JP2007050326A - Method for utilizing final disposal site, and final disposal facility - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for utilizing a final disposal site, by which waste can be maintained at a low cost and to provide a final disposal facility. <P>SOLUTION: The final disposal site is constituted so that a recessed part is formed on the ground and covered with a liner sheet to enable the recessed part to shut off water and waste is buried in the recessed part having a water sealing structure. A circulation waterway is arranged on the slope of the final disposal site, exuding water produced at the final disposal site is returned to the circulation waterway, the returned exuding water is vaporized in the circulation waterway while flowing therein, so that the amount of the exuding water remaining in an exuding water regulating pond can be reduced owing to the vaporization. The exuding water is cleaned by a microbe deposited on crushed stones arranged in the circulation waterway and on the crushed stones arranged at the bottom of the final disposal site. The treatment load to be imposed on an exuding water treatment facility is decreased since heavy metals are removed by heavy metal adsorption ability of the crushed stones. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a final disposal site operation method for landfill disposal of waste and a final disposal facility operated by this operation method.

Fig. 5 shows the structure of the final disposal site that has been used in the past. In the figure, 10 indicates the final disposal site. In this final disposal site 10, the ground surface having a recessed surface is covered with a water-impervious sheet 11, and the recessed surface is formed as a water-impervious structure.
An operation period of about 10 to 20 years is required for the final disposal site 10 to become full, and the landfill disposal of waste is performed during the operation period. During the operation period, the rainwater 21 falls on the waste 20, and the rainwater touched by the waste 20 is regarded as contaminated by the waste 20 and is called leachate 22. The leachate 22 is required to be purified. For this purpose, a drain pipe 12 is laid on the bottom surface of the final disposal site 10, and the leachate 22 is collected by the drain pipe 12, and the collected leachate 22 is adjusted to the leachate provided outside the final disposal site 10. Water is collected in the pond 30.

After the amount of water is adjusted in the leachate adjustment reservoir 30, it is appropriately purified at the leachate treatment facility 40 and discharged into the water area after the purification treatment.
As points to keep in mind when setting the scale of the leachate treatment facility 40,
1. The operation period of the final disposal site 10 is as long as about 10 to 20 years, and it must be possible to properly handle the rain during that period.
2. In order to achieve early stabilization by promoting the decomposition of waste in the final disposal site 10, it is necessary to make the final disposal site 10 an aerobic atmosphere, and the leachate is stagnated in the final disposal site 10. It must be quickly removed out of the final disposal site 10 without water (anaerobic atmosphere).

Water purification performed at the leachate treatment facility 40 includes measures for organic pollutants such as BOD and measures for heavy metal treatment.
Measures for organic pollutants such as BOD For the current measures for organic pollutants such as BOD, biological treatment such as the activated sludge method, rotating disk method, contact aeration method, etc. is performed in the leachate treatment facility 40.
(Activated sludge method)
Mix the returned sludge into the influent wastewater in the aeration tank and aerate with a blower. Organic matter in the wastewater is purified by activated sludge microorganisms. After introducing and mixing the activated sludge mixed liquid into the settling tank, the supernatant water is discharged as treated water. At the same time, part of the activated sludge is returned to the aeration tank, and the other part is treated as excess sludge and disposed of.
(Rotating disk method)
Rotate the disc in a semicircular aquarium. The disk repeats rotation in the air and takes in oxygen when it appears in the air. This disc is rotated at a constant speed, and the waste water is purified by microorganisms attached to the surface.
(Contact aeration method)
Place the contact filler in the aeration tank and aerate. The organic matter in the waste water is purified by microorganisms adhering to the filter medium surface. Sediment separation, sludge return and extraction are similar to the principle of activated sludge.

These treatments are performed by adjusting the volume of the biological treatment tank, the amount of chemicals, the amount of aeration, etc. according to the concentration of the organic pollutant in the leachate that flows in, and the organic pollutant concentration in the leachate is high If so, the maintenance cost will increase accordingly.
Heavy metal countermeasures Heavy metals in the current leachate are removed by the hydroxide method, sodium sulfide method, ferrite method, chelate resin method, etc. separately from the aforementioned biological treatment.
(Hydroxylation method)
The pH of the wastewater is made alkaline, and the heavy metal is made into a hydroxide that is hardly soluble in water, and then precipitated and separated using a flocculant.
(Sodium sulfide method)
A heavy metal and sodium sulfide are reacted to form a sulfide which is hardly soluble in water, and is precipitated and separated using a flocculant.
(Ferrite method)
When the temperature of the waste water is heated to 70 ° C. or more and ferrous sulfide is added and the pH of the waste water is made alkaline, the ferrite insoluble in water is generated. This is magnetically separated.
(Chelate resin method)
A kind of ion exchange is used to chelate and remove heavy metals in the wastewater from the functional groups of the chelating adhesive. Chelate resins include mercury adsorption and general metal adsorption.

  These treatments require the installation of dedicated equipment, and after maintenance, costs such as expensive chemicals, recycling and replacement of consumables such as chelates, and equipment inspection and repair are incurred. In addition, management by specialized technology is necessary for operation.

As described above, the leachate treatment facility 40 performs advanced water quality purification treatment, and the cost required for the purification treatment increases in proportion to the treatment amount and load amount of the leachate. Furthermore, since the expense required for the purification process continues for a period (10 to 20 years) in which the final disposal site 10 is operated, the accumulated amount is large.
The object of the present invention is a final disposal site operation method capable of reducing the amount of leachate treated and load in the leachate treatment facility 40 and reducing the cost required for operation as much as possible, and the operation method. The final disposal facility is proposed.

In the present invention, in the final disposal site operation method in which the recessed surface has a water-impervious structure and waste is landfilled in the recessed surface of the water-impervious structure, the process of collecting leachate generated in the final disposal site into the leachate adjustment pond And the process of circulating the leachate collected in the leachate control pond to the circulation channel provided in the final disposal site, the evaporation process of evaporating the returned leachate in the circulation channel, and the remaining in the leachate adjustment pond And a step of introducing the leachate into the leachate treatment facility.
Furthermore, the final disposal site operation method according to the present invention is characterized in that crushed stone composed of limestone is disposed at the bottom of the final disposal site and the bottom of the circulation channel, and includes a biological treatment process and a heavy metal treatment process.

  The final disposal facility according to the present invention has a final disposal site having a concave surface with a water-impervious structure constituted by covering the concave surface with a water shielding sheet, and discharges leachate generated in this final disposal site to the outside of the final disposal site. A wastewater treatment section that collects the leachate discharged from the wastewater treatment section, and a pump that recirculates a portion of the leachate collected in the leachate adjustment pond to the final disposal site. In the final disposal site, the leachate is circulated by receiving the leachate circulated by the pump, and the leachate is circulated, and the leachate remaining in the leachate adjustment pond is introduced and the leachate is circulated. And a leachate treatment facility to be treated.

  Furthermore, the final disposal facility according to the present invention is characterized in that crushed stone made of limestone is arranged at the bottom of the final disposal site and the bottom of the circulation channel.

  According to the final disposal site operation method and the final disposal facility according to the present invention, the leachate discharged from the final disposal site is returned to the circulation channel established in the final disposal site and evaporated in this circulation channel. The amount of leachate remaining can be reduced. As a result, the amount of leachate to be purified at the leachate treatment facility 40 can be reduced. Furthermore, according to the present invention, the purification of leachate by microorganisms attached to the crushed stones arranged in the circulation channel and the crushed stone arranged at the bottom of the final disposal site, and the removal of heavy metals by the heavy metal adsorption capacity of these crushed stones for purification treatment. An effect peculiar to the present invention that the cost required can be reduced can be obtained.

  The final disposal site operation method and the final disposal facility according to the present invention reduce the amount of leachate by circulating the leachate discharged from the final disposal site to a circulation channel provided in the final disposal site and evaporating it in the circulation. . For this purpose, it is the best embodiment that the final disposal site operation method and the final disposal facility according to the present invention are implemented in an area having a warm climate.

  One embodiment of the final disposal facility of the present invention will be described with reference to FIGS. Parts corresponding to those in FIG. 5 are denoted by the same reference numerals. In the figure, 10 indicates the final disposal site. As described in FIG. 5, the final disposal site 10 forms a concave surface on land having a desired area, and the concave surface is covered with a water shielding sheet 11 or the like to form a water shielding structure. As the shape of the concave surface, the four sides are sloped so that the earth and sand will not collapse, and each slope and bottom are covered with the water shielding sheet 11. A drain pipe 12 is installed on the bottom surface and the leachate is discharged to the outside of the final disposal site 10 through the drain pipe 12. The leachate discharged through the drain pipe 12 is collected in the leachate adjustment pond 30.

  In this invention, the pump P is installed in the leachate adjustment pond 30, and part of the leachate collected in the leachate adjustment pond 30 by this pump P is returned to the circulation channel 50 provided in the final disposal site 10. For example, the circulation channel 50 can be configured by arranging U-shaped grooves or the like on the small slopes forming the final disposal site 10. The circulation water channel 50 is provided with a gradient, and the leachate flows unilaterally in the circulation water channel 50 due to this gradient. 1 and 2 show an example in which the circulation channel 50 is constructed only on a part of the slope, but it may be constructed over two or three slopes. The total length of the circulation channel 50 is preferably long, and the evaporation amount of the leachate can be increased by forming it long. By increasing the evaporation amount of the leachate, there is an advantage that the amount of leachate reinjected into the final disposal site 10 from the most downstream side of the circulation channel 50 can be reduced. The leachate reinjected into the final disposal site 10 passes through the waste 20 and reaches the bottom surface of the final disposal site 10 again, and is returned to the leachate adjustment reservoir 30 through the drain pipe 12 again. When the evaporation amount in the circulation channel 50 is large, there is an advantage that the amount of the leaching amount returned from the circulation channel 50 to the final disposal site 10 can be reduced.

  Thus, by returning the leachate collected in the leachate adjustment pond 30 to the final disposal site 10 through the circulation channel 50, the amount of leachate remaining in the leachate adjustment pond 30 can be reduced. As a result, the amount of leachate that must be treated at the leachate treatment facility 40 can be reduced, and the cost required for treatment can be reduced.

3 and 4 show a second embodiment of the present invention. In this embodiment, a crushed stone 60 is laid on the bottom of the final disposal site 10 and the bottom of the circulation channel 50, and a biological treatment for decomposing organic pollutants such as BOD by the crushed stone 60 and a heavy metal adsorption treatment are performed. Examples are shown.
As the crushed stone 60, what crushed Ryukyu limestone can be used, for example.
The principle of the biological treatment is an adhesion type biofilm treatment similar to the contact aeration method or the rotating disk method. By contact with the leachate, microorganisms adhere to the surface of the crushed stone 60 and a biofilm is formed. . By using this biological treatment together, in the circulation channel 50, in addition to the evaporation effect described in the first embodiment, it is possible to reduce the water quality load of the returned leachate, and the chemicals consumed in the leachate treatment facility 40 In addition, the cost required for aeration can be reduced, leading to a reduction in maintenance costs.

  On the other hand, when Ryukyu limestone is used as the crushed stone 60, the Ryukyu limestone is a coral reef deposit in the Ryukyu coral sea. This Ryukyu limestone is known to be capable of absorbing heavy metals under aerobic conditions. Specifically, calcium contained in the Ryukyu coral reacts with oxygen and heavy metals under the presence of microorganisms in the final disposal site 10, and the heavy metal becomes an insoluble compound and exhibits a phenomenon of being fixed in limestone. As described above, by placing the crushed stone 60 made of Ryukyu limestone in the circulating water channel 50 and the bottom portion of the final disposal site 10 as described above, the crushed stone 60 made of Ryukyu limestone is disposed in the final disposal site 10. Adsorb heavy metals.

  By using this heavy metal adsorption method, the special equipment for heavy metal treatment that has been conventionally provided in the leachate treatment facility 40 is not required in the present invention, and the cost of chemicals for treating heavy metals can be reduced. Therefore, it leads to reduction of facility maintenance cost and maintenance cost of leachate treatment facility. Furthermore, since dedicated equipment is unnecessary, there is an advantage that management by dedicated technology is not required.

  The final disposal site operation method and the final disposal facility according to the present invention are utilized for the operation of the final disposal site for processing general waste and industrial waste operated by local governments.

The top view for demonstrating 1st Example of this invention. Sectional drawing on the AA line of FIG. The top view for demonstrating 2nd Example of this invention. Sectional drawing on the BB line of FIG. Sectional drawing for demonstrating the structure of the conventional final disposal site.

Explanation of symbols

10 Final disposal site 30 Leachate adjustment pond 11 Impermeable sheet 40 Leachate treatment facility 12 Drain pipe 50 Circulating water channel 20 Waste 60 Crushed stone

Claims (4)

In the final disposal site operation method in which the recessed surface has a water shielding structure, and waste is landfilled on the recessed surface of this water shielding structure.
The process of collecting leachate generated on the concave surface into the leachate adjustment pond
The process of circulating the leachate collected in the leachate control pond to the circulation channel provided in the final disposal site,
An evaporation process for evaporating the refluxed leachate in the circulation channel;
A process of introducing the leachate remaining in the leachate adjustment pond to the leachate treatment facility;
The final disposal site operation method characterized by including. In the final disposal site operation method according to claim 1,
A final disposal site operating method, comprising arranging a crushed stone made of limestone at the bottom of the final disposal site and the bottom of a circulation channel, and including a biological treatment process and a heavy metal treatment process. A final disposal site with a bottom surface of a water shielding structure constituted by covering the concave surface with a water shielding sheet;
A wastewater treatment unit for discharging leachate generated in the final disposal site to the outside of the final disposal site;
A leachate adjustment pond that collects leachate drained from this wastewater treatment section;
A pump for circulating a portion of the leachate collected in the leachate control pond to the final disposal site;
A circulation channel that is provided in the final disposal site, receives the leachate circulated by the pump, circulates the leachate, and evaporates the leachate;
A leachate treatment facility for introducing leachate remaining in the leachate adjustment pond and purifying the leachate;
And a final disposal facility. In the final disposal facility according to claim 3,
A final disposal facility, characterized in that crushed stone made of limestone is disposed at the bottom of the final disposal site and the bottom of the circulation channel.

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