JP4255872B2 - Groundwater purification method and groundwater purification structure - Google Patents

Description

  The present invention relates to a groundwater purification method and a groundwater purification structure, and more particularly to a groundwater purification method and a groundwater purification structure for removing the contaminant from the groundwater contaminated with the contaminant and purifying the groundwater.

  Hazardous substances such as organochlorine compounds and heavy metals should be treated according to the prescribed legal standards, but in factories and commercial areas, pollutants accumulated over many years diffuse in the soil, May contaminate groundwater.

As a method for purifying groundwater contaminated with pollutants, conventionally, a method is known in which groundwater is pumped, detoxified with chemicals or microorganisms in a detoxification treatment plant, and then discharged (Patent Documents 1 and 2). ).
Japanese Patent Laid-Open No. 11-207373 Japanese Patent Laid-Open No. 11-647

However, according to such prior art, there is a problem that enormous costs for constructing and operating the processing plant are generated.
In addition, pumping up groundwater can cause ground subsidence, and depending on the amount of contaminated groundwater and the strength of the ground, it is often not an appropriate method.
Furthermore, when there is groundwater under the poorly permeable ground, there is a problem that it is difficult to pump up the groundwater.

  An object of the present invention is to provide a means for purifying contaminated groundwater more easily and inexpensively in view of the problems of the prior art.

In order to solve the above-mentioned problems, the groundwater purification method of the present invention comprises a columnar solidified body formed by mixing and stirring the soil, stabilizer and purification agent constituting the ground with respect to the ground through which the groundwater flows, and the solidification. A groundwater purification structure comprising a reinforcing layer that is partially formed by discharging a liquid material on the outer periphery of the body and that is harder than the solidified body is provided, and contaminants contained in the groundwater are removed by the solidified body. And

In addition, the groundwater purification structure of the present invention provided in the ground through which groundwater flows to remove contaminants contained in the groundwater was formed by mixing and stirring the soil, stabilizer and purification agent constituting the ground. It is characterized by comprising a columnar solidified body and a reinforcing layer harder than the solidified body, which is partially formed by discharging a liquid material on the outer periphery of the solidified body.

  The groundwater purification method and the groundwater purification structure according to the present invention are preferably characterized in that the reinforcing layer is formed at a predetermined interval with respect to the axial direction of the solidified body.

According to the groundwater purification method and the groundwater purification structure according to the present invention, since the reinforcing layer harder than the solidified body is partially formed on the outer periphery of the solidified body, the groundwater reaches the solidified body from the gap, Contaminants in the groundwater will be removed by the cleaning agent contained in the solidified body.
Further, since a reinforcing layer that is harder than the solidified body is partially formed on the outer periphery of the solidified body containing the purifier, the shape of the solidified body is easily retained by the reinforcing layer, and the surrounding ground is softened. Can be prevented.

  As described above, according to the groundwater purification method and the groundwater purification structure according to the present invention, the construction can be performed by a relatively simple means obtained by improving the conventional ground improvement method, and the operation cost or the like is increased after the construction. It is possible to purify groundwater at a low cost.

Hereinafter, the present invention will be described in detail with reference to the drawings.
FIG. 1 is a side view showing an embodiment of the groundwater purification structure 1, and FIG. 2 is a cross-sectional view of the groundwater purification structure 1.
As shown in FIGS. 1 and 2, the groundwater purification structure 1 of the present embodiment includes a columnar solidified body 2 formed by mixing and stirring the soil, stabilizer and purification agent constituting the ground, and the solidified body. The reinforcing layer 3 is partially formed on the outer periphery of the hardened body 2 and harder than the solidified body 2.

  The solidified body 2 is a cylindrical shape formed substantially vertically in the ground, and the diameter and length (depth) of the solidified body 2 are appropriately determined according to the position and amount of groundwater to be purified. Is set. Specifically, the diameter is 20 cm or more, preferably 50 to 200 cm.

  On the other hand, as shown in FIG. 1, the reinforcing layer 3 is partially formed on the outer peripheral portion of the solidified body 2 so that a part of the columnar solidified body 2 can be in direct contact with the outer ground. It is. As the shape of the reinforcing layer 3, for example, as shown in FIG. 1A, an annular reinforcing layer 3 is provided with an interval with respect to the axial direction of the solidified body 2, or FIG. As shown in FIG. 4, there can be mentioned those formed in a spiral shape that is coaxial with the solidified body 2.

  The thickness of the reinforcing layer 3 is usually 0.5 to 50 cm, preferably 2 to 20 cm, and the width of the reinforcing layer 3 when annular or spiral is usually 1 to 50 cm, preferably 5 to 20 cm. To do.

The reinforcing layer 3 may have a shape in which a part of the solidified body 2 can be in direct contact with the outer ground and the solidified body 2 can be reinforced so that the shape of the solidified body 2 can be easily maintained. For example, the shape is not limited to the above.
In addition, when the position where the groundwater to be purified flows is limited, only the area where the groundwater flows is formed at a predetermined interval as described above, and other portions, for example, below the groundwater vein or In the upper region, the reinforcing layer 3 may be formed so as to cover the entire solidified body 2, or the reinforcing layer 3 may not be formed.

  As the stabilizer for forming the solidified body 2, a conventional stabilizer used in the ground improvement method can be used. For example, a lime-based or cement-based chemical stabilizer can be used.

Moreover, an adsorbent or an insolubilizing agent can be used as the purifying agent. Examples of the adsorbent include clay minerals such as zeolite, activated carbon, and apatite. Examples of the insolubilizer include iron powder, iron (II) salts such as iron (II) sulfate, and sulfides such as sodium sulfide. Can be mentioned.
These cleaning agents and adsorbents may be used alone or in combination of two or more.

On the other hand, the material constituting the reinforcing layer 3 is not particularly limited as long as it can form the reinforcing layer 3 having strength higher than that of the solidified body 2. For example, not only the stabilizing material as described above but also the fiber High strength materials such as mixed cement mortar and polymer cement mortar, or rapid solidification materials such as bituminous materials and water glass materials can be used.
Moreover, when actually using these, it is preferable to use in a liquid state.

  The material for forming the solidified body 2 and the reinforcing layer 3 is not limited to those described above, and is appropriately selected according to the soil quality of the ground, the amount of groundwater, the type of contaminant, the size of the groundwater purification structure to be installed, etc. Or can be used in combination with other materials.

Next, a method for forming the groundwater purification structure 1 will be described.
The groundwater purification structure 1 first discharges a stabilizer and a purifying agent while excavating the ground, and mixes and stirs the stabilizer, the purifying agent, and the excavated soil to form a columnar solidified body 2 in the excavation part. Form. Thereafter, the stabilizer or other material is discharged to the inside of the solidified body 2 in the vicinity of the outer periphery, and the reinforcing layer 3 having an annular shape or a spiral shape as described above is formed in the vicinity of the outer periphery of the solidified body 2. To do.

FIG. 3 is a perspective view showing a tip portion of the rotating shaft 11 of the construction apparatus used for forming the groundwater purification structure 1.
The rotary shaft 11 is attached to the lower part of a drive device main body (not shown) so as to be able to rotate forward and backward. A drill bit 12 is fixed to the lower end of the rotary shaft 11, and a drilling blade is provided near the upper part of the drill bit 12. 13 and the stirring blade 14 are fixed. The perforated bit 12 is formed of a tapered plate-like body, and rotates together with the rotary shaft 11 when the rotary shaft 11 is driven to make a hole in the ground. Further, the excavation blade 13 and the stirring blade 14 are both formed by a rectangular plate-like body extending in the horizontal direction, and an uneven excavation blade 15 is formed at the lower end portion of the excavation blade 13 in particular.
The excavating blade 13 and the stirring blade 14 are fixed to the rotating shaft 11 with the same elevation angle in accordance with the rotation of the rotating shaft 11 in the positive direction. The stirring blades 14 are provided in multiple stages in the vertical direction of the rotating shaft 11 and are arranged at an angle of 90 degrees with respect to each other.

Further, in the apparatus, a first discharge hole 16 is provided in the rotary shaft 11 in the vicinity of the excavation blade 13, and a conduit disposed on the back side of the excavation blade 13 is provided at the tip of the excavation blade 13. A second discharge hole 17 led to 18 is provided.
These discharge holes 16 and 17 are respectively connected to two supply passages formed inside the rotary shaft 11. The stabilizer and the purifying agent are mainly supplied from the supply path connected to the discharge hole 16 and discharged from the discharge hole 16. On the other hand, the stabilizing material is mainly supplied from the supply passage connected to the discharge hole 17 and is discharged from the discharge hole 17.

  The state at the time of forming the groundwater purification structure 1 using the apparatus which consists of the said structure is shown in FIG.4 and FIG.5. First, when forming the columnar solidified body 2, as shown in FIG. 4, the rotating shaft 11 is rotated in the forward direction to make a hole in the ground with the drill bit 12, and the excavating blade 13 gradually digs. Simultaneously with this excavation, a chemical stabilizer such as lime-based or cement-based and a purifying agent are discharged from the first discharge hole 16 provided in the rotary shaft 11, and the soil and stabilizer excavated by the stirring blade 14 are discharged. The solidified body 2 is formed at the excavation site by sufficiently mixing and stirring.

  Next, it is confirmed that the digging has progressed to a predetermined depth, the supply of the stabilizer and the purifying agent from the first discharge hole 16 is stopped, and the rotary shaft 11 is pulled up while being reversely rotated as shown in FIG. . At the same time, a stabilizer or other material is supplied from the second discharge hole 17 provided at the tip of the excavating blade 13.

  For example, when the annular reinforcing layer 3 as shown in FIG. 1A is formed, the pulling up of the rotating shaft 11 is temporarily stopped while the rotating shaft 11 is rotated in the reverse direction, and the second discharge hole 17 is formed. An annular reinforcing layer 3 is formed by supplying a stabilizer or the like. Then, the supply of the stabilizer or the like is stopped, the lifting of the rotating shaft 11 is restarted, and the above procedure is repeated, whereby the annular reinforcing layer 3 can be formed at a predetermined interval.

  When forming the spiral reinforcing layer 3 as shown in FIG. 1B, the rotating shaft 11 is pulled up at a constant speed while rotating in the reverse direction, and at the same time, a stabilizer or other material is continuously supplied from the discharge hole 17. Supply. And the spiral reinforcement layer 3 which has a predetermined pitch and width | variety can be formed by adjusting the distance pulled up while the discharge hole 17 rotates once, and the quantity of the stabilizer etc. which discharge.

The groundwater purification structure 1 of the present invention is provided in the ground through which groundwater flows. Therefore, a stabilizer and a purification agent will be dissipated with the flow of groundwater only by adding a purification agent in the solidified body formed by a general ground improvement construction method. Moreover, if the solidified body is dissipated, the soil portion may be disturbed and the ground may be weakened. If a large number of such solidified bodies are provided, the surrounding ground will be adversely affected.
On the other hand, the groundwater purification structure 1 of the present invention has a structure in which a solidified body 2 containing a purifying agent is formed in the central portion and a reinforcing layer 3 is partially formed on the outer peripheral portion of the solidified body 2. Therefore, the surface of the solidified body 2 is protected until the internal solidified body 2 is sufficiently cured, and even after the solidified body 2 is cured, it is possible to prevent dissipation of the stabilizer and the purifier due to groundwater. Therefore, even if a large number of such groundwater purification structures are installed, the ground is not easily softened, and it is difficult to adversely affect the surrounding ground.

  It is preferable to install a plurality of such groundwater purification structures 1 on the ground through which the groundwater to be purified flows. As the arrangement of the groundwater purification structure 1, for example, as shown in FIG. 6A, the groundwater purification structure 1 is arranged so as to be evenly distributed in a predetermined region, or as shown in FIG. The case where it arrange | positions so that it may distribute at equal intervals on the circular arc centering on the upstream with respect to the flow direction.

  When the groundwater purification structure 1 having such a structure is installed in the ground, the groundwater containing the pollutant flows into the solidified body 2 from the gap of the reinforcing layer 3, and the pollutant is removed by adsorption or insolubilized by the purifier. Can purify groundwater.

  In the above-described embodiment, the case where the purification agent for purifying the groundwater is contained only in the solidified body has been described. If it is within the possible range, a purifying agent may be contained in the reinforcing layer.

Side surface sectional drawing which showed embodiment of the groundwater purification structure which concerns on this invention. The plane sectional view showing the embodiment of the groundwater purification structure concerning the present invention. The perspective view which showed an example of the apparatus used when installing a groundwater purification structure. Side surface sectional drawing explaining the procedure which installs a groundwater purification structure. Side surface sectional drawing explaining the procedure which installs a groundwater purification structure. The top view which illustrated arrangement of a groundwater purification structure.

Explanation of symbols

1 Groundwater purification structure 2 Solidified body 3 Reinforcement layer

Claims (4)

For ground where groundwater flows
A columnar solidified body formed by mixing and stirring the soil, stabilizer and purification agent constituting the ground, and partially formed by discharging a liquid material around the solidified body and being harder than the solidified body A groundwater purification method comprising: providing a groundwater purification structure comprising a reinforcing layer, and removing contaminants contained in groundwater by the solidified body.   The groundwater purification method according to claim 1, wherein the reinforcing layer is formed at a predetermined interval with respect to the axial direction of the solidified body. A groundwater purification structure provided in ground where groundwater flows to remove contaminants contained in groundwater,
A columnar solidified body formed by mixing and stirring the soil, stabilizer and purifying agent constituting the ground, and the solidified body partially formed by discharging a liquid material to the outer periphery of the solidified body A groundwater purification structure characterized by comprising a hard reinforcing layer.   The groundwater purification structure according to claim 3, wherein the reinforcing layer is formed at a predetermined interval with respect to the axial direction of the solidified body.

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