Title of Invention	HOLLOW FIBER MEMBRANE CARTRIDGE
Abstract	A hollow fiber membrane (22) cartridge comprising a hollow fiber membrane bundle (1) consisting of plural hollow fiber membranes and arranged in vertical direction in an immersion bath and adhesion fixation layers for adhering and fixing the hollow fiber membrane bundle (1) at the both ends, and in which the hollow portions of the hollow fiber membranes (22) open at at least the end of an upper-side adhesion fixation layer (4) and the hollow fiber membrane bundle is in a state of plural small bundles on the filtration section-side interface of the upper- side adhesion fixation layer and divided into plural small bundles between the lower-side adhesion fixation layer (5) and the upper-side adhesion fixation layer (4) and there is confounding between hollow fiber membranes.

Title of Invention

HOLLOW FIBER MEMBRANE CARTRIDGE

Abstract

A hollow fiber membrane (22) cartridge comprising a hollow fiber membrane bundle (1) consisting of plural hollow fiber membranes and arranged in vertical direction in an immersion bath and adhesion fixation layers for adhering and fixing the hollow fiber membrane bundle (1) at the both ends, and in which the hollow portions of the hollow fiber membranes (22) open at at least the end of an upper-side adhesion fixation layer (4) and the hollow fiber membrane bundle is in a state of plural small bundles on the filtration section-side interface of the upper- side adhesion fixation layer and divided into plural small bundles between the lower-side adhesion fixation layer (5) and the upper-side adhesion fixation layer (4) and there is confounding between hollow fiber membranes.

Full Text	DESCRIPTION HOLLOW FIBER MEMBRANE CARTRIDGE TECHNICAL FIELD The present invention relates to an immersion type membrane cartridge using a hollow fiber membrane set to a suction type tank filter device or an immersion type filter device. More minutely, the present invention relates to a hollow fiber membrane cartridge used for a filter device that removes turbidity and bacteria from raw water such as river water, lake water, underground water, seawater, domestic liquid waste, industrial liquid waste, or sewage secondary treated water, membrane separation activated sludge device for carrying out solid-liquid separation of activated sludge by a membrane, or separation of valuable objects and non-valuable objects. BACKGROUND ART As a waste water treatment method, there is a membrane separation activated sludge method comprising immersing a membrane cartridge in an activated sludge tank and carrying out solid-liquid separation of the activated sludge and the treated water after the treatment. This method allows the concentration of the activated sludge (MLSS: Mixed Liquor Suspended Solid) to be set at a very large value from 5,000 to 20,000 mg/1 for a filtering process. This advantageously allows the capacity of the activated sludge vessel to be reduced or enables a reaction time in the activated sludge vessel to be shortened. Further, the filtration with the membrane prevents suspended solids (SS) from being mixed into treated water, thus eliminating the need for a final sedimentation tank. This makes it possible to reduce the construction area of the treatment facility and to achieve filtration regardless of whether or not activated sludge is appropriately sedimented. This method thus has advantages such as a reduction in the load of activated sludge managing operation. Therefore, in recent years, the membrane separation activated sludge method has prevailed rapidly. If hollow fiber membranes are used for the membrane cartridge, the high strength of the membrane itself hinders the surface of the membrane from being damaged as a result of contact with contaminants contained in the raw water. The membrane cartridge can thus be used for a long period. Moreover, this structure has the advantage of being capable of back wash reverse filtration, that is, injecting a medium such as treated water in a direction opposite to that of filtration to remove fouling to the membrane surface. In this case, however, effective membrane area may decrease unless filtration is carried out while excluding aggregates of activated sludge as well as contaminants from the raw water accumulating in the gap between the hollow fiber membranes. As a result, filtration efficiency lowers, thus stable filtration is prevented from being maintained over a long period. Conventionally, the following method is used to avoid accumulating sludge or the like on the surfaces of hollow fiber membranes or between the hollow fiber membranes. That is, aeration by air or the like is performed from the lower portion of a membrane cartridge, and activated sludge aggregate and contaminants brought from raw water on the surface of a hollow fiber membrane or between hollow fiber membranes are removed in accordance with the oscillation effect of a membrane and agitation effect by movement of bubblers upward and thereby, accumulation of them is prevented. For example, a lower ring (or also referred to as skirt) is set to the lower portion of a hollow fiber membrane cartridge and a plurality of through- holes are formed on a lower-ring-side adhesion fixation layer to form an air pool in the end of the lower ring protruded from the lower ring by aeration from the lower portion of the cartridge. Thus, bubbles are uniformly generated from the plurality of through-holes and hollow fiber membranes are oscillated so that a suspended material deposited on the outer surfaces of the membranes are easily removed. (For example, refer to Patent Document 1). According to this method, when filtering high-concentration MLSS such as the case of the membrane separation activated sludge method, there is an effect for removing the sludge between hollow fiber membrane bundles in accordance with the agitation effect by aeration and the oscillation effect of a membrane. However, a force for raising activated sludge aggregate or contaminants acts due to ascent of bubbles, and removed sludge moves to a position nearby the adhesion fixation layer, and they are not easily removed to the outside of the membrane bundle. Moreover, the hollow fiber membrane at the portion nearby the adhesion fixation layer has a small oscillation amplitude and therefore, it is impossible to sufficiently remove fouling from the surface of the membrane, and there is a problem that the surface of a hollow fiber is clogged because sludge is accumulated between membranes. [Patent Document 1] JP-A-2000-157846 DISCLOSURE OF THE INVENTION [Problems to Be Solved by the Invention] It is an object of the present invention to provide a hollow fiber membrane cartridge for preventing accumulation of sludge aggregate and contaminants on the hollow fiber membrane cartridge at a necessary minimum amount of aeration and having a stable filtering performance for a long time. [Means for Solving the Problem] As a result of devoting themselves to study, the present inventor et al. have found that by using the following structure for a hollow fiber membrane cartridge, a sludge-fouling discharge route is formed and sludge aggregates and contaminants are discharged to the outside of the membrane cartridge without accumulating between hollow fiber membranes of the membrane cartridge and have completed the present invention. That is, the present invention is described below. (1) A hollow fiber membrane cartridge comprising a hollow fiber membrane bundle consisting of plural hollow fiber membranes and arranged in vertical direction in an immersion bath; and adhesion fixation layers for adhering and fixing the hollow fiber membrane bundle at the both ends, in which the shape of the adhesion fixation layers is selected from the group consisting of a triangle, rectangle, and hexagon and the hollow portions of the hollow fiber membranes open at at least the end of an upper-side adhesion fixation layer, and the hollow fiber membrane bundle is in a state of plural small bundles on the filtration section-side interface of the upper-side adhesion fixation layer. (2) The hollow fiber membrane cartridge described in the above Item (1), wherein the shape of the adhesion fixation layers for adhering and fixing the hollow fiber membrane bundle at the both ends is rectangular, and the hollow fiber membrane bundle is divided into plural small bundles between the lower- side adhesion fixation layer and the upper-side adhesion fixation layer. (3) The hollow fiber membrane cartridge described in the above Item (1), wherein in the plural small bundles of hollow fiber membranes on the filtration section-side interface of the upper-side adhesion fixation layer, the distance between the nearest hollow fiber membranes is less than 2 mm in each small bundle, and the number of hollow fiber membranes constituting each small bundle is 10 or more and 1000 or less, and the distance between the nearest small bundles is 2 mm or more and 100 mm or less. (4) The hollow fiber membrane cartridge described in the above Item (1), in which the upper-side and lower-side adhesion fixation layers include a resin, respectively, and the hardness (measured in accordance with JIS K6253) of the resin at the filtration section- side interface(s) of either or both of the adhesion fixation layers is 20 A or more and 90 A or less. [Effects of the Invention] The present invention makes it possible to prevent sludge from accumulating on the surface of a hollow fiber membrane and realize a filtering performance stable for a long time. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a cross sectional illustration showing an embodiment of a hollow fiber membrane cartridge of the present invention; Figs. 2(a) to 2(c) are schematic diagrams of bundle structures of a hollow fiber membrane cartridge of the present invention and Fig. 2(d) is the bundle structure of a hollow fiber membrane cartridge not included in the present invention; Figs. 3(a) and 3(b) are cross sectional illustrations showing an embodiment of a hollow fiber membrane cartridge of the present invention, respectively, in which Fig. 3(a) shows an example in which a bubble supply section is connected with a membrane cartridge and Fig. 3(b) shows an example in which the bubble supply section is separated from the membrane cartridge; Figs. 4(a), 4(b), and 4(c) are schematic diagrams showing an embodiment of a hollow fiber membrane arrangement on the filtration section-side interface of an upper-side adhesion fixation layer of a hollow fiber membrane cartridge of the present invention, respectively; and Fig. 5(a) is a schematic diagram showing a hollow fiber membrane winding cassette of Example 1. Fig. 5(b) is a schematic diagram showing a cartridge on which a small bundle structure is formed by changing winding pitches at the both ends at the time of winding. Fig. 5(c) is schematic diagram showing the positional relation between the cassette and a housing and the cutting position of an upper-side adhesion fixation layer. Fig. 5(d) is a schematic diagram showing an embodiment of hollow fiber membrane bundle arrangement on the interface of an upper-side adhesion fixation layer exposed due to cutting. And, Fig. 5(e) is a schematic diagram showing an embodiment of hollow fiber bundle arrangement on the interface of a lower-side adhesion fixation layer exposed due to cutting. [Description of reference numerals] 1: Hollow fiber membrane bundle 2: Upper-side adhesion fixation section 3: Lower-side adhesion fixation section 4: Upper-side adhesion fixation layer 5: Lower-side adhesion fixation layer 6: End surface of upper-side adhesion fixation layer 7: End surface of lower-side adhesion fixation layer 8: Bubble supply port 9, 11: Catchment chamber 10, 12: Catchment pipe 13: Side stem 14: Filtration section 15: Filtration section-side interface of upper-side adhesion fixation layer 16: Filtration section-side interface of lower-side adhesion fixation layer 17: Small bundle 18: Through-hole 19: Skirt 20: Gas jetting port 21: Winding pipe 22: Hollow fiber membrane 23: Housing 24: Urethane resin 25: Urethane resin 26: Cut surface BEST MODE FOR CARRYING OUT THE INVENTION Fig. 1 shows an example for illustrating the structure of a hollow fiber membrane cartridge of the present invention. The hollow fiber membrane cartridge has a hollow fiber membrane bundle 1 consisting of plural hollow fiber membranes and a upper-side adhesion fixation section 2 and a lower-side adhesion fixation section 3 at the both ends of the hollow fiber membrane bundle 1, and the hollow fiber membranes are fixed by an upper-side adhesion fixation layer 4 and a lower- side adhesion fixation layer 5. The hollow fiber membranes open at the end surface 6 of the upper-side adhesion fixation layer and they may open or may not at the end surface 7 of the lower-side adhesion fixation layer. More preferable is a structure in which the hollow fiber membranes open only at the end surface 6 of the upper-side adhesion fixation layer and do not open at the end surface 7 of the lower-side adhesion fixation layer, because such a structure enables a lower-side catchment chamber as well as an auxiliary facility to be omitted. A bubble supply port 8 for applying aeration to hollow fiber membranes may be integrated or may not with a membrane cartridge. When the membranes are not integrated with the cartridge, it is preferable to set the port 8 to a position to which aeration is applied to a membrane bundle under the membrane cartridge. Moreover, when the port 8 is integrated with the cartridge, it is possible to jet vapor from an airtight pipe or jet vapor from an air pool after supplying the vapor into a skirt-like space and forming the air pool. When the port 8 is integrated with the cartridge, through-holes for bubbles supplied from the lower portion to escape to the upper portion are formed on the lower-side adhesion fixation layer 5. Fig. 1 shows an example in which the end surfaces of an adhesion fixation layer open at both the upper side and the lower side of hollow fiber membranes and a bubble supply port for carrying out aeration is not integrated with a membrane cartridge. A catchment chambers 9 and 11 and catchment pipes 10 and 12 are connected to the upper and lower adhesion fixation portions. The upper and lower adhesion fixation layers are connected by a side stem 13. In hollow fiber membranes, a portion not included in adhesion fixation layers at the both ends is defined as a filtration section 14, a portion facing the filtration section- side in the upper-side adhesion fixation layer 4 is defined as a filtration section-side interface 15 of the upper-side adhesion fixation layer, and a portion facing the filtration section in the lower-side adhesion fixation layer 5 is defined as the filtration section-side interface 16 of the lower-side adhesion fixation layer. The hollow fiber membrane bundle 1 is divided into plural small bundles 17 on the upper-side adhesion fixation layer 4. Bubbles due to aeration from the lower portion almost vertically rise in a gap between hollow fiber membranes while applying oscillation to the hollow fiber membranes. Amplitude of oscillation of the hollow fiber membranes are small nearby the upper- side adhesion fixation layer and the gap becomes small, and bubbles escape to the outside of a membrane cartridge. When a filling factor is increased and the gap between hollow film membranes is small, solid matter contained in sludge, fiber-like object, and deposit of sludge cannot escape through the gap. As a result, they remain between hollow fiber membranes to decrease a filtering area and make filtering difficult. To easily remove sludge deposit while increasing the filling factor of hollow fiber membranes, it is necessary to form a rarefaction portion in density of hollow fiber membranes nearby an upper-side adhesion fixation portion and use the rarefaction portion as a channel through which sludge deposit escape. That is, a structure is effective in which a hollow fiber membrane bundle is divided into plural small bundles to use the gap between hollow fiber membrane bundles as a channel of aeration bubbles and sludge deposit. However, the gap between hollow fiber membrane bundles nearby an adhesion portion has a small amplitude of oscillation and sludge is easily deposited in the gap. Therefore, by forming small bundles, the distance between hollow fiber membranes in the small bundles decreases, a space in which sludge is accumulated is eliminated, and it is possible to prevent accumulation. Moreover, dividing a hollow fiber membrane bundle into plural small bundles in the portion between the lower-side adhesion fixation layer and the upper- side adhesion fixation layer is preferable because aeration from the lower portion oscillates all hollow fiber membranes thereby enhancing cleaning effect. Particularly, forming plural mutual confoundings between the lower-side adhesion fixation layer and the upper-side adhesion fixation layer on hollow fiber membranes is preferable because the effect of oscillation by aeration is further increased. Though the structure of a lower bundle may be a single bundle, plural small bundle structures may be used. It is preferable that hollow fiber membranes are divided into plural small bundles between the lower-side adhesion fixation layer and the upper-side adhesion fixation layer and there is confounding between hollow fiber membranes. Figs. 2(a) to 2(d) show schematic views of bundle structures. Bundle structures of the present invention are shown in Fig. 2(a) to 2(c) but Fig. 2(d) is not included. As used herein, the fact that there is confounding represents that the positional relation between hollow fiber membranes fixed by the lower-side adhesion fixation layer does not always coincide with the positional relation between hollow fiber membranes fixed by the upper-side adhesion fixation layer. Or it represents a state in which a rod-like object cannot be moved due to the intersection between the membranes when inserting the rod-like object between hollow fiber membranes from the outside of the cartridge on the filtration section-side interface of the lower-side adhesion fixation layer and then, moving the rod-like object to the upper-side adhesion fixation layer. Confounding can be realized by dividing the either side of a single bundle of hollow fiber membranes into small bundle structures, keeping the shapes of the small bundle structures, and bonding the both ends of the hollow fiber membranes. For example, it is possible to form a bundle by winding hollow fiber membranes on two facing sides of a rectangular frame. As shown in Figs. 5(a) and 5(b), it is also possible to form a confounding state by changing the interval between hollow fiber membranes to be wound on two sides. It is preferable that the shape of an adhesion fixation layer to be adhered and fixed at the both ends of a hollow fiber membrane (the shape when viewing a hollow fiber membrane cartridge from the upper portion or lower portion after setting the cartridge so as to arrange the hollow fiber membranes vertically) is any one of triangle, rectangle, and hexagon because closet packing is realized when setting plural hollow fiber membrane cartridges to an immersion bath. Particularly, a rectangle shape is preferable because a channel for sludge deposit to escape to the outside of a cartridge becomes short and thereby sludge deposit is easily discharged with respect to the same number of hollow fiber membranes being used. Moreover, also when infilling plural cartridges, it is possible to independently set or remove any cartridge in the horizontal direction by arranging the cartridges in parallel and the setting operation is efficiently carried out. In the case of small bundles of hollow fiber membranes at the filtration section-side interface of the upper-side adhesion fixation layer, it is preferable that the distance between nearest hollow fiber membranes in each small bundle is less than 2 mm and it is more preferable that the distance is less than 1 mm because it is possible to increase the effective membrane area of hollow fiber membranes and improve the filtering water quantity of a membrane cartridge. As used herein, the distance between hollow fiber membranes is the distance between outermost surfaces of the hollow fiber membranes. Moreover, the number of hollow fiber membranes constituting each small bundle preferably is 10 or more and 1000 or less and more preferably 20 or more and 500 or less. Accumulation of sludge aggregates and contaminants is small between hollow fiber membranes in these ranges. The distance between the nearest small bundles is 2 mm or more and 100 mm or less, more preferably 3 mm or more and less than 30 mm. In this range, it is possible to increase the filling factor of a hollow fiber membrane and filtering water quantity with little accumulation of sludge aggregates and contaminants. As used herein, the distance between small bundles represents the nearest distance among distances between outermost surfaces of hollow fiber membranes included in each small bundle. The aggregation state of hollow fiber membranes in the lower-side adhesion fixation layer may be a single bundle structure or may be divided into plural small bundles. Hereafter, an embodiment of a hollow fiber membrane cartridge of the present invention is described by referring to the accompanying drawings. In Fig. 1, a hollow fiber membrane cartridge is constituted of a hollow fiber membrane bundle 1 in which plural hollow fiber membranes are collected, upper-side adhesion fixation section 2, and lower-side adhesion fixation section 3. In the both ends of the bundled hollow fiber membrane bundle 1, hollow fiber membranes are integrally connected by an adhesive and integrally connected in the upper-side adhesion fixation layer 4 and the lower-side adhesion fixation layer 5, and are opened at the end surface 6 of the upper-side adhesion fixation layer and at the end surface 7 of the lower-side adhesion fixation layer. Catchment chambers 9 and 11 and catchment pipes 10 and 12 are connected to the upper and lower adhesion fixation sections. The bubble supply section 8 is set to the lower portion of the membrane cartridge and bubbles by aeration move upward while oscillating hollow fiber membranes. To integrate the bubble supply section 8 with the membrane cartridge, the bubble supply section 8 is connected to the lower portion of the catchment chamber 11 as shown in Fig. 3(a). Moreover, it is possible to apply gas to hollow fiber membranes by forming through- holes 18 continuing from the bubble supply section 8 up to the filtration section-side interface 16 of the lower-side adhesion fixation layer by passing through the lower-side adhesion fixation layer 5. Moreover, it is possible to form the lower portion of the lower-side adhesion fixation layer 5 into an opened skirt 19 and set a gas jetting port 20 without closing the bubble supply section as shown in Fig. 3(b). It is preferable that the size of through- holes ranges from 2 to 30 mm in an equivalent diameter. The shape of through-hole is optionally selected from a polygon such as a triangle, quadrangle, or hexagon, circle, ellipse, sector, C-shape, or star. It is preferable that the number of through-holes is 2 to 300 though it depends on the cross-sectional area of a membrane cartridge or the number of fibers. It is possible to set positions of the through-holes to optional positions in the lower-side adhesion fixation layer 5. However, it is preferable to uniformly disperse the through-holes in order to uniformly oscillate all hollow fiber membranes. It is preferable that the skirt 19 is protruded to a position lower than the catchment chamber 11 and fixed to the outer periphery of a hollow fiber membrane bundle. It is preferable that the length protruded from the lower portion of the catchment chamber ranges from 5 to 300 mm in order to prevent dissipation of gas from the lower portion though it depends on the size of the membrane cartridge, the amount of supplied gas, and the number and diameter of through-holes. The length of 300 mm or less is preferable because a wasted space is small over the entire length of a cartridge. The length of 5 mm or more is preferable because the gas supplied to the cartridge is effectively led to the through-holes but it is not dissipated in the transverse direction. For uniformly passing the gas spouted from the gas jetting port 20 through plural through-holes 18, it is necessary that the gas spouted from the gas jetting port 20 forms a gas pool on the skirt 19 and gas is supplied from the gas pool to each through-hole. The thickness of the gas pool is preferably 30 mm or more, more preferably 50 mm or more. It is preferable to determine the position of the gas jetting port 20 for aeration by taking into account the thickness of a gas pool to be formed. Though the size of a hollow fiber membrane cartridge adhesion fixation section (the size when viewing the hollow fiber membrane cartridge from the upper portion or lower portion after setting the cartridge so as to arrange the hollow fiber membranes vertically) is optional, in the case of a rectangle structure it is preferable that the aspect ratio (length : width) of the rectangle structure is 3:1 or more and 50:1 or less. When the aspect ratio is smaller than 3:1, a channel when sludge passes between small bundles relatively becomes long but when the aspect ratio is larger than 50:1, a percentage for bubbles to dissipate to the outside of a cartridge increases before the bubbles passing between membrane bundles reach the upper adhesion fixation layer. It is preferable that the vertical length of a hollow fiber membrane cartridge ranges from 300 to 3000 mm. In the present invention, to prevent the rise or twist of the lower-side adhesion fixation layer 3 at the time of aeration, the upper-side adhesion fixation layer 4 and lower-side adhesion fixation layer 5 are connected and fixed by any one of a rod, pipe, plate, chain, cord, and net. The rod or pipe is particularly preferable. It is preferable to use metal or resin as the material to be used. Though the shape of the rod or pipe is optional, it is preferable that the rod or pipe is cylindrical. A shape having an acute-angle corner is not very suitable because it causes a damage when a hollow fiber membrane repeatedly contacts. It is preferable to determine the thickness of the rod or pipe by taking into account the strength against deformation of the material used. Using a pipe or rod having a high hardness for connection is preferable because it is possible to prevent a damage when a hollow fiber membrane repeatedly contacts with the pipe or rod by coating the surface with resin of low hardness. For a hole diameter of a hollow fiber membrane used for the present invention, it is possible to use a reverse osmosis membrane, ultrafilter or a precise filter. Moreover, the material of a hollow fiber membrane is not particularly limited, but the following are cited: polysulfone, polyether sulfone, polyacrylonitrile, polyimide, polyether imide, polyamide, polyether keton, polyether ether keton, polyethylene, polypropylene, poly-4-methylpenten, cellulose, cellulose acetate, polyvinylidene fluoride, polyethylene-tetrafluoroethylene copolymer, and polytetrafluoroethylene. Moreover, it is possible to use a compound material thereof. Furthermore, as the shape of a hollow fiber membrane, a membrane having an inside diameter ranging from 50 to 3000 jxm and an inside/outside diameter ratio ranging from 0.3 to 0.8 is preferably used. As an adhesive used for the present invention, any one of the following polymer materials is used: epoxy resin, urethane resin, epoxy acrylate resin, and silicon resin. It is preferable that the resin hardness of the filtration section-side interface 15 of the upper- side adhesion fixation layer and the filtration section-side interface 16 of the lower-side adhesion fixation layer is 20 A or more and 90 A or less and it is more preferable that the resin hardness is 20 A or more and 70 A or less. If the hardness is 20 A or more, it is possible to keep a shape for a long time. If the hardness is 90 A or less, it is possible to sufficiently moderate a strain stress when a hollow fiber membranes oscillate. It is possible to adjust a resin hardness of an interface to a preferable range by using a resin having a low hardness as an adhesive and moreover bonding such a resin having a low hardness on a fixed layer adhered to a first stage. . For example, it is possible to adjust a resin hardness of an interface by forming an adhesion fixation layer by an epoxy resin and then bonding a silicon resin on the epoxy resin or forming an adhesion fixation layer by an urethane resin and then bonding another urethane resin having a low hardness on the urethane resin. As bonding methods, publicly known methods such as centrifugal bonding method and stationary bonding method are known. To improve the shrinkage on curing or strength of an adhesive, it is also allowed to include a fiber-like object such as glass fiber or carbon fiber or fine powder such as carbon black, alumina, or silica in the above adhesive. Materials of housings of the upper-side adhesion fixation section 2 and the lower-side adhesion fixation section 3 and the catchment chambers 9 and 11 are not particularly limited and they may be the same or different. However, thermoplastic resin or stainless steel is preferably used. In the present invention, as shown in examples of Figs. 4(a) to 4(c), the arrangement of small bundles of hollow fiber membranes on the filtration section-side interface of an upper-side adhesion fixation layer, irregularity is allowed as shown in Fig. 4(a) but it is preferable to linearly arrange the small bundles at equal intervals as shown in Fig. 4(b). Moreover, as shown in Fig. 4(c), the small bundles may be divided into plural rows. It is possible that the shape of a small bundle is not circular or sizes of small bundles are not equal. [Examples] Examples of the present invention are described below. However, the present invention is not restricted to the examples. Example 1 Two cylindrical pipes 21 having a diameter of 1 cm and a length of 80 cm shown in Fig. 5(a) were arranged in parallel by keeping a distance of 2 m from each other to form a winding cassette and wound hollow fiber membranes 22. The pipes 21 were wound by rotating them at 1,650 times while adjusting a winding position so that hollow fiber membranes became small bundles at the one pipe side and became a single bundle at the other pipe side. As shown in Fig. 5(b), traverse was conducted when winding the hollow fiber membrane 22 so that the bundle was divided from the side which became the lower position of a cartridge toward the side which became the upper position of the cartridge and confounding occurs between hollow fiber membranes. Each of cylindrical pipes at the both ends on which hollow fiber membranes were wound was stationary- bonded in a housing 23 made of ABS resin by using a urethane resin 24 (made by SANYUREKKUSU Inc. "SA-6330 type"; hardness after curing: 98A) serving as an adhesion fixation layer in the ABS-resin housing 23. Thereafter, urethane resin 25 (made by SANYUREKKUSU Inc., "SA-6330 type"; hardness after curing: 56A) was fixed on the interface between bonding portion and nonbonding portion of hollow fiber membranes through stationary bonding. A measuring method of resin hardness conformed to JIS K6253. Along the cutting direction 26 shown in Fig. 5(c), a housing, a urethane resin, and a cylindrical pipe were cut. The state of one of the cut cylindrical pipe was the end face shown in Fig. 5(d) and the other one of the cut cylindrical pipe was the state shown in Fig. 5(e). A catchment chamber and a catchment pipe were connected to each of the cut surfaces while keeping the hollow fiber membranes open. It is possible to use any connection method as long as connection is liquid-tightly made. A hollow fiber membrane was a precise filtering membrane made of polyvinylidene fluoride and having a small hole diameter of 0.1 µm, outside diameter of about 1.25 mm, and inside diameter of 0.7 mm and the membrane area of the membrane cartridge was 25 m2. A small bundle was formed by 110 hollow fiber membranes per bundle at the filtration section-side interface of the upper adhesion fixation layer and 30 small bundles were present. The distance between nearest small bundles was 5 mm. In the connection of two pipes of the winding cassette, an upper-side adhesion fixation section and a lower-side adhesion fixation section were connected and fixed by using two pipes each one of which was obtained by covering a pipe made of SUS304 and having an outside diameter of 13 mm with a vinylidene chloride film. An aeration bubble supply section was set to a position 5 cm lower than the lower-side adhesion fixation layer. A hollow fiber membrane cartridge produced thereby was immersed in an activated sludge tank having a volume of 8 m3, and the catchment chamber of the upper adhesion fixation layer and a filtrate pipe were connected, and fixed to the activated sludge tank. Suction filtration was conducted using a suction pump so that a membrane-filtration flow rate is 0.6 m3/membrane area m2/day while aerating air of 10 Nm3/hr from the aeration bubble supply section to the hollow fiber membrane cartridge. The differential pressure between membranes in this case ranged between -15 and -20 kPa and was stable for three months. The concentration MLSS in the activated sludge tank in the evaluation period was 10000 mg/1 on average and the average temperature was 25°C. City sewage water having an average BOD of 150 mg/1 and SS of 160 mg/1 was used for the raw water of activated sludge. The weight of the sludge fouling or contaminants attached to the cartridge after operation was 0.84 kg and it was found that the attached quantity was small. Weights of the cartridge before and after operation were measured for wet hollow fiber membranes and the weight difference was defined as the weight of sludge fouling or contaminants. Example 2 Two cylindrical pipes 21 having a diameter of 1 cm and a length of 80 cm shown in Fig. 5(a) were arranged in parallel by keeping a distance of 1.4 m from each other to form a winding cassette and wound hollow fiber membranes 22. The winding method, the bonding and fixing method by urethane resin and the cutting method were conducted in the same manner as in Example 1. Open were end surfaces of the hollow fiber membranes at the side where small bundles of the hollow fiber membranes were constituted, while close were the oppsite end surfaces of the hollow fiber membranes at the side where the end surfaces were buried inside the urethane resin. A catchment chamber and a catchment pipe were connected only to the end surfaces of the hollow fiber membranes at the side where small bundles of the hollow fiber membranes were constituted. The hollow fiber membranes were the same as those used in Example 1. The membrane area of the hollow fiber membrane cartridge was 17.5 m2. A small bundle was formed by 110 hollow fiber membranes per bundle at a filtration section-side interface of the upper adhesion fixation layer and 30 small bundles were present. The distance between nearest small bundles was 5 mm. In the connection of two pipes of the winding cassette, an upper-side adhesion fixation section and a lower-side adhesion fixation section were connected and fixed by using two pipes each one of which was covering a pipe made of SUS304 and having an outside diameter of 13 mm with a vinylidene chloride film. An aeration bubble supply section was set to a position 5 cm lower than the lower-side adhesion fixation layer. A hollow fiber membrane cartridge produced thereby was immersed in an activated sludge tank having a volume of 8 m3, and the catchment chamber of the upper adhesion fixation layer and a filtrate pipe were connected, and fixed to the activated sludge tank. Suction filtration was conducted using a suction pump so that a membrane-filtration flow rate is 0.6 m3/membrane area m2/day while aerating air of 10 Nm3/hr from the aeration bubble supply section to the hollow fiber membrane cartridge. The differential pressure between membranes in this case ranged between -15 and -20 kPa and was stable for three months. The concentration MLSS in the activated sludge tank in the evaluation period was 10000 mg/1 on average and the average temperature was 25°C. City sewage water having an average BOD of 150 mg/1 and SS of 160 mg/1 was used for the raw water of activated sludge. The weight of the sludge fouling or contaminants attached to the cartridge after operation was determined in the same manner as in Example 1. As a result, the weight was 0.65 kg and it was found that the attached quantity was small. Example 3 The hollow fiber membranes, the number thereof and the housing which are the same as those of Example 1 were used and all hollow fiber membranes were collected to one bundle and they are entwined to a state in which there was confounding between hollow fiber membranes. Thereafter, the hollow fiber membranes at one end were divided into the bundles shown in Fig. 4(b) and the other end was divided as shown in Fig. 4(c). Under this state, stationary bonding was carried out together with the catchment chamber, the catchment pipe, and the housing using the same resin as that used in Example 1. The bonding was conducted while keeping both ends of the hollow fiber membranes open. The procedure after that was carried out similarly to Example 1. As a result of carrying out the same evaluation as the case of Example 1, the differential pressure between membranes ranged from -15 and -21 kPa and it was stable for three months. Moreover, the sludge fouling or contaminants attached to the cartridge after operation was 0.78 kg and it was found that the attached quantity is small. Comparative Example 1 Evaluation was made by an activated sludge tank in the same filtration conditions as the case of the Example 1 except that the arrangement of hollow fiber membranes on the filtration section-side interface of the upper-side adhesion fixation layer was not divided into small bundles but it was formed into a single bundle structure. In this case, the differential pressure between membranes suddenly rises for 14 days, reached up to -80 kPa, and pump suction becomes impossible. Similarly to the case of Example 1, the concentration MLSS in the activated sludge tank in the evaluation period was 10000 mg/1 on average and the average temperature was 25°C. City sewage water having average BOD of 150 mg/1 and SS of 160 mg/1 was used for the raw water of activated sludge. The weight of sludge fouling or contaminants attached to the cartridge after operation was 6.4 kg and it was found that the fouling weight was extremely large. Comparative Example 2 Evaluation was made by an activated sludge tank in the same filtration conditions as the case of the Example 2 except that the arrangement of hollow fiber membranes on the filtration section-side interface of the upper-side adhesion fixation layer was not divided into small bundles but it was formed into a single bundle structure. In this case, the differential pressure between membranes suddenly rises for 12 days, reached up to -80 kPa, and pump suction becomes impossible. Similarly to the case of Example 2, the concentration MLSS in the activated sludge tank in the evaluation period was 10000 mg/1 on average and the average temperature was 25°C. City sewage water having average BOD of 150 mg/1 and SS of 160 mg/1 was used for the raw water of activated sludge. The weight of sludge fouling or contaminants attached to the cartridge after operation was 5.7 kg and it was found that the fouling weight was extremely large. INDUSTRIAL APPLICABILITY The hollow fiber membrane cartridge of the present invention can be preferably used in the field of membrane filtration, in particular for a suction- type tank filtration device or an immersion-type filtration device. WE CLAIM : 1. A hollow fiber membrane (22) cartridge comprising a hollow fiber membrane bundle (1) consisting of plural hollow fiber membranes and arranged in vertical direction in an immersion bath and adhesion fixation layers for adhering and fixing the hollow fiber membrane bundle (1) at the both ends, and in which the hollow portions of the hollow fiber membranes (22) open at at least the end of an upper-side adhesion fixation layer (4) and the hollow fiber membrane bundle is in a state of plural small bundles on the filtration section-side interface of the upper-side adhesion fixation layer and divided into plural small bundles between the lower-side adhesion fixation layer (5) and the upper-side adhesion fixation layer (4) and there is confounding between hollow fiber membranes. 2. The hollow fiber membrane cartridge claimed in claim 1, wherein the plural small bundles of hollow fiber membranes (22) on the filtration section-side interface of the upper-side adhesion fixation layer(15), the distance between the nearest hollow fiber membranes is less than 2 mm in each small bundle, and the number of hollow fiber membranes (22) constituting each small bundle is 10 or more and 1000 or less, and the distance between the nearest small bundles is 2 mm or more and 100 mm or less. 3. The hollow fiber membrane cartridge as claimed in claim 1, in which the upper-side and lower-side adhesion fixation layers (5) include a resin, respectively, and the hardness ( measured in accordance with JTS K6253) of the resin at the filtration section-side interface(s) of either or both of the adhesion fixation layers is 20 A or more and 90 A or less. 4. The hollow fiber membrane catridge as claimed in any one of claims 1 to 3, wherein the shape of the adhesion fixation layers is selected from the group consisting of a triangle, rectangle, and hexagon. ABSTRACT Title : HOLLOW FIBER MEMBRANE CARTRIDGE A hollow fiber membrane (22) cartridge comprising a hollow fiber membrane bundle (1) consisting of plural hollow fiber membranes and arranged in vertical direction in an immersion bath and adhesion fixation layers for adhering and fixing the hollow fiber membrane bundle (1) at the both ends, and in which the hollow portions of the hollow fiber membranes (22) open at at least the end of an upper-side adhesion fixation layer (4) and the hollow fiber membrane bundle is in a state of plural small bundles on the filtration section-side interface of the upper- side adhesion fixation layer and divided into plural small bundles between the lower-side adhesion fixation layer (5) and the upper-side adhesion fixation layer (4) and there is confounding between hollow fiber membranes.

Full Text

DESCRIPTION
HOLLOW FIBER MEMBRANE CARTRIDGE
TECHNICAL FIELD
The present invention relates to an immersion
type membrane cartridge using a hollow fiber membrane
set to a suction type tank filter device or an
immersion type filter device. More minutely, the
present invention relates to a hollow fiber membrane
cartridge used for a filter device that removes
turbidity and bacteria from raw water such as river
water, lake water, underground water, seawater,
domestic liquid waste, industrial liquid waste, or
sewage secondary treated water, membrane separation
activated sludge device for carrying out solid-liquid
separation of activated sludge by a membrane, or
separation of valuable objects and non-valuable
objects.
BACKGROUND ART
As a waste water treatment method, there is a
membrane separation activated sludge method comprising
immersing a membrane cartridge in an activated sludge
tank and carrying out solid-liquid separation of the
activated sludge and the treated water after the
treatment. This method allows the concentration of the
activated sludge (MLSS: Mixed Liquor Suspended Solid)

to be set at a very large value from 5,000 to 20,000
mg/1 for a filtering process. This advantageously
allows the capacity of the activated sludge vessel to
be reduced or enables a reaction time in the activated
sludge vessel to be shortened. Further, the filtration
with the membrane prevents suspended solids (SS) from
being mixed into treated water, thus eliminating the
need for a final sedimentation tank. This makes it
possible to reduce the construction area of the
treatment facility and to achieve filtration regardless
of whether or not activated sludge is appropriately
sedimented. This method thus has advantages such as a
reduction in the load of activated sludge managing
operation. Therefore, in recent years, the membrane
separation activated sludge method has prevailed
rapidly.
If hollow fiber membranes are used for the
membrane cartridge, the high strength of the membrane
itself hinders the surface of the membrane from being
damaged as a result of contact with contaminants
contained in the raw water. The membrane cartridge can
thus be used for a long period. Moreover, this
structure has the advantage of being capable of back
wash reverse filtration, that is, injecting a medium
such as treated water in a direction opposite to that
of filtration to remove fouling to the membrane
surface. In this case, however, effective membrane
area may decrease unless filtration is carried out

while excluding aggregates of activated sludge as well
as contaminants from the raw water accumulating in the
gap between the hollow fiber membranes. As a result,
filtration efficiency lowers, thus stable filtration is
prevented from being maintained over a long period.
Conventionally, the following method is used
to avoid accumulating sludge or the like on the
surfaces of hollow fiber membranes or between the
hollow fiber membranes. That is, aeration by air or
the like is performed from the lower portion of a
membrane cartridge, and activated sludge aggregate and
contaminants brought from raw water on the surface of a
hollow fiber membrane or between hollow fiber membranes
are removed in accordance with the oscillation effect
of a membrane and agitation effect by movement of
bubblers upward and thereby, accumulation of them is
prevented. For example, a lower ring (or also referred
to as skirt) is set to the lower portion of a hollow
fiber membrane cartridge and a plurality of through-
holes are formed on a lower-ring-side adhesion fixation
layer to form an air pool in the end of the lower ring
protruded from the lower ring by aeration from the
lower portion of the cartridge. Thus, bubbles are
uniformly generated from the plurality of through-holes
and hollow fiber membranes are oscillated so that a
suspended material deposited on the outer surfaces of
the membranes are easily removed. (For example, refer
to Patent Document 1).

According to this method, when filtering
high-concentration MLSS such as the case of the
membrane separation activated sludge method, there is
an effect for removing the sludge between hollow fiber
membrane bundles in accordance with the agitation
effect by aeration and the oscillation effect of a
membrane. However, a force for raising activated
sludge aggregate or contaminants acts due to ascent of
bubbles, and removed sludge moves to a position nearby
the adhesion fixation layer, and they are not easily
removed to the outside of the membrane bundle.
Moreover, the hollow fiber membrane at the portion
nearby the adhesion fixation layer has a small
oscillation amplitude and therefore, it is impossible
to sufficiently remove fouling from the surface of the
membrane, and there is a problem that the surface of a
hollow fiber is clogged because sludge is accumulated
between membranes.
[Patent Document 1] JP-A-2000-157846
DISCLOSURE OF THE INVENTION
[Problems to Be Solved by the Invention]
It is an object of the present invention to
provide a hollow fiber membrane cartridge for
preventing accumulation of sludge aggregate and
contaminants on the hollow fiber membrane cartridge at
a necessary minimum amount of aeration and having a
stable filtering performance for a long time.

[Means for Solving the Problem]
As a result of devoting themselves to study,
the present inventor et al. have found that by using
the following structure for a hollow fiber membrane
cartridge, a sludge-fouling discharge route is formed
and sludge aggregates and contaminants are discharged
to the outside of the membrane cartridge without
accumulating between hollow fiber membranes of the
membrane cartridge and have completed the present
invention.
That is, the present invention is described
below.
(1) A hollow fiber membrane cartridge comprising
a hollow fiber membrane bundle consisting of plural
hollow fiber membranes and arranged in vertical
direction in an immersion bath; and adhesion fixation
layers for adhering and fixing the hollow fiber
membrane bundle at the both ends, in which the shape of
the adhesion fixation layers is selected from the group
consisting of a triangle, rectangle, and hexagon and
the hollow portions of the hollow fiber membranes open
at at least the end of an upper-side adhesion fixation
layer, and the hollow fiber membrane bundle is in a
state of plural small bundles on the filtration
section-side interface of the upper-side adhesion
fixation layer.
(2) The hollow fiber membrane cartridge described
in the above Item (1), wherein the shape of the

adhesion fixation layers for adhering and fixing the
hollow fiber membrane bundle at the both ends is
rectangular, and the hollow fiber membrane bundle is
divided into plural small bundles between the lower-
side adhesion fixation layer and the upper-side
adhesion fixation layer.
(3) The hollow fiber membrane cartridge described
in the above Item (1), wherein in the plural small
bundles of hollow fiber membranes on the filtration
section-side interface of the upper-side adhesion
fixation layer, the distance between the nearest hollow
fiber membranes is less than 2 mm in each small bundle,
and the number of hollow fiber membranes constituting
each small bundle is 10 or more and 1000 or less, and
the distance between the nearest small bundles is 2 mm
or more and 100 mm or less.
(4) The hollow fiber membrane cartridge described
in the above Item (1), in which the upper-side and
lower-side adhesion fixation layers include a resin,
respectively, and the hardness (measured in accordance
with JIS K6253) of the resin at the filtration section-
side interface(s) of either or both of the adhesion
fixation layers is 20 A or more and 90 A or less.
[Effects of the Invention]
The present invention makes it possible to
prevent sludge from accumulating on the surface of a
hollow fiber membrane and realize a filtering
performance stable for a long time.

BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a cross sectional illustration
showing an embodiment of a hollow fiber membrane
cartridge of the present invention;
Figs. 2(a) to 2(c) are schematic diagrams of
bundle structures of a hollow fiber membrane cartridge
of the present invention and Fig. 2(d) is the bundle
structure of a hollow fiber membrane cartridge not
included in the present invention;
Figs. 3(a) and 3(b) are cross sectional
illustrations showing an embodiment of a hollow fiber
membrane cartridge of the present invention,
respectively, in which Fig. 3(a) shows an example in
which a bubble supply section is connected with a
membrane cartridge and Fig. 3(b) shows an example in
which the bubble supply section is separated from the
membrane cartridge;
Figs. 4(a), 4(b), and 4(c) are schematic
diagrams showing an embodiment of a hollow fiber
membrane arrangement on the filtration section-side
interface of an upper-side adhesion fixation layer of a
hollow fiber membrane cartridge of the present
invention, respectively; and
Fig. 5(a) is a schematic diagram showing a
hollow fiber membrane winding cassette of Example 1.
Fig. 5(b) is a schematic diagram showing a
cartridge on which a small bundle structure is formed

by changing winding pitches at the both ends at the
time of winding.
Fig. 5(c) is schematic diagram showing the
positional relation between the cassette and a housing
and the cutting position of an upper-side adhesion
fixation layer.
Fig. 5(d) is a schematic diagram showing an
embodiment of hollow fiber membrane bundle arrangement
on the interface of an upper-side adhesion fixation
layer exposed due to cutting.
And, Fig. 5(e) is a schematic diagram showing
an embodiment of hollow fiber bundle arrangement on the
interface of a lower-side adhesion fixation layer
exposed due to cutting.
[Description of reference numerals]
1: Hollow fiber membrane bundle
2: Upper-side adhesion fixation section
3: Lower-side adhesion fixation section
4: Upper-side adhesion fixation layer
5: Lower-side adhesion fixation layer
6: End surface of upper-side adhesion fixation layer
7: End surface of lower-side adhesion fixation layer
8: Bubble supply port
9, 11: Catchment chamber
10, 12: Catchment pipe
13: Side stem
14: Filtration section

15: Filtration section-side interface of upper-side
adhesion fixation layer
16: Filtration section-side interface of lower-side
adhesion fixation layer
17: Small bundle
18: Through-hole
19: Skirt
20: Gas jetting port
21: Winding pipe
22: Hollow fiber membrane
23: Housing
24: Urethane resin
25: Urethane resin
26: Cut surface
BEST MODE FOR CARRYING OUT THE INVENTION
Fig. 1 shows an example for illustrating the
structure of a hollow fiber membrane cartridge of the
present invention. The hollow fiber membrane cartridge
has a hollow fiber membrane bundle 1 consisting of
plural hollow fiber membranes and a upper-side adhesion
fixation section 2 and a lower-side adhesion fixation
section 3 at the both ends of the hollow fiber membrane
bundle 1, and the hollow fiber membranes are fixed by
an upper-side adhesion fixation layer 4 and a lower-
side adhesion fixation layer 5. The hollow fiber
membranes open at the end surface 6 of the upper-side
adhesion fixation layer and they may open or may not at

the end surface 7 of the lower-side adhesion fixation
layer. More preferable is a structure in which the
hollow fiber membranes open only at the end surface 6
of the upper-side adhesion fixation layer and do not
open at the end surface 7 of the lower-side adhesion
fixation layer, because such a structure enables a
lower-side catchment chamber as well as an auxiliary
facility to be omitted.
A bubble supply port 8 for applying aeration
to hollow fiber membranes may be integrated or may not
with a membrane cartridge. When the membranes are not
integrated with the cartridge, it is preferable to set
the port 8 to a position to which aeration is applied
to a membrane bundle under the membrane cartridge.
Moreover, when the port 8 is integrated with the
cartridge, it is possible to jet vapor from an airtight
pipe or jet vapor from an air pool after supplying the
vapor into a skirt-like space and forming the air pool.
When the port 8 is integrated with the cartridge,
through-holes for bubbles supplied from the lower
portion to escape to the upper portion are formed on
the lower-side adhesion fixation layer 5.
Fig. 1 shows an example in which the end
surfaces of an adhesion fixation layer open at both the
upper side and the lower side of hollow fiber membranes
and a bubble supply port for carrying out aeration is
not integrated with a membrane cartridge. A catchment
chambers 9 and 11 and catchment pipes 10 and 12 are

connected to the upper and lower adhesion fixation
portions.
The upper and lower adhesion fixation layers
are connected by a side stem 13. In hollow fiber
membranes, a portion not included in adhesion fixation
layers at the both ends is defined as a filtration
section 14, a portion facing the filtration section-
side in the upper-side adhesion fixation layer 4 is
defined as a filtration section-side interface 15 of
the upper-side adhesion fixation layer, and a portion
facing the filtration section in the lower-side
adhesion fixation layer 5 is defined as the filtration
section-side interface 16 of the lower-side adhesion
fixation layer.
The hollow fiber membrane bundle 1 is divided
into plural small bundles 17 on the upper-side adhesion
fixation layer 4.
Bubbles due to aeration from the lower
portion almost vertically rise in a gap between hollow
fiber membranes while applying oscillation to the
hollow fiber membranes. Amplitude of oscillation of
the hollow fiber membranes are small nearby the upper-
side adhesion fixation layer and the gap becomes small,
and bubbles escape to the outside of a membrane
cartridge.
When a filling factor is increased and the
gap between hollow film membranes is small, solid
matter contained in sludge, fiber-like object, and

deposit of sludge cannot escape through the gap. As a
result, they remain between hollow fiber membranes to
decrease a filtering area and make filtering difficult.
To easily remove sludge deposit while
increasing the filling factor of hollow fiber
membranes, it is necessary to form a rarefaction
portion in density of hollow fiber membranes nearby an
upper-side adhesion fixation portion and use the
rarefaction portion as a channel through which sludge
deposit escape. That is, a structure is effective in
which a hollow fiber membrane bundle is divided into
plural small bundles to use the gap between hollow
fiber membrane bundles as a channel of aeration bubbles
and sludge deposit.
However, the gap between hollow fiber
membrane bundles nearby an adhesion portion has a small
amplitude of oscillation and sludge is easily deposited
in the gap. Therefore, by forming small bundles, the
distance between hollow fiber membranes in the small
bundles decreases, a space in which sludge is
accumulated is eliminated, and it is possible to
prevent accumulation.
Moreover, dividing a hollow fiber membrane
bundle into plural small bundles in the portion between
the lower-side adhesion fixation layer and the upper-
side adhesion fixation layer is preferable because
aeration from the lower portion oscillates all hollow
fiber membranes thereby enhancing cleaning effect.

Particularly, forming plural mutual confoundings
between the lower-side adhesion fixation layer and the
upper-side adhesion fixation layer on hollow fiber
membranes is preferable because the effect of
oscillation by aeration is further increased. Though
the structure of a lower bundle may be a single bundle,
plural small bundle structures may be used. It is
preferable that hollow fiber membranes are divided into
plural small bundles between the lower-side adhesion
fixation layer and the upper-side adhesion fixation
layer and there is confounding between hollow fiber
membranes. Figs. 2(a) to 2(d) show schematic views of
bundle structures. Bundle structures of the present
invention are shown in Fig. 2(a) to 2(c) but Fig. 2(d)
is not included.
As used herein, the fact that there is
confounding represents that the positional relation
between hollow fiber membranes fixed by the lower-side
adhesion fixation layer does not always coincide with
the positional relation between hollow fiber membranes
fixed by the upper-side adhesion fixation layer. Or it
represents a state in which a rod-like object cannot be
moved due to the intersection between the membranes
when inserting the rod-like object between hollow fiber
membranes from the outside of the cartridge on the
filtration section-side interface of the lower-side
adhesion fixation layer and then, moving the rod-like
object to the upper-side adhesion fixation layer.

Confounding can be realized by dividing the
either side of a single bundle of hollow fiber
membranes into small bundle structures, keeping the
shapes of the small bundle structures, and bonding the
both ends of the hollow fiber membranes. For example,
it is possible to form a bundle by winding hollow fiber
membranes on two facing sides of a rectangular frame.
As shown in Figs. 5(a) and 5(b), it is also possible to
form a confounding state by changing the interval
between hollow fiber membranes to be wound on two
sides.
It is preferable that the shape of an
adhesion fixation layer to be adhered and fixed at the
both ends of a hollow fiber membrane (the shape when
viewing a hollow fiber membrane cartridge from the
upper portion or lower portion after setting the
cartridge so as to arrange the hollow fiber membranes
vertically) is any one of triangle, rectangle, and
hexagon because closet packing is realized when setting
plural hollow fiber membrane cartridges to an immersion
bath. Particularly, a rectangle shape is preferable
because a channel for sludge deposit to escape to the
outside of a cartridge becomes short and thereby sludge
deposit is easily discharged with respect to the same
number of hollow fiber membranes being used. Moreover,
also when infilling plural cartridges, it is possible
to independently set or remove any cartridge in the
horizontal direction by arranging the cartridges in

parallel and the setting operation is efficiently
carried out.
In the case of small bundles of hollow fiber
membranes at the filtration section-side interface of
the upper-side adhesion fixation layer, it is
preferable that the distance between nearest hollow
fiber membranes in each small bundle is less than 2 mm
and it is more preferable that the distance is less
than 1 mm because it is possible to increase the
effective membrane area of hollow fiber membranes and
improve the filtering water quantity of a membrane
cartridge. As used herein, the distance between hollow
fiber membranes is the distance between outermost
surfaces of the hollow fiber membranes. Moreover, the
number of hollow fiber membranes constituting each
small bundle preferably is 10 or more and 1000 or less
and more preferably 20 or more and 500 or less.
Accumulation of sludge aggregates and contaminants is
small between hollow fiber membranes in these ranges.
The distance between the nearest small bundles is 2 mm
or more and 100 mm or less, more preferably 3 mm or
more and less than 30 mm. In this range, it is
possible to increase the filling factor of a hollow
fiber membrane and filtering water quantity with little
accumulation of sludge aggregates and contaminants. As
used herein, the distance between small bundles
represents the nearest distance among distances between
outermost surfaces of hollow fiber membranes included

in each small bundle.
The aggregation state of hollow fiber
membranes in the lower-side adhesion fixation layer may
be a single bundle structure or may be divided into
plural small bundles.
Hereafter, an embodiment of a hollow fiber
membrane cartridge of the present invention is
described by referring to the accompanying drawings.
In Fig. 1, a hollow fiber membrane cartridge
is constituted of a hollow fiber membrane bundle 1 in
which plural hollow fiber membranes are collected,
upper-side adhesion fixation section 2, and lower-side
adhesion fixation section 3. In the both ends of the
bundled hollow fiber membrane bundle 1, hollow fiber
membranes are integrally connected by an adhesive and
integrally connected in the upper-side adhesion
fixation layer 4 and the lower-side adhesion fixation
layer 5, and are opened at the end surface 6 of the
upper-side adhesion fixation layer and at the end
surface 7 of the lower-side adhesion fixation layer.
Catchment chambers 9 and 11 and catchment pipes 10 and
12 are connected to the upper and lower adhesion
fixation sections. The bubble supply section 8 is set
to the lower portion of the membrane cartridge and
bubbles by aeration move upward while oscillating
hollow fiber membranes.
To integrate the bubble supply section 8 with
the membrane cartridge, the bubble supply section 8 is

connected to the lower portion of the catchment chamber
11 as shown in Fig. 3(a). Moreover, it is possible to
apply gas to hollow fiber membranes by forming through-
holes 18 continuing from the bubble supply section 8 up
to the filtration section-side interface 16 of the
lower-side adhesion fixation layer by passing through
the lower-side adhesion fixation layer 5. Moreover, it
is possible to form the lower portion of the lower-side
adhesion fixation layer 5 into an opened skirt 19 and
set a gas jetting port 20 without closing the bubble
supply section as shown in Fig. 3(b).
It is preferable that the size of through-
holes ranges from 2 to 30 mm in an equivalent diameter.
The shape of through-hole is optionally selected from a
polygon such as a triangle, quadrangle, or hexagon,
circle, ellipse, sector, C-shape, or star. It is
preferable that the number of through-holes is 2 to 300
though it depends on the cross-sectional area of a
membrane cartridge or the number of fibers. It is
possible to set positions of the through-holes to
optional positions in the lower-side adhesion fixation
layer 5. However, it is preferable to uniformly
disperse the through-holes in order to uniformly
oscillate all hollow fiber membranes.
It is preferable that the skirt 19 is
protruded to a position lower than the catchment
chamber 11 and fixed to the outer periphery of a hollow
fiber membrane bundle. It is preferable that the

length protruded from the lower portion of the
catchment chamber ranges from 5 to 300 mm in order to
prevent dissipation of gas from the lower portion
though it depends on the size of the membrane
cartridge, the amount of supplied gas, and the number
and diameter of through-holes. The length of 300 mm or
less is preferable because a wasted space is small over
the entire length of a cartridge. The length of 5 mm
or more is preferable because the gas supplied to the
cartridge is effectively led to the through-holes but
it is not dissipated in the transverse direction.
For uniformly passing the gas spouted from
the gas jetting port 20 through plural through-holes
18, it is necessary that the gas spouted from the gas
jetting port 20 forms a gas pool on the skirt 19 and
gas is supplied from the gas pool to each through-hole.
The thickness of the gas pool is preferably 30 mm or
more, more preferably 50 mm or more. It is preferable
to determine the position of the gas jetting port 20
for aeration by taking into account the thickness of a
gas pool to be formed.
Though the size of a hollow fiber membrane
cartridge adhesion fixation section (the size when
viewing the hollow fiber membrane cartridge from the
upper portion or lower portion after setting the
cartridge so as to arrange the hollow fiber membranes
vertically) is optional, in the case of a rectangle
structure it is preferable that the aspect ratio

(length : width) of the rectangle structure is 3:1 or
more and 50:1 or less. When the aspect ratio is
smaller than 3:1, a channel when sludge passes between
small bundles relatively becomes long but when the
aspect ratio is larger than 50:1, a percentage for
bubbles to dissipate to the outside of a cartridge
increases before the bubbles passing between membrane
bundles reach the upper adhesion fixation layer.
It is preferable that the vertical length of
a hollow fiber membrane cartridge ranges from 300 to
3000 mm.
In the present invention, to prevent the rise
or twist of the lower-side adhesion fixation layer 3 at
the time of aeration, the upper-side adhesion fixation
layer 4 and lower-side adhesion fixation layer 5 are
connected and fixed by any one of a rod, pipe, plate,
chain, cord, and net. The rod or pipe is particularly
preferable. It is preferable to use metal or resin as
the material to be used. Though the shape of the rod
or pipe is optional, it is preferable that the rod or
pipe is cylindrical. A shape having an acute-angle
corner is not very suitable because it causes a damage
when a hollow fiber membrane repeatedly contacts. It
is preferable to determine the thickness of the rod or
pipe by taking into account the strength against
deformation of the material used. Using a pipe or rod
having a high hardness for connection is preferable
because it is possible to prevent a damage when a

hollow fiber membrane repeatedly contacts with the pipe
or rod by coating the surface with resin of low
hardness.
For a hole diameter of a hollow fiber
membrane used for the present invention, it is possible
to use a reverse osmosis membrane, ultrafilter or a
precise filter. Moreover, the material of a hollow
fiber membrane is not particularly limited, but the
following are cited: polysulfone, polyether sulfone,
polyacrylonitrile, polyimide, polyether imide,
polyamide, polyether keton, polyether ether keton,
polyethylene, polypropylene, poly-4-methylpenten,
cellulose, cellulose acetate, polyvinylidene fluoride,
polyethylene-tetrafluoroethylene copolymer, and
polytetrafluoroethylene. Moreover, it is possible to
use a compound material thereof. Furthermore, as the
shape of a hollow fiber membrane, a membrane having an
inside diameter ranging from 50 to 3000 jxm and an
inside/outside diameter ratio ranging from 0.3 to 0.8
is preferably used.
As an adhesive used for the present
invention, any one of the following polymer materials
is used: epoxy resin, urethane resin, epoxy acrylate
resin, and silicon resin.
It is preferable that the resin hardness of
the filtration section-side interface 15 of the upper-
side adhesion fixation layer and the filtration
section-side interface 16 of the lower-side adhesion

fixation layer is 20 A or more and 90 A or less and it
is more preferable that the resin hardness is 20 A or
more and 70 A or less. If the hardness is 20 A or
more, it is possible to keep a shape for a long time.
If the hardness is 90 A or less, it is possible to
sufficiently moderate a strain stress when a hollow
fiber membranes oscillate. It is possible to adjust a
resin hardness of an interface to a preferable range by
using a resin having a low hardness as an adhesive and
moreover bonding such a resin having a low hardness on
a fixed layer adhered to a first stage. . For example,
it is possible to adjust a resin hardness of an
interface by forming an adhesion fixation layer by an
epoxy resin and then bonding a silicon resin on the
epoxy resin or forming an adhesion fixation layer by an
urethane resin and then bonding another urethane resin
having a low hardness on the urethane resin. As
bonding methods, publicly known methods such as
centrifugal bonding method and stationary bonding
method are known. To improve the shrinkage on curing
or strength of an adhesive, it is also allowed to
include a fiber-like object such as glass fiber or
carbon fiber or fine powder such as carbon black,
alumina, or silica in the above adhesive.
Materials of housings of the upper-side
adhesion fixation section 2 and the lower-side adhesion
fixation section 3 and the catchment chambers 9 and 11
are not particularly limited and they may be the same

or different. However, thermoplastic resin or
stainless steel is preferably used.
In the present invention, as shown in
examples of Figs. 4(a) to 4(c), the arrangement of
small bundles of hollow fiber membranes on the
filtration section-side interface of an upper-side
adhesion fixation layer, irregularity is allowed as
shown in Fig. 4(a) but it is preferable to linearly
arrange the small bundles at equal intervals as shown
in Fig. 4(b). Moreover, as shown in Fig. 4(c), the
small bundles may be divided into plural rows. It is
possible that the shape of a small bundle is not
circular or sizes of small bundles are not equal.
[Examples]
Examples of the present invention are
described below. However, the present invention is not
restricted to the examples.
Example 1
Two cylindrical pipes 21 having a diameter of
1 cm and a length of 80 cm shown in Fig. 5(a) were
arranged in parallel by keeping a distance of 2 m from
each other to form a winding cassette and wound hollow
fiber membranes 22. The pipes 21 were wound by
rotating them at 1,650 times while adjusting a winding
position so that hollow fiber membranes became small
bundles at the one pipe side and became a single bundle
at the other pipe side. As shown in Fig. 5(b),

traverse was conducted when winding the hollow fiber
membrane 22 so that the bundle was divided from the
side which became the lower position of a cartridge
toward the side which became the upper position of the
cartridge and confounding occurs between hollow fiber
membranes.
Each of cylindrical pipes at the both ends on
which hollow fiber membranes were wound was stationary-
bonded in a housing 23 made of ABS resin by using a
urethane resin 24 (made by SANYUREKKUSU Inc. "SA-6330
type"; hardness after curing: 98A) serving as an
adhesion fixation layer in the ABS-resin housing 23.
Thereafter, urethane resin 25 (made by SANYUREKKUSU
Inc., "SA-6330 type"; hardness after curing: 56A) was
fixed on the interface between bonding portion and
nonbonding portion of hollow fiber membranes through
stationary bonding.
A measuring method of resin hardness
conformed to JIS K6253. Along the cutting direction 26
shown in Fig. 5(c), a housing, a urethane resin, and a
cylindrical pipe were cut. The state of one of the cut
cylindrical pipe was the end face shown in Fig. 5(d)
and the other one of the cut cylindrical pipe was the
state shown in Fig. 5(e). A catchment chamber and a
catchment pipe were connected to each of the cut
surfaces while keeping the hollow fiber membranes open.
It is possible to use any connection method as long as
connection is liquid-tightly made.

A hollow fiber membrane was a precise
filtering membrane made of polyvinylidene fluoride and
having a small hole diameter of 0.1 µm, outside
diameter of about 1.25 mm, and inside diameter of 0.7
mm and the membrane area of the membrane cartridge was
25 m2. A small bundle was formed by 110 hollow fiber
membranes per bundle at the filtration section-side
interface of the upper adhesion fixation layer and 30
small bundles were present. The distance between
nearest small bundles was 5 mm.
In the connection of two pipes of the winding
cassette, an upper-side adhesion fixation section and a
lower-side adhesion fixation section were connected and
fixed by using two pipes each one of which was obtained
by covering a pipe made of SUS304 and having an outside
diameter of 13 mm with a vinylidene chloride film.
An aeration bubble supply section was set to
a position 5 cm lower than the lower-side adhesion
fixation layer.
A hollow fiber membrane cartridge produced
thereby was immersed in an activated sludge tank having
a volume of 8 m3, and the catchment chamber of the upper
adhesion fixation layer and a filtrate pipe were
connected, and fixed to the activated sludge tank.
Suction filtration was conducted using a
suction pump so that a membrane-filtration flow rate is
0.6 m3/membrane area m2/day while aerating air of 10
Nm3/hr from the aeration bubble supply section to the

hollow fiber membrane cartridge. The differential
pressure between membranes in this case ranged between
-15 and -20 kPa and was stable for three months. The
concentration MLSS in the activated sludge tank in the
evaluation period was 10000 mg/1 on average and the
average temperature was 25°C. City sewage water having
an average BOD of 150 mg/1 and SS of 160 mg/1 was used
for the raw water of activated sludge.
The weight of the sludge fouling or
contaminants attached to the cartridge after operation
was 0.84 kg and it was found that the attached quantity
was small. Weights of the cartridge before and after
operation were measured for wet hollow fiber membranes
and the weight difference was defined as the weight of
sludge fouling or contaminants.
Example 2
Two cylindrical pipes 21 having a diameter of
1 cm and a length of 80 cm shown in Fig. 5(a) were
arranged in parallel by keeping a distance of 1.4 m
from each other to form a winding cassette and wound
hollow fiber membranes 22. The winding method, the
bonding and fixing method by urethane resin and the
cutting method were conducted in the same manner as in
Example 1.
Open were end surfaces of the hollow fiber
membranes at the side where small bundles of the hollow
fiber membranes were constituted, while close were the

oppsite end surfaces of the hollow fiber membranes at
the side where the end surfaces were buried inside the
urethane resin. A catchment chamber and a catchment
pipe were connected only to the end surfaces of the
hollow fiber membranes at the side where small bundles
of the hollow fiber membranes were constituted. The
hollow fiber membranes were the same as those used in
Example 1. The membrane area of the hollow fiber
membrane cartridge was 17.5 m2. A small bundle was
formed by 110 hollow fiber membranes per bundle at a
filtration section-side interface of the upper adhesion
fixation layer and 30 small bundles were present. The
distance between nearest small bundles was 5 mm.
In the connection of two pipes of the winding
cassette, an upper-side adhesion fixation section and a
lower-side adhesion fixation section were connected and
fixed by using two pipes each one of which was covering
a pipe made of SUS304 and having an outside diameter of
13 mm with a vinylidene chloride film.
An aeration bubble supply section was set to
a position 5 cm lower than the lower-side adhesion
fixation layer.
A hollow fiber membrane cartridge produced
thereby was immersed in an activated sludge tank having
a volume of 8 m3, and the catchment chamber of the upper
adhesion fixation layer and a filtrate pipe were
connected, and fixed to the activated sludge tank.
Suction filtration was conducted using a

suction pump so that a membrane-filtration flow rate is
0.6 m3/membrane area m2/day while aerating air of 10
Nm3/hr from the aeration bubble supply section to the
hollow fiber membrane cartridge. The differential
pressure between membranes in this case ranged between
-15 and -20 kPa and was stable for three months. The
concentration MLSS in the activated sludge tank in the
evaluation period was 10000 mg/1 on average and the
average temperature was 25°C. City sewage water having
an average BOD of 150 mg/1 and SS of 160 mg/1 was used
for the raw water of activated sludge.
The weight of the sludge fouling or
contaminants attached to the cartridge after operation
was determined in the same manner as in Example 1. As
a result, the weight was 0.65 kg and it was found that
the attached quantity was small.
Example 3
The hollow fiber membranes, the number
thereof and the housing which are the same as those of
Example 1 were used and all hollow fiber membranes were
collected to one bundle and they are entwined to a
state in which there was confounding between hollow
fiber membranes. Thereafter, the hollow fiber
membranes at one end were divided into the bundles
shown in Fig. 4(b) and the other end was divided as
shown in Fig. 4(c). Under this state, stationary
bonding was carried out together with the catchment

chamber, the catchment pipe, and the housing using the
same resin as that used in Example 1. The bonding was
conducted while keeping both ends of the hollow fiber
membranes open. The procedure after that was carried
out similarly to Example 1.
As a result of carrying out the same
evaluation as the case of Example 1, the differential
pressure between membranes ranged from -15 and -21 kPa
and it was stable for three months. Moreover, the
sludge fouling or contaminants attached to the
cartridge after operation was 0.78 kg and it was found
that the attached quantity is small.
Comparative Example 1
Evaluation was made by an activated sludge
tank in the same filtration conditions as the case of
the Example 1 except that the arrangement of hollow
fiber membranes on the filtration section-side
interface of the upper-side adhesion fixation layer was
not divided into small bundles but it was formed into a
single bundle structure.
In this case, the differential pressure
between membranes suddenly rises for 14 days, reached
up to -80 kPa, and pump suction becomes impossible.
Similarly to the case of Example 1, the
concentration MLSS in the activated sludge tank in the
evaluation period was 10000 mg/1 on average and the
average temperature was 25°C. City sewage water having

average BOD of 150 mg/1 and SS of 160 mg/1 was used for
the raw water of activated sludge.
The weight of sludge fouling or contaminants
attached to the cartridge after operation was 6.4 kg
and it was found that the fouling weight was extremely
large.
Comparative Example 2
Evaluation was made by an activated sludge
tank in the same filtration conditions as the case of
the Example 2 except that the arrangement of hollow
fiber membranes on the filtration section-side
interface of the upper-side adhesion fixation layer was
not divided into small bundles but it was formed into a
single bundle structure.
In this case, the differential pressure
between membranes suddenly rises for 12 days, reached
up to -80 kPa, and pump suction becomes impossible.
Similarly to the case of Example 2, the
concentration MLSS in the activated sludge tank in the
evaluation period was 10000 mg/1 on average and the
average temperature was 25°C. City sewage water having
average BOD of 150 mg/1 and SS of 160 mg/1 was used for
the raw water of activated sludge.
The weight of sludge fouling or contaminants
attached to the cartridge after operation was 5.7 kg
and it was found that the fouling weight was extremely
large.

INDUSTRIAL APPLICABILITY
The hollow fiber membrane cartridge of the
present invention can be preferably used in the field
of membrane filtration, in particular for a suction-
type tank filtration device or an immersion-type
filtration device.

WE CLAIM :
1. A hollow fiber membrane (22) cartridge comprising a hollow fiber
membrane bundle (1) consisting of plural hollow fiber membranes and
arranged in vertical direction in an immersion bath and adhesion fixation
layers for adhering and fixing the hollow fiber membrane bundle (1) at the
both ends, and in which the hollow portions of the hollow fiber
membranes (22) open at at least the end of an upper-side adhesion fixation
layer (4) and the hollow fiber membrane bundle is in a state of plural
small bundles on the filtration section-side interface of the upper-side
adhesion fixation layer and divided into plural small bundles between the
lower-side adhesion fixation layer (5) and the upper-side adhesion fixation
layer (4) and there is confounding between hollow fiber membranes.
2. The hollow fiber membrane cartridge claimed in claim 1, wherein the
plural small bundles of hollow fiber membranes (22) on the filtration
section-side interface of the upper-side adhesion fixation layer(15), the
distance between the nearest hollow fiber membranes is less than 2 mm in
each small bundle, and the number of hollow fiber membranes (22)
constituting each small bundle is 10 or more and 1000 or less, and the
distance between the nearest small bundles is 2 mm or more and 100 mm
or less.

3. The hollow fiber membrane cartridge as claimed in claim 1, in which the
upper-side and lower-side adhesion fixation layers (5) include a resin,
respectively, and the hardness ( measured in accordance with JTS K6253)
of the resin at the filtration section-side interface(s) of either or both of the
adhesion fixation layers is 20 A or more and 90 A or less.
4. The hollow fiber membrane catridge as claimed in any one of claims 1 to
3, wherein the shape of the adhesion fixation layers is selected from the
group consisting of a triangle, rectangle, and hexagon.

ABSTRACT

Title : HOLLOW FIBER MEMBRANE CARTRIDGE
A hollow fiber membrane (22) cartridge comprising a hollow fiber membrane
bundle (1) consisting of plural hollow fiber membranes and arranged in vertical
direction in an immersion bath and adhesion fixation layers for adhering and
fixing the hollow fiber membrane bundle (1) at the both ends, and in which the
hollow portions of the hollow fiber membranes (22) open at at least the end of an
upper-side adhesion fixation layer (4) and the hollow fiber membrane bundle is in
a state of plural small bundles on the filtration section-side interface of the upper-
side adhesion fixation layer and divided into plural small bundles between the
lower-side adhesion fixation layer (5) and the upper-side adhesion fixation layer
(4) and there is confounding between hollow fiber membranes.

HOLLOW FIBER MEMBRANE CARTRIDGE

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