JP6145242B2 - Pollution prevention device and pollution prevention method - Google Patents

Description

  The present invention relates to a pollution prevention device and a pollution prevention method, and more particularly, to a technique for purifying pollution in water using a flocculant and bubbles.

  Conventionally, a technique disclosed in Patent Document 1 by the same applicant is known as this type of pollution prevention technique. The prior art disclosed in Patent Document 1 spouts a flocculant and bubbles near the lower end of a pollution prevention film (also referred to as “fouling prevention curtain” in this technical field) that extends down from the water surface to the water. By doing so, convection is formed in the water, and the contamination in the water is efficiently removed.

  Applicants have discovered the fact that the flocculant is more effectively agitated in the water near the surface of the water where bubbles are repelled during repeated verification experiments. If this effect can be utilized, the contamination in water can be removed more efficiently.

Japanese Patent No. 4774112

  The present invention has been made in view of the above problems and discovery facts, and provides a pollution prevention device and a pollution prevention method that improve the efficiency of pollution cleaning by utilizing the stirring effect of the flocculant by bubbles near the water surface. For the purpose.

  In order to solve the above problems and achieve the above object, a first aspect of the present invention is a pollution control device, which is a gas holder, a supporting means, a bubble releasing means, and a flocculant releasing means. And. The gas holder has an opening and can hold gas in water. The support means supports the gas holder in water so that the opening portion faces downward. The bubble releasing means discharges bubbles into the water below the supported gas holder. The flocculant releasing means discharges the flocculant into the water surface formed inside the supported gas holder or in the water below the water surface.

  According to this configuration, gas is supplied in advance to the inside of the gas holding body by releasing the bubbles into the water below the gas holding body supported in the water so that the opening portion faces downward. Regardless of whether it is present, a gas chamber is formed and maintained. Bubbles rise in the water and repel at the water surface formed by the gas chamber. The flocculant released into the water below the water surface moves by the water flow formed by the bubbles and reaches the vicinity of the water surface. Accordingly, the flocculant released into the water surface or the water below the water surface is effectively stirred in the water near the water surface by bubbles repelling on the water surface. Thereby, pollution is efficiently removed in the water below the surface of the water area to be treated.

  According to a second aspect of the present invention, there is provided the pollution control device according to the first aspect, wherein the gas holding body is mainly composed of a film body and can be folded. Further, the support means includes a string body having a trunk portion and a branch portion branched into three or more at one end thereof, and a gantry. As for the said string body, the front-end | tip part of the said branch part is connected to the peripheral part of the said opening part of the said gas holding body. The said gantry supports a part of trunk part of the said string body by being sunk in a water bottom.

  According to this structure, since the gas holding body is mainly formed of a film body and can be folded, it can be easily transported and stored. Furthermore, a part of the string connected to the gas holding body is supported by a gantry submerged in the water bottom. Thereby, the gas holder is supported in water against buoyancy generated by the air chamber formed in the gas holder.

  According to a third aspect of the present invention, there is provided the pollution control device according to the second aspect, wherein the gantry supports the trunk portion of the string body so as to be able to be drawn out and retracted.

  According to this configuration, since the length of the string body from the gantry to the gas holding body can be changed, the depth of the gas holding body in water can be changed by operating the gantry. Thereby, pollution removal is performed efficiently in various depths in water.

  According to a fourth aspect of the present invention, there is provided the pollution control device according to the second or third aspect, wherein the gas holders are radially formed along three or more radial directions from the center and are mutually connected. It includes a bag body that communicates and a gas stopper that allows gas to be taken in and out of the bag body.

  According to this structure, a gas holding body can be expand | deployed by supplying gas, for example, air, through a gas stopper to the bag body (Fukutai) radially formed in the gas holding body. Thereby, it is possible to expand the gas holding body in the water before releasing the bubbles into the water, and it is possible to apply buoyancy in advance in the water. By removing the gas from the bag body, the gas holder can be folded, so that the convenience of transportation and storage is not hindered.

  According to a fifth aspect of the present invention, there is provided the pollution control device according to any one of the second to fourth aspects, wherein the bubble releasing means includes a gas pipe having one end supported by the gantry, Gas delivery means for feeding gas into the gas pipe. The gas pipe is formed with a discharge port for discharging bubbles at the one end.

  According to this configuration, for example, by placing the gas delivery means on the shore of the target water area and operating it, bubbles can be discharged into the water from the position of the gantry submerged in the bottom of the water. The bubbles rise and reach the water surface formed inside the gas holder. In this way, by sinking the gantry to the bottom of the water and operating the gas delivery means, the bubbles can be easily fed into the water surface formed inside the gas holder. The gas delivery means may be connected to the gas pipe from the beginning or connected at the time of use. This configuration includes both.

  According to a sixth aspect of the present invention, there is provided a pollution control apparatus according to any one of the second to fifth aspects, wherein the flocculant releasing means includes a liquid pipe having one end supported by the gantry, Solution delivery means for feeding a solution containing a flocculant into the liquid pipe. The liquid pipe is formed with a discharge port for discharging the solution at the one end of the liquid pipe.

  According to this configuration, for example, by placing the solution delivery means on the shore of the target water area and operating it, the solution containing the flocculant can be discharged into the water from the position of the gantry submerged in the bottom of the water. The flocculant rises due to the flow of water generated by bubbles and reaches the vicinity of the water surface formed inside the gas holder. In this way, the flocculating agent can be easily fed to the vicinity of the water surface formed inside the gas holder by sinking the gantry to the bottom of the water and operating the solution delivery means. The solution delivery means may be connected to the liquid pipe from the beginning or may be connected at the time of use. This configuration includes both.

  According to a seventh aspect of the present invention, there is provided the pollution control device according to any one of the second to fourth aspects, wherein the bubble releasing means and the flocculant releasing means are supported at one end by the gantry. And a mixed fluid sending means for sending a mixed fluid of a gas and a solution containing a coagulant to the fluid pipe. The fluid pipe is formed with a discharge port for discharging the mixed fluid at the one end of the fluid pipe. The mixed fluid delivery means may be connected to the fluid piping from the beginning or connected at the time of use. This configuration includes both.

  According to this configuration, the mixed fluid delivery means is placed on the shore of the target water area, for example, and operated to release the solution containing bubbles and coagulant in the water from the position of the mount submerged in the bottom of the water. be able to. The bubbles rise and reach the water surface formed inside the gas holder. The flocculant rises due to the flow of water generated by bubbles and reaches the vicinity of the water surface formed inside the gas holder. In this way, by sinking the gantry to the bottom of the water and operating the mixed fluid delivery means, the bubbles are sent to the water surface formed inside the gas holding body, and the flocculant is near the water surface formed inside the gas holding body. Easy to feed.

  According to an eighth aspect of the present invention, there is provided a pollution prevention method, wherein a gas holding body having an opening and capable of holding a gas in water is disposed in water with the opening facing downward. , Releasing bubbles into the water below the gas holder disposed in the water, and releasing a flocculant into the water surface formed inside or below the gas holder disposed in the water; To do.

  According to this configuration, gas is supplied in advance to the inside of the gas holding body by releasing bubbles into the water below the gas holding body arranged in the water so that the opening portion faces downward. Regardless of whether it is present, a gas chamber is formed and maintained. Bubbles rise in the water and repel at the water surface formed by the gas chamber. The flocculant released into the water below the water surface moves by the water flow formed by the bubbles and reaches the vicinity of the water surface. Accordingly, the flocculant released into the water surface or the water below the water surface is effectively stirred in the water near the water surface by bubbles repelling on the water surface. Thereby, pollution is efficiently removed in the water below the surface of the water area to be treated.

According to a ninth aspect of the present invention, there is provided a pollution prevention method according to the eighth aspect, wherein the release of the bubbles and the above-mentioned while changing the depth of the gas holder in water stepwise or continuously. The flocculant is supplied.
According to this configuration, contamination removal is efficiently performed at various depths in water.

  As described above, according to the present invention, a pollution prevention device and a pollution prevention method that improve the efficiency of pollution cleaning are realized by utilizing the stirring effect of the flocculant by bubbles in the vicinity of the water surface.

It is a front view which shows the structure and operation | movement of the pollution prevention apparatus by one embodiment of this invention. It is a schematic explanatory drawing which illustrates the usage pattern of the pollution control apparatus of FIG. 1, and has shown the mode of use seen from the sky of the target water area. It is a figure which shows one modification about the gas holding body of the pollution control apparatus of FIG. 1, (a) is the perspective view seen from the upper surface, (b) is front sectional drawing. It is a schematic explanatory drawing which illustrates the usage form of the pollution prevention apparatus by another embodiment of this invention.

  FIG. 1 is a front view showing the configuration and operation of a pollution control device according to an embodiment of the present invention. FIG. 2 is a schematic explanatory view illustrating the usage pattern of this pollution control device, and shows a state of use viewed from above the target water area. The pollution prevention apparatus 101 is an apparatus for removing the pollution of the underwater 3 in the target water area 67 (FIG. 2) that is the target of the pollution removal using the flocculant 19 and the bubbles 17. The target water area 67 is, for example, a lake, a pond, a river, a dam lake, and a harbor. In particular, the pollution prevention apparatus 101 is configured such that the water surface 11 is formed in the water 3 and the flocculant 19 is effectively stirred on the water surface 11 in the water 3 or in the vicinity thereof. That is, the pollution preventing apparatus 101 includes the gas holding body 5, the string body branching section 13, the string body trunk section 15, the liquid pipe 31, the gas pipe 33, and the mount 35.

  The gas holder 5 is a film body having a substantially hemispherical shape as a whole, and is used in the water 3 of the target water area 67. The film body is, for example, a cloth or a flexible plastic sheet, so that the gas holding body 5 can be folded. A string branch portion 13 is connected to the peripheral edge of the gas holder 5. In the example of FIG. 1, the tip end portions of the cord body branching portion 13 that is a bundle of cord bodies are connected to eight places at equal intervals. The other end portion of the string body branching portion 13 is connected to a string body trunk that is a single string body. The string base part 15 may be one in which a bundle of string bodies forming the string branch part 13 is twisted together. The string body is, for example, a rope. The gas holding body 5, the string body branching section 13, and the string body trunk section 15 illustrated in FIG. 1 form a parachute shape as a whole. In the gas holder 5 of FIG. 1, a plurality of curves extending radially from the zenith toward the periphery like the umbrella bone of the umbrella are sewn to the joints of the membrane bodies or the membrane bodies to reinforce the membrane bodies, Or the pasted linear or strip-shaped reinforcing material is shown. Such a reinforcing material may be omitted.

  The gantry 35 has a constant weight and is used by being submerged in the bottom 37 of the target water area 67. The gantry 35 has a winder 25 that winds the string core 15 so as to be rewound. Thereby, the string main part 15 is supported by the mount 35 in the wound part. The winder 25 has, for example, an electric motor or a pneumatic actuator (not shown) that operates in water, and is remotely operated from the shore 51 of the target water area 67 or the work ship 59 (FIG. 2) floating on the water surface 1. Thus, the string main body 15 can be wound and rewound to a desired degree. The power cable and control wiring for operating the electric motor, or the air piping for operating the pneumatic actuator can be disposed along the bottom 37 or the water surface 1 from the shore 51 to the mount 35, for example.

  The gantry 35 further includes suspension rings 27 and 29 attached to the upper surface of the main body, for example. The suspension rings 27 and 29 are connected to one end of a rope or the like (not shown), and the rope 35 is pulled up or pulled down on the work boat 59 to pull the gantry 35 from the bottom 37 or sink it into the bottom 37. It is possible to do. By moving the work boat 59 along the water surface 1 while the gantry 35 is pulled up from the water bottom 37, the gantry 35 can be disposed on the water bottom 37 at a desired position in the target water area 67. Thus, the gantry 35 is movable.

  One end of a gas pipe 33 and a liquid pipe 31 is further attached to the gantry 35. The other end of the gas pipe 33 is connected to, for example, a gas delivery pump 53 temporarily installed on the shore 51. The gas delivery pump 53 sends gas, for example, air, into the gas pipe 33. The fed air is discharged into the water 3 as bubbles 17 from a discharge port 23 formed at the tip of one end of the gas pipe 33, for example. Note that the term “one end” of the gas pipe 33 and the liquid pipe 31 is used in a broad sense that allows the vicinity of one end as illustrated in FIG.

  The other end of the liquid pipe 31 is connected to a liquid delivery pump 55 temporarily installed on the shore 51, for example. Connected to the liquid delivery pump 55 is a solution supply device 57 that supplies a solution containing a flocculant to the liquid delivery pump 55. Thereby, the liquid delivery pump 55 sends the solution containing the flocculant into the liquid pipe 31. The aggregating agent is a drug that agglomerates and precipitates 3 pollutants in water, and various types are well known. The sent solution is discharged into the water 3 from the discharge port 21 formed at the tip of one end of the liquid pipe 31, for example.

  Even if the connection between the gas pipe 33 and the gas delivery pump 53 and the connection between the liquid pipe 31, the liquid delivery pump 55 and the solution supply apparatus 57 are made when the pollution prevention apparatus 101 is used, the pollution prevention apparatus. It may be already connected at the time of manufacturing and shipping 101. In addition, as illustrated in FIG. 2, the gas pipe 33 may sink in water and extend along the water bottom 37, but may be disposed so as to float on the water surface 1. Depending on the weight of the gas pipe 33, any of them can be adopted. For example, when the gas pipe 33 is made of a light material, the specific gravity is lightened by the internal cavity and floats on the water surface 1. In this case, the gas pipe 33 may be submerged in the water bottom 37 by attaching a weight (weight) such as a metal chain along the gas pipe 33. The same applies to the liquid pipe 31.

  The flocculant 19 released into the water 3 in the form of a solution rises on the rising water stream formed by the released bubbles 17. The solution discharge port 21 is preferably located above the gas discharge port 23 as illustrated in FIG. Thereby, the released flocculant 19 is more effectively carried by the water flow formed by the bubbles 17.

  The discharged flocculant 19 rises together with the bubbles 17 and reaches the inside of the gas holder 5 through an opening opened below the gas holder 5. The bubbles 19 are accumulated to form a gas chamber 7 inside the gas holder 5. The gas chamber 7 imparts buoyancy to the gas holder 5. Thereby, the gas holding body 5 tends to float in the water 3. The gantry 35 supports the gas holding body 5 in water by applying a tension against the buoyancy to the string main body 15. The gas holding body 5 forms a body like a parachute held in the water 3 in an opened state as illustrated in FIG. 1 by forming the gas chamber 7. The gantry 35 has a weight sufficient to resist the buoyancy of the gas holder 5.

  Before the bubbles 17 are released, the gas chamber 7 is not formed in the gas holder 5. When the gas holder 5 is submerged in the water 3 together with the gantry 35, the gas holder 5 is submerged, for example, so as to cover the discharge port 23 of the gas pipe 33. Thereby, the gas chamber 7 is formed in the gas holding body 5 by the discharge of the bubbles 17, and the gas holding body 5 is lifted until the tension from the gantry 35 is reached. On the other hand, when the gas holder 5 is submerged in the water 3, the gas chamber 7 may be formed in advance before the bubbles 17 are released by holding the air inside the gas holder 5. Is possible. In this case, before the bubbles 17 are released, the gas holder 5 is already in a floating state in water.

  The released bubbles 17 rise in the water 3 and are repelled on the water surface 11 formed in the water 3 by the gas chamber 7. The flocculant 19 rising with the bubbles 17 reaches near the water surface 11. Thus, the flocculant 19 is effectively agitated in the water near the water surface 11 by the bubbles 17 repelling on the water surface 11. Thereby, pollution is efficiently removed in the water below the water surface 1 of the target water area 67.

  After a sufficient amount of gas chambers are formed in the gas holder 5, the water level of the water surface 11 formed inside the gas holder 5 is in the vicinity of the periphery of the gas holder 5 as illustrated in FIG. To position. At this time, when the bubbles 17 are supplied to the inside of the gas holding body 5, the overflowing gas becomes bubbles 9 and leaks into the water 3 from the periphery of the gas holding body 5. FIG. 2 illustrates a state in which bubbles 9 appear on the water surface 1 at the work position 61 where the gas holder 5 is installed and the decontamination is performed. The water level of the water surface 11 formed on the inner side of the gas holding body 5 is formed by forming the film body of the gas holding body 5 with a cloth having a certain degree of air permeability or by forming a vent hole in the film body. It is also possible to hold at a position higher than the peripheral edge. Thereby, the position in the water 3 of the gas holding body 5 can be stabilized more.

  The gas holder 5 can be raised or lowered by driving the winder 25 while releasing the bubbles 17 and the flocculant 19 into the water 3. Thereby, the depth of the water surface 11 can be changed. By operating the winder 25, the depth of the water surface 11 can be changed continuously or stepwise. In this way, by changing the depth of the water surface 11 where the stirring of the flocculant is effectively performed, it becomes possible to efficiently remove the contamination at various depths in the water 3. Further, by moving the gantry 35, it is possible to remove the contamination at various positions in the target water area 67. Thus, by removing the bubbles 17 and the flocculant 19 into the water 3 while changing the depth and position, it is possible to efficiently remove the contamination of the target water area 67.

  FIGS. 3A and 3B are views showing a modification of the gas holder 5 of the pollution control apparatus 101, wherein FIG. 3A is a perspective view seen from above, and FIG. 3B is a front sectional view. The gas holding body 5 </ b> A has a bag body 45 formed in a part of the film body 47. The material of the film body 47 is the same as the material of the film body of the gas holding body 5, for example, and the material of the bag body 45 is the same as the material of the film body 47, for example. The bag body 45 is formed radially so as to extend along the radial direction from the center. In the example of FIG. 3, six branch portions extending radially are formed. The bag body 45 is formed in a bag shape capable of holding gas therein, and the inside communicates with each other between the six branch portions extending radially. A gas stopper 41 is connected to the central portion of the radial bag body 45 to allow gas such as air to be taken into and out of the bag body 45. The gas stopper 41 can supply the gas to the bag body 45 through the gas stopper 41 and then close the stopper to prevent the gas from leaking, or the stopper can be opened to extract the internal gas. The gas stopper 41 may realize such a function by having a check valve, for example.

  By supplying gas, for example, air, to the radially formed bag body 45, the gas holding body 5A can be developed. As illustrated in FIG. 3, the expanded gas holder 5 </ b> A forms a body similar to a state in which an umbrella having a radial bag body 45 as a main bone is opened. As described above, the gas holder 5A can be introduced into the water 3 in a developed state. Therefore, the gas holding body 5A is already deployed in the water 3 before the discharge of the bubbles 17 into the underwater 3 is started, and in addition, the gas holding body 5A floats in the water 3 due to the buoyancy caused by the swelling of the bag body 45. It is possible to wait for the rise. The gas holder 5A can be folded after use by extracting the gas from the gas stopper 41, similarly to the gas holder 5 (FIG. 1). For this reason, the gas holder 5A is not inferior to the gas holder 5 in terms of convenience of transportation and storage.

  Although FIG. 3 shows an example in which the vent hole 43 is formed near the center of the film body 47, that is, near the zenith, the vent hole 43 may not be formed. Further, the bag body 45 may not be completely airtight, and may be formed of, for example, a cloth having some air permeability. Even in this case, since the bag 45 holds the supplied gas for a certain period of time, the gas holder 5 </ b> A can maintain the expanded state in the water 3 if the bubble 17 starts to be released during that time. it can. The phrase “holding gas” by the bag body 45 includes a form of holding gas over a certain period of time.

  FIG. 4 is a schematic explanatory view illustrating the usage pattern of the pollution control device according to another embodiment of the present invention. This pollution prevention device 102 has a configuration in which the gas pipe 33 and the liquid pipe 31 are integrated into a single fluid pipe 77 in the pollution prevention device 101. That is, the pollution prevention apparatus 102 includes a fluid pipe 77 instead of the gas pipe 33 and the liquid pipe 31. For example, one end of the fluid pipe 77 is supported by the gantry 35 and a fluid discharge port is formed at the tip of the one end (not shown). The other end of the fluid pipe 77 is connected to the fluid delivery pump 71. The fluid delivery pump 71 is connected to the fluid delivery pump 71 which supplies a fluid mixture of a gas such as air and a solution containing a flocculant. The mixed fluid supply device 73 is further connected to a solution supply device 75 that supplies the mixed fluid supply device 73 with a solution containing a flocculant. Even if the connection between the fluid piping 77 and each of the devices 71, 73, 75 is performed when the pollution prevention device 102 is used, it is already connected at the time of manufacture and shipment of the pollution prevention device 102. There may be. Further, the fluid pipe 77 may be used by being submerged in the water bottom 37 or may be used by being floated on the water surface 1. This is the same as the gas pipe 33 and the liquid pipe 31.

  In the pollution prevention device 102 configured as described above, a fluid mixture of a gas such as air and a solution containing a flocculant is supplied to the fluid pipe 77. The supplied mixed fluid is discharged into the water 3 (see FIG. 1) from a fluid discharge port (not shown) formed at the tip of one end of the fluid pipe 77, for example. The gas contained in the mixed fluid becomes bubbles 17 and is released into the water 3. The flocculant 19 contained in the solution in the discharged mixed fluid rises in the water 3 together with the bubbles 17.

  In the pollution prevention devices 101 and 102, the flocculant 19 was released into the water 3 immediately below the water surface 11 formed by the air chamber 7, as with the bubbles 17. In contrast, the flocculant 19 may be released directly to the water surface 11 where stirring of the flocculant 19 is most effectively performed. For example, a solution containing the flocculant 19 may be poured from the gas chamber 7 above the water surface 11 toward the water surface 11. In order to pour a solution onto the water surface 11, a liquid pipe 31 for supplying the solution is attached to the gas holder 5 so that one end of the liquid pipe 31 penetrates the gas holder 5, for example, and the solution is discharged from the tip of the one end. Can be. Alternatively, a float (not shown) that is in the gas chamber 7 and floats on the water surface 11 may be prepared, and one end of the liquid pipe 31 may be attached to the float.

  In the above embodiment, the gas holders 5 and 5A are mainly composed of a film body, but may be configured as a hard container having one end opened, for example, a metal container. Further, such a container may be supported by the gantry 35 through a telescopic telescopic rod-like body instead of the string bodies 13 and 15. The stretchable rod-like body is driven by an actuator or the like.

  In the above embodiment, the discharge ports 21 and 23 of the liquid pipe 31 and the like are formed at the tip of one end of the liquid pipe 31 and the like. On the other hand, you may form the discharge ports 21 and 23 as a hole arranged in the side surface of one end parts, such as the liquid piping 31, for example.

DESCRIPTION OF SYMBOLS 3 Underwater 5,5A Gas holding body 7 Gas chamber 11 Water surface 13 String body branch part 15 String body trunk part 17 Bubble 19 Coagulant 21, 23 Release port 25 Winding machine 31 Liquid pipe 33 Gas pipe 35 Mount 37 Water bottom 51 Shore 53 Gas delivery pump 55 Liquid delivery pump 57 Solution supply device 67 Target water area 41 Gas plug 45 Bag body 47 Film body 71 Fluid delivery pump 73 Mixed fluid supply device 75 Solution supply device 77 Fluid piping 101, 102 Pollution prevention device

Claims (9)

A gas holder having an opening and capable of holding gas in water;
Support means for supporting the gas holder in water so that the opening faces downward;
Bubble releasing means for releasing bubbles in the water below the supported gas holder;
An anti-contamination device, comprising: a flocculant releasing means for releasing the flocculant into a water surface formed on the inside of the supported gas holder or in water below the water surface. The gas holder is mainly composed of a film body and can be folded.
The support means is a string body having a trunk portion and a branch portion branched into three or more at one end thereof, and a distal end portion of the branch portion is connected to a peripheral portion of the opening portion of the gas holding body The pollution prevention device according to claim 2, further comprising: a string body that is formed, and a gantry that supports a part of the trunk portion of the string body by being submerged in a water bottom.   The pollution control device according to claim 2, wherein the gantry supports the trunk portion of the string body so as to be capable of being drawn out and retracted.   The gas holding body includes a bag body that is radially formed along three or more radial directions from the center and communicates with each other, and a gas stopper that allows gas to be taken in and out of the bag body. Item 4. The pollution control device according to Item 2 or 3. The bubble releasing means includes a gas pipe whose one end is supported by the gantry, and a gas delivery means for sending gas into the gas pipe,
The pollution preventing device according to any one of claims 2 to 4, wherein the gas pipe is formed with a discharge port for discharging bubbles at the one end. The flocculant releasing means includes a liquid pipe whose one end is supported by the gantry, and a solution delivery means for sending a solution containing the flocculant into the liquid pipe,
The pollution control device according to any one of claims 2 to 5, wherein the liquid pipe is formed with an outlet for discharging the solution at the one end of the liquid pipe. The bubble releasing means and the flocculant releasing means include a fluid pipe having one end supported by the mount, and a mixed fluid sending means for sending a mixed fluid of a gas and a solution containing the flocculant into the fluid pipe. Including
The pollution preventing device according to any one of claims 2 to 4, wherein the fluid pipe is formed with a discharge port for discharging the mixed fluid at the one end of the fluid pipe. A gas holding body having an opening and capable of holding a gas in water, placing the opening downward in the water; and
Discharging bubbles into the water below the gas holder disposed in water;
A fouling prevention method comprising: releasing a flocculant into a water surface formed inside or below the water formed inside the gas holder disposed in water.   The pollution prevention method according to claim 8, wherein the bubbles are released and the flocculant is supplied while changing the depth of the gas holder in water stepwise or continuously.

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