JP2011000567A - Method and system for decomposing/purifying soil and groundwater polluting substances - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a practical purification method which can purify substances polluting soil and ground water actually in a short time.SOLUTION: The method practiced in the site where soil or ground water is polluted by pollutants includes: a step in which an injection well 1 and a pumping well 2 are formed so that injection water passes through a pollution region, and ground water containing pollutants is pumped up from the pumping well 2; a step in which the pumped water is led into a bioreactor 15 on the ground for propagating microorganisms including the microorganisms in soil of the site to decompose the pollutants; and a step in which an apparatus 26 for generating ultrafine bubbles is arranged on the side of the injection well 1, and ultrafine bubbles are introduced into the decomposed pumped water and injected from the injection well 1.

Description

  The present invention relates to a method and system for purifying soil and groundwater contaminants.

Conventionally, development research on bioremediation has been actively conducted as a purification method for removing contaminants from soil and groundwater. Bioremediation is a technology that removes pollutants using microorganisms in situ without excavating soil.
As a conventional purification method using bioremediation, several wells are drilled near the underground contamination area, and various substrates (oxygen, nutrients, etc.) that enhance the activity of microorganisms are added to the groundwater pumped from the pumping pipe. A method of repeating the process of returning to the injection tube excavated to the side is known (see Patent Document 1).
In recent years, a configuration has been proposed in which oxygen is supplied to soil by introducing ultrafine bubbles into the injected water.

JP-A-10-216696

Even with the above prior art, the pollutants that have been pumped up, such as oil that has been peeled off and separated from the soil, etc., must finally be disposed of in an industrial waste, and only the contamination will be transferred. It is not a fundamental solution to environmental pollution problems. In particular, in actual bioremediation, it is difficult to process separated oils such as gasoline, light oil and heavy oil.
In addition, the actual contaminated soil is contaminated by many entangled pollutants, and by simply injecting ultra-fine bubbles, each area of the contaminated soil is refined and highly effective depending on the contamination status. It is difficult to process.

The present invention has been made in view of the above problems, and an object of the present invention is to enhance the fermentation and decomposition functions of microorganisms separated from soil and groundwater, and to completely generate industrial waste related to pollutants in a short period of time. It is an object of the present invention to provide a system that can be eliminated or extremely reduced.
In addition, the purpose of the present invention is to develop a bioreactor system that utilizes the fermentation and decomposition capabilities of microorganisms with pollutants such as oil recovered by pumping water, so that it can be practically purified in a short time. Is to provide.
In addition, the subject of invention other than having described above, its solution means, and its effect are demonstrated in detail in description in the specification mentioned later.

Although the present invention can be expressed in many ways, for example, typical ones are configured as follows. In each of the following inventions, each symbol is shown as an example for easy understanding of the correspondence with the embodiment described later, and each component of the present invention corresponds to the configuration related to the symbol described in the embodiment. It goes without saying that it is not limited.
The method for decomposing and purifying soil and groundwater pollutants according to the present invention is a method for performing in situ where soil or groundwater is contaminated with pollutants,
A step of providing an injection well 1 and a pumping well 2 so that the injected water passes through the contaminated area, and pumping groundwater containing the pollutant from the pumping well 2;
A process of introducing the pumped water to a ground bioreactor 15 for growing microorganisms including soil microorganisms in its original position to decompose pollutants;
A step of placing the ultrafine bubble generating device 26 on the injection well 1 side, injecting ultrafine bubbles into the decomposed pumped water and injecting from the injection well 1;
It is characterized by including.

  According to the present invention, the pollutant can be almost completely decomposed in a short time by introducing the pumped water to the above-ground bioreactor for growing microorganisms containing soil microorganisms at least in situ. Therefore, industrial waste related to pollutants can be significantly reduced. Regardless of whether it is in the soil where anaerobic microorganisms or aerobic microorganisms are working, an ultrafine bubble generator is placed on the injection well side of the circulating water path to introduce the ultrafine bubbles into the injection well. It is possible to increase the decontamination function of the pollutant to the soil components and increase the purification rate by the synergistic interfacial effect of the ultrafine bubbles and the microorganisms.

In the above configuration, the microorganisms grown in the bioreactor 15 can be injected from the injection well 1 together with ultrafine bubbles.
With this configuration, the microorganisms present in the contaminated soil are gathered with bacteria that have a high function of decomposing the pollutants, so that the microorganisms in the soil are grown in the bioreactor and injected from the injection well together with ultrafine bubbles. This can increase the rate of decomposition in the soil.
In the above configuration, in the decomposition process of the bioreactor 15, in addition to the in-situ microorganisms, microorganisms selected by the operator in consideration of the types of contaminants can be used.
If it is this structure, the decomposition speed in a bioreactor can be raised by preparing the microorganisms suitable for decomposition | disassembly of a pollutant based on an operator's experience.

In the above-described configuration, the injection side buffer tank 12 is provided on the injection port side of the injection well 1, the ultrafine bubble generator 26 is provided in the injection side buffer tank 12, and the ultrafine bubbles are formed in the injection side buffer tank 12. The content of can also be adjusted.
With this configuration, by providing an injection-side buffer tank according to the state of contaminant distribution, even if it is contaminated soil at the same in-situ location, the conditions of the injection solution can be changed for each narrow contaminated area, and detailed purification processing can be performed. It can be performed.

In the above configuration, a high concentration microorganism supply device 27 may be provided in the injection side buffer tank 12 to supply microorganisms selected by the operator into the injection side buffer tank 12.
If it is this structure, degradation conditions will be raised by adding microorganisms newly, and it will become possible to decompose in a short time.

The system for decomposing and purifying soil and groundwater pollutants of the present invention includes an injection well 1 and a pumping well 2 provided so that the injected water passes through the contaminated area in the original position where the soil or groundwater is contaminated with the contaminant. When,
A ground bioreactor 15 through which the pumped water obtained by the pumping well 2 is guided and grows microorganisms including soil microorganisms at least in its original position;
An injection-side buffer tank 12 connected to the injection well 1 corresponding to the state of distribution of the contaminants;
An ultrafine bubble generator 26 for supplying ultrafine bubbles to the injection side buffer tank 12,
It is provided with.

In the above configuration, a microorganism supply device 27 that supplies microorganisms selected by an operator to the injection side buffer tank 12 may be provided.
In the above configuration, a pumping-side buffer tank 13 is provided in the pumping well 2, and the ultrafine bubble generating device is based on detection information of the pollutant detecting device 24 attached to the bioreactor 15 or the pumping-side buffer tank 13. 26. At least one of the microorganism supply devices 22 and 27 may be provided with a control device 25 that outputs drive information.

According to the present invention, the fermentation and decomposition functions of the microorganisms of pollutants separated from soil and groundwater can be enhanced, and the generation of industrial waste of contaminated oil can be completely eliminated in a short period of time.
In addition, it is possible to provide a practical system that can purify contaminants of soil and groundwater in a short time.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 is a schematic configuration diagram showing a system for decomposing and purifying soil and groundwater contaminants according to the present invention, FIG. 2 is a diagram showing an example of a plane arrangement of an injection well and a pumping well, and FIG. 3 is a cross-sectional view of the injection well and the pumping well. FIG. 4 is a view showing the state of injection and inhalation in the action part of each well.
This pollutant decomposition and purification system is carried out in situ where soil or groundwater is contaminated with pollutants.
As shown in FIG. 2, first, the injection well 1 and the pumping well 2 are formed in a lattice shape in plan view so as to pass through the contaminated region 6. The arrangement interval between the injection well 1 and the pumping well 2 is set such that the density is high when the contamination concentration is high, and the density is low when the contamination concentration is low, but FIG. Moreover, as shown in FIG. 4, each well 1 and 2 is normally comprised with the pipe | tube, and many holes 3 are provided in the surrounding wall of the action part (mainly tip part area) of each well 1 and 2. As shown in FIG. The injected water 4 radiated from the holes 3 of the injection well 1 flows through the soil and is sucked from the holes 3 on the peripheral wall of the pumping well 2.

  As shown in FIGS. 1 and 3, the underground structure is mainly composed of a groundwater layer 7 through which groundwater flows, a contaminated soil layer 8 above it, and an impermeable layer 9 below the groundwater layer 7. Yes. Most of the pollutants are present in the contaminated soil layer 8, and in particular, a large amount is present at the boundary portion of each layer. For example, contaminants such as oil are easily adsorbed by clay and organic matter in the soil, and the contaminants are gradually separated into the groundwater, so that the groundwater layer 7 also contains the contaminants. Therefore, the injection well 1 and the pumping well 2 are excavated to a depth that sufficiently reaches the underground groundwater layer 7. Further, the purification treatment area is partitioned by the water shielding wall 10 so as not to diffuse around.

As shown in FIG. 1, the purification system according to the present embodiment includes an injection well 1 and a pumping well 2, an injection-side buffer tank 12 that communicates with the injection well 1, and a pumping-side buffer tank that communicates with the pumping well 2. 13, a sewage tank 14 for temporarily storing pumped water from the pumping side buffer tank 13, a bioreactor 15 for decomposing pollutants, a water treatment device 16, and a water storage tank for storing water treated by the water treatment device 16 17.
In this configuration, most of the pumped water from the pumping well 2 is reinjected into the injection well 1 through the pumping side buffer tank 13, the sewage tank 14, the bioreactor 15, the water treatment device 16, the water storage tank 17, and the water injection side buffer tank 12. As a result, the circulation line 18 is formed.

A valve device 29 and a water injection pump 30 are provided between the injection well 1 and the water injection side buffer tank 12. A valve device 31 and a water injection pump 32 are also provided between the pumping well 2 and the pumping side buffer tank 13.
The injection-side buffer tank 12 is provided to change the nature and state of the water injected into each injection well 1, and a microbe that injects a microbe selected by the ultrafine bubble generator 26 and drive information described later. A supply device 27 is provided. In many cases, a plurality of microorganism supply devices 27 are provided. On the other hand, the pumping side buffer tank 13 is provided if necessary. The pumping-side buffer tank 13 is a water level meter or a flow meter (not shown) for detecting the pumping amount of each pumping well 2 and the pollutant concentration, and a pollutant detection device 24 for identifying the pollutant concentration and pollutants. Is provided.

In the configuration shown in FIG. 1, an example in which one injection-side buffer tank 12 is provided for one injection well 1 is shown, but one injection-side buffer is provided for a plurality of injection wells 1. The tank 12 may be communicated. In this case, the injection state of the plurality of injection wells 1 is changed in the same manner in the state of the single injection side buffer tank 12. Similarly, one pumping-side buffer tank 13 may be communicated with a plurality of pumping wells 2. In this case, an average amount of pumped water and an average contamination concentration are detected. The plurality is preferably 2 to 3 in number.
The water treatment device 16 includes an adjustment tank, a flotation separation tank, a sedimentation tank, a sediment residence tank, a filter press (all not shown), and the like.

  The bioreactor 15 is a device for growing microorganisms including soil microorganisms at least in situ. The bioreactor 15 is configured to be capable of almost completely decomposing contaminants such as oil by the action of microorganisms in a short time. The bioreactor 15 according to the present embodiment includes a microbial culture apparatus 20, a microbial fermentation decomposition tank 21, and a microbial supply apparatus 22. The bioreactor 15 is also provided with a contaminant detection device 34. The contaminant detection device 34 detects the type and concentration of the contaminant.

  The bioreactor 15 is for growing microorganisms in the soil contained in the groundwater pumped from the pumping well 2 by the microorganism culturing apparatus 20 and decomposing the microorganisms by fermentation or the like in the microorganism fermentation decomposition tank 21. An appropriate type of bioreactor 15 can be selected and used according to the type of pollutant, and a nutrient source necessary for the growth of the pollutant-degrading bacteria can be added, or the temperature can be increased in the microorganism culture apparatus 20 in the bioreactor 15. The bacteria are propagated by maintaining the oxygen concentration at conditions suitable for the growth of the degrading bacteria.

  The bioreactor 15 has both an anaerobic bioreactor function and an aerobic bioreactor function. For example, when aerobic bacteria and anaerobic bacteria are used, a decomposition tank using ultrafine bubbles is adopted, and a food chain-like aerobic and anaerobic bacteria decomposition function in the decomposition tank or in another decomposition tank To break down pollutants.

The microorganism having the resolution of the pollutant employed in the present embodiment is not particularly limited and is selected according to the pollutant to be decomposed.
For example, examples of main microorganisms are as follows.
Pseudomonas genus, Bacillus genus, Nitrosomonas genus, Escherichia genus, Burkholderia genus, Alcaligenes genus, Acinetobacter genus Acinetobacter Vibrio genus, Nocardia genus, Arthrobacter genus, Micrococcus genus, Lactobacillus genus, Achromobacter genus, Mycobacterium ter , Methylocinus (Methy osinus) genus, Methylomonas (Methylomonas) genus, Berukia (Welchia) genus, Mechiroshisuchisu (Methylocystis) genus, and the like. In addition, the microorganisms to be administered are often used in a mixture of 3 to 15 types. When growing in situ bacteria, more than 100 types of bacteria may be grown.
Regarding microorganisms added to the microorganism supply devices 22 and 27, when the pollutant is an organic chlorine compound such as trichlorethylene or tetrachloroethylene, anaerobic bacteria, anaerobic bacteria separated from soil or anaerobic sludge, for example, methane Bacteria such as producing bacteria, phenol-utilizing bacteria, toluene-utilizing bacteria, ammonia-oxidizing bacteria, and sulfate-reducing bacteria can be used.

  Regarding the control of the system, based on the detection information of the pollutant detection device 24 provided in the pumping-side buffer tank 13, the control device 25 controls the microorganism culture device 20, the microorganism fermentation decomposition tank 21, and the microorganism supply device 22 of the bioreactor 15. Drive information (including drive signals) is output to Moreover, based on the pollutant distribution grasped in advance, the drive information is output to the ultrafine bubble generating device 26 and the microorganism supply device 27 attached to the water injection side buffer tank 12 corresponding to the pollutant region.

The operation of the purification system will be briefly described.
Based on the three-dimensional pollutant distribution information obtained from the boring survey, the insertion form of the injection well 1 and the pumping well 1 is determined as shown in FIG. 2, for example, and attached to the injection well 1 based on the contamination distribution information. The arrangement ratio of the injection side buffer tank 12 to the injection well 1 is determined. For example, in the configuration shown in FIG. 3, one injection-side buffer tank 12 is provided for two injection wells 1. Similarly, the arrangement ratio of the pumping-side buffer tank 13 to the pumping well 1 is also determined.

In this set state, water is injected into the soil or the like from the injection well 1 by the injection pump 30 and ejected as shown in FIG. 4, and the surface active function of the microorganisms containing ultrafine bubbles allows the stone, gravel, The pollutant is peeled off from the soil components such as rocks and sand silt and pumped up from the pumping well 2 together with the pollutant. Then, in the bioreactor 15 through the sewage tank 14, the microorganisms in the soil that live in the soil are propagated by the microorganism culture apparatus 20, and if necessary, the decomposition of the pollutants is concentrated in the microorganism fermentation decomposition tank 21 using the selected microorganisms. To do. In the experiment, it was possible to decompose almost 100% of gasoline, light oil, etc. in the bioreactor 15 by growing microorganisms in the soil living in the contaminated area and adjusting the types of microorganisms selected and added according to empirical rules. It was.
The pumped water from which the pollutants have been removed is stored in the water storage tank 17 via the downstream water treatment device 16 and re-supplied to the injection side buffer tank 12.

On the other hand, from the pollutant detection device 24 of the pumping-side buffer tank 13 provided at a key point on the pumping side of the contaminated area, pumping information (pumping amount, concentration of pollutants, etc.) of pumped water is sent at fixed time intervals or fixed time intervals. Therefore, based on the pumping information, the control device 25 adjusts the operating conditions of each tank of the bioreactor 15 based on a predetermined program (operation table or the like). Further, in order to change the type of microorganisms supplied to the injection-side buffer tank 12 and the presence / absence and amount of ultrafine bubbles while changing the operating conditions of the bioreactor 15, the microorganism supply device 27 and the ultrafine bubble generator 26 are provided. Send drive information.
In this way, by automatically changing the operating conditions of the bioreactor 15 and the conditions of the injection side buffer tank 12 automatically for a certain time or every certain period, the time required for purification at the conventional in-situ position can be significantly shortened. It becomes possible to purify contaminated soil and contaminated groundwater in about one to three months. In addition, since the pollutant can be almost completely decomposed, the expense of disposing it as industrial waste becomes unnecessary, and a large cost reduction can be realized.

FIG. 1 is a schematic configuration diagram illustrating a decomposition and purification system for soil and groundwater contaminants according to an embodiment. FIG. 2 is a diagram showing an example of a planar arrangement of an injection well and a pumping well. FIG. 3 is a diagram showing an example of a cross-sectional arrangement of an injection well and a pumping well. FIG. 4 is a view showing the state of injection and inhalation in the working part of the well.

DESCRIPTION OF SYMBOLS 1 ... Injection well, 2 ... Pumping well, 15 ... Bioreactor, 12 ... Injection side buffer tank, 22.27 ... Microorganism supply apparatus, 24.34 ... Contaminant detection apparatus, 25 ... Control apparatus, 26 ... Ultrafine bubble generation apparatus.

Claims (8)

It is a method performed in situ where soil or groundwater is contaminated with pollutants,
Providing an injection well (1) and a pumping well (2) so that the injected water passes through the contaminated area, and pumping groundwater containing pollutants from the pumping well (2);
A process of decomposing pollutants by guiding the pumped water to a ground bioreactor (15) for growing microorganisms including soil microorganisms in its original position;
A step of disposing an ultrafine bubble generating device (26) on the injection well (1) side, injecting ultrafine bubbles into the decomposed pumped water and injecting from the injection well (1);
A method for decomposing and purifying soil and groundwater contaminants, characterized by comprising: The method for decomposing and purifying soil / groundwater pollutants according to claim 1, wherein microorganisms grown in the bioreactor (15) are injected from the injection well (1) together with ultrafine bubbles. Purification method. The method for decomposing and purifying soil and groundwater pollutants according to claim 1, wherein in the bioreactor (15) decomposition process, the microorganism selected by the operator in consideration of the type of contaminant in addition to the soil microorganisms in situ Decomposing and purifying soil and groundwater pollutants. The method for decomposing and purifying soil and groundwater contaminants according to any one of claims 1 to 3, wherein an injection-side buffer tank (12) is provided on the injection port side of the injection well (1), and the injection side A method for decomposing and purifying soil and groundwater pollutants, wherein an ultrafine bubble generating device (26) is disposed in a buffer tank (12), and the content of ultrafine bubbles is adjusted in the injection side buffer tank (12). 5. The method for decomposing and purifying soil and groundwater contaminants according to claim 4, wherein a high concentration microorganism supply device (27) is provided in the injection side buffer tank (12), and an operator is provided in the injection side buffer tank (12). A method for decomposing and purifying soil and groundwater contaminants that supplies selected microorganisms. An infusion well (1) and a pumping well (2) provided to allow the injected water to pass through the contaminated area at the site where the soil or groundwater is contaminated with the pollutant;
An above-ground bioreactor (15) to which the pumped water obtained by the pumping well (2) is guided and propagates microorganisms including soil microorganisms at least in its original position;
An injection-side buffer tank (12) provided continuously to the injection well 1 corresponding to the distribution of the contaminants;
An ultrafine bubble generator (26) for supplying ultrafine bubbles to the injection side buffer tank (12);
A system for decomposing and purifying soil and groundwater contaminants. The soil / groundwater contaminant decomposition and purification system according to claim 6, wherein a microorganism supply device (27) for supplying microorganisms selected by an operator to the injection side buffer tank (12) is provided. Purification system. The soil / groundwater contaminant decomposition and purification system according to claim 6, wherein a pumping-side buffer tank (13) is provided in the pumping well (2), and the bioreactor (15) or the pumping-side buffer tank (13) is provided. Based on the detection information of the attached pollutant detection device (24), the control device (25) outputs drive information to at least one of the ultrafine bubble generation device (26) and the microorganism supply device (22, 27). ), A system for decomposing and purifying soil and groundwater contaminants.