JP2022151501A - Soil cleaning agent and soil cleaning method - Google Patents

Abstract

To provide a soil cleaning agent and a soil cleaning method by which it is possible to reduce movement in a contaminated soil, thereby efficiently cleaning the contaminated soil.SOLUTION: A soil cleaning agent decomposes and removes oils contained in a soil by being dispersed in a contaminated soil. The soil cleaning agent includes a microbe-containing solution, which includes an oils decomposable microbe having oils decomposability, and a nutrient for the purpose of action of the microbe, and a thickener to increase viscosity of the solution.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a soil cleaning agent and a soil cleaning method for cleaning contaminated soil contaminated with oils (hydrocarbon compounds, oils and fats of animals and plants, etc.).

As is well known, for example, in oil storage facilities such as factories and gas stations (e.g., oil storage facilities), mistakes in handling and oils (e.g., mineral oils such as petroleum, benzene, etc.) from storage tanks Hydrocarbon compounds), etc., may leak or flow out and permeate into the soil, contaminating the underground soil. Oils that have soaked into the underground soil are a cause of soil contamination.

Therefore, as a technology to purify contaminated soil infiltrated with oils, a soil remediation agent containing oil-degrading microorganisms that decompose oils is injected into the underground soil, and the infiltrated oils are removed. A soil remediation technique for decomposing and removing soil by degrading microorganisms is known (see, for example, Patent Document 1).

As a general soil remediation technique, for example, a pipe is driven into the ground of contaminated soil, a soil remediation agent is supplied into this pipe, and the soil remediation agent is injected into the underground soil through a hole in the side of the pipe by pressure. There is a way.
Thus, it takes several months, for example, to decompose and remove oils by the oil-degrading microorganisms.

On the other hand, for example, the degree of soil contamination in the underground soil is generally not uniform depending on the position (depth, etc.) in the underground soil, and the degree of contamination is uneven in the underground soil.
In particular, as shown in FIG. 29, in the soil G in which the aquifer W through which groundwater is formed, the oils that permeate the soil G have a small specific gravity and are insoluble in water. etc. have the property of staying near the groundwater table (upper part) of the aquifer W. Therefore, a contaminated area C is formed near the groundwater table (upper part).

Therefore, in order to perform soil remediation efficiently and economically, the degree of contamination in the underground soil G is investigated in advance, and as shown in FIG. There is a case where a depth-specific injection method is applied in which the cleaning agent injection device 100 is installed in correspondence with the depth of the contaminated soil area C near the groundwater level of the aquifer W with a large water level and the soil cleaning agent M0 is injected.

JP 2012-228191 A

However, for example, the soil cleaning agent M0 injected near the groundwater table by the depth-specific injection method has a higher specific gravity than the oils. As shown in FIG. 30, the soil remediation agent M0 moves and diffuses to a position deeper than the contaminated area C near the groundwater table and to the downstream side of the groundwater during the several months until the decomposition and removal of the soil is completed. There is a problem of storage.
As a result, it may be necessary to inject the soil cleaning agent over a long period of time, and even if a large amount of the soil cleaning agent is injected, the expected effect may not be obtained.

The present invention has been made in consideration of such circumstances, and provides a soil remediation agent and a soil remediation method that are capable of suppressing movement in contaminated soil and, in turn, remediating contaminated soil efficiently. intended to

In order to solve the above problems, the present invention proposes the following means.
(1) A first aspect of the present invention is a soil remediation agent that is injected into contaminated soil to decompose and remove oils contained in the soil, and contains an oil-degrading microorganism capable of decomposing oils. It is characterized by comprising a microorganism-containing solution, nutrients for the activity of the oil-degrading microorganisms, and a thickening agent for increasing the viscosity of the microorganism-containing solution.

According to the soil remediation agent of the present invention, the migration speed of the oil-degrading microorganisms contained in the microorganism-containing solution (soil remediation agent) in the contaminated soil is reduced, thereby increasing the residence time of the oil-degrading microorganisms. be able to.
As a result, oils contained in contaminated soil can be efficiently purified.

In this specification, "to stay" or "to stay longer" does not necessarily mean to stay at the same position, but rather that the oil-degrading microorganisms perform the oil-degrading action on the target position for a long time. It shall include performing.

Here, the thickening agent is a composition capable of increasing the viscosity of the microorganism-containing solution as a soil remediation agent by mixing (dissolving, etc.) with the microorganism-containing solution containing oil-degrading microorganisms. A substance (for example, polysaccharide, amino acid, protein, glycerin, rubber, etc.) shall be referred to.
In addition, the thickening agent may be solid such as powder or particles, or liquid (a composition that is liquid at room temperature, a thickened liquid obtained by dissolving or dispersing a solid thickening agent in a liquid such as water). It may be composed of a plurality of composition parts without being limited to a single composition. Since the thickener is dispersed in the soil, it is preferable that the thickener is made of a substance that does not affect the environment.
Oils refer to mineral oils such as petroleum, hydrocarbons (chain hydrocarbons and cyclic hydrocarbons), animal and plant oils and fats, or mixtures thereof.
Oil-degrading microorganisms include gram-negative bacteria, gram-positive bacteria (eg, Bacillus subtilis, actinomycetes), and fungi (eg, yeast) that decompose oils.
In addition, although the soil to be applied can be arbitrarily set, for example, it can be suitably applied to sandy to gravel soils.

(2) In the soil cleaning agent according to (1) above, the thickener may contain a polysaccharide.

According to the soil remediation agent according to the present invention, since it contains a polysaccharide as a thickening agent, the movement speed of the soil remediation agent in the soil is efficiently reduced, and the retention time of the oil-degrading microorganisms is lengthened. can do.
Moreover, even if it is mixed with a microorganism-containing solution containing oil-degrading microorganisms, the activity of the oil-degrading microorganisms is not inhibited.

Here, that the thickener contains a polysaccharide means that the thickener may consist only of a polysaccharide or contain a thickener other than the polysaccharide.

(3) In the soil cleaning agent according to (2) above, the thickener may contain xanthan gum.

According to the soil remediation agent according to the present invention, since the thickener contains xanthan gum, which is a type of polysaccharide, the movement speed of the soil remediation agent in the soil is efficiently reduced, and the oil decomposability is improved. The residence time of microorganisms can be lengthened.
Moreover, even if it is mixed with a microorganism-containing solution containing oil-degrading microorganisms, the activity of the oil-degrading microorganisms is not inhibited.

Here, the thickener containing xanthan gum means that the thickener may consist of only xanthan gum or may contain a thickener other than xanthan gum.

(4) In the soil cleaning agent according to (1) above, the thickener may contain an amino acid.

According to the soil remediation agent according to the present invention, since it contains an amino acid as a thickening agent, it efficiently reduces the movement speed of the soil remediation agent in the soil and prolongs the residence time of the oil-degrading microorganisms. be able to.
Moreover, even if it is mixed with a microorganism-containing solution containing oil-degrading microorganisms, the activity of the oil-degrading microorganisms is not inhibited.

Here, that the thickener contains an amino acid means that the thickener may consist of only amino acids or may contain a thickener other than amino acids.

(5) In the soil cleaning agent according to (4) above, the amino acid may contain polyglutamic acid.

According to the soil remediation agent according to the present invention, since the thickener contains polyglutamic acid, which is a type of amino acid, the movement speed of the soil remediation agent in the soil is efficiently reduced, and the oil decomposability is improved. The residence time of microorganisms can be lengthened.
Moreover, even if it is mixed with a microorganism-containing solution containing oil-degrading microorganisms, the activity of the oil-degrading microorganisms is not inhibited.

Here, that the thickener contains polyglutamic acid means that it may consist of only polyglutamic acid or may contain a thickener other than polyglutamic acid.

(6) In the soil cleaning agent according to (1) above, the oil-degrading microorganism may be at least one of Gram-negative bacteria, Gram-positive bacteria, and yeast.

According to the soil cleaning agent of the present invention, the oil-degrading microorganism is at least one of Gram-negative bacteria, Gram-positive bacteria, and yeast, so that oils can be efficiently decomposed and removed. .
Gram-negative bacteria can be arbitrarily selected in consideration of the speed of purification. Formulation) GHK-II (manufactured by Gate Co., Ltd.) is preferably applied.

(7) The soil remediation agent according to any one of (1) to (6) above, even if the thickener is mixed with the microorganism-containing solution after producing a thickened liquid dissolved in water. good.

According to the soil remediation agent of the present invention, since the thickener is dissolved in water to form a water-soluble thickened liquid, the thickener can be easily mixed with the microorganism-containing solution. can dissolve large amounts of thickening agents in

(8) The soil cleaning agent according to any one of (1) to (7) above may have a viscosity of 30 (mPa·s) or more.

According to the soil cleaning agent according to the present invention, since the viscosity is set to 30 (mPa·s) or more, it is possible to greatly reduce the movement speed in the soil and extend the residence time.
As a result, oils can be efficiently decomposed and removed.

(9) A second aspect of the present invention is a soil remediation method for injecting a soil remediation agent into contaminated soil to decompose and remove oils contained in the contaminated soil, wherein the soil remediation agent is injected into the contaminated soil. The depth direction position of the site to be injected with the cleaning agent is set, the cleaning agent injection hole of the soil cleaning agent injection device is arranged to correspond to the site to be injected with the cleaning agent, and any one of the above (1) to (8) is arranged. 2. Contaminated soil is cleaned by injecting the soil cleaning agent according to item 1 into the injection target site.

According to the soil remediation method according to the present invention, the migration speed of the oil-degrading microorganisms contained in the microorganism-containing solution (soil remediation agent) in the contaminated soil is reduced, thereby increasing the residence time of the oil-degrading microorganisms. be able to.
As a result, oils contained in contaminated soil can be efficiently purified.
In addition, since the soil cleaning agent is injected into the cleaning agent injection target site after setting the depth direction position of the cleaning agent injection target site, waste of the soil cleaning agent can be suppressed.

(10) In the soil remediation method described in (9) above, the soil in the contaminated soil may contain at least one of sand and gravel.
According to the soil remediation method according to the present invention, movement in the contaminated soil is suppressed even for soil with relatively high water permeability, including at least one of sand and gravel, and thus the contaminated soil is remedied efficiently. be able to.

According to the soil cleaning agent and the soil cleaning method according to the present invention, it is possible to reduce the moving speed of the soil cleaning agent in the contaminated soil. As a result, soil contamination can be purified efficiently.

It is a graph explaining the influence of the viscosity with respect to the retention property of the soil decontamination agent which concerns on 1st Embodiment of this invention. 4 is a graph for explaining the influence of viscosity on retention in sandy soil of Gram-negative bacteria, which are oil-degrading microorganisms, according to the first embodiment. 4 is a graph for explaining the influence of viscosity on retention of Gram-negative bacteria, which are oil-degrading microorganisms, in gravel soil according to the first embodiment. 4 is a graph for explaining the influence of viscosity on retention in sandy soil of actinomycetes, which are oil-degrading microorganisms, according to the first embodiment. 4 is a graph for explaining the influence of viscosity on retention in gravel soil of actinomycetes, which are oil-degrading microorganisms, according to the first embodiment. 4 is a graph for explaining the influence of viscosity on retention in sandy soil of Bacillus subtilis, which is an oil-degrading microorganism according to the first embodiment. 4 is a graph illustrating the influence of viscosity on retention of Bacillus subtilis, which is an oil-degrading microorganism, in gravel soil according to the first embodiment. 4 is a graph for explaining the effect of viscosity on retention of yeast, which is an oil-degrading microorganism, in sandy soil according to the first embodiment. 4 is a graph illustrating the influence of viscosity on retention of yeast, which is an oil-degrading microorganism, in gravel soil according to the first embodiment. FIG. 2 is a graph for explaining the influence of xanthan gum on oil-degrading microorganisms in the soil decontaminant according to the first embodiment, and is a graph showing changes in the number of viable bacteria over the course of treatment days. FIG. 2 is a graph for explaining the influence of oil-degrading microorganisms on xanthan gum in the soil decontaminant according to the first embodiment, and showing changes in viscosity over the course of treatment days. It is a figure explaining the oil decomposition property of the soil decontamination agent which concerns on 1st Embodiment, and is a graph which shows transition of oil concentration with progress of treatment days. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram explaining schematic structure of an example of the soil purification apparatus which concerns on 1st Embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram explaining schematic structure of the soil purification apparatus main body which concerns on 1st Embodiment. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram explaining an example of the outline of the soil remediation method based on 1st Embodiment, (A) is the state which inserted the cleaning agent injection apparatus into the contaminated soil, (B) is added in the cleaning agent injection apparatus. (C) shows the state in which the pressurization chamber is filled with the soil cleaning agent, (D) shows the state in which the soil cleaning agent is injected, and (E) shows the position of the main body of the cleaning agent injection device. It shows the action of moving. BRIEF DESCRIPTION OF THE DRAWINGS It is a conceptual diagram which shows the state which injects a soil cleaning agent into the soil explaining the outline of the soil cleaning method which concerns on 1st Embodiment. It is a conceptual diagram explaining the effect of the soil decontamination agent which concerns on 1st Embodiment. 4 is a graph illustrating the influence of viscosity on retention in sandy soil of Gram-negative bacteria, which are oil-degrading microorganisms, according to the second embodiment. 7 is a graph for explaining the influence of viscosity on retention in gravel soil of Gram-negative bacteria, which are oil-degrading microorganisms, according to the second embodiment. 7 is a graph for explaining the influence of viscosity on retention in sandy soil of actinomycetes, which are oil-degrading microorganisms, according to the second embodiment. It is a graph explaining the influence of the viscosity on the retention property in the gravel soil of actinomycetes, which are oil-degrading microorganisms, according to the second embodiment. 7 is a graph for explaining the influence of viscosity on retention in sandy soil of Bacillus subtilis, which is an oil-degrading microorganism according to the second embodiment. 7 is a graph illustrating the influence of viscosity on retention of Bacillus subtilis, which is an oil-degrading microorganism, in gravel soil according to the second embodiment. 7 is a graph illustrating the influence of viscosity on retention in sandy soil of yeast, which is an oil-degrading microorganism, according to the second embodiment. 7 is a graph illustrating the influence of viscosity on retention of yeast, which is an oil-degrading microorganism, in gravel soil according to the second embodiment. FIG. 10 is a graph for explaining the effect of polyglutamic acid on oil-degrading microorganisms in the soil decontaminant according to the second embodiment, and showing the change in the number of viable bacteria over the course of treatment days. FIG. 10 is a graph for explaining the influence of oil-degrading microorganisms on polyglutamic acid in the soil decontaminant according to the second embodiment, and showing changes in viscosity over the course of treatment days. It is a figure explaining the oil decomposition property of the soil decontamination agent which concerns on 2nd Embodiment, and is a graph which shows transition of the oil concentration with progress of treatment days. It is a conceptual diagram explaining the prior art of this invention. It is a conceptual diagram explaining the effect|action in the prior art of this invention.

<First embodiment>
Hereinafter, the soil cleaning agent according to the first embodiment of the present invention will be described.
[Soil cleaning agent]
The soil cleaning agent according to the first embodiment includes, for example, a microorganism-containing solution containing oil-degrading microorganisms having oil-degrading properties, nutrients for the activity of the oil-degrading microorganisms, and the viscosity of the microorganism-containing solution. and an increasing thickener.
Moreover, the viscosity of the soil decontamination agent is set to 50 (mPa·s), for example.
The viscosity of the soil remediation agent can be set arbitrarily. s) is more preferably set in the range of 80 (mPa·s) or more, and more preferably set the viscosity in the range of 30 (mPa·s) or more and 80 (mPa·s) or less.

Then, the soil cleaning agent is dispersed (eg, injected) into the soil contaminated with oils (for example, mineral oils such as gasoline, kerosene, light oil, heavy oil, cutting oil, and machine oil), benzene, etc., and the oils It is configured to decompose and remove oils by degrading microorganisms to purify the soil.

[Microorganism-containing solution]
The microorganism-containing solution is, for example, an aqueous solution containing oil-degrading microorganisms capable of degrading oils and nutrients for the activity of the microorganisms dissolved in water (water-soluble liquid) and containing the oil-degrading microorganisms and nutrients. It is said that
The composition of the microorganism-containing solution is determined by considering the form of the contaminated soil (target oils, contamination concentration, set target pollution remediation period, etc.), and removing the soil contamination at the target concentration (e.g., Environmental Standard Concentration) can be arbitrarily set within a range that can be decomposed below.

As the microorganism-containing solution, for example, it is possible to dilute and apply the environmental purification microorganism preparation GHK-II (manufactured by Gate Co., Ltd.), but it is not limited to the environmental purification microorganism preparation GHK-II. can be set to

[Oil-degrading microorganisms (oil-degrading microorganisms)]
Oil-degrading microorganisms can be arbitrarily selected from Gram-negative bacteria, Gram-positive bacteria (e.g., Bacillus subtilis), yeast, etc., after considering the target oil, target decontamination period, etc. is possible.

The environmental remediation microbial preparation GHK-II in this embodiment uses, for example, Gram-negative bacteria. Specifically, GHK-II includes Gram-negatives identified, for example, in US Pat. No. 5,715,477.

[Thickener]
The thickening agent can be arbitrarily set in consideration of the movement speed in the underground soil of the soil remediation agent produced by mixing with the microorganism-containing solution, but in this embodiment, for example, It is composed of xanthan gum, which is A thickener other than xanthan gum (polysaccharide) may be used in combination.

Also, xanthan gum (thickening agent) is dissolved in 20 L of water (water-soluble solvent) to produce a thickened liquid, and 20 L of the thickened liquid is mixed with the microorganism-containing solution to obtain 1000 L of the soil remediation agent. generated. Dissolving xanthan gum in water to form a thickened liquid is suitable for uniformly mixing a large amount of xanthan gum with the microorganism-containing solution.

The amount of the thickening agent to water can be arbitrarily set in consideration of the target viscosity and the like.
In addition, the thickener (and the solvent that dissolves the thickener), in order to ensure the action as a soil remediation agent, when mixed with the microorganism-containing solution, oil-degrading microorganisms (oil-degrading microorganisms) and the thickener should not interfere with each other to inhibit the soil remediation action of the soil remediation agent.
Specifically, it is necessary that the thickened liquid (thickener) does not kill the oil-degrading microorganisms and that the oil-degrading microorganisms do not inhibit the thickening action of the thickened liquid (thickener). .

Next, with reference to FIGS. 1 to 12, verification results regarding the feasibility of the soil remediation agent according to the present invention will be described. In the feasibility verification, (1) the effect of viscosity on retention, (2) the effect of thickeners on oil-degrading microorganisms, and (3) the effect of oil-degrading microorganisms on thickeners. , (4) confirmed the oil degradability of the soil decontamination agent.

(1) [Influence of viscosity on retention]
Hereinafter, with reference to FIG. 1, the influence of the viscosity on the retention of the soil decontaminant will be described.
FIG. 1 is a graph illustrating the influence of viscosity on the retention of a soil decontaminant. ). The verification by the viscosity and the flow rate (moving speed) shown in FIG. 1 is the result of the column test.
The conditions in the column test are as follows.

[Column test conditions]
Column: 28 cm in height from the top to the beginning of the curve, 30 cm in height from the dropping bottom, and 3 cm in inner diameter.
Filler: crushed white gravel, 500 μm < particle size < 1250 μm (particle size determined using a sieve)
Test viscosity: As shown in FIG. 1, the amount of xanthan gum added was varied to vary the viscosity of the test solution within the range of 60 (mPa·s). The test solution with no added xanthan gum is located on the leftmost side of the horizontal axis.

As a result, as shown in FIG. 1, the flow rate (moving speed) of the test solution to which no thickening agent was added was about 80 (ml/min), and the flow speed (moving speed) decreased as the viscosity increased. , was confirmed to impart retention.
As a result, when the viscosity was about 10 (mPa·s), the flow rate decreased by about 25%, and when the viscosity was about 20 (mPa·s), the flow rate decreased by about 38%, indicating an improvement in retention.
In particular, when the viscosity exceeded 30 (mPa·s), the decrease in flow rate became large, and an improvement in retention was recognized.
Further, when the viscosity exceeded 50 (mPa·s), no decrease in flow velocity was observed, and no further improvement in retention was observed.

Next, the influence of viscosity on the retention of oil-degrading microorganisms will be described with reference to FIGS. 2 to 9. FIG.
2 to 9 are graphs illustrating the influence of viscosity on the retention of oil-degrading microorganisms. Body concentrations (×10 ⁵ cells/mL) are shown. The verification based on the integrated flow rate and cell concentration shown in FIGS. 2 to 9 is the test result of the column test. The conditions in the column test are as follows.

[Column test conditions]
Column: 28 cm in height from the top to the beginning of the curve, 30 cm in height from the dropping bottom, and 3 cm in inner diameter.
Filler: Crushed white gravel, 500 μm <particle size <1250 μm (equivalent to sandy (sandy soil), particle size is specified using a sieve), 2000 μm <particle size <4000 μm (equivalent to gravelly (gravely soil))
1) Comparative Example 1: Distilled water contains microbial activation nutrients and oil-degrading gram-negative bacteria 2) Present invention example 1: Distilled water contains microbial-activating nutrients and gram-negative oil-degrading microorganisms Addition of bacteria and xanthan gum The concentration of oil-degrading microorganisms in the eluent in Comparative Example 1 and Inventive Example 1 was 1.0×10 ⁷ cells/ml, and the amount of xanthan gum added was 1.2 g/L. did.

Next, as shown in FIGS. 2 and 3, in Comparative Example 1, a high concentration of cells was rapidly eluted from the column for both sandy and gravel soils, and a thickening agent was added. In the case (Invention Example 1), bacterial cells were gently eluted from the column, and an improvement in retention of oil-degrading microorganisms was observed in both sand and gravel.

Next, with reference to FIGS. 4 to 9, the effect of viscosity on retention of oil-degrading microorganisms other than Gram-negative bacteria will be described. In Figures 4 to 9, the tests were performed with actinomycetes, Bacillus subtilis, and yeast as oil-degrading microorganisms, but the retention of oil-degrading microorganisms was improved in both sand and gravel for all microorganisms. was accepted.

Next, with reference to FIGS. 10 to 12, (2) the effect of the thickener on the oil-degrading microorganisms, (3) the effect of the oil-degrading microorganisms on the thickener, and (4) The oil degradability of the soil decontaminant will be explained. (2) Effects of thickeners on oil-degrading microorganisms, (3) Effects of oil-degrading microorganisms on thickeners, and (4) Verification of oil-degrading properties of soil remediation agents are as follows. was carried out by the beaker test shown in .
[Beaker test conditions]
The beaker test was carried out by storing 250 ml of test solutions according to Comparative Examples 1 and 2 and Example 1 of the present invention in a beaker, and adding 440 μl (concentration: 1500 mg/L) of light oil to each beaker.
1) Comparative Example 1: Addition of microorganism-containing solution GHK-II to distilled water 2) Comparative Example 2: Distilled water 3) Invention Example 1: Addition of microorganism-containing solution GHK-II and xanthan gum to distilled water The concentration of the microorganism-containing solution GHK-II in Example 1 of the present invention was 10 ml/L (100-fold dilution), and the amount of xanthan gum added was 1.2 g/L.

(2) [Influence of thickener on oil-degrading microorganisms]
Hereinafter, the influence of the thickener on oil-degrading microorganisms will be described with reference to FIG.
FIG. 10 is a graph illustrating the effect of a thickener in a soil decontamination agent on oil-degrading microorganisms. It shows the viable cell count (cfu/ml) of analogolytic microorganisms.
Regarding the effect of the thickener on the oil-degrading microorganisms, whether or not xanthan gum (thickening agent) kills the oil-degrading microorganisms was tested with respect to Comparative Example 1 and Invention Example 1. It was verified by the change in the number of viable oil-degrading microorganisms with the passage of days after the start of treatment.

As a result, as shown in FIG. 10, there was no significant difference in the number of viable bacteria over the course of treatment between Comparative Example 2 and Inventive Example 1. No impact was confirmed.

(3) [Effect of oil-degrading microorganisms on thickener]
Hereinafter, the influence of oil-degrading microorganisms on the thickener will be described with reference to FIG. FIG. 11 is a graph illustrating the effect of oil-degrading microorganisms in the soil decontamination agent on xanthan gum. ).
Regarding the effect of oil-degrading microorganisms on xanthan gum in the soil remediation agent, regarding Comparative Examples 1 and 2 and Inventive Example 1, the change in the viscosity of the test solution with the passage of days after the start of the test. verified.

As a result, as shown in FIG. 11, in Example 1 of the present invention, it was confirmed that the viscosity did not significantly decrease with the lapse of treatment days.
Therefore, it was confirmed that oil-degrading microorganisms do not affect the viscosity of xanthan gum.

(4) [Oil degradability of soil decontamination agent]
Hereinafter, with reference to FIG. 12, the oil degradability of the soil cleaning agent will be described. FIG. 12 is a graph for explaining the oil decomposability of the soil decontaminant, in which the horizontal axis indicates the treatment days from the start of the test, and the vertical axis indicates the oil concentration (mg/L).
Regarding the oil decomposability of the soil detergency agent, in Comparative Examples 1 and 2 and Inventive Example 1, changes in oil concentration with the number of days after the start of the test were verified.

As a result, as shown in FIG. 12, in Comparative Example 2, the oil concentration hardly decreased. On the other hand, in Comparative Example 1 and Inventive Example 1, it was confirmed that the oils concentrations decreased with the passage of treatment days, and that there was almost no difference between Comparative Example 1 and Inventive Example 1.
Therefore, it was confirmed that the soil decontamination agent according to Example 1 of the present invention exhibited sufficient oil-decomposing properties.

Next, a cleaning agent injection device and a soil cleaning method according to the first embodiment will be described with reference to FIGS. 13, 14 and 15. FIG.
Methods of injecting remediation agents include the strainer well method and the double packer method, which use an injection well with an injection port (or slit) in the depth range of the soil remediation target, and are currently used for soil remediation and soil improvement. It is possible to apply the grouting method. However, in order to maximize the effects of the present invention, a double packer method that allows injection according to depth as described below is more suitable.
FIG. 13 is a conceptual diagram illustrating a schematic configuration of an example of the cleaning agent injection device according to the first embodiment, and FIG. 14 is a conceptual diagram illustrating a schematic configuration of the main body of the soil purification device.
13 to 15, reference numeral 100 denotes a cleaning agent injection device, reference numeral 10 denotes an outer cylindrical member, reference numeral 14H denotes a slit, reference numeral 20 denotes a cleaning agent injection device main body, reference numeral 21H denotes a soil cleaning agent supply hole, Reference numeral 22 (22A, 22B) indicates a balloon (bag-like member).

<Soil purification device>
The cleaning agent injection device 100 includes, for example, an outer cylinder member 10 and a cleaning agent injection device main body 20 arranged inside the outer cylinder member 10, as shown in FIG.

As shown in FIG. 13, the outer cylindrical member 10 includes, for example, a pipe member 11 having a cylindrical straight pipe portion, and an elastic cylindrical member 14 arranged on the outer peripheral surface of the pipe member 11. ing.
It is preferable that the pipe member 11 has a streamlined leading end (lower portion) that is gradually reduced in diameter toward the leading end (lower side) and slightly bulges outward. .

The pipe member 11 has, for example, a plurality of through holes 11H penetrating in the thickness direction at intervals in the longitudinal direction (vertical direction). In addition, the through hole 11H may be formed only at one place in the longitudinal direction.
In addition, a plurality of (eg, three) through-holes 11H are formed radially in the circumferential direction of the pipe member 11 at each position in the longitudinal direction.

The elastic cylinder member 14 is made of, for example, elastic rubber or the like, and is formed in a cylindrical shape that can be attached to the outer circumference of the pipe member 11 .
Further, in this embodiment, the elastic tubular member 14 is formed with a slit 14H along the entire circumferential direction at a position where the position in the longitudinal direction overlaps with the through hole 11H.
The material forming the elastic cylindrical member 14 is not limited to rubber or the like, and can be set arbitrarily.

As shown in FIGS. 13 and 14, the main body 20 of the purifying agent injection device includes, for example, a rod member 21, a balloon (bag-like member) 22 disposed on the outer peripheral surface of the rod member 21, and air is supplied to the balloon 22. and a balloon air supply pipe 23 for

The rod member 21 is formed, for example, in a bottomed cylindrical inner hole (not shown) in which a hole is formed inward along the longitudinal direction and the lower end is closed. A cleaning agent supply nozzle 21H is formed that penetrates from the outer peripheral surface to an inner hole (not shown) and ejects the soil cleaning agent from the hole (not shown) to the outer peripheral surface.

As shown in FIGS. 13 and 14, the balloon (bag-shaped member) 22 includes, for example, a lower balloon (lower bag-shaped member) 22A arranged on the lower side of the purifying agent supply nozzle 21H and a lower balloon (lower bag-shaped member) 22A arranged on the upper side. and an upper balloon (upper bag-like member) 22B.
The lower balloon (lower bag-shaped member) 22A and the upper balloon (upper bag-shaped member) 22B include base portions 221A and 221B attached to the outer peripheral surface of the rod member 21, and balloon main bodies 222A and 222B that actually inflate and deflate. , is equipped with

The balloon (bag-shaped member) 22 is a bag-shaped member made of an elastic material such as rubber. A soil decontaminant pressurizing chamber 100P is formed between the lower balloon (lower bag-like member) 22A and the upper balloon (upper bag-like member) 22B by bringing them into contact with the inner peripheral surface of the outer cylindrical member 10, respectively. It is configured.

As shown in FIGS. 13 and 14, the balloon air supply pipe 23 is connected to the balloon (bag-like member) 22 on the downstream side and to an air supply source (not shown) on the upstream side.
Specifically, the balloon air supply pipe 23 is connected on the downstream side to a lower balloon (lower bag-shaped member) 22A and an upper balloon (upper bag-shaped member) 22B, and is connected to the lower balloon (lower bag-shaped member) 22A and the upper balloon. Air can be supplied to the balloon (upper bag-like member) 22B.
Also, the balloon air supply pipe 23 is arranged along the longitudinal direction on the outer peripheral surface of the rod member 21 in this embodiment.

<Soil purification method>
Next, with reference to FIG. 15, the outline of the soil remediation method will be described.
15A and 15B are conceptual diagrams for explaining an example of the outline of the soil remediation method according to the first embodiment, FIG. 15(C) shows a state in which the pressurization chamber is formed in the cleaning agent injection device, FIG. 15(C) shows a state in which the pressure chamber is filled with the soil cleaning agent, and FIG. 15(D) shows a state in which the soil cleaning agent is injected. FIG. 15(E) shows the operation of moving the position of the main body of the cleaning agent injection device.
In FIG. 15, symbol G indicates the soil, symbol C indicates the oil-contaminated area in the soil, and symbol M1 indicates the soil remediation agent added with xanthan gum (thickener).

Soil G may include at least one of sand and gravel. For example, sand is stone with a grain size of 1/16 (0.0625) to 2 millimeters. Gravel is stone with a grain size of 2 millimeters or more.

(1) Confirmation of Contaminated Area First, a boring survey is conducted to investigate the degree of contamination depending on the position of the contaminated soil G, and the depth of the oil-contaminated soil area to which the soil decontamination agent should be injected is confirmed. Specifically, for example, the position (depth) of the aquifer formed in the soil near the groundwater table is confirmed.

(2) Installing the cleaning agent injection device Next, the cleaning agent injection device 100 is installed in the soil G as shown in FIG. 15(A).
Specifically, the slit 14H of the outer cylindrical member 10 is made to correspond to the vicinity of the confirmed groundwater level (not shown), etc., and is inserted into the soil G. do. Then, the cleaning agent supply nozzle 21H is aligned with the slit 14H, and the cleaning agent injection device main body 20 is arranged in the outer cylindrical member 10. As shown in FIG.

(3) Formation of purifying agent pressurizing chamber Next, as shown in FIG. The cleaning agent pressurizing chamber 100</b>P is formed in the cleaning agent injection device 100 by inflating and contacting and closely contacting the inner peripheral surface of the outer cylindrical member 10 .

(4) Soil cleaning agent supply Then, as shown in FIG. 15(C), the soil cleaning agent M1 is pressurized and supplied from the upper part of the hole formed inside the rod member 21 .
As a result, the supplied soil cleaning agent M1 is supplied to the cleaning agent pressurization chamber 100P through the cleaning agent supply nozzle 21H, and the cleaning agent pressurization chamber 100P is filled with the soil cleaning agent M1.

(5) Soil cleaning agent injection Subsequently, as shown in FIG. 15(D), when the soil cleaning agent M1 is pressurized and supplied to the rod member 21, the pressure of the soil cleaning agent M1 in the cleaning agent pressurization chamber 100P rises to expand the elastic cylindrical member 14 and form a gap in the slit 14H.
As a result, the soil cleaning agent M1 is injected into the soil G over the entire periphery of the cleaning agent injection device 100 through the slit 14H.
The injection of the soil remediation agent is completed by injecting the amount of the soil remediation agent M1 that is estimated to be required according to the contamination status.

As for the injection of the soil cleaning agent M1, it is preferable to inject the soil cleaning agent M1 near the groundwater level formed above the aquifer W formed in the soil G, as shown in FIG.
As shown in FIG. 17, the soil cleaning agent M1 injected into the soil G in this way has a low moving speed and an improved retention property. Compared with M0, the oils C that have accumulated in the vicinity of the groundwater table of the aquifer W for a long period of time can be efficiently purified over a long period of time. Here, the region of the two-dot chain line indicated by symbol M0 in FIG. 17 conceptually represents the area where the conventional soil decontamination agent moves.

(6) Change of Soil Cleaning Agent Injection Position Next, when the soil cleaning agent injection in the target soil cleaning area is completed, the slit 14H for injecting the same cleaning agent is moved to the next soil contaminated area.
Specifically, as shown in FIG. 15(E) , the air inside the balloon 22 is released, the balloon 22 is contracted, and the balloon 22 is separated from the inner peripheral surface of the pipe member 11 .
Next, the cleaning agent injection device main body 20 is moved vertically within the outer cylinder 10 as indicated by the arrow T, so that the lower balloon 22A and the upper balloon 22B are aligned with the soil-contaminated region into which the soil cleaning agent is to be injected next. They are arranged so as to sandwich the corresponding slit 14H.
Until the injection of the soil decontaminant into the target well is completed, the above (3) placement of the decontaminant injection device main body to the above (6) change of the soil decontaminant injection position are repeated.

According to the soil cleaning agent according to the first embodiment, by reducing the moving speed of the oil-degrading microorganisms (oil-degrading microorganisms) in the contaminated soil G, the residence time of the oil-degrading microorganisms is lengthened. be able to. As a result, oils contained in the contaminated soil G can be efficiently purified.

Further, according to the soil remediation agent according to the first embodiment, since the thickener is composed of xanthan gum (polysaccharide), the movement speed of the soil remediation agent M1 in the soil G is efficiently reduced, The retention time of the oil-degrading microorganisms can be lengthened.
Moreover, even if it is mixed with a microorganism-containing solution containing oil-degrading microorganisms, the activity of the oil-degrading microorganisms is not inhibited.

In addition, according to the soil remediation agent according to the first embodiment, since xanthan gum is dissolved in water to form a water-soluble thickened liquid, the xanthan gum can be easily mixed with the microorganism-containing solution. can dissolve large amounts of xanthan gum in

In addition, according to the soil decontaminant according to the first embodiment, since the oil-degrading microorganisms are gram-negative bacteria (for example, Japanese Patent No. 5715477), oils are efficiently decomposed and removed. be able to.

Moreover, according to the soil cleaning agent according to the first embodiment, since the viscosity is set to 50 (mPa·s), it is possible to greatly reduce the moving speed in the soil G and extend the residence time. As a result, oils can be efficiently decomposed and removed.

When the soil G contains at least one of sand and gravel, movement in the contaminated soil G is suppressed even for the soil G with relatively high permeability, and the contaminated soil G is thus efficiently purified. can do.

<Second embodiment>
Hereinafter, the soil cleaning agent according to the second embodiment of the present invention will be described.
[Soil cleaning agent]
The soil cleaning agent according to the second embodiment includes, for example, a microorganism-containing solution containing oil-degrading microorganisms having oil-degrading properties and nutrients for the activity of the oil-degrading microorganisms, and a microorganism-containing solution. and polyglutamic acid (PGA) (thickener) to increase viscosity.
The soil cleaning agent according to the second embodiment differs from the soil cleaning agent according to the first embodiment in that the thickener is composed of polyglutamic acid (PGA), which is an amino acid, instead of xanthan gum (polysaccharide). The point is that A thickener other than polyglutamic acid (PGA) may be used in combination. Others are the same as those of the first embodiment, so description thereof will be omitted.

[Polyglutamic acid (thickener)]
Polyglutamic acid (PGA) is a type of amino acid as described above.
In addition, the thickener and the solvent for dissolving the thickener, when mixed with the microorganism-containing solution, are mixed with oil-degrading microorganisms (oil-degrading microorganisms) in order to ensure the action as a soil remediation agent. It is necessary that the viscous agents do not interfere with each other to inhibit the soil remediation action of the soil remediation agent.
Specifically, it is necessary that the thickened liquid (thickener) does not kill the oil-degrading microorganisms and that the oil-degrading microorganisms do not inhibit the thickening action of the thickened liquid (thickener). .

Next, with reference to FIGS. 18 to 28, verification results regarding the feasibility of the soil remediation agent according to the second embodiment will be described. In the feasibility verification, (1) the effect of viscosity on the retention of oil-degrading microorganisms, (2) the effect of thickeners on oil-degrading microorganisms, and (3) oil-degrading microorganisms The effect on the thickener and (4) oil degradability of the soil remediation agent were confirmed.
Verifications (1) to (4) were performed by column tests and beaker tests as in the first embodiment.

(1) [Influence of viscosity on retention of oil-degrading microorganisms]
The effect of viscosity on the retention of oil-degrading microorganisms will be described below with reference to FIGS. 18 to 25. FIG.
18 to 25 are graphs illustrating the influence of viscosity on the retention of oil-degrading microorganisms, where the horizontal axis is the integrated flow rate (mL) of the eluent eluted from the column, and the vertical axis is the bacteria Body concentrations (×10 ⁵ cells/mL) are shown. The verification by the integrated flow rate and cell concentration shown in FIGS. 18 to 25 are the test results of the column test. The conditions in the column test are as follows.

[Column test conditions]
Column: 28 cm in height from the top to the beginning of the curve, 30 cm in height from the dropping bottom, and 3 cm in inner diameter.
Filler: crushed white gravel, 500 μm <particle diameter <1250 μm (equivalent to sand, particle size is determined using a sieve), 2000 μm <particle diameter <4000 μm (equivalent to gravel)
1) Comparative Example 1: Distilled water contains microbial activation nutrients and oil-degrading gram-negative bacteria 2) Invention Example 2: Distilled water contains microbial-activating nutrients and gram-negative oil-degrading microorganisms Addition of bacteria and polyglutamic acid (PGA) The concentration of oil-degrading microorganisms in the eluent in Comparative Example 1 and Example 2 of the present invention was 1.0 × 10 ⁷ cells / ml, and the amount of polyglutamic acid (PGA) added was 35 g/L.

Next, as shown in FIGS. 18 and 19, in Comparative Example 1, a high concentration of cells was rapidly eluted from the column in both sandy and gravel soils, and a thickening agent was added. In the case (Invention Example 2), bacterial cells were gently eluted from the column, and an improvement in retention of oil-degrading microorganisms was observed in both sand and gravel.

Next, with reference to FIGS. 20 to 25, the effect of viscosity on retention of oil-degrading microorganisms other than Gram-negative bacteria will be described. In Figures 20 to 25, the tests were performed with actinomycetes, Bacillus subtilis, and yeast as oil-degrading microorganisms, but the retention of oil-degrading microorganisms was improved in both sand and gravel for all microorganisms. was accepted.

[Beaker test conditions]
The beaker test was carried out by storing 250 ml of test solutions according to Comparative Examples 1, 2, and 2 of the present invention in a beaker, and adding 440 μl (concentration: 1500 mg/L) of light oil to each beaker. .
1) Comparative Example 1: Addition of microorganism-containing solution GHK-II to distilled water 2) Comparative Example 2: Distilled water 3) Invention Example 2: Addition of microorganism-containing solution GHK-II and polyglutamic acid (PGA) to distilled water The concentration of the microorganism-containing solution GHK-II in Comparative Example 1 and Invention Example 2 was 10 ml/L (100-fold dilution), and the amount of polyglutamic acid (PGA) added was 26 g/L.
Comparative Examples 1 and 2 are the same as those of the first embodiment.

(2) [Influence of thickener on oil-degrading microorganisms]
The effect of polyglutamic acid (PGA) (thickener) on oil-degrading microorganisms will be described below with reference to FIG.
FIG. 26 is a graph illustrating the effect of polyglutamic acid (PGA) (thickener) in the soil decontamination agent on oil-degrading microorganisms. The axis indicates the viable cell count (cfu/ml) of oil-degrading microorganisms.
Regarding the effect of the thickener on oil-degrading microorganisms, whether or not polyglutamic acid (PGA) (thickener) kills oil-degrading microorganisms was examined in Comparative Example 1 and Invention Example 2. Regarding, it was verified by the change in the number of viable oil-degrading microorganisms over the course of the treatment days after the start of the test.

As a result, as shown in FIG. 26, there was no significant difference in the number of viable bacteria over the course of treatment between Comparative Example 1 and Inventive Example 2. No impact was confirmed.

(3) [Effect of oil-degrading microorganisms on thickener]
Hereinafter, the influence of oil-degrading microorganisms on the thickener will be described with reference to FIG. FIG. 27 is a graph for explaining the effect of oil-degrading microorganisms in the soil remediation agent on polyglutamic acid (PGA). (mPa·s).
In the soil remediation agent, the effect of oil-degrading microorganisms on polyglutamic acid (PGA) is as follows. The change in viscosity was verified.

As a result, as shown in FIG. 27, in Example 2 of the present invention, it was confirmed that the viscosity did not significantly decrease with the lapse of treatment days.
Therefore, it was confirmed that oil-degrading microorganisms do not affect the viscosity of polyglutamic acid (PGA).

(4) [Oil degradability of soil decontamination agent]
Hereinafter, with reference to FIG. 28, the oil degradability of the soil cleaning agent will be described. FIG. 28 is a graph for explaining the oil decomposability of the soil decontaminant, in which the horizontal axis indicates the treatment days after the start of the test, and the vertical axis indicates the oil concentration (mg/L).
Regarding the oil decomposability of the soil detergency agent, in Comparative Examples 1 and 2 and Inventive Example 2, changes in oil concentration with the number of days after the start of the test were verified.

As a result, as shown in FIG. 28, in Comparative Example 2, the oil concentration hardly decreased. On the other hand, in Comparative Example 1 and Inventive Example 2, it was confirmed that the oil concentration decreased with the passage of treatment days, and that there was almost no difference between Comparative Example 1 and Inventive Example 2.
Therefore, it was confirmed that the soil decontamination agent according to Inventive Example 2 exhibited sufficient oil-decomposing properties.

According to the soil decontaminant according to the second embodiment, by reducing the movement speed of the oil-degrading microorganisms (oil-degrading microorganisms) in the contaminated soil G, the residence time of the oil-degrading microorganisms is lengthened. be able to. As a result, oils contained in the contaminated soil G can be efficiently purified.

Further, according to the soil remediation agent according to the second embodiment, since it is composed of polyglutamic acid (PGA) (amino acid), the movement speed of the soil remediation agent in the soil G is efficiently reduced, and the oil is removed. The residence time of degrading microorganisms can be lengthened.
Moreover, even if it is mixed with a microorganism-containing solution containing oil-degrading microorganisms, the activity of the oil-degrading microorganisms is not inhibited.

The technical matters described in the above embodiments are not limited to the above embodiments, and various changes can be made without departing from the scope of the invention.

For example, in the above embodiment, the case where the oil-degrading microorganism is a gram-negative bacterium (for example, Japanese Patent No. 5715477) was described, but the type of oil-degrading microorganism is limited to gram-negative bacteria. It is possible to arbitrarily set the target oils (e.g., mineral oils) within a range that can be decomposed without bacteria, actinomycetes, etc.), yeast, etc. may be arbitrarily set. Also, a plurality of oil-degrading microorganisms may be used in combination. That is, the oil-degrading microorganism may be at least one of Gram-negative bacteria, Gram-positive bacteria, and yeast.

Further, in the above embodiment, the case where the thickener is xanthan gum (polysaccharide) and polyglutamic acid (PGA) (amino acid) has been described, but the type of thickener is xanthan gum and polyglutamic acid (PGA). It can be arbitrarily set without being limited. For example, instead of xanthan gum and polyglutamic acid (PGA), polysaccharides other than xanthan gum, amino acids other than polyglutamic acid (PGA), proteins, glycerin, fucoidan, rubber, and the like may be used.

Further, in the above embodiment, the case where a thickened liquid containing a thickener is generated and mixed with a microorganism-containing solution to prepare a soil remediation agent has been described. A soil remediation agent may be prepared by directly mixing thickeners in the form of particles, particles, etc.).

Further, in the above-described embodiment, the case where the viscosity of the soil remediation agent is set to 50 (mPa s) has been described, but the viscosity of the soil remediation agent is not limited to 50 (mPa s) and can be any value. can be set to For example, it is preferable to set the viscosity in the range of 30 (mPa s) to 80 (mPa s), but the range of 20 (mPa s) to 80 (mPa s) or 10 (mPa s) mPa·s) or more and 80 (mPa·s) or less.
Moreover, the amount of the thickening agent to be added to the microorganism-containing solution can be set arbitrarily.

Further, in the above embodiment, the soil purification method using the double backer type cleaning agent injection device 100 has been described, but the soil purification method is not limited to the double backer type and can be arbitrarily set. Specifically, for example, an injection method such as a strainer well method, which is currently used for soil remediation and soil improvement, can be applied.

INDUSTRIAL APPLICABILITY According to the soil remediation agent and the soil remediation method according to the present invention, it is possible to reduce the movement speed of the soil remediation agent in the contaminated soil, and eventually to efficiently remediate soil contamination, so that it is industrially applicable. .

10 Outer cylinder member 14H Cleaning agent injection hole 20 Cleaning agent injection device body 21H Cleaning agent supply nozzle 22 Balloon (bag-shaped member)
22A lower balloon (lower bag-like member)
22B upper balloon (upper bag-like member)
100 cleaning agent injection device 100P cleaning agent pressurization chamber

Claims (10)

A soil remediation agent that is injected into contaminated soil to decompose and remove oils contained in the soil,
a microorganism-containing solution containing oil-degrading microorganisms having oil-degrading properties;
Nutrients for the activity of the oil-degrading microorganisms;
a thickening agent that increases the viscosity of the microorganism-containing solution;
A soil remediation agent characterized by comprising: The soil cleaning agent according to claim 1,
A soil cleaning agent, wherein the thickener contains a polysaccharide. The soil cleaning agent according to claim 2,
A soil cleaning agent, wherein the polysaccharide includes xanthan gum. The soil cleaning agent according to claim 1,
A soil cleaning agent, wherein the thickener contains an amino acid. The soil cleaning agent according to claim 4,
A soil cleaning agent, wherein the amino acid contains polyglutamic acid. The soil cleaning agent according to claim 1,
The soil cleaning agent, wherein the oil-degrading microorganism is at least one of Gram-negative bacteria, Gram-positive bacteria, and yeast. The soil remediation agent according to any one of claims 1 to 6,
A soil cleaning agent, wherein the thickening agent is dissolved in water to form a thickened liquid, and then mixed with the microorganism-containing solution. The soil remediation agent according to any one of claims 1 to 7,
A soil cleaning agent characterized by having a viscosity of 30 (mPa·s) or more. A soil remediation method for injecting a soil remediation agent into contaminated soil to decompose and remove oils contained in the contaminated soil,
Setting the depth direction position of the site to be injected with the cleaning agent into which the soil cleaning agent is injected in the contaminated soil,
arranging a cleaning agent injection hole of a soil cleaning agent injection device so as to correspond to the site to be injected with the cleaning agent,
A soil remediation method, comprising remediation of contaminated soil by injecting the soil remediation agent according to any one of claims 1 to 8 into a site to be injected with the remediation agent. The soil remediation method according to claim 9,
A soil remediation method, wherein the contaminated soil contains at least one of sand and gravel.

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