KR102061828B1 - Soil remediation method for remediating soil contaminated with mercury and persistent organic pollutants - Google Patents

Abstract

The present invention relates to a method for purifying contaminated soil which is to purify contaminated soil contaminated by mercury and persistent organic pollutants. The method of the present invention comprises: a step of preparing contaminated soil; an evaporation step of heating the contaminated soil at 150 to 250°C under an oxygen-free atmosphere to evaporate moisture in the contaminated soil with superheated steam; a thermal desorption and decomposition step of thermally desorbing mercury and persistent organic pollutants in the contaminated soil by heating the contaminated soil evaporated with moisture in the presence of superheated steam and in an oxygen-free atmosphere, dechlorinating the thermally desorbed persistent organic pollutants, and breaking a benzene ring of the persistent organic pollutants by an OH radical; a combustion step of performing hydrolysis oxidation by combusting gas thermally desorbed and decomposed from the contaminated soil in the presence of hot air of 860 to 1,000°C and superheated steam; and a quenching step of injecting the combusted gas into water of 250°C or less to quench the same.

Description

SOIL REMEDIATION METHOD FOR REMEDIATING SOIL CONTAMINATED WITH MERCURY AND PERSISTENT ORGANIC POLLUTANTS}

The present invention relates to a method for purifying contaminated soil contaminated with mercury and persistent organic contaminants.

Soil pollution is aggravated by various pollutants caused by industrialization and urbanization. Various methods have been proposed to purify contaminated soil, but residual organic contaminants such as dioxins and furans and mercury in contaminated soils are not easy to remove.

Mercury has been designated as a designated waste if the mercury concentration is over 0.005 mg / L by the Domestic Waste Management Act after the death of about 50 people due to mercury pollution in Minamata City, Kyushu, Japan, but it is already contaminated with mercury. It is not related to the purification of the soil. In other words, there is a need to purify soil already contaminated with mercury.

Persistant organic pollutants (POPs) are harmful substances that do not degrade well in the natural environment but are accumulated in the flora and fauna through the food chain, causing immune system disturbances and central nervous system damage. As the risk of persistent organic pollutants has been identified, the Stockholm Convention to regulate 12 persistent organic pollutants, including polychlorinated Biphenyls (PCBs), dioxins and furans, was introduced in May 2001. Was adopted. Soils contaminated with persistent organic pollutants are difficult to process. For example, methods for purifying contaminated soil include radiolysis, base catalyst dechlorination, subcritical water treatment, thermal desorption, in-situ photolysis, solvent and liquefied gas extraction, mechanochemical and biological degradation. Although this method has been proposed, these methods require too much cost or have a disadvantage that the efficiency is too low due to the slow purification rate.

On the other hand, sewage sludge or dredged soils contain a large amount of residual organic pollutants or mercury. The high water content (more than about 80%) of sewage sludge or dredged soils causes the efficiency of the various contaminated soil purification methods described above to be reduced. do.

Therefore, a new way to solve this problem is needed.

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Cited Invention 1: Japanese Unexamined Patent Publication No. 2010-036128 Cited Invention 2: Japanese Unexamined Patent Application Publication No. 2007-296410 Cited Invention 3: Patent Publication No. 10-0976586 Cited Invention 4: Registered Patent Publication 10-0919924

One object of the present invention is to solve the above problems and to purify contaminated soil that can efficiently purify mercury and residual organic pollutants even in soil contaminated with persistent organic pollutants, especially sewage sludge or dredged soil having high moisture content. To provide a way.

On the other hand, other unspecified objects of the present invention will be further considered within the range that can be easily inferred from the following detailed description and effects.

In the contaminated soil purification method according to an embodiment of the present invention for achieving the above object, in the contaminated soil purification method for purifying the contaminated soil by mercury and persistent organic pollutants, preparing a contaminated soil; An evaporation step of heating the contaminated soil to a temperature of 150 to 250 ° C. under an oxygen-free atmosphere to evaporate water in the contaminated soil with superheated steam; Moisture evaporated contaminated soil is heated to a temperature of 360 to 600 ℃ under the presence of superheated steam and an oxygen-free atmosphere to thermally desorb mercury and residual organic contaminants in the contaminated soil, dechlorinate the thermally desorbed residual organic pollutants and by OH radicals. Thermal desorption and decomposition step of breaking the benzene ring of persistent organic pollutants; A combustion step of hydrolyzing and decomposing the gas desorbed and decomposed from the contaminated soil in the presence of hot air of 860 to 1000 ° C. and superheated steam; And a quenching step of quenching the injected gas into water at 250 ° C. or less.

In one embodiment, after performing the quenching step, flowing the gas cooled by the cyclone cyclone, separating the coarse particles contained in the introduced gas; And adsorbing unremoved mercury and residual organic pollutants to the activated carbon by spraying powdered activated carbon on a gas from which coarse particles discharged from the dust collection cyclone have been removed. And injecting and filtering the gas injected with the powder activated carbon into a bag filter.

In one embodiment, the step of preparing the contaminated soil may be carried out by adding and homogenizing zero iron to the contaminated soil.

In one embodiment, the step of recovering the non-ferrous iron using a magnetic separator from the soil from which mercury and residual organic pollutants are removed in the thermal desorption and decomposition step.

In one embodiment, the step of preparing the contaminated soil may be performed including spraying water on the contaminated soil.

In one embodiment, the residual organic pollutants are toluene, diisocyanoic acid isophorone, meta-cresol, benzyl chloride, phosphorus oxychloride, toluene-2,4-diisocyanate, para-nitrotoluene, phenol, benzene, allyl Chloride, acrylonitrile, vinyl chloride, carbon disulfide, nitrobenzene, 1,4-dioxin, 2,3,7,8-tetrachlorodibenzo [b, e] [1,4] -dioxin, 1,2,3,7 , 8-Pentachlorodibenzo-P-dioxin, 1,2,3,4,7,8-Hexachlorodibenzo-P-dioxin, 1,2,3,6,7,8-Hexachlorodibenzo-P-dioxin, 1,2,3 , 4,6,7,8-Heptachlorodibenzo-P-dioxin, Octachlorodibenzodioxin, 2,3,7,8-Tetrachlorodibenzofuran, 1,2,3,7,8-Pentachlorodibenzofuran, 1,2,4,7,8-Hexachlorodibenzofuran , 1,2,3,6,7,8-Hexachlorodibenzofuran, 1,2,3,4,6,7,8-Hexachlorodibenzofuran, and Octachlorodibenzofuran.

In one embodiment, the thermal desorption and decomposition step may be performed by heating the contaminated soil to 537 to 600 ℃.

In one embodiment, the quenching step may neutralize the acidic material contained in the burned gas by dissolving Ca (OH) ₂ in water.

In the contaminated soil purification method according to another embodiment of the present invention for achieving the above object, in the contaminated soil purification method for purifying the contaminated soil contaminated by mercury and persistent organic pollutants, preparing a contaminated soil; Thermal desorption and decomposition step of heating the contaminated soil to a temperature of 360 to 600 ℃ under an oxygen-free atmosphere; A combustion step of hydrolyzing and decomposing the gas desorbed and decomposed from the contaminated soil in the presence of hot air of 860 to 1000 ° C. and superheated steam; And a quenching step of injecting the burned gas into water of 250 ° C. or lower, and quenching the water, wherein the thermal desorption and decomposition step evaporate water in the contaminated soil with superheated steam, and mercury and residuals in the contaminated soil in which the water is evaporated. Thermal desorption of organic pollutants, dechlorination of the thermally desorbed residual organic pollutants, and the benzene ring of the residual organic pollutants by the OH radical is carried out.

Contaminated soil purification method according to an embodiment of the present invention generates the moisture contained in the contaminated soil as a superheated steam, thermal desorption of mercury and residual organic pollutants from the contaminated soil, and further the superheated steam of the residual organic pollutants By decomposing using it, the soil contaminated with mercury and persistent organic pollution can be cleaned efficiently in a short time.

In particular, the contaminated soil purification method according to an embodiment of the present invention has the advantage that it can be discharged in a harmless state by purification once again to the discharged soil, effluent water, sediment and air.

On the other hand, even if the effects are not explicitly mentioned here, it is added that the effects described in the following specification and the provisional effects expected by the technical features of the present invention are treated as described in the specification of the present invention.

1 is a schematic flowchart of a soil cleaning method according to an embodiment of the present invention.
Figure 2 is a schematic diagram of a soil purification apparatus according to another embodiment of the present invention.
※ The accompanying drawings show that they are illustrated as a reference for understanding the technical idea of the present invention, by which the scope of the present invention is not limited.

In the following description of the present invention, when it is determined that the subject matter of the present invention may be unnecessarily obscured by the person skilled in the art with respect to the related well-known functions, the detailed description will be omitted.

Pollutant soil purification method

1 is a schematic flowchart of a soil cleaning method according to an embodiment of the present invention.

In detail, the method of purifying contaminated soil (M100) according to an embodiment of the present invention includes preparing a contaminated soil (S10), an evaporating step of evaporating moisture in the contaminated soil with superheated steam (S20), mercury and residual pollution. A thermal desorption and decomposition step (S30) for thermally desorbing and decomposing materials from contaminated soil, a combustion step (S40) for hydrolytic decomposition by burning the thermal desorption and decomposed gas, and a quenching step (S50) for quenching the burned gas.

First, a step (S10) of preparing a contaminated soil is performed. The soil contaminated by the present invention refers to soil contaminated with mercury and persistent organic pollutants, for example, soils of chemical-related production facilities, soils of refinery-related facilities, waste landfill soil, sewage sludge, and dredged soil. it means. In particular, the contaminated soil purification method according to an embodiment of the present invention can effectively perform soil purification even for high sewage sludge and dredged soil.

Pollutants to be cleaned are shown in Table 1 below.

In particular, in the step (S10) of preparing the contaminated soil, a process of removing the foreign matter having a size of 20 mm or more included in the contaminated soil and grinding the contaminated soil for homogenization is performed.

Furthermore, water may be sprayed on the contaminated soil during the step S10 of preparing the contaminated soil. This spraying water is to reduce the dust generated in the grinding process, and to cause a sufficient amount of superheated steam in the subsequent evaporation step (S20).

In addition, the step (S10) of preparing the contaminated soil may further include a step of adding and stirring the ferrous iron to the contaminated soil. Zero iron added to contaminated soils leads to desalination of persistent organic pollutants.

For the contaminated soil, an evaporation step (S20) of evaporating water in the contaminated soil with superheated steam is performed.

Evaporation step (S20) may be performed in the evaporator or rotary kiln of the soil purification apparatus to be described later. Evaporation step (S20) may be carried out by heating the contaminated soil for 2 to 30 minutes at a temperature of 150 to 250 ℃ under an oxygen-free atmosphere. The superheated steam generated here is used in the thermal desorption and decomposition step (S30).

The contaminated soil purification method (M100) according to an embodiment of the present invention uses superheated steam, and superheated steam means steam having a temperature above the saturation temperature at atmospheric pressure by heating saturated steam, and increasing the temperature to 1200 ° C. It is possible. Superheated steam is superior in heat transfer compared to air, and the particle size of superheated steam is smaller than the average particle size of air constituents, so the contact area with the object is large, and there is no risk of oxidizing the object, explosion or fire. .

Next, a thermal desorption and decomposition step (S30) of thermally desorbing and decomposing the contaminated soil in which moisture is evaporated is heated to a temperature of 360 to 600 ° C. under the presence of superheated steam and an oxygen-free atmosphere.

Thermal desorption and decomposition step (S30) is to maintain the temperature to be carried out at 360 ℃ or more, the mercury and residual organic pollutants phase change to a gas to thermal desorption from contaminated soil. Preferably, the temperature at which the thermal desorption and decomposition step (S30) is performed may be heated to 537 ° C. or more, so that all of the pollutants described in Table 1 are thermally desorbed from the contaminated soil.

In particular, the thermal desorption and decomposition step (S30) is to form a reducing atmosphere by maintaining in an oxygen-free atmosphere of high temperature, dechlorination of the residual organic pollutants thermally desorption using the reducing atmosphere. Furthermore, the superheated steam generates OH radicals and hydrogen at temperatures above 360 ° C. As a result, the benzene ring of the thermally desorbed residual organic pollutants is broken.

On the other hand, the temperature of the above-mentioned evaporation step (S20) and the thermal desorption and decomposition step (S30) does not include 250 to 350 ℃, de novo synthesis in which dioxin and the like is regenerated at a temperature of 250 to 350 ℃ Can be minimized or prevented. In particular, a lot of energy is consumed in the phase change of water, by dividing the evaporation step (S20) and the thermal desorption and decomposition step (S30) can minimize the time out of the temperature at which de novo synthesis proceeds.

If necessary, additional superheated steam may be supplied from a separate superheated steam generator to perform an evaporation step (S20) and a thermal desorption and decomposition step (S30).

After performing the thermal desorption and decomposition step (S30), mercury and residual organic pollutants are thermally desorbed and decomposed to generate gas and soil from which mercury and residual organic pollutants are removed, and the soil is discharged to the outside. At this time, by re-measuring the soil pollution level, the soil in which contaminants exist above a predetermined standard may be re-run from the step (S10) of preparing the contaminated soil.

The combustion step S40 is performed on the gas desorption and decomposition from the contaminated soil. Combustion step (S40) is hydrodecomposed by burning the desorption and decomposition gas for 5 seconds to 5 minutes in the presence of hot air and superheated steam of 860 to 1000 ℃. After performing the combustion step (S40), a combustion gas including H ₂ , CO, CO ₂ , HCl is generated. In other words, the residual organic pollutants desalted in the combustion step S40 and the benzene ring is broken are decomposed by 99% or more.

The quenched gas (S50) for quenching the injected gas generated after the combustion step (S40) is injected into water is performed. In order to quench the burned gas, the water of the quenching step S50 has a temperature of 250 ° C. or less. In addition, since the burned gas contains an acidic substance such as HCl, the acidic substance is removed from the water in the quenching step (S50). To this end, Ca (OH) ₂ is dissolved in the water used in the quenching step (S50), and reacts with HCl of the combustion gas to produce CaCl ₂ as a precipitate. On the other hand, the temperature of the water is 250 ℃ or less to minimize or prevent de novo synthesis (dioxin synthesis) is regenerated, for this purpose, the temperature of the water may be preferably 200 ℃ or less. In the quenching step (S50), mercury is liquefied and separated, and the mercury not separated is adsorbed onto activated carbon.

The effluent and sediment are separated from the discharge tank so that the sediment is discharged to the bottom of the discharge tank and the supernatant is discharged to the discharge pipe.

On the other hand, the gas cooled through the quenching step (S50) includes mercury and residual organic contaminants, fly ash and the like not completely removed.

Therefore, in the contaminated soil purification method (M100) according to an embodiment of the present invention, the gas cooled by the dust collection cyclone is introduced to separate the coarse particles contained in the introduced gas, and the coarse particles discharged from the dust collection cyclone. The method may further include adsorbing unremoved mercury and residual organic contaminants to the activated carbon by spraying the powdered activated carbon on the removed gas, and filtering and injecting the gas injected with the powdered activated carbon into the bag filter.

In the dust collection cyclone, the coarse particles collide with the wall surface of the dust collection cycle by centrifugal force, and the cooling gas from which the coarse particles are separated is introduced into the bag filter.

An activated carbon injector is installed in the connection pipe connecting the bag filter and the dust collection cyclone to inject 200 to 350 mesh of powdered activated carbon toward the cooling gas. Mercury and residual organic pollutants are adsorbed to the injected powdered activated carbon, coarse particles in the powdered activated carbon are collected at the forward part of the bag filter, and fine particles are filtered out of the filter. Accordingly, harmless air with 99.99% or more of mercury and residual organic pollutants removed is discharged to the outside.

On the other hand, solid discharges, such as sediment discharged from the discharge tank, dust collected in the cyclone and bag filter can be further processed in the microbial reactor. That is, in the microbial reaction tank, the ferric iron and the solid discharge are mixed to desalting residual organic pollutants, and the benzene ring can be decomposed into microbial diallocoles in the anaerobic state. As such, the method using the microorganisms takes a long time, but the solid discharge can shorten the time required for purification in the state where the majority of the residual organic pollutants have already been removed.

In addition, the discharged soil may perform a separation process using a magnetic separator containing heavy metals, heavy metal removal process using an elution tank and sedimentation tank, neutralization tank and flocculation tank can be carried out.

Soil Purification System

2 is a schematic configuration diagram of a soil purification apparatus 100 according to another embodiment of the present invention capable of performing the above-described contaminated soil purification method. Referring to FIG. 2, the soil purification apparatus 100 according to another embodiment of the present invention includes an evaporator 20, a reactor 30, a combustor 40, and a quench cooler 50.

The contaminated soil is introduced into the evaporator 20. The evaporator 20 includes a feed screw 25 for stirring and conveying the introduced contaminated soil. That is, as the feed screw 25 rotates, the blade of the feed screw 25 moves the contaminated soil from one side to the other side. Evaporator 20 is provided with a heating means to change the moisture contained in the contaminated soil for 2 to 30 minutes at a temperature of 150 to 250 ℃ to superheated steam. The superheated steam generated in the evaporator 20 is transferred to the reactor 30 and used for thermal desorption and decomposition of residual organic pollutants. On the other hand, the inside of the evaporator 20 maintains an oxygen-free atmosphere. In order to maintain the inside of the evaporator 20 in an oxygen free atmosphere, an inert gas may be introduced into the evaporator 20.

Soil purification apparatus 100 according to an embodiment of the present invention uses superheated steam, superheated steam means a steam having a temperature above the saturation temperature at atmospheric pressure by heating saturated steam, it is possible to increase the temperature to 1200 ℃ Do. Superheated steam is superior in heat transfer compared to air, and the particle size of superheated steam is smaller than the average particle size of air constituents, so that the contact area with the object is large, and there is no risk of oxidizing the object, explosion or fire. .

Meanwhile, the contaminated soil introduced into the evaporator 20 may be homogenized in the pretreatment 10. That is, in the pretreatment 10, a process of removing the foreign matter having a size of 20 mm or more included in the contaminated soil and grinding the contaminated soil for homogenization is performed. In particular, the pretreatment unit 10 of the soil purification apparatus 100 of an embodiment of the present invention may further include a sprinkler 11 for spraying water to the homogenized contaminated soil. The sprinkler 11 serves to lower the dust generated during the homogenization of the soil and to increase the moisture in the contaminated soil so that a sufficient amount of superheated steam is generated in the evaporator 20. In addition, the pretreatment 10 may induce desalination of residual organic pollutants by adding and stirring zero iron to contaminated soil.

Contaminated soil and superheated steam are introduced into the reactor 30 from the evaporator 20. The reactor 30, like the evaporator 20, also includes a feed screw 35 for stirring and conveying contaminated soil. On the other hand, the reactor 30 also has a heating means to heat the interior for 2 to 30 minutes at 360 to 600 ℃.

The temperature of the reactor 30 is heated to 360 ° C. or higher, and the mercury and residual organic pollutants are phase-changed with gas and thermally desorbed from the contaminated soil. Preferably, the temperature of the reactor 30 may be heated to 537 ° C. or higher, so that all of the pollutants listed in Table 1 may be thermally desorbed from the contaminated soil.

In particular, the soil purification apparatus 100 according to an embodiment of the present invention may be formed in a reducing atmosphere by maintaining the inside of the reactor 30 in a high temperature anoxic atmosphere, thereby dechlorination of the residual organic pollutants thermally desorbed. . Furthermore, the superheated steam generates OH radicals and hydrogen at temperatures above 360 ° C. As a result, the benzene ring of the thermally desorbed residual organic pollutants is broken.

In order to improve the reaction efficiency, the reactor 30 may have a plurality of multistage reaction structures like the first reactor 31 and the second reactor 32. At this time, the first reactor 31 has a lower temperature than the second reactor 32, specifically, the first reactor 31 is a temperature of 360 to 560 ℃, the second reactor 32 is 400 to 600 ℃ It can be heated to a temperature of.

On the other hand, the soil purification apparatus 100 according to an embodiment of the present invention by separately configuring the evaporator 20 and the reactor 30, de novo synthesis in which dioxin and the like is regenerated at a temperature of 250 to 350 ℃ ) Can be minimized or prevented.

If necessary, the superheated steam generator 45 may be provided to inject the superheated steam into the evaporator 20 or the reactor 30.

The contaminated soil in the reactor 30 is thermally desorbed and decomposed and mercury and residual organic pollutants are discharged to the combustor 40 as decomposition gas. Soil from which mercury and residual organic pollutants are removed is discharged to the outside and stored in the soil storage tank (95). When the contaminant detection sensor is installed in the soil storage tank 95, in the case of soil in which the contaminants exist above a predetermined standard, the soil is transferred back to the preprocessor 10.

On the other hand, in the pretreatment 10 when the addition of stirring iron to the contaminated soil and stirred, it is provided with a magnetic separator 91 can be recovered and reused iron.

As described above, the combustor 40 is introduced into the exhaust gas containing mercury and residual organic pollutants thermally desorbed from the contaminated soil. In addition, the superheated steam is introduced into the combustor 40 from the superheated steam generator 45, and hot air is introduced from the hot air blower 43. The temperature in the combustor 40 is increased to 860 to 1000 ° C. by the hot air blower 43, and the exhaust gas is hydrolyzed by burning for 5 seconds to 5 minutes in the combustor 40 to be H ₂ , CO, CO ₂ , HCl. Produces a combustion gas comprising a. That is, the residual organic pollutants desalted in the combustor 40 and the benzene ring is broken are decomposed by 99% or more.

Combustion gas flows into the quench cooler 50. The quench cooler 50 contains water of 250 ° C. or lower, so that the introduced combustion gas is quenched. In addition, since the combustion gas contains an acidic substance such as HCl, the acidic substance is removed from the water of the quench cooler (50). To this end, Ca (OH) ₂ is dissolved in the water of the quench cooler 50, and reacts with HCl of the combustion gas to produce CaCl ₂ as a precipitate. The temperature of the water in the quench cooler 50 is 250 ° C. or less to minimize or prevent de novo synthesis in which dioxin or the like is regenerated. For this purpose, the temperature of water may be preferably 200 ° C. or less. have. In the quench cooler 50, mercury is liquefied and separated, and mercury not liquefied is adsorbed and removed by powdered activated carbon, which will be described later.

In the quench cooler 50, the incoming gas flows into the received water, and undissolved combustion gas flows back to the upper portion of the quench cooler 50. In order to increase the efficiency of the quench cooler 50, the quench cooler 50 may be configured in multiple stages as shown in FIG.

The discharge water and the sediment are separated from the discharge tank 92, the precipitate is discharged to the lower portion of the discharge tank 92, the supernatant water is discharged to the discharge pipe.

On the other hand, the cooling gas cooled in the quench cooler 50 includes mercury, residual organic pollutants, fly ash and the like that are not completely removed.

Therefore, the soil purification apparatus 100 according to an embodiment of the present invention does not discharge the cooling gas directly to the outside, and the remaining mercury, residual organic pollutants in the dust collection cyclone 60 and the bag filter 70, and Fly ash and the like can be removed.

First, the cold gas is introduced into the cyclone cyclone (60).

The cyclone cyclone 60 is coupled to one end of the cylindrical housing 61 and the housing 61, which forms an external swirl flow while the cooling gas rotates along the surface thereof, and gradually decreases in diameter to form an inner swirl flow that rises from the center portion. The cyclone part 62 is comprised. Coarse particles, for example, fly ash, collide with the wall of the cylindrical housing 61 or the cyclone portion 62 by the external swirl flow and fall to the dust collecting portion 63, and the other cooling gas flows to the air outlet 64. Discharged.

Cooling gas from which the coarse particles have been removed flows into the bag filter 70. Before flowing into the bag filter 70, an activated carbon injector 80 is installed in the connection pipe between the dust collecting cyclone 60 and the bag filter 70. Activated carbon injector 80 is pulverized activated carbon in the activated carbon mill 82 to 200 ~ 350 mesh to make powdered activated carbon, the powdered activated carbon is injected from the injector 83 to the injection tank 81. The sprayed activated carbon adsorbs mercury and residual organic contaminants. The fine particles of the activated carbon adsorbed with the mercury and the residual organic contaminants are filtered by the filter 72 of the bag filter 70, and the coarse particles fall to the dust collector 73 along the bag filter housing 71.

The bag filter 70 discharges harmless air from which mercury and residual organic contaminants are removed 99.99% or more to the outside.

On the other hand, solid discharge, such as sediment discharged from the discharge tank 92, particles collected in the cyclone cyclone 60 and the bag filter 70 may be further processed in the microbial reactor. In other words, in the microbial reactor, the ferrous iron and the solid discharge are mixed to desalination of residual organic pollutants, and the benzene ring is microbial diallocoles, Pseudomonas sp. DJ-12, Pseudomonas sp. P20, Achromabactor xylosoxidans KF701, Pseudomonas sp. It can be decomposed using at least one of S-47. As such, the method using the microorganisms takes a long time, but the solid discharge can shorten the time required for purification in the state where the majority of the residual organic pollutants have already been removed.

In addition, the soil discharged from the reactor 30 may be carried out using a magnetic separator containing a heavy metal, heavy metal removal process using the elution tank and the settling tank, the neutralization tank and the coagulation tank may be carried out.

On the other hand, the scope of protection of the invention is not limited to the description and expression of the embodiments explicitly described above. In addition, it is again noted that the scope of protection of the present invention may not be limited due to obvious changes or substitutions in the technical field to which the present invention pertains.

Claims (8)

In the contaminated soil purification method to purify contaminated soil contaminated by mercury and persistent organic pollutants,
Adding contaminant iron and homogenizing in a pretreatment to prepare contaminated soil;
An evaporation step of heating the contaminated soil to a temperature of 150 to 250 ° C. under an oxygen-free atmosphere to evaporate water in the contaminated soil with superheated steam;
Moisture evaporated contaminated soil is heated to a temperature of 360 to 600 ℃ under the presence of superheated steam and an oxygen-free atmosphere to thermally desorb mercury and residual organic contaminants in the contaminated soil, dechlorinate the thermally desorbed residual organic pollutants and by OH radicals. Thermal desorption and decomposition step of breaking the benzene ring of persistent organic pollutants;
A combustion step of hydrolyzing and decomposing gas desorbed and decomposed from the contaminated soil in the presence of hot air of 860 to 1000 ° C. and superheated steam;
A quenching step of quenching the injected gas into water at 250 ° C. or lower;
A discharge step of discharging the water used for quenching into discharge water and sediment;
Separating the coarse particles contained in the introduced gas by introducing the quenched gas into the cyclone cyclone; And
Activated carbon grinder is pulverized into 200 to 350 mesh to prepare powdered activated carbon, and powdered activated carbon is sprayed onto the gas from which coarse particles discharged from the dust collection cyclone are removed to adsorb unremoved mercury and residual organic pollutants to the activated carbon. Making a step; And
Injecting the powder activated carbon is injected into the bag filter and filtered;
And removing zero iron from the soil discharged by removing the mercury and residual organic pollutants through the thermal desorption and decomposition step using a magnetic separator.
The method of claim 1,
And treating the solids discharged from the discharge step and the solid discharge including the dust collected by the cyclone and the bag filter in a microbial reactor for decomposing the residual organic contaminants using microorganisms. To clean the soil.
delete delete The method of claim 1,
The preparing of the contaminated soil may include spraying water on the contaminated soil.
The method of claim 1,
The residual organic pollutants include toluene, isocorate diisocyanate, meta-cresol, benzyl chloride, phosphorus oxychloride, toluene-2,4-diisocyanate, para-nitrotoluene, phenol, benzene, allyl chloride, acrylonitrile, Vinyl chloride, carbon disulfide, nitrobenzene, 1,4-dioxin, 2,3,7,8-tetrachlorodibenzo [b, e] [1,4] -dioxin, 1,2,3,7,8-Pentachlorodibenzo-P -dioxin, 1,2,3,4,7,8-Hexachlorodibenzo-P-dioxin, 1,2,3,6,7,8-Hexachlorodibenzo-P-dioxin, 1,2,3,4,6,7 , 8-Heptachlorodibenzo-P-dioxin, Octachlorodibenzodioxin, 2,3,7,8-Tetrachlorodibenzofuran, 1,2,3,7,8-Pentachlorodibenzofuran, 1,2,4,7,8-Hexachlorodibenzofuran, 1,2,3 At least one selected from the group consisting of 6,7,8-Hexachlorodibenzofuran, 1,2,3,4,6,7,8-Hexachlorodibenzofuran, and Octachlorodibenzofuran.
The method of claim 1,
The thermal desorption and decomposition step is a contaminated soil purification method performed by heating the contaminated soil to 537 to 600 ℃.
The method of claim 1,
The quenching step is a contaminated soil purification method by dissolving Ca (OH) ₂ in water to neutralize the acidic substances contained in the burned gas.

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