JP2640616B2 - Solidification method of submerged sludge - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for solidifying submerged sludge.

[0002]

2. Description of the Related Art When performing dredging work for harbors, rivers, lakes and marshes, it is difficult to dredge the mud at a high mud content (the ratio of the sludge deposited on the water bottom in the dredged bottom sludge). Dredging amount is unavoidable. Therefore, the submerged sludge, dredged submerged sludge is allowed to stand still in a reservoir to settle the soil particles constituting the sludge, and then the excess water formed on the sediment layer is removed, and the sediment is removed. Has been treated by solidification. In this case, it is also known to add a soil particle solidifying agent directly to the dredged submarine sludge in order to promote the sedimentation of the soil particles in the submarine sludge and to simultaneously dehydrate and solidify the sediment (Japanese Unexamined Patent Publication No. 61-149291). However, when the soil particle hardening agent is added to and mixed with the sediment after the surplus water is separated, it is very difficult to uniformly mix the soil particle hardening agent into the sediment. In addition, when the soil particle solidifying agent was directly added to the dredged submerged sludge, the dewatering and solidification of the sediment was often insufficient, and it was difficult to obtain a dewatered and solidified material suitable for truck transportation at an early stage. . In this case, it is considered that the improvement is performed by using a dehydrating machine, but it is not economical in the dredging work that handles a huge amount of dredging.

[0003]

DISCLOSURE OF THE INVENTION The present invention has excellent overall workability and can obtain solidified soil which can be transported by truck by allowing a mixture of submerged sludge and a soil particle solidifying agent to stand for a short period of time. It is an object of the present invention to provide an economical method for solidifying submerged sludge.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have completed the present invention. That is, according to the present invention, in the method for solidifying submerged sludge, (i) a step of dredging submerged sludge by a vacuum suction method and continuously mixing a soil particle solidifying agent in a transfer process thereof, (ii) obtained. Charging the mixture into the reservoir,
(iii) a step of allowing the mixture charged into the reservoir to stand to form a sediment layer formed of soil particles and a soil particle solidifying agent contained in the bottom sediment; (iv) surplus water formed on the upper part of the sediment layer Removing (v) the sediment layer with a water content of 300 to 400;
(Vi) digging a part of the solidified soil and stacking it on the surrounding solidified soil,
(vii) a step of oozing excess water contained in the solidified soil into a concave portion where the solidified soil has been excavated to generate solidified soil having a water content of 200 to 300%, and (viii) removing exuded water remaining in the concave portion. There is provided a method for solidifying submerged sludge, comprising the steps of:

[0005] In order to carry out the present invention, first, sludge deposited on the water bottom is separated and recovered (dredged) from the water bottom. Separation and recovery of water bottom sludge can be performed using a vacuum suction device.
In addition, the water content of the collected bottom sediment varies depending on the properties of the deposited sludge and the depth at which the tip of the vacuum suction device is inserted into the bottom sediment, but taking into account the working efficiency and the amount of separated bottom sediment, It is preferable to control it to about 500 to 1000%. The sludge water content ratio referred to in this specification is the weight of soil particles contained in sludge (the weight of dried sludge).
Means the weight ratio (%) of the water content in the sludge. The submerged sludge separated and collected by the suction by the vacuum suction device is transferred to a soil particle solidifying agent mixing device and uniformly mixed with the soil particle solidifying agent. The mixing apparatus is usually installed at an appropriate place on land, and the transfer of the submarine sludge to this apparatus can be performed by a pressurized transport method using piping. The vacuum suction device for separating and recovering the submarine sludge and the pump device for pumping the submarine sludge can be installed on a hull floating on land. Further, a pipe for pumping the submerged sludge connects the pump device installed on the hull and the soil particle solidifying agent mixing device. By using such a submerged sludge separation and recovery system and a submerged sludge pumping system, the submerged sludge can be transferred to the soil particle mixing device without adversely affecting the surrounding environment.

[0006] The submerged sludge transferred to the soil particle solidifying agent mixing device is uniformly mixed with the soil particle solidifying agent here. As the mixing device, an ordinary stirring and mixing device having stirring blades can be used. As the soil particle hardening agent, any material can be used as long as it reacts with the soil particles and has an action of solidifying the same, but a cement-based hardening agent can be preferably used. Examples of cement-based solidifying agents include blast furnace slag / Portland cement / calcium-based solidifying agent, sulfuric acid-modified blast furnace slag / Portland cement-based solidifying agent, sulfuric acid-modified blast-furnace slag / Portland cement / calcium-based solidifying agent, blast furnace cement, etc. Solidifying agent. Such cement-based solidifying agents are disclosed, for example, in JP-A-55-102677 and JP-A-56-10092.
0, JP-A-57-174523 and JP-A-5-174523.
No. 7,030,783 and JP-A-58-032680. The preferred solidifying agent used in the present invention is blast furnace slag: 73 to 18% by weight, preferably 54 to 18% by weight.
34% by weight, Portland cement: 70 to 16% by weight, preferably 50 to 30% by weight, stone masonry: 2 to 38%
%, Preferably 10 to 25% by weight. The amount of the soil particle solidifying agent added to the bottom sediment is 50 to 150 parts by weight, preferably 70 to 120 parts by weight, based on 100 parts by weight of the soil particles in the bottom sediment. The soil particle solidifying agent is added to the submerged sludge in the form of powder or slurry (mixed liquid of the solidifying agent and water), but is preferably added in the form of slurry. When the soil particle solidifying agent is added in the form of a slurry, the solidifying agent concentration in the slurry is 25 to 63% by weight, preferably 35 to 60% by weight. The mixing of the submerged sludge and the soil particle solidifying agent in the present invention can be performed using a stirring and mixing device provided in a pipe or between a pipe and a pipe, and the mixing operation is easy and uniform. It can be carried out.

[0007] The mixture of the submerged sludge and the soil particle solidifying agent is charged into a reservoir (pit) and allowed to stand. The transfer of the mixture from the mixing device to the reservoir can be pumped using piping. The reservoir may be a large concrete pit or any other pit, as well as an unpitted pit. The depth of this reservoir is not restricted,
It is at least 1.5 m, preferably 2-3 m.
The area of the reservoir is not particularly limited, and may be appropriately selected according to the amount of the mixture to be charged. Also, the number of reservoirs for the mixture is not limited at all and can be one or more.

When the mixture of the submerged sludge and the soil particle solidifying agent is charged into the reservoir and allowed to stand still, the amount of the mixture in the reservoir is not particularly limited. good. When the mixture is left in the reservoir,
The mixture of the soil particles in the sludge and the solidifying agent gradually settles to form a sediment layer, and an excess water layer is formed above the sediment layer. This surplus water layer can be discharged in advance by providing a weir in the reservoir and adjusting it, but it is more efficient to remove it by a suction pump. The removal of the surplus water can be performed one to two days after the mixture is charged and left in the reservoir. Excess water removed from the reservoir is transferred to a spill pit (another reservoir) and stored there. This surplus water is
Normally, since the alkalinity is exhibited by the solidifying agent, excess water is neutralized in this reservoir by aeration (air blowing), carbon dioxide gas blowing, or injection of a chemical such as sulfuric acid. After removal, release to river.

The sediment layer composed of a mixture of the soil particles and the solidifying agent in the reservoir becomes solidified by the reaction between the soil particles and the solidifying agent, increases its strength, and becomes solidified soil. In the present invention,
When the water content of the sediment reaches about 300 to 400% (after separating the excess water from the mixture of the bottom sediment and the solidifying agent,
On the fourth day), a part of the sediment (solidified soil) is excavated, and the excavated solidified soil is piled up on the surrounding solidified soil layer. The ratio of the solidified soil to be excavated is 5 to 40% by volume, preferably 10 to 30% by volume of the total solidified soil, and the excavated location can be one or more locations, and the excavated location can be one or more. The shape of the concave portion of the mark is not particularly limited, but is preferably a groove. Excess water contained in the solidified soil oozes (bleeds) into the concave portion of the excavated trace, and the excess water stays in the concave portion. This surplus water is removed by a suction pump, transferred to the surplus water pit, and stored there.

[0010] After the recesses are formed in the solidified soil as described above, on the second to sixth days, the water content of the solidified soil is 200 to 30 days.
It was reduced to about 0%, and it was found that the product could be transported by truck. In the case of solidified soil having a water content ratio larger than the above range, when attempting to transport it by truck, due to external force such as vibration during the transportation, a part of the water fixed in the reaction product between the soil particles and the solidifying agent Is released and the solidified soil is made muddy and mucous. Such solidified mudified mud can no longer be loaded on the truck bed and flows out of the bed.

FIG. 1 shows an example of a sectional state diagram of a reservoir after excavating a part of the solidified soil, stacking it on the surrounding solidified soil and allowing the solidified soil to stand still. In FIG. 1, reference numerals 1 and 2 denote concrete plates forming the peripheral wall and the bottom of the reservoir, respectively. Reference numeral 3 denotes a solidified soil, and reference numeral 4 denotes a groove-shaped concave portion formed in the excavation trace by partially excavating the solidified soil. Reference numeral 5 denotes a solidified soil obtained by stacking solidified soil obtained by partially raising the solidified soil on the solidified soil 3 around the solidified soil. Numeral 6 indicates seepage water from the solidified soil stored in the groove-shaped concave portion. The height of the reservoir shown in FIG. 1 is about 2.8 m, the vertical length is about 20 m, and the horizontal length is about 5 m. The height of the solidified soil 3 is about 2m
And the width of the groove-shaped recess 5 is about 1.5 m. By partially digging the solidified soil as described above, the solidified soil that can be transported by truck can be obtained in a short period of time. For example, after the mixture of the submerged sludge and the solidifying agent is put into the storage tank and allowed to stand, the time required to obtain solidified soil that can be transported by truck is about 14 days in winter, when excavation is not performed. Can be reduced to about 11 to 12 days by excavation. Also, in the case of summer, what would take seven days when the excavation is not performed can be reduced to 4 to 5 days by performing the excavation.
The solidified soil having a water content of about 200 to 300% obtained as described above can be used not only as a landfill soil but also as a planting soil or a soil improvement soil.

[0012]

According to the present invention, submerged sludge can be converted into soil (solidified soil) which can be transported by truck in a short period of time with good work efficiency. Moreover, the soil obtained by the present invention can be effectively used as landfill soil, planting soil, soil improvement soil, and the like.

[0013]

Next, the present invention will be described in more detail with reference to examples.

Example 1 Sludge deposited on the bottom of a castle moat pond is sucked up from the bottom by a vacuum suction device installed on a hull, and introduced into a stirring and mixing tank installed on land through a pipe by a pressure pump.
Here, it was mixed with a slurry-like soil particle solidifying agent. In this case, the water content of the bottom sludge introduced into the stirring and mixing tank is about 90%.
It was 0%. Blast furnace slag: 38% by weight as a solidifying agent
And Portland cement: 42% by weight and stone stone: 2
A mixture consisting of 0% by weight is dispersed in water and the concentration is 59%.
A slurry in which the weight% was used was used. This slurry-like solidifying agent is equivalent to the solid particles 100 in the soil sediment contained in the bottom sediment.
100 parts by weight with respect to parts by weight were added and mixed.

Next, the mixture of the submerged sludge obtained as described above and the solidifying agent was mixed with the mixture shown in FIG.
m, the width: 5 m, and the height: 2.8 m. The concrete pit was charged up to a height of 2.6 m, and allowed to stand for 2 days. By this standing, the mixture of the soil particles in the bottom sediment and the solidifying agent settles,
A sediment with a height of 2.2 m was obtained. The sediment (water content: 3
An excess water layer was formed on the upper part of the (64%) layer. After removing this surplus aqueous layer, it was left still for 4 days. By this standing, the reaction between the soil particles in the sediment layer and the solidifying agent proceeded, and solidified soil with increased strength (water content: 330%) was formed. At this point, a part of the solidified soil was excavated using a backhoe, and was piled up on the solidified soil around the part as shown in FIG. After this operation, excess water contained in the solidified soil oozed into the concave portion. After excavation of the solidified soil, the exuded water remaining in the concave portion was removed on the fifth day by a suction pump. At this point, the water content of the solidified soil was about 248%, and it was confirmed that the soil could be transported by truck. In the solidification treatment of submerged sludge, when excavation work of solidified soil is not performed, solidified soil capable of being transported by truck (water content: 296)
%), It took 4 days after the mixture of the submerged sludge and the solidifying agent was put into the reservoir and allowed to stand.

[Brief description of the drawings]

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a cross-sectional view of a reservoir after excavating a part of the solidified soil, stacking the solidified soil on a surrounding solidified soil, and allowing the solidified soil to stand still.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Concrete surrounding wall 2 Concrete bottom plate 3 Solidified soil 4 Concavity of the mark which excavated solidified soil 5 Solidified soil piled up 6

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Zenichi Mashino 2-1-1, Tsurumichuo, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside Chiyoda Chemical Works (72) Inventor Yoshinori Watanabe Tsurumi-ku, Yokohama-shi, Kanagawa Tsurumi Chuo 2-chome No. 12 Chiyoda Kako Construction Co., Ltd. (56) References JP 50-153454 (JP, A) JP-B 60-12120 (JP, B2) JP-B 52-49912 (JP, B2)

Claims (3)

(57) [Claims] 1. A method for solidifying submerged sludge, comprising:
(I) a step of dredging submerged sludge by a vacuum suction method and continuously mixing the soil particle solidifying agent in the transfer process, (ii) a step of charging the obtained mixture into a reservoir, and (iii) a step of charging the reservoir. A step of allowing the input mixture to stand to form a sediment layer comprising soil particles contained in the submarine sludge and a soil particle solidifying agent, (i.
v) a step of removing excess water formed on the upper part of the sediment layer, (v) a step of allowing the sediment layer to stand until a solidified soil having a water content of 300 to 400% is obtained, (vi) one of the solidified soils (Vii) exuding surplus water contained in the solidified soil into the concave portion of the trace where the solidified soil has been digged, and solidifying the solidified material having a water content of 200 to 300%. A method of solidifying submerged sludge, comprising: a step of generating; and (viii) a step of removing exuded water remaining in the concave portions. 2. The method according to claim 1, wherein the soil particle solidifying agent is mixed with the submerged sludge as a slurry liquid having a concentration of 25 to 63% by weight dispersed in water. 3. The method according to claim 1, wherein a cement-based solidifying agent is used as the soil particle solidifying agent.