JP5389196B2 - Water treatment method and water treatment apparatus - Google Patents

Description

  Embodiment described here is related with the water treatment method and water treatment apparatus for purifying factory waste water, domestic waste water, etc. using a filter aid.

  Recently, the effective use of water resources has been required due to industrial development and population growth. In order to effectively use water resources, it is important to purify and reuse various wastewaters such as industrial wastewater and domestic wastewater. In order to purify the waste water, it is necessary to separate and remove water insoluble matters and impurities contained in the water. Examples of methods for purifying wastewater include membrane separation methods, centrifugal separation methods, activated carbon adsorption methods, ozone treatment methods, and suspended matter precipitation removal methods by adding flocculants. By using these water treatment methods, chemical substances having a great influence on the environment such as phosphorus and nitrogen contained in the wastewater can be removed, and oils and clays dispersed in water can be removed.

  Of the various water treatment methods described above, the membrane separation method is one of the most commonly employed methods for removing insoluble substances in water. The membrane separation method is often used in the form of using a filter aid such as a so-called precoat method or body feed method from the viewpoint of protecting the filtration membrane or from the viewpoint of increasing the flow rate of water containing a hardly dehydrated substance. It is used.

JP 2006-218381 A

  In general, when a filter aid such as silica sand is used, the used filter aid is discarded without being reused. Even when the filter aid is to be reused, many process steps are required for the recovery and washing of the filter aid, which is not practical.

  The embodiments described herein are made to solve the above-described problems, and are a water treatment method and a water treatment capable of efficiently removing fine solids in water and easily reusing a filter aid. An object is to provide an apparatus.

The water treatment method described here is: (a) a filter aid in which a part or all of magnetic single particles or aggregates thereof are covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. (B) A dispersion medium is mixed with the filter aid to prepare a suspension in which the filter aid is dispersed in the dispersion medium, and (c) the suspension is filtered through a filter membrane. And forming a precoat layer containing the filter aid on the filter membrane, and then allowing water to be treated containing a solid content to pass through the precoat layer and the filter membrane, and adding the solid to the filter aid of the precoat layer. The solid component is separated from the water to be treated by this, and (d) peeling water is poured into the precoat layer to separate the precoat layer from the filtration membrane, thereby capturing the solid component. A mixture of the precoat layer release material and the release water was provided. (E) magnetically separating the filter aid from the mixture and (f) reusing the separated filter aid in the preparation of the suspension in step (b), or (A) 22 A filter aid in which a part of or all of the magnetic single particles or aggregates thereof is covered with a coating material having a critical surface tension γ _c of × 10 ⁻³ N / m or less is prepared. Treated water and the filter aid are mixed, a suspension in which the filter aid is dispersed in the treated water is prepared, (C) the suspension is filtered through a filter membrane, and the filter membrane is placed on the filter membrane. Forming a deposited layer containing the filter aid and the solid content, causing the filter aid to adsorb and trap the solid content in the deposited layer, thereby separating the solid content from the water to be treated; ) Pour stripping water into the deposited layer to strip the deposited layer from the filter, thereby making the water insoluble Providing a mixture of the exfoliation product of the deposited layer capturing the metal compound particles and the exfoliation water, (E) magnetically separating the filter aid from the mixture, and (F) separating the filter aid. In the step (B), it is reused for preparing a suspension.

The characteristic diagram which shows an example of the Zisman plot used when calculating | requiring the critical surface tension (gamma) _c between solid-liquid. The block diagram which shows the water treatment apparatus which concerns on 1st Embodiment. Process drawing which shows the water treatment method (precoat method) of 1st Embodiment using the apparatus of FIG. (A) is a cross-sectional schematic diagram which shows the aggregate which the magnetic particle aggregated, (b) is a cross-sectional schematic diagram which shows the magnetic particle coat | covered with the hydrophobic coating material. The block diagram which shows the water treatment apparatus which concerns on 2nd Embodiment. Process drawing which shows the water treatment method (body feed method) of 2nd Embodiment using the apparatus of FIG.

  Various embodiments are described below.

(1) The water treatment method according to the embodiment described herein includes: (a) a part of a magnetic single particle or an aggregate thereof by a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less; A filter aid that is entirely covered is prepared, (b) a dispersion medium is mixed with the filter aid, and a suspension in which the filter aid is dispersed in the dispersion medium is prepared, and (c) a filter membrane The suspension is filtered, a precoat layer containing the filter aid is formed on the filtration membrane, and then water to be treated containing solids is passed through the precoat layer and the filtration membrane, and the precoat layer The filter aid adsorbs and captures the solid content, thereby separating the solid content from the water to be treated, and (d) peeling water is poured into the precoat layer to peel the precoat layer from the filter membrane, As a result, the exfoliation of the precoat layer that has captured the solid content and the exfoliation Providing a mixture with water separation, (e) magnetically separating the filter aid from the mixture, and (f) reusing the separated filter aid in the step (b) for making a suspension.

The water treatment method of the above embodiment is a method corresponding to the precoat method. A filter aid having the specific critical surface tension γ _c 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 solid content (water-insoluble substance) 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 material is further sprayed on the peeled material, and the peeled material is decomposed into pieces. To do. Next, the separated product separated into pieces is sent from the solid-liquid separation device to the magnetic separation tank together with the separation water, and the separated product is stirred in the magnetic separation tank until it becomes a particle state. Disperse. Next, the filter aid dispersed in water is adsorbed by a magnetic adsorption means such as an electromagnet, and the treated water containing solid content is discharged from the magnetic separation tank while the filter aid is adsorbed by the magnetic adsorption means. Next, the magnetic adsorption of the filter aid is released, the filter aid is dropped from the magnetic adsorption means, and treated water or tap water is sprayed onto the magnetic adsorption means to wash away the filter aid adhering to the magnetic adsorption means. ,to recover. The collected filter aid 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.

The filter aid is obtained by coating a part or all of magnetic simple particles or aggregates thereof with a coating material having a specific critical surface tension γ _c . The shape of the magnetic single particle can take various shapes such as a spherical shape, a polyhedron, and an indeterminate shape, but is not particularly limited. The particle size and shape of the magnetic carrier desirable for use may be appropriately selected in view of production costs and the like, and a spherical structure or a polyhedral structure with rounded corners is particularly preferable. By incorporating these magnetic materials, the specific gravity of the filter aid is relatively high, so it is possible to use sedimentation by gravity and separation by centrifugal force using a cyclone in combination with magnetic separation. Filter aid can be quickly separated from water.

The surface of the filter aid is partially or entirely covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. Here, the critical surface tension γ _c means that a liquid with various surface tensions is dropped onto the solid and the surface tension of the liquid whose contact angle is zero is obtained by extrapolation. Can be obtained by the Jisman method using the value of as the critical surface tension. Moreover, when measurement is difficult, it is good also as a literature value with a close composition. For example, values described in a plastic data book (Asahi Kasei Amidus Co., Ltd., “Plastics” editorial department, P. 35, (1999)) are used.

By using such a filter aid covered with a coating material having a critical surface tension γ _c , the filter aid and the solid matter in water can be easily separated by simple operation. That is, since the critical surface tension γ _c is low, solids in water can be solid-liquid separated using stirring or ultrasonic waves in water, and only the filter aid can be adsorbed on the magnet and recovered.

  The magnetic particles may be aggregates (secondary particles) obtained by aggregating single magnetic single particles (primary particles). In the aggregate, if there is a gap between the aggregated primary particles, the filtrate passes through this gap, so that the amount of treated water can be increased. The average particle diameter of the primary particles is preferably in the range of 0.5 to 5 μm. If the average particle size of the magnetic single particles as the primary particles is larger than 5 μm, the distance between the particles becomes too large, and there is a risk of causing a through-pass that allows fine precipitates in water to be described later to pass through. is there. On the other hand, when the primary particle diameter is less than 0.5 μm, the particles are densely aggregated and there is a possibility that an effective water flow rate cannot be obtained.

As a method of making a filter aid composed of aggregates, a method of applying a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less after first forming aggregates with a granulator, etc. There is a method of granulating primary particles using a material having a surface tension γ _c of 22 × 10 ⁻³ N / m or less as a binder. In the former, primary particles and organic binders or inorganic binders are kneaded with a spray dryer or Henschel mixer, etc., and a granulated product is produced, and then a material with a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less is used. After applying and reacting at 100 ° C. to 200 ° C., or by sintering the magnetic material in a porous form by spray drying or the like to produce a porous magnetic body, the density is 22 × 10 ⁻³ N / m or less The method of apply | coating material is mentioned. The latter is granulated directly with a Henschel mixer or spray dryer using a binder with a critical surface tension of 22 × 10 ⁻³ N / m or less.

  By incorporating these magnetic substances into the filter aid, the specific gravity of the filter aid is relatively high, so that sedimentation by gravity and separation by centrifugal force using a cyclone can be used in combination with magnetic separation. Therefore, the filter aid can be quickly separated from the water.

The procedure and method for determining the critical surface tension γ _c will be described with reference to FIG.

The critical surface tension γ _c can be determined using the Zisman method. In the Jisman method, various liquids having a known surface tension γ _L are brought into contact with the surface of a solid that is difficult to wet with water, and the contact angle θ is measured. Each value of cos θ is obtained from the measured contact angle θ, the obtained cos θ value is taken on the vertical axis (Y axis), and the corresponding surface tension γ _L of the liquid is taken on the horizontal axis (X axis) on the XY coordinates. Plot the results one after the other. As a result, a figure with a large number of plots is completed. The tendency of the plot group in the created figure is obtained by using a calculation method such as the least square method, and a straight line Z having the obtained inclination is drawn in the figure. This straight line Z is called a Zisman plot. Next, the surface tension when the value of cos θ is equal to 1 on the created straight line Z is obtained. That is, the X-axis intercept of the straight line Z when cos θ = 1 is obtained. The value (surface tension value) of the X-axis intercept of the obtained straight line Z is particularly called critical surface tension γ _c . The solid (filter aid) is easily separated from water because it is not wetted by a liquid having a surface tension γ _L greater than the critical surface tension γ _c .

  In the water treatment method of the embodiment described here, since the filter aid is excellent in separability and durability, the filter aid can be repeatedly used in a cycle of dispersion → adsorption → separation → recovery → dispersion. For this reason, there exists an advantage that an operating cost and a maintenance cost can be restrained low. As will be described later, a silicone resin or a fluororesin can be suitably used as the filter aid coating material. Moreover, various ferrite compounds can be suitably used as the magnetic simple particles of the filter aid.

  In addition, since a magnetic substance is used for the core part of the filter aid, it is possible to quickly and reliably separate the filter aid and the solid matter (water-insoluble substance such as SS) captured by magnetic adsorption means such as an electromagnet. it can. Thus, according to the said embodiment, the isolate | separated filter aid can be collect | recovered efficiently and smoothly, and the collect | recovered filter aid can be reused repeatedly.

(2) The water treatment method according to the embodiment described herein includes (A) a part of magnetic single particles or an aggregate thereof by a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. A filter aid that is entirely covered is prepared, and (B) the water to be treated containing solids and the filter aid are mixed to prepare a suspension in which the filter aid is dispersed in the water to be treated. (C) filtering the suspension with a filtration membrane, forming a deposition layer containing the filter aid and the solid content on the filtration membrane, and adding the solid content to the filter aid in the deposition layer. Adsorbed and captured, thereby separating the solid content from the water to be treated, and (D) peeling water is poured into the deposited layer to separate the deposited layer from the filtration membrane, thereby capturing the solid content. Providing a mixture of the exfoliation product of the deposited layer and the exfoliation water, and (E) removing the filter aid from the mixture Magnetically separated and (F) the separated filter aid is reused for the preparation of the suspension in the step (B).

The water treatment method of the above embodiment is a method corresponding to the body feed method. The filter aid having the specific critical surface tension γ _c is dispersed in the water to be treated, the water-insoluble solid content is adsorbed on the filter aid, and the water to be treated in this filter aid / solid content adsorption state is removed. Water is passed through the filter membrane, and a deposited layer composed of a filter aid / solid content 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, and further the peeling water is sprayed on the separation product, and the separation product is decomposed into pieces. To do. Next, the separated exfoliated material is sent from the solid-liquid separation device to the separation tank together with the exfoliated water, and the exfoliated material is agitated in the separation tank until it becomes a particle state, and the filter aid and the metal compound particles are uniformly dispersed in water. Let Next, the filter aid dispersed in water is magnetically adsorbed by a magnetic adsorption means (electromagnet, permanent magnet, etc.), and while the filter aid is adsorbed by the magnetic adsorption means, the treated water containing the solid content is magnetically separated. To the collection and storage tank. Next, the magnetic adsorption of the filter aid is released, the filter aid is dropped from the electromagnet, and treated water or tap water is sprayed on the electromagnet to wash and collect the filter aid adhered to the electromagnet. The recovered filter aid 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, since the filter aid is excellent in separability and durability, the filter aid can be used repeatedly. In particular, since solids (filter aids) are not wetted by liquids with a surface tension γ _L greater than the critical surface tension γ _c, filter aids are easily separated from water containing solids (water-insoluble substances such as SS). The For this reason, the separated filter aid can be collected efficiently and smoothly, and the collected filter aid can be reused repeatedly. For this reason, there exists an advantage that an operating cost and a maintenance cost can be restrained low.

  (3) In any of the above methods (1) or (2), it is preferable that the filtration membrane has a filtration surface orthogonal to the direction in which gravity acts.

Since the above-mentioned filter aid has a low critical surface tension γ _c , it is difficult to hold on the filter surface. For this reason, if the surface is not perpendicular to the direction of gravity (that is, a horizontal surface), the filter aid slips on the filter surface, and it may be difficult to laminate the filter to a uniform thickness. If the surface is perpendicular to the direction of gravity, you don't have to worry about this.

  In addition, when the filtration surface is orthogonal to the direction in which gravity acts, gravity acts on the suspension and water to be treated to the maximum, and the filtration action through which water molecules permeate the membrane is promoted. In this case, it is preferable to pressurize the suspension and / or the water to be treated to a pressure higher than the atmospheric pressure and pass the water through the filtration membrane. When the suspension or water to be treated is pressurized, the water passing speed through the membrane increases, and the filtration efficiency is further improved.

  Various kinds of filter membranes such as woven fabric, nonwoven fabric, paper, wire mesh (mesh), resin mesh (mesh), porous polymer membrane, and porous ceramic membrane can be used. Most preferred. As the woven fabric (filter fabric), fabrics such as double weave, twill weave, plain weave and satin weave are used. The material of the filter cloth may be any of synthetic fibers such as polypropylene, nylon and polyester, or natural fibers such as cotton and hemp.

  It is desirable that the average pore size of the filtration membrane be a size that does not allow the filtration aid to pass through. In order to ensure a predetermined level of water flow rate, the average pore size of the filter membrane can be further expanded to about 2 to 3 times the average particle size of the filter aid. This is because the silicone resin or fluororesin covering the surface of the filter aid is strong in hydrophobicity, so that it easily bridges on the surface of the filter membrane and can be sufficiently laminated even with a pore size larger than the average particle size.

  (4) In any one of the above methods (1) to (3), the average particle diameter of the filter aid is preferably in the range of 1 to 50 μm.

  When a filter aid having an average particle size in the range of 1 to 50 μm is used, fine particles in water can be adsorbed and captured. This is because if the average particle size is less than 1 μm, an effective amount of treated water may not be obtained, and if it exceeds 50 μm, particles to be trapped may be missed. More preferably, the average particle size is in the range of 2 to 35 μm. This is because when the average particle size is 2 μm or more, a more effective amount of treated water can be obtained, and when the average particle size is 35 μm or less, particles to be captured can be adsorbed and captured more finely.

  Here, the average particle diameter of the filter aid is obtained by calculation using a plurality of actual measurement values measured by a laser diffraction method. Specifically, the particle size of the filter aid can be measured using a SALD-DS21 measuring device (product name) manufactured by Shimadzu Corporation. In addition, the average particle diameter of a filter aid is a volume average particle diameter (Mean Volume Diameter). The volume average particle size is a value obtained by calculating the average particle size based on the volume of the particles.

  (5) In any one of the above methods (1) to (4), it is preferable that the covering material contains either a silicone resin or a fluororesin.

Silicone resin or fluororesin can be used as a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. Silicone resin is a polymer compound made of organopolysiloxane, and there are two types, one-pack type and two-pack type. Examples include the KE series and KR series, which are products of Shin-Etsu Chemical Co., Ltd. Fluorine resin is a general term for polymers containing fluorine in the resin. For example, polytetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer Polymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), chlorotrifluoroethylene-ethylene copolymer (ECTFE), polychlorotrifluoroethylene (PCTFE), polyvinyl fluoride (PVF) and a complex thereof. For example, the critical surface tension γ _{c of} PTFE is about 18 × 10 ⁻³ N / m. If necessary, a resin obtained by copolymerizing these resins with an epoxy resin, polyimide, polyamide or the like is used to improve the adhesion with the magnetic particles. Even when these resins are copolymerized, since the fluororesin is localized on the resin surface, the critical surface tension of the fluororesin may be used for calculation. A filter aid can be prepared by applying a solution of these resins on the surface of magnetic single particles (primary particles) or aggregates (secondary particles) and curing (solidifying) the resin.

  (6) In any one of the above methods (1) to (5), it is preferable that the magnetic single particle is made of a ferrite compound.

Ferromagnetic materials can be generally used as magnetic materials, 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 and the like 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. 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 suitable for use in water treatment. Yes.

(7) In the water treatment apparatus described here, (a) a part or all of magnetic single particles or aggregates thereof are covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. A filter aid supply device 5 for supplying the filter aid, (b) a raw water tank 2 for temporarily storing raw water containing solids, and (c) a filter aid supplied from the filter aid supply device. A mixing tank 6 for preparing a suspension in which the dispersion aid is dispersed in the dispersion medium, and (d) a filtration membrane that partitions the interior into an upper space and a lower space, A solid-liquid separation device 3 in which an upper space communicates with the filter aid supply device and the mixing tank; and (e) a suspension is introduced from the mixing tank into the upper space of the solid-liquid separation device, The suspension is filtered with a filter, and a precoat layer made of the filter aid is formed on the filter membrane. A suspension supply line L7 configured to: (f) introducing raw water from the raw water tank into the upper space of the solid-liquid separator, passing the raw water through the precoat layer and the filtration membrane; The solid content is captured by the filter aid of the precoat layer and the raw water supply line L2 configured to provide the filtrate to the lower space, and (g) a precoat layer that captures the solid content from the filtration membrane. A stripping water supply line L31 configured to supply stripping water for stripping to the upper space of the solid-liquid separator so that the stripping water strips the precoat layer from the filtration membrane; (h) The peeled material of the precoat layer discharged together with the peeling water is supplied from the upper space of the solid-liquid separator, and the solid content contained in the peeled material and the filter aid are magnetically separated. And (i) a filter aid returning line L5 configured to return the separated filter aid from the magnetic separation tank to the filter aid supply device. And

  The water treatment apparatus of the said embodiment is an apparatus used for the precoat method. In the mixing tank, filter aid is dispersed in a dispersion medium to prepare a suspension, and this suspension is supplied to the filter membrane of the solid-liquid separator, and the filter aid is deposited on the filter membrane. The precoat layer is formed. Next, the raw water is passed from the raw water tank through the precoat layer, and the solid content (water insoluble substance) 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 material is further sprayed on the peeled material, and the peeled material is decomposed into pieces. To do. Next, the separated product separated into pieces is sent from the solid-liquid separation device to the magnetic separation tank together with the separation water, and the separated product is stirred in the magnetic separation tank until it becomes a particle state. Disperse. Next, the filter aid dispersed in water is adsorbed by a magnetic adsorption means such as an electromagnet, and the treated water containing solid content is discharged from the magnetic separation tank while the filter aid is adsorbed by the magnetic adsorption means. Next, the magnetic adsorption of the filter aid is released, the filter aid is dropped from the magnetic adsorption means, and treated water or tap water is sprayed onto the magnetic adsorption means to wash away the filter aid adhering to the magnetic adsorption means. ,to recover. The collected filter aid is sent from the magnetic separation tank 4 to the filter aid supply device 5 and reused in the filter aid supply device 5 and the mixing tank 6 for producing a suspension.

In the above embodiment, by using a filter aid covered with a coating material having a specific critical surface tension γ _c , it is possible to easily separate the filter aid and the solid matter in water by a simple operation. Can do. That is, since the critical surface tension γ _c of the filter aid is low, solids in water can be separated into solid and liquid using stirring or ultrasonic waves in water, and only the filter aid can be adsorbed on the magnet and recovered. . Since the collected filter aid can be reused repeatedly, the operating cost and maintenance cost can be kept low.

  (8) In the apparatus of (7), it is preferable that the suspension supply line L7 is connected to the raw water supply line L2 (FIG. 2).

  In the mixing tank, a dispersion medium is added to the filter aid and mixed to prepare a slurry suspension. Since this slurry-like suspension has a large solid content, when it is sent directly from the line L7 to the filtration membrane of the solid-liquid separator, a part of the filter aid remains in the line L7. Therefore, the suspension supply line L7 is connected to the raw water supply line L2, and the suspension from the line L7 is joined to the raw water flowing through the line L2, so that the filtration aid remaining in the line when passing the raw water is passed. Since it is sent to the solid-liquid separator together with the agent, a prescribed precoat thickness can be obtained.

  (9) In the apparatus of either (7) or (8) above, the treated water that is provided between the lower space 32 and the upper space 31 of the solid-liquid separator and permeates the filtration membrane 33 is used as the separation water. A first treated water utilization line L31 configured to be introduced into the space 31 can be further included (FIG. 2).

  According to the above embodiment, the treated water produced by the solid-liquid separation device can be sent to the upper space 31 via the line L31, and can be effectively used as peeling water for peeling off the precoat layer. In addition, since the treated water that has passed through the filtration membrane is rarely used immediately, a treated water storage tank for temporarily storing the treated water is provided, and an upper space of the solid-liquid separation device is provided from the storage tank as necessary. The treated water can be sent to

  (10) In any of the above devices (7) to (9), the treated water that is provided between the lower space 32 of the solid-liquid separation device and the magnetic separation tank 4 and permeates the filtration membrane is used as washing water. A second treated water utilization line L33 configured to be introduced into the separation tank 4 can be further provided (FIG. 2).

  According to the above embodiment, the treated water produced by the solid-liquid separation device can be effectively used as washing water that is sent to the magnetic separation tank via the line L33 to wash off the solid content adsorbed on the filter aid.

  (11) In the apparatus according to any one of (7) to (10), the mixing tank is provided with the treated water that is provided between the lower space 32 and the mixing tank 6 of the solid-liquid separator and permeates the filtration membrane as a dispersion medium. 6 can further include a third treated water utilization line L34 configured to be introduced into FIG. 6 (FIG. 2).

  According to the above embodiment, the treated water produced by the solid-liquid separator can be effectively used as a dispersion medium for sending the filter aid to the mixing tank 6 via the line L34.

(12) In the water treatment apparatus described here, (A) a part or all of magnetic single particles or aggregates thereof are covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. A filter aid supply device for supplying the filter aid, and (B) temporarily storing raw water containing solids, and mixing the raw material water with the filter aid from the filter aid supply device, A mixed raw water tank for producing a suspension in which the filter aid is dispersed in water; and (C) a filtration membrane that divides the interior into an upper space and a lower space, and the upper space communicates with the mixed raw water tank. A solid-liquid separator; and (D) introducing the suspension from the mixed raw water tank into an upper space of the solid-liquid separator, filtering the suspension through the filtration membrane, and filtering the filtration on the filtration membrane. Suspension provided to form a deposition layer containing auxiliaries and solids A supply line; and (E) stripping water for stripping the deposited layer from the filtration membrane is supplied to the upper space of the solid-liquid separator, whereby the stripping water strips the deposited layer from the filtration membrane. A stripping water supply line configured as described above, and (F) a stripped product of the deposited layer discharged together with the stripping water from an upper space of the solid-liquid separator is supplied, and the solid content contained in the stripped material and A magnetic separation tank configured to magnetically separate the filter aid; and (G) a filter aid configured to return the separated filter aid from the magnetic separation tank to the filter aid supply device. It has an agent return line and a filter aid return line configured to return the separated filter aid from the magnetic separation tank to the filter aid supply device.

  The water treatment apparatus of the said embodiment is an apparatus used for the body feed method. The filter aid is dispersed in the raw water in the mixed raw water tank, the raw water is passed through the filter membrane together with the filter aid, and a deposited layer composed of the filter aid / solid content 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, and further the peeling water is sprayed on the separation product, and the separation product is decomposed into pieces. To do. Next, the separated product separated into pieces is sent from the solid-liquid separation device to the separation tank together with the separation water, and the separated product is stirred in the 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 magnetically adsorbed by a magnetic adsorption means (electromagnet, permanent magnet, etc.), and while the filter aid is adsorbed by the magnetic adsorption means, the treated water containing the solid content is magnetically separated. To the collection and storage tank. Next, the magnetic adsorption of the filter aid is released, the filter aid is removed from the magnet, and treated water or tap water is sprayed on the magnet to wash and collect the filter aid adhered to the magnet. The recovered filter aid 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 and the mixed raw water tank.

In the above embodiment, by using a filter aid covered with a coating material having a specific critical surface tension γ _c , it is possible to easily separate the filter aid and the solid matter in water by a simple operation. Can do. That is, since the critical surface tension γ _c of the filter aid is low, solids in water can be separated into solid and liquid using stirring or ultrasonic waves in water, and only the filter aid can be adsorbed on the magnet and recovered. . Since the collected filter aid can be reused repeatedly, the operating cost and maintenance cost can be kept low.

  (13) In the apparatus of (12), the treated water that is provided between the lower space 32 and the upper space 31 of the solid-liquid separator and permeates the filtration membrane 33 is introduced into the upper space 31 as separation water. It can further have a first treated water utilization line L31 configured (FIG. 5).

  According to the above embodiment, the treated water produced by the solid-liquid separation device can be sent to the upper space 31 via the line L31, and can be effectively used as peeling water for peeling off the precoat layer.

  (14) In the apparatus according to (12) or (13), the treated water that is provided between the lower space 32 of the solid-liquid separator and the magnetic separation tank 4 and permeates the filtration membrane is used as washing water. A second treated water utilization line L33 configured to be introduced into the separation tank 4 can be further provided (FIG. 5).

  According to the above embodiment, the treated water produced by the solid-liquid separation device is sent to the magnetic separation tank via the line L33, and can be effectively used as washing water for washing away the solid content adsorbed and captured by the filter aid. it can.

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

  There are two types of water treatment methods using the filter aid of the present embodiment, a pre-coating method and a body feed method, but the apparatus used in 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 this embodiment is an apparatus used for the precoat method, and is effectively used particularly when the concentration of water insoluble matter in the water to be treated is low. The water treatment apparatus 1 has a raw water tank 2, a solid-liquid separation apparatus 3, a magnetic separation tank 4, a filter aid supply apparatus 5, a mixing tank 6, a raw water supply source and a drainage storage tank (not shown), and these devices. And the apparatus are connected to each other by a plurality of piping lines L1 to L8. Various pumps P1 to P9, valves V1 to V3, 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 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. As described above, the entire water treatment apparatus 1 is comprehensively controlled by a controller (not shown).

  The 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 solid-liquid separation device 3 includes a filtration membrane 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 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 three three-way valves V1, V2, and V3. 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. A treated water supply line L32 having a pump P2 branches off 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 (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 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 washing discharge water received from the upper space 31 of the solid-liquid separation device through the peeled material discharge line L4, and is separated into a solid and a filter aid. The magnet 42 for carrying out is built in. The magnet 42 is in a cylindrical pipe closed on one side, and is moved up and down by a controller (not shown), and the magnetic field is controlled on and off.

  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 is a pipe having a pump P6 for returning the filter aid separated and recovered from the magnetic separation tank 4 to the filter aid supply device 5.

  The filter aid supply device 5 is newly replenished with a filter aid supply source (not shown), and the filter aid separated in the magnetic separation tank 4 passes through the filter aid return line L5 described above. It is supposed to be returned. Moreover, the filter aid supply apparatus 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, adds a dispersion medium to the filter aid supplied from the filter aid supply device 5 and mixes by stirring, and a suspension containing the filter aid Is supposed to be made. It is preferable to use water as the dispersion medium. A third treated water utilization 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. In 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 joined at an appropriate position of the treated water supply line L2. The slurry-like suspension from the suspension supply line L7 is added to the raw water flowing through the treated 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.

(Method of the first embodiment)
Next, the water treatment method according to the first embodiment using the above-described apparatus will be described with reference to FIGS. 3 and 2.

  The precoat method is particularly effective when the concentration of water-insoluble matter contained in the water to be treated is low. The water-insoluble solid content in this embodiment is not particularly limited to an organic substance or an inorganic substance. Even if the particles are hardly dewatering particles such as heavy metal hydroxides or contain non-water-removing components other than particles, such as oil, they can be easily filtered by the structure of the filter aid. In this case, it is preferable to appropriately select a coating material for the filter aid according to the properties of the wastewater that is the water to be treated.

In the precoat method, first, a filter aid and a dispersion medium are mixed in the mixing tank 6 to prepare a suspension containing the filter aid (step S1). The filter aid includes a coating material having a single magnetic particle or an aggregate thereof in the core portion and further having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less that covers the magnetic core portion. Although water is mainly used as the dispersion medium, other dispersion medium can be appropriately used in addition to water. The concentration of the filter aid in the suspension is not particularly limited as long as a precoat layer, that is, a filter aid deposited layer can be formed by the following operation, but is adjusted to, for example, about 10,000 to 200,000 mg / L.

  Next, the suspension is passed through the filtration membrane 33 of the solid-liquid separator 3, and the filter aid in the suspension is filtered off and left on the filtration membrane 33, and the particle deposition is formed by laminating the filter aid. A layer (precoat layer) is formed (step S2). In addition, the water flow to the filtration membrane 33 by the pressurization pump P1 is performed at a predetermined pressure. Here, the filter surface is a filter in which a filter aid such as a filter cloth, a metal mesh, a porous ceramic, or a porous polymer is laminated thereon. Among these, a filter cloth is preferable, for example, a material such as polypropylene, nylon, polyester, and knitted with double weave, twill weave, plain weave, satin weave, or the like is used.

The filter surface is preferably orthogonal to the direction of gravity. Since the filter aid of this embodiment has a low critical surface tension γ _c , it is difficult to hold on the filter surface. For this reason, if it is not perpendicular to gravity (that is, parallel to the ground), the filter aid may slip on the filter surface, and uniform lamination may be difficult. If the surface is perpendicular to gravity, you don't have to worry about this.

  The filtration membrane 33 is attached so as to close the inlet of the solid-liquid separation device 3, and the suspension membrane is filtered by the filtration membrane 33 so that the pressure drop of the suspension in the solid-liquid separation device 3 is minimized. Do it. 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 solid (filter aid) and liquid by the filter membrane 33 is promoted. At this time, the liquid component of the suspension quickly permeates through the filtration membrane 33 and the solid component of the suspension (filter aid) passes through the filtration membrane 33 due to the synergistic action of the pressure and gravity caused by driving the pressurizing pump P1. As a result, a precoat layer is formed on the filtration membrane 33. In addition, although the thickness of a precoat layer changes with the density | concentrations of the liquid to process, it is about 0.1-10 mm in general.

  Next, the raw water is pumped from the raw water tank 2 to the solid-liquid separator 3 through the line L2 by driving the pump P1, and the raw water is passed through the filter 33 and the precoat layer (step S3). At this time, the water-insoluble solid content in the raw water is adsorbed and captured by the filter aid in the precoat layer.

  When the raw water filtration process is completed, the valve V1 is switched, the pump P3 is activated, and the pump P3 is driven to return part or all of the treated water to the upper space 31 of the solid-liquid separator through the line L3 → L31. The returned treated water is used as peeling water for peeling the precoat layer from the filter 33. Treated water (peeling water) is sprayed on the precoat layer from the side of the upper space 31 to peel the precoat layer from the filter 33, and further treated water is sprayed on the peeled material to decompose the peeled material apart, and a filter aid and The solid content is dispersed in the dispersion medium (step S4).

  The precoat layer may be peeled / decomposed in a container in which a filter is installed, or in another container. In the case where the precoat layer is peeled and decomposed in another container, the precoat layer is decomposed into disassembled pieces using a spray nozzle or the like and then transported. When the treated water is insufficient, the line L31 may be replenished with water from another location. 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.

  The suspension containing the decomposition product of the precoat layer is sent from the upper space 31 to the magnetic separation tank 4 through the line L4, and the decomposition product of the precoat layer is stirred in the magnetic separation tank 4 by the stirring screw 41. Further break down to particle level and disperse filter aid and solids. When this stirring is sufficiently performed, the filter aid and the solid content are more uniformly dispersed in the suspension, and the filter aid is easily separated.

  Next, the filter aid is recovered from the suspension after separation and decomposition of the precoat layer using a magnetic separation method (step S5). Magnetic separation methods include a method of collecting permanent magnets or electromagnets in the container of the magnetic separation tank 4 and a method of collecting particles by collecting them with a metal mesh magnetized by a magnet and releasing a magnetic field. Is mentioned. Specifically, there is a permanent magnet in a cylindrical pipe that is closed on one side, and after the filter aid is adsorbed and fixed in the suspension by the magnet 42, the line is drawn from the container of the magnetic separation tank 4 to the line. The waste liquid containing solid content is discharged to a storage tank (not shown) via L8, and then the magnet 42 is pulled up by an air cylinder (not shown) attached to the upper part of the magnet 42 to turn off the magnetic field. And a part of the treated water is supplied from the solid-liquid separation device 3 into the container via the line L32, and the treated water is added to the removed filter aid to form a slurry or suspension. The suspension-like filter aid is sent from the separation tank 4 to the filter aid supply device 5 via the line L5. Alternatively, after the filter aid is adsorbed and fixed by the magnet 42, the filter aid is moved to another container together with the magnet 42, the magnetic field of the magnet 42 is turned off in the other container, and the filter aid is removed from the magnet 42. You may make it drop | omit and collect | recover filter aids in another container.

  Thereafter, the 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 the cycle of precoat layer formation → filtration → separation → recovery → precoat layer formation.

  In this embodiment, a precoat layer is formed on the filtration membrane in advance, and then the treated water is passed through, so that the amount of solid matter adsorbed on the surface of the filter aid increases with the treatment time. As a result, the excessively adsorbed solid matter embeds the voids in the filter aid, so that the water flow rate is reduced.

(Device of Second Embodiment)
Next, a water treatment apparatus 1A used in the water treatment method of 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 used in the body feed method, and is effectively used particularly when the concentration of water insoluble matter in water is high. The difference of the apparatus 1A of the present embodiment from the apparatus 1 of the first embodiment is that the apparatus 1A has no mixing tank 6 and is provided with a mixed raw water tank 2A instead of the raw water tank 2. This mixed raw water tank 2A has both a function of temporarily storing raw water and leveling the flow rate of the raw water, and a mixing function of adding a filter aid to the raw water and mixing them. That is, in the apparatus 1A of the present embodiment, the filter aid is directly supplied from the filter aid supply device 5 into the mixed raw water tank 2A via the line L6 without going through the mixing tank. .

(Method of Second Embodiment)
Next, a body feed method as a second water treatment method using the above apparatus will be described with reference to FIGS.

  Also in this embodiment, the filter aid and the dispersion medium are first mixed to adjust the suspension. The dispersion medium used in this case is treated water existing in the mixing raw water tank 2A. 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 filtration layer can be formed by the following operation, but is adjusted to, for example, about 10,000 to 200,000 mg / L.

  Next, the suspension (water to be treated) is passed through the filtration membrane 33, the filter aid in the suspension is filtered off and left on the filter membrane 33, and the deposited layer formed by laminating the filter aid is formed. Form (step K2). In addition, the water flow with respect to the filtration membrane 33 is performed 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, it is preferable that the filter surface is horizontal.

  In addition, since the filtration layer is formed and held by the action of external force as described above, the filtering described above is performed by, for example, arranging the filtration membrane so as to close the container opening of the predetermined container, and the filtration thus arranged. The filter aid remains on the membrane so that it can be aligned and stacked. 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.

  After removing the water-insoluble matter in the water to be treated as described above, the filter layer is dispersed in the dispersion medium, the filter layer is decomposed into a filter aid, and the filter aid is washed (step K3). This washing may be performed in a container in which the filtration membrane 33 is installed, or may be performed in another container. In the case of using another container, the deposited layer is decomposed into a filter aid by means of cleaning or the like and then transported. Although water is used for washing, washing with a surfactant or an organic solvent is also possible.

  Next, the washed filter aid is recovered using a magnetic separation method (step K4). The method used for the magnetic separation method is not particularly limited, but a method of collecting a permanent magnet or an electromagnet in a container and a method of collecting particles by collecting them with a metal mesh magnetized by a magnet and releasing a magnetic field Etc.

  In the water treatment method of the present embodiment, the filter aid constituting the deposition layer is contained in the water to be treated, that is, in the suspension prepared using this water, so that the water-insoluble to be removed. The filter aid is always supplied together with the water to be treated (suspension) containing the solid content.

  Therefore, even when the amount of solid content in the water to be treated (suspension) is large, the supply of water-insoluble matter and the supply of filter aid are performed at the same time. Like the form, the water insoluble matter adsorbed excessively does not embed the voids of the filter aid. For this reason, the filtration rate can be maintained for a long time. As a result, as described above, the water treatment method of the second embodiment is effective when the concentration of water insoluble matter in the water to be treated is high.

  According to the above embodiment, the filter aid can be easily reused, and fine solid matter in water can be removed without adding chemicals.

  Various examples and comparative examples will be described below.

(Preparation of filter aid)
(Filter aid A)
High speed mixing in a Henschel mixer using a resin dispersion consisting of 2% polyamideimide consisting of a reaction product of maleic anhydride and diaminodiphenylmethane and 10% copolymer of ethylene fluoride and polypropylene fluoride on the surface of manganese magnesium ferrite particles The filter aid was prepared by spraying the ferrite particles to be applied to the surface, and curing the ferrite particles at 200 ° C. for 1 hour, thereby coating the ferrite surface with a fluororesin. (Spherical, average particle diameter 35 μm) The critical surface tension γ _c of the fluororesin was 18.5 × 10 ⁻³ N / m.

(Filter aid B)
Similarly to the filter aid A, a filter aid in which the surface of the manganese magnesium ferrite particles was coated with a fluororesin was prepared. (Spherical, average particle size 50 μm)
(Filter aid C)
Similarly to the filter aid A, a filter aid in which the surface of the manganese magnesium ferrite particles was coated with a fluororesin was prepared. (Irregular shape, average particle size 2μm)
(Filter aid D)
Similarly to the filter aid A, a filter aid in which the surface of the manganese magnesium ferrite particles was coated with a silicone resin (SR-2441) manufactured by Toray Dow Corning was prepared. (Amorphous, average particle diameter 35 μm) The critical surface tension γ _c of the silicone resin was 22 × 10 ⁻³ N / m.

  As a comparative example, the following filter aid was prepared.

(Filter aid E)
Manganese magnesium ferrite particles having an average particle diameter of 35 μm were prepared.

(Filter aid F)
Similarly to the filter aid A, a filter aid in which the surface of the manganese magnesium ferrite particles was coated with a fluororesin was prepared. (Spherical, average particle size 14μm)
(Filter aid G)
A metal oxide mixture in which the molar ratio was adjusted to 40% manganese, 10% magnesium, and 50% iron was prepared. This was dispersed in water, and a granulated body having an average particle diameter of 40 μm was produced by spray drying at 200 ° C. using polyvinyl alcohol as a binder. The granulated body was sintered at 1200 ° C. to obtain a porous manganese magnesium ferrite. Similarly to the filter aid A, a filter aid having a fluororesin coated on the particle surface was prepared. (Spherical, average particle size 40μm)
(Filter aid H)
Similarly to the filter aid A, a filter aid in which the surface of the manganese magnesium ferrite particles was coated with a fluororesin was prepared. (Spherical, average particle diameter 85μm)
(Water treatment equipment)
Example 1
A device as schematically shown in FIG. 2 was produced. The water to be treated containing solid matter is supplied to the raw water tank 2 and temporarily received in the tank. Here, the time fluctuation of the treated water is averaged by mixing with a mixer. Moreover, a filter aid is sent from the filter aid supply device 5 to the mixing tank 6 and mixed with treated water that is partially reused to produce a filter aid slurry. This filter aid slurry is first sent to the solid-liquid separator 3 to form a filter aid membrane on the filter membrane 33. In this example, a filter cloth made of woven cloth was used as the filter membrane. Thereafter, the liquid to be treated is supplied to the solid-liquid separation device 3 under pressure, and solid-liquid separation (filtration) is performed with a filter aid membrane formed in advance. The filtrate (treatment liquid) is the one from which the solid matter has been removed and may be drained after necessary treatment, but the washing water for the solid-liquid separation device 3 and the washing water for the magnet of the magnetic separation tank 4 are mixed. It can also be used as a liquid when preparing the filter aid slurry in the tank 6. When filtration of the water to be treated is completed, a filter aid and a solid deposit (cake) in water are present in the filter membrane 33 in the solid-liquid separator 3. In order to peel this from the filtration membrane 33, peeling water is sprayed from the side of the filtration membrane 33 to peel and decompose the deposit (cake), which is discharged from the solid-liquid separator 3 to the magnetic separation tank 4. The magnetic separation tank 4 includes a stirring mechanism 41 and an electromagnet (magnetic separation mechanism) 42, and separates the filter aid and the solid matter while mixing and stirring, and collects and separates only the filter aid with the magnet 42. The liquid collected from the filter aid is collected as concentrated water containing a high-concentration solid material, washed with the supplied wash water, and returned to the filter aid supply device 5. The filter aid returned in this way is supplied again to the mixing tank 6 and is reused for producing a suspension for forming the precoat layer.

  Simulated waste water containing bentonite 200 mg / L was prepared as water to be treated. This was supplied to the raw water tank 2 and mixed. Moreover, the filter aid was supplied to the mixing tank 6 from the filter aid supply apparatus 5 filled with the filter aid A, and water was mixed, and the filter aid slurry was produced. This was supplied to the solid-liquid separator 3, and a precoat layer having an average thickness of 1 mm was produced on the filtration membrane 33. After that, when water to be treated was supplied from the raw water tank 2 to the solid-liquid separator 3 and subjected to filtration, it was confirmed that 90% of bentonite in the filtrate (treated water) was removed. After the filtration treatment, peeling water was sprayed from the side of the filtration membrane 33 of the solid-liquid separator 3, the precoat layer was peeled off from the filtration membrane 33, and the peeled material was discharged into the magnetic separation tank 4. After the stirrer 41 in the magnetic separation tank 4 was operated to separate the filter aid and bentonite, only the filter aid was separated by operating the magnet 42 and the liquid was discharged to obtain a bentonite concentrate. When the concentrate was analyzed, almost 99% or more of the filtered bentonite was desorbed and recovered. Thereafter, the magnetic field of the magnet was released, cleaning water was supplied to make a filter aid slurry, and then returned to the filter aid supply device 4. The recovered filter aid was supplied to the mixing tank 6 and the same operation as described above was performed, but the recovered filter aid could be reused without any problem.

(Example 2)
A test was performed in the same manner except that filter aid B was used instead of filter aid A using the same apparatus as in Example 1. The bentonite removal rate was 88%. Although the water flow rate of the solid-liquid separator was 1.5 times that of Example 1, it could be operated without any problem, and the bentonite recovery rate was 99% or more.

(Example 3)
Using the same apparatus as in Example 1, a test was conducted in the same manner except that filter aid C was used instead of filter aid A. The removal rate of bentonite was 99% or more. Compared with Example 1, the water flow rate of the solid-liquid separator became almost 1/4, but it could be operated without any problem, and the bentonite recovery rate was 99% or more.

Example 4
A test was performed in the same manner except that filter aid D was used instead of filter aid A using the same apparatus as in Example 1. The bentonite removal rate was 90%. Compared with Example 1, the water flow rate of the solid-liquid separator was almost the same, and the recovery rate of bentonite was 91%.

(Example 5)
A test was performed in the same manner except that filter aid F was used in place of filter aid A using the same apparatus as in Example 1. The removal rate of bentonite was about 100%. Compared with Example 1, the water flow rate of the solid-liquid separator was almost the same, and the bentonite recovery rate was 96%.

(Example 6)
A test was performed in the same manner except that filter aid G was used instead of filter aid A, using the same apparatus as in Example 1. The bentonite removal rate was 98%. Compared with Example 1, the water flow rate of the solid-liquid separator was 1.5 times, and the recovery rate of bentonite was 90%.

(Comparative Example 1)
A test was performed in the same manner except that filter aid D was used instead of filter aid A using the same apparatus as in Example 1. The bentonite removal rate was 90%. Compared to Example 1, the water flow rate of the solid-liquid separator was about 80%, but the recovery rate of bentonite was 25%.

(Example 7)
An apparatus schematically shown in FIG. 5 was produced. The water to be treated containing solid matter is supplied to the mixed raw water tank 2A and temporarily received by the mixed raw water tank 2A. Further, the filter aid is supplied also from the filter aid supply device 5 to the mixed raw water tank 2A, and a mixed slurry of bentonite and filter aid is made. When this filter aid slurry is first sent to the solid-liquid separator 3, a deposited layer composed of the filter aid and bentonite is formed on the filter membrane 33. In this deposited layer, bentonite is trapped by the filter aid.

  Since the filtrate (treated water) is a bentonite-removed liquid, it may be appropriately treated and drained, but it is also used as the separation water for the solid-liquid separator 3 and the washing water for the magnetic separation tank 4. Is possible. When filtration of the water to be treated is completed, a filter aid and a deposited bentonite layer (cake) are present in the filter membrane 33 in the solid-liquid separator 3. In order to peel this from the filtration membrane 33, peeling water is sprayed from the side of the filtration membrane 33 to peel the deposited layer (cake), and the peeled material is discharged to the magnetic separation tank 4. The magnetic separation tank 4 includes a stirring mechanism 41 and a magnet 42 (magnetic separation mechanism), separates the filter aid and bentonite while mixing and stirring, and adsorbs and collects only the filter aid with the magnet 42. The liquid collected from the filter aid is collected as concentrated water containing high-concentration bentonite, washed with the supplied wash water, and returned to the filter aid supply device 5. The recovered filter aid was supplied to the mixing tank 6 and the same operation as described above was performed, but the recovered filter aid could be reused without any problem.

  Simulated waste water containing bentonite 200mg / L was prepared as water to be treated. This was supplied to the mixing raw water tank 2A and mixed. Moreover, the filter aid was supplied to the mixed raw water tank 2A from the filter aid supply device 5 filled with the filter aid A so as to be 2000 mg / L, thereby preparing a slurry of the filter aid and bentonite. When this was supplied to the solid-liquid separator 3 and filtered on the filtration membrane 33, it was confirmed that 97% of bentonite in the filtrate (treated water) was recovered. After the filtration treatment, peeling water was sprayed from the side of the filtration membrane 33 of the solid-liquid separation device 3, the deposited layer formed on the filtration membrane 33 was peeled off, and the peeled material was discharged to the magnetic separation tank 4. After the stirrer 41 in the magnetic separation tank 4 was operated to separate the filter aid and bentonite, the magnet 42 was operated, and only the filter aid was adsorbed, separated and recovered, and a bentonite concentrate was obtained as the residue. When the concentrate was analyzed, it was confirmed that almost the entire amount of bentonite had been detached. Thereafter, the magnetic field of the magnet was released, washing water was supplied to make a filter aid slurry, and then returned to the filter aid supply device 5. The recovered filter aid was supplied to the mixing tank 6 and the same operation as described above was performed, but the recovered filter aid could be reused without any problem.

(Example 8)
Using the same apparatus as in Example 1, a test was conducted in the same manner except that filter aid H was used instead of filter aid A, cellulose particles having an average particle diameter of 50 μm and gear oil of the same amount were used instead of bentonite. It was. The removal rate of cellulose was 100%. The cellulose recovery rate was 90%.

(Comparative Example 2)
A test was performed in the same manner except that filter aid E was used in place of filter aid H using the same apparatus as in Example 8. Although the removal rate of cellulose was 100%, cellulose could not be separated from the magnetic material and cellulose could not be recovered.

1, 1A ... Water treatment device, 2 ... Raw water tank, 2A ... Mixed raw water tank,
3 ... solid-liquid separator, 31 ... upper space, 32 ... lower space, 33 ... filtration membrane,
4 ... Magnetic separation tank, 5 ... Filter aid supply device, 6 ... Mixing tank,
10 ... primary particles, 11 ... magnetic particles, 12 ... coating material (polymer),
13 ... Secondary aggregate (filter aid, aggregate of primary particles),
P1-P9 ... pump, V1-V3 ... valve,
L2 ... treated water supply line, L3 ... treated water line, L31 ... stripped water supply line (first treated water utilization line), L32 ... treated water carry-out line, L33 ... second treated water utilization line, L34 ... first 3 treated water utilization line,
L4 ... Washing drain water line, L5 ... Filter aid return line, L6 ... Filter aid supply line, L7 ... Mixing line, L8 ... Recovery component concentrated water discharge line.

Claims (14)

(A) preparing a filter aid in which part or all of magnetic single particles or aggregates thereof are covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less,
(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 solids is passed through the precoat layer and the filtration membrane. The solid component is adsorbed and captured by the filter aid of the precoat layer, thereby separating the solid component from the water to be treated,
(D) pouring release water into the precoat layer to release the precoat layer from the filtration membrane, thereby providing a mixture of the release product of the precoat layer and the release water that has captured the solid content;
(E) magnetically separating the filter aid from the mixture;
(F) The separated filter aid is reused for preparing a suspension in the step (b).
A water treatment method characterized by the above. (A) preparing a filter aid in which part or all of magnetic single particles or aggregates thereof are covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less,
(B) Mixing the water to be treated containing 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 filtration aid and the solid content is formed on the filtration membrane, and the solid content is adsorbed to the filtration aid in the deposition layer. -Capture and thereby separate the solids from the treated water,
(D) Pour stripping water into the deposited layer to strip the deposited layer from the filtration membrane, thereby providing a mixture of the stripped layer stripped product and the stripped water capturing the solid content;
(E) magnetically separating the filter aid from the mixture;
(F) The separated filter aid is reused for the preparation of the suspension in the step (B).
A water treatment method characterized by the above.   The method according to claim 1, wherein the filtration membrane has a filtration surface perpendicular to a direction in which gravity acts.   The method according to any one of claims 1 to 3, wherein an average particle diameter of the filter aid is in the range of 1 to 50 µm.   The method according to any one of claims 1 to 4, wherein the covering material contains either a silicone resin or a fluororesin.   The method according to any one of claims 1 to 5, wherein the magnetic single particles are made of a ferrite compound. (A) A filter aid supply device for supplying a filter aid in which part or all of magnetic single particles or aggregates thereof are covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. When,
(B) a raw water tank for temporarily storing raw water containing solids;
(C) a mixing tank that mixes a dispersion medium with the filter aid supplied from the filter aid supply apparatus, and produces a suspension in which the filter aid is dispersed in the dispersion medium;
(D) a solid-liquid separation device having a filtration membrane that partitions the interior into an upper space and a lower space, wherein the upper space communicates with the filter aid supply device and the mixing tank,
(E) The suspension is introduced from the mixing tank into the upper space of the solid-liquid separator, the suspension is filtered through the filtration membrane, and a precoat layer made of the filter aid is formed on the filtration membrane. A suspension supply line configured to:
(F) Raw water is introduced from the raw water tank into the upper space of the solid-liquid separator, and the raw water is passed through the precoat layer and the filtration membrane, whereby the solid content is captured by the filter aid of the precoat layer. A raw water supply line configured to provide filtrate to the lower space;
(G) Supplying stripping water for stripping the precoat layer capturing the solid content from the filtration membrane to the upper space of the solid-liquid separator, whereby the stripping water strips the precoat layer from the filtration membrane. Stripping water supply line configured as follows,
(H) The exfoliated material of the precoat layer discharged together with the exfoliated water from the upper space of the solid-liquid separator is supplied, and the solid content contained in the exfoliated material and the filter aid are magnetically separated. A magnetic separation tank configured in
(I) a filter aid return line configured to return the separated filter aid from the magnetic separation tank to the filter aid supply device;
A water treatment apparatus comprising:   The apparatus according to claim 7, wherein the suspension supply line is connected to the raw water supply line.   A first treated water utilization line provided between the lower space and the upper space of the solid-liquid separator and configured to introduce treated water that has passed through the filtration membrane into the upper space as the stripped water. The apparatus according to claim 7, further comprising:   Use of second treated water provided between the lower space of the solid-liquid separator and the magnetic separation tank, and configured to introduce treated water that has passed through the filtration membrane into the magnetic separation tank as washing water The apparatus according to claim 7, further comprising a line.   A third treated water utilization line provided between the lower space of the solid-liquid separator and the mixing tank and configured to introduce the treated water that has passed through the filtration membrane into the mixing tank as the dispersion medium. The apparatus according to claim 7, further comprising: (A) A filter aid supply device for supplying a filter aid in which part or all of magnetic single particles or aggregates thereof are covered with a coating material having a critical surface tension γ _c of 22 × 10 ⁻³ N / m or less. When,
(B) While temporarily storing raw water containing solid content, a filter aid from the filter aid supply device is mixed with the raw water to produce a suspension in which the filter aid is dispersed in the raw water. Mixing raw water tank,
(C) a solid-liquid separator having a filtration membrane that divides the interior into an upper space and a lower space, wherein the upper space communicates with the mixed raw water tank;
(D) The suspension is introduced from the mixed raw water tank into the upper space of the solid-liquid separator, the suspension is filtered through the filtration membrane, and the filter aid and solid content are added onto the filtration membrane. A suspension supply line configured to form a deposited layer comprising:
(E) Supplying stripping water for stripping the deposited layer from the filtration membrane to the upper space of the solid-liquid separator, whereby the stripping water strips the deposited layer from the filtration membrane. Stripped water supply line,
(F) A separation product of the deposited layer discharged from the upper space of the solid-liquid separation device together with the separation water is supplied, and the solid content contained in the separation product and the filter aid are magnetically separated. A magnetic separation tank configured in
(G) a filter aid return line configured to return the separated filter aid from the magnetic separation tank to the filter aid supply device;
A filter aid return line configured to return the separated filter aid from the magnetic separation tank to the filter aid supply device;
A water treatment apparatus comprising:   Use of first treated water provided between the lower space and the upper space of the solid-liquid separator and configured to introduce treated water that has passed through the filtration membrane into the magnetic separation tank as the separation water. The apparatus of claim 12, further comprising a line.   A second treated water use line provided between the lower space of the solid-liquid separator and the magnetic separation tank, and configured to introduce treated water that has passed through the filtration membrane into the magnetic separation tank; 14. A device according to any one of claims 12 or 13, characterized in that it comprises a device.

Images