JP3778775B2 - Landfill stabilization methods - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to landfill technology at final disposal sites such as general waste and industrial waste, and recovery technology at soil contamination sites, inappropriate disposal sites, illegal dumping sites, etc., and a landfill site that shortens the time required for processing It relates to the stabilization method.
[0002]
[Prior art]
The conventional waste landfill site is isolated from the surroundings by a storage structure that forms a levee body, and rainwater leaks into the surrounding ground as leachate by constructing a water barrier and protective soil (not shown) at the bottom. In addition, the collection and drainage pipes are installed to guide the leachate to the treatment facility. The collection and distribution pipe penetrates the storage structure and communicates with the pump pit, and a gate is provided at the opening of the collection and distribution pipe. The pump pit has a wastewater pump that discharges leachate. In the landfill structure, waste and soil cover are layered alternately.
[0003]
The amount of leachate in landfills depends on landfill quality, weather conditions such as rainfall, landfill structure, size of landfill, size of water collection area, landfill period, waste landfill elapsed time, etc. Is seen. For example, organic pollutants in leachate have a high concentration at the beginning of landfill, but decrease over time, and organic matter that is difficult to biodegrade remains after several years. In addition, when incineration residue or incombustible waste is landfilled, since there are many inorganic substances, SS, salts (Ca, Cl, etc.), heavy metals (Pb, Hg, Cd, etc.) and dioxins derived therefrom are included. In addition, when there are many organic substances that are easily biodegradable in incineration residues or incombustible waste, BOD, COD, TN, NH ₄ ⁺ -N, etc. have a relatively high concentration.
[0004]
[Problems to be solved by the invention]
This landfill site is closed when landfill in the entire site has been completed and the concentration of harmful metals such as heavy metals and salt in the leachate has fallen below the permissible level and the quality of the leachate has stabilized. Yes.
[0005]
Therefore, it took many years for the landfill site to start and close, and the scale and capacity of the treatment plant in the leachate treatment facility had to be set for the total amount of precipitation falling on the landfill site.
[0006]
In addition, the amount of dioxins in incineration residue (fly ash, main ash) is extremely low, the dioxin potential in the landfill is high, and the risk of landfill is high over a long period of time. Becomes longer.
[0007]
This invention solves the above-mentioned subject, and aims at providing the stabilization method of the landfill which can stabilize the quality of leachate at an early stage, and can shorten the period from the start of landfill to closure. To do.
[0008]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the stabilization method of the present invention according to claim 1 pretreats waste before putting it into a landfill, and the waste that has been finely crushed is pre-machined. By washing with water in the washing process, organic substances, heavy metals and dioxins in the waste are eluted in the washing liquid, and the solid waste obtained by solid-liquid separation of this washing waste water in the separation and removal process and the mechanical washing process in the previous stage Dioxins remaining in the waste are eluted in the cleaning liquid by washing the pre-wash with the organic solvent in the post-machine wash process, and the post-wash in the post-machine wash process is re-injected into the pre-machine wash process. , washed with water, this after machine washing of the final wash was charged to the landfill, water treatment and cleaning waste water eluate and subsequent mechanical cleaning step of separating and removing step landfill leachate treatment facility It is intended to.
[0011]
With the above configuration, the removal rate of salts, heavy metals and dioxins contained in the waste is increased, and these harmful substances are not eluted in the leachate, reducing the time required from the start of operation to closure of the landfill site. can do.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, landfill waste (or carry-in waste) 1 contains multiple types of pollutants such as municipal waste incineration ash and industrial waste, and this landfill waste 1 is thrown into the landfill. Prior to disposal, pre-treatment.
[0013]
The landfill waste 1 is finely crushed to a particle size of 30 mm or less in the crushing step 2, and the crushed waste is washed with a cleaning liquid composed of water or an organic solvent in the mechanical washing step 3. In the machine cleaning step 3, for example, a predetermined amount of waste and a predetermined amount of water or organic solvent are put in a ratio (volume ratio) of 1:10 into a rotating drum of a mechanical washer, and once (about 20 minutes). In this cleaning operation, the cleaning operation is performed by stirring the waste and the cleaning liquid by the rotation of the rotating drum. By this washing, organic substances (BOD, COD, etc.), heavy metals (Pb, Hg, Cd, etc.) and dioxins in the waste are eluted in the washing liquid, and the washing waste water (slurry) in the mechanical washing machine after one washing operation is completed. ) To the separation and removal step 4. Thereafter, a cleaning liquid composed of water or an organic solvent is newly put into the rotating drum of the mechanical cleaning machine to perform the cleaning operation, and this cleaning operation is performed four or more times. After all the cleaning operations are completed, the machine-cleaned items remaining in the mechanical washer are thrown into the landfill.
[0014]
The stabilization index of the waste obtained by this washing is as follows for each component amount in the filtered water obtained by filtering the washing waste water after the final washing operation.
EC (electrical conductivity) ≦ 1500 μs / cm
Pb ≦ 0.1ppm
DXN (Dioxins) Content ≦ 10pg-TEQ / L
COD ≦ 20ppm
In the separation / removal process 4, for example, the washing wastewater is settled and separated in a sedimentation separation facility, the settled solid matter is thrown into a landfill and disposed in landfill, and the desorbed liquid is water-treated in the leachate treatment facility in the landfill.
[0015]
This configuration removes salts, heavy metals, and dioxins contained in the waste in advance, so that these harmful substances do not elute into the leachate, shortening the time required from the start of operation to closure of the landfill site. can do.
[0016]
FIG. 2 shows another embodiment of the present invention. In FIG. 2, landfill waste (or carry-in waste) 11 contains multiple types of pollutants such as municipal waste incineration ash and industrial waste, and this landfill waste 11 is thrown into a landfill. Prior to waste disposal.
[0017]
The landfill waste 11 is finely crushed to a particle size of 30 mm or less in the crushing step 12, and the crushed waste is washed with washing water in the preceding machine washing step 13. In the machine cleaning step 13 in the previous stage, for example, a predetermined amount of waste and a predetermined amount of water are introduced into a rotating drum of a mechanical washer at a ratio (volume ratio) of 1:10 once (about 20 minutes). In the cleaning operation, the cleaning operation is performed by stirring the waste and the cleaning liquid by the rotation of the rotating drum. By this washing, organic substances (BOD, COD, etc.), heavy metals (Pb, Hg, Cd, etc.) and dioxins in the waste are eluted in the washing water, and the washing waste water (slurry in the mechanical washing machine) after the completion of one washing operation. ) To the separation and removal step 14. After that, cleaning water is newly added into the rotating drum of the mechanical cleaning machine to perform cleaning work, and this cleaning work is performed four or more times.
[0018]
In the separation / removal step 14, for example, the washing wastewater is settled and separated in a sedimentation separation facility, and the desorbed liquid is treated with water in a leachate treatment facility in a landfill. The solid matter settled in the separation / removal step 14 and the pre-washed product in the pre-machine wash step 13 are washed with an organic solvent in the post-machine wash step 15.
[0019]
In the subsequent mechanical cleaning step 15, for example, a predetermined amount of waste and a predetermined amount of organic solvent (concentration of 5% methanol) are charged in a ratio (volume ratio) of 1:10 into a rotating drum of a mechanical cleaning machine, Heating is performed at 30 to 80 ° C. (optimum 80 ° C.), and the cleaning operation is performed by stirring the waste and the cleaning liquid by rotating the rotating drum in one cleaning operation (about 20 minutes). Dioxins remaining in the waste are eluted in the cleaning liquid by this cleaning operation, and the cleaning wastewater is treated with the leachate treatment facility in the landfill.
[0020]
The post-cleaning material in the post-machine washing step 15 is washed again with washing water in the pre-machine wash step 13. In the machine cleaning step 13 in the preceding stage, for example, a predetermined amount of waste and a predetermined amount of water are put into a rotating drum of a mechanical washer at a ratio (volume ratio) of 1:10 once (about 20 minutes). In this cleaning operation, the cleaning operation is performed by stirring the waste and the cleaning liquid by the rotation of the rotating drum. The final washed product after machine washing is thrown into the landfill.
[0021]
The stabilization index of the waste obtained by this washing is as follows for each component amount in the filtered water obtained by filtering the washing waste water after the final washing operation.
EC (electrical conductivity) ≦ 1500 μs / cm
Pb ≦ 0.1ppm
DXN (dioxins) content ≦ 10 ng-TEQ / g
That is, the DXN (dioxins) content is extremely small compared to the previous embodiment.
[0022]
【The invention's effect】
As described above, according to the present invention, waste is pretreated before being put into a landfill, and salts, heavy metals and dioxins contained in the waste are removed in advance. It does not elute in water, and the time required from the start of operation of the landfill site to closure can be shortened.
[Brief description of the drawings]
FIG. 1 is a flow sheet showing a processing method in an embodiment of the present invention.
FIG. 2 is a flow sheet showing a processing method in another embodiment of the present invention.
[Explanation of symbols]
1 Landfill waste 2 Crushing process 3 Machine washing process 4 Separation and removal process

Claims (1)

Waste is pretreated before being put into the landfill, and finely crushed waste is washed with water in the previous mechanical washing process to remove organic matter, heavy metals, and dioxins in the washing solution. The solid waste obtained by solid-liquid separation in the separation and removal process and the pre-wash in the previous mechanical washing process are washed with an organic solvent in the post-mechanical washing process to remain in the waste. Dioxins to be eluted in the cleaning liquid, the latter-stage washing product in the latter-stage machine washing step is again put into the former-stage machine washing step and washed with water, and the final washing item after this machine washing is thrown into the landfill. A landfill stabilization method characterized in that the desorbed liquid in the separation and removal process and the washing wastewater in the subsequent mechanical washing process are treated with a leachate treatment facility at the landfill.

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