JP7215387B2 - Contaminated soil treatment method - Google Patents

Description

The present invention relates to a contaminated soil treatment method for treating contaminated soil.

In Japan, soil and rocks containing naturally occurring heavy metals, etc. are widely distributed. is the problem.
Such excavation muck may contain harmful metals and their compounds, which are natural or artificial contaminants. cannot be brought in.
In addition, since there is a possibility that hazardous metals, etc., may be contained in the soil of factory premises and their former sites, etc. due to leakage of specific hazardous substances used in the factory facilities, etc., depending on the contamination status, hazardous substances will be removed from the contaminated soil. to meet the second dissolution criterion.

On the other hand, with regard to contaminated soil, the Soil Contamination Countermeasures Law (Ministry of the Environment) designates land where the state of soil contamination does not meet the designated standards as an "area requiring action" or "area requiring notification upon transformation". The criteria for designation include soil elution amount standards related to the risk of ingestion of groundwater, etc., and soil content standards related to the risk of direct intake. An area requiring action is an area where there is an intake route of soil contamination, and there is a risk of health hazards, so measures such as removal of contamination are required. In principle, alteration of the character of land is prohibited in areas requiring action. Areas where notification is required at the time of transformation are areas where there is no intake route of soil contamination and there is no risk of health hazards, so measures such as removal of contamination are unnecessary (including areas where intake routes have been blocked). be. In areas requiring notification when changing the character of land, prior notification is required when changing the character of the land.

For areas requiring action, soil that does not conform to the standards for soil contamination exceeding the countermeasure standards (equivalent to 3 to 30 times By taking measures such as position insolubilization and insolubilization backfilling, it may be possible to make it an area that requires notification when changing its appearance. In-situ insolubilization is a measure of insolubilizing harmful substances in the soil by injecting and stirring them into the range of existence of soil that does not conform to the standards, so as to meet the soil elution amount standards. Insolubilization backfill involves excavating soil that does not meet the standards, mixing chemicals at plants outside or on the site, and insolubilizing harmful substances in the soil so that they do not dissolve in water. After confirmation, it is a measure to backfill the excavation range.

Japanese Patent No. 4109017 (Patent Document 1) discloses a widely used material for insolubilizing heavy metals, etc., applied to treat contaminated soil, which is magnesium oxide alone or a material containing the same as a main component. Also, as a material having an insolubilizing effect on hexavalent selenium eluted from rocks such as soil and mud, Japanese Patent Application Laid-Open No. 2013-116952 (Patent Document 2) describes α-iron/iron oxide composite powder and Mixtures with iron oxide powders are disclosed.

Since the material disclosed in Patent Document 2 is mainly composed of iron, the effect of insolubilizing halogens such as fluorine is low, and not only selenium eluted from rocks such as soil and mud, but also heavy metals such as fluorine are insolubilized. Insolubilizing materials such as heavy metals are expected to effectively insolubilize selenium, fluorine, etc. eluted from soil, mud, etc., which are not effective as materials.

In recent years, as a method for treating contaminated soil, from the viewpoint of low cost and low energy consumption, a method has been proposed in which heavy metals, etc. are dissolved in an aqueous solution as chelate compounds by wet cleaning using a chelating agent, and removed from the contaminated soil. For example, Japanese Patent Application Laid-Open No. 2018-8222 (Patent Document 3) describes a washing step of wet washing by adding a chelating agent to contaminated soil, a separation step of solid-liquid separation of the contaminated soil after wet washing, A solid-phase treatment process in which cement, a cement-based solidifying agent, or a lime-based solidifying agent is added to the solid-liquid separated solid phase for modification, and a solid-liquid-separated liquid phase contains the solidifying agent and iron (III). a liquid phase treatment step of adding an additive and precipitating the harmful substance to remove it from the liquid phase.
However, the method of treating contaminated soil using a chelating agent has problems with long-term stability because the chelating agent is an organic substance, and if it decomposes over time, heavy metals will be re-eluted. In the method of treating contaminated soil using slaked lime, since cement and slaked lime are alkaline, the treated soil becomes alkaline, making reuse difficult.

As an insolubilizing material for effectively insolubilizing harmful substances from contaminated soil, the applicant has applied for Japanese Patent Application No. 2018-066533 (Patent Document 4), Japanese Patent Application No. 2019-067054 (Patent Document 5), and Japanese Patent Application No. 2019-067075. No. (Patent Document 6) and Japanese Patent Application No. 2019-163561 (Patent Document 7) propose a novel heavy metal insolubilizing material capable of effectively insolubilizing harmful substances such as heavy metals.

Patent No. 4109017 JP 2013-116952 A JP 2018-8222 A Japanese Patent Application No. 2018-066533 Japanese Patent Application No. 2019-067054 Japanese Patent Application No. 2019-067075 Japanese Patent Application No. 2019-163561

However, although a method for insolubilizing harmful substances in contaminated soil has been proposed so far, a mechanism for reusing the insolubilized soil as an effective resource has not yet been proposed.
Therefore, the problem to be solved by the present invention is to provide a contaminated soil treatment method that enables effective reuse of contaminated soil.
In particular, it is an object of the present invention to provide a method for treating contaminated soil that can appropriately utilize the treated contaminated soil or the like as a raw material for cement after subjecting the contaminated soil to insolubilization treatment.

In order to solve the above problems, the contaminated soil treatment method of the present invention has the following technical features.
(1) In a contaminated soil treatment method for treating contaminated soil, a registration step of measuring the content of soil components and the amount of elution of harmful substances in contaminated soil and registering at least the content of soil components in a database; An insolubilization treatment step of performing insolubilization treatment on contaminated soil in which the elution amount of substances exceeds the second standard, which is greater than the first standard, so that the elution amount of harmful substances is equal to or less than the second standard, and the contaminated soil after insolubilization treatment. If the amount of eluted hazardous substances exceeds the first standard, it is transported and stored at a specified location, including the premises of a cement plant, and if it is less than the first standard, it is stored at the original location or transported to the specified location. and a management step of registering and managing the storage location of the contaminated soil in the database, selecting the contaminated soil using the database and using it as a raw material in cement production. Soil treatment method.

(2) In the contaminated soil treatment method according to (1) above, in the insolubilization step, the insolubilization treatment is also applied to the contaminated soil in which the elution amount of harmful substances is equal to or less than the second standard and exceeds the first standard. and in the management step, the contaminated soil is stored at the original location or transported to the specified location for storage, and the storage location of the contaminated soil is registered in the database for management. The method.

(3) In the contaminated soil treatment method described in (1) or (2) above, in the management step, based on the in-situ location of the contaminated soil, the content of soil components, the amount of elution of harmful substances, or the amount of contaminated soil A contaminated soil treatment method, characterized in that the contaminated soil is classified and stored, and information relating to the classification of the contaminated soil is registered in the database and managed.

(4) The method for treating contaminated soil according to any one of (1) to (3) above, wherein an inorganic insolubilizing material is used for the insolubilizing treatment.

(5) In the contaminated soil treatment method according to any one of (1) to (4) above, for contaminated soil in which the amount of elution of harmful substances after insolubilization exceeds the first standard, in the management process, 1 This contaminated soil treatment method is characterized in that the amount of contaminated soil stored in a location is set to be equal to or less than a predetermined amount.

(6) In the contaminated soil treatment method according to any one of (1) to (5) above, when selecting contaminated soil using the database, the total amount of contaminated soil used is set, and the total amount of used Set the amount of contaminated soil in which the amount of elution of hazardous substances exceeds the first standard, and for the shortfall obtained by subtracting the amount of use from the total amount of use, the amount of elution of hazardous substances is the first standard A contaminated soil treatment method characterized by supplementing with soil below the standard.

According to the contaminated soil treatment method according to the present invention, the contaminated soil is effectively insolubilized, the insolubilized contaminated soil is stored at the original position or at a specific position, and the raw material for producing the desired cement is For example, the soil components, their content, and the storage location, section, and inventory of insolubilized contaminated soil are registered and managed in the database so that they can be selected as substitute materials for clay raw materials, so cement with desired characteristics When manufacturing , it is possible to efficiently use insolubilized contaminated soil as a raw material for cement. Therefore, not only can harmful substances in contaminated soil be insolubilized, but the insolubilized contaminated soil can be effectively reused.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the structural example of the system which implement|achieves the contaminated soil processing method of this invention. 2 is a diagram showing an example of a flow chart of a contaminated soil treatment method by the system of FIG. 1; FIG. 2 is a diagram showing an example of a soil management table used in the system of FIG. 1; FIG.

An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a diagram showing a configuration example of a system that implements the contaminated soil treatment method of the present invention. Schematically, the system of this example insolubilizes the contaminated soil according to the amount of elution of harmful substances, stores the insolubilized contaminated soil at the original site 10 or the site of the cement factory 20, etc., and cement manufacturing The contents of the soil components are registered and managed in the database 32 of the server 30 of the control center so that the soil components can be selected as raw materials for the soil. In the following, a case where the "soil elution amount standard" is used as the "first standard" according to the present invention and the "second elution amount standard" is used as the "second standard" according to the present invention will be described as an example. However, the invention is not limited to this.

In the system of this example, contaminated soil is treated according to the following procedure.
(Step 1: registration process)
A worker goes to the original position 10 and measures the content of soil components and the amount of elution of harmful substances in the contaminated soil. Examples of soil components include calcium, aluminum, silicon, iron, magnesium, potassium, sodium, sulfur, and chlorine.
Harmful substances include heavy metals, halogens, and second-class specified hazardous substances defined in the Soil Contamination Countermeasures Law. Heavy metals include one or more of manganese, chromium, copper, cadmium, mercury, selenium, lead, arsenic, etc., and heavy metal simple substances and their compounds can be exemplified. Halogens include fluorine, chlorine, etc. can be exemplified by simple substance and compounds thereof, and further, simple substance of boron and its compounds contained in Class 2 Specified Hazardous Substances stipulated in the Soil Contamination Countermeasures Law can be exemplified. The measurement data of these components are registered in the database 32 of the server 30 of the management center. In the contaminated soil treatment method of the present invention, at least the contents of soil components are registered in the database, but the elution amount of harmful substances may also be registered in the database.

The soil management table exemplified in FIG. 3 includes soil ID, which is identification information of contaminated soil, original position of contaminated soil, content of soil components by component, elution amount of hazardous substances by component, storage of insolubilized contaminated soil, etc. It has data items such as location (location, section) and inventory amount. At the stage where the registration process is completed, the soil ID, the original position, the content of each soil component, and the elution amount of hazardous substances by component are registered, and the storage location and inventory amount are registered in the management process described later. Access to the database 32 of the server 30 may be realized by directly operating the server 30, or by connecting to the server 30 from a terminal device installed in each cement factory or a terminal device possessed by each worker. may be implemented.

(Procedure 2: Insolubilization treatment step)
If the eluted amount of harmful substances exceeds the second eluted amount standard, the polluted soil is subjected to insolubilization treatment so that the eluted amount of toxic substances is equal to or less than the second eluted amount standard. Whether or not the amount of eluted hazardous substances exceeds the second standard for the amount of eluted hazardous substances may be determined by the operator based on the measurement result of the eluted amount of hazardous substances, or based on the measurement data registered in the database 32. You may let the server 30 determine. In addition, even if the amount of elution of harmful substances is below the second standard for the amount of elution of harmful substances, the contaminated soil may be subjected to insolubilization treatment if the amount of elution of harmful substances exceeds the standard for the amount of elution of soil.

The insolubilization treatment is assumed to be performed by a worker injecting and stirring the insolubilizing material into the existing range of the contaminated soil at the original position 10, but the contaminated soil is excavated and the insolubilizing material is mixed at another location. I don't mind.
For the insolubilization treatment, any known insolubilizing material can be used as long as it can insolubilize harmful substances. Preferably, an inorganic insolubilizing material with excellent long-term stability is used. Examples of such an inorganic insolubilizing material include the dolomite insolubilizing material under the trade name Magical Fix (registered trademark of Sumitomo Osaka Cement Co., Ltd.), and the dolomite insolubilizing materials described in Patent Documents 4 to 7 above. Since the insolubilization treatment using such an insolubilizing material can effectively insolubilize harmful substances, it becomes possible to stably store contaminated soil for a long period of time.

(Step 3: Management process)
The contaminated soil after the insolubilization treatment is stored at the original position 10 or transported to a specific position different from the original position 10 for storage. Contaminated soil that does not require insolubilization treatment is also stored at the original location 10 or transported to a specific location for storage. The specific location may be any location where the operator of this system can appropriately manage contaminated soil, and includes, for example, the premises of the cement factory 20 . Alternatively, a location near the cement factory 20 or a location easily accessible from the cement factory 20 may be used. In the example of FIG. 1, the contaminated soil at the original positions A, B, and C (10-1 to 10-3) is transported to the cement factory X (20-1), and the original positions D, F (10-4, 10- The contaminated soil of 6) is transported to cement factory Y (20-2). On the other hand, the contaminated soil at the original position E (10-5) is stored on the spot.

Contaminated soil is transported to a specific location when the elution amount of hazardous substances after insolubilization exceeds the soil elution amount standard, or when the elution amount of hazardous substances after insolubilization treatment is below the soil elution amount standard. 10 is carried out when necessary. Whether or not the eluted amount of hazardous substances after the insolubilization treatment exceeds the soil eluted amount standard may be determined by the operator by re-measuring the eluted amount of hazardous substances, or the re-measured data may be registered in the database 32. may be determined by the server 30. Further, cases where it is necessary to carry out from the original position 10 include cases where a request is made by the administrator of the original position 10, and cases where a request is made by the local government having jurisdiction over the original position 10, and the like.

Storage of the contaminated soil at the original position 10 may be carried out in the form of backfilling the contaminated soil, or in the form of simply placing it temporarily. Also, the contaminated soil carried out from the original position 10 is temporarily stored at a specific position (for example, the site of the cement factory 20). When the contaminated soil is temporarily placed at a specific position, the contaminated soil is sorted and temporarily placed, for example, according to the original position of the contaminated soil so that the contaminated soil is not mixed with other contaminated soil. In addition, it is not limited to the mode of classifying the contaminated soil based on the original position of the contaminated soil, and the contaminated soil may be classified based on the content of soil components, the amount of elution of harmful substances, or the amount of contaminated soil. , the contaminated soil may be classified based on a combination of these. After placement of the contaminated soil, data indicating its storage status (in this example, storage location and stock amount) are added to the database 32 .

Here, it is preferable to keep the amount of contaminated soil stored in one location below a predetermined amount for contaminated soil in which the amount of eluted hazardous substances after the insolubilization treatment exceeds the soil elution amount standard. This is to prevent secondary pollution caused by concentration of highly concentrated contaminated soil. Such placement of contaminated soil can be determined by the server 30 based on data registered in the database 32, for example. Information on the contaminated soil (e.g., soil ID, origin of shipment, content of soil components, hazardous substance content, etc.) is provided in each section where the contaminated soil is located so that it is easy to understand what kind of contaminated soil is located. It is also possible to install a stake or a notice board with an identifier indicating the amount of elution, etc.). It is preferable that the stakes, notice boards, etc. are firmly fixed to the ground or the wall surface of the installed object, etc., in a position that is easy to see so that they will not move due to wind and rain.

FIG. 2 shows an example of a flow chart of the contaminated soil treatment method by the system of FIG.
When a request for treatment of contaminated soil is received, a worker first goes to the original position 10 and analyzes the state of contamination of the contaminated soil. In analyzing the state of contamination of contaminated soil, the content of soil components is measured (step S11) and the amount of elution of harmful substances is measured (step S12). The measured values obtained by these measurements are registered in the database 32 (step S13).

Next, the server 30 determines the necessity of insolubilizing the contaminated soil based on the measurement data registered in the database 32 . In this example, it is determined whether or not the elution amount of harmful substances exceeds the second elution amount standard (step S14), and it is determined whether or not the elution amount of hazardous substances exceeds the soil elution amount standard (step S15). I do.

Insolubilization treatment is applied to the contaminated soil determined in step S14 that the elution amount of harmful substances exceeds the second elution amount standard (step S19, S20). After that, it is determined whether or not the elution amount of harmful substances after the insolubilization treatment exceeds the soil elution amount standard (step S21). and stored (step S22). On the other hand, the soil in which the eluted amount of harmful substances after the insolubilization treatment is equal to or less than the soil eluted amount standard is stored at the original location 10 or transported to a specific location for storage (step S18).

Even if it is determined in step S14 that the amount of elution of hazardous substances is equal to or less than the second standard for the amount of elution of hazardous substances in the contaminated soil, if it is determined in step S15 that the amount of elution of hazardous substances exceeds the standard for the amount of elution of hazardous substances, the contaminated soil is considered to be harmful. The insolubilization treatment is performed until the elution amount of the substance becomes equal to or less than the soil elution amount standard (steps S16 and S17). The contaminated soil after the insolubilization treatment is stored at the original position 10 or transported to a specific position for storage (step S18). Contaminated soil determined in step S15 to have a hazardous substance elution amount below the soil elution amount standard can also be stored at the original location 10 or transported to a specific location for storage (step S18).
After placing the contaminated soil at the original position 10 or at the specific position (after starting storage), data indicating the storage status (storage location and stock amount) is registered in the database 32 (step S23).

The contaminated soil treated as described above can be kiln fired at the cement factory 20 and used as a raw material for manufacturing cement. When contaminated soil is used as a raw material for manufacturing cement, a worker operates a terminal device, designates the amount of contaminated soil to be used and the content of soil components, and inputs an inventory confirmation request. When entering an inventory confirmation request, it is also possible to specify other conditions such as the permissible elution amount of hazardous substances. The input inventory confirmation request is transmitted to the server 30 . The server 30 searches the database 32 for the presence or absence of contaminated soil that satisfies the received inventory confirmation request, and transmits the result to the requesting terminal device. The worker confirms the search results displayed on the terminal device, and if there is no particular problem, arranges for the contaminated soil to be used as a raw material for cement production. Contaminated soil on the site of a cement factory 20 that manufactures cement may be used as a raw material, or contaminated soil on the site of another cement factory 20 or contaminated soil at the original location 10 may be used as a raw material. There is also However, considering the cost and time required for transportation, it is preferable to preferentially select contaminated soil from a location near the cement factory 20 that manufactures cement. After the contaminated soil is used as a raw material for cement production (or after it is carried out from the storage location), the inventory amount of contaminated soil in the database 32 is updated.

In addition, the contaminated soil used as a raw material for manufacturing cement may be of one type or may be a mixture of a plurality of types. For example, if no single contaminated soil that satisfies the specified soil component content is found, multiple types of contaminated soil should be mixed and used so that the specified soil component content is met. can be done. Contaminated soil used as a raw material for manufacturing cement may be selected in consideration of the state of contamination. For example, when selecting contaminated soil based on the data registered in the database 32, the server 30 sets the total usage amount A of the contaminated soil, Contaminated soil whose elution amount exceeds the soil elution amount standard) is set, and the shortfall obtained by subtracting the usage amount B from the total usage amount A is low-concentration contaminated soil (the amount of toxic substances eluted into the soil is You may make up for it with the soil below a quantity standard). In this way, by limiting the amount of highly-concentrated contaminated soil used, it is possible to keep the amount of harmful substances in cement below a certain level. As the usage amount B, for example, an amount that is a predetermined ratio to the total usage amount A can be set.

As described above, the system of this example measures the content of soil components and the amount of elution of harmful substances in contaminated soil, and includes a registration step of registering at least the content of soil components in the database 32, and the amount of elution of harmful substances. is greater than the soil elution standard, the contaminated soil that exceeds the second elution standard is insolubilized so that the elution of hazardous substances is less than the second elution standard, and the contaminated soil after insolubilization If the amount of hazardous substances eluted exceeds the soil elution amount standard, it is transported and stored at a specific location including the premises of the cement factory 20, and if the soil elution amount is less than the soil elution standard, it is stored at the original location 10 or transported to a specific location. and a management step of registering and managing the storage position of the contaminated soil in the database 32. Using the database 32, the contaminated soil is selected and used as a raw material in cement production. Therefore, according to the system of this example, it is possible to efficiently reuse contaminated soil. In addition, the burden of storing the insolubilized contaminated soil is reduced for the in-situ manager of the contaminated soil.

Although the present invention has been described in detail above, it goes without saying that the present invention is not limited to the configuration described above, and may be realized by configurations other than those described above.
Further, the present invention provides, for example, a system for realizing the contaminated soil treatment method of the present invention, a program for realizing the contaminated soil treatment method of the present invention by a computer having hardware resources such as a processor and a memory, and so on. It is also possible to provide as a storage medium for storing such programs.

The contaminated soil treatment method of the present invention can be used to treat various types of contaminated soil to which the insolubilization treatment can be applied, and enables the reuse of the contaminated soil after the insolubilization treatment as a raw material for producing cement.

10 original location 20 cement factory 30 server 32 database

Claims (6)

In a contaminated soil treatment method for treating contaminated soil,
a registration step of measuring the content of soil components and the amount of elution of harmful substances in contaminated soil, and registering at least the content of soil components in a database;
an insolubilization treatment step of insolubilizing contaminated soil in which the amount of elution of harmful substances exceeds the second standard, which is greater than the first standard, so that the amount of elution of harmful substances is equal to or less than the second standard;
Contaminated soil after insolubilization treatment, if the amount of elution of hazardous substances exceeds the first standard, is transported and stored at a specific location including the premises of a cement factory, and if the amount is less than the first standard, it is stored at the original location or a management step of transporting and storing the contaminated soil to the specific location, and registering and managing the storage location of the contaminated soil in the database;
A contaminated soil treatment method, comprising selecting contaminated soil using the database and using the contaminated soil as a raw material in cement production. 2. The method for treating contaminated soil according to claim 1, wherein in the insolubilization step, insolubilization is performed even on contaminated soil in which the elution amount of harmful substances is equal to or less than the second standard and exceeds the first standard, and the management is performed. In the step, the contaminated soil is stored at the original location or transported to the specified location for storage, and the storage location of the contaminated soil is registered in the database for management. 3. In the contaminated soil treatment method according to claim 1 or 2, in the management step, based on the in-situ location of the contaminated soil, the content of soil components, the amount of elution of harmful substances, or the amount of contaminated soil, classified and stored, and information relating to the classification of the contaminated soil is registered in the database and managed. 4. The method for treating contaminated soil according to claim 1, wherein an inorganic insolubilizing material is used for said insolubilizing treatment. 5. The contaminated soil treatment method according to claim 1, wherein the contaminated soil in which the amount of elution of harmful substances after insolubilization exceeds the first standard is stored in one place in the management process. A polluted soil treatment method, characterized in that the amount of soil is set so as to be equal to or less than a predetermined amount. 6. In the contaminated soil treatment method according to claim 1, when selecting contaminated soil using the database, a total amount of contaminated soil used is set, and harmful substances occupying the total amount used The amount of polluted soil whose elution amount exceeds the first standard is set, and the shortage obtained by subtracting the amount used from the total amount used is supplemented with soil whose elution amount of hazardous substances is less than the first standard. A contaminated soil treatment method characterized by:

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