JP4374682B2 - Method and apparatus for purifying contaminated ground - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for purifying contaminated ground and a purification apparatus therefor, and in particular, intermittently blows ultrahigh-pressure intermittent air together with moisture into the contaminated ground at short intervals, while circulating moisture in the ground. The present invention relates to a contaminated ground purification method and a purification device for improving the efficiency of ground purification.
[0002]
[Prior art]
In recent years, the contaminated ground has become a problem, and various methods for purifying and recovering this have been proposed. In-situ purification that is particularly advantageous in terms of facilities and space is desired. For this in-situ purification, there is a method using indigenous decomposing microorganisms (bioremediation). In order to activate these decomposing microorganisms, nutrient sources such as air (oxygen) and nutrient salts are injected into the ground. Depending on the situation, it may be supplemented with newly decomposed microorganisms. For example, Japanese Patent Laid-Open No. 10-216696 discloses an apparatus for supplying oxygen to contaminated soil. This is to establish an injection well that reaches the groundwater under the contaminated soil, supply supersaturated water containing oxygen excessively from this injection well into the groundwater, make the groundwater oxygen supersaturated, and generate fine bubbles from this oxygen supersaturated groundwater It is intended to supply oxygen to the contaminated soil on the surface layer.
[0003]
[Problems to be solved by the invention]
However, in the conventional method of supplying oxygen from the groundwater to the contaminated soil, oxygen naturally infiltrates into the soil and activates indigenous decomposing microorganisms, so a significantly long purification period is required, The soil is not uniform throughout, and there are cracks and soft spots, so oxygen will concentrate and penetrate there, and the entire soil cannot be purified uniformly.
[0004]
It is also possible to insert injection wells into contaminated soil and continuously inject oxygen (air) or other decomposition-promoting substances and degrading microorganisms directly into the soil. In this case, the purification promoting component is injected into the soil in the form of an aqueous solution or a gas, but also purification unevenness occurs due to the non-uniformity of the soil. In addition, since the injection is continuous, the injection pressure is almost constant and cannot be increased so much, the reach of the purification promoting component is short, and it is difficult to secure a wide purification area per injection well. Therefore, in order to purify the contaminated ground in a wide range of desired areas, the number of injection wells must be increased, resulting in an increase in the cost of ground purification.
[0005]
The present invention has been made in view of such conventional problems, and by injecting air, moisture, and other purification promoting components as necessary into the contaminated ground intermittently at ultrahigh pressure and blowing them explosively. In addition to making this purification promoting component reach far and wider, and circulating the water recovered from the contaminated ground, it promotes the fluidization of the purification promoting component together with this moisture, greatly increasing the purification capacity of the contaminated ground It is an object of the present invention to provide a purification method and a purification device for contaminated ground that can be improved.
[0006]
[Means for Solving the Problems]
Method of purifying contaminated soil of the present invention in order to achieve the above object, a short time interval the ultra-high pressure of the compressed air from 2 to 10 atmospheres from a high voltage intermittent injection device provided on the upper end of the injection well which is inserted in the contaminated soil And supplying water intermittently to the injection well , adding water to the compressed air from the upper end of the injection well on the discharge side of the high-pressure intermittent injection device, and misting the water together with the compressed air while injection from the opening of the infusion Nyui in the contaminated soil in the Jo, to recover the moisture in the contaminated ground from the opening of the slit and perforated formed over a predetermined interval in the suction well inserted into the contaminated soil The recovered water is temporarily stored in a reflux device, and then added to the compressed air from the upper end of the injection well to return it to the contaminated ground.
[0007]
Further, a purification device for achieving this purification method is formed of a pipe and inserted into a contaminated ground , and an injection well having an opening of the pipe as a jet outlet and attached to the upper end of the injection well . A high-pressure intermittent injection device that supplies ultra-high-pressure compressed air of 10 atm in a pulsed manner at short intervals to the injection well, and a pipe formed and inserted into the contaminated ground, the lower end of the pipe In the part, a suction well in which slits and porous openings for sucking moisture in the contaminated ground are formed over a predetermined section, and temporarily store the moisture in the contaminated ground sucked from this suction well, a recirculation unit which supplies the upper end portion of the injection well is a discharge side of the water high pressure intermittent injection device can be configured with a.
[0008]
In this purification method and the purification device, compressed air is intermittently pulsed at a short interval with ultrahigh pressure (for example, 2 to 10 atm) through a high-pressure intermittent injection device together with moisture supplied from the reflux device ( For example, since the injection well is injected into the contaminated ground at a period of 1/30 to 1/5 HZ), the compressed air mixed with moisture is explosively blown into the contaminated ground. For this reason, the compressed air mixed with moisture injected from the injection well into the contaminated ground can be diffused and reached to a wider range.
[0009]
On the other hand, the water in the contaminated ground recovered from the suction well is once stored in the reflux device and then returned from the injection well to the contaminated ground through the high-pressure intermittent injection device, thereby causing the contaminated ground to the suction well to return. A return path is constructed from the device to the injection well to the contaminated ground. For this reason, the water | moisture content contained in compressed air can flow in the contaminated ground, can activate a decomposing microorganism over a wide range , and can improve soil quality on the average.
[0010]
Moreover, it is desirable to replenish the above-mentioned reflux device with groundwater recovered from the pumping well inserted into the aquifer.
In this purification method, when the water recovered from the ground is insufficient, it is possible to always ensure the water to be injected into the contaminated ground by replenishing the reflux device with groundwater. Since groundwater is used for replenishing water in this way, water can be self-supplied. Further, it is desirable to supply water from the reflux device to a reservoir formed on the ground of the contaminated ground, and to infiltrate the water from the reservoir into the contaminated ground.
In this purification method, sufficient moisture can be supplied into the ground by the moisture permeated from the reservoir formed on the ground, and this permeated moisture is the moisture of the reflux device, so that the moisture circulation path through the reservoir is Thus, the fluidization of moisture in the contaminated ground is further promoted.
In addition, at least one purification promoting component of an oxygen-containing substance such as hydrogen peroxide or ozone, a decomposing microorganism, or a nutrient source that activates the decomposing microorganism may be added to the water.
In this purification method, purification sources such as nutrient sources and decomposing microorganisms can flow into the contaminated ground together with moisture contained in the compressed air, so that the input amount of the nutrient sources can be reduced and used efficiently. Become.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 shows an embodiment of a method for purifying contaminated ground according to the present invention, and FIG. 1 is a cross-sectional view schematically showing a main part of the purification device.
[0012]
The basic method of the purification method for contaminated ground according to the present invention is to pulse moisture and, if necessary, other purification promoting components from the injection well 14 inserted into the contaminated ground 12 together with ultrahigh pressure compressed air at short intervals. The water in the contaminated ground 12 is recovered from the suction well 18 inserted into the contaminated ground 12 and temporarily stored in the reflux device 20. It is to return to the contaminated ground 12 from the injection well 14.
[0013]
That is, the purification method for contaminated ground according to the present invention can be achieved with the purification device 10 shown in FIG. This purification apparatus 10 shows one embodiment for achieving the purification method of the present invention, and an injection well 14 inserted into the contaminated ground 12 and an ultrahigh pressure compressed air attached to the upper end of the injection well 14. The high-pressure intermittent injection device 16 that supplies the injection well 14 intermittently in a pulse form at short intervals, the suction well 18 inserted into the contaminated ground 12, and the contaminated ground 12 sucked from the suction well 18 A recirculation device 20 is provided that stores water once and supplies other purification promoting components to the compressed air as needed together with the water.
[0014]
The contaminated ground 12 is a waste landfill site or a natural ground in which pollutants are diffused. In this embodiment, a groundwater aquifer 22 exists below the contaminated ground 12. The injection well 14 and the suction well 18 are arranged at a predetermined interval, and each is inserted into the contaminated ground 12 by boring vertically. Each of the injection well 14 and the suction well 18 is formed of a pipe having a predetermined length, and the lower end opening of the injection well 14 serves as a spout 14a, and moisture is sucked into the lower end portion of the suction well 18 over a predetermined section. For this purpose, a slit and a porous opening 18a are formed. Further, the upper ends of the injection well 14 and the suction well 18 are in a state of projecting to the ground surface.
[0015]
The high-pressure intermittent injection device 16 is attached to the upper end of the injection well 14, and the high-pressure intermittent injection device 16 is supplied with ultra-high pressure (for example, 2 to 10 atm) compressed air generated by an air compressor 24 through a supply pipe 24a. Is introduced through. Although not shown, the high-pressure intermittent injection device 16 includes a tank that stores compressed air and an intermittent valve that intermittently discharges compressed air in the tank. When the pressure in the tank exceeds a predetermined pressure, the intermittent valve Is instantaneously opened to discharge high-pressure air, and when the pressure in the tank is reduced by this discharge, the intermittent valve is instantaneously closed.
[0016]
Therefore, while compressed air is supplied from the air compressor 24, the high-pressure intermittent injection device 16 intermittently pulsates the high-pressure air in the tank at short intervals (for example, a period of 1/30 to 1 / 5HZ). ) Continue to discharge. Then, when the ultra-high pressure air pulsed at short intervals is supplied to the injection well 14, the contaminated ground 12 is instantaneously provided at a predetermined intermittent timing from the outlet 14 a at the lower end of the injection well 14. It will be continuously infused. In addition, the injection is explosively blown out from the jet outlet 14a with a cavitation effect, and the blowing energy at this time becomes remarkably large.
[0017]
A suction pump 28 is connected to the upper end of the suction well 18 via a gas-liquid separator 26, and the air separated by the gas-liquid separator 26 is sent from the suction pump 28 to the purification device 30 to be harmless. And then released into the atmosphere. On the other hand, the water separated by the gas-liquid separator 26 is supplied to the reflux device 20 and temporarily stored. As necessary, the reflux device 20 is supplied with a purification promoting component such as a nutrient source for decomposing microorganisms and a new decomposing microorganism to the stored water. And the stored water in this recirculation | reflux apparatus 20 is supplied to the supply path of compressed air by the pipe line 20a via the flow regulating valve 32, and the pipe line 20a is the discharge side of the said high-pressure intermittent injection apparatus 16 in the said embodiment. It is connected to the upper end of the injection well 14. Therefore, the moisture of the reflux device 20 is added to the compressed air discharged and discharged from the high-pressure intermittent injection device 16, and the compressed air containing this moisture becomes mist-like in the contaminated ground 12 from the lower portion of the injection well 14 and explosively. Will be supplied.
[0018]
The purification promoting component promotes purification of pollutants such as air, oxygen-containing substances such as hydrogen peroxide (H ₂ O ₂ ) and ozone (O ₃ ), decomposing microorganisms, and nutrient sources that activate the decomposing microorganisms. It is an ingredient. Particularly representative examples of the pollutants include organochlorine compounds, oils, solvents, volatile substances, and heavy metals such as cadmium.
[0019]
Air promotes the activation of aerobic microorganisms by the oxygen contained in this, and H ₂ O ₂ has the effect of exfoliating oil from the soil particles of the oil-contaminated soil by bubbles when oxygen is generated. After decomposition, no extra material remains and can be easily injected as a mist. O ₃ has a better oxidation efficiency. As nutrient sources, nutrient salts suitable for growing decomposing microorganisms and components suitable for activating these degrading microorganisms are used. For example, nutrient salts maintain the life of organisms such as phosphorus, nitrogen, potash and silicon. There are some major elements necessary for this and trace elements such as manganese that are mainly taken as salts other than carbon, hydrogen and oxygen.
[0020]
As a decomposing microorganism, a methane-utilizing bacterium that aerobically decomposes (oxidizes) TCE (trichloroethylene) is known. In this methane-utilizing bacterium, methane is used as a nutrient source. In addition, as other degrading microorganisms used for TCE degradation, toluene-utilizing bacteria, phenol-utilizing bacteria, nitrifying bacteria, propane-oxidizing bacteria, isopropylene-oxidizing bacteria, etc. are known, and nutrient sources suitable for each are used. It is done. Of course, it is needless to say that a nutrient source suitable for decomposing microorganisms that purify the contaminant is used for other contaminants in the contaminated ground 12 without being limited to TCE.
[0021]
In addition, it is desirable to provide a pumping well 34 that penetrates the contaminated ground 12 and reaches the groundwater aquifer 22. A pumping pump 36 is connected to the upper end of the pumping well 34 protruding from the ground, and groundwater recovered by the pumping well 34 is supplied to the reflux device 20 through a water purification device 38. At this time, the pumping well 34 is not necessarily required when the aquifer 22 is not present in the contaminated ground 12 to be purified, or when the water is sufficiently contained in the contaminated ground 12.
[0022]
Furthermore, it is desirable to form a reservoir 40 on the ground of the contaminated ground 12. The reservoir 40 is left in an excavated state without finishing the inner surface with concrete or the like, and the accumulated water is naturally permeated into the contaminated ground 12 from the bottom surface and the side surface. The reservoir 40 is supplied with water from the reflux device 20 and stored therein.
[0023]
Hereinafter, the operation of the purification method for contaminated ground according to the present embodiment will be described. The compressed air is injected by driving the air compressor 22 of the purification device 10 and supplying the ultrahigh pressure compressed air to the high-pressure intermittent injection device 16. From the spout 14a of the well 14, it is pulsed at short intervals and injected into the contaminated ground 12 with a predetermined intermittent timing. At this time, by opening the flow rate adjustment valve 32, the moisture stored in the reflux device 20 and the purification promoting component added as necessary are introduced into the contaminated ground 12 from the injection well 14 together with the compressed air. Injected. At this time, the compressed air mixed with moisture injected into the contaminated ground 12 is made into pulses at short intervals by the high-pressure intermittent injection device 16 and is injected into the contaminated ground 12 with a super-high pressure at a predetermined intermittent timing. Therefore, it is explosively blown into the contaminated ground 12 from the jet outlet 14a with a cavitation effect.
[0024]
Therefore, the compressed air mixed with moisture can reach the farther and wider area together with the purification promoting component contained in the moisture, and can activate the decomposing microorganisms in the contaminated ground 12 to promote the purification. Moreover, since the explosive injection of the compressed air is repeated intermittently, the accumulation state of the contaminated ground 12 changes every time the injection is performed, and the path of the purification promoting component tends to be random, and the entire contaminated ground 12 Is purified almost uniformly.
[0025]
On the other hand, the water in the contaminated ground 12 collected from the suction well 18 is temporarily stored in the reflux device 20, and the water in the reflux device 20 is supplied to the compressed air, and the contaminated ground 12 is passed through the high-pressure intermittent injection device 16. In order to return to the inside, a reflux path of the contaminated ground 12 to the suction well 18 to the reflux device 20 to the injection well 14 to the contaminated ground 12 is configured. For this reason, the moisture contained in the compressed air flows in the contaminated ground 12 together with the purification promoting components such as nutrient sources and decomposing microorganisms, and the purification promoting components are spread throughout the contaminated ground 12 so that the decomposing microorganisms are spread over a wide area. Can be activated. Accordingly, in combination with the explosive blowing function by the high-pressure intermittent injection device 16, the cleanable area of the contaminated ground 12 with respect to one injection well 14 is remarkably expanded, so the number of injection wells 14 in the entire purification device 10. As well as running costs can be reduced.
[0026]
Further, since the purification promoting component supplied to the contaminated ground 12 along with the flowing water is circulated, the amount of the purification promoting component such as a nutrient source or a decomposing microorganism can be reduced. Moreover, since the water | moisture content supplied to the said compressed air can recycle | reuse the water | moisture content collect | recovered from the contaminated ground 12, water can be saved.
[0027]
By the way, in this embodiment, the pumping well 34 inserted in the aquifer 22 is provided, and since the groundwater recovered from the pumping well 34 can be replenished to the reflux device 20, the moisture in the contaminated ground 12 is reduced. Thus, when the water in the reflux device 20 supplied from the suction well 18 is insufficient, the water can be self-supplied using the groundwater under the contaminated ground 12.
[0028]
Further, in this embodiment, since water is supplied from the reflux device 20 to the reservoir 40 formed on the ground of the contaminated ground 12, water can permeate into the contaminated ground 12 from the reservoir 40. 12 can supply a sufficient amount of moisture, and the permeated moisture is the moisture of the reflux device 20, so that a moisture circulation path passing through the reservoir 40 is configured to further promote fluidization of moisture.
[0029]
【The invention's effect】
As described above, in the contaminated ground purification method and the purification device according to claims 1 and 5 of the present invention, the compressed air mixed with moisture from the injection well into the contaminated ground is pulsed in a short interval at an ultrahigh pressure. Since the water is sprayed intermittently, the water is atomized together with the compressed air and blown explosively from the outlet into the contaminated ground with a cavitation effect. Can be reached. On the other hand, the water in the contaminated ground recovered from the suction well is once stored in the reflux device and then returned from the injection well to the contaminated ground via the high-pressure intermittent injection device. It circulates through the reflux path of ~ injection well ~ contaminated ground, and allows moisture contained in the compressed air to flow in the contaminated ground . Therefore, in combination with the explosive blowing function by the high-pressure intermittent injection device, activation of decomposing microorganisms can be achieved in a wider area of the contaminated ground, and average soil quality improvement should be performed as much as possible. In addition, the ability to clean up contaminated ground can be greatly improved.
[0030]
Moreover, in the purification method of the contaminated ground shown in Claim 2 of this invention, since the groundwater collected from the pumping well inserted in an aquifer is supplemented to the said reflux apparatus, when the water collect | recovered from the ground is insufficient In addition, it is possible to replenish the reflux device with groundwater and to always ensure the water to be injected into the contaminated ground, and to self-supply water.
[0031]
Further, in the method for purifying contaminated ground according to claim 3 of the present invention, water is supplied from the reflux device to a reservoir formed on the ground of the contaminated ground, and water penetrates into the contaminated ground from the reservoir. Sufficient water can be supplied to the water, and since the permeated water is the water in the reflux device, a water circulation path through the reservoir can be formed to further promote the fluidization of the water.
Furthermore, in the purification method for contaminated ground according to claim 4 of the present invention, purification promoting components such as decomposing microorganisms and their nutrient sources are added to the moisture contained in the compressed air in the form of a mist to flow in the contaminated ground. Therefore, it becomes possible to use the nutrient source efficiently by reducing the input amount of the nutrient source.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing one embodiment of a purification apparatus for contaminated ground according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Purification apparatus 12 Contaminated ground 14 Injection well 14a Spout 16 High pressure intermittent injection apparatus 18 Suction well 20 Returning apparatus 34 Pumping well 40 Reservoir

Claims (5)

From the high pressure intermittent injection device provided at the upper end of the injection well inserted into the contaminated ground , 2-10 atm of ultra high pressure compressed air is pulsed at short intervals and intermittently supplied to the injection well , While adding water to the compressed air from the top of the injection well that is the discharge side of the high-pressure intermittent injection device, the water is atomized together with the compressed air and injected into the contaminated ground from the opening of the injection well,
Moisture in the contaminated ground from the slit or perforated openings formed over a predetermined interval in the suction well inserted into the contaminated soil was collected,
A method for purifying contaminated ground, wherein the recovered water is temporarily stored in a reflux device and then added to the compressed air from above the injection well and returned to the contaminated ground.   2. The method for purifying contaminated ground according to claim 1, wherein the reflux device is supplemented with groundwater recovered from a pumping well inserted into an aquifer.   3. The method for purifying contaminated ground according to claim 1 or 2, wherein water is supplied from the reflux device to a reservoir formed on the ground of the contaminated ground, and water is permeated into the contaminated ground from the reservoir. The oxygen-containing substance such as hydrogen peroxide and ozone, a decomposing microorganism, and at least one purification promoting component of a nutrient source that activates the decomposing microorganism are added to the moisture. A method for purifying contaminated ground according to crab. An injection well formed with a pipe and inserted into the contaminated ground , with the opening of the pipe as a spout ;
A high-pressure intermittent injection device that is attached to the upper end of this injection well and supplies the ultra-high pressure compressed air of 2 to 10 atm to the injection well intermittently in a pulsed manner at short time intervals;
A suction well which is formed of a pipe and is inserted into the contaminated ground, and a slit or a porous opening for sucking moisture in the contaminated ground is formed over a predetermined section at the lower end of the pipe ; ,
A reflux device that temporarily stores the moisture in the contaminated ground sucked from this suction well, and supplies this moisture to the upper part of the injection well that is the discharge side of the high-pressure intermittent injection device ;
A device for purifying contaminated ground, characterized by comprising:

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