JP3406149B2 - Hazardous substance removal method at final waste disposal site - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing harmful substances from a final waste disposal site for landfills of general waste and industrial waste.

[0002]

2. Description of the Related Art Generally, at a final disposal site for landfills of general waste and industrial waste, harmful substances such as heavy metals and pollutants such as BOD and COD may flow out to contaminate the surrounding environment. Therefore, there is a structure to prevent it. Hereinafter, both harmful substances such as heavy metals and pollutants will be referred to as harmful substances for description.

For example, in the interception type repository 1 shown in FIG. 2, in order to prevent outflow of harmful substances in the waste 3 due to rainwater 2, rainwater inflow prevention measures such as installation of a roof 4 are taken.

In the managed landfill 5 shown in FIG. 3, rainwater 6 is introduced to draw out the leachate 8 in which the harmful substances in the waste 7 are eluted, and the leachate 8 is introduced into the leachate treatment facility 9. Then, biological treatment, coagulation-sedimentation, sand filtration, activated carbon adsorption, and other treatments are performed to discharge the treated water 10 from which harmful substances have been removed.

[0005]

However, in the shut-off type repository 1 described above, harmful substances are left indefinitely, and the treatment is postponed in the future.

Since a large amount of leachate is generated during heavy rain or rainy season at the management-type disposal site 5, a large-scale adjusting tank for temporarily storing leachate is required. Also, the amount of treated leachate is usually large even during heavy rains and rainy seasons, and almost no leachate occurs during the dry season. The substance cannot be removed, and it is necessary to continue the treatment for a long time after the landfill is completed.

The present invention solves the above problems, and an object of the present invention is to enable efficient removal of harmful substances from waste final disposal sites.

[0008]

In order to solve the above problems, the method for removing harmful substances from a final waste disposal site according to claim 1 of the present invention is a waste final disposal method for landfilling general waste or industrial waste. A method for removing hazardous substances from a disposal site, wherein the rainwater is prevented from flowing into the final disposal site,
Sprinkle water on the landfilled waste and draw out the leachate leached from the waste, subject the extracted leachate to biological treatment, coagulation sedimentation, sand filtration, activated carbon adsorption, etc. removing the material, treated water to remove harmful substances be one which watering the waste and return cycle
Then, the water is mixed with acid. When watering,
A sufficient amount to elute harmful substances in waste,
Sprinkle as little water as possible quantitatively and continuously.

[0009]

According to the method for removing harmful substances at the final disposal site of waste according to claim 2 , the salt concentration in the leachate rises above a predetermined concentration.
When it is done, the treated water is further desalted, and the desalinated water is
In the desalination process of treated water, it is recycled and sprinkled on the waste.
The resulting concentrated saline solution is separated into acid and alkali by electrodialysis.
The acid is mixed with sprinkling water, and the alkali is sent to the harmful substance removal process.
It is used by circulating and returning .

According to the above construction, it is sufficient to treat a relatively small amount of substantially constant amount of leachate, and the harmful substances can be removed efficiently. In addition, the treated water can be effectively used.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, a final waste disposal site 11 is a landfill of waste 12, which is general waste or industrial waste, and a leachate treatment facility 13 is provided adjacent to the disposal site 11.

The final waste disposal site 11 is a shield type disposal site equipped with a roof 15 for preventing the inflow of rainwater 14, and a sprinkler 16 for sprinkling the waste 12 is provided below the roof 15. A water collecting device (not shown) for collecting the leachate leached from the waste 12 is buried in the bottom portion.

The leachate treatment facility 13 is a leachate treatment unit 1.
7, a desalting device 18 such as an electrodialysis method, and a bipolar membrane electrodialysis device 19, and the leachate 20 collected in the water collecting device is introduced into the leachate treatment device 17.
Although not shown, the leachate treatment device 17 includes pretreatment equipment such as a conditioning tank, calcium removal equipment such as a floc formation tank and sedimentation tank, biological treatment equipment such as an aeration tank, coagulation tank and coagulation sedimentation tank. Sedimentation equipment, sand filtration tower, activated carbon adsorption tower,
It has a chelate resin adsorption tower.

The operation of the above structure will be described below.
The sprinkler water 16 is sent to the sprinkler 16, the acid 22 is injected into the sprinkler water 21 to be sent, and the prepared acidic water 23 is sprinkled from above the waste 12 by the sprinkler 16 so that The leachate 20 containing the harmful substances and flowing into the water collecting device is introduced into the leachate treating device 17 of the leachate treating facility 13.

In the leachate treatment device 17, the pretreatment facility removes contaminants and adjusts the flow rate of the leachate 20, the calcium removal facility precipitates the calcium content, and the biological treatment facility removes mainly BOD and nitrogen to agglomerate. Mainly C in precipitation equipment
The OD and the suspension are coagulated and settled, the fine suspension remaining in the sand filtration tower is removed, the COD remaining in the activated carbon adsorption tower is removed, and the heavy metals remaining in the chelate resin adsorption tower are removed.

Treated water 24 from which these harmful substances have been removed
Is mixed with the water for sprinkling 21 and used in circulation. The loss due to evaporation or the like is compensated by the makeup water 25. When the salt concentration of the leachate 20 rises to a predetermined concentration, for example 0.5% or more, while the harmful substances are removed while circulating the treated water 24 (that is, the leachate 20), the leachate treatment apparatus 1
Treated water 24a having a salt concentration higher than that of No. 7 is sent to the desalting device 18 and desalted by an electrodialysis method or the like. Desalinated water 26
Is mixed with the water for sprinkling 21 and used in circulation.

The concentrated salt water 27 produced in the desalting device 18 is sent to a bipolar membrane electrodialysis device 19 to separate into an acid 28 and an alkali 29, the acid 28 is mixed with sprinkling water 21, and the alkali 29 is treated with leachate. It is returned to the device 17 and is recycled or used for coagulation-sedimentation treatment or the like. The acid 22 injected from the outside depends on the amount of the acid 28 separated at this time.
Adjust the amount of.

The harmful substance 30 accumulated in the leachate treatment device 17 is appropriately extracted. According to the above-mentioned structure, the waste 12 can be obtained by sprinkling water while using the blocking type disposal site 11.
Leachate 20 containing toxic substances by elution of harmful substances
Since it is circulated while removing harmful substances, the amount of leachate treated can be suppressed to the necessary minimum amount for the harmful substances to be eluted, and the harmful substances can be efficiently removed. Can be removed stably. At this time, since the acidic water 23 is sprinkled, the elution of heavy metals and the like can be promoted, and the treatment period after completion of landfill can be shortened.

Further, as a result of minimizing the amount of treated leachate, a preparation tank for storing leachate is not required as compared with the conventional controlled disposal site, which saves space, labor and energy. The cost can be reduced.

Further, the acid 28 and the alkali 29 are recovered from the concentrated salt water 27 after the desalting treatment, and the recovered acid 28 is used for spraying to the disposal site 11, and the alkali 29 is used for the coagulation and precipitation treatment. Therefore, effective use of by-products can be achieved.

The leachate treatment device 17 and the desalination device 1
8. The electrodialysis device 19 can be configured without being limited to the above-mentioned one, and may be appropriately modified, for example, an ozone treatment device may be provided in a stage before or after the desalting device 18.

[0023]

As described above, according to the present invention, since the water is sprinkled in the interception type disposal site, the amount of leachate to be treated can be minimized and the harmful substances can be efficiently removed. Space saving, labor saving, energy saving, and cost reduction can be realized compared with the conventional management type landfill.

When an acid is mixed and sprinkled with water, elution of harmful substances such as heavy metals can be promoted, and the treatment period after completion of landfill can be shortened. When the treated water is desalted, the acid and alkali can be recovered from the concentrated salt water,
The recovered acid / alkali can be effectively used in the treatment system.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic overall configuration of a final waste disposal site according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic overall configuration of a conventional barrier-type disposal site.

FIG. 3 is an explanatory diagram showing a schematic overall configuration of a conventional managed disposal site.

[Explanation of symbols]

11 Waste final disposal site 12 Waste 13 Leachate treatment facility 15 roof 16 Sprinkler 17 Leachate treatment equipment 18 Desalination equipment 19 Bipolar membrane electrodialyzer 20 Leachate 21 Water for watering 22 acid 23 Acidic water 24, 24a treated water 25 Make-up water 26 Desalinated water 27 concentrated brine 28 acid 29 Alkali 30 Hazardous substances

Continuation of front page (56) Reference JP-A-54-84328 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B09B 1/00

Claims (2)

(57) [Claims] 1. A method for removing harmful substances from a final waste disposal site for landfills of general waste or industrial waste, wherein rainwater is prevented from flowing into the final disposal site.
Sprinkle water on the landfilled waste and draw out the leachate leached from the waste, subject the extracted leachate to biological treatment, coagulation sedimentation, sand filtration, activated carbon adsorption, etc. removing the material, treated water to remove harmful substances be one which watering the waste and return cycle
A method for removing harmful substances at a final landfill site for waste, which comprises mixing acid with sprinkling water . 2. The salt concentration in the leachate rises above a certain level.
When it is done, the treated water is further desalted, and the desalinated water is
In the desalination process of treated water, it is recycled and sprinkled on the waste.
The resulting concentrated saline solution is separated into acid and alkali by electrodialysis.
The acid is mixed with sprinkling water, and the alkali is sent to the harmful substance removal process.
The method for removing harmful substances from a final disposal site of waste according to claim 1, wherein the method is used by circulating and returning .