JP6914026B2 - Soil purification system - Google Patents

Description

The present invention relates to a soil purification system.

Patent Document 1 below discloses a method for purifying contaminated soil by adding a microbial nutrient that decomposes pollutants to the groundwater pumped from a pumping well and allowing the groundwater to permeate the contaminated soil from the water injection well. ..

Japanese Unexamined Patent Publication No. 2015-160175

In the method for purifying contaminated soil of Patent Document 1, in order to allow groundwater to which a nutrient is added to permeate into the contaminated soil from the water injection well, the nutrients are evenly applied to the portion where the water permeability of the soil is low and the portion where the groundwater level is low. It is difficult to infiltrate the injection solution).

In view of the above facts, an object of the present invention is to provide a soil purification system capable of evenly infiltrating the injection liquid into the soil.

The soil purification system according to claim 1 is a water injection layer provided on the surface of the soil or in the soil, which is a material having a higher water permeability than the soil and is formed in a planar shape over the entire range covering the pollutants contained in the soil. When the said contaminants by injecting an infusion liquid containing a substance for decomposing the water injection layer, and injection equipment to infiltrate injectate into the soil from the water injection layer, ground water containing the infusion fluid from the soil Has a pumping facility and a pumping facility.

In the soil purification system of claim 1, since the injection liquid is injected into the water injection layer having a higher water permeability than the soil, the injection liquid easily penetrates into the water injection layer faster than it penetrates into the soil. Since this water injection layer is formed in a planar shape, the injection liquid permeates the soil from the water injection layer toward the pumping facility by forming a surface. Therefore, as compared with the case where the injection liquid is permeated into the soil from, for example, a rod-shaped (linear) water injection well, the injection liquid can be easily permeated into the soil evenly.

In the soil purification system of claim 2, the water injection layer is provided on the surface of the soil, and the pumping facility is a pumping well.

In the soil purification system of claim 2, since the water injection layer is provided on the surface of the soil, the injection liquid permeates the soil by gravity. Therefore, a water injection well for permeating the injection liquid is not required. In addition, since the pumping equipment is a pumping well, water can be pumped from a deep position in the soil. Therefore, the penetration of the injection liquid by gravity can be promoted.

The soil purification system according to claim 3 is provided with a water blocking wall on the outer peripheral portion of the water injection layer.

In the soil purification system of claim 3, since the water blocking wall is provided on the outer peripheral portion of the water injection layer, it is difficult for the injection liquid injected into the water injection layer to flow out to the outside of the water injection layer. Therefore, it is possible to suppress the flow of the injection liquid to the portion where the injection liquid does not need to permeate, and the soil purification efficiency is high.
In the soil purification system of claim 4, the water injection layer is laid without excavating the soil.
In the soil purification system of claim 5, the water injection layer is composed of a plurality of layers, and the upper layer has a larger hydraulic conductivity than the lower layer.
The soil purification system according to claim 6 is provided with a purification device capable of heating the injection liquid, and the water injection layer is provided with a recovery pipe for collecting a part of the injection liquid injected into the water injection layer. ing.
In the soil purification system of claim 7, a coating layer is provided above the water injection layer.

According to the soil purification system according to the present invention, the injection liquid can be evenly permeated into the soil.

It is a vertical cross-sectional view which shows the soil purification system which concerns on 1st Embodiment of this invention. It is a partially enlarged vertical sectional view which shows the structure of the water injection layer in the soil purification system which concerns on 1st Embodiment of this invention. It is a partially enlarged vertical sectional view which shows the example which the surface of the soil is inclined in the soil purification system which concerns on 1st Embodiment of this invention. (A) is a vertical sectional view showing a procedure for purifying soil using the soil purification system according to the first embodiment of the present invention, showing a state in which a soil purification system is constructed on top of contaminated soil, and (B). ) Indicates the state in which groundwater is pumped from the pumping well, (C) indicates the state in which the injection liquid is injected from the purification device into the water injection layer, and (D) indicates the state in which the injection liquid is continuously injected from the purification device into the water injection layer, and the soil is ground. (E) indicates a state in which the injection solution has permeated into the soil, (E) indicates a state in which the injection solution has stopped injecting the injection solution, and the injection solution has penetrated into the soil by gravity, and (F) indicates a state in which the injection solution has penetrated into the soil. It shows the later state. It is a vertical cross-sectional view which shows the soil purification system which concerns on 2nd Embodiment of this invention. (A) is a plan view showing the positional relationship between the water injection well and the pumping well and the water injection layer in the soil purification system according to the third embodiment of the present invention, and (B) is a vertical sectional view. (A) is a vertical cross-sectional view showing a method of forming a water injection layer in the soil purification system according to the third embodiment of the present invention, showing a state in which a pit is drilled in the ground, and (B) is from the pit to the ground. A state in which a notch is formed is shown, (C) shows a state in which the notch is cut to form a planar flow path, and (D) shows a state in which the flow path is filled with silica sand to form a planar water injection layer. Shows the state of (A) is a vertical cross-sectional view showing a state in which a plurality of vertical holes are drilled in the ground and water injection layers formed from the respective vertical holes are connected in the soil purification system according to the third embodiment of the present invention. (B) Is a plan view. It is a perspective view which shows the soil purification system which concerns on 4th Embodiment of this invention.

[First Embodiment]
(Soil purification system)
As shown in FIG. 1, in the soil purification system 10 according to the first embodiment, the injection liquid is injected into the water injection layer 20 provided on the surface of the soil G and the water injection layer 20, and the injection liquid is injected from the water injection layer 20 to the soil G. It is provided with an injection facility 30 for permeating the injection solution and a pumping well 40 as a pumping facility for pumping groundwater containing the injection solution from the soil G.

(Injection equipment)
The injection equipment 30 includes a purification device 32 that generates an injection liquid for injecting into the water injection layer 20, an injection pipe 34 that injects the injection liquid generated by the purification device 32 into the water injection layer 20, and before permeating into the soil G. A recovery pipe 36 for collecting a part of the injection liquid of the above is provided. The injection liquid is a liquid containing a substance (decomposing substance) for decomposing the pollutant E contained in the soil G.

The purification device 32 purifies the groundwater pumped from the pumping well 40, and adds a decomposing substance to the purified groundwater. As the decomposing substance, a "degrading microorganism" that biodegrades the pollutant E, a "chemical decomposing agent" that chemically decomposes the pollutant E, an "activator" that activates the biodegradation of the degrading microorganism, and the like can be used.

Further, the purification device 32 heats the injection liquid to promote the action of these decomposing substances.

The injection pipe 34 and the recovery pipe 36 are perforated pipes laid inside the water injection layer 20, and the injection liquid is distributed from the purification device 32 to the injection pipe 34 by using a pump (not shown), and from the recovery pipe 36. The injection liquid is collected in the purification device 32 by using a pump (not shown).

The recovery pipe 36 is used to collect the injection liquid injected into the water injection layer 20 and reheat the injection liquid when the temperature of the injection liquid becomes lower than a predetermined temperature before permeating into the soil G. , It is not always necessary to provide it.

The amount of water distributed to the injection pipe 34 and the amount of water recovered from the recovery pipe 36 are controlled by a control unit (not shown) provided in the purification device 32. The control unit also receives a signal from a weighing sensor (not shown) and controls the amount of groundwater pumped from the pumping well 40.

(Water injection layer)
The water injection layer 20 is formed of a material having a higher water permeability than the soil G, and is laid in a plane on the ground surface of the soil G in a range covering the pollutant E to be purified. A water blocking wall 50 made of a non-permeable material is provided around the water injection layer 20, making it difficult for the injection liquid injected into the water injection layer 20 to flow out of the water injection layer 20.

As shown in FIG. 2, the water injection layer 20 has a three-layer structure, the upper layer 22 is formed of crushed stone, the middle layer 24 is formed of gravel, and the lower layer 26 is formed of silica sand. Since these particle sizes decrease in the order of crushed stone, gravel, and silica sand, the hydraulic conductivity increases in the order of upper layer 22, middle layer 24, and lower layer 26.

The injection pipe 34 is embedded inside the upper layer 22, and the injection liquid injected into the upper layer 22 rapidly permeates laterally inside the upper layer 22, gradually permeates into the middle layer 24 by gravity, and further penetrates into the lower layer 24. Penetrate to 26.

The structure of the water injection layer 20 is not limited to this, and may be a structure of two or less layers or a structure of four or more layers. The material for forming the water injection layer 20 includes porous concrete, open cell urethane foam, a molded product obtained by molding fibrous or mesh-like polyethylene into a mat shape, and a composite material in which a non-woven fabric is attached to the surface thereof. Can be used. Impurities (biofilm, etc.) can be filtered by attaching the non-woven fabric. When a resin material such as urethane foam or polyethylene is used as the material for forming the water injection layer 20, the density of the resin material in the upper layer is made smaller than that in the middle layer and the lower layer.

Further, in the present embodiment, the ground surface of the soil G is a substantially horizontal plane, and the water injection layer 20 is also laid substantially horizontally, but the embodiment of the present invention is not limited to this. For example, when there is a slope on the ground surface as shown in FIG. 3, a water injection layer 28 may be formed along the slope. In such a water injection layer 28, the injected liquid flows along a gradient, so that the injection liquid permeates into the water injection layer 28 as compared with the horizontally laid water injection layer 20 (see FIG. 1). Cheap. Therefore, the pitch of the injection pipe 34 can be increased. By increasing the pitch of the injection pipe 34, it is possible to reduce the construction work.

The slope of the ground surface of the soil G may be created and provided, or a pre-installed slope may be used.

Further, in the present embodiment, the injection liquid is injected from the injection pipe 34 into the water injection layer 20, but the embodiment of the present invention is not limited to this. For example, the injection liquid may be sprayed on the water injection layer 20 by installing a sprinkler on the water injection layer 20 or using a hose on hand.

(Pump well)
As shown in FIG. 1, the pumping well 40 is a steel pipe having a strainer 42 at its tip, and has a pump (not shown) inside. The strainer 42 is arranged at a position deeper than the pollutant E to be purified, whereby the pumping well 40 can pump groundwater from a position deeper than the pollutant E.

(Action and effect)
The operation and effect of the soil purification system 10 according to the first embodiment will be described together with the soil G purification method. In order to purify the soil G using the soil purification system 10 according to the first embodiment, first, as shown in FIG. 4A, a water injection layer 20 is applied to the ground surface of the soil G so as to cover the pollutant E. It is formed to construct an injection facility 30 and a pumping well 40.

Next, as shown in FIG. 4 (B), groundwater is pumped from the pumping well 40 to lower the groundwater level H1 in the portion of the soil G where the pollutant E is present.

Next, as shown in FIG. 4C, the injection liquid is injected from the injection facility 30 into the water injection layer 20. Since the water injection layer 20 is made of a material having a higher water permeability than the soil G, the injection liquid is more likely to permeate the inside of the water injection layer 20 than the soil G and is diffused in the lateral direction. As a result, the injection liquid diffuses in a plane so as to cover the contaminant E from above.

Further, the water injection layer 20 has a high water permeability coefficient of the upper layer 22 and a low water permeability coefficient of the lower layer 26. Therefore, the injection liquid can be diffused in a plane in the upper layer 22, and the biofilm or the like contained in the injection liquid can be filtered out in the lower layer 26.

Next, as shown in FIG. 4 (D), by continuing the injection of the injection liquid from the injection equipment 30 into the water injection layer 20, the injection liquid permeates into the soil G. At this time, since the injection liquid permeates from above to below the soil G by gravity, the injection liquid can permeate into the soil G without using power.

Further, the injection liquid diffuses in a plane shape inside the water injection layer 20 and evenly permeates into the soil G. Therefore, the injectable solution can pass through the entire portion of the soil G containing the contaminant E.

Further, a water blocking wall 50 made of a non-permeable material is provided around the water injection layer 20, making it difficult for the injection liquid to flow out to the outside (laterally outside) of the water injection layer 20. Therefore, it is possible to prevent the injection liquid from diffusing into a portion where the injection liquid does not need to permeate.

The water blocking wall 50 does not necessarily have to be provided. The injection liquid can be diffused in a plane without providing the water blocking wall 50. Alternatively, the water blocking walls may be arranged in a grid pattern inside the water injection layer 20 to form a subdivided water injection layer 20. In this way, when the pollutant E is irregularly distributed, it can be efficiently purified by injecting the injection liquid into a part of the subdivided water injection layer.

Next, as shown in FIG. 4 (E), the injection of the injection liquid from the injection equipment 30 into the water injection layer 20 is stopped, and the injection liquid is permeated into the soil G containing the pollutant E by gravity.

Next, as shown in FIG. 4 (F), when the injection liquid passes through the portion containing the pollutant E and the concentration of the decomposing substance in the groundwater becomes lower than the predetermined value, the groundwater is discharged from the pumping well 40. Pump water. The concentration of the decomposing substance is measured using groundwater collected from a pumping well or groundwater collected from a separately provided observation well.

The criterion for pumping groundwater from the pumping well 40 is not limited to the concentration of the decomposing substance, but may be, for example, the temperature of groundwater or soil G. When the temperature of the groundwater or soil G becomes lower than the predetermined value, the groundwater is pumped, the pumped groundwater is purified, a decomposition substance is added to generate an injection liquid, and the heated injection liquid is permeated into the soil G. .. The temperature of groundwater can be measured by a thermocouple installed inside the pumping well, and the temperature of soil G can be measured by a thermocouple buried in soil G.

Further, both the concentration of the decomposing substance and the temperature of the groundwater (or soil G) may be used as a criterion for pumping the groundwater from the pumping well 40. In this case, groundwater is pumped when either the concentration or the temperature falls below a predetermined value. The "predetermined value" of the concentration and temperature as an index of the start of pumping is a threshold value at which the activity of the decomposing substance decreases when the value is lower than the predetermined value.

[Second Embodiment]
(Coating layer)
As shown in FIG. 5, in the soil purification system 12 according to the second embodiment, the covering layer 52 is provided above the water injection layer 20. The covering layer 52 is formed of a concrete panel, and is formed by laying it on the upper part of the water injection layer 20. Since the concrete panel has a lower water permeability than the soil G, it is difficult for rainwater to mix with the injection liquid injected into the water injection layer 20. Therefore, it is possible to suppress a decrease in the concentration of the decomposing substance and a decrease in the temperature of the injection solution. In addition, it is possible to suppress the volatilization of the injection liquid. Therefore, the concentration of the decomposing substance in the injection solution and the temperature of the injection solution can be maintained at appropriate values.

As the material for forming the coating layer 52, in addition to the concrete panel, a rubber or vinyl chloride sheet, asphalt roofing, or the like can be used. Since these materials also have lower water permeability than soil G, it is possible to prevent rainwater from being mixed with the injection liquid.

Further, in the present embodiment, the coating layer 52 is provided in order to prevent rainwater from being mixed with the injection liquid, but the embodiment of the present invention is not limited to this. For example, the coating layer 52 may be provided to make the injection liquid less susceptible to the outside air temperature. In this case, for example, by forming the coating layer 52 with a heat insulating material such as Styrofoam, it is possible to prevent the heated injection liquid from being cooled by the outside air in winter.

Since Styrofoam is a closed-cell foam, it also has water-stopping properties. Therefore, Styrofoam can also be used to prevent rainwater from being mixed with the injection solution. As described above, the coating layer 52 may be provided for a plurality of purposes. For example, since concrete has a large heat capacity, the above-mentioned concrete panel has the purpose of suppressing the mixing of rainwater with the injection liquid, and also reduces the heating energy at night by storing solar heat in the daytime and dissipating it at night. It can be used for the purpose of making it.

[Third Embodiment]
As shown in FIG. 6B, in the soil G in the third embodiment, the contaminated layer G2 is formed at a position sandwiched between the clay layers G1. The clay layer G1 has low water permeability, and it is difficult for the injection liquid to permeate from above.

Therefore, in the soil purification system 14 according to the third embodiment, the water injection layer 60 formed in a planar shape is formed inside the soil G and above the contaminated layer G2. The water injection layer 60 is formed of crushed stone, gravel, silica sand, etc., and has a higher hydraulic conductivity than the clay layer G1 and the contaminated layer G2.

The injection facility 70 in the soil purification system 14 includes a water injection well 74 for injecting an injection liquid into the water injection layer 60 instead of the injection pipe 34 (see FIG. 1) in the first embodiment. The tip of the water injection well 74 reaches the contaminated layer G2, and a discharge port (not shown) is provided at a portion in contact with the water injection layer 60. The purification device 72 of the injection facility 70 has the same configuration as the purification device 32 in the first embodiment.

Further, the pumping well 80 has a tip reaching the contaminated layer G2, and groundwater of the contaminated layer G2 can be pumped from a strainer (not shown) formed at the tip.

As a result, the injection liquid generated by the purification device 32 is injected into the water injection layer 60 from the water injection well 74 and permeates the inside of the water injection layer 60 in the lateral direction. Then, it permeates from the water injection layer 60 into the contaminated layer G2 to purify the pollutant E. After that, it is pumped from the pumping well 80 together with the groundwater.

FIG. 6A shows a plan view showing the arrangement of the water injection well 74, the pumping well 80, and the water injection layer 60. The water injection layer 60 is formed in a planar shape across a plurality of water injection wells 74 and pumping wells 80.

In order to form such a water injection layer 60, first, as shown in FIG. 7A, a vertical hole 90 reaching the contaminated layer G2 sandwiched between the clay layers G1 is drilled from the ground surface of the soil G. ..

Next, as shown in FIG. 7B, a hollow discharge pipe 92 is inserted into the vertical hole 90, and a high-pressure water flow from the discharge port 92A formed in the pipe wall of the discharge pipe 92 toward the hole wall of the vertical hole 90. To form a notch GE in the contaminated layer G2.

Further, as shown in FIG. 7C, the notch GE is excavated and extended in the lateral direction. In order to open the notch GE, a fracturing fluid (splitting fluid) is pumped from the discharge port 92A to the notch GE. The fracturing fluid is water to which a chemical substance used for excavating soil or rock body by water pressure is added, and in the present embodiment, it is a viscous fluid having self-decomposability. Further, in order to promote the purification of the pollutant E, a decomposing substance of the pollutant E is contained. The autolytic property is a property that the viscosity decreases with the passage of time, and due to this property, the fracturing fluid is recovered from the pumping well 80 without staying in the soil G.

By pumping the fracturing fluid to the notch GE, the fracturing fluid flows into the contaminated layer G2 while cutting open a portion where the interparticle bonding force of the particles forming the contaminated layer G2 is weak, and a planar flow path GW is formed. NS.

Further, as shown in FIG. 7 (D), a fracturing fluid mixed with silica sand or gravel having a particle size larger than that of the particles forming the contaminated layer G2 is discharged from the discharge port 92A to the flow path GW, and the silica sand or the like. The flow path GW is filled with gravel. As a result, the water injection layer 60A surrounding the vertical hole 90 is formed.

As shown in FIG. 8B, the water injection layer 60A is formed in a planar shape around the vertical hole 90. A plurality of vertical holes 90 are drilled at predetermined intervals, and a water injection layer 60A is formed in each of the vertical holes 90 by the steps of FIGS. 7 (B) to 7 (D) described above. As a result, as shown in FIG. 8 (A), the water injection layers 60A are connected to form the water injection layers 60 shown in FIGS. 6 (A) and 6 (B).

The vertical hole 90 after the water injection layer 60 is formed can be used as a water injection well 74 or a pumping well 80 by inserting a casing.

In the soil purification system 14 according to the third embodiment, when the pollutant E spreads in a plane inside the soil G, the water injection layer 60 can be formed directly above the pollutant E. Therefore, the pollutant E can be effectively purified.

The soil purification system 14 according to the third embodiment can be applied not only to the case where the pollutant E is spread in a planar manner but also to the case where the pollutant E is spread in a deep part of the soil G. Even in such a case, if the water injection layer 60 is formed directly above the pollutant E, the purification efficiency is high.

[Fourth Embodiment]
As shown in FIG. 9, in the soil purification system 16 according to the fourth embodiment, the water injection layer 110 is formed in a wall shape downward from the ground surface of the soil G. When the wall-shaped water injection layer 110 is viewed from the front, the water injection layer 110 is arranged so as to overlap the pollutant E of the soil G.

The injection facility 100 includes a purification device 102 and an injection pipe 104 that injects the injection liquid generated by the purification device 102 into the water injection layer 110. The injection pipe 104 is laid inside the water injection layer 110 in the vertical direction in order to allow the injection liquid to quickly permeate the water injection layer 110. Further, a pumping well 120 is provided on the side opposite to the water injection layer 110 with the pollutant E in between.

In the soil purification system 16 according to the fourth embodiment, the injection liquid injected into the water injection layer 110 diffuses in a plane inside the water injection layer 110 and evenly permeates into the soil G. Therefore, the injectable solution can pass through the entire portion of the soil G containing the contaminant E.

In the first and second embodiments, a water injection layer 20 is formed on the ground surface above the pollutant E as shown in FIGS. 1 and 5, and in the third embodiment, FIGS. 6 (A) and 6 (A), As shown in (B), the top of the water injection well 74 is exposed on the ground surface. That is, in the first to third embodiments, it is necessary to install the water injection layer 20 and excavate the water injection well 74 on the ground surface above the pollutant E.

On the other hand, in the fourth embodiment, it is not necessary to carry out the construction on the ground surface above the pollutant E. Therefore, if there is a building above the pollutant E, the soil G can be purified while the building is in service.

In the soil purification system 16, the injection pipe 104 is laid inside the water injection layer 110 along the vertical direction, but the embodiment of the present invention is not limited to this. For example, the injection pipe may be embedded in the upper part of the water injection layer 110 in the lateral direction, or the injection liquid may be poured into the water injection layer 11 without using the injection pipe. Even in this way, the injection liquid permeates the inside of the water injection layer 110 by gravity.

Further, the groundwater is pumped by the pumping well 120, but the embodiment of the present invention is not limited to this. For example, the ground surface may be excavated in a groove shape to form an underdrain filled with crushed stone, and groundwater may be pumped from this underdrain. If an underdrain is formed instead of the pumping well 120, it becomes easy to construct a pumping facility.

20, 28, 60, 110 Water injection layer 30, 70, 100 Injection equipment 40, 80, 120 Pumping well (pumping equipment)
50 Water stop wall G Soil

Claims (7)

A water injection layer provided on the surface of the soil or in the soil and having a higher water permeability than the soil and formed in a planar shape over the entire area covering the pollutants contained in the soil.
An injection facility that injects an injection solution containing a substance for decomposing the pollutant into the water injection layer and permeates the injection solution from the water injection layer into the soil.
A soil purification system including a pumping facility for pumping groundwater containing the injectable solution from the soil. The soil purification system according to claim 1, wherein the water injection layer is provided on the surface of the soil, and the pumping facility is a pumping well. The soil purification system according to claim 2, wherein a water blocking wall is provided on the outer peripheral portion of the water injection layer. The soil purification system according to claim 2 or 3, wherein the water injection layer is laid without excavating the soil. The soil purification system according to any one of claims 2 to 4, wherein the water injection layer is composed of a plurality of layers, and the upper layer has a larger hydraulic conductivity than the lower layer. Wherein the infusate comprises a possible warming purifier, the water injection layer, the recovery pipe for recovering a portion of the injection liquid injected into the water injection layer is provided, according to claim 2-5 The soil purification system according to any one item. The soil purification system according to any one of claims 2 to 6, wherein a coating layer is provided on the upper part of the water injection layer.

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