JP4433276B2 - Hollow fiber membrane filtration module and cleaning method thereof - Google Patents

Description

  The present invention relates to a hollow fiber membrane filtration module that treats water containing suspended solids such as river water, lake water, ground water, brine, seawater, etc., and removes fine particles, microorganisms, and the like contained therein. Relates to a hollow fiber membrane module having good washing performance by backwashing solid components such as suspended substances adhering to the membrane surface and hollow fiber membrane bundle, and having good discharge of solid content.

  When water containing suspended substances such as river water, lake water, ground water, brine, seawater, etc. is filtered directly or after pretreatment using a hollow fiber membrane module, the membrane-impermeable substances contained in the water gradually A phenomenon is observed in which the water permeation rate of the membrane is lowered by adhering and accumulating on the hollow fiber membrane surface and the membrane pore surface. In normal operation, when the membrane permeation performance drops below a predetermined value, that is, when the filtration flow rate drops below a predetermined value in the case of constant pressure operation, the transmembrane pressure difference exceeds a predetermined value in the case of constant flow operation. When the temperature rises to a certain point or when a certain operation time has elapsed, the membrane is washed to perform the operation of restoring the membrane water permeability.

There are various methods for cleaning the membrane. For example, in addition to back pressure cleaning performed by flowing water in reverse from the permeate side of the membrane, so-called back cleaning, back flow cleaning that supplies raw water in the outer peripheral direction from the core tube, The air washing which pushes out air from a core pipe is proposed. (For example, see Patent Document 1). However, the module structure in this case uses a so-called thread-wound cartridge type element in which a hollow fiber membrane is wound around the core tube part, and the yarn is not bound in the module in which the hollow fiber membranes are arranged in parallel. In addition, there was a problem that the yarn was damaged during backwashing and air washing. In addition, a method of performing air cleaning from the core tube simultaneously with backwashing is disclosed (for example, see Patent Document 2), but this also uses a thread-wound cartridge type element, and the same problem as in Patent Document 1 There is. On the other hand, with only normal backwashing, the amount of water flowing on the surface of the hollow fiber membrane is small, and the ability to completely drain the solid component peeled off from the membrane is low. There was a problem of sticking to the surface. For this reason, a method of extruding the outside of the membrane with water and compressed air as described above can also be taken, but in order to suppress damage to the yarn, the reverse flow rate is suppressed, and further, water and compressed air are supplied from one direction. For this reason, there is a problem that the flow rate of the washing water becomes slow on the membrane surface far from the supply port, and the dirt cannot be removed efficiently. This is more conspicuous as the size of the module increases, and the membrane located far from the cleaning water or air supply port has a longer flow rate, resulting in insufficient flow of backwash water, and deposits on the membrane surface. There are problems that the removal becomes insufficient and the solid matter discharged from the upstream accumulates.
JP 2000-79390 A (pages 2 to 4) JP 2002-239350 A (pages 2 to 3)

On the other hand, a module structure has been proposed in which a raw water supply port and an aeration air supply port are provided at the sealed end. (For example, see Patent Document 3). In this case, since the raw water supply port provided at the sealing end is not used for drainage in the reverse direction, there is a disadvantage that the solid matter accumulated at the bottom of the module is difficult to escape.
JP-A-9-220446 (pages 2 to 4)

  The object of the present invention is to solve such problems of the prior art, and the surface of the hollow fiber membrane can be efficiently washed, and solid components such as turbidity separated from the membrane surface by washing can be removed. It is an object of the present invention to provide a module that can be efficiently discharged from a container and a cleaning method thereof.

  The inventors of the present invention have arrived at the present invention as a result of intensive studies to overcome the above problems. That is, a core tube that is parallel to the hollow fiber membrane is provided at the center of the module container, and a hollow fiber membrane is arranged around the core tube to constitute a membrane module, which is arranged in the longitudinal direction when used. The core tube has a stopper plug near the lower part, and several holes are provided on the side surface of the core tube. By supplying compressed air to the filtration chamber for cleaning from the hole below the stopper plug, the hollow fiber membrane is shaken, and the turbid components on the membrane surface are peeled off with the force of rising bubbles, and air scrubbing is performed. More efficient cleaning. Moreover, the module structure which discharged | emitted the turbid component which peeled off efficiently was discharged | emitted by discharging | emitting outside the module from the hole of the upper side of a core pipe with water and compressed air. Further, it has been found that by providing a partition plate in the core tube, the effect of regulating the flow path of bubbles and shaking the hollow fiber membrane is improved.

  By using the module of the present invention, the hollow fiber membrane surface can be efficiently washed, and solid components such as turbidity separated from the membrane surface by washing can be efficiently discharged from the container, so that the lifetime of the membrane can be extended, Water purification that is stable for a long time is possible.

  Hereinafter, the present invention will be described in detail.

  The core tube in the present invention is a tubular member having a function of distributing the fluid supplied from the supply fluid inlet to the hollow fiber membrane assemblies. A suitable example is a perforated tube. The core tube is preferably located in the center of the aggregate of hollow fiber membranes. If the diameter of the core tube is too large, the proportion of the hollow fiber membrane in the membrane filtration module is reduced, and as a result, the membrane area of the membrane filtration module is reduced, so that the throughput may be reduced. On the other hand, if the diameter of the core tube is too small, the pressure loss increases when the supply fluid flows in the core tube, and as a result, the effective differential pressure applied to the hollow fiber membrane decreases and the separation efficiency may decrease. In addition, the core tube may be damaged due to the strength of the hollow fiber membrane that is reduced when the supply fluid flows through the hollow fiber membrane layer due to a decrease in strength. It is important to set an optimum diameter by comprehensively considering these effects. The area ratio of the core tube cross-sectional area to the module container cross-sectional area is 4 to 20%, preferably 5 to 15%.

Having selective permeability means that when water containing suspended solids is treated, the higher the water permeability of the hollow fiber membrane can be filtered at a low pressure, which is advantageous in terms of the required power of the supply pump, Increasing the membrane water permeability generally increases the membrane pore diameter, and a larger substance enters the membrane pores. In addition, the improvement in water permeability increases the processing capacity per module, so that the amount of filtration per unit area increases, the accumulation of dirt on the membrane surface increases, and the detergency in backwashing may deteriorate. For this reason, it is desirable that the water permeability of the membrane is between 50 and 1000 L / m ² / hr / 100 kPa. More preferably, it is 100-800L / m < ² > / hr / 100kPa. On the other hand, the membrane structure has a dense layer on the outer and inner surfaces of the membrane, and an asymmetric membrane with a macrovoid or finger-like structure at the center of the membrane, or a homogeneous sponge-like uniform structure as a whole. Although there are membranes and the like, for the treatment of water containing suspended substances, a structure in which suspended substances do not easily enter the membrane is desirable. Accordingly, it is desirable that the external pressure type hollow fiber membrane for membrane filtration has a dense layer on the outer surface of the hollow fiber membrane so that suspended substances do not enter the inside of the membrane. However, the suspended matter may have an inclined structure in which the pore diameter increases from the inner surface to the outer surface, which makes it easier to go outward.

  The arrangement of the hollow fiber membranes in the filtration module may be either a parallel arrangement or a cross arrangement, but the hollow fiber membranes flow in order to efficiently wash the solid suspended components adhering to the outer surface of the membrane during backwashing. It is preferable to shake or vibrate a little. Since the hollow fiber membranes are fixed in the crossing arrangement, the passage of water during backwashing is fixed, and the flow of water is biased, which may make it difficult to clean the entire membrane surface. Therefore, a parallel arrangement in which the filling rate is 60 vol% or less and the hollow fiber membrane is not fixed except for the bonded portion is preferable in order to provide a certain amount of voids between the hollow fiber membranes. Further, for the purpose of reducing the contact between yarns, the hollow fiber membrane may be crimped or the like.

  In the present invention, both ends of the hollow fiber membranes are separately fixed with the resin, so that fluid leaks between the hollow fiber membranes by potting both ends of the aggregate of the hollow fiber membranes separately with an adhesive resin. It means that it is hermetically fixed in the absence. The adhesive resin to be used can be selected from an epoxy resin, a urethane resin, a silicon resin, and the like depending on the characteristics of the processing fluid and the use conditions. The end portion fixed with the adhesive is cut so that the hollow hole of the hollow fiber membrane is opened to obtain a hollow fiber membrane filtration module.

  In the case of the both-end opening type with both ends of the resin end opened, when using the external pressure type, it is necessary to supply raw water from one port port provided on the side of the container, and it is hollow due to the influence of the water flow at the port port. There is a problem that the yarn membrane is easily damaged.

  The hollow fiber membrane filtration module used in the present invention is preferably an external pressure total volume filtration type. Conventionally, when performing filtration using a membrane such as a microfiltration (MF) membrane or an ultrafiltration (UF) membrane, cross-flow filtration has been used. In cross-flow filtration, the adhesive layer such as gel layer and cake layer formed on the membrane surface is peeled off by the flow of the supply liquid, and the accumulation by filtration and the separation of turbidity by the flow are balanced, thereby stabilizing the filtration performance. It is intended to make it. However, if an attempt is made to increase the ratio of the filtrate flow rate to the supply solution flow rate, the force for peeling off the adhesion layer becomes weak, and therefore it is necessary to flow the supply solution excessively to some extent. Further, if the concentrated liquid in which the non-filtered components are concentrated is discarded as it is, the overall recovery rate is lowered, and therefore, a circulation operation is performed to return to the supply liquid again. However, when such a circulation operation is performed, the pump consumption power increases due to an increase in the flow rate of the supply liquid pump, and it is necessary to increase the piping of the concentrate recirculation system. There is a problem. On the other hand, in the all-volume filtration type, since all the feed water is filtered, the recovery rate in the filtration step is 100%. However, in the treatment of water containing suspended solids, a membrane-impermeable component accumulates in the membrane, and thus a decrease in membrane filtration performance over time cannot be avoided. For this reason, it is necessary to perform backwashing at the time when the membrane performance is reduced or at regular time intervals. If the amount of treated water consumed at the time of backwashing can be reduced and a membrane filtration wastewater having a high concentration can be obtained, an efficient membrane filtration system with a high recovery rate and a small amount of wastewater can be configured by a simple membrane filtration system. . The membrane filtration module structure required to make this efficient backwash system is the main object of the present invention. In the present invention, it is preferable to adopt an external pressure type total amount filtration method in order to effectively use the membrane area of the hollow fiber membrane and to ensure a large turbid flow path at the time of washing.

  A hollow fiber membrane bundle 3 is accommodated in a filtration chamber having a core tube 2 at the center of a cylindrical container 1 and divided into at least two by a partition plate attached to the core tube 2. One of the two bonded end portions of the container 1 is injected with an adhesive 4 between the container and the hollow fiber membrane bundle 3, and the hollow fiber membrane bundle 3 and the bonded end portion outside the end portion after the adhesive is cured. An opening end 8 is formed by cutting 4 to open the hollow fiber membrane. The other is a sealed end 9 in which the end of the hollow fiber membrane bundle 3 is sealed with an adhesive 4. The sealed end 9 is provided with at least one slit 10 in the portion of the adhesive 4 between the hollow fiber membrane bundle 3 and the container 1 for each filtration chamber partitioned by a partition plate. The cap 5 and the rubber packing 6 are attached to both ends of the core tube-equipped container 1 in which the hollow fiber membrane bundles thus formed are arranged, and fixed with the clamp band 7 to constitute a hollow fiber membrane filtration module. 3-12 are preferable and, as for the number of a partition plate, 4-6 are more preferable. If there is no partition plate or the number is small, it is difficult to regulate the location where bubbles rise due to the partition plate, and the effect of yarn swinging is weakened. As a result, there is a possibility that the entire hollow fiber membrane cannot be washed efficiently. On the other hand, if the number of partition plates is too large, the interval between the partition plates becomes narrow, so that it may be difficult to provide a sufficient size and number of holes for air supply and discharge in the core tube. In addition, since the angle between the partition plates becomes an acute angle, it may be difficult to fill the hollow fiber membrane.

  The hollow fiber membrane of the present invention can be used, for example, to remove turbidity from raw water containing suspended substances such as river water, lake water, groundwater, seawater, and to obtain purified water for water and industrial use, and reverse osmosis of seawater desalination. When used as a pretreatment for a membrane system, hollow fiber membranes such as microfiltration membranes and ultrafiltration membranes are widely used, and there are a wide variety of membrane shapes with an inner diameter of 200 to 2,000 μm. These membranes can be used as the hollow fiber membrane of the hollow fiber membrane filtration module of the present invention. Considering ease of cleaning, the inner diameter of the hollow fiber membrane is preferably 200 to 600 μm, more preferably 200 to 550 μm, and further preferably 200 to 500 μm. The outer diameter of the hollow fiber membrane is preferably 300 to 1000 μm, more preferably 300 to 950 μm, and further preferably 300 to 900 μm. If the yarn diameter is too small, the yarn becomes weak, so that it is easy to break the yarn in a process such as back washing, and the washing condition and frequency may be limited. Also, if the hollow fiber membrane is too thick, the membrane area per volume is small, so the amount of filtered water per membrane area increases, the amount of dirt accumulated on the membrane surface increases, and the stiffness of the yarn increases, The yarn does not sway during backwashing, and the releasability of suspended substances attached to the membrane surface may decrease.

  Regarding the strength of the hollow fiber membrane, it is desirable that the hollow fiber membrane has a breaking strength of 60 g or more per single yarn of the hollow fiber membrane in order to prevent a thread breakage leak that occurs during filtration or backwashing. In the module structure of the present invention, a device is devised to make the vertical flow toward the yarn as small as possible, so that an extremely large force is not applied. A flow rate that shakes the yarn film and pushes out deposits on the surface is necessary. For this reason, the force concentrates on the root of the bonded part of the yarn, particularly in the case of vertical installation, and the thread damage and thread breakage occur. Therefore, the hollow fiber membrane has a breaking strength of 60 g or more per single yarn. It is preferable to have. More preferably, it is 70 g or more, More preferably, it is 80 g or more, More preferably, it is 90 g or more, Most preferably, it is 100 g or more.

  Regarding membrane materials, various membrane materials such as cellulose esters, polyolefins, ester-based synthetic polymers such as polycarbonate, polysulfone, and polyethersulfone, and halogen-containing polymers such as polyvinyl chloride, polyvinylidene fluoride, and tetrafluoroethylene are used. Hollow fiber membranes can be used. From the viewpoint of bacterial resistance, polysulfone and polyethersulfone are preferred. Cellulose acetate and cellulose triacetate are preferable from the viewpoint of chlorine resistance and pressure resistance.

  In the case of external pressure type total filtration operation, the relationship between the inner diameter D of the module container and the effective length L of the hollow fiber membrane can be determined optimally from the water permeability of the membrane, the inner and outer diameter of the hollow fiber membrane, and the filling rate. From the standpoint of performance, a module length of 1.5 m or less is appropriate. Moreover, about 1 m is more desirable from the washing | cleaning property at the time of backwashing, and the force applied to the thread | yarn of the upper adhesion part by the weight of the thread | yarn when a module is installed vertically. Regarding the module length, regarding the module diameter, the inner diameter of the container is preferably 30 to 500 mm in order to efficiently flow the washing water from the core tube to the outer periphery of the yarn. Therefore, L / D is preferably 3-50. If L / D is too large, the pressure loss increases, so that it is difficult for permeate to come out and the filtration efficiency may be reduced. On the other hand, if the L / D is too small, the effective length of the hollow fiber membrane is too short and the separation efficiency may decrease. More preferably, it is 3-45, More preferably, it is 3-40, More preferably, it is 3-35.

  The filling rate of the hollow fiber membrane in the filtration chamber of the membrane module is an important factor for ensuring the volumetric efficiency of membrane filtration and the washability during backwashing, and the ratio of the volume of the hollow fiber membrane to the volume of the filtration chamber (vol %) Is required to be 30 vol% to 60 vol%, and more preferably 40 vol% to 55 vol%. When the filling rate is 30 vol% or less, the filtration flow rate per unit pressure per unit module is low, which may be disadvantageous in terms of module volume, installation area, and pump power consumption. On the other hand, when the filling rate is too high, the washing water line speed during backwashing is increased, the force applied to the hollow fiber membrane is increased, the movement of the yarn bundle is reduced, and the variation in the yarn filling is uneven. As a result of imbalance of the backwash water, it becomes impossible to wash the portion where the hollow fiber membrane is densely packed, and a phenomenon may occur in which solid components accumulate and cause a reduction in membrane performance. For this reason, the yarn filling rate in the filtration chamber is 30 vol% to 60 vol%, preferably 40 vol% to 55 vol%.

  In the filtration operation, water supplied to the module from A of the cap 5 is supplied to the hollow fiber membrane bundle 3 through the slit 10 at the sealing end. The water that has permeated through the hollow fiber membrane is collected from the opening end of the hollow fiber membrane to the permeate port B and goes out of the module. Since the filtration operation is carried out by total filtration, suspended substances contained in the raw water gradually accumulate on the membrane surface, the amount of filtered water decreases with time in constant pressure operation, and in the case of low flow control, the transmembrane pressure The difference will rise and it will be necessary to increase the supply pressure. In the constant pressure operation, the backwash operation is performed when the amount of filtered water decreases below the set value, and in the constant flow operation, when the transmembrane pressure difference increases above the set value. Here, when the water quality of the raw water is stable and the concentration of the turbid component is relatively low and stable, it is possible to perform a backwash operation at regular time intervals. Backwashing by any method is possible.

  In the backwashing of the membrane, first, washing water is supplied from the permeate port B toward the inside of the hollow fiber membrane, and turbidity attached to the membrane surface is peeled off by backfiltration of the membrane to perform backfiltration washing. The pressure of the washing water is preferably in the range of 0.01 to 0.3 MPa. If the pressure of the washing water is too low, the water does not spread over the entire hollow fiber membrane, so that the washing becomes uneven and the washing efficiency may deteriorate. On the other hand, if the pressure of the washing water is too high, the supply pressure exceeds the pressure resistance of the membrane, and as a result, the membrane is deformed (collapsed, etc.) or the performance is degraded due to changes in the pore structure (consolidation, etc.). Or, a weak portion of the yarn may rupture and leak. In particular, at the bonding interface, the thread shape of the bonded portion is fixed by the resin, whereas the portion where there is no resin is deformed so that the yarn swells, and shear force is generated at the resin interface. The polymer film is relatively weak in shearing force, and if such a situation is repeated, the yarn breaks and may cause a leak. For this reason, it is preferable to set the pressure at the time of reverse filtration to the said range. Membrane filtered water can be used as the washing water at this time, and a chemical such as sodium hypochlorite can be added to the washing water as necessary. Usable agents include oxidizing agents such as sodium hypochlorite and hydrogen peroxide, reducing agents such as formalin, acids such as nitric acid, phosphoric acid, hydrochloric acid, sulfuric acid and citric acid, and alkalis such as sodium hydroxide and sodium carbonate Chelating agents such as ethylenediaminetetraacetic acid (EDTA), various surfactants, and mixtures thereof can be used, but are not limited thereto. For example, when sodium hypochlorite is added using a polyethersulfone membrane, the effective chlorine concentration is preferably about 1 to 50 ppm. However, the required concentration needs to be optimized due to the characteristics of the membrane material and raw water.

  It is also a preferred embodiment that compressed air is sent into the module from the bottom of the module during backwashing. Compressed air passes through the core tube 2 and flows into the hollow fiber membrane bundle through a hole 13 provided below the stopper plug 12, and moves upward while shaking the hollow fiber membrane. At this time, it is preferable that the hole diameter of the lower side surface of the core tube is 1 mm to 4 mm. If the hole diameter is too small, the air bubbles are too fine and the force to vibrate the hollow fiber membrane is so small that the turbidity adhering to the membrane surface may not be peeled off. Moreover, since a bubble will become large when a hole diameter is too large, a hollow fiber membrane bundle may not be wash | cleaned uniformly. Therefore, the hole diameter on the lower side surface of the core tube is more preferably 1.5 mm to 3.5 mm, and further preferably 2 mm to 3 mm. Further, the number of holes on the lower side surface of the core tube is preferably 6-20. By setting it in this range, bubbles having a size and amount preferable for peeling off the turbidity on the surface of the hollow fiber membrane can be obtained, and the cleaning ability can be enhanced. More preferably, it is 8-16. The position of the closing plug 12 provided in the core tube is preferably provided at a position 1/10 to 2/10 of the length of the core tube from the bottom of the core tube. By providing the closure plug in this range, the entire hollow fiber membrane bundle can be efficiently washed from the lower part to the upper part of the hollow fiber membrane bundle. The turbidity separated from the film surface is adsorbed by the bubbles and moves upward along with the bubbles. Bubbles that have moved up to the top of the module enter the inside of the core tube through holes formed in the top of the core tube and are discharged out of the module. Here, the hole diameter of the upper part of the core tube is preferably 5 mm to 10 mm. By setting the amount within this range, bubbles with adhering turbidity can easily escape into the core tube, so that the turbidity is less likely to be re-adsorbed on the hollow fiber membrane surface. The number of holes on the upper side surface of the core tube is preferably 20-50. By setting the number of holes within this range, the discharge resistance can be reduced, and waste water containing turbidity can be quickly discharged outside the module. The pressure of compressed air is preferably in the range of 0.1 to 0.4 MPa. Since the pressure difference between the pressure of the washing water and the compressed air affects the amount of bubbles and the rising speed, it is necessary to increase the pressure of the compressed air, and the difference is preferably set to 0.01 to 0.3 MPa.

The hollow fiber membrane filtration module is mounted vertically with the open end side up, and pure water is poured from the lower sealed end side, and the whole amount is filtered. The raw water supply pressure at the module inlet is adjusted to 100 kPa, and the amount of water on the filtration side at that time is measured.
The pure water filtration rate of the hollow fiber membrane module of the present invention is preferably 0.5 to ³⁰ m ³ / hr. If the pure water filtration rate is too high, the turbidity will become compacted on the membrane surface when used in a full-water filtration system at a water purification plant, and it will be difficult to remove the turbidity even after washing, reducing the life of the membrane. There is a possibility of coming out. On the other hand, if the pure water filtration rate is too low, the required number of hollow fiber membrane filtration modules increases, installation space becomes large, and there is a possibility that the equipment cost will increase. Therefore, pure water filtration rate is more preferably 0.5 to 30 m ³ / hr, more preferably 1.0~8m ³ / hr.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by this.

(Measurement of hollow fiber membrane inner and outer diameters)
The hollow fiber membrane inner and outer diameters were measured by the following method. First, prepare a metal plate having a thickness of about 1.5 to 2 mm with a hole of 2 to 3 mmφ, and insert the number of hollow fiber membranes into the hole so that the hollow fiber membrane cannot be removed by its own weight. Then, cut the hollow fiber membrane with a razor to adjust the measurement sample. This hollow fiber membrane sample is observed with, for example, a Nikon universal projector V-12A, and a stage that can measure the amount of movement in units of 1 μm is moved, and the outer diameter and inner diameter of the membrane are measured in two perpendicular directions. Record. Five to ten hollow fiber membranes are measured, and the average is taken as the inner and outer diameters of the hollow fiber membranes.

(Calculation of filling rate)
The filling rate is calculated by the filtration chamber volume (Vr) and hollow fiber membrane outer diameter and effective length surrounded by the inner wall of the container, the partition plate, the core tube surface and the bonded portion, and the hollow fiber calculated by the number of yarns in each filtration chamber. It is the ratio of the outer volume diameter reference volume (Vh) and is obtained by Vh / Vr × 100 (%).

(Measurement method of water permeability)
Evaluation of the water permeation performance of pure water is performed by supplying pure water with a turbidity of 0.005 degrees or less, adjusted using an RO device, to the membrane module at a supply pressure of about 100 kPa at room temperature and flowing for 30 minutes. After 30 minutes, the water temperature, supply pressure, and filtration flow rate are measured and converted to a filtration flow rate (L / m ² / hr / 100 kPa) at 25 ° C. and a unit area of 0.1 MPa. The temperature correction is converted by the ratio of the viscosity at each temperature of pure water.
The measurement of the water permeation performance at the time of use is similarly converted from the water temperature, the supply pressure, and the filtration flow rate to a filtration flow rate at 100 kPa per unit area at 25 ° C.

(Measurement method of breaking strength)
The tensile strength of the membrane is measured by using a Tensilon universal testing machine to measure the strength (g) and the elongation (elongation) (%) at the breaking point of a sample obtained by cutting one hollow fiber membrane into a length of 10 cm. Ten hollow fiber membranes are measured, and the average of each strength and elongation is taken as the breaking strength of the membrane. However, if the yarn breaks at the chuck portion, the data is excluded and the data at which the yarn breaks at other than the chuck portion is used.

Example 1
A core tube having an outer diameter of 124 mm and four partition plates was inserted into a polyvinyl chloride cylindrical container having an inner diameter of 125 mm, an outer diameter of 145 mm, and a length of 1,000 mm, and a module container having four filtration chambers was assembled. Internal diameter 400 [mu] m, outer diameter 640 .mu.m, fractional molecular weight of 500,000, water permeation performance ^{560L / hr / m 2 / 100kPa} (25 ℃) polyethersulfone hollow fiber ultrafiltration membrane 8600 pieces of fiber bundle 4 to prepare a of, After inserting into the four filtration chambers of the filtration module container, end bonding was performed using an epoxy resin. The hollow fiber membrane filling rate at this time was 50 vol%, and L / D was 8. At the time of bonding, a plastic mold for slit formation is set in each filtration chamber and bonded to the bonded portion that becomes the sealing end, and after the resin is cured, the plastic mold is removed to form a slit portion. . A part of the opening end side was cut so that the hollow fiber membrane opened after the resin was cured to obtain a membrane filtration module. A plug was inserted into the core tube portion when bonding, so that the adhesive resin did not enter the core tube. The core tube has a length L = 1075 mm, an outer diameter of 32 mm, an inner diameter of 28 mm, a polyvinyl chloride pipe with a stopper plug at a position of 120 mm from the sealing end side, the core tube lower hole diameter of 2 mm, the number of holes, 8 core tubes An upper hole diameter of 5 mm and a shape having 80 holes were used. The area ratio of the core tube to the inner diameter of the module was 6.5%.
A membrane filtration module was configured by attaching a cap to the membrane module container thus formed. The pure water permeation amount of this module was 0.1 MPa and 3 m ³ / hr.

Using the membrane filtration module configured as described above, lake water having an average turbidity of 1.7 was supplied at a pressure of 0.07 MPa, and washing was performed once every 30 minutes with air scrubbing + back filtration washing for 30 seconds. This operation was carried out continuously for one month, and the filtration flow rate and filtrate water turbidity were measured. The initial filtration rate is 0.8 m ³ / hr, and the filtration rate after 1 month is 0.8 m ³ / hr and shows stable filtration performance. No change was observed at 0.01 degrees or less, and no leakage or the like was observed.

(Comparative Example 1)
A module similar to that of Example 1 was produced except that no closing plug was provided in the core tube.

Although continuous operation was performed for 1 month using the same lake water as in Example 1, since no stopper was provided in the core tube, turbid components deposited on the surface of the hollow fiber membrane were sufficiently removed during backwashing. The filtration performance declined over time. That is, after one month, the filtration water turbidity did not change, but the filtration rate decreased to 0.5 m ³ / hr.

(Comparative Example 2)
A module similar to that of Example 1 was produced except that a core tube having 4 holes in the lower part of the core tube and 6 holes in the upper part of the core tube was used.

  Continuous operation was performed for 1 month using the same lake water as in Example 1, but because the number of holes in the upper part of the core tube is particularly small, the turbid component (solid component) peeled off from the membrane surface during backwashing is efficient. It was not well discharged outside the module, but accumulated at the top of the module, and the filtration performance declined over time.

( Reference example )
A module similar to that of Example 1 was produced except that a core tube without a partition plate was used.

  Continuous operation was carried out for 1 month using the same lake water as in Example 1, but since no partition plate was provided in the core tube, air bubbles were evenly dispersed and moved between the hollow fiber membranes during air scrubbing. In addition, spots were generated in the removal of turbid components. Therefore, a decrease in filtration performance over time was observed.

  The module container has a core tube that is parallel to the hollow fiber membrane, and a hollow fiber membrane is arranged around the core tube to constitute a membrane module. When used, the membrane module is arranged in the vertical direction. The core tube has a stopper near the lower part, and a hole is provided on the side surface. By supplying compressed air for cleaning to the filtration chamber from the hole in the lower part of the core tube, the hollow fiber membrane is shaken and air bubbles By removing the turbid components on the film surface with the force of increasing the pressure and performing air scrubbing, more efficient cleaning can be performed. Also, the separated turbid component is discharged together with water and compressed air from the hole on the upper side of the core tube to the outside of the module, so that the peeled turbid component can be efficiently discharged. It was possible to wash and maintain stable filtration performance for a long time. For this reason, it can be suitably used as a hollow fiber membrane filtration module that treats water containing suspended solids such as river water, lake water, ground water, brine, seawater, etc., and removes fine particles and microorganisms contained in these. It is important to contribute to industrial development.

An example of the hollow fiber membrane module of the present invention, which has a core tube 2 having a closure plug 12 in a container 1 and four partition plates 11 attached thereto, and has a slit 10 in an adhesive portion on the sealing end side. Indicates. It is an example of the hollow fiber membrane module of this invention, and is a simple block diagram of a hollow fiber membrane opening side cross section. It is an example of the hollow fiber membrane module of this invention, and is a simple block diagram of the sealing-side adhesion part cross section. It is an example of the comparative example 1 of the hollow fiber membrane module of this invention. The container 1 has the core tube 2 without a closure plug, the four partition plates 11 attached to it, and has the slit 10 in the adhesion part of the sealing end side. The block diagram of a thing is shown. FIG. 2 is an example of Comparative Example 1 of the hollow fiber membrane module of the present invention, and is a simple configuration diagram of a hollow fiber membrane opening side cross section. FIG. 3 is an example of Comparative Example 1 of the hollow fiber membrane module of the present invention, and is a simple configuration diagram of a cross section of a sealing side adhesive portion. It is an example of the comparative example 2 of the hollow fiber membrane module of this invention, has the core pipe 2 which has the closure plug 12 in the container 1, and the four partition plates 11 attached to it, and has the slit 10 in the adhesion part by the side of a sealing end. The block diagram of what has it but has few holes on the side surface of a core pipe is shown. FIG. 6 is an example of Comparative Example 2 of the hollow fiber membrane module of the present invention, and is a simple configuration diagram of a hollow fiber membrane opening side cross section. FIG. 5 is an example of a comparative example 2 of the hollow fiber membrane module of the present invention, and is a simple configuration diagram of a cross section of a sealing side adhesive portion. FIG. 3 shows an example of Comparative Example 3 of the hollow fiber membrane module of the present invention, showing a configuration of a container 1 having a closure plug 12 but no partition plate, and a slit 10 at a sealing end side adhesive portion. . FIG. 6 is an example of Comparative Example 3 of the hollow fiber membrane module of the present invention, and is a simple configuration diagram of the hollow fiber membrane opening side cross section. FIG. 5 is an example of Comparative Example 3 of the hollow fiber membrane module of the present invention, and is a simple configuration diagram of a cross section of a sealing-side adhesive portion.

Explanation of symbols

1: Membrane module container 2: Core tube 3: Hollow fiber membrane 4: Adhesive resin 5: Membrane module cap 6: Packing 7: Clamp band 8: Module opening end face 9: Module sealing end face
10: slit
11: Partition plate
12: Stopcock
13: Core tube side hole for air
14: Core tube side hole for cleaning wastewater discharge a: Raw water supply port b: Permeate outlet c: Cleaning wastewater discharge port d: Air supply port

Claims (8)

A hollow fiber membrane in which a plurality of hollow fiber membranes having permselectivity are arranged around a core tube, both ends of the hollow fiber membrane are separately fixed with resin, and the hollow fiber membrane is open at least at one end A filtration module having a closing plug in a core tube, the closing plug being provided at a position 1/10 to 2/10 of the length of the core tube from the lower part of the core tube, and a core tube below the closing plug The hole diameter (a) on the side surface is 1 to 4 mm, the hole diameter (b) on the side surface of the core tube above the closing plug is 5 to 10 mm, and b ≧ a, and the hole on the side surface of the core tube below the closing plug The number (c) is 6 to 20, the number of holes (d) on the side surface of the core tube above the stopper plug is 20 to 50, d ≧ c, and the upper portion of the core tube is a discharge port. Yarn membrane filtration module.   The hollow fiber membrane filtration module according to claim 1, which is used in external pressure total filtration. The hollow fiber membrane filtration module according to claim 1 or 2 filling factor of the hollow fiber membranes in the filtration chamber of the hollow fiber membrane filtration module is characterized by a 30~60vol%.   The hollow fiber membrane filtration module according to any one of claims 1 to 3, wherein the hollow fiber membrane has an inner diameter of 200 to 600 µm and an outer diameter of 300 to 1000 µm.   The hollow fiber membrane filtration module according to any one of claims 1 to 4, wherein the hollow fiber membrane is mainly composed of polyethersulfone or cellulose triacetate.   The hollow fiber membrane filtration module according to any one of claims 1 to 5, wherein a ratio (L / D) of the effective length L of the hollow fiber membrane filtration module to the inner diameter D of the container is 3 to 50. A hollow fiber membrane in which a plurality of hollow fiber membranes having permselectivity are arranged around a core tube, both ends of the hollow fiber membrane are separately fixed with resin, and the hollow fiber membrane is open at least at one end A method for cleaning a filtration module, which has a stopper plug in the core tube, the hole diameter (a) on the side surface of the core tube below the stopper plug is 1 to 4 mm, and the hole diameter on the side surface of the core tube above the stopper plug (B) is 5 to 10 mm and b ≧ a, the number of holes (c) on the side surface of the core tube below the stopper plug is 6 to 20, and the number of holes on the side surface of the core tube above the stopper plug (d) 20 to 50 and d ≧ c , and compressed air is introduced from the lower part of the core tube with the closure plug located at 1/10 to 2/10 of the length of the core tube from the lower part of the core tube, A method for washing a hollow fiber membrane filtration module, wherein the hollow fiber membrane filtration module is extracted from the upper part of the core tube.   8. The method for washing a hollow fiber membrane filtration module according to claim 7, further comprising flowing filtered water from the inside to the outside of the hollow fiber membrane.

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