JP2013052338A - Water treating device and water treating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treating device and a water treating method capable of further enhancing water treating deficiency and economical efficiency while securing mechanical strengths and water permeability.SOLUTION: The water treating device has a membrane module 1 using a hollow fiber membrane 2 by a single main constituting material having a self-standing structure in which an outer diameter is 3.5 mm to 10 mm and an SDR value being a ratio of the outer diameter to the wall thickness is 5.8 to 34, and the water treating method includes carrying out water treatment by total filtration and backwash alternately using the same.

Description

  The present invention relates to a water treatment device and a water treatment method, and more particularly to a water treatment device including a membrane module using a so-called single-material large-diameter hollow fiber membrane and a water treatment method using the same.

Conventionally, hollow fiber membranes have been used for water purification, for example, clarification of river water and groundwater, clarification of industrial water, drainage and sewage treatment, pretreatment for seawater desalination, and the like.
Such a hollow fiber membrane is usually used as a separation membrane in a water treatment apparatus. For example, polysulfone (PS), polyvinylidene fluoride (PVDF), polyethylene (PE), cellulose acetate (CA) , Polyacrylonitrile (PAN), polyvinyl alcohol (PVA), and polyimide (PI).

In general, the performance required for hollow fiber membranes includes excellent water permeability, excellent physical strength, stability against various chemical substances in addition to the desired separation characteristics (that is, chemical resistance) ) Is high, the attached dirt can be easily removed, or the dirt is difficult to adhere during filtration (that is, the stain resistance is excellent).
In particular, in a situation where it is required to constantly supply a large amount of safe water, various components contained in the water to be treated are separated by a membrane in a large amount more efficiently and economically. It is necessary to supply water.
For this purpose, for example, cleaning with a chemical solution is performed at predetermined intervals (for example, Patent Document 1).
However, cleaning with a chemical solution requires a relatively long time, and in order to circulate the chemical solution in the membrane at a high speed, a large amount of the chemical solution is required, and the water treatment operation during that time must be stopped. There is. Moreover, the cost of the chemical | medical agent to be used, the processing cost of waste chemicals, etc. generate | occur | produce and an operating cost increases.

Further, in recent wastewater treatment, an internal pressure type (external tank type) MBR in which biologically treated water is allowed to flow inside a hollow fiber membrane provided in the biologically treated water tank and filtration by an internal pressure is proposed.
In the water treatment membrane module used in these internal pressure MBRs, the inner diameter is about 5 to 10 mm so as not to cause clogging due to solid content accumulation on the end face of the membrane module due to biologically treated water containing various solid contents. Tubular water treatment membranes are used.
However, the treatment with the tubular membrane requires a strong support or an increase in the film thickness because the resistance to the internal pressure during the treatment decreases as the inner diameter of the water treatment membrane increases. On the other hand, when dirt such as turbidity components accumulates on the membrane surface, it is usually back-pressure washed (backwashed) in the hollow fiber membrane when the treatment amount is reduced. In the tubular membrane, breakage due to peeling of the tubular membrane itself attached to the support tends to occur. In particular, backwashing is virtually impossible with a tubular membrane of an internal pressure type total filtration system suitable for water treatment containing highly suspended substances. Therefore, the current situation is that the use of a sponge ball and the maintenance of a high internal flow rate in order to prevent a decrease in the water permeation amount by a method other than back washing necessitates a complicated system and an increase in energy consumption.
Moreover, when the film thickness of a water treatment film | membrane is increased, the new subject that the installation area efficiency with respect to the amount of treated water will fall will be caused.

JP 2006-102634 A

  The present invention has been made in view of the above problems, and provides a water treatment apparatus and a water treatment method that can further improve water treatment efficiency and economy while ensuring mechanical strength, water permeability, and the like. Objective.

The water treatment apparatus of the present invention is a hollow fiber membrane made of a single main constituent material having a self-standing structure having an outer diameter of 3.6 mm to 10 mm and an SDR value of 5.8 to 34 which is a ratio of the outer diameter to the wall thickness. The membrane module used is provided.
In such a water treatment device,
The hollow fiber membrane is preferably made of a vinyl chloride resin.

Moreover, the water treatment method of this invention uses the water treatment apparatus mentioned above, (1) The water treatment by total filtration and backwashing are performed alternately, or (2) The water treatment by total filtration and flushing are performed. It is performed alternately, and backwashing is performed at regular or random timing.
In such a water treatment method,
It is preferable to perform draining or flushing after or during the water treatment by the total filtration and backwashing.
It is preferable to introduce bubbles or ultrasonic waves in the water treatment, back washing or flushing.
As pretreatment for the water treatment, it is preferable to subject the water to be treated to total filtration without turbidity.
It is preferable to use a chemical solution during the backwashing.

  According to the present invention, since it is a single material, it performs backwashing at a high pressure, which is impossible with a large-diameter membrane made of a composite material or can only be performed at a low pressure, while ensuring mechanical strength and water permeability. Therefore, it is possible to provide a water treatment apparatus and a water treatment method that can ensure high water treatment efficiency and economy.

It is a schematic sectional drawing of the membrane module used by this invention. It is a conceptual diagram of the water treatment apparatus of this invention. It is the schematic for demonstrating the manufacturing method of the hollow fiber membrane of the membrane module used by this invention. It is the schematic for demonstrating the discharge angle of the resin solution at the time of manufacturing the hollow fiber membrane of the membrane module used by this invention.

(Hollow fiber membrane)
The hollow fiber membrane used in the water treatment apparatus of the present invention is a membrane formed of a single main constituent material having a self-supporting structure.
Here, the single main constituent material means that the main material is a single material. A single material means that there is only one main material. That is, in the material forming the hollow fiber membrane (for example, the resin constituting the membrane), one type of resin is 50% by mass or more (preferably 60% by mass or more, more preferably 70% by mass or more, 80% by mass or more, More preferably, it occupies 85% by mass or more), or the property of one kind of resin dominates the property of the constituent material. Specifically, it means a material in which one kind of resin has 50 to 99% by mass. However, the single material does not include the material itself to be described later or an additive usually used in the production of the hollow fiber membrane, and does not include an additive to be described later for improving the processability of the resin. It may be.

  Usually, a material with low strength can maintain a desired shape, for example, a cylindrical shape, a tube shape, etc., unless it is a composite with a support made of a material with higher strength (ceramic, nonwoven fabric, etc.). Can not. Therefore, the conventional hollow fiber membrane having a relatively large diameter has a cylindrical ceramic structure as a structure supporting the membrane so that it can maintain a desired shape when used as a water treatment membrane in addition to the material forming the membrane. Or the nonwoven fabric etc. which were shape | molded by the cylinder shape were accompanied.

  On the other hand, the hollow fiber membrane used in the present invention is not accompanied by a support formed from different materials / materials (for example, non-woven fabric, paper, metal, ceramic, etc.) that does not change a desired shape such as a cylindrical shape. . In other words, the hollow fiber membrane used in the present invention means a membrane formed with a single layer structure of a single main constituent material, and does not take a laminated structure with different materials / materials. Nevertheless, even such a structure has sufficient strength to maintain a desired shape such as a cylinder or tube when used as a hollow fiber membrane, that is, has a “self-supporting structure”. doing. Therefore, it can be used as a large-diameter membrane without a support. For this reason, even at the time of backwashing described later, the membrane part responsible for the filtration function does not peel off from the support, and unlike a tube-shaped film using a support such as ceramic, excellent water permeability Can be secured.

  Such single main constituent materials include polysulfone (PS), polyvinylidene fluoride (PVDF), polyolefins such as polyethylene (PE), cellulose acetate (CA), polyacrylonitrile (PAN), poly Various polymer materials such as ether sulfone, polyvinyl alcohol (PVA), and polyimide (PI) can be used, and a vinyl chloride resin is preferable. As these materials, any materials such as those commercially available and those obtained by polymerization from various monomers by a known method can be used.

  As described above, the hollow fiber membrane used in the present invention has high mechanical strength regardless of which material is used. For example, in a single layer structure in which the hollow fiber membrane is made of a single material of vinyl chloride resin, the mechanical strength is high with a breaking strength of about 10 to 100 N / piece and a breaking elongation of about 10 to 100%. The strength and elongation are, for example, values measured according to the measurement method of JISK6301 at a chuck distance of 50 mm and a pulling speed of 200 mm / min.

Examples of vinyl chloride resins include vinyl chloride homopolymer (vinyl chloride homopolymer), a copolymer of a monomer having an unsaturated bond copolymerizable with vinyl chloride monomer and vinyl chloride monomer, and vinyl chloride monomer in the polymer. Examples thereof include graft copolymers obtained by graft copolymerization, and (co) polymers composed of chlorinated vinyl chloride monomer units. These may be used alone or in combination of two or more. In particular, it is preferable that a hydrophilic monomer is copolymerized in order to improve stain resistance.
Chlorination of the vinyl chloride monomer unit may be performed before polymerization or may be performed after polymerization. In the case of a vinyl chloride copolymer, the content of monomer units other than vinyl chloride monomer units is within a range that does not impair the original performance, and the units derived from vinyl chloride monomer are 50% by weight or more and 60% by weight. % Or more or 70% by weight or more, for example, about 50 to 99% by mass, 60 to 99% by mass or 70 to 99% by mass is preferable (in the mass calculation here, the vinyl chloride resin contains a plasticizer. And other polymers blended with the copolymer resin).

  Examples of the monomer having an unsaturated bond copolymerizable with the vinyl chloride monomer include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl (meth) ) Acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, neopentyl (meth) acrylate, cyclopentyl (meth) acrylate, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate , N-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate , Tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, phenyl (meth) acrylate, toluyl (meth) acrylate, xylyl (meth) acrylate, benzyl (meth) acrylate , (Meth) acrylic acid such as 2-ethoxyethyl (meth) acrylate, 2-butoxy (meth) acrylate, 2-phenoxy (meth) acrylate, 3-methoxypropyl (meth) acrylate, 3-ethoxypropyl (meth) acrylate Derivatives; α-olefins such as ethylene, propylene, butylene; vinyl esters such as vinyl acetate and vinyl propionate; vinyl ethers such as butyl vinyl ether and cetyl vinyl ether; styrene, α-methyls Aromatic vinyls such as len; halogenated vinyl vinyls such as vinylidene chloride and vinylidene fluoride; N-substituted maleimides such as N-phenylmaleimide and N-cyclohexylmaleimide, (meth) acrylic acid, maleic anhydride, acrylonitrile, etc. Is mentioned. These may be used alone or in combination of two or more. For example, it is suitable to copolymerize or blend vinyl acetate, acrylate ester, ethylene, propylene, and vinylidene fluoride in order to impart further flexibility, stain resistance, and chemical resistance.

  The polymer to be graft-copolymerized to vinyl chloride is not particularly limited as long as it can be graft-polymerized to vinyl chloride. For example, ethylene-vinyl acetate copolymer, ethylene-vinyl acetate-carbon monoxide copolymer Polymer, ethylene-ethyl acrylate copolymer, ethylene-butyl acrylate-carbon monoxide copolymer, ethylene-methyl methacrylate copolymer, ethylene-propylene copolymer, acrylonitrile-butadiene copolymer, polyurethane, chlorinated polyethylene, Examples include chlorinated polypropylene. These may be used alone or in combination of two or more.

Furthermore, a crosslinkable monomer may be used as the monomer material constituting the polymer film. Examples of crosslinkable monomers include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di ( (Meth) acrylate, 1,2-butylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerol di (meth) acrylate, glycerol tri (meth) acrylate , (Meth) acrylic acid esters of polyhydric alcohols such as trimethylolpropane tri (meth) acrylate and pentaerythritol tetra (meth) acrylate;
Acrylamides such as N-methylallylacrylamide, N-vinylacrylamide, N, N′-methylenebis (meth) acrylamide, bisacrylamide acetic acid;
Divinyl compounds such as divinylbenzene, divinyl ether, divinylethylene urea;
Polyallyl compounds such as diallyl phthalate, diallyl malate, diallylamine, triallylamine, triallyl ammonium salt, allyl etherified product of pentaerythritol, and allyl etherified product of sucrose having at least two allyl ether units in the molecule;
(Meth) acrylic acid of unsaturated alcohol such as vinyl (meth) acrylate, allyl (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl (meth) acrylate, 2-hydroxy-3-acryloyloxypropyl (meth) acrylate Examples include esters.

Examples of hydrophilic monomers include:
(1) A cationic group-containing vinyl monomer such as an amino group, an ammonium group, a pyridyl group, an imino group or a betaine structure and / or a salt thereof (hereinafter sometimes referred to as “cationic monomer”),
(2) Hydrophilic nonionic group-containing vinyl monomers such as hydroxyl groups, amide groups, ester structures and ether structures (hereinafter sometimes referred to as “nonionic monomers”),
(3) Anionic group-containing vinyl monomers such as carboxyl groups, sulfonic acid groups, and phosphoric acid groups and / or their salts (hereinafter sometimes referred to as “anionic monomers”)
(4) Other monomers may be mentioned.

In particular,
(1) As cationic monomers, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dipropylaminoethyl (meth) acrylate, diisopropylaminoethyl (meth) acrylate, dibutylaminoethyl (meth) acrylate, diisobutyl Aminoethyl (meth) acrylate, di-t-butylaminoethyl (meth) acrylate, dimethylaminopropyl (meth) acrylamide, diethylaminopropyl (meth) acrylamide, dipropylaminopropyl (meth) acrylamide, diisopropylaminopropyl (meth) acrylamide, Dibutylaminopropyl (meth) acrylamide, diisobutylaminopropyl (meth) acrylamide, di-t-butylaminopropyl (meth) With a dialkylamino group having a carbon number of 2-44 such as acrylamide (meth) acrylate or (meth) acrylamide;
Styrene having a total carbon number of 2 to 44 dialkylamino groups such as dimethylaminostyrene and dimethylaminomethylstyrene;
Vinylpyridines such as 2- or 4-vinylpyridine; N-vinyl heterocyclic compounds such as N-vinylimidazole;

Vinyl ethers such as aminoethyl vinyl ether and dimethylaminoethyl vinyl;
Acid neutralized products of monomers having amino groups such as alkyl halides (C1-22), benzyl halides, alkyls (C1-18) or aryl (C6-24) sulfones Quaternized with acid or dialkyl sulfate (total carbon number 2 to 8) etc .;

Diallyl-type quaternary ammonium salts such as dimethyldiallylammonium chloride and diethyldiallylammonium chloride, N- (3-sulfopropyl) -N- (meth) acryloyloxyethyl-N, N-dimethylammonium betaine, N- (3-sulfo Propyl) -N- (meth) acryloylamidopropyl-N, N-dimethylammonium betaine, N- (3-carboxymethyl) -N- (meth) acryloylamidopropyl-N, N-dimethylammonium betaine, N-carboxymethyl Examples include monomers such as vinyl monomers having a betaine structure such as -N- (meth) acryloyloxyethyl-N, N-dimethylammonium betaine.
Among these cationic groups, amino group and ammonium group-containing monomers are preferable.

(2) As the nonionic monomer, vinyl alcohol;
(Meth) acrylic acid ester or (meth) acrylamide having a hydroxyalkyl group (1 to 8 carbon atoms) such as N-hydroxypropyl (meth) acrylamide, hydroxyethyl (meth) acrylate, N-hydroxypropyl (meth) acrylamide;
(Meth) acrylic acid esters of polyhydric alcohols such as polyethylene glycol (meth) acrylate (degree of polymerization of ethylene glycol 1-30);
(Meth) acrylamide;
Alkyl (carbon number: 1) such as N-methyl (meth) acrylamide, Nn-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N-isobutyl (meth) acrylamide ~ 8) (meth) acrylamide;
Dialkyl (total carbon number 2 to 8) (meth) acrylamide such as N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethylacrylamide, N, N-diethylacrylamide;
Diacetone (meth) acrylamide; N-vinyl cyclic amides such as N-vinylpyrrolidone;
(Meth) acrylic acid ester having an alkyl (C 1-8) group such as methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate;
Examples include (meth) acrylamide having a cyclic amide group such as N- (meth) acryloylmorpholine.
Especially, the (meth) acrylic acid ester which has vinyl alcohol, a (meth) acrylamide type monomer, said hydroxyalkyl (C1-C8) group, and (meth) acrylic acid ester of said polyhydric alcohol are preferable.

(3) Examples of the anionic monomer include a carboxylic acid monomer having a polymerizable unsaturated group such as (meth) acrylic acid, maleic acid, and itaconic acid and / or an acid anhydride thereof (two or more in one monomer). When having a carboxyl group);
A sulfonic acid monomer having a polymerizable unsaturated group such as styrene sulfonic acid, 2- (meth) acrylamide-2-alkyl (1 to 4 carbon atoms) propanesulfonic acid;
Examples thereof include a phosphoric acid monomer having a polymerizable unsaturated group such as vinylphosphonic acid and (meth) acryloyloxyalkyl (carbon number 1 to 4) phosphoric acid.
The anionic group may be neutralized with a basic substance to an arbitrary degree of neutralization. In this case, all anionic groups in the polymer or some anionic groups thereof form a salt. Here, as a cation in the salt, ammonium ions, trialkylammonium ions having 3 to 54 total carbon atoms (for example, trimethylammonium ions and triethylammonium ions), hydroxyalkylammonium ions having 2 to 4 carbon atoms, and total carbon numbers. Examples include 4 to 8 dihydroxyalkylammonium ions, trihydroxyalkylammonium ions having 6 to 12 carbon atoms in total, alkali metal ions, alkaline earth metal ions, and the like.
Neutralization may be performed by neutralizing the monomer or neutralizing the polymer.

  (4) A monomer having an active site capable of hydrogen bonding, such as N-vinyl-2-pyrrolidone, hydroxyethyl methacrylate, and hydroxyethyl acrylate, other than the vinyl monomer described above.

In the vinyl chloride resin, additives such as a lubricant, a heat stabilizer, and a film-forming auxiliary are used for the purpose of improving the moldability and heat stability during film formation within the range not impairing the effects of the present invention. Etc. may be blended.
Examples of the lubricant include stearic acid and paraffin wax.
Examples of the thermal stabilizer include tin-based, lead-based, and Ca / Zn-based stabilizers that are generally used for molding a vinyl chloride resin.
Examples of the film forming aid include hydrophilic polymers such as polyethylene glycol and polyvinyl pyrrolidone having various polymerization degrees.

The method for producing the vinyl chloride resin is not particularly limited, and any conventionally known polymerization method can be used. Examples thereof include a bulk polymerization method, a solution polymerization method, an emulsion polymerization method, and a suspension polymerization method.
The chlorination method is not particularly limited, and methods known in the art such as JP-A-9-278826, JP-A-2006-328165, International Publication WO / 2008/62526, etc. The described method can be used. In addition, it is preferable that the chlorine content rate of vinyl chloride-type resin is 56.7-73.2%. Further, the chlorine content as the chlorinated vinyl chloride resin is suitably from 58 to 73.2%, preferably from 60 to 73.2%, more preferably from 67 to 71%. preferable.

The vinyl chloride resin preferably has a number average molecular weight of about 20,000 to 200,000. In general, when the molecular weight is extremely small, the strength of the prepared water treatment membrane is reduced, and conversely, when the molecular weight is large, the viscosity of the solution during film formation is greatly increased, which hinders the film forming operation. The number average molecular weight can be measured by, for example, a gel permeation chromatography (GPC) method.
The degree of polymerization of the vinyl chloride resin is preferably about 250 to 3000, and more preferably 500 to 1300. If the degree of polymerization is too low, the solution viscosity at the time of spinning decreases, making the film forming operation difficult, and the strength of the prepared water treatment film tends to be poor. On the other hand, if the degree of polymerization is too high, the viscosity tends to be too high, which tends to cause bubbles to remain in the formed water treatment film. The degree of polymerization here means a value measured according to JIS K 6720-2.
In order to adjust the degree of polymerization to the above range, it is preferable to appropriately adjust conditions known in the art such as reaction time and reaction temperature.

  When using a resin other than vinyl chloride resin, it is preferable to adjust the number average molecular weight, the viscosity at the time of film formation, and the like as appropriate depending on the type of resin.

  Such a hollow fiber membrane may be produced using any method known in the art, such as a thermally induced phase separation method (TIPS), a non-solvent induced phase separation method (NIPS), or a stretching method. Especially, it is preferable to manufacture by the NIPS method.

For example, when the NIPS method is used, a resin solution comprising a material (resin) constituting the film, its good solvent, and optionally an additive is prepared. The good solvent in this case is not particularly limited, and can be appropriately selected depending on the type of material (resin). Examples include dimethyl sulfoxide, N, N-dimethylformamide, tetrahydrofuran, N, N-dimethylacetamide, N-methyl-2-pyrrolidone and the like.
The concentration and viscosity of the resin solution in this case are not particularly limited, but for example, a viscosity of about 500 to 4000 mPa · s is suitable, and about 1000 to 3000 mPa · s is preferable. Thereby, the roundness of the outer shape of the hollow fiber membrane can be ensured in the spinning line, and a membrane having a uniform thickness and film thickness can be produced.
From another point of view, it is suitable to adjust the specific gravity difference with the non-solvent described later within 1.0, preferably within 0.8, and more preferably within 0.2. Thereby, it is possible to effectively prevent the film itself from floating, sinking or flattening in the coagulation tank during the film take-up.

In order to solidify the resin solution described above, a coagulation tank 30 as shown in FIG. 3 is usually used. The coagulation tank 30 is filled with a non-solvent.
In order to spin the resin solution, a spinning die having a discharge port having a concentric double nozzle shape is usually used. The spinning mold may be arranged inside or outside the coagulation tank or from outside to inside so that the spinning mold 30 can be spun. For example, a spinning die 31 having a discharge port (not shown) is disposed inside the coagulation tank 30, that is, immersed in a non-solvent. Thus, when the spinning die 31 is disposed inside the coagulation tank 30, the resin solution is directly discharged into the non-solvent without touching the air, and liquid-liquid phase separation is started quickly. A dense skin layer is not formed on the surface, resulting in a porous surface. That is, it is possible to develop an excellent water permeability due to a decrease in filtration resistance. Also in the horizontal spinning described later, according to the method of immersing the mold in the coagulation tank according to the present invention, the mold is submerged in the coagulation tank from a state in which the resin solution is discharged in advance in the air. Since the resin solution is continuously discharged, clogging associated with an increase in discharge resistance occurring at the nozzle tip at the start of spinning can be avoided.

  The discharge direction of the resin solution from the spinning mold 31 (32 in FIG. 4), that is, the direction of the resin solution discharged from the discharge port is, for example, ± 30 ° with respect to the bottom surface 30a of the coagulation tank 30 (in FIG. 33) is preferably adjusted so as to be within the range. In other words, the discharge direction is preferably adjusted so that the resin solution is discharged within ± 30 ° with respect to the ground. Especially, it is more preferable to adjust so that it may discharge in the horizontal or substantially horizontal (about +/- 5 degree) with respect to the coagulation tank 30a or the ground.

The non-solvent filled in the coagulation tank can be appropriately selected depending on the type of the resin solution described above. For example, a non-solvent whose main component is water is preferable.
Since the non-solvent in the coagulation tank is in direct contact with the resin solution, the difference between the temperature of the resin solution discharged from the discharge port (or the spinning mold) and the temperature of the non-solvent is about 100 ° C. It is preferable to be within. Thereby, it is possible to prevent clogging in the vicinity of the discharge port of the spinning die due to a rapid temperature drop of the resin solution and a sudden increase in the viscosity of the resin solution. Further, by keeping the temperature of the non-solvent constant, the phase separation behavior of the resin solution can be stably maintained, and performance such as water permeability and strength can be stably expressed.

  In general, it is preferable to take off the film during film formation in the linear direction. In the present invention, as described above, since the discharge port is held horizontally within ± 30 ° in the coagulation tank, a constant speed and a uniform load can be obtained without changing the film take-off direction after discharging the resin solution. It becomes easy to pick up while maintaining. This makes it possible to minimize the deformation of the film structure.

  The cutting after the film is taken off may be performed in the coagulation tank or outside the tank. In particular, as shown in FIG. 3, when the membrane 34 is cut outside the coagulation tank 30, the cut 35 is at a cutting position 38 higher than the position 37 of the discharge port of the spinning mold 31 in the coagulation tank 30. Preferably it is done. This prevents the flow of the internal coagulation fluid from the tip of the ejected membrane due to the siphon effect, thereby minimizing the pressure change of the internal coagulation fluid inside the membrane, and thereby starting to flatten the membrane shape. The film shape variation can be prevented, and the film shape can be stabilized. From this viewpoint, when cutting in the coagulation tank, the cutting position is not particularly limited.

Examples of the hollow fiber membrane include a membrane having an outer diameter of about 3.6 to 10 mm and a thickness of about 5.8 to 34.
The strength of the hollow fiber membrane is determined by various factors such as the material, the inner diameter, the wall thickness, the roundness, the inner structure, etc. Among them, it is effective to use the SDR value (outer diameter / wall thickness ratio). It is. That is, as a result of various experiments, it has been found that it is preferable to design the SDR value to be about 34 or less in order to achieve, for example, 0.3 MPa as the pressure resistance performance of the internal and external pressures. On the other hand, designing to reduce the SDR value leads to a decrease in membrane filtration area in the membrane module. Therefore, from the viewpoint of balancing these, the SDR is preferably about 5.8 or more.
In particular, it is preferably about 5.9 or more, about 6.0 or more, about 6.5 or more, or about 7 or more, and is about 32 or less, about 30 or less, about 35 or less, or about 20 or less. Preferably, it is about 16 or less and more preferably about 11 or less. In particular, when the outer diameter is about 5 to 7 mm, the SDR value is preferably about 4 to 16, and more preferably set to about 6.5 to 11.
In addition, although an internal diameter is determined by the outer diameter and wall thickness, about 1.6-9.4 mm is mentioned, for example, is 4.0 mm or more, about 4.5 mm or more, and about 5.0 mm or more. Moreover, Preferably it is about 20 mm or less, Furthermore, about 10 mm or less or about 8 mm or less is mentioned. In particular, an inner diameter of about 2 mm to 8 mm is suitable. In this case, a thickness of about 0.1 mm to 2 mm is suitable.

Therefore, the hollow fiber membrane used in the present invention is specifically
(1) The membrane which consists of a hollow fiber membrane which has a self-supporting structure by the substantially single main structural material whose outer diameter is 3.6-10 mm and whose SDR value is 5.8-34 is mentioned.
Especially, it is preferable that an outer diameter is about 5-7 mm and an SDR value is about 6.5-11. As a result, it is possible to secure an inner diameter that is large enough not to block the hollow fiber even when high-concentration wastewater is passed through while maintaining the strength when internal pressure and external pressure are applied to the hollow fiber membrane. It becomes.
The inner and outer diameters, thickness, etc. of the film can be measured by actual measurement using an electron micrograph or the like.

(2) A membrane comprising a hollow fiber membrane having a self-supporting structure of a substantially single main constituent material having an inner diameter of 3 to 8 mm and an SDR value of 4 to 13,
(3) A membrane made of a hollow fiber membrane having a self-supporting structure of a substantially single main constituent material having an inner diameter of 1.6 mm to 9.4 mm and a wall thickness of 0.15 mm to 2.4 mm can be mentioned.

  The hollow fiber membrane is preferably a porous membrane having a large number of micropores on its surface. The average pore diameter of the micropores can be appropriately adjusted depending on the application, that is, the type of water to be treated, which will be described later, and for example, about 0.001 to 10 μm, preferably about 0.01 to 1 μm. The size and density of the pores on the membrane surface can be adjusted as appropriate according to the above-mentioned inner diameter, thickness, characteristics to be obtained, etc. Is suitable. Therefore, the function of the water treatment membrane is achieved by the pores of such micropores, and the fractionation of the ultrafiltration membrane or the microfiltration membrane is adjusted by the size and density of the micropores, for example. Can do. In general, it is known that an ultrafiltration membrane is a membrane having a pore size of about 2 to 200 nm, and a microfiltration membrane is a membrane of about 50 nm to 10 μm.

In such a hollow fiber membrane, the amount of pure water permeated at a transmembrane pressure difference of 100 kPa is suitably about 100 L / (m ² · h) or more, about 200 L / (m ² · h) or more, and 600 L / (M ² · h) or higher, preferably 800 L / (m ² · h) or higher, more preferably 1000 L / (m ² · h) or higher.
Thus, the hollow fiber membrane used in the present invention is a hollow fiber membrane made of a single main constituent material having a self-supporting structure, but has an excellent balance between the amount of permeated water and physical strength. Therefore, it can be suitably used for an existing water treatment apparatus as a separation membrane, and suitable water treatment for the purpose of water purification, particularly water treatment of high-concentration waste water, can be performed. Moreover, backwashing can be performed effectively, and it can be applied to dead-end filtration. As a membrane module in a water treatment apparatus, it is possible to extend the life and cost.

(Membrane module)
Examples of the membrane module included in the water treatment apparatus of the present invention include a module including at least a plurality of hollow fiber membranes 2 and a cylindrical case 10 as shown in FIG.
As the hollow fiber membrane 2, except for using the hollow fiber membrane described above, the outer diameter, length, number, etc. of the hollow fiber membrane can be appropriately adjusted according to the characteristics of the membrane module to be obtained.
The cylindrical case 10 stores a plurality of hollow fiber membranes 2. The cylindrical case 10 can be made of various materials such as metals and plastics. Generally, plastic that can be easily molded and can ensure mechanical strength is used. Examples of the plastic used include acrylic resin, polystyrene resin, ABS resin, AS resin, polycarbonate resin, and vinyl chloride resin.

Preferably, a predetermined number of hollow fiber membranes 2 are bundled into a hollow fiber membrane bundle, and the hollow fiber membrane bundle is cut into a predetermined length in accordance with the cylindrical case 10 and inserted into the case. The state of the hollow fiber membrane bundle is preferably straight.
The plurality of hollow fiber membranes 2 are sealed in the case 10 at both end surfaces 10 a, 10 b side through a sealing material 11. This seal can be formed by, for example, potting by centrifugal molding. The seal material is preferably made of a material that has an initial viscosity, cures with time, and finally reaches a predetermined hardness, such as an epoxy resin or a urethane resin.

On the case side surfaces 10 a and 10 b between the seals 11, a primary side pipe port (permeation side) 12 to which a permeation side pipe line (not shown) communicating with the outer space of the hollow fiber membrane 2 is connected is arranged. . Two or more primary side pipe ports 12 may be arranged. In the case 10, a raw water supply pipe (not shown) that communicates with the inner (inside of the hollow) space of the above-described plurality of hollow fiber membranes 2 on the end surfaces (one end surface or both end surfaces) 10 a and 10 b side of the seal material 11. The secondary side pipe port (stock solution supply side) pipe port 13 is connected. In addition, the secondary side inlet port 13 normally supplies raw water only from one side when performing dead end filtration, which will be described later, and is closed when the other side is closed and performs flushing, draining, etc., which will be described later. Is done.
Such a membrane module itself has been conventionally known. For example, various modules described in JP-A-62-2140607, JP-A-6-319961, JP-A-2009-183822, etc. Can be used.

(Water treatment equipment)
In addition to the membrane module described above, the water treatment apparatus of the present invention includes a water treatment tank 3, a raw water supply pump 4, a gas supply apparatus 7, a permeate tank 6, and a backwash pump 5 as shown in the schematic diagram of FIG. It is preferable that at least one of pipes (not shown) for arbitrarily connecting them is provided, and in addition to / in place of these various tanks, a biological treatment tank, a flocculant treatment tank, and A coagulant injection means, a chemical solution tank and / or a chemical solution injection means, a concentrated water tank, an on-off valve, an ultrasonic generator, and the like may be provided. However, it is not always necessary to use a turbidity removal device such as sand filtration, thread-wound filter, strainer, etc., which has been necessary for conventional seawater desalination, etc., from the viewpoint that the water to be treated is directly introduced into the membrane module described above and subjected to water treatment. Is preferably not provided with a turbidity eliminating device or a similar device. That is, when seawater treatment is performed using a conventional hollow fiber membrane having a relatively small diameter, the hollow fiber membrane is immediately clogged, and thus turbidity is required as a pretreatment. On the other hand, since a large-diameter hollow fiber membrane used in the present invention is not easily clogged, a turbidity treatment is not always necessary.
In addition, you may use the apparatus which can perform filtration and backflow washing | cleaning using a water level difference, an air pressure, etc., without using the raw | natural water supply pump 4 and / or the backwash pump 5. FIG. Furthermore, the raw water supply pump 4 and / or the backwash pump 5 can be used as a chemical solution injection pump.

  The water-treated tank is a tank for storing raw water, and a pipe equipped with a pump for supplying the raw water to the membrane module is connected to the tank. Here, raw water refers to wastewater containing activated sludge at sewage treatment plants, urban sewage such as household wastewater, wastewater from various facilities such as factory wastewater, agricultural wastewater, biologically treated water, wastewater containing suspended matter, seawater In addition, it means water to be treated by membrane separation such as well water and rivers, lakes and marshes, but in order to concentrate liquid food by membrane separation, fruit juice, milk or the like may be used. From another viewpoint, for example, a liquid having an SS (floating substance) of about 20000 or less, about 5000 or less, for example, about 10 to 4000 is given. From another point of view, the raw water is preferably raw water whose permeation flow rate does not change in a short time by constant pressure filtration or whose transmembrane pressure difference does not change in a short time by quantitative filtration. Specifically, in constant pressure filtration, it is preferable that the raw water has a permeation flux decrease of less than 20% in 30 minutes. In quantitative filtration, it is preferably raw water whose increase in transmembrane pressure is less than 20% after 30 minutes of filtration.

  The raw water supply pump is not particularly limited as long as the raw water can be fed to the membrane module. For example, a centrifugal pump, a diffuser pump, a spiral mixed flow pump, a mixed flow pump, a piston pump, a plunger pump Various pumps such as a diaphragm pump, a gear pump, a screw pump, a vane pump, a cascade pump, and a jet pump can be used. The raw water supply pump can be used as a pump for absorbing, pumping, or pumping raw water or permeated water either downstream or upstream of the membrane module. The raw water supply pump may be provided in a pipe that connects the water treatment tank and the membrane module. Using this raw water supply pump, it is possible to apply a differential pressure between the inner and outer membranes to a membrane module described later.

  The gas supply device is a device for supplying gas (preferably compressed air), and generally a blower, a compressor or the like is used, and a microbubble generating blower or the like may be used. Normally, air is supplied as the gas, but a device capable of supplying ozone or the like may be used. The gas is supplied to the membrane module as bubbles, and the bubbles can effectively wash the hollow fiber membrane in the membrane module. The size of the bubble is not particularly limited as long as it is useful for cleaning the hollow fiber membrane, and an air discharge hole of about 1 mm to several tens of mm is formed in stainless steel, ceramic, plastic, rubber or the like. It is preferable to adjust appropriately using an air diffuser or the like. Further, a means for generating so-called microbubbles (for example, about several tens μm to several hundreds μm) may be used. The gas supply device may be connected to either the upstream side (water treatment tank side) and / or the downstream side (permeate tank side) of the membrane module, but is preferably connected to the upstream side, It is more preferable that the raw water supply pump and the membrane module are connected to each other.

The hollow fiber membrane module 1 is connected downstream of the water treatment tank 3, the raw water supply pump 4 and the gas supply device 7. Only one membrane module 1 may be used, or two or more membrane modules 1 may be connected in series, in parallel, or a combination of series and parallel.
Among these, in consideration of energy efficiency, a series arrangement is preferable, and it is possible to assemble units so that the membrane surface flow rate is increased at the final stage, such as modules arranged in series, series units arranged in parallel, series units arranged in series, etc. More preferred.
A permeated water tank in which water filtered by the membrane module is accommodated is disposed downstream of the membrane module.
In the permeated water tank, in order to be able to use a part of the permeated water for backwashing, the permeated water from the hollow fiber module passes through the backwash pump 5 in a completely or partially different path from the pipe. A tube connected to the membrane module is provided.
A backwash pump is a pump used in order to supply permeated water to a membrane module at the time of backwashing, and the thing similar to what was illustrated with the raw | natural water supply pump mentioned above can be utilized.

(Water treatment method)
The water treatment method of the present invention is not particularly limited, and a method known in the art may be used according to the object, purpose, application, etc., other than using the above-described membrane module of the present invention. it can.
For example, water treatment can be performed according to the following treatment flow using the water treatment apparatus provided with the membrane module shown in FIG.

  The raw water X, that is, the water to be treated is supplied to the membrane module 1 by the raw water supply pump 4 from the water tank 3 to be treated. In the membrane module 1, for example, a certain pressure difference between the inner and outer membranes is loaded, and by using the pressure difference between the membranes, only water permeates through the hollow fiber membrane, and suspended matter (soil etc.) is captured by the hollow fiber membrane. Be collected. As a result, the permeated water A is obtained, and the obtained permeated water A is fed into the permeated water tank 6.

Such water treatment (filtration) is usually performed continuously for a predetermined time.
In the water treatment method of the present invention, the pressurization method in the membrane module may be either an internal pressure type or an external pressure type. In particular, the internal pressure type, that is, the water to be treated is supplied inside the hollow fiber membrane, A method of taking out permeated water to the outside of the thread membrane is preferable. In this case, the transmembrane pressure difference between the inside and the outside is, for example, about 10 to 300 kPa in terms of permeation pressure, and preferably about 200 kPa or less, depending on the type of processing target. By setting the transmembrane pressure difference within this range, the water permeation performance required in practice can be maintained, and a stable water permeation rate can be obtained for a long period of time. In particular, in the present invention, since the hollow fiber membrane used in the membrane module has a large diameter, it can be processed without blocking high-turbidity water. Moreover, by being able to pressurize by internal pressure filtration, high processing operation can be performed by high-pressure filtration exceeding the transmembrane pressure difference that can only be applied to a vacuum with a flat membrane.

In the water treatment method of the present invention, the membrane module 1 may be either dead-end filtration (total filtration) or cross-flow filtration, but it is preferable to perform dead-end filtration. In particular, in the present invention, since the hollow fiber membrane used in the membrane module has a large diameter, a larger amount of raw water can be processed in a shorter time than a small diameter, and the small diameter Since the hollow fiber membrane is less likely to be clogged as compared with the above, it is suitably used for dead-end filtration.
For example, dead-end filtration is performed by unidirectional discharge of the permeated water A to the permeate tank 6 without the membrane module 1 discharging the concentrate, for example, within the range of the transmembrane pressure difference, as described above. In addition, it is preferable to perform the operation while maintaining a substantially constant differential pressure (for example, about ± 20%).

In the above-described filtration, backwashing with water or air (preferably water) is performed periodically or at an arbitrary time (at random timing) in order to maintain the filtration capacity.
In the backwashing, it is preferable to send a part of the permeated water A obtained in the membrane module 1 to the membrane module 1 as backwash water B by the backwash pump 5. At this time, for example, a constant outer-intimal differential pressure is applied and backwashing is performed. The differential pressure between the outer and inner membranes is not particularly limited, and it is preferably performed at a high pressure comparable to or higher than that during the filtration operation in a short time, and more preferably at a higher pressure than during the filtration operation. For example, the backwash pressure is about 50 to 300 kPa. In particular, it is preferable to perform at about 100 kPa or more and about 150 kPa or more because the performance can be effectively recovered in a short time.
The duration and interval of backwashing are not particularly limited, and can be appropriately adjusted depending on the type of water to be treated, turbidity, and the like.

  Thus, in the water treatment method of the present invention, water treatment by total filtration and backwashing can be performed alternately. This is because a hollow fiber membrane having a single-layer structure with a high strength can be used with a single material while having a relatively large diameter (large internal diameter). This is because the counter-pressure cleaning can be performed efficiently without any problems. Thereby, it becomes possible to process high turbidity waste water with low energy.

  Backwashing is usually performed using a part of the permeated water A, but a chemical solution may be used in addition to or instead of this. For example, a method of injecting a chemical solution at a constant concentration at the time of backwashing can be mentioned. As the chemical solution, those usually used in the art can be used, and examples thereof include organic or inorganic acid or alkali aqueous solutions, surfactants and the like. By using the chemical solution for backwashing, the chemical solution can be washed in a shorter time, and the chemical solution can easily penetrate into the pores in the hollow fiber membrane by pressurization in the backwashing in a short time. Effective cleaning can be performed. Furthermore, since the pump for backwashing can be used as it is for chemical cleaning, it can be easily and simply performed without any new equipment or piping. Moreover, since the chemical solution can be easily permeated and immersed in the hollow fiber membrane by backwashing using the chemical solution, the amount of the chemical solution used can be reduced.

The alternating water treatment (filtration) and backwashing performed in the water treatment method of the present invention do not necessarily have to be performed continuously. For example, after or during water treatment or backwashing, flushing, draining, A break process may be performed.
Flushing is a process performed mainly for removing floating / adherent matters, residual foreign matters, etc. in the tank, piping and / or the membrane module, etc., without applying pressure, for example, a membrane surface flow rate of 0.1 m / s. It is preferable to carry out the above. The water used for flushing is usually treated water. The water that has passed through the membrane module 1 is returned to the water tank 3 as flushing water C again.
In addition, particles larger than the inner diameter of the hollow fiber membrane, a lump of fibers, or a rod-like substance may get caught at the end face of the membrane module and block the pipeline. This blockage at the end face of the module is opposite to the supply direction of raw water. It may be prevented by flushing.

  In the present invention, water treatment by total filtration and flushing may be alternately performed, and backwashing may be performed periodically or at random timing. Examples of the random timing here include a time when a decrease in water permeability performance is 20% during constant pressure filtration and a time when an increase in transmembrane pressure difference is 20% during quantitative filtration. Further, the backwashing is preferably performed with a fluctuation within 10%. Thereby, the frequency | count of the backwashing itself in a high voltage | pressure can be reduced, and also the lifetime of a hollow fiber membrane can be improved.

Drain is a process that mainly removes / discharges floating, adhesion, residue, concentrated liquid, etc. remaining on the treated water side of the hollow fiber membrane when water treatment is performed in the membrane module by total filtration. For example, there is a method in which the concentrated liquid or the like is naturally dropped and recovered by opening the lower part or the upper part of the membrane module while all the pumps are stopped. Alternatively, it may be a method in which backwashing is performed with the lower part or the upper part of the membrane module open at the same time, and the backwash waste water is recovered at the lower part or the upper part of the module. The recovered concentrated water or backwash waste water may be stored in a drain water tank provided separately or may be returned to the upstream side in the processing flow.
The break process means that water treatment is temporarily stopped.

In the water treatment, backwashing, and flushing described above, bubbles may be introduced using a gas supply device. The bubbles may be microbubbles. For example, total filtration → back washing → flushing, total filtration → back washing + bubbling, total filtration → back washing → flushing + bubbling, total filtration → flushing + bubbling → total filtration → ... → back washing and the like.
The bubbling time is not particularly limited, and it is preferably adjusted within a range of 1 second or more, 1 minute or more, preferably about several seconds to several minutes, and water treatment, backwashing, or flushing is not inefficient. . Further, it is preferable to appropriately adjust the bubbling time depending on the size of the bubbles.
The introduction of bubbles is, for example, a volume of about 5 or less, about 4 or less, about 2 or less, or about 1/2 or less in terms of raw water ratio (relative to the volume of raw water introduced into the membrane module when introduced into the membrane module). It is preferable to adjust appropriately in consideration of the bubble size and the like.
It should be noted that the introduction of bubbles may be performed constantly or intermittently regardless of the time of filtration or backwashing, other times, and the like.

  Furthermore, in the above-described water treatment, backwashing, and flushing, ultrasonic waves may be applied using a method known in the art using an ultrasonic generator. The ultrasonic waves in this case may be those having a frequency of about a dozen kHz to a few GHz, for example. The ultrasonic wave is preferably applied only to the membrane module, and may be applied during water treatment, backwashing, flushing, etc. or between these treatments, as in the above-described bubbling. It may be performed or may be applied intermittently.

  In the water treatment method of the present invention, as described above, since a large-diameter membrane module is used, water to be treated is directly treated without performing turbidity treatment such as sand filtration, which is necessary for conventional seawater desalination. It can be introduced into the membrane module. Here, turbidity is filtration that is coarser than filtration with a hollow fiber membrane, i.e., before filtration with a membrane module, and removes impurities (e.g., solid substances) that are coarser than those separated with a hollow fiber membrane. It means to remove. However, in some cases, the module end face may be blocked, and in this case, the blockage on the module end face can be removed by performing flushing in the direction opposite to the normal supply direction.

  In the water treatment method of the present invention, suspended particles such as sludge and valuable solids can be concentrated and accumulated inside the hollow fiber membrane by total filtration. Etc. may be used. These sludges, valuable solids, and the like can be recovered in a concentrated state inside the hollow fiber membrane, for example, in a solidified state by pellets, by draining, backwashing or flushing.

  Hereinafter, the hollow fiber membrane and the water treatment method of the present invention will be described in detail based on examples. In addition, this invention is not limited only to these Examples.

(Membrane module production)
As a chlorinated vinyl chloride resin, 25% by weight of HA31K (chlorination degree 67%, polymerization degree 800) manufactured by Sekisui Chemical Co., Ltd., and 20% by weight of polyethylene glycol 400 as a hole making aid are dissolved in dimethylacetamide. did. A porous hollow fiber membrane was obtained by submerging a mold in a coagulation tank from a state in which this solution was previously discharged in air, and continuously discharging it with a hollow fiber nozzle, and performing phase separation in a water bath ( (See FIGS. 5 and 6).
The obtained hollow fiber membrane had an outer diameter of 5.4 mm and an inner diameter of 4.8 mm.
The tensile strength at break was 33 N / piece and the tensile elongation at break was 50%.
A membrane module as shown in FIG. 1 was produced using the obtained hollow fiber membrane single yarn.
As a result of a water permeation test using pure water, it was possible to demonstrate the performance as a water treatment film without deformation of the film structure at an internal water pressure of 0.5 MPa during treatment.
In addition, the membrane structure was not deformed even under conditions of an external water pressure of 0.3 MPa during backwashing, and the performance without hindrance to washing could be exhibited.
Furthermore, the pure water permeability was 200 L / m ² · hr · atm.
In addition, as a result of conducting a water permeability test using an activated sludge having a concentration of 3000 ppm using an apparatus as shown in FIG. 2, the water pressure during the treatment was 0.5 MPa, and water treatment was not caused by sludge accumulation. The film performance was able to be demonstrated.
Furthermore, backwashing was performed with a sodium hypochlorite solution at an external water pressure of 0.3 MPa. However, the membrane structure was not deformed, and performance without hindrance to washing could be exhibited.

In this membrane module, although it is a large-diameter hollow fiber membrane, it has a mechanical strength of 0.3 MPa or more, which is sufficient as a water treatment membrane, and a water permeability of 100 L / m ² · hr · atm or more. In particular, it was found that the balance between the amount of permeated water and the tensile strength is excellent, the clogging due to the accumulation of solids is difficult to occur, the chemical resistance is excellent, and the water treatment efficiency can be further improved. .

Example: Water treatment method 1
Membrane modules were produced using hollow fiber membranes having a single layer structure made of a single main material of chlorinated vinyl chloride resin shown in Table 1 of various sizes obtained by the same method as described above. The filtration performance LMH (L / m ² · hr · atm) with pure water of this membrane module is also shown in Table 1.

被処理水における括弧内数値は、ＳＳ又はＭＬＳＳの値を示す。 Using the water treatment apparatus shown in FIG. 2 equipped with this membrane module, a series of water treatments (continuous treatment of filtration and backwashing for a predetermined time) shown in the following table are performed, and filtration performance (LMH) and energy consumption are determined. evaluated.
The results are shown in Table 2. In addition, the water treatment in Example 4 was performed in the order of total filtration → flushing → total filtration → flushing → ... → back washing → total filtration.

The numerical value in parentheses in the treated water indicates the value of SS or MLSS.

From the above results, it was confirmed that the water treatment method of the present invention can perform filtration and backwashing very efficiently, and can ensure high water treatment efficiency and economy.
On the other hand, in Comparative Examples 1 to 3, filtration could not be performed without turbidity. Moreover, in the comparative example 4, since the backwash was not performed, the high energy driving | running | working was forced and the performance was also quite low with respect to energy. In addition, the chemical cost was high. In Comparative Example 5, since a NORIT composite membrane was used, the membrane was crushed by high-pressure backwashing (around 0.2 MPa), and as a result, backwashing was not possible. Further, in the backwashing at 0.15 MPa, the membrane was blocked in a short period of time, and stable operation was not possible.

Example: Water treatment method 2
24% by weight of cellulose triacetate (CA) and 15.4% by weight of triethylene glycol as a pore making aid were dissolved in N-methyl 2-pyrrolidone. In the same manner as described above, this resin solution was continuously discharged almost horizontally by a spinning die into a coagulation tank (filled with water) and phase-separated in the coagulation tank to obtain a porous hollow fiber membrane. .
As shown in FIG. 3, the spinning direction of the membrane 34 was set to the horizontal direction, and the film 34 was drawn in the horizontal direction 36) in a straight line 10 m from the discharge port of the spinning die 31 in the coagulation tank 30 (water filling). Between about 1 m downstream thereof, the membrane 34 is lifted by about 10 cm by a roller 39 and cut at a cutting position 38 outside the coagulation tank 30 and higher than the discharge port position 37 of the spinning mold 31 in the coagulation tank 30. A hollow fiber membrane was obtained by cutting 35 with a machine (Table 3).

Further, 22% by weight of polyethersulfone (PES) and 5% by weight of polyvinyl pyrrolidone as a hole making aid were dissolved in N-methyl 2-pyrrolidone. In the same manner as described above, this resin solution was continuously discharged almost horizontally by a spinning die into a coagulation tank (filled with water) and phase-separated in the coagulation tank to obtain a porous hollow fiber membrane. .
As shown in FIG. 3, the spinning direction of the membrane 34 was set to the horizontal direction, and the film 34 was drawn in the horizontal direction 36) in a straight line 10 m from the discharge port of the spinning die 31 in the coagulation tank 30 (water filling). Between about 1 m downstream thereof, the membrane 34 is lifted by about 10 cm by a roller 39 and cut at a cutting position 38 outside the coagulation tank 30 and higher than the discharge port position 37 of the spinning mold 31 in the coagulation tank 30. The hollow fiber membrane was obtained by cutting 35 with a machine (Table 3).
A membrane module shown in FIG. 1 was produced using a hollow fiber membrane having a single layer structure of a single main material shown in Table 3.

被処理水における括弧内数値は、ＳＳ又はＭＬＳＳの値を示す。 Using the water treatment apparatus shown in FIG. 2 equipped with this membrane module, a series of water treatments (continuous treatment of filtration and backwashing for a predetermined time) shown in the following table are performed, and filtration performance (LMH) and energy consumption are determined. evaluated.
The results are shown in Table 4.

The numerical value in parentheses in the treated water indicates the value of SS or MLSS.

  The present invention is widely used as a water treatment apparatus used for water purification such as clarification of river water and groundwater, clarification of industrial water, drainage and sewage treatment, pretreatment for seawater desalination, etc. It is possible to carry out economical and efficient water treatment.

DESCRIPTION OF SYMBOLS 1 Membrane module 2 Hollow fiber membrane 3 Water tank to be treated 4 Raw water supply pump 5 Backwash pump 6 Permeated water tank 7 Air supply device 10 Case 10a, 10b End surface 11 Sealing material 12 Permeate side pipe port 13 Stock solution supply port 30 Coagulation tank 30a Bottom 31 Spinning Die 32 Discharge Direction 33 Discharge Angle 34 Film 35 Cutting 36 Horizontal Direction 37 Discharge Port Position 38 Cutting Position 39 Roller

Claims (8)

  A membrane module using a hollow fiber membrane made of a single main constituent material having a self-supporting structure having an outer diameter of 3.6 mm to 10 mm and an SDR value which is a ratio of the outer diameter to the wall thickness of 5.8 to 34; A water treatment device characterized.   The water treatment apparatus according to claim 1, wherein the hollow fiber membrane is formed of a vinyl chloride resin.   A water treatment method using the water treatment device according to claim 1 or 2, wherein water treatment by total filtration and backwashing are alternately performed.   A water treatment method using the water treatment apparatus according to claim 1 or 2, wherein water treatment by total filtration and flushing are alternately performed, and backwashing is performed regularly or at random timing.   The water treatment method according to claim 3 or 4, wherein draining or flushing is performed after or during the water treatment by total filtration and backwashing.   The water treatment method according to claim 3, wherein bubbles or ultrasonic waves are introduced in the water treatment, backwashing or flushing.   The water treatment method as described in any one of Claims 3-6 which attaches to-be-processed water to total filtration, without performing turbidity as pre-processing of the said water treatment.   The water treatment method according to any one of claims 3 to 7, wherein a chemical solution is used during the backwashing.

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