JP6797706B2 - Water treatment system and water treatment method - Google Patents

Description

Embodiments of the present invention relate to water treatment systems and water treatment methods.

In the fields of water and sewage, wastewater treatment, water supply, etc., various methods have been devised and implemented to purify water. The water purification method is a method of removing unnecessary substances and substances that cannot be discharged to the subsequent process among solid substances and dissolved substances in water.
As a general water purification method, a water tank is installed, the water to be treated is retained there, and the solid matter is separated by the difference in specific gravity and gravity. Sedimentation separation, floating separation, and water in which air is dissolved by pressurization. Is brought into contact with a solid material, and fine air bubbles are attached to the solid material to cause the water to float.

When the water to be treated contains oil, organic substances, a large amount of suspended substances (hereinafter referred to as "turbid substances"), colloids (fine turbid substances), etc., the difference in specific gravity is used to make solid substances. Is difficult to separate. In that case, in addition to sedimentation separation and floating separation, a coagulation treatment is also used in which a chemical such as a coagulant or a coagulant is added to the water to be treated to coarsen the solid matter and then separate it. In addition, membrane separation by filtering using porous ceramics or resin, activated sludge method in which microorganisms prey on organic substances or the like may be used.

Among such separation methods, coagulation filtration, which is a combination of coagulation treatment and membrane separation, is a method of separating agglomerates in water to be treated that have been coarsened by coagulation treatment using a membrane material having fine pores or the like. As the membrane material, a material having fine pores having a pore size corresponding to the size of the agglomerates is used. As a result, the required separation accuracy is ensured.

An issue in coagulation filtration is, for example, filtration flow rate. Since the membrane material is filtered on the surface, the volume of the membrane material and the structures supporting it increases in proportion to the flow rate of the water to be treated. As a result, equipment costs are high. If a membrane material capable of increasing the flow rate of water to be treated per unit area can be used, the equipment can be miniaturized. As a result, the installation area of the equipment can be reduced and the equipment can be operated smoothly.

Further, as another problem in coagulation filtration, for example, detergency of the membrane material can be mentioned. The detergency of the membrane material is the ease of cleaning the membrane material. In agglutination filtration, the agglutination is continuously filtered, so that the agglutination is deposited on the surface of the membrane material. Further, when a substance having poor water permeability such as a biofilm or an organic polymer adheres to the vicinity of the surface of the membrane material, the filtration flow rate becomes slow. In that case, the deposits near the surface of the membrane material are removed by backwashing the membrane material or washing with chemicals. The ease of removing the deposits varies depending on the properties of the agglomerates and the film material.

In view of these problems, conventional membrane materials using fluororesin whose surface is inert (particularly, polytetrafluoroethylene, polyvinylidene fluoride, etc.) and membrane materials having a large surface area (hollow fiber membrane, etc.) have been used. Has been developed. However, these film materials alone are not sufficient, and the problem of fouling is still unsolved.

JP-A-2015-85252

An object to be solved by the present invention is to provide a water treatment system and a water treatment method that suppress clogging of the filtration device and improve the detergency of the filtration device.

The water treatment system of the embodiment includes a miniaturization device, a coagulation device, a filtration device, and a backwash device. The micronization apparatus makes the turbidity-containing material containing the turbidity and the coagulant, which is formed in the water to be treated, finely divided by mixing the coagulant with the water to be treated containing the turbidity. The agglutinator aggregates the finely divided turbidity-containing substances into agglomerates. The filtration device filters the water to be treated containing agglomerates. The backwash device backwashes the filtration device.

The schematic diagram which shows the water treatment system of 1st Embodiment. The figure which shows the turbidity and the gel-like flocculant. The figure which shows the turbid substance containing turbidity and a flocculant. The figure which shows the agglomerate. The figure which shows the filtration process. The figure which shows the backwash process. The figure which shows the change of the filtration flow rate. The figure which shows the agglutination formed in the general agglutination filtration. The schematic diagram which shows the water treatment system of 2nd Embodiment. The figure which shows the turbidity content which went through the homogenization step. The figure which shows the agglomerate of the turbid matter content which went through the homogenization step.

Hereinafter, the water treatment system and the water treatment method of the embodiment will be described with reference to the drawings.

[First Embodiment]
(Water treatment system)
The water treatment system according to the first embodiment will be described with reference to FIG.
The water treatment system 100 shown in FIG. 1 is roughly composed of a miniaturization device 1, a coagulation device 2, a filtration device 3, and a backwash device 4. These devices are provided in this order along the direction in which the water to be treated is transferred.
As shown in FIG. 1, the water treatment system 100 may have a water to be treated storage tank 5 and a coagulant storage tank 6. These components are connected by a flow path including pipes and the like.

The miniaturization device 1 is a device that mixes a flocculant with water to be treated containing turbidity and miniaturizes a turbidity-containing substance containing turbidity and coagulant formed in the water to be treated.
In the miniaturization apparatus 1, the coagulant-containing water to be treated, which is obtained by adding a coagulant to the water to be treated containing turbidity, is agitated to mix the coagulant with the water to be treated containing turbidity, and the turbidity-containing substance. To be miniaturized. Further, by this stirring, the finely divided turbid substance is dispersed in the water to be treated.

The miniaturization device 1 has a stirring tank 7 for accommodating water to be treated containing a turbid substance, a flocculant, and a turbid substance-containing substance.

In the micronization apparatus 1, the stirring for refining the turbid substance-containing substance by mixing the coagulant with the water to be treated containing the turbid substance means that the turbid substance, the coagulant and the turbid substance are contained in the stirring tank 7. Substances due to shearing force between soluble or insoluble fine substances, collisions between substances, collisions between substances and the inner wall surface of the stirring tank 7, etc., which occur when energy is applied to water to be treated containing substances. It is to break the bond between them and make them finer. Here, the soluble or insoluble fine substance is a turbid substance and a turbid substance-containing substance.

In the miniaturization device 1, the stirring force when stirring the water to be treated containing the turbid substance, the coagulant and the turbid substance-containing substance is 1000 or more in the stirring force (G) defined by the following formula (1). Is preferable.
G = (P / (V · μ)) ^1/2 ... (1)
(In the formula, P is the energy (W) input to the miniaturization device, V is the capacity (m ³ ) of the stirring tank provided in the miniaturization device and accommodates the water to be treated, and μ is the viscosity coefficient of water (kg / kg /). Represents m · s).
When the stirring power (G) is 1000 or more, the flocculant can be uniformly mixed with the water to be treated containing the turbid substance, and the turbid substance-containing substance can be made finer.
The energy P (W) input to the miniaturization device can be confirmed by the device.

The miniaturization device 1 is preferably at least one selected from the group consisting of a disperser, a stirrer, and an emulsifier. One of these devices may be used alone, or two or more thereof may be used in combination.
By using these devices, the flocculant can be uniformly mixed with the water to be treated containing turbidity, and the turbidity-containing material can be made finer.

The agglutinating device 2 is a device that agglomerates finely divided turbid substances into agglomerates.
The aggregating device 2 has a treatment tank 8 for accommodating water to be treated containing a turbid substance.
As the aggregating device 2, a stirring device or the like provided with a general stirring blade is used.

In the agglutinating device 2, agitation in general agglutination filtration is performed in order to agglomerate the finely divided turbidity-containing substances into agglomerates. That is, in the aggregating device 2, energy is applied to the water to be treated containing the turbid substances in the treatment tank 8 to cause the turbid substances and the turbid substances to collide with each other and adhere the substances to each other. And make it coarse.

The filtration device 3 is a device that filters the water to be treated containing the agglutinating device 2 and separates the agglutinating water into solid and liquid.
Examples of the filtration device 3 include a membrane material having a large number of micropores, a plate material, and the like.

The backwash device 4 is a device for washing the filtration device 3 by backflowing the filtered water to be treated or clean water (in the cohesive filtration by the water treatment system 100, the direction opposite to the direction in which the water to be treated is transferred). Is.

The water storage tank 5 to be treated is connected to the miniaturization device 1 and the industrial facility 200 via a flow path including pipes and the like.
The treated water storage tank 5 is a tank that stores the treated water (wastewater) discharged from the industrial facility 200 and supplies the treated water to the miniaturization device 1.

The coagulant storage tank 6 is provided in the middle of the flow path connecting the water to be treated water storage tank 5 and the miniaturization device 1, and immediately before the miniaturization device 1 in the flow path, via a flow path composed of pipes or the like. It is connected.
The coagulant storage tank 6 is a tank for adding a coagulant to the water to be treated immediately before being supplied from the water to be treated water storage tank 5 to the miniaturization apparatus 1.

In FIG. 1, the coagulant storage tank 6 is connected in the middle of the flow path connecting the water to be treated water storage tank 5 and the miniaturization device 1, and is treated from the coagulant storage tank 6 in the middle of the flow path. Although the case where the flocculant is added to water has been illustrated, the present embodiment is not limited to this. In the present embodiment, the coagulant storage tank 6 may be directly connected to the micronizing device 1 and the coagulant may be added directly from the coagulant storage tank 6 to the treated water in the miniaturizing device 1.

(Water treatment method)
An example of a water treatment method using the water treatment system 100 will be described with reference to FIGS. 1 to 8, and the operation of the water treatment system 100 will be described.
In the water treatment system 100 according to the first embodiment, the water to be treated is, for example, industrial wastewater containing turbid substances such as oil, organic matter, solid matter, and colloid discharged from the industrial facility 200. ..
The water to be treated is transferred from the water storage tank 5 to the miniaturization device 1 by a pump or the like.

Next, the coagulant is added from the coagulant storage tank 6 to the water to be treated being transferred from the water to be treated storage tank 5 to the miniaturization apparatus 1. The position where the coagulant is added is immediately before the miniaturization device 1.
The amount of the flocculant added is not particularly limited, and is appropriately adjusted depending on the content of the turbidity in the water to be treated.

Next, the turbidity containing the turbidity and the flocculant formed in the water to be treated by mixing the coagulant with the water to be treated containing the turbidity transferred from the water storage tank 5 to be treated by the miniaturization apparatus 1. The quality-containing material is refined (miniaturization step).

In the miniaturization step, the miniaturization device 1 mixes the turbidity 310 and the coarsened gel-like flocculant 320 contained in the water to be treated in the stirring tank 7 as shown in FIG. At the same time, as shown in FIG. 3, the turbidity-containing material 330 containing the turbidity 310 and the flocculant 320 is miniaturized to about the size of the turbidity 310. More specifically, by stirring the water to be treated by the stirring force of the miniaturizing device 1, the coarsened coagulant 320 is miniaturized, and the coagulant 320 is refined while suppressing the agglomeration of the turbid substances 310 to each other. The 320 and the turbid material 310 are made to collide with each other to adhere them. As a result, as shown in FIG. 3, the surface of the turbid substance 310 is coated with the thin film-like flocculant 320 to form the turbid substance-containing material 330. In the turbid substance 330, the flocculant 320 adheres in a thin film shape along the surface shape of the turbid substance 310. Therefore, the flocculant 320 smoothes the surface irregularities of the turbidity 310. Further, as shown in FIG. 3, the turbid substance 330 is in a state in which a single turbid substance 310 is coated with a thin film-like flocculant 320, and a plurality of turbid substances 310 are coated with the flocculant 320. Not in a state. The turbidity-containing material 330 is miniaturized by forming such a state.

The smaller the volume of the flocculant 320 contained in the turbidity-containing material 330, the larger the surface area of the turbidity-containing material 330 in the same volume. As a result, not only the flocculant 320 can be used efficiently, but also the amount of the flocculant 320 made of a low-strength gel is reduced in the turbidity-containing material 330, and the turbidity is subjected to the backwashing step described later. It is possible to prevent the flocculant 320 that overlaps 310 from breaking. Therefore, the turbid substance 330 is easily peeled off from the filtration device 3 by the backwashing step described later. Further, even if the filtration step described later is repeated, it is possible to prevent the turbid substance 330 from remaining adhering to or in the vicinity of the micropores of the filtration device 3. As a result, a decrease in the filtration flow rate can be suppressed.

In the miniaturization step, the stirring force when stirring the water to be treated containing the turbidity, the flocculant and the turbidity-containing substance is 1000 in the stirring force (G) defined by the above formula (1) as described above. The above is preferable.

As the coagulant, an iron-based coagulant or an aluminum-based coagulant is used.
Examples of the iron-based flocculant include polyiron, ferric chloride and the like.
Examples of the aluminum-based flocculant include aluminum sulfate (sulfate band), polyaluminum chloride (PAC), and the like.

After obtaining the turbidity-containing material, it is preferable to measure the particle size of the turbidity-containing material in order to confirm its particle size (outer diameter). That is, it is preferable that the particle size of the turbidity-containing material is measured between the micronization step and the coagulation step (between the miniaturization device 1 and the coagulation device 2).
As a method for measuring the particle size of the turbid substance, for example, a general measuring method such as laser diffraction, dynamic light scattering, or image processing is used.

Next, the aggregating device 2 agitates the treated water containing the pulverized turbidity-containing material transferred from the pulverizing apparatus 1, and agglomerates the turbid substance-containing material in the treated water. Agglomerate (aggregation step).

In the aggregating step, the aggregating device 2 aggregates the finely divided turbidity-containing material 330 in the treatment tank 8 as shown in FIG. 3 to obtain an agglomerate 400 as shown in FIG. More specifically, the turbidity-containing material 330 and the turbidity-containing material 330 are made to collide with each other by stirring the water to be treated containing the turbidity-containing material that has been refined by the stirring force of the aggregating device 2, and the turbidity-containing material is contained. The objects 330 are adhered to each other and coarsened to obtain an agglomerate 400.

After obtaining the agglomerates, it is preferable to measure the particle size of the agglomerates in order to confirm whether or not the particle size (outer diameter) thereof is suitable for the filtration step. That is, it is preferable that the particle size of the agglomerates is measured between the agglutination step and the filtration step (between the agglutinating device 2 and the filtering device 3).
As a method for measuring the particle size of agglomerates, for example, a general measuring method such as laser diffraction, dynamic light scattering, or image processing is used.

Next, the water to be treated containing the agglutinating device transferred from the agglutinating device 2 is filtered by the filtration device 3 and solid-liquid separated into the agglutinating device and the treated water (filtration step).

In the filtration step, as shown in FIG. 5, the agglomerates 400 contained therein are separated from the water to be treated 500 by passing the water to be treated 500 containing the agglomerates 400 through the filtration device 3, and the filtrate is separated. (Treatment water after filtration) 510 is obtained.
When the water to be treated 500 is filtered, a predetermined pressure is applied to the water to be treated 500, so that the water to be treated 500 is supplied to the filtration device 3 at a constant flow rate or a constant pressure. When the water to be treated 500 is filtered for a certain period of time, the agglomerates 400 contained in the water to be treated 500 are collected from the surface and micropores of the filtration device 3 (in FIG. 6, the filtration device 3 is pressed from the supply side α of the water to be treated 500). It is deposited in the hole) 3a penetrating to the equivalent side β. Then, the resistance of the water to be treated 500 to permeate the filtration device 3 increases, and the flow velocity when the water to be treated 500 permeates the filtration device 3 (hereinafter, referred to as “filtration flow velocity”) increases with the passage of time. descend. That is, the easiness of permeation of the water to be treated 500 in the filtration device 3 (hereinafter referred to as "permeability") is reduced.

When the permeability of the water to be treated 500 is lowered, as shown in FIG. 6, the filtrate 510 or clean water is used as the washing water 520, and the washing water 520 is backflowed (in the cohesive filtration by the water treatment system 100, the treated water is treated. The filtration device 3 is washed (backwashed) by moving the treated water 500 in the direction opposite to the transfer direction (backwashing step).
It is preferable that the filtration device 3 is washed regularly. As a result, the permeability of the filtration device 3 can be restored.

In the backwashing step, a predetermined pressure is applied to the washing water 520, and the washing water 520 is supplied from the permeation side β of the filtration device 3 to the supply side α at a predetermined flow rate. When the cleaning liquid 520 passes through the micropores 3a of the filtration device 3 from the permeation side β toward the supply side α, the agglomerates 400 adhering to the surface of the filtration device 3 and the micropores 3a are the filtration device 3 and its fine particles. It peels off from the surface of the hole 3a and is removed from the filtration device 3 with the washing water 520.

The filtration device 3 is backwashed with the cleaning liquid 520, and the agglomerates 400 adhering to the filtration device 3 are removed from the filtration device 3, so that the amount of the agglomerates 400 adhering to the filtration device 3 is accumulated. It can be reduced. As a result, the filtration flow rate of the water to be treated 500 can be restored when the water to be treated 500 containing the agglomerates 400 is passed through the filtration device 3. By washing, the water to be treated 500 can be filtered again at a filtration flow rate close to the initial use, using the filtration device 3 whose filtration flow rate has been restored.

Generally, the filtration of the water to be treated and the washing (backwashing) of the filtration device are repeated to restore the filtration flow velocity of the filtration device, and the water to be treated is filtered again.
However, as shown in FIG. 7, it is not possible to restore the filtration flow rate of the filtration device to the initial value only by cleaning the filtration device. This is because, as shown in FIG. 8, the agglomerates 410 formed in general agglutination filtration have a large amount of the agglutinant 320 made of a low-strength gel, and the agglutinant 320 remains in the filtration device. ..
Therefore, as the filtration of the water to be treated and the washing of the filtration device are repeated, the filtration flow rate of the water to be treated gradually decreases, and finally, even if the filter is washed, the filtration of the water to be treated in the filtration device is performed. The flow velocity does not recover sufficiently and the filtration device is blocked.

In the present embodiment, the case where the miniaturization device 1 and the coagulation device 2 are individually provided has been illustrated, but the present embodiment is not limited to this. In the present embodiment, the above-mentioned miniaturization step and aggregation step may be performed in the same device.

[Second Embodiment]
(Water treatment system)
The water treatment system according to the second embodiment will be described with reference to FIG.
The same configurations as those of the water treatment system according to the first embodiment shown in FIG. 1 are designated by the same reference numerals, and redundant description will be omitted.

The water treatment system 600 according to the second embodiment shown in FIG. 9 is roughly composed of a miniaturization device 1, a coagulation device 2, a filtration device 3, a backwash device 4, and a homogenization device 9. ..
The homogenizing device 9 is provided between the miniaturization device 1 and the coagulation device 2. The homogenizing device 9 gives a swirling flow to the water to be treated containing the turbid substance contained in the turbid substance refined by the micronizing device 1 to smooth (homogenize) the surface of the coagulant that superimposes the turbidity. It is a device.

The homogenizing device 9 has a treatment tank 10 for accommodating water to be treated containing a turbid substance.
As the homogenizing device 9, a device capable of generating a swirling flow in the water to be treated containing the turbidity-containing substance in the treatment tank 10 is used. Examples of the homogenizing device 9 include a container rotating type rolling device.

(Water treatment method)
An example of a water treatment method using the water treatment system 600 will be described with reference to FIGS. 9 to 11, and the operation of the water treatment system 600 will be described.
In the water treatment method of the present embodiment, in addition to each step of the first embodiment, a homogeneity that gives a swirling flow to the water to be treated containing the finely divided turbid substance during the micronization step and the aggregation step. Has a chemical conversion process.

In the homogenization step, the homogenizing device 9 gives a swirling flow to the treated water containing the finely divided turbidity-containing material transferred from the finening device 1, and the turbidity is superimposed in the treated water. Smooth (homogenize) the surface of the flocculant.

As a result, as shown in FIG. 10, a turbidity-containing material 330 having a smooth surface of the flocculant 320 covering the turbidity 310 can be obtained.
In the homogenization step, the degree of smoothing (homogenizing) the surface of the flocculant 320 is such that the sphericity of the turbidity-containing material 330 is 1.6 or less and the line segment passes through the center of the turbidity-containing material 330 in one direction. Aspect ratio (minor axis) when the length (particle size) of the line segment passing through the center of the turbid substance 330 is the minor axis and the length (particle size) of the line segment orthogonal to the minor axis is the major axis. / Long axis) is preferably 0.8 or less. When the sphericity is 1.6 or less and the aspect ratio is 0.8 or less, the turbidity-containing material 330 can be brought into a state generally called spherical fine particles. Further, by homogenizing the turbidity-containing material 330, the filling rate of the turbidity-containing material 330 in the same volume increases when the turbidity-containing material is aggregated in the agglomeration step, as shown in FIG. Not only can the flocculant 320 be used efficiently, but also the flocculant 320 made of a low-strength gel can be reduced in the turbidity-containing material 330. As a result, it is possible to prevent the flocculant 320 that superimposes the turbidity 310 from being broken by the backwashing step. Therefore, the turbid substance 330 is easily peeled off from the filtration device 3 by the backwashing step, and even if the filtration step is repeated, the turbid substance 330 remains attached to or in the vicinity of the fine pores of the filtration device 3. As a result, it is possible to suppress a decrease in the filtration flow rate. Further, since the filling rate of the turbid substance 330 is increased, the amount of water held in the gaps of the agglomerates 400 is also reduced, and as a result, the amount of sludge composed of the agglomerates 400 can be reduced.

After homogenizing the turbidity-containing material 330, it is preferable to measure its particle size (outer diameter). That is, it is preferable to measure the particle size of the homogenized turbidity-containing material 330 between the homogenization step and the coagulation step (between the homogenization device 9 and the coagulation device 2).
As a method for measuring the particle size of the homogenized turbidity-containing material 330, for example, a general measuring method such as laser diffraction, dynamic light scattering method, or image processing is used.

In the present embodiment, the case where the miniaturization device 1, the coagulation device 2, and the homogenization device 9 are individually provided has been illustrated, but the present embodiment is not limited to this. In the present embodiment, the above-mentioned miniaturization step, aggregation step, and homogenization step may be performed in the same device.

According to at least one embodiment described above, the turbidity-containing material containing the turbidity and the coagulant, which is formed in the water to be treated, is pulverized by the pulverizer 1 and then finely divided by the pulverizer 2. By aggregating the turbid substance-containing substances to form aggregates, clogging of the filtration device 3 can be suppressed and the detergency of the filtration device 3 can be improved.

Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Micronization device, 2 ... Coagulation device, 3 ... Filtration device, 4 ... Backwash device, 5 ... Water treatment tank, 6 ... Coagulant storage tank, 7 ... Stirring tank, 8 ... Treatment tank, 9 ... Homogenizer, 10 ... Treatment tank, 100 ... Water treatment system, 200 ... Industrial facility, 310 ... Turbidity, 320 ... coagulant, 330 ... turbidity-containing material, 400 ... coagulant, 410 ... general agglomerate, 500 ... water to be treated, 510 ... filtrate, 520 ...・ ・ Washing water, 600 ・ ・ ・ Water treatment system.

Claims (6)

A miniaturizing device for purifying the turbidity and the turbidity-containing material containing the flocculant, which are formed in the water to be treated by mixing the flocculant with the water to be treated containing the turbidity.
An agglutinator that agglomerates the finely divided turbidity-containing material into an agglomerate
A filtration device that filters the water to be treated containing the agglomerates, and
A backwash device that backwashes the filtration device and
A coagulant provided between the micronization device and the coagulation device to apply a swirling flow to the water to be treated containing the micronized turbidity-containing substance to superimpose the turbidity in the treated water. and a homogenizer to homogenize the surface,
The homogenizing device has a sphericity of 1.6 or less of the turbid substance, a minor axis of the length of a line segment passing through the center of the turbid substance in one direction, and passes through the center of the turbid substance. the aspect ratio (short axis / long axis) water treatment systems that than 0.8 when the length of the line was long axis perpendicular to the minor axis of the. In the miniaturization apparatus, the stirring force at the time of stirring the water to be treated containing the turbidity, the flocculant and the turbidity-containing substance is 1000 with a stirring force (G) defined by the following formula (1). The water treatment system according to claim 1 as described above.
G = (P / (V · μ)) ^1/2 ... (1)
(In the formula, P is the energy (W) input to the miniaturization device, V is the capacity (m ³ ) of the stirring tank provided in the miniaturization device and accommodates the water to be treated, and μ is the viscosity coefficient of water (kg / kg /). Represents m · s). The water treatment system according to claim 1 or 2 , wherein the miniaturization device is at least one selected from the group consisting of a disperser, a stirrer, and an emulsifier. By mixing a coagulant with the water to be treated containing the turbidity, a miniaturization step of refining the turbidity and the turbidity-containing substance containing the coagulant formed in the water to be treated, and
The agglutination step of agglutinating the finely divided turbidity-containing material into an agglutination,
A filtration step for filtering the water to be treated containing the agglomerates, and
Between the micronization step and the coagulation step, a swirling flow is applied to the water to be treated containing the miniaturized turbidity-containing substance, and the coagulant that superimposes the turbidity in the treated water. a homogenization step homogenizing the surface, was closed,
In the homogenization step, the sphericity of the turbid substance is 1.6 or less, the length of the line segment passing through the center of the turbid substance in one direction is the minor axis, and the line segment passes through the center of the turbid substance. A water treatment method in which the aspect ratio (minor axis / major axis) is 0.8 or less when the length of a line segment orthogonal to the minor axis of is taken as the major axis . The water treatment method according to claim 4 , further comprising a backwashing step of backwashing the filtration device. In the miniaturization step, the stirring force at the time of stirring the water to be treated containing the turbid substance, the flocculant and the turbid substance-containing substance is 1000 by the stirring force (G) defined by the following formula (1). The water treatment method according to claim 4 or 5 , which is the above.
G = (P / (V · μ)) ^1/2 ... (1)
(In the formula, P is the energy (W) input to the miniaturization device used in the miniaturization step, V is the capacity (m ³ ) of the stirring tank provided in the miniaturization device and accommodates the water to be treated, and μ is water. Represents the viscosity coefficient (kg / m · s) of

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