JP2003181465A - Engineering method for decontaminating water bottom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an engineering method for decontaminating a water bottom which can treat not only earth, sand, sludge or the like deposited at the water bottoms of a harbor, a lake, a marsh, a river, a pond, a canal or the like but also algae, suspended solids floating in water by coagulation and precipitation, which does not need scrapping precipitated solids or the like as industrial waste again and further which dispenses with treatment of separated water. <P>SOLUTION: Muddy water at the water bottom is pumped up on a work ship 2 floated in a water area to be treated such as the pond 1, powdery inorganic coagulant is added to the muddy water in an agitating tank 6, is mixed and then the muddy water is returned as it is to the water area to be treated. Otherwise a circulating water stream circulating in the water area is formed in the water area to be treated and the coagulant is added to the circulating water stream. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to sludge, sludge, sedimented algae such as water and water-blooming algae suspended on the bottom of water such as lakes, ponds, rivers and harbors, and suspended solids (S
S), a pollutant, an offensive odor-causing substance, and the like are aggregated and separated to purify the water bottom and improve the clarity of the water, and in particular, the industrial waste is not generated during the treatment.

[0002]

2. Description of the Related Art In ports, lakes, lakes, rivers, ponds, excavations, etc., the depth of water and the prevention of offensive odors are secured by dredging and removing sediment, dust, and sludge that accumulate on the bottom of the water over time. , Protection of aquatic organisms has been made. The dredged bottom mud generated during this dredging is in a semi-solid state with a high water content and must be disposed of.

As one method of disposing such dredged bottom mud, the dredged bottom mud is temporarily stored in a sedimentation tank or the like, and a sulfuric acid band, a polymer system such as PAC (polyaluminum chloride) or polyacrylate is added to the dredged bottom mud. There is a method in which various coagulants such as a coagulant are added, and the mixture is stirred and mixed to coagulate the solid content in the mud for precipitation separation, and the supernatant water is returned to a port or the like, and the precipitate is discarded as industrial waste.

However, in this disposal method, depending on the type of the coagulant used, the pH of the supernatant water tends to the acid side or the alkali side, which needs to be neutralized.
There are problems that it takes a long time to precipitate the solid content, it takes a long time to process, and it is actually difficult to dispose of the precipitate as industrial waste.

Although the precipitate may be dehydrated in order to reduce the volume of the precipitate, the dehydrated separated water contains pollutants, and the waste water treatment of this separated water is required again. Further, the conventional dredging method has a disadvantage that algae suspended in water, suspended solids and the like are not removed, and the water is not clarified in a turbid state.

[0006]

Therefore, the object of the present invention is to aggregate and settle not only sediment, sludge, sludge, etc. accumulated on the bottom of the water, but also algae suspended in water, suspended solids, etc. The present invention is to obtain a water bottom purification method in which the precipitated solids and the like do not have to be discarded as industrial waste again and the secondary treatment of separated water is unnecessary.

[0007]

In order to solve such a problem, the invention according to claim 1 pumps up mud water at the bottom of a work vessel floated in a water area to be treated, and adds a coagulant thereto.
This is a water bottom purification method characterized by mixing and returning this muddy water as it is to the water area to be treated. The invention according to claim 2 is a water bottom purification method characterized in that a circulating water flow that circulates in the water body to be treated is formed, and a coagulant is added to the circulating water flow.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail based on embodiments. FIG. 1 shows an example of the water bottom purification method of the invention according to claim 1, wherein the water area to be treated is an example of a pond. One or more work boats 2 are floated on this pond 1. The work boat 2 is a pier or the like, and a suction device 3, a suction pump 4, a flocculant charging device 5,
The stirring tank 6, the generator 7, etc. are mounted.

A suction pipe 8 extending to the bottom of the pond 1 is connected to the suction device 3. A cage 9 is attached to the tip of the suction pipe 8 so that the suction pump 4 operates to suck the sediment on the pond bottom and the water around it (hereinafter referred to as muddy water) by the suction device 3. Has become.

The muddy water sucked by the suction device 3 is sent to the stirring tank 6 through the pipe 10 in a turbulent state. The stirring tank 6 is a tank having a normal stirring blade and a capacity of about 1 to 5 cubic meters, and the like, into which the powdery coagulant supplied from the coagulant feeding device 5 is added. .

The coagulant feeding device 5 is provided at the upper part of the stirring tank 6, and a storage tank for storing the powdery coagulant and a screw for quantitatively feeding the coagulant falling from the bottom of the storage tank. A feeder such as a feeder is provided, and the amount of the flocculant added to the stirring tank 6 can be controlled by a control signal from the controller.

The muddy water to which the flocculant has been added and stirred in the stirring tank 6 is re-drained from the discharge pipe 11 connected to the discharge port at the upper portion of the stirring tank 6 as new muddy water is sucked from the bottom of the pond. It is set back to 1. As the aggregating agent used here, a powdery one mainly composed of inorganic silica and having a high aggregating rate in a neutral region is used.
The generator 7 supplies electric power to the suction pump 4, the stirring tank 6, the coagulant feeding device 5, etc., and the pond 1 is small,
It is not necessary if the equipment can be directly distributed from the shore.

Next, a purification method using this work boat 2 will be described. The muddy water sucked from the bottom of the pond by the suction pump 4 to the suction device 3 is sent to the stirring tank 6, where the coagulant feeding device 5
Add flocculant from. The amount of the flocculant added to the muddy water depends on the type and concentration of sludge contained in the muddy water, but usually 60 to 60 liters of the flocculant is added to 1000 liters of the muddy water.
It is about 150 g.

The concentration of sludge and suspended solids in mud water is 1
If it exceeds 0%, it exceeds the effective range of the coagulant, so it is necessary to dilute it to within 10%. For this dilution, when sucking muddy water, a method of adjusting the position of the cage 9 at the tip of the suction pipe 8 so that a large amount of water at the bottom of the pond is sucked,
There is a method of returning the water to the suction device 3 using the water discharged from the stirred tank 6 after the treatment.

In the stirring tank 6, the muddy water to which the flocculant is added is stirred and mixed by the stirring blades, and then, as it is from the stirring tank 6 as it is, that is, without aggregating solid components by precipitation, dehydration or the like. While being suspended in water, it is returned from the discharge pipe 11 to the pond 1 as treated mud water. The feature of the present invention is that the coagulant is added to the muddy water and the mixture is returned to the pond as it is, and the treatment process can be extremely simple.

When the above coagulant is added to the muddy water in the stirring tank 6 in this manner, the capillary water which has been bound to the soil, the sand particles and the suspended solids floating in the muddy water becomes
Separated and separated as free water. Due to this agglomeration phenomenon, solid particles such as sediment particles and suspended solid particles suspended in mud water are mutually adsorbed to form flocs and become small lumps, and immediately start to settle.

Further, even in the treated water returned to the pond 1, such a coagulation reaction further progresses, and as a result, treated soil having a high compaction property and a low water content is deposited on the bottom of the pond 1. As a result, the transparency of the water increases and clear water is obtained. Furthermore, a part of the flocculant diffuses from the treated water returned to the pond 1 into the water in the surrounding ponds, and the above-mentioned flocculation reaction also occurs there. proceed.

At the same time as agglomeration and sedimentation of sediment particles, suspended solids and the like, algae such as water-bloom and the like, organic substances and malodor causing substances that are floating in muddy water are adsorbed by the flocs described above and settled. . Furthermore, the separated water after treatment has a neutral pH by using an inorganic flocculant, and does not adversely affect the environment even if it is discharged as it is.

Thus, the bottom of the pond 1 has high compaction,
Treated soil with a low water content is deposited and the pond water becomes clear. The entire pond 1 can be purified by cruising the work boat 2 in the pond 1 or by using a plurality of work boats 2, 2 ...

In such a purification method, the treated soil generated by the coagulation reaction is reduced in volume as compared with that before the treatment and is returned to the bottom of the pond, so that the treated soil does not become an industrial waste and is discarded. A practically extremely useful effect is obtained in that the labor of disposal is unnecessary. In the present situation where there is almost no final disposal site for industrial waste, the fact that no industrial waste is generated is a great advantage.

In addition, the fact that the secondary treatment of the treated soil is unnecessary in this manner eliminates the need for equipment such as a dehydration facility, a space such as a drying place, and a cost for carrying out and transporting the treated soil. On the other hand, it does not give off a bad odor, so that the total treatment cost is greatly reduced, and the purification work can be carried out even in a small park or riverbed without causing discomfort to neighboring private houses. further,
Since the separated water is neutral, no secondary treatment is required, and the cost required for this is also unnecessary.

FIG. 2 shows an example of the construction method of the invention according to claim 2. In this example, a plurality of (seven) circulation pumps 21, 21, ... Are dispersed and submerged on the water surface around the pond 1 and arranged. This circulation pump 21
Are operated simultaneously, and a large amount of pond water is ejected from each circulation pump 21, and the pond water flow velocity of 0.
A circulating water flow A of about 5 to 5 m / sec is formed. Due to this rapid circulating water flow A, the sediment, sludge, etc. that have sunk at the bottom of the pond roll up and move along with the circulating water flow A.

Then, in this state, the coagulant is injected into the circulating water flow A from the work boat 22 floated near the shore. The introduced coagulant is mixed with the pond water in the circulation flow A and diffuses. The work vessel 22 has a flocculant injection device 2
3 are installed. As the aggregating agent, the same powdery inorganic material as that used in the previous example is used.

The addition of the coagulant to the circulating water flow A
For example, by continuing for about 3 to 5 days continuously, the same agglutination reaction as in the previous example is performed in the pond water, and eventually the treated soil with high compaction and low water content is deposited on the bottom of the pond. The pond water is gradually clarified and purified.

In the construction method of this example as well, similar to the construction method of the previous example, a great merit that no industrial waste is generated due to the coagulation treatment is obtained and the same action and effect are obtained. Further, it is sufficient to install the flocculant charging device 23 on the work boat 22, which is advantageous in that the facility is simple.

In the above description, the pond is the treated water area, but the present invention is not limited to this.
Rivers, ponds, excavations, etc. can be targeted water areas. Further, if a work boat having an appearance like a leisure boat is used, the work is invisible, and the cleaning work can be performed even when a rental boat is in business.

[0027]

As described above, according to the water bottom purification method of the present invention, the treated soil does not become an industrial waste, and there is no need to dispose of it, which is extremely useful in practice. can get. In addition, since the secondary treatment of treated soil is not required, there is no need for equipment such as dehydration equipment, space for drying places, transportation costs for carrying out treated soil, etc. As a result, the total processing cost can be greatly reduced, and the purification work can be performed without causing discomfort to neighboring private houses even in a narrow park or riverbed.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first example of the present invention.

FIG. 2 is a plan view showing a schematic configuration of a second example of the present invention.

[Explanation of symbols]

1 ... Pond, 2 ... Workboat, 3 ... Suction device, 4 ...
..Suction pump, 5 ... Flocculant charging device, 6 ... Stirring tank, 8 ... Suction pipe, 11 ... Discharge pipe, 2
1 ... Circulation pump, 22 ... Work boat, 23 ... Coagulant feeding device.

Claims (2)

[Claims] 1. A method for purifying a bottom of a water, which is characterized in that mud at the bottom of a water is pumped up to a work boat floated in the water to be treated, a coagulant is added to and mixed with this, and the mud is returned to the water to be treated as it is. 2. A water bottom purification method characterized in that a circulating water flow circulating in the water body to be treated is formed and a coagulant is added to the circulating water flow.