollutants (POPs), the soil can be contained and held in a biodegradable sheet or a biodegradable film. is there. According to this configuration, the inner wall of the storage device is not contaminated with POPs, the outside of the storage device can be easily reused, and the storage cost can be reduced.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows an example of a processing flow. First, soil containing persistent organic pollutants (POPs) is transferred into a treatment tank capable of holding soil and a solvent. Thereafter, a solvent for dissolving POPs contained in the soil is introduced from the solvent supply device into the treatment tank until the soil is sufficiently immersed. If left as it is for a predetermined time (for example, 2 to 24 hours), at least a part of the residual organic pollutants (POPs) dissolves in the solvent. Thereafter, the solvent is removed from the treatment tank, and the residual concentration of the residual organic pollutants (POPs) contained in the soil in the treatment tank is measured or estimated. If this concentration is higher than the target reference value, the solvent is again introduced into the processing tank, and the standing and the confirmation of the concentration are repeated. If the concentration is lower than the reference value, the soil in the treatment tank is dried to make the soil regenerated. In the present process, a process is described in which the components of the regenerated soil are further confirmed, and if the components are not sufficient, the components are added and used as a raw material for cement.
[0015]
In this treatment process, when the soil containing residual organic pollutants (POPs) is washed with a solvent to obtain a cement raw material, if the components (eg, silica, alumina, etc.) as the cement raw material are insufficient, , Mix the missing components and provide as a high quality cement raw material. However, the cement factory has already been manufacturing while adjusting the components, and it is of course possible to supply the cement to the cement factory as a raw material for the cement when it is dried and used as recycled soil.
[0016]
Solvents include alcoholic solvents such as ethyl alcohol, methyl alcohol, isopropyl alcohol, ethylene glycol, diethylene glycol, propylene glycol and dipropylene glycol, paraffinic solvents such as hexane, aromatic solvents such as xylene and toluene, kerosene, and Cosmo Petrotech. Petrozole, Nuclean P-IS, Shiro Japan Loin, Nikko Petrochemical Co., Ltd. Nikko White Co., Ltd., and other petroleum solvents such as soybean oil, limonene, etc., can be used alone or in combination. . However, when the soil containing persistent organic pollutants (POPs) is immersed, alcohol-based solvents or plants that are highly compatible with water also elute the persistent organic pollutants (POPs) dissolved in water. The washing process is selected so that the extraction solvent remains in the soil. For example, it is preferable that the cleaning is always performed by using at least one of an alcohol solvent and a plant extraction solvent.
[0017]
The time for immersion in the solvent depends on the eluted concentration of the residual organic pollutants (POPs), and can be determined by sampling the target soil and confirming the elution characteristics. In order to shorten the immersion time as much as possible to shorten the cleaning time, it is of course possible to continuously or intermittently stir in the treatment tank and / or slightly raise the solvent temperature in the treatment tank. However, in order to suppress heating costs, volatilization from the inside of the treatment tank, and avoid fire, it is preferable that the vapor pressure of the solvent be 100 mmHg or less, or the ignition temperature, whichever is lower. In an environment where a solvent is used (in a house), it is preferable to humidify in order to avoid ignition due to static electricity.
[0018]
The immersion treatment of the contaminated soil with this solvent is performed not only with the same solvent but also with a solvent having a high solubility for POPs contained in the soil among the above-mentioned solvents, such as a petroleum solvent or an aromatic solvent. First, the effect of separating and extracting POPs is enhanced, and the solvent remaining in the reclaimed soil is considered. Finally, for example, an alcohol-based solvent having little residual problem, or a plant-based solvent such as soybean oil or limonene is used. Of course, washing can be performed once or more. At this time, for example, when washing with only an alcohol-based solvent or a plant extraction-based solvent, the solubility is low, so that the number of washings is increased and the processing cost is increased. it can.
[0019]
In addition, water from the soil containing the solvent and the persistent organic pollutants (POPs) is supplied from the solvent supply device and kept for a predetermined time (for example, 2 to 24 hours). Pull out and store temporarily in the storage tank. Thereafter, the solid content and the moisture can be separated by distillation means and regenerated as a solvent.
[0020]
On the other hand, if the concentration of persistent organic pollutants (POPs) in the treatment tank is lower than the standard accepted as a raw material for cement (for example, in the case of PCB, the "Special Measures Act on Promotion of Proper Treatment of Polychlorinated Biphenyl Waste") The graduation standard of 0.003 ppm or less for the treatment specified in “) or less than 0.0005 ppm specified as the environmental standard is adopted). However, the solvent containing residual organic pollutants (POPs) contains no solvent. Since the soil remains, in drying the soil, the solvent is removed by a soil drying device (for example, a boiler, a drying furnace, a hot air generator, etc.), and the soil is regenerated. The recycled soil is used as a cement raw material, and can be recycled as a safe cement raw material without landfilling a landfill of a managed type for treatment of soil containing persistent organic pollutants (POPs), which is industrial waste.
[0021]
Also, considering the use of landfill as reclaimed soil, even if it is below the standard value, it can not be easily reused as landfill soil in places near general residential areas, and it must be purified to a lower concentration, for example, It is required to be at a level that is か ら to 1/10 lower than the reference value, and the purification cost is likely to be high.
However, according to the present invention, by making the value lower than the legal standard value (as described above) that is acceptable as a cement raw material, the cement can be safely and efficiently reused, and the purification of contaminated soil is promoted. This is because in the cement production process, heat treatment is performed at a high temperature of 1000 ° C. or more, so that contamination with very low concentration of persistent organic pollutants (POPs) can be safely treated.
[0022]
It should be noted that water contained in the soil is recovered together with the solvent used for the extraction and separation of POPs. It is preferable that the solvent after the extraction is separated into solids, POPs, and water by a solvent regenerating device such as distillation, and reused as a solvent for extraction. Further, it is more preferable that the solvent remaining in the regenerated soil volatilized and recovered by a soil drying device and liquefied through a condenser is recycled as a solvent by the present device. In addition, some POPs may remain in the separated water, and after being subjected to wastewater treatment, the POPs are discharged to sewage or natural rivers.
[0023]
In addition, this solvent regenerating apparatus can regenerate as a solvent, separate and recover the water originally contained in the soil, and mix at least a part of the separated water with the reclaimed soil to use as a cement raw material. it can. At this time, as described above, equipment for wastewater treatment for discharging sewage and natural rivers is unnecessary or can be reduced in processing capacity. Further, it is assumed that the concentration of the residual organic pollutants (POPs) in the reclaimed soil is slightly increased by returning the water, but, of course, the residual organic pollutants (POPs) are mixed to an extent lower than the standard accepted as a cement raw material. For example, the residual organic pollutant (POPs) concentration of the separated and recovered water is measured from the residual organic pollutant (POPs) concentration of the reclaimed soil measured by the concentration monitoring device (for example, the concentration is measured by the concentration monitoring device). ) Is measured, and the mixing amount is determined so as to be less than the reference value.
[0024]
The soil containing persistent organic pollutants (POPs) can be stored in a storage device while being included in a biodegradable sheet or a biodegradable film. At this time, the soil is taken out of the storage device and transported to the treatment tank with the soil contained therein, whereby the diffusion of the soil into the atmosphere due to the transfer can be minimized. It is also preferable to break the biodegradable sheet or biodegradable film as small as possible to transfer the soil containing persistent organic pollutants (POPs) so that the sheet or film does not hinder the penetration of the solvent into the soil.
[0025]
For the soil containing persistent organic pollutants (POPs), a storage device for temporarily storing the soil is provided, and the soil containing persistent organic pollutants (POPs) is biodegradable sheet or biodegradable film, etc. , It is possible to prevent the persistent organic pollutants (POPs) and the inner wall of the storage device (for example, a drum) from directly contacting the soil containing the persistent organic pollutants (POPs). Is not contaminated with persistent organic pollutants (POPs) and can be easily reused.
[0026]
Also, as described above, by purifying the biodegradable sheet or biodegradable film together with the soil, when leaving the reclaimed soil before using as a cement raw material, the sheet or film used for the biodegradable zipper Decomposition proceeds, and transport of the reclaimed soil is further facilitated. In addition, even when a part is used as landfill soil, spontaneous decomposition proceeds even after burying, and as in the case of using a general polyolefin film, a long-term film or sheet-like material does not remain, It does not remain as industrial waste and the soil is improved.
[0027]
(Example 1)
A first embodiment of the present invention will be described with reference to FIG. FIG. 2 is a flowchart of a recycling system for contaminated soil.
[0028]
The soil 1 containing persistent organic pollutants (POPs) is contained in a biodegradable wrapper (biodegradable sheet or biodegradable film) 2 and stored with a storage device (for example, a drum) 3 and a sealing lid 4. A storage device (for example, a drum) 3 is provided with a biodegradable wrapper (biodegradable sheet or biodegradable film) 2 and the soil 1 containing persistent organic pollutants (POPs) is put into a storage device (for example, a drum) 3. Even if the lid is closed, the soil 1 containing persistent organic pollutants (POPs) does not directly adhere to the storage device (for example, a drum) 3.
[0029]
The soil 1 containing persistent organic pollutants (POPs) contained in the biodegradable wrapper (biodegradable sheet or biodegradable film) 2 stored in the storage device (for example, a drum) 3 is put into the treatment tank 5. I do.
At this time, the biodegradable wrapper (biodegradable sheet or biodegradable film) 2 is broken so that the soil 1 containing residual organic pollutants (POPs) does not scatter outside, and the treatment tank 5 is made of a material compatible with POPs. Have been.
At this time, the torn biodegradable zipper (biodegradable sheet or biodegradable film) 2 can also be put into the processing tank 5. Also, since only the surface of the biodegradable wrapper (biodegradable sheet or biodegradable film) 2 is in contact, it can be broken more finely and mixed with the reclaimed soil 18 during the cement production process.
[0030]
By breaking the biodegradable wrapper (biodegradable sheet or biodegradable film) 2 into the treatment tank 5, the soil 1 containing the persistent organic pollutants (POPs) is thrown in, and up to about 85% of the capacity of the treatment tank 5 After the soil 1 containing persistent organic pollutants (POPs) is charged, the upper lid 6 of the processing tank 5 is closed, and the upper closed handle 7 is closed, the solvent 9 is injected into the processing tank 5 from the solvent supply device 8, and the residual Soaked soil 1 containing volatile organic pollutants (POPs).
Although the injection amount of the solvent 9 is not shown, it is injected by a liquid level meter to a position where the soil 1 containing the residual organic pollutants (POPs) is completely immersed and left for a predetermined time (2 to 24 hours in the experiment by the present inventor). It is shown that the residual organic pollutants (POPs) from the soil 1 containing the residual organic pollutants (POPs) are eluted by the solvent 9 and that the POPs contained in the soil can be reduced. Was proved in
[0031]
After the soil 1 containing the persistent organic pollutants (POPs) immersed in the solvent 9 is left for a predetermined time, the valve 14 below the treatment tank 5 is opened, and the solvent 9 and the residual organic pollutants eluted by the solvent 9 ( POPs), and a mixed liquid 15 composed of water and the like contained in the soil 1 containing the residual organic pollutants (POPs) is drawn into the storage tank 10.
The residual organic pollutants (POPs) contained in the soil 1 containing the persistent organic pollutants (POPs) are measured and estimated from the mixed solution 15 using the concentration observing device 11, and the concentration of the persistent organic pollutants (POPs) is measured. To determine whether or not the graduation standard is acceptable as a cement raw material.
In the present embodiment, the concentration observation device 11 is configured by a process of sampling the mixed solution 15 and replacing the sample with the normal hexane with a gas chromatogram. At this time, by preparing in advance a calibration curve of the concentration of the persistent organic pollutants (POPs) contained in the soil and the concentration of the mixed solution, the residual organic pollutants (POPs) remaining in the soil from the mixed solution are prepared. ) Can be estimated.
[0032]
When the numerical value of the concentration monitoring device 11 is equal to or less than the graduation standard accepted as a cement raw material (for example, in the case of PCB, the graduation standard of the treatment specified in the “Special Law on Promotion of Proper Treatment of Polychlorinated Biphenyl Waste” is 0). (Less than 0.003 ppm) transfers the washed residual organic pollutant (POPs) -containing soil 1 to a drying furnace (a rotary kiln or the like) 19 and is dried to produce a reclaimed soil 18 as a raw material for cement. At this time, it is preferable to control the concentration of the residual organic pollutants (POPs) in the kiln exhaust gas.
[0033]
If the value of the concentration monitoring device 11 is not accepted as a cement raw material, the valve 14 below the treatment tank 5 is opened, and the solvent 9 and the residual organic pollutants (POPs) eluted by the solvent 9 from the soil 1 containing the residual organic pollutants (POPs) are removed. Water contained in the soil 1 containing the volatile organic pollutant (POPs) and the soil 1 containing the persistent organic pollutant (POPs) is drawn into the storage tank 10, the valve 14 below the treatment tank 5 is closed, and the solvent is supplied from the solvent supply device 8. A new solvent 9 is injected into the treatment tank 5 to soak the soil 1 containing persistent organic pollutants (POPs).
Although the injection amount of the solvent 9 is not shown, it is injected by a liquid level meter to a position where the soil 1 containing the residual organic pollutants (POPs) is completely immersed and left for a predetermined time (2 to 24 hours in the experiment by the present inventor). The residual organic pollutants (POPs) from the soil 1 containing the persistent organic pollutants (POPs) are eluted by the solvent 9 and are dissolved in the solvent 9. The residual organic pollutants (POPs) of the soil 1 containing the persistent organic pollutants (POPs) are reduced to a level lower than the standard accepted as (for example, 0.003 ppm or 0.0005 ppm as described above in the case of PCB). Elute in solvent 9.
[0034]
The number of elutions depends, of course, on the initial POPs concentration. In this experiment, in the case of soil 1 containing 100 mg / kg of PCB (Kanechlor KC400) containing persistent organic pollutants (POPs), when alcohols, especially ethanol, were used as solvent 9, the average was 3 times. Four washes were performed.
The PCB residual concentration of the residual organic pollutant (POPs) -containing soil 1 was determined by sampling the soil 1 containing the residual organic pollutant (POPs) after washing and measuring the concentration by ECD gas chromatography according to the PCB measurement method. It was measured.
[0035]
Further, the mixed liquid 15 in the storage tank 10 is sent to the distillation column 12A, where alcohols having a low boiling point are first vaporized and liquefied by the condenser (condenser) 13A through the upper part of the distillation column 12A, and the solvent is stored. It is stored in the tank 16A. When a certain amount of the distilled alcohol in the solvent storage tank 16A is stored, the alcohol is conveyed by a pump, passes through the activated carbon tower 17, and is reused.
[0036]
Next, water having a low boiling point is vaporized in the distillation tower 12B, liquefied in the condenser (condenser) 13B through the upper part of the distillation tower 12B, and stored in the water storage tank 16B. When a certain amount of the distilled water in the water storage tank 16B is stored, it is conveyed by a pump and connected to a sewage treatment process system (not shown) or mixed with the reclaimed soil 18 and put into a drying furnace 19 to be steamed. The liquefied product is again passed through a condenser (condenser) 13C to be liquefied, passed through an activated carbon tower 17, and then conveyed together with regenerated soil 18 dried in a drying furnace 19 to be conveyed as a cement raw material to a cement production process. Is done.
[0037]
The concentrated residual organic pollutants (POPs) separated in the distillation tower 12B are stored and managed in a persistent organic pollutant storage tank 16C together with other solid components such as mineral components such as sand, calcium, and magnesium.
[0038]
The solvent 9 was injected into the treatment tank 5 at least once until the value of the concentration monitoring device 11 became lower than the standard accepted as a cement raw material (for example, 0.003 ppm in the case of PCB). Is distilled and purified in the distillation column 12A and can be used repeatedly.
[0039]
On the other hand, the residual organic pollutant (POPs) -containing soil 1 after washing, in which the value of the concentration monitoring device 11 is lower than the standard (for example, 0.003 ppm in the case of PCB) due to the solvent 9, which is acceptable as a cement raw material. Is a soil drying apparatus (a rotary kiln or the like) 19 as a soil drying apparatus for volatilizing the solvent 9 remaining in the soil, where the residual organic pollutant (POPs) -containing soil 1 And dried to produce a reclaimed soil 18 which is a raw material for cement.
[0040]
(Example 2)
A second embodiment of the present invention will be described with reference to FIG. FIG. 3 is a flowchart 2 of a recycling system for contaminated soil, in which the configuration of the processing tank of FIG. 2 is different from that of the processing tank of FIG.
[0041]
The soil 1 containing residual organic pollutants (POPs) after washing, in which the value of the concentration monitoring device 11 becomes lower than the standard (for example, 0.003 ppm in the case of PCB) that is accepted as a cement raw material by the solvent 9, The solvent 9 and water slightly remain, and the soil containing residual organic pollutants (POPs) after washing is washed by a hot air generator 20 (for example, a boiler, a chiller, or the like) provided in the treatment tank 5 via a pipeline. 1 is dried in the treatment tank 5 without being transferred to the outside to produce a reclaimed soil 18 as a raw material for cement.
In the present embodiment, the concentration observation device 11 is implemented by sampling the regenerated soil 18, extracting it with normal hexane, and measuring it with a gas chromatogram.
[0042]
(Example 3)
Example 3 relates to a solvent regenerating apparatus, which is not shown in FIG. 2 and FIG. It is possible to lower the boiling point by applying a vacuum to the pipe that is passed through the activated carbon tower 17 and reused, the distillation tower 12B for purifying water, the condenser (condenser) 13B, and the pump at the subsequent stage of the water storage tank 16B. is there.
[0043]
By making the vacuum state, the boiling point is lowered and the temperature in the distillation column can be reduced, so that it is needless to say that the same solvent 9 can be reused by lowering the running cost of the heat source.
[0044]
In this embodiment, the case where an alcohol-based solvent was used was shown. However, when normal hexane was used, for example, as shown in Embodiment 1, the mixed solution 15 did not need to be re-extracted with hexane, and sampling was performed. The gas chromatograph measurement can be performed only by removing the solid content from the mixed solution 15. In addition, when a plurality of solvents are used, it is needless to say that arranging a plurality of distillation columns 12A for regeneration facilitates maintenance. Further, in each embodiment, it is not necessary to completely complete the reclaimed soil, and the soil may be naturally dried by leaving.
[0045]
【The invention's effect】
As described above, according to the present invention, soil containing persistent organic pollutants (POPs) is immersed in a solvent, and the numerical value of the concentration monitoring device is accepted as a cement raw material (for example, 0.003 ppm or less for PCB). After that, it can be dried to obtain a safe reclaimed soil, which can be used as a raw material for cement, and can be transferred to a cement manufacturing company as valuable without the need for management-type landfill as industrial waste. .
In addition, since the solvent can be used repeatedly in a solvent regeneration apparatus (distillation / purification), the cost of the solvent can be kept low.
Further, since the storage device includes the soil containing the residual organic pollutants (POPs) in the biodegradable sheet or the biodegradable film, the soil containing the persistent organic pollutants (POPs) does not directly contact the storage device. Pollution can be prevented.
[Brief description of the drawings]
FIG. 1 is a flowchart of a process for treating contaminated soil according to an embodiment of the present invention.
FIG. 2 is a flowchart of a contaminated soil recycling system 1.
FIG. 3 is a flowchart of a contaminated soil recycling system 2.
[Explanation of symbols]
1. Soil containing persistent organic pollutants (POPs)
2. Biodegradable zipper (biodegradable sheet or biodegradable film)
3. Storage device
4 ... Lid
5 ... Treatment tank
6 ... Top lid
7. Sealed handle
8 ... Solvent supply device
9 ... Solvent
10 ... storage tank
11… Concentration observation device
12A… Distillation tower
12B… Distillation tower
13A: Condenser (condenser)
13B: Condenser (condenser)
13C: Condenser (condenser)
14 ... Valve
15 ... mixture
16A ... Solvent storage tank
16B… Water storage tank
16C: Persistent organic pollutant storage tank
17 ... Activated carbon tower
18… Regenerated soil
19 ... Drying oven
20 ... warm air generator

Claims (5)

For soil containing persistent organic pollutants, a solvent that dissolves the persistent organic pollutants, a treatment tank that holds the soil and the solvent, and a soil drying device that volatilizes the solvent contained in the soil. Equipped with a concentration monitoring device capable of measuring or estimating the amount of persistent organic pollutants contained in soil,
First, the soil is transferred to the treatment tank, and then the solvent is injected into the treatment tank and left for a predetermined time.After that, at least a part of the solvent in the treatment tank is withdrawn, and the solvent is removed together with the solvent. A washing step of eluting and separating the residual organic pollutants was performed at least once, and the concentration of the persistent organic pollutants contained in the soil was confirmed to be lower than the standard accepted as a cement raw material by the concentration monitoring device. A recycling system for contaminated soil, characterized in that the soil drying device further removes the solvent remaining in the soil and uses the regenerated soil as a cement raw material. It further comprises a solvent regenerating device for separating and removing at least a part other than the solvent from the mixed solution to regenerate as a solvent for extracting the residual organic pollutants, and the water separated and recovered from the soil together with the solvent after immersing the soil. The contaminated soil recycling system according to claim 1, wherein the solvent is separated from the solvent by the solvent regenerating device, and at least a part of the separated water is mixed with the regenerated soil and used as a cement raw material. The contaminated soil recycling system according to claim 1 or 2, wherein when the regenerated soil has a shortage of constituent components as a cement raw material, the shortage component is mixed to form a cement raw material. Using a storage device that holds the soil containing the persistent organic contaminants in a biodegradable sheet or a biodegradable film, and from the storage device, includes the biodegradable sheet or the biodegradable film. The contaminated soil recycling system according to any one of claims 1 to 3, wherein the soil containing the persistent organic contaminant is taken out and transferred to a treatment tank while keeping the state. A storage device for contaminated soil, wherein the soil containing the persistent organic contaminant can be contained and held in a biodegradable sheet or a biodegradable film.

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