JPH11216441A - Waste disposal method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower the concn. of hazardous materials, such as heavy metals and dioxin, and to gradually make deposited waste pollution-free even if these hazardous materials are included in the leachate from a waste landfill hole. SOLUTION: While water collecting pipes 5, water replenishing pipes 6 and air replenishing pipes 7 are embedded into the waste landfill hole 2, the landfill hole is filled with the waste and the leachate collected by the water collecting pipes 5 is supplied to a water treatment apparatus 22. A closed circulation system 20 which refluxes the treated leachate subjected to a purification treatment in the water treatment apparatus 22 from the water replenishing pipes 6 into the landfill hole 2 is formed. When the leachate is circulated and supplied by the closed circulation system 20, the hazardous materials in the deposited waste 4 are captured via the leachate in the water treatment apparatus 22 and the purified leachate is refluxed to the landfill hole 2 and, therefore, the deposited waste 4 is gradually purified and made pollution-free.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a waste disposal method that can gradually reduce the concentration of harmful substances such as heavy metals and dioxins contained in the waste after landfilling the waste. About the method.

[0002]

2. Description of the Related Art There are three types of final disposal sites for wastes set by the government: stable disposal sites, managed disposal sites, and closed disposal sites. Of these, the managed landfills store sedimentary waste dumped in landfills safely and sanitarily for a long period of time, reducing the volume and volume of the sedimentary waste, and stabilizing and harmless. And eventually return to nature. Rainwater and surface water that penetrates and penetrates the waste landfill hole will elute harmful substances from the sedimentary waste dumped into the hole and leak water, and the leakage will contaminate soil and groundwater. In order to prevent this, a plastic sheet, rubber sheet, asphalt sheet, etc. are applied to the inner surface of the waste landfill hole, or a water barrier treatment such as forming a concrete wall is applied, and the bottom of the landfill hole is connected. In general, the water collected in the hole is discharged to a purification treatment facility through the drain pipe thus provided, and the purification treatment facility performs biological and chemical detoxification treatment, and then discharges the water to a river or the like. Therefore, the waste that can be landfilled in such a managed disposal site is limited to waste that has high BOD and COD and contains organic substances, but does not contain harmful metals.

[0003] However, it is practically impossible to check all of the waste received at a disposal site. If waste containing heavy metals is mixed in the landfill waste, Heavy metals that are difficult to completely treat by the purification facility elute in the wastewater sent to the purification facility by the drain pipe from the landfill hole, and when the water containing the heavy metals is discharged into the river, There is a risk of causing soil pollution and water pollution throughout the basin. Therefore, the applicant has
From the start of digging a waste landfill hole until the hole is landfilled with the dumped waste, a large tent warehouse that can accommodate the hole is set up to allow rainwater and surface water to enter the waste landfill hole. After infiltration is stopped and the landfill hole is filled with waste, the waste is covered with a water-impervious sheet such as a plastic sheet, rubber sheet, or asphalt sheet before covering it. By sealing the opening of the landfill hole and permanently preventing the penetration and penetration of rainwater and surface water into the hole, drainage from the waste landfill hole,
A new type of management type disposal site that eliminates the possibility of environmental pollution by eliminating the need for purification treatment of the wastewater is provided (Utility Model Registration No. 3040303).

[0004] However, when the inner surface and the opening of the waste landfill hole are subjected to the water-blocking treatment as described above, the inside of the waste landfill hole tends to be deficient in moisture and oxygen, and is discarded in the hole. The oxidation of air and water, the hydrolysis of water, and the hydration, which chemically decompose harmful components in sedimentary waste, are unlikely to progress, and organisms and microorganisms in soil and waste sludge do not easily progress. It has been found that the growth and growth are inhibited and biological decomposition is unlikely to occur. Furthermore, since weeds and the like do not grow on the surface layer of the sedimentary waste, it has been found that decomposition by the respiration of plant roots and the like does not easily occur. For this reason, there is a concern that the weight reduction, volume reduction, stabilization, and detoxification of sedimentary waste do not progress slowly. Therefore, the present applicant embeds an air supply pipe and a water supply pipe in the sediment waste in the waste landfill hole to supply a suitable amount of air and moisture, thereby making it possible for the waste water to be chemically treated with air and water. A management type disposal site improved so as to be able to promote the decomposition action and the biological decomposition action by microorganisms or the like was proposed (Utility Model Registration No. 3045009).

[0005]

However, an alkylmercury compound (R-Hg), mercury or its compound (Hg), cadmium or its compound (C
d), lead or its compound (Pb), hexavalent chromium (C
When heavy metals such as r ⁶⁺ ), copper or its compound (Cu), zinc or its compound (Zn) are eluted, these heavy metals cannot be detoxified only by water and air. The leachate is circulated and supplied to the sedimentary waste so as not to cause environmental pollution problems in the surrounding area.However, when the useful life of several tens to one hundred years has passed after the landfill, If the impermeable sheet affixed to the inner surface of the landfill hole deteriorates due to aging and breaks, heavy metals may leak around the waste disposal site and adversely affect the environment. Also, when leachate containing heavy metals is circulated and supplied,
Since microorganisms called activated sludge contained in sedimentary wastes also die, there is a problem that even wastes that can be made harmless by natural purification cannot be made harmless. Furthermore, incineration ash discarded as waste often contains a large amount of highly toxic dioxin, and this dioxin is also extremely stable and hardly decomposed, so that it cannot be made harmless with water and air alone.

Further, in order to confirm the degree of harmlessness of the deposited waste, a waste sample is taken out from the landfill hole and subjected to chemical analysis. Must be done. Moreover, in order to accurately know the degree of detoxification in a vast landfill, several to several tens of samples are required, so that there is also a problem that a huge amount of cost is required for a single survey.

[0007] Accordingly, the present invention provides a method for killing microorganisms in waste when leaching water from a waste landfill hole is circulated and supplied, even if the leachate contains harmful substances such as heavy metals and dioxins. Technology to reduce the concentration of harmful substances and gradually detoxify sedimentary waste, and to easily monitor the degree of detoxification of sedimentary waste without boring surveys. Is a subject.

[0008]

In order to solve this problem, a method of the present invention is to provide a water collection pipe for collecting leachate from sedimentary waste into a landfill hole having a water-impermeant inside. A landfilling step of burying a hydration pipe for supplying moisture to the sedimentary waste and an air supply pipe for blowing air supplied from the outside into the sedimentary waste while burying the waste with the waste; The leachate collected by the collection pipe buried in the object is supplied to the water treatment device without flowing out to the outside, and the treated leachate purified by the water treatment device is landfilled from the water supply pipe. Forming a closed circulation system that recirculates in the hole, and circulating the leachate through the closed circulation system until the leachate is rendered harmless based on the results of the water quality test of the untreated leachate flowing into the water treatment device, thereby accumulating waste. Purification for purifying objects Characterized in that it consists of a degree.

According to the present invention, the landfill hole is buried with waste while the water collection pipe, the water supply pipe, and the air supply pipe are buried in the waste landfill hole, and the sediment collected by the buried water collection pipe is collected. A closed circulation system is formed in which the leachate from the waste is supplied to the water treatment apparatus, and the treated leachate purified by the water treatment apparatus is returned from the water supply pipe into the landfill hole. When various harmful substances are mixed in the sedimentary waste, if the leachate leaching from the sedimentary waste is circulated and supplied in a closed circulation system, the harmful substances in the sedimentary waste are circulated through the leachate. And collected by a water treatment device from a waste landfill hole. As this water treatment device, for example, a waste oil removal device for removing waste oil contained in leachate, a metal adsorption device for selectively adsorbing and removing metal ions contained in leachate, and collecting dioxin contained in leachate If a dioxin removing device is provided, harmful substances such as waste oil, heavy metals, and dioxin in the leachate can be removed. The effluent water purified by the water treatment device is returned to the landfill hole and is again supplied to the water treatment device via the closed circulation system together with the harmful substances eluted from the sedimentary waste, so that the effluent water is circulated. As a result, harmful substances in the sedimentary waste are collected by the water treatment device, and the sedimentary waste is gradually purified and made harmless.

[0010] Furthermore, since the untreated leachate flowing into the water treatment device is sampled and subjected to a water quality test to monitor the concentration of harmful substances contained in the leachate, the degree of harmlessness in the landfill hole is determined. Can be easily known. In this case, since the leachate is leached from all of the sedimentary waste, it is possible to objectively grasp the degree of detoxification as a whole without performing a boring survey at several to tens of places.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The method of the present invention will be described below. FIG. 1 is an explanatory diagram showing a waste disposal site used in the method of the present invention, and FIG. 2 is an explanatory diagram showing another waste disposal site used in the method of the present invention.

In the waste disposal site 1 shown in FIG. 1, the inner surface of a waste landfill hole 2 dug in the ground is subjected to a water-blocking treatment with a water-blocking sheet 3 such as a plastic sheet, a rubber sheet, and an asphalt sheet. I have. In the sedimentary waste 4 dumped in the waste landfill hole 2, a water collection pipe 5 for collecting leachate from the sedimentary waste 4 at the bottom of the landfill hole 2, and a leachate collected by the water collection pipe 5. A water supply pipe 6 for circulating water to flow out into the sedimentary waste 4, an air supply pipe 7 for blowing air supplied from outside into the sedimentary waste 4, and discharging excess gas in the sedimentary waste 4. Exhaust pipe 8 is buried. Then, in this state, the opening of the waste landfill hole 2 is
Sealed by a waterproof material 9 such as a plastic sheet, a rubber sheet, or an asphalt sheet having excellent waterproofness and weather resistance that covers the sediment waste 4 dumped into the inside, and furthermore, a soil covering 10 is placed on the waterproof material 9. It has been subjected.

The water collecting pipe 5, the water supply pipe 6, and the air supply pipe 7 have a plurality of perforations (not shown) formed along the longitudinal direction of a plastic pipe such as a hard vinyl chloride pipe, and are laid in layers. It is buried in the gravel 11 to prevent the perforations from being blocked by the sediment waste 4. Further, the water collecting pipe 5, the water supply pipe 6, and the air supply pipe 7 are communicated with the outside via pipes 5a, 6a, 7a penetrating the water-blocking sheet 3 or the water-blocking material 9, and each of the pipes 5a, 6a. , 7a and the impermeable sheet 3 or impermeable material 9 are hermetically welded. further,
The air supply pipe 7 is connected to a compressor 12 disposed outside the landfill hole via a pipe 7a so that air can be supplied as needed.

A closed circulation system 20 is formed to supply the effluent water collected by the water collection pipe 5 to the waste landfill hole 2 via the water supply pipe 6 without flowing out to the outside. The circulation system 20 is provided with a strainer 21 for removing relatively large solid foreign substances contained in the leachate, and a water treatment device 22 for removing harmful substances contained in the leachate, and is included in the leachate. A water quality inspection device 23 for monitoring the type and concentration of harmful substances is provided. Reference numeral 24 denotes a treated leachate storage tank for temporarily storing the treated leachate treated by the water treatment device 22, and 25 designates the treated leachate when the water supplied to the waste landfill hole 2 is insufficient. Rainwater storage tanks 26 and 27 for replenishing the leachate storage tank 24 with rainwater are pumps.

The water treatment device 22 includes a filter (waste oil removal device) 28 for removing waste oils, a metal adsorption device 29 for selectively adsorbing metal ions contained in leachate, and a dioxin contained in leachate. A dioxin removing device 30 is provided.

The metal adsorption device 29 has an inlet 31 in at the upper end and a drain 31 ou at the lower end.
The chelating agent or chelating resin that selectively adsorbs metal ions contained in the leachate to form a chelate compound is filled in the treatment tower 31 where the t is formed, and the leachate is injected from the inflow port 31in to downflow. Let drain 31 out
From which leachate from which metals have been removed is discharged. As the chelating agent or the chelating resin, any one whose main component is dimethylglyoxime, dithizone, oxine, acetylacetone, EDTA, NTA or the like depending on the type of metal ions contained in the leachate can be used. .
Further, the effective pH range varies depending on the type of the chelating agent or the chelating resin charged in the treatment tower 31. Therefore, the pH of the leachate is detected at the upstream of the treatment tower 31 and the optimum pH is determined.
A pH adjuster 32 for adjusting the H value is provided. In this case, the metal adsorption device 29 may include a plurality of processing towers 31 according to the type of metal to be removed.

The dioxin removing device 30 uses activated carbon for adsorbing dioxin, a molecular sieve, or a special filter for collecting dioxin on the market, and the like. It is designed to collect dioxin.

In the water quality inspection device 23, the sample collection ports 23 a and 23 b are connected to the inflow port 22 in side and the outflow port 22 of the water treatment apparatus 22 through sample collection pipes 33 a and 33 b.
In addition to being connected to the out side, the outflow port 23c of the inspection device 23 joins the closed circulation system 20 downstream from the sample collection pipe 33b via the junction pipe 33c.
Further, the sampling pipes 33a and 33b are provided with sample water inlets 34a and 34b formed by faucets or the like, so that an appropriate amount of a sample for water quality inspection can be taken out as needed.

As the water quality inspection device 23, for example, a device in which a computer is connected to an ultraviolet-visible spectrophotometer is used, and based on data of a light absorption spectrum output from the ultraviolet-visible spectrophotometer every month, a computer is used. so,
Alkyl mercury compounds (R-Hg), mercury or its compounds (Hg), cadmium or its compounds (Cd), lead or its compounds (Pb), organic phosphorus compounds (OP), hexavalent chromium compounds (Cr ⁶⁺ ), Arsenic or its compound (C
N), PCB, organic chlorine-based compound (O-Cl), copper or its compound (Cu), zinc or its compound (Zn), fluoride, trichloroethylene, tetrachloroethylene,
The types and concentrations of harmful substances such as dioxins are read, and the data is automatically transferred to a management department such as a central management center remote from the waste disposal site 1.

The above is an example of a waste disposal site used in the method of the present invention, and the method of the present invention will be described next.
First, a waste landfill hole 2 is dug, and the impermeable sheet 3
, And water collecting treatment is performed. A water collecting pipe 5 is piped to the bottom of the waste landfill hole 2, and the gravel 11 is spread in layers until the water collecting pipe 5 is filled. At this time, the water collecting pipe 5 is made to penetrate the water impermeable sheet 3, and in this state, the water impermeable sheet 3 and the water collecting pipe 5 are brought into close contact with each other so as not to leak water. Next, every time the waste is dumped into the landfill hole 2 in a layered manner and deposited to a predetermined depth,
The hydration pipe 6 and the air supply pipe 7 are installed horizontally,
Gravel 11 is layered until these tubes 6 and 7 are filled.
Since the pipes 5, 6, and 7 are thus buried in the gravel 11, the perforations of the pipes 5, 6, and 7 are not blocked by the waste. During this time, it is preferable to prevent rainwater from entering by temporarily installing a tent warehouse or the like and covering the waste landfill hole 2 with a roof.

When the landfill with the waste is completed, a water-blocking material 9 is covered so as to cover the sedimentary waste 4, and the water-blocking material 9 is pierced through the respective pipes 6 a, 7 a. The water-blocking material 9 and the pipes 6a, 7a are brought into close contact with each other so as not to leak, and a closed circulation system 20 from the water collecting pipe 5 to the water supply pipe 6 is formed. A water quality inspection device 23 and the like are provided.

Here, when the pumps 26 and 27 and the compressor 12 are started, water is supplied from the water supply pipe 6 to the accumulation waste 4, and air is supplied from the air supply pipe 7. The leachate leached from the sedimentary waste 4 is collected by the water collection pipe 5, and after large trash is removed by the strainer 21,
It flows into the water treatment device 22. In the water treatment device 22, first, waste oil is removed by the filter 28, then, metal ions contained in the leachate are removed by adsorption by the metal adsorption device 29, and then dioxin contained in the leachate is removed by the dioxin removal device 30. Collected.

As described above, the leachate purified by removing the waste oil, metal, and dioxin by the water treatment device 22 is temporarily stored in the treated leachate storage tank 24,
It is circulated and supplied again to the deposited waste 4 via the water supply pipe 6 by the pump 27. Therefore, even if the waste landfill hole 2 is sealed with the water-blocking sheet 3 and the water-blocking material 9, water and air can be supplied to the deposited waste 4 through the water supply pipe 6 and the air supply pipe 7. As a result, the chemical decomposition effect of air and water on the sedimentary waste and the biological decomposition effect of microorganisms are promoted.

The water treatment device 22 provided in the closed circulation system 20 includes a metal adsorption device 29. When circulating the leachate, the leachate leached from the sediment waste 4 contains harmful metals. However, since it is possible to supply clean water from which the water has been removed, microorganisms (activated sludge) contained in the waste are not killed. There is no loss.

Also, when harmful substances such as waste oil and dioxin are contained in the sedimentary waste 4, these are carried to the water treatment device 22 via leachate and collected,
The harmful substances contained in the sedimentary waste 4 gradually decrease and become harmless by long-term operation. Further, the leachate leached from the sedimentary waste 4 is purified by the water treatment device 22 of the closed circulation system 20, and then circulated and supplied to the sedimentary waste 4 again to form a complete closed loop. Since the leachate is not discharged to the outside, even if the leachate contains harmful organic substances that cannot be removed by the water treatment device 22, it does not pollute the surrounding environment. In addition, these harmful organic substances are oxidized by a natural purification action by supplying water and air, and gradually become harmless.

In this example, the untreated leachate flowing into the water treatment device 22 and the treated leachate flowing out from the water treatment device 22 are introduced into the water quality inspection device 23, and harmful substances contained in the leachate are removed. The type and concentration are measured periodically, for example, once a month, and the data is automatically transferred to a management department such as a central management center remote from the waste disposal site 1, for example. Therefore, when managing the waste disposal site 1, the waste disposal site 1 is often installed in a mountainous area away from the town, but automatically without going to the site and conducting a boring survey. The degree of purification of the deposited waste 4 and the processing capacity of the water treatment device 22 can be ascertained based on the data of the transferred leachate water quality test results.

For example, it is possible to judge how much the sedimentary waste 4 has been purified by comparing the water quality test result of the untreated leachate flowing into the water treatment device 22 with the water quality test result measured previously. it can. As a result, it is possible to know when the purification is most promoted throughout the year. If the water supply amount and the air supply amount are adjusted to meet the temperature and humidity conditions at that time, the purification will be further improved. Can be promoted. Further, by comparing the quality of the untreated leachate with the quality of the treated leachate,
Can be monitored. For example, when the difference between the metal concentrations contained in the untreated leachate and the treated leachate has decreased, it is considered that the treatment capacity of the metal adsorption device 29 has decreased, and the treatment tower 31 is filled. The existing chelating agent or chelating resin may be replaced.

When the water quality inspection device 23 breaks down, for example, the sample intake ports 34a and 34b
Just take a sample, take it back and analyze it,
Even in this case, the degree of purification and the treatment capacity of the water treatment device 22 can be known very easily and easily as compared with the case of performing a boring survey.

FIG. 2 is an explanatory view showing another waste disposal site used in the method of the present invention. 1 are denoted by the same reference numerals, and detailed description is omitted. The waste disposal site 41 of this example is of a type in which the top surface opening of the landfill hole 2 that has been landfilled is not covered with a water-blocking material, but is simply covered with soil such as clay or the like, which is difficult to pass water. After the landfill is completed, for example, a tree or the like is planted thereon so that it can be used as a park. The bottom and side surfaces of the waste landfill hole 2 are constructed of a concrete impermeable wall 43 and are impermeable to water.

Further, in the sediment waste 4 dumped in the landfill hole 2, a water collection pipe 5 that collects seepage water escaping from the sedimentary waste 4, and a leachate collected by the water collection pipe 5. A water supply pipe 6 for circulating water to the sedimentary waste 4 is buried. Then, the leachate collected by the water collection pipe 5 is temporarily circulated to the closed circulation system 20 for circulating the leachate through the water supply pipe 6 into the sedimentary waste 4 without discharging the leachate to the outside. A pit 44 having a predetermined capacity to be stored and a water treatment device 22 for removing harmful substances contained in the leachate stored in the pit 44 are provided.

The pit 44 is formed next to the landfill hole 2 and is dug down to a position lower than the outlet of the water collecting pipe 5. The capacity is determined by the capacity of the waste landfill hole 2 and the weather conditions in the area where the waste landfill hole 2 is constructed. For example, when the expected maximum rainfall falls in anticipation of the safety factor, one of the rainwater Even if the part permeates into the waste landfill hole 2 and the amount of seepage water from the landfill hole 2 increases, it is designed to be able to store the water sufficiently.
An exhaust pipe (not shown) is formed in the pit 44 and the treated effluent water storage tank 24 so that the vapor evaporated in the tank can be exhausted to the outside without rainwater flowing directly.

According to this, the leached water leached from the sedimentary waste 4 is first temporarily stored in the pit 44, purified by the water treatment device 22, and stored in the treated effluent water storage tank 24. After being stored, it is circulated and supplied to the deposited waste 4 again. When the rainfall increases, the amount of leached water also increases, and the pit 44 and the treated leached water storage tank 2
Although the water level of No. 4 gradually rises, when the weather is fine, the effluent water evaporates and the water level decreases, so that the effluent water does not overflow outside throughout the year.

[0033]

As described above, according to the present invention, even if harmful substances such as heavy metals and dioxins are contained in the buried sediment waste, the effluent is interposed in the closed circulation system. By purifying with a water treatment device, it is possible to reduce the concentration of harmful substances contained in sedimentary wastes through leachate without killing microorganisms in the wastes, and to gradually detoxify the wastes. In addition, there is an excellent effect that the degree of detoxification of sedimentary waste can be easily monitored without performing a boring survey by performing a water quality inspection of the leached water.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a waste disposal site used in the method of the present invention.

FIG. 2 is an explanatory view showing another waste disposal site used in the method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Waste disposal site 2 ... Waste landfill hole 4 ... Sedimentary waste 5 ... Water collecting pipe 6 ... Water supply pipe 7 ... Air supply pipe 20 ... Closed circulation system DESCRIPTION OF SYMBOLS 21 ... Strainer 22 ... Water treatment apparatus 23 ... Water quality inspection apparatus 28 ... Filter (waste oil removal apparatus) 29 ... Metal adsorption apparatus 30 ... Dioxin removal apparatus 31 ... Treatment tower 34a , 34b ・ ・ ・ Sample intake 41 ・ ・ ・ Waste disposal site 44 ・ ・ ・ Pit

Claims (3)

[Claims] 1. A wastewater collection pipe (5) for collecting leachate from a sedimentary waste (4) and a sedimentary waste (4) in a waste landfill hole (2) having an inner surface subjected to a water shielding treatment. A landfilling step of burying a hydration pipe (6) for replenishing moisture, and an air supply pipe (7) for blowing air supplied from the outside into the deposited waste (4) while burying the waste in the landfill; The effluent water collected by the water collection pipe (5) buried in the sedimentary waste (4) by the process is supplied to the water treatment device (22) without flowing out to the outside, and the water treatment device (22) (20) a closed circulation system (20) for returning the treated leachate purified from the water supply pipe (6) into the landfill hole (2).
And circulating the leachate through the closed circulation system (20) until the leachate is rendered harmless based on the results of the water quality test of the untreated leachate flowing into the water treatment device (22). And (4) a purification step of performing a purification treatment. 2. A wastewater collection pipe (5) for collecting leachate from a sedimentary waste (4) and a sedimentary waste (4) in a waste landfill hole (2) having an inner surface subjected to a water shielding treatment. A landfilling step of burying a water supply pipe (6) for supplying moisture, and an air supply pipe (7) for blowing air supplied from the outside into the deposited waste (4) while burying the waste in the landfill; The effluent water collected by the collecting pipe (5) buried in the sedimentary waste (4) by the process is supplied to the water treatment device (22) without flowing out to the outside, and the water treatment device (2
A closed circulation system (20) for returning the treated leachate purified in 2) from the water supply pipe (6) to the landfill hole (2).
And a purifying step of purifying the sedimentary waste (4) by circulating the leachate in the closed circulation system (20). 3. A waste oil removing device (28) for removing waste oil contained in leachate, and a metal adsorption device (29) for selectively adsorbing and removing metal ions contained in leachate. 3) and a dioxin removing device (30) for collecting dioxin contained in the leachate.
Waste disposal method as described.