JPH08128068A - Treatment system of dredged mud - Google Patents

Abstract

PURPOSE: To provide a dredged mud's processing system that is unnecessary to have an extensive site for a coagulating sedimentation basin, and even in the case where the dredged mud is liable to emit a bad smell, it can be processed with a mechanical hydroextractor as preventing the spreading of its odor easily. CONSTITUTION: This processing system 3 is composed of a mud storage tank 4, storing high density dredged mud made up of checking excessive water suction to the utmost, fed out of a dredger 1 and controlling a quantity and density of the dredged mud, a slurry tank 7, stirring the dredged mud to be fed out of this mud storage tank 4 together with a coagulant and coagulating and settling the mud content, and a dewatering device 10 dewatering this coagulated and settled mud content. A series of operations ranging from the storage of the high density dredged mud to the watering process in this dewatering device 10 by these devices can be done in a hermetically sealed circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a treatment system for dredged mud, and more particularly to a treatment system for soft mud such as dredged sludge.

[0002]

2. Description of the Related Art Soft mud such as sludge deposited on the sea bottom contains a large amount of water, and it is not easy to separate the water from the mud. Therefore, even if such softened mud is dredged, it is difficult to use it as it is as a material for civil engineering work such as landfill, or to discard it. A method is adopted in which it is dried or accumulated in landfills, dehydrated by driving vertical drains, and then reused as dumped or landfill.

Further, as a method of treating such dredged mud,
In addition to the above-mentioned sun drying, etc., conventionally known,
A method of using a mechanical dewatering device as a muddy water treatment facility, which is used in construction sites such as muddy water shield construction method and underground continuous wall construction method, can be considered, but it is necessary to simply treat a large amount of dredged sand with this equipment. For example, a vast coagulation sedimentation basin is set up on land near the dredging construction site, and a large amount of dredged mud is fed into this coagulation sedimentation basin from, for example, a pump-type dredger. After the separation, the high-concentration dredged mud is fed to the slurry tank together with the flocculant to stir and settle the mud, and the sedimented mud is dehydrated by the mechanical dehydrator. There is a need.

[0004]

However, in the method for treating the dredged mud soil by the mechanical dewatering device considered from the above-mentioned prior art, in the land near the dredging site, a cohesive sedimentation basin with a vast area for spillage treatment is provided. However, there is a problem that it is difficult to secure the site.

Further, since a large area of the coagulation sedimentation basin is open above, dredged mud may give off a bad odor due to harmful components in the sludge, for example, which may adversely affect the surrounding environment. There was a problem that there is.

Therefore, the present invention has been made in view of the above problems, and does not require a vast site for the coagulating sedimentation pond, and even if the dredged sand is apt to give off a bad odor, An object of the present invention is to provide a treatment system for dredged mud using a mechanical dewatering device, which can easily prevent the diffusion of the odor.

[0007]

The present invention has been made to achieve the above object, and its gist is to store the dredged mud fed from a dredging ship and manage the amount and concentration of the dredged mud. And a slurry tank for agitating the dredged mud sent from the mud tank with a flocculant to concentrate and settle the mud content, and a dehydration treatment device for dewatering the concentrated and sedimented mud content. It is a treatment system for dredged mud characterized by the fact that

[0008]

According to the dredged mud treatment system of the present invention, in recent years, a pump-type dredger called a high-concentration dredging vessel having a function capable of feeding the dredged mud at a high and stable concentration is provided. Since it is widespread, for example, by using such a dredging ship, it is possible to easily feed highly concentrated dredged mud with minimal intake of spilled water to the mud storage tank, and also to send dredging. By removing excess water and reducing the volume of the mud, the mud can be easily fed and stored in the mud tank as a closed space without requiring a large-scale storage space such as a coagulation sedimentation basin.

The dredged mud sent from the dredger is
By being stored in the mud storage tank as a closed space, the subsequent coagulation processing in the slurry tank and the dehydration processing in the dehydration processing apparatus can be performed in a so-called series of closed circuits, which enables the operation from the dredged mud soil. It is possible to easily prevent the emission of odors, and it is also possible to easily make the dredged mud soil harmless by mixing the deodorant and the elution control material.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is an explanatory diagram showing an outline of the overall configuration of a dredged mud treatment system 3 according to this embodiment.

That is, the processing system 3 of this embodiment
Is mainly used to store high-concentration dredged mud sent from the dredger 1 and manage the amount and concentration of this dredged mud, and to agglomerate the dredged mud sent from this mud tank 4. The slurry tank 7 is configured to stir together with the agent to coagulate and settle the mud content, and the dewatering apparatus 10 to dehydrate the coagulated and settled mud content in the slurry tank 7.

The dredger 1 is, for example, a so-called high-concentration dredger, which dredges dredged mud such as sludge containing a large amount of water at a high concentration while suppressing intake of excess water, and pumps it. Thus, it has a function of feeding from the dredging site E1 in the sea area to the processing system 3 provided on the land E near the dredging site E1 through the mud transport pipe 2.

The highly concentrated dredged mud sent from the dredger 1 is first stored in the mud tank 4 in the treatment system 3. That is, the mud storage tank 4 includes a closed tank body 4a and a stirring blade 4c provided inside the tank body 4a.
In addition to having a drive device 4b for driving the, and the like, it has a function of accommodating the dredged mud without managing the odor and managing the amount and concentration of the stored mud. In other words, in order to control this concentration, use a device that measures the specific gravity, which is also used at shield sites and automatically measures the concentration, periodically measures the concentration, gives instructions to the dredger, The amount of flocculant is automatically added according to the concentration.

The capacity of the tank body 4a of the mud storage tank 4 is set in accordance with the amount of dredged mud soil to be fed with a high concentration, that is, the dredging capacity of the dredger 1, but the dredged mud soil to be stored is Supplies a high concentration while suppressing the suction of extra water as much as possible, so that it is possible to construct the mud storage tank 4 as a closed structure having a size that is economically viable. Also, the mud tank 4
A plurality of can be installed according to the dredging capability of the dredger 1.

Then, the mud is temporarily stored in the mud tank 4,
The dredged mud whose concentration is controlled is then transferred from the lower part of the tank body 4a to the slurry tank 7 by the pump 6 via the mud feed pipe 5. Here, the slurry tank 7 is a hermetically sealed tank main body 7a similar to the mud storage tank 4, and a drive device 4b for driving a stirring blade 7c provided inside the tank main body 7a.
And so on. Then, a coagulant is added to the dredged mud transferred to the inside of the mud transfer pipe 5 or in the mud storage tank 4, and is agitated and mixed by the agitating blades 7c to make the mud content of the dredged mud flock. At the same time, they are aggregated and settled at the bottom of the slurry tank. In addition, in the dredged mud,
In addition to the flocculant, a deodorant and an elution inhibitor for removing harmful metal ions are added, and these can be used to make the dredged mud soil harmless. The slurry tank 7
As with the mud storage tank 4, it is desirable to provide a plurality of them as needed.

Here, the coagulant added to the dredged mud is
Various known flocculants can be used, but preferably, for example, a 10% solution obtained by dissolving or suspending PAC (polyaluminum chloride) or aluminum sulfate (sulfuric acid band) in water is used as a solid matter 1t in mud. However, it is desirable to add 10 to 80 kg. When such a coagulant is added, the fine particles in the mud water are secondarily coagulated into large particles, which promotes the sedimentation of the mud.

As the deodorant added to the dredged mud, various known deodorants can be used, but preferably, for example, when the causative agent of odor is weakly acidic hydrogen sulfide. Since volatile components can be removed by making the pH alkaline, cement or slaked lime is added, for example. The addition amount is determined by judging the properties of the dredged mud with a pH meter or the like. When the dredged mud is not desired to be alkaline, it can be deodorized by adding hydrogen peroxide solution to oxidize the sulfur content.

Further, as the elution inhibitor added to the dredged mud, various kinds of eluents which differ depending on the metal ions to be eluted can be used. For example, for iron, manganese, etc., slaked lime slurry is effective. is there.

Since the coagulant, deodorant, and dissolution inhibitor interact with each other depending on the liquidity and the reactivity of each drug, when a plurality of substances are used at the same time, the components should be selected. It is also necessary to pay attention to the order of addition.

Then, in the slurry tank 7, the mud content of the dredged mud coagulated and settled is allowed to stand and then the tank body 7
A pump 9 is transferred from a lower part of a through a mud pipe 8 to a mechanical dewatering apparatus 10. Also, the tank body 7a
The clear water generated in the upper part of the river is returned to the sea as extra water.

The dehydration treatment apparatus 10 is a known one such as a roll press or a filter press used for treating the muddy water discharged by the shield construction method, the continuous underground wall construction method or the like, and is a combination of a filtration apparatus and a centrifuge. The treated soil A that has been filtered and dehydrated in this device is sequentially discharged to the lower part of the dehydrator 10, and is conveyed to the discharge position [11] by the belt conveyor 10a located there and accumulated there. At the same time, it is carried out to the landfill site and the dump facility.

That is, according to the dredged mud treatment system 3 of this embodiment, the dredged mud fed from the dredging ship 1 does not require a large-scale storage space such as a coagulation sedimentation basin or the like to suck in residual water. The dredged mud that was stored in the mud tank 4 as a closed space in a highly concentrated state that was suppressed as much as possible and that was fed from the dredging ship was subjected to a series of operations up to the dehydration treatment in the dehydration treatment equipment in a closed circuit. It is possible to prevent the deterioration of the surrounding environment due to the emission of odor from the dredged mud and the like.

[0023]

As described in detail above, the treatment system for dredged mud according to the present invention aggregates the dredged mud sent from the dredger and the storage tank for storing the dredged mud fed from the dredger. It is composed of a slurry tank that agitates with the agent to coagulate and settle the mud, and a dewatering device that dehydrates the coagulated and sedimented mud, without the need for a vast site for the coagulating sedimentation pond and dredging. Even if the earth and sand easily emits a bad odor, it is possible to easily treat the dredged mud using a mechanical dewatering device while easily preventing the odor from diffusing.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a dredged mud treatment system according to an embodiment of the present invention.

[Explanation of symbols]

 1 Dredger 3 Dredging Mud Treatment System 4 Mud Storage Tank 7 Slurry Tank 10 Dehydration Treatment Equipment

Claims (1)

[Claims] 1. A mud tank for storing the dredged mud sent from a dredging ship to control the amount and concentration of the dredged mud, and stirring the dredged mud sent from the mud tank with a coagulant. A treatment system for dredged mud, comprising a slurry tank for concentrating and settling mud and a dewatering device for dewatering the concentrated and settling mud.