JP2010264449A - Flotation separation apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flotation separation apparatus without bursting an air bubble floating on the surface, further repeatedly mixing treated water with a polluted matter and having the possibility of mixing the treated water with the floated polluted matter even if the floated polluted matter descends in the apparatus for obtaining stable treated water having water quality of a fixed value or lower even if the amount of the polluted matter included in water to be treated fluctuates. <P>SOLUTION: The flotation separation apparatus comprises a flotation separation tank 1 including an air bubble contact area 10 for carrying out flotation separation treatment of the water to be treated 17, a gas-liquid separation area 5 for separating a bubble layer and the treated water 11 subjected to the flotation separation treatment in the air bubble contact area 10, and a treated water transfer area 6 for transferring the treated water 11 outside the flotation separation tank 1. In the flotation separation apparatus, the pressure in a space 9 on the surface where the polluted matter 8 separated by the flotation separation treatment floats and temporarily remains is increased higher than atmospheric pressure, and also the treated water is repeatedly introduced into the air bubble contact area 10 through a circulation pass 21 by a circulation pump 20. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a water treatment apparatus, and more particularly to a flotation separation apparatus using fine bubbles.

  A floating separation device such as a foam separation device is a device that separates and removes organic matter dissolved in the treated water and floating fine suspended matter using fine bubbles supplied into the treated water. Air bubbles are supplied, and contaminants such as organic matter and fine suspended matters dissolved in the water to be treated are floated as scum (foam) on the surface of the water to be treated, and the scum (foam) is separated and separated. Processing is performed by discharging to the outside.

  Conventionally, with regard to the improvement of the processing performance in the levitation separator, the structure has been improved so that fine bubbles are supplied into the water to be treated, and the bubbles floating up by the fine bubbles are efficiently separated and discharged from the levitation separation tank. (See Patent Document 1). As shown in FIG. 9, the levitation separation apparatus in this levitation separation method is connected to an introduction pipe 101 for introducing raw water 107 into the inner cylinder 100 below the inner cylinder 100 in the foam separation apparatus 99. An air diffuser 102 that takes in air 113 from the inside and generates fine bubbles 111 inside the inner cylinder 100 is installed. An outer cylinder 103 is installed on the outer side of the inner cylinder 100, and the treated water 110 that has been subjected to foam separation processing in the inner cylinder 100 is configured to flow from the top to the bottom in the outer cylinder 103. An overflow pipe 104 is connected to the lower side of the outer cylinder 103, and a weir 105 that separates the foam and the treated water 110 is provided above the outer cylinder 103. A bubble discharge pipe 106 for discharging the bubble water 108 is provided.

  By configuring as described above, the water level 112 in the foam separating device 99 can be kept constant, and the water level can be kept constant by changing the height of the water surface height adjusting pipe 114 connected to the overflow pipe 104. Since the height from 112 to the weir 105 can be arbitrarily changed, the foam separation device 99 can perform efficient processing.

JP 2001-170617 A

  However, the raw water 107 to be treated by the floating separation device such as the foam separation device 99 often does not have a constant amount of contaminants such as dissolved organic matter and fine suspended solids. Therefore, when processing the raw water 107 with the conventional foam separation device 99, the performance of the foam separation device 99 depends on the contaminant concentration of the raw water 107. When the raw water 107 having a concentration higher than the concentration of the contaminants that can be subjected to the foam separation process is introduced, the contaminants remain in the treated water 110 after the foam separation process, and the quality of the treated water cannot be maintained below a certain value. It was. Further, there is no problem with the problem that the bubbles floating on the water surface, which is a drawback of the foam separation device 99, are ruptured due to pressure release, and some of the contaminants floating along with the bubbles on the water surface are mixed into the treated water again. It was not solved.

  The present invention has been made in view of the above problems, and is an apparatus that can obtain stable treated water having a water quality of a certain value or less even when the amount of contaminants contained in the treated water is increased or decreased. In order to prevent the bubbles floating on the water surface from rupturing, the contaminants will not be mixed into the treated water again, and even if the floated contaminants descend, there is no possibility of mixing in the floating separator. The purpose is to provide.

The levitation separator of the present invention is a levitation separator that separates and removes contaminants from the water to be treated by supplying fine bubbles into the water to be treated and floating the contaminants in the water to be treated.
The surface of the water to be treated in the levitation separation tank is covered with a top plate to form a space above the water surface, and an external pipe is connected to a communication port provided in the space above the water surface. The outlet end portion is submerged in a water tank prepared outside the floating separation tank, so that the space above the water surface is maintained at a pressure higher than atmospheric pressure,
The floating separation treatment is performed by circulating the treated water subjected to the floating separation treatment again into the floating separation tank.

  The present invention has the structure as described above, and the following excellent effects can be obtained.

  (1) By pressurizing the space above the surface of the water, the concentration of contaminants in the treated water can be kept below a certain value even if the concentration of contaminants contained in the treated water increases or decreases, and the treated water is circulated. By making it pass, the treatment performance can be improved by bringing the water to be treated that has not been treated without being brought into contact with fine bubbles once again into contact.

  (2) In addition to (1), the treated water is recirculated to improve the treatment performance by re-contacting the water to be treated which has not been treated without passing through the fine bubbles once again. By pressurizing the upper space, the fine bubbles that float on the surface of the water are less likely to be destroyed, and the concentration of the contaminants in the treated water is kept below a certain value even if the concentration of the contaminants in the treated water increases or decreases. Thus, treated water having a high turbidity removal rate can be obtained.

  (3) Since the bubble contact area and the gas-liquid separation area are arranged one above the other, it is not necessary to provide a separate area for removing very fine bubbles contained in the treated water. It can be made small and the floating separation tank can be made compact.

It is a mimetic diagram of a 1st embodiment of a floating separation device of the present invention. It is a schematic diagram of 2nd reference embodiment of the floating separation apparatus of this invention. It is a schematic diagram of 3rd Embodiment of the floating separation apparatus of this invention. It is a schematic diagram of the floating separation apparatus of the comparative example of this invention. 4 is a graph showing the results of measuring changes in COD in Example 1. It is a graph which shows the result of having measured change of COD in reference example 2. FIG. It is a graph which shows the result of having measured change of COD in Example 3. FIG. It is a graph which shows the result of having measured change of COD in a comparative example. It is a schematic diagram which shows the conventional floating separator.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings, but it goes without saying that the present invention is not limited to these embodiments. FIG. 1 is a schematic view of a first embodiment of a flotation separation apparatus of the present invention. FIG. 2 is a schematic diagram of a second reference embodiment of the floating separation apparatus of the present invention. FIG. 3 is a schematic view of a third embodiment of the floating separation apparatus of the present invention.

[Embodiment 1]
In FIG. 1, reference numeral 1 denotes a floating separation tank, which is a vertical floating separation tank in which a gas-liquid separation area 5 is provided below the bubble contact area 10. In the levitation separation tank 1, a bubble contact area 10 where the water to be treated 17 is subjected to levitation separation processing, a gas-liquid separation area 5 which separates the foam layer and the treatment water 11 which are levitation separation processed in the bubble contact area 10, It is comprised with the treated water transfer area 6 which transfers the treated water 11 out of the floating separation tank 1. Near the middle of the levitation separation tank 1, an introduction port 4 for introducing the treated water 17 from the outside is provided, and a fine bubble generator 2 that supplies fine bubbles to the levitation separation tank 1 below the introduction port 4 is a gantry. (Not shown) is fixed in the water to be treated. An air pipe 3 is connected to the fine bubble generator 2 in order to introduce air from the outside of the floating separation tank 1. Further, a gas-liquid separation area 5 is provided below the fine bubble generating device 2 for reliably separating the contaminant 8 separated from the treated water 17 and the treated water 11. The gas-liquid separation area 5 is configured such that the rising speed of the fine bubbles that have entered the gas-liquid separation area 5 is faster than the flow rate of the treated water 11 passing through the gas-liquid separation area 5. That is, the ascending speed of the fine bubbles in the gas-liquid separation area 5 determines the sum of the circulation flow rate of the water in the levitation separation tank 1 and the flow rate of the treated water 17 flowing into the levitation separation tank 1. The flow rate of the water to be treated 17 with respect to the cross-sectional area of the tank is adjusted to be larger than the value divided by the area.

  On the other hand, a treatment water transfer area 6 for transferring the treated water 11 to the outside is provided at a position adjacent to the gas-liquid separation area 5, and a separation plate in which the lower part of the gas-liquid separation area 5 and the lower part of the treated water transfer area 6 communicate with each other. 16 is partitioned. Further, a weir 7 is provided above the treated water transfer area 6 to keep the water level of the levitation separation tank 1 constant, and a circulation pump 20 is provided below the treated water transfer area 6, The circulation pump 20 and the bubble contact area 10 are in communication with each other.

  In this embodiment, the fine bubble generating device 2 is a self-contained type that is driven by a motor and sucks air through the air pipe 3, but an air diffuser such as a perforated plate can be used as long as it can generate fine bubbles. However, it is not particularly limited.

  On the other hand, on the water surface in the levitation separation tank 1, a water surface space 9 where the contaminants 8 separated by the levitation separation process float and temporarily stay is covered with a top plate 19. A communication port 12 for conveying the separated pollutant 8 generated at any time to the outside is provided above the. Furthermore, an external pipe 13 is connected to the communication port 12, and the separated contaminant 8 is configured to be transferred to the outside of the floating separation tank 1.

  In the present embodiment, the communication port 12 is provided in the upper part of the gas-liquid separation area 5. However, the communication port 12 is located in the water surface space 9 of the floating separation tank 1, and the polluted matter 8 that has floated and separated is placed in the water surface space 9. There is no particular limitation as long as it is provided so as to be discharged.

  The outlet end portion of the external pipe 13 is set to be submerged in a polluted concentrated water 15 contained in a separately prepared water tank 14. Further, the water tank 14 is provided with a pollutant transfer port 18.

  Hereinafter, the operation of the present embodiment will be described with reference to FIG. The treated water 17 subjected to the floatation separation process is introduced into the bubble contact area 10 in the floatation separation tank 1 from the introduction port 4 provided in the floatation separation tank 1. The pollutant 8 in the water to be treated 17 moves upward along with the water to be treated 17 in the bubble contact area 10 when the fine bubbles generated by the fine bubble generator 2 are attached. When the water to be treated 17 and the pollutant 8 reach the vicinity of the water surface in the floating separation tank 1, the pollutant 8 to which fine bubbles in the water to be treated 17 adhere is floated on the water surface and separated from the water to be treated 17. The The treated water 17 from which the contaminants 8 have been separated descends as the treated water 11 outside the bubble contact area 10. The treated water 11 proceeds downward toward the gas-liquid separation area 5 provided below the fine bubble generator 2 and passes through the gas-liquid separation area 5. Compared to the horizontal levitation separation tank, the bubble contact area 10 and the gas-liquid separation area are arranged vertically so that an area for removing very fine bubbles can be provided separately by using a partition plate. Since there is no need to do this, there is an effect that the installation area of the floating separation tank 1 can be reduced. The treated water 11 that has passed through the gas-liquid separation area 5 flows over the weir 7 through the treated water transfer area 6, and flows out of the floating separation tank 1. On the other hand, a part of the treated water 11 in the treated water transfer area 6 is again introduced into the bubble contact area 10 through the circulation path 21 by the circulation pump 20 and repeatedly floated and separated.

  When the treated water is introduced again into the bubble contact area 10 via the circulation path 21 by the circulation pump 20, the flow rate of the water in the tank flowing downward is increased to raise the fine bubbles in order to raise the contaminants by the fine bubbles. It is set to be slower than the speed.

  On the water surface of the bubble contact area 10, the contaminants 8 that are separated from the water to be treated 17 by the action of fine bubbles form a foam layer on the water surface of the water to be treated 17. As long as the treated water 17 continues to be introduced into the floating separation tank 1, the foamed layer is pushed up above the water surface space 9 because the separated contaminants 8 float up. On the other hand, above the water surface space 9, the separated contaminants 8 are guided toward the communication port 12 by the top plate 19 disposed obliquely in the floating separation tank 1. By such an arrangement of the top plate 19, the separated and separated contaminants 8 are collected in the vicinity of the communication port 12 so as to be pushed up by the separated and separated contaminants 8 that rise from below. In addition, if the nature of the floating contaminants 8 is a scum that is difficult to rise and stays on the surface of the water, a discharge trough (not shown) is provided on the surface of the water so that it is scraped and discharged by a scraper or the like. It may be.

  The pollutant 8 separated and collected in the vicinity of the communication port 12 in this way is pushed out to the external pipe 13 through the communication port 12, transferred to a separately prepared water tank 14, and discharged from the floating separation tank 1. . At this time, the pressure of the water surface space of the water to be treated 17 can be easily increased / decreased by changing the water immersion depth at the outlet side end of the external pipe 13, and the contaminant 8 transferred through the external pipe 13 is By being pushed into the polluted concentrated water 15 accumulated in the water tank 14 through the outlet of the external pipe 13 by the pressure that is equal to or higher than the pressure held in the water surface space 9, it is outside the system of the floating separation tank 1. Will be pushed out.

  Moreover, when the pressure of the water surface space 9 in the levitation separation tank 1 is increased, the water level in the bubble contact area 10 in the levitation separation tank 1 is pushed down by the pressure of the water surface space 9, so If the space 9 is pressurized too much, the water level in the bubble contact area 10 is pushed down to a position where the fine bubble generating device 2 is exposed, so that no fine bubbles are generated and the floating separation process is not performed. Therefore, the pressure applied to the water surface space 9 must be equal to or lower than the pressure at which the bubble contact area 10 is formed, that is, equal to or lower than the pressure within a range where the bubble generating action can be performed. Furthermore, it is desirable that the pressure applied to the water surface space 9 is 1 kPa or more so that fine bubbles floating on the water surface are not exposed to rapid pressure release. On the other hand, when flotation separation is performed in a batch-type flotation separation tank (not shown), when a pressure higher than the air pressure that can be supplied by the fine bubble generating device 2 is applied to the water surface space 9, the fine bubble generating device 2 is used. Since the fine bubbles are not supplied, and the floating separation itself is not performed, the pressure held in the water surface space 9 is preferably less than the air pressure that can be pressurized by the fine bubble generator 2.

  By making the water surface space 9 higher than the atmospheric pressure in this way, the separated pollutant 8 has risen because it does not receive a sudden pressure release when it floats on the water surface. The separated contaminants 8 form a foam layer without breaking the bubbles that are levitated and fixed on the water surface.

  Further, by providing the circulation pump 20 and the circulation path 21 so as to treat the treated water 11 again, the opportunity to float and separate very fine bubbles contained in the treated water 11 is increased. Even if the amount of contaminants contained in the water to be treated 17 increases or decreases, treated water having a concentration of the contaminants below a certain value can be obtained.

[Reference Embodiment 2]
Next, a second reference embodiment of the floating separation apparatus of the present invention will be shown. In FIG. 2, reference numeral 22 denotes an upward substantially shade-shaped shielding plate having a communication hole, and two are provided in the bubble contact area 10 above the fine bubble generating device 2 in the floating separation tank 1. It arrange | positions so that the inside of 1 may be divided up and down. In the present embodiment, two upward substantially shade-shaped shielding plates 22 having communication holes are disposed, but at least one is sufficient, and the number is not particularly limited.

  The same as in the first embodiment except that an upward substantially shade-shaped shielding plate 22 having a communication hole is provided in the levitation separation tank 1 and that the circulation pump 20 and the circulation path 21 are not installed. Since there is, explanation is omitted.

  Hereinafter, the operation of the present embodiment will be described with reference to FIG. The treated water 17 subjected to the floatation separation process is introduced into the bubble contact area 10 in the floatation separation tank 1 from the introduction port 4 provided in the floatation separation tank 1. The pollutant 8 in the water to be treated 17 moves upward along with the water to be treated 17 in the bubble contact area 10 when the fine bubbles generated by the fine bubble generator 2 are attached. On the other hand, when it reaches the vicinity of the water surface, the contaminant 8 to which bubbles are attached floats on the water surface, and the water to be treated 17 descends outside the bubble contact area 10. At this time, the fine pollutant 23 among the pollutants 8 is not lifted up and descends together with the water to be treated 17. In order to prevent the fine contaminants 23 riding on such a downward flow from descending, the bubble contact area 10 is defined so that an upward substantially shade-shaped shielding plate 22 having a communication hole defines the bubble contact area 10. Is provided. Due to the upward substantially shade-shaped shielding plate 22 having the communication hole, the fine contaminants 23 that have descended together with the treated water 17 do not descend to the gas-liquid separation area 5, and the flow of the treated water 17 that rises again. Therefore, there is no risk of being mixed into the treated water 11.

  On the other hand, the treated water 11 from which the contaminants 8 have been removed proceeds downward in the gas-liquid separation area 5 provided below the fine bubble generating device 2 and passes through the gas-liquid separation area 5, whereby the treatment water 11 is removed. Fine bubbles contained in the water 11 are reliably separated. By arranging the bubble contact area 10 and the gas-liquid separation area 5 above and below, the rising speed of the fine bubbles is always faster than the descending flow rate of the treated water 11, and the pollutant 8 always has upward buoyancy due to the fine bubbles. As a result, the contaminant 8 hardly falls to the gas-liquid separation area 5. Therefore, the effect that the height of the gas-liquid separation area 5 can be made low and the foam separation tank 1 can be made compact is produced. The treated water 11 that has passed through the gas-liquid separation area 5 flows over the weir 7 through the treated water transfer area 6, and flows out of the floating separation tank 1.

  Hereinafter, the method for transferring the separated contaminants 8 and the method for pressurizing the water surface space 9 are the same as those in the first embodiment, and thus the description thereof is omitted.

  By making the water surface space 9 higher than the atmospheric pressure in this way, the separated pollutant 8 is not subjected to a rapid pressure release when it floats on the surface of the water 17 to be treated. Therefore, the separated contaminant 8 that has floated up forms a foam layer without breaking the bubbles that float and fix the separated contaminant 8 on the water surface. Furthermore, by providing the upward substantially shade-shaped shielding plate 22 having communication holes so that the bubble contact area 10 is partitioned, it is possible to prevent the fine contaminants 23 from descending to the treated water transfer area 6. By acting in this way, the separated pollutant 8 is not mixed with the treated water 11 again, the treatment performance becomes extremely higher than before, and the pollutant contained in the treated water 17 increases or decreases. However, treated water with a contaminant concentration below a certain value can be obtained.

[Embodiment 3]
Next, a third embodiment of the levitation separator of the present invention will be shown. In FIG. 3, reference numeral 22 denotes an upward substantially shade-shaped shielding plate having a communication hole, which is provided in two bubble contact areas 10 above the fine bubble generating device 2 in the floating separation tank 1. It arrange | positions so that the inside of 1 may be divided up and down. In the present embodiment, two upward substantially shade-shaped shielding plates 22 having communication holes are disposed, but at least one is sufficient, and the number is not particularly limited.

  Since it is the same as 1st Embodiment except having provided the upward substantially shade-shaped shielding board 22 which has a communicating hole in the floating separation tank 1, description is abbreviate | omitted.

  Hereinafter, the operation of the present embodiment will be described with reference to FIG. The treated water 17 subjected to the floatation separation process is introduced into the bubble contact area 10 in the floatation separation tank 1 from the introduction port 4 provided in the floatation separation tank 1. The contaminant 8 in the water to be treated 17 moves upward in the bubble contact area 10 by the fine bubbles generated by the fine bubble generator 2. On the other hand, the water to be treated 17 introduced into the levitation separation tank 1 rises with the bubbles, and when reaching the water surface, the contaminants 8 containing the bubbles float on the water surface, and the water to be treated 17 is in the bubble contact area 10. It will descend inside. At this time, among the contaminants 8, the fine contaminants 23 and the contaminants 24 that have lost their buoyancy due to the bursting of bubbles are not lifted up and move down together with the water to be treated 17. In order to prevent the fine pollutant 23 riding on the descending flow or the pollutant 24 losing buoyancy from descending, the bubble contact area 10 is provided with an upward substantially shade-shaped shielding plate 22 having a communicating hole. It is provided so as to partition the contact area 10. Due to the upward substantially shade-shaped shielding plate 22 having the communication hole, the fine contaminants 23 that have descended together with the treated water 17 do not descend to the gas-liquid separation area 5, and the flow of the treated water 17 that rises again. Therefore, there is no risk of being mixed into the treated water 11.

  Further, by providing the circulation pump 20 and the circulation path 21 so as to treat the treated water 11 again, the opportunity to float and separate very fine bubbles contained in the treated water 11 is increased. Even if the amount of contaminants contained in the water to be treated 17 increases or decreases, treated water having a concentration of the contaminants below a certain value can be obtained.

  Hereinafter, the method for transferring the separated contaminants 8 and the method for pressurizing the water surface space 9 are the same as those in the first embodiment, and thus the description thereof is omitted.

  In this way, the upward substantially shade-shaped shielding plate 22 having a communication hole in the center is provided so as to partition the bubble contact area 10, and a part of the treated water 11 is circulated to the bubble contact area 10 again. When the separated contaminant 8 floats on the surface of the water 17 to be treated, the above-described space 9 in the floating separation tank 1 can be maintained at a pressure higher than atmospheric pressure. The separated pollutant 8 that has risen due to the descending flow of the water to be treated 17 is not lowered and mixed into the treated water 11, and a part of the treated water 11 is again brought into the bubble contact area using the circulation pump 20. By circulating to 10, there is an increased chance that the contaminant 8 mixed in or remaining in the treated water 11 is also levitated and separated, and even if fine bubbles adhering to the contaminant 8 reach the water surface, a sudden pressure is applied. Do not open Since, it is possible to stay on the water surface of the flotation tank 1 without losing buoyancy. By acting in this way, the separated pollutant 8 is hardly mixed with the treated water 11 again, the treatment performance becomes extremely higher than before, and the pollutant contained in the treated water 17 increases or decreases. Even so, treated water having a concentration of contaminants below a certain value can be obtained.

  An evaluation experiment was performed using the devices of the first embodiment (Example 1), the second reference embodiment (Reference Example 2), and the third embodiment (Example 3) of the present invention. The results are shown below. The test apparatus was implemented using the apparatus shown in the figure corresponding to each embodiment. As the treated water 17 to be introduced, cargo wastewater actually generated from the fish market was used. The treatment performance was confirmed by measuring and comparing the chemical oxygen consumption (COD) for the treated water of the Examples, Reference Examples and Comparative Examples and the treated water. The test conditions were such that the pressure applied to the water surface space 9 was increased by 1.0 kPa from atmospheric pressure, and the amount of circulating water was the same as the amount of circulating water with respect to the water to be treated 17. In addition, it performed using the thing which does not pressurize at all as a comparative example, does not install the shielding board 22 which has a communicating hole, and also does not circulate a treated water. A schematic diagram of a flotation separation apparatus of a comparative example is shown in FIG.

  FIG. 5 is a graph showing the results of measuring changes in COD concentration in Example 1. FIG. 6 is a graph showing the results of measuring the change in COD concentration in Reference Example 2. FIG. 7 is a graph showing the results of measuring changes in COD concentration in Example 3. FIG. 8 is a graph showing the results of measuring the change in the COD concentration of the comparative example.

  The COD concentration of the water to be treated 17 and the water to be treated 11 was measured based on the amount of oxygen consumed by alkaline potassium permanganate according to JIS K 010219.

Each condition of the test apparatus is as follows.
Flotation separation tank 1: Effective volume 15L, fine bubble generator 0.04kw, water depth in the tank 90cm
Water tank 14: Effective volume 45L, water depth in water tank 50cm, pressure with transfer port: 1kPa
Pressure measurement in the space 9 above the water surface: a manometer connected to the top plate 19 and a shielding plate 22 having a measurement communication hole due to a water head difference: installed amount of treated water introduced at positions 40 cm and 60 cm from the bottom of the floating separation tank 1: 30L / hr

  As a comparative example, the same measurement was performed without submerging the external piping, without performing circulation, and without using a shielding plate having an upward communication hole.

  In Example 1, Reference Example 2 and Example 3, the COD concentration of the treated water fluctuates between about 50 to 70 mg / L, but the COD concentration of the treated water is stable at around 30 mg / L. Yes. Therefore, it can be seen that the COD concentration of the treated water 11 is stable regardless of the fluctuation of the COD concentration of the treated water 17. On the other hand, in the comparative example, when the COD concentration of the water to be treated fluctuates between 50 and 70 mg / L, it can be seen that the COD concentration of the treated water also increases to around 30 to 45 mg / L.

  Similarly, in the treated water treated in Example 1, Reference Example 2, Example 3 and Comparative Example, turbidity was measured by a nephrometric method using a portable 2100P turbidimeter manufactured by HACH. As shown in Table 1, the turbidity removal rate of Example 3 was high, about 75%. Next, Example 1 and Reference Example 2 had the same degree, which was around 43%. In the comparative example, the removal rate was 11%, and the turbidity was hardly removed.

DESCRIPTION OF SYMBOLS 1 Floating separation tank 2 Fine bubble generator 3 Air pipe 4 Inlet 5 Gas-liquid separation area 6 Processed water transfer area 7 Weir 8 Pollutant 9 Water surface space 10 Bubble contact area 11 Processed water 12 Communication port 13 External piping 14 Water tank 15 Contaminated water 16 Separator plate 17 Water to be treated 18 Contaminant transfer port 19 Top plate 20 Circulating pump 21 Circulating path 22 Upward substantially shade-shaped shielding plate having communication holes 23 Fine contaminant 24 Contaminated material 99 which has lost buoyancy 99 Foam Separator 100 Inner cylinder 101 Inlet pipe 102 Aeration pipe 103 Outer cylinder 104 Overflow pipe 105 Weir 106 Foam discharge pipe 107 Raw water 108 Sewage water 109 Mount 110 Treatment water 111 Fine bubbles 112 Water level 113 Air 114 Control pipe

Claims (1)

In the floating separation device for separating and removing the contaminants from the treated water by supplying fine bubbles into the treated water and floating the contaminants in the treated water,
The surface of the water to be treated in the levitation separation tank is covered with a top plate to form a space above the water surface, and an external pipe is connected to a communication port provided in the space above the water surface. The outlet end portion is submerged in a water tank prepared outside the floating separation tank, so that the space above the water surface is maintained at a pressure higher than atmospheric pressure,
A flotation separation apparatus characterized in that a flotation separation process is performed by circulating treated water that has undergone flotation separation treatment again into a flotation separation tank.

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