JP4970627B1 - Pollutant separation and removal method - Google Patents

Abstract

Disclosed is a method for separating and removing pollutants so that the contaminated soil can be processed and taken out in a reduced volume without being carried out of the contaminated site.
An agglomeration flotation separation container is disposed at or near a site where soil contaminated with a pollutant is present. The method for separating and removing pollutants includes a step of scooping and temporarily accumulating soil containing pollutants at the site, excavating the site after scooping up the soil or the vicinity thereof into a predetermined shape, and excavating Forming the isolation tank by forming impermeable walls and impermeable bottom walls on the side and bottom, and screening while applying water washing and vibration to the soil containing the temporarily accumulated contaminants Sieving to a plurality of sizes, the soil components sifted to the minimum size, and the wastewater generated during the washing is put into the isolation tank and agitated, so that the minimum size can be screened. A separation process for precipitating the sediment component contained in the soil component, and draining waste water and floating substances in the isolation tank and throwing them together with a flocculant into the aggregating and floating separation container. Stirring and, after mixing, subjected to aeration at microbubbles, comprising the steps of introducing floating matter floated by aeration managed container, the.
[Selection] Figure 2

Description

  The present invention relates to a method for separating and removing pollutants, and more particularly to a method for separating and removing pollutants suitable for separating and removing pollutants from topsoil and mud contaminated with radioactive substances.

  Various methods have been proposed to remove contaminants in the soil. For example, Patent Document 1 discloses a treatment method and apparatus for soil contaminated with waste materials such as radioactive substances and heavy metals in a mixed state.

JP-A-6-343948

  In addition to the apparatus described in Patent Document 1, most of the various methods proposed so far require large-scale processing equipment that is supposed to be used permanently in a predetermined place. is there. Further, when the soil contaminated area is extensive, a temporary storage place for a large amount of contaminated soil is required, and when the pollutant is a radioactive substance, it is difficult to secure the temporary storage place.

  In the case of contaminated soil treatment for radioactive substances, generally, removal work is performed to scrape off the topsoil contaminated with radioactive substances. Then, the soil generated by this removal work is stored in a temporary storage site (about 3 years), then brought to an intermediate storage facility and further processed at a final disposal site. However, in order to treat a large amount of contaminated soil, an enormous cost can be expected from the transportation cost alone, and it is very difficult to secure a storage place for the contaminated soil.

  Therefore, the problem of the present invention is that the contaminated soil can be discharged in a greatly reduced volume by treating the contaminated soil at or near the generation site without transporting the contaminated soil out of the site. The object is to provide a method for separating and removing substances.

  According to a first aspect of the present invention, there is provided a method for separating and removing a pollutant from a soil contaminated with a pollutant at or near the site where the contaminated soil is located. In addition, a step of flocculating and flotation separating the soil containing the pollutants at the site and temporarily accumulating the soil and excavating the site after the soil has been scraped into a predetermined shape Forming an isolation tank by forming impermeable walls and impermeable bottom walls on the excavated side and bottom, and applying water washing and vibration to the soil containing the temporarily accumulated contaminants The process of sieving into a plurality of sizes by performing screening, the soil components sifted to the minimum size, and the wastewater generated during the washing are put into the isolation tank and stirred. Separation process for precipitating the sediment component contained in the soil component screened to the minimum size, and the waste water and floating matter in the isolation tank are extracted and put into the coagulation and flotation separation container together with the flocculant. And agitation and mixing, aeration with microbubbles, and a floating substance floating by aeration is charged into a control-type container.

  According to a second aspect of the present invention, there is provided a method for separating and removing a pollutant from a soil contaminated with a pollutant at or near the site where the contaminated soil is located. In addition, a step of flocculating and flotation separating the soil containing the pollutants at the site and temporarily accumulating the soil and excavating the site after the soil has been scraped into a predetermined shape Forming a water-impervious side wall and a water-impervious bottom wall on the excavated side and bottom, forming a separation tank, soil containing the contaminants temporarily accumulated in the separation tank, and contamination The substance adsorbing auxiliary material and the kneaded water are added, stirred and mixed, and classified by the difference in specific gravity, and the classified water and the floated substance above it are taken out and at least classified water together with the flocculant Above A step of taking into the collection and flotation separation container, taking out the aggregated precipitate below the classified water and throwing it into a control-type vessel, and the classified water put into the flotation and separation vessel and After the aggregating agent is stirred and mixed, a method of separating and removing pollutants is provided, including the steps of aeration with microbubbles, and placing the levitated material floating by aeration into a control-type container.

  In any of the first and second aspects, a part of the excavated earth and sand, a cement-based solidifying material, and kneaded water are added to the hole excavated into the predetermined shape, and stirred and mixed. After forming the fluidized soil, the structure and the excavation were performed by applying a load by applying a structure having a size smaller than the excavated hole by the thickness of the impermeable sidewall and the impermeable bottom wall. The isolation tank having a volume determined by the size of the structure is formed by interposing the fluidized soil between the side and the bottom of the hole, and extracting the structure when the fluidized soil is solidified. Or a fluidization process formed by stirring and mixing a part of the excavated earth and sand, a cement-based solidifying material, and kneaded water in the hole excavated in the predetermined shape. Throw soil at least the thickness of the impermeable bottom wall. Then, a structure having a size smaller than the excavated hole by the thickness of the impermeable sidewall and the impermeable bottom wall is introduced, and the fluidization treatment is performed in the space between the structure and the side of the hole. By introducing the soil, the fluidized soil is interposed between the structure and the side and bottom of the excavated hole, and when the fluidized soil is solidified, the structure is removed, The isolation tank having a volume determined by the size of the structure can be formed.

  In the first aspect, after the waste water generated in the separation treatment step and the floating material above the waste water are taken out from the isolation tank, the screening is performed on the sediment component precipitated in the isolation tank. A step of filling the excavated hole including the isolation tank by adding a soil component having a size larger than the minimum size screened and another portion of the excavated earth and sand.

  In the second aspect, the classified water and the floated substance above the classified water and the aggregated sediment below the classified water are taken out, and then settled below the aggregated sediment. A step of filling another portion of the excavated sediment on the sand and gravel sediment deposits included in the excavated sediment and refilling the excavated hole including the isolation tank. May be included.

  This method is suitable when the contaminant is a radioactive material contained in topsoil.

  According to the present invention, it is possible to take out contaminated soil which has been processed and reduced in volume without carrying out the contaminated soil outside the contaminated site, transport it to a dedicated disposal site, and dispose of it without a large fixed processing facility. it can.

It is a figure for demonstrating two forms the construction method of the isolation tank provided in the removal work site or its vicinity in order to implement the contaminant separation-and-removal method by this invention. FIG. 3 is a longitudinal sectional view showing an example of a flocculating and separating container for treating wastewater separated in the separation tank of FIG. 1 in order to implement the first embodiment of the contaminant separation and removal method according to the present invention. is there. It is a figure for demonstrating the classification process implemented using the isolation tank constructed | assembled in FIG. 1, in order to implement 2nd Embodiment of the contaminant separation and removal method by this invention. FIG. 3 is a longitudinal sectional view showing an example of a simple coagulation flotation separation container for treating the water separated in the classification process of FIG. 3 in order to carry out the second embodiment of the contaminant separation and removal method according to the present invention. It is. It is a figure for demonstrating an example of the heavy machine used for the excavation of the hole accompanying construction of the isolation tank of FIG. 1, and the stirring accompanying the classification process of FIG.

  First, an example of a ground improvement machine having a ground excavation function and a stirring function associated with fluidization processing for ground improvement will be described with reference to FIG. FIG. 5 shows a ground improvement machine called a backhoe. The backhoe 70 has a first arm 71 and a second arm 72, and a bucket mixer 73 is provided at the tip of the second arm 72. The bucket mixer 73 is supported in a bucket for excavation so that a rotary shaft can be rotated laterally, and a plurality of rotary stirring blades are attached to the rotary shaft at intervals in the axial direction.

  FIG. 5A shows a state where the backhoe 70 inserts the bucket mixer 73 into the ground via the first arm 71 and the second arm 72 to excavate and form a hole.

  FIG. 5B shows a state in which the backhoe 70 performs stirring associated with the fluidization process by moving the bucket mixer 73 vertically and horizontally in the hole while rotating the rotor blades.

  With reference to FIGS. 1 and 2, a first embodiment of the pollutant separation and removal method according to the present invention will be described. Here, a case where a radioactive substance such as cesium 137 is targeted as a contaminant will be described. As a result of radioactive material scattering into the atmosphere, it adheres to the dust and rain in the atmosphere in micron units and comes down to the ground. And it adheres to bark and topsoil. Moreover, the radioactive material scattered on the roof flows into the rainwater, travels along the gutter, and flows down to the drainage channel, and intervenes in the mud of the drainage channel. And the place which needs the removal of the topsoil and mud like the above will be called the field below.

  The method for separating and removing contaminants according to the present invention is characterized in that the above-mentioned radioactive soil-mixed topsoil and mud are not taken out of the field as they are, and the processing work for removing them in a reduced state is performed at the site. Have Moreover, a large fixed processing facility is not required to perform this processing operation.

For this reason, in the first embodiment, a treatment water tank called an isolation tank is constructed in the soil at or near the site, and a material having a high mechanical strength, such as agglomeration of steel, is provided near the treatment water tank. Place a flotation vessel. The size of the separation tank and the flocculation / floating separation container may be about several m ³ to several tens m ³ . In particular, the flocculation / floating separation container has a size that can be carried by a vehicle such as a truck.

  FIG. 1 is a cross-sectional view for explaining two forms of a method for constructing an isolation tank in the soil so that a joint (border) does not occur.

  The topsoil is scraped off at a site of a certain size, and the topsoil that has been scooped up is temporarily accumulated at a specific place in the site. Soiled topsoil is contaminated with radioactive materials.

  Excavation by the backhoe 70 described above is performed in a relatively flat place in the site where the topsoil has been scraped off to form a hole having a predetermined shape. Here, as shown in FIG. 1A, the shape of the hole 10 is a cube or a rectangular parallelepiped, but is not limited thereto. The excavated earth and sand 11 is not contaminated with radioactive materials and is stored beside the hole.

  FIG. 1B to FIG. 1E show a first mode for forming an isolation tank. In FIG. 1 (B), a part of excavated earth and sand 11, cement-based solidified material, and kneaded water are introduced into a hole 10 and stirred and mixed to form a fluidized soil 12. For the stirring and mixing at this time, the bucket mixer 73 of the backhoe 70 described above is used.

  In FIG. 1C, before the fluidized soil is solidified, a structure 20 such as a water tank is placed on the fluidized soil and a load is applied. Here, the shape and size of the structure 20 is a shape in which the hole 10 is reduced, and has such a size that a space of several tens of centimeters or more can be formed between the side portion and the bottom portion of the hole 10. Then, water is poured into the structure 20 and a load is applied to cause the structure 20 to sink (FIG. 1D). The second arm 72 of the backhoe 70 can also be used for loading the structure 20, and when the load is insufficient, the second arm 72 may be used. The sinking is continued until the distance between the bottom of the hole 10 and the bottom of the structure 20 becomes the same as the impermeable bottom wall of the isolation tank, after which the structure 20 is suspended so as not to sink. Alternatively, water is drained from the structure 20. The structure 20 is not limited to a water tank as long as the outer shape is a shape obtained by reducing the size of the hole 10 and has a mechanical strength capable of applying a load.

  In FIG. 1 (E), when the fluidized soil is solidified, the structure 20 is taken out. As a result, the isolation tank 30 defined by the water shielding side wall 31 and the water shielding bottom wall 32 having a thickness of several tens of centimeters or more is formed in the hole 10. In this isolation tank 30, the water shielding side wall 31 and the water shielding low wall 32 are constructed integrally, and there is no seam, so that no leakage occurs in the subsequent separation process.

  FIG. 1 (F) to FIG. 1 (I) show a second mode for forming an isolation tank. In the second embodiment, a part of excavated earth and sand 11, cement-based solidified material, and kneaded water are put into a container at a place different from the hole 10 and stirred to mix to form a fluidized soil. To do. For the formation of the fluidized soil, a relatively large container used for forming a slurry at a normal construction site can be used, and the above-described backhoe 70 is also used for stirring and mixing. A bucket mixer 73 is used.

  In FIG. 1 (F), a part 12 ′ of the fluidized soil thus formed is put into the hole 10. Note that only this input amount may be formed in the hole 10 by the same method as in the first embodiment.

  In FIG. 1 (G), before the fluidized soil in the hole 10 is solidified, the same structure 20 as in the first embodiment is put on the fluidized soil. Then, the fluidized soil prepared in another place is put into a space formed between the hole 10 and the structure 20 (FIG. 1 (H)). At this time, water is injected into the structure 20 or a load is applied by the second arm 72 of the backhoe 70 so that the structure 20 does not float by the fluidized soil that has been introduced.

  In FIG. 1I, when the fluidized soil is solidified, the structure 20 is taken out. As a result, as in the first embodiment, the isolation tank 30 defined by the water shielding side wall 31 and the water shielding bottom wall 32 having a thickness of several tens of centimeters or more is formed in the hole 10. In this isolation tank 30, the water shielding side wall 31 and the water shielding low wall 32 are constructed integrally, and there is no seam, so that no leakage occurs in the subsequent separation process.

  As will be described later, the impermeable side wall 31 and the impermeable bottom wall 32 formed by stirring and mixing the cement-based solidified material, the excavated earth and sand 11, and the kneaded water are sufficient for the subsequent separation process. Mechanical strength and water shielding performance, but mechanical strength is small compared to concrete. Thereby, in the case of the backfill performed after completion | finish of a separation process, when crushing the impermeable side wall 31 and the impermeable bottom wall 32, there exists an advantage that it is easy to crush.

  Next, a separation process performed using the isolation tank 30 formed according to the first or second embodiment will be described.

  Prior to this separation process, a screening process is performed on topsoil accumulated at a specific place in the site using a screening machine that performs sieving while applying water washing and vibration. Screening is performed by screening over three stages, for example, 10 mm, 4 mm, and 2 mm. Such screening is often performed in order to preliminarily sort the topsoil because it contains fallen leaves, garbage, pebbles, and gravel. In particular, this screening is carried out while washing with water, and by setting the washing time appropriately within a range of several minutes, the amount of radioactive material attached, in other words, the radiation dose, except for soil of 2 mm or less in size, is reduced. It can be greatly reduced. When the radiation dose was measured for a sorting result exceeding 2 mm which is the minimum screening size, it was reduced to about 1/4 or less. Thereby, the sorting result exceeding 2 mm generated by the above screening may be backfilled as it is without requiring any special processing.

  On the other hand, the soil with a size of 2 mm or less contains fine particles (mainly fine soil components called silt) in addition to the sediment component, and most of the radioactive material in the topsoil is attached to the silt. Exists. For this reason, about the waste water of the washing water used for screening, and the soil of the size of 2 mm or less, the radiation dose is higher than the surface soil before screening, and a separation process is required. Therefore, the following separation process is performed using the isolation tank 30.

  The waste water of the washing water generated during the screening and the soil having a size of 2 mm or less are put into the isolation tank 30. In the isolation tank 30, stirring is performed using a bucket mixer 73 to separate a fine silt component to which earth and sand components and radioactive substances are attached from soil having a size of 2 mm or less. As a result, in the isolation tank 30, the silt component and the earth and sand component to which the radioactive substance is attached are separated, and the silt component is suspended in the muddy water, but the earth and sand component is precipitated. And since the sediment component which does not contain the fine particle component to which the radioactive substance adhered is attached, the radiation dose is greatly reduced, and it may be refilled as it is without requiring any special treatment thereafter.

  The muddy wastewater and levitated matter in the isolation tank 30 are sent to the next agglomeration levitating separation container by pumping up.

  In addition, when there are a lot of waste water generated by screening and soil having a size of 2 mm or less, two or three or more separation tanks 30 may be formed according to the size of screening, and separation processing may be performed for each tank.

  FIG. 2 is a longitudinal cross-sectional view showing an example of a container for aggregation and levitation separation.

  In FIG. 2, the flocculation / floating separation container 100 has a tank divided into at least three, here four, from the wastewater inlet side (upstream side) to the clarified water outlet side (downstream side). . That is, from the upstream side, the first agitation tank 110 in which the first agitator 111 is arranged, the second agitation tank 120 in which the second agitator 121 is arranged, and the aspirator 132 connected to the microbubble generator 131 are arranged. The floated separation tank 130 and the clear water storage tank 140 are partitioned. There may be at least one stirring tank.

  Here, in order to give the stirring effect by convection, the partition wall 115 between the first stirring tank 110 and the second stirring tank 120 is provided with a communication port on the upper side thereof, while the second stirring tank 120 is provided. And a separation wall 125 between the levitation separation tank 130 and a communication port on the lower side thereof.

  The first agitation tank 110 is charged with a flocculant in addition to the waste water and floating substances generated in the separation process. The flocculant is for adhering to fine particles such as silt to which radioactive substances are attached in wastewater, and for promoting flotation separation in the flotation separation tank 130. Commercially available materials can be used.

  The flocculant charged into the first agitation tank 110 is stirred and mixed with the waste water in the first agitation tank 110 and the second agitation tank 120 by the first agitator 111 and the second agitator 121. By repeating convection up and down, it adheres to fine particles such as silt where radioactive substances adhere to the wastewater. In the following, the flocculant and the fine particles attached are referred to as a suspension.

  In the floating separation tank 130, aeration with the microbubbles generated by the microbubble generator 131 is performed. The microbubble generator is a device that generates fine bubbles having a bubble diameter of several tens of μm or less at the time of generation, and is a combination of a plurality of aspirators and a pump for supplying air. Then, by placing an aspirator 132 at the bottom of the floating separation tank 130 and performing aeration of microbubbles in the floating separation tank 130, microbubbles are generated in the suspension in the wastewater flowing from the second stirring tank 120. To promote the floating of the suspension.

  While the suspended matter with microbubbles floats as scum, the water from which the suspended matter has been removed hardly contains the radioactive material contained in the topsoil and flows into the storage tank 140 as clear water. The floated scum is scooped up by the scraper 141 and put into the scum tank 150. In addition, when a floating thing exists also in the 1st stirring tank 110 and the 2nd stirring tank 120, this is also thrown into the scum tank 150.

  The scum in the scum tank 150 contains a radioactive material in a condensed form, so it needs to be processed at the final disposal site. After draining, the scum is drained with a dehydrator, stored in a managed container as a solid, and transported to a final disposal site. Managed containers are made to have the sealing function, mechanical strength, etc. necessary to safely transport scum containing radioactive materials to the final disposal site.

  Since the clarified water in the storage tank 140 contains almost no radioactive substance, it may be discharged into the river as it is, or may be reused for cleaning or separation processing in the isolation tank 30.

  Further, the separation tank 30 after the separation treatment can be continuously used for the separation treatment while the amount of the sediment deposit is small, but when the thickness of the sediment sediment reaches a certain value, the sediment sedimentation is performed. The earth and sand 11 stored beside the hole 10 is thrown over the object and backfilled. When the hole 10 is backfilled, the isolation tank 30 may be left as it is, or the water-impervious side wall 31 and the water-impervious bottom wall 32 may be crushed and backfilled. In addition, soil components having a size exceeding 20 mm generated during screening contain almost no radioactive substances, and therefore may be backfilled together at the time of backfilling.

  If contaminated topsoil is temporarily accumulated at a specific location on the site, a new isolation tank will be built at another location on the site and the above separation process and coagulation flotation separation process will be performed. And separate radioactive material from the topsoil.

As an example, if the topsoil contaminated with the radioactive material is scraped by about 5 cm for an area of 20 m × 20 m, the amount of topsoil scooped out is 20 m ³ . In this case, when a hole 10 having a length and width of 5 m and a depth of 3 m is excavated to form an isolation tank 30 including a water-impervious side wall 31 having a thickness of 0.5 m and a water-impervious bottom wall 32 having a thickness of 1 m, The capacity is 4 * 4 * 2 = 32 m ³ , which is large enough for separation processing for a top soil amount of 20 m ³ . In general, topsoil consists of 20% air, 45% pore water, 25% sand and humus, and 10% clay and silt, and the target silt component is estimated to be 10% or less. Therefore, the amount of scum containing radioactive material does not exceed 3 m ³ even if the flocculant is included, and is reduced to about 1/10 of the case of carrying the entire topsoil.

  Next, a second embodiment of the pollutant separation and removal method according to the present invention will be described with reference to FIGS. In the second embodiment, the screening in the first embodiment is not performed, and the aggregation and separation container can be a simple container.

  In FIG. 3 (A), the topsoil accumulated at a specific place in the field and the pollutant adsorbing auxiliary material are introduced into the isolation tank 30 and the kneaded water is added to perform stirring and mixing (FIG. 3). (B)). The bucket mixer 73 of the backhoe 70 is also used for this stirring and mixing.

  When the stirring and mixing are sufficiently performed, the bucket mixer 73 is lifted to stop the stirring and mixing, and left for a certain period of time. As shown in FIG. From the bottom, in order from the bottom, sand, gravel gravel sediment 41 contained in the topsoil, agglomerated sediment 42 containing radioactive material attached to the silt contained in the topsoil, water 43, Classification is performed in the order of the levitated material 44 lighter than water.

  The radioactive material contained in the topsoil is contained in the aggregated precipitate 42 mainly in the form of adhering to the silt, but is also contained in the water 43. Strictly speaking, it is included in the water 43 because fine particles to which radioactive substances are attached that cannot be grasped by the contaminant adsorption auxiliary material remain in the water 43. In the aggregated precipitate 42, the radioactive substance is included in a state of adhering to the silt that has adhered to the contaminant adsorbing auxiliary material and precipitated. On the other hand, since the sediment sediment 41 does not contain silt, the radioactive material contained in the topsoil is hardly contained. Of course, about the sediment deposit 41, after measuring a radiation dose and confirming that it is less than an allowable amount, it is refilled as described later.

  In addition, bentonite, zeolite, etc. can be used as a pollutant adsorption auxiliary material. It is preferable to use a pollutant adsorbing auxiliary material that is colored so that it can be easily distinguished from the sediment sediment 41 when the aggregate sediment 42 is taken out from the isolation tank 30.

  The levitated material 44 classified in the isolation tank 30 is scooped out and discarded after draining. The water 43 is pumped up and transferred to the above-described aggregation / floating / separation container 100 or a simple aggregation / floating / separation container described later. In addition, the radiation dose is also measured for the levitated matter 44, and when it exceeds the allowable amount, the levitated matter 44 is transferred together with the water 43 to the agglomeration levitating separation container. Subsequently, the aggregated precipitate 42 is scraped off by the backhoe 70 and is put into a management type container. Since the aggregated sediment 42 contains the radioactive material attached to the silt in a condensed form, the managed container is transported to the final disposal site.

  In the case of using the above-described flocculation / floating / separation container 100, water in the isolation tank 30 is put into the first stirring tank 110 together with the flocculation / separation agent. Subsequent processing is as described above.

  With reference to FIG. 4, the agglomeration floating separation process performed using the simple type aggregation flotation separation container 60 different from the aggregation flotation separation container 100 described in FIG. 2 will be described.

  In FIG. 4 (A), the same flocculant as the flocculant described in FIG. 2 is added to the water 43 (FIG. 3C) charged into the simple type coagulation / floating separation container 60 and stirred and mixed. The bucket mixer 73 of the backhoe 70 can be used for this stirring and mixing. As an example, when stirring is performed for about 30 to 120 seconds at a rotational speed of a rotating blade of the bucket mixer 73 of about 600 to 1200 rpm, the bucket mixer 73 is pulled up and stirring and mixing are stopped.

  Subsequently, in FIG. 4B, the aspirator 65 of the microbubble generator is put into the simple coagulation levitation separation container 60 and aeration with the microbubbles is performed, and the microbubbles are fine particles with radioactive substances attached thereto. And adhering to a suspension containing a flocculant to promote floating of the suspension.

  When the occurrence of scum, that is, sufficient floating of the suspended matter is confirmed, the aeration is stopped and separated into sediment, water, and floating matter due to the difference in specific gravity. According to such a flocculation and flotation process, the sediment and water contain almost no radioactive substances contained in the topsoil, but are contained in the suspended matter (fine particles attached to the foam) that floated as scum. It becomes a state. Therefore, the vacuum means removes the scum, drains the water, and then dehydrates it with a dehydrator, stores it as a solid in a managed container, and transports it to the final disposal site. The water generated in the draining process is returned to the simple coagulation levitation separation container 60 and reprocessed.

  In addition, also when the amount of the sediment deposit 41 is small, the isolation tank 30 after the classification treatment can be left as it is and reused for the next classification treatment. Usually, the sediment sediment 41 is used. The earth and sand 11 stored beside the hole 10 is thrown into the top and filled back. When the hole 10 is backfilled, the isolation tank 30 may be left as it is, or the water-impervious side wall 31 and the water-impervious bottom wall 32 may be crushed and backfilled.

  If contaminated topsoil is temporarily accumulated at a specific location on the site, a new isolation tank will be built at another location on the site, and the above classification and flocculation / floating separation will be performed. And separate radioactive material from the topsoil.

  Also in the second embodiment, the principle of the separation and removal of pollutants is the same as that in the first embodiment, so the amount of pollutants that need to be transported to the final disposal site is 1 / It is reduced to about 10. In addition, the simplified coagulation / floating / separation container 60 is less expensive than the coagulation / floating / separation container 100 of the first embodiment.

  As described above, the two embodiments of the present invention have been described for the case where the topsoil contaminated with the radioactive material is targeted. However, the present invention is the case where the radioactive material flying to the roof in a state of adhering to the fine particles as described above. It is possible to separate radioactive substances by the same separation or classification treatment and coagulation flotation separation treatment for mud that is washed away by rainwater, flows down the rain gutter and falls into the drainage channel, and mixes in the mud of the drainage channel. it can. Moreover, it can be applied not only to radioactive substances but also to pollutants such as heavy metals that cause pollution.

  The isolation tank may be realized by embedding a metal container in the excavated hole according to the situation at the site. In this case, the container is taken out after completion of the separation process and used for the separation process at another site. You may do it.

  The form of screening is not limited to a screening machine that performs sieving while applying washing and vibration with water, and other screening methods may be employed.

10 hole 11 excavated earth and sand 12, 12 ′ fluidized soil 20 structure 30 isolation tank 31 impermeable side wall 32 impermeable bottom wall 60 simplified coagulation floating separation vessel 65, 132 aspirator 70 backhoe 71 first arm 72 first arm 72 Two arms 73 Bucket mixer 100 Coagulation flotation separation vessel 110 First agitation tank 120 Second agitation tank 130 Flotation separation tank 131 Microbubble generator 140 Reservoir 150 150 Scum tank

Claims (7)

A method for separating and removing contaminants from soil contaminated with contaminants at or near the site of the contaminated soil,
Place a container for agglomeration and flotation at or near the site,
Scooping and temporarily accumulating soil containing contaminants at the site;
Excavating the site after scooping up the soil or the vicinity thereof into a predetermined shape, forming a water-impervious side wall and a water-impervious bottom wall at the excavated side and bottom, and forming an isolation tank;
Screening the plurality of sizes by performing screening while applying water washing and vibration to the soil containing the temporarily accumulated contaminants; and
Separation of sediment components contained in the minimum-sized soil component by stirring the soil component screened to the minimum size and the waste water generated during the washing into the isolation tank and stirring. Processing steps;
The waste water and floating substances in the isolation tank are extracted, put into the coagulation / floating separation container together with the coagulant, stirred and mixed, then aerated with microbubbles, and the floating substance floating by aeration is put into a management type container. The process of input,
A method for separating and removing pollutants. A method for separating and removing contaminants from soil contaminated with contaminants at or near the site of the contaminated soil,
Place a container for agglomeration and flotation at or near the site,
Scooping and temporarily accumulating soil containing contaminants at the site;
Excavating the site after scooping up the soil or the vicinity thereof into a predetermined shape, forming a water-impervious side wall and a water-impervious bottom wall at the excavated side and bottom, and forming an isolation tank;
The step of adding the soil containing the contaminants temporarily accumulated in the isolation tank, the contaminant adsorption auxiliary material, and the kneaded water, stirring, and mixing,
As a result of classification based on the difference in specific gravity, the classified water and the floating substance above it are taken out, and at least the classified water is put together with the flocculant into the coagulation and flotation separation container, and below the classified water. A step of taking out the aggregated precipitate and putting it in a control-type container;
Stirring and mixing the classified water and the flocculant charged in the flocculating and separating container, and performing aeration with microbubbles, and charging the floated material floating by aeration into a management-type container;
A method for separating and removing pollutants.   A portion of the excavated earth and sand, a cement-based solidified material, and kneaded water are added to the hole excavated into the predetermined shape, and stirred and mixed to form a fluidized soil, and then the excavated hole The fluidization is performed between the structure and the side and bottom of the excavated hole by applying a load by introducing a structure having a size smaller than the thickness of the impermeable sidewall and the impermeable bottom wall. The pollutant according to claim 1 or 2, wherein a treatment soil is interposed, and when the fluidized treatment soil is solidified, the structure is extracted to form the isolation tank having a volume determined by the size of the structure. Separation removal method.   The fluidized soil formed by stirring and mixing a part of the excavated earth and sand, a cement-based solidified material, and kneaded water in the hole excavated into the predetermined shape is at least the thickness of the impermeable bottom wall. Then, a structure having a size smaller than the excavated hole by the thickness of the impermeable sidewall and the impermeable bottom wall is introduced, and the fluid flows into the space between the structure and the side of the hole. The fluidized soil is interposed between the structure and the side and bottom of the excavated hole by introducing the fluidized soil, and when the fluidized soil is solidified, the structure is removed. The method for separating and removing contaminants according to claim 1 or 2, wherein the isolation tank having a volume determined by the size of the structure is formed.   Further, after the waste water generated in the separation treatment step and the floating material above it are taken out from the isolation tank, the minimum size screened in the screening on the sediment component precipitated in the isolation tank. The method for separating and removing pollutants according to claim 1, further comprising a step of refilling the excavated hole including the isolation tank by introducing a larger size soil component and another part of the excavated sediment.   Further, after taking out the classified water and the floated substance above the classified water and the aggregated sediment below the classified water, the excavated sediment is settled below the aggregated sediment. 3. The method according to claim 2, further comprising a step of filling another portion of the excavated earth and sand to fill the excavated hole including the isolation tank onto the sand and gravel sediment sediment. Pollutant separation and removal method.   The method for separating and removing contaminants according to claim 1, wherein the contaminant is a radioactive material contained in topsoil.

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