JP5630961B2 - Hollow fiber porous membrane and water treatment method - Google Patents

Description

  The present invention relates to a hollow fiber porous membrane and a water treatment method. Specifically, the present invention relates to a hollow fiber porous membrane having protrusions on the outer peripheral portion, and a method for treating water containing an inorganic substance and / or an organic substance using the hollow fiber porous film.

In recent years, porous membranes such as ultrafiltration membranes and microfiltration membranes have been used for electrodeposition paint collection, removal of fine particles from ultrapure water, production of pyrogen-free water, enzyme concentration, sterilization / clarification of fermentation broth, etc. Used in a wide range of fields such as water, sewage and wastewater treatment. In particular, hollow fiber porous membranes are widely used because they have a high membrane packing density per unit volume and can reduce the size of processing equipment.
Also, the external pressure filtration method that filters the liquid to be treated from the outer surface side to the inner surface side of the hollow fiber porous membrane is the internal pressure filtration method that filters the liquid to be treated from the inner surface side to the outer surface side of the hollow fiber porous membrane. Compared with this, it is possible to secure a large effective membrane area that can contribute to filtration, so that the amount of treated water per unit volume can be increased, and it is widely used in the treatment of water supply, sewage, and wastewater, where the demand for reducing water production costs is severe. ing.

  When various kinds of liquids to be treated are filtered using a hollow fiber porous membrane, some of the inorganic substances and / or organic substances contained in the liquid to be treated are adsorbed, blocked or deposited in the membrane pores or on the membrane surface, so-called A concentration polarization layer and a cake layer are formed. As a result, a so-called fouling phenomenon occurs, and the filtration performance of the hollow fiber porous membrane is reduced from a fraction to a few tenths compared to the permeation flux when pure water is filtered. When the filtration performance is lowered due to such a fouling phenomenon, a larger membrane area is required, and the membrane filtration equipment becomes larger, so that the construction cost and the operation cost increase, which is a big problem.

As methods for suppressing such a fouling phenomenon, Patent Documents 1 and 2 disclose methods using chemicals.
Patent Document 1 discloses a method of supplying ozone-containing water having a high oxidizing power to a semipermeable membrane, and Patent Document 2 discloses a film cleaning agent, an oxidizing agent, an acid, a basic compound, and a countercurrent cleaning water. A method of adding a drug such as a surfactant is disclosed.
Patent Document 3 discloses a method of removing fine particles adhering to the surface of the hollow fiber membrane by introducing air into the hollow fiber membrane storage container, vibrating the liquid in the container.

Furthermore, Patent Documents 4 to 7 disclose methods for suppressing the fouling phenomenon by controlling the shape of the hollow fiber membrane.
Patent Document 4 discloses a method for suppressing a fouling phenomenon by applying a meandering crimp to a hollow fiber.
Patent Documents 5 to 7 disclose a method in which protrusions are provided on the outer periphery of a hollow fiber membrane to suppress a decrease in membrane area due to contact between the hollow fibers and a decrease in processing performance due to liquid retention.

JP 57-194005 A JP-A-8-1158 JP-A-60-19002 JP 57-194007 A JP 58-169510 A Japanese Unexamined Patent Publication No. 63-21914 JP-A 48-75481

However, the fouling suppression methods using chemicals disclosed in Patent Documents 1 and 2 require a large amount of money for the purchase of chemicals and waste liquid treatment, and these chemicals cause membrane deterioration. There is a problem of shortening the service life.
Although the fouling suppression method disclosed in Patent Document 3 has a high cleaning effect, the membranes rub against each other with fine particles adhering to the membrane surface. There's a problem.
In the method of applying crimp to the hollow fiber disclosed in Patent Document 4, the flow of the liquid is controlled over the entire membrane surface because the crimp cycle in the longitudinal direction of the hollow fiber is as long as several mm to several tens mm. As a result, there is a problem that fouling is caused and a sufficient effect cannot be obtained.
In the methods disclosed in Patent Documents 5 to 7, since protrusions are mainly provided as spacers for preventing adhesion between yarns, the flow of water on the film surface cannot be sufficiently controlled, and fouling There is a problem that a sufficient effect for suppression cannot be obtained.

  The problem to be solved by the present invention is that it is suitable for processing liquids containing inorganic substances and / or organic substances at low cost, and can suppress fouling and achieve high filtration performance without damaging the membrane. It is to provide a hollow fiber porous membrane and a water treatment method.

As a result of intensive studies in order to solve the above-mentioned problems, the present inventors effectively provided fouling on the outer periphery of the hollow fiber porous membrane by providing continuous protrusions in the longitudinal direction of the hollow fiber porous membrane. The present invention has been completed by finding that it can be suppressed.
That is, the present invention is as follows.
(1) A hollow fiber porous membrane having protrusions continuous in the longitudinal direction on the outer peripheral portion.
(2) The hollow fiber porous membrane according to (1), wherein the width of the protrusion is 50 to 250 μm and the height of the protrusion is 20 to 300 μm.
(3) The hollow fiber porous membrane according to (1) or (2), wherein the number of protrusions is 8 or more and 250 or less.
(4) The hollow fiber porous membrane according to any one of (1) to (3), wherein the inner diameter is 50 to 2000 μm and the film thickness is 50 to 1000 μm.
(5) Using the hollow fiber porous membrane according to any one of (1) to (4), a liquid to be treated containing an inorganic substance and / or an organic substance is transferred from the outer surface side to the inner surface of the hollow fiber porous film. The water treatment method including the process filtered to the side.
(6) The water treatment method according to (5), further comprising a step of backwashing the hollow fiber porous membrane from the inner surface side to the outer surface side of the hollow fiber porous membrane.
(7) The water treatment method according to (5) or (6), further comprising a step of supplying air to the outer surface side of the hollow fiber porous membrane, swinging the hollow fiber porous membrane, and washing with air. .

According to the present invention, it is possible to provide a hollow fiber porous membrane that can effectively suppress fouling without damaging the membrane and enables water treatment at low cost.
Moreover, according to this invention, the water treatment method which processes the to-be-processed liquid containing an inorganic substance and / or an organic substance with low filtration and high filtration performance can be provided.

The schematic diagram of the cross section orthogonal to the film | membrane longitudinal direction of a hollow fiber porous membrane is shown. The schematic of the apparatus for evaluating the filtration performance of a hollow fiber porous membrane is shown. Filtration time of the hollow fiber porous membrane - shows a graph of measurement results of the flux holding ratio J / J _0. The graph of the measurement result of the frequency | count of backwashing of a hollow fiber porous membrane-backflow washing | cleaning recovery rate nRF is shown.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as the present embodiment) will be described in detail. In addition, this invention is not limited to the following embodiment, It can change and use variously within the range of the summary.

[Hollow fiber porous membrane]
The hollow fiber porous membrane of the present embodiment is a hollow fiber porous membrane having protrusions continuous in the longitudinal direction on the outer peripheral portion.
In the present embodiment, the “outer peripheral portion” means the outer surface portion of the hollow fiber porous membrane.
In the present embodiment, the “longitudinal direction” means a direction perpendicular to the outer circumference of the hollow fiber membrane.
In the present embodiment, “having continuous protrusions” means that the outer circumferential circular section perpendicular to the longitudinal direction of the hollow fiber membrane has a protrusion structure that is substantially the same at any point. .

The hollow fiber porous membrane of the present embodiment is a porous membrane having pores on the membrane surface.
The pore diameter is preferably 1 nm to 10 μm, more preferably 2 nm to 1 μm.
If the pore diameter is 1 nm or more, the filtration resistance of the membrane is low and sufficient water permeability is obtained, and if it is 10 μm or less, a membrane having excellent separation performance is obtained.
In the present embodiment, the pore diameter can be measured by filtering an indicator substance having a known particle diameter and setting the size of the indicator substance having a rejection rate of 90% or more as the pore diameter.
Specifically, by using monodisperse polystyrene particles as an indicator substance, it is possible to measure a film having a pore diameter of 20 to 30 nm or more, and by using a protein as an indicator substance, 20 to 20 nm. A film having a pore diameter of 30 nm or less can be measured.

The hollow fiber porous membrane of the present embodiment is a porous membrane having a hollow portion.
The inner diameter (corresponding to the hollow portion) of the hollow fiber porous membrane is preferably 50 μm to 2 mm.
If the inner diameter is 50 μm or more, it is possible to keep the pressure loss generated when filtered water flows through the hollow part low, and if it is 2 mm or less, the membrane packing density per unit volume can be increased. It can be made compact.
The film thickness of the hollow fiber porous membrane is preferably 50 μm to 1 mm.
If the film thickness is 50 μm or more, sufficient compressive strength required for the external pressure filtration hollow fiber porous membrane can be obtained, and if it is 1 mm or less, the film packing density per unit volume can be increased. It can be made compact.
The hollow fiber porous membrane of the present embodiment preferably has an inner diameter of 50 μm to 2 mm and a film thickness of 50 μm to 1 mm, an inner diameter of 100 μm to 1 mm, and a film thickness of 100 μm to 500 μm. More preferred.
In this Embodiment, the internal diameter and film thickness of a hollow fiber porous membrane can be measured by the method as described in a following example.

In the present embodiment, the porosity of the hollow fiber porous membrane is preferably 20% to 90%.
When the porosity is 20% or more, it has excellent water permeability, and when it is 90% or less, a film having practical strength characteristics can be obtained.
In this embodiment, the porosity is the difference between the wet mass and the absolutely dry mass of the hollow fiber porous membrane in which water is impregnated in the pores excluding the hollow portion, and the membrane volume excluding the hollow portion. It can be measured by dividing.

In the present embodiment, the hollow fiber porous membrane may be either a polymer membrane or an inorganic membrane, but a polymer membrane is preferred because it has a high degree of freedom in film formation and can be produced at low cost.
The polymer porous membrane can be produced by discharging a polymer from a bicyclic spinneret and then forming a porous membrane by a phase separation method, a stretch hole method, a track etching method, or the like.
For example, as a phase separation method, a polymer is dissolved in a solvent capable of dissolving the polymer, and then discharged from a bicyclic spinneret with water or a solvent as a hollow material and brought into contact with a non-solvent to perform phase separation. Induced non-solvent induced phase separation method or polymer dissolved in a latent solvent that does not dissolve at room temperature but dissolves at high temperature, discharged from a double ring spinneret with air or solvent as a hollow material, and contacted with air or water Examples of the method include a thermally induced phase separation method in which cooling is performed to induce phase separation.
In the stretch opening method and the track etching method, the polymer is melted at a high temperature, the polymer solution is discharged as a hollow material from a double ring spinneret, and then stretched or etched to open the hole. The method of making it, etc. are mentioned.

  The material of the polymer membrane is not particularly limited, and examples thereof include polysulfone, polyethersulfone, polyacrylonitrile, cellulose, cellulose acetate, polyvinylidene fluoride, polyethylene, polypropylene, polytetrafluoroethylene, polycarbonate, polyester, polystyrene, and polysulfone. Examples include methyl methacrylate.

In the present embodiment, examples of the method for providing the protrusion include a method using a spinneret having a notch formed in the outer periphery of a slit through which a polymer solution of the spinneret is discharged.
By using a spinneret with a notch, a hollow fiber porous membrane having protrusions continuously in the longitudinal direction can be produced on the outer peripheral portion of the present embodiment.

As an example of the hollow fiber porous membrane of this embodiment, as shown in FIG. 1, d is the inner diameter, t is the film thickness, h is the height of the protrusion, and w is the width of the protrusion.
In the present embodiment, the height of the protrusion means the distance from the outer peripheral portion where the protrusion of the hollow fiber porous membrane is not present to the tip of the protrusion, and the width of the protrusion is a position that is 1/2 the height of the protrusion. This means the protrusion width at.

As the width and height of the protrusion provided on the outer peripheral portion of the hollow fiber porous membrane, it is preferable that the width of the protrusion is 50 μm to 250 μm and the height of the protrusion is 20 μm to 300 μm.
If the width of the protrusion is 50 μm or more, the protrusion will not be crushed when external pressure filtration is performed, and if it is 250 μm or less, the complicated flow of fluid near the membrane surface causes It is possible to effectively suppress adhesion and deposition of inorganic substances and / or organic substances.
If the height of the protrusion is 20 μm or more, it is possible to effectively suppress the adhesion and deposition of inorganic and / or organic matter on the film surface by generating a complicated flow in the vicinity of the film surface. If it is 300 micrometers or less, since a processus | protrusion will not be crushed by filtration of an external pressure filtration system, it is preferable.
As for the width and height of the protrusion, the width of the protrusion is preferably 60 μm to 200 μm, and the height of the protrusion is more preferably 40 μm to 200 μm.
In the present embodiment, the width and height of the protrusions can be measured by the methods described in the following examples.

In the present embodiment, the number of protrusions can be appropriately selected depending on the inner diameter and film thickness of the hollow fiber porous membrane, but is preferably 8 to 250.
If the number of protrusions is 8 or more, it is possible to cause a complicated flow in the vicinity of the film surface and to prevent adhesion and deposition of inorganic and / or organic materials on the film surface, and 250 or less. If it is then, it becomes possible to form protrusions on the outer periphery of the hollow fiber porous membrane with high accuracy.
The number of protrusions is more preferably 10 to 120.

The shape of the protrusion is not particularly limited, and examples thereof include various shapes such as a convex shape and a concave shape.
Since the protrusions on the outer peripheral portion of the hollow fiber porous membrane cause a complicated flow in the vicinity of the membrane surface, it is preferably provided continuously over the entire longitudinal direction of the membrane surface.

[Water treatment method]
The water treatment method of the present embodiment includes a step of filtering a liquid to be treated containing an inorganic substance and / or an organic substance from the outer surface side to the inner surface side of the hollow fiber porous membrane using the hollow fiber porous membrane. Water treatment method.
According to the water treatment method of the present embodiment, the reason is not clear, but it is possible to effectively suppress fouling of the inorganic material and / or organic material to the membrane surface by the complicated fluid flow in the vicinity of the membrane surface. It becomes possible.
In the present embodiment, the outer surface side of the hollow fiber porous membrane means the outer peripheral portion side having the projection of the hollow fiber porous membrane, and the inner surface side means the hollow portion side of the hollow fiber porous membrane.

The hollow fiber porous membrane is usually used as a membrane module in which several hundred to several thousand bundles are bundled and both ends are bonded to a case or the like with an epoxy resin or a urethane resin.
The type of the membrane module is not particularly limited. For example, a casing type in which the entire bundle of hollow fiber porous membranes is covered with a case, and a casing-less in which both ends of the bundle of hollow fiber porous membranes are accommodated in a case or the like. Type membrane module.
The type of the membrane module is not particularly limited, and examples thereof include a cylindrical type and a rectangular type.

A liquid to be treated containing an inorganic substance and / or an organic substance (hereinafter sometimes simply referred to as a liquid to be treated), which is a treatment target of the water treatment method of the present embodiment, is a liquid to which a membrane separation method can be applied. If it is, it will not specifically limit, For example, river water, groundwater, lake water, dam water, seawater, sewage, sewage secondary treated water, various factory waste water, pool water, bathtub water, fermentation liquid, culture solution, etc. are mentioned.
The liquid to be treated contains inorganic substances and / or organic substances having various sizes, shapes and concentrations depending on the application.
In river water and the like, organic substances include, for example, low and high molecular weight humic substances, polysaccharides, proteins, and colloidal substances thereof, and inorganic substances include, for example, ionic iron, manganese, calcium, Examples thereof include magnesium, aluminum, silica, colloidal materials thereof, and fine particles such as kaolin and bentonite.
In the liquid to be treated, which is treated in the membrane separation activated sludge method that combines biological treatment and membrane separation, in addition to various inorganic and / or organic substances contained in the raw water subjected to biological treatment, as an organic substance, for example, activated sludge And various microorganisms that form, and carcasses and metabolites thereof.

In the present embodiment, a method for filtering the liquid to be processed is not particularly limited. For example, a pressure filtration method in which the liquid to be processed is pressurized with a pump or the like from the outer surface side, and the liquid to be processed is sucked from the inner surface side. Examples thereof include a suction filtration method.
When filtering, either the total filtration method for filtering the total amount of the liquid to be treated supplied to the hollow fiber porous membrane or the cross-flow filtration method for filtering a part of the liquid to be treated and circulating the remaining liquid to be treated A scheme can also be used. In addition, before the liquid to be treated is filtered through the hollow fiber porous membrane, pretreatment such as coagulation sedimentation, pressurized flotation filtration, biological treatment, and addition of a drug may be appropriately performed.

The water treatment method of the present embodiment preferably further includes a step of backwashing the hollow fiber porous membrane from the inner surface layer to the outer surface layer of the hollow fiber porous membrane.
Even when membrane filtered water or the like is passed from the inner surface side to the outer surface side of the hollow fiber porous membrane and the hollow fiber porous membrane is subjected to so-called back-flow cleaning, a complicated flow occurs in the vicinity of the membrane surface, and deposition In addition, the fouling material composed of the inorganic and / or organic matter adhered to the outer surface side starting from the protrusion on the film surface, and the fouling material composed of the deposited inorganic and / or organic matter is divided and easily peeled off from the film surface. High effect of backwashing can be obtained.

  In the present embodiment, the method for backwashing is not particularly limited, and for example, a clear liquid such as membrane filtered water is pressure filtered from the inner surface side to the outer surface side by a pump, head difference, etc. A method of discharging the washing wastewater out of the system of the filtration system can be mentioned.

The liquid used for the backflow cleaning is not particularly limited as long as it does not contaminate the hollow fiber porous membrane. Usually, membrane filtered water is used, and if necessary, a fau such as sodium hypochlorite is used. It is also possible to add chemicals that have the effect of preventing rings.
The frequency, pressure, and amount of water for backwashing can be appropriately selected depending on the intended use.

The water treatment method of the present embodiment preferably further includes a step of supplying air to the outer surface side of the hollow fiber porous membrane, oscillating the hollow fiber porous membrane, and washing with air.
When air cleaning is performed using a normal hollow fiber porous membrane, although the cleaning effect is high, many hard particles such as inorganic particles are adhered and deposited on the membrane surface. A rubbing phenomenon that crushes the pores of the surface and conversely reduces the filtration performance occurs.
When the hollow fiber porous membrane of this embodiment is air-washed, since there are few hard components such as inorganic components deposited on the membrane surface, and the fouling material on the membrane surface easily peels off from the protrusion, the membrane Even if they are rubbed with each other, the scratching phenomenon in which the film surface is crushed is also suppressed, and a high air cleaning effect can be obtained.
In the filtration process using the hollow fiber porous membrane according to the present embodiment, the complex liquid flow near the membrane surface prevents the fouling material composed of inorganic and / or organic matter from adhering to and depositing on the membrane surface even during filtration. Furthermore, even if it adheres, the fouling material is divided starting from the protruding portion, and thus easily peels off from the film surface, so that it is possible to obtain a high cleaning effect even during air cleaning while suppressing scratching. .
Further, in this embodiment, when the hollow fiber porous membrane is air-washed, a complicated flow of a mixed fluid of air and water is generated on the membrane surface, and the fouling substance is easily separated from the membrane surface.

The method of air cleaning is not particularly limited as long as it is a commonly used method. For example, if the membrane module is a casing type, air is supplied from the primary side of the membrane module directly or from any position of the piping leading to the membrane module. The method of introduce | transducing is mentioned.
In the case of a casingless type membrane module, air washing can be performed by dipping the membrane module in a dipping tank and supplying air from a pipe installed at the bottom of the membrane module or at the bottom of the dipping tank.
The frequency, pressure, and amount of air cleaning can be appropriately selected depending on the intended use. In addition to air, it is also possible to use a gas that has an effect of preventing fouling such as ozone gas.

When water treatment is performed using a hollow fiber porous membrane, fouling can be suppressed, and thus high filtration performance can be achieved. Further, since the hollow fiber porous membrane can be easily washed by the backwashing or the air washing, the water treatment method of the present embodiment can solve the problems of the prior art in suppressing fouling. it can.
According to the water treatment method of the present embodiment, the amount of the chemical used can be suppressed, so that the cost of purchasing the chemical and treating the waste liquid can be reduced, and further, the deterioration of the hollow fiber porous membrane due to the chemical can be suppressed.
In addition, since the abrasion phenomenon due to air washing is suppressed, the lifetime of the hollow fiber porous membrane is extended, and the membrane replacement frequency can be reduced.

  Hereinafter, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited only to these examples. In addition, the measuring method used for this Embodiment is as follows. The following measurements were all performed at 25 ° C.

(1) Measurement of inner diameter and film thickness (μm) The hollow fiber porous membrane was sliced thinly with a razor or the like in a direction perpendicular to the longitudinal direction of the film, and the inner diameter and film thickness of the cross section were measured using a microscope.

(2) Measurement of protrusion width and height (μm) A photograph taken at an arbitrary magnification capable of clearly confirming the shape of the protrusion on the outer peripheral portion of the hollow fiber porous membrane cross section with a scanning electron microscope was used. On the photograph, the length from the outer periphery without the protrusion to the tip of the protrusion was measured to determine the height of the protrusion. Further, at the position where the height of the protrusion was divided into two equal parts, the width of the protrusion was measured, and this was taken as the width of the protrusion.

上記式において、膜有効長とは、注射針が挿入されている部分を除いた、中空糸多孔膜の正味の膜長を指し、πは、円周率を指す。 (3) Measurement of pure water permeation flux (L / m ² / hr) FIG. 2 shows a schematic diagram of an apparatus used for evaluating the filtration performance of the hollow fiber porous membrane. A hollow fiber porous membrane 7 moistened with pure water having a length of about 10 cm was set in a tube 6 having an inner diameter of 3 mm, and both ends were sealed with silicon caps 8. Next, the injection needle 9 whose end was sealed from one silicon cap was stabbed and set in the hollow portion of the hollow fiber porous membrane. Further, the injection needle 10 having an end opened from the other silicon cap was stabbed and set in the hollow portion of the hollow fiber porous membrane. Thereafter, the pure water filled in the stock solution tank 1 is sent from the pipes 2 and 4 to the tube 6 in which the hollow fiber porous membrane 7 is set using the pump 3, and a part of the water passes through the three-way valve 14 and exits 12. Returned to stock solution tank 1. A part of the water sent to the tube 6 was filtered by the hollow fiber porous membrane 7. The amount of filtered pure water permeated from the injection needle 10 was measured, and the pure water permeation flux was determined by the following equation. At this time, the linear velocity of the water flowing through the cross section excluding the hollow fiber porous membrane 7 in the tube 6 was 0.1 m / s, and the average value of the pressure of the pressure gauges 5 and 11 was 0.1 MPa.

In the above formula, the effective membrane length refers to the net membrane length of the hollow fiber porous membrane excluding the portion where the injection needle is inserted, and π refers to the circumference.

(4) Measurement of permeation flux retention ratio J / J _{0 The same} as the pure water permeation flux of (3) above, except that the stock solution tank 1 was filled with 50 ppm of sodium alginate aqueous solution in the apparatus shown in FIG. The operation of was carried out.
Using the permeation flux J of the membrane filtration water obtained and the pure water permeation flux J ₀ obtained in the above (3), the permeation flux retention ratio J / J ₀ was calculated from the following equation.

(5) Measurement of backwashing recovery rate nRF With the apparatus shown in FIG. 2, the same operation as the pure water permeation flux in (3) above was performed except that the stock solution tank 1 was filled with 50 ppm of sodium alginate aqueous solution. Then, filtration was performed for 60 minutes, and the pump 3 was stopped. The permeation flux of the sodium alginate aqueous solution immediately before the backwashing was J _bb . Next, pure water was supplied from the injection needle 10 to the hollow portion of the hollow fiber porous membrane 7, and the backwash waste water that permeated from the inner surface side to the outer surface side was discharged out of the system from the outlet 13 of the three-way valve 14. After the backwashing, a 50 ppm sodium alginate aqueous solution was filtered again. The permeation flux of the aqueous sodium alginate solution immediately after the backwashing was taken as J _ab . Using the pure water permeation fluxes J ₀ , J _bb and J _ab , the backwashing recovery rate nRF was calculated by the following equation.

[Example 1]
20% by mass of a cellulose acetate propylate polymer having a weight average molecular weight of 65,000 and 80% by mass of triethylene glycol were stirred at 170 ° C. for 1 hour and then allowed to stand for 2 hours to obtain a uniform polymer polymer solution. Next, using this polymer solution, a bicyclic spinneret having 16 200 μm cutouts on the outer periphery of the discharge slit, and using triethylene glycol at 170 ° C. as an internal coagulating liquid, a discharge linear velocity of 0.2 m / s, It was discharged at a temperature of 170 ° C., cooled and solidified in a 50 ° C. water bath with an empty running distance of zero, and wound up at a speed of 0.2 m / s. The wound hollow fiber polymer was immersed in water to remove triethylene glycol as a solvent to obtain a hollow fiber porous membrane. The physical properties of the obtained film are shown in Table 1. Moreover, the measurement results of the permeation flux retention ratio J / J ₀ and the backflow cleaning recovery ratio nRF are shown in FIGS. 3 and 4, respectively.

[Example 2]
A hollow fiber porous membrane was obtained by the method of Example 1 except that a double ring spinneret having 64 notches of 100 μm was used on the outer periphery of the slit for discharging the polymer solution. The physical properties of the obtained film are shown in Table 1. Moreover, the measurement results of the permeation flux retention ratio J / J ₀ and the backflow cleaning recovery ratio nRF are shown in FIGS. 3 and 4, respectively.

[Comparative Example 1]
A hollow fiber porous membrane was obtained by the method of Example 1 except that a double ring spinneret having no notch in the outer periphery of the slit for discharging the polymer solution was used. The physical properties of the obtained film are shown in Table 1. Moreover, the measurement results of the permeation flux retention ratio J / J ₀ and the backflow cleaning recovery ratio nRF are shown in FIGS. 3 and 4, respectively.

Table 1 shows the characteristics of the hollow fiber porous membrane used in Examples and Comparative Examples.

From the result of FIG. 3, in Examples 1 and 2, compared with the comparative example using the hollow fiber porous membrane which does not have a protrusion, a high permeation flow rate retention rate is shown, and fouling can be effectively suppressed. Indicated.
In addition, from the results of FIGS. 3 and 4, the backwashing at a filtration time of 60 minutes showed a very high backwashing recovery rate in Examples 1 and 2, and a permeate flow rate retention rate much higher than before washing. A high cleaning effect was shown.

According to the present invention, it is possible to provide a hollow fiber porous membrane that can effectively suppress fouling without damaging the membrane and enables water treatment at low cost.
The present invention has industrial applicability in the field of water treatment.

d Inner diameter t Film thickness h Projection height w Projection width 1 Stock solution tank 2 Piping 3 Pump 4 Piping 5 Pressure gauge 6 Tube 7 Hollow fiber porous membrane 8 Silicon cap 9 Injection needle 10 whose end is sealed Injection needle 11 Pressure gauge 12 Outlet 13 Outlet 14 Three-way valve

Claims (4)

Ejecting dual-cyclic polymer solution from spinneret, then, a hollow fiber porous membrane is produced by a more porous membrane phase separation method,
The spinneret has a notch on the outer peripheral portion of a slit the polymer solution is discharged,
The hollow fiber porous membrane has protrusions continuous in the longitudinal direction on the outer periphery, the protrusion width is 60 to 100 μm, the protrusion height is 20 to 300 μm, and the number of protrusions is 16 or more and 64. It is a number less, hollow fiber inner diameter of 600～1500Myuemu, and I thickness 310~500μm der, Ru used to filter the inner surface side of the liquid to be treated from the outer surface side of the hollow fiber porous membrane Porous membrane.   The water treatment method including the process of filtering the to-be-processed liquid containing an inorganic substance and / or an organic substance from the outer surface side of the said hollow fiber porous membrane to an inner surface side using the hollow fiber porous membrane of Claim 1.   The water treatment method according to claim 2, further comprising a step of backwashing the hollow fiber porous membrane from the inner surface side to the outer surface side of the hollow fiber porous membrane.   The water treatment method according to claim 2 or 3, further comprising a step of supplying air to the outer surface side of the hollow fiber porous membrane, oscillating the hollow fiber porous membrane, and washing with air.

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