JP2014117626A - Turbid water treatment method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure good working environment and improve working efficiency in underwater construction work involving diving work in port facilities, a dam, a river or the like.SOLUTION: A turbid water treatment method includes the steps of: isolating a target range of turbid water treatment from an outside water area by installing partition walls 10 in water subjected to the turbid water treatment to surround the target range of the turbid water treatment; inserting an air injection pipe 20 into the target range of the turbid water treatment; injecting air from a tip part of the air injection pipe 20 into the target range of the turbid water treatment to generate vertical water flows; adding a coagulating material 40 to the target range of the turbid water treatment; continuing the air injection for a predetermined time; and stopping the air injection to leave at rest for a predetermined time.

Description

  The present invention relates to a method for performing muddy water treatment in situ in underwater construction involving diving work such as harbor facilities, dams, and rivers.

  For underwater construction in harbor facilities, dams, rivers, etc., divers may perform diving work. In this case, if the working water area is cloudy or turbid due to work, the visibility of the diver deteriorates, work efficiency decreases, and work may have to be interrupted to ensure safety . For this reason, it is necessary to perform turbid water treatment in a water area where a diver performs underwater work to reduce turbidity and to ensure transparency above a predetermined standard.

  Conventionally, various muddy water treatment methods have been proposed for ensuring transparency of a predetermined standard or more in a water area where diving work is performed (see, for example, Patent Document 1). The technique described in Patent Document 1 has the following configuration. First, at the bottom of the lake water, a working water area for connecting the ends of the lake bottom pipes is partitioned by a cylindrical curtain. Since the curtain has a plurality of floats on the upper peripheral surface and a weight is attached to the lower end, the upper end of the curtain can be positioned on the water surface and the lower end can be positioned on the lake bottom. Moreover, the notch for letting a lake bottom pipe pass is provided in the lower part of the curtain. Then, a suitable amount of polyaluminum chloride or polymer flocculant is introduced into the work water area partitioned by the curtain, and the work water area is agitated by a pump. It is said that the turbidity in the working water area can be lowered by sinking to the bottom of the lake.

Japanese Patent Laid-Open No. 5-321234

  However, in the conventional turbid water treatment technique as described in Patent Document 1, polyaluminum chloride or a polymer flocculant is directly put into a working water area, and the turbid water is stirred using a submersible pump. It was difficult to ensure transparency above a predetermined standard. That is, the agglomerated material that has been used conventionally works effectively for turbid water with SS (suspended substance, suspended substance) of 1,000 mg / liter or more, but for turbid water with less SS than that. It is known that the effect is small.

  In this way, in submersible work involving diving work, the turbidity of the working water area is low, but the field of view may be nearly zero, even if the aggregate material that has been used for removing turbidity is used, it is actually However, it was not possible to ensure transparency exceeding a predetermined standard.

  Furthermore, in order for the conventionally used agglomerated material to act for turbidity removal, it is necessary to sufficiently agitate the turbid water to disperse the agglomerated material in the muddy water. However, in the conventional technology described in Patent Document 1, since stirring is performed using a submersible pump, the stirring is not sufficient, and the agglomerate cannot be dispersed in muddy water. was there.

  The present invention has been proposed in view of the above-described circumstances, and muddy water treatment capable of ensuring a good working environment and improving work efficiency in underwater construction involving diving work such as harbor facilities, dams, and rivers. It aims to provide a method.

  The muddy water treatment method of the present invention has the following features to solve the above-described problems. That is, the muddy water treatment method of the present invention includes a step of isolating the muddy water treatment target range from an external water area by providing a partition wall in the muddy water treatment water to surround the muddy water treatment target range, and a muddy water treatment target. A step of inserting an air injection tube into the range, a step of injecting air from the tip of the air injection tube into the target area of the muddy water treatment to generate a vertical water flow, and an agglomerate in the target area of the muddy water treatment And a step of continuing the air injection for a predetermined time, and a step of stopping the air injection and allowing to stand for a predetermined time.

  Moreover, it is preferable that the aggregating material described above is an inorganic powder aggregating material using natural mineral as a main raw material.

  According to the muddy water treatment method of the present invention, the agglomerated material can be uniformly and reliably dispersed in muddy water by injecting air into the target range of muddy water treatment to generate a vertical water flow. Therefore, in underwater work involving diving work by a diver, it is possible to ensure transparency that is equal to or higher than a predetermined standard, and it is possible to secure a good working environment for the diver and improve work efficiency.

  In addition, by using an inorganic powder agglomerated material mainly composed of natural minerals as an agglomerated material, even in a muddy water environment where the turbidity is low but sufficient visibility cannot be ensured, it is ensured that the transparency exceeds a predetermined standard. can do. Furthermore, inorganic powder agglomerated materials made mainly of natural minerals have very little adverse effect on the environment because they are less toxic to aquatic organisms.

Explanatory drawing of the equipment used with the muddy water processing method which concerns on embodiment of this invention. The flowchart which shows the procedure of the muddy water processing method which concerns on embodiment of this invention. Explanatory drawing which shows the experimental result in the muddy water processing method which concerns on embodiment of this invention. The graph which shows the relationship between SS, transparency, and transparency.

  Hereinafter, an embodiment of a muddy water treatment method of the present invention will be described with reference to the drawings. 1 to 4 illustrate a muddy water treatment method according to an embodiment of the present invention. FIG. 1 is an explanatory diagram of equipment used in the muddy water treatment method. FIG. 2 is a flowchart showing a procedure of the muddy water treatment method. Is an explanatory diagram showing experimental results, and FIG. 4 is a graph showing the relationship between SS, transparency and transparency.

<Outline of muddy water treatment method>
The muddy water treatment method according to the embodiment of the present invention forms a closed water area by surrounding a target area of muddy water treatment with a partition wall, for example, in underwater construction involving diving work in a port facility, a dam, a river, and the like. In this method, agglomerated material is introduced into the inside, air is injected, and stirring is performed, and muddy water treatment is performed in situ in a closed water area. Moreover, it is preferable to use the inorganic type powder agglomerate which used the natural mineral as the main raw material.

<Equipment used for muddy water treatment method>
In the muddy water treatment method according to the embodiment of the present invention, as shown in FIG. 1, a partition wall (for example, a sheet material) 10, an air injection pipe (for example, an air lift pipe) 20 that surrounds a target area for muddy water treatment, and air An air pump (for example, an air lift pump) 30 for supplying compressed air to the injection pipe 20 is a main equipment used. When a sheet material is used as the partition wall 10, for example, as shown in FIG. 1, a float 11 is attached to the upper part of the sheet material, and a weight 12 is attached to the lower part of the sheet material.

  In addition, the installation used with the muddy water processing method of this invention is not limited to the apparatus mentioned above. For example, any member may be used for the partition wall 10 as long as the target range of the muddy water treatment can be substantially closed. For example, a sheet pile or the like can be used in addition to the sheet material. The air injection tube 20 may be a rigid tube such as a metal tube, or may be a flexible synthetic resin material tube, as long as compressed air can be injected into the target range of muddy water treatment. Also good. Further, the air pump 30 for supplying compressed air may be an air pump 30 having any structure as long as it can supply a predetermined amount of air at a pressure equal to or higher than a predetermined value. Furthermore, an open / close valve 31 for adjusting the air supply amount can be provided in the middle of the air supply pipe 21 for supplying air from the air pump 30 to the air injection pipe 20.

<Specific procedure of muddy water treatment method>
The muddy water treatment method according to the embodiment of the present invention includes the following six steps as shown in FIG. The first step is a step of isolating the target area of the muddy water treatment from the external water area by providing the partition wall 10 in the water to be subjected to the muddy water treatment to surround the target area of the muddy water treatment (S1). In the first step, a closed water area is formed, and muddy water treatment is performed at the original position in the closed water area.

  A 2nd process is a process of inserting the air injection pipe | tube 20 in the target range (closed water area) of muddy water treatment (S2). In the second step, the insertion position of the air injection tube 20 is determined so that the tip of the air injection tube 20 is positioned near the bottom of the closed water area and the turbid water within the target range can be sufficiently stirred. That is, the insertion depth of the air injection tube 20 is adjusted as appropriate in accordance with the situation and water quality of the site that is the target of turbid water treatment.

  A 3rd process is a process of inject | pouring air into the object range (closed water area) of muddy water treatment from the front-end | tip part of the air injection pipe 20 using the air pump 30, and generating a water flow of an up-down direction (S3). ). In the third step, the air injection amount is adjusted so that the turbid water is uniformly stirred within the target range (closed water area) of the turbid water treatment. The air injection amount can be adjusted by, for example, the opening degree of the opening / closing valve 31 provided between the air pump 30 and the air injection pipe 20.

  A 4th process is a process of throwing the aggregate 40 into the target range (closed water area) of muddy water treatment. In the fourth step, the agglomerate 40 is introduced into the muddy water while the air injection is continued (S4). In the present embodiment, an inorganic powder agglomerated material using a natural mineral as a main raw material is used as the aggregating material 40. The amount of the agglomerated material 40 is appropriately adjusted according to the quality of muddy water to be treated. For example, the input amount of the aggregate 40 is about 40 to 400 mg / liter, and the input speed is about 2 to 10 kg / min. If the charging speed of the agglomerate 40 is increased, the agglomerated material 40 becomes dull in water. Therefore, the charging speed should be adjusted as appropriate while observing the stirring state. In addition, the existing fixed amount injection | throwing-in apparatuses (not shown), such as a screw type, a pump type, and a natural fall type, can be used for injection | throwing-in of the aggregate 40. FIG.

  The fifth step is a step of continuing air injection for a predetermined time (S5). In the fifth step, stirring by air injection is continued to form a floc. The duration of air injection varies depending on the quality of the turbid water to be treated, but is, for example, about 1 to 3 hours.

  The sixth step is a step in which the injection of air is stopped and left for a predetermined time (S6). The sixth step is a step of waiting for the formed floc to settle. The standing time varies depending on the flock state and the like, but for example, is about 2 to 5 hours.

<Experimental result>
Using the turbid water treatment method described above, the experiment was conducted with the addition amount of the inorganic powder agglomerated material being 300 mg / liter, the charging time being 30 minutes, the stirring time being 2 hours, and the standing time being 7 hours. In this experiment, as shown in FIG. 3, the transparency, which was originally about 0.2 m, improved to about 2 to 14 m after the muddy water treatment. In this experiment, since the effect was confirmed by turbidity analysis, turbidity and transparency were converted based on known literature data.

<Comparison with conventional muddy water treatment method>
As described above, turbidity may occur in the water area to be dive when performing underwater work involving diving work. The degree of turbidity varies depending on the situation at the site, but as shown in FIG. 4, even if SS is about 20 mg / liter, the transparency may be about 20 to 30 cm. In such a field of view, not only is the work efficiency of divers significantly reduced, but there are also cases where work must be stopped to ensure safety.

  In conventional construction turbid water treatment, turbid water treatment using polyaluminum chloride and polymer flocculant is performed, but in the mechanical turbid water treatment method using polyaluminum chloride and polymer flocculant, SS is about 25 mg / liter. It has proven to be a limit.

  Therefore, the inventors of the present application have conducted various experiments, and as a result, by using an inorganic powder aggregate, the turbidity after treatment is 0 for low concentration turbid water with turbidity of raw water of 15 to 40 NTU. 0.1 to 1.1 NTU and the knowledge that almost transparent treated water was obtained.

  By the way, when a diver works near the bottom of a water in an open chain after turbid water treatment, if the conventional turbid water treatment using polyaluminum chloride and a polymer flocculant, the bottom mud rolls up and poor visibility occurs. It was. On the other hand, when the muddy water treatment is performed by the muddy water treatment method of the present invention, the agglomerate accumulated in the bottom mud is highly durable, so even if the bottom mud is rolled up, it settles in an instant, The defect did not recur.

  Moreover, since the aggregate 40 used in the muddy water treatment method of the present invention is an inorganic powder aggregate made of natural minerals that do not contain harmful substances, it is less toxic to aquatic organisms and has an impact on the environment. Few. As a result of a fish acute toxicity test using Himedaka, the concentration of polyaluminum chloride, which is a conventional aggregating material, was 800 mg / liter at which half of the fish moribund after 96 hours. On the other hand, in the inorganic powder aggregate used in the muddy water treatment method of the present invention, the concentration at which half of the fish drown after 96 hours was 4,500 mg / liter. That is, the inorganic powder aggregate used in the muddy water treatment method of the present invention is significantly less toxic to fish (fish toxicity) than the polyaluminum chloride used in the conventional muddy water treatment method. I understand.

  In addition, the inorganic powder agglomerated material used in the muddy water treatment method of the present invention may form a floc that is stronger and has a larger particle size compared to the case where conventional polyaluminum chloride and a polymer flocculant are used. It turns out. For this reason, the sedimentation speed of flocs is increased and the processing time can be shortened. Further, since the floc is not re-dissolved and is hydrophobized, there is also an advantage that a visual field defect due to re-rolling does not occur.

DESCRIPTION OF SYMBOLS 10 Partition 11 Float 12 Weight 20 Air injection pipe 21 Air supply pipe 30 Air pump 31 On-off valve 40 Aggregating material (inorganic powder aggregating material)

Claims (2)

Isolating the target area of the muddy water treatment from the outside water area by providing a partition wall in the muddy water treatment water and surrounding the target area of the muddy water treatment;
Inserting an air injection tube into the target area of the muddy water treatment;
A step of injecting air into the target area of the muddy water treatment from the tip of the air injection pipe to generate a vertical water flow;
A step of introducing an aggregating material into the target area of the muddy water treatment;
Continuing the air injection for a predetermined time;
Stopping the air injection and allowing to stand for a predetermined time;
The muddy water treatment method characterized by including.   2. The muddy water treatment method according to claim 1, wherein the agglomerated material is an inorganic powder agglomerated material using a natural mineral as a main raw material.

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