JP2007209911A - Contaminated soil treatment method by deep layer mixing treatment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a treatment method which enables the production of a solidifying material slurry for containment into ground by recovering bottom mud or contaminated soil, and mixing contaminant-containing slurry with a solidifying material, a purifying agent and the like, and performs containment treatment by kneading the solidifying material slurry deeply into the ground on land, or in sea by using a deep layer mixer, and insolubilizing it so as to prevent diffusion. <P>SOLUTION: The solidifying material slurry for containment into ground is kneaded within a range from a prescribed depth below the water bottom surface or the ground surface to a predetermined depth of a soil improvement by agitation and mixing treatment. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention mainly includes dioxins, PCBs, agricultural chemicals contained in bottom mud that forms the bottom of ports, rivers, lakes, etc., or on land such as trash incinerators, chemical factory sites, agricultural land, or contaminated soil in the vicinity. When the pollutants such as the above are diffused at a relatively low concentration, the bottom mud or the contaminated soil is recovered, and the mud slurry containing the pollutants is mixed with the solidifying material and the purification agent. Producing solidified slurry for containment into the ground ", deeply kneading into the ground on the ground or into the bottom of the bottom using a deep mixing treatment device, insolubilizing to prevent diffusion, and containment treatment (harmless Belongs to the technical field of contaminated soil treatment method.

The bottom mud that forms the bottom of ports, rivers, lakes, etc., or dioxins that elute and diffuse from contaminated soil on land will have a negative impact on human society and the health of the human body through the food chain. Therefore, it is necessary to block the route through which humans ingest dioxins, or to block it before the food chain. Conventionally, as countermeasures, the following three kinds of bottom mud formed mainly on the water bottom have been considered and implemented.
(I) A method of dripping contaminated bottom mud or excavating and removing contaminated soil (for example, see Patent Document 1 below).
(Ii) A method of covering sand with good quality sand on the contaminated bottom mud of the water bottom (see Patent Document 2 below).
(Iii) A method of solidifying contaminated bottom mud and contaminated soil in situ (see Patent Documents 3, 4, 5, 6, and 7 below).

The method (i) of dripping contaminated bottom mud or excavating and removing contaminated soil is a method with a large risk reduction effect. However, success or failure depends on whether final disposal can be performed according to the degree of contamination of the bottom mud and ground, and how the amount of bottom mud and soil in the final disposal can be reduced.
The method (ii) for covering sand has a lot of construction results. However, it is necessary to monitor the sustainability of the bottom mud roll-up suppression effect over a long period of time. If sufficient results are not confirmed as a result of monitoring, it is necessary to implement other countermeasures such as dredging and excavation. Moreover, since the pollutant remains, there is a problem that it is not a fundamental countermeasure.
Even in the method (iii) of solidifying the contaminated bottom mud and contaminated soil in situ, there is a problem that the pollutant continues to remain in the environment. Moreover, it is necessary to solve the difficulty of quality control by preventing turbidity and diffusion of water during construction. Therefore, if sufficient results cannot be confirmed as a result of monitoring, it is necessary to implement other measures such as dredging and excavation.
In short, the existing technology has both merits and demerits in all countermeasure methods.

As another countermeasure method, Patent Document 8 below discloses a purifying agent such as soil or ground water that can decompose and insolubilize organic halogen compounds contained in soil, particularly dioxins, PCBs, and heavy metals. .
Further, Patent Document 9 sucks sludge containing contaminants, while discharging the suction sludge into the soil where the sludge stirring means is located, and then kneads the sludge into the surrounding soil by the stirring means. A purification method is disclosed. However, the depth of kneading into the soil by this method is described as an area of about 5 m (second line of paragraph number [0017] of the same publication). Therefore, there are doubts and concerns about the effect and reliability of insolubilization and containment to prevent diffusion.

JP 2004-44268 A JP 2004-92244 A JP 2004-298659 A JP 2004-308199 A JP 2003-147355 A Japanese Patent No. 3610458 JP-A 64-47414 Japanese Patent Laid-Open No. 2005-21882 JP 2005-282232 A

  As mentioned above, pollutants such as dioxins, PCBs, agricultural chemicals, etc. that are eluted and diffused or rolled up from the bottom mud that forms the bottom of the water or the contaminated soil on land, have an adverse effect on human society through the food chain. Various countermeasure methods and purifiers for blocking the light have been proposed or implemented. At present, however, there is no countermeasure method suitable for contamination at a relatively low concentration of several times the environmental standard.

Therefore, the object of the present invention is to enable large-scale implementation suitable for industrial use, and insolubilize and contain in a content that can safely prevent the elution and diffusion of pollutants without using a special processing machine It is to provide a contaminated soil treatment method.
The next object of the present invention is to provide a treatment method for insolubilizing and containing contaminated soil that can be used for both long-term purification and decomposition treatment using a deep mixing treatment method and an appropriate soil purification agent. It is to be.

As a means for solving the above-mentioned problem, a method for treating contaminated soil by deep mixing treatment according to the invention described in claim 1 is:
The bottom mud 3 containing pollutants in the bottom 2 is recovered, and a mud slurry made of clay, silt, water, etc. containing pollutants, excluding coarse particles such as gravel and sand, according to the particle size of the soil particles, In the construction method of mixing a solidifying material such as cement, a purifying agent and an additive to produce a solidifying material slurry for containment in the ground, and embedding it in the ground using the deep mixing processing device 5,
The solidification material slurry for containment in the ground is kneaded by stirring and mixing in a range S below a certain depth T below the bottom surface 2 or the ground surface and up to a planned depth 16 of ground improvement. Features.

The method for treating contaminated soil by the deep mixing treatment according to the invention described in claim 2 is:
Muddy water slurry consisting of clay, silt, water, etc. containing pollutant that collects coarse particles such as gravel, sand, etc. according to the particle size of soil particles, collecting bottom mud 3 containing pollutant in bottom 2 Is mixed with a solidifying material such as cement, a purifying agent and an additive to produce a solidifying material slurry for containment in the ground, and this is supplied to the deep mixing device 5.
The penetration step of the stirring and mixing shaft 15 in the deep mixing treatment device 5 is performed up to the planned depth (T + S) for ground improvement.
In the subsequent lifting step, a stirring and mixing process in which the solidifying slurry for containment into the ground is discharged from the vicinity of the top of the stirring and mixing shaft 15 is moved upward from the bottom 16 of the ground improvement to the bottom surface 2 or the surface of the ground. The process is performed in a range S that reaches a certain downward depth T.
At the stage where the stirring and mixing shaft 15 is pulled up to a certain depth T below the bottom surface 2 or the ground surface, discharge of the solidifying slurry for containment into the ground is stopped, and then the stirring and mixing shaft 15 is moved to the bottom surface 2 or It is characterized by pulling up to the ground surface.

The method for treating contaminated soil by the deep mixing treatment according to the invention described in claim 3 is:
Muddy water slurry consisting of clay, silt, water, etc. containing contaminants collected from soil containing onshore contaminants and treated with deaerated water to remove coarse particles such as gravel and sand according to the particle size of the soil particles In the construction method of mixing a solidifying material such as cement, a purification agent and an additive to produce a solidifying material slurry for containment in the ground, and embedding it in the ground using the deep mixing treatment device 5,
The solidifying slurry for containment into the ground is kneaded by stirring and mixing in a range S below a certain depth T below the surface of the bottom of the water or the ground surface 2 and up to a planned depth 16 of ground improvement. Features.

The processing method of the contaminated soil by the deep mixing processing according to the invention described in claim 4 is:
Muddy water slurry consisting of clay, silt, water, etc. containing contaminants collected from soil containing onshore contaminants and treated with deaerated water to remove coarse particles such as gravel and sand according to the particle size of the soil particles Is mixed with a solidifying material such as cement, a purifying agent and an additive to produce a solidifying material slurry for containment in the ground, and this is supplied to the deep mixing device 5.
The penetration step of the stirring and mixing shaft 15 in the deep mixing treatment device 5 is performed up to the planned depth (T + S) for ground improvement.
In the subsequent pulling step, a stirring and mixing process for discharging the solidifying slurry for containment into the ground from the vicinity of the upper part of the stirring and mixing shaft 15 is performed upward from the lowermost part 16 of the ground improvement and below the bottom surface or the ground surface 2. It is performed in a range S that reaches a certain depth T.
At the stage where the stirring and mixing shaft 15 is pulled up to a certain depth T below the bottom surface or the ground surface 2, the discharge of the solidifying slurry for containment into the ground is stopped, and then the stirring and mixing shaft 15 is moved to the bottom surface or the ground. It is characterized by pulling up to the surface 2.

Invention of Claim 5 in the processing method of the contaminated soil by the deep layer mixing process as described in any one of Claims 1-4,
In the penetration step of the stirring and mixing shaft 15, only the stirring by the stirring and mixing shaft 15 is performed from the water bottom surface or the ground surface 2 to the planned depth (T + S) of ground improvement.
In the subsequent pulling step, first, a stirring and mixing process for discharging the solidified slurry for containment into the ground from the vicinity of the upper part of the stirring and mixing shaft 15 is performed upward from the lowermost part 16 of the ground improvement and below the bottom surface or the ground surface 2. It is performed in a range S that reaches a certain depth T.
At the stage where the stirring and mixing shaft 15 is pulled up to a certain depth T below the water bottom surface or the ground surface 2, the discharge of the solidifying slurry for containment into the ground is stopped, and then a solidifying material such as cement is used. The stirring / mixing process of discharging the solidified slurry having the normal composition from the vicinity of the upper portion of the stirring / mixing shaft 15 is performed up to the water bottom surface 2 or the ground surface.

Invention of Claim 6 in the processing method of the contaminated soil by the deep layer mixing process as described in any one of Claims 1-4,
In the penetration process of the stirring and mixing shaft 15, a stirring and mixing process in which a normally mixed solidifying material slurry using a solidifying material such as cement is discharged from the tip of the stirring and mixing shaft 15 is performed at a constant depth below the bottom surface or the ground surface 2. At this depth, the discharge of the solid compound slurry of the normal composition is stopped, and after that, only the stirring by the stirring and mixing shaft 15 is performed to the planned depth (T + S) for ground improvement.
In the subsequent pulling step, first, a stirring and mixing process for discharging the solidified slurry for containment into the ground from the vicinity of the upper part of the stirring and mixing shaft 15 is performed upward from the lowermost part 16 of the ground improvement and below the bottom surface or the ground surface 2. It is performed in a range S that reaches a certain depth T.
At the stage where the stirring and mixing shaft 15 is pulled up to a certain depth T below the water bottom surface or the ground surface 2, the discharge of the solidifying slurry for containment into the ground is stopped, and thereafter only the stirring by the stirring and mixing shaft 15 is performed. The treatment is performed up to the bottom surface 2 or the ground surface.

The invention described in claim 7 is a method for treating contaminated soil by the deep mixing process according to any one of claims 1 to 4,
In the step of penetration of the stirring and mixing shaft 15, a stirring and mixing process in which a normally mixed solidifying material slurry using a solidifying material such as cement is discharged from the tip of the stirring and mixing shaft 15 is scheduled to be improved from the bottom surface or the ground surface 2. Repeat to depth (T + S).
In the subsequent pulling step, first, a stirring and mixing process for discharging the solidified slurry for containment into the ground from the vicinity of the upper part of the stirring and mixing shaft 15 is performed upward from the lowermost part 16 of the ground improvement and below the bottom surface or the ground surface 2. It is performed in a range S that reaches a certain depth T.
At the stage where the stirring and mixing shaft 15 is pulled up to a certain depth T below the water bottom surface or the ground surface 2, the discharge of the solidifying slurry for containment into the ground is stopped, and then a solidifying material such as cement is used. The stirring / mixing process of discharging the solidified slurry having the usual composition from the vicinity of the upper portion of the stirring / mixing shaft 15 is performed up to the water bottom surface 2 or the ground surface.

The invention described in claim 8 is a method for treating contaminated soil by the deep mixing process described in any one of claims 1 to 4,
Purifies pollutants such as dioxins, PCBs, and pesticides in mud slurry consisting of clay, silt, water, etc. containing pollutants collected from the bottom mud 3 containing pollutants in the bottom 2 or land containing pollutants As a cleaning agent, metallic iron powder, a metal-based reducing agent composed of carbon or other noble metals, or a material containing a metal such as iron and a metal oxide such as iron oxide or titanium oxide, or sodium sulfite, sodium bisulfite, etc. A material containing a reducing agent and a metal oxide such as iron oxide or titanium oxide is used.

Invention of Claim 9 in the processing method of the contaminated soil by the deep layer mixing process as described in any one of Claims 5-7,
The constant depth T below the bottom surface 2 or the ground surface, to which the normally mixed solid material slurry using a solid material such as cement should be discharged, is twice the distance H between the upper and lower discharge ports of the stirring and mixing shaft 15. The depth is equivalent to three times.

High-concentration thin-layer dredging such as bottom mud 3 containing pollutants in the bottom 2 by dredger 1, or grab dredging technology, excavation and removal technology for contaminated soil on land by power shovel, etc., and sediment classification / washing plant Technology to collect mud slurry consisting of clay, silt, water, etc. containing pollutants in accordance with the particle size of soil particles by removing coarse particles such as gravel and sand, and on-ground ground by the deep mixing treatment device 5 And the technology of the improved treatment method for the submarine ground 2 is a past technology that has already had a large number of construction results, is excellent in ease of implementation and certainty of construction effects, and is highly feasible. Moreover, it can be used and implemented on a large scale in the industry, and it is kneaded deeply into the soil in a state where there is no risk that the pollutant will be eluted from the contaminated soil or the bottom mud 3 of the bottom 2 and spread or rolled up. Safe insolubilization and containment.
On the other hand, coarse particles such as gravel and sand recovered by classification can be reused as resources.

  Collecting contaminated soil on the land or bottom mud 3 of the bottom 2 and classifying and washing it to produce “solidified slurry for containment in the ground”, and the above “containment in the ground” The deep mixing treatment method for land or submarine ground 2 implemented using “solidifying material slurry” is a conventional system itself and is a completely closed system that is deeply insolubilized in land or underwater 2 Contained contaminants are unlikely to elute or diffuse into water or air again. In other words, pollutants are solidified and kneaded deeply in land and underwater ground, insolubilized and contained, so they are stable for a long time without being affected by scouring or outflow due to stormy weather such as floods or typhoons, and ocean current Processing effects can be obtained.

  In addition, since the “solidifying material slurry for containment in the ground” is treated by mixing a cleaning agent such as iron powder, not only the above solidification and insolubilization effects, but also long-term decomposition and purification are actively carried out. Promoting and reliably reducing the likelihood that contained contaminants will remain in the environment. Moreover, in the case of using the improved treatment method for the submarine ground 2, it is possible to reinforce with the improved body 12 by the deep mixing process with respect to adverse effects on marine structures such as revetments. In addition, the anchorage of the anchored ship is not adversely affected, and the influence on the ship route can be eliminated by changing the construction site.

  The bottom mud 3 containing pollutants in the bottom 2 is recovered, and a mud slurry made of clay, silt, water, etc. containing pollutants, excluding coarse particles such as gravel and sand, according to the particle size of the soil particles, A “solidifying slurry for containment in the ground” is produced by mixing a solidifying material such as cement, a purifying agent and an additive. Soil containing on-land pollutants is a slurry of clay, silt, water, etc. containing pollutants that are collected and treated with degassed water after removing coarse particles such as gravel and sand according to the particle size of the soil particles. Is mixed with a solidifying material such as cement, a purifying agent and an additive to produce a “solidifying material slurry for containment in the ground”. When embedding the “solidifying material slurry for containment into the ground” into the ground using the deep mixing treatment device 5, the ground is improved below a certain depth T below the bottom surface or the ground surface 2. The kneading process is performed in the range S up to the planned depth 16 by the stirring and mixing process.

More specifically, the mud slurry obtained by collecting the bottom mud 3 containing the pollutant in the water bottom 2 or collecting the ground containing the pollutant on the land includes a solidifying material such as cement, a purifier, and an additive. This is mixed with an agent to produce a “solidifying slurry for containment in the ground”, which is supplied to the deep-mixing treatment device 5.
In the penetration process of the agitation and mixing shaft 15 in the improvement process of the ground ground or the underwater ground 2 by the deep mixing treatment device 5, is the process only for the agitation by the rotation of the agitation and mixing shaft 15 performed up to the planned depth (T + S) of the ground improvement 12? Or, as an intrusion discharge stirring and mixing process in which a “normally mixed solidifying material slurry” using a solidifying material such as cement is discharged from the tip of the stirring and mixing shaft 15, from the bottom surface 2 or the ground surface to a certain depth T Or to the planned depth (T + S) of the ground improvement 12.
In the subsequent lifting step, the above-mentioned “stirring material slurry for containment into the ground” is discharged from the vicinity of the upper portion of the stirring and mixing shaft 15, and the stirring and mixing processing for lifting and discharging is performed upward from the lowermost portion 16 of the ground improvement 12 to the bottom of the water. It is performed in a range S from the surface 2 or the ground surface to a certain depth T.
At the stage where the stirring and mixing shaft 15 is pulled up to a certain depth T from the water bottom surface 2 or the ground surface, the discharge of the “solidifying material slurry for containment into the ground” is stopped, and only stirring by rotation of the stirring and mixing shaft 15 is performed. The stirring / mixing process of discharging the above-mentioned “ordinary solidifying material slurry” from the vicinity of the upper part of the stirring / mixing shaft 15 is performed up to the water bottom surface 2 or the ground surface.

Purifies pollutants such as dioxins, PCBs and pesticides in mud slurry consisting of clay, silt, water, etc. containing pollutants collected from soil containing pollutants on land, or soil containing land pollutants. As a purifying agent, metallic iron powder, a metal-based reducing agent composed of carbon or other noble metals, or a material containing a metal such as iron and a metal oxide such as iron oxide or titanium oxide, or sodium sulfite, sodium bisulfite, etc. A material containing a reducing agent and a metal oxide such as iron oxide or titanium oxide is used.
The constant depth T below the bottom surface 2 or the ground surface, which discharges the “normally mixed solid material slurry” using a solidified material such as cement, is a distance H of 2 between the upper and lower discharge ports of the stirring and mixing shaft 15. The depth range is equivalent to double or triple.

Next, the present invention will be described based on the illustrated embodiment.
First, FIG. 1 is a conceptual development view showing an overall image of mechanical equipment and devices that implement a method for treating a contaminated bottom mud 3 of a water bottom 2 by a deep mixing treatment method according to the present invention.
(A) on the right side in FIG. 1 shows a work situation in which bottom mud 3 containing pollutants deposited on water bottom 2 is collected by dredging using high-concentration thin-layer dredger 1. The high-concentration thin-layer dredger 1 shown in the figure shows that it is configured to be dredged by a duct suction method that does not cause as much diffusion and winding of contaminants as possible. However, the meaning is not limited to the collection method, the configuration, function, and work content of the soot processing. This is only an example of a preferred form of dredging / collecting work system.
The work method for collecting the contaminated soil on land is not particularly shown, but a method of excavating, removing, and collecting using a well-known power shovel is generally performed.

In the central part (B) of FIG. 1, the intermediate processing plant ship 4 (or work table ship) receives the bottom mud 3 containing the pollutant dredged and collected by the high-concentration thin-layer dredger 1, and receives particles of soil particles. According to the diameter, an embodiment is shown in which muddy water slurry composed of clay, silt, water and the like containing contaminants is separated and classified from coarse particles such as gravel and sand.
Of course, depending on the geographical conditions, without using the intermediate treatment plant ship 4 (or work table ship), the bottom mud 3 collected by the high concentration thin layer dredger 1 is immediately sent to the intermediate treatment plant facility prepared on land. In some cases, the same classification process is performed on land. Although illustration thereof is omitted, it should be considered that the embodiment described below may include classification / sorting processing on land.

The mud slurry made of clay, silt, water, etc. containing pollutants collected by the classification process in the intermediate treatment plant ship 4 is sent to the deep mixing treatment ship 5 shown at (C) on the left in FIG. A “solidifying material slurry for containment in the ground” is produced by mixing with a solidifying material such as cement and a purifying agent or additive which will be described later. By carrying out the deep mixing method using this “containment solidifying material slurry”, the “consolidating material slurry for confinement into the ground” containing contaminants is deeply kneaded into the bottom soil 2 and insolubilized and contained.
FIG. 1 (C) shows the deep mixing processing vessel 5 for convenience, but this only shows a case where the deep mixing processing operation is predicated on the water surface.
In the following description, it should be understood as a term including the deep mixing treatment device 5 for performing so-called ground improvement of land.

FIG. 2 shows a work flow of the entire deep mixing treatment method outlined above.
In this work flow, the bottom mud 3 containing the pollutant collected from the bottom of the water is slurried in the intermediate treatment plant ship 4 and made of clay, silt, water, etc. containing the pollutant in accordance with the particle size of the soil particles. As an example, the “classification process” of separating and classifying the particles from coarse particles such as gravel and sand is performed by the conceptual diagram and process flow shown in FIG. 3A.
That is, the collected bottom mud 3 is first accommodated in a mud storage tank 6, which is sent to a vibrating sieve 7 through a line that means a pump and a pipe, and coarse particles 8 such as gravel and sand are separated into other pollutants. Remove from the mud moisture 9 consisting of clay, silt, water, etc. (separate and classify). By the way, dixins are less soluble in water and are attached to the surface of the soil particles in the bottom mud 3 than in the pore water, and have a higher surface area per unit weight than gravel and sand. It is already known that it adheres to the concentration. Therefore, if the bottom mud 3 at the bottom of the water is collected and classified, most of the pollutants can be secured and recovered.
The mud moisture 9 composed of clay, silt, water and the like containing the classified contaminants as described above is further sent to the cyclone 10 for further fine separation and classification. The mud slurry made of clay, silt, water and the like containing the pollutant thus obtained is stored in the slurry tank 11 and sent to the deep mixing treatment vessel 5.
On the other hand, the coarse particles 8 such as gravel and sand classified by the vibration sieve 7 are washed out with a washing water 12 using seawater or river water to a state where the influence on the environment is lightly taken out, and the water quality is monitored. After performing the above, it is reused as a resource or returned to the bottom 2 as it is.

However, in the case of contaminated soil collected on land, it is first sent to the mud storage tank 6 of the processing flow shown in FIG. 3B. Most of the processing flow of FIG. 3B is substantially the same as the content of the contaminant processing flow of the bottom mud 3 on the bottom of the water shown in FIG. 3A.
However, the point that the treatment of the contaminated soil on land is greatly different from the case of treating the bottom mud 3 of the water bottom 2 is that deaerated water subjected to the deaeration treatment is used. The reason for this is that when the contaminated soil collected on land is treated in the form of muddy water, the intervention of oxygen interferes, and the reduction treatment with a metal-based reducing agent such as metal iron powder is insufficient in the purification action with a later purification agent. This is in order to eliminate the concern of ending.
3A and 3B, in FIG. 3B, the decontaminated water deaerated by the deaeration device 30 is added to the contaminated soil collected on land in the mud tank 6 when it is accommodated. And make it muddy. The muddy water is sent to the vibration sieve 7 in the building 31 which is sealed in an airtight state in advance by a conveyor or the like. In the vibration fluid 7, the deaerated water deaerated by the deaerator 30 is sprayed to remove coarse particles 8 such as gravel and sand, and mud moisture 9 such as clay, silt and water containing other pollutants. (Separate, classify). By treating the mud water 9 made of clay, silt, water, etc. containing this pollutant as a mud slurry, it is possible to secure and recover most of the pollutants in the contaminated soil on land.

The mud moisture 9 made of clay, silt, water or the like containing the contaminants is further sent to the cyclone 10 for further fine separation and classification. The muddy water slurry made of clay, silt, water and the like containing the pollutants thus obtained is stored in the slurry tank 11 and sent to the deep mixing treatment vessel 5.
On the other hand, the coarse particles 8 such as gravel and sand removed by the vibration sieve 7 are thoroughly washed out with a washing water 12 using seawater or river water so that the influence on the environment is minimal, and the water quality is monitored. After being performed, it can be reused as a resource, or it can be returned to the surface or underground.

Incidentally, as a method of degassing water with the degassing apparatus 30, the following types are usually implemented.
(A) A processing method in which dissolved gas in water is degassed in a tank whose pressure is reduced to a vacuum by a vacuum pump or the like.
(B) Degassing treatment using a combination of low-temperature boiling in a vacuum vessel and cavitation by ultrasonic waves.
(C) Vacuum deaeration in which water to which ultrasonic energy is applied is deaerated by a vacuum deaerator and deaerated by pressurizing the degassed water and adiabatic expansion in reduced-pressure air Processing method.
(D) A system in which nitrogen gas is blown while water is appropriately stirred.
(E) A method in which bubbles in water are taken into and removed from coarse bubbles by coarse bubble aeration.
(F) Membrane vacuum deaeration method using a material that does not allow water to pass through only air (for example, a polymer gas separation membrane) (only the gas such as oxygen dissolved in water is removed from the membrane due to the pressure difference inside and outside the membrane) Method to eliminate outward).

  Next, the deep mixing processing vessel 5 shown in (C) on the left side in FIG. 1 means a so-called deep mixing processing device having a configuration equipped with a set of machines and equipment necessary for the deep mixing processing on the ship. As described above, there is no reason to limit the structure to a ship. For example, a well-known machine and apparatus can be applied in the embodiment of the DCM method by the applicants. As described above, this deep mixing treatment vessel 5 is used to remove mud slurry composed of clay, silt, water, etc. containing the classified and recovered contaminants, cement or other solidified material having a slight impact on the environment, and purification to be described later. It is mixed with an additive and an additive to produce a “solidified slurry for containment in the ground”, which is kneaded into a submerged ground or a land ground by a deep mixing treatment method by a deep mixing treatment method, and a ground improvement body 12 is obtained. Create a process that can be insolubilized in a long-term safe state and contained.

By the way, it should be understood that there are two types of solidifying material slurries used in the practice of the present invention, and these are used properly.
One of them is the so-called “ordinary blended solidifying material slurry” using a solidifying material such as cement. For example, as illustrated in FIG. 4A, this “ordinary solidifying material slurry” is prepared by mixing, for example, water (or seawater or the like, the same shall apply hereinafter), a solidifying material such as cement, and an additive with a predetermined amount. Proper amount is added so as to achieve a ratio, and kneaded to produce.
As another example, as illustrated in FIG. 4B, a mud slurry composed of clay, silt, water, etc. containing the pollutant collected as described above is used alone, or water is added to the mud slurry and cement. A solidifying material and additives such as the above, and a purifying agent having a property of purifying or decomposing the above-mentioned contaminants are added to the mixer 14 in appropriate amounts so as to obtain a predetermined blending ratio, and sufficiently kneaded. "Solidifying material slurry for containment in the ground".

Incidentally, as the cement used for the production of the solidifying material slurry, there are ordinary Portland cement, blast furnace cement, cement-based solidifying material, low alkaline cement and the like.
As the low alkaline cement, magnesia phosphate cement (pH of slurry added with water is 10.7), neutral solidified material mainly composed of plant kenaf (pH of slurry added with water is 7.0) Etc. are known.

The above-mentioned additive is used to adjust the properties of the solidifying material slurry to be produced, and refers to a thickener, an admixture, a retarder, and the like.
The thickener is used to facilitate penetration of the stirring and mixing shaft 15 of the deep mixing treatment device 5, to prevent sedimentation of particles in the pipe containing the purifier, or to thicken the metal reducing agent. It is a material for increasing the amount of the material and dispersing it uniformly. Specifically, diatomaceous earth, bentonite, commercially available refined clay, natural sediment clay, etc. are used.
The admixture is used for the purpose of changing the properties of the solidifying material slurry in order to facilitate the pumping of the solidifying material slurry. For example, it is used for the purpose of imparting fluidity to the solidifying material slurry or suppressing the increase in viscosity of the solidifying material slurry in summer.
The retarder is a drug used for the purpose of delaying the strength development of a solidifying material such as cement.

Next, the contaminant cleaning agent used in the production of the above-mentioned other one type of “solidified slurry for containment in the ground” is a contaminant contained in the recovered mud slurry, such as mainly dioxins, PCBs, It has a property of promoting or decomposing agricultural chemicals and the like over a long period of time, and for example, any of the following can be used.
(I) A metallic reducing agent comprising metallic iron powder, carbon or other noble metals.
(Ii) A material containing a metal such as iron and a metal oxide such as iron oxide or titanium oxide.
(Iii) A material containing a reducing agent such as sodium sulfite and sodium hydrogen sulfite and a metal oxide such as iron oxide and titanium oxide.

  Next, as a feature of the present invention, the improvement processing method of the bottom bottom ground 2 (or on the ground ground, the same shall apply hereinafter) by the above-mentioned deep mixing processing vessel 5 (or the onshore deep mixing processing apparatus) is largely composed of the stirring and mixing shaft 15. It is divided roughly into the process at the time of the penetration process which penetrates toward the underwater ground 2, and the process performed at the time of the raising process after the stirring and mixing shaft 15 reaches the planned depth of ground improvement (see reference numeral 16 in FIG. 1). Is done. FIG. 5 summarizes the types of such processing flows.

(Type of penetration process)
As for the penetration process of the stirring and mixing shaft 15, for example, only the stirring process (non-discharge) by the rotation of the stirring and mixing shaft 15 shown in FIG. The above-mentioned “normally-mixed solidifying material slurry” produced using a solidifying material is discharged downward from the tip discharge port (not shown in particular) of the stirring and mixing shaft 15 as indicated by an arrow 17 while following it downward. It is roughly divided into an in-penetration discharge method in which the stirring and mixing shaft 15 performs the stirring and mixing process. Furthermore, with regard to the agitation and mixing treatment by the latter discharge method at the time of penetration, as shown in FIG. 1 or FIG. 7E, when the penetration and discharge are performed at once to the planned depth of ground improvement (T + S), the water bottom surface or the ground surface 2 Intrusion discharge is performed until a certain downward depth T, and after that, the discharge of the above-mentioned “normally mixed solidifying material slurry” is stopped, and only stirring processing by simply rotating the stirring and mixing shaft 15 is performed (non-discharge). Divided.

The outline of the configuration of the stirring and mixing shaft 15 shown in FIG. 6 will be outlined. Reference numeral 20 is a tip excavating blade, 21 is a stirring blade, 22 is a connecting member that maintains a distance between two shafts, 23 is a drive shaft, and 24 is a slurry pipe. It is.
In short, in the penetration step, it is essential that the stirring and mixing shaft 15 penetrates vertically to the bottom 16 of the ground improvement. At the time of this penetration process, when the above-mentioned “normally mixed solidifying material slurry” is discharged and the water bottom ground 2 is stirred and mixed, the subsequent pulling process is easily performed. It is necessary to delay the solidification rate of the solidified material by blending the additive (retarding agent).

(Type of lifting process)
In the subsequent pulling process, as described above, it was produced by mixing mud slurry consisting of clay, silt, water, etc. containing pollutants, solidifying materials such as cement, and purifying agents and additives. For example, as shown in FIG. 6, the “solidifying material slurry” is discharged in the downward or horizontal lateral direction as indicated by an arrow 19 from a discharge nozzle 18 prepared in the vicinity of the upper portion of the stirring and mixing shaft 15 to follow it. The stirring / mixing process is performed by rotating the stirring / mixing shaft 15 pulled upward.

However, the stirring and mixing process using the above-mentioned “solidifying slurry for containment in the ground” is stopped at the stage where the water bottom surface 2 is pulled up to a certain depth T, and the depth range S shown in FIG. 1 or FIG. Limited.
That is, at the upper limit of the depth range S, the discharge of the “solidifying slurry for containment into the ground” is stopped, and the above “normally mixed solidifying material slurry” is also stirred above the position (range T). The discharge nozzle 18 located in the vicinity of the upper portion of the mixing shaft 15 is commonly used to discharge as indicated by an arrow 19, and the stirring and mixing shaft 15 that is pulled up to follow the nozzle 19 rotates to the surface of the water bottom 2. (A constant depth range T from the bottom surface 2 shown in FIG. 1) A method of performing a stirring and mixing process and a stirring process by simply rotating the stirring and mixing shaft 15 without discharging the “normally mixed solidifying material slurry”. It is divided into cases.

In short, in the upper part of the stirring and mixing treatment range S from which the above-mentioned “solidifying slurry for containment into the ground” is discharged, a range T in which “normally mixed solidifying material slurry” is discharged and stirred and mixed is so-called “ The construction of a “closed lid” is made to ensure that contaminants are prevented from eluting and diffusing again. As long as the above-mentioned “closed lid” can be formed, it is possible to combine a case where only the stirring process by the rotation of the stirring and mixing shaft 15 is performed in either the penetration process or the pulling process.
FIG. 7 conceptually shows the work flow of the penetration process and the lifting process performed as described above.

Here, the depth range S of the stirring and mixing process using the “solidifying material slurry for containment in the ground” in the above-described pulling process, and the depth range of the stirring and mixing process using the “solidifying material slurry of normal blending” Specific examples of significance and depth for distinguishing T will be described.
The basic idea is that “solidified slurry for containment in the ground” produced using a slurry of clay, silt, water, etc., containing contaminants is safe and stable in the long term. For the purpose of insolubilization and containment treatment, it is kneaded as a deep layer mixing treatment at a deep position (range S) of the water bottom ground 2. On the other hand, the stirring and mixing process using the “normally-consolidated solidifying material slurry” has a hard “closing lid” on the pollutant kneaded in the deep position (range S) of the underwater ground 2 as described above. For the purpose of preventing elution again, diffusion, and winding up, the stirring and mixing process is performed within a certain depth T from the surface of the bottom 2.

  More specifically, the lowermost part 16 of the ground improvement by the deep mixing method is usually about 45 m underground. On the other hand, the stirring and mixing process using the “normally mixed solidifying material slurry” has the purpose of forming a hard “closed lid” on the kneaded contaminants, and secondaryly to the deep range S of the underwater ground 2. The stirring and mixing shaft 15 that is contaminated with the “solidifying slurry for containment into the ground” containing the contaminated contaminant is cut off from the “solidifying slurry for containment into the ground” and the contaminant is removed. In order to obtain a cleaning effect, when the distance between the upper and lower discharge ports in the stirring and mixing shaft 15 is H (usually, H is 2 m to 3 m), the constant depth T from the bottom surface 2 is It is preferable to secure a depth of 2 to 3 times, specifically a depth of 4 m to 6 m to 6 m to 9 m.

  Although the present invention has been described based on the illustrated embodiment, it is not meant to be limited to the illustrated embodiment. It is noted that the scope of the present invention extends to a range of design changes, applications, and uses that are made by those skilled in the art as needed without changing the gist of the present invention.

It is explanatory drawing which shows arrangement | positioning and a general image of the implementation equipment and machine which implements this invention. It is a processing flow of the present invention. A is a flow chart for classifying a bottom mud of a water bottom, and B is a classification treatment of a slurry of a mud containing a pollutant in land soil. A and B are explanatory drawings of the point which manufactures two sorts of solidification material slurries. It is key point explanatory drawing of a deep-layer mixing processing method. It is explanatory drawing of the stirring mixing shaft used by this invention. A to E are explanatory views of the main points of the deep mixing process.

Explanation of symbols

2 Water bottom 3 Bottom mud 5 Deep layer processing equipment 15 Stirring mixing shaft 18 Slurry nozzle
16 Bottom of ground improvement S Depth range to contain pollutants T Depth from bottom surface H Distance between upper and lower outlets of stirring and mixing shaft

Claims (9)

Collects bottom mud containing pollutants on the bottom of the water, and makes mud slurry containing clay, silt, water, etc. containing pollutants, excluding coarse particles such as gravel and sand according to the particle size of the soil, cement, etc. In the construction method of mixing the solidifying material and the purifying agent and additives, and producing a solidifying material slurry for containment in the ground, and embedding it into the ground using a deep mixing treatment device,
The solidifying slurry for containment in the ground is kneaded by stirring and mixing in a range below a certain depth below the surface of the bottom of the water or the surface of the ground and up to the planned depth of ground improvement, Contaminated soil treatment method by mixed treatment. The bottom mud containing pollutants on the bottom of the water is collected by dredging, and a slurry of clay, silt, water, etc. containing pollutants, excluding coarse particles such as gravel and sand, according to the particle size of the soil particles, Producing a solidifying material slurry for containment into the ground by mixing with a solidifying material such as cement and a purifying agent and additives, and supplying this to a deep mixing treatment device;
The penetration process of the stirring and mixing shaft in the deep mixing processing equipment is performed to the planned depth for ground improvement,
In the subsequent pulling step, a stirring and mixing process in which the solidifying slurry for containment into the ground is discharged from the vicinity of the upper part of the stirring and mixing shaft is moved upward from the bottom of the ground improvement to the bottom of the water bottom surface or the ground surface. To the depth,
In the stage where the stirring and mixing shaft is pulled up to a certain depth below the surface of the water or the ground surface, the discharge of the solidifying slurry for containment into the ground is stopped, and then the stirring and mixing shaft is pulled up to the surface of the water bottom or the ground surface. A characteristic method for treating contaminated soil by deep mixing treatment. Muddy water slurry consisting of clay, silt, water, etc. containing contaminants collected from soil containing onshore contaminants and treated with deaerated water to remove coarse particles such as gravel and sand according to the particle size of the soil particles In a construction method of mixing a solidifying material such as cement, a purifying agent and an additive to produce a solidifying slurry for containment in the ground, and embedding it in the ground using a deep mixing treatment device,
The solidifying slurry for containment in the ground is kneaded by stirring and mixing in a range from a certain depth below the surface of the bottom of the water or the ground to a predetermined depth for ground improvement, Contaminated soil treatment method by mixed treatment. Muddy water slurry consisting of clay, silt, water, etc. containing contaminants collected from soil containing onshore contaminants and treated with deaerated water to remove coarse particles such as gravel and sand according to the particle size of the soil particles Is mixed with a solidifying material such as cement, a purifying agent and an additive to produce a solidified slurry for containment in the ground, and this is supplied to a deep-mixing treatment device,
The penetration process of the stirring and mixing shaft in the deep mixing processing equipment is performed to the planned depth for ground improvement,
In the subsequent pulling step, a stirring and mixing process in which the solidifying slurry for containment into the ground is discharged from the vicinity of the upper part of the stirring and mixing shaft is moved upward from the bottom of the ground improvement to the bottom of the water bottom surface or the ground surface. To the depth,
In the stage where the stirring and mixing shaft is pulled up to a certain depth below the surface of the water or the ground surface, the discharge of the solidifying slurry for containment into the ground is stopped, and then the stirring and mixing shaft is pulled up to the surface of the water bottom or the ground surface. A characteristic method for treating contaminated soil by deep mixing treatment. The penetration process of the stirring and mixing shaft performs only the stirring by the stirring and mixing shaft from the surface of the water bottom or the ground surface to the planned depth of ground improvement,
In the subsequent pulling step, first, a stirring and mixing process in which the solidifying slurry for containment into the ground is discharged from the vicinity of the upper part of the stirring and mixing shaft is moved upward from the bottom of the ground improvement to a certain depth below the bottom surface or the ground surface. Do it,
At the stage where the stirring and mixing shaft is pulled up to a certain depth below the surface of the water bottom or the ground surface, the discharge of the solidifying slurry for containment into the ground is stopped, and then the normal mixing using a solidifying material such as cement is performed. The mixed soil slurry is discharged from the vicinity of the upper portion of the stirring and mixing shaft, and the stirring and mixing treatment is performed up to the water bottom surface or the ground surface. Processing method. The penetration process of the stirring and mixing shaft performs a stirring and mixing process in which a normally blended solidifying material slurry using a solidifying material such as cement is discharged from the tip of the stirring and mixing shaft to a certain depth below the surface of the water bottom or the ground surface, Stop the discharge of the solidified material slurry of the normal composition at the depth, deeper than that, perform only the stirring with the stirring and mixing shaft to the planned depth of ground improvement,
In the subsequent pulling step, first, a stirring and mixing process in which the solidifying slurry for containment into the ground is discharged from the vicinity of the upper part of the stirring and mixing shaft is moved upward from the bottom of the ground improvement to a certain depth below the bottom surface or the ground surface. Do it,
At the stage where the stirring and mixing treatment is pulled up to a certain depth below the bottom surface or the ground surface, the discharge of the solidifying slurry for containment into the ground is stopped. The method for treating contaminated soil by the deep mixing treatment according to any one of claims 1 to 4, wherein the treatment is performed up to the ground surface. The penetration process of the stirring and mixing shaft is carried out from the bottom or ground surface to the planned depth for ground improvement by discharging the normally mixed solidifying material slurry using a solidifying material such as cement from the tip of the stirring and mixing shaft. ,
In the subsequent pulling step, first, a stirring and mixing process in which the solidifying slurry for containment into the ground is discharged from the vicinity of the upper part of the stirring and mixing shaft is moved upward from the bottom of the ground improvement to a certain depth below the bottom surface or the ground surface. Do it,
At the stage where the stirring and mixing shaft is pulled up to a certain depth below the surface of the water bottom or the ground surface, the discharge of the solidifying slurry for containment into the ground is stopped, and then the normal mixing using a solidifying material such as cement is performed. The treatment of contaminated soil by the deep mixing treatment according to any one of claims 1 to 4, wherein the stirring and mixing treatment for discharging the solidified material slurry from the vicinity of the upper portion of the stirring and mixing shaft is performed up to the water bottom surface or the ground surface. Construction method.   A purifying agent that purifies contaminants such as dioxins, PCBs, and agricultural chemicals in mud slurry containing clay, silt, water, etc. containing pollutants collected from the bottom mud containing pollutants on the bottom of the water or pollutants on land. As a metal-based reducing agent composed of metallic iron powder, carbon or other noble metals, or a material containing a metal such as iron and a metal oxide such as iron oxide or titanium oxide, or a reducing agent such as sodium sulfite or sodium bisulfite. A material containing a metal oxide such as iron oxide and titanium oxide is used. The method for treating contaminated soil by deep mixing treatment according to any one of claims 1 to 4. The fixed depth below the surface of the water bottom or ground where the solidified slurry containing a solidified material such as cement should be discharged is equivalent to 2 to 3 times the distance between the upper and lower discharge ports on the stirring and mixing shaft. The method for treating contaminated soil by the deep mixing treatment according to any one of claims 5 to 7, characterized in that the depth of the soil.

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