JP3232494B2 - Method for cleaning contaminated soil and cleaning apparatus used in the method - Google Patents

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 apparatus 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 such as groundwater for such ground, it is necessary to remove pollutants.

Conventionally, there has been no effective means for removing such contaminants from the ground, and there is no means for collecting and discarding contaminated soil as it is, or replacing it with new soil or contaminated soil. Measures were taken to contain the contaminants from leaking out.

Here, when collecting and discarding soil on the contaminated ground, it is difficult to secure land at a dump site for discarding the contaminated soil, and at the same time, transportation costs for waste soil and new soil are required. There is a problem that a large-scale facility must be constructed and a large cost is required even when a large amount of cost is required and contaminants are contained.

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

That is, as shown in FIG. 2, a water pumping hole 2 is excavated in the ground 1 and a water injection hole 3 is excavated at a position separated from the water pumping hole 2 by a predetermined distance. And a water conduit 5 extending from the water pump 4 to the water injection hole 3 via the ground is laid, and pollution contained in groundwater pumped from the water pump 4 in the water conduit 5 on the ground. Filtration devices 6 and 7 for removing substances or impurities, and a pressure pump 8 for pressure-feeding the treated water purified by the filtration 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 pump 8. In the drawings, reference numerals 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-described groundwater purifying apparatus, Contaminants such as heavy metals are not easily released or eluted from the soil,
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 contaminants (including impurities) contained in groundwater and adsorbing the soil in a negatively charged state. Provided is a method for cleaning contaminated soil, which can efficiently remove and elute contaminants such as heavy metals, thereby completely purifying the contaminated soil, and a cleaning apparatus used in the method. With the goal.

[0009]

SUMMARY OF THE INVENTION According to the present invention, there is provided a method for cleaning contaminated soil, comprising pumping groundwater from a pumping hole formed by excavating the ground including the contaminated soil, and collecting the contaminated material by the pumped groundwater. A method for cleaning contaminated soil, wherein water is injected into a water injection hole formed by excavating the ground after passing the soil .
Primary treatment by filtration device and filtration membrane by quality recovery device
Secondary treatment by the device and tertiary treatment by the reverse osmosis membrane device
After performing, the treatment water discharged from the contaminant recovery apparatus is characterized by adding a chemical which promotes separation and elution of the contaminant from the soil. Preferably, the chemical is a low pH acidic substance or a powder of an ion exchange resin.

A contaminated soil cleaning apparatus of the present invention pumps groundwater from a pumping hole formed by excavating the ground containing contaminated soil, and excavates the ground from groundwater pumped by the pumping apparatus. And a contaminant collecting device interposed in the water conduit, the contaminated soil cleaning device comprising the contaminant collecting device.
The equipment consists of a primary treatment device consisting of a filtration device and a filtration membrane device.
Treatment equipment consisting of a second treatment device and tertiary treatment treatment consisting of a reverse osmosis membrane device
And a chemical addition device for adding a chemical to the treated water discharged from the contaminant recovery device, which promotes separation and elution of the contaminant from the soil.

[0011]

In the method for purifying contaminated soil according to the present invention, groundwater is pumped from a pumping hole, the pumped groundwater is passed through a pollutant collection device, and then injected into a water injection hole. Since a chemical that promotes separation 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 to which the chemical is added penetrates into the ground. Then, the separation and elution of the contaminants such as heavy metals adsorbed on the contaminated soil are promoted and eluted into the groundwater. In this way, by repeating the cycle consisting of pumping, collection of contaminants, addition of chemicals, and water injection, contaminants can be efficiently released and eluted,
It is possible to completely clean the contaminated soil.

In the apparatus for purifying contaminated soil according to the present invention, the pumping device raises the groundwater from the pumping hole to the ground through the headrace, and the groundwater that has risen to the ground passes through the pollutant recovery device. The contaminants (including impurities) contained in the groundwater are removed, and the treated water is injected into the water injection holes, and the treated water discharged from the contaminant collecting device is added to the contaminated material 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 to which the chemical is added penetrates into the ground, and separation and elution of the contaminants such as heavy metals adsorbed on the contaminated soil are promoted and eluted into the groundwater. The contaminants are removed from the pumping holes and removed by a contaminant recovery device. In this way, by repeating the cycle consisting of pumping, collection of contaminants, addition of chemicals, and injection of water, it is possible to efficiently release and elute contaminants and completely clean the contaminated soil. .

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG.

The apparatus 10 for cleaning contaminated soil according to this embodiment
Indicates a case where the present invention is applied to ground contaminated by factory drainage and the like.

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

A water pump (corresponding to the water pump of the present invention) 14 is disposed in the water pumping hole 12, and a water pipe 15 extending from the water pump 14 to the water injection hole 13 through the ground.
(Corresponding to the headrace of the present invention). A primary treatment device 16 (filtration device), a secondary treatment device 17 ( filtration membrane device ), a pressure pump 1
8, a tertiary treatment device 19 (reverse osmosis membrane device) and a chemical addition device 20 are interposed in this order in the direction of the groundwater moving in the water pipe 5. The contamination of the present invention is caused by the primary treatment device 16, the secondary treatment device 17, and the tertiary treatment device 19.
A substance recovery device is configured.

The primary treatment device 16 comprises a sand settling 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 diameter such as suspended substances in groundwater.

The secondary processing unit 17 is made of stainless steel,
Metals such as brass, monel, nickel, or alumina, aluminum silicate, porcelain, silicon carbide,
Microfiltration membranes made of inorganic materials such as glass and silica fibers, or organic polymer materials such as polyethylene, polyamide, polyolefin, and polytetrafluoroethylene, or cellulose acetate and its derivatives, polyacrylonitrile, polysulfone, and polyether It is composed of an ultrafiltration membrane made of materials such as sulfone, polyelectrolyte complex, aromatic polyamide, polyvinyl alcohol, chitosan, acetyl curdlan, crosslinked polyamide, crosslinked polyimide, polyvinylidene fluoride, and polytetrafluoroethylene. From several hundred μm to 0.0
It has a function of removing a substance having a particle size of about 1 μm. The secondary processing device 7 is provided with a recovery port 17a for recovering the removed substance.

The pressure pump 18 includes a primary processing unit 16.
And a function of pumping the treated water purified by the secondary treatment device 17 to the water injection hole 13 side.

The tertiary treatment apparatus 19 comprises a reverse osmosis membrane using a material such as cellulose acetate, polyamide, heterocyclic polymer, water-soluble polymer cross-linking, polymerizable monomer, and fluorine. And 10 contained in groundwater
It has a function of removing substances having a particle size of about 0.1 nm to 0.1 nm. The tertiary processing apparatus 19 is provided with a recovery port 19a for recovering the removed substance.

The chemical adding device 20 agitates and mixes a chemical discharge unit (not shown) for discharging a chemical, a chemical discharged from the chemical discharge unit, and a treated water discharged from the tertiary treatment device 19. And a stirring tank (not shown) for mixing. As the chemical, those that promote the release or elution of contaminants from soil are appropriately selected.
Acidic substances, ion-exchange resin powder, and the like.

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

First, by driving the pump 14, the groundwater rises in the water pipe 15. This groundwater is
Primary processing unit 16 and secondary processing unit 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. The contaminants removed by the secondary processing device 17 are collected from the collection port 17a.

The treated water is pumped by driving the 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, a chemical is added to the treated water discharged from the tertiary treatment device 19 by a chemical addition device 20.

Thereafter, the treated water to which the chemical has been added reaches the water injection hole 13 and easily penetrates into the ground 1 through the water injection hole 13.
Then, the chemicals added to the treated water act on contaminants such as heavy metals adsorbed on the contaminated soil, thereby promoting separation or elution from these soils. Here, when a low pH acidic substance is used as a chemical, the negatively charged state of the ground is relaxed, cations such as heavy metals are easily released from the soil, and when an ion exchange resin powder is used as the chemical, Reacts directly with heavy metals and the like, and the heavy metals and the like are separated from the soil.

As described above, the groundwater from which the contaminants have been separated or eluted is pumped again from the pumping hole 12, and the primary to
By repeating the cycle of processing by the tertiary treatment devices 16, 17, and 19, the contaminated soil is gradually cleaned. Then, the cycle is continued until no contaminant is detected in the pumped ground water or the pollutant falls below the allowable value.

According to the contaminated soil purifying apparatus 10 and the contaminating method of the present embodiment, the contaminants contained in the groundwater are removed from the primary treatment device 16, the secondary treatment device 17, and the tertiary treatment device 19.
Is removed and collected outside, only the purified groundwater is injected into the ground 11 and reduced. Thereby, pollutants in the ground 11 can be removed through the groundwater.

Further, since chemicals for promoting the separation or elution of contaminants are added to the treated water discharged from the tertiary treatment device 19 by the chemical addition device 20, when the treated water is injected into the ground 11, the chemicals are added. Is added to the ground 11, the contaminants such as heavy metals adsorbed on the contaminated soil are promoted to be released and eluted, and eluted into the groundwater. Contaminants are removed. In this way, by repeating the cycle consisting of pumping, collection of contaminants, addition of chemicals, and water injection, contaminants can be efficiently separated and eluted, and the contaminated soil can be completely purified.

In the above embodiment, there is an advantage that the operation is simple because the circulation system is such that the groundwater is pumped from the pumping hole 12 and injected from the injection hole 13. Furthermore, the cleaning operation can be performed while confirming the cleaning effect by analyzing the water quality of the pumped water.

Incidentally, soil contamination is often distributed in the unsaturated zone above the groundwater table. However, the flow rate to be injected from the injection hole 13 is set large to forcibly raise the groundwater table to reduce the unsaturated zone. By applying the cleaning method to a saturated zone, the contaminated soil distributed in the unsaturated zone can be cleaned.

In this embodiment, three processing devices 16 and
It was performed to remove contaminants using 17 and 19 but, filtered
A primary treatment device 16 composed of a device and a filtration membrane device
Secondary treatment device 17 and tertiary treatment device comprising reverse osmosis membrane device
As long as it has a storage device 19,
The formation is optional , for example, 1
The next processing device 16 and the secondary processing device 17 may be configured as one device, or the number of processing devices may be increased.

The aquifer in which the pumping hole 2 and the water injection hole 3 are located has no problem if it is the same aquifer or different aquifers.

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

[0035]

As described above, according to the method for purifying contaminated soil according to the present invention, groundwater is pumped from pumping holes formed by excavating the ground containing contaminated soil, and the pumped groundwater is contaminated with contaminants. after passing through the recovery system, a method of cleaning contaminated soil water injection water injection holes formed by drilling the ground, the
The primary to tertiary treatment is performed by the pollutant recovery device.
, Since the addition of chemicals to facilitate the separation and elution from soil contaminants treated water discharged from the pollutant recovery device, the pollutants contained in the groundwater contaminant collecting device
1st to 3rd treatment by advanced treatment to ensure removal
In addition, the treated water to which chemicals have been added is allowed to penetrate into the ground, promoting the separation and elution of contaminants such as heavy metals adsorbed on the contaminated soil. The apparatus can efficiently remove contaminants and complete the cleaning of contaminated soil.

Further, according to the apparatus for cleaning contaminated soil of the present invention, a pumping apparatus for pumping groundwater from a pumping hole formed by excavating the ground containing contaminated soil, and a pump for pumping groundwater pumped by the pumping apparatus. An apparatus for purifying contaminated soil, comprising: a headrace that leads to a water injection hole formed by excavating the ground; and a pollutant recovery device interposed in the headrace.
The substance recovery device consists of a primary treatment device consisting of a filtration device and a filtration device.
A secondary treatment device consisting of a permeation device and a reverse treatment device consisting of a reverse osmosis device
A tertiary treatment device, and a chemical addition device for adding a chemical that promotes separation and elution of the pollutant from the soil to the treated water discharged from the contaminant collection device. Underground by primary to tertiary treatment
Advanced treatment of pollutants contained in water for reliable removal
In addition, the treated water, to which chemicals have been added by the chemical addition device, penetrates into the ground, promotes separation and elution of contaminants such as heavy metals adsorbed on the contaminated soil, and pumps water again from the pumping holes. Thus, the pollutant can be efficiently removed by the pollutant recovery device, and the cleaning of the contaminated soil can be completely completed.

[Brief description of the drawings]

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

FIG. 2 is a longitudinal section showing a prior art groundwater purifying apparatus of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Purification apparatus of contaminated soil 11 Ground 12 Pumping hole 13 Water injection hole 14 Pumping pump (water pumping device) 15 Water pipe (water pumping channel) 16 Primary treatment device (filtration device) 17 Secondary treatment device (filtration membrane device) 193 Next processing equipment (reverse osmosis membrane equipment) 20 Chemical addition equipment

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-228463 (JP, A) JP-A-52-67104 (JP, A) JP-A-5-23692 (JP, A) JP-A 52-67 48202 (JP, A) JP-A-53-48871 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) E02D 3/10 B09C 1/02 B09C 1/04 B09C 1/08

Claims (4)

(57) [Claims] 1. Groundwater is pumped from a pumping hole formed by excavating the ground including contaminated soil, and the pumped groundwater is passed through a pollutant recovery device. A method for cleaning contaminated soil to be injected with water, the method comprising:
The primary treatment by the filtration device and the filtration
Secondary treatment with a supermembrane device and tertiary treatment with a reverse osmosis membrane device
After physical, method of cleaning contaminated soil characterized by the addition of chemicals to facilitate the separation and elution from soil contaminants treated water discharged from the pollutant recovery device. 2. The method according to claim 1, wherein the chemical is a low pH acidic substance. 3. The method 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 ground containing contaminated soil, and a guide for guiding groundwater pumped by the pumping device to a water injection hole formed by excavating the ground. An apparatus for cleaning contaminated soil, comprising a waterway and a pollutant recovery device interposed in the waterway,
The contaminant recovery device is a primary treatment device comprising a filtration device.
, A secondary treatment device consisting of a filtration membrane device, and a reverse osmosis membrane device
A tertiary treatment device comprising a chemical treatment device, and a chemical addition device for adding a chemical to the treated water discharged from the contaminant collection device to promote separation or elution of the contaminant from the soil. Equipment for cleaning contaminated soil.