JP2017209599A - Purification method of oil contaminated soil and purification system thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a purification method of an oil contaminated soil capable of a purification treatment of oil contamination in short time and at low cost, and a purification system thereof.SOLUTION: There is provided a method for purifying an oil contaminated soil at an original position, containing; an oil recovery groove formation process for forming an oil recovery groove 1 on a ground surface 48 of the oil contaminated soil zone; a fine air bubble hot water injection process for injecting hot water containing fine air bubbles 36 to the oil contaminated soil to enhance moisture content contained in the oil contaminated zone; and an oil separation process for flowing oil contaminated water from the oil contaminated soil with enhanced moisture content into the oil recovery groove 1 by the fine air bubble hot water 12 and separating oil from the flown oil contaminated water.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for purifying oil-contaminated soil in situ and a purification system thereof.

  Conventionally, when a gasoline station site, a factory site, or the like is reused, there is a problem that oil such as gasoline, fuel oil, and machine oil contaminates the soil inside and outside the site.

  If such oil-contaminated soil is left as it is, the oil mixed in the soil volatilizes and diffuses to the surroundings, and it may be harmful to the surrounding residents, and when the oil in the soil is released by rainwater, etc. May cause contamination of groundwater and contaminate water quality in the surrounding area. For this reason, if it becomes clear that the soil is contaminated with oil of a specified concentration or higher by a boring survey or the like, it is necessary to perform soil purification treatment as soon as possible.

As a method for such a soil purification treatment, for example, as shown in Patent Document 1, for example, there is a method of excavating soil on site and removing oil by washing to prevent diffusion to the environment.
On the other hand, as shown as an example in Patent Document 2, research on a technique for decomposing and detoxifying oil in soil using microorganisms suitable for oil decomposition, that is, bioremediation for oil treatment, is progressing.

JP-A-9-299924 JP 2001-327955 A

However, in the soil cleaning method, even when a soil cleaning facility is installed locally or when the soil is transported to a soil cleaning plant in another location, if the land area that needs to be cleaned is large, the processing cost becomes extremely high. There is.
Also in bioremediation, a simple method such as injecting oil-treating microorganisms into water and injecting them into soil has a problem that the period required for purification becomes longer. At present, even if half a year to several years are required for the treatment period, a sufficient degree of purification cannot often be obtained, and it is extremely difficult to purify oil-contaminated soil by bioremediation technology.

Apart from the above-mentioned problems of the prior art, the present inventor has found that there are the following problems that must be solved in the purification of oil-contaminated soil. Hereinafter, a description will be given with reference to FIG.
[It is difficult to raise the groundwater level to the oil-contaminated area near the ground in the permeable layer]
In FIG. 6, a partition member 40 such as a steel sheet pile is inserted to the impermeable layer 41, and an injection well 43 and a pumping well 44 reaching at least the aquifer 42 are provided. As shown in FIG. 6, as is conventionally known, the lower oil-contaminated region 45-1 often exists in the water permeable layer 47 slightly above the groundwater level 46.
On the other hand, the upper oil-contaminated region 45-2 may be spread over a wide region of the permeable layer 47 due to seasonal and aging vertical movement of groundwater. Furthermore, since machine oil, fuel oil, etc. leaked from the building site are not affected by rain penetration because they are in the building, there may be a wide range of the upper oil-contaminated region 45-2 at a shallow distance from the ground surface 48. is there. In addition, there are many cases where the oil-contaminated region 45 having a locally high concentration exists in a soil region where the groundwater easily flows and the ground region where the groundwater hardly flows.
As a method for purifying these oil contaminations, it is generally considered that a large amount of water containing a surface active substance is injected from the injection well 43 so that the groundwater level 46 exists in the relatively lower permeable layer 47. The lower oil-contaminated area 45-1 is raised to a water level C1 where the oil is contaminated, and the oil-contaminated water is pumped from the pumping well 44 to separate the oil.

However, it is difficult to raise the groundwater level 46 at the normal position to the water level C1 including the lower oil-contaminated region 45-1, because the amount of injected water flowing out between the steel sheet piles 40 is actually larger. In particular, it is not easy to raise the groundwater level 46 when the groundwater flows in a considerably deep position from the ground surface 48 or when the oil-contaminated soil area to be purified is large.
Furthermore, as shown in FIG. 6, in the purification site where the groundwater level 46 is at a deep position, when the upper oil contaminated area 45-2 exists at a relatively shallow position from the ground surface 48, the upper oil contaminated area 45- It is extremely difficult to recover the oil from the pumping well 44 and purify it by raising the normal groundwater level 46 to the water level C2 where 2 is immersed. That is, in reality, it is impossible to secure the amount of injected water and to consider the outflow of injected water in the gap between the steel sheet piles 40.

[Problem to increase the cost of forming many injection and pumping wells]
In addition, the oil-contaminated region 45 of the soil is often in a state where oil is firmly attached to the soil particles in the region where the groundwater is difficult to flow as described above. In order for water containing a surface-active substance to effectively act on these oil-contaminated areas 45, the conventional in-situ purification method uses an oil-contaminated area 45 in which the interval between the injection well 43 and the pumping well 44 is extremely close. It becomes necessary to do. As a result, it becomes necessary to form a large number of injection wells 43 and pumping wells 44, and there is a problem that the cost for the purification treatment increases. In FIG. 6, reference numeral 49 is a water injection pump, and reference numeral 50 is a pump.

An object of the present invention is to solve the problems of the prior art and the problems found by the inventor.
An example of a specific purpose is as follows.
(A) Provided is a method for purifying oil-contaminated soil and a purification system thereof, which can purify oil contamination in situ in a short period of time.
(B) Provided is a method and system for purifying oil-contaminated soil that can be purified at a lower cost than conventional techniques such as soil washing.
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 is not limited.

The method for purifying oil-contaminated soil according to the present invention is a method for purifying oil-contaminated soil in situ, and an oil recovery groove forming step for forming an oil recovery groove 1 on the ground surface 48 of the oil-contaminated soil area;
A step of injecting hot water containing fine bubbles 36 into the oil-contaminated soil to increase the amount of water contained in the oil-contaminated region;
An oil separation step of separating oil from the oil-contaminated water that has flowed into the oil recovery groove 1 after the oil-contaminated water is caused to flow from the oil-contaminated soil with the increased water content by the fine bubble warm water 12; It is characterized by including.

The fine bubble hot water means “hot water containing fine bubbles having a size called microbubble or nanobubble”.
If it is this structure, in the state which increased the amount of moisture contained in an oil pollution area | region by the fine bubble warm water injection | pouring process, oil can be peeled from a soil particle by a fine bubble, and it can be made to float. This is because these fine bubbles have a high permeation effect for entering between the soil particles and a high effect of capturing and floating oil. As a result, even if the oil recovery groove is dug to a relatively shallow depth from the ground surface, the oil can flow in and float well.
Furthermore, since the fine bubbles are formed in the warm water, the action of separating and floating the oil from the soil particles is high, so that the oil recovery effect can be increased.

The method for purifying oil-contaminated soil according to the present invention is characterized in that the lower limit of the gas-containing concentration of the fine bubbles is set to about 160% of the limit dissolution concentration.
As the “fine bubble gas”, air is usually used from the viewpoint of cost. However, for example, in order to activate the activity of aerobic bacteria in the soil, oxygen gas may be selected as a fine bubble gas, or various gas gases may be injected for various reasons. The upper limit of the limit dissolution concentration is preferably as high as possible. However, warm water is sometimes used, and in many cases, it cannot be increased so much even if the fine bubble generator is operated for a long time.
With this configuration, the present inventor has confirmed that if the lower limit of the limit dissolution concentration is set to about 160%, it is possible to generate fine bubble warm water having a sufficient effect of oil contamination purification. And if it is this fine bubble warm water, a lot of air etc. which cannot be included on the conditions of the conventional soil water can be included. With this configuration, it is possible to increase the amount of oil flowing into the oil recovery groove by strongly peeling off oil pollutants adhering to the various particles constituting the contaminated soil by the penetration and floating action of fine bubbles.

In the method for purifying oil-contaminated soil according to the present invention, when the fine bubble warm water 12 is generated, a microbubble generator 23 of a pipeline pressurization method is used, and the fine bubble generator 23 of the method is used a plurality of times. The concentration of the gas is achieved by repeatedly passing water.
If it is this structure, the content concentration of the said gas can be easily achieved by allowing water to repeatedly pass through the micro-bubble generator of a line pressurization method.

In the method for purifying oil-contaminated soil according to the present invention, the hot water is naturally made by the action of pressurizing water by repeatedly passing water through the microbubble generating device 23 of the pipe pressurization method a predetermined number of times. It is characterized by that.
If it is this composition, while allowing water to pass through a micro-bubble generator of a line pressurization method repeatedly, while being able to achieve the concentration concentration of the above-mentioned gas, it can be made natural to the above-mentioned preferred warm water, Further, it is not necessary to separately provide a water heating means, and the configuration is simplified.
In addition, by adopting a method of repeatedly passing the microbubble generator through the microbubble generator multiple times compared to the case where the microbubble generator is allowed to act on preheated warm water, the microbubbles are generated in the process of increasing the water temperature. Since it is a structure that is naturally injected into water, it is expected that the release of fine bubbles from the water during the process of raising the temperature of the water will be reduced, increasing the possibility of effectively raising the gas content concentration in hot water Can do.

In the method for purifying oil-contaminated soil according to the present invention, in the step of injecting the fine bubble warm water, when the fine bubble warm water 12 is injected into the oil-contaminated soil, the water is injected into the outer peripheral surface of the groove injection pipe 3. The length L1 in the longitudinal direction of the groove injection pipe 3 inserted into the oil-contaminated soil is 3 m to 3 mm. The groove injection pipe 3 has a transverse diameter of 1 inch to 3 inches.
With this configuration, the injection of fine bubble warm water that can increase the amount of water contained in the contaminated soil is very simple and inexpensive compared to the configuration of conventional injection wells that are costly to form in the soil. Can be configured. The reason is that, for example, an inexpensive pipe such as a vinyl chloride pipe is used, and only a configuration in which a fine opening is provided on the outer peripheral wall thereof can be used as a groove injection pipe. Moreover, this purification method can be implemented only by driving the groove injection pipe from the ground of the contaminated soil and pumping the fine bubble warm water with a pump or the like. That is, the installation cost and the operation cost can be reduced as compared with the case where the same number of conventional injection wells as the groove injection pipes according to the present invention are provided.

The method for purifying oil-contaminated soil according to the present invention includes a fine bubble warm water sprinkling step of sprinkling the fine bubble warm water 12 from the ground surface 48 of the oil contaminated soil.
If it is this structure, the time which raises the moisture content contained in oil-contaminated soil can be shortened by providing a fine bubble warm water sprinkling process with a fine bubble warm water injection | pouring process. Or it is possible to wet not only the injection point of the fine bubble warm water injection pipe but also the fine bubble warm water from the ground surface of oil-contaminated soil so that it soaks into the soil. It is possible to enhance the effect of oil separation and floating and oil recovery in the existing oil contaminated area.

In addition to the above configuration, the method for purifying oil-contaminated soil according to the present invention reaches at least the aquifer 42 and reaches the aquifer 42 and injects the microbubble warm water 12 and at least the aquifer 42. A fine bubble warm water pumping well 15 for pumping oil-contaminated water is separately provided to inject the fine bubble warm water 12 from the fine bubble warm water injection well 14 into the permeable layer 47, and the fine bubble warm water pumping well 15 It is characterized by pumping contaminated water containing oil separated from the water.
If it is this composition, the 1st oil levitation channel in which the fine bubble warm water which diffuses from the injection pipe for grooves flows from the comparatively near the ground surface flows into the oil recovery ditch is the one using the levitation action near the ground water of another system. A two-oil floating channel can be formed. That is, as the second polluted water flow path, the micro-bubble hot water pumping well can form a flow path that flows from the oil-contaminated region around the micro-bubble hot water pumping well into the micro-bubble hot water pumping well. In combination, oil-contaminated soil can be purified efficiently.
In addition, the structure for implement | achieving each above-mentioned method comprises a system or an apparatus. That is, in the embodiments described later, each of the above-described methods can be recognized as the configuration of the corresponding system and apparatus.

The purification system for oil-contaminated soil according to the present invention is a system that provides the following components for purifying oil-contaminated soil in situ,
(A) an oil recovery groove 1 provided on the ground surface 48 of the oil-contaminated soil area;
(B) a fine bubble generator 23 for generating fine bubbles in water;
(C) At least before the injection into the oil-contaminated soil, the fine bubble warm water generating means 24 for warming the water containing the fine bubbles;
(D) Fine bubble warm water injection means 3 for injecting the fine bubble warm water 12 generated by the fine bubble warm water generation means 24 into the oil-contaminated soil;
(E) a pump 19 for applying pressure to the fine bubble hot water 12 from the fine bubble warm water injection means 3 and sending it out;
(F) a pump 6 for taking out oil-contaminated water flowing into the oil recovery groove 1 together with water from the oil recovery groove 1;
(G) an oil separator 29 for separating oil from the oil-contaminated water that has flowed into the oil recovery groove 1 together with water;
It is characterized by including at least.
If it is this structure, compared with the conventional construction method, since oil in soil can be collect | recovered in large quantities from an oil collection groove | channel, while being able to shorten a purification period, oil-contaminated soil can be purified cheaply.

The oil-contaminated soil purification system according to the present invention is for the microbubble hot water injecting means 3 for grooves having a plurality of openings 10 having a width of 2 mm to 5 mm for injecting injected water on the outer peripheral surface and having a bottom. The longitudinal length L1 of the groove injection pipe 3 constituted by the injection pipe 3 and inserted into the oil-contaminated soil is 3 to 5 m, and the transverse diameter of the groove injection pipe 3 is 1 inch. It is characterized by having a configuration of ˜3 inches.
With this configuration, installation cost and operation cost can be greatly reduced.

In the oil-contaminated soil purification system according to the present invention, the fine bubble generating device 23 is configured by a device that generates fine bubbles by a pipe pressurization method, and the fine bubble warm water generating means 24 contains the fine bubble warm water 12. A feed flow path 26 and a return flow path 27 are provided so as to be repeatedly circulated a plurality of times between the injection buffer tank 25 and the fine bubble generator 23 and the injection buffer tank 25.
If it is this structure, the gas content density | concentration in warm water can be raised effectively.
The oil-contaminated soil purification system according to the present invention is characterized in that a water sprinkler 28 is provided for sprinkling the fine bubble warm water 12 generated by the fine bubble warm water generating means 24 from the ground surface 48.
With this configuration, the amount of water contained in the oil-contaminated soil can be increased at a low cost.

The purification system for oil-contaminated soil according to the present invention has a branched pipe 39 for supplying the fine bubble warm water 12 from one fine bubble warm water generation means 24 to the plurality of fine bubble warm water injection means 3. Features.
If it is this structure, while being able to supply fine bubble warm water to a wide area, a structure can be simplified and it can comprise at low cost.
The purification system for oil-contaminated soil according to the present invention includes a microorganism supply device 33 that adds microorganisms that decompose or separate oil to the fine bubble warm water 12 generated by the fine bubble warm water generation means 24.
If it is this structure, the purification | cleaning period of oil-contaminated soil can be shortened by making the microbubble warm water contain the microorganisms suitable for exfoliation of oil and a soil particle, flotation, or decomposition | disassembly of oil itself. In particular, by injecting fine bubble warm water, it is possible to bring it close to the oxygen concentration and temperature at which the injected microorganisms can actively propagate, and the purification treatment of oil-contaminated soil can be carried out effectively and continuously.

  As described above, according to the present invention, it is possible to provide a method for purifying oil-contaminated soil and a system for purifying the oil-contaminated soil that can purify oil contamination in situ in a short period of time. Moreover, the purification method of oil-contaminated soil and its purification system could be provided at low cost compared with conventional techniques such as soil washing.

It is a typical longitudinal section showing an example of oil pollution soil which shows a purification method and a purification system of oil pollution soil concerning this embodiment. It is a figure which shows an example of the purification method and purification system of the oil-contaminated soil which concern on this embodiment, and is the schematic described including each structure installed on the ground. It is a top view which shows an example of the purification method and system of oil-contaminated soil comprised by the oil collection | recovery groove | channel and the injection pipe for grooves. It is a longitudinal cross-sectional view which shows an example of the state which inserted the injection pipe for grooves employ | adopted by this embodiment in the soil. (A) (b) is a figure for demonstrating the separation effect and the floating effect between the soil particle and oil by the effect | action of microbubble warm water, respectively. It is a typical longitudinal cross-sectional view of the oil-contaminated soil for demonstrating the realistic subject in the case of purifying oil-contaminated soil by raising groundwater.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings of FIGS.
FIG. 1 is a schematic side sectional view showing an example of a purification method and a purification system for oil-contaminated soil according to the present invention. FIG. 6 is a premise of basic contamination status, groundwater position, partition members and the like of oil-contaminated soil. The same reference numerals are given to the configurations, and descriptions thereof are omitted.
First, in the configuration of the present embodiment shown in FIG. 1, the characteristic points are mainly the oil recovery groove 1 for the upper oil-contaminated region 45-2 and the inexpensive fine bubbles for supplying the fine bubble warm water 12 into the soil. A groove injection pipe 3 serving as hot water injection means and a groove pumping pipe 4 provided corresponding to the groove injection pipe 3 are provided.
Hereinafter, each component in this embodiment is demonstrated.

(Configuration of oil recovery groove 1)
The oil recovery groove 1 is a groove formed on the ground surface 48 where oil separated from the oil-contaminated area 45 grasped in advance can be expected to float. The oil recovery groove 1 is dug from the ground surface 48 toward the ground, and the planar shape and the shape in the vertical direction are not particularly limited. It is economically preferable to be dug within a range of about 0.5 m to 2.0 m from the ground surface 48 of the oil-contaminated soil. However, the depth and width can be adjusted as appropriate depending on the situation of the contamination site such as the depth at which the upper oil contamination area 45-2 is located.
As shown in FIG. 3 as an example, the oil recovery groove 1 is set so that the fine bubble warm water 12 ejected from the groove injection pipe 3 flows through the soil.

If it demonstrates concretely by the structure shown in FIG. 3, the example of the oil collection | recovery groove | channel 1 formed in the shape extended substantially in parallel with the row | line | column between the injection pipes 3 for groove | channels arranged in the row | line | column of the up-down direction of a paper surface will be shown. is there. An oil-contaminated water collecting unit 5 is formed at the center of the oil collecting groove 1, and a submersible pump 6 is provided at the bottom of the collecting unit 5 to collect the oil-contaminated water.
When the water level in the recovery unit 5 is lowered by the suction of the submersible pump 6, the oil-contaminated water in the oil recovery groove 1 naturally flows into the recovery unit 5. Further, a configuration in which the bottom of the oil recovery groove 1 is inclined toward the recovery unit 5 so that the oil-contaminated water actively flows into the recovery unit 5 can be employed.
Incidentally, the oil recovery groove 1 has a circular shape in a plan view, corresponding to the range in which the contaminated areas such as the lower oil contaminated area 45-1 and the upper oil contaminated area 45-2 as shown in FIGS. Various shapes such as a letter shape and an H shape can be adopted.

(Configuration of groove injection pipe 3)
The groove injection pipe 3 is an instrument that injects the fine bubble warm water 12 into the oil contaminated area 45 on the ground surface 48 or the water permeable layer 47, and can effectively inject the fine bubble warm water 12 into the grasped oil contaminated area 45. Number and placement are selected. In addition, it is preferable to set the temperature of the fine bubble warm water 12 in the range of 30 degreeC-40 degreeC. However, since temperature will fall if it inject | pours in soil, producing | generating hot water of high temperature exceeding 40 degreeC (for example, the range of 30 to 60 degreeC) is not excluded. However, since it becomes difficult to mix fine bubbles when the temperature becomes high, the optimum temperature setting is appropriately performed according to the situation at the site.
As shown in FIG. 4, when inserting the groove injection tube 3 into the soil, the vertical hole 8 reaching a predetermined depth is usually formed in advance, and the groove injection tube 3 is inserted into the vertical hole 8. The backflow prevention part 9 (for example, a clay part) which prevents the backflow of the injection water from the vertical hole 8 is provided in the ground surface 48.
The groove injection tube 3 is formed of an elongated bottomed tube such as a circular tube, and has a configuration in which a large number of openings 10 of various shapes such as slit openings are formed on the outer wall of the tube tip region.

  There is no need to provide anything inside the pipe, and the fine bubble hot water 12 pumped from the injection pump 19 for the groove injection pipe 3 (see also FIG. 1) is jetted from the opening 10. The length L1 of the groove injection pipe 3 configured as described above into the soil is appropriately set to a length that allows the fine bubble warm water 12 to be satisfactorily supplied to the oil-contaminated region existing at each site. Usually, the length range is set as described above. The cost of placing the groove injection tube 3 in the vertical hole 8 is very low compared to the cost of forming a conventional injection well.

(Installation of ditch pump 4)
As shown in FIG. 1, the groove water pumping pipe 4 mainly includes fine bubble warm water 12 from the groove injection pipe 3 provided corresponding to the upper oil-contaminated region 45-2 existing near the ground surface 48 of the water permeable layer 47. Is provided not only from the oil recovery groove 1 but also from the groove pumping pipe 4 for the purpose of recovery. Usually, it is often formed to the same depth in the soil as the groove injection pipe 3. Further, the planar arrangement of the groove injection pipe 3, the oil recovery groove 1, and the groove pumping pipe 4 is arranged so that the fine bubble hot water 12 injected from the groove injection pipe 3 actively flows into the oil recovery groove 1. Devise it. The groove pumping pipe 4 is provided with a pumping pump 7 for the groove pumping pipe 4.
(Fine bubble hot water injection well 14)
The fine bubble hot water injection well 14 shown in FIG. 1 is provided as necessary, and can be configured by replacing the injection water of the conventional injection well with the fine bubble hot water 12. The fine bubble hot water injection well 14 is preferably formed to a depth reaching the aquifer 42. Since it is preferable not only to collect the oil-contaminated water from the oil collecting groove 1 but also to purify the oil contained in the groundwater in the aquifer 42, usually in the purifying operation, the groove injection pipe 3 and the oil collecting are collected. Separately from the first oil floating flow path 17 in the groove 1, the second oil floating flow path 18 related to the fine bubble warm water injection well 14 reaching the aquifer 42 and the fine bubble warm water pumping well 15 reaching the aquifer 42 is also formed. Often done. Since the fine bubble warm water injection well 14 supplies at least the fine bubble warm water 12 to the water permeable layer 47, the oil peeling / floating effect of the fine bubbles 36 can be used synergistically, and the purification of the oil contaminated area 45 can be promoted. it can. The fine bubble hot water injection well 14 is provided with an injection pump 20 for the fine bubble hot water injection well 14.

(Fine bubble warm water pumping well 15)
The fine bubble warm water pumping well 15 shown in FIG.1 and FIG.2 is provided as needed, and uses the fine bubble warm water 12 compared with the pumping well 44 used for the purification process of the contaminated soil shown in FIG. The point is different. The fine bubble warm water pumping well 15 is preferably provided so as to reach at least a position reaching the aquifer 42. By pumping up the ground water or sucking up the fine bubble warm water 12 near the fine bubble warm water pumping well 15, not only the ground water but also the oil separated from the oil contaminated area 45 near the fine bubble warm water pumping well 15 is pumped up. The second oil floating flow path 18 can be formed. The fine bubble warm water pumping well 15 is provided with a pump 21 for the fine bubble warm water pumping well 15.

(Sprinkling of fine bubble warm water 12 supplied from the ground surface 48)
It is preferable that the fine bubble warm water 12 is sprinkled and supplied to the ground surface 48 from above the oil-contaminated soil. This watering is indicated by the arrow 16 in FIG. 1 and by the watering device 28 in FIG. In addition to the injection of fine bubble warm water from the groove injection pipe 3, the amount of water contained in the entire water permeable layer 47 can be improved, and the peeling / floating of oil from the soil particles can be promoted.

(Simple action explanation)
One feature of the present embodiment is that the fine bubble warm water 12 diffusing from the groove injection pipe 3 from a relatively close position to the ground surface 48 enters the upper oil-contaminated region 45-2 and detaches the oil to float. Thus, the first oil floating flow path 17 flowing into the oil recovery groove 1 is formed. This effect becomes remarkable when the slight difference bubble warm water 12 is adopted.
Further, if necessary, a fine bubble warm water injection well 14 and a fine bubble warm water pumping well 15 are provided, and a second oil floating channel 18 for pumping oil mainly flowing into the aquifer 42 from the fine bubble warm water pumping well 15. Can also be used for purification.

[Second Embodiment]
FIG. 2 is a diagram showing a configuration example for realizing the oil contamination purification method and system of the present invention. 2, the pumping path from the injection pump 19 to the groove injection pipe 3 and a part of the pumping path from the fine bubble hot water pumping well 15 to the oil separator 29 are omitted for simplicity. Yes.
2, the configuration for supplying the fine bubble warm water 12 and the configuration for recovering the oil-contaminated water from the oil recovery groove 1 and the like are described in detail compared to FIG.
1 is different from the configuration of FIG. 1 in that the fine-pump hot water pumping well 15 reaching the aquifer 42 is used instead of the groove pumping pipe 4 having a depth corresponding to the oil collecting groove 1 and the ground. The partition member 40 such as a steel sheet pile is erected from the ground so that the fine bubble warm water 12 of about 20 cm to 40 cm indicated by d in the figure is accumulated from the surface 48.
Even if the groundwater level 22 does not change so much from the height before the purification treatment before the injection of the fine bubble warm water 12, the amount of water contained in the water permeable layer 47 is increased, and the oil recovery groove 1 from the groove injection pipe 3 is increased. The first oil levitation channel 17 can be formed.
Hereinafter, each configuration of the system arranged on or near the original position will be described.

(Microbubble generator 23)
If an example is shown, it is preferable to employ | adopt the product name "GALF" of the pipeline pressurization system manufactured by IDEC Corporation of Japan as the fine bubble generator 23. With this fine bubble generating device 23, the bubble number concentration can generate about 10 times the number of fine bubbles in water compared to the pressure dissolution type fine bubble generating device which is another method of the fine bubble generating method. .

(Microbubble hot water generating means 24)
There is provided fine bubble warm water generating means 24 for setting the temperature of the injected water of the fine bubble generator 23 to warm water in the above temperature range. In the present embodiment, as shown in FIG. 2, an injection buffer tub 25 that holds the injection water is provided, a feed flow channel 26 and a return flow channel 27 that communicate the fine bubble generating device 23 and the injection buffer tub 25 are provided, By repeating the water in the injection buffer tank 25 and passing it through the fine bubble generator 23, the number of injected fine bubbles is maintained in a high range even when the temperature of the injection water is increased. That is, the fine bubble warm water generating means 24 is constituted by the fine bubble generator 23, the injection buffer tank 25, the feed flow channel 26 and the return flow channel 27.

(Water sprinkler 28 for fine bubble warm water 12)
This watering process is a process performed by the watering device 28 as necessary. It is also a preferable process to be performed in the oil contamination purification process.
The fine bubble warm water 12 in a state where the fine bubbles are contained in a predetermined range or more in the warm water is branched from the injection buffer 25 or the like and sprinkled on a predetermined region of the ground surface 48 of the oil-contaminated soil. Water spraying is performed so that the ground surface 48 is immersed in the hot water 12. By this watering treatment, the effect of floating the oil content of the oil-contaminated soil in the oil recovery groove 1 can be enhanced. In addition, it is preferable that the watering of the watering device 28 is performed while avoiding the position where the oil recovery groove 1 is located.

(Oil separator 29)
As shown in FIG. 2, an oil separation device 29 having a function of separating oil from oil-contaminated water collected from the oil collection groove 1 and the fine bubble warm water pumping well 15 is provided. The oil separator 29 is often composed of an oil separator and an oil floating separator that are not shown. The water from which the oil has been removed is used as water for generating the fine bubble warm water 12 again via the reservoir 30.
(Water injection pump)
A water injection pump 19 for the groove injection pipe 3 and the like are disposed to pump the fine bubble hot water to the groove injection pipe 3. Moreover, as shown in FIG. 1, the water injection pump 20 for the fine bubble warm water injection well 14 is also provided.
(Suction pump)
A submersible pump 6 for sucking oil-contaminated water in the oil collecting groove 1, a pumping pump 7 for the groove pumping pipe 4 shown in FIG. 1, a pumping pump 21 for the fine bubble warm water pumping well 15, and the like are provided as appropriate.

(Sensors)
As shown in FIG. 2, a temperature sensor 31 that detects the temperature of the fine bubble hot water that is press-fitted into the groove injection pipe 3, a pressure sensor 32 that detects the injection pressure of the fine bubble hot water, and the like are provided as appropriate. Although not shown, these various sensors are also provided in the fine bubble warm water injection well 14, the fine bubble warm water pumping well 15, the watering device 28, and the like.
(Microbe supply device 33)
If necessary, a device for injecting microbes for oil decomposition into the fine bubble hot water 12 to be injected is provided. As microorganisms, stimulation using microorganisms already existing in the soil and augmentation for injecting oil-degrading bacteria not in the soil are appropriately selected and employed. In addition, by inject | pouring the fine bubble warm water 12, there exists a secondary effect which can raise the activity of the microorganisms with the oil component action which already inhabits in soil. In addition, it is preferable that the sprinkler 28 also contains microorganisms from the microorganism supply device 33.

(Control device)
Although not shown in FIGS. 1 and 2, the injection process, the pumping process, the oil separation process, the fine bubble hot water generating process, and the like are managed by a predetermined processing program based on the detection information of the various sensors.
[Description of action]
Hereinafter, an example of the operation of the oil contamination purification method and system shown in FIGS. 1 and 2 will be briefly described.
(Understanding oil pollution status)
First, the range and the concentration of contamination of oil-contaminated soil are grasped in advance by a boring survey or the like, and a method of processing based on the contamination concentration is specified. Specifically, when an extremely high concentration of oil-contaminated soil is found near the ground surface by a boring survey or the like, the high-concentration contaminated soil region (hot spot) is excavated and removed before the oil purification treatment according to the present invention. It is preferable to carry out.
When the oil contamination concentration can be purified by the method of the present embodiment by a boring survey or the like, the following processing is usually performed.

(Division processing by steel sheet pile driving processing, etc.)
A partition member 40 such as a steel sheet pile is driven into the soil so as to surround the oil-contaminated region 45. Usually, the lower end of the partition member 40 is driven so as to bite into the impermeable layer 41.
The oil-contaminated area 45 isolated by the partition member 40 is blocked to some extent from the surrounding soil that is not contaminated, and the passage of groundwater with the uncontaminated soil is relatively small.

(Oil recovery groove 1 is formed and groove injection pipe 3 is inserted into the soil)
Two operations, a process of driving the groove injection pipe 3 for injecting the fine bubble warm water 12 into the upper oil-contaminated area 45-2 and an operation of forming the oil recovery groove 1 dug in a predetermined depth range from the ground surface 48, are performed. Do. As shown in FIG. 1, a groove pumping pipe 4 for collecting the fine bubble hot water 12 injected from the groove injection pipe 3 is provided as necessary. Moreover, if necessary, the fine bubble warm water injection well 14 reaching the aquifer 42 for floating the oil in the lower oil-contaminated region 45-1 near the aquifer, and the fine bubble warm water pumping up to the aquifer 42. The well 15 is installed (see FIG. 1).

(Injection of fine bubble warm water 12 and recovery of oil contaminated water)
As shown in FIGS. 1 and 2, the fine bubble warm water 12 is injected from the groove injection pipe 3 and, if necessary, water is sprayed from the sprinkler 28 to increase the amount of water contained in the water permeable layer 47. .
Preferably, in parallel with the state where the ground surface 48 is immersed in the fine bubble warm water 12, oil-contaminated water is recovered from the submersible pump 6 of the recovery unit 5 of the oil recovery groove 1 and is supplied to the oil separator 29. send. Similarly, the oil-contaminated water is pumped from the groove pumping pipe 4 or the micro-bubble hot water pumping well 15 provided as necessary, and sent to the oil separator 29. The oil separated by the oil separation device 29 is removed, and the water from which the oil has been separated is sent to the injection buffer tank 25 through the water storage tank 30, converted into the fine bubble warm water 12, and again from the groove injection pipe 3 to the soil. Injected into.

  If it is this structure, it can implement simply by digging the groove | channel of predetermined depth in the ground surface 48. FIG. Moreover, the injected fine bubble warm water 12 can form the first oil levitation flow path 17 in which the oil in the oil-contaminated region 45 is separated by the fine bubbles 36 and floats or flows into the oil recovery groove 1. Therefore, high purification can be performed in a short period of time at low cost.

FIGS. 5A and 5B schematically show the peeling effect of the soil particles 34 and the oil 35 by the fine bubble warm water 12.
As shown in FIG. 5 (a), even if the oil 35 is firmly bound to the soil particles 34 in the soil, the fine bubbles 36 permeate from the surface of the contaminated oil, including the effect of dissolving the hot water. ), The oil 35 is separated and separated from the soil particles 34, and the oil 35 is more likely to float due to the fine bubbles 36 adhering to the periphery thereof. In particular, in the lower oil-contaminated region 45-1 having a high water content formed between the groove injection pipe 3 and the oil recovery groove 1, the first oil levitation flow path 17 through which the hot water 12 to be injected repeatedly flows. The effect will be greater than expected. In the drawings of the present patent application, the fine bubbles are very small and are not visible in size, but are schematically shown as visible bubbles.

  In addition, when the microorganism supply apparatus 33 shown in FIG. 2 is used to supply microorganisms to the microbubble hot water 12 to be injected, the microorganisms are high enough not to die, for example, considering the degree of cooling by the soil after the injection. If the temperature is set, the soil temperature and the microorganism concentration can be set so that the microorganisms actively decompose oil in the soil. In general, most of the microorganisms that decompose oil are aerobic bacteria, and the microbubbles warm water 12 is injected so as to satisfy the growth conditions of the oil-decomposing bacteria as long as there is oil by including the microbubbles 36 in the warm water. Thereafter, as long as there is oil in the soil, the microorganisms grow and decompose the oil for purification, so that it can be promoted in a short period of time and at a low cost.

[Example]
In order to verify the effect of the present invention, the present inventor struck a steel sheet pile around the site of a 200 m ² site of a gas station not exposed to rainwater to make it almost isolated from the outside groundwater. Further, as the fine bubble hot water injection means 3, for a groove having a length L1 of 2500 mm to 3000 mm, provided with a large number of slit openings 10 having an interval of 2 mm and a slit width of 1 mm on the outer peripheral surface of a bottomed vinyl chloride tube having a diameter of 50 mm. The injection tube 3 was adopted.
And the said vinyl chloride pipe | tube was driven by the space | interval of about 600 mm-1000 mm so that it might become effective arrangement | positioning to the oil-contaminated area previously discovered by the boring investigation.
Further, the oil collecting groove 1 is formed at a position above the oil-contaminated region and in a shape that can effectively collect oil-contaminated water corresponding to the arrangement of the groove injection pipes 3. In addition, a plurality of grooved water pumping pipes 4 were installed so as to provide an effective arrangement with respect to the oil-contaminated area.

And the collection | recovery part 5 which is the deepest location of the oil collection groove | channel 1 was installed in several places, and the submersible pump 6 which sucks up oil-contaminated water was installed in the bottom face of those collection | recovery parts 5.
In the above configuration, it was possible to purify to below the allowable oil contamination concentration determined by the country in about 10 days from the injection start date of the fine bubble warm water.

In the present embodiment, the ground surface is not immersed in the fine bubble warm water by the watering device, and the fine bubble warm water injection well reaching the aquifer and the fine bubble warm water pumping well reaching the aquifer are not provided. Thus, the above-described purification effect in a short period can be obtained only by combining the oil recovery groove, the groove injection pipe, and the groove pumping pipe. This example demonstrates that the purification period and purification cost can be significantly reduced by the method and system of the present invention compared to the conventional method.
In addition, if necessary, a water sprinkling device for supplying fine bubble warm water to the ground surface is provided, and a floating flow of oil-contaminated water by the fine bubble warm water injection well or the fine bubble warm water pumping well reaching the aquifer (the second oil described above) The combined use of the floating flow path) can significantly reduce the purification period and purification treatment cost not only for the upper oil-contaminated area, but also for the lower oil-contaminated area and groundwater contamination spreading in the permeable layer and aquifer. found.

The present invention can be variously modified within the scope of the present invention other than the above embodiment.
(1) The method and principle for generating the fine bubble warm water are not particularly limited. The method and system according to the present invention can be similarly applied to the fine bubble warm water generated by a method other than the fine bubble generation device according to the above-described pipeline pressurization method.
Further, in the present invention, as a method for generating the fine bubble warm water, warm water is prepared in advance and the fine bubble generating device includes the fine bubbles in the warm water, and other methods include water containing the fine bubbles. Both methods of forming warm water after forming can be employed.

(2) In the method and system of the present invention, even if a relatively high-concentration oil-contaminated region is near the ground surface, oil recovery can be achieved by providing a high-density groove injection pipe and a groove pumping pipe as necessary. A large amount of oil can float in the groove. Therefore, even high-concentration oil-contaminated soil, which conventionally had to be washed by excavation, could be treated in situ (several weeks to several months) by the method and system of the present invention. There is actually an oil pollution purification site.

DESCRIPTION OF SYMBOLS 1 ... Oil recovery groove | channel 3 ... Fine bubble warm water injection | pouring means (The injection pipe | tube 3 for grooves is shown as an example)
6 ... Submersible pump 10 ... Opening 12 ... Fine bubble warm water 14 ... Fine bubble warm water injection well 15 ... Fine bubble warm water pumping well 19 ... Injection pump (for groove injection pipe)
DESCRIPTION OF SYMBOLS 23 ... Fine bubble generator 24 ... Fine bubble warm water production | generation means 25 ... Injection buffer tank 26 ... Feed flow path 27 ... Return flow path 28 ... Sprinkling device 29 ... Oil separator 33 ... Microorganism supply apparatus 36 ... Fine bubble 39 ... Branch Pipe 42 ... Aquifer 47 ... Water permeable layer 48 ... Ground surface L1 ... Length in the longitudinal direction of soil in the groove injection pipe

Claims (13)

An oil recovery groove forming step of forming an oil recovery groove (1) on the ground surface (48) of the oil-contaminated soil area, wherein the oil-contaminated soil is purified in situ,
A step of injecting hot water containing fine bubbles (36) into the oil-contaminated soil to increase the amount of water contained in the oil-contaminated region;
Oil separation in which oil-contaminated water is made to flow into the oil recovery groove (1) by the fine bubble warm water (12) from the oil-contaminated soil with increased water content, and then separated from the oil-contaminated water that has flowed in. And a method for purifying oil-contaminated soil. The method for purifying oil-contaminated soil according to claim 1, wherein the lower limit of the gas-containing concentration of the fine bubbles is set to about 160% of the limit dissolution concentration. In the purification method of the oil-contaminated soil according to any one of claims 1 to 2, when generating the fine bubble warm water (12), a fine line generator (23) of a pipe pressurization method is used. A method for purifying oil-contaminated soil, which is used and achieves the concentration of the gas by repeatedly passing water through the microbubble generator (23) of the above method a plurality of times. In the purification method of the oil-contaminated soil according to claim 3, naturally by the action of pressurizing water by repeatedly passing water through the microbubble generating device (23) of the pipeline pressurization method a predetermined number of times. A method for purifying oil-contaminated soil as warm water. In the purification method of the oil-contaminated soil according to any one of claims 1 to 4, when the fine bubble warm water (12) is injected into the oil-contaminated soil in the fine bubble warm water injection step, As the groove injection pipe (3), a plurality of openings (10) having a width of 2 mm to 5 mm for ejecting injection water is formed on the outer peripheral surface thereof, and a pipe having a bottom portion is used and inserted into the oil-contaminated soil The longitudinal length (L1) of the groove injection pipe (3) is 3 m to 5 m, and the transverse diameter of the groove injection pipe (3) is 1 inch to 3 inches. Purification method for oil-contaminated soil. The method of purifying oil-contaminated soil according to any one of claims 2 to 4, wherein the fine bubble warm water sprinkling waters the fine bubble warm water (12) from the ground surface (48) of the oil contaminated soil. A method for purifying oil-contaminated soil, comprising a step. In the purification method of the oil-contaminated soil according to any one of claims 1 to 6, in addition to the above-described configuration, a fine water that reaches at least the aquifer (42) and injects the fine bubble warm water (12). A bubble hot water injection well (14) and a fine bubble warm water pumping well (15) that reaches at least the aquifer (42) and pumps up oil-contaminated water are separately provided. A method for purifying oil-contaminated soil, wherein the fine bubble warm water (12) is injected into the region of (47) and the contaminated water containing oil separated from the soil by the fine bubble warm water pumping well (15) is pumped. It is a system that provides the following components for purifying oil-contaminated soil in situ,
(A) an oil recovery groove (1) provided on the ground surface (48) of the oil-contaminated soil area;
(B) a fine bubble generator (23) for generating fine bubbles in water;
(C) a fine bubble warm water generating means (24) for warming the water containing the fine bubbles before being injected into at least the oil-contaminated soil;
(D) Fine bubble warm water injection means (3) for injecting the fine bubble warm water (12) generated by the fine bubble warm water generation means (24) into the oil-contaminated soil;
(E) a pump (19) for applying pressure to the fine bubble warm water (12) from the fine bubble warm water injection means (3) and sending it out;
(F) a pump (6) for taking out the oil-contaminated water flowing into the oil recovery groove (1) together with water from the oil recovery groove (1);
(G) an oil separator (29) for separating oil from the oil-contaminated water that has flowed into the oil recovery groove (1) together with water;
A system for purifying oil-contaminated soil, comprising at least The system for purifying oil-contaminated soil according to claim 8, wherein the fine bubble warm water injection means (3) is formed with a plurality of openings (10) having a width of 2 mm to 5 mm for injecting injected water to the outer peripheral surface thereof. And a groove injection pipe (3) having a bottom, and the length (L1) in the longitudinal direction of the groove injection pipe (3) inserted into the oil-contaminated soil is 3 m to 5 m, and the groove The oil-contaminated soil purification system has a transverse diameter of 1 to 3 inches. The oil-contaminated soil purification system according to any one of claims 8 to 9, wherein the fine bubble generating device (23) is a device that generates fine bubbles by a line pressurization method, and the fine bubbles are generated. The bubble hot water generating means (24) repeats a plurality of times between the injection buffer bottle (25) containing the fine bubble hot water (12), the fine bubble generator (23) and the injection buffer bottle (25). An oil-contaminated soil purification system provided with a feed channel (26) and a return channel (27) so that it can circulate. The oil-contaminated soil purification system according to any one of claims 8 to 10, wherein the fine bubble warm water (12) produced by the fine bubble warm water production means (24) is used as the ground surface (48). Purification system for oil-contaminated soil with a watering device (28) for watering from The oil-contaminated soil purification system according to any one of claims 8 to 11, wherein the fine bubble warm water (12) from one fine bubble warm water generating means (24) is used as a plurality of fine bubble warm water. A system for purifying oil-contaminated soil having a branched pipe (39) for feeding to the injection means (3). The oil-contaminated soil purification system according to any one of claims 8 to 12, wherein the microbubbles warm water (12) generated by the microbubbles hot water generating means (24) decomposes or separates oil. A system for purifying oil-contaminated soil, which has a microorganism supply device (33) for adding water.

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