JP5348369B2 - Water treatment method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method for treating even the water to be treated of low turbidity. <P>SOLUTION: The water treatment method includes: a coagulant aid adding process of adding a coagulant aid to the water to be treated; a polymer particle adding process of adding particles made of a cationic polymer which swells but does not substantially dissolve in water after the coagulant aid adding process; an agitation process of agitating the water to be treated after the polymer particle adding process; and a solid-liquid separation treatment process of solid-liquid separating the water to be treated after the agitation process. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a method for treating water to be treated such as industrial water, city water, river water, lake water, and well water, and more particularly to a water treatment method that can be applied to water to be treated having low turbidity.

  Microfiltration membranes (MF membranes), ultrafiltration membranes (UF membranes), reverse osmosis membranes (RO membranes), etc. as methods for treating treated water such as industrial water, city water, river water, lake water, and well water There is a method of membrane separation treatment for passing water through the membrane. Industrial water, city water, well water, etc. are usually membrane contaminants that contaminate membranes, such as humic acid and fulvic acid organic substances, biological metabolites such as sugar produced by algae, and synthetic chemicals such as surfactants. Therefore, when the membrane separation treatment is performed, there is a problem that these membrane contaminants are adsorbed on the membrane surface and the membrane separation performance deteriorates.

  Therefore, before the membrane separation treatment, an inorganic flocculant and an anionic polymer flocculant are added to the water to be treated to agglomerate to condense the membrane contaminants, and the liquid is solidified by precipitation or pressurized flotation. After the separation, a method of subjecting the supernatant, that is, the water to be treated from which membrane contaminants have been removed, to membrane separation treatment is performed. However, when the polymer flocculant is added, a new problem arises in that the polymer flocculant remaining in the water is adsorbed on the subsequent membrane to contaminate the membrane and deteriorate the separation performance of the membrane.

  As a method for solving such a problem, an inorganic flocculant and a polymer flocculant are added to the water to be treated, and after the aggregation reaction, the inorganic flocculant is added again before solid-liquid separation, and then solid-liquid separation is performed. There is an aggregating and separating method (see Patent Document 1). However, in the method of Patent Document 1, it is necessary to add an inorganic flocculant and a polymer flocculant to the water to be treated and then add the inorganic flocculant again. Therefore, a simpler method is required. Yes.

  Therefore, as a method for solving these problems, the applicant of the present invention added an adsorption treatment by adding particles made of a cationic polymer that swells in water and does not substantially dissolve in water to the treatment water. A method for membrane separation treatment of treated water with a separation membrane was filed earlier (Japanese Patent Application No. 2007-284111). According to this method, adsorption of membrane contaminants contained in the water to be treated to the membrane surface can be reduced, and deterioration of membrane separation performance can be reduced.

  However, in the method of Japanese Patent Application No. 2007-284111, when the turbidity of the water to be treated is low, that is, when the amount of the turbidity (SS) of the water to be treated is small, Particles that are made of a cationic polymer that does not dissolve in water, and that are made of a cationic polymer that swells in water and does not substantially dissolve in water, so that the cationic polymer swells in water and does not substantially dissolve in water. The inside of the system such as the wall of a reaction tank (coagulation tank) for adding particles made of water to the treated water is contaminated, and there is a problem that clear treated water may not be obtained continuously. In addition, not only in the case of performing the membrane separation process as described above, but also in the case of performing other solid separation processes such as pressurized flotation, there is a similar problem that the inside of the system such as an agglomerated layer is contaminated.

Japanese Patent Laid-Open No. 11-77062

  An object of this invention is to provide the water treatment method which can process the to-be-processed water with low turbidity in view of the situation mentioned above.

  As a result of intensive studies to achieve the above object, the present inventor has added a coagulation aid to the water to be treated, and then added particles made of a cationic polymer that swells in water and does not substantially dissolve in water, It has been found that the above object can be achieved by employing a solid-liquid separation method, and the present invention has been completed.

That is, the water treatment method of the present invention comprises a flocculation aid addition step of adding a flocculation aid to treated water, and after the flocculation aid addition step , primary amines, secondary amines, tertiary amines and their acids. It is a copolymer of a cationic monomer having a functional group such as a salt or a quaternary ammonium group and a crosslinking agent monomer, and it swells to a particle size of 10 to 200 times in water with respect to the particle size when not swollen. A polymer particle addition step of adding particles made of a cationic polymer that is substantially insoluble in water, a stirring step of stirring the water to be treated after the polymer particle addition step, and solidifying the water to be treated after the stirring step. It has a solid-liquid separation process step for performing liquid separation.
The turbidity of the water to be treated before adding the coagulation aid may be less than 5 degrees.
Moreover, it is preferable that the aggregating aid is an inorganic aggregating agent.

  After adding a coagulant aid to the water to be treated, particles made of a cationic polymer that swells in water and does not substantially dissolve in water are added, and then a solid-liquid separation treatment is performed. Even treated water can be treated, and clear treated water can be obtained without contaminating the system or the membrane.

Hereinafter, the present invention will be described in detail based on embodiments.
The water treatment method of the present invention comprises a flocculation aid addition step of adding a flocculation aid to treated water, and particles comprising a cationic polymer that swells in water after the flocculation aid addition step and does not substantially dissolve in water. A polymer particle adding step of adding, a stirring step of stirring the water to be treated after the polymer particle adding step, and a solid-liquid separation processing step of subjecting the water to be treated to solid-liquid separation after the stirring step .

  First, an agglomeration aid is added to the water to be treated (aggregation aid addition step). Examples of water to be treated include turbidity, humic acid and fulvic acid organic substances, biological metabolites such as sugar produced by algae, or synthetic chemicals such as surfactants, specifically, Industrial water, city water, river water, lake water, well water, and the like. In addition, humic acid and fulvic acid organic substances, biological metabolites such as sugar produced by algae, or synthetic chemical substances such as surfactants are substances that contaminate the membrane when membrane separation treatment is performed later. (Film contamination).

  And in this invention, even if it uses water whose turbidity (amount of turbidity (SS)) is less than 5 degrees, for example, 0.1 degree or more and less than 5 degree | times as to-be-processed water, it can process suitably. it can. Treated water whose turbidity is maintained at less than 5 degrees can be suitably treated to obtain clear treated water. Also, treated water with high turbidity such as industrial water and river water is usually used. However, even those having a turbidity of less than 5 degrees due to fluctuations in water quality can be suitably treated. In the present specification, turbidity is a value determined by a transmitted light measurement method using a kaolin standard solution.

  The agglomeration aid is not particularly limited as long as it can increase the turbidity of water to be treated. For example, turbid components such as bentonite and kaolin, and aluminum such as sulfate bands and polyaluminum chloride are used. Inorganic flocculants such as salts, iron salts such as ferric chloride and ferrous sulfate can be mentioned, and inorganic flocculants are particularly preferable. The inorganic flocculant also functions as a flocculant, and can remove COD components and turbidity from the water to be treated. From the cationic polymer that swells in water added later and does not substantially dissolve in water. This is because the amount of added particles can be reduced. Moreover, you may use together multiple types of aggregation adjuvant.

  The addition amount of the coagulation aid is not particularly limited, but is preferably added so that the turbidity of the water to be treated after adding the coagulation aid is 5 degrees or more, for example, 5 degrees to 10 degrees, preferably Is about 5 to 7 degrees.

  After the aggregation auxiliary agent addition step, particles made of a cationic polymer that swells in water and does not substantially dissolve in water are added (polymer particle addition step). Here, humic acid and fulvic acid organic substances, biological metabolites such as sugars produced by algae, or synthetic chemical substances such as surfactants do not aggregate with ordinary polymer flocculants and inorganic flocculants. Complete and difficult to remove from treated water. However, by adding particles made of a cationic polymer that swells in water and does not substantially dissolve in water (hereinafter sometimes referred to as “swellable polymer particles”), the particles can be well aggregated.

  The cationic polymer which swells in the water constituting the particles to be added to the water to be treated and does not substantially dissolve in water includes, for example, primary amines, secondary amines, tertiary amines and their acid salts, quaternary ammonium groups, etc. Is a copolymer of a cationic monomer having the functional group and a crosslinking agent monomer for substantially not dissolving in water. Specific examples of the cationic monomer include dimethylaminoethyl (meth) acrylate acid salt or its quaternary ammonium salt, dimethylaminopropyl (meth) acrylamide acid salt or its quaternary ammonium salt, diallyldimethylammonium chloride, and the like. It is done. Examples of the cross-linking agent monomer include divinyl monomers such as methylene bisacrylamide. Moreover, it is good also as a copolymer with the anionic or nonionic monomer copolymerizable with the said cationic monomer. Specific examples of the anionic monomer to be copolymerized include (meth) acrylic acid, 2-acrylamido-2-methylpropanesulfonic acid, and alkali metal salts thereof. It is necessary to use a small amount so as not to impair the properties as a conductive polymer. Nonionic monomers include (meth) acrylamide, N isopropylacrylamide, N methyl (NN dimethyl) acrylamide, acrylonitrile, styrene, methyl or ethyl (meth) acrylate. Each monomer may be one kind or plural kinds. The amount of the crosslinking agent monomer such as divinyl monomer is required to be 0.0001 to 0.1 mol% with respect to the total monomer, and the amount of swelling of the swellable polymer particles and the particle diameter in water can be adjusted by this amount. . As the swellable polymer particles, for example, Akogel C (manufactured by Mitsui Cytec Co., Ltd.) is commercially available. An anion exchange resin such as WA20 (manufactured by Mitsubishi Chemical Corporation) may be used as the swellable polymer particles. Further, the average particle size of the swellable polymer particles is not particularly limited, but the average particle size in the reversed-phase emulsion liquid or the suspension-like dispersion liquid, that is, the average particle size in a state not swollen with water is 100 μm or less. It is preferable that the thickness is 0.1 to 10 μm. This is because the smaller the particles, the higher the adsorbing effect of turbidity contained in the water to be treated, but if it is too small, solid-liquid separation becomes difficult.

  There is no particular limitation on the form of adding particles composed of a cationic polymer that swells in water and does not substantially dissolve in water to the water to be treated. For example, the particles may be used as they are, or dispersed in water, You may add in the form of an emulsion liquid or a suspension-like dispersion liquid. In any case, by adding the swellable polymer particles to the water to be treated, the water to be treated comes into contact with the swellable polymer particles, and the turbidity contained in the water to be treated is swellable through a subsequent stirring step. What is necessary is just to make it adsorb | suck to a polymer particle and to aggregate.

  Two or more kinds of swellable polymer particles may be added to the water to be treated. Since the cationic polymer constituting the swellable polymer particles swells in water and does not substantially dissolve in water, the swellable polymer particles also swell in water and substantially water, unlike ordinary polymer flocculants. Does not dissolve. “Substantially insoluble in water” means that the degree of water solubility is such that it can exist as particles composed of a cationic polymer in water. Specifically, for example, solubility in water at 30 ° C. Is about 0.1 g / L or less. The degree of swelling of these particles in water is about 10 to 200 times the particle size in water with respect to the particle size when not swollen with water.

  Here, although it demonstrates in detail below about the particle | grains which consist of a cationic polymer made into the form of a reverse phase emulsion liquid, it is not limited to this form. In addition, it is not a special thing but is a very general reverse phase (W / O) emulsion polymer.

  The inverse emulsion liquid contains the cationic polymer, water, a hydrocarbon liquid, and a surfactant. And mass ratio (%) of each component is cationic polymer: water: hydrocarbon liquid: surfactant = 20-40: 20-40: 20-40: 2-20, and the cationic polymer and water. The total mass is preferably 40 to 60% by mass with respect to the total mass of the cationic polymer, water, hydrocarbon liquid and surfactant.

  Examples of the hydrocarbon liquid include, but are not limited to, isoparaffins such as isohexane, and aliphatic hydrocarbon liquids such as n-hexane, kerosene, and mineral oil.

  Examples of the surfactant include polyoxyethylene ethers of higher aliphatic alcohols having 10 to 20 carbon atoms, or higher fatty acids having 10 to 22 carbon atoms, such as HLB (hydrophilic lipophilic balance) of 7 to 10. A polyoxyethylene ester is mentioned. Examples of the former include polyoxyethylene (EO addition mole number = 3 to 10) ethers such as lauryl alcohol, cetyl alcohol, stearyl alcohol, and oleyl alcohol. Examples of the latter include polyoxyethylene (EO addition mole number = 3 to 10) esters such as lauric acid, palmitic acid, stearic acid, and oleic acid.

  The reverse phase emulsion liquid is obtained by polymerizing a monomer (emulsion polymerization or suspension polymerization) by mixing a cationic monomer or a crosslinking agent monomer, which is a raw material of the cationic polymer, with water, a hydrocarbon liquid, and a surfactant. However, the present invention is not limited to this. For example, after various monomers are solution polymerized, they are pulverized with a homogenizer, and then added to a hydrocarbon liquid together with a dispersant such as a surfactant. It is done.

  When the swellable polymer particles are added to the water to be treated, the surface area of the particles is preferably large. Therefore, it is preferable to add the particles in the form of the above-mentioned reversed phase emulsion liquid or suspension-like dispersion liquid to the water to be treated after adding the particles to the water under stirring to swell the particles.

  Although there is no restriction | limiting in particular in the quantity which adds a swelling polymer particle to to-be-processed water, It is preferable to set it as about 1-50 mass% with respect to the total amount of the turbidity and film | membrane contaminant contained in to-be-processed water.

  Moreover, you may provide the process of adding an inorganic flocculant to to-be-processed water simultaneously with a polymer particle addition process, or a back | latter stage. By adding an inorganic flocculant as a turbid flocculant, the turbidity easily aggregates, and the turbidity removal effect increases. In addition, when providing the process of adding an inorganic flocculant to to-be-processed water simultaneously with a polymer particle addition process or a back | latter stage, in the agglomeration adjuvant addition process provided in the front | former stage of a polymer particle addition process, it is inorganic aggregation It is preferable to add an agglomeration aid that is not an agent. The inorganic flocculant is not particularly limited, and examples thereof include an aluminum salt such as a sulfuric acid band and polyaluminum chloride, and an iron salt such as ferric chloride and ferrous sulfate. Moreover, there is no limitation in particular also in the addition amount of an inorganic flocculant, What is necessary is just to adjust according to the property of the to-be-processed water to process, but about 0.5-10 mg / L in conversion of aluminum or iron with respect to to-be-processed water. It is. Further, although depending on the properties of the water to be treated, when polyaluminum chloride (PAC) is used as the inorganic flocculant, the pH of the water to be treated to which the swellable polymer particles and the inorganic flocculant are added is pH 5.0-7. If it is about 0.0, aggregation is optimal.

  After such a polymer particle addition step, the water to be treated is stirred (stirring step). Thereby, turbidity etc. are made to adsorb | suck to swelling polymer particle | grains completely, and turbidity etc. are aggregated. Here, when the flocculation aid addition step is not performed before the polymer particle addition step, when the turbidity of the water to be treated is low, the wall surface of the flocculation tank to which the swellable polymer particles are added and the solid-liquid separation treatment at the latter stage Swelling polymer particles that are not adsorbed by turbidity adhere to the system, such as the walls of the sedimentation tank in the process, contaminate the system, and turbidity aggregation becomes incomplete. If the aggregation of the turbidity becomes incomplete, there arises a problem that a clear treated water cannot be obtained, or the membrane is contaminated by a subsequent membrane separation treatment. The mechanism by which turbid aggregation is incomplete is not clear, but is presumed as follows. When the flocculation aid addition step is not performed, if the turbidity of the water to be treated is low, swellable polymer particles that are not adsorbed by the turbidity are present and adhere to the system such as the wall of the flocculation tank or the precipitation tank. When the swellable polymer adheres to the wall surface or the like, the swellable polymer further adheres to the attached swellable polymer, and the swellable polymer that adsorbs the turbidity is insufficient, and the aggregation of the turbidity is incomplete. Become.

  On the other hand, in the present invention, since the aggregation assistant addition step is performed before the polymer particle addition step, contamination of the wall surface of the aggregation tank or the like, and insufficient aggregation can be suppressed.

  After the stirring step, the water to be treated is subjected to solid-liquid separation treatment (solid-liquid separation treatment step). The solid-liquid separation treatment is not particularly limited as long as aggregates such as turbidity generated in the stirring step can be removed from the water to be treated, but precipitation treatment, sand filtration treatment, pressure flotation treatment, membrane separation treatment, and the like. Etc.

  In the precipitation treatment and the pressure levitation treatment, it is preferable to adjust pH with caustic soda, slaked lime, sulfuric acid or the like and finally flocculate the suspension with an organic polymer flocculant. Moreover, an organic coagulant can also be used together as needed. There is no particular limitation on the organic coagulant, for example, polyethyleneimine, ethylenediamine epichlorohydrin polycondensate, polyalkylene polyamine, polymers having quaternary ammonium salts of diallyldimethylammonium chloride or dimethylaminoethyl (meth) acrylate as constituent monomers, etc. Examples include cationic organic polymers that are usually used in water treatment. Moreover, there is no limitation in particular also in the addition amount of an organic coagulant | flocculant, What is necessary is just to adjust according to the property of to-be-processed water, However It is 0.01-10 mg / L in solid content with respect to to-be-processed water. The organic polymer flocculant is not particularly limited, and a polymer flocculant usually used in water treatment can be used. For example, poly (meth) acrylic acid, copolymers of (meth) acrylic acid and (meth) acrylamide, and anionic organic polymer flocculants such as alkali metal salts thereof, poly (meth) acrylamide, etc. Nonionic organic polymer flocculants, homopolymers composed of cationic monomers such as dimethylaminoethyl (meth) acrylate or quaternary ammonium salt thereof, dimethylaminopropyl (meth) acrylamide or quaternary ammonium salt thereof, and the like Examples thereof include cationic organic polymer flocculants such as a copolymer of a cationic monomer and a nonionic monomer copolymerizable. Moreover, there is no limitation in particular also in the addition amount of an organic type polymer flocculant, and what is necessary is just to adjust according to the property of treated water, but it is 0.01-10 mg / L in solid content with respect to to-be-treated water in general. .

  Examples of the membrane separation treatment include a microfiltration membrane (MF membrane), an ultrafiltration membrane (UF membrane), a nanofiltration membrane (NF membrane), or a reverse osmosis membrane (RO membrane). Here, for example, when performing a membrane separation process as a solid-liquid separation process, industrial water, city water, river water, lake water, well water, etc., which are treated water, are usually humic acid, fulvic acid organic matter, algae, etc. Contains membrane contaminants such as sugar and other biological metabolites, and synthetic chemicals such as surfactants. Therefore, when membrane separation treatment is performed, membrane contaminants adsorb to the membrane surface and membrane separation performance deteriorates. There is a problem that it ends up. In the present invention, since the swellable polymer particles are added before the membrane separation treatment, the membrane separation treatment is performed after membrane contaminants are adsorbed and aggregated on the particles. Therefore, water with low dissolved organic matter concentration of membrane pollutants such as biological metabolites can be membrane-separated, so that adsorption of membrane pollutants to the membrane can be reduced, degradation of membrane separation performance can be suppressed, and continued Thus, clear treated water can be obtained.

  These solid-liquid separation treatments may be used alone or in one or more stages, and may be combined with various solid-liquid separation treatments such as membrane separation treatment after precipitation treatment, sand filtration treatment or pressure flotation treatment. .

  Moreover, you may have further deionization processes, such as an ion exchange process, after a membrane separation process. Thereby, pure water or ultrapure water can be obtained. And you may further perform the refinement | purification processes of to-be-processed water, such as a decarboxylation process and an activated carbon process.

  Moreover, you may add a coagulant | flocculant, a disinfectant, a deodorant, an antifoamer, an anticorrosive, etc. as needed. Furthermore, you may use ultraviolet irradiation, ozone treatment, biological treatment, etc. together as needed.

  As described above, according to the water treatment method of the present invention, after adding an agglomeration aid to the water to be treated, solid particles are added after particles made of a cationic polymer that swells in water and does not substantially dissolve in water. By performing liquid separation treatment, water to be treated having low turbidity can be treated, and clear water can be obtained without contaminating the wall surface of the coagulation tank.

  An example of a water treatment apparatus using this water treatment method is shown in the schematic system diagram of FIG. As shown in FIG. 1, the water treatment apparatus 1 includes water to be treated introduction means 10 such as a pump for introducing water to be treated (raw water), and a first flocculation tank 11 and a second flocculation tank 12 in order from the raw water side. A flocculating tank 13, a flocculating aid introducing means 15 including a pump for introducing the flocculating aid from the flocculating auxiliary tank 14 in which the flocculating auxiliary is held into the first flocculating tank 11, and swellable polymer particles are held. The swellable polymer particle introduction means 17 comprising a pump or the like for introducing the swellable polymer particles into the second agglomeration tank 12 from the swellable polymer particle tank 16 and the water to be treated in which the turbid matter is agglomerated in the agglomeration tank 13 are discharged. And discharging means 18. The agglomeration tank 13 is provided with an agitator 19 for agitating the water to be treated in the first agglomeration tank 11 and an agitator 20 for agitating the water to be treated in the second agglomeration tank 12. Further, on the downstream side of the coagulation tank 13, a pressure levitation device 21, a sand filtration device 22, and a membrane separation processing device 23 having an MF membrane are provided in this order.

  In such a water treatment apparatus 1, treated water (raw water) such as industrial water, city water, river water, lake water, and well water is first introduced into the first coagulation tank 11. Then, the coagulation assistant held in the coagulation assistant tank 14 is introduced into the first coagulation tank 11 by the coagulation assistant introduction means 15 and added to the water to be treated, and the water to be treated is stirred by the stirrer 19. The Next, the water to be treated is introduced into the second flocculation tank 12. The swellable polymer particles held in the swellable polymer particle tank 16 are introduced into the second agglomeration tank 12 by the swellable polymer particle introduction means 17 and added to the water to be treated. Is stirred by. As a result, turbidity and membrane contaminants contained in the water to be treated are adsorbed and aggregated on the swellable polymer particles to form aggregates. Next, the water to be treated on which the aggregates are formed is discharged from the reaction tank 13 by the discharge means 18, and is solid-liquid by the pressure flotation device 21, the sand filtration device 22, and the membrane separation treatment device 23 having an MF membrane. Separation is performed to remove aggregates, and clear treated water is obtained.

  In the present invention, since the swellable polymer particles are added after adding the coagulation aid, contamination in the system of the water treatment apparatus 1 such as the wall surface of the second coagulation tank 12 can be suppressed, and Can be sufficiently agglomerated, so that clear treated water can be obtained. Furthermore, in the water treatment apparatus shown in FIG. 1, since membrane separation treatment is performed after the swellable polymer particles are aggregated, the membrane separation treatment is reduced, so that the adsorption of the membrane contaminants to the membrane surface is reduced and the membrane separation performance is deteriorated. It is possible to suppress and continue to obtain clear treated water.

  In addition, in the water treatment apparatus shown in FIG. 1, although it was set as the 2 tank structure which consists of the 1st coagulation tank 11 and the 2nd coagulation tank 12, it is good also as a structure which stirs one or both coagulation tanks in piping. Moreover, although the MF membrane is shown as the membrane separation processing device 23, a UF membrane, an RO membrane, an NF membrane, or the like may be used.

  EXAMPLES Hereinafter, although this invention is explained in full detail based on an Example and a comparative example, this invention is not limited at all by this Example.

Example 1
Contains humic substances and biological metabolites, has a turbidity of 1.2 to 4.8 degrees according to a transmitted light measurement method using a kaolin standard solution, and an absorbance at a wavelength of 260 nm (E260: organic substance concentration index) of 0.187 to Membrane separation treatment apparatus having industrial water fluctuating at 0.345 as treated water (raw water) and having a coagulation tank, pressurized flotation device, sand filtration device, and MF membrane (0.45 μm, made of cellulose acetate) shown in FIG. A kaolin (Kishida Chemical Co., 300 mesh (100%)) is added to the first coagulation tank, and swellable polymer particles (Akogel C, Mitsui Cytec Co., Ltd.) are added to the second coagulation tank. Water treatment was performed for 1 month. Kaolin is added in such an amount that the turbidity of the water to be treated in the first flocculation tank becomes 5 ° C., and Acogel C is 4 mg / L with respect to the water to be treated in the second flocculation tank. Was added.

  During one month after water treatment, the TOC concentration and turbidity were determined for the water to be treated after sand filtration, and the MFF value was determined for the water to be treated after being treated with the MF membrane. The results are shown in Table 1. The TOC concentration was determined by a wet oxidation infrared absorption method, and the turbidity was determined by a transmitted light measurement method using a kaolin standard solution. The MFF value is determined by using a Buchner funnel with an outer diameter of 40 mm and an upper height of 100 mm and a membrane filter (Millipore) with a diameter of 47 mm and a fine hole of 0.45 μm. After filtration in a state filled with water, the time T1 (second) until the filtration amount reaches 500 ml and the time T2 (second) until the filtration amount reaches 1,000 ml are measured. From the following [Equation 1] Asked. In addition, it shows that the to-be-processed water measured is clear, so that a MFF value is small. Furthermore, the wall surface in the water treatment apparatus after performing water treatment for one month was observed visually.

(Example 2)
In place of kaolin, industrial polyaluminum chloride (PAC) was used, and the same operation as in Example 1 was performed except that 30 mg / L of PAC was added to the water to be treated in the first coagulation tank. went.

(Comparative Example 1)
The same operation as in Example 1 was performed except that kaolin was not added.

As a result, in Example 1 and Example 2, swellable polymer particles did not adhere in the water treatment apparatus such as the wall surface of the second flocculation tank, and the second flocculation tank was not contaminated.
Moreover, in Example 1 and Example 2, the TOC density | concentration and turbidity of the to-be-processed water after sand filtration were able to be maintained at the low value. Therefore, it was confirmed that the turbid agglomeration continued to be satisfactorily performed by the swellable polymer particles.
Furthermore, in Example 1 and Example 2, it was confirmed that the MFF value of the water to be treated after the MF membrane treatment could be maintained at a low value, and that clear treated water was continuously obtained reliably. . Note that the MF membrane was not contaminated even after one month of water flow.

  On the other hand, in Comparative Example 1 in which the flocculating aid was not added before the swellable polymer particles were added, the swellable polymer particles adhered to the wall surface of the second flocculation tank. In addition, the TOC concentration and turbidity of the water to be treated after sand filtration and the MFF value of the water to be treated after MF membrane treatment were sometimes higher than those in Example 1 and Example 2. Therefore, when the swellable polymer particles adhere to the wall surface of the coagulation tank, turbidity aggregation may be insufficient, and it is not possible to continuously obtain a clear water as the treated water after the MF membrane treatment. It was. The MF membrane was also contaminated.

It is a schematic system diagram which shows an example of the water treatment apparatus using the water treatment method of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water treatment apparatus 10 To-be-processed water introduction means 11 1st coagulation tank 12 2nd coagulation tank 13 coagulation tank 14 aggregation auxiliary agent tank 15 aggregation auxiliary agent introduction means 16 swelling polymer particle tank 17 swelling polymer particle introduction means 18 discharge means 19, 20 Stirrer 21 Pressure floatation device 22 Sand filtration device 23 Membrane separation treatment device

Claims (3)

A coagulation aid adding step for adding a coagulation aid to the water to be treated, and a functional group such as primary amine, secondary amine, tertiary amine and their acid salts, quaternary ammonium groups after the coagulation aid addition step Is a copolymer of a cationic monomer having a crosslinking agent and a crosslinking agent monomer, and swells to a particle size of 10 to 200 times in water with respect to the particle size when not swollen and does not substantially dissolve in water A polymer particle adding step for adding particles made of a polymer, a stirring step for stirring water to be treated after the polymer particle adding step, and a solid-liquid separation processing step for solid-liquid separating the water to be treated after the stirring step. A water treatment method comprising:   The water treatment method according to claim 1, wherein the turbidity of the water to be treated before adding the coagulation aid is less than 5 degrees.   The water treatment method according to claim 1 or 2, wherein the coagulation aid is an inorganic coagulant.

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