JP2001009480A - Method for removing harmful substance in ground water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently remove harmful substances in ground water in a short time with a small-scaled device while preventing the ground subsidence or the like due to the removal. SOLUTION: In this method for removing the harmful material in the ground water W stored in a well 1 vertically provided in soil 2, the harmful material in the ground water W stored in the well 1 is decomposed by the oxidation action of ozone by aerating the ground water W with an ozone-containing gas G. An ultraviolet emitting means 6 for irradiating the ground water stored in the well 1 with ultraviolet ray and a reflux means 1b for refluxing the ground water, in which the harmful material is removed, into the soil 2 can be provided. The gas can contain ozone, oxygen and an oxidizing agent. The oxidizing agent is desirably hydrogen peroxide or hypochlorite.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for removing harmful substances from groundwater.

[0002]

2. Description of the Related Art As a method of removing harmful substances such as volatile organic compounds (VOC) existing in groundwater, a well is erected in soil, and groundwater stored in the well is pumped and pumped. There is a method that removes harmful substances from the groundwater and releases it into rivers. In addition, removal of harmful substances is performed by, for example, oxidative decomposition or adsorption of activated carbon from aerated gas in a processing facility provided on the ground.

[0003]

However, in the case of the above method, there is a problem that it is necessary to secure a site for the pumping equipment and the processing equipment on the ground near the well, and it takes a long time to install the equipment. . In particular, in the case where volatile organic compounds in groundwater are transferred to air by aeration and then activated carbon adsorption treatment is performed, an aeration tower and a means for collecting the air after aeration are required. there were. In addition, there was a possibility of land subsidence due to pumping of groundwater.

The present invention has been made in view of the above circumstances, and an object of the present invention is to efficiently remove harmful substances in groundwater using a small-scale apparatus without adversely affecting land subsidence or the like.

[0005]

SUMMARY OF THE INVENTION The present invention relates to a method for removing a harmful substance from groundwater stored in a well by erection of a well in soil, the method comprising: Groundwater is aerated with a gas containing ozone, and harmful substances in the groundwater are decomposed by the oxidizing action of ozone.

[0006] Ultraviolet irradiation means for irradiating ultraviolet light to groundwater stored in the well, and groundwater from which harmful substances have been removed are pumped by the airlift effect of gas supplied into the well, and then returned to the soil. A reflux means may be provided.

[0007] The gas may contain ozone, oxygen and an oxidizing agent. For example, the gas may contain ozone, air and an oxidizing agent. In this case, the oxidizing agent is desirably hydrogen peroxide or hypochlorous acid.

The harmful substances that can be removed by the removal method of the present invention include oxidatively decomposable harmful substances such as dioxin, PCB, and cyan, in addition to the volatile organic compounds.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an apparatus used in the method for removing harmful substances in groundwater according to the present invention. Reference numeral 1 denotes a well, and the well 1 penetrates through an unsaturated layer (range indicated by an arrow A in the figure) in the soil 2 to form an aquifer (range indicated by an arrow B in the figure).
Buried in the soil 2 so as to reach. At the lower end of the well 1, an opening 1a is formed toward the aquifer B,
Through this opening 1a, groundwater W in aquifer B is transferred to well 1
Is stored within.

A pipe 3 is inserted into the well 1 from above. The lower end of the pipe 3 opens at the lower end of the well 1 into the groundwater W stored in the well 1 and the upper end of the pipe 3 Is connected to the compressor 4 and the ozone generator 5.
Further, an opening 1b is formed at the upper end of the well 1 toward the unsaturated layer A, and the groundwater W stored in the well 1 is indicated by an arrow C in the figure through the opening 1b. As described above, the water is returned to the surrounding soil 2.

Reference numeral 6 denotes an ultraviolet lamp (ultraviolet irradiation means) installed at the lower end of the well 1 for irradiating the groundwater W stored in the well 1 with ultraviolet light, and reference numeral 7 denotes a downstream side of the compressor 4. Is an oxidant supply device for supplying an oxidant to the pipeline 3. In place of the opening 1b, a trench is installed at the upper end of the well 1 as the above-mentioned reflux means, and the groundwater W
From the trench to an infiltration well, a pond, or the like by underground infiltration or piping, or the like, and may be returned to the soil 2.

When removing harmful substances from groundwater W,
By operating the compressor 4, the gas supplied from the ozone generator 5 or the mixed gas of the gas supplied from the ozone generator 5 and the oxidant supplied from the oxidant supply device 7 is supplied through the pipe 3. Supply to well 1. Then, the groundwater W stored in the well 1 flows from the lower end of the pipeline 3 to the well 1
It is aerated by the gas (indicated by G in the figure) injected into the inside. At the same time, the ultraviolet lamp 6 is turned on to irradiate the groundwater W aerated with the gas G with ultraviolet rays.

In the present invention, the gas G supplied from the ozone generator 5 to the groundwater W via the pipe 3 is
A gas containing ozone is used. Specifically, a mixed gas of ozone and oxygen or ozone and air is used. As the oxidant supplied from the oxidant supply device 7, for example, hydrogen peroxide or hypochlorous acid is used.

Then, harmful substances in the groundwater W are transferred to the well 1
Inside, it is strongly accelerated and oxidatively decomposed by contact of aerated ozone with oxygen and an oxidizing agent and irradiation of ultraviolet rays, and is decomposed and removed into carbon dioxide, water, chlorine gas, hydrochloric acid or the like. These decomposition products are dissolved in the groundwater W and made harmless. The groundwater W from which harmful substances have been removed is gas G
Together with the soil, and is returned to the surrounding soil 2 through the opening 1b provided at the upper end of the well 1. On the other hand, when a trench is installed in place of the opening 1b, the water is guided to a well or a pond for infiltration by underground infiltration from the trench or a pipe, and is returned to the soil 2.

That is, according to the present invention, the harmful substances in the groundwater W are decomposed in the well 1 by the synergistic action of the aerated gas G and the irradiated ultraviolet light.
There is no need to provide groundwater W pumping equipment and toxic substance treatment equipment. In addition, the land for the above facilities becomes unnecessary,
The time required to install the device is also reduced. As a result, according to the present invention, harmful substances can be efficiently removed in a short time by a small-scale device. Furthermore, groundwater W
The groundwater W is returned to the surrounding soil 2 via the opening 1b and other return means without pumping the ground, and there is no danger of land subsidence or the like.

[0016]

As described above, according to the method for removing harmful substances in groundwater according to the present invention, the harmful substances in groundwater are decomposed in advance by oxidative decomposition with ozone or the like in the wells. There is no need to provide groundwater pumping equipment and toxic substance treatment equipment. As a result, harmful substances
With a small-scale device, it can be efficiently removed in a short time. In addition, since groundwater is not pumped, there is no danger of land subsidence.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of an apparatus used for a method for removing an organic chlorine compound in groundwater according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 well 1b opening (reflux means) 2 soil 6 ultraviolet lamp (ultraviolet irradiation means) G gas W groundwater

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) E21B 43/12 E21B 43/12 // E21B 43/00 43/00 Z

Claims (6)

[Claims] 1. A method for removing a harmful substance from groundwater stored in a well by standing a well in soil, wherein the groundwater stored in the well is filled with a gas containing ozone. A method for removing harmful substances in groundwater, comprising aerating and decomposing the harmful substances in the groundwater by the oxidizing action of ozone. 2. The method for removing harmful substances in groundwater according to claim 1, further comprising an ultraviolet irradiation means for irradiating the groundwater stored in the well with ultraviolet light. 3. A method according to claim 1, wherein said well is provided with a reflux means for returning groundwater from which harmful substances have been removed to the soil after pumping the groundwater by an airlift effect of a gas supplied into said well. Item 3. The method for removing harmful substances in groundwater according to Item 1 or 2. 4. The method according to claim 1, wherein said gas contains ozone, oxygen, and an oxidizing agent.
3. The method for removing harmful substances in groundwater according to the section. 5. The method according to claim 4, wherein the gas contains ozone, air and an oxidizing agent. 6. The method according to claim 4, wherein the oxidizing agent is selected from hydrogen peroxide or hypochlorous acid.
3. The method for removing harmful substances in groundwater according to 1.).