JP2008221167A - Soil purification method and apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a soil purification method and apparatus which can be applied in any place without restriction, make a system simple and compact, and inhibit a spread of contamination. <P>SOLUTION: The contaminant-containing soil purification method comprises the process of throwing an activated carbon cartridge 14 into soil, and the process of supplying a microorganism activator to the activated carbon cartridge 14. Contaminant-decomposing microorganisms in the soil are activated by the microorganism activator, and the activated microorganisms are made to grow on the surface of activated carbon. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a soil purification method and apparatus, and more particularly to a method and apparatus for purifying soil groundwater contaminated with volatile organic solvents such as organochlorine compounds.

  For example, Patent Document 1 discloses a pumped water aeration method widely used as a method for purifying contaminated soil. This method is a method of purifying soil by pumping groundwater contaminated with an organic solvent with a vacuum pump, aeration in a container, and adsorbing the organic solvent moved to the air after aeration to the activated carbon. However, this pumped water aeration method requires a pumping well, a vacuum pump, a gas-liquid separation tank, a fume tank, a blower, and an activated carbon adsorption tank. In this way, the equipment cost is high due to the large number of devices, and a relatively large installation area is required. In addition, it is necessary to replace the activated carbon as appropriate, which raises the problem that the introduction cost and maintenance cost of the equipment are increased.

On the other hand, for example, there is an in-situ bioremediation method as disclosed in Patent Document 2 as a purification method that can reduce the introduction cost of equipment. In this method, microbial organic solvents are decomposed by microorganisms by injecting a solution of a microbial activator mainly composed of organic matter into a well provided upstream of contaminated groundwater and activating the microorganisms in the soil and groundwater. It is a construction method. In this method, the main equipment is a microbial activator solution tank and an injection pump to some extent, and the introduction cost of the equipment can be relatively low. In addition, it is said that tetrachloroethylene, trichlorethylene, etc., which are main pollutants in soil and groundwater, can be decomposed.
JP 2007-21280 A JP 2006-218457 A

  However, in the method of Patent Document 2, cis-1,2-dichloroethylene, which is an intermediate product in the decomposition process, may not be decomposed and accumulated.

  Specifically, it is known that a Dehalococcoides genus bacterium (hereinafter referred to as “cis-1,2-dichloroethylene-degrading microorganism”) is required to decompose cis-1,2-dichloroethylene. For this reason, in soil where cis-1,2-dichloroethylene-degrading microorganisms do not exist, cis-1,2-dichloroethylene remains undecomposed even when the construction method of Patent Document 2 is applied. That is, the in-situ bioremediation method has a limited application location.

  In addition, in order to purify groundwater in soil where cis-1,2-dichloroethylene-degrading microorganisms are present, the microorganism activator solution must be sufficiently infiltrated and cis-1,2-dichloroethylene-degrading microorganisms must be propagated over a wide area. There wasn't. For this reason, a large amount of organic matter must be injected into the groundwater, which may cause contamination and diffusion. In addition, it takes about several months for the cis-1,2-dichloroethylene-degrading microorganisms to grow until the purification of soil and groundwater is sufficiently advanced, and the purification period may be significantly increased.

  The present invention has been made in view of such circumstances, and provides a soil purification method and apparatus that does not limit the place of application, can make the equipment simple and compact, and does not cause the contamination and diffusion of soil. For the purpose.

  In order to achieve the above object, Claim 1 of the present invention is a method for purifying soil containing pollutants, comprising the steps of introducing activated carbon into the soil and supplying a microbial activator to the activated carbon. And a soil purification method characterized by activating microorganisms in the soil that decomposes the pollutant with the microorganism activator and allowing the activated microorganisms to grow on the activated carbon surface.

  According to the first aspect, since the microbial activator is supplied to the activated carbon and the microbial activator is adsorbed on the activated carbon surface, the microorganisms in the soil are activated on the activated carbon surface and efficiently propagated, and are not decomposed. It can adsorb and remove pollutants in the soil.

  Thereby, while being able to make an installation simple and compact, the spreading | diffusion of pollution by inject | pouring a microbial activator into soil in large quantities can be suppressed. In the present invention, the soil includes groundwater, groundwater containing sand particle components, and the like.

  A second aspect is characterized in that, in the first aspect, the microbial activator is supplied to a place where the activated carbon is introduced.

  According to the second aspect, since the microbial activator is supplied to the place where the activated carbon is introduced, the microbial activator can be efficiently adsorbed on the activated carbon surface.

  A third aspect of the present invention is characterized in that, in the first aspect, the microbial activator is supplied into the soil upstream of the activated carbon.

  According to the third aspect, since the microbial activator is supplied to the soil upstream of the activated carbon, the activated microorganism can be adsorbed and grown on the activated carbon downstream, and is not decomposed. It can also remove contaminants in soil.

  A fourth aspect of the present invention is characterized in that, in any one of the first to third aspects, the microbial activator uses an organic substance or a mixture of the organic substance and an inorganic substance.

  According to the fourth aspect, the microorganisms in the soil that decompose the pollutants can be effectively activated. Note that glucose, acetic acid, butyric acid, lactic acid, and the like are preferable as the organic substance, and nitrogen compounds, phosphorus compounds, and the like can be preferably used as the inorganic substance.

  A fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the contaminant is a volatile organic solvent containing an organochlorine compound.

  In claim 5, the organochlorine compound includes tetrachloroethylene, trichloroethylene, cis-1,2-dichloroethylene, and the like.

  According to a sixth aspect of the present invention, in order to achieve the above object, a well for purifying pollutants contained in soil, activated carbon filled in the well, and microbial activity for supplying a microbial activator to the activated carbon A soil purification device comprising: an agent supply means.

  According to the sixth aspect, the facility can be made simple and compact, and the diffusion of contamination caused by injecting a large amount of the microbial activator into the soil can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, an application place is not restrict | limited, While being able to make an installation simple and compact, the spreading | diffusion of soil contamination can be suppressed.

  Hereinafter, preferred embodiments of a soil purification method and apparatus according to the present invention will be described in detail with reference to the accompanying drawings.

  First, a first embodiment according to the present invention will be described. In the present embodiment, in the soil deposited in the order of the surface layer F, the sandy soil layer S (permeable layer), and the clay layer C (impervious layer), the contaminants that have permeated or flowed down from the surface due to infiltration or groundwater are permeable layer This is a method for purifying soil (including groundwater) in the contaminated area A with respect to the contaminated area A formed by depositing on the sandy soil layer S.

  In this embodiment, volatile organic solvents such as tetrachloroethylene (PCE), trichlorethylene (TCE), cis-1,2-dichloroethylene (trans-1,2-dichloroethylene) are used as pollutants that cause soil contamination. ), 1,1-dichloroethylene (1,1-DCE), chlorinated ethylene such as vinyl chloride (VC), 1,1,1-trichloroethane (MC or 1,1,1-TCA), 1,1,2 -Organic chlorine such as chlorinated ethane such as trichloroethane (1,1,2-TCA) and 1,2-dichloroethane (EDC), ethane tetrachloride, carbon tetrachloride (CT), chloroform (CF) and dichloromethane (DCM) And petroleum-based hydrocarbons represented by petroleum products such as naphtha, kerosene, LPG, and gasoline.

  In the present embodiment, an example of a microorganism that decomposes the volatile organic substance and an intermediate product (such as cis-1,2-dichloroethylene generated in the decomposition process of the organic chlorine compound) in the decomposition process will be described. The present invention is not limited to this, and can be applied to other microorganisms that inhabit soil and decompose pollutants.

  FIG. 1 is an explanatory diagram showing an example of a purification device 10 to which a soil purification method according to the present invention is applied.

  As shown in FIG. 1, the purification apparatus 10 mainly includes a well 12 buried in the formation, an activated carbon cartridge 14 introduced into the ground water through the well 12, and a microbial activator for storing a microbial activator. And a tank 16.

  The well 12 is installed in the soil so as to reach the clay layer C, which is an impermeable layer, on the downstream side of the contaminated area A. A screen 18 is formed on the side wall surface in contact with the water permeable layer of the well 12 so that groundwater can be introduced into the well 12. As a result, the activated carbon cartridge 14 and the microbial activator can be filled into the well 12, and groundwater can be introduced into the activated carbon cartridge 14 and the microbial activator.

  Although not particularly illustrated, the activated carbon cartridge 14 is a container in which a side wall is formed with a slit and filled with activated carbon particles, and is filled in the lower portion of the well 12. The activated carbon cartridge 14 has a function of adsorbing contaminants in the contaminated area A of groundwater and a function as a fixed bed for growing cis-1,2-dichloroethylene-degrading microorganisms in the groundwater. The activated carbon cartridge 14 is not limited to the form housed in the container as described above, and the activated carbon solidified in a cylindrical shape may be used directly.

  The microbial activator tank 16 stores a microbial activator serving as a substrate for microorganisms in the soil (including cis-1,2-dichloroethylene-degrading microorganisms), and is connected to the well 12 via the pump 22 and the injection pipe 24. They are connected (the microbial activator tank 16, the pump 22, and the injection pipe 24 correspond to microbial activator supply means).

  Such a microbial activator is not particularly limited as long as it becomes a substrate for microorganisms including cis-1,2-dichloroethylene-degrading microorganisms. For example, organic substances such as glucose, acetic acid, butyric acid, lactic acid, nitrogen compounds, An inorganic substance such as a phosphorus compound, or a mixture of the organic substance and the inorganic substance can be used. In particular, it is preferable to use a mixed solution of glucose, ammonium sulfate and dipotassium hydrogen phosphate as the microbial activator.

  The microbial activator is added in a range suitable for the growth of cis-1,2-dichloroethylene-degrading microorganisms in groundwater. For example, the TOC concentration (organic substance concentration) in the groundwater at the original position is 50 mg / L or more. Are added as follows.

  It is preferable that a plurality of wells 12 are arranged in accordance with the positional relationship with the contaminated area A and the flow direction of groundwater so that the purification efficiency is high.

  2 and 3 are top views for explaining examples of the arrangement form of the wells 12. 2A is a top view illustrating an example of the arrangement form of the wells 12, and FIG. 2B is a top view illustrating another example of the arrangement form.

  As shown in FIG. 2 (A), for example, the plurality of wells 12 are arranged in a row in the direction orthogonal to the flow direction (arrow) of groundwater on the downstream side of the contaminated area A. This arrangement is mainly suitable when the decomposition load of the pollutant on the activated carbon is low, such as when the flow rate of groundwater is small.

  As shown in FIG. 2 (B), a plurality of wells 12a, 12a,... And a plurality of wells 12b, 12b, etc. can be arranged in two rows in a direction perpendicular to the direction of groundwater flow. In this case, it is preferable to arrange the second row of wells so as to collect groundwater that bypasses the first row of wells. This arrangement is mainly suitable when the decomposition load of the pollutant on the activated carbon is high, such as when the flow rate of groundwater is large.

  As a result, even if the groundwater is not purified by bypassing between the adjacent wells 12 and 12 in the first row, it is collected by the wells 12 in the second row. Spilling out can be suppressed. In addition, although the case where the well 12 was arrange | positioned 2 rows was demonstrated in the figure, it is not limited to this, Three or more rows may be sufficient.

  Further, a plurality of wells 12 can be arranged as shown in FIG. 3 according to the site shape, the direction of groundwater flow, the distribution of contamination, and the like.

  Next, the effect | action of the purification apparatus 10 of this embodiment is demonstrated with reference to FIG.

  First, the activated carbon cartridge 14 is filled in the bottom of the well 12.

  Next, a microbial activator mainly containing an organic substance is supplied from the microbial activator tank 16 through the pump 22 and the injection pipe 24. Thereby, the microbial activator is adsorbed on the activated carbon surface.

  When the activated carbon cartridge 14 to which the microbial activator is adsorbed contacts the groundwater, microorganisms (including cis-1,2-dichloroethylene-decomposing microorganisms) in the groundwater grow on or near the activated carbon surface. These microorganisms decompose trichlorethylene in groundwater and produce cis-1,2-dichloroethylene as an intermediate. Then, using the produced cis-1,2-dichloroethylene as a substrate, cis-1,2-dichloroethylene-degrading microorganisms grow on or near the activated carbon surface.

  In this way, activated carbon is introduced into groundwater, and the microbial activator, which is a substrate for microorganisms, is adsorbed on the surface of the activated carbon, so that cis-1,2-dichloroethylene-degrading microorganisms in groundwater mainly grow on the surface of the activated carbon. And can be immobilized. Therefore, the amount of the microbial activator injected into the well can be significantly reduced as compared with the conventional case, and cis-1,2-dichloroethylene in the groundwater can be efficiently decomposed and removed.

  Further, even in soil where cis-1,2-dichloroethylene-degrading microorganisms do not inhabit, the activated carbon can be physically adsorbed with contaminants, and the groundwater can be purified. In this case, the purification performance can be maintained by replacing a part of the activated carbon with a new one before the entire activated carbon breaks through.

  In this embodiment, the example using the cylindrical well 12 has been described. However, the present invention is not limited to this, and a groove 26 having a predetermined length as shown in FIG. 4 may be used. As a result, as compared with the case where a plurality of wells 12 are arranged (for example, FIG. 2A), the groundwater always passes through the groove 26 unless it bypasses the groove 26, so that contaminants can be more reliably removed. Can be removed.

  Next, a second embodiment according to the present invention will be described. This embodiment is a method of purifying the pulverized coal slurry in the soil while being injected into the well 12 instead of periodically replacing the activated carbon cartridge.

  FIG. 5 is an explanatory diagram illustrating an example of the purification device 20 according to the second embodiment.

  As shown in FIG. 5, the pulverized coal slurry tank 28 for supplying the pulverized coal slurry into the well 12 instead of the activated carbon cartridge 14 is provided.

  The pulverized coal slurry tank 28 stores pulverized coal slurry, and is connected to the well 12 via a pump 32 and a pipe 34. The pulverized coal slurry is obtained by dissolving activated carbon having a particle size of about 0.5 to 100 μm in water.

  First, pulverized coal slurry is injected into the well 12 from the pulverized coal slurry tank 28 via the pump 32 and the injection pipe 34. At the same time, the microbial activator is injected into the well 12 from the microbial activator tank 16. In this way, the pulverized coal slurry and the microbial activator are mixed, and the microbial activator is adsorbed on the surface of the pulverized coal and accumulated at the bottom of the well 12. After a predetermined amount of pulverized coal slurry has been injected, the injection is stopped.

  When the pulverized coal with the microbial activator adsorbed on the surface comes into contact with groundwater containing contaminants introduced through the screen 18, cis-1,2-dichloroethylene-decomposing microorganisms grow on the surface of the pulverized coal. Thereby, cis-1,2-dichloroethylene in groundwater is decomposed and removed.

  This embodiment is particularly effective when cis-1,2-dichloroethylene-decomposing microorganisms are surely present in the soil and pulverized coal does not need to be replaced.

  Next, a third embodiment will be described. The present embodiment is a method for purifying soil by separately arranging a well 36 for injecting a microbial activator and a well 38 for injecting activated carbon.

  FIG. 6 is a diagram illustrating the purification device 30 in the present embodiment. As shown in FIG. 6, instead of the well 12, a well 36 for injecting a microbial activator and a well 38 for injecting activated carbon are separately provided, and the configuration is the same as in FIG.

  The well 36 for injecting the microbial activator is provided on the upstream side of the contaminated area A. Thereby, the cis-1,2-dichloroethylene decomposing microorganism can be activated and supplied to the contaminated area A on the upstream side of the contaminated area A.

  A well 38 into which the activated carbon cartridge 14 is placed is provided on the downstream side of the contaminated area A. As a result, activated cis-1,2-dichloroethylene-degrading microorganisms can be collected on the activated carbon surface on the downstream side of the contaminated area A, and contaminants that have not been decomposed can be adsorbed.

  Thus, according to this embodiment, the cis-1,2-dichloroethylene-decomposing microorganisms in the soil can be activated by injecting the microbial activator into the groundwater and passing through the contaminated area A. Then, on the downstream side of the contaminated area A, activated cis-1,2-dichloroethylene-degrading microorganisms can be collected on the activated carbon surface. Further, since the undecomposed contaminants are also adsorbed on the activated carbon surface, it is possible to suppress the accumulation of a large amount of undegraded contaminants and microbial activators on the downstream side.

  As mentioned above, although preferable embodiment of the purification method and apparatus of the soil concerning this invention was described, this invention is not limited to the said embodiment, Various aspects can be taken.

  For example, in each of the above-described embodiments, an example in which activated carbon is introduced into soil has been described. However, the present invention is not limited to this, and support materials (such as porous materials) other than activated carbon can be used.

  In the first and second embodiments, the example in which the microbial activator is adsorbed to the activated carbon by supplying the microbial activator after the activated carbon has been introduced into the well has been described. What has been adsorbed with a microbial activator in advance may be introduced into the well.

It is explanatory drawing which shows an example of the purification apparatus of 1st Embodiment which concerns on this invention. It is a top view which shows an example of the arrangement | positioning form of the well of FIG. It is a top view which shows the other example of the arrangement | positioning form of the well of FIG. It is explanatory drawing which shows the other aspect of the purification apparatus of 1st Embodiment. It is explanatory drawing which shows an example of the purification apparatus of 2nd Embodiment. It is explanatory drawing which shows an example of the purification apparatus of 3rd Embodiment.

Explanation of symbols

  10, 20, 30 ... purification device, 12, 36, 38 ... well, 14 ... activated carbon cartridge, 16 ... microbial activator tank, 18 ... screen, 22, 32 ... pump, 24, 34 ... injection pipe, 26 ... groove, 28 ... Pulverized coal slurry tank

Claims (6)

In the purification method of soil containing pollutants,
Introducing activated carbon into the soil;
Supplying a microbial activator to the activated carbon,
A method for purifying soil, comprising activating microorganisms in the soil that decomposes the pollutant with the microbial activator, and allowing the activated microorganisms to grow on the activated carbon surface.   The soil purification method according to claim 1, wherein the microbial activator is supplied to a place where the activated carbon is introduced.   The soil purification method according to claim 1, wherein the microbial activator is supplied into the soil upstream of the activated carbon.   The soil purification method according to any one of claims 1 to 3, wherein the microbial activator uses an organic substance or a mixture of the organic substance and an inorganic substance.   The soil purification method according to any one of claims 1 to 4, wherein the pollutant is a volatile organic solvent containing an organochlorine compound. A well for purifying pollutants in the soil;
Activated carbon filled in the well;
Microbial activator supply means for supplying a microbial activator to the activated carbon;
A soil purification apparatus comprising:

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