JP6873629B2 - Water treatment equipment and water treatment method - Google Patents

Description

Embodiments of the present invention relate to a water treatment apparatus and a water treatment method.

In fields such as wastewater treatment and water supply, various treatment methods for purifying water are implemented. In such a treatment method for purifying water (hereinafter, also referred to as a water treatment method), among the objects to be removed such as solids and dissolved substances contained in the water to be treated such as wastewater and irrigation water, from the water to be treated. Remove the object to be removed that you want to remove, for example, the object that you do not want to be discharged in the water treatment process performed later.

In a general water treatment method, the water to be treated is retained in a water tank, and the difference in specific gravity between the water to be treated and the object to be removed is used to settle and separate the object to be removed. There is levitation separation, which separates objects by levitation. Further, in the water treatment method, the fine bubbles generated by adding the water to be treated to the water in which air is pressure-dissolved are attached to the object to be removed, and the object to be removed is floated and separated by pressure flotation. There is a separation.

However, if the size of the object to be removed is fine and the mass is small, the object to be removed does not settle or float, but is dispersed in the water to be treated. Therefore, it is difficult to separate the object to be removed from the water to be treated by the separation method utilizing the difference in specific densities as described above.

In such a case, in the separation method as described above, it is possible to add a coagulant that agglomerates the object to be removed to the water to be treated, and perform a coagulation treatment that agglomerates the object to be removed to form a coarsened agglomerate. is there. The mass of the agglomerates produced by the agglomeration of the objects to be removed is larger than that of the objects to be removed. Therefore, the agglomerates containing the object to be removed are easily separated from the water to be treated by the above-mentioned separation method.

Further, in the separation method as described above, the water to be treated may be filtered using a porous separation membrane. For example, when the water to be treated which has undergone the above-mentioned aggregation treatment is filtered through a separation membrane, the separation membrane can easily separate the agglomerates coarsened by the aggregation treatment from the water to be treated. Furthermore, by changing the size of the pores penetrating the separation membrane, the size of the agglomerates penetrating the separation membrane is adjusted, so that the desired separation accuracy can be obtained.

As described above, in the separation method using the separation membrane, the water to be treated containing the agglomerates composed of the object to be removed and the coagulant is continuously filtered by the separation membrane. Therefore, agglomerates may be deposited on the surface of the separation membrane. When a substance adheres to the surface of the separation membrane, the pores formed in the separation membrane are closed, so that the filtration rate is reduced. In particular, when a substance having adhesiveness and low water permeability, such as a biofilm or an organic polymer, adheres to the separation membrane, the filtration rate is further reduced. When the pores of the separation membrane are completely closed, the water to be treated cannot permeate the separation membrane, which makes it difficult to filter the water to be treated. In such a case, the separation membrane is washed by backwashing the separation membrane by allowing water to permeate through the separation membrane in the direction opposite to the filtration direction, or by chemical washing to wash the separation membrane with a chemical. Work is performed to remove the deposits that adhere to the surface of the separation membrane and block the pores of the separation membrane.

Japanese Unexamined Patent Publication No. 2013-215657

The detergency of the separation membrane is affected by the deposits adhering to the surface of the separation membrane and the physical properties of the separation membrane. Under these circumstances, separation membranes formed from fluororesins such as PTFE and PVDF whose surface is inert, and separation membranes having an increased surface area such as hollow fiber membranes have been developed. However, the decrease in filtration rate due to the deposits on the separation membrane has not been sufficiently resolved, and there is room for improvement.

The problem to be solved by the present invention is to suppress the adhesive force between the separation membrane and the agglomerates contained in the water to be treated, and to suppress the adhesion of the agglomerates to the separation membrane and the clogging of the pores of the separation membrane by the agglomerates. It is an object of the present invention to provide a water treatment apparatus and a water treatment method capable of improving the cleanability of the separation membrane.

The water treatment apparatus of the embodiment is a water treatment apparatus that separates the agglomerates from water to be treated containing agglomerates composed of an object to be removed and a coagulant that agglomerates the agglomerates via a separation membrane. Is. The water treatment device is provided with a first adhesive force suppressing mechanism for suppressing the adhesive force of the agglomerates on the separation membrane and a tank for filtering the water to be treated, and the adhesive force with the agglomerates. It has a second adhesive force suppressing mechanism for suppressing the pressure, and includes a separation membrane that separates the aggregates whose adhesive force to the separation membrane is suppressed from the water to be treated.

The adhesive force between the separation membrane and the agglomerates contained in the water to be treated can be suppressed, the adhesion of the agglomerates to the separation membrane and the clogging of the pores of the separation membrane by the agglomerates can be suppressed, and the cleanability of the separation membrane can be suppressed. It is possible to provide a water treatment apparatus and a water treatment method that can improve the above.

It is a schematic diagram which shows the water treatment equipment which includes the water treatment apparatus of 1st Embodiment. It is sectional drawing which shows typically the separation membrane which comprises the water treatment apparatus of 1st Embodiment. It is an enlarged cross-sectional view which shows typically the uneven structure of the separation membrane which comprises the water treatment apparatus of 1st Embodiment. It is an SEM image which observed the upper surface of the separation membrane which comprises the water treatment apparatus of 1st Embodiment. It is sectional drawing which shows typically the separation membrane which comprises the water treatment apparatus of 1st Embodiment. It is a graph which shows the relationship between the radius of the convex part of the separation membrane and the van der Waals force between the separation membrane and the agglomerate in the water treatment apparatus of the first embodiment. In the graph showing the relationship between the pitch size of the convex portion of the separation membrane / the particle size of the agglomerates and the flow path cross-sectional area of the flow path formed on the separation membrane in the water treatment apparatus of the first embodiment. is there. It is a process drawing which shows the process performed in the water treatment equipment provided with the water treatment apparatus of 1st Embodiment. It is a graph which shows the contact angle of water on the surface of the separation membrane before the hydrophilic treatment and after the hydrophilic treatment in the water treatment apparatus of 2nd Embodiment. It is a graph which shows the relationship between the contact angle of water on the surface of a separation membrane, and the cleaning energy of a separation membrane in the water treatment apparatus of the second embodiment. It is a graph which shows the relationship between the surface charge density of the separation membrane and the electrostatic force acting between the separation membrane and the agglomerates in the water treatment apparatus of the third embodiment. It is a graph which shows the relationship between the sphericity of agglomerates, and the adhesive force between a separation membrane and agglomerates in the water treatment apparatus of 4th Embodiment. It is a graph which shows the relationship between the consolidation ratio of agglomerates, and the adhesive force between a separation membrane and agglomerates in the water treatment apparatus of the 5th Embodiment. It is a graph which shows the relationship between the size of a pitch / particle size of agglomerates, and van der Waals force between a separation membrane and agglomerates in the water treatment apparatus of the sixth embodiment.

Hereinafter, embodiments will be described with reference to the drawings.

(First Embodiment)
FIG. 1 is a schematic view showing a water treatment facility 1 including the water treatment device 7 of the first embodiment. As shown in FIG. 1, the water treatment facility 1 provided with the water treatment device 7 of the first embodiment separates the water to be treated storage unit 2, the coagulation treatment unit 3, and the first adhesive force suppressing mechanism 4. A unit 5 and a treated water storage unit 6 are provided.

The water to be treated storage unit 2 stores the water to be treated including the object to be removed. The object to be removed is, for example, a solid substance composed of an organic substance such as an oil or an inorganic substance, or a turbid substance such as a colloidal substance. The water to be treated is an aqueous liquid containing the above-mentioned object to be removed. Examples of the water to be treated include industrial wastewater discharged from industrial facilities. For example, the solvent of the water to be treated is water. The concentration of the object to be removed in the water to be treated is, for example, 10 ppm or more.

The coagulation treatment unit 3 adds a coagulant to the water to be treated to perform a coagulation treatment of the object to be removed. The water to be treated containing the object to be removed discharged from the water storage unit 2 to be treated is supplied to the coagulation treatment unit 3. Further, a coagulant that agglomerates the object to be removed is supplied to the coagulation treatment unit 3. When the coagulant is added to the water to be treated in the coagulation treatment unit 3, the object to be removed in the water to be treated coagulates to generate an agglomerate composed of the object to be removed and the coagulant. The agglomerates are coarsened by the agglomeration of fine objects to be removed. In order to make the coagulant added to the water to be treated uniform in the water to be treated, the water to be treated in the coagulation treatment unit 3 may be agitated by a stirrer (not shown) or the like.

The coagulant supplied to the water to be treated is appropriately selected according to the type of the object to be removed and the like. Examples of the flocculant include an inorganic flocculant, a cationic polymer flocculant, and an anionic polymer flocculant.

The first adhesive force suppressing mechanism 4 suppresses the adhesive force of agglomerates to the separation membrane attached to the separation unit 5. The water to be treated containing the agglomerates discharged from the agglomeration treatment unit 3 is supplied to the first adhesive force suppressing mechanism 4. The first adhesive force suppressing mechanism 4 reduces the adhesive force of the agglomerates generated by the agglomeration treatment unit 3 to the separation membrane.

The separation unit 5 solid-liquid separates the agglomerates having reduced adhesion to the separation membrane from the water to be treated. The water to be treated containing the agglomerates discharged from the first adhesive force suppressing mechanism 4 is supplied to the separation unit 5. Further, the separation unit 5 is provided with a separation membrane for filtering the water to be treated. In the separation unit 5, by filtering the water to be treated with the separation membrane, the agglomerates do not permeate the separation membrane, and the remaining components constituting the water to be treated permeate the separation membrane. At this time, the treated water is obtained by removing the agglomerates containing the object to be removed by the separation membrane.

The treated water discharged from the separation unit 5 is supplied to the treated water storage unit 6. The treated water storage unit 6 stores the treated water obtained by removing agglomerates from the water to be treated at the separation unit 5. The treated water stored in the treated water storage unit 6 is an aqueous liquid. The concentration of the object to be removed in the treated water is, for example, 10 ppm or less.

The form of the object to be removed in the treated water includes holes formed in the separation membrane in the object to be removed that did not aggregate even when the coagulant was added and the agglomerate composed of the object to be removed and the coagulant. It contains fine agglomerates that have passed through. Here, the size of the object to be removed and the fine agglomerates is smaller than that of the agglomerates removed by the separation unit 5, and the object to be removed and the fine agglomerates pass through the pores formed in the separation membrane.

As described above, by performing the treatment of the coagulation treatment unit 3, the first adhesive force suppressing mechanism 4, and the separation unit 5, the water to be treated is treated and the treated water is generated.

The treated water storage unit 2, the coagulation treatment unit 3, the first adhesive force suppressing mechanism 4, the separation unit 5, and the treated water storage unit 6 may be provided in one tank, or may be provided in a plurality of tanks. May be good. When the treated water storage unit 2, the coagulation treatment unit 3, the first adhesive force suppressing mechanism 4, the separation unit 5, and the treated water storage unit 6 are provided in a plurality of tanks, the water to be treated water storage unit 2, the coagulation treatment unit 3, Each of the first adhesive force suppressing mechanism 4, the separating unit 5, and the treated water storage unit 6 may be provided in separate tanks, or any two or more of these may be provided in one tank.

Next, the water treatment apparatus 7 of the first embodiment will be described.

The water treatment device 7 separates the agglomerates from the water to be treated containing the agglomerates composed of the object to be removed and the aggregating agent via a separation membrane. As shown in FIG. 1, the water treatment device 7 includes a first adhesive force suppressing mechanism 4 and a separation membrane provided in the separation unit 5.

The separation membrane is provided in a tank for filtering the water to be treated, in other words, a tank provided with the separation unit 5. In addition, the separation membrane has a second adhesive force suppressing mechanism that suppresses the adhesive force with the agglomerates, and the agglomerates whose adhesive force to the separation membrane is suppressed is solid-liquid separated from the water to be treated.

FIG. 2 is a cross-sectional view schematically showing the separation membrane 10 constituting the water treatment apparatus 7. FIG. 3 is an enlarged cross-sectional view schematically showing the uneven structure of the separation membrane 10 constituting the water treatment apparatus 7. FIG. 4 is an SEM image of the upper surface of the separation membrane 10 constituting the water treatment apparatus 7.

As shown in FIGS. 2 and 4, the separation membrane 10 is a porous membrane having a plurality of holes 11 penetrating the separation membrane 10 in a direction perpendicular to the surface of the separation membrane 10. A second adhesive force suppressing mechanism 8 is provided on the surface of the separation membrane 10. The second adhesive force suppressing mechanism 8 includes a regular uneven structure formed on the surface of the separation film 10 and composed of a plurality of concave portions 12 and a plurality of convex portions 13. The uneven structure of the second adhesive force suppressing mechanism 8 is provided on the surface of the portion of the separation membrane 10 where the holes 11 are not formed.

The relationship between the magnitude R ₁₁ of the hole 11 and the diameter R ₉ agglomerates 9, as shown in FIG. 3, for the separation membrane 10 to remove aggregates 9 is filtered water to be treated 14, the hole 11 The size R ₁₁ is smaller than the diameter R _{9 of the} agglomerates 9, that is, the particle size of the agglomerates 9. Here, an example in which the agglomerate 9 is spherical is shown, but when the agglomerate 9 is non-spherical, a sphere having the same volume as the non-spherical volume is approximated, and the diameter of the approximate sphere is used as the aggregate. Considered as a diameter of 9.

The cross-sectional shape of the hole 11 parallel to the surface of the separation membrane 10 is not particularly limited, and may be circular or polygonal. When the cross-sectional shape of the hole 11 is a circle, the diameter of the circle corresponds to _{the size R 11 of the hole 11.} When the cross-sectional shape of the hole 11 is a polygon, a circle having the same area as the area of the polygon is approximated, and the diameter of the approximated circle corresponds to _{the size R 11 of the hole 11.}

The size R ₁₁ of the holes 11 is appropriately selected in consideration of the size of the agglomerates 9 and the separation accuracy. The size R ₁₁ of the hole 11 is, for example, preferably 0.5 μm or more and 50.0 μm or less, and more preferably 5.0 μm or more and 30.0 μm or less. When the size R ₁₁ of the hole 11 is smaller than 0.5 μm, the opening ratio of the hole 11 becomes very low and the hole 11 becomes very narrow, so that the flow velocity of the treated water 15 flowing through the hole 11 decreases. , The desired filtration rate may not be obtained. Further, when the size R ₁₁ of the hole 11 is larger than 50.0 micrometers, and the retention rates of aggregate 9 by the separation membrane 10 is decreased, it decreases the strength of the separation membrane 10, when the separation membrane 10 is filtered It can be damaged by the water pressure of.

The relationship between the size of the uneven structure of the second adhesive force suppressing mechanism 8 and the diameter R ₉ of the agglomerates 9 preferably satisfies the following formula (1). That is, as shown in FIG. 3, it is preferable that _{the width W 12 of the} recess 12 is smaller than the diameter R _{9 of the agglomerate 9.} The relationship between the depth _{D 12} of the recess 12 and the diameter _{R 9} agglomerates 9 preferably satisfies the following formula (2). Here, the depth D ₁₂ of the concave portion 12 is equal _{to the height H 13} of the convex portion 13.

W ₁₂ <R ₉ ... Equation (1)

By satisfying the formulas (1) and (2), as shown in FIGS. 2 and 3, the agglomerate 9 makes point contact with the upper end portion of the convex portion 13 and the bottom surface 12a of the concave portion 12 during filtration. Does not come into contact with. On the other hand, with respect to the conventional separation membrane having a regular uneven structure on the surface and not provided with the second adhesive force suppressing mechanism, the agglomerates come into surface contact with the surface of the separation membrane during filtration. As described above, since the contact area between the separation membrane 10 and the agglomerate 9 is reduced as compared with the conventional separation membrane, the adhesive force between the separation membrane 10 and the agglomerate 9 is reduced. Therefore, the detergency of the separation membrane 10 is improved.

Further, by satisfying the formulas (1) and (2), as shown in FIG. 2, a flow path 16 is formed between the bottom surface 12a of the recess 12 and the agglomerate 9. The water to be treated 14 flows in the flow path 16. When the flow path 16 is formed, the flow velocity of the water to be treated 14 is improved in the vicinity of the surface of the separation membrane 10 and the vicinity of the holes 11. Therefore, the time required for filtering the water to be treated 14 is shortened.

The size of the uneven structure in the second adhesive force suppressing mechanism 8 is appropriately adjusted according to _{the diameter R 9 of the agglomerates 9 which are the objects to be filtered. For example, the width W 12} of the recess 12 in the concave-convex structure is preferably 0.5 μm or more and 50.0 μm or less, and more preferably 5.0 μm or more and 30.0 μm or less. When the width W _{12 of the} recess 12 is within the above range, the cleanability of the separation membrane 10 is improved, and the filtration time by the separation membrane 10 is shortened.

Further, when the size of the concave-convex structure in the second adhesive force suppressing mechanism 8 is very small, for example, when the width W _{12 of the concave portion 12 is much smaller than the diameter R 9} of the agglomerate 9, the volume of the flow path 16 is very small. Becomes smaller. Therefore, the effect of improving the flow velocity of the water to be treated 14 in the vicinity of the surface of the separation membrane 10 and the vicinity of the holes 11 is reduced.

FIG. 5 is a cross-sectional view schematically showing the separation membrane 10 constituting the water treatment apparatus 7. As shown in FIG. 5, when the size of the concave-convex structure, for example, the width W _{12 of the} recess 12 becomes the diameter R ₉ or more of the agglomerate 9, the agglomerate 9 may enter the recess 12. In the recess 12 in which the agglomerate 9 has entered, the agglomerate 9 comes into contact with the bottom surface 12a of the recess 12, so that the flow path 16 is not formed. As described above, the volume of the flow path 16 formed in the entire separation membrane that does not satisfy at least one of the formulas (1) and (2) is larger than that of the separation membrane 10 that satisfies the formulas (1) and (2). Since the amount is reduced, the effect of improving the flow velocity of the water to be treated 14 is reduced.

FIG. 6 is a graph showing the relationship between the radius of the convex portion 13 of the separation membrane 10 and the van der Waals force between the separation membrane 10 and the agglomerate 9 in the water treatment apparatus 7 of the first embodiment. .. Here, as an index of the size of the concave-convex structure in the second adhesive force suppressing mechanism 8 provided on the separation membrane 10, the radius of the convex portion 13 when the concave-convex structure is composed of continuous hemispherical convex portions 13 is used. Using. For example, when the radius of the convex portion 13 is 1.00 μm, the hemispherical convex portion 13 having a radius of 1.00 μm is continuously formed on the surface of the separation membrane 10. Further, as an index of the adhesive force between the separation membrane 10 and the agglomerate 9, the van der Waals force acting between the separation membrane 10 and the agglomerate 9 was used. At this time, the agglomerate 9 is a sphere having a diameter R ₉ ^{of 1.00 × 10 1 μm.} The radius of the hemispherical convex portion ₁₃ is equal to the height H 13 of the convex portion 13.

As shown in FIG. 6, in the second adhesive force suppressing mechanism 8 having a concavo-convex structure composed of hemispherical convex portions 13, when the radius of the convex portions 13 is equal to or less than _{the diameter R 9 of the agglomerates 9, the separation membrane 10} The van der Waals force acting between the agglomerate 9 and the agglomerate 9 is reduced. On the other hand, when the radius of the convex portion 13 _{is larger than the diameter R 9 of the} agglomerate 9, the van der Waals force acting between the separation membrane 10 and the agglomerate 9 is substantially constant. That is, by making _{the uneven structure of the second adhesive force suppressing mechanism 8 finer than the diameter R 9} of the agglomerate 9, the adhesive force of the separation membrane 10 with the agglomerate 9 can be reduced.

FIG. 7 shows the size of the pitch of the convex portion 13 of the separation membrane 10 / the particle size of the agglomerates in the water treatment apparatus 7 of the first embodiment, and the flow path of the flow path 16 formed in the separation membrane 10. It is a graph which shows the relationship with the cross-sectional area (μm ^2). Here, as an index of the uneven structure in the second adhesive force suppressing mechanism 8 provided on the separation membrane 10, the pitch of the convex portion 13 when the concave-convex structure is composed of continuous hemispherical convex portions 13 is used. For example, when the pitch size / agglomerate particle size value is 1.00 or more, the particle size of the agglomerate 9 is equal to or less than the pitch size of the convex portion 13, and the pitch size / agglomerate. When the value of the particle size is smaller than 1.00, the particle size of the agglomerates 9 is larger than the size of the pitch of the convex portions 13. At this time, the agglomerate 9 is a sphere having a diameter R ₉ ^{of 1.00 × 10 1 μm.}

As shown in FIG. 7, in the second adhesive force suppressing mechanism 8 having a concavo-convex structure composed of hemispherical convex portions 13, the convex portions 13 are convex in the range where the pitch size of the convex portions 13 is equal to or less than the diameter of the agglomerate 9. As the size of the pitch of the portion 13 decreases, the flow path cross-sectional area of the flow path 16 formed between the recess 12 and the agglomerate 9 increases. That is, the flow path cross-sectional area of the flow path 16 can be controlled by adjusting the size of the uneven structure of the second adhesive force suppressing mechanism 8. Then, in the range where the pitch size of the convex portion 13 is equal to or less than the diameter of the agglomerate 9, the flow path cross-sectional area of the flow path 16 is reduced by reducing the pitch size of the uneven portion of the second adhesive force suppressing mechanism 8. Can be increased.

In this way, by adjusting the size and / or the size of the pitch of the concave-convex structure of the second adhesive force suppressing mechanism 8 provided on the separation membrane 10, the cleanability of the separation membrane 10 can be improved and the cleanability of the separation membrane 10 can be improved. The filtration time of the water to be treated 14 by the separation membrane 10 can be shortened.

Further, the method of forming the uneven structure in the hole 11 and the second adhesive force suppressing mechanism 8 is not particularly limited, and a known method can be used. With respect to the separation membrane 10 shown in FIG. 4, the surface of the separation membrane 10 was partially removed without penetrating the separation membrane 10 by irradiating with a laser beam to form a plurality of recesses 12. After that, the irradiation intensity of the laser beam was increased and the surface of the separation membrane 10 was irradiated with the laser beam to remove the separation membrane 10 and form a plurality of holes 11 penetrating the separation membrane 10. The holes 11 and the uneven structure may be formed by irradiating the surface of the separation membrane 10 with a photomask while partially blocking the laser beam.

Further, as a method for forming the hole 11 and the uneven structure, in addition to the laser beam, for example, a method such as electron beam irradiation, machining such as drill or nanoimprint, etching processing, electric discharge machining, or 3D printing can be used.

Further, in the separation membrane 10 shown in FIG. 4, a concavo-convex structure composed of a plurality of recesses 12 formed by partially removing the surface of the separation membrane 10 has been described, but the concavo-convex structure of the separation membrane 10 is separated. It may be composed of a plurality of convex portions 13 formed by partially laminating a predetermined substance on the surface of the film 10. The uneven structure may be composed of a plurality of concave portions 12, a plurality of convex portions 13, or a plurality of concave portions 12 and a plurality of convex portions 13.

The substance to be laminated on the surface of the separation membrane 10 when forming the convex portion 13 is not particularly limited as long as it has corrosion resistance to the water to be treated 14 and has strength to withstand filtration. For example, it is the same as the material constituting the separation membrane 10. The type of substance to be laminated on the surface of the separation membrane 10 is appropriately selected depending on the type of water to be treated 14, the object to be removed, the type of coagulant, the filtration conditions, and the like.

The uneven pattern of the concave-convex structure in the second adhesive force suppressing mechanism 8 is not particularly limited, and examples thereof include a square, rectangular, and linear pattern.

The material constituting the separation membrane 10 is not particularly limited as long as it has corrosion resistance to the water to be treated 14 and has strength to withstand filtration. The separation film 10 is composed of, for example, an alloy such as SUS, a metal such as titanium or nickel, a resin such as polyethylene or polyethylene terephthalate, polypropylene, polyimide, or a fluororesin. The material constituting the separation membrane 10 is appropriately selected depending on the method for forming the pores 11 and the uneven structure, the water to be treated 14, the object to be removed, the type of coagulant, the filtration conditions, and the like.

The thickness of the separation membrane 10 is preferably 5 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. Here, the thickness of the separation membrane 10 is the shortest distance between the back surface and the front surface facing the front surface of the separation membrane 10 in the direction perpendicular to the surface of the separation membrane 10, that is, the back surface of the separation membrane 10 and the surface of the convex portion 13. Is the shortest distance to. If the thickness of the separation membrane 10 is smaller than 5 μm, the strength of the separation membrane 10 may decrease. Therefore, the pores 11 and the uneven structure may not be stably formed in the separation membrane 10 with high accuracy, and the separation membrane 10 may be damaged by the water pressure during filtration. Further, if the thickness of the separation membrane 10 is larger than 100 μm, it may be difficult to form the holes 11 and the uneven structure.

Next, a step performed in the water treatment facility 1 including the water treatment device 7 of the first embodiment and using the water treatment method of the first embodiment will be described. Here, an example is shown in which each of the treated water storage unit 2, the coagulation treatment unit 3, the first adhesive force suppressing mechanism 4, the separation unit 5, and the treated water storage unit 6 is provided in separate tanks.

FIG. 8 is a process diagram showing a process performed in the water treatment facility 1 provided with the water treatment device 7. As shown in FIG. 8, the step performed in the water treatment facility 1 includes a coagulation step S10, an adhesive force suppressing step S20, and a separation step S30.

As shown in FIG. 1, in the water treatment facility 1, the treated water 14 including the object to be removed is stored in the treated water storage unit 2. The water to be treated 14 including the object to be removed is discharged from the water storage unit 2 to be treated.

As shown in FIGS. 1 and 8, the water to be treated 14 discharged from the water to be treated 2 is supplied to the coagulation treatment unit 3. In the coagulation processing unit 3, the coagulation step S10 is performed. In the aggregating step S10, an aggregating agent is added to the water 14 to be treated containing the object to be removed to generate an agglomerate 9 composed of the object to be removed and the aggregating agent. In this way, the water to be treated 14 containing the agglomerates 9 is obtained. The water to be treated 14 containing the agglomerates 9 is discharged from the agglomeration treatment unit 3.

The water to be treated 14 containing the agglomerates 9 discharged from the agglomeration treatment unit 3 is supplied to the first adhesive force suppressing mechanism 4. In the first adhesive force suppressing mechanism 4, the adhesive force suppressing step S20 is performed. The adhesive force suppressing step S20 suppresses the adhesive force of the agglomerates 9 to the separation membrane 10. The water to be treated 14 containing the agglomerates 9 subjected to the adhesive force suppressing step S20 is discharged from the first adhesive force suppressing mechanism 4.

The water to be treated 14 containing the agglomerates 9 discharged from the first adhesive force suppressing mechanism 4 is supplied to the separation unit 5. In the separation unit 5, the separation step S30 is performed. In the separation step S30, the water to be treated 14 containing the agglomerates 9 is filtered through the separation membrane 10 to separate the agglomerates 9 from the water to be treated 14. When a predetermined pressure is applied to the water to be treated 14 by, for example, an inert gas such as nitrogen or compressed air when the water to be treated 14 is filtered, the water to be treated 14 is applied to the separation film 10 at a constant pressure or a constant flow rate. Be supplied. In the separation step S30, when the separation membrane 10 filters the water to be treated 14, the agglomerates 9 in the water to be treated 14 are removed by the separation membrane 10 to generate the treated water 15. The treated water 15 is discharged from the separation unit 5.

The treated water 15 discharged from the separating unit 5 is supplied to the treated water storage unit 6. The treated water 15 stored in the treated water storage unit 6 can be flushed to a river or the like without performing a separate cleaning treatment or the like. For example, the total concentration of the object to be removed and the agglomerates contained in the treated water 15 is 10 ppm or less.

Next, the water treatment method of the first embodiment will be described.

In the water treatment method of the first embodiment, as shown in FIG. 2, the agglomerates 9 are separated from the water to be treated 14 containing the agglomerates 9 via the separation membrane 10. This water treatment method includes an adhesive force suppressing step S20 and a separation step S30.

The adhesive force suppressing step S20 is applied to the agglomerates 9 in the water to be treated 14. In the adhesive force suppressing step S20, the adhesive force of the agglomerate 9 composed of the object to be removed and the coagulant to the separation membrane 10 is reduced. The adhesive force suppressing step S20 is performed in a tank provided with the first adhesive force suppressing mechanism 4.

In the separation step S30, the agglomerate 9 whose adhesive force to the separation membrane 10 is suppressed is separated from the water to be treated 14 via the separation membrane 10. The separation membrane 10 attached to the separation portion 5 has a second adhesive force suppressing mechanism 8 that suppresses the adhesive force with the agglomerates 9 in the water to be treated 14. The separation step S30 is performed in a tank provided with the separation unit 5.

Here, the separating portion 5 is supplied with the water 14 to be treated, which contains the agglomerates 9 having a reduced adhesive force to the separation membrane 10 and has discharged the first adhesive force suppressing mechanism 4. Further, a separation membrane 10 having a reduced adhesive force with the agglomerates 9 is attached to the separation portion 5. Then, since the adhesive force acting on the agglomerates 9 and the separation membrane 10 is reduced, the agglomerates 9 are less likely to adhere to the surface of the separation membrane 10, and the agglomerates 9 on the separation membrane 10 increase with the passage of filtration time. The amount of adhesion is suppressed more than before. In this way, since the increase in the amount of the agglomerates 9 adhering to the separation membrane 10 is suppressed, the time for the pores 11 to be closed by the agglomerates 9 adhering to the separation membrane 10 is longer than in the conventional case. Therefore, the decrease in the filtration rate of the separation membrane 10 with time due to the clogging of the pores 11 due to the agglomerates 9 is suppressed as compared with the conventional case.

Further, even when the pores 11 of the separation membrane 10 are blocked by the agglomerates 9 or the filtration rate of the separation membrane 10 is reduced by the agglomerates 9, backwashing or chemical washing is performed on the separation membrane 10. By applying, the agglomerates 9 that adhere to the surface of the separation membrane 10 and close the pores 11 are removed from the surface of the separation membrane 10 more easily than before. When the agglomerates 9 are removed from the surface of the separation membrane 10, the permeability of the water to be treated 14 is restored, so that the decrease in the filtration rate of the separation membrane 10 is eliminated. Here, as described above, the adhesive force acting on the agglomerates 9 and the separation membrane 10 is reduced, so that the cleaning recoverability of the separation membrane 10 is improved. Therefore, by cleaning the separation membrane 10, the agglomerates 9 adhering to the surface of the separation membrane 10 can be easily removed from the separation membrane 10 and remain on the surface of the separation membrane 10 after cleaning the separation membrane 10. The amount of agglomerates 9 attached can be reduced. Therefore, the filtration rate of the separation membrane 10 after cleaning the separation membrane 10 increases to near the filtration rate at the start of use of the unused separation membrane 10.

The first adhesive force suppressing mechanism 4 and the separating portion 5 may be provided in separate tanks, but may be provided in one tank.

As described above, according to the water treatment apparatus and the water treatment method of the first embodiment, the adhesive force of the agglomerates 9 contained in the water to be treated 14 to the separation membrane 10 is reduced, and the agglomeration in the separation membrane 10 is reduced. The adhesive force with the object 9 can be reduced. In this way, the adhesive force of the agglomerates 9 and the separation membrane 10 is reduced. Therefore, since it is possible to suppress the blockage of the pores 11 formed in the separation membrane 10, it is possible to suppress a decrease in the filtration rate of the separation membrane 10 with time. Further, by periodically cleaning the separation membrane 10, it is possible to eliminate the decrease in the filtration rate of the separation membrane 10 and restore the filtration rate of the separation membrane 10.

(Second Embodiment)
The water treatment apparatus and the water treatment method of the second embodiment are basically the same as the configurations of the water treatment apparatus and the water treatment method of the first embodiment except that the configuration of the second adhesion suppressing mechanism is different. Is. Therefore, here, the different configurations will be mainly described. In addition, in the embodiment shown below, the description overlapping with the configuration of the water treatment apparatus and the water treatment method of the first embodiment will be omitted or simplified.

The water treatment device of the second embodiment includes a first adhesive force suppressing mechanism and a separation membrane having a second adhesive force suppressing mechanism. The second adhesive force suppressing mechanism includes a hydrophilic portion formed on the surface of the separation membrane. The hydrophilic portion formed on the surface is a portion of the surface that has been hydrophilized.

The surface shape of the separation membrane is not particularly limited. That is, the second adhesive force suppressing mechanism may include a hydrophilic portion formed on the surface of the separation membrane having a concavo-convex structure composed of the concave portion 12 and the convex portion 13 as shown in FIG. 2, or the concavo-convex structure. May be provided with a hydrophilic portion formed on the surface of a smooth separation membrane that does not include. In other words, the surface of the separation membrane having a concavo-convex structure may be hydrophilized, or the surface of a smooth separation membrane not having a concavo-convex structure may be hydrophilized.

The hydrophilization treatment of the separation membrane is not particularly limited, and is treated by a known method. For example, the hydrophilic part of the second adhesive force suppressing mechanism is formed by a hydrophilic coating that coats the surface of the separation membrane with a hydrophilic material such as glass, or a surface modification that modifies the surface of the separation membrane with plasma or an electron beam. Is formed on the surface of the separation membrane.

The hydrophilization of the separation membrane can be measured, for example, by the contact angle of water on the surface of the separation membrane. Here, the contact angle of water refers to a water droplet among the angles formed by the tangent line of the water droplet and the surface of the separation film at the contact point between the free surface of the water droplet and the surface of the separation film. The corner on the containing side. The contact angle of water can be measured with a contact angle meter.

FIG. 9 is a graph showing the contact angle of water on the surface of the separation membrane before and after the hydrophilization treatment in the water treatment apparatus of the second embodiment. Here, the surface of the separation membrane was hydrophilized by coating the surface of the separation membrane, which is composed of SUS and has a smooth surface without having an uneven structure, with glass.

In the separation membrane before the hydrophilization treatment, that is, the separation membrane not provided with the second adhesive force suppressing mechanism, the contact angle of water was about 80 degrees. Further, in the separation membrane after the hydrophilic treatment, that is, the separation membrane provided with the second adhesive force suppressing mechanism, the contact angle of water was about 10 degrees. As described above, it was suggested that by applying the hydrophilic coating on the surface of the separation membrane, a second adhesive force suppressing mechanism having a hydrophilic portion is formed on the surface of the separation membrane.

FIG. 10 is a graph showing the relationship between the contact angle of water on the surface of the separation membrane and the cleaning energy of the separation membrane in the water treatment apparatus of the second embodiment. The cleaning energy of the separation membrane is the energy required to remove the agglomerates adhering to the surface of the separation membrane from the surface of the separation membrane. When the cleaning energy is small, the adhesive force of the separation membrane with the agglomerates can be considered to be small, and the clogging of the pores of the separation membrane is suppressed. Further, the organic agglomerate is a non-gel-like agglomerate composed of an organic material such as a resin, and the inorganic agglomerate is a non-gel-like agglomerate composed of an inorganic material such as clay. A water-based agglomerate is a gel-like agglomerate.

As shown in FIG. 10, the cleaning energy of the separation membrane changes linearly according to the change of the contact angle of water in the separation membrane. The smaller the contact angle of water, the smaller the cleaning energy of the separation membrane, and the more the pores of the separation membrane are suppressed from being blocked.

The degree of hydrophilization treatment of the separation membrane is appropriately set in consideration of the type of agglomerates contained in the water to be treated, the cleaning energy of the cleaning method applied to the separation membrane, and the like. Even when a plurality of types of agglomerates are contained in the water to be treated, the agglomerates can be easily removed from the separation membrane by reducing the contact angle of the water.

As described above, according to the water treatment apparatus and the water treatment method of the second embodiment, the separation membrane has a second adhesive force suppressing mechanism including a hydrophilic portion formed on the surface of the separation membrane. The smaller the contact angle of water on the surface of the separation membrane, the smaller the cleaning energy of the separation membrane and the better the cleaning performance of the separation membrane. As described above, by using the separation membrane having the second adhesive force suppressing mechanism provided with the hydrophilic portion, the separation membrane can be easily washed, so that the decrease in the filtration rate of the separation membrane with time can be eliminated. , The filtration rate of the separation membrane can be restored.

(Third Embodiment)
The water treatment apparatus and the water treatment method of the third embodiment are basically the same as the configurations of the water treatment apparatus and the water treatment method of the first embodiment except that the configuration of the second adhesive force suppressing mechanism is different. Is. Therefore, here, the different configurations will be mainly described.

The water treatment device of the third embodiment includes a separation membrane having a first adhesive force suppressing mechanism and a second adhesive force suppressing mechanism. The second adhesive force suppressing mechanism includes a charged portion formed on the surface of the separation membrane. The charged portion formed on the surface is a portion of the surface to which an electric charge is applied.

For example, when a positive charge is applied to the surface of the separation membrane and the charge of the agglomerates contained in the water to be treated is positive, there is a repulsive force between the charged portion of the second adhesive force suppressing mechanism and the agglomerates. Electrostatic force acts. Therefore, the adhesive force of the separation membrane to the agglomerates is reduced, and the clogging of the pores of the separation membrane is suppressed. On the other hand, for example, when a negative charge is applied to the surface of the separation membrane and the charge of the agglomerate is positive, an attractive electrostatic force acts between the charged portion of the second adhesive force suppressing mechanism and the agglomerate. To do. Therefore, the adhesive force of the separation membrane to the agglomerates increases.

In this way, by applying a charge having the same polarity as the charge of the agglomerate to the surface of the separation membrane to form a charged portion, between the charged portion of the second adhesive force suppressing mechanism and the agglomerate. The electrostatic force of the repulsive force works. Therefore, the adhesive force of the separation membrane to the agglomerates can be reduced. Furthermore, the adhesion of aggregates to the separation membrane can be suppressed.

The surface condition of the separation membrane is not particularly limited. That is, the second adhesive force suppressing mechanism may or may not have a concavo-convex structure composed of the concave portion 12 and the convex portion 13. Further, the second adhesive force suppressing mechanism may or may not include a hydrophilic portion.

The charge application to the surface of the separation membrane is not particularly limited, and is treated by a known method. For example, a charged portion of the second adhesive force suppressing mechanism is formed on the surface of the separation membrane by a charging coating that coats the surface of the separation membrane with a charging material such as a metal oxide.

Further, the charging to the surface of the separation membrane may utilize the property that the surface of the substance is charged with a predetermined polarity and the amount of electric charge by immersing the substance in water. That is, the polarity and the amount of charge of the separation membrane in the water to be treated are determined according to the type of the material constituting the separation membrane. Therefore, when forming the charged portion of the second adhesive force suppressing mechanism by utilizing such a property, the material constituting the separation membrane is selected based on the polarity and the amount of electric charge to be imparted to the separation membrane.

The charge of the separation membrane can be measured, for example, by the surface charge density of the separation membrane. The surface charge density of the separation membrane can be measured by the zeta potential.

FIG. 11 is a graph showing the relationship between the surface charge density of the separation membrane and the electrostatic force acting between the separation membrane and the agglomerates in the water treatment apparatus of the third embodiment. Here, an example is shown in which the agglomerates contained in the water to be treated ^{are charged with 1.0 × 10 -4} (C / m ^2).

When the surface charge density of the separation membrane is 0, no charge is applied to the surface of the separation membrane, and a charged portion is not formed. When the surface charge density of the separation film is positive, a positive charge is applied to the surface of the separation film, and a positively charged portion is formed. When the surface charge density of the separation film is negative, a negative charge is applied to the surface of the separation film, and a negatively charged portion is formed.

Further, when the electrostatic force is 0, no electrostatic force acts between the separation membrane and the agglomerates. When the electrostatic force is positive, a repulsive electrostatic force acts between the separation membrane having the positively charged portion and the positively charged agglomerate. When the electrostatic force is negative, an attractive electrostatic force acts between the separation membrane having the negatively charged portion and the positively charged agglomerate. That is, as the electrostatic force increases, the adhesive force of the separation membrane with the agglomerates decreases, and as the electrostatic force decreases, the adhesive force of the separation membrane with the agglomerates increases.

As shown in FIG. 11, the electrostatic force acting between the separation membrane and the agglomerates changes linearly according to the change in the surface charge density of the separation membrane. The higher the surface charge density of the separation membrane, the greater the electrostatic force of the repulsive force. The surface charge density of the separation membrane is appropriately set in consideration of the polarity and amount of the charge of the aggregate. For example, when the charge of the agglomerate is negative, by applying a negative charge to the surface of the separation membrane, a second adhesive force suppressing mechanism including a negatively charged portion is formed. , The electrostatic force of the repulsive force acts between the second adhesive force suppressing mechanism of the separation membrane and the agglomerates. Therefore, the adhesive force of the separation membrane to the agglomerates becomes small. That is, by applying a charge having the same polarity as the charge of the agglomerate to the surface of the separation membrane to form a charged portion, the adhesive force with the agglomerate in the second adhesive force suppressing mechanism provided with the charged portion can be obtained. Can be lowered.

As described above, according to the water treatment apparatus and the water treatment method of the third embodiment, the separation membrane has a second adhesive force suppressing mechanism including a charged portion formed on the surface of the separation membrane. For example, when the agglomerates in the water to be treated are positively charged, the larger the positive surface charge density in the separation membrane, the greater the electrostatic force of the repulsive force acting between the separation membrane and the agglomerates. The adhesive force with the agglomerates is reduced, and the blockage of the pores of the separation membrane is suppressed. In this way, by adjusting the polarity and amount of the electric charge applied to the surface of the separation membrane according to the polarity and amount of the electric charge of the agglomerates contained in the water to be treated, the adhesive force with the agglomerates in the separation membrane can be adjusted. At the same time, the amount of agglomerates attached to the separation membrane can be reduced. Furthermore, the detergency of the separation membrane can be improved. Therefore, it is possible to suppress the blockage of the pores formed in the separation membrane, and thus it is possible to suppress the decrease in the filtration rate of the separation membrane with time. Further, by using a separation membrane having a second adhesive force suppressing mechanism provided with a charged portion, the separation membrane can be easily washed, so that the decrease in the filtration rate of the separation membrane over time can be eliminated. The filtration rate of the separation membrane can be restored.

(Fourth Embodiment)
The water treatment apparatus and the water treatment method of the fourth embodiment are basically the same as the configurations of the water treatment apparatus and the water treatment method of the first embodiment except that the configuration of the first adhesion suppressing mechanism is different. Is. Therefore, here, the different configurations will be mainly described.

The water treatment device of the fourth embodiment includes a separation membrane having a first adhesive force suppressing mechanism and a second adhesive force suppressing mechanism. The first adhesive force suppressing mechanism includes a spheroidizing treatment unit that spheroidizes the agglomerates contained in the water to be treated.

When the first adhesive force suppressing mechanism including the spheroidizing treatment portion spheroidizes the agglomerates, the agglomerates are processed into spheres. The closer the shape of the agglomerate to a true sphere, the lower the filtration resistance, and the higher the flow velocity of the water to be treated during filtration. Therefore, the filtration rate becomes short. Further, as the shape of the agglomerates is closer to a true sphere, the contact area between the separation membrane and the agglomerates decreases, so that the adhesion force of the agglomerates to the separation membrane decreases. Therefore, the blockage of the pores of the separation membrane is suppressed, and the cleanability of the separation membrane is improved.

The spheroidization of the agglomerates is not particularly limited and is treated by known methods. For example, by using a device or system for rolling an agglomerate, such as a rolling granulator, the agglomerate is sphericalized. In addition, the shape of the spheroidized agglomerates can be controlled by changing the spheroidizing treatment time, the amount of the aggregating agent, and the like.

The shape of the agglomerate can be measured by, for example, an aspect ratio representing the ratio of the major axis to the minor axis, sphericity, and the like. The aspect ratio and sphericity can be measured by image processing of agglomerates.

FIG. 12 is a graph showing the relationship between the sphericity of the agglomerates and the adhesive force between the separation membrane and the agglomerates in the water treatment apparatus of the fourth embodiment.

As shown in FIG. 12, as the sphericity of the agglomerates decreases, the adhesive force decreases. When the sphericity of the agglomerates is 0 μm , the adhesive force is the lowest. In this way, the spheroidizing treatment unit spheroidizes the agglomerates, so that the adhesion of the agglomerates to the separation membrane is reduced. Therefore, the blockage of the pores of the separation membrane is suppressed, and the cleanability of the separation membrane is improved.

As described above, according to the water treatment apparatus and the water treatment method of the fourth embodiment, the first adhesive force suppressing mechanism including the spheroidizing treatment unit for spheroidizing the agglomerates is provided. The more true the shape of the agglomerates, the lower the adhesion of the agglomerates to the separation membrane, and the more the clogging of the pores of the separation membrane is suppressed. In this way, the spheroidizing treatment unit makes the agglomerates spherical, so that the separation membrane can be easily washed. Therefore, the decrease in the filtration rate of the separation membrane over time can be eliminated, and the separation membrane can be filtered. You can restore speed.

A coagulation treatment unit and a first adhesion suppressing mechanism having a spheroidizing treatment unit are provided in separate tanks, and after the coagulation treatment performed by the coagulation treatment unit is performed, the spheroidization treatment is performed by the first adhesion suppression mechanism. However, the coagulation treatment unit and the first adhesive force suppressing mechanism having the spheroidizing treatment unit are provided in the same tank, and the coagulation treatment performed by the coagulation treatment unit and the spheroidization performed by the first adhesive force suppression mechanism are performed. The processing may be carried out at the same time.

(Fifth Embodiment)
The water treatment apparatus and the water treatment method of the fifth embodiment are basically the same as the configurations of the water treatment apparatus and the water treatment method of the first embodiment except that the configuration of the first adhesion suppressing mechanism is different. Is. Therefore, here, the different configurations will be mainly described.

The water treatment device of the fifth embodiment includes a separation membrane having a first adhesive force suppressing mechanism and a second adhesive force suppressing mechanism. The first adhesion suppressing mechanism includes a consolidation processing unit that compacts the agglomerates contained in the water to be treated.

Here, in general, the agglomerate composed of the object to be removed and the coagulant is in the form of a gel and contains a large amount of water, so that it is easily deformed. Therefore, the agglomerates may be deformed by the pressure during filtration. When the agglomerates are deformed, the filtration resistance increases, so that the flow velocity of the water to be treated during filtration decreases. Further, when the agglomerates are deformed, the contact area between the separation membrane and the agglomerates increases, so that the adhesion force of the agglomerates to the separation membrane increases and the pores of the separation membrane are easily closed.

When the first adhesion suppressing mechanism including the consolidation processing unit compacts the agglomerates, the agglomerates are densified and compacted. The compacted agglomerates change from a easily deformable state to a less deformable state. Therefore, a decrease in the flow velocity during filtration, an increase in the adhesive force of the agglomerates, and clogging of the pores are suppressed.

Consolidation of the agglomerates is not particularly limited and is treated by known methods. For example, consolidation of agglomerates is performed by stirring while giving a G value of 75 (1 / s) or more, which is applied in stirring of a predetermined stirring intensity or more, for example, general water treatment. In addition, the state of consolidation of the agglomerates can be controlled by changing the agitation strength, the agitation time, the amount of the aggregating agent, and the like.

The state of consolidation of the agglomerates can be measured by a general measuring method such as image processing of the agglomerates and the sedimentation rate.

FIG. 13 is a graph showing the relationship between the consolidation ratio of agglomerates and the adhesive force between the separation membrane and the agglomerates in the water treatment apparatus of the fifth embodiment.

As shown in FIG. 13, as the consolidation ratio of the agglomerates increases, the adhesive force decreases. In this way, the consolidation treatment unit compacts the agglomerates, so that the adhesion of the agglomerates to the separation membrane is reduced. Therefore, the blockage of the pores of the separation membrane is suppressed, and the cleanability of the separation membrane is improved.

As described above, according to the water treatment apparatus and the water treatment method of the fifth embodiment, the first adhesive force suppressing mechanism having a consolidation treatment unit for compacting the agglomerates is provided. The higher the consolidation ratio of the agglomerates, the lower the adhesion of the agglomerates to the separation membrane, and the more the clogging of the pores of the separation membrane is suppressed. In this way, the consolidation processing unit compacts the agglomerates, so that the separation membrane can be easily washed. Therefore, the decrease in the filtration rate of the separation membrane over time can be eliminated, and the separation membrane can be filtered. You can restore speed.

A coagulation treatment unit and a first adhesion suppressing mechanism having a consolidation treatment unit are provided in separate tanks, and after the coagulation treatment performed by the coagulation treatment unit is performed, the consolidation treatment is performed by the first adhesion suppression mechanism. However, the coagulation treatment unit and the first adhesion suppressing mechanism having a consolidation treatment unit are provided in the same tank, and the coagulation treatment performed by the coagulation treatment unit and the consolidation performed by the first adhesion suppression mechanism are performed. The processing may be carried out at the same time.

Further, the first adhesive force suppressing mechanism may include the above-mentioned spherical processing unit in addition to the consolidation processing unit. When the first adhesive force suppressing mechanism includes a spheroidizing treatment unit and a consolidation processing unit, the order in which the spheroidizing treatment and the consolidation treatment are performed is not particularly limited, and the consolidation treatment is performed after the spheroidization treatment is performed. , The spheroidization treatment may be carried out after the consolidation treatment, or the spheroidization treatment and the consolidation treatment may be carried out at the same time. Preferably, the consolidation treatment is performed followed by the spheroidization treatment.

(Sixth Embodiment)
The water treatment apparatus and the water treatment method of the sixth embodiment are basically the same as the configurations of the water treatment apparatus and the water treatment method of the first embodiment except that the configuration of the first adhesion suppressing mechanism is different. Is. Therefore, here, the different configurations will be mainly described.

The water treatment device of the sixth embodiment includes a separation membrane having a first adhesive force suppressing mechanism and a second adhesive force suppressing mechanism. The first adhesive force suppressing mechanism includes a particle size control unit that controls the particle size of the agglomerates contained in the water to be treated.

Here, in general, the particle size, that is, the diameter is non-uniform in the agglomerate composed of the object to be removed and the coagulant. For agglomerates having a non-uniform particle size, agglomerates having a small particle size may enter between the agglomerates having a large particle size to form coarse agglomerates larger than the agglomerates having a large particle size. There is. When such coarse agglomerates are generated, the filtration resistance increases, so that the flow velocity of the water to be treated during filtration decreases. Further, since the agglomerates having a small particle size may pass through the pores without being trapped by the pores of the separation membrane, the trapping rate of the agglomerates by the separation membrane may decrease. Furthermore, agglomerates having a small particle size may enter the pores and adhere to the inner peripheral surface of the pores, thereby closing the pores.

When the first adhesive force suppressing mechanism provided with the particle size control unit controls the particle size of the agglomerates, the agglomerates are processed to have a desired particle size, and the particle size of the agglomerates is controlled and made uniform. When the particle size of the agglomerates becomes uniform, the formation of coarse agglomerates as described above is suppressed, and the amount of agglomerates having a small particle size decreases. Therefore, a decrease in the flow velocity during filtration, a decrease in the capture rate of aggregates, a blockage of pores, and the like are suppressed.

The particle size control of the agglomerates is not particularly limited, and is processed by a known method. For example, the particle size control treatment of the agglomerates is performed by stirring. For example, a large particle size can be obtained by weakening the stirring intensity, lengthening the stirring time, and increasing the amount of the coagulant. On the contrary, when it is desired to obtain a small particle size, the particle size of the agglomerates can be controlled by changing the stirring intensity, the stirring time, the amount of the coagulant, etc. by performing the reverse operation.

The particle size of the agglomerates can be measured by a general measuring method such as a laser diffraction method, a dynamic light scattering method, or image processing.

FIG. 14 is a graph showing the relationship between the pitch size / particle size of the agglomerates and the van der Waals force between the separation membrane and the agglomerates in the water treatment apparatus of the sixth embodiment. Here, the size of the pitch / the particle size of the agglomerates is controlled as the particle size when a plurality of hemispherical protrusions having a uniform size are formed on the surface of the separation membrane at a uniform pitch. It is the ratio of the size of the pitch to the particle size of the agglomerate. Further, on the surface of the separation membrane, the portion where the convex portion is not formed is a smooth surface.

For example, when the pitch size / agglomerate particle size value is 1.00 or more, the agglomerate particle size is less than or equal to the pitch size, so that the agglomerates come into contact with the smooth surface of the separation membrane. .. On the other hand, when the pitch size / agglomerate particle size value is smaller than 1.00, the agglomerate particle size is larger than the pitch size, so that the agglomerates come into contact with the smooth surface of the separation membrane. Do not make point contact with the convex part.

As shown in FIG. 14, when the pitch size / agglomerate particle size value is less than 1.00, the van der Waals force decreases as the pitch size / agglomerate particle size value increases. To do. Then, when the pitch size / particle size value of the agglomerates becomes 1.00 or more, the van der Waals force increases sharply. In this way, the particle size control unit controls the particle size of the agglomerates according to the size of the uneven structure of the separation membrane, so that the adhesive force of the agglomerates to the separation membrane is reduced. Therefore, the blockage of the pores of the separation membrane is suppressed, and the cleanability of the separation membrane is improved.

As described above, according to the water treatment apparatus and the water treatment method of the sixth embodiment, the first adhesive force suppressing mechanism including the particle size control unit for controlling the particle size of the agglomerates is provided. When the particle size of the agglomerates whose particle size is controlled is larger than the size of the pitch, the closer the particle size of the agglomerates to the size of the pitch, the lower the adhesion force of the agglomerates to the separation membrane, and the pores of the separation membrane. Blockage is suppressed. In this way, the particle size control unit controls the particle size of the agglomerates according to the size of the uneven structure of the separation membrane, so that the separation membrane can be easily washed. Therefore, the filtration rate of the separation membrane It is possible to recover the filtration rate of the separation membrane by eliminating the decrease over time.

A coagulation treatment unit and a first adhesive force suppressing mechanism having a particle size control unit are provided in separate tanks, and after the coagulation treatment performed by the coagulation treatment unit is performed, the particle size control is performed by the first adhesive force suppression mechanism. The treatment may be carried out, but a coagulation treatment unit and a first adhesive force suppressing mechanism having a particle size control unit are provided in the same tank, and the coagulation treatment performed by the coagulation processing unit and the grains performed by the first adhesive force suppressing mechanism are performed. The diameter control process may be performed at the same time.

Further, the first adhesive force suppressing mechanism may include at least one of the above-mentioned spherical processing unit and consolidation processing unit in addition to the particle size control unit. When the first adhesive force suppressing mechanism includes a spheroidizing treatment unit, a consolidation processing unit, and a particle size control unit, the order in which the spheroidization treatment, the consolidation treatment, and the particle size control treatment are performed is not particularly limited. Instead, the spheroidizing treatment, the consolidation treatment, and the particle size control treatment may be performed at the same time.

(7th Embodiment)
The water treatment apparatus and the water treatment method of the seventh embodiment are basically the same as the configurations of the water treatment apparatus and the water treatment method of the first embodiment except that the configuration of the first adhesive force suppressing mechanism is different. Is. Therefore, here, the different configurations will be mainly described.

The water treatment device of the seventh embodiment includes a separation membrane having a first adhesive force suppressing mechanism and a second adhesive force suppressing mechanism. The first adhesive force suppressing mechanism includes a surface potential control unit that controls the surface potential of the agglomerates contained in the water to be treated.

Here, in general, in the coagulation treatment performed by the coagulation treatment unit 3 shown in FIG. 1, a coagulant having a polarity opposite to the polarity of the surface potential of the object to be removed is added to the water to be removed to remove the object to be removed. By electrically neutralizing the surface potential of the sol, the object to be removed is agglomerated. Therefore, the surface potential of the agglomerate composed of the object to be removed and the aggregating agent is close to 0, and the agglomerate is in a state of easily adhering to the separation membrane. When the agglomerates in such a state are filtered by the separation membrane, the agglomerates may easily adhere to the separation membrane, so that the flow velocity of the water to be treated during filtration is lowered, the cleanability of the separation membrane is lowered, and so on. It may cause blockage of holes formed in the separation membrane.

When the first adhesive force suppressing mechanism provided with the surface potential control unit controls the surface potential of the agglomerate to make the polarity of the surface potential of the agglomerate the same as the polarity of the separation membrane, between the agglomerate and the separation membrane. Repulsive force works. When the repulsive force acts between the agglomerate and the separation membrane, the adhesion force of the agglomerate to the separation membrane is reduced. Therefore, a decrease in the flow velocity during filtration, a decrease in the detergency of the separation membrane, a blockage of pores, and the like are suppressed. Furthermore, when the polarity of the aggregate and the polarity of the separation membrane are the same, the repulsive force acting between the aggregate and the separation membrane increases as the surface potential of the aggregate increases.

The control of the surface potential of the agglomerates is not particularly limited and is processed by a known method. For example, the surface potential of the agglomerates is controlled by changing the pH of the water to be treated. Further, the surface potential control treatment of the agglomerates is also performed by adding a potential control agent for controlling the surface potential of the agglomerates to the water to be treated containing the agglomerates. The potential control agent is appropriately selected according to the polarity of the separation membrane. When the separation membrane has a positive polarity, a cationic potential control agent is added to the water to be treated to positively charge the surface potential of the aggregate. When the separation membrane has a negative polarity, an anionic potential control agent is added to the water to be treated to negatively charge the surface potential of the aggregate.

The surface charge of the agglomerates can be measured by a general measuring method such as a microscope electrophoresis method, a rotational diffraction grating method, or a laser Doppler electrophoresis method.

The surface potential control unit controls the surface potential of the agglomerate so that the polarity of the surface potential of the agglomerate becomes the same as the polarity of the surface potential of the separation membrane, so that the adhesive force of the agglomerate to the separation membrane is reduced. Therefore, the blockage of the pores of the separation membrane is suppressed, and the cleanability of the separation membrane is improved. Further, when the polarity of the agglomerates and the polarity of the separation membrane are the same, as the magnitude of the surface potential of the agglomerates increases, the adhesive force of the agglomerates to the separation membrane further decreases.

As described above, according to the water treatment apparatus and the water treatment method of the seventh embodiment, the first adhesive force suppressing mechanism including the surface potential control unit for controlling the surface potential of the agglomerates is provided. The polarity of the surface potential of the agglomerate and the polarity of the surface potential of the separation membrane are the same, and further, the larger the surface potential of the agglomerate, the lower the adhesion of the agglomerate to the separation membrane, and the pores of the separation membrane Occlusion is suppressed. In this way, the surface potential control unit controls the surface potential of the agglomerates according to the surface potential of the separation membrane, so that the separation membrane can be easily washed. Therefore, the filtration rate of the separation membrane over time. The reduction can be eliminated and the filtration rate of the separation membrane can be restored.

It should be noted that the surface potential control performed by the first adhesive force suppressing mechanism after the coagulation treatment performed by the coagulation processing unit is performed by providing the coagulation processing unit and the first adhesive force suppressing mechanism having the surface potential control unit in separate tanks. The treatment may be carried out, but the coagulation treatment unit and the first adhesive force suppressing mechanism having the surface potential control unit are provided in the same tank, and the coagulation treatment performed by the coagulation processing unit and the surface performed by the first adhesive force suppressing mechanism are provided. The potential control process may be performed at the same time.

Further, the first adhesive force suppressing mechanism may include at least one of the above-mentioned spheroidizing processing unit, consolidation processing unit, and particle size control unit in addition to the surface potential control unit. When the first adhesive force suppressing mechanism includes a spheroidizing processing unit, a compaction processing unit, a particle size control unit, and a surface potential control unit, the spheroidizing treatment, the compaction processing, the particle size control processing, and the surface potential control processing are performed. The order of execution is not particularly limited, and the spheroidizing treatment, the compaction treatment, the particle size control treatment, and the surface potential control treatment may be carried out at the same time.

According to at least one embodiment described above, the adhesive force between the separation membrane and the agglomerates contained in the water to be treated is suppressed, the agglomerates adhere to the separation membrane, and the pores of the separation membrane are closed by the agglomerates. It is possible to provide a water treatment apparatus and a water treatment method that can suppress the above-mentioned problems and improve the cleanability of the separation membrane.

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 novel embodiments can be implemented in various other embodiments, 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, and are also included in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Water treatment equipment, 2 ... Water storage unit to be treated, 3 ... Aggregation treatment unit, 4 ... First adhesion suppression mechanism, 5 ... Separation unit, 6 ... Treated water storage unit, 7 ... Water treatment equipment, 8 ... No. 2 Adhesive force suppressing mechanism, 9 ... Aggregates, 10 ... Separation membrane, 11 ... Holes, 12 ... Recessions, 12a ... Bottom surface, 13 ... Convex parts, 14 ... Water to be treated, 15 ... Treated water, 16 ... Channels.

Claims (8)

A water treatment device that separates the agglomerates from water to be treated, which contains agglomerates composed of an object to be removed and a coagulant that agglomerates the agglomerates, via a separation membrane.
The separation membrane comprising at least one selected from a spheroidizing treatment unit for spheroidizing the agglomerates, a consolidation treatment unit for compacting the agglomerates, and a particle size control unit for controlling the particle size of the agglomerates. A first adhesive force suppressing mechanism that suppresses the adhesive force of the agglomerates against
Wherein comprises a separation membrane, and a separation unit for have a second attachment force suppression mechanism having an uneven structure on the surface of the separation membrane,
The second adhesive force suppressing mechanism is a water treatment device characterized in that the width of the concave portion of the concave-convex structure is smaller than the diameter of the agglomerate. A water treatment device that separates the agglomerates from water to be treated, which contains agglomerates composed of an object to be removed and a coagulant that agglomerates the agglomerates, via a separation membrane.
The separation membrane comprising at least one selected from a spheroidizing treatment unit for spheroidizing the agglomerates, a consolidation treatment unit for compacting the agglomerates, and a particle size control unit for controlling the particle size of the agglomerates. A first adhesive force suppressing mechanism that suppresses the adhesive force of the agglomerates against
Wherein comprises a separation membrane, and a separation unit for have a second attachment force suppression mechanism having an uneven structure on the surface of the separation membrane,
The separation membrane is made of a porous membrane having a plurality of holes penetrating in a direction perpendicular to the surface, and the uneven structure is provided in a portion where the penetrating holes are not formed. apparatus. The water treatment apparatus according to claim 1 or 2, wherein the second adhesive force suppressing mechanism includes a hydrophilic portion formed on the surface of the separation membrane. The water treatment apparatus according to any one of claims 1 to 3, wherein the second adhesive force suppressing mechanism includes a charged portion formed on the surface of the separation membrane. The water treatment apparatus according to any one of claims 1 to 4, wherein the first adhesive force suppressing mechanism includes the spherical treatment unit and the particle size control unit. The water treatment apparatus according to any one of claims 1 to 5 , wherein the first adhesive force suppressing mechanism includes a surface potential control unit that controls the surface potential of the aggregate. A water treatment method for separating the agglomerates from water to be treated, which contains agglomerates composed of an object to be removed and a coagulant that agglomerates the agglomerates, via a separation membrane.
A first adhesive force suppression including at least one selected from a spheroidizing treatment unit for spheroidizing the agglomerates, a consolidation treatment unit for compacting the agglomerates, and a particle size control unit for controlling the particle size of the agglomerates. A step of suppressing the adhesion of the agglomerates to the separation membrane by a mechanism, and
After the step of suppressing the adhesive force, the adhesive force to the separation membrane was suppressed via a separation portion including the separation membrane and having a second adhesive force suppressing mechanism having a concavo-convex structure on the surface of the separation membrane. It has a step of separating the agglomerate from the water to be treated .
The second adhesive force suppressing mechanism is a water treatment method characterized in that the width of the concave portion of the concave-convex structure is smaller than the diameter of the agglomerate. A water treatment method for separating the agglomerates from water to be treated, which contains agglomerates composed of an object to be removed and a coagulant that agglomerates the agglomerates, via a separation membrane.
A first adhesive force suppression including at least one selected from a spheroidizing treatment unit for spheroidizing the agglomerates, a consolidation treatment unit for compacting the agglomerates, and a particle size control unit for controlling the particle size of the agglomerates. A step of suppressing the adhesion of the agglomerates to the separation membrane by a mechanism, and
After the step of suppressing the adhesive force, the adhesive force to the separation membrane was suppressed via a separation portion including the separation membrane and having a second adhesive force suppressing mechanism having a concavo-convex structure on the surface of the separation membrane. It has a step of separating the agglomerate from the water to be treated .
The separation membrane is made of a porous membrane having a plurality of holes penetrating in a direction perpendicular to the surface, and the uneven structure is provided in a portion where the penetrating holes are not formed. Method.

Images