JP2006043602A - Treatment system for contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To surely recover ground water and gas in soil comprising contaminants even if the recovery of the contaminants is difficult since the presence of a layer hard to permeate water or a layer hard to permeate gas obstructs the same. <P>SOLUTION: Regarding the treatment system 1 for contaminated soil, the inside of contaminated soil 2 is provided with a pumping well 3, and the pumping well is mainly composed of a casing 4 made of a hollow cylindrical steel tube and gravel 5 as a gas-water permeable material arranged so as to surround the circumferential face and the bottom face thereof. The lower end of the casing is provided with a strainer part 7 as shown in figure (b), further, the upper position of the strainer part is provided with an adsorbent cartridge 10 capable of adsorbing the contaminants within the casing 4, and in the upper part of the adsorbent cartridge 10, a storage pump 8 and a column pipe 9 communicating with the storage pump are installed within the casing. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a contaminated soil treatment system for detoxifying contaminated soil mainly containing an organic chlorine compound as a contaminant.

  Various pollutants such as volatile organochlorine compounds, fuel oils and machine oils, dioxins, or heavy metals such as cadmium, lead, copper, zinc, nickel, and chromium are mixed in the soil of the factory site. Sometimes.

  If the contaminated soil contaminated with such contaminants is left as it is, the contaminants mixed in the soil will diffuse to the surroundings, hindering the lives of the surrounding residents, and if they are released from the soil particles by rainwater In addition, it may cause contamination of groundwater by contaminating water quality. Therefore, the soil contaminated with the above-mentioned pollutants must be cleaned using various methods.

  Various methods have been developed to purify the pollutants in the soil in-situ, including the excavation aeration method and the pumped aeration method, as well as the soil gas suction method and water injection into the contaminated soil. So-called water washing method that pumps water and treats on the ground, so-called bubble entrainment purification method that sends air and entrains pollutants in the bubbles, air sparging method that combines air pressure and gas suction, microbial activity of soil fungi A wide variety of methods are known, such as a method using bioremediation using a biotin.

  Here, volatile organochlorine compounds such as trichlorethylene, which is mainly used for degreasing cleaning of machine parts, and tetrachloroethylene, which is used as a cleaning liquid for dry cleaning, are vaporized and recovered using a soil gas suction method or an air sparging method. There are many cases.

JP 2000-42537 A

  Here, even if it is a volatile organochlorine compound, its vapor pressure varies.For example, the vapor pressure of trichlorethylene is 7.8 kPa (20 ° C), and the vapor pressure of tetrachlorethylene is 1.9 kPa (20 ° C). Although it is easy to evaporate and recover, tetrachloroethylene takes time to evaporate and recover.

  In other words, vaporization and recovery using the above-described excavation aeration method, pumped water aeration method, soil gas suction method, etc. may slow down vaporization due to aeration because of the low vapor pressure depending on the type of volatile organic chlorine compound. The recovery process takes a long time.

  In addition, it is difficult to recover heavy metals by aeration, and the ground gas treatment method and water flow cleaning method require ground treatment facilities, so this may depend on the size of the contaminated site. There has also been a problem that the processing method may not be adopted.

  In addition, it goes without saying that soils, especially soils mainly composed of sedimentary rocks, are composed of multiple layers of different soil properties, but there are poorly permeable and hardly permeable layers in such layers. If the groundwater is pumped or the gas is sucked using the pumping aeration method, the flushing method, the gas suction method, etc., depending on the relative positional relationship between the pumping point or the suction point and the hardly permeable layer or hardly permeable layer However, the presence of the poorly permeable layer and the hardly permeable layer has been a problem, and it has become difficult to collect contaminants by pumping or sucking.

  The present invention has been made in consideration of the above-described circumstances, and even if it is difficult to recover the pollutant due to the presence of the hardly water-permeable layer or the hardly air-permeable layer, the contaminant is included. An object of the present invention is to provide a contaminated soil treatment system capable of reliably collecting groundwater and gas in the soil.

  In order to achieve the above-mentioned object, the contaminated soil treatment system according to the present invention is, as described in claim 1, a pollution in which a pumping well is provided in contaminated soil containing contaminants such as volatile organic chlorine compounds and heavy metals. In the soil treatment system, the pumping well is composed of a casing and a water-permeable material arranged so as to surround the circumferential surface and the bottom surface thereof, and a strainer portion having a water absorption opening formed at the lower end of the casing is provided, and the casing An adsorbent capable of adsorbing the pollutant is filled in an upper position of the strainer portion, and a pumping pump connected to the pumping pump is connected to the upper portion of the adsorbent.

  Further, the contaminated soil treatment system according to the present invention is configured such that the water permeable material is an air permeable water permeable material, and the water intake opening is an intake water intake opening capable of intake air, and the ground discharge of the pump pipe is performed. A vacuum pump connected to the outlet and an airtight cap attached to the top of the casing.

  In the contaminated soil treatment system according to the present invention, the water well is composed of a casing and a water-permeable material disposed so as to surround the peripheral surface and the bottom surface thereof, and a strainer portion in which a water absorption opening is formed at the lower end of the casing. An adsorbent capable of adsorbing the pollutant at a position above the strainer portion in the casing, and a pumping pump connected to the pump and the pump connected to the pump. is there.

  In such a configuration, when the pump is driven, groundwater around the pumping well is collected in the pumping well, and a flow is formed that is forced into the adsorbent through the water absorption opening of the strainer section. And the contaminant contained in the groundwater which flowed into the adsorbent is adsorbed and removed when passing through the adsorbent.

  The groundwater from which contaminants have been removed by the adsorbent is pumped to the ground via a pumping pipe. Such groundwater may be effectively used as appropriate, for example, by returning it to the contaminated soil and using it again.

  Here, in the present invention, since the pumping well is composed of a casing and a water-permeable material arranged so as to surround the peripheral surface and the bottom surface thereof, each layer in the contaminated soil is in a state where each layer communicates with the water-permeable material. Therefore, the groundwater that flows or stays in each layer once flows into the water-permeable material and then flows down through the water-permeable material, and then adsorbs through the water-absorbing openings of the strainer section as described above. It is forced into the material.

  For this reason, even if difficultly permeable layers or permeable layers are laminated in the contaminated soil, the groundwater in each permeable layer is surely collected in the pumping well. It is possible to avoid a situation in which the existence of the layer becomes an obstacle and the groundwater in the permeable layer cannot be collected.

  It is conceivable that the pumping wells are arranged vertically and horizontally in a plane as necessary, and the pitch is set to 3 to 5 m, for example. In addition, the bottom of the pumping well is aquifer (contains saturated or unsaturated) where contaminated groundwater flows or stays in order to collect groundwater in the area where pollutants are diffused. It penetrates to the hardly permeable layer or impervious layer below. By the way, if there is another aquifer under the impermeable layer or impermeable layer and the groundwater present in the aquifer is also contaminated, the pumping well is changed to the above-mentioned impermeable layer or impermeable layer. Further, the lower end is penetrated into another hardly water-permeable layer or water-impermeable layer below it.

  The casing can be made of a cylindrical hollow steel pipe with an inner diameter of about 100 to 120 mm if an inner diameter that allows the arrangement of the pump is used, for example, a small pump, but groundwater is filled in the casing. Needless to say, in order to pass the adsorbent reliably, it must be impermeable.

  The water-permeable material can be composed of coarse particles such as gravel and crushed stone, but the casing is configured so that all layers in the contaminated soil communicate with the strainer provided at the lower end of the casing via the water-permeable material. It arrange | positions continuously on the surrounding surface and bottom face.

  The strainer portion may be configured by forming a water absorption opening such as a water permeable hole in the vicinity of the lower end of the casing, or a hollow porous tube having the same diameter as the casing may be joined to the lower end of the casing. Absent.

  The adsorbent is filled without any gaps in the casing, for example, so that the groundwater flowing in from the strainer part surely passes through the adsorbent, and the entire cross section of the adsorbent exhibits an effective adsorption action. Fill or place above the strainer. Furthermore, for example, when the casing is a cylindrical hollow steel pipe, the adsorbent has a cylindrical shape whose outer diameter is approximately equal to the inner diameter of the casing as a whole. And the flow rate and the like may be determined appropriately.

  The adsorbent can be appropriately selected from known adsorbents such as activated carbon, charcoal powder, diatomaceous earth, and zeolite.

  The pump is also arranged so that the water intake position is above the adsorbent so that all the cross sections of the adsorbent exhibit effective adsorption.

  Here, it is conceivable that the specific layer in the contaminated soil becomes an unsaturated layer because the groundwater level is lowered by pumping or the groundwater level is originally low.

  In the case of such a site, the water-permeable material is a gas-permeable and water-permeable material that can be permeable, and the water-absorbing opening is an intake-and-water-absorbing opening that can be sucked, and is connected to the ground-side discharge port of the pumping pipe What is necessary is just to provide the airtight cap attached to the top part of a pump and the said casing.

  In such a configuration, if an airtight cap is attached to the top of the casing, a vacuum pump is connected to the ground-side discharge port of the pump, and then the vacuum pump is driven, gas in the unsaturated layer can be obtained. The pollutants present in the state once flow into the air-permeable and water-permeable material so as to be entrained by the air, and then flow down through the air-permeable and water-permeable material, and then the adsorbent through the intake water absorption opening of the strainer portion. It is forced to flow into.

  For this reason, even if difficultly permeable layers or permeable layers are laminated in the contaminated soil, the contaminants in each permeable layer must be reliably gasified in the air in the pumping well. Thus, it is possible to avoid a situation in which the presence of the hardly permeable layer is obstructive and the contaminants in the permeable layer cannot be collected.

  Embodiments of a contaminated soil treatment system according to the present invention will be described below with reference to the accompanying drawings. Note that components that are substantially the same as those of the prior art are assigned the same reference numerals, and descriptions thereof are omitted.

  FIG. 1 is a diagram showing a contaminated soil treatment system according to the present embodiment. As shown in FIG. 1 (a), a contaminated soil treatment system 1 according to this embodiment includes a pumping well 3 in a contaminated soil 2 containing contaminants such as volatile organic chlorine compounds and heavy metals. The well is generally composed of a casing 4 made of a hollow cylindrical steel pipe and gravel 5 as an air-permeable and water-permeable material arranged so as to surround the peripheral surface and the bottom surface thereof.

  Here, the lower end of the casing is provided with a strainer portion 7 in which a hole 6 serving as an intake water intake opening is formed, as shown in FIG. An adsorbent cartridge 10 capable of adsorbing contaminants is provided in the casing 4, and further, above the adsorbent cartridge 10, a pumping pump 8 and a pumping pipe 9 connected to the pumping pump are connected to the casing 4. It is installed in.

  The adsorbent cartridge 10 is formed by filling an adsorbent 12 made of activated carbon into a cylindrical body 11 that is in contact with the inner surface of the casing 4, and fixing the cylindrical body to the pedestal of the pumping pump 8 at the top thereof. If the pump is pulled up, the adsorbent 12 can be replaced with a new one, and the adsorbent cartridge 10 and the inner surface of the casing 4 become watertight and airtight, and inserted into the casing 4. In addition, the peripheral surface of the cylindrical body 11 is constituted by an elastic cylindrical body such as rubber subjected to smooth processing so that the take-out operation can be performed smoothly.

  On the other hand, the discharge port on the ground side of the pumping pipe 9 is bifurcated via a switching device 14 including a switching valve 14a and a switching valve 14b, and a vacuum pump 13 is connected to the switching valve 14b. An airtight cap 15 is attached to the top of the casing 4 as shown in 1 (c).

  In order to construct the contaminated soil treatment system 1 according to the present embodiment, first, a pumping hole having a diameter obtained by adding the thickness of the gravel 5 which is an air permeable material to the outer diameter of the casing 4 is formed by excavation in the contaminated soil 2. .

  As shown in FIG. 1A, the contaminated soil 2 is a ground in which an air permeable water permeable layer 21 and a hardly air permeable water permeable layer 22 are laminated in a complicated manner.

  It is desirable to prevent the collapse of the hole wall by, for example, performing the excavation formation of the pumping hole while filling muddy water.

  Next, when the excavation formation of the pumping hole is completed, the slime precipitated at the bottom portion is removed as necessary.

  Next, the gravel 5 which is an air permeable permeation | transmission material is thrown into a water pumping hole, and it spreads on the hole bottom.

  Next, the casing 4 in which the strainer portion 7 is formed in advance is built in the pumping hole, and then the water-permeable material cartridge 10, the pumping pump 8 and the pumping pipe 9 are inserted into the casing 4. Note that the water permeable material cartridge 10, the pumping pump 8, or the pumping pipe 9 may be built in the pumping hole in a state of being inserted into the casing 4 in advance.

  Next, gravel 5 which is an air permeable permeation material is thrown into the peripheral surface of casing 4 and is compacted as necessary, so that the peripheral surface and bottom surface of casing 4 are surrounded by gravel 5 as an air permeable water permeable material. .

  In the contaminated soil treatment system 1 according to the present embodiment, the pumping well 3 is composed of the casing 4 and gravel 5 which is an air permeable material disposed so as to surround the peripheral surface and the bottom surface thereof. A strainer section 7 is provided at the lower end, an adsorbent cartridge 10 capable of adsorbing contaminants is inserted above the strainer section, and a pumping pump 8 and a pumping pipe connected to the pump are connected above the adsorbent cartridge. 9 is installed.

  In such a configuration, when the groundwater level is high, the switching valve 14a is opened and the switching valve 14b is closed, and the pumping pump 8 is driven in this state.

  In this way, groundwater around the pumping well is collected in the pumping well 3, and a flow is formed that is forced to flow into the adsorbent cartridge 10 through the hole 6 that is the intake water intake opening of the strainer section 7. .

  Contaminants such as organic chlorine compounds such as trichlorethylene and tetrachloroethylene and heavy metals such as cadmium, lead, copper, zinc, nickel, and chromium contained in the groundwater flowing into the adsorbent cartridge 10 pass through the adsorbent 12. It is adsorbed and removed.

  The groundwater from which the pollutants have been removed by the adsorbent 12 is pumped to the ground via the pumping pipe 9, and such groundwater can be reused and returned to the contaminated soil 2 for effective use as appropriate. Good.

  Here, in this embodiment, since the pumping well 3 is comprised from the casing 4 and the air permeable material which consists of the gravel 5 arrange | positioned so that the surrounding surface and bottom face may be surrounded, the permeability in the contaminated soil 2 is comprised. The air permeable layer 21 and the hardly permeable air permeable layer 22 are in a state of communicating with the air permeable material.

  Therefore, as shown in FIG. 2, the groundwater that flows or stays in the air permeable layer 21 once flows into the air permeable material composed of gravel 5, and then flows down in the air permeable material. As described above, it is forced to flow into the adsorbent 12 through the hole 6 that is the intake water intake opening of the strainer portion 7.

  On the other hand, when the groundwater level is low, the switching valve 14a is closed and the switching valve 14b is opened, the airtight cap 15 is attached to the top of the casing 4, and the vacuum pump 13 is driven in this state.

  In this way, the gas around the pumping well is collected in the pumping well 3, and a flow is formed that is forced to flow into the adsorbent cartridge 10 through the hole 6 that is the intake water intake opening of the strainer section 7. .

  The above-described contaminants contained in the gas flowing into the adsorbent cartridge 10 are adsorbed and removed when passing through the adsorbent 12.

  Here, in this embodiment, as above-mentioned, the air-permeable water-permeable layer 21 and the hardly air-permeable water-permeable layer 22 in the contaminated soil 2 will be in the state which each communicated with the air-permeable water-permeable material.

  Therefore, the gas flowing or staying in the air-permeable / permeable layer 21 once flows into the air-permeable and water-permeable material composed of gravel 5 and then flows down in the air-permeable and water-permeable material as in FIG. As described above, it is forced to flow into the adsorbent 12 through the hole 6 which is the intake water intake opening of the strainer portion 7.

  As described above, according to the contaminated soil treatment system 1 according to the present embodiment, even if the hardly permeable air permeable layer 22 and the permeable air permeable layer 21 are laminated in a complicated manner in the contaminated soil 2. The groundwater and gas in each permeable permeation layer are surely collected in the pumping well 3, and as in the conventional case, the presence of the hardly permeable permeation layer obstructs the groundwater and gas in the permeable permeation layer. It is possible to avoid the situation where the gas cannot be recovered.

  Although not particularly mentioned in the present embodiment, the adsorbent cartridge 10 is configured by filling the adsorbent 12 made of activated carbon into the cylindrical body 11 in contact with the inner surface of the casing 4 and the cylindrical body 11 at the top thereof. , The adsorbent 12 can be replaced as needed.

  That is, the adsorbent cartridge 10 is lifted to the ground together with the pump 8 and then either the entire adsorbent cartridge 10 is replaced or only the adsorbent 12 is replaced, and then fixed to the pedestal of the pump 8, What is necessary is just to insert in the casing 4. Although there is a concern that the groundwater containing pollutants flows into the casing 4 with the removal of the pumping pump 8, when the new adsorbent cartridge 10 is inserted into the casing 4 together with the pumping pump 8, the pumping pump is If the adsorbent cartridge 10 is inserted into the casing 4 while being driven and pumped, the contaminated water flowing into the casing passes through the adsorbent 12 and is pumped. There will be no problem with the exchange. Even in the case of contaminated gas, except when the adsorbent cartridge 10 is taken out and inserted, if the adsorbent cartridge 10 is moved up and down while driving the vacuum pump with the airtight cap 15 placed on the top of the casing 4, After all, no problem arises.

  Moreover, in this embodiment, although the adsorbent 12 was comprised with activated carbon, it cannot be overemphasized that it is not limited to this material as a material which adsorb | sucks a contaminant.

  In the present embodiment, the adsorbent 12 is placed in the cylindrical body 11 so as to be a cartridge type. However, the adsorbent 12 may be directly inserted into the casing 4 regardless of whether or not replacement is necessary.

  Further, in this embodiment, the system takes into consideration not only the mode in which the pollutant is contained in the groundwater but also the mode in which the pollutant is contained in the air. However, it is necessary to consider gas suction at a site where the groundwater level is high. If not, the switching device 14 and the vacuum pump 13 may be omitted and the gravel 5 may be a water permeable material.

  In addition, although not particularly mentioned in the present embodiment, by selecting a layer to be purified by using a part of the air-permeable and water-permeable material composed of gravel 5 as an air-impermeable and water-permeable material by mortar filling or the like. Can do.

  FIG. 3 shows an example of contaminated groundwater or polluted gas existing in the air-permeable permeation layer under the non-air-permeable permeation layer 22 that extends almost horizontally in the ground. The air-impermeable water-permeable material 31 is formed by filling mortar in the gaps of the gravel 5.

Schematic of the processing system of the contaminated soil which concerns on this embodiment. The figure which showed the effect | action of the processing system of the contaminated soil which concerns on this embodiment. Schematic of the processing system of the contaminated soil which concerns on a modification.

Explanation of symbols

1 Contaminated soil treatment system 2 Contaminated soil 3 Pumping well 4 Casing 5 Gravel (air-permeable water-permeable material, water-permeable material)
7 Strainer section 8 Pumping pump 9 Pumping pipe 12 Adsorbent 13 Vacuum pump 15 Airtight cap

Claims (2)

In the contaminated soil treatment system, which has a pumping well in the contaminated soil containing pollutants such as volatile organic chlorine compounds and heavy metals,
The pumping well is composed of a casing and a water-permeable material arranged so as to surround the peripheral surface and the bottom surface thereof, and is provided with a strainer portion in which a water absorption opening is formed at the lower end of the casing, and the strainer portion in the casing A contaminated soil treatment system, wherein an adsorbent capable of adsorbing the pollutant is filled in an upper position, and a pumping pump connected to the pumping pump and a pumping pipe connected to the pump are installed above the adsorbent. The water permeable material is an air permeable water permeable material that can be permeable, the water intake opening is an intake water intake opening that can be sucked, and a vacuum pump that is connected to the ground-side discharge port of the pumping pipe and the top of the casing. 2. The contaminated soil treatment system according to claim 1, further comprising an airtight cap attached thereto.

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