JP2000237735A - Reclaimed ground treatment system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly start the use of the site of reclaimed ground in the case that alkaline components or acidic components leach from the reclaimed ground. SOLUTION: This reclaimed ground treatment device 1 is provided with a neutralizing gas tank 2 being a neutralizing gas feeding means for feeding neutralizing gas, an air intake pump 4 being an air intake means connected to the neutralizing gas tank, and a discharge pipe 3. Carbon dioxide (gaseous CO2) being the neutralizing gas is fed from the neutralizing gas tank 2, and also the fed carbon dioxide is forcibly fed to the discharge pipe 3 through the air intake pump 4. Many discharge holes 5 for discharging the neutralizing gas are formed in the discharge pipe 3 and are laid on the bottom surface of a storing space 11 of reclaiming material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for treating a landfill board made of an acidic or alkaline landfill material.

[0002]

2. Description of the Related Art When forming a landfill board using a landfill material,
If the landfill material is a material exhibiting acidity or alkalinity, an acidic component or an alkaline component may flow into the groundwater system together with rainwater.

[0003] Therefore, when the landfill site is, for example, an industrial waste disposal site, a drainage structure is provided on the bottom of the disposal site, and a drainage / drainage structure is provided at the bottom of the drainage site. The leachate collected at the site is pumped up, neutralized, and then discharged to prevent the leachable components from the landfill material from diffusing into the environment.

[0004] On the other hand, the land where the landfill operation has been completed is a valuable land resource, and it is desirable to use the land appropriately and effectively. However, in order to use the land, the settlement and strength of the landfill, Needless to say, it is necessary to pay sufficient attention to the composition and change of the leachate, the quality and quantity of the leachate from the landfill material and the change thereof.

[0005]

Here, for example, when coal ash generated from a thermal power plant is a landfill material, highly alkaline leachate is generated with the infiltration of rainwater. Therefore, even after the landfill disposal is completed, pump-up from the drainage system and neutralization discharge work must be continued for a long time until the pH of the leachate clears a predetermined drainage standard, for example, 5.8 to 8.6. However, there has been a problem that the use of the former site is delayed or the use of the former site becomes substantially difficult.

The present invention has been made in view of the above-mentioned circumstances, and provides a landfill disposal system capable of promptly starting to use a former site when an alkaline component or an acidic component leaches from the landfill. The purpose is to provide.

[0007]

To achieve the above object, a landfill disposal system according to the present invention comprises a neutralizing gas supply means for supplying a neutralizing gas, Air supply means connected to the sum gas supply means for supplying the neutralizing gas to the landfill material.

Further, in the landfill disposal system according to the present invention, the landfill material is coal ash, and the neutralizing gas is carbon dioxide.

Further, the landfill disposal system according to the present invention is provided with a collecting and exhausting means for collecting the neutralizing gas which has passed through the landfill material.

[0010] In the landfill disposal system according to the present invention, the landfill material is supplied with neutralizing gas supplied from the neutralizing gas supply means via the supply means.

With this configuration, the supplied neutralizing gas neutralizes the landfill material while passing through the landfill material.

As the landfill material, any material that oozes out an alkali component or an acidic component by itself or in the form of being entrained by the infiltrated rainwater with the infiltration of the rainwater can be used. May be appropriately selected according to the pH of the landfill material, but if the landfill material is coal ash and the neutralizing gas is carbon dioxide (carbon dioxide gas), even if a large amount of neutralizing gas is supplied to the landfill material, Since the pH of the landfill does not significantly shift to the acidic side, it is possible to prevent the adverse effects of soil acidification beforehand, and there is almost no environmental concern even if excess carbon dioxide is released into the atmosphere. Therefore, there is no need to provide a collection and exhaust unit. In addition, since the acidity of carbon dioxide is relatively weak, the state in which iron, aluminum, or heavy metals are eluted from coal ash is also prevented.

With respect to the air supply means, if the neutralizing gas ejected therefrom passes through the landfill material, the position, shape or arrangement of the air supply means is arbitrary. If the collecting and exhausting means for recovering the neutralizing gas that has passed through the landfill material is used together, the neutralizing gas is synergized with the gas supply force by the gas supply means and the gas extraction force by the gas collecting and discharging means. In addition to allowing the gas to pass smoothly through the soil, the collected and exhausted neutralizing gas and reactant can be treated as necessary, and then released to the atmosphere.

The structure and shape of the collecting / exhausting means and the relative positional relationship with the air supply means are arbitrary as long as a landfill material exists between them. A large number can be buried vertically to provide air supply means and collection / exhaust means.

[0015]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a landfill board processing system according to an embodiment of the present invention. It is to be noted that the same reference numerals are given to components and the like that are substantially the same as those in the conventional technology, and description thereof is omitted.

FIG. 1 is an overall view showing a landfill board processing system according to this embodiment. As you can see in the figure,
The landfill disposal system 1 according to the present embodiment includes a neutralizing gas tank 2 as a neutralizing gas supply unit for supplying a neutralizing gas, an air supply pump 4 as an air supply unit connected to the neutralizing gas tank, and And a discharge pipe 3.

Carbon dioxide (carbon dioxide) as a neutralizing gas is supplied from the neutralizing gas tank 2, and the supplied carbon dioxide is pressure-fed to the discharge pipe 3 via the air supply pump 4. It is supposed to be.

A large number of discharge holes 5 for discharging the neutralizing gas are formed in the discharge pipe 3 and are laid on the bottom of the space 11 for storing the landfill material. The discharge pipe 3 can be formed of, for example, a hollow pipe made of vinyl chloride.

In order to construct a landfill disposal system 1 according to the present embodiment, as shown in FIG. 2, a discharge pipe 3 is previously laid on a water shield 12 installed on the bottom of a storage space 11. Then, the coal ash 13 as a landfill material is landfilled.

Here, the water shield 12 may be made of, for example, reinforced concrete, a waterproof sheet, or the like. Further, the discharge pipe 3 is preferably laid so that the discharge hole 5 faces upward.

When the construction of the processing system 1 is completed in this way, carbon dioxide from the neutralizing gas tank 2 is supplied to the coal ash 13 as landfill material through the discharge pipe 3.

In this way, the supplied carbon dioxide contains alkaline components such as alkaline earth metals such as calcium ions, sodium ions and potassium ions and alkali metal ions eluted from the coal ash while passing through the coal ash 13. Releases and then is released from the earth's surface to the atmosphere.

Here, calcium ions contained in the coal ash 13 in large amounts become calcium carbonate by the reaction with carbon dioxide and remain in the soil. However, since such calcium carbonate is hardly soluble, it is difficult to diffuse into the groundwater system. No need to worry.

When supplying carbon dioxide into the coal ash 13, it is preferable to appropriately adjust the gas supply rate while monitoring the pH change and the like of the coal ash. In addition, if the permeability coefficient of the landfill site decreases due to the generation of calcium carbonate due to the supply of carbon dioxide, the supply pressure and the like may be appropriately increased.

Next, the operation and effect of the landfill disposal system according to the present embodiment have been confirmed by experiments, and the outline thereof will be described below.

First, 2.5 liters of water and 30 liters of carbon dioxide gas (about 6% by mass) were added to 1 kg of coal ash, and the pH changed as shown in Table 1. The pH when no carbon dioxide was added was 12.6.

[0027]

[Table 1]

As can be seen from the table, the pH significantly decreased, and a clear neutralizing effect was observed. Further, pH 5.8 to 8.6, which is a drainage standard, was satisfied.

When 1 liter of water and 10 liters of carbon dioxide (about 2% by mass) were added to 1 kg of coal ash, the pH dropped to 7.5 after one day.

As described above, according to the landfill disposal system 1 according to the present embodiment, the carbon dioxide as the supplied neutralizing gas passes through the coal ash 13 as a landfill material while the carbon ash is supplied. Since the alkaline component eluted from the soil is neutralized, the landfill made of coal ash 13 quickly changes from a highly alkaline ground to a neutral ground.

Therefore, it is possible to start using the former land after the completion of the landfill work earlier than in the conventional case where the neutralization of the landfill is entrusted to rainwater infiltration.

Further, according to the landfill disposal system 1 according to the present embodiment, the landfill using coal ash 13 can be neutralized quickly and at low cost. The coal ash generated can be actively used as landfill material for landfill.

According to the landfill disposal system 1 according to this embodiment, the neutralizing gas is carbon dioxide.
Not only can the chemical cost required for neutralization be reduced, but even if a large amount is supplied to the coal ash 13 as a landfill, the pH of the landfill does not significantly shift to the acidic side. Since the pH does not fall below about 5.5, the adverse effects of soil acidification can be prevented. Further, even if the excess carbon dioxide is released into the atmosphere, there is almost no environmental concern, so there is no need to provide a collection and exhaust means. In addition, since the acidity of carbon dioxide is relatively weak, it is possible to prevent iron, aluminum or heavy metal from being eluted from the coal ash 13 and flowing into the groundwater system.

Further, according to the landfill disposal system 1 according to the present embodiment, carbon dioxide reacts with calcium ions in the coal ash 13 to produce calcium carbonate. There is no danger of inflow into the system, and the formation in the soil particle gap of the ground contributes to a reduction in the permeability coefficient and an increase in strength of the landfill.

In the present embodiment, the carbon dioxide supplied into the coal ash 13 is naturally released from the ground surface. However, as shown in FIG. A large number of the bottomed porous tube 41a, the bottomed porous tube 41b as the collecting and exhausting means, and the exhaust pump 42b may be vertically buried in the landfill made of coal ash 13 at opposing positions.

According to this configuration, carbon dioxide, which is a neutralizing gas, can be smoothly passed through the coal ash 13 by the synergistic effect of the gas supply force of the gas supply means and the gas extraction force of the gas collection and exhaust means. Becomes

In this embodiment, carbon dioxide is used as a neutralizing gas for neutralizing the coal ash 13. However, any chemical may be used as long as it has a neutralizing ability and can be vaporized at about room temperature. You may.

In the present embodiment, an example has been shown in which coal ash, which is an alkaline landfill, is neutralized with an acidic neutralizing gas. Needless to say, it is good.

In the present embodiment, it is assumed that the present invention is applied to a waste disposal site installed in a mountainous area or the like. However, the present invention is not limited to the location conditions and is not limited to the waste disposal site in the first place. However, it goes without saying that the present invention may be applied to landfill sites constructed along the coast or offshore.

[0040]

As described above, according to the landfill disposal system according to the first aspect of the present invention, the landfill quickly changes from an alkaline or acidic ground to a neutral ground. Therefore, the use of the site after the completion of the landfill work can be started earlier as compared with the conventional method in which the neutralization of the landfill is entrusted to rainwater infiltration.

Further, according to the landfill disposal system of the present invention, the landfill using coal ash generated from the thermal power plant can be neutralized quickly and at low cost. First, even if a large amount of carbon dioxide, which is a neutralizing gas, is supplied to the landfill, the pH of the landfill does not significantly shift to the acidic side, so that adverse effects due to soil acidification can be prevented. In addition, there is almost no environmental concern even if surplus carbon dioxide is released into the atmosphere, so there is no need to provide collection and exhaust means.
Since the acidity of carbon dioxide is relatively weak, there is also an effect that elution of iron, aluminum or heavy metal from coal ash is prevented beforehand.

According to the third aspect of the present invention, the neutralizing gas is removed from the soil by the synergistic action of the gas supply force of the gas supply means and the gas extraction force of the gas collection and exhaust means. In addition to allowing the gas to pass smoothly, the neutralized gas and reactant collected and exhausted are once processed and released to the atmosphere without affecting the environment.

[0043]

[Brief description of the drawings]

FIG. 1 is an overall view showing a landfill board processing system according to an embodiment.

FIG. 2 is a sectional view showing the operation of the landfill board processing system according to the embodiment.

FIG. 3 is a sectional view of a landfill board processing system according to a modification.

[Explanation of symbols]

DESCRIPTION OF REFERENCE NUMERALS 1 Landfill disposal system 2 Neutralizing gas tank (neutralizing gas supply means) 3 Discharge pipe (air supply means) 4 Air supply pump (air supply means) 13 Coal ash (landfill material) 11 Storage space 41a Bottomed porous pipe ( Air supply means) 42a Air supply pump (air supply means) 41b Perforated pipe with bottom (collection / exhaust means) 42b Exhaust pump (collection / exhaust means)

Claims (3)

[Claims] 1. A landfill comprising a neutralizing gas supply means for supplying a neutralizing gas, and an air supply means connected to the neutralizing gas supply means for supplying the neutralizing gas to a landfill material. Ground treatment system. 2. The landfill disposal system according to claim 1, wherein said landfill material is coal ash, and said neutralizing gas is carbon dioxide. 3. The landfill disposal system according to claim 1, further comprising a collection / exhaust means for collecting neutralized gas passing through the landfill material.