WO2013145372A1

WO2013145372A1 - Water treatment filter aid and water treatment method

Info

Publication number: WO2013145372A1
Application number: PCT/JP2012/073191
Authority: WO
Inventors: 深谷　太郎; 厚山崎; 剣治堤; 伊知郎山梨
Original assignee: 株式会社東芝
Priority date: 2012-03-29
Filing date: 2012-09-11
Publication date: 2013-10-03
Also published as: TWI444228B; IN2014DN07415A; JP5583162B2; TW201338861A; JP2013202569A

Abstract

This filter aid comprises an aggregate resulting from a plurality of magnetic primary particles aggregating. The magnetic primary particles have: magnetic inorganic particles having an average particle size of 5-40 μm inclusive; and a coating layer that covers some or all of the surface of the magnetic inorganic particles and contains an organic fluorine compound supported by the magnetic inorganic particles. The value of the circularity of a 2D projected image projected onto a plane in a microscope field of view is in the range of at least 0.40 and less than 1.00 (not including 1.00).

Description

Filter aid for water treatment and water treatment method

Embodiment described here is related with the filter aid for water treatment used repeatedly and removing the foreign material, such as the solid substance contained in water, and the water treatment method using the same.

Recently, the effective use of water resources is required due to industrial development and population growth. For this purpose, it is very important to reuse industrial wastewater and other wastewater. In order to achieve these, it is necessary to purify the water, ie to separate other substances from the water. Various methods are known as methods for separating other substances from the liquid, such as membrane separation, centrifugation, activated carbon adsorption, ozone treatment, removal of suspended substances by aggregation, and the like. By such a method, chemical substances having a great influence on the environment such as phosphorus and nitrogen contained in water can be removed, and oils and clays dispersed in water can be removed.

Among these various water treatment methods, the membrane separation method is one of the most commonly used methods for removing insoluble substances in water. From the viewpoint of increasing the water flow rate of the contained water, filter aids are used in membrane separation methods.

On the other hand, as a method for removing harmful substances and valuables from water, a method of causing some reaction to precipitate in a substance dissolved in water and precipitating and solid-liquid separation is known. For example, Patent Document 1 describes a method of removing a hardly filterable substance such as algae by adding a paramagnetic substance powder to a waste liquid.

JP 09-327611 A

However, in the conventional method, the zeta potential of the paramagnetic substance and the algae are close to each other, it is very difficult to separate after removal from water, and the paramagnetic substance is difficult to reuse. Even when a water-containing solid such as a hydroxide is removed using a magnetic filter aid, it may be difficult to separate the magnetic filter aid and the water-containing solid.

The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a water treatment filter aid that can remove fine foreign matters existing in water and is easy to reuse, and a water treatment method using the same. And

FIG. 1A is a schematic cross-sectional view showing magnetic inorganic particles coated with fluoride. FIG. 1B is a schematic cross-sectional view showing a particle aggregate in which magnetic primary particles are aggregated. FIG. 2A is a schematic diagram for explaining the circularity of the particle aggregate. FIG. 2B is a schematic diagram for explaining the circularity of the particle aggregate. FIG. 2C is a schematic diagram for explaining the circularity of the particle aggregate. FIG. 3A is a schematic diagram for explaining the circularity of the particle aggregate. FIG. 3B is a schematic diagram for explaining the circularity of the particle aggregate. FIG. 3C is a schematic diagram for explaining the circularity of the particle aggregate. FIG. 4 is a schematic diagram showing a state in which foreign matter is sandwiched between particles. FIGS. 5A, 5B, and 5C are schematic views showing a reaction mechanism between a silane coupling agent and an inorganic surface. FIG. 6 is a schematic diagram illustrating a reaction mechanism between a silane coupling agent and an inorganic surface. FIG. 7 is a schematic view showing a formation reaction of polyimide amide. FIG. 8 is a characteristic diagram showing an example of distribution of interparticle pore diameter (interparticle spacing) S in sample A. FIG. 9 is a photomicrograph showing an enlarged view of the particles of Sample A. FIG. 10 is a characteristic diagram showing an example of the distribution of interparticle pore size (interparticle spacing) S and the distribution of intraparticle pore size in Sample C, respectively. FIG. 11 is a photomicrograph showing an enlarged view of the particles of Sample C. FIG. 12 is a configuration block diagram showing an outline of a water treatment apparatus using the particles of the first embodiment. FIG. 13 is a process diagram showing a water treatment method (body feed method) of the first embodiment using the apparatus of FIG. FIG. 14 is a configuration block diagram showing an outline of another water treatment apparatus using the particles of the second embodiment. FIG. 15 is a process diagram showing a water treatment method (precoat method) of a second embodiment using the apparatus of FIG.

Hereinafter, various preferred embodiments will be described.

(1) The filter aid for water treatment according to the embodiment described herein adsorbs foreign substances contained in the water to be treated, and is separated from the water to be treated by membrane filtration together with the adsorbed foreign substances, and separated by membrane filtration. It is a filter aid for water treatment that is magnetically separated from foreign substances in it and is repeatedly used. The filter aid is composed of an aggregate of a plurality of magnetic primary particles, and the magnetic primary particles are averaged. And a magnetic inorganic particle having a particle size of 5 μm or more and 40 μm or less, a coating layer that covers a part or all of the surface of the magnetic inorganic particle and contains a fluorine organic compound supported on the magnetic inorganic particle, and The circularity value of the two-dimensional projection image projected on the plane in the microscope field is in the range of 0.40 or more and less than 1.00 (excluding 1.00).

In the embodiment described here, the average particle diameter d ₁ of the magnetic primary particles is in the range of 5 μm to 40 μm (FIG. 1A). When the average particle diameter d ₁ of the magnetic primary particles is less than 5 [mu] m, the particles become too small distance between particles too densely aggregated as a filter aid, effective through water it is difficult to obtain. On the other hand, when the average particle diameter d ₁ of the magnetic primary particles exceeds 40 μm, the particles are coarsely aggregated and the distance between the particles becomes too large, and it becomes easy for foreign substances (fine particles, valuables or harmful substances) in water to pass through. , May not work as a filter aid. Further, it is more preferable that the average particle diameter d ₁ of the magnetic primary particles is in the range of 10 to 25 μm. When the average particle diameter d ₁ of the magnetic primary particles is 25 μm or less, the removal efficiency of foreign matters from water is further increased. On the other hand, when the average particle diameter d ₁ of the magnetic primary particles is 10 μm or more, the water flow rate is further increased and the treatment efficiency is improved. Magnetic primary particles having an average particle diameter d _{1 in} the range of 10 to 25 μm are the most preferable range with a good balance between the foreign matter removal efficiency and the water flow rate.

In the embodiment described herein, the magnetic inorganic particles and the coating layer are adjusted so that the circularity value of the two-dimensional projection image projected in the microscope field falls within the range of 0.40 or more and less than 1.00 (excluding 1.00).

Here, the “circularity” is given by the following equation (1) using the perimeter and area of the two-dimensional projection image when the object is projected onto a plane, and the contour shape of the two-dimensional projection image is a circle. It is defined as a coefficient that quantifies the degree of whether it is close or far.

CR = 4πA / L ² (1)
Here, CR is circularity, L is the perimeter of the two-dimensional projection image, and A is the area of the two-dimensional projection image.

The closer the circularity value is to 1, the closer the shape is to a circle, and the farther the circularity value is from 1, the more distorted the shape is from the circle. Incidentally, the shape when the value of circularity is equal to 1 is a perfect circle.

As long as the value of circularity is in the range of 0.40 or more and less than 1.00, the shape of the magnetic primary particles may be spherical, polyhedral or amorphous. The filter aid having a circularity value in the range of 0.40 or more and less than 1.00 improves the amount of water passing through the surface and increases the water flow rate, and increases the aspect ratio of the magnetic primary particles, thereby increasing the spacing S between the magnetic primary particles. Therefore, the desired water flow rate can be secured while capturing water-insoluble solids in water. When the circularity value is further in the range of 0.40 to 0.90, and further in the range of 0.43 to 0.84, a desired level of water-insoluble solid removal efficiency can be obtained, and the water flow rate is further increased to improve the treatment efficiency. (Table 1, Table 2).

(2) In the above (1), the magnetic inorganic particles are preferably made of a ferrite compound.

Various ferrite compound particles can be suitably used as the magnetic inorganic particles. Ferrite compounds such as iron, iron-based alloys, magnetite (magnetite), titanite (ilmenite), pyrrhotite (pilotite), magnesia ferrite, manganese magnesium ferrite, manganese zinc ferrite, cobalt ferrite, nickel ferrite, nickel zinc ferrite, barium Ferrite, copper zinc ferrite, etc. can be used. Of these, it is most preferable to use a ferrite-based compound such as magnetite, magnesia ferrite, or manganese magnesium ferrite having excellent stability in water. In particular, magnetite (Fe ₃ O ₄ ) is not only inexpensive, but also exhibits stable properties as a magnetic substance in water and is composed of only safe and non-toxic elements, so it is used for water treatment. Suitable for

As described above, the average particle diameter d ₁ of the magnetic primary particles is preferably in the range of 5 to 40 μm. The average particle diameter d ₁ of the magnetic primary particles is more preferably in the range of 10 to 25 μm, and most preferably 20 ± 5 μm. When the average particle diameter d ₁ of the magnetic primary particles is less than 5 μm, the particles as the filter aid are too densely aggregated, the distance S between the particles becomes too small, and it becomes difficult to obtain an effective water flow rate. On the other hand, when the average particle diameter d ₁ of the magnetic primary particles exceeds 40 μm, the particles are coarsely aggregated and the distance S between the particles becomes too large, and it becomes easy for fine particles (valuable or harmful substances) in water to pass through. There is a possibility that it may not function effectively as a filter aid. Further, when the average particle diameter d ₁ of the magnetic primary particles is in the range of 10 to 25 μm, the balance between the collection efficiency (removal efficiency) of foreign matter in water and the amount of water flow is improved. Here, an average particle diameter is a volume average (Mean Volume Diameter). The average particle diameter is measured by a laser diffraction method. For example, the average particle diameter can be measured with a SALD-DS21 type measuring device (trade name) manufactured by Shimadzu Corporation.

(3) In the above (1), in the distribution of the mutual spacing S of the magnetic primary particles, the mode P _a, the mode is better distribution width D _S of the smaller interval than the interval at P _c1 P _a, with P _c1 It is preferable that the distribution width D _L is larger than the interval of (Figs. 8, 10, and 4).

In the embodiment described here, in the distribution of the mutual spacing (interparticle pore diameter) S of the particles in the aggregate, the distribution width D _S of the spacing smaller than the spacing in the mode values P _a and P _c1 . _Is made wider than the distribution width D _L of the interval larger than the interval between the mode values P _a and P _c1 . Such an asymmetric distribution is called a non-normal distribution or an extreme value distribution. In such a non-normal distribution, since the distribution is wide from a small interval to a large interval between particles, water-insoluble solids 59 in water are first sandwiched between small mutual intervals (gap) between particles, and the gap is initially Even if the solid material 59 is sandwiched between the particles 50, even if the solid material 59 is blocked, a force is applied to both the solid material 59 and the particles 50, and the solid material 59 and the particles 50 are displaced and deformed, respectively. Thereby, the opening diameter of the open pores 56 changes, and the solid matter 59 is easily captured by the changed open pores 56. By this action, the filter aid of the present embodiment improves the ability to capture the solid material 59 having a diameter smaller than the mutual interval S between the mode values P _a and P _c1 . The interparticle pore size S in the aggregate can be measured by a pore distribution measurement method using a mercury press-in method. For example, the pore size S between particles in the aggregate can be measured using Autopore IV 9500 series (trade name) manufactured by Shimadzu Corporation.

(4) In the above (1), the magnetic inorganic particles have an apparent specific gravity greater than 1, have a large number of open pores opened on the surface, and the diameter of the open pores is larger than the mutual spacing S of the magnetic primary particles. It is preferable that it is small (FIG. 4).

In the embodiment described here, it has open pores 56 having pore diameters d3 and d4 smaller than the mutual spacing S of the magnetic primary particles (relationship d3, d4 <S in FIG. 4). In order to increase the water flow rate, use porous magnetic particles as filter aids, or use particles with irregularities on the surface, or spherical particles and irregular particles with linear parts. It is effective to use in combination. These measures can be implemented by adjusting the circularity value of the magnetic particles to a range of 0.40 to 1.00. When fine solids 59 in water are captured by pores having an interparticle pore size S, if small open pores 56 are present in the vicinity thereof, another flow path for bypassing water is formed. Becomes larger. The diameters d3 and d4 of the open pores 56 can be analyzed by measuring the pore distribution by the mercury intrusion method described above. When measured by the mercury intrusion method, data having two pore distributions having different pore diameters can be obtained. For example, as shown in FIG. 10, the small pore distribution C2 corresponds to the diameter distribution of the open pores 56, and the large pore distribution C1 corresponds to the distribution of the interparticle pore diameter S.

(5) In (1) above, the fluorine organic compound is preferably obtained by reacting a compound having a fluorocarbon and an alkoxy group with the surface of the magnetic inorganic particles (FIGS. 5, 6, and 7).

In the embodiment described here, by supporting fluorocarbon on the surface of the magnetic inorganic particles, the surface energy of the magnetic primary particles is reduced, and foreign substances adsorbed in water (such as solids) are easily desorbed, Separation of the adsorbed foreign matter and the filter aid is promoted. This facilitates the recovery of the filter aid from the water.

As a method of supporting the fluorine organic compound (fluorocarbon) on the magnetic inorganic particles serving as the carrier, a method of directly modifying the magnetic inorganic particles using a silane coupling agent, and a method of coating the magnetic inorganic particles with a resin (or polymer) There is.

In the method of directly modifying the surface of the magnetic inorganic particle with a silane coupling agent, a compound having a fluorocarbon and an alkoxy group is reacted with the surface of the magnetic inorganic particle to carry the fluorocarbon on the surface of the particle. Here, “combination” refers to the addition of a functional group to the surface of magnetic inorganic particles. “Attaching a functional group” means that the functional group and the magnetic inorganic particles are chemically bonded at least chemically. A combination of a chemical bond and a physical bond such as adsorption is also called a combination. It should be noted that the magnetic inorganic particles and the functional group are not chemically bonded, and the two are simply physically bonded, which is not a combination. However, as an exception, there is a case where a combination is made only when the entire surface of the magnetic inorganic particles is covered with a polymer having a specific functional group.

The modification method includes a dry method and a wet method. The dry method is a method of spraying a silane coupling agent solution while stirring magnetic inorganic particles at high speed. The wet method is a method of reacting particles in a solvent containing a silane coupling agent. In any of the dry method and the wet method, the solvent is volatilized after the treatment to cure the silane coupling agent. It is also possible to cause the fluorocarbon to be supported on the magnetic inorganic particles by reacting the fluorocarbon with a compound having an alkoxy group.

On the other hand, there are two methods for resin coating. One method is to coat a resin having a fluorocarbon and an alkoxy group. Another method is a method in which a resin having a reactive functional group on the side chain is coated and a compound having a fluorocarbon and an alkoxy group is reacted. In the former method, first, a resin having a fluorocarbon and an alkoxy group is coated on magnetic inorganic particles, a compound in the resin is reacted with the magnetic inorganic particles, and the compound is supported on the surface of the particles.

Fluorocarbons include polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), perfluoroethylene propene copolymer (PFEP), polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene- Ethylene copolymer (ETFE), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), and the like can be used. These are compounds containing an F—C bond, and make the surface properties of the particles hydrophobic when supported on the surface of the magnetic inorganic particles.

A silane coupling agent is a reactant that contributes to two reactions, a hydrolysis reaction and a condensation reaction. In the hydrolysis reaction, the hydroxyl group M-OH (M is a metal atom) on the ferrite particle surface and the alkoxy group (RO-Si) contained in the silane coupling agent undergo a dealcoholization reaction, or (a) in FIG. b) and the reaction with water as shown in FIG. 6, the alkoxy group (RO-Si) contained in the silane coupling agent is hydrolyzed, thereby producing a silanol group, and the hydroxyl group on the surface of the magnetic inorganic particles It moves to the surface of the magnetic inorganic particle through the hydrogen bond. The hydrolysis rate of the silane coupling agent molecule depends on the surface state of the magnetic inorganic particles. That is, the hydrolysis rate of silane coupling agent molecules is affected by the pH of the surface of the magnetic inorganic particles and the amount of adsorbed water.

On the other hand, in the condensation reaction, as shown in FIGS. 5B and 5C and FIG. 6, the silane coupling agent undergoes a dehydration condensation reaction to generate a strong covalent bond with the surface of the magnetic inorganic particles. In parallel with this reaction, silanol groups are condensed to produce a siloxane oligomer. These reactions can be accelerated in the presence of heat or catalyst. Moreover, these reactions can be accelerated | stimulated by discharging | emitting water and alcohol byproduced by heating and drying a coating compound out of a system. Since the organic functional groups of the silane coupling agent molecules are oriented outside the magnetic inorganic particles, the optimal mixing ratio of solvent and solute is selected in consideration of the balance between hydrophilicity and hydrophobicity of the silane coupling agent solution. There is a need to.

An example of a reaction when producing a compound having an alkoxy group will be described with reference to FIG. The compound having an alkoxy group is one of raw materials used for the reaction when a fluorine organic compound is supported on magnetic inorganic particles. Here, an outline of the reaction when generating an organic compound containing an amide (N—C═O) and an imide (O═C—N—C═O) shown in FIG. 7 as the compound having an alkoxy group will be described.

First, pyromellitic anhydride (tetracarboxylic acid dianhydride) and diaminodiphenylmethane are polymerized in equimolar amounts to produce polyamic acid (polyamic acid) which is a polyimide precursor. Next, the polyamic acid is heated or a dehydration / cyclization (imidization) reaction is promoted using a catalyst to obtain a polyimide as a compound having an alkoxy group. The polyimide thus obtained is mixed with a tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA) as a fluorocarbon to obtain a mixture of fluorine organic compounds. When this mixture of fluorine organic compounds is reacted with magnetic inorganic particles by a wet method, PFA as a fluorine organic compound is supported (modified) on the surfaces of the magnetic inorganic particles.

(6) In (1) above, the foreign matter is a water-insoluble solid contained in the water to be treated, and the water-insoluble solid can be removed from the water to be treated using a filter aid.

Examples of water-insoluble zero-soluble solids that are targeted include non-magnetic inorganic particles such as sand, metal particles such as copper and lead, and polymer organic compound fibers such as cellulose.

(7) In the water treatment method according to the embodiment described herein, the foreign substances contained in the water to be treated are adsorbed to the filter aid, and the filter aid is separated from the treated water together with the adsorbed foreign matters by membrane filtration. In the water treatment method in which the filter aid is magnetically separated from the foreign matter in the separated substance after membrane filtration and the separated filter aid is repeatedly used, (A) magnetic inorganic particles having an average particle size of 5 μm or more and 40 μm or less; A two-dimensional projection image that covers a part or all of the surface of the magnetic inorganic particles and has a coating layer containing a fluorine organic compound supported by the magnetic inorganic particles, and is projected onto a plane in a microscope field of view Magnetic primary particles having a circularity value of 0.40 or more and less than 1.00 (excluding 1.00) are prepared, and an aggregate in which a plurality of the magnetic primary particles are aggregated is prepared as the filter aid, and (B) water Treatments containing insoluble solids Mixing physical water and the filter aid, producing a suspension in which the filter aid is dispersed in the water to be treated, (C) filtering the suspension with a filter membrane, A deposition layer containing the filter aid and the water-insoluble solid is formed, and the water-insoluble solid is adsorbed and trapped by the filter aid in the deposition layer, whereby the water-insoluble from the treated water. (D) Peeling water is poured into the deposited layer to separate the deposited layer from the filtration membrane, thereby removing the deposited layer separated from the deposited layer that has captured the water-insoluble solid. Providing a mixture with water; (E) magnetically separating the filter aid from the mixture; and (F) reusing the separated filter aid in the step (B).

The water treatment method of the above embodiment is a method corresponding to the body feed method. Disperse the specific filter aid in the water to be treated, adsorb the water-insoluble solid matter to the filter aid, and pass the water to be treated in the adsorption state of the filter aid / solid matter through the filter membrane, A deposited layer comprising a filter aid / solid mixture is formed on the filter membrane. Next, the peeling water is sprayed from the side toward the deposition layer on the filtration membrane, the deposition layer is peeled off from the filtration membrane, the peeling water is further sprayed on the separation, and the separated matter is decomposed into pieces. To do. Subsequently, the decomposed exfoliated material is sent from the solid-liquid separation device to the separation tank together with exfoliated water, and the exfoliated material is stirred in the separation tank until it becomes a particle state, and the filter aid and the metal compound particles are uniformly dispersed in water. Next, the filter aid dispersed in water is magnetically adsorbed on the magnet, and while the filter aid is adsorbed on the magnet, the treated water containing solid matter is discharged from the magnetic separation tank to the collection storage tank. Next, the magnetic adsorption of the filter aid by the magnet is released, the filter aid is dropped from the magnet protective tube, and treated water or tap water is sprayed onto the magnet protective tube, and the filter aid adhering to the magnet protective tube is washed with water. To do. The filter aid washed with water is sent from the magnetic separation tank to the filter aid supply device, and is reused for producing a suspension in the filter aid supply device.

In the water treatment method of the above embodiment, the circularity value of the magnetic primary particles constituting the filter aid is in the range of 0.40 or more and less than 1.00 (excluding 1.00). Therefore, in the distribution shown in FIG. 8 and FIG. Shikichi P _a, towards the distribution width D _S of smaller spacing than the spacing becomes wider than the distribution width D _L mode value P _a, larger spacing than the spacing at the P _c1 in P _c1. Thereby, the amount of water flow can be increased while capturing fine particles, and the processing efficiency is improved. Moreover, since the filter aid is excellent in separability and durability, the filter aid can be used repeatedly. The separated filter aid can be discharged and transferred efficiently and smoothly and can be reused repeatedly. Thereby, there is an advantage that the operating cost and the maintenance cost can be kept low.

(8) In the water treatment method according to the embodiment described herein, foreign substances contained in the water to be treated are adsorbed on the filter aid, and the filter aid is separated from the water to be treated together with the adsorbed foreign substances by membrane filtration. In the water treatment method in which the filter aid is magnetically separated from the foreign matter in the separated substance after membrane filtration and the separated filter aid is repeatedly used, (a) magnetic inorganic particles having an average particle diameter of 5 μm or more and 40 μm or less; A two-dimensional projection image that covers a part or all of the surface of the magnetic inorganic particles and has a coating layer containing a fluorine organic compound supported by the magnetic inorganic particles, and is projected onto a plane in a microscope field of view A magnetic primary particle having a circularity value of 0.40 or more and less than 1.00 (excluding 1.00), and preparing an aggregate in which a plurality of the magnetic primary particles are aggregated as the filter aid; (b) Mixing dispersion medium with filter aid And preparing a suspension in which the filter aid is dispersed in the dispersion medium, (c) filtering the suspension through a filter membrane, and forming a precoat layer containing the filter aid on the filter membrane. Then, water to be treated containing water-insoluble solid matter is passed through the precoat layer and the filtration membrane, and the water-insoluble solid matter is adsorbed and captured by the filter aid of the precoat layer, thereby treating Separating the water-insoluble solid from the water; and (d) pouring stripping water onto the precoat layer to peel the precoat layer from the filtration membrane, thereby capturing the water-insoluble solid. A mixture of the exfoliated product and the exfoliated water is provided, (e) the filter aid is magnetically separated from the mixture, and (f) the separated filter aid is reused in the step (b).

The water treatment method of the above embodiment is a method corresponding to the precoat method. The specific filter aid is dispersed in a dispersion medium to prepare a suspension. This suspension is supplied to a filtration membrane of a solid-liquid separator, and a filter aid is deposited to form a desired precoat layer on the filtration membrane. Next, the water to be treated is passed through the precoat layer, and the water-insoluble solid is adsorbed and captured by the filter aid. Next, the peeling water is sprayed from the side toward the precoat layer on the filtration membrane, the precoat layer is peeled off from the filtration membrane, the peeling water is further sprayed on the peeled material, and the peeled material is decomposed into pieces. To do. Next, the decomposed exfoliated material is sent together with the exfoliated water from the solid-liquid separator to the magnetic separation tank, and the exfoliated substance is stirred in the magnetic separation tank until it becomes a particle state, and the filter aid and the solid content are uniformly dispersed in the water. . Next, the filter aid dispersed in water is adsorbed on the magnet, and the treated water containing water-insoluble solids is discharged from the magnetic separation tank while the filter aid is adsorbed on the magnet. Next, the magnetic adsorption of the filter aid by the magnet is released, the filter aid is dropped from the magnet protection tube, and further, treated water or tap water is sprayed on the magnet protection tube, and the filter aid adhered to the magnet protection tube is removed. Wash with water. The filter aid washed with water is sent from the magnetic separation tank to the filter aid supply apparatus, and is reused for producing a suspension in the filter aid supply apparatus and the mixing tank.

(Filter aid)
Next, the filter aid used in the embodiment described herein will be described in detail.

In the embodiment described here, a filter aid covered with a coating layer containing a fluorine organic compound is used. When such a filter aid is used for purification treatment of water containing water-insoluble solids, not only the filter aid is easily separated from the water, but also the filter aid used in water is separated from the water-insoluble solids. Sometimes magnetic force can be used. For this reason, it becomes possible to apply the filter aid of this embodiment to various processes. Further, the apparent specific gravity of the filter aid exceeds 1.0. For this reason, there is an advantage that the filter aid can be gravity settled in water, the precipitated filter aid can be easily separated from the water, and the selection range of the process is widened.

The filter aid is preferably a substance exhibiting ferromagnetism in a room temperature region, and a ferromagnetic substance such as a ferrite compound can be generally used. Ferrite compounds such as iron, iron-based alloys, magnetite (magnetite), titanite (ilmenite), pyrrhotite (pilotite), magnesia ferrite, manganese magnesium ferrite, manganese zinc ferrite, cobalt ferrite, nickel ferrite, nickel zinc ferrite, barium Ferrite, copper zinc ferrite, etc. can be used. Of these, it is most preferable to use a ferrite-based compound such as magnetite, magnesia ferrite, or manganese magnesium ferrite having excellent stability in water. In particular, magnetite (Fe ₃ O ₄ ) is not only inexpensive, but also exhibits stable properties as a magnetic substance in water and is composed of only safe and non-toxic elements, making it suitable for use in water treatment. ing. Further, the filter aid can take various shapes and forms such as spherical, polyhedral and irregular shapes.

In the embodiment described here, the average particle diameter d ₁ of the magnetic primary particles is in the range of 5 to 40 μm (FIG. 1A). When the average particle diameter d ₁ of the magnetic primary particles is less than 5 μm, the particles as the filter aid are too densely aggregated, the distance S between the particles becomes too small, and it becomes difficult to obtain an effective water flow rate. On the other hand, when the average particle diameter d ₁ of the magnetic primary particles exceeds 40 μm, the particles are coarsely aggregated and the distance S between the particles becomes too large, and it is easy for foreign substances (fine particles, valuables or harmful substances) in water to pass through. And may not function sufficiently as a filter aid. Further, it is more preferable that the average particle diameter d ₁ of the magnetic primary particles is in the range of 10 to 25 μm. When the average particle diameter d ₁ of the magnetic primary particles is 25 μm or less, the foreign matter removal efficiency is further increased. On the other hand, when the average particle diameter d ₁ of the magnetic primary particles is 10 μm or more, the water flow rate is further increased and the treatment efficiency is improved. Magnetic primary particles having an average particle diameter d ₁ of 10 to 25 μm have a good balance between the removal efficiency of foreign matter and the amount of water flow.

In the embodiment described here, the magnetic inorganic particles and the coating layer are adjusted so that the circularity value of the two-dimensional projection image projected onto the plane within the microscope field of view falls within the range of 0.40 to less than 1.00 (excluding 1.00). To do. If the circularity value is within this range, the shape of the magnetic primary particles may be spherical, polyhedral or amorphous. Filter aids with a circularity value in the range of 0.40 or more and less than 1.00 improve the amount of water flow through the surface and increase the aspect ratio of the magnetic primary particles, thereby increasing the mutual spacing between the magnetic primary particles. Since the aspect ratio of S is also increased, it is possible to obtain a water flow rate while capturing fine particles in water. Further, when the circularity value is 0.40 or more and 0.90 or less, and further 0.43 or more and 0.84 or less, as shown in Tables 1 and 2, a desired level of water-insoluble solid removal efficiency can be obtained, and the water flow rate is further increased. Increase the processing efficiency.

Here, the “circularity” is given by the following equation (1) using the perimeter and area of the two-dimensional projection image in which the object is projected on a plane, and the contour shape of the two-dimensional projection image is a perfect circle. It is defined as a coefficient that quantifies the degree of nearness or distance.

CR = 4πA / L ² (1)
Here, the symbol CR represents the circularity, the symbol L represents the perimeter of the two-dimensional projection image, and the symbol A represents the area of the two-dimensional projection image.

Several examples in the case of evaluating the shape of an aggregate of magnetic primary particles using circularity will be described with reference to FIGS. 2A to 2C and FIGS. 3A to 3C.

For example, as shown in FIG. 2A, FIG. 2B, and FIG. 2C, the circularity value decreases as the overall contour shape (two-dimensional projection image) of the aggregate of magnetic primary particles gradually moves away from the perfect circle. The contour shape of the entire aggregate can be quantitatively evaluated based on the circularity value measured in the microscope visual field. That is, the outline shape of the aggregate in FIG. 2A is closest to a perfect circle, and the value of the circularity CR1 is close to 1. Next, since the outline shape of the aggregate in FIG. 2B is deformed slightly away from the perfect circle, the value of the circularity CR2 is smaller than the value of the circularity CR1 of the aggregate in FIG. 2A. Next, since the outline shape of the aggregate in FIG. 2C is deformed further away from the perfect circle, the value of the circularity CR3 is further smaller than the value of the circularity CR2 of the aggregate in FIG. 2B. The relationship between these circularity values is CR3 <CR2 <CR1 <1.

Also, for example, as shown in FIGS. 3A, 3B, and 3C, the value of the circularity decreases as the surface shape (two-dimensional projection image) of the aggregate changes from a smooth one to a large one having unevenness. The contour shape of the entire aggregate can be quantitatively evaluated based on the circularity value measured in the microscope visual field. That is, since the surface shape of the aggregate of FIG. 3A is smooth, the value of the circularity CR4 becomes a high value. Next, since the surface shape of the aggregate of FIG. 3B is uneven, the value of the circularity CR5 is smaller than the value of the circularity CR4 of the aggregate of FIG. 3A. Next, since the surface shape of the aggregate in FIG. 3C is further uneven, the value of the circularity CR6 is further smaller than the value of the circularity CR5 of the aggregate in FIG. 3B. The relationship between these circularity values is CR6 <CR5 <CR4 <1.

The filter aid of the embodiments described herein, in the distribution of the mutual distance (inter-particle pore size S) of the magnetic primary particles, than the distance of the mode the better the distribution width D _S of smaller spacing than the spacing of the mode The distribution width D _L is larger than the large interval. In distribution A shown in FIG. 8, for example, it is wider than the distribution width D _L larger interval than the interval of the better of the distribution width D _S of smaller spacing than the spacing in the mode P _a in the mode P _a . Further, for example, the distribution C1 shown in FIG. 10, wider than the distribution width D _L larger interval than the interval in the mode P _c1 and towards the distribution width D _S of smaller spacing than the spacing in the mode P _c1 ing. As described above, the distribution (variation) width D _S is increased when the particle mutual interval S is smaller, and the distribution (variation) width D _L is decreased when the particle mutual interval S is larger.

In such a non-normal distribution or extreme value distribution, since there is a wide distribution from a small interval between particles to a large interval, first, fine solid matter 59 in water is sandwiched between small intervals between particles. At this time, even if the mutual space S between the magnetic primary particles 50 is closed by the solid material 59, the solid material 59 is sandwiched between the primary particles 50, whereby the surrounding primary particles 50 are deformed and the open pores 56 are expanded. Then, the solid material 59 fits into the expanded open pores 56. By this action, the filter aid improves the ability to capture the solid material 59 having a diameter smaller than the interparticle pore diameter S of the mode values P _a and P _c1 . The interparticle pore diameter S in the aggregate can be measured using, for example, Autopore IV 9500 series (trade name) manufactured by Shimadzu Corporation.

In the embodiment described here, water permeability is improved by making the filter aid porous. That is, as shown in FIG. 4, with a porous filter aid, water bypasses the open pores 56 in the primary particles 50 even when the solid particles 59 are sandwiched between the particles 50. Therefore, the water flow does not stop completely, and the necessary minimum water flow amount can be secured.

Further, in the filter aid of the embodiment described here, the diameters d ₃ and d ₄ of the open pores 56 are made smaller than the mutual spacing S of the primary particles to further improve the water permeability (d ₃ and d ₄ <S). In order to increase the water flow rate, it is effective to use porous primary particles 50 as a filter aid. In addition, when a small solid substance in water is captured by a hole having an interparticle pore size S, if a small open pore 56 exists in the vicinity thereof, another flow path for bypassing water is formed. Increases speed. The diameters d ₃ and d ₄ of the open pores 56 can be measured by a pore size distribution measuring method using a mercury intrusion method. When the pore size distribution is measured using the mercury intrusion method, data having two pore size distributions having different pore sizes can be obtained. For example, as shown in FIG. 10, the smaller intra-particle pore size distribution C2 corresponds to the distribution of the diameters d ₃ and d ₄ of the open pores 56, and the larger inter-particle pore size distribution C 1 corresponds to the distribution of the inter-particle pore size S. To do. Incidentally, the peak P _c2 (mode) of the distribution C2 of the diameters d ₃ and d ₄ of the open pores 56 is lower than the peak P _c1 (mode) of the distribution C1 of the interparticle pore diameter S.

(Fluorine organic compound)
As a method for supporting a fluorine organic compound on magnetic inorganic particles (or an aggregate of magnetic inorganic particles), a first method obtained by reacting a fluorocarbon and a compound having an alkoxysilyl group on the surface of the magnetic inorganic particles; And a second method of coating the magnetic particles with the polymer containing s.

In the first method, a so-called fluorine-containing silane coupling agent is reacted with the surface of the magnetic inorganic particles. The alkoxysilyl group of the silane coupling agent reacts with and binds to the hydroxyl group on the surface of the magnetic inorganic particle, and the fluorocarbon can be supported on the particle surface. Examples of such a compound include KY-100 series manufactured by Shin-Etsu Chemical Co., Ltd. Examples of the surface treatment method using these include a dry method and a wet method. In the dry method, for example, magnetic inorganic particles are dispersed in a mixer such as a Henschel mixer, and applied to the surface by dripping or spraying a silane coupling agent diluted in a solvent while mixing. It can produce by advancing reaction in the range. In the wet method, the coupling agent is dissolved in a solvent in advance, and then the magnetic inorganic particles to be treated are added and stirred in water to react the surface hydroxyl groups with the alkoxysilyl groups. Thereafter, the magnetic inorganic particles are taken out from the solution, the solvent is removed with hot air or vacuum, and then the reaction is allowed to proceed in a temperature range of room temperature to 100 ° C.

The second method is obtained by applying a fluorocarbon-containing resin solution to the surface of the magnetic inorganic particles. For example, a copolymer or mixture in which a structure having a fluorocarbon and a structure to be heat-cured coexist is used. Examples of the fluorocarbon include PTFE, PFA, PEEP, PCTFE, ETFE, ECTFE, PVDF, and the like. Examples of the resin having a heat-curing structure include polyamide resin, polyimide resin, polyamideimide resin, acrylic resin, and epoxy resin. Examples of the surface treatment method using these include a dry method. In the dry method, similarly to the treatment with the silane coupling agent, the magnetic inorganic particles are dispersed in a mixer such as a Henschel mixer, and the resin solution containing the fluorocarbon is sprayed while mixing. Then, the filter aid which carry | supported fluorocarbon on the surface can be manufactured by heat-hardening with the hardening temperature of this resin.

Hereinafter, apparatuses and methods used in various embodiments will be described with reference to the accompanying drawings.

(How to use filter aid)
Since the filter aid of the embodiment described herein has a hydrophobic surface, it can adsorb a hydrophobic substance in water and separate and remove it with a magnet even if it is dispersed in water. However, the most effective performance of such filter aids is the reusable filtration that can repeat adsorption → filtration (solid-liquid separation) → desorption → adsorption in a process that uses membrane filtration. It is to be used as an auxiliary agent. There are two types of membrane filtration methods, a pre-coating method and a body feed method, as the method of use, but the apparatus used for each method is different in configuration, so each will be described below.

(Apparatus of the first embodiment)
First, the water treatment apparatus used in the first embodiment will be described with reference to FIG. The water treatment apparatus 1 of the present embodiment is used for a body feed method, and is effectively used particularly when the concentration of water-insoluble solids is high in water.

The water treatment apparatus 1 has a mixed raw water tank 2, a solid-liquid separation apparatus 3, a magnetic separation tank 4, a filter aid supply apparatus 5, and a raw water supply source and a drainage storage tank (not shown). Are connected to each other by a plurality of piping lines L1 to L8. Various pumps P1 to P7, valves V1 to V2, and measuring instruments and sensors (not shown) are attached to the piping lines L1 to L8. Detection signals are input from these measuring instruments and sensors to the input of a controller (not shown), and control signals are output from the output of the controller to the pumps P1 to P7 and valves V1 to V2, respectively, to control their operations. It has become so. As described above, the entire water treatment apparatus 1 is comprehensively controlled by a controller (not shown).

The mixed raw water tank 2 has a stirring screw 21 for stirring the water to be treated, and factory wastewater to be treated water is introduced through a line L1 from a raw water supply source (not shown). The mixed raw water tank 2 has a function of temporarily storing raw water and leveling the flow rate of the raw water, and a mixing function of adding magnetic powder to the raw water and mixing them. That is, in the apparatus 1 of the present embodiment, the filter aid is directly supplied from the filter aid supply device 5 into the mixed raw water tank 2 via the line L6.

The solid-liquid separator 3 has a built-in filter 33 that partitions the interior into an upper space 31 and a lower space 32. The upper space 31 of the solid-liquid separation device is connected to the mixed raw water tank 2 via a to-be-treated water supply line L2 having a pressure pump P1. Further, a separation water supply line (first treated water utilization line) L31 having a pump P5 and a separation material discharge line L4 are respectively connected to the side portions of the upper space 31.

On the other hand, the lower space 32 of the solid-liquid separator is connected to a treated water distribution line L3 having two three-way valves V1, V2. At the first three-way valve V1, the separation water supply line (first treated water utilization line) L31 is branched from the treated water distribution line L3. At the second three-way valve V2, two lines L33 and L34 are branched from the treated water distribution line L3. One branch line (second treated water utilization line) L33 has a pump P4 and is connected to a separation tank 4 described later. The other branch line (third treated water utilization line) L34 is connected to a treated water supply line L32 having a pump P5.

The magnetic separation tank 4 has an agitation screw 41 for agitating the washing discharge water received from the upper space 31 of the solid-liquid separation device through the peeled material discharge line L4, and magnetically solids and the filter aid. A magnet 42 is provided for separation. The magnet 42 is composed of a rod-like permanent magnet supported by a cylinder mechanism (not shown) so as to be movable up and down, and is housed in a cylindrical protective tube whose lower end is closed. When the magnet 42 is raised by the cylinder mechanism, the magnet 42 comes out of the protective tube, and the magnetic field applied to the water to be treated in the magnetic separation tank 4 disappears. On the other hand, when the magnet 42 is lowered by the cylinder mechanism, the magnet 42 is inserted into the protective tube, a magnetic field is applied to the water to be treated in the tank, and the magnetic filter aid is adsorbed on the outer periphery of the protective tube. It has become. In the embodiment described here, a rod-shaped permanent magnet is used as the magnetizing means, but a rod-shaped electromagnet may be used as the magnetizing means. Also, a magnetized metal mesh can be used as the magnetizing means.

In addition to the separated product discharge line L4, a second treated water use line L33 branched from the treated water distribution line L3 is connected to the upper part of the magnetic separation tank 4, and has passed through the filter 33 of the solid-liquid separator. A part of the treated water is supplied to the magnetic separation tank 4, and a part of the treated water is reused in the magnetic separation tank 4. On the other hand, a concentrated water discharge line L8 and a filter aid return line L5 are connected to the lower part of the magnetic separation tank 4, respectively. The concentrated water discharge line L8 has a pump P9 and is a pipe for discharging water-insoluble matter concentrated water from the magnetic separation tank 4 to a storage tank (not shown). The filter aid return line L5 has a pump P6 and is a pipe for returning the filter aid separated from the magnetic separation tank 4 to the filter aid supply device 5.

The filter aid supply device 5 is replenished with a fresh filter aid from a filter aid supply source (not shown), and the filter aid separated in the magnetic separation tank 4 is supplied to the filter aid return line L5. Will be sent back through. Moreover, the filter aid supply apparatus 5 supplies an appropriate amount of filter aid to the mixed raw water tank 2 through a filter aid supply line L6 having a pump P7.

(Method of the first embodiment)
Next, a body feed method will be described as a first water treatment method using the above apparatus with reference to FIGS. The water treatment method of the first embodiment is effective when the concentration of the filter aid in the water to be treated is high. In the embodiment described here, the water-insoluble solid matter to be removed includes not only inorganic compounds but also organic compounds.

In this embodiment, first, an appropriate amount of a filter aid and a dispersion medium are mixed to prepare a suspension. The dispersion medium used in this case is treated water existing in the mixed raw water tank 2. That is, in this embodiment, the filter aid is directly added to the raw water that is the treated water to adjust the suspension from the raw water (step K1). The concentration of the filter aid in the suspension is not particularly limited as long as a deposited layer can be formed on the filter 33 by the following operation, but is adjusted to, for example, about 10,000 to 200,000 mg / L.

Next, the suspension (treated water) is passed through the filter 33, the filter aid in the suspension is filtered, and a deposited layer in which the filter aid is deposited is formed on the filter 33 (step K2). . Note that the water to be treated is supplied to the filter 33 under pressure. At this time, the formation of the deposited layer and the filtration treatment of the water to be treated are performed in parallel. In the method of the present embodiment, the filter 33 is preferably horizontal.

Further, since the deposited layer is formed and held by the action of an external force, the above-described filtering is performed, for example, by placing the filter 33 so as to close the container opening of a predetermined container. The filter aid remains on the filter 33 arranged in this way so that it is deposited, arranged and laminated. In this case, the deposited layer is formed and held by the external force from the wall surface of the container and the downward external force (gravity) due to the weight of the filter aid positioned above.

Next, peeling water is sprayed from a nozzle (not shown) toward the deposition layer on the filter 33, the deposition layer is peeled off from the filter 33 by the spray force of water, and water is further sprayed onto the peeling material to separate the peeling material. Decompose (step K3). The filter aid in the exfoliated material adsorbs solid materials such as metal particles. The peeled material is decomposed in the upper space 31 of the solid-liquid separator 3. However, the peeled material may be decomposed in a container other than the solid-liquid separator 3. In the case where the peeled material is decomposed in another container, the peeled material is decomposed into discrete particles by jetting water from a nozzle. When the exfoliated material is decomposed to a particle state, it becomes a suspension state, which facilitates transportation to the magnetic separation tank 4 and facilitates magnetic separation of the magnetic filter aid. In addition, although water is used for peeling of the deposited layer, it is possible to clean using a surfactant or an organic solvent.

Next, the deposited layer separation is supplied from the upper space 31 to the magnetic separation tank 4 through the discharge line L4 (step K4). In the magnetic separation tank 4, the deposit layer peeled material is stirred by the stirring screw 41, the peeled material is further decomposed to the particle level, and the filter aid and the solid matter are dispersed. When this stirring is sufficiently performed, the filter aid and the solid matter are uniformly dispersed in the suspension, and the filter aid and the solid matter are easily separated.

Next, the magnet 42 is lowered by the cylinder mechanism, the magnet 42 is inserted into the protective tube of the magnetic separation tank 4, and a magnetic field is applied to the suspension being stirred. Since the magnetic filter aid is adsorbed on the protective tube by the magnetic force of the magnet 42, the filter aid is magnetically separated from the suspension. With the filter aid adsorbed and fixed to the magnet protective tube, the pump P7 is started and the solid concentrate is discharged from the magnetic separation tank 4 (step K5). The discharged solid concentrate is substantially free of filter aid and contains a large amount of water-insoluble solid.

¡After discharging the solid concentrated water, the magnet 42 is raised by the cylinder mechanism, and the magnet 42 is pulled out from the protective tube. Thereby, the magnetic field applied to the magnetic filter aid disappears, and the filter aid falls off from the magnet protective tube.

Next, the valve V2 is opened, the pump P4 is started, and treated water is introduced into the magnetic separation tank 4 from the solid-liquid separation device 3. The introduced water and the filter aid are mixed in the magnetic separation tank 4, and this mixture is stirred by the screw 41. Thereby, a suspension of the filter aid is produced. The suspension does not contain water-insoluble solids but substantially contains only a filter aid. After the pump P4 is stopped and the valve V2 is closed, the pump P5 is started and the suspension of the filter aid is sent from the magnetic separation tank 4 to the filter aid supply device 5 so that the separated filter aid is filtered. It is returned to the auxiliary agent supply device 5 (step K6).

After the filter aid is temporarily stored in the filter aid supply device 5, it is sent from the filter aid supply device 5 to the mixed raw water tank 2 by driving the pump P <b> 6 and is reused in the mixed raw water tank 2. (Step K6 → Step K1).

In the water treatment method of the present embodiment, the filter aid constituting the deposition layer is contained in the suspension adjusted using the water to be treated. The filter aid is always supplied together with the turbid liquid.

Therefore, even when the amount of water-insoluble solids in the water to be treated (suspension) is large, the supply of water-insoluble solids and the supply of filter aid are performed at the same time. Thus, the solid matter does not block the voids (interval S between the aggregated particles) of the filter aid. For this reason, a desired filtration rate can be maintained over a long time.

In this way, the filter aid is repeatedly used in the cycle of solids adsorption → solid-liquid separation by filtration membrane → desorption of solid matter from filter aid → magnetic separation → recovery → solids adsorption. be able to.

(Device of Second Embodiment)
Next, a water treatment device used in the second embodiment will be described with reference to FIG. In addition, description of the part which this embodiment overlaps with said embodiment is abbreviate | omitted.

The water treatment apparatus 1A of the present embodiment is an apparatus used for the precoat method, and is particularly effective when the concentration of water insoluble matter in the water to be treated is low. A water treatment apparatus 1A includes a coagulation precipitation tank 2A, a solid-liquid separation apparatus 3, a separation tank 4, a filter aid tank 5, a mixing tank 6, a coagulant addition apparatus 7, an alkali addition apparatus 8, and a raw water supply source and concentrated water (not shown). A storage tank is provided, and these devices and apparatuses are connected to each other by a plurality of piping lines L1 to L10. Various pumps P1 to P9, valves V1 to V3, measuring instruments and sensors (not shown) are attached to the piping lines L1 to L10. A detection signal is input from these measuring instruments and sensors to an input section of a controller (not shown), and control signals are output from the output section of the controller to pumps P1 to P9 and valves V1 to V3, respectively, and their operations are controlled. It has become so. In this way, the entire water treatment apparatus 1A is comprehensively controlled by a controller (not shown).

The coagulation / precipitation tank 2A has a stirring screw 21 for stirring the water to be treated, and factory wastewater to be treated water is introduced through a line L1 from a raw water supply source (not shown) to temporarily store the water to be treated. Is. A coagulant adding device 7 and an alkali agent adding device 8 are installed above the coagulation precipitation tank 2A. An appropriate amount of the flocculant is added from the flocculant addition device 7 through the line L9 to the water to be treated in the coagulation / precipitation tank 2A, thereby aggregating fine solid particles contained in the water to be treated. Further, an appropriate amount of an alkali agent is added to the water to be treated in the coagulation precipitation tank 2A from the alkali addition device 8 through the line L10, and metal ions or non-metal ions contained in the water to be treated are precipitated as compound salt particles. It is like that.

The solid-liquid separator 3 has a built-in filter 33 that partitions the interior into an upper space 31 and a lower space 32. The upper space 31 of the solid-liquid separator is connected to the coagulation / precipitation tank 2 via a to-be-treated water supply line L2 having a pressure pump P1. Further, a peeling water supply line L31 having a pump P5 and a peeled material discharge line L4 are connected to the side portions of the upper space 31, respectively.

On the other hand, the discharge space 32 of the solid-liquid separator is connected to a treated water distribution line L3 having three three-way valves V1, V2, and V3. At the first three-way valve V1, the above-described separation water supply line L31 branches from the treated water distribution line L3. A treated water line L32 having a pump P2 branches from the treated water distribution line L3 at the second three-way valve V2. At the third three-way valve V3, two lines L33 and L34 are branched from the treated water distribution line L3. One branch line L33 has a pump P4 and is connected to the magnetic separation tank 4. The other branch line L34 has a pump P5 and is connected to a mixing tank 6 described later.

The magnetic separation tank 4 has a stirring screw 41 for stirring the washed discharged water received from the upper space 31 of the solid-liquid separator through the peeled material discharge line L4, and the precipitated copper compound particles (copper hydroxide particles). A permanent magnet 42 for separating particles) and a filter aid is incorporated.

A branch line L33 that branches from the treated water distribution line L3 is connected to the upper part of the magnetic separation tank 4 in addition to the separated matter discharge line L4, and a part of the treated water that has passed through the filter 33 of the solid-liquid separator. Is supplied to the magnetic separation tank 4, and a part of the treated water is reused in the magnetic separation tank 4. On the other hand, a concentrated water discharge line L8 and a filter aid return line L5 are connected to the lower part of the magnetic separation tank 4, respectively. The concentrated water discharge line L8 has a pump P9 and is a pipe for discharging water-insoluble concentrated water from the magnetic separation tank 4 to a storage tank (not shown). The filter aid return line L5 has a pump P6 and is a pipe for returning the filter aid separated from the magnetic separation tank 4 to the filter aid tank 5.

The filter aid tank 5 is newly replenished with a filter aid supply source (not shown), and the filter aid separated in the magnetic separation tank 4 is returned through the above-described filter aid return line L5. It has come to be. Moreover, the filter aid tank 5 supplies an appropriate amount of filter aid to the mixing tank 6 through a filter aid supply line L6 having a pump P7.

The mixing tank 6 has a stirring screw 61 for stirring water, and a dispersion medium is added to the filter aid supplied from the filter aid tank 5 and the mixture is stirred and mixed. Liquid). It is preferable to use water as the dispersion medium. A branch line L34 branched from the treated water distribution line L3 is connected to the upper part of the mixing tank 6, and a part of the treated water that has passed through the filter 33 of the solid-liquid separator is supplied to the mixing tank 6. A part of the treated water is reused as a dispersion medium.

In addition, a suspension supply line L7 having a pump P8 communicates with an appropriate place of the mixing tank 6. The suspension supply line L7 is connected and merged at an appropriate position of the treated water supply line L2. The mixture (suspension) containing the filter aid from the suspension supply line L7 is added to the water to be treated flowing through the water supply line L2. The suspension supply line L7 is provided with a flow rate control valve (not shown) so that the flow rate of the suspension is adjusted by the controller.

(Water treatment method of the second embodiment)
Next, a water treatment method according to a second embodiment using the above apparatus will be described with reference to FIGS. 15 and 14.

The precoat method is particularly effective when the concentration of water-insoluble solids contained in the water to be treated is low. In the embodiment described here, the water-insoluble solid matter to be removed includes not only inorganic compounds but also organic compounds. Even if the water-insoluble solid is a hardly dehydrating particle such as a metal hydroxide, or a non-particle dehydrating component other than the particle, such as oil or fat, the filter aid of the specific structure of the present embodiment It can be easily separated and removed.

In the precoat method, first, the filter aid and the dispersion medium are mixed in the mixing tank 6 to prepare a suspension containing the filter aid (step S1). Although water is mainly used as the dispersion medium, other dispersion media such as an aqueous alcohol solution can be used in addition to water. The concentration of the filter aid in the suspension may be adjusted to about 10,000 to 200,000 mg / L, for example, as long as a precoat layer, that is, a deposited layer of filter aid, can be formed by the following operation.

Next, the suspension is passed through the filter 33 of the solid-liquid separator 3, the filter aid in the suspension is filtered, and a precoat layer of the filter aid is formed on the filter 33 (step S2). In addition, the water flow of the suspension to the filter 33 by the pressurization pump P1 is performed at a predetermined pressure. As the filter 33, a filter cloth, a filtration membrane, a metal mesh, a porous ceramic, or a porous polymer can be used. Among these, a filter cloth is preferable. For example, a cloth knitted with a double woven fabric, a twill woven fabric, a plain woven fabric, a satin woven fabric, or the like is used for the filter 33.

The filter surface of the filter 33 is preferably in a direction (that is, horizontal) orthogonal to the direction in which gravity acts. The filter aid of this embodiment is difficult to be held on the filter surface. For this reason, if the filter surface of the filter 33 is not horizontal, the filter aid slips on the filter surface, and a deposited layer having a uniform thickness may be difficult to form.

The filter 33 is attached so as to close the inlet of the solid-liquid separation device 3, and the suspension 33 is filtered by the filter 33 so that the pressure drop of the suspension in the solid-liquid separation device 3 is minimized. To. Specifically, by reducing the upper space 31 defined by the container wall of the solid-liquid separator 3 and the filtration membrane 33 and pushing the pressurized suspension into the small space 31 with a small volume, Separation of the filter aid and the liquid by the filter 33 is promoted. At this time, the liquid component of the suspension quickly permeates through the filter 33 and the solid component of the suspension (filter aid) is captured by the filter 33 due to the synergistic action of the pressure and gravity generated by driving the pressurizing pump P1. As a result, a precoat layer is formed on the filter 33. The thickness of the precoat layer varies depending on the concentration of the liquid to be treated, but is about 0.1 to 10 mm.

The water to be treated is introduced into the coagulation / deposition tank 2A from a raw water supply source (not shown) (step S3). Copper ions are contained in the factory effluent to be treated. A predetermined amount of sodium hydroxide (NaOH) is added to the water to be treated in the coagulation precipitation tank 2A from the alkali addition device 8 (step S4). The water to be treated in the coagulation precipitation tank 2A is stirred with a screw to dissolve sodium hydroxide, the water to be treated is made alkaline, and copper hydroxide fine particles are precipitated from the water to be treated (step S5).

Next, the water to be treated is pumped from the coagulation / precipitation tank 2A to the solid-liquid separation device 3 through the line L2 by driving the pump P1, and the water to be treated is filtered by the precoat layer on the filter 33, and hydroxylated from the water to be treated. Copper particles are adsorbed and captured (step S6). The water to be treated is passed through the precoat layer on the filter 33 mainly under pressure. At this time, the copper hydroxide particles are separated and removed from the water to be treated by adsorbing on the surface of the filter aid in the precoat layer. At this time, by setting the filter aid to a specific configuration as described later, copper hydroxide particles can be captured efficiently and a sufficient water flow rate can be obtained.

When filtration of the water to be treated by the precoat layer is completed, the valve V1 is switched, the pump P3 is started, and a part of the treated water enters the upper space 31 of the solid-liquid separator through the line L3 → L31 by driving the pump P3. Or return everything. The returned treated water is used as peeling water for peeling the precoat layer from the filter 33. Treated water (peeling water) is sprayed onto the precoat layer from the side of the upper space 31, the precoat layer is peeled off from the filter 33, and further treated water is sprayed on the peeled material to decompose the peeled material into pieces, and a filter aid and water Copper oxide particles are dispersed in water (step S7).

The separation / decomposition of the precoat layer may be performed in the solid-liquid separator 3 or in another container. When disassembling the precoat layer exfoliated material in another container, the precoat layer exfoliated material is disintegrated by water injection from a nozzle until it becomes particles. When the peeled material is in a suspension state in this way, it becomes easy to transfer it from another container to the magnetic separation tank 4. In addition, when the treatment water used as peeling water is insufficient, the industrial water or tap water may be replenished to the line L31 from another place. Although water is preferably used for peeling / decomposing the precoat layer, it is also possible to peel / decompose the precoat layer using a surfactant or an organic solvent.

Next, the precoat layer peeled material is supplied from the upper space 31 to the magnetic separation tank 4 through the discharge line L4 (step S8). In the magnetic separation tank 4, the peeled precoat layer is stirred by the stirring screw 41, the peeled material is further decomposed to the particle level, and the filter aid and the copper compound particles are dispersed. When this stirring is sufficiently performed, the filter aid and the copper compound particles are uniformly dispersed in the suspension, and the filter aid and the copper compound particles are easily separated.

Next, the magnet 42 is lowered by the cylinder mechanism, the magnet 42 is inserted into the protective tube of the magnetic separation tank 4, and a magnetic field is applied to the suspension being stirred. As a result, the magnetic filter aid is adsorbed on the magnet protective tube, and the filter aid is magnetically separated from the suspension. With the filter aid adsorbed and fixed to the magnet protective tube, the pump P9 is activated and the copper concentrate is discharged from the magnetic separation tank 4 (step S9). The copper concentrate discharged | emitted contains substantially no filter aid, and contains the copper compound particle | grains (a main component is copper hydroxide) in high concentration.

After discharging the copper concentrate, the magnet 42 is raised by the cylinder mechanism, the magnet 42 is withdrawn from the protective tube of the magnetic separation tank 4, the magnetic field applied to the magnetic filter aid is lost, and the filter aid is removed from the protective tube. Drop off the agent.

Next, the valve V3 is opened, the pump P4 is started, and the treated water is introduced from the solid-liquid separator 3 into the magnetic separation tank 4. The introduced water and the filter aid are mixed in the magnetic separation tank 4, and this mixture is stirred by the screw 41. Thereby, a suspension of the filter aid is produced. The suspension does not contain water-insoluble solids but substantially contains only a filter aid. After the pump P4 is stopped and the valve V3 is closed, the pump P6 is started and the suspension of the filter aid is sent from the magnetic separation tank 4 to the filter aid tank 5 so that the separated filter aid is filtered. It is returned to the agent tank 5 (step S10).

After the filter aid is temporarily stored in the filter aid tank 5, it is sent from the filter aid tank 5 to the mixing tank 6 by driving the pump P7 and reused in the mixing tank 6 (step S10 → Step S1).

Thereafter, the separated and recovered filter aid is supplied from the filter aid supply device 5 to the upper space 31 of the solid-liquid separation device 3 via the line L6, and the recovered filter aid is reused to form the precoat layer. In this way, the filter aid can be used repeatedly in a cycle process consisting of precoat layer formation → filtration / adsorption → desorption → magnetic separation → precoat layer formation.

The filter aid according to the embodiment described herein efficiently adsorbs water-insoluble solids in water, easily desorbs the adsorbed solids, and is easily magnetically separated from the desorbed solids. Suitable for reuse.

Examples and comparative examples will be described below.

(Filter aid A)
KY-108 from Shin-Etsu Chemical Co., Ltd., which has tetrafluoroethylene perfluoroalkyl vinyl ether copolymer (PFA) and an alkoxy group as a fluorine organic compound while mixing manganese magnesium ferrite powder with an average particle size of 15 μm with a Henschel mixer. ) Was sprayed to 1% with respect to the weight of ferrite.

The ferrite particles were heated in a constant temperature bath at 100 ° C. for 2 hours and then passed through a 100 mesh sieve to obtain a filter aid A. When the circularity of the magnetic primary particles constituting the filter aid A was measured, the circularity value was 0.90. Furthermore, when the mutual space | interval S of the particle | grains of the filter aid A was measured, distribution A of the mutual space | interval S shown in FIG. 8 was obtained. In the distribution A, interval value (= 4.1 .mu.m) than larger interval value in the distribution width D _L as compared to the mode P _a spacing (= 4.1 .mu.m) smaller intervals than in the mode P _a The distribution width D _S of was wider (D _L <D _S ).

(Filter aid B)
A filter aid B was obtained in the same manner as the filter aid A except that manganese magnesium ferrite particles having an average particle size of 5 μm were used. When the circularity of the magnetic primary particles constituting the filter aid B was measured, the circularity value was 0.91. The most frequent interval value was 2.3 μm. In the filter aid B, as in the case of the filter aid A, the distribution width D _S of the interval smaller than the most frequent interval value is wider than the distribution width D _L of the interval larger than the most frequent interval value. (D _L <D _S ).

(Filter aid C)
Porous manganese magnesium ferrite particles with an average particle size of 35 μm are put into a fluidized bed, and a resin of a copolymer of PFA resin and polyamideimide (made of maleic anhydride and diaminodiphenylmethane) is added until the resin content reaches 5%. did. The magnetic primary particles were taken out and cured by heating at 200 ° C. for 2 hours to obtain a filter aid C.

When the circularity of the magnetic primary particles constituting the filter aid C was measured, the circularity value was 1.08. Further, when the interparticle pore diameter S and the open pore diameters d ₃ and d ₄ were measured by mercury porosimetry, distributions C1 and C2 shown in FIG. 10 were obtained. In the distribution C1, the interval width D _L is larger than the interval value at the mode value P _c1 (= 10 μm) of the interparticle pore diameter S, and is smaller than the interval value (= 10 μm) at the mode value P _c1. The distribution width D _S of the gap was wider (D _L <D _S ). Further, in the distribution C2, pore diameter values (= 1.5 μm) at the mode value P _c2 were obtained for the diameters d ₃ and d ₄ of the open pores.

(Filter aid D)
A filter aid D was obtained in the same manner as the filter aid C except that porous manganese magnesium ferrite particles having an average particle size of 25 μm were used. When the circularity of the magnetic primary particles constituting the filter aid D was measured, the circularity value was 1.09. In addition, the mutual spacing value of the most frequent particles was 8 μm. Further, the most frequent pore diameter value of 1.5 μm was obtained for the diameters d ₃ and d ₄ of the open pores.

(Filter aid E)
Magnetic particles E that do not carry a fluorocarbon on the same manganese magnesium ferrite particles as the filter aid A were prepared. This magnetic particle E was used in a comparative example as described later.

Example 1
A factory effluent containing 200 mg / L ceramic with an average particle size of 2 μm and a sticky adhesive was prepared. In addition, a solid-liquid separator in which a filter cloth having an air permeability of 20 cc / min was set on a horizontal filtration surface was prepared. After uniformly laminating 1 kg of filter aid A per square meter on the filter surface of this solid-liquid separator, the factory wastewater was passed through a filter (filter cloth) under pressure. 99.5% or more was removed, and the ceramic concentration was 1 mg / L or less. The average flux representing the water flow rate through the filter was 5 m / h.

The filter aid after use was recovered and put into a stainless steel container together with washing water (tap water). While mixing this container with a stirrer, a neodymium magnet was brought close to the outside of the container to separate the magnet. As a result, only ceramic was dispersed in the washing water, and the filter aid A could be washed. When the industrial wastewater was treated using the filter aid A after the washing again, 99.5% or more of the ceramic particles in the water were removed, and the ceramic concentration was 1 mg / L or less. The flux representing the water flow rate to the filter was an average of 4.7 m / h. Even if the same operation is repeated 10 times, and the filter aid A is used even when regenerated 10 times, the removal efficiency is maintained at a ceramic concentration of 1 mg / L or less, and the water flow rate is 4.5 m / h or more. Maintained.

(Comparative Example 1)
When the filter aid E not supporting the fluorocarbon was passed in the same manner as in Example 1, 99.5% or more of the ceramic particles in the water were removed as in Example 1, and the ceramic concentration was 1 mg / L or less. The flux representing the water flow rate to the filter was an average of 4.6 m / h. However, when the ceramic particles and the filter aid E were separated in the same manner with washing water, most of the ceramic particles could not be recovered. When this filter aid E was used to pass through the filter again, 99.5% or more of the ceramic particles in the water were removed and the ceramic concentration was 1 mg / L or less. The auxiliary E could not be reused.

(Example 2)
A test was conducted in the same manner except that filter aid B was used instead of filter aid A. As in Example 1, 99.5% or more of the ceramic particles in the water were removed, and the ceramic concentration was 1 mg / L or less. Met. The flux representing the water flow rate through the filter was an average of 4.2 m / h. Further, the filter aid B can be washed without any problem. When the filter aid B is used even when regenerated 10 times, the removal efficiency with a ceramic concentration of 1 mg / L or less can be obtained. Water flow rate of m / h or more was maintained.

(Example 3)
A similar test was conducted except that filter aid C was used instead of filter aid A. As in Example 1, 98.5% of the ceramic particles in the water were removed, and the ceramic concentration was 3 mg / L. . The flux representing the water flow rate to the filter was an average of 8.0 m / h. In addition, the filter aid can be washed without any problem, and even when the filter is regenerated 10 times, the use of the filter aid C provides a removal efficiency with a ceramic concentration of 1 mg / L or less, and a flux of 7.0 m / L. The water flow rate over h was maintained.

(Example 4)
A test was conducted in the same manner except that filter aid D was used instead of filter aid A. As in Example 1, 99.0% of the ceramic particles in water were removed, and the ceramic concentration was 2 mg / L. . The average flux representing the water flow rate through the filter was 7.1 m / h. In addition, the filter aid can be washed without any problem, and even when regenerated 10 times, the filter aid D can be used to obtain a removal efficiency with a ceramic concentration of 1 mg / L or less and a flux of 6.2 m / L. The water flow rate over h was maintained.

Claims

Water treatment filter aid that adsorbs foreign matter contained in the water to be treated, is separated from the treated water together with the adsorbed foreign matter by membrane filtration, is magnetically separated from foreign matter in the membrane-filtered separation, and is used repeatedly. An agent,
The filter aid comprises an aggregate in which a plurality of magnetic primary particles are aggregated,
The magnetic primary particles are:
Magnetic inorganic particles having an average particle size of 5 μm to 40 μm,
Covering a part or all of the surface of the magnetic inorganic particles, and having a coating layer containing a fluorine organic compound supported on the magnetic inorganic particles, and
The circularity value of the two-dimensional projection image projected on the plane in the microscope field is in the range of 0.40 to less than 1.00 (excluding 1.00).
The filter aid for water treatment characterized by the above-mentioned.
The filter aid for water treatment according to claim 1, wherein the magnetic inorganic particles are made of a ferrite compound.
In the distribution of the mutual spacing S of the magnetic primary particles, the mode P a, the mode is better distribution width D S of the smaller interval than the interval at P c1 P a, the width of the distribution of intervals greater than the interval at P c1 D for water treatment filter aid according to claim 1, wherein a wider than L.
The magnetic inorganic particles have an apparent specific gravity of greater than 1, have a large number of open pores opened on the surface, and the diameter of the open pores is smaller than the mutual spacing S of the magnetic primary particles. The filter aid for water treatment according to claim 1.
The filter aid for water treatment according to claim 1, wherein the fluorine organic compound is obtained by reacting a compound having a fluorocarbon and an alkoxy group with the surface of the magnetic inorganic particles.
2. The filter aid for water treatment according to claim 1, wherein the foreign matter is a water-insoluble solid contained in the water to be treated.
Foreign matter contained in the water to be treated is adsorbed to the filter aid, and the filter aid is separated from the treated water together with the adsorbed foreign matter by membrane filtration, and the filter aid is magnetically separated from the foreign matter in the membrane-filtered separation. In the water treatment method in which the separated filter aid is repeatedly used,
(A) a magnetic inorganic particle having an average particle diameter of 5 μm or more and 40 μm or less, and a coating layer that covers a part or all of the surface of the magnetic inorganic particle and contains a fluorine organic compound supported on the magnetic inorganic particle. In addition, magnetic primary particles having a circularity value in the range of 0.40 or more and less than 1.00 (excluding 1.00) of a two-dimensional projection image projected onto a plane within a microscope field of view are prepared, and a plurality of filtration aids are used. Preparing an aggregate in which the magnetic primary particles are aggregated;
(B) Mixing the water to be treated containing water-insoluble solids and the filter aid to produce a suspension in which the filter aid is dispersed in the water to be treated;
(C) The suspension is filtered through a filtration membrane, a deposition layer containing the filter aid and the water-insoluble solid is formed on the filtration membrane, and the water is added to the filtration aid in the deposition layer. Adsorb and capture insoluble solids, thereby separating the water-insoluble solids from the water to be treated,
(D) providing a mixture of exfoliated material of the deposited layer and the exfoliated water in which exfoliated water is poured into the accumulated layer to exfoliate the accumulated layer from the filtration membrane, thereby capturing the water-insoluble solid matter. ,
(E) magnetically separating the filter aid from the mixture;
(F) Reusing the separated filter aid in the step (B),
A water treatment method characterized by that.
In the distribution of the mutual spacing S of the magnetic primary particles, the mode (mode) P a, the mode is better distribution width D S of the smaller interval than the interval at P c1 P a, larger spacing than the spacing at the P c1 The method according to claim 7, wherein the distribution width is wider than the distribution width D L of .
Foreign matter contained in the water to be treated is adsorbed to the filter aid, and the filter aid is separated from the treated water together with the adsorbed foreign matter by membrane filtration, and the filter aid is magnetically separated from the foreign matter in the membrane-filtered separation. In the water treatment method in which the separated filter aid is repeatedly used,
(A) a magnetic inorganic particle having an average particle size of 5 μm or more and 40 μm or less, and a coating layer that covers a part or all of the surface of the magnetic inorganic particle and contains a fluorine organic compound supported on the magnetic inorganic particle. In addition, magnetic primary particles having a circularity value in the range of 0.40 or more and less than 1.00 (excluding 1.00) of a two-dimensional projection image projected onto a plane within a microscope field of view are prepared, and a plurality of filtration aids are used. Preparing an aggregate in which the magnetic primary particles are aggregated;
(B) Mixing a dispersion medium with the filter aid, producing a suspension in which the filter aid is dispersed in the dispersion medium,
(C) The suspension is filtered through a filtration membrane, a precoat layer containing the filter aid is formed on the filtration membrane, and then water to be treated containing a water-insoluble solid material is added to the precoat layer and the filtration. Passing through a membrane, the pre-coat layer filter aid adsorbs and captures the water-insoluble solid material, thereby separating the water-insoluble solid material from the water to be treated,
(D) Pour release water into the precoat layer to release the precoat layer from the filtration membrane, thereby providing a mixture of the precoat layer exfoliation and the release water capturing the water-insoluble solid material. ,
(E) magnetically separating the filter aid from the mixture;
(F) Reusing the separated filter aid in the step (b).
A water treatment method characterized by the above.
In the distribution of the mutual spacing S of the magnetic primary particles, the mode (mode) P a, the mode is better distribution width D S of the smaller interval than the interval at P c1 P a, larger spacing than the spacing at the P c1 The method according to claim 9, wherein the distribution width is wider than the distribution width D L of .