JP2005305311A - Early stabilization method of improper disposal site - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an early stabilization method of an improper disposal site that conducts the stabilization treatment by controlling a ground water level and prohibiting the infiltration of rainwater into the site while preventing the immersion water from discharging to public water area. <P>SOLUTION: The early stabilization method comprises the steps of placing an outside water sealing wall 23 so as to surround reclaimed land 21 at the foundation 22 of the stabilization disposal site turned into the improper disposal site until it reaches the hardly permeable layer 24, installing a surface impermeable sheet 25 to cover the reclaimed land 21 surrounded with the outside water sealing wall 23, installing a pumping well 29 between the outside water sealing wall 23 and the reclaimed layer 27 of the reclaimed land 21, installing an air injection well 35 at contaminated site 26 in which the contaminant of the reclaimed layer 27 exists while maintaining the contaminated site 26 in the non-aquifer 32 by pumping the stored water of the reclaimed layer 27 through the pumping well 29 and blowing air into the contaminated site 26 through the well 35 for injecting air to produce aerobic condition, thereby promoting the stabilization of the contaminated site 26. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an early stabilization method for an inappropriate disposal site.

  Conventionally, a stable disposal site (stable final disposal site) is a final disposal site that has been defined by the structural standards for industrial waste final disposal sites (landfills) and maintenance management standards. A place to dispose of things. Stable industrial waste is industrial waste (excluding specially controlled industrial waste) that is almost the same as soil, gravel, etc. and can be disposed of as non-polluting environmental waste. Waste plastics, rubber scraps, scrap metal, scrap glass , Ceramic waste, concrete debris.

On the other hand, managed landfills (managed final landfills) are industrial wastes other than those targeted for cutoff and stable landfills, such as waste oil, paper waste, wood waste, textile waste, animal and vegetable residues, animals It is a landfill site for manure, animal carcasses and harmless husks, dust, sludge, mines, etc., and there is a facility standard defined by law.
The main standards are as follows.
(1) Indicate that it is the final disposal site for industrial waste.
(2) Install retaining walls, embankments, etc. to prevent outflow of landfill waste.
(3) To perform conservation measures for public water areas due to leachate from landfills and necessary water shielding works when there is a risk of groundwater contamination.
(4) To install surface opening and others that can prevent surface water from flowing into the landfill from the opening of the landfill.

However, in the stable disposal site (stable final disposal site), industrial waste (waste oil, paper waste, wood waste, textile waste, animal and plant residues, animal manure, animal carcass and harmless materials that should be landfilled in the managed disposal site originally. Incorrect disposal of burning husks, dust, sludge, slag, etc.) or improper disposal of these wastes by mixing them with stable industrial waste due to insufficient sorting It becomes a problem to become a place.
Japanese Patent Publication No. 48-16534

  By the way, the stable disposal site assumes landfill disposal of stable industrial waste (which is almost the same as soil, gravel, etc. and does not pollute the environment). No leachate treatment equipment is installed. In addition, in a stable disposal site, flammable gas such as carbon monoxide and toxic gas such as hydrogen sulfide are not generated. There is no equipment such as a tube, or no facilities are installed to create a semi-aerobic atmosphere.

  For this reason, industrial waste (waste oil, paper waste, wood waste, textile waste, animal and vegetable residues, animal manure, animal carcass and harmless husks, dust, sludge, iron waste, etc.) that should be landfilled in a managed disposal site It is necessary to carry out a stabilization process that stabilizes the inappropriate disposal site at an early stage.

Stabilization is a process in which wastes are forced to end in a short time in a natural manner in which waste undergoes physical, chemical, or biochemical changes and does not change any further.
By the way, conventional purification methods for contaminated soil include air sparging, bio-venting (bioventing), and flushing.

  As shown in FIG. 3, bio-venting is performed when a volatile organic compound is present as the pollutant 3 in the non-aquifer 2 of the purification target formation 1, and the contaminated non-aquifer 2 An insufflation well 4 for insufflation is provided, and compressed air is blown directly from the blower 5 through the insufflation well 4 into the contaminated part to aerobicize, thereby evaporating the volatile organic compound and promoting the removal of volatile substances. In addition, oxygen is supplied to promote biodegradation by indigenous bacteria and biologically promote soil purification. In the air sparging, when the contaminant 3 is present in the aquifer 6, the compressed air is blown directly into the aquifer 6 to aerobize.

  As shown in FIG. 4, the flushing is performed when heavy metal is present as the pollutant 3 in the aquifer 6 of the purification target formation 1, and the water injection well 7 provided at the upstream position of the contaminated part of the aquifer 6. Clean water 8 is injected into the aquifer 6 from the aquifer 6, and the contaminated water 10 is pumped from the aquifer 6 through the pumping well 9 provided downstream of the contaminated site to wash away the pollutants. 10 is made into clean water by a water treatment system (water treatment facility) 11 provided in the vicinity, and then poured into the injection well 7 as cleaning water 8 again.

  However, when applying the conventional purification method to stabilization of improper disposal sites, the stable disposal sites, unlike the management-type disposal sites, prevent leachate from landfills from flowing into public water bodies. There is no water-impervious work, and there is not necessarily an open water that prevents surface water from flowing into the landfill from the opening of the landfill, so that leachate containing pollutants flows out of the site even during the purification period. There was a problem that underground pollution by pollutants spread.

  Also, for aerobicization of the site, it is desirable to perform bio-venting without draining the water held in the site. However, in a stable disposal site, control of groundwater level in the site and intrusion of rainwater into the site Therefore, flushing is also difficult.

  The present invention solves the above-described problems, and controls the groundwater level and prevents intrusion of rainwater into the site, and performs an improper disposal site that performs stabilization treatment while preventing leachate from flowing into public water bodies. The purpose is to provide an early stabilization method.

  In order to solve the above problems, the method for early stabilization of an inappropriate disposal site of the present invention according to claim 1 is characterized in that an external impermeable wall surrounds a reclaimed land on the ground of a stable disposal site that has become an inappropriate disposal site. Is installed until it reaches the hard-permeable layer, covers the area enclosed by the external impermeable wall including the landfill site, and provides groundwater impermeable means, and a pumping well is installed between the external impermeable wall and the landfill layer of the landfill site. Establish an air filling well at the contaminated site where the pollutant in the landfill layer exists, and pump the retained water in the non-aquifer by pumping the water held in the landfill layer through the pumping well. The stabilization of the contaminated site is promoted by blowing air into the site to be aerobic.

  With the above configuration, by enclosing the landfill layer including the contaminated site as a closed area with the ground water-impervious means, the external impermeable wall, and the poorly permeable layer, rainwater and groundwater flow into the landfill layer from outside the closed area. Minimize as much as possible, keep contaminated water in the landfill layer within the closed area and prevent leachate from diffusing outside the closed area.

  In this state, while maintaining the contaminated site in the non-aquifer by pumping the retained water in the landfill through the pumping well, air, for example compressed air, is preferably blown directly into the contaminated site through the well. Vaporizes and vaporizes volatile organic compounds to promote detachment of volatile substances, and supplies oxygen to promote biodegradation by indigenous bacteria to promote biological soil purification.

  The early stabilization method of the inappropriate disposal site of the present invention according to claim 2 is to surround the reclaimed land on the ground of the stable disposal site that has become an inappropriate disposal site and reach the impermeable layer through the external impermeable wall Laying, covering the area including the landfill and surrounded by the external impermeable wall, providing groundwater impermeable means, providing a pumping well between the outer impermeable wall and the landfill layer of the landfill, and from the pumping well to the landfill layer An injection well is provided at a position that separates the contaminated site where pollutants are present, and clean water is supplied from the injection well to the landfill layer, while maintaining the contaminated site in the aquifer, The retained water is pumped as contaminated water, and the pumped contaminated water is converted into clean water at the water treatment facility and then circulated and supplied to the injection well as cleaning water. Is.

  With the above configuration, by enclosing the landfill layer including the contaminated site as a closed area with the ground water-impervious means, the external impermeable wall, and the poorly permeable layer, rainwater and groundwater flow into the landfill layer from outside the closed area. Minimize as much as possible, keep contaminated water in the landfill layer within the closed area and prevent leachate from diffusing outside the closed area.

  In this state, clean water is supplied from the injection well to the landfill layer to increase the amount of water held by the aquifer in the closed area to raise the groundwater level and maintain the contaminated site in the aquifer. While injecting water from this injection well, the retained water in the landfill layer is pumped through the pumping well, so that the wash water (retained water) flowing from the injection well to the pumping well in the aquifer removes contaminants from the contaminated site. Wash away. Contaminated water that has passed through the contaminated site is pumped up through a pumping well, purified at a water treatment facility to form clean water, and then circulated and supplied to the injection well as cleaning water. This cleaning water circulation supply takes out contaminants from the contaminated site to the outside of the buried layer and promotes stabilization of the contaminated site.

  As described above, according to the present invention, it is possible to enclose rainwater and groundwater from outside the closed region to the landfill layer by enclosing the landfill layer including the contaminated portion as a closed region with the surface water-impervious means, the external water-impervious wall, and the hardly permeable layer. While controlling the level of groundwater (retained water) as much as possible, the contaminated retained water in the landfill layer remains in the closed area, and the leachate flows out to the public water area outside the closed area It is possible to achieve early stabilization of an inappropriate disposal site while preventing diffusion.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, the improper disposal site originally has a structure of a stable disposal site, and there is no water-impervious work or the like separating the landfill 21 (area surrounded by a broken line) from the surrounding ground 22. For this reason, the external impermeable wall 23 surrounding the landfill 21 is provided on the ground 22 around the landfill 21 of the inappropriate disposal site. The external impermeable wall 23 is placed until it reaches the poorly permeable layer 24 of the ground 22. Further, a surface impermeable sheet 25 is provided as a ground impermeable means so as to cover the landfill 21 surrounded by the external impermeable wall 23 and the surrounding ground 22. The ground water shielding means can be a roof. With this structure, the surface impermeable sheet 25, the external impermeable wall 23, and the hardly water-permeable layer 24 surround the landfill 21 including the contaminated site 26 and a portion of the ground 22 around the landfill 21 as a closed region 28.

  A pumping well 29 is provided between the external impermeable wall 23 and the landfill 21. The pumping well 29 has a lower end reaching the hardly permeable layer 24, and has a suction part 30 for sucking water retained in the landfill 21 at the lower side, and the suction part 30 is a boundary between the aquifer 31 and the non-aquifer 32. Corresponds to the groundwater level 33. Although the groundwater level 33 varies depending on the amount of retained water, the groundwater level 33 is maintained at a predetermined position below the contaminated site 26 in the present invention as will be described later. The upper end of the pumping well 29 communicates with a water treatment system (water treatment device) 34. The water treatment system 34 is a known leachate treatment facility, and detailed description thereof is omitted.

  An air injection well 35 is provided in the contaminated site 26 where the pollutant in the landfill 21 exists. The air injection well 35 has a lower end reaching the vicinity of the groundwater level 33 below the contaminated site 26, has an air supply portion 36 on the lower side, and is connected to a blower 37 on the upper end. The air supply unit 36 mainly corresponds to the non-aquifer 32.

  The operation of the above configuration will be described below. Since the surface impermeable sheet 25, the external impermeable wall 23, and the poorly permeable layer 24 enclose the landfill 21 including the contaminated site 26 and a portion of the ground 22 around the landfill 21 as a closed region 28, it is closed. Inflow of rainwater and groundwater from the outside of the region 28 to the landfill 21 is suppressed as much as possible. In addition, the contaminated retained water in the landfill 21 stays inside the closed area 28, thereby preventing leachate from diffusing into the public water area outside the closed area 28.

  In the stabilization process, the groundwater level 33 is maintained so that the contaminated site 26 exists in the non-aquifer 32 by pumping the retained water in the landfill 21 through the pumping well 29. Since the pollutant in the contaminated site 26 may leak to the retained water outside the landfill 21 due to a temporary rise in the groundwater level 33, the pumped retained water is discharged after being purified by the water treatment system 34. In this state, the compressed air supplied from the blower 37 is blown directly into the contaminated site 26 through the air filling well 35 to aerobicize, and the volatile organic compound of the pollutant is vaporized to promote the detachment of the volatile substance. To promote biodegradation by indigenous bacteria and biologically promote soil remediation.

  FIG. 2 shows another embodiment of the present invention, and the same reference numerals are given to configurations that perform the same operation as the previous embodiment, and the description thereof is omitted. In FIG. 2, a water injection well 38 is provided at a position separating the contaminated site 26 where the pollutant in the landfill 21 exists from the pumping well 29, and the lower end of the water injection well 38 reaches the vicinity of the bottom of the landfill 21. A water supply unit 39 for supplying cleaning water to the landfill 21 is provided on the side, and the water supply unit 39 mainly corresponds to the aquifer 31. The upper end of the water injection well 38 is connected to the water treatment system 34.

  Also in this configuration, the surface impermeable sheet 25, the external impermeable wall 23, and the hardly water-permeable layer 24 surround the landfill 21 including the contaminated site 26 and a part of the ground 22 around the landfill 21 as a closed region 28. Therefore, the inflow of rainwater and groundwater from the outside of the closed region 28 to the landfill 21 is suppressed as much as possible. In addition, the contaminated retained water in the landfill 21 stays inside the closed area 28, thereby preventing leachate from diffusing into the public water area outside the closed area 28.

In the stabilization process, by supplying clean washing water from the water injection well 38 to the landfill 21, the groundwater level 33 is raised and maintained so that the contaminated site 26 exists in the aquifer 31.
While washing water is poured from the injection well 38, the retained water in the landfill layer is pumped up as contaminated water through the pumping well 29, and the contaminated water is made clean by the water treatment system 34 and then circulated and supplied to the injection well 38 as cleaning water. To do.

  By this operation, the washing water (retained water) flowing from the injection well 38 to the pumping well 29 in the aquifer 31 ishes away the heavy metals of the pollutant in the polluted site 26, and the pollutant is released from the polluted site by circulating supply of the wash water. Is taken out of the buried layer 27 to promote stabilization of the contaminated site.

The schematic diagram which shows the early stabilization method of the improper disposal site in embodiment of this invention The schematic diagram which shows the early stabilization method of the improper disposal site in other embodiment of this invention Schematic diagram showing a conventional method for purifying contaminated soil Schematic diagram showing a conventional method for purifying contaminated soil

Explanation of symbols

21 Landfill 22 Ground 23 External impermeable wall 24 Impermeable layer 25 Surface impermeable sheet 26 Contaminated site 28 Closed area 29 Pumping well 30 Suction part 31 Aquifer 32 Non-aquifer 33 Groundwater level 34 Water treatment system 35 Air pressure Well 36 Air supply part 37 Blower 38 Water injection well 39 Water supply part

Claims (2)

Surrounding the landfill site on the ground of the stable disposal site that has become an inappropriate disposal site, driving the external impermeable wall until it reaches the poorly permeable layer, covering the area enclosed by the external impermeable wall including the landfill site Provide ground-impervious means, provide a pumping well between the external impermeable wall and the landfill layer in the landfill, provide an air well at the contaminated site where the pollutant in the landfill layer exists, and hold the water in the landfill layer through the pumping well Improper disposal characterized by promoting the stabilization of the contaminated site by blowing air into the non-aquifer while pumping water and aerobicizing by blowing air into the contaminated site through the air well Early stabilization method of the field. Surrounding the landfill site on the ground of the stable disposal site that has become an inappropriate disposal site, driving the external impermeable wall until it reaches the poorly permeable layer, covering the area enclosed by the external impermeable wall including the landfill site A groundwater impermeable means is provided, a pumping well is provided between the external impermeable wall and the landfill layer of the landfill, and a water injection well is provided at a position that separates the contaminated part where the pollutant in the landfill layer exists from the pumping well. By supplying clean washing water from the landfill layer to the landfill layer, the retained water in the landfill layer is pumped up as contaminated water through the pumping well, and the pumped contaminated water is purified at the water treatment facility. An early stabilization method for an inappropriate disposal site characterized by promoting the stabilization of contaminated sites by supplying water as irrigation water to the injection well after it has been converted to water and washing away the contaminants with the wash water.

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