JP4337787B2 - Wastewater treatment method and treatment apparatus - Google Patents

Description

  The present invention relates to a wastewater treatment method and treatment apparatus, and in particular, SS and oily lean wastewater (hereinafter referred to as “lean wastewater”) and SS and / or oily rich wastewater (hereinafter referred to as “rich wastewater”). Wastewater treatment method for reducing the processing cost by reducing the amount of flocculant used in the concentrated wastewater treatment system and further the amount of fine bubbles for flotation separation. And a processing apparatus.

  Conventionally, as a method of treating industrial wastewater such as steel, machinery, oil, fiber, metal, food, leather, laundry, etc., and wastewater from gasoline stations, restaurants, etc., the wastewater is agglomerated and then floated and separated. It has been known. In particular, oil-containing wastewater containing emulsified oil and suspended solid material (SS) cannot be floated and separated as it is. For this reason, after adding an inorganic flocculant such as PAC (polyaluminum chloride) in the coagulation tank and coagulating, it is necessary to float and separate the coagulated water. A method of coagulating, floating and separating dilute waste water and rich waste water separately is known for the coagulation floating separation of the waste water.

The present applicant first performs an efficient agglomeration process as an agglomeration processing apparatus capable of obtaining a uniform and agglomerated floc,
A coagulation treatment tank, a passage through which liquid and sediment pass, at least one partition plate that divides the interior of the coagulation treatment tank into a plurality of chambers in the vertical direction, and each chamber divided by the partition plate Stirring means for stirring the inside, raw water supply path provided at one of the upper and lower ends of the treatment tank for removing the treated water by passing the raw water up and down in the coagulation treatment tank, and the other end A coagulation treatment apparatus (Japanese Patent Laid-Open No. 10-337406) characterized by having a treated water take-out path provided in the section
Proposed.

Moreover, the following apparatus was proposed as a pressure levitation apparatus.
(1) In a pressurized flotation separation device for subjecting water to be treated to flotation separation under pressure,
By dividing the tank body by a partition wall, a mixing chamber and a floating separation chamber are installed,
An outlet for discharging the water to be treated is provided at the bottom of the mixing chamber and near the center in the width direction of the partition;
The partition wall rises from the bottom surface of the tank body, and its upper end is positioned lower than the water surface level of the tank body, whereby water flows out from the mixing chamber to the floating separation chamber through the upper side of the partition wall. And
Of the bottom of the mixing chamber, a pressurized water discharge port is provided near the partition and near the center in the width direction of the partition to discharge pressurized water in which the gas is dissolved upward.
A pressurization flotation separation device (Japanese Patent Application No. 2005-33283), wherein the flotation separation chamber is provided with a means for removing flotation sludge.

(2) A pressurization flotation separation device that performs a flotation separation process in a flotation separation chamber after mixing agglomeration reaction water and pressurized water in a mixing chamber,
By dividing the tank body by a partition wall, a mixing chamber and a floating separation chamber are installed,
The partition wall rises from the bottom surface of the tank body, and its upper end is positioned lower than the water surface level of the tank body, whereby water flows out from the mixing chamber to the floating separation chamber through the upper side of the partition wall. In the pressurized flotation separation device,
A pressurized water discharge port for discharging pressurized water in which gas is dissolved in the mixing chamber;
A pressure flotation separation apparatus (Japanese Patent Application No. 2005-40855), characterized in that an addition means for adding a polymer coagulation aid is provided in the mixing chamber.

In the case of the pressure flotation device described in Japanese Patent Application No. 2005-33283 and Japanese Patent Application No. 2005-40855, bubbles were adhered by mixing with agglomeration treatment water, a polymer flocculant as an agglomeration aid, and fine bubbles in a mixing chamber. Agglomerated flocs can be obtained and efficiently separated into floating scum and separated water in the floating separation chamber. That is, if it is an apparatus described in the above Japanese Patent Application No. 2005-33283 and Japanese Patent Application No. 2005-40855, in the mixing chamber, at the same time as adding the polymer flocculant to the flocculated water, fine bubbles are generated, By mixing by a swirl flow, it is possible to form a bubble-containing floc that contains bubbles firmly inside, and this bubble-containing floc can be efficiently levitated and separated in the levitating separation chamber.
Japanese Patent Laid-Open No. 10-337406 Japanese Patent Application No. 2005-33283 Japanese Patent Application No. 2005-40855

  If it is a method that separates and separates the wastewater into a dilute wastewater and a concentrated wastewater, it can be efficiently treated under optimum conditions for each wastewater. As the amount of pollutants increases, the amount of flocculant necessary for the agglomeration treatment of wastewater also increases, so a large amount of flocculant is required to agglomerate dense wastewater with a high concentration of pollutants such as SS and / or oil. There is a disadvantage that the cost of drugs is high. In addition, the amount of fine bubbles necessary for floating separation is determined by the gas-solid ratio, which is the ratio of the amount of bubbles and the amount of pollutants such as SS and / or oil, so a large amount of fine bubbles is required to float and separate concentrated wastewater. This requires bubbles, which necessitates a large fine bubble generating facility, and has the disadvantage that the overall facility cost and power cost are high.

  The present invention solves the above-mentioned conventional problems, and reduces the amount of flocculant used in the concentrated wastewater treatment system and the necessary amount of fine bubbles when separately separating the concentrated wastewater and the concentrated wastewater. It is an object of the present invention to provide a wastewater treatment method and a treatment apparatus that reduce treatment costs.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the floating scum obtained by the coagulation and flotation of dilute wastewater effectively functions as a flocculant and a flotation aid in the coagulation and flotation of concentrated wastewater. Therefore, the amount of flocculant used in the concentrated wastewater treatment system and the required amount of fine bubbles are greatly increased by adding and mixing the floating scum obtained by the coagulation and floating separation of the lean wastewater to the concentrated wastewater and mixing and floating and separating. I found that it can be reduced.

This invention is made | formed based on such knowledge, and makes the following a summary.
[1] A first flocculation and separation process of flocculating and separating SS and oily lean waste water to obtain floating scum and separated water; and SS and / or oil-rich waste water is flocculated and separated to float scum. And a second flocculation and separation process for obtaining separated water, wherein the floating scum obtained in the first flocculation and separation process is mixed with the SS and / or oil-rich wastewater. The wastewater treatment apparatus that flocculates and separates by flocculation , wherein the SS and oily lean wastewaters have an SS concentration and a normal hexane extractable substance concentration of 10 to 1,000 mg / L and 10 to 1,000 mg / L, respectively. The SS and / or oil-rich wastewater has an SS concentration of 1,000 to 10,000 mg / L and / or a normal hexane extractable substance concentration of 1,000 mg / L to 100,000 mg / L. A method for treating wastewater.
[2] A wastewater treatment method according to [1], wherein the separated water obtained in the second agglomeration floating separation step is mixed with the SS and oily lean wastewater for agglomeration floating separation.
[3] In [1] or [2], a biological treatment step for biologically treating the separated water obtained in the first flocculation / floating separation step; And a third flocculating and flotation step for obtaining separated water, and the flotation scum of the third flocculating and flotation step is mixed with the SS and / or oily concentrated waste water for flocculation and separation. Characterized wastewater treatment method.
[4] In [1] to [3], a floating tank in which a mixing chamber and a floating separation chamber are formed by partitioning the inside of the tank with a partition wall is used in the mixing chamber. A wastewater treatment method comprising mixing wastewater agglomeration treatment water with agglomeration aid and fine bubbles, and separating the wastewater into a flotation scum and separation water in the flotation separation chamber.
[5] In [1] to [4], the separated water obtained in the first aggregation / floating / separation step and / or the third aggregation / floating / separation step is used as water for generating fine bubbles. Wastewater treatment method.
[6] A first agglomeration and flotation separating means for aggregating and flotation of SS and oil-lean wastewater to obtain flotation scum and separated water; and flotation and separation of SS and / or oil-rich wastewater by agglomeration and flotation. And a second flocculating / floating / separating means for obtaining separated water, and a means for feeding the floating scum from the first flocculating / floating / separating means to the second flocculated / floating / separating means. A wastewater treatment apparatus, wherein the SS and the oily lean wastewater have an SS concentration and a normal hexane extractable substance concentration of 10 to 1,000 mg / L and 10 to 1,000 mg / L, respectively, and the SS and / or Rich oily drainage is characterized by an SS concentration of 1,000 to 10,000 mg / L and / or a normal hexane extractant concentration of 1,000 mg / L to 100,000 mg / L. Wastewater treatment equipment.
[7] The wastewater treatment apparatus according to [6] , further comprising means for feeding the separated water from the second flocculating and floating separation means to the first flocculating and floating separation means.
[8] In [6] or [7] , the biological treatment means for biologically treating the separated water from the first flocculating and floating separation means, and the treated water of the biological treatment means are flocculated and floated to separate from the floating scum. 3. A wastewater treatment apparatus comprising: a third agglomeration floating separation means for obtaining water, and the floating scum of the third agglomeration floating separation means is fed to the second agglomeration separation means.
[9] In [6] to [8] , the agglomeration floating separation means forms a mixing chamber and a flotation separation chamber by partitioning the inside of the tank by a partition wall, and agglomeration treated water for drainage is formed in the mixing chamber. A wastewater treatment apparatus comprising: a floating tank that mixes the coagulant with a coagulation aid and fine bubbles and separates the mixed water into a floating scum and separated water in the floating separation chamber.
[10] In [6] to [9] , the separated water obtained by the first flocculating and separating means and / or the third flocculating and separating means is used as water for generating fine bubbles. Processing equipment.

  According to the present invention, the floating scum obtained by the cohesive flotation separation of dilute wastewater is mixed with the concentrated drainage, and by effectively using this flotation scum as a flocculant and a flotation aid in the coagulation flotation separation step of the concentrated drainage, It is possible to reduce the amount of flocculant necessary for the flocculation and floating separation of the concentrated drainage or to eliminate the need for the flocculant and to reduce the amount of fine bubbles for the levitation separation.

  That is, most of the pollutants and flocculants in the agglomerated water obtained by adding a flocculant to dilute wastewater and agglomerating it become floating scum in the next flotation separation step. When the effluent scum is a dilute effluent, a sufficient amount of pollutant adsorbing ability remains, and the levitation scum is a strong flock having a small specific gravity and containing bubbles therein. For this reason, when this floating scum is added to and mixed with concentrated drainage, pollutants in the concentrated drainage are efficiently adsorbed. At that time, even if the floating scum is stirred and mixed with the concentrated drainage in the coagulation tank, since the floating scum is a strong flock, no bubbles are released from the floating scum. Since the levitation scum has a small specific gravity including bubbles, the levitation scum is easily levitated in the next levitation separation step after adsorbing the pollutant.

  In this way, the floating scum obtained by the coagulation flotation separation of dilute wastewater can be used as a flocculant for concentrated drainage and as a flotation aid in place of fine bubbles for flotation separation. The amount of coagulant used in the coagulation treatment step can be greatly reduced, or no coagulant can be required, and the amount of fine bubbles required in the next floating separation step can be reduced.

  For this reason, the amount of coagulant required as a whole can be significantly reduced to reduce the drug cost, and the equipment cost and power cost can be reduced by downsizing the fine bubble generating equipment.

  Embodiments of the wastewater treatment method and treatment apparatus of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a system diagram showing an embodiment of the wastewater treatment method and treatment apparatus of the present invention.

  The lean wastewater is first introduced into the coagulation tank 11 in the dilute wastewater treatment system 10, and an inorganic coagulant such as PAC is added to the coagulation treatment together with the separated water from the concentrated wastewater treatment system 20 described later. The agglomerated water is fed to the levitation tank 12, mixed with the fine bubbles and the polymer flocculant from the fine bubble generator 13 in the mixing chamber 12A, and then floated and separated in the floating separation chamber 12B. The levitation scum from the levitation separation chamber 12B is fed to the coagulation tank 21 of the concentrated wastewater treatment system. On the other hand, a part of the separated water is used as water for generating fine bubbles of the fine bubble generating device 13 and the fine bubble generating device 23 of the concentrated waste water treatment system, and the remaining part is fed to the biological treatment system 30.

  After the fine bubble generating device 13 of the diluted waste water treatment system 10 and the fine bubble generating devices 23 and 33 of the dense waste water treatment system 20 and the biological treatment system 30 described later pressurize the water for generating fine bubbles and dissolve the gas, This is a method of generating fine bubbles by reducing the pressure. In the floating tank 12 of the lean wastewater treatment system 10 and the floating tanks 22 and 32 of the concentrated wastewater treatment system 20 and the biological treatment system 30 described later, the fine bubble generator 13 is used. , 23 and 33, the fine bubbles and the coagulant aid are mixed with the coagulated water at the same time as the fine bubbles are generated.

  In the biological treatment system 30, the separated water from the floating tank 12 of the diluted wastewater treatment system 10 is biologically treated in the biological treatment tank 34, and then an agglomeration tank 31 is added with an inorganic flocculant such as PAC for aggregation treatment. The agglomerated water is fed to the floating tank 32, mixed with the fine bubbles and the polymer flocculant from the fine bubble generating device 33 in the mixing chamber 32A, and then floated and separated in the floating separation chamber 32B. The levitation scum from the levitation separation chamber 32 </ b> B is fed to the agglomeration tank 21 of the concentrated wastewater treatment system 20. On the other hand, since the separated water has a sufficiently high water quality, a part thereof is used as water for generating fine bubbles of the fine bubble generating device 33, and the remaining part is discharged out of the system as treated water.

  The concentrated wastewater is first introduced into the agglomeration tank 22 by the concentrated wastewater treatment system 20, and the inorganic flocculation such as levitation scum from the lean wastewater treatment system 10, levitation scum from the biological treatment system 30, and PAC added as necessary. Coagulated with the agent. The agglomerated water is fed to the floating tank 22, mixed with the fine bubbles and the polymer flocculant from the fine bubble generator 23 in the mixing chamber 22A, and then floated and separated in the floating separation chamber 22B. The floating scum from the floating separation chamber 22B is discharged out of the system. On the other hand, the separated water is supplied to the lean wastewater treatment system 10 and coagulated with the lean wastewater.

  By adding the floating scum of the lean wastewater treatment system 10 and the floating scum of the biological treatment system 30 for treating the separated water of the lean wastewater treatment system 10 to the concentrated wastewater treatment system 20 as described above, As described above, these floating scum can be used as a flocculant and a flotation aid for concentrated drainage, and the amount of inorganic flocculant used in the flocculant tank 21 can be greatly reduced. In some cases, an inorganic flocculant is added. It is also possible to perform the agglomeration process only with the floating scum of the diluted waste water treatment system 10 and the biological treatment system 30. In the levitation tank 22, the amount of fine bubbles necessary for levitation separation can be greatly reduced.

  As the inorganic flocculant to be added to the flocculation tanks 11, 21, 31, inorganic flocculants such as PAC, sulfate band (aluminum sulfate), ferric chloride, ferrous sulfate, ferric sulfate can be used, The amount added is preferably about 0.1 to 10 times, particularly about 5 to 10 times the concentration of pollutants in the water to be agglomerated.

  In addition, as coagulation aids to be added to the levitation tanks 11, 21, 31, poly (meth) acrylamide, its hydrolyzate, poly (meth) acrylic acid, (meth) acrylamide and alkylamino (meth) acrylamide are usually used. Nonionic, anionic, cationic or amphoteric polymer flocculants such as polymers can be used.

  The addition amount of a coagulant aid such as a polymer flocculant is usually about 0.5 to 5 mg / L with respect to the amount of drainage.

  The agglomeration tanks 11, 21, and 31 are not particularly limited, but an efficient agglomeration process can be performed by using the agglomeration apparatus described in the above-mentioned JP-A-10-337406.

  Although there is no restriction | limiting in particular as a levitation tank, It is preferable to use the pressurization levitation | floating apparatus described in above-mentioned Japanese Patent Application No. 2005-33283 and Japanese Patent Application No. 2005-40855.

  As the fine bubble generators 13, 23, 33, a vortex pump type can be used.

  The biological reaction tank 34 preferably uses a biofilm, and in particular, a contact aeration biological reaction tank or a biological reaction tank into which a sponge carrier is charged is preferable.

  The wastewater treatment method shown in FIG. 1 is an example of an embodiment of the present invention, and the present invention is not limited to the illustrated one as long as it does not exceed the gist thereof.

  For example, the separated water of the concentrated wastewater treatment system 20 may be supplied to the biological reaction tank 34 of the biological treatment system 30, and is supplied to both the biological reaction tank 34 and the coagulation tank 11 of the lean wastewater treatment system 10. You may do it.

  Further, the separated water in the floating tank 32 of the biological treatment system 30 may be used as water for generating fine bubbles in the fine bubble generating devices 13 and 23 of the lean waste water treatment system 10 and the concentrated waste water treatment system 20.

Such book SS concentration and the method and apparatus Ru rare thin effluent apply the invention and n-hexane extractives levels respectively 10~1,000mg / L, it is of 10~1,000mg / L, the concentrated wastewater The SS concentration and the normal hexane extractable substance concentration are 1,000 to 10,000 mg / L and 1,000 to 100,000 mg / L, respectively.

  Such a method of the present invention is effective for the treatment of wastewater from food factory wastewater, steel, machinery, petroleum, textile, metal, food, leather, laundry, etc., and wastewater from gas stations, restaurants, etc. Among such wastewaters, for example, miscellaneous wastewater from a metal processing factory can be used as dilute wastewater, and cutting oil wastewater from the same factory can be used as concentrated wastewater to be agglomerated and separated.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.

  In addition, the diluted waste water processed below is a miscellaneous waste water with a normal hexane extract substance concentration of 100 mg / L, and the concentrated waste water is a cutting oil waste water with a normal hexane extract substance concentration of 30,000 mg / L.

  Further, PAC was used as the inorganic flocculant, and sodium polyacrylate was used as the polymer flocculant.

Example 1
The waste water treatment apparatus of the present invention shown in FIG. 1 was used to agglomerate and separate the lean waste water and the concentrated waste water. The specifications of each tank are as follows.
Coagulation tank 11: 2.1 m ³
Levitation tank 12: 2.7 m ³
Microbubble generator 13: Nikuni vortex pump 5.5 kW
Coagulation tank 12: 0.5 m ³
Levitation tank 22: 0.7 m ³
Microbubble generator 23: Nikuni vortex pump 5.5 kW
Biological reaction tank 34: 8 m ³
Coagulation tank 31: 2.1 m ³
Floating tank 32: 2.7 m ³
Microbubble generator 33: Nikuni vortex pump 5.5 kW

20 m ³ / hr of dilute wastewater and 2.7 m ³ / hr of the separation water in the floating separation chamber 22 B are introduced into the coagulation tank 1, PAC is added for coagulation treatment, and the coagulation treatment water is polymerized in the floatation tank 12. Then, fine bubbles were added and mixed, and floated and separated into floating scum of 0.2 m ³ / hr and separated water of 26.5 m ³ / hr. The floating scum was fed to the agglomeration tank 22.

A part of the separated water 4m ³ / hr is used as water for generating fine bubbles in the fine bubble generating device 13, the other 2m ³ / hr is used as water for generating fine bubbles in the fine bubble generating device 23, and the rest is in the biological reaction tank 34. Biologically processed. Biologically treated water 20.5 m ³ / hr is agglomerated by adding PAC in the agglomeration tank 31, and the polymer aggregating agent and fine bubbles are added and mixed in the agglomeration treated water in the levitation tank 32, so that the floating scum 0.2 m ³ / Hr and separation water 20.3 m ³ / hr. The floating scum was fed to the agglomeration tank 22. A part of the separated water was used as water for generating fine bubbles in the fine bubble generator 33, and the remaining part was discharged out of the system as treated water.

On the other hand, concentrated drainage is introduced into the flocculation tank 21 at a flow rate of 0.7 m ³ / hr, and flocculation scum and PAC are added from the levitation tanks 12 and 32 to perform flocculation treatment. The flocculant and fine bubbles were added and mixed, and the mixture was floated and separated into floating scum of 0.4 m ³ / hr and separated water of 2.7 m ³ / hr.

  The floating scum was discharged out of the system, and the separated water was fed to the coagulation tank 11.

  Table 1 shows the amount of PAC, the amount of fine bubbles, and the amount of polymer flocculant required in each tank in this treatment. In addition, the amount of fine bubbles was expressed as a pressurized water amount and a pressurized water pressure.

Comparative Example 1
In Example 1, the treatment was performed in the same manner except that the floating scum of the floating tanks 12 and 32 was not added to the coagulation tank 21, and the amount of PAC, the amount of fine bubbles, and the polymer coagulant required in each tank The amount is shown in Table 1.

  From Table 1, according to the present invention, the amount of flocculant used in the concentrated wastewater treatment system and the floating scum of the biological wastewater treatment system in the subsequent stage are fed to the concentrated wastewater treatment system. It can be seen that the required amount of fine bubbles can be greatly reduced.

It is a systematic diagram which shows embodiment of the processing method and processing apparatus of the waste_water | drain of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Diluted waste water treatment system 11, 21, 31 Coagulation tank 12, 22, 32 Floating tank 12A, 22A, 32A Mixing chamber 12B, 22B, 32B Flotation separation chamber 13, 23, 33 Fine bubble generator 20 Concentrated waste water treatment system 30 Biology Treatment system 34 Biological reaction tank

Claims (10)

A first agglomeration and flotation step of aggregating and flotation of SS and oil-lean waste water to obtain flotation scum and separated water; and a flotation and separation of SS and / or oil-rich waste water by flotation and separation and flotation scum and separated water In the wastewater treatment method having the second coagulation flotation separation step to obtain
A wastewater treatment method in which the floating scum obtained in the first flocculation and separation step is mixed with the SS and / or oil-rich wastewater to flocculate and separate .
The SS and oil-lean wastewater has SS concentration and normal hexane extractable substance concentration of 10 to 1,000 mg / L and 10 to 1,000 mg / L, respectively. The SS and / or oily wastewater has SS concentration. Is a method for treating waste water, wherein the concentration of the normal hexane extract is 1,000 to 100,000 mg / L.   The wastewater treatment method according to claim 1, wherein the separated water obtained in the second flocculation and separation step is mixed with the SS and a dilute drainage of oil to perform flocculation and separation.   In Claim 1 or 2, the biological treatment process which carries out the biological treatment of the separated water obtained by the 1st above-mentioned flocculent floating separation process, flocculent floating separation of the treated water of this biological treatment process, and floating scum and separated water A third agglomeration-floating separation step to obtain, and the flotation scum of the third agglomeration-flotation separation step is mixed with the SS and / or oily concentrated waste water for agglomeration flotation separation. Processing method.   In any one of Claims 1 thru | or 3, in the flocculation floating separation of waste_water | drain, in the mixing chamber using the floating tank in which the mixing chamber and the floating separation chamber were formed by partitioning the inside of the tank with the partition. A wastewater treatment method comprising mixing wastewater agglomeration treatment water with agglomeration aid and fine bubbles, and separating the wastewater into a flotation scum and separation water in the flotation separation chamber.   5. The separation water obtained in any one of claims 1 to 4, wherein the separated water obtained in the first flocculating and separating step and / or the third flocculating and separating step is used as water for generating fine bubbles. Wastewater treatment method. First flocculating and floating separation means for flocculating and separating SS and oil-lean wastewater to obtain floating scum and separated water; and SS and / or oil-rich wastewater for flocculating and floating to separate floating scum and separated water A wastewater treatment apparatus having second agglomeration levitation separation means for obtaining
A wastewater treatment apparatus having means for feeding a floating scum from the first agglomeration floating separation means to the second agglomeration separation means ;
The SS and oil-lean wastewater has SS concentration and normal hexane extractable substance concentration of 10 to 1,000 mg / L and 10 to 1,000 mg / L, respectively. The SS and / or oily wastewater has SS concentration. Is a wastewater treatment apparatus, wherein the concentration of the normal hexane extract is 1,000 mg / L to 100,000 mg / L. 7. The wastewater treatment apparatus according to claim 6 , further comprising means for feeding the separated water from the second flocculating and floating separation means to the first flocculating and floating separation means. In Claim 6 or 7 , the biological treatment means for biologically treating the separated water from the first flocculating and floating separation means, and the treated water of the biological treatment means is flocculated and separated to obtain floating scum and separated water. And a third flocculating / floating / separating means, and the floating scum of the third flocculating / floating / separating means is fed to the second flocculating / floating / separating means. 9. The flocculation / floating / separating means according to any one of claims 6 to 8 , wherein the flocculating / floating / separating means forms a mixing chamber and a floating / separating chamber by partitioning the inside of the tank by a partition wall, and the flocculated treated water for drainage is formed in the mixing chamber. A wastewater treatment apparatus comprising: a floating tank that mixes the coagulant with a coagulation aid and fine bubbles and separates the mixed water into a floating scum and separated water in the floating separation chamber. The drainage according to any one of claims 6 to 9 , wherein the separated water obtained by the first flocculating and separating means and / or the third flocculating and separating means is used as water for generating fine bubbles. Processing equipment.

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