JP2006000702A - Method and system for treating contaminated soil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a system for treating contaminated soil by which contaminated soil can be treated inexpensively in a short period of time and contaminants remaining in contaminated soil can effectively be decomposed continuously even after treated. <P>SOLUTION: This method for treating contaminated soil comprises: a step 110 of mixing a nutrient for activating a microbe having oil content decomposing ability in contaminant-containing contaminated soil; a step 120 of mixing an improving material containing unslaked lime or a lime-based chemical in the contaminated soil where the nutrient is mixed at the step 110; and a step 130 of burying the soil treated by mixing the nutrient and the improving material respectively at the steps 110, 120 in the dug contaminated soil. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a contaminated soil treatment method and a contaminated soil treatment system for purifying contaminated soil containing contaminants such as oils.

  As an example of a method for treating contaminated soil contaminated with oils and other contaminants, first, high temperature calcined quicklime powder is mixed with the contaminated soil, and after the reaction of quicklime is completed, a nutrient that activates microorganisms in the soil (Microbial nutrients) are sprayed and mixed to promote the volatilization of pollutants by hydration heat generated by the reaction between quicklime and soil moisture, and then the method of further decomposing and removing pollutants by microorganisms. Yes (see, for example, Patent Document 1).

JP-A-5-228499

  Here, the soil particles constituting the soil are different in particle size, and when viewed microscopically, fine particles having a small particle size are often aggregated to form a aggregate structure. In contaminated soil, contaminants may penetrate into the soil particles of the aggregate structure, and in order to decompose without leaving any contaminants, there must be some microorganisms in the soil particles of the aggregate structure. I must. However, microorganisms in the soil have poor ability to move and generally cannot move unless water is used as a medium. Therefore, in order for microorganisms to move inside the soil particles having a aggregate structure, water needs to penetrate into the soil particles.

  However, in the said prior art, quick lime is mixed with contaminated soil at the first process. Therefore, when water penetrates into the soil particles having the aggregate structure, the pH of the water rises through the lime layer attached to the surface of the soil particles, and the high pH water enters the soil particles. Moreover, since water in which nutrients are dissolved must be allowed to permeate into the soil particles in order to permeate the nutrients into the soil particles, high pH water is allowed to enter the soil particles when mixing the nutrients. . As a result, not only microorganisms that originally lived in the soil particles of aggregated structure, but also microorganisms that infiltrated into the soil particles along with the permeated water were exposed to high pH water, and in extreme cases, the microorganisms were killed. May cause the pollutant to not be sufficiently decomposed.

  The present invention has been made on the basis of the above-mentioned matters, and its purpose is that it can be constructed at low cost in a short period of time, and the contaminants remaining in the soil can be decomposed continuously and effectively even after construction. The object is to provide a contaminated soil treatment method and a contaminated soil treatment system.

  In order to achieve the above object, the first invention comprises a step of mixing a nutrient that activates microorganisms having oil-degrading ability into contaminated soil containing a pollutant, and quicklime or lime or the contaminated soil mixed with the nutrient And a step of mixing an improving material containing a lime-based drug.

  According to a second aspect of the invention, there is provided a step of mixing a microbial material containing a microorganism carrier carrying a microorganism having a surface soil or oil content resolution into a contaminated soil containing a pollutant, and a quick lime or lime-based material in the contaminated soil mixed with the microbial material. And a step of mixing an improving material containing a drug.

  3rd invention mixes the nutrient which activates the microorganisms which have oil content resolution to the contaminated soil containing a pollutant, and the microorganisms containing the microorganism carrier which carry | supported the topsoil or the microorganisms which have oil content resolution to the said contaminated soil The step of mixing the materials is performed in any order or at the same time, and then the step of mixing the improving material containing quicklime or lime-based chemicals into the contaminated soil mixed with the nutrient and the microbial material is performed.

  According to a fourth invention, in any one of the first to third inventions, the improving material is a granular state having a particle size larger than that of a single particle, or a particle aggregate formed by aggregation of single particles. It is characterized by mixing in a state.

  5th invention is the improvement which mixes the nutrient which activates the microorganisms which have an oil content resolution into the contaminated soil containing a pollutant, and quicklime or a lime type chemical | medical agent in the contaminated soil mixed with the said nutrient And a mixing means for mixing the materials.

  According to a sixth aspect of the present invention, there is provided a mixing means for mixing a microbial material containing a microbial carrier carrying microorganisms having a surface soil or oil content resolution into a contaminated soil containing a pollutant, and quick lime or lime system in the contaminated soil mixed with the microbial material. And a mixing means for mixing the improving material containing the drug.

  The seventh invention is a mixing means for mixing a nutrient agent for activating microorganisms having oil-decomposability in contaminated soil containing a pollutant, and a microbial material including a topsoil or a microorganism carrier carrying microorganisms having oil-decomposability, and Mixing means for mixing quick lime or an improving material containing a lime-based chemical into the contaminated soil mixed with the nutrient and the microbial material is provided.

  According to the present invention, it is possible to increase the number of microorganisms surviving in the soil even after the improvement material is mixed by simply mixing the nutrient and the microbial material with the contaminated soil before mixing the improvement material. . Therefore, construction can be performed at a low cost in a short construction period, and contaminants remaining in the soil can be decomposed continuously and effectively even after construction.

  Hereinafter, embodiments of the contaminated soil treatment method and the contaminated soil treatment system of the present invention will be described with reference to the drawings.

First, the background of the contaminated soil treatment method of the present invention will be described.
Conventionally, when a lime-based chemical is mixed with contaminated soil in order to promote volatilization of oil pollutants, the soil temperature temporarily becomes high (for example, 80 to 100 ° C.) and the pH also increases, which is severe for microorganisms. Since it became a habitat, the microorganisms were killed, and it was generally recognized that after the construction, the continuous degradation of pollutants by microorganisms cannot be expected.

On the other hand, the inventors of the present application conducted the following test in order to confirm the above general theory.
First, a sample of contaminated soil containing oil pollutants mixed with a required amount of quicklime or lime-based chemicals (hereinafter simply referred to as an improved material) is left indoors and regularly The content of pollutants was measured.
As a result of the measurement, the pollutant content of the sample, which was about 4000 mg / kg before mixing the improving material, is reduced to about 1500 mg / kg due to the promotion of volatilization by heat generation immediately after mixing the improving material. It was found that after a month, it gradually decreased to 400 mg / kg, after 3 months, 300 mg / kg, after 6 months, 250 mg / kg.

Next, it was confirmed how the content of pollutants in the soil was changed in the actual site where the improved soil was mixed and treated in the past.
An investigation was conducted at the site where 10 months had passed since construction, and it was confirmed that the contaminant content, which was about 1500-3500 mg / kg before construction, has dropped to about 100-200 mg / kg. .

Based on this result, for further investigation, we analyzed the change over time in the number of cells living in the soil at other sites where similar construction was carried out.
As a result, the number of cells per 1 g of dry soil was 1.0 × 10 ^{11 to} 6.0 × 10 ¹¹ cells / g before construction, but was actually 1.0 × 10 ^{10 to} 1.5 × immediately after construction. As many as 10 ¹¹ cells / g of microorganisms were active, and when 1 month passed, they showed a tendency to grow to 1.0 × 10 ^{10 to} 3.0 × 10 ¹¹ cells / g.

The inventors of the present application assumed the support of the above phenomenon as follows.
(1) Effect of heat of hydration reaction on microorganisms As is well known, when quicklime or lime chemicals are mixed with soil, heat of hydration reaction occurs due to the reaction between water and lime. This works effectively to promote the volatilization of pollutants consisting of oils. In general, this increase in temperature has been considered to be a cause of killing microorganisms, but even if the temperature environment suitable for microorganisms is exceeded, damage to microorganisms due to high temperature environments is generally considered to be temporary. Less than you are. This is presumed from the fact that many microorganisms were alive in the soil immediately after the construction.

(2) About high pH environment in soil (i) Since rainwater and groundwater do not pass through most areas in the soil, the pH is increased only by a part of the entire soil due to the improving material.

  That is, as shown in FIG. 1, a “water supply” is generally formed in the soil. Water (rainwater, groundwater, etc.) that permeates into the soil due to rainfall, etc., is likely to flow into the water supply A, and does not penetrate all over the soil, but normally passes through the water supply A preferentially. is there.

  Therefore, as shown in FIG. 2, although water (high pH water) in contact with the improved material mixed in the soil flows along the tap water A, the pH of the soil in most other regions almost increases. do not do. Therefore, most of the microorganisms that inhabit the soil continue their activities without being exposed to the high pH environment.

  (Ii) The microscopic increase in the pH after mixing with the improving material is limited only to the vicinity of the particles of the improving material. Even if the apparent pH increases as a whole, the actual increase in the soil The increase in pH is local.

In general, soil is composed of individual soil particles having a wide particle size range. However, as shown in FIG. 3, generally, fine particles C having a small particle size are aggregated to form soil particles D having a aggregate structure. Yes.
When the fine particle-like improvement material close to a state in which single particles are independent from each other is mixed with the soil containing the soil particles D having such aggregate structure, the improvement material is applied to the surface layer (surface) of the soil particles D. The particles are coated and adhered. If there is rain or the like in such a state, there is a possibility that the improved material adhering to the surface layer of the soil particles D and water may come into contact with each other. However, the water hardly penetrates into the soil particles D, and the water becomes high pH water. Only the surface layer portion of the soil particles D is actually exposed to a high pH environment as shown in FIG. Therefore, most of the soil particles D do not have a high pH environment up to the inside.

  Moreover, when mixing the improvement material of the granular state whose particle size is larger than a single particle instead of the fine grained powder (particulate) as described above, as shown in FIG. The granular improvement material E is not distributed evenly in the soil, but is usually dispersed and distributed locally. In this case, when there is rain or the like and the improved material E comes into contact with water, the high pH water may diffuse around the improved material E. As a result, exposure to high pH water is limited only to the vicinity of the granular improvement material E, and microorganisms exposed to the high pH environment also lived in the vicinity of the improvement material E. Limited.

  Here, lime is generally mined as limestone, and when this is pulverized and fired at a high temperature, decarburization occurs and quick lime is generated. Quicklime is crushed as necessary, classified and adjusted in particle size, and shipped as a product. In general, lime having a particle size of 0 to 2 mm, 2 to 5 mm, 0 to 5 mm, 5 to 15 mm, 5 to 25 mm, 25 to 30 mm, and 5 to 30 mm is distributed. In the present invention, the aforementioned powdery (particulate) improving material refers to an improving material having a particle size of about 0 to 2 mm or a particle size close thereto, and the granular improving material is about 2 to 5 mm in particle size or An improvement material with a particle size close to this.

  In addition, it is also conceivable that the improving material is mixed in a state of a particle aggregate formed by aggregation of single particles (for example, particles having a particle size of about 0 to 2 mm or close to this). In this case as well as the granular improvement material, it is locally dispersed in the soil, and since the surface area of the improvement material is larger than that of the granular improvement material, the reaction rate with water, that is, the heat generation rate is increased. The advantage is that it is faster.

  As described in (i) and (ii) above, even if an improved material is mixed with the soil, most of the microorganisms that live in the soil are not actually exposed to the high pH environment and are active without any special damage. The present inventors have inferred that this can be continued.

  However, after mixing the improving material into the contaminated soil, in order to activate the microorganisms that live in the soil and continuously degrade the pollutant after construction, There is concern.

FIG. 6 is a model diagram of the soil particles D having a aggregate structure after mixing the particulate improvement material with the contaminated soil.
As described above, the soil particles D constituting the soil have different particle sizes, and the individual soil particles D often have a aggregate structure by agglomerating fine particles having a small particle size. FIG. 6 illustrates a state where the particulate improvement material F is attached to the surface layer of each soil particle D having a aggregate structure.

  When giving a nutrient that activates the microorganisms G that live inside the soil particles D in such a state, in order to permeate the nutrients into the soil particles D, water in which the nutrients are dissolved as shown in FIG. Must penetrate into the soil particles D. In this case, when passing through the lime layer on the surface of the soil particles D having the aggregate structure, the pH of the water containing nutrients rises, and the high pH water enters the soil particles D. As a result, not only the microorganisms G that originally lived inside the soil particles D of aggregated structure, but also the microorganisms G that infiltrate the soil particles D due to the permeated water are exposed to high pH water. In some cases, microorganisms may die and the pollutants cannot be sufficiently decomposed.

  Therefore, in the present embodiment, the contaminated soil containing oil pollutants is purified by the following method.

FIG. 8 is a flowchart showing the procedure of an embodiment of the contaminated soil treatment method of the present invention.
As shown in FIG. 8, in the contaminated soil treatment method of the present embodiment, the step 110 of mixing a nutrient that activates microorganisms having oil-degrading ability into the contaminated soil containing the contaminant, The step 120 of mixing the improved soil containing quicklime or lime-based chemicals into the mixed contaminated soil and the step 130 of backfilling the treated soil generated by mixing the nutrient and the improver into the contaminated soil are performed. .

  Further, in step 120, preferably, an improved material in a granular state having a particle size larger than that of a single particle or in a state of a particle aggregate formed by agglomeration of single fine particles is mixed with the contaminated soil.

  As described above, in the present embodiment, by mixing the nutrients in the contaminated soil before mixing the improving material, the nutrient particles are preliminarily contained in the soil particles of the aggregate structure so that the inside of the soil particles Activates the microorganisms. Then, by mixing the improving material into the contaminated soil mixed with the nutrient, the volatilization of the pollutant is promoted by the heat of hydration reaction, and the content of the pollutant in the soil is greatly reduced.

  At this time, in the present embodiment, the nutrient is infiltrated into the soil particles before the improving material adheres around the soil particles having the aggregate structure. There is no infiltration of pH water. In other words, there is a low risk of killing microorganisms that are alive inside the soil particles even after the improvement material is mixed, such as when adding nutrients after mixing the improvement material, so that more microorganisms can survive in the soil. These microorganisms can be activated.

  Therefore, at the time of construction, the content of contaminants can be greatly reduced by the heat of hydration reaction, and the contaminants remaining by the microorganisms actively utilized even after the construction can be decomposed and removed continuously and efficiently. As described above, in the present embodiment, it is possible to improve the decomposition efficiency of the pollutants after the construction by actively utilizing the microorganisms as described above and allowing as many microorganisms as possible to survive in the soil. Certainty is also improved. In addition, the construction itself is simply a matter of mixing the nutrients and then backfilling with the improved material, and can be carried out in a short construction period and at a low cost.

  As described above, according to the present embodiment, construction can be completed in a short construction period at a low cost, and the contaminants remaining in the soil can be continuously removed after construction without impeding the activity of microorganisms in the soil as much as possible. And can be effectively decomposed.

  In addition, as described with reference to FIG. 5, the granular improvement material is usually present locally in the soil even if mixed. From this, in this embodiment, if the granular improvement material is mixed with the contaminated soil, the region exposed to the high pH water is limited to a local region even when there is rainfall or the like after the construction, for example. The area where the microbial habitat deteriorates can be minimized. Therefore, it is possible to further restrict the factors that inhibit the activation of microorganisms and to further improve the effect of decomposing pollutants after construction. Furthermore, as described above, when the improving material in the state of the particle aggregate is used, in addition to the effect when the granular improving material is used, there is an advantage that the heat generation rate becomes faster.

FIG. 9 is a side view showing the entire structure of an embodiment of the contaminated soil treatment system of the present invention for carrying out the contaminated soil treatment method of the present embodiment.
As shown in FIG. 9, the contaminated soil treatment system of the present embodiment has a hydraulic excavator 200 that excavates and introduces contaminated soil containing pollutants, and has an oil content resolution in the contaminated soil input by the hydraulic excavator 200. Self-propelled mixing machine 100 that mixes nutrients that activate microorganisms, and self-propelled type that mixes quick lime or lime-based chemicals with improved materials in contaminated soil mixed with nutrients in self-propelled mixing machine 100 A mixing machine 500.

  First, the configuration of the hydraulic excavator 200 will be described. 201 is a traveling body, 202 is a revolving body provided on the traveling body 201 so as to be turnable, 203 is a prime mover provided on the rear side of the revolving body 202, and 204 is a rear portion of the revolving body 202. , A counter seat provided at the front of the swing body 202, a boom provided at the center of the front of the swing body 202 so as to be able to be lifted and lowered, and 207 provided at the tip of the boom 206 so as to be rotatable. Reference numeral 208 denotes an excavation bucket that is rotatably provided at the tip of the arm 207.

  Reference numeral 209 denotes a hydraulic cylinder for driving the boom. The base end of the hydraulic cylinder 209 is connected to the swing body 202, and the tip of the piston rod 210 is connected to the middle portion of the side surface of the boom 206. 211 is a hydraulic cylinder for driving the arm, and its base end is connected to the middle portion of the upper surface of the boom 206, and the tip of the piston rod 212 is connected to the base of the arm 207. Reference numeral 213 denotes a bucket drive hydraulic cylinder, the base end of which is connected to the upper surface base side of the arm 207, and the tip of the piston rod 214 is connected to one of the links 215 and 216. The other side of the link 215 is connected to the distal end side of the arm 207, and the other side of the link 216 is connected to the back portion of the bucket 208 by a pin 217. The boom 206, the arm 207, and the drive hydraulic cylinders 210 and 211 constitute an articulated work arm.

  The configuration of the self-propelled mixing machine 100 will be described. The traveling body 101 is a traveling body. The traveling body 101 includes a traveling body frame 102, a track frame 103 provided on each side of the traveling body frame 102, and the track frame. 103, a driven wheel 104 provided on one side (left side in FIG. 9) of 103, a driving wheel 105 provided on the other side (right side in FIG. 9) of the track frame 103, and the driven wheel 104 and driving wheel 105. It consists of a crawler belt 106 that has been turned.

  107 is a main body frame provided on the traveling body frame 102, 108 is a power unit provided on the other side (right side in FIG. 9) of the main body frame 107 via a support member 109. The power unit 108 includes an engine, A pump driven by the engine, and a valve for switching and supplying the pressure oil from the pump to the traveling body and a device to be described later are provided.

  Reference numeral 110 denotes a mixing device serving as a nutrient mixing means provided substantially at the center of the main body frame 107. Inside the mixing device 110, at least one paddle mixer is provided as a stirring transfer means. Although not particularly illustrated, the mixing device 110 includes an inlet at an upper portion on one side (left side in FIG. 9) and an outlet at a lower portion on the other side (right side in FIG. 9). Reference numeral 111 denotes a driving device for the mixing device 110.

  112 is a support frame provided on one side of the main body frame 7 (left side in FIG. 9), 113 is a sieve device provided on the support frame 112 via a spring 114, and 115 is an eccentric body drive provided on the sieve device 113. The shaft 116 is a vibration hydraulic motor, and 117 is a belt that connects the vibration hydraulic motor 116 and the eccentric drive shaft 115.

  A transport conveyor 118 is provided on the support frame 112 so as to be positioned below the sieving device 113, and a discharge side (right side in FIG. 9) of the transport conveyor 118 faces an inlet of the mixing device 110. Reference numeral 119 denotes a hopper that receives the earth and sand that has passed through the sieving device 113, and this hopper 119 is a hopper provided on the support base 112 so as to be positioned between the sieving device 113 and the transport conveyor 118.

  Reference numeral 120 denotes a storage tank supported by a column 121. The upper portion of the storage tank 120 is formed in a bellows shape in order to adjust its height. 122 is a supply port provided in the lower part of the storage tank 120, and this supply port 122 is located above the other side (right side in FIG. 9) of the conveyor 118.

  In addition, in this self-propelled mixing machine 100, when mixing a nutrient with earth and sand (contaminated soil) in the state of a solution, the storage tank 120 and its supply port 122 may not be used. Although not particularly illustrated, a pipe for spraying a nutrient solution in a solution state is installed at the inlet of the mixing device 110, and the nutrient solution stored in a tank (not shown) is appropriately discharged by a pump or the like. The mixing device 110 is supplied to the mixing device 110 through the pipe provided near the inlet of the mixing device 110.

  123 is a discharge conveyor that conveys and discharges the mixed soil of nutrient solution and contaminated soil discharged from the outlet of the mixing device 110, and one side (left side in FIG. 9) of the discharge conveyor 123 is an outlet of the mixing device 110. The other side (the right side in FIG. 9) is supported by the main body frame 107 and the like so as to have an upward slope from the lower side of the power unit 108.

  The configuration of the self-propelled mixing machine 500 is substantially the same as that of the self-propelled mixing machine 100. That is, reference numeral 501 denotes a traveling body, and the traveling body 501 is provided on the traveling body frame 502, the track frame 503 provided on each side of the traveling body frame 502, and one side of the track frame 503 (the left side in FIG. 9). A driven wheel 504, a drive wheel 505 provided on the other side (right side in FIG. 9) of the track frame 503, and a crawler belt 506 wound around the driven wheel 504 and the drive wheel 505.

  Reference numeral 507 denotes a main body frame provided on the traveling body frame 502, and reference numeral 508 denotes a power unit provided on the other side (right side in FIG. 9) of the main body frame 507 via a support member 509. Reference numeral 510 denotes a mixing device as an improving material mixing means provided in the approximate center of the main body frame 507. The mixing device 510 is provided with a paddle mixer. Reference numeral 511 denotes a driving device for the mixing device 510.

  512 is a support frame provided on one side of the main body frame 7 (left side in FIG. 9), 513 is a sieve device provided on the support frame 512 via a spring 514, and 515 is an eccentric drive shaft provided on the sieve device 513. Reference numeral 516 denotes a vibration hydraulic motor, and 517 denotes a belt that connects the vibration hydraulic motor 516 and the eccentric drive shaft 515.

  Reference numeral 518 denotes a conveyer provided on the support frame 512 so as to be positioned below the sieving device 513, and the discharge side (right side in FIG. 9) of the conveyer 518 faces the inlet of the mixing device 510. Reference numeral 519 denotes a hopper provided on the support frame 512 so as to be positioned between the sieving device 513 and the conveyor 518.

  Reference numeral 520 denotes an improvement material storage tank supported by a column 521, and the upper portion of the improvement material storage tank 520 is formed in a bellows shape in order to adjust the height thereof. Reference numeral 522 denotes a supply port provided in the lower part of the improvement material storage tank 520. This supply port 522 is located above the other side (right side in FIG. 9) of the transport conveyor 518, and is mixed by the transport conveyor 518. Supply improvement materials on the ground.

  Reference numeral 523 denotes a discharge conveyor that conveys and discharges the treated soil discharged from the outlet of the mixing device 510. One side (left side in FIG. 9) of the discharge conveyor 523 is located below the outlet of the mixing device 510, and the other side. (Right side in FIG. 9) is supported by the main body frame 507 so as to have an upward inclination from below the power unit 508.

Next, the operation of the contaminated soil treatment system of the present embodiment having the above configuration will be described.
The process of step 110 in FIG. 8 will be described. First, the articulated work arm of the excavator 200 is operated to excavate the contaminated soil a to be treated by the bucket 208 and supply it to the self-propelled mixing machine 100.

  In this way, the contaminated soil introduced into the sieving device 113 of the self-propelled mixing machine 100 is removed by foreign matter such as large stones by the sieving device 113 and introduced into the lower hopper 119. The contaminated soil received by the hopper 119 is further placed on the transport belt of the lower transport conveyor 118, transported toward the mixing device 110, and introduced into the mixing device 110 together with nutrients supplied from a tank (not shown). The The contaminated soil and nutrients introduced into the mixing device 110 are uniformly stirred and mixed by the paddle mixer and discharged onto the discharge conveyor 123. Then, the contaminated soil and the mixed soil of nutrients are conveyed by the discharge conveyor 123 and discharged outside the machine.

  The step 120 will be described. The mixed soil discharged from the self-propelled mixing machine 100 may be temporarily placed in a predetermined place, but in this example, the sieve device 513 of the self-propelled mixing machine 500 is directly used. To be supplied. The mixed soil received by the hopper 519 via the sieving device 513 is placed on the transport belt of the transport conveyor 518 and is transported toward the mixing device 510. Then, the improving material in the improving material storage tank 520 is supplied through the supply port 522 during the conveyance, and the mixed soil is introduced into the mixing device 510 together with the improving material. The mixed soil and the improved material introduced into the mixing device 510 are uniformly agitated and mixed by the paddle mixer and discharged onto the discharge conveyor 523. Then, the treated soil generated by mixing the mixed soil and the improving material is further conveyed by the discharge conveyor 523 and discharged outside the machine.

  In step 130, for example, the processing soil b discharged from the self-propelled mixing machine 500 is backfilled to a target backfilling site d (for example, a drilling site) at the excavation site using a hydraulic excavator 200 or the like.

  After completing the above steps, there is no special construction after that. For example, when using land as a construction site, a facility e is constructed immediately after processing in the backfilling place d where the treated soil b is backfilled. Is possible. Of course, the land is not limited to the construction site. For example, even when the land is used for a parking lot or a ground, the land can be reused immediately after the construction according to the purpose.

  In the contaminated soil treatment method of the present embodiment, the contaminated soil treatment system can be simply configured as described above, because the improving material is simply mixed and backfilled after the nutrient agent is mixed into the contaminated soil. Further, since both the hydraulic excavator 200 and the self-propelled mixing machines 100 and 500 have a self-propelled function, the degree of freedom of layout is large at the contaminated site, and the movement within the contaminated site is easy. In addition, because it can be lifted and lowered by itself on a carrier such as a trailer, it is excellent in transportability between sites.

FIG. 10 is a flowchart showing the procedure of another embodiment of the contaminated soil treatment method of the present invention.
As shown in FIG. 10, the contaminated soil treatment method of the present embodiment includes a step 210 of mixing a microbial material containing a microbial carrier carrying microorganisms having a topsoil or oil resolution in contaminated soil containing a contaminant. A step 220 of mixing the improved soil containing quicklime or lime-based chemicals into the contaminated soil mixed with the microbial material, and a step 230 of backfilling the treated soil generated by mixing the microbial material and the improved material into the contaminated soil. Process.

  The steps 220 and 230 are the same as the steps 120 and 130 in FIG. 8, and in this example as well, the step 220 is preferably a granular state having a particle size larger than a single particle, or a single particle. An improved material in a state of a particle aggregate formed by agglomeration of a single fine particle is mixed with contaminated soil.

  One embodiment of the contaminated soil treatment method of the present invention described above is an example in which a nutrient is mixed into the contaminated soil before the improved soil is mixed in order to activate microorganisms in the soil. This embodiment is an example of increasing the number of microorganisms themselves that inhabit the soil.

  In general, the distribution of the number of microorganisms changes in the depth direction of the soil, and the number of microorganisms decreases as the surface soil becomes deeper. By mixing such topsoil with a large number of microorganisms into contaminated soil, the number of microorganisms in the entire treated soil finally backfilled also increases. In this sense, not only the topsoil but also a microbial carrier in which microorganisms are supported on a medium such as earth and sand or sawdust may be mixed in the step 210.

  In this example, by previously increasing the number of microorganisms in this way, it is possible to increase the number of living microorganisms after mixing the improving material. In addition, by increasing the number of microorganisms, the number of microorganisms that inhabit the aggregated soil particles also increases. Therefore, as in the above-described embodiment of the contaminated soil treatment method of the present invention, the content of contaminants can be greatly reduced by the hydration heat during construction, and the contaminants can be increased by the increased microorganisms after construction. It can be decomposed and removed continuously and effectively. Moreover, since it is a simple construction of simply mixing the microbial material and then backfilling the improved material, it can be implemented in a short construction period and at low cost.

  Also in the present embodiment, if the granular improvement material is mixed with the contaminated soil, the region exposed to the high pH water can be limited to a local region even when there is rainfall or the like after the construction. And the area where the microbial habitat deteriorates can be minimized. Therefore, it is possible to further restrict the factors that inhibit the activation of microorganisms and to further improve the effect of decomposing pollutants after construction. Moreover, if the improving material in the state of a particle aggregate is mixed with the contaminated soil, the heat generation rate can be further increased in addition to the effect when the granular improving material is used.

Further, the contaminated soil treatment method of the present embodiment can also be constructed by the contaminated soil treatment system previously shown in FIG.
That is, the process of step 210 in FIG. 10 will be described. First, the articulated work arm of the excavator 200 is operated to excavate the contaminated soil a to be treated by the bucket 208 and supply it to the self-propelled mixing machine 100. .

  In this way, the contaminated soil introduced into the sieving device 113 of the self-propelled mixing machine 100 is removed by foreign matter such as large stones by the sieving device 113 and introduced into the lower hopper 119. The contaminated soil received by the hopper 119 is further placed on the conveyor belt of the conveyor conveyor 118 below and conveyed toward the mixing device 110. Then, the microbial material stored in the storage tank 120 during the conveyance is supplied through the supply port 122, and the contaminated soil is introduced into the mixing device 110 together with the microbial material. The contaminated soil and microbial material introduced into the mixing device 110 are uniformly agitated and mixed by the paddle mixer and discharged onto the discharge conveyor 123. Then, the contaminated soil and the mixed soil of the microbial material are conveyed by the discharge conveyor 123 and discharged outside the apparatus.

  The step 220 will be described. The mixed soil discharged from the self-propelled mixing machine 100 may be temporarily placed in a predetermined place, but in this example, the sieve device 513 of the self-propelled mixing machine 500 is directly used. To be supplied. The mixed soil received by the hopper 519 via the sieving device 513 is placed on the transport belt of the transport conveyor 518 and is transported toward the mixing device 510. Then, the improving material in the improving material storage tank 520 is supplied through the supply port 522 during the conveyance, and the mixed soil is introduced into the mixing device 510 together with the improving material. The mixed soil and the improved material introduced into the mixing device 510 are uniformly agitated and mixed by the paddle mixer and discharged onto the discharge conveyor 523. Then, the treated soil generated by mixing the mixed soil and the improving material is further conveyed by the discharge conveyor 523 and discharged outside the machine.

  In the step 230, for example, the processing soil b discharged from the self-propelled mixing machine 500 is backfilled to a target backfilling site d (for example, a drilling site) using a hydraulic excavator 200 or the like.

  After completing the above steps, there is no special construction after that. For example, when using land as a construction site, a facility e is constructed immediately after processing in the backfilling place d where the treated soil b is backfilled. Is possible. Of course, the land is not limited to the construction site. For example, even when the land is used for a parking lot or a ground, the land can be reused immediately after the construction according to the purpose.

  Also in the contaminated soil treatment method of the present embodiment, the contaminated soil treatment system can be simply configured as described above, because the improvement material is simply mixed and backfilled after the microbial material is mixed into the contaminated soil. Further, since both the hydraulic excavator 200 and the self-propelled mixing machines 100 and 500 have a self-propelled function, the degree of freedom of layout is large at the contaminated site, and the movement within the contaminated site is easy. In addition, because it can be lifted and lowered by itself on a carrier such as a trailer, it is excellent in transportability between sites.

FIG. 11 is a flowchart showing the procedure of still another embodiment of the contaminated soil treatment method of the present invention.
As shown in FIG. 11, in the contaminated soil treatment method of the present embodiment, the step 310 of mixing a nutrient that activates microorganisms having oil-degrading ability into the contaminated soil containing the pollutant, and the topsoil to the contaminated soil. Alternatively, the step 320 of mixing a microbial material containing a microbial carrier carrying microorganisms having oil-degrading ability, and the step 330 of mixing an improved material containing quicklime or a lime-based agent into contaminated soil mixed with a nutrient and microbial material. And the step 340 of backfilling the treated soil generated by mixing the nutrient, microbial material, and improving material into the contaminated soil.

  Steps 310 to 340 are the same as steps 110 in FIG. 8 and steps 210 to 230 in FIG. 10 respectively. In this example, in step 330, the particle size is preferably larger than that of single particles. An improved material in the state of a particle aggregate formed by agglomeration of large granules or single fine particles is mixed with the contaminated soil. Moreover, in this Embodiment, the construction order of the process of step 310,320 is not limited. That is, the step 330 may be performed after the step 310 and the step 320 are performed in any order or simultaneously.

  In this example, by combining the embodiments of the contaminated soil treatment method of the present invention described above, the number of surviving microorganisms after mixing with the improving material can be further increased. Thus, the content of pollutants can be greatly reduced, and the pollutants can be decomposed and removed continuously and more effectively even after construction. In addition, since it is a simple construction in which the improving material is mixed and backfilled after mixing the nutrient and microbial material, it can be implemented in a short construction period and at low cost.

  Also in this embodiment, if the granular improvement material is mixed with the contaminated soil, for example, even if there is rainfall after construction, the region exposed to high pH water can be locally restricted, Deterioration of microbial habitat can be minimized. Therefore, it is possible to further restrict the factors that inhibit the activation of microorganisms and to further improve the effect of decomposing pollutants after construction. Moreover, if the improving material in the state of a particle aggregate is mixed with the contaminated soil, in addition to the effect when the granular improving material is used, there is an advantage that the heating rate can be further increased.

Further, the contaminated soil treatment method of the present embodiment can also be constructed by the contaminated soil treatment system previously shown in FIG.
For example, in the self-propelled mixing machine 100, the nutrient agent is stored in a tank (not shown), the nutrient agent is supplied to the contaminated soil, the microorganism material is stored in the storage tank 120, and the microorganism material is supplied to the contaminated soil. . Thereby, in the self-propelled mixing machine 100, the contaminated soil is introduced into the mixing device 110 together with the nutrient and the microbial material, and the contaminated soil is mixed with the nutrient and the microbial material. Further, the mixed soil is introduced into the subsequent self-propelled mixing machine 500 and mixed with the improving material. That is, in this case, the steps 310 and 320 are simultaneously performed by the self-propelled mixing machine 100.

  When the steps 310 and 320 are performed separately, for example, as shown schematically in FIG. 12, two self-propelled mixing machines 100 that respectively perform steps 310 and 320 are arranged, and the preceding self-propelled mixing machine is arranged. After mixing the nutrient with the contaminated soil at 100, the microbial material may be mixed with the mixed soil by the subsequent self-propelled mixing machine 100. Of course, it is also possible to mix the microbial material into the contaminated soil with the front-stage self-propelled mixing machine 100 and then mix the nutrients with the rear-stage self-propelled mixing machine 100. The mixed soil discharged from the subsequent self-propelled mixing machine 100 is supplied to the self-propelled mixing machine 500, mixed with the improving material, and then backfilled.

  Also in the contaminated soil treatment method of the present embodiment, the contaminated soil treatment system can be simply configured as described above, because the improvement material is simply mixed and backfilled after the microbial material is mixed into the contaminated soil. Further, since both the hydraulic excavator 200 and the self-propelled mixing machines 100 and 500 have a self-propelled function, the degree of freedom of layout is large at the contaminated site, and the movement within the contaminated site is easy. In addition, because it can be lifted and lowered by itself on a carrier such as a trailer, it is excellent in transportability between sites.

  The contaminated soil treatment system shown in FIGS. 9 and 12 uses a self-propelled mixing machine unitized with a traveling body, a sieve device, a conveyor, an improved material, a microorganism supply device, etc. The contaminated soil treatment method of the invention is applied if there is at least two mixing devices, that is, at least one mixing device that mixes nutrients and microbial materials with contaminated soil, and a mixing device that mixes improved materials and contaminated soil. Is possible. The mixing device is not based on a paddle mixer, but other mixing methods such as a device that crushes and mixes earth and sand with a rotary hammer that rotates at high speed, a mixer that uses a rotary mixer, a screw mixer, a ribbon screw, a pan type mixer, etc. It is also possible to replace with other mixing devices. In addition, when the amount of contaminated soil to be treated is small, it is not always necessary to construct a system, and it is possible to mix manually. In these cases, the same effect can be obtained.

It is explanatory drawing of the background of this invention, and is a model figure of the soil in which the water supply was formed. It is explanatory drawing of the background of this invention, and is a model figure showing the high pH area | region of the soil in which the water supply was formed. It is explanatory drawing of the background of this invention, and is a model figure showing the aggregate structure of the soil particle. It is explanatory drawing of the background of this invention, and is a model figure showing the high pH area | region of the soil particle of a aggregate structure. It is explanatory drawing of the background of this invention, and is a model figure showing the mixing state of the granular improvement material with respect to soil. It is a model figure of the soil particle of a aggregate structure after mixing a particulate improvement material with contaminated soil. It is the model figure which modeled the state which the water which dissolved the nutrient penetrate | invaded into the soil particle of a aggregate structure after mixing a particulate improvement material with contaminated soil. It is a flowchart showing the procedure of one Embodiment of the contaminated soil processing method of this invention. It is a side view showing the whole structure of one Embodiment of the contaminated soil processing system of this invention for enforcing the contaminated soil processing method of this Embodiment. It is a flowchart showing the procedure of other embodiment of the contaminated soil processing method of this invention. It is a flowchart showing the procedure of further another embodiment of the contaminated soil processing method of this invention. It is a side view showing the whole structure of other embodiment of the contaminated soil processing system of this invention for enforcing the contaminated soil processing method of this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Self-propelled mixing machine 110 Mixing apparatus 500 Self-propelled mixing machine 510 Mixing apparatus a Contaminated soil b Treated soil C Soil fine particle D Soil particle E Improvement material F Improvement material G Microorganism

Claims (7)

Mixing a nutrient that activates microorganisms having oil-degrading ability into contaminated soil containing a pollutant; and
A method for treating contaminated soil, comprising the step of mixing an improved material containing quicklime or a lime-based chemical into the contaminated soil mixed with the nutrient. Mixing a microbial material containing a microbial carrier carrying microorganisms having a topsoil or oil-decomposability into contaminated soil containing a pollutant; and
A method for treating contaminated soil, comprising the step of mixing an improved material containing quicklime or a lime-based chemical into the contaminated soil mixed with the microbial material. Mixing a nutrient for activating microorganisms having oil-degrading ability into contaminated soil containing pollutants, mixing a microbial material containing a microorganism carrier carrying microorganisms having surface soil or oil-degrading ability into the contaminated soil, and In random order or simultaneously
A method for treating contaminated soil, comprising a step of mixing quick lime or an improving material containing a lime-based chemical into contaminated soil mixed with the nutrient and the microbial material.   The improvement material is mixed in a granular state having a particle size larger than that of a single particle or in a state of a particle aggregate formed by aggregation of single particles. The contaminated soil treatment method as described. A mixing means for mixing a nutrient that activates microorganisms having oil-degrading ability in contaminated soil containing a pollutant;
A contaminated soil treatment system, comprising: mixing means for mixing quick lime or an improved material containing a lime-based chemical into the contaminated soil mixed with the nutrient. A mixing means for mixing a microbial material including a microbial carrier carrying microorganisms having a topsoil or oil content resolution into contaminated soil containing a pollutant;
A contaminated soil treatment system comprising: mixing means for mixing quick lime or an improved material containing a lime-based chemical into the contaminated soil mixed with the microbial material. A mixing means for mixing a nutrient agent that activates microorganisms having oil-decomposability in contaminated soil containing a pollutant, and a microbial material including a topsoil or a microorganism carrier carrying microorganisms having oil-decomposability, and
A contaminated soil treatment system, comprising: mixing means for mixing quick lime or an improving material containing a lime-based chemical into the contaminated soil mixed with the nutrient and the microbial material.

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