JP4897980B2 - Methods for detoxifying harmful substances, waste disposal sites and paved roads - Google Patents

Description

  The present invention relates to a waste itself and a method for detoxifying harmful substances such as incinerated ash and molten slag, a waste disposal site using the detoxification method, and a paved road.

It is necessary to reuse or landfill waste and its incinerated ash as civil engineering materials and the like under conditions that are safe and have a low environmental impact.
For example, in a final disposal site for waste, the waste and its disposal materials such as incineration ash and molten slag are stored for a long period of time. For this reason, it is necessary to prevent soil and groundwater from being contaminated by organic pollutants and heavy metals and the like that are eluted from the disposal materials.

Conventionally, there is a technology for recycling waste and its incinerated ash into molten slag, thereby suppressing the elution of harmful substances such as heavy metals contained therein and reusing them as civil engineering materials.
However, there is a problem that this ordinary molten slag forming technique is incomplete as an insolubilizing technique in consideration of conditions such as acid rain.

Moreover, in the conventional waste disposal site, the underground penetration | invasion of a hazardous | toxic substance is aimed at by laying a water-impervious sheet (refer patent document 1).
However, there is a risk that the water shielding sheet may be broken due to deterioration or the like, and it is considered that diffusion of harmful substances cannot be prevented appropriately.

Japanese Patent Application Laid-Open No. 05-112924

Problems to be solved regarding the detoxification method of hazardous substances, waste disposal sites and paved roads include the risk of toxic substances leaching from wastes and their incinerated ash and molten slag under acidic conditions, The conventional method cannot cope with the risk that the water shielding sheet at the disposal site is broken due to deterioration or the like, and it is not possible to appropriately prevent the diffusion of harmful substances.
Accordingly, an object of the present invention is to provide a method for detoxifying a hazardous substance, which can appropriately prevent the harmful substance eluted from the waste and its incinerated ash, molten slag, etc. from being diffused, and does not burden the environment and at a low cost. To provide a disposal site and paved road.

The present invention has the following configuration in order to achieve the above object.
According to one form of the detoxifying method for harmful substances according to the present invention, hazardous substances such as heavy metals and organic pollutants eluted from waste and its incinerated ash and molten slag come into contact with the permeable clay mineral. In order to be adsorbed by the water-permeable clay mineral, the water-permeable clay mineral is arranged close to and / or in contact with the harmful substance, and is adsorbed and fixed.

Moreover, according to one form of the detoxifying method for harmful substances according to the present invention, the water-permeable clay mineral is mixed with and / or kneaded with the waste or the incinerated ash thereof, thereby adding the water-permeable clay mineral to the water-permeable clay mineral. It can be characterized by adsorbing and fixing harmful substances.
Moreover, according to one form of the detoxifying method for harmful substances according to the present invention, the water-permeable clay mineral to which the harmful substances are adsorbed and fixed is melted.

  Further, according to one form of the detoxifying method for harmful substances according to the present invention, the permeable clay mineral adsorbing layer is provided on the inner bottom surface portion and the inner side surface portion that form a storage space for a landfill disposal site or a container, By adsorbing and fixing harmful substances, diffusion due to elution of the harmful substances can be prevented.

  Moreover, according to one form of the detoxifying method for harmful substances according to the present invention, the water-permeable clay mineral contains at least allophane and / or imogolite.

Moreover, according to one form of the waste disposal site concerning this invention, the adsorption layer of the said water-permeable clay mineral is provided so that the detoxification method of the said harmful substance may be used.
Moreover, according to one form of the waste disposal site concerning this invention, the said water-permeable clay mineral can be used for at least one part of covering soil.

  Further, according to one aspect of the paved road according to the present invention, the molten slag formed by melting waste and its incineration ash is paved by being paved by being laid as a part of the laminated material of the inner layer. A toxic substance such as heavy metal eluted from the molten slag or the like is in contact with the permeable clay mineral, and is adsorbed by the permeable clay mineral. In addition, an adsorption layer of the water-permeable clay mineral is provided.

  According to the method for detoxifying harmful substances, the waste disposal site and the paved road according to the present invention, it is appropriate that the hazardous substances eluted from the waste and its incinerated ash, molten slag, etc. are diffused properly and without burdening the environment. In addition, it has a particularly remarkable effect that it can be prevented at low cost.

It is explanatory drawing of the system which shows the example of the form of the disposal method of the waste concerning this invention. It is a side view which shows the example of the form of the disposal site of the waste concerning this invention. It is sectional drawing which shows the example of the form of the paved road which reuses the waste concerning this invention.

The present invention finds the property of water-permeable clay mineral and has the property of adsorbing and fixing harmful substances and utilizing the property.
In addition, even if it is a low water permeability clay mineral, since harmful substances, such as a heavy metal, can be adsorbed, a harmful substance can be made harmless. However, since the water-permeable clay mineral has more excellent adsorptivity, it can efficiently detoxify harmful substances.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, best modes of a detoxifying method, waste disposal site and paved road according to the present invention will be described in detail with reference to the accompanying drawings (FIGS. 1 to 3).
FIG. 1 is an explanatory diagram of a system showing an embodiment of a waste disposal method according to the present invention. FIG. 2 is a cross-sectional view showing an example of a waste disposal site according to the present invention. FIG. 3 is a cross-sectional view showing an example of a paved road for reusing waste according to the present invention.

To prevent harmful substances such as heavy metals and organic pollutants eluted from waste and its incinerated ash and molten slag from adhering to the permeable clay mineral, The water-permeable clay mineral is placed close to and / or in contact with it, and is adsorbed and fixed. Thereby, a hazardous | toxic substance can be fixed suitably and the spreading | diffusion can be prevented.
The elution of heavy metals is performed using water such as rain water as a medium. Further, the adsorption action of the eluted heavy metal by the water-permeable clay mineral is also performed using water such as rain water as a medium.

By mixing and / or kneading the permeable clay mineral with the incinerated ash after burning the waste or its waste in an incinerator (see Fig. 1), harmful substances (organic pollutants) are added to the permeable clay mineral. , Heavy metals, etc.) can be effectively adsorbed and fixed.
Because it uses the chemical adsorption of permeable clay minerals, it is highly detoxifying. An example of the waste that is rendered harmless is sewer sludge.
In addition, since the water-permeable clay mineral contains at least allophane and / or imogolite, harmful substances can be effectively adsorbed and fixed. Allophane and imogolite are naturally permeable clay minerals that can be used at low cost.

Moreover, after mixing and / or kneading | mixing a water-permeable clay mineral with waste and its incinerated ash, the water-permeable clay mineral by which the harmful substance was adsorbed and fixed may be melt | dissolved with a melting furnace (refer FIG. 1).
Thus, by mixing the water-permeable clay mineral when melting the waste and its incineration ash, elution of heavy metals from the produced solidified product can be appropriately prevented even under acidic conditions.

  The permeable clay mineral adsorbed with harmful substances may be melted in a state of being mixed with waste or its incinerated ash, or it may be melted in a state where the permeable clay mineral is separated from the waste or its incinerated ash. May be. By separating and melting the permeable clay mineral, it is possible to reduce the amount of melt-solidified product. The separation of the water-permeable clay mineral from the waste and its incinerated ash can be performed by utilizing the specific gravity difference. This separation can also remove harmful substances.

  In the above process, since it is a simple operation process of mixing a water-permeable clay mineral with disposal and its incineration ash, a large-scale installation is not required.

  By melting the water-permeable clay mineral to which harmful substances are adsorbed, it is possible to effectively realize detoxification, insolubilization, and prevention of diffusion of harmful substances such as heavy metals. Moreover, the molten solidified material can be suitably reused as a detoxified civil engineering material.

Further, when the waste and its incinerated ash are landfilled, a water-permeable clay mineral can be mixed to prevent penetration of harmful substances into the soil. Low cost due to the use of abundant natural water-permeable clay minerals.
Further, as shown in FIG. 2, a permeable clay mineral adsorbing layer 20 (inner bottom surface portion) is formed on the inner bottom surface portion and inner side surface portion (the slope portion in the case of a landfill disposal site) that forms a storage space for a landfill disposal site and containers. By adsorbing and fixing the above-mentioned harmful substances, it is possible to prevent diffusion due to the elution of the harmful substances.

  In the embodiment shown in FIG. 2, the low water-permeable clay layer 40, the water-permeable clay mineral adsorption layer 20 (20 </ b> A and 20 </ b> B), the water-impervious sheet 45, and the water-permeable clay mineral adsorption layer 20 are again formed on the base layer 50. They are laminated in order, and the waste 10 is placed thereon and covered with soil (covering layer 30). Further, a water-permeable clay mineral adsorption layer 20, a waste 10, and a soil covering layer 30 are further formed and backfilled thereon.

In this landfill site, a water-permeable clay mineral adsorption layer 20 is provided on the downstream side of water that permeates the waste 10. For this reason, even if harmful substances such as heavy metals are eluted, they can be appropriately adsorbed and captured by the adsorption layer 20 and further prevent contamination of deep soil and groundwater. That is, it is possible to suitably prevent the diffusion of harmful pollutants. And since a water-permeable clay mineral accept | permits permeation | transmission of water, it does not produce the problem by stagnant water.
Furthermore, a permeable clay mineral may be used as at least a part of the soil covering layer 30. For example, a water-permeable clay mineral may be mixed with the cover soil or spread as cover soil. According to this, the adsorption capacity of harmful substances can be increased, and the diffusion thereof can be suitably prevented.

Further, the present invention can also be applied to a paved road in which ordinary molten slag formed by melting waste and its incinerated ash is laid and paved as part of an inner layered laminate (see FIG. 3). .
For example, harmful substances such as heavy metals eluted from molten slag etc. come into contact with the water-permeable clay mineral and are adsorbed by the water-permeable clay mineral below the layer 60 on which the molten slag etc. is laid, It is preferable that the water-permeable clay mineral adsorption layer 20 is laid.

  As an example of the embodiment, as shown in FIG. 3, first, a permeable clay mineral adsorption layer 20 is laid on a base layer 50, and a layer 60 on which molten slag or the like is laid is provided. . The layer 60 on which the molten slag is spread is generally a layer that becomes a base of the pavement by a civil engineering material such as gravel or crushed stone, and at least a part of the civil engineering material that the molten slag substitutes for gravel or crushed stone. It is the layer used as. According to this, waste (molten slag) can be reused suitably as a civil engineering material.

In the construction of the paved road, the adsorbing layer 20 is provided again on the layer 60 on which the molten slag is spread, and the surface layer is covered with the asphalt 70.
According to this, harmful substances such as heavy metals eluted from the molten slag can be adsorbed and fixed by the lower adsorption layer 20, and organic pollutants eluted from the asphalt 70 are adsorbed and fixed by the upper adsorption layer 20. be able to. Therefore, the diffusion of harmful pollutants can be suitably prevented. And since a water-permeable clay mineral accept | permits permeation | transmission of water, it does not produce the problem by stagnant water.

  As another embodiment, the mixing / kneading treatment with the soil covering of the waste treatment plant can be used as an improvement material for soil-contaminated land using the adsorbing and fixing action of harmful substances of the water-permeable clay mineral.

  10% by mass of 1500 mg / kg lead nitrate and allophane dry-ground to a particle size of 300 microns or less are wet-mixed with incineration ash of general waste, dried at 100 ° C., heated at 1500 ° C. for 2 hours to melt, The solution was naturally cooled to obtain a melt-solidified product. The obtained melt-solidified product was pulverized and the lead content was measured by the measurement method according to the soil content survey based on Ministry of the Environment Notification No. 19 to obtain 55.4 mg / kg. The obtained value was significantly lower than the designated reference value 150 mg / kg of the designated area based on the provisions of Article 5, Paragraph 1 of the Soil Contamination Countermeasures Law.

  5% by mass of 1500 mg / kg lead nitrate and allophane dry-pulverized to a particle size of 300 microns or less are wet mixed with the incineration ash of general waste, dried at 100 ° C., heated at 1500 ° C. for 2 hours to melt, The solution was naturally cooled to obtain a melt-solidified product. The obtained melt-solidified product was pulverized and the lead content was measured by the measurement method according to the soil content survey based on Ministry of the Environment Notification No. 19 to obtain 77.6 mg / kg. The obtained value was significantly lower than the designated reference value 150 mg / kg of the designated area based on the provisions of Article 5, Paragraph 1 of the Soil Contamination Countermeasures Law.

  10% by mass of 4500 mg / kg of lead nitrate and dry-ground allophane to a particle size of 300 microns or less are wet mixed with the incineration ash of general waste, dried at 100 ° C., heated at 1500 ° C. for 2 hours to melt, The solution was naturally cooled to obtain a melt-solidified product. The obtained melt-solidified product was pulverized and the lead content was measured by the measurement method according to the soil content survey based on Ministry of the Environment Notification No. 19 to obtain 86.7 mg / kg. The obtained value was significantly lower than the designated reference value 150 mg / kg of the designated area based on the provisions of Article 5, Paragraph 1 of the Soil Contamination Countermeasures Law.

  10% by mass of 7500mg / kg of lead nitrate and dry pulverized allophane to a particle size of 300 microns or less are wet mixed with the incineration ash of general waste, dried at 100 ° C, heated and melted at 1500 ° C for 2 hours, The solution was naturally cooled to obtain a melt-solidified product. The obtained melt-solidified product was pulverized and the lead content was measured by the measurement method according to the soil content survey based on Ministry of the Environment Notification No. 19 to obtain 140.7 mg / kg. The obtained value was lower than the designated reference value 150 mg / kg of the designated area based on the provisions of Article 5, Paragraph 1 of the Soil Contamination Countermeasures Law.

Comparative example (without allophane)
1500 mg / kg of lead nitrate was wet mixed with the incineration ash of general waste, dried at 100 ° C., heated and melted at 1500 ° C. for 2 hours, and naturally cooled to room temperature to obtain a molten solidified product. The obtained melt-solidified product was pulverized and the lead content was measured by the measurement method according to the soil content survey based on Ministry of the Environment Notification No. 19 to obtain 488.4 mg / kg. The obtained value greatly exceeded the designated reference value of 150 mg / kg in the designated area based on the provisions of Article 5, Paragraph 1 of the Soil Contamination Countermeasures Law.

  As described above, the present invention has been described in various ways with preferred embodiments. However, the present invention is not limited to these embodiments, and many modifications can be made without departing from the spirit of the invention. That is.

DESCRIPTION OF SYMBOLS 10 Waste 20 Adsorbing layer of water-permeable clay mineral 20A Adsorbing layer of inner bottom part of water-permeable clay mineral 20B Adsorbing layer of slope part of water-permeable clay mineral 30 Covering layer 40 Low water-permeable clay layer 45 Water-impervious sheet 50 Base layer 60 Layer with molten slag, etc. 70 Asphalt

Claims (2)

Waste , hazardous metals such as heavy metals and organic pollutants eluted from the incineration ash and molten slag of the waste are brought into contact with the permeable clay mineral so that the toxic substance is adsorbed on the permeable clay mineral. On the other hand, the permeable clay mineral adsorbing layer is provided on the inner bottom surface and the inner surface of the landfill disposal space so that the water permeable clay mineral is placed close to and / or in contact with and fixed by adsorption. , A waste disposal site where a harmful substance detoxification method is used to prevent diffusion due to elution of the harmful substance by adsorbing and fixing the harmful substance,
A clay layer having a low water permeability is laminated on the base layer, and a water shielding sheet is laminated on the adsorption layer of the water permeable clay mineral laminated on the low water permeability clay layer . The adsorption layer of the water-permeable clay mineral is again laminated thereon, and the accommodation space is provided .
A waste disposal site, wherein the water-permeable clay mineral contains at least allophane and / or imogolite . The waste disposal site according to claim 1 , wherein the water-permeable clay mineral is used in at least a part of the covering soil.

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