JP2006055817A - Method for operating hollow fiber membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow fiber membrane module which can stably be operated for filtration for a long period of time. <P>SOLUTION: The packing ratio of a hollow fiber membrane in the hollow fiber membrane module is regulated according to the turbidity of the original water to be supplied so that the stable operation of the hollow fiber membrane module can be continued since the backwashing and draining are facilitated. This hollow fiber membrane module is constituted so that the hollow fiber membrane is packed in a case housing having an inlet and an outlet and the original water containing a turbid component is made to flow through the hollow fiber membrane from the outside to the inside and filtered. The ratio B (%) of the gross cross-sectional area of the hollow fiber membrane to the cross-sectional area of the case housing in the width direction is adjusted according to the maximum value A of the turbidity of the original water so that relational expression (1): 0.6-0.05log<SB>10</SB>A≤B≤0.65-0.05log<SB>10</SB>A is satisfied. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for operating a hollow fiber membrane module.

  A hollow fiber membrane module of a type in which a required number of hollow fiber membrane bundles are accommodated in a case housing having a liquid inlet / outlet, and liquid (raw water, permeated water, etc.) enters / exits into the case housing only by the liquid inlet / outlet. These types of modules are widely used according to applications in each field because of their advantages such as compactness and small priming volume.

  In addition, with the increase in processing amount, recently, a relatively large module having a high processing capability is often applied. For example, there are modules with a diameter of 400 mm or more and modules with a length of 2000 mm or more. Among these, a treatment operation for filtering from the outside of the hollow fiber to the inside due to the size of the treatment membrane (external pressure filtration operation, hereinafter, external pressure filtration) A lot of driving).

  However, when external pressure filtration operation is performed using this type of hollow fiber membrane module, the turbidity of raw water enters between the hollow fibers of the hollow fiber membrane bundle and must be discharged periodically. There is. In order to increase the processing capacity, the membrane area is increased and the hollow fiber filling rate is improved. In this case, turbid components that have entered between the hollow fibers are difficult to escape during back pressure washing or air bubbling washing. Cause short-term performance decline.

In order to improve such a situation, increase the backwash flow rate and air bubbling amount, increase the backwash frequency and air bubbling frequency, but if the backwash flow rate and air bubbling amount are increased, the hollow fiber Since the membrane bundle is vigorously shaken, there is a problem that the hollow fiber membrane constituting the hollow fiber membrane bundle is likely to be broken, and the replacement frequency of the hollow fiber membrane at a specific part in the hollow fiber membrane bundle is increased. Problems such as interruption of the filtration operation due to replacement work and an increase in operating costs arise. Further, when the backwash frequency and the air bubbling frequency are increased, the recovery rate is lowered, that is, the processing capacity is lowered.
JP 2001-087630 A WO 00/63122

  An object of the present invention is to provide a hollow fiber membrane module that facilitates the discharge of turbid components that have entered between hollow fibers and that can be stably filtered for a long period of time.

  The present invention adjusts the ratio B (%) of the total cross-sectional area of the hollow fiber membrane with respect to the cross-sectional area in the width direction of the case housing according to the turbidity concentration of the raw water, so This is a method of operating a hollow fiber membrane module that facilitates the discharge of mass and enables stable filtration operation for a long period of time.

  As a means for solving the problem, the invention of claim 1 uses a hollow fiber membrane module in which a hollow housing is filled in a case housing having a liquid inlet / outlet, and raw water containing turbid components is transferred from the outside to the inside of the hollow fiber membrane. In the operation method of the hollow fiber membrane module to be filtered, the ratio B (% of the total cross-sectional area of the hollow fiber membrane to the cross-sectional area in the width direction of the case housing of the hollow fiber membrane module used according to the maximum turbidity A of the raw water ) Is adjusted by the following relational expression (1).

0.6-0.05 log ₁₀ A ≦ B ≦ 0.65-0.05 log ₁₀ A (1)
Here, the total cross-sectional area of the hollow fiber membrane is a total sum of cross-sectional areas based on the outer diameter of each hollow fiber.

  When the external pressure filtration operation is performed in the hollow fiber membrane module, the ratio B (% of the total cross-sectional area of the hollow fiber membrane to the cross-sectional area in the width direction of the case housing according to the turbidity concentration of the raw water supplied. The filtration operation method using the membrane module which prescribed | regulated) is provided.

  For example, when the turbidity maximum value A of the supplied raw water is 1 degree, a membrane module in which the ratio B (%) of the total cross-sectional area of the hollow fiber membrane to the cross-sectional area in the width direction of the case housing is 60 to 65% is used. Filtration operation. Moreover, when the maximum value of the turbidity of the supplied raw water is 10 degrees, a membrane module in which the ratio B (%) of the total cross-sectional area of the hollow fiber membrane to the cross-sectional area in the width direction of the case housing is 55 to 60% is used. Perform filtration operation. The filtration operation is performed using the membrane module in which the ratio of the hollow fiber filling rate to the cross-sectional area in the width direction of the case housing body is changed according to the raw water turbidity supplied in this way.

  In the present invention, depending on the supplied raw water turbidity, by performing an external pressure filtration operation using a hollow fiber membrane module that defines the hollow fiber membrane filling ratio in the case housing, the suspended matter that has entered between the hollow fibers Emission of water can be facilitated, and stable filtration operation can be performed continuously for a long time. In addition, it becomes easy to discharge turbidity, so there is no need to increase the backwash flow rate or air bubbling amount, or increase the backwash frequency or air bubbling frequency. It is difficult to occur, and problems such as replacement of the hollow fiber membrane, interruption of the filtration operation due to the replacement work, and increase in operating cost can be reduced, and a reduction in recovery rate, that is, a reduction in processing capacity can be prevented.

  The invention of claim 2 provides a method for operating the hollow fiber membrane module according to claim 1, wherein the effective length of the hollow fiber membrane is 2 m or more. The longer the hollow fiber effective length is, the more effective the membrane area of the membrane module increases.

  The invention according to claim 3 provides the hollow fiber membrane module according to 1 or 2, wherein the hollow fiber bundle of the effective portion of the hollow fiber membrane bundle is partitioned into 2 to 24. Thus, by dividing the hollow fiber bundle of the effective portion of the hollow fiber membrane bundle, a space serving as a flow path is created between the hollow fiber membrane bundles, and the turbid component that has entered between the hollow fibers as described above. Can be easily discharged, and stable filtration operation can be performed continuously for a long period of time.

  `` Hollow fiber membrane bundle '' as used in the present invention means a bundle of a plurality of hollow fiber membranes or an aggregate of a plurality of small bundles in which a plurality of hollow fiber membranes are integrated with an adhesive, The small bundles described above may be integrated with an adhesive or may not be integrated with an adhesive. Further, the number of hollow fibers forming one hollow fiber membrane bundle is not particularly limited, and is appropriately determined in consideration of workability and the like.

  Invention of Claim 4 is a driving | operation method of Claim 1 which includes only a backwashing process and the backwashing process is only the backwashing process which does not use an air bubbling. When the same hollow fiber membrane is used, the effective membrane area increases when the raw water is filtered from the outside to the inside of the hollow fiber membrane compared to the treatment of filtering the raw water from the inside to the outside of the hollow fiber membrane. In the process of filtering raw water from the inside to the outside of the hollow fiber membrane, pressure loss occurs at the inlet side and outlet side of the hollow fiber as the turbidity and viscosity of the supplied raw water increases, As the yarn length becomes longer, this pressure loss increases and effective treatment capacity cannot be exhibited. Therefore, it is preferable to filter from the outside to the inside of the hollow fiber membrane.

  However, in the process of filtering raw water from the outside to the inside of the hollow fiber membrane, back washing and air bubbling are usually performed at the time of back washing. As the length becomes longer, the hollow fiber membrane is more likely to shake, and breakage such as disconnection of the hollow fiber membrane is likely to occur. Therefore, it is preferable to perform only the backwashing process without using air bubbling.

  Invention of Claim 5 is an operating method of the hollow fiber membrane module in any one of Claims 1-3 in which a hollow fiber membrane consists of a cellulose resin, Other materials, for example, polysulfone, PVDF, etc. Compared to the above, since the hydrophilicity is high, fouling of the film hardly occurs and high water permeability can be maintained, which is advantageous.

  A sixth aspect of the present invention is the hollow fiber membrane according to any one of the first to fifth aspects, wherein the bundle of hollow fiber membranes is bound, and the binding means is an annular, tubular, or belt-shaped member having a thickness of 0.1 to 3 mm. This is how the module operates. By bundling the hollow fiber membrane bundle with an annular, tubular, or belt-like member, breakage such as disconnection due to hollow fiber membrane shaking during backwashing is less likely to occur.

  The invention according to claim 7 is the method of operating the hollow fiber membrane module according to any one of claims 1 to 5, wherein the bundling means is water permeable and stretchable, and the opening ratio is 90% or more. By making the binding means water-permeable and having an opening ratio of 90% or more, the permeability and fluidity of raw water and permeated water are not hindered. Moreover, since it can endure the force concerning a hollow fiber membrane bundle by having elasticity, a membrane bundle can be bound effectively.

  The present invention uses a hollow fiber membrane module that defines the hollow fiber membrane filling rate of the hollow fiber membrane module according to the raw water supply turbidity, thereby facilitating sludge discharge during backwashing and reducing processing capacity reduction. In addition, a stable filtration operation can be performed for a long time.

  Hereinafter, the hollow fiber membrane module of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a hollow fiber membrane module, and FIGS. 2, 3, and 4 are plan views of bonded end surfaces when the cap 2 of the hollow fiber membrane module of FIG. 1 is removed. It is shown. FIG. 5 is a cross-sectional view of the membrane module, illustrating the ratio of the total cross-sectional area of the hollow fiber membrane bundle to the cross-sectional area of the case housing. Here, D indicates the inner diameter of the tubular case housing, and d indicates the outer diameter of one hollow fiber membrane. FIG. 6 is a graph showing the relationship between the hollow fiber filling rate and the transmembrane pressure difference in the examples.

  First, the hollow fiber membrane module 100 shown in FIG. 1 will be described. In the hollow fiber membrane module 100, an outer shell (case housing) is formed from the cylindrical main body 1, the upper cap 2, and the lower cap 3. In addition, you may obstruct | occlude the lower part of the cylindrical main-body part 1 and provide a bottom part, without providing the lower cap 3. FIG. These cylindrical main body 1, upper cap 2, and lower cap 3 are preferably made of plastic resin or fiber reinforced resin.

  The upper cap 2 is provided with an upper liquid inlet / outlet 10 (permeate outlet or reverse pressure wash water supply port), and the lower cap 3 is provided with a lower liquid inlet / outlet 11 (permeate outlet or reverse pressure wash water). Supply port) is provided.

  A cylindrical liquid inlet / outlet 12 (raw water inlet / outlet or concentrated water outlet) is provided at the lower part of the side surface of the cylindrical main body 1 so as to protrude outward from the side surface. A cylindrical liquid inlet / outlet 13 (raw water inlet / outlet or concentrated water outlet) is provided so as to protrude outward.

  The hollow fiber membrane bundle 6 is an aggregate of small bundles in which one end or both ends of a plurality of hollow fiber membranes 4 are integrated with an adhesive 5, and the small bundles are in contact with each other at their both ends. There are some that are not, but they are integrated with the adhesive 5.

  By integrating the hollow fiber membrane bundles 6 with an adhesive in this way, the hollow fiber membrane bundles 6 sway and collide repeatedly due to the flow accompanying the flow of liquid (for example, supply of backwash water), and breakage occurs. Is prevented. The hollow fiber membrane bundle on the lower cap 3 side may not be integrated with an adhesive. However, from the viewpoint of making the hollow fiber membrane bundle 6 difficult to shake due to the hydraulic pressure, the adhesive may be used in the same manner as the upper cap 2 side. It is preferable to integrate them.

  The hollow fiber membrane bundle 6 is bound by the binding means 7 in the entire length direction. At this time, a plurality of hollow fiber membrane bundles 6 or all the hollow fiber membrane bundles 6 can be bound by a binding means.

  The bundling means 7 uses a tubular member, particularly a net-like tubular member. Since the hollow fiber membrane bundle is inserted into the bundling means 7, the bundling means 7 is preferably wider than the hollow fiber membrane bundle diameter at the time of insertion and smaller than the hollow fiber membrane bundle diameter after the insertion.

  The bundling means 7 is preferably water-permeable and stretchable. By having water permeability, filtration can be performed even in the bound portion, so that the effective area of the membrane is not reduced. Furthermore, by having elasticity, even when the hollow fiber membrane bundle 6 is shaken by a liquid pressure such as water during filtration operation or back pressure washing, the hollow fiber membrane bundles 6 do not repeatedly collide with each other. In addition to being able to maintain a certain degree of binding strength, it acts to absorb and suppress shaking when shaken.

  2, FIG. 3, and FIG. 4 are plan views of the bonded end face when the cap 2 of the hollow fiber membrane module is removed, and show the end face structure. The thing of FIG. 2 has divided the effective part of the hollow fiber membrane bundle 6 into 6 divisions, and the hollow fiber membrane bundle of the adhesion | attachment edge part is circular. The thing of FIG. 3 has divided the effective part of the hollow fiber membrane bundle 6 into 4 divisions, and the hollow fiber membrane bundle of an adhesion end part is fan-shaped. In FIG. 4, the effective portion of the hollow fiber membrane bundle 6 is divided into eight parts, and the hollow fiber membrane bundle at the bonded end has a fan shape.

  The ratio B (%) of the total cross-sectional area of the hollow fiber membrane to the cross-sectional area in the width direction of the case housing (also referred to as the hollow fiber filling rate) is calculated by the following equation (see FIG. 5).

^{{((D / 2) 2} π × n) / (D / 2) 2 π} × 100 (%)
D: Case housing inner diameter
d: outer diameter of one hollow fiber membrane
n: Number of hollow fibers In order to obtain membrane modules having different hollow fiber filling rates, there are a method of changing the number of hollow fiber membranes and a method of changing the outer diameter of the hollow fiber membrane when using the same cylindrical main body. When the same hollow fiber membrane is used, a method of changing the number of hollow fiber membranes and the inner diameter of the cylindrical main body is used.

  Either method can be used properly depending on the use conditions, but using the same hollow fiber membrane for the same cylindrical body and changing the number of hollow fiber membranes to change the hollow fiber filling rate is simple and efficient. Yes, more preferred.

Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples.
Example 1
Two hollow fiber membrane modules 100 having the shapes of FIGS. 1 and 3 and having different hollow fiber filling rates were produced. Details of each component are as follows.

  The cylindrical body portion 1 of the first membrane module 100 was made of polysulfone having an inner diameter of 80 mm (D) and a length of 2100 mm, and upper and lower caps 2 and 3 made of polysulfone were attached to both ends.

The hollow fiber membrane bundle is a bundle of 592 cellulose acetate hollow fiber membranes (inner diameter 0.8 mm, outer diameter 1.3 mm, length 2100 mm), and is a netron light package “HR3L White 70” manufactured by Dainippon Plastic Co., Ltd. ( A hollow fiber membrane bundle is inserted into a bag-shaped net), and four bundles are stored in a fan shape in a state in which a portion having a total length of 2070 mm other than each 15 mm at both ends of the hollow fiber bundle is covered. By machine industry, horizontal centrifugal molding machine), between the hollow fiber membrane bundles located on both ends of the cylindrical main body 1 and between the hollow fiber membrane bundle and the inner peripheral surface of the cylindrical main body 1 Was adhesively sealed with a urethane-based adhesive. The thickness of the adhesive (the length of one end of the hollow fiber membrane fixed and integrated with the adhesive) is 30 mm (60 mm at both ends), the effective membrane area is 19.7 m ² , and the case housing of the hollow fiber membrane module The ratio (%) (hollow fiber filling factor) of the total cross-sectional area of the hollow fiber membrane to the cross-sectional area in the width direction was 62.5%.

  The cylindrical body portion 1 of the second membrane module 100 was made of polysulfone having an inner diameter of 80 mm (D) and a length of 2100 mm, and upper and lower caps 2 and 3 made of polysulfone were attached to both ends.

The hollow fiber membrane bundle is a bundle of 545 hollow fiber membranes made of cellulose acetate (inner diameter 0.8 mm, outer diameter 1.3 mm, length 2100 mm), and is a netron light package “HR3L White 70” manufactured by Dainippon Plastic Co., Ltd. A hollow fiber membrane bundle is inserted into a bag-shaped net), and four bundles are stored in a fan shape in a state in which a portion having a total length of 2070 mm other than each 15 mm at both ends of the hollow fiber bundle is covered. By machine industry, horizontal centrifugal molding machine), between the hollow fiber membrane bundles located at both ends of the cylindrical main body 1 and between the hollow fiber membrane bundle and the inner peripheral surface of the cylindrical main body 1 Was adhesively sealed with a urethane adhesive. The thickness of the adhesive (the length of one end of the hollow fiber membrane fixed and integrated with the adhesive) is 30 mm (60 mm at both ends), the effective membrane area is 18.2 m ² , and the case housing of the hollow fiber membrane module The ratio (%) (hollow fiber filling factor) of the total cross-sectional area of the hollow fiber membrane to the cross-sectional area in the width direction is 57.5%.

Using two types of membrane modules with different hollow fiber filling ratios produced as described above, membrane filtration experiments were performed using river water with a turbidity of 2 to 7 degrees (average turbidity of 4 degrees). (Since the turbidity maximum value A is 7, the range of the preferable B value in the present application is 55.8 to 60.8% from the equation (1).
Operating conditions: Permeation rate: 3 m / day Back pressure washing flow rate: Twice the filtration flow rate Filtration method: Hollow fiber external pressure total filtration Operation step: Filtration operation 59 minutes / back pressure washing 1 minute The results of the membrane filtration experiment are shown in FIG. As shown in the figure, the increase in the transmembrane pressure difference of the membrane module (57.5% module) having a filling rate within the above range and a hollow fiber filling rate of 57.5% was small in 60 days of operation. The membrane pressure difference of the membrane module having a hollow fiber filling rate of 62.5% (62.5% module) was greatly increased.

Sectional drawing of a hollow fiber membrane module. The end surface top view of a hollow fiber membrane module. The end surface top view of a hollow fiber membrane module. The end surface top view of a hollow fiber membrane module. Explanatory drawing of the ratio (hollow fiber membrane filling rate) of the total cross-sectional area of a hollow fiber membrane with respect to the width direction cross-sectional area of the case housing of a hollow fiber membrane module. The figure which shows the relationship between the hollow fiber filling rate and transmembrane differential pressure | voltage in an Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Hollow fiber membrane module 1 Cylindrical main-body part 2 Upper cap 3 Lower cap 4 Hollow fiber membrane 5 Adhesive 6 Hollow fiber membrane bundle 7 Bundling means 10 Upper liquid inlet / outlet 11 Lower liquid inlet / outlet 12 Liquid inlet / outlet 13 Liquid inlet / outlet

Claims (7)

In a method for operating a hollow fiber membrane module, the raw water containing turbid components is filtered from the outside to the inside of the hollow fiber membrane using a hollow fiber membrane module filled with a hollow fiber membrane in a case housing having a liquid inlet / outlet. According to the maximum turbidity A, the ratio B (%) of the total cross-sectional area of the hollow fiber membrane to the widthwise cross-sectional area of the case housing of the hollow fiber membrane module to be used is adjusted by the following relational expression (1). Operation method of the hollow fiber membrane module.
0.6-0.05 log ₁₀ A ≦ B ≦ 0.65-0.05 log ₁₀ A (1) The method for operating a hollow fiber membrane module according to claim 1, wherein the effective length of the hollow fiber membrane is 2 m or more. The operating method of a hollow fiber membrane module according to claim 1 or 2, wherein the hollow fiber bundle of the hollow fiber membrane bundle effective part is partitioned into 2 to 24. The operating method according to claim 1, comprising a backwashing step, wherein the backwashing step is only a backwashing step without using air bubbling. The operation method of the hollow fiber membrane module according to any one of claims 1 to 3, wherein the hollow fiber membrane is made of a cellulose resin. The method for operating a hollow fiber membrane module according to any one of claims 1 to 5, wherein the hollow fiber membrane bundle is bound, and the binding means is an annular, tubular, or belt-like member having a thickness of 0.1 to 3 mm. The operation method of the hollow fiber membrane module according to claim 1, wherein the binding means is water permeable and stretchable, and the opening ratio is 90% or more.

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