JPH0782729A - Purification method of contaminated soil and purification device used for method concerned - Google Patents

Abstract

PURPOSE:To enable efficiently the separation and elusion of contaminant of heavy metal, etc., adsorbed to soil in a state negatively electrified. CONSTITUTION:A purification method is such that ground water is pumped up from a pumped-up bole 12, in the case water is poured into a water pouring hole 13 after the ground water is made to pass through contaminant collection device 16, 17 and 19, chemicals facilitating the separation and elusion from contaminated soil is added to treated water discharged from the contaminant collection device. A purification device 10 is equipped with a pumping device 14 pumping up the ground water from the pumped-up hole 12, a water conveyance channel 15 leading the ground water pumped up by the pumping device to the water pouring hole 13 and the contaminant collection device 16, 17 and 19 provided to the water conveyance channel. A chemical addition device 20 adding the chemicals facilitating the separation and elusion from the contaminated soil to the treated water discharged from the contaminant collection devices is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning contaminated soil suitable for cleaning contaminated soil and a cleaning device used in the method.

[0002]

2. Description of the Related Art Generally, the ground around a factory is often contaminated by leakage of factory wastewater. When using land including the use of groundwater for such ground, it is necessary to remove pollutants.

Conventionally, there is no effective means for removing such pollutants of the ground, and means for recovering the contaminated soil as it is, discarding it, and replacing it with new soil, or a contaminated soil. Measures have been taken to contain the pollutants from the spillway.

[0004] Here, when the soil of the contaminated soil is collected and discarded, it is difficult to secure land at the disposal site where the contaminated soil is discarded, and the transportation cost of the discarded soil and new soil, etc. There is a problem that a large amount of cost is required and a large-scale facility must be constructed even if the pollutant is contained, which requires a large amount of cost.

In order to solve such a problem, the applicant has proposed the following groundwater purification device (see Japanese Patent Application No. 5-113466).

That is, as shown in FIG. 2, a pumping hole 2 is drilled in the ground 1, a water injection hole 3 is drilled at a position separated from the pumping hole 2 by a predetermined distance, and a pumping pump 4 is installed in the pumping hole 2. And laying a water conduit 5 from the pumping pump 4 to the inside of the water injection hole 3 via the ground, and contamination contained in groundwater pumped from the pumping pump 4 in the water conduit 5 on the ground. Filtering devices 6 and 7 for removing substances or impurities, and a pressure pump 8 for pumping the treated water purified by the filtering devices 6 and 7 to the water injection hole 3 side.
And a reverse osmosis membrane device 9 for further purifying the treated water pumped by the pressure pump 8. In the figure, 7a and 9a are recovery ports for recovering the removed contaminants and impurities.

[0007]

However, since the ground is generally in a negatively charged state, cations such as heavy metals are easily adsorbed on the ground, and even if a groundwater flow is generated by the above-mentioned groundwater cleaning device, Pollutants such as heavy metals are not easily released or eluted from the soil, therefore
There is a problem that the contaminated soil cannot be completely cleaned.

The present invention has been made in view of the above circumstances and is capable of recovering pollutants (including impurities) contained in groundwater and adsorbed to negatively charged soil. To provide a method for cleaning a contaminated soil and a cleaning device used for the method, which can efficiently remove and elute pollutants such as heavy metals and can completely clean the contaminated soil. With the goal.

[0009]

The method for cleaning contaminated soil according to the present invention comprises pumping groundwater from a pumping hole formed by excavating the ground containing the contaminated soil, and pumping the groundwater to a pollutant recovery device. This is a method for cleaning contaminated soil in which water is injected into a water injection hole formed by excavating the ground after the passage, and promotes separation and elution of pollutants from soil in treated water discharged from the pollutant recovery device. It is characterized by adding a chemical that does. The chemical is preferably a low pH acidic substance or an ion exchange resin powder.

The cleaning apparatus for polluted soil according to the present invention is a pumping apparatus for pumping groundwater from a pumping hole formed by excavating the ground containing the polluted soil, and groundwater for pumping groundwater by the pumping apparatus. An apparatus for purifying contaminated soil, comprising: a water conduit leading to a water injection hole formed by the above; and a pollutant recovery device interposed in this water conduit, wherein the treated water discharged from the pollutant recovery device is contaminated. It is characterized in that a chemical addition device for adding a chemical that promotes release and elution of the substance from the soil is provided.

[0011]

In the method for cleaning contaminated soil according to the present invention, the groundwater is pumped from the pumping hole, the pumped groundwater is passed through the pollutant collecting device, and then the groundwater is poured into the pouring hole. Since a chemical that promotes the release and elution of pollutants from the soil is added to the discharged treated water, when the treated water is injected into the ground, the treated water containing the chemical penetrates into the ground. The removal and elution of pollutants such as heavy metals adsorbed on the contaminated soil is promoted to elute into the groundwater, and the water is pumped again from the pumping hole, and the pollutants are removed by the pollutant recovery device. In this way, by repeating the cycle of pumping water, collecting pollutants, adding chemicals, and injecting water, pollutants can be efficiently released and eluted,
It is possible to completely clean the contaminated soil.

In the apparatus for cleaning polluted soil of the present invention, the pumping device causes groundwater to rise above the ground through the pumping hole into the headrace, and the groundwater that rises above the ground passes through the pollutant recovery device. The pollutants (including impurities) contained in the groundwater are removed, and the treated water is poured into the water injection hole, and the treated water discharged from the pollutant recovery device is polluted by the chemical addition device. A chemical that promotes the release and elution of the soil from the soil is added. Therefore, when the treated water is injected into the ground, the treated water into which the chemical has been added permeates into the ground, and the desorption / elution of contaminants such as heavy metals adsorbed on the contaminated soil is promoted to elute into the groundwater, and again. Water is pumped from the pumping hole and pollutants are removed by the pollutant recovery device. In this way, by repeating the cycle of pumping water, collecting pollutants, adding chemicals, and injecting water, it becomes possible to remove and elute pollutants efficiently, and to completely clean the contaminated soil. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A cleaning apparatus for polluted soil according to an embodiment of the present invention will be described with reference to FIG.

Cleaning apparatus 10 for polluted soil according to this embodiment
Shows the case where it is applied to the ground contaminated by factory wastewater.

In the figure, reference numeral 11 is the ground, and a pumping hole 12 is excavated in the ground 11, and a water injection hole 13 is drilled at a position separated from the pumping hole 12 by a predetermined distance.

A pumping pump (corresponding to the pumping device of the present invention) 14 is disposed in the pumping hole 12, and a water conduit 15 extends from the pumping pump 14 to the inside of the pumping hole 13 via the ground.
(Corresponding to the headrace of the present invention) is laid. At the above-ground portion of the water pipe 15, the primary treatment device 16 (filter device), the secondary treatment device 17 (filter device), the pressure pump 1
8. A tertiary treatment device 19 (reverse osmosis membrane device) and a chemical addition device 20 are provided in this order in the direction of groundwater moving in the water conduit 5. The primary treatment device 16, the secondary treatment device 17, and the tertiary treatment device 19 correspond to the contaminant recovery device of the present invention.

The primary treatment device 16 is composed of a sedimentation tank filled with sand or the like having an appropriate particle size.
The primary treatment device 16 has a function of removing substances having a large particle size such as suspended substances in groundwater.

The secondary processing device 17 is made of stainless steel,
Metals such as brass, monel, nickel, alumina, aluminum silicate, porcelain, silicon carbide,
Microfiltration membrane made of inorganic material such as glass / silica fiber or organic polymer material such as polyethylene, polyamide, polyolefin, polytetrafluoroethylene, or cellulose acetate and its derivatives, polyacrylonitrile, polysulfone, polyether Sulfone, polyelectrolyte complex, aromatic polyamide, polyvinyl alcohol, chitosan, acetyl curdlan, crosslinked polyamide, crosslinked polyimide, polyvinylidene fluoride, polytetrafluoroethylene, etc. Included number 100 μm to 0.0
It has a function of removing a substance having a particle diameter of about 1 μm. The secondary processing device 7 is also provided with a recovery port 17a for recovering the removed substance.

The pressure feed pump 18 is a primary treatment device 16
It also has a function of pumping the treated water purified by the secondary treatment device 17 to the water injection hole 13 side.

The tertiary treatment device 19 is composed of a reverse osmosis membrane using materials such as cellulose acetate type, polyamide type, heterocyclic polymer type, water-soluble polymer cross-linking type, polymerizable monomer type and fluorine type. 10 included in groundwater
It has a function of removing a substance having a particle diameter of about 0.1 nm to 0.1 nm. The tertiary treatment device 19 is also provided with a recovery port 19a for recovering the removed substance.

The chemical addition device 20 stirs a chemical discharge portion (not shown) for discharging the chemical, the chemical discharged from the chemical discharge portion and the treated water discharged from the tertiary treatment device 19. And a stirring tank (not shown) for mixing. As the chemical, a chemical that promotes release and elution of pollutants from the soil is appropriately selected, for example, low pH
The acidic substance, the ion-exchange resin powder, and the like are used.

Next, the operation of the contaminated soil cleaning apparatus 10 will be described, and the contaminated soil cleaning method of one embodiment of the present invention will be described.

First, groundwater rises in the water pipe 15 by driving the pumping pump 14. This groundwater is
Primary processing device 16 and secondary processing device 17 located on the ground
Pass through. At this time, the contaminants contained in the groundwater are removed by the primary treatment device 16 and the secondary treatment device 17. Further, the contaminants removed by the secondary processing device 17 are recovered from the recovery port 17a.

The treated water is pressure-fed by driving the pressure-feed pump 18, and passes through the tertiary treatment device 19. At this time, the tertiary treatment device 19 removes extremely fine contaminants contained in the treated water. The substance removed by the tertiary treatment device 19 is recovered from the recovery port 19a.

Further, chemicals are added to the treated water discharged from the tertiary treatment device 19 by the chemical addition device 20.

After that, the treated water to which the chemical is added reaches the water injection hole 13 and easily permeates into the ground 1 through the water injection hole 13.
Then, the chemicals added to the treated water act on the pollutants such as heavy metals adsorbed on the contaminated soil to promote their release or elution from these soils. Here, when an acidic substance having a low pH is used as a chemical, the negatively charged state of the ground is eased and cations such as heavy metals are easily released from the soil, and when an ion exchange resin powder is used as a chemical. Reacts directly with heavy metals, etc., and the heavy metals, etc. separate from the soil.

In this way, the groundwater from which the pollutants have been released or eluted is pumped again from the pumping holes 12 and the primary to
The contaminated soil is gradually cleaned by repeating the cycle of being treated by the tertiary treatment devices 16, 17, and 19. Then, the cycle is continued until no pollutants are detected in the pumped groundwater or the pollutants are below the allowable value.

According to the contaminated soil cleaning device 10 and the cleaning method of this embodiment, the pollutants contained in the groundwater are treated as the primary treatment device 16, the secondary treatment device 17, and the tertiary treatment device 19.
Since it is removed by and is collected outside, only the cleaned groundwater is injected and returned to the ground 11. As a result, the pollutants in the ground 11 can be removed via groundwater.

Furthermore, the treated water discharged from the tertiary treatment device 19 is added with a chemical that promotes the removal or elution of pollutants by the chemical addition device 20. Therefore, when the treated water is injected into the ground 11, the chemical is added. The treated water with added water permeates into the ground 11, promotes the removal and elution of pollutants such as heavy metals adsorbed on the contaminated soil, elutes into the groundwater, and is pumped up again from the pumping hole and by the pollutant recovery device. Pollutants are removed. In this way, by repeating the cycle of pumping water, collecting pollutants, adding chemicals, and injecting water, pollutants can be efficiently released and eluted to completely clean the contaminated soil.

The above-mentioned embodiment has a merit that the work is simple because it is a circulation system in which groundwater is pumped from the pumping hole 12 and poured from the injection hole 13. Furthermore, the cleaning work can be carried out while confirming the cleaning effect by analyzing the quality of the pumped water.

By the way, soil contamination is often distributed in the unsaturated zone above the water table, but the flow rate injected from the injection hole 13 is set to a large value to forcibly raise the water table to form the unsaturated zone. By applying the cleaning method to the saturated zone, the contaminated soil distributed in the unsaturated zone can be cleaned.

In this embodiment, the three processing units 16,
Although the contaminants were removed using 17 and 19, depending on the contamination status of the ground 1, for example, the primary treatment device 16 and the secondary treatment device 17 may be configured as one device, or the number of treatment devices may be increased. May be.

The aquifers in which the pumping holes 2 and the pouring holes 3 are located may be the same aquifer or different aquifers without any problem.

Further, in the above embodiment, the pumping hole 12 and the water injection hole 13 are separately excavated, but one excavating hole is vertically divided by a partition member such as a packer, and for example, the lower excavating hole is formed. It may be configured as a water pumping hole and as an upper drilling hole, and the lower part and the upper part may be provided with the cleaning device as shown in the above embodiment. In this case, it is preferable that the impermeable layer is located at the portion where the partition member is arranged.

[0035]

As described above, according to the method for cleaning polluted soil of the present invention, groundwater is pumped from the pumping hole formed by excavating the soil containing the polluted soil, and the pumped groundwater is polluted. A method for cleaning contaminated soil, which comprises pouring water into a water injection hole formed by excavating the ground after passing through a recovery device, wherein the treated water discharged from the pollutant recovery device separates pollutants from soil and Since a chemical that promotes elution is added, the pollutants contained in groundwater can be removed by a pollutant recovery device, and the treated water containing the chemical is allowed to penetrate into the ground, and the heavy metals adsorbed on the polluted soil. It is possible to promote the removal and elution of pollutants such as, and to pump water again from the pumping holes to efficiently remove pollutants by the pollutant recovery device, and to completely clean polluted soil.

Further, according to the contaminated soil cleaning apparatus of the present invention, the pumping apparatus for pumping groundwater from the pumping hole formed by excavating the soil containing the polluted soil, and the groundwater pumped by this pumping apparatus. A device for purifying contaminated soil, comprising a water conduit leading to a water injection hole formed by excavating the ground, and a pollutant collecting device interposed in the water conduit, which is discharged from the pollutant collecting device. Since a chemical addition device is added to the treated water to add a chemical that promotes the release and elution of pollutants from the soil, it is possible to remove the pollutants contained in the groundwater with the pollutant recovery device. The permeation of treated water with added chemicals into the ground promotes the removal and elution of pollutants such as heavy metals adsorbed on contaminated soil, and pumps water from the pumping hole again to efficiently pollutants with the pollutant recovery device. To Can be removed by, it is possible that makes it complete the cleaning of the contaminated soil.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an apparatus for cleaning contaminated soil according to an embodiment of the present invention.

FIG. 2 is a longitudinal section showing a prior art groundwater cleaning device of the present invention.

[Explanation of symbols]

 10 Cleaner for contaminated soil 11 Ground 12 Pumping hole 13 Water injection hole 14 Pumping pump (pumping device) 15 Water pipe (conducting channel) 16 Primary treatment device (pollutant recovery device) 17 Secondary treatment device (pollutant recovery device) ) 19 Tertiary treatment device (pollutant recovery device) 20 Chemical addition device

Claims (4)

[Claims] 1. A groundwater is pumped from a pumping hole formed by excavating a soil containing contaminated soil, the pumped groundwater is passed through a pollutant recovery device, and then the groundwater is formed into a water injection hole formed by excavating the ground. A method for cleaning contaminated soil, which comprises pouring water into the treated water discharged from the pollutant recovery device and adding a chemical that promotes release and elution of the pollutant from the soil. Method. 2. The method for cleaning contaminated soil according to claim 1, wherein the chemical is an acidic substance having a low pH. 3. The method for cleaning contaminated soil according to claim 1, wherein the chemical is a powder of an ion exchange resin. 4. A pumping device for pumping groundwater from a pumping hole formed by excavating the ground containing contaminated soil, and a conduit for guiding the groundwater pumped by the pumping device to a water injection hole formed by excavating the ground. A device for cleaning contaminated soil, comprising a waterway and a pollutant recovery device interposed in the waterway,
A cleaning device for contaminated soil, comprising a chemical addition device for adding a chemical that promotes release and elution of pollutants from soil to the treated water discharged from the pollutant recovery device.