Method for reducing turbidity of water area

Abstract

To provide a method for reducing turbidity of a water area capable of easily reducing turbidity of a water area and applicable to a wide variety of water areas.SOLUTION: In a water area in which water flows or stays, water is drained, an anti-suspension agent that prevents sediments from being suspended by water flow is sprayed on at least the bottom of the water area, and after the area sprayed with the anti-suspension agent has solidified, water is poured into the water area.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to turbidity reduction for reducing the turbidity of water areas. Method

Background Art

[0002] Conventionally, for example, when muddy water generated during the construction of a power plant is allowed to flow down to a sedimentation basin (water area) through a water conduit (water area), the turbidity of the water has been reduced by precipitating suspended particles in the muddy water in the water conduit and the sedimentation basin. However, when there are sudden increases or decreases in the water flow rate or velocity in the water conduit or sedimentation basin, there has been a problem that the sediment is resuspended and the turbidity increases.

[0003] On the other hand, there is known a sedimentation basin structure in which a spiral waterway is composed of a gradient waterway in the central part and a horizontal waterway in the outer peripheral part, and by forcibly diffusing a flocculant, separation into water that can be discharged and soil particles is achieved (see, for example, Patent Document 1). Also, there is known a method for treating muddy water in which muddy water generated by civil engineering work is led to a sedimentation basin, large sand and small stones are precipitated, and then passed through a water permeable plate, so that small suspended particles adhere to the water permeable plate and are removed (see, for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] ​However, in the grit chamber structure described in Patent Document 1, it is applicable only to circular grit chambers, and it is difficult to apply when the shape of the grit chamber cannot be made circular due to geographical reasons or the like. Also, although the flocculant can be diffused, it is difficult to prevent the sediment from resuspending due to strong water flow. Further, in the treatment method of Patent Document 2, since the treatment amount of muddy water depends on the permeation capacity of the water-permeable plate, it is difficult to apply when a large amount of muddy water is generated in large-scale construction. Moreover, since floating particles adhere to the water-permeable plate, it is necessary to regularly maintain and replace the water-permeable plate, which requires a great deal of cost and labor for maintenance, and thus it is particularly difficult to apply to large-scale construction.

[0006] Therefore, the present invention aims to simply reduce the turbidity of water areas and is applicable to various water areas for reducing the turbidity of water areas. Method

Means for Solving the Problems

[0007] In order to solve the above problems, the invention according to claim 1 is a method for reducing the turbidity of a water area, which comprises draining water in a water area where water flows or stagnates, spraying an anti-floating agent on at least the bottom part of the water area to prevent sediment from floating due to water flow, and flowing water into the water area.

[0008] The invention according to claim 2 is characterized in that, in the method for reducing the turbidity of a water area according to claim 1, after the part where the anti-floating agent is sprayed is solidified, water is flowed into the water area.

[0009] The invention according to claim 3 is characterized in that, in the method for reducing the turbidity of a water area according to claim 1 or 2, every time the turbidity of the water in the water area becomes equal to or higher than a predetermined value, the water is drained, the anti-floating agent is sprayed, and water is flowed into the water area.

Effects of the Invention

[0011] Claim 1 ​According to the invention described in , a floating prevention agent for preventing sediment from floating due to water flow is sprayed on at least the bottom surface of the water area, that is, the sedimentation part. Therefore, it is possible to prevent the sediment from resuspending due to water flow and the turbidity from increasing. Moreover, since it is only necessary to spray the floating prevention agent, it is possible to easily reduce the turbidity of the water area. Furthermore, it is applicable to various water areas regardless of the shape, topography, size, scale, etc. of the water area.

[0012] According to the invention described in claim 2, after the part where the floating prevention agent is sprayed solidifies, that is, after the bottom surface part and sedimentation part of the water area solidify, water is flowed into the water area. Therefore, it is possible to more reliably prevent the sediment from resuspending due to water flow.

[0013] According to the invention described in claim 3, every time the turbidity of the water in the water area becomes equal to or higher than a predetermined value, the water is drained, the floating prevention agent is sprayed, and water is flowed into the water area. Therefore, it is possible to continuously prevent the turbidity of the water area from increasing. Moreover, since it is only necessary to spray the floating prevention agent every time the turbidity of the water becomes equal to or higher than a predetermined value, it is possible to easily and continuously keep the turbidity of the water area low. Furthermore, it is applicable to various water areas. That is, if it is known how long the turbidity of the water becomes equal to or higher than the predetermined value, the anti-resuspension function can be restored only by spraying the floating prevention agent regularly (every such period). Therefore, it is possible to reduce the labor, cost, and time required for maintenance.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Embodiments for Carrying Out the Invention

[0015] Hereinafter, this invention will be described based on the illustrated embodiments.

[0016] FIG. 1 is a flowchart showing the steps of a method for reducing the turbidity of a water area according to an embodiment of this invention (hereinafter referred to as the "turbidity reduction method"). This turbidity reduction method is a method / technique for reducing the turbidity of a water area where water flows or stagnates. In this embodiment, as shown in FIG. 2, the case where the muddy water generated during the construction of a power plant is allowed to flow down to a sedimentation basin (water area) 101 through a water conduit (water area) 102 will be mainly described.

[0017] Here, a substantially horizontally long equipment yard 103 is provided adjacent to the substantially horizontally long sedimentation basin 101 in a side-by-side manner, and a water conduit (outer peripheral water conduit) 102 is provided so as to bypass the outer peripheries of the sedimentation basin 101 and the equipment yard 103. This water conduit 102 is a concave side groove and is provided adjacent to the sedimentation basin 101 on the outer periphery of the sedimentation basin 101, as shown in FIG. 3. Then, the muddy water generated during the construction flows down from an inlet (notch) 101a into the sedimentation basin 101 through the long water conduit 102, and the purified muddy water is drained into the open sea from a drain port (not shown).

[0018] In this way, by flowing the muddy water generated during the construction of the power plant through the long water conduit 102, the suspended particles in the muddy water precipitate in the water conduit 102 and flow down into the sedimentation basin 101. Furthermore, the remaining suspended particles in the muddy water that has flowed down into the sedimentation basin 101 precipitate in the sedimentation basin 101. However, in the water conduit 102 and the sedimentation basin 101, there is a problem that if the water flow rate or flow velocity changes suddenly or a turbulent flow occurs, the sediment on the bottom surface of the water conduit 102 or the sedimentation basin 101 will re-suspend and the turbidity will increase.

[0019] On the other hand, by adopting this turbidity reduction method, the turbidity of the water conduit 102 and the grit chamber 101 is reduced and stabilized. Here, the case of applying this turbidity reduction method to the water conduit 102 will be mainly described, but it goes without saying that it can also be applied to the grit chamber 101 in the same way.

[0020] First, as shown in FIG. 1, stop the flow of the muddy water and drain the muddy water and water in the water conduit 102 (step S1), and spray a floating inhibitor on at least the bottom surface of the water conduit 102 (step S2). Here, the floating inhibitor is a chemical that prevents the sediment deposited on the bottom surface of the water conduit 102, etc. from floating due to the water flow. Specifically, it is a water-resistant dust inhibitor that covers the sediment with a consolidated layer rich in water resistance, binding property, and elasticity (coating the sediment), thereby preventing the re-floating of the sediment. Such a floating inhibitor may be sprayed not only on the bottom surface of the water conduit 102 but also on the side surface as necessary. That is, it is preferably sprayed on the part where the floating particles in the muddy water come into contact and settle.

[0021] Next, solidify the part where the floating inhibitor is sprayed (step S3), that is, wait until the sprayed part solidifies, and then resume the flow of the muddy water and flow the muddy water and water into the water conduit 102 (step S4). Here, whether the sprayed part has solidified can be confirmed by whether the color has changed (for example, whether it has whitened). And every time the turbidity of the water in the water conduit 102 becomes equal to or higher than a predetermined value (when "Y" in step S5), the above-mentioned draining, spraying, solidifying, and water inflow (steps S1 to S4) are repeated. On the other hand, when the turbidity of the water is less than the predetermined value (when "N" in step S5), the water flow is continued (step S4).

[0022] Here, the method for measuring the turbidity of water can be any method. For example, visual turbidity, transmitted light turbidity, scattered light turbidity, etc. may be adopted. Also, if it is generally understood how long after the spraying of the anti-floating agent the turbidity of the water becomes equal to or higher than a predetermined value, steps S1 to S4 may be repeated regularly (for each such period). Further, when the bottom surface portion, etc. of the water conduit 102 discolors (becomes white) after the spraying of the anti-floating agent and the turbidity of the water reaches a value equal to or higher than the predetermined value and discolors again after the water inflow (for example, when it returns from white to the original earth color), steps S1 to S4 may be repeated.

[0023] In this way, by applying this turbidity reduction method to the water conduit 102, this water conduit 102 becomes a turbidity reduction water area where the anti-floating agent is sprayed on the bottom surface portion, etc.

[0024] As described above, according to this turbidity reduction method and the turbidity reduction water area (water conduit 102), since an anti-floating agent for preventing sediment from floating due to the water flow is sprayed on at least the bottom surface portion of the water conduit 102, that is, the sedimentation portion, it becomes possible to prevent the sediment from re-floating due to the water flow and the turbidity from increasing. That is, in a state where the anti-floating agent is not sprayed, when the water flow rate or flow velocity of the water changes rapidly or a turbulent flow occurs, as shown in Fig. 4(a), the sediment above the bottom surface portion (sedimentation portion) 102a of the water conduit 102 is entrained and re-floats, and the turbidity increases. On the other hand, in a state where the anti-floating agent is sprayed, as shown in Fig. 4(b), a solidified layer 102b due to the anti-floating agent is formed above the bottom surface portion 102a of the water conduit 102. Therefore, even if the water flow rate or flow velocity of the water changes rapidly or a turbulent flow occurs, the re-floating of the sediment is suppressed and prevented, and it becomes possible to prevent the turbidity from increasing.

[0025] Furthermore, after the portion where the anti-floating agent is sprayed solidifies, that is, after the upper part of the bottom surface portion 102a of the water conduit 102 solidifies and the solidified layer 102b is formed, water is flowed through the water conduit 102 again, so that it becomes possible to more surely prevent the sediment from re-floating due to the water flow.

[0026] Moreover, since it is only necessary to spray the anti-floating agent, it is possible to easily reduce the turbidity of the water conduit 102, and furthermore, it can be applied to various water conduits 102 regardless of the shape, topography, size, or scale of the water conduit 102.

[0027] Also, every time the turbidity of the water in the water conduit 102 becomes equal to or higher than a predetermined value, the water is drained, the anti-floating agent is sprayed, and then water is flowed through the water conduit 102. Therefore, it is possible to continuously prevent the turbidity of the water conduit 102 from increasing. Moreover, since it is only necessary to spray the anti-floating agent every time the turbidity of the water becomes equal to or higher than a predetermined value, it is possible to easily and continuously keep the turbidity of the water conduit 102 low, and furthermore, it can be applied to various water conduits 102. That is, if it is generally known how long it takes for the turbidity of the water to become equal to or higher than a predetermined value, the anti-floating agent can be sprayed regularly (every such period), and the anti-re-suspension function can be restored. Alternatively, if the color (white) discolored by the spraying of the anti-floating agent returns to the original earth color, the anti-floating agent can be sprayed, and the anti-re-suspension function can be restored. For this reason, it is possible to reduce the labor, cost, and time required for maintenance.

[0028] Here, the results of the applicant's experimental application of this turbidity reduction method to the water conduit 102 will be described.

[0029] First, regarding the test procedures and conditions, water with a turbidity of less than 10 NTU is pumped at a predetermined flow rate to the water conduit 102 without spraying the anti-floating agent and the water conduit 102 with spraying respectively. Then, when the water flow in the water conduit 102 reaches a steady state, water is sampled and the turbidity is measured at the upstream and downstream sides of the water conduit 102. And such tests were conducted in each case where the water flow was intentionally disturbed (when locally intense turbulent flow was generated) and where it was not disturbed, at the intermediate point between the water sampling points on the upstream and downstream sides.

[0030] The results are as follows. In the water channel 102 where the anti-floating agent was not sprayed, when the water flow was not disturbed, there was no significant difference in turbidity between the upstream side and the downstream side. However, when the water flow was disturbed, it was found that the turbidity on the downstream side became significantly (orders of magnitude) higher and worse than that on the upstream side. On the other hand, in the water channel 102 where the anti-floating agent was sprayed, when the water flow was not disturbed, there was no significant difference in turbidity between the upstream side and the downstream side. Also, even when the water flow was disturbed, it was found that the turbidity on the downstream side was only slightly higher than that on the upstream side.

[0031] Thus, it was confirmed that by applying this turbidity reduction method to the water channel 102, that is, the water area, it is possible to prevent an increase in turbidity even when turbulent flow occurs. Also, it was confirmed that there was an obvious difference in the turbidity of the water visually between the water channel 102 where the anti-floating agent was sprayed and the water channel 102 where it was not sprayed (the water channel 102 where it was not sprayed was clearly more turbid).

[0032] Although the embodiments of this invention have been described in detail above, the specific configuration is not limited to this embodiment. Even if there are design changes and the like within the scope that does not deviate from the gist of this invention, they are included in this invention. For example, in the above embodiment, the water area is the water channel 102 or the sedimentation basin 101, and in particular, the case where this turbidity reduction method is applied to the water channel 102 was explained. Needless to say, it can be applied to other water areas.

Explanation of Signs

[0033] 101 Sedimentation basin (water area) 102 Water channel (water area) 102a Bottom surface part 102b Consolidated layer 103 Equipment yard W Water (muddy water)

Claims

**Claim 1** In a water area where water is flowing or stagnant, draining the water, spraying a floating prevention agent on at least the bottom surface of the water area to prevent sediment from floating due to water flow, flowing water into the water area, A method for reducing the turbidity of a water area, characterized by the above. **Claim 2** After the part where the floating prevention agent is sprayed solidifies, flowing water into the water area, The turbidity reduction method according to claim 1, characterized by the above. **Claim 3** Whenever the turbidity of the water in the water area reaches a predetermined value or more, draining the water, spraying the floating prevention agent, and flowing water into the water area, The turbidity reduction method according to any one of claims 1 or 2, characterized by the above.

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