JP2005279397A - Cleaning method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polluted soil cleaning method having a process for excavating polluted soil and mixing the same with a nutrient by a soil mixer to return the resulting mixture to the excavated position and intermittently supplying air at the original position, and stably propagating and activating anaerobic microorganisms and aerobic microorganisms living in soil not only to optimize cleaning treatment or control but also simplify each cleaning treatment equipment or facilities. <P>SOLUTION: The nutrient salt 5 based on a 6C or higher carbon straight chain saturated monocarboxylic acid is mixed with the polluted soil obtained by excavating a polluted region by a building machine 2 and air is intermittently supplied to the obtained mixture by a blower 5 to propagate and activate of aerobic or anaerobic microorganisms living in soil. By this method, the polluted soil 1 polluted with a volatile organic compound or an oil component can be subjected to a decomposition treatment and cleaned soil is returned to the original place or can be recycled. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  This invention activates anaerobic microorganisms and aerobic microorganisms using a bioremediation method, promotes purification of soil contaminated with organochlorine compounds and waste oil, and purifies contaminated areas in situ in a short time It is about technology.

  Conventionally, soil and pollution purification equipment and methods include vacuum extraction, pumping aeration, lime, iron powder, soil excavation and replacement, soil moisture cleaning, insolubilization, gas / liquid mixing well Various methods are used for purification, air sparging, bioremediation, and purification, and methods that can purify soil and groundwater contamination in a short period of time are the iron powder method and the bioremediation method.

In-situ biological treatment is possible, fatty acids having 10 or more carbon atoms, alcohols having 12 or more carbon atoms, esters of linear saturated fatty acids having 14 or more carbon atoms and monohydric alcohols, 14 carbon atoms A method of reducing nitrate nitrogen and volatile organic compounds in soil and groundwater by embedding the above-mentioned linear saturated fatty acid and polyhydric alcohol ester, fatty acid and glycerin ester having 16 or more carbon atoms in the soil Is known (see, for example, Patent Document 1).
A denitrification accelerator mainly composed of a straight-chain saturated monocarboxylic acid having 6 or more carbon atoms and formed into particles having a particle diameter of 100 mm or less, and mainly used for wastewater treatment, and water using this denitrification accelerator A processing method is known (see, for example, Patent Document 2).
JP 2002-370085 A (pages 4 to 14, FIGS. 1 to 3) JP 2000-334492 A (pages 3 to 9, FIGS. 1 to 4)

However, in such conventional soil and groundwater contamination purification equipment and methods, the iron powder method is a method of excavating the soil and injecting zeroized iron powder, and the soil is purified in a short time by chemical reaction. However, at present, the method of excavating the contaminated area is mainly used, and therefore, it is not possible to purify the entire contaminated area within the optimum period, and the construction cost is high. The bioremediation method is unstable because it depends on the environment and may not be purified within the optimum period.
Furthermore, with regard to the purification treatment agent, the conventional nutrient salts have high solubility in water (for example, polylactic acid ester), and in this case, the supplied nutrient salt (consumption amount) is rapidly eluted into the ground water (many), and therefore frequently. Additional (continuous) administration of nutrients was required. In addition, fatty acids having 10 or more carbon atoms are slow to elute into moisture in the soil, and the optimal amount of elution in the contaminated soil cannot be managed.
Accordingly, there has been a strong demand for a purifying treatment agent having an optimum solubility, stable treatment, and easy maintenance. In addition, in the bioremediation method that does not excavate contaminated soil, it is difficult to judge the state of purification of underground contaminated soil, and even if excavated contaminated soil is treated as waste, specially controlled industrial disposal There were many problems, such as a huge amount of money and energy.

  The present invention solves such a conventional problem, excavating contaminated soil, mixing nutrient salt and contaminated soil with a soil mixer and returning to the excavated position, and intermittently supplying air at the original position. It is a construction method to clean up, anaerobic microorganisms and aerobic microorganisms that inhabit the soil are stably propagated and activated over a long period of time (optimum), and the purification treatment and management are optimized. The purpose is to simplify the facility and provide a method for the purification of contaminated soil. In other words, focusing on the bioremediation method with relatively low construction costs, the treatment of anaerobic and aerobic microorganisms with specific nutrients promotes the purification of soil contamination, and the straight chain has 6 or more carbon atoms. Nutrient salts based on saturated monocarboxylic acids (caproic acid, pentanecarboxylic acid, butylacetic acid, enanthic acid, enanthic acid, hexanecarboxylic acid, pentylacetic acid, caprylic acid, heptanecarboxylic acid, hexylacetic acid, pelargonic acid, octanecarboxylic acid The present invention provides a purification method using a construction method capable of stably purifying all contaminated soil within an optimum period by mixing acid, heptyl acetic acid, etc.) with soil excavated in a contaminated area.

  In order to achieve the above object, the method for purifying contaminated soil of the present invention excavates the contaminated soil region using a heavy construction machine, and extracts the excavated contaminated soil and a linear saturated monocarboxylic acid having 6 or more carbon atoms. The nutrient salt as a main component is mixed with a soil mixer, a water shielding sheet is laid on the area excavated by the construction heavy machinery, and the gradient of the water shielding sheet is maintained at 2 to 4 degrees, and then the gradient The water collecting pipe is provided below, the gravel is spread on the water shielding sheet, the air supply pipe is disposed thereon, and the contaminated soil and the nutrient salt are mixed by the soil mixer. A method for purifying contaminated soil, in which soil is introduced, and by blowing an air blower connected to the air supply pipe to the mixed soil by intermittent operation, the indwelling anaerobic microorganisms and aerobic microorganisms are proliferated and activated. And soak in the waterproof sheet The leachate which, pumped by pumping the pump via the water collection pipe, in which using a method for decomposing a volatile organic compound and oil in the contaminated soil by spraying the mixed soil.

  The present inventors excavated a contaminated area using construction heavy equipment and grasped the situation, and then laid a water shielding sheet on the part that was excavated and became a non-contaminated area so as to maintain a horizontal gradient of 2 to 4 degrees, Install one or more water collection pipes on it, spread gravel so as to cover the water collection pipes, install one or more air supply pipes on it, and install the air supply pipes. Covered with crushed stone so as to cover, backfill the mixed soil in which the contaminated soil and nutrients mainly composed of linear saturated monocarboxylic acid having 6 or more carbon atoms are mixed almost uniformly with a soil mixer, Volatility contained in contaminated soil by promoting the growth and activity of anaerobic microorganisms and aerobic microorganisms indigenous to contaminated soil by intermittently controlling the air supply to the air supply pipe for mixed soil Completes organic compounds and oils in a stable and biological manner It can be decomposed (purified by reductive dechlorination reaction, detoxified), and the entire contaminated soil can be purified in the optimal construction period. The leachate leached out from the contaminated soil is passed through the water collecting pipe. It is stored in storage means (for example, storage tanks and storage containers), and by appropriately sprinkling the mixed soil, there is no risk of causing secondary pollution, no wastewater treatment facility is required, and there is no need to dispose as specially managed industrial waste It can also clean up leachate contamination.

  According to the present invention, after grasping the situation of the contaminated area by excavation or the like, the water shielding sheet is laid on the portion that has been excavated and becomes the non-contaminated area so as to maintain a horizontal gradient of 2 to 4 degrees, and collected thereon. Install one or more water pipes, cover the water collection pipes with flat gravel, install one or more air supply pipes on it, and excavate the contaminated area on it. The mixed soil obtained by mixing the contaminated soil and nutrients mainly composed of straight-chain saturated monocarboxylic acid having 6 or more carbon atoms with a soil mixer is piled up and sent to the air supply pipe. Volatile organic compounds and waste oil contained in the mixed soil are biologically treated by anaerobic and aerobic treatment that promotes the growth and activity of aerobic microorganisms that are indigenous to the contaminated soil in the method of intermittently supplying generated air Stable decomposition (reductive dechlorination) Purification by response, detoxification) can be treated, the overall soil mixture at the optimum engineering period can the purifying, can also be purified leachate leaching from soil mixture.

  Moreover, the construction method of purifying the mixed soil of the present invention by anaerobic / aerobic treatment can effectively purify the soil in a wide range of soil contamination.

  Furthermore, since the entire mixed soil can be biodegradably and completely decomposed (purified by reductive dechlorination reaction, detoxified) in the optimal construction period, the purified soil can be used as it is. This eliminates the need to dispose of specially managed industrial waste, saving enormous costs and energy.

  According to the first aspect of the present invention, a contaminated soil region is excavated using a heavy construction machine, and a specific nutrient salt (straight chain having 6 or more carbon atoms) according to the local pollution situation and various surrounding situations. (Saturated monocarboxylic acid as a main component), and excavated contaminated soil and a linear saturated monocarboxylic acid with six or more carbon atoms as a main component are mixed with a soil mixer. A horizontal slope in the non-contaminated area excavated by heavy construction equipment is set to 2 to 4 degrees (preferably 3 degrees), a water shielding sheet is laid, and one or more water collecting pipes are arranged below the slope. Lay gravel almost horizontally to cover the water collection pipe, place one or more air supply pipes on it, lay crushed stone almost horizontally to cover the air supply pipe, In addition, soil mixed with a soil mixer and straight-chain saturated monocarbo having 6 or more carbon atoms Anaerobic microorganisms indwelling in contaminated soil by backfilling the mixed soil in which nutrient salts mainly composed of acids are mixed almost uniformly and intermittently controlling the air supply to the mixed soil By promoting the growth and activity of aerobic microorganisms, volatile organic compounds and oils contained in contaminated soil can be biodegraded and completely decomposed (purification and detoxification by reductive dechlorination reaction). . In general, when the soil surface layer is 50 cm or less, anaerobic microorganisms are often active in an environment where the anaerobic microorganisms are active, but some anaerobic microorganisms decompose to harmless low molecular weight substances, but most anaerobic microorganisms. Microorganisms cannot be decomposed until the molecular weight of carbon dioxide and water is reduced, and remain cisDCE in the soil. cisDCE is decomposed into ethylene by an aerobic microorganism, and further decomposed into carbon dioxide and water.

  Therefore, the leachate leached from the mixed soil is stored in the storage means (for example, storage tank, storage container) via the water collection pipe, sprayed to the mixed soil as appropriate, and a part is taken out and analyzed over time by gas chromatography When the concentration of cisDCE increases and stabilizes with the concentration of the volatile organic compound, it is contained in the mixed soil by promoting the growth and activity of aerobic microorganisms by operating the blower and sending air into the supply pipe. Volatile organic compounds and waste oil can be biodegraded stably (purification and detoxification by reductive dechlorination reaction), and the entire mixed soil can be purified in the optimal construction period. The leachate that leaches from the water can be purified, there is no risk of causing secondary pollution, no wastewater treatment facility is required, and it is necessary to dispose of it as specially managed industrial waste Ku, of leachate contamination can be cleaned.

  Regarding nutrient salts, nutrient salts mainly composed of straight-chain saturated monocarboxylic acid having 6 or more carbon atoms that can cope with activation and growth of anaerobic microorganisms and aerobic microorganisms are used. It dissolves gradually with respect to the moisture in the soil, and the rate of elution is more difficult as the carbon number increases, and the moisture content of the contaminated soil and certain nutrient salts (for example, caproic acid, pentanecarboxylic acid) , Butyl acetic acid, enanthic acid, enanthylic acid, hexane carboxylic acid, pentyl acetic acid, caprylic acid, heptane carboxylic acid, hexyl acetic acid, pelargonic acid, octane carboxylic acid) By this, the degradation of organochlorine compounds and oils due to activation and growth of anaerobic and aerobic microorganisms can be stabilized and optimized in a short period of time.

  In particular, when practicing the present invention, a part of excavated contaminated soil is analyzed to identify the pollutant and to determine the nature of the contaminated soil by measuring its moisture content. In the contaminated soil (surface layer portion) containing trichlorethylene and water content of 20% or less, the nutrient salt is selected from caproic acid and nutrient salt mainly composed of pentanecarboxylic acid. Use a blower, fan, etc., use an oil warm air heater, etc. as a heat source, set the air temperature to 15 ° C-38 ° C (preferably 20 ° C-35 ° C), and control the air flow with the blower damper By supplying air to the ventilation pipes in the contaminated soil, the indigenous aerobic microorganisms are propagated and promoted to promote bioactivity of volatile organic compounds and oil contained in the contaminated soil. Stable can be decomposed into dioxide carbon and water and low molecular weight in a short period of time with the.

  In addition, by analyzing a part of the excavated contaminated soil, identifying the pollutant and measuring its moisture content, the nature of the contaminated soil is ascertained. For example, trichlorethylene, an organochlorine compound, is contained. In contaminated soil (surface layer) with a water content of 20% or more, the nutrient salt is selected from pelargonic acid and octane carboxylic acid as the main components, the blower is used as a blower, and the oil temperature is used as the heat source. Use a wind heater or an electric heater to set the air temperature to 20 ° C to 40 ° C (preferably 25 ° C to 38 ° C), and control the air flow with a blower or fan damper for ventilation in contaminated soil. By supplying air to the piping, nutrient salts are eluted by the moisture of the contaminated soil and become feed for indigenous aerobic microorganisms. Volatile organic compounds and the oil bio stable can be decomposed into dioxide carbon and water and low molecular weight in a short period of time by.

  According to the second aspect of the present invention, by using a U-shaped groove formed of crushed stone, chestnut stone and concrete as a pipe protection means on the upper part of the air supply pipe, the load on the mixed soil can be increased It is possible to prevent the air supply pipe from being damaged or to block the air supply holes, and to supply air uniformly to the mixed soil, whereby aerobic microorganisms can be stably grown and promoted. The material of the air supply pipe is preferably made of steel having a thickness of about 3 mm.

  According to the third aspect of the present invention, by using a U-shaped groove formed of crushed stone, gravel, concrete as a pipe protection means on the upper part of the water collection pipe, the load on the mixed soil can be increased Water collection pipes can be prevented from being damaged and water collection holes can be blocked, and the water leached from the mixed soil can be collected stably, pumped up by a pump, and then sprinkled into the mixed soil again. Thus, aerobic microorganisms or anaerobic microorganisms can be grown and promoted in activity. The material of the water collecting pipe is preferably made of steel having a thickness of about 3 mm.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a cross-sectional view showing an outline of excavating contaminated soil of the present invention with a heavy construction machine and backfilling the mixed soil with a soil mixer.

In FIG. 1, the contaminated soil 1 in the contaminated area is excavated by a heavy construction machine 2 (excavator, bulldozer), the contaminated soil 1 is put into a soil mixer 3, and the nutrient storage provided in the soil mixer 3 A mixed soil 6 mixed with a nutrient salt 5 mainly composed of a linear saturated monocarboxylic acid having 6 or more carbon atoms stored in the hopper 4 is buried in a separately excavated area covered with a water shielding sheet 7. It is a method of purifying by returning.

  The details of the separately excavated area covered with the water shielding sheet 7 will be described with reference to FIG.

  FIG. 2 is a cross-sectional view showing an outline for producing the mixed soil of the present invention.

  In FIG. 2, the contaminated soil 1 excavated by the heavy construction machine 2 is put into a contaminated soil input hopper 8 of the soil mixer 3, pushed forward by a conveyor 9, and conveyed by a rotor 10 in a certain amount. Then, the nutrient salt 5 mainly composed of a linear saturated monocarboxylic acid having 6 or more carbon atoms stored in the nutrient salt storage hopper 4 provided in the soil mixer 3 is added.

  The contaminated soil 1 to which the nutrient salt 5 is added is finely crushed by a soil crushing section 11 provided in front of the transporting conveyor 9, and the contaminated soil 1 and the nutrient salt 5 are uniformly mixed, It becomes the mixed soil 6 and is put into the discharge conveyor 12. In addition, the mixing ratio of the contaminated soil and the nutrient salt is a pollutant obtained by analyzing a part of the excavated contaminated soil 1 (for example, in the case of tetrachlorethylene, three times the amount of substitution of chlorine and hydrogen for detoxification and decomposition) ) Type and concentration.

  FIG. 3 is a cross-sectional view schematically showing the mixed soil purification method of the present invention.

  The excavated non-contaminated area has a gradient of 2 to 4 degrees, the water shielding sheet 7 is laid thereon, and one or more water collecting pipes 13 are provided above the water shielding sheet 7 on the lower side of the gradient. This is installed, and gravel 14 is spread over the water collecting pipe 13 so as to cover the water collecting pipe 13, and the ground is leveled, and one or more air supply pipes 16 communicated from the blower 15 are installed on the gravel 14 A crushed stone (kuriishi) 17 is laid down so as to cover the air supply pipe 16 and leveled horizontally, and the mixed soil 6 is stacked thereon. The stacked height of the mixed soil 6 is preferably 50 cm to 90 cm. Since the ground is finally leveled by the heavy construction machine 3, it is necessary to load the mixed soil 6 in consideration of the load of the heavy construction machine 3 and the like. is there.

  The mixed soil 6 contains an organic chlorine compound, a volatile organic compound VOC (for example, cisDCE, trichloroethylene, tetrachloroethylene, formaldehyde, toluene, benzene, xylene, etc.) and waste oil. These are chemically stable and difficult to decompose, and as a reaction that has become widespread for various uses in industry, it is now a cause of contamination of soil and groundwater.

  The nutrient salt 5 mixed in the mixed soil 6 specifies a nutrient salt mainly composed of a linear saturated monocarboxylic acid having 6 or more carbon atoms, and the aerobic microorganism group in the mixed soil 6 It becomes a nutritional agent that proliferates and activates.

  Specifically, linear saturated monocarboxylic acids having 6 or more carbon atoms include, for example, caproic acid, pentanecarboxylic acid, butylacetic acid, enanthic acid, enanthylic acid, hexanecarboxylic acid, pentylacetic acid, caprylic acid, heptanecarboxylic acid. Acids, hexyl acetic acid, pelargonic acid, octane carboxylic acid, heptyl acetic acid and the like as main components are raised and are appropriately selected depending on the water content of the mixed soil 6.

  The mixed soil 6 is purified by analyzing a part of the excavated contaminated soil 1 and then measuring the moisture content and temperature of the contaminated soil 1 to obtain a heat source device 18 (electric heater, hot oil hot air heater, etc.). ) Is set to 20 to 40 ° C. (preferably 25 to 38 ° C.).

  Further, the heat source device 18 is forcibly supplied to the mixed soil 6 through the supply pipe 16 by the communicated blower 15. As a condition for supplying air, a portion of the leachate in the storage tank 19 is extracted, the concentration of cisDCE is measured in time series by gas chromatography, and the blower 15 is operated when the concentration rises and stabilizes.

  As a result, an active environment of aerobic microorganisms indwelling in the mixed soil 6 is created, and the nutrient salt 5 is mixed at a temperature at which the aerobic microorganisms are activated. When activated, the organic chlorine compound, volatile organic compound VOC, and waste oil contained in the mixed soil 6 are decomposed.

  Further, leachate leached from the mixed soil 6 into the water shielding sheet 7 is stored in the storage tank 19 through the water collecting pipe 13.

  The leachate in the storage tank 19 is pumped up by a water collection pump 20, and is pressed by a water spray pump 21 provided at the rear stage of the storage tank 19 and is stacked on the top of the mixed soil 6 stacked through a water spray pipe 22. By spraying water, the nutrient 5 mixed in the mixed soil 6 can be eluted by spraying water without the need for wastewater treatment, and contained in the mixed soil 6 by aerobic microorganisms. The decomposition of the organic chlorine compound, volatile organic compound VOC, and waste oil can be further accelerated.

  The purification treatment of the present application utilizes the characteristics of anaerobic microorganisms and aerobic microorganisms that lower the molecular weight of pollutants. By taking out part of the leachate from the storage tank 10 and analyzing it by gas chromatography, When the concentration of trichlorethylene and tetrachlorethylene is high and the concentration of cisDCE is low (initial state), air is not supplied to the mixed soil 6, and the contaminants of the mixed soil 6 are reduced by anaerobic microorganisms. A part of the leachate is taken out at intervals of one month and analyzed by gas chromatography. When the concentration of cisDCE increases and becomes stable, the blower 15 forces the mixed soil 6 through the supply pipe 16 to the mixed soil 6. This is a method for purifying anaerobic and aerobic treatments to reduce the molecular weight of pollutants by aerobic microorganisms. State of the mixed soil 6 by it can be determined, cleaned soil can be well or reused as it is allowed.

  As the carboxylic acid of the nutrient salt 5, it is essential that the number of carbon atoms is 6 or more. If the number of carbon atoms is less than 6 (for example, formic acid or butyric acid), the solubility in the leachate is too high. Is less than 6 (for example, formic acid, butyric acid) most of the basic components dissolve, there is a problem of destabilizing the quality of leachate water such as malodor due to the propagation of various bacteria, the water content of the contaminated soil 1, A correlation between the supply air temperature forcibly supplied by the specific nutrient 5 and the blower 15 and the supply air amount is established to create and control an environment in which aerobic microorganisms are propagated and activated. It is difficult to purify.

  In addition, although it is not necessary to set the upper limit of the carbon number, it is considered that the carbon number is about 18 as industrially available in large quantities (but not necessarily limited to those having 18 or less carbon atoms). Needless to say that there is nothing.) If the carbon number is too large, the water solubility is further deteriorated (it takes time to dissolve), and the effect (effectiveness) as the nutrient 5 is lowered as described above.

  In addition, the carboxylic acid of the present application has a linear structure, and is preferably a saturated monocarboxylic acid (the basic contents thereof are described in JP 2000-334492 A). )

  As described above, in the case of the nutrient salt 5 having a large number of carbons, it takes time to dissolve in the mixed soil 6 and the effect as the nutrient salt 5 is reduced (slow effect). Fatty acid) may be added with alcohol (glycerin) to form an ester (oil or fat). That is, the carboxylic acid is converted to an ester bond with glycerin, so that the water solubility of the carboxylic acid is increased, and an auxiliary contribution to the purification by the carboxylic acid can be expected (for these contents and the like, see JP-A-2002-370085). As described in the Gazette).

  Temporarily, from the viewpoint of the pollution purification treatment period, there are short-term to medium-term to long-term, etc. For example, if it is short-term, a carboxylic acid having a small carbon number and a carboxylic acid esterified with glycerin It can be considered. On the contrary, if it is long-term, it can be considered to use a carboxylic acid having a large number of carbons (eg, stearic acid) or a nutrient salt that does not use glycerin. That is, the carbon number of the carboxylic acid and the amount of glycerin added can be freely selected, and the optimum purification treatment conditions such as the amount added can be controlled, so that it is possible to freely deal with limited places.

  From the above description, “Land Farming”, which is one of the biotechnological method classifications, is a known method, but the feature of the present application is that the nutrient 5 is specified and anaerobic / aerobic treatment is performed. By doing this, a new unique effect will be produced.

  Although one embodiment has been described above, it is self-evident to diversify and develop each embodiment by appropriately combining each embodiment in accordance with the pollution situation at the site.

This invention activates anaerobic microorganisms and aerobic microorganisms using a bioremediation method, promotes purification of soil contaminated with organochlorine compounds and waste oil, and purifies contaminated areas in situ in a short time Applicable to equipment.

Sectional drawing which shows the outline | summary which excavates the contaminated soil of this invention with construction heavy machinery, and backfills mixed soil with a soil mixer Sectional drawing which shows the outline which manufactures the mixed soil of this invention Sectional drawing which shows the outline of the purification method of the mixed soil of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Contaminated soil 2 Construction heavy machine 3 Soil mixing machine 4 Nutrient salt storage hopper 5 Nutrient salt 6 Mixed soil 7 Water shielding sheet 8 Contaminated soil input hopper 9 Conveyor 10 Rotor 11 Soil crushing part 12 Discharge conveyor 13 Collecting pipe 14 Gravel 15 Blower 16 Air supply piping 17 Crushed stone (Kuriishi)
18 heat source device 19 storage tank 20 water collecting pump 21 watering pump

Claims (3)

The contaminated soil area is excavated using a heavy construction machine, and the excavated contaminated soil and a nutrient salt mainly composed of a linear saturated monocarboxylic acid having 6 or more carbon atoms are mixed by a soil mixer. A water shielding sheet is laid in the excavated area, and the slope of the water shielding sheet is maintained at 2 to 4 degrees. Then, a water collecting pipe is provided below the slope, and gravel is disposed on the water shielding sheet. A method for purifying contaminated soil, wherein the air supply pipe is arranged on the ground, and the mixed soil in which the contaminated soil and the nutrient salt are mixed is introduced by the soil mixer, the air supply pipe The inhaled anaerobic microorganisms and aerobic microorganisms are propagated and activated by blowing air to the mixed soil in intermittent operation through the air blower communicated with the leaching water that is leached into the water shielding sheet, for collecting water Pumped by a pump using piping Purification method using a method for decomposing the volatile organic compounds in the contaminated soil by spraying the mixed soil. The purification method according to claim 1, wherein a pipe protection means is used in an upper part of the air supply pipe. The purification method according to claim 1, wherein a pipe protection means is used in an upper part of the water collection pipe.

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