JP2002370084A - How to reclaim contaminated soil - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a method for reclaiming contaminated soil that hardly generates industrial waste and does not require much labor and cost for treatment. SOLUTION: A sheet pile 1 is driven into the vicinity of a boundary of a contaminated soil S area to be partitioned, and a starting shaft and a reaching shaft which also serve as a water collecting tank 2 are excavated and formed inside the pile, and a horizontal direction from the starting shaft to the reaching shaft is formed. Press the guide tube slightly upwards,
When the guide pipe reaches the reaching shaft, one end of the water collection pipe 3 is connected to the leading end of the guide pipe and pulled in, so that the water collection pipe 3 is buried in the contaminated soil S, and the contaminant P in the contaminated soil S is removed by rainwater or the like. The contaminated water is accumulated in the water collecting tank 2 through the water collecting pipe 3 and the contaminant P contained in the contaminated water is coagulant F
Then, the coagulant F and the like are collected and discarded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of reclaiming contaminated soil by reclaiming soil by recovering contaminants from soil contaminated with heavy metals, oils and the like.

[0002]

2. Description of the Related Art In some cases, such as a former site of a semiconductor manufacturing plant, a plating plant, and a petroleum product plant, soil is contaminated with harmful heavy metals and oils. These harmful substances infiltrate into the ground together with rainwater and the like, and have become one of the important so-called environmental problems such as secondary disasters such as dissolution into groundwater and other places.

[0003] As a countermeasure against such contaminated soil, the contaminated soil is excavated and removed, and the contaminated soil is backfilled with non-contaminated soil. If the causative substance is a heavy metal, the contaminated soil is directly solidified with cement to remove rainwater or groundwater. If the causative substance is oil, the contaminated soil was incinerated in an incinerator to evaporate the oil.

[0004] However, not only do both methods require enormous disposal costs and operation time, but also a large amount of industrial waste is generated and pollution control becomes insufficient.
It was not a very realistic treatment measure. Thus, for example, Japanese Patent Application Laid-Open No. 10-102471 discloses that 50 to 100% by weight of quicklime and 5 to 10% by weight of
After adding and mixing the sodium silicate, water of about 40% by weight is injected to induce a hydration reaction of quick lime, heavy metals are converted into silicates, and oils are adsorbed on calcium silicate gel generated during the reaction to form water. There is disclosed an invention of a method for treating soil contamination which is modified into an insoluble substance.

[0005]

Although the cost and work time required for the pollution treatment can be reduced to some extent by the above-mentioned method for treating the soil, the chemical used for binding with heavy metals must be consumed in a large amount. Because of this, a large amount of processing cost is required, and the chemicals must be reacted and combined with heavy metals, etc., so that contaminated soil must be excavated, or a myriad of injection holes must be excavated to inject the chemicals. This is a troublesome processing operation, and there is a problem that contaminants remain in the soil.

The present invention has been made to solve such a problem in the prior art, and a method for regenerating contaminated soil which does not produce much industrial waste and does not require much labor and cost for the disposal work. The purpose is to provide.

[0007]

According to the present invention, a water collecting tank for storing contaminated water in a contaminated soil area is formed by excavation, and a plurality of water introduction holes are formed around the water collecting tank. A large number of water collection pipes are buried under pressure in contaminated soil so that one end opens into the water collection tank and is approximately horizontal and slightly inclined toward the water collection tank. Is stored in a water collecting tank through which the contaminant eluted in the contaminated water is adsorbed by the coagulant or the adsorbent put into the water collecting tank, and the coagulant or the like is recovered, preferably Excavates a shaft to reach a position opposite to the water collection tank formed in the contaminated soil area, and presses the guide tube from the inside of the water collection tank into the contaminated soil so that it is almost horizontal and slightly inclined toward the water collection tank, At the tip of the guide tube that has reached the arrival shaft side, After sintering, through the guide tube in which is embedded draws water collecting pipe in the contaminated soil.

[0008]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a schematic diagram of an underground section showing a water collecting facility for regenerating contaminated soil according to an embodiment of the present invention, and FIG. It is an underground cross section schematic diagram. In these figures, reference numeral 1 denotes a sheet pile made of a steel plate or the like buried to a predetermined depth at a boundary portion in order to partition the contaminated soil S area to prevent the diffusion of the contaminant P to other areas, and 2 denotes a contaminated soil. In order to collect the contaminants P in the soil S, a water collecting tank formed also from the surface near the boundary of the contaminated soil S area and serving as a starting shaft, which will be described later, 3 faces the water collecting tank 2 in the contaminated soil S. A large number of water pipes buried under pressure with a slight slope,
Reference numeral 31 denotes a plurality of water guide holes formed over the entire surface except for the lower surface thereof for introducing inundation such as rainwater oozing out of the contaminated soil S into the water collecting pipe 3.

FIG. 5 is a perspective view of the water collecting pipe 3. Water collecting pipe 3
Is formed of a commercially available steel pipe, vinyl pipe, or the like, and the water guide hole 31 is not formed below the water collecting pipe 3 to prevent rainwater or the like from flowing out from the lower surface side. The diameter of the water introduction hole 31 is slightly different depending on the drilling density and the soil quality of the contaminated soil S, but is selected in a range of 3 to 12 mmφ in order to prevent the inflow of the earth and sand and to efficiently introduce the inundation. Is good. The material of the water collecting pipe 3 is preferably a vinyl pipe from the viewpoint of corrosion resistance and price advantage.

Next, a method of constructing a water collecting facility according to the present embodiment will be described. FIG. 3 and FIG. 4 are schematic cross-sectional views of the underground for explaining the method of constructing the water collecting facility. FIG. 3 shows the first step and FIG. 4 shows the second step. In these figures, 4 is a reaching shaft which is a target to be excavated from the starting shaft which becomes the water collecting tank 2, 5 is a push-down device installed on the bottom surface of the starting shaft, and 6 is a contaminated soil S by guiding a guide tube described below. A tip device for pushing the inside, 7 is a guide (pilot) pipe for guiding the water collecting pipe 3, and 8 is a connecting cylinder connecting the guide pipe 7 and the water collecting pipe 3.

First, a sheet pile 1 is driven so as to surround the vicinity of the boundary of the contaminated soil S area to partition the contaminated area, and a start shaft and a reaching shaft 4 which also serve as the water collecting tanks 2 are excavated at both inner ends thereof. Then, a push-down device 5 is provided on the bottom of the starting shaft.
Is installed. Next, the guide tube 7 is attached to the lower push device 5,
After the tip device 6 is screwed to the tip, the pushing device 5 is driven to push the tip device 6 into the contaminated soil S via the guide tube 7. Then, as the tip device 6 enters, the guide tube 7
Are sequentially connected (see FIG. 3). The tip device 6 is provided with a rocking mechanism for rocking its head by hydraulic pressure and an electromagnetic coil for generating a magnetic field, and is connected to the push-down device 5 via a guide tube 7 by a hydraulic cable and an electric wire cable, respectively. ing. The magnetic field generated from the electromagnetic coil is detected by a magnetic field detection device movably installed on the ground surface, and the position of the tip device 6 is detected.

Based on the location information of the tip device 6 obtained in this way, it is determined whether or not the tip device 6 is proceeding in an appropriate direction. It is emitted to the device 5, and the direction correcting hydraulic mechanism (not shown) of the lowering device 5 is driven, and the direction of the head of the tip device 6 is corrected by the swinging mechanism. The traveling direction of the tip device 6 is set so as to slightly rise toward the reaching shaft 4.

When the tip device 6 reaches the reaching shaft 4, the tip device 6 is removed from the guide tube 7, and a connecting tube 8 is attached to the trail, and one end of the water collecting tube 3 is attached to the rear end of the connecting tube 8. Then, the lower pushing device 5 is driven in reverse to draw in the guide pipes 7, and along with this, the water collecting pipes 3 are drawn in along the through holes through which the guide pipes 7 pass. At the time of this retraction, the guide tube 7 pulled out from the through hole is sequentially removed just opposite to the time when the guide tube 7 is pushed. Finally, when the connecting tube 8 is pulled out from the through-hole, the connecting tube 8 is removed from one end of the water collecting pipe 3 and the drawing operation of the water collecting pipe 3 is completed. In this way, a large number of water collecting pipes 3 are buried in the contaminated soil S at predetermined intervals at equal intervals without any gap. When all the water collecting pipes 3 have been buried, the reaching shaft 4 is backfilled to complete the construction of the water collecting facility.

After the water collecting facility is constructed, the contaminants P in the contaminated soil S dissolve into rainwater and groundwater, and the contaminated water flows into the water collecting pipe 3 from the nearest water inlet 31. The inflowing contaminated water flows down to the water collecting tank 2 along the buried collecting pipe 3 slightly inclined toward the water collecting tank 2 and is stored in the water collecting tank 2. When the amount of precipitation is small or when it is desired to quickly collect the pollutant P, water may be artificially sprayed on the surface of the contaminated soil S. When the contaminant P is a heavy metal that is easily soluble in water, it can be recovered through rainwater or groundwater. However, in the case of oils, the contaminant P is not easily dissolved in water. Sprinkle water with the agent dissolved.

As shown in FIG. 1, the water collecting tank 2
Material incineration to made artificial zeolites such as papermaking sludge (composition for _{example, SO 2 62.7% CaCO 3 15.5} % Al 2 O 3 7.2% K
_If a flocculant F or a porous adsorbent such as ₂ O 2.8% Fe ₂ O ₃ 0.3% TiO ₂ 0.2% Na ₂ O 0.2%) is charged and the contaminated water flows into the collection tank 2, the contaminant P is taken into the fine pores of the flocculant F and adsorbed, as shown in FIG. It is considered that the adsorption action of the coagulant F is caused by the electrostatic attraction force because the local part of the coagulant F and the contaminant P are ions of opposite polarities. After a lapse of a predetermined period in which it is considered that the contaminant P has been sufficiently adsorbed to the flocculant F, the flocculant F settled at the bottom of the water collecting tank 2 is pumped and collected together with water by a suction pump. The collected flocculant F and the like are dried and then discarded as industrial waste.

As described above, in the present embodiment, the contaminant P in the contaminated soil S is eluted into rainwater or the like, and the contaminated water containing the contaminant P is passed through the water collecting pipe 3 embedded in the contaminated soil S to collect water. After the contaminant P contained in the contaminated water is adsorbed on the coagulant F or the like, the coagulant F or the like is collected and discarded. The main structure of the water collecting equipment for removing the pollutants P without consuming the chemical is a large number of water collecting pipes 3 buried under pressure in the contaminated soil S and a water collecting tank 2 to which these water collecting pipes 3 communicate. Since no large-scale mechanical equipment is required to construct the water collecting facility, the labor and cost required for removing and regenerating the pollutant P in the contaminated soil S can be greatly reduced. In this embodiment, the contaminant P is adsorbed on the coagulant F or the like. However, if it is possible to secure a large amount of precipitation and a large amount of water supply source, the coagulant F is not used.
The contaminated water stored in the water collecting tank 2 may be drained after being purified by being pumped up by a suction pump.

[0017]

As described above, according to the first aspect of the present invention, a water collecting tank is excavated and formed in a contaminated soil area, and a number of water collecting pipes having a number of water introducing holes formed therearound are provided.
One end opens into the collection tank, and is buried in the contaminated soil so as to be substantially horizontal and slightly inclined toward the collection tank, and the contaminated water is stored in the collection tank through the collection pipe and injected into it. Since the contaminant is adsorbed on the flocculant or the adsorbent and the collected contaminant is recovered, almost no industrial waste is produced, and the labor and cost required for the processing operation can be greatly reduced.

According to the second aspect of the present invention, the reaching shaft is excavated at a position facing the water collecting tank formed in the contaminated soil area, and the guide pipe is inclined substantially horizontally from the water collecting tank toward the water collecting tank. After that, one end of the water collection pipe was connected to the tip of the guide pipe that reached the reaching shaft side by injecting it into the contaminated soil, and then the water collection pipe was drawn into the contaminated soil through the guide pipe and buried. In addition, a water collection pipe can be efficiently pressed into and buried in contaminated soil.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an underground cross section showing a water collecting facility for regenerating contaminated soil according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of an underground cross-section of a water collecting facility showing a state in which a process of regenerating contaminated soil has progressed.

FIG. 3 is a schematic diagram of an underground cross section for explaining a first step of a method of constructing a water collecting facility.

FIG. 4 is an underground cross-sectional schematic view for explaining a second step of the method of constructing the water collecting facility.

FIG. 5 is a perspective view of a water collecting pipe.

FIG. 6 is an explanatory view showing a situation in which a contaminant is adsorbed on a flocculant.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 sheet pile 2 water collecting tank 3 water collecting pipe 4 reaching shaft 5 lowering device 6 tip device 7 guide tube 8 connecting tube 31 water guide hole F coagulant P pollutant S contaminated soil

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2D043 DA04 DD15 4D004 AA41 AB02 AB03 AC07 4D015 BA19 BB05 CA06 CA17 DA35 DC04 EA32 FA03 FA30 4D024 AA04 AB04 AB16 BA07 DA10 DB01 DB21

Claims (2)

[Claims] 1. A method for reclaiming contaminated soil by reclaiming soil by collecting contaminants from soil contaminated with heavy metals, oils, etc., wherein a water collecting tank for storing contaminated water in a contaminated soil area is formed. At the same time, a large number of water collection pipes having a large number of water introduction holes formed around them are pressed into the contaminated soil so that one end of the water collection pipe is opened in the water collection tank and is substantially horizontal and slightly inclined toward the water collection tank. Contaminated water buried and eluted with contaminants in rainwater etc. is stored in the water collecting tank through the water collecting pipe, and the contaminants eluted in the contaminated water into the flocculant or the adsorbent charged in the water collecting tank A method for reclaiming contaminated soil, wherein the method comprises adsorbing and collecting the flocculant or the adsorbent. 2. A contaminated soil is excavated at a position facing a water collecting tank formed in the contaminated soil area, and a guide pipe is substantially horizontally inclined from the inside of the water collecting tank toward the water collecting tank. After connecting one end of the water collecting pipe to the tip of the guide pipe reaching the reaching shaft side, the water collecting pipe was drawn into the contaminated soil via the guide pipe and buried therein. The method for reclaiming contaminated soil according to claim 1.