JP3918304B2 - Hollow fiber membrane processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hollow fiber membrane treatment apparatus used for wastewater treatment or the like.
[0002]
[Prior art]
Membrane separation technology uses reverse osmosis membranes, ultrafiltration membranes, and microfiltration membranes to produce high-quality products such as seawater / brine desalination, production of ultrapure water for semiconductor cleaning, and food separation or concentration. Research has been focused on applications that require water. However, recently, from the viewpoint of environmental protection, research is being conducted to apply membrane separation technology to wastewater treatment.
[0003]
In many cases, wastewater treatment involves solid-liquid separation by precipitation, so if membrane separation technology can be implemented as an alternative, not only high-quality treated water can be obtained, but a large sedimentation basin can be omitted or reduced. The space merit is very large. In wastewater treatment, an activated sludge treatment process is widely used in which organic matter in wastewater is decomposed by microorganisms called activated sludge and then flocified sludge and treated water are separated.
[0004]
In this activated sludge treatment process, if activated sludge is increased in concentration to increase the treatment efficiency, the decomposition process proceeds, but sludge sedimentation may occur in the subsequent sedimentation basin, preventing deterioration of water quality. The management work to do was complicated.
[0005]
By using membrane separation technology for solid-liquid separation of this sludge and treated water, even when high-concentration activated sludge treatment is performed, the water quality is not deteriorated, and the sedimentation basin can be omitted, resulting in extremely space saving. Become. From such a point, research on the membrane separation technology for the solid-liquid separation application of the high concentration (MLSS about 7,000 to 20,000 mg / L) activated sludge mixture is being conducted.
[0006]
By the way, there are mainly flat membranes, tubular membranes, hollow fiber membranes and the like as separation membranes, and separation membrane modules suitable for the method used have been developed.
[0007]
For high-concentration solid-liquid separation, a cross-flow method is used in which raw water is circulated and supplied to the separation membrane module, and the dirt adhering to the membrane surface is removed by circulating flow. Membrane modules have been mainly used.
[0008]
However, this method makes it difficult to supply high-concentration activated sludge into the separation membrane module, and in order to scrape off the sludge adhering to the membrane surface, the raw water is always circulated and supplied to the membrane surface. It was necessary and the power cost was expensive. For this reason, use was limited to the field | area which requires some advanced treatments among wastewater treatments, such as reused water.
[0009]
In recent years, research on energy-saving immersion type separation membrane modules, in which a separation membrane module is immersed in a water tank and the permeate side of the module is sucked with a pump, or treated water is obtained using a water level difference like a siphon, etc. Has been done. In activated sludge treatment, aeration is usually performed to raise aerobic microorganisms. This immersion type uses a swirl flow formed in the water tank by aeration of the membrane surface, and while removing dirt, it is a solid liquid. Separation can be performed and operation is possible at a very low cost.
[0010]
In the flat membrane module, an apparatus as described in Japanese Patent Publication No. 4-70958 is being tried, but when separating high-concentration activated sludge, if the amount of treated water per unit membrane area is large, the membrane surface In addition, since sludge adheres rapidly, a large membrane area is required for mass treatment.
[0011]
On the other hand, the hollow fiber membrane module has a larger membrane area per unit volume than a flat membrane, and can be mass-processed in a compact manner. However, when the hollow fiber membrane module is used for wastewater treatment such as urine treatment, it has been found that very fine fibrous debris in the wastewater is entangled with the hollow fiber membrane. Large residues are removed by pretreatment, etc., but when hollow fiber membranes are used, very small residues that cannot be removed by pretreatment become entangled with the hollow fiber membranes, Furthermore, it became clear that the sludge adhered on it.
[0012]
Once the residue is entangled with the hollow fiber membrane, it is difficult to remove, and the entanglement gradually accumulates, and sludge adheres to the core as a core. Sludge clogs between the hollow fiber membranes, increasing not only the filtration differential pressure, but also causing breakage of the hollow fiber membranes, making it difficult to use in activated sludge. Therefore, in Japanese Patent Application No. 9-297993, the inventors of the present invention have a free end portion of the hollow fiber membrane and can remove the tangled residue from the distal end portion to prevent the tangled residue and the accumulation in the waste water. A hollow fiber membrane module was proposed.
[0013]
[Problems to be solved by the invention]
When this module is placed and operated in the water tank, that is, when it is immersed in the raw water in the water tank, it can remove entanglements and the like entangled from the free end of the hollow fiber membrane by the swirling flow in the water tank. On the other hand, when the water level in the aquarium drops, such as when the operation is stopped and the raw water in the aquarium is discharged, the hollow fiber membrane sinks downward due to its own weight, and when the water level rises again, The hollow fiber membrane may be disturbed.
[0014]
If this module causes turbulence of the hollow fiber membranes or entanglement between the hollow fiber membranes, sludge and stagnation of the sludge accumulate there, preventing continuous long-term operation stability.
[0015]
In long-term operation, there is an opportunity to discharge water in the water tank, and the water level may be lowered due to equipment failure. In such a case, the hollow fiber membrane may be disturbed. Disturbance of some hollow fiber membranes is a major factor that lacks device reliability in long-term stable operation, and there is a problem to solve this.
[0016]
It is an object of the present invention to be able to operate while removing the tangled residue that occurs when using a hollow fiber membrane module in wastewater treatment and the like, and to prevent the entanglement of the hollow fiber membrane itself and stably operate for a long period of time. The present invention provides a possible hollow fiber membrane treatment apparatus.
[0017]
[Means for Solving the Problems]
The above object is basically achieved by the following invention.
That is, “one end of a large number of hollow fiber membranes is a free end, the other end is a fixed end bundled, and is connected to a water collecting portion, and a protective member is adjacent to the hollow fiber membrane. the hollow fiber membrane module is provided, the free end upper, a hollow fiber membrane treatment apparatus disposed in the lower side of the water collecting portion, an angle against the hollow fiber membrane module in the vertical direction more than 5 °, A hollow fiber membrane treatment apparatus characterized by being disposed at an angle of 45 ° or less . ”
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail based on examples shown in the drawings, but the present invention is not limited to these examples.
[0019]
FIG. 1 is a schematic side view showing an example of a hollow fiber membrane treatment apparatus according to the present invention. FIG. 2 is a schematic side view showing an example of the hollow fiber membrane treatment apparatus according to the present invention when the water level is lowered.
[0020]
In the hollow fiber membrane treatment apparatus, a hollow fiber membrane module 2 is accommodated in a container 8 in a water tank 1 with the free end 4 of the hollow fiber membrane 3 on the upper side and the water collecting part 5 on the lower side. Each of the hollow fiber membrane module vertically against angle of 5 ° or more, 45 ° are arranged inclined so that less. As a result, as shown in FIG. 2, even when the water level in the water tank is lowered, the hollow fiber membrane 3 leans against the protective member 7 of the hollow fiber membrane module 2, and as a result, the hollow fiber membrane 3 sinks. To prevent.
[0021]
The hollow fiber membrane module 2 causes the separation means 10 to generate a pressure difference on the membrane surface of the hollow fiber membrane module in the water tank, separates the raw water in the water tank, and takes out the treated water. The upward flow generating means 9 is provided below the hollow fiber membrane module in the water tank and generates a swirling flow. The dirt that is removed during the separation and adheres to the membrane surface is scraped off by the upward flow of the swirling flow that is generated, and in addition to the dirt, it gets entangled with the hollow fiber membrane. Since it is arranged on the upper side, entanglement does not accumulate and stable operation is possible.
[0022]
FIG. 3 is a schematic front perspective view showing an example of a hollow fiber membrane module used in the hollow fiber membrane treatment apparatus according to the present invention.
[0023]
As shown in FIG. 3, the multiple hollow fiber membranes 3 are filled and fixed with an adhesive or the like so that one end is a free end 4 that is not fixed to each other and the other end is sealed between the hollow fiber membranes. The inside of the hollow fiber membrane is opened by cutting or the like at the fixed end 6, a water collecting member is attached to the opening surface, and the water collecting portion 5 for collecting treated water obtained through the inside of the hollow fiber membrane is formed. The hollow fiber membrane module 2 is configured.
[0024]
The free end 4 is in a state in which each hollow fiber membrane is independently restrained without any restraint, and can be restrained by providing a support member or a plurality of hollow fiber membranes can be caught. It does not move freely or end in a loop.
[0025]
Moreover, the state of the front-end | tip part of the hollow fiber membrane used as a free end is what has sealed and what is open | released. The state of the tip is not particularly limited as long as each hollow fiber membrane freely swings.
[0026]
On the other hand, the other end is bonded and fixed, and the inside of the hollow fiber membrane is opened by cutting or the like to form a fixing portion 6, the water collecting portion 5 is attached, and the treated water obtained through the inside of the hollow fiber membrane is removed. Gather. If the shape of the water collecting portion 5 attached to the other end is a thin plate, it is preferable that a water flow can be imparted to the entire hollow fiber membrane even when a large number of hollow fiber membranes are used. However, the shape is not particularly limited as long as it is a shape capable of collecting water, such as a round shape and a square shape. Further, the hollow fiber membrane module 2 is provided with a protective member 7 adjacent to the side of the hollow fiber membrane in the longitudinal direction, so that the hollow fiber membrane 3 leans against the protective member 7, and as a result, the hollow fiber membrane sinks. To prevent intrusion. In addition, it is preferable that the protective member 7 is provided only on the side surface, and the raw water can flow through the hollow fiber membrane module 2 by being open at both ends in the longitudinal direction.
[0027]
The protective member 7 is attached integrally with the hollow fiber membrane module 2, and can be handled without damaging the hollow fiber membrane. The shape may be appropriately selected depending on the shape of the hollow fiber membrane bundle, and a cylindrical shape is preferable if the hollow fiber membranes are simply bundled. When the hollow fiber membranes are arranged in a thin plate shape, a plate shape is preferable. It is also preferable that it is attached so as to cover only the hollow fiber membrane part, and if it is plate-shaped, a porous one is also preferable. In addition to the plate, it may be anything that supports the hollow fiber membrane, and a net-like or rod-like one is also preferable. The hollow fiber membrane is not particularly limited as long as it leans against it.
[0028]
Moreover, the treated water extraction part 11 takes out the separated treated water. It may be attached integrally with the water collection part 5, and if it can prevent a leak etc., it is also preferable that it is a different body. As shown in FIG. 3, what is joined to the protective member 7 may be a nozzle provided in the water collecting portion, and the shape and the like are not particularly limited.
[0029]
As shown in FIG. 1, the hollow fiber membrane module 2 is arranged in a water tank 1 with the free end 4 of the hollow fiber membrane 3 on the upper side and the water collecting part 5 on the lower side at a predetermined angle with respect to the vertical direction.
[0030]
In FIG. 1, a plurality of hollow fiber membrane modules are housed in a container, but it is also preferable that each hollow fiber membrane module is disposed at a predetermined angle with respect to the vertical direction. However, it is more preferable to arrange all the hollow fiber membrane modules at a certain angle, and in this case, the arrangement is easy if they are accommodated in a container. The container is open at the bottom, allowing the upward flow to flow through the hollow fiber membrane module. Most preferably, the number of containers is not one, but they are accommodated in a plurality of containers and arranged for each group. In the case of a large amount of hollow fiber membrane modules, the arrangement becomes easy.
[0031]
Angle to arrange the hollow fiber membrane module, the size Ihodo hollow fiber membranes with respect to the vertical direction is likely to lean against. However, on the other hand if there at an angle too large, because the effect of the upward flow was reduced, at an angle can Rukoto is middle hollow fiber membrane Motarekaka, and an as small as possible angle. Specifically, 5 ° or more with respect to the vertical direction, and 45 ° or less under an angle. Good Mashiku is 5 ° or more and 20 ° or less.
[0032]
In the water tank 1 used here, an activated sludge mixed solution, an agglomeration treatment solution, and the like are stored as raw water for wastewater treatment. Raw water containing activated sludge is preferable because the sludge can be kept at a high concentration by the hollow fiber membrane and the treatment capacity can be increased. However, the type of raw water varies depending on the purpose of treatment, and is not particularly limited. The raw water may be supplied into the water tank every time it is treated, but it is preferable that the raw water is supplied continuously and stably. Moreover, the hollow fiber membrane module 2 may be immersed in an existing water tank, or a separate water tank may be provided as a water tank, and raw water may be transferred by a pump or the like. The size of the water tank is not particularly limited as long as it can accommodate the hollow fiber membrane module to be installed and has a volume capable of receiving raw water.
[0033]
Therefore, the hollow fiber membrane module 2 is given an upward flow of swirl flow formed in the tank by the upward flow generation means 9, thereby removing the dirt adhering to the hollow fiber membrane 3 and entanglement of the residue. Operation can be continued while removing from the free end 4.
[0034]
It is preferable that the upward flow generating means 9 is provided with a propeller or the like and agitates the inside of the tank to give the upward flow to the hollow fiber membrane module. More preferably, the power cost can be reduced by effectively giving the upward flow by the existing stirring means or the like. When the activated sludge mixed solution is used as raw water for wastewater treatment or the like, aeration is used for aerobic biological treatment. Therefore, it is most preferable to form an upward flow using aeration as shown in FIG. However, there is no particular limitation as long as it gives an upward flow.
[0035]
The treated water obtained through the hollow fiber membrane is taken out by the separating means 10 connected directly or indirectly to the hollow fiber membrane module 2. The separation means 10 here is preferably a suction means such as a pump. More preferably, the pressure reducing part provided in the permeation line is assisted by a vacuum pump, and most preferably, the pressure difference required for membrane permeation is most preferably applied by the water level difference utilizing the water level in the water tank. . With this method, driving power can be greatly reduced.
[0036]
The hollow fiber membrane 3 used in the hollow fiber membrane module 2 of the present invention is suitably an ultrafiltration membrane or a microfiltration membrane, and may be a reverse osmosis membrane that can be separated at a low pressure. As long as an external pressure type porous hollow fiber membrane in which dirt is removed on the outer surface of the hollow fiber membrane and permeate flows toward the inner surface is used, the type beyond that is not particularly limited. Also, the symmetric film and the asymmetric film are not limited in the film structure.
[0037]
Furthermore, the hollow fiber membrane material is not particularly limited as long as a hollow fiber can be formed, but polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinyl alcohol, cellulose acetate, polyacrylonitrile, polytetrafluoroethylene, etc. It is possible to use. When used in wastewater treatment, if the membrane material is hydrophilic, the membrane surface is difficult to get dirty even when used in high-concentration wastewater. Examples of the hydrophilic film material include polyacrylonitrile, polyvinyl alcohol, and cellulose acetate, and these are preferably used.
[0038]
[Example 1]
2,400 polyacrylonitrile hollow fiber membranes were arranged in a thin plate shape, one end was bonded and fixed in a thin plate shape in a mold by applying urethane adhesive, the fixed portion was cut, and the hollow fiber membrane was opened. . The water collecting member was attached to the fixed part by adhesion. At the end of the hollow fiber membrane that is open at the opposite end, a vacuum pump is connected to the water collecting part of the module, the permeate side is decompressed, and the polymer of polyacrylonitrile is sucked from the tip of the hollow fiber membrane and sucked to a predetermined position. The tip was immersed in water and solidified, and the tip was sealed. A square pipe was connected to the water collecting member so as to be aligned with the hollow fiber membrane on both sides of the hollow fiber membrane, and the water collecting member was directed toward the tip of the hollow fiber membrane so that treated water could be taken out. Further, a plate-shaped protective member was attached to the square pipe by bonding. The protective member was attached so as to cover not only the hollow fiber membrane part but the entire module. Three hollow fiber membrane modules (3.5 m ² ) were connected to a magnet gear pump as permeation means. The hollow fiber membrane was accommodated in an open container in the vertical direction so that the free end of the hollow fiber membrane was up and the other end was down so that the angle with respect to the vertical direction was 5 °, and placed in a water tank. Two stainless steel diffuser tubes were arranged below the arranged container, and aeration was performed from here to give an upward flow to the hollow fiber membrane module in the upper container.
[0039]
The activated sludge mixed solution (MLSS about 13,000 mg / L) for industrial wastewater treatment is supplied to this water tank, and the inside of the tank is aerated at 30 l / min as aeration, and the membrane permeation flux is 0.4 m ³ / m ² / day. The permeated water was sucked with a pump so that a quantitative operation was performed. The liquid in the water tank was discharged every day, and at that time, the tilting means was operated to observe whether the hollow fiber membrane bundle of the hollow fiber membrane module was disturbed. It was observed whether the residue was entangled. The hollow fiber membrane was not disturbed or entangled after 16 times of drainage.
[0040]
[Example 2]
In the same manner as in Example 1, the hollow fiber membrane module was accommodated in a container at 20 ° with respect to the vertical direction and placed in a water tank. The hollow fiber membrane was free from turbulence and entanglement after 16 times of drainage, and the hollow fiber membrane module was free from residue.
[0041]
[Comparative example]
Similarly to Examples 1 and 2, when the hollow fiber membrane module is disposed in the vertical direction and drainage is performed, the hollow fiber membrane is entangled with the two hollow fiber membrane modules when the drainage is performed five times, and the drainage is performed nine times. The remaining one hollow fiber membrane module also entangled the hollow fiber membrane, and the first two modules had a large amount of sludge adhering to the entangled portion, and many hollow fiber membranes entangled.
[0042]
【The invention's effect】
The hollow fiber membrane module, which can take a compact and large membrane area, was able to operate stably for a long period of time even in applications where stagnation is involved, such as in wastewater treatment.
[Brief description of the drawings]
FIG. 1 is a schematic side view showing an example of a hollow fiber membrane treatment apparatus according to the present invention.
FIG. 2 is a schematic side view showing an example of the hollow fiber membrane treatment apparatus according to the present invention when the water level is lowered.
FIG. 3 is a schematic front perspective view showing an example of a hollow fiber membrane module used in the hollow fiber membrane treatment apparatus according to the present invention.
[Explanation of symbols]
1: Water tank 2: Hollow fiber membrane module 3: Hollow fiber membrane 4: Free end 5: Water collecting part 6: Fixing part 7: Protection member 8: Container 9: Upflow generating means 10: Separating means 11: Treated water take-out part

Claims (5)

One end of a plurality of hollow fiber membranes is a free end, the other end is a fixed end bundled, and is connected to a water collecting portion, and a protective member is provided adjacent to the hollow fiber membrane the hollow fiber membrane module, the free end upper, a hollow fiber membrane treatment apparatus disposed in the lower side of the water collecting portion, an angle against the hollow fiber membrane module in the vertical direction more than 5 °, 45 ° or less A hollow fiber membrane treatment apparatus, which is disposed so as to be inclined.   The hollow fiber membrane treatment apparatus according to claim 1, wherein the hollow fiber membrane module is arranged so that an angle with respect to a vertical direction is not less than 5 ° and not more than 20 °. The hollow fiber membrane treatment apparatus according to claim 1 or 2 , wherein an upward flow generating means is disposed below the hollow fiber membrane module. The hollow fiber membrane treatment apparatus according to any one of claims 1 to 3, wherein the hollow fiber membrane is a hollow fiber membrane module using a hydrophilic membrane material. Raw fiber water contains activated sludge, The hollow fiber membrane processing apparatus in any one of Claims 1-4 characterized by the above-mentioned.

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