JP2013023810A - Method for preventing diffusion of pollution near water bottom in dredging - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for preventing the diffusion of pollution near the water bottom in dredging.SOLUTION: A coagulant is previously applied to pollution diffusion substances at the water bottom for dredging, so as to prevent the diffusion of pollution near the water bottom in dredging and pollution in removing sludge.

Description

The present invention relates to a method for preventing the diffusion of pollution near the bottom of a water during drought.

In recent years, dredging of water beds such as lakes, rivers, dam lakes, and harbors has been carried out. A grab frame is used as a method of suppressing the diffusion of pollution during such drought. The grab frame has a float section partitioned by a buoyant body on the water surface and a curtain membrane section surrounded by water. Is deeper than the water depth, the actual condition is that the dirt diffuses from the bottom of the curtain film during mud.

Therefore, as a method for suppressing the diffusion of pollution during conventional dredging, for example, a flocculant filler that contains a flocculant in the curtain film part and is capable of eluting the flocculant with water is attached at intervals in the horizontal and vertical directions. Has been proposed in which the flocculant is brought into contact with the curtain membrane portion to which the flocculant filler is attached, and the pollutant is agglomerated with the eluting flocculant.
In addition, the flocculant filler is directly attached to the grab bucket, and the contaminated water is brought into contact with the flocculant filler and stirred by flowing water when the grab bucket is poured into the water, dredging, or during muddying. A method of aggregating with the eluting flocculant has been proposed. In the construction method in which the flocculant filler is attached to the curtain film portion, the flocculant is always in contact with water, so that the elution time is fast, but the agglomeration effect is worsened because the agitation necessary for aggregation is insufficient. . In addition, the construction method in which the flocculant filler is directly attached to the grab bucket has a lot of work in the grab bucket underwater, such as when the grab bucket is poured into the water, dredging, and during mud, and the stirring effect is sufficient. The grab bucket is not always in water, and the elution time of the flocculant filler is short, so there is a drawback that the coagulation effect is deteriorated.

Japanese Patent No. 2516742

  The present invention has been completed as a result of various studies on construction methods capable of preventing the diffusion of pollutants in the vicinity of the bottom of the water by dripping the flocculant.

  That is, the present invention is a construction method for preventing diffusion near the bottom of the water at the time of dredging and pollution at the time of drainage by spreading the flocculant in advance on the pollutant at the bottom of the water.

According to the method of preventing diffusion near the bottom of the water during dredging of the present invention, the flocculant is sprayed in advance on the bottom mud, and after dissolution, the mixture is stirred with a grab bucket or a pump dredger ladder, etc. It is possible to agglomerate a high concentration of the flocculant in the turbid material at the time of drought, and to effectively prevent the pollution at the time of small-scale high turbidity of the pollution generation source.

  Further, according to the present invention, the pollutant and the flocculant are brought into contact with each other at a high concentration, so that reliable aggregation can be achieved.

Furthermore, according to the present invention, the aggregated particles settle and contact and agglomerate again to the turbidity, so that clarification in water can be achieved.

The perspective view which shows the dredger which fixed the grab frame to the grab type dredger, and lowered | hung the grab bucket which attached the flocculant filler which the coagulant | flocculant contained and the flocculant can be eluted with water was dropped in water. The perspective view which shows that the diver is spraying the flocculant on the water bottom. The perspective view which shows the dredging which lowered | hung the grab bucket which attached the flocculant filling body which contains the flocculant of a grab type dredger and which can elute the flocculant with water after spraying the flocculant on the water bottom.

Next, the present invention will be described with reference to the drawings, but the present invention is not limited to the following description.
FIG. 1 is a perspective view showing a dredger in which a grab bucket 6 to which a grab frame 3 is fixed to a grab dredger 1 and a flocculant filling body 7 containing a flocculant and from which the flocculant can be eluted is attached is lowered into water. When the grab bucket 6 is lowered into the water, when it is thrown into the water, when dredging, when mud, etc., the water is stirred to bring the contaminated water into contact with the flocculant filler 7 and stir to remove the pollutant. The glove bucket 6 is not always in the water, and the elution time of the flocculant filler 7 is small, so that the aggregation is worsened and the length of the curtain film part 5 is greater than the depth of water. If it is short, it means that the non-aggregated pollutant diffusing substance diffuses from the bottom of the curtain film part 5 when the mud is pumped.

  In FIG. 2, the diver 8 dive before the dredging / excavation work, and the flocculant 10 is sprayed on the bottom 9. By dispersing the flocculant 10 on the bottom 9, the flocculent 10 absorbs water and becomes a gel shape with time. The flocculant action is promoted without scattering or diffusing in the bottom flow, and high concentrations of pollutants and flocculants are present. It is possible to cause reliable aggregation by contacting with.

As a method for spraying the flocculant 10 according to the present invention, the diver 8 is submerged before construction work for dredging and excavation, and depending on the size of the flocculant 10, the flocculant 10 can be dispersed vertically and horizontally. Although it is desirable to arrange them at intervals of about 1 m in the direction, depending on the work process or the current situation, about 100 pieces may be sprayed per 100 m ² from the water or from the water.

  FIG. 3 shows the water bottom 9 sprayed with the flocculant 10 being drowned by dropping the grab bucket 6 with the flocculant filler 7 attached to the grab dredger 1 into the water. The grab bucket 6 grips the flocculant 10 and dredged sand at the water bottom 9, and the pollutant and the flocculant come into contact with each other at a high concentration, so that the agglomeration can be surely performed. By bringing the pollutant into contact with the flocculant 10, the resulting agglomerated particles settle and contact and agglomerate again with the pollutant, thereby clarifying the turbid water in water and increasing the transparency in water.

  In addition, the present invention instantly prevents the diffusion of pollution caused by mechanical impacts caused by dredging by placing the flocculant 10 on the bottom 9 and dredging by the grab bucket 6 before dredging and excavation work. Not only can it be kept within a small range by re-contacting agglomeration, but also sedimentation of the turbid water discharged from dredged soil can be clarified.

  The earth and sand dredged by the grab bucket 6 is transferred to the earth transport ship 2 provided alongside the grab dredger 1. In addition to dredged sand, a large amount of discharged turbid water is stored in the earth ship 2, and the settled separated water that has been clarified in the solid / liquid separated water is returned to the grab frame 3, Since the mud load can be further increased and the dredged sand can be stored on the earth ship 2, the work efficiency due to the increase in the amount of mud stored in the earth ship 2 can be increased.

Further, as shown in FIG. 3, by attaching the flocculant filler 7 to the grab bucket 6, the diffused pollutants in the grab frame 1 can be used when the grab bucket 6 is poured into water, dredged, mud pumped, etc. By agitation with water flow, coagulation and sedimentation can be achieved, and transparency in water can be achieved.

  The flocculant 10 of the present invention is preferably a solid flocculant, a powder flocculant, etc. However, unlike a powder or liquid flocculant, the solid flocculant has a delayed solubility and a long flocculant life. If it is placed on the bottom mud of the soil, it is mixed with mud at a high concentration in the surroundings at dredging, and the diffusion of stirring pollution at dredging can also be prevented. It is optimal because it prevents further diffusion.

  As an application of the present invention, it is also preferable to increase the visibility of suspended water under water depth such as disaster water areas and dams by spreading the flocculant 10 on the water bottom 9 in advance.

DESCRIPTION OF SYMBOLS 1 .... Grab-type dredger 2 .... Soil ship 3 .... Grab frame 4 .... Float part 5 .... Curtain part 6 .... Grab bucket 7 .... Agglomeration Filler 8 ... Diver 9 ... Water bottom 10 ... Flocculant

Claims (1)

  A construction method that prevents spreading of pollutants in the vicinity of the bottom of the dredging and polluted by drainage, characterized by spreading the flocculant in advance on the pollutant diffused in the bottom of the water.

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