JP2000061442A - Method for cleaning soil and groundwater using granular cleaning material and its equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce and decompose contaminants with iron powder by using a granular cleaning material and widely sprinkling the cleaning material in a horizontal channel over a long distance. SOLUTION: At least one horizontal channel 8 is dug below a contaminated zone C, and then a granular purifying material 6 is incorporated into a semifluid body 7. The semifluid body 7 contg. the granular purifying material is forcedly poured into the horizontal channel 8 from an opening 5 of the channel 8 to widely sprinkle the granular purifying material in the channel 8. Otherwise, iron powder 6 is incorporated into a slurry ice water 13, and the slurry ice water 13 is forcedly poured into the horizontal well channel 8 from the opening 5 of the well channel 8.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying soil and groundwater using granular purification substances such as iron powder and its equipment, and more specifically, in the plating industry, dry cleaning industry, semiconductor industry, etc. The present invention relates to a soil / groundwater purification method and equipment for purifying soil / groundwater pollution generated by widely used chlorine-based volatile organic compounds such as trichlorethylene and tetrachloroethylene.

[0002]

2. Description of the Related Art Chlorine-based volatile organic compounds such as trichloroethylene and tetrachloroethylene are widely used in the semiconductor industry, plating industry, cleaning industry, etc., because they are rich in degreasing property. Then, these chlorine-based organic compounds permeate the soil to contaminate the soil and groundwater.

When this contaminated groundwater is used as drinking water, these chlorine-based volatile organic compounds act as carcinogens that induce cancer in the human body. Other heavy metals such as cadmium, lead, mercury, hexavalent chromium, and C
OD also pollutes the soil, causing various problems. As a method for purifying contaminated soil / ground water, a soil suction method, a pumping treatment method, bioremediation, a thermal desorption method, a thermal decomposition method, etc. have been conventionally performed.

[0004]

By the way, the above-mentioned conventional soil and groundwater purification methods have limited implementation conditions, and if the effect is judged in consideration of cost and treatment period, the purification effect depends on the situation of the polluted site. There were variations. Therefore, development of a purification technology that can decompose pollutants such as chlorine-based volatile organic compounds in-situ is required.

However, in order to decompose pollutants such as chlorine-based volatile organic compounds in-situ, it is necessary to spray a purification substance according to the size of the contamination zone. Since a trench and an underdrain were formed in this way and a purification substance was placed in this, it was extremely expensive. Moreover, in the case where there is a wide range of polluted zones, it is necessary to send purification substances into the ground in a wide range, but this is limited, and it is difficult to sufficiently prevent soil and groundwater pollution. Establishing effective soil and groundwater purification measures was an urgent issue. By the way, recently, purification has come to be performed by an iron powder method in which a chlorine-based volatile organic compound is decomposed in an aqueous solution of a granular purification substance such as iron powder. In this case, it has been practiced to inject a granular purification substance using a vertical well, or to pump groundwater and then mix the granular purification substance for purification. However, in vertical wells, iron powder could only be mixed with a small amount of groundwater. Moreover, the trench and the underdrain cannot be installed under the building or the tank, and it is difficult to construct the deep trench.

The object of the present invention is to solve the above-mentioned conventional problems, and by using a granular purification substance, and further by spreading the granular purification substance over a horizontal well hole over a long distance, It is an object of the present invention to provide a soil / groundwater purification method and equipment for reducing and decomposing pollutants by granular purification substances.

[0007]

The present invention was made based on the finding that it is possible to perform in-situ decomposition treatment of pollutants such as chlorine-based volatile organic compounds in an aqueous solution with a granular purification substance such as iron powder. A method for purifying soil and groundwater using a granular purifying substance and its equipment, which are configured as follows in order to solve the above-mentioned technical problems.

That is, in the method for purifying soil / ground water using the granular purification substance of the present invention, at least one horizontal well hole is drilled below the contaminated zone, and then the granular purification substance is contained in the semi-fluid body, A semi-fluid containing the granular purification material is forcibly injected into the horizontal well hole from the opening of the horizontal well hole to reduce and decompose harmful substances such as chlorine-based organic compounds that permeate into soil and groundwater. It is characterized (Claim 1).

Iron powder is preferable as the particulate purification substance. Besides, silicon or the like can be used. Normally, the horizontal well hole may be left excavated, but if the soil tends to collapse, the horizontal well hole may be formed by inserting a tubular well material with a large number of holes into the horizontal well hole. It is also possible to prevent the collapse of the well hole.

Further, the semi-fluid body is a fluid having a high viscosity at first, but the viscosity becomes smaller with the lapse of time and becomes a water state so that it is not dissolved in the ground water, and iron powder which is a purification substance, It is preferable to use a gel-like substance, such as a polymer which is a muddy water material, or a jelly-like substance, in which only the purification substance mainly containing iron powder remains in the well.

Further, in the method for purifying soil / ground water using the granular purification substance of the present invention, at least one horizontal well hole is drilled below the contaminated zone, and then the granular purification substance is contained in slurry ice water. , Forcibly injecting the granular purification substance contained in the ice water into the horizontal well hole from the opening of the horizontal well hole to reduce harmful substances such as chlorine-based volatile organic compounds that permeate into soil and groundwater It is characterized in that it is decomposed (claim 2).

The ice water in the form of slurry is produced by freezing organic brine, which is an aqueous solution of a dihydric alcohol such as ethylene glycol or propylene glycol, and precipitating ice as the freezing progresses. Is preferably used. However, it goes without saying that an aqueous solution of salt can be used.

The present invention is a soil / groundwater purification facility using a granular purification substance, and is configured as follows in order to solve the above-mentioned technical problems. That is, at least one horizontal well hole excavated below the polluted zone and a granular purification substance sprinkled in the horizontal well hole are provided, and harmful substances such as chlorine-based volatile organic compounds that permeate soil and groundwater. Is reducible and decomposable (claim 3).

[0014]

[Operation] According to the method for purifying soil and groundwater using the granular purification substance of the present invention and the equipment therefor, the granular purification substance such as iron powder is a chlorinated volatile organic compound in situ in the aqueous solution in soil and groundwater. Perform disassembly processing. Furthermore, by mixing a reducing agent with the particulate purification substance, the decomposition treatment of pollutants such as chlorine-based volatile organic compounds is promoted.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a soil / groundwater purification facility using the granular purification material of the present invention will be described in more detail with reference to the embodiments shown in the drawings. However, unless otherwise specified, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment are not intended to limit the scope of the present invention thereto, It is just an example of explanation.

(First Embodiment) FIG. 1 is an explanatory view showing an excavated state of a horizontal well hole according to an embodiment of the present invention.
Shows an outline of a soil / groundwater purification facility using iron powder according to the first embodiment. Further, FIG. 5 shows a cross section of the horizontal well hole of this embodiment.

First, in order to excavate a horizontal well hole, small pits are formed at both ends below a contaminated zone C by a chlorine-based volatile organic compound, trichlorethylene, at predetermined intervals as shown in FIG. One is called a penetration pit 1 and the other is a reaching pit 2. Next, the drill 4 which is a drilling tool is attached to the tip of the rod 3, and the power unit track 25 which is a drive source is driven to move the rod 3 into the drill unit 16.
The guide 4 is rotated while being guided, and the drill 4 is rotationally driven toward the water table WL. Then, the drill 4 excavates the aquifer in the underground E in a substantially horizontal direction while rotating. When the drill 4 reaches the reaching pit 2, the rotation of the drill is stopped and the excavation is completed.

Then, the drill 4 is removed from the rod 3 at the reaching pit 2, the penetration pit 1 and the reaching pit 2 are backfilled, and a horizontal well 8 having an opening 5 at one end and the other end closed as shown in the figure is formed. To construct. The horizontal wells 8 are arranged in parallel at a plurality of places according to the size of the contamination zone C as shown in FIG.

In the present embodiment, iron powder was used as the particulate purification substance. The iron powder may have the composition and physical properties shown in Table 1, but in the present embodiment, Among them, iron powder E-200 manufactured by Dowa Iron Powder Co., Ltd. having the largest surface area was used. In addition, DE, DNC
-240 is iron powder manufactured by Dowa Iron Powder Co., Ltd., and cast iron powder is manufactured by Wako Pure Chemical Industries, Ltd.

[0020]

[Table 1]

Then, as shown in FIG.
Polymer 7 (trade name: BioBore), which is a muddy water material as a semi-fluid, is included in the horizontal well hole 8 as shown by an arrow from the opening 5 (shown in an exaggerated manner in the figure).
Pressed in. Further, a high pressure is applied to the polymer 7 containing the iron powder 6 by using the rotary pump P to press the iron powder from the container 15 into the horizontal well hole.

Then, since the polymer 7 containing the iron powder 6 is a substance having a strong viscosity at the beginning, the iron powder 6 is not flowed in the horizontal well hole 8 from the end of the horizontal well hole 8 to the other end thereof. It flows and conveys the iron powder 6 to the back of the well hole. Therefore, iron powder 6
Has been widely spread in the well hole.

Then, the polymer 7 becomes water-like with the passage of time and is not dissolved in the groundwater, and only the iron powder 6 remains in the well hole 8. As a result, iron powder 6
Decompresses trichlorethylene contained in gravity water that penetrates underground E through pollution zone C, and the concentration of trichlorethylene (TCE) will decrease exponentially with time. Contamination is prevented.

(Second Embodiment) FIG. 3 shows a second embodiment of the present invention.
It is a schematic diagram showing a state of excavation of a horizontal well hole of the embodiment. 5 shows a cross section of the horizontal well hole of this embodiment. In order to excavate the horizontal well 81, small pits are bored at both ends of a predetermined section as shown in FIG. 1 so that one is a penetration pit 1 and the other is a reaching pit 2. Next, the drill 4 is attached to the tip of the rod 3, the power unit track 25 is driven, the rod 3 is rotated while being guided by the drill unit 16, and the drill 4 is rotationally driven toward the water table WL. Then, the drill 4 rotates E
The aquifer is dug in a substantially horizontal direction. Drill 4 reached 2
Then, the rotation is stopped and the horizontal well hole 81 is excavated.

Then, a reamer (not shown) for expanding a hole is attached to the tip of the rod 3 in the direction opposite to the drill 4, and a cylindrical well material 9 is attached to the rear of the reamer to rotate the rod 3. While rotating the reamer by driving, the tubular well material 9 provided with a large number of holes is pulled by pulling the rod 3 in the direction opposite to the drilling direction of the well holes (from the right side to the left side in FIG. 1). The material 9 is inserted into the well hole 81.

Then, the penetration pit 1 and the reaching pit 2 are backfilled,
As shown in FIG. 3, a horizontal well hole 81 having a pair of openings 5a and 5b communicating with the horizontal well hole 81 is constructed. In addition,
The horizontal wells 81 are also arranged in parallel at a plurality of places depending on the size of the contamination zone C as shown in FIG.

Also in this embodiment, E-200 having the largest specific surface area among the iron powders shown in Table 1 is used as the iron powder 6 as the granular purification substance. Then, this iron powder is powdered sodium bisulfite (NaHS) which is a weakly acidic reducing substance.
Mix with O3). The mixed iron powder is mixed with brine, which is an aqueous solution of ethylene glycol, and then charged into the ice maker 10. In the ice making machine 10, brine precipitates ice containing iron powder as freezing progresses, and ice water 13 in the form of a slurry is generated.

Ice 12 containing iron powder produced as described above
The ice water 13 in the form of slurry is sent to the heat storage layer 11, is further pressurized by the pump P, and is sent to the horizontal well hole 81 under pressure. Therefore, the slurry ice water flows in the well and deeply flows into the horizontal well hole 8. The ice gradually melts with the passage of time and melts into the groundwater, after which iron powder 6
Remain in the horizontal well hole 81, and are spread over a wide area.

Further, iron powder as a granular purification substance is a weakly acidic reducing substance such as sodium bisulfite (NaHSO).
Since 3) is mixed, it is not passivated by iron oxide due to the presence of dissolved oxygen DO in the aqueous solution or iron hydroxide in the basic region. For this reason, the decomposition reaction of pollutants such as trichlorethylene and tetrachloroethylene is not blocked, the reductive decomposition reaction of chlorine-based volatile organic compounds by the iron powder is promoted, and the soil and groundwater are efficiently purified. .

(Third Embodiment) FIG. 4 shows a cross section of the present embodiment, in which the same well hole as that of the first embodiment is constructed above the water table WL. Therefore, in the present embodiment, the method of excavating the horizontal well hole 8 is the same as that of the first embodiment, and therefore the description of the excavation method is omitted.
Of the iron powders shown in Table 1, E-200 was used and a low-basic reducing agent, sodium sulfite (Na2 2 SO3), was used.
To mix.

Next, the iron powder 6 as a granular purification substance was contained in the jelly-like semi-fluid body 71 as a semi-fluid body, and was pressed into the horizontal well hole 8 from the opening 5 as shown by the arrow. Further, a high pressure is applied to the jelly-like semi-fluid 71 containing the iron powder 6 by using the rotary pump P, and the jelly-like semi-fluid 71 is pressed into the horizontal well hole 8 from the container 15.

The jelly 71 containing the iron powder 6 is a substance having a strong viscosity at first, but the iron powder 6 does not flow in the horizontal well hole 8 but flows from the end of the horizontal well 8 to the other end thereof. Carry iron powder 6. Therefore, the iron powder 6 is widely spread in the well holes.

Then, the jelly 71 becomes water-like with the passage of time and does not dissolve in the groundwater, and only the iron powder 6 remains in the well hole 8. As a result, the iron powder 6 reductively decomposes tetrachloroethylene contained in gravity water that permeates the ground E through the pollution zone C.

[0034]

As described above, according to the soil / groundwater purification method and the equipment using the granular purification material of the present invention, the purification ability for soil / groundwater contamination by chlorine-based volatile organic compounds, etc. A certain iron powder can be spread over a wide area in a horizontal well hole by a semi-fluid or slurry ice water, so that pollutants such as chlorine-based volatile organic compounds are widely captured and reductive decomposition reaction is performed. . Moreover, the reductive decomposition of harmful substances is further promoted by mixing iron powder, which is a granular purification substance, with a reducing agent such as sodium sulfite or sodium bisulfite.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an excavated state of a horizontal well hole according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a soil / groundwater purification facility according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram of a soil / groundwater purification facility according to a second embodiment of the present invention.

FIG. 4 is a schematic diagram of a soil / groundwater purification facility according to a third embodiment of the present invention.

FIG. 5 is a cross-sectional view of the soil purification equipment of each embodiment.

[Explanation of symbols]

5, 5a, 5b openings 6 Iron powder (granular purification substance) 7 Semi-fluid (polymer) 8 horizontal well holes 13 Slurry ice water C pollution zone

Claims (3)

[Claims] 1. At least one horizontal well hole is drilled below the contaminated zone, and then the particulate purification material is contained in a semi-fluid, and the semi-fluid containing the particulate purification material is opened in the opening of the horizontal well hole. A method for purifying soil / groundwater using a granular purifying substance, which comprises forcibly injecting into the horizontal well hole to reduce and decompose harmful substances such as chlorine-based organic compounds that permeate into soil and groundwater. 2. At least one horizontal well hole is drilled below the contaminated zone, and then the granular purification material is contained in slurry ice water, and the granular purification material contained in the ice water is contained in the horizontal well hole. Soil and groundwater using granular purification substances characterized by reducing and decomposing harmful substances such as chlorine-based volatile organic compounds that permeate into soil and groundwater by forcibly injecting into the horizontal well hole from the opening Purification method. 3. A chlorine-based volatile organic compound, etc., which comprises at least one horizontal well hole excavated below the contaminated zone and a granular purification substance sprinkled in the horizontal well hole, and which permeates soil and groundwater. Soil / groundwater purification equipment using granular purification substances, which is capable of reducing and decomposing the harmful substances of.