JPH11342321A - Hollow fiber membrane treating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hollow fiber membrane treating device in which operation can be performed while removing entanglement of retentate and entanglement of hollow fiber membranes themselves is preventing to enable long-term, stable operation which entanglement occurs when a hollow fiber membrane module is used in waste water treatment or the like. SOLUTION: In this hollow fiber membrane treating device wherein each of hollow fiber membrane modules 2 in which one end of a lot of hollow fiber membranes 3 is made a free end 4 and the other end thereof is made a fixed end at which the membranes are bundled and also which fixed end is connected to a water collecting part 5 and a protective member 7 is provided adjacent to the hollow fiber membranes 3 is arranged with the free end 4 and water collecting part 5 being made on the up and down sides respectively, the hollow fiber membrane modules 2 are arranged, substantially inclined with respect to the vertical direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber membrane treatment apparatus used for wastewater treatment and the like.

[0002]

2. Description of the Related Art Membrane separation technology includes reverse osmosis membranes, ultrafiltration membranes,
Research is being conducted mainly on applications that require high-quality water, such as desalination of seawater and brackish water, production of ultrapure water for cleaning semiconductors, and separation or concentration of food, using microfiltration membranes. Have been. However, recently, from the viewpoint of environmental conservation, research for applying the membrane separation technology to wastewater treatment has been advanced.

Since wastewater treatment often involves solid-liquid separation by sedimentation, if membrane separation technology can be used as an alternative, not only high-quality treated water can be obtained, but also the omission or reduction of a vast sedimentation tank. The space merits are very large. In wastewater treatment, an activated sludge treatment process is widely used in which microorganisms called activated sludge decompose organic matter in wastewater and then separate floculated sludge from treated water.

[0004] In this activated sludge treatment process, if the concentration of activated sludge is increased to increase the treatment efficiency, the decomposition treatment proceeds, but the sedimentation of the sludge may be poor in the sedimentation basin at the later stage. The management work for preventing the deterioration was complicated.

[0005] By utilizing membrane separation technology for solid-liquid separation of this sludge and treated water, even when high-concentration activated sludge treatment is carried out, the sedimentation basin can be omitted without deteriorating the water quality. Space saving. From such a point, the high concentration (M
(LSS: About 7,000 to 20,000 mg / L) Research on membrane separation technology for solid-liquid separation of activated sludge mixture has been conducted.

[0006] Meanwhile, separation membranes mainly include flat membranes, tubular membranes,
There are hollow fiber membranes and the like, and a separation membrane module more suitable for the system used has been developed.

[0007] For high-concentration solid-liquid separation, a cross-flow method is used in which raw water is circulated and supplied to a separation membrane module, and dirt adhering to the membrane surface is separated while being scraped off by a circulating flow.
Flat membrane and tubular membrane modules adapted to this method have been mainly used.

[0008] However, in this method, it is difficult to supply a high concentration of activated sludge into the separation membrane module. In addition, raw water is always applied to the membrane surface in order to scrape off the sludge adhering to the membrane surface. It had to be circulated and the power cost was high. For this reason, its use has been limited to some fields requiring advanced treatment in wastewater treatment such as reused water.

In recent years, the separation membrane module is immersed in a water tank and the permeate side of the module is suctioned by a pump, or treated water is obtained by utilizing a water level difference like a siphon or the like, so as to obtain an energy-saving immersion type separation membrane. Module research is being conducted. In activated sludge treatment, aeration is usually performed to breed aerobic microorganisms, and this immersion type uses a swirling flow formed in the water tank by aeration on the membrane surface to remove solids and liquid while removing dirt. Separation can be performed,
Operation is possible at very low cost.

In the flat membrane module, Japanese Patent Publication No. 4-7095
Although an apparatus as described in Japanese Patent Publication No. 8 is being trially used, when separating a high concentration of activated sludge, if a large amount of treated water per unit membrane area is taken, the adhesion of the sludge to the membrane surface proceeds rapidly. In addition, a large membrane area was required for mass processing.

On the other hand, the hollow fiber membrane module has a large membrane area per unit volume as compared with a flat membrane, and can be processed in a large amount in a compact manner. However, when the hollow fiber membrane module was used for wastewater treatment such as human waste treatment, it was found that very fine fibrous debris (waste) in the wastewater became entangled with the hollow fiber membrane. The large residue is removed by pretreatment etc., but when a hollow fiber membrane is used, very small residue that cannot be completely removed by the pretreatment becomes coarse due to entanglement in the hollow fiber membrane, Further, it was found that sludge had adhered thereon.

Once the residue is entangled with the hollow fiber membrane, it is difficult to remove the entanglement, and the entanglement gradually accumulates, and the sludge adheres to the entanglement. Sludge blocks between the hollow fiber membranes, and not only increases the filtration pressure difference, but also causes breakage of the hollow fiber membranes,
Use in activated sludge was difficult. Therefore, the present inventors have disclosed in Japanese Patent Application No. 9-297993 that the tip of the hollow fiber membrane is a free end and the entangled scum is removed from the tip to prevent entanglement and accumulation of the scum in wastewater. A hollow fiber membrane module was proposed.

[0013]

When the module is placed and operated in a water tank, that is, when the module is immersed in raw water in the water tank, the free end of the hollow fiber membrane is swirled by the swirling flow in the water tank. Entangled residue can be removed. On the other hand, when the operation is stopped and the water level in the water tank decreases, such as when discharging the raw water in the water tank, the hollow fiber membrane sinks down by its own weight, and when the water level rises again, The hollow fiber membrane may be disturbed.

When the hollow fiber membranes are disturbed or entangled with each other in the module, sludge and entanglement of the residue accumulate there, which hinders long-term stable operation.

In long-term operation, there is an opportunity to drain water from the water tank, and the water level may be lowered due to a failure of the equipment. In such a case, the hollow fiber membrane may be disturbed. Disturbance of some hollow fiber membranes is a major factor that lacks the reliability of the device in performing long-term stable operation, and it is an issue to solve this.

An object of the present invention is to provide a method for treating wastewater,
Provided is a hollow fiber membrane processing device that can be operated while removing the entanglement of residue, which occurs when a hollow fiber membrane module is used, and that can be operated stably for a long period of time by preventing the entanglement of the hollow fiber membrane itself. It is.

[0017]

The above objects are basically achieved by the following inventions. That is, "one end of the multiple hollow fiber membranes is a free end, the other end is a fixed end that is bundled, connected to the water collecting portion, and the protective member is adjacent to the hollow fiber membrane. The provided hollow fiber membrane module is a hollow fiber membrane treatment device in which a free end is located upward and a water collecting part is located downward, wherein the hollow fiber membrane module is substantially inclined with respect to a vertical direction. And a hollow fiber membrane treatment device characterized by being disposed. "

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic side view showing an example of a hollow fiber membrane processing apparatus according to the present invention. FIG. 2 is a schematic side view showing an example of the hollow fiber membrane treatment device according to the present invention when the water level has dropped.

In the hollow fiber membrane processing apparatus, a hollow fiber membrane module 2 is provided in a water tank 1 with a free end 4 of a hollow fiber membrane 3 above, a water collecting part 5
Is housed in the container 8 with the lower side. Each hollow fiber membrane module is arranged substantially inclined with respect to the vertical direction. As a result, as shown in FIG. 2, even when the water level in the water tank drops, the hollow fiber membrane 3 leans against the protection member 7 of the hollow fiber membrane module 2, and as a result, the hollow fiber membrane 3 sinks. To prevent.

In the hollow fiber membrane module 2, a pressure difference is generated on the membrane surface of the hollow fiber membrane module in the water tank by the separation means 10, and the raw water in the water tank is separated and treated water is taken out. 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 generated swirling flow, and in addition to the dirt, it becomes entangled with the hollow fiber membrane. Since it is arranged on the upper side, tangling does not accumulate and stable operation is possible.

FIG. 3 is a schematic front perspective view showing an example of a hollow fiber membrane module used in the hollow fiber membrane processing apparatus according to the present invention.

As shown in FIG. 3, a large number of hollow fiber membranes 3
Is 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 with an adhesive or the like so as to seal a gap between the hollow fiber membranes. The hollow fiber membrane module 2 is constructed by forming a water collecting part 5 for collecting treated water obtained through the inside of the hollow fiber membrane by attaching a water collecting member to the opening surface.

The free end 4 is in a state in which each hollow fiber membrane is capable of swinging independently without being restrained by anything. The membrane is not stuck and is free to move or end looped.

The state of the tip of the hollow fiber membrane which is the free end is preferably either sealed or open. If each hollow fiber membrane is a free end swinging freely,
The state of the tip is not particularly limited.

On the other hand, the other end is adhered and fixed, and the inside of the hollow fiber membrane is opened by cutting or the like to form a fixing part 6, and the water collecting part 5 is attached and obtained through the inside of the hollow fiber membrane. Collect the treated water. If the shape of the water collecting portion 5 attached to the other end is a thin plate shape, even when a large number of hollow fiber membranes are used,
It is preferable because a water flow can be applied to the entire hollow fiber membrane. However, the shape may be any shape as long as it can collect water, and the shape such as a round shape and a square shape is not particularly limited. Furthermore, in the hollow fiber membrane module 2, the protection member 7 is provided adjacent to the side of the hollow fiber membrane in the longitudinal direction, so that the hollow fiber membrane 3 leans on the protection member 7, and as a result, the hollow fiber membrane sinks. To prevent intrusion.
The protection member 7 is preferably provided only on the side surface, and is open at both ends in the longitudinal direction, so that raw water can flow through the hollow fiber membrane module 2.

The protection member 7 is mounted integrally with the hollow fiber membrane module 2 so that it 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 tubular shape is preferable as long as the hollow fiber membranes are simply bundled. When the hollow fiber membranes are arranged in a thin plate shape, a plate-like shape is preferable. It is also preferable to mount the cover so as to cover only the hollow fiber membrane portion, and it is also preferable to use a porous plate if it is a plate-like member. Any material other than the plate that supports the hollow fiber membrane may be used.
Rods are also preferred. There is no particular limitation as long as the hollow fiber membrane leans.

The treated water take-out section 11 takes out the separated treated water. It may be attached to the water collecting part 5 integrally, or it is preferable that it is a separate body as long as leakage can be prevented. As shown in FIG. 3, the one joined to the protection member 7 may be a nozzle provided in the water collecting part, and the shape and the like are not particularly limited.

As shown in FIG. 1, the hollow fiber membrane module 2 is disposed in the 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. .

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 arranged 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. In this case, the arrangement is easy if the modules are housed in a container. The container is open at the bottom to allow the upward flow to flow through the hollow fiber membrane module. Most preferably, the number of containers is not one, but is accommodated in a plurality of containers and arranged in groups. In the case of a large number of hollow fiber membrane modules, the arrangement becomes easy.

When the angle at which the hollow fiber membrane module is arranged is large with respect to the vertical direction, the hollow fiber membrane tends to lean.
However, on the other hand, if the angle is large, the effect of the upward flow is reduced, so it is important that the angle is as small as possible and the angle at which the hollow fiber membrane leans. Preferably it is 5 ° or more and 45 ° or less with respect to the vertical direction, and most preferably 5 ° or more and 20 ° or less.

In the water tank 1 used here, in the case of wastewater treatment, an activated sludge mixed solution, a coagulation treatment solution, and the like are stored as raw water. Raw water containing activated sludge is preferable because sludge can be maintained 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 the treatment, and is not particularly limited. The raw water may be supplied into the water tank every time the treatment is performed, but is preferably supplied continuously and stably. Further, 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 installed hollow fiber membrane module and has a volume capable of receiving raw water.

Therefore, by applying the upward flow of the swirling flow formed in the tank by the upward flow generating means 9 to the hollow fiber membrane module 2, the dirt adhering to the hollow fiber membrane 3 is removed and the residue is removed. The operation can be continued while removing the entanglement from the free end 4.

The upflow generating means 9 is preferably provided with a new propeller or the like and agitating the inside of the tank to apply an upflow to the hollow fiber membrane module. More preferably, the upflow is effectively provided by the existing stirring means or the like, so that the power cost can be reduced. When the activated sludge mixture is used as raw water in wastewater treatment or the like, aeration is used for aerobic biological treatment. Therefore, it is most preferable to form the upflow using aeration as shown in FIG. However, there is no particular limitation as long as it gives an upward flow.

The treated water obtained through the hollow fiber membrane is taken out by the separation means 10 connected directly or indirectly to the hollow fiber membrane module 2. Separation means 10 here
It is also preferable to use a suction means like a pump.
More preferably, a vacuum pump is used to assist the decompression unit provided in the permeation line, and it is most preferable to apply a pressure difference required for membrane permeation by a water level difference utilizing a water level in a water tank. . This method can greatly reduce the driving power.

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 capable of separation at low pressure. Any other type can be used as long as an external pressure type porous hollow fiber membrane is used, which removes dirt on the outer surface of the hollow fiber membrane and allows permeated water to flow toward the inner surface. Also, the film structure is not limited to a symmetric film, an asymmetric film, or the like.

The material of the hollow fiber membrane is not particularly limited as long as the hollow fiber is formed. Examples of the material include polyethylene, polypropylene, polysulfone, polyethersulfone, polyvinyl alcohol, cellulose acetate, and the like.
It is possible to use polyacrylonitrile, polytetrafluoroethylene, or the like. When used in wastewater treatment, the membrane surface is unlikely to become dirty even if used in high-concentration wastewater, as long as it is a hydrophilic membrane material. Examples of the hydrophilic film material include polyacrylonitrile, polyvinyl alcohol, cellulose acetate and the like, and it is preferable to use these.

Example 1 2,400 polyacrylonitrile hollow fiber membranes were arranged in a thin plate shape, and only one end was adhered and fixed in a thin plate shape by applying a urethane adhesive, and the fixed portion was cut. The inside of the hollow fiber membrane was opened. The water collecting member was attached to the fixed part by bonding. After connecting the vacuum pump to the water collecting part of the module, the permeate side is depressurized, and the polyacrylonitrile polymer is sucked from the hollow fiber membrane tip 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 line up the hollow fiber membrane on both sides of the hollow fiber membrane, and the shape was such that treated water could be taken out toward the tip of the hollow fiber membrane. Further, a plate-like protection member was attached to the square pipe by bonding. The protection member was attached so as to cover not only the hollow fiber membrane portion but also the entire module.
The three hollow fiber membrane modules (3.5 m ² ) were connected to a magnet gear pump as transmission means. The hollow fiber membrane is housed in a vertically open container such that the free end of the hollow fiber membrane is at the top and the other end is at the bottom, so that the angle to the vertical direction is 5 °,
It was placed in an aquarium. Two stainless steel air diffusers were disposed below the disposed container, and aeration was performed from this, and an upward flow was applied to the hollow fiber membrane module in the upper container.

An activated sludge mixed solution for industrial wastewater treatment (MLSS about 13,000 mg / L) is supplied to the 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. Permeated water was sucked by a pump so as to be ² / day, and 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. There were no turbulence or entanglement of the hollow fiber membrane at 16 drainage times.

Example 2 As in Example 1, the hollow fiber membrane module was housed in a container at 20 ° to the vertical direction.
It was placed in an aquarium. There were no turbulence or entanglement of the hollow fiber membrane at 16 drainage times, and there was no entanglement of the residue in the hollow fiber membrane module.

[Comparative Example] In the same manner as in Examples 1 and 2, when the hollow fiber membrane modules are arranged vertically and drained, the hollow fiber membranes are entangled by the two hollow fiber membrane modules at the fifth drainage. The remaining one hollow fiber membrane module also becomes entangled with the hollow fiber membrane at the ninth drainage, and the first two modules have a large amount of sludge attached to the entangled portion, and a large number of hollow fiber membranes are entangled. Had occurred.

[0042]

Industrial Applicability The hollow fiber membrane module which can take a large membrane area in a compact manner can be operated stably for a long period of time even in applications involving sewage such as wastewater treatment.

[Brief description of the drawings]

FIG. 1 is a schematic side view showing an example of a hollow fiber membrane processing apparatus according to the present invention.

FIG. 2 is a schematic side view showing an example of the hollow fiber membrane treatment device according to the present invention when the water level has dropped.

FIG. 3 is a schematic front perspective view showing an example of a hollow fiber membrane module used in the hollow fiber membrane processing device 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: Fixed part 7: Protective member 8: Vessel 9: Upflow generating means 10: Separating means 11: Treated water taking out part

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Masahide Taniguchi 1-1-1, Sonoyama, Otsu-shi, Shiga Prefecture Toga Co., Ltd. Shiga Plant (72) Inventor Hiromichi Okada 1-1-1, Sonoyama, Otsu-shi, Shiga Prefecture Toray Engineering Co., Ltd., Shiga Plant

Claims (6)

[Claims] (1) one end of a plurality of hollow fiber membranes is made a free end,
A hollow fiber membrane module whose other end is a fixed end that is bundled, is connected to the water collecting section, and is provided with a protective member adjacent to the hollow fiber membrane, has a free end facing upward, the water collecting section The hollow fiber membrane processing device, wherein the hollow fiber membrane module is disposed with the lower side of the hollow fiber membrane module being substantially inclined with respect to the vertical direction. 2. The hollow fiber membrane processing apparatus according to claim 1, wherein said 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 45 °. 3. The hollow fiber membrane processing apparatus according to claim 1, wherein the hollow fiber membrane module is arranged so that an angle with respect to a vertical direction is 5 ° or more and 20 ° or less. 4. The hollow fiber membrane processing apparatus according to claim 1, wherein an upflow generator is disposed below the hollow fiber membrane module. 5. The hollow fiber membrane module according to claim 1, wherein said hollow fiber membrane is a hollow fiber membrane module using a hydrophilic membrane material.
5. The hollow fiber membrane treatment device according to any one of 4. 6. The hollow fiber membrane treatment apparatus according to claim 1, wherein the raw water contains activated sludge.