JP4636738B2 - Contaminated soil purification method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a method for separating and removing harmful substances from soil contaminated with harmful substances to ecosystems, and in particular, a method for purifying contaminated soils that separates harmful substances against ecosystems from soil using a surfactant and its Relates to the device.
[0002]
[Prior art]
  Traditionally, soil has been contaminated by improper handling of industrial waste, accidents in transit, ignorant use of pesticides and other chemicals, causing harmful consequences for ecosystems including animals and plants. Not only chemical substances with strong acute toxicity and mutagenicity, but also non-toxic hydrocarbons and oils and fats, destroy the environment suitable for the ecosystem and threaten the survival of living organisms. These harmful substances include, for example, heavy metals such as lead, hexavalent chromium and mercury, organic metal compounds and organic chlorides derived from agricultural chemicals and pesticides, organic chlorides such as PCB and trichlene discharged from the electric industry, and incinerators. Dioxins contained in residual ash, cutting oil and lubricating oil discharged by machinery industry, crude oil from tanker accidents, various by-products and tars from the crude oil refining industry are innumerable. In particular, soil contaminated with polycyclic aromatic hydrocarbons generated from urban traffic, coke production, aluminum refining, etc. is considered extremely toxic. These harmful substances not only harm plants and soil organisms, but they also dissolve in groundwater and rivers, contaminating water quality, volatilizing and diffusing into the atmosphere, and polluting the atmosphere. Other organisms will be adversely affected.
  In particular, polycyclic aromatic hydrocarbons have recently been recognized to increase in the amount released into the environment from plants for producing fossil fuels such as petroleum and coal. Carcinogenesis of the polycyclic aromatic hydrocarbons There are concerns about the effects on the human body and environment of mutagenicity that induces sex or mutation.
[0003]
  For such soil contamination, conventionally, air-drying methods that remove the target substances by crushing the contaminated soil and letting it through the air, solidification and stabilization methods that contain the contaminated soil with concrete, heat that is heat-treated at low or high temperatures There have been used decomposition, thermal desorption methods, microbial decomposition treatment methods in which water, nutrients, air, etc. are supplied to contaminated soil and decomposed by indigenous microorganisms.
  However, the air drying method not only may cause harmful substances to remain in the soil, but also causes air pollution. The solidification / stabilization method has a problem that it is difficult to treat a large amount of soil in addition to monitoring over time leakage of pollutants after treatment. Further, the thermal decomposition and thermal desorption methods require treatment of dioxins generated by the combustion of organic chloride compounds, resulting in high costs. Furthermore, although the microbial decomposition treatment method is low in cost, the treatment time is long and impractical.
[0004]
  Therefore, as a method for treating harmful organic compounds in the soil, a method has been proposed in which a surfactant, alkali or the like is added to the excavated contaminated soil and washed with water to extract the pollutant.
  As one of them, a soil purification method using a surfactant is proposed in JP-A-9-75907. This involves excavating soil contaminated with organic compounds, adding a surfactant solution of a predetermined concentration to the excavated soil in an agitating tank, stirring and mixing to desorb the pollutants, and after the desorption is complete, solid-liquid separation This is a method for separating soil and surfactant solution by an apparatus. The soil from which the surfactant solution has been separated in this manner is returned to the excavation site, and the surfactant solution is reused after removing contaminants in the activated carbon adsorption tank.
[0005]
  In such a treatment method using a surfactant, the soil remediation treatment is inexpensive and simple, but on the other hand, there is a problem that a large amount of contaminated water is generated when the soil is washed. Therefore, it is necessary to add a wastewater treatment facility with a high treatment capacity to the soil washing facility.
  In order to solve such a problem, in Japanese Patent Laid-Open No. 10-216693, as shown in FIG. 3, the contaminated soil B is accommodated in a cleaning tank 02 containing a cleaning water W to which a chemical cleaning agent is added, and chemically cleaned. After separating the pollutant A from the contaminated soil B, supersaturated water in which gaseous components in the air are excessively dissolved is supplied into the wash tank 02 to generate fine bubbles in the wash water W. A pollutant separation method has been proposed in which the pollutant A floats on the surface of the washing water W by being attached to the pollutant A and is recovered.
[0006]
[Problems to be solved by the invention]
  However, in this method, the equipment cost can be greatly reduced by the simplified cleaning system as described above. However, depending on the type of soil, the generation of bubbles in the cleaning tank causes the soil to move along with the contaminants. The amount of final pollutant treatment increases due to floating and collection, and conversely, there is a possibility that the contaminants will remain slightly in the lower soil because the washing tank is always in a fluid state, Even a trace amount such as a polycyclic aromatic hydrocarbon which is a material to be treated in the present invention is not suitable for treatment of a very toxic contaminant.
  Therefore, in view of the problems of the prior art, the present invention can reliably separate harmful substances from a large amount of wastewater discharged by soil washing using a surfactant and circulates and uses water used for washing. An object of the present invention is to provide a contaminated soil purification method and apparatus capable of efficiently performing soil purification treatment including wastewater treatment.
[0007]
[Means for Solving the Problems]
  In order to solve such problems, the present invention provides a washing process for washing soil contaminated with ecosystem harmful substances using a surfactant aqueous solution, a solid phase comprising purified soil, and emulsification incorporating the harmful substances. In the contaminated soil purification method having a solid-liquid separation step of solid-liquid separation into a liquid phase composed of an aqueous surfactant solution containing substances,
  The liquid phase that has been separated into solid and liquid is cooled and frozen to produce ice, thereby concentrating the harmful substance in the liquid phase, thawing the ice from which the harmful substance has been removed, Recycling for soil cleaningPropose as intermediate technology.
[0008]
  Ecosystem harmful substances mentioned here refer to chemical substances that are acutely toxic, mutagenic or teratogenic, or those that adhere to or enter the organism and are necessary for life support such as breathing, sweating, exercise, and digestion / absorption functions. A substance that inhibits function. The former belong to, for example, inorganic substances such as lead, mercury and hexavalent chromium, organic metal compounds such as organic mercury and organic tin compounds, organic chlorides such as trichlorethylene, tetrachloroethylene, polychlorinated biphenyl and benzene hexachloride. , Anthracene, phenanthrene, pyrene, fluoranthene, polycyclic aromatic hydrocarbons such as chrysene, benzopyrene, perylene, those belonging to the latter include, for example, crude oil, crude oil refined distillates, crude oil-derived substances such as mineral oil, tar, etc. There is.
[0009]
  Although the above-mentioned harmful substances include water-soluble substances, many of them are water-insoluble, and in any case, they are adsorbed on the soil particles, so it is necessary to wash the soil with limited time and water. Uses a surfactant that has the function of increasing the wetness of the soil particle surface to dissociate the adsorbed harmful substances, disperse it in the aqueous phase by solubilization or emulsification, and lower the concentration of harmful substances on the surface of the soil particles Is essential.
[0010]
  As the surfactant, any of generally known anionic surfactants, cationic surfactants, amphoteric surfactants and nonionic surfactants can be used. More specifically, for example, anionic surfactants such as sodium fatty acid, alkyl sulfate, alkyl polyoxyethylene sulfate, alkylbenzenesulfonate, α-olefinsulfonic acid, alkyltrimethylammonium salt, triethanolamine, Cationic surfactants such as difatty acid ester quaternary salts, zwitterionic surfactants such as alkyldimethylamine oxide, alkylcarboxybetaine, amide amino acid salts, polyoxyethylene alkyl ethers, polyoxyethylene alkylphenyl ethers, fatty acids It can be selected from nonionic surfactants such as polyoxyethylene ester and fatty acid sorbitan ester, and two or more kinds can be used in combination.
[0011]
  In particular, metal ions such as calcium ions that lower the kraft point of surfactants and reduce their functional effects are included in the soil, so chelating agents and zeolites that have high reactivity with these metal ions, etc. It is also preferable to use a sequestering agent in combination.
[0012]
  And of the present inventionIn intermediate technologyThe wastewater containing harmful substances separated from the soil by surfactants is frozen by cooling with a refrigerator, etc., and impurities such as surfactants and harmful substances are concentrated by generating pure ice that does not contain impurities. By recirculating the water generated by melting the true ice for soil washing, it becomes possible to reliably separate water, surfactants and harmful substances, and further facilitate the reuse of water. Therefore, cost reduction and efficient soil cleaning are possible. In addition, when freezing the waste water, it is preferable to discharge fine bubbles into the waste water and continuously stir and shake with air. By doing so, mass transfer frequently takes place around the nucleus of the water crystal in the wastewater, so that the crystal to be purified subsequently becomes only pure water crystal, which makes it possible to efficiently concentrate and purify the drainage impurities. Done.
[0013]
  AndIn the contaminated soil purification method of the present invention, the separated liquid phase is cooled below the Kraft point of the contained surfactant, heated to a cloud point or higher, or irradiated with ultrasonic waves to cause harmful effects on the liquid phase. The solubilization or emulsification of the substance is disrupted and the upper layer and the lower layer are separated into two layers, and the lower layer containing the harmful substance is cooled and frozen to produce ice, thereby concentrating the harmful substance in the lower layer, and The ice from which harmful substances have been removed is melted, and the generated water is recycled for the soil washing.
[0014]
  This is because the drainage after washing the contaminated soil with the surfactant is cooled to below the Kraft point before freezing, thereby greatly reducing the solubility due to micelle formation of the ionic surfactant. A step of separating the active agent. As is well known, the Kraft point is a temperature at which the solubility of the surfactant due to micelle formation in water rapidly increases. Usually, the solubility is small and useless if the surfactant is not used above this temperature. On the other hand, the solubility of the nonionic surfactant rapidly decreases at a temperature equal to or higher than the cloud point.
[0015]
  In addition, since the surfactant separated in this way has a specific gravity smaller than water, it accumulates in the upper layer, while harmful substances larger than specific gravity water or water-soluble harmful substances move to the lower layer. Of these, the upper layer containing the surfactant can be recycled and reused, so that the cost can be reduced. Furthermore, since the hazardous substance and the surfactant are separated, the hazardous substance treatment in the next process becomes easy. That is, a further feature of the contaminated soil purification method of the present invention is that the surfactant from which harmful substances are removed by separating into two layers is recycled for the soil washing.
[0016]
  Now, when the harmful substance is insoluble in water and the specific gravity is less than water in the liquid phase incorporating the harmful substance obtained by the solid-liquid separation, the temperature is lowered below the Kraft point of the contained surfactant, When an operation of separating and depositing the surfactant and the harmful substance by the action of ultrasonic waves is performed, the harmful substance moves to the upper layer together with the surfactant. In this case, it is necessary to separate the surfactant from the harmful substance by another method, or to transfer the upper layer surfactant to the decomposition step separately to make it harmless.
[0017]
  In addition, the soil cleaning treatment according to the present invention may not always achieve a desired purification by a single batch operation depending on the treatment conditions. That is, the treatment rate ((initial soil contamination concentration-post-treatment soil contamination) depends on the size of the treatment device, the amount of soil to be treated at one time, the amount of usable water limited by this, the ability and concentration of the surfactant. (Concentration) × 100 / initial soil contamination concentration) does not become 100%, but varies depending on conditions. In such a case, the treatment purpose can be achieved by multi-stage treatment that repeats multiple washings according to the final soil concentration of the set soil.The
[0018]
  For example, when it is desired to reduce the contaminated soil to a final concentration of 1 ppm or less that is contaminated with a pollutant concentration of 1000 ppm by the above-mentioned constraint condition, an ultimate treatment rate of only 90% can be obtained by a single cleaning process. If repeated multi-stage cleaning should be performed,
  (1-0.9) n × 1000 ppm ≦ 1 ppm
  10−n ≦ 10−3 ∴n ≧ 3
  That is, the purpose can be achieved by washing three times or more.
[0019]
  An invention of an apparatus that effectively implements these inventionsSuggest below.
[0020]
  In a soil purification apparatus equipped with a soil cleaning means for cleaning soil contaminated with ecosystem harmful substances using an aqueous surfactant solution,
  After washing the soil, cooling the wastewater containing the surfactant that has incorporated the harmful substances below the Kraft point of the surfactant, raising the temperature above the cloud point, or irradiating with ultrasonic waves, A two-layer separation means for breaking the emulsification of the liquid phase and separating the two layers into an upper layer and a lower layer;
  Freeze concentration by cooling and freezing the separated lower layer containing the harmful substancemeansWhen,
  Ice separation and thawing means for separating and thawing ice from which the harmful substances generated by freezing are removed,
  And a washing water preparation device for preparing washing water to be supplied to the soil washing machine using the separated surfactant and water generated by melting ice.
[0021]
  Moreover, in the contaminated soil purification apparatus, the present invention is further characterized in that the freeze concentration means and the ice separation and melting means are performed in the same tank by a heat release / heat absorption cycle of a heat pump.
  Accordingly, by adopting a configuration in which the heat pump cycle / refrigeration cycle are alternately formed in the tank having both the freeze concentration means and the ice separation and thawing means, it becomes a simple facility that eliminates the movement of the true ice, and the installation area is reduced. Reduce.
[0022]
  Furthermore, the present invention provides the ice separation and melting means for melting ice on the condenser side, the freeze concentration means for freezing waste water on the evaporator side, and the surfactant separating means for the surfactant separating means. The melting water of the ice is used for cooling the effluent containing kraft to a temperature below the Kraft point temperature, and the condensation heat during the freeze concentration is converted into a heating heat source of the washing water regulator and a surfactant in the surfactant separating means. It connected with the heat pump utilized for the temperature rising to the cloud point or more of the waste_water | drain containing this.
[0023]
  The washing water regulator needs to be kept above the Kraft point in order to increase the solubility of the surfactant,The two-layer separation meansThen, in order to float and separate the surfactant, it must be kept below the Kraft point or at the cloud point. Therefore, in such an invention, when an ionic surfactant is used, the heat of condensation during the formation of ice is led to the washing water regulator to raise the temperature, and the low-temperature molten water generated by melting of the ice isTwo-layer separation meansWhen the non-ionic surfactant is used while maintaining the surfactant separation means at a low temperature, a soil purification device with high thermal efficiency is provided by utilizing the heat of condensation during ice formation. Is possible.
  In addition to the method of cooling the surfactant separating means using the cold heat from the ice melting water as described above, the method of cooling using the heat of melting when melting the ice may be used. Good.
[0024]
[0025]
[0026]
DETAILED DESCRIPTION OF THE INVENTION
  Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
  FIG. 1 illustrates the present invention.Intermediate technologyFig. 2 shows the overall configuration of the soil purification deviceOf the present invention1 is an overall configuration diagram of an embodiment.
  As shown in FIG.Intermediate technologyThe soil purification apparatus according to the present invention comprises a soil washing step 1 and a freeze concentration step 3, and the soil washing step 1 comprises a soil washing machine 10, solid-liquid separators 11 and 12, and return means 35, and is a freeze concentration step. 3 is composed of a toxic substance separation means 13 and a refrigeration / heat pump device 16 comprising a storage tank 13a, a freeze concentration means 13b, and an ice separation and thawing means 13c.
[0027]
  In the soil washing machine 10 in the soil washing step, for example, a screw feeder that moves the contaminated soil 20 introduced from the inlet of the contaminated soil 20 containing harmful substances to the downstream side by rotation of a helical screw, A cleaning water supply port is provided on the downstream side of the soil cleaning machine 10, and the cleaning water 21 and the surfactant are passed to the soil charging port side so that the contaminated soil is cleaned.
  Further, the solid-liquid separator 11 is provided on the downstream side of the soil washer 10, that is, on the soil discharge port side, and a filter thickener or the like is used to remove liquid from the soil washed by the soil washer 10 by filtration. Good. The soil that has been subjected to solid-liquid separation is configured such that it can be returned to the soil washing machine again by the return means 35 such as a bucket conveyor and repeatedly washed. Further, a solid-liquid separator 12 for separating the soil remaining in the waste water by precipitation is provided on the downstream side.
[0028]
  The freeze concentration step is a step of separating pure water from waste water containing a surfactant that has taken in harmful substances, and includes a harmful substance separation means 13 provided with a storage tank 13a, a freeze concentration means 13b, and an ice separation and melting means 13c. And a refrigeration / heat pump device 16. The freeze concentration means 13b is located on the evaporator side of the refrigeration / heat pump device 16 to form a refrigeration cycle 16a. The pure water is frozen by cooling the waste water stored in the freeze concentration means 13b. It is configured to separate from impurities. On the other hand, the ice separating and melting means 13c is located on the condenser side of the refrigeration / heat pump device 16 to form a heat pump cycle 16b, and the pure water 29 melted thereby is circulated to the soil washing machine 10 for reuse. To do.
[0029]
  The surfactant contained in the washing water 21 may be any of an anionic surfactant, a cationic surfactant, and a nonionic surfactant, such as alkylbenzene sulfonate, abietic acid salt, A surfactant suitable for pollutants and soils is used in combination of one or more of fatty acid soap, polyoxyethylene alkyl ether, polyoxyethylene nonylphenyl ether and the like.
[0030]
  Then takeIntermediate technologyThe purification process of contaminated soil in will be described.
  First, the contaminated soil 20 containing harmful substances is put into the soil washing machine 10, and after separating the harmful substances from the contaminated soil 20 by mixing with the washing water 21 supplied from the downstream side, the purified soil containing moisture is removed. It introduces into the solid-liquid separator 11 divided up and down by the filter and removes the liquid component. If the harmful substance concentration does not fall to a predetermined value after one washing, the separated soil is returned to the soil washing machine by the return means 35 and washing is repeated. The purified soil 24 is returned to the environment by being returned to the excavation site or transported to a soil use place.
  On the other hand, the waste water 23 containing a surfactant that has taken in harmful substances through the soil washing machine 10 is guided to the solid-liquid separator 12 together with the liquid component 26 separated from the purified soil by the solid-liquid separator 11. Then, the purified soil 25 remaining in the liquid is precipitated and separated, and then sent to the freeze concentration step 3.
[0031]
  The hazardous substance-containing wastewater 27 discharged from the soil washing step 1 is temporarily stored in the storage tank 13a of the hazardous substance separation means 13 by the pump 18 with the valves a and c opened, and the required amount is stored. At this point, it is supplied to the freeze concentration means 13b. In the freeze concentration means 13b, pure water freezes on the refrigerant pipe of the refrigeration cycle 16a formed by the refrigeration / heat pump device 16, so that the waste water in which the surfactant containing the harmful substances is concentrated is frozen. It collects in the lower part of the concentration means 13b, and is discharged to the decomposition process as the hazardous substance concentrated waste water 30 by the pump 18 with the valves a and c closed and the valves b and e opened.
  After the drainage 30 is completely discharged, the valves b and e are closed, and the freeze concentrating means 13b forms a heat pump cycle 16b and functions as the ice separating and thawing means 13c. To obtain pure water. The pure water 29 obtained here is returned to the soil washing step and reused.
[0032]
  In this manner, by forming the refrigeration / heat pump cycle alternately by the refrigeration / heat pump device 16, pure water can be generated in one tank as shown in FIG. 2 described later, as shown in FIG. In addition, by installing two or more tanks and using the freeze concentration means 13b and the ice separation and thawing means 13c with a time difference, respectively, a large amount of waste water discharged from the soil washing step 1 can be treated efficiently. In addition, the heat energy on the evaporator side and the condenser side of the refrigeration / heat pump device 16 can be used effectively, and waste of power can be reduced.
[0033]
  In the present invention shown in FIG.FruitThe embodiment further includes a step of separating the surfactant and the harmful substance from the first embodiment described above.(Two-layer separation process)It comprises a soil washing step 1, a freeze concentration step 3, and a surfactant recycling step 2.
  In the second embodiment, the soil washing step 1 has the same configuration as that of the first embodiment.
  In the surfactant recycling process, when the surfactant used is ionic, the aqueous solution is cooled to below the Kraft point and separated, and when the surfactant used is nonionic, the aqueous solution is warmed above the cloud point. Need to be separated. Surfactant recycling step 2 which is a treatment step of harmful substance-containing waste water 27 discharged from soil washing step 1 is a surfactant separating means.(Two-layer separation means)14 and the washing water adjuster 15, the surfactant separating means 14 is maintained below the craft point or the cloud point of the used surfactant used, and the wash water adjuster 15 is the same craft point. Above or below the cloud point. As a result, the surfactant separating means 14 has a very low solubility of the surfactant, so that the surfactant is separated, and conversely, the washing water adjuster 15 dissolves the surfactant.
  And in the freeze concentration step 3 of the next step,Intermediate technologyIn the same manner as described above, pure water is obtained by concentrating and separating impurities in the waste water.
[0034]
  HeelsFruitTo explain the flow of the embodiment, in the soil washing process 1Intermediate technologySimilarly to the above, the waste water 27 discharged by the cleaning treatment of the contaminated soil is led to the surfactant separating means 14 by opening the valve a, where the surfactant is floated and separated, and in this case, the harmful substance has a specific gravity. Since it is larger than water, it settles in the lower part of the surfactant separating means 14. The separated surfactant 33 is guided to the washing water adjuster 15, and waste water containing harmful substances settled in the lower part is stored in the storage tank of the freeze concentration process 3 by the pump 18 with the valves d and c opened. 13a.
  The surfactant separating means 14 can also apply ultrasonic bubbles or fine bubbles with ultrasonic waves in the tank, and separate the surfactant and harmful substances by the fine bubbles or ultrasonic waves. In the case of the nonionic surfactant,TheIt is possible to make the temperature higher than the cloud point by the temperature rise effect by this ultrasonic wave.
  When a certain amount of the wastewater stored in the storage tank 13a is accumulated, it is transferred to the freeze concentration means 13b. In the freeze concentration means 13b, the pure water portion is frozen by the refrigeration cycle 16a formed by the refrigeration / heat pump device 16. Therefore, the harmful substances are concentrated and accumulated in the lower part, and the three-way valve 19, valves b and e are opened, The concentrated hazardous substance concentrated waste water 34 is supplied to facilities equipped with a hazardous substance decomposition treatment process or the like.
  At this time, the heat of condensation at the time of ice generation is supplied to the washing water regulator 15 and used to keep the temperature of the washing water regulator 15 at or above the Kraft point of the used surfactant. That is, by constructing the refrigeration / heat pump device 16 so as to form the refrigeration cycle 16a on the freeze concentration means 13b side and the heat pump cycle 16b ′ on the washing water adjuster 15 side, the soil washing device can be operated efficiently. It becomes possible to do.
[0035]
  After the hazardous substance concentration waste water 34 is completely discharged from the freeze concentration means 13b, the freeze concentration means 13b is formed with a heat pump cycle 16b and transferred to the ice separation and melting means 13c, so that the frozen ice is melted and purified. You can get water. The melted water 29 obtained here is supplied to the washing water regulator 15 by opening the three-way valve 19 in the direction of the washing water regulator 15. At this time, the surfactant separating means 14 is cooled by using the cold heat of the low-temperature molten water 29. Thereby, heat exchange can be efficiently performed by the surfactant separating means 14, and when the washing water regulator 15 into which the pure water 29 having an increased temperature is introduced is heated above the craft point of the used surfactant, Alternatively, less heat energy is required when cooling below the cloud point of the surfactant used.
  In addition, as a cooling method of the surfactant separating means 14, a refrigeration cycle formed by using the heat of evaporation at the time of ice melting in the ice separating and melting means 13 c in addition to using melted water or heat of condensation as described above. May be used.
[0036]
  In the washing water adjuster 15 to which the waste water containing the surfactant 33 separated by the surfactant separating means 14 and the pure water 29 generated in the freeze concentration step 3 are supplied, these are mixed and used for soil washing. A suitable washing water is prepared and supplied to the soil washing step 1 to reuse the washing water. As a result, wastewater discharged in large quantities can be reduced, and the surfactant and water can be circulated and used, leading to cost reduction.
  The water separated from the surfactant and harmful substances by the surfactant separating means 14 is preferably used in the cleaning water adjuster 15 together with the pure water 29.
[0037]
【The invention's effect】
  As described above, according to the present invention, it is possible to reliably remove harmful substances from a large amount of wastewater used for washing treatment of soil contaminated with ecosystem harmful substances, and to reduce the amount of wastewater. In addition, it is possible to provide a soil purification method and apparatus that are inexpensive in terms of cost by circulating and using water and a surfactant used for washing.
  Further, in the freeze concentration step used in the present invention, by effectively utilizing the refrigeration / heat pump cycle, a highly efficient apparatus can be realized, and waste of power can be saved.
[Brief description of the drawings]
FIG. 1 of the present inventionIntermediate technologyIt is a whole block diagram of the soil purification apparatus concerning.
FIG. 2The fruitIt is a whole block diagram of the soil purification apparatus concerning embodiment.
FIG. 3 is a schematic view showing an embodiment of a conventional contaminated soil purification apparatus.
[Explanation of symbols]
  1 soil washing process
  2 Surfactant recycling process
  3 Freeze concentration process
  10 Soil cleaner
  11, 12 Solid-liquid separator
  13 Hazardous substance separation means
  13a storage tank
  13b Freeze concentration means
  13c Ice separation and melting means
  15 Washing water regulator
  16 Refrigeration / heat pump equipment
  18 Pump
  19 Three-way valve
  20 Contaminated soil
  29 Melted water (pure water)
  34 Concentrated drainage of hazardous substances
  35 Returning means

Claims (6)

A washing process for washing soil contaminated with ecosystem harmful substances using an aqueous surfactant solution, and a liquid phase comprising an aqueous surfactant solution containing a solid phase consisting of purified soil and an emulsion containing the harmful substance. In the contaminated soil purification method having a solid-liquid separation step of solid-liquid separation into
The separated liquid phase is cooled below the Kraft point of the contained surfactant, and the solubilization or emulsification of harmful substances in the liquid phase is disrupted by raising the temperature above the cloud point of the contained surfactant or irradiating with ultrasonic waves. The upper layer and the lower layer are separated into two layers, and the lower layer containing the harmful substance is cooled and frozen to produce ice, thereby concentrating the harmful substance in the lower layer and removing the harmful substance from the ice. A method for purifying contaminated soil, wherein the generated water is melted and the generated water is recycled for the soil washing. Contaminated soil remediation method according to claim 1 Symbol mounting, characterized in that recycled use of surfactants harmful substances are removed by separating the two layers to the soil washing. The contaminated soil purification method according to any one of claims 1 to 2, wherein the solid-liquid separated solid phase is returned to the washing step, and the washing step and the solid-liquid separation step are repeated a plurality of times to perform multi-stage washing. . In a soil purification apparatus equipped with a soil cleaning means for cleaning soil contaminated with ecosystem harmful substances using an aqueous surfactant solution,
After washing the soil, cooling the wastewater containing the surfactant that has incorporated the harmful substances below the Kraft point of the surfactant, raising the temperature above the cloud point, or irradiating with ultrasonic waves, A two-layer separation means for breaking the emulsification of the liquid phase and separating the two layers into an upper layer and a lower layer;
Freeze concentration means for cooling and freezing the lower layer containing the separated harmful substances,
Ice separation and thawing means for separating and thawing the ice from which the harmful substances generated by freezing are removed;
A contaminated soil purification apparatus comprising: a washing water preparation device that prepares washing water to be supplied to a soil washing machine using the separated surfactant and water generated by melting ice. 5. The contaminated soil purification apparatus according to claim 4, wherein the freeze concentration means and the ice separation and thawing means are performed in the same tank by a heat release / heat absorption cycle of a heat pump. In the ice separation and melting means, ice is melted on the condenser side, and in the freeze concentration means, the waste water is frozen on the evaporator side, and below the Kraft point of the waste water containing the surfactant in the two-layer separation means. The ice melting water is used for cooling to the above, and the heat of condensation during the freeze concentration is increased to a cloud point or higher of the waste water containing the surfactant in the washing water preparation device and the surfactant in the two-layer separation means . The contaminated soil purification apparatus according to any one of claims 4 to 5 , wherein the contaminated soil purification apparatus is connected by a heat pump used for temperature rise.

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