JP2004216263A - Hollow fiber membrane filter and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow fiber membrane filter by which removed stain or particles are prevented from re-sticking to a membrane surface to positively discharge the removed stain or the particles after effective back washing. <P>SOLUTION: The hollow fiber membrane comprises: a housing 2 housing a hollow fiber membrane 3; a raw water supply conduit 7; an overflow conduit 15; a treatment water conduit 17; A drainage conduit 9; and a back wash air supply conduit 19. The treatment water conduit 17 derives treatment water obtained by filtering raw water through the hollow fiber membrane 3 from the housing 2 and is openably provided with a treatment water outlet valve 18. The back wash air supply conduit 19 is connected to the treatment water conduit 17 at the housing 2 side remote from the treatment water outlet valve 18. In a state retaining the treatment water in the treatment water conduit 17 by closing the treatment water outlet valve 18, pressure by air is applied plural times to the retaining section to conduct air push back washing returning the treatment water in the retaining section through the hollow fiber membrane 3 to the raw water side. Draining the treatment water to the drainage conduit 9 from the housing 2 is accompanied by bubbling. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a hollow fiber membrane filtration device and a method for operating the same.
[0002]
[Prior art]
The hollow fiber membrane filtration device is used to obtain treated water by filtering raw water through a hollow fiber membrane in order to remove bacteria (bacteria) and fine suspended substances (SS) such as iron in raw water. is there. In this hollow fiber membrane filtration device, dirt and particles adhere to the hollow fiber membrane during filtration. It is necessary to wash to prevent clogging.
[0003]
Conventional methods for washing such hollow fiber membranes include backwashing, in which the liquid is returned from the treated water side to the raw water side in the opposite direction to the filtration, and washing, and bubbling, in which the hollow fiber membrane is shaken with air bubbles and washed, and the like. Are known. Further, as disclosed in Patent Literature 1 below, there is also known a method of applying a gas pressure to treated water and returning the treated water to the raw water side for cleaning.
[0004]
[Patent Document 1]
JP-A-10-286441
[0005]
[Problems to be solved by the invention]
However, in the conventional hollow fiber membrane filtration device, the backwash is performed only once after the filtration operation, and only a constant constant pressure is applied. For this reason, depending on the degree of adhesion of dirt, insufficient backwashing occurs, and there is a possibility of early clogging. Further, even if dirt and particles can be removed from the hollow fiber membrane by washing, the dirt and particles cannot be discharged to the outside of the housing well, and there is a possibility that the dirt and particles may be reattached to the membrane surface.
[0006]
The present invention has been made in view of the above circumstances, and its main purpose is to enable effective backwashing, and to reattach dirt and particles removed by backwashing or bubbling to the film surface. It is an object of the present invention to provide a hollow fiber membrane filtration device capable of reliably discharging the outside of the housing while preventing such a situation, and an operation method thereof.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the hollow fiber membrane filtration device of the present invention is provided with the following constituent features (A) to (E).
(A) Housing housing hollow fiber membrane.
(B) A raw water supply pipe capable of supplying raw water to the housing.
(C) A treated water pipe for extracting treated water obtained by filtering raw water through a hollow fiber membrane from a housing.
(D) A drainage pipe capable of discharging raw water from the lower part of the housing.
(E) a bubbling air supply which is connected to a raw water supply pipe or a drain pipe or a housing at a lower part of the housing and supplies air so that bubbles can be ejected from the lower part of the housing into the housing when draining from the housing to the drain pipe; Pipeline.
[0008]
According to this configuration, in the draining step, the water in the housing can be drained (blown) while bubbling. Bubbling during drainage prevents suspended solids from re-adhering.
[0009]
Further, the hollow fiber membrane filtration device of the present invention is characterized by having the following constituent requirements (A) to (E).
(A) Housing housing hollow fiber membrane.
(B) A raw water supply pipe capable of supplying raw water to the housing.
(C) A treated water pipe in which treated water obtained by filtering raw water through a hollow fiber membrane is led out of a housing, and a treated water outlet valve is provided so as to be openable and closable.
(D) A drainage pipe capable of discharging raw water from the lower part of the housing.
(E) A state in which the treated water is connected to the treated water pipe on the housing side or the treated water section of the housing from the treated water outlet valve, the treated water outlet valve is closed, and the treated water is retained in the treated water pipe or the treated water section of the housing. A backwash air supply line for performing air-pressed backwashing by returning the treated water in the staying portion to the raw water side through the hollow fiber membrane by applying a plurality of times of air pressure to the staying portion.
[0010]
According to this configuration, backwashing is performed in which the treated water is returned to the raw water side by the pressure of air in a direction opposite to that at the time of the filtration treatment, and the dirt attached to the surface of the hollow fiber membrane is removed. In the present specification, such backwashing is referred to as “air-pushed backwashing”. According to the air-pushed backwashing, a pump and its driving source are not required, and a backwashing water tank is not required as compared with a normal pump backwashing using a liquid. Moreover, by applying the air-push backwash not a single time but a plurality of times, the flow of the backwashing treatment water can be changed. In other words, by performing the pressurization with air a plurality of times, at the start of each backwash, the impact force of the air is applied to the backwashing treatment water, and effective cleaning of the hollow fiber membrane is expected.
[0011]
Preferably, in addition to the above configuration, an air push valve is provided in the backwash air supply line so as to be openable and closable, and the pressure on the housing side of the backwash air supply line is higher than that of the air push valve. The hollow fiber membrane filtration device is characterized in that the opening and closing operation is performed a plurality of times before the pressure becomes equal to the pressure on the compressor side from the valve, and the air pushing backwash is performed.
[0012]
In this configuration, before the pressure on the housing side from the air push valve becomes equal to the pressure on the compressor side from the air push valve, the air push valve can be opened and closed several times to perform multiple air push backwashes. Easy to implement. As described above, the situation of the adhered matter peeling off from the hollow fiber membrane surface is improved by the air pushing wavy backwashing.
[0013]
Further, the present invention provides a water filling step of supplying raw water into a housing containing a hollow fiber membrane, a filtration step of filtering raw water with a hollow fiber membrane to obtain treated water, a washing step of a hollow fiber membrane, The method of operating a hollow fiber membrane filtration device, wherein the draining step is sequentially performed, wherein the draining step is performed while jetting air bubbles from a lower portion of the housing. In this configuration, bubbling during drainage prevents re-adherence of suspended matter.
[0014]
Further, the present invention is a method for operating a hollow fiber membrane filtration device, comprising the following steps (a) to (e).
(A) A water filling step of supplying raw water into the housing in which the hollow fiber membrane is housed.
(B) A filtration step in which raw water supplied to the housing is filtered through a hollow fiber membrane to obtain treated water.
(C) While the overflow pipe of the raw water from the housing is opened and the treated water pipe from the housing is closed, pressure is applied to the treated water retaining section on the upper part of the housing by air, thereby retaining the treated water via the hollow fiber membrane. An air-pressed backwashing step of washing the hollow fiber membrane by returning the treated water of the section to the raw water side and draining it from the overflow conduit.
(D) A bubbling step of blowing air bubbles from a lower part of the housing to wash the hollow fiber membrane.
(E) A draining process in which air bubbles are ejected from the lower part of the housing and drained from the housing.
[0015]
Also in the case of this configuration, by performing bubbling in the draining step following the air pushing backwashing step and the bubbling step, removal of suspended substances and prevention of reattachment are achieved, and the effect of cleaning the hollow fiber membrane is improved. Then, in the air-pushed backwashing step, if the air-pushed backwash is performed a plurality of times, the effect of removing adhering matter from the hollow fiber membrane surface is further improved.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the hollow fiber membrane filtration device of the present invention and the operation method thereof will be described in more detail based on examples. In addition, the hollow fiber membrane filtration device of the present invention and the operation method thereof are not limited to the following examples, and it is needless to say that they can be appropriately changed without departing from the spirit of the invention.
[0017]
FIG. 1 is a schematic view showing a main part of one embodiment of the hollow fiber membrane filtration device of the present invention. The device of the present embodiment has a structure as shown in FIGS. 3 to 6 more specifically, as will be described later, but FIG. 1 schematically shows a main part thereof.
[0018]
As shown in this figure, the hollow fiber membrane filtration device includes one or more hollow fiber membrane modules 1 as a main part. Each hollow fiber membrane module 1 has a hollow fiber membrane 3 housed in a box-shaped housing 2. In this embodiment, the housing 2 has a housing lid 5 detachably provided at an upper opening of a substantially cylindrical housing body 4. The housing body 4 and the housing lid 5 are vertically divided via a partition plate 6, and a bundle of, for example, thousands of hollow fiber membranes 3 is suspended on the partition plate 6. It is held in the state that it was. In this embodiment, the lower end of the hollow fiber membrane 3 is held free. The configuration of the hollow fiber membrane 3 is not particularly limited, but in the present embodiment, for example, a high-precision hollow fiber membrane having a filtration accuracy of 0.02 μm is used.
[0019]
The housing 2 has a raw water side below the partition plate 6, that is, the housing body 4 side, and a treated water side above the partition plate 6, ie, the housing lid 5 side. That is, the raw water supplied to the housing 2 is filtered through the hollow fiber membrane 3 and can be led out to the upper part of the housing 2 as treated water.
[0020]
A raw water supply pipe 7, a bubbling air supply pipe 8, and a drain pipe 9 are connected to a lower end of the housing 2. Although these pipes 7 to 9 may be individually connected to the housing 2, in this embodiment, only the raw water supply pipe 7 is connected to the housing 2, and the bubbling air supply pipe is connected to the raw water supply pipe 7. The line 8 and the drainage line 9 are connected, and the distal end of the raw water supply line 7 is commonly used as the other lines 8 and 9.
[0021]
That is, the raw water supply pipe 7 is connected to the lower end of the housing 2, and the raw water from the raw water pump 10 can be supplied to the housing 2 via the raw water inlet valve 11 to the raw water supply pipe 7. Have been. Then, a drain pipe 9 is connected to the raw water supply pipe 7 on the housing 2 side from the raw water inlet valve 11. The drain pipe 9 is provided with a drain valve 12 that can be opened and closed. Further, a bubbling air supply line 8 is connected to the raw water supply line 7 at the lower part of the housing 2 at a position close to the housing 2. A bubbling valve 13 is provided in the bubbling air supply pipe 8 so as to be openable and closable, and the presence or absence of communication of pressurized air from the compressor 14 is switched.
[0022]
With such a configuration, when the raw water inlet valve 11 is closed and the drain valve 12 is opened, the water in the housing 2 can be discharged. On the other hand, when the raw water inlet valve 11 is opened and the drain valve 12 is closed, the raw water is closed. Raw water can be supplied from the pump 10 into the housing 2. In addition, when the bubbling valve 13 is opened and pressurized air is sent from the compressor 14 when supplying or discharging the raw water, the air can shake the hollow fiber membrane 3 in the housing 2 to perform bubbling. Further, when the raw water inlet valve 11 and the drain valve 12 are closed, the bubbling valve 13 is opened, and air is sent from the compressor 14, general bubbling can be performed. In addition, the drainage from the housing 2 is piped so as to be able to drain using the natural fall due to gravity.
[0023]
An overflow pipe 15 for overflowing and draining water excessively supplied to the housing 2 is connected to an upper portion of the housing body 4 on the raw water side. An overflow valve 16 is provided in the overflow pipe 15 so as to be openable and closable. In this embodiment, the overflow valve 16 is opened at the time of cleaning the hollow fiber membrane 3, that is, at the time of regeneration including an air pushing backwashing step, a bubbling step, a draining step, and a water filling step to be described later.
[0024]
A treated water pipeline 17 for extracting treated water filtered by the hollow fiber membrane 3 is connected to an upper portion of the housing lid 5 on the treated water side. The treated water pipe 17 is provided with a treated water outlet valve 18 so as to be openable and closable. A backwash air supply pipe 19 is connected to the treated water pipe 17 on the upstream side (the housing 2 side) of the treated water outlet valve 18. An air push valve 20 is provided in the backwash air supply pipe 19 so as to be openable and closable, and the presence or absence of communication of pressurized air from the compressor 14 is switched. In this embodiment, the backwash air supply pipe 19 is connected to the treated water pipe 17, but the backwash air supply pipe 19 may be directly connected to the housing lid 5.
[0025]
With this configuration, if the raw water inlet valve 11 and the treated water outlet valve 18 are opened and the other valves are closed, the raw water supplied from the raw water supply pipe 7 into the housing 2 will be hollow fiber membrane. The water is filtered at 3 and can be led out of the treated water line 17 as treated water. When the treated water outlet valve 18 is closed at the end of the filtration, the treated water stays in the treated water pipe 17 and the housing lid 5 on the upstream side of the treated water outlet valve 18. Then, in this state, when the air push valve 20 is opened with the overflow valve 16 opened, the pressurized air from the backwash air supply pipe 19 acts on the treated water in the stagnation portion, and the treated water is It is possible to perform an air-push backwash in which the water is pushed back to the raw water side and discharged to the overflow pipe 15. Then, in the filtration device of the present embodiment, the air of the air pushing and backwashing is impulsively applied a plurality of times.
[0026]
Hereinafter, the hollow fiber membrane filtration device of the present embodiment and the operation method thereof will be described more specifically.
FIG. 2 is a flowchart showing an operation method of the hollow fiber membrane filtration device of the present embodiment. 3 to 6 are views showing the use state of the hollow fiber membrane filtration device of this embodiment. FIG. 3 shows a water filling (water refilling) step, FIG. 4 shows an air pushing backwashing step, and FIG. 5 shows a bubbling step. FIG. 6 shows a drainage (blow) process. In each figure, a thick solid line indicates a flow of water, and a broken line indicates a flow of air. Further, a valve element painted black indicates a closed state, and a white valve element indicates an open state.
[0027]
Typically, the operation of the hollow fiber membrane filtration device of the present embodiment is performed by repeating the steps shown in FIG. That is, a water filling step, a filtration step, an air pushing backwashing step, a bubbling step, and a draining step are sequentially performed. Although details of each step will be described later, in the filtration step, the raw water is filtered, and the dirt and particles filtered in the filtration step are subjected to other steps (air pushing backwashing step, bubbling step, drainage step, water filling step), It is peeled off from the hollow fiber membrane, discharged out of the housing, and washed and regenerated. In the present embodiment, a hollow fiber membrane filtration device that applies external pressure to the hollow fiber membrane and filters the entire amount of raw water (external pressure total filtration) is used.
[0028]
FIG. 3 is a diagram showing a specific configuration of the hollow fiber membrane filtration device of the present embodiment, and shows a water filling process. In addition, in the figure, the main unit surrounded by the two-dot chain line is the main body of the hollow fiber membrane filtration device.
[0029]
In the present embodiment, four hollow fiber membrane modules 1 are used, but it is needless to say that this number is appropriately changed. Raw water is supplied to the housing 2 of each hollow fiber membrane module 1 from a raw water tank 21 via a raw water supply pipe 7. The raw water tank 21 is provided with a raw water tank level switch 22. The raw water in the raw water tank 21 is sent out to the raw water supply line 7 by the raw water pump 10, and is branched and supplied to each housing 2 after passing through the raw water flow control valve 23 and the raw water inlet valve 11. A drain pipe 9 is connected to the raw water supply pipe 7 on the housing 2 side from the raw water inlet valve 11, and the drain pipe 9 is provided with a drain valve 12.
[0030]
A bubbling air supply line 8 is connected to the raw water supply line 7 to each housing 2 at a position on the housing 2 side. Pressurized air from the compressor 14 is passed through the bubbling air supply line 8, and the pressurized air can be supplied to the raw water supply line 7 and the housing 2 via the bubbling valve 13. In the drawings, reference numeral 24 denotes a bubbling flow meter. The bubbling flow meter 24 of the present embodiment is a float indicating type instantaneous flow meter for measuring a bubbling air flow rate and visually checking whether a predetermined amount of air is flowing.
[0031]
An overflow pipe 15 is connected to each housing 2 in order to discharge overflow water on the raw water side. The overflow pipe 15 is connected to the drain pipe 9 via an overflow valve 16. At this time, it is connected downstream from the drain valve 12. In the drawings, reference numeral 25 denotes an air introduction valve. The air introduction valve 25 is for introducing air into the housing 2 at the time of drainage so that the inside of the housing 2 can be drained at atmospheric pressure.
[0032]
A treated water pipe 17 is connected to an upper portion of each housing 2 to discharge treated water. The treated water pipe 17 is connected to a treated water tank 26 via a treated water outlet valve 18. The treated water tank 26 is provided with a treated water tank level switch 27 for grasping the treated water amount.
[0033]
Further, a backwash air supply pipe 19 is connected to the treated water pipe 17 on the upstream side of the treated water outlet valve 18. The backwash air supply pipe 19 may be directly connected to the treated water section on the upper part of the housing 2, but is connected to the treated water pipe 17 in this embodiment. The backwash air supply pipe 19 is branched in the middle, one is connected to the drain pipe 9 via an air release valve 28, and the other is connected to the compressor 14 via an air push valve 20. .
[0034]
An air tank 29 is provided in the main body of the hollow fiber membrane filtration device of the present embodiment, and air from the compressor 14 can be stored in the air tank 29. The backwash air supply line 19 can discharge air from the air tank 29 to the treated water line 17 via the air filter 30, the regulator 31, the air pressure switches 32 and 33, and the air push valve 20. . The backwash air supply line 19 branches off at the air pressure switch 33 and is connected to the bubbling air supply line 8. In other words, the two air supply pipes 8 and 19 are shared at the base end, branch off in the middle, and one is the bubbling air supply pipe 8 and the other is the backwash air supply pipe 19.
[0035]
Pressurized air is supplied from the backwash air supply line 19 to the treated water line 17 for air pushing backwashing. The pressure of the air is appropriately set. In this embodiment, for example, the pressure resistance of the hollow fiber membrane is 3 kg / cm. ² The maximum differential pressure between the inside and outside of the membrane during normal operation is 1 to 1.5 kg / cm. ² About 2 kg / cm ² The degree is adopted. In order to stably supply the air, the filtration device body is provided with the above-described air tank 29. Air is stored in the air tank 29 at a pressure higher than the backwash air pressure. In this embodiment, for example, 5 kg / cm ² To store the air in the air tank 29. In this case, as the compressor 14, for example, 5 to 8 kg / cm ² The existing compressor can be used and there is no need to newly install a dedicated compressor.
[0036]
By storing the backwash air in the air tank 29, the size of the air source can be reduced, and the installation space can be reduced. In addition, energy saving in the cleaning step can be achieved due to the cleaning method described later.
[0037]
The high-pressure air stored in the air tank 29 passes through an air filter 30 and the like, and is then supplied to a regulator (pressure reducing valve) 31 at 2 kg / cm. ² And sent to the air push valve 20 side. On the way, two air pressure switches 32 and 33 for low pressure and high pressure are provided, and a pressure adjustment failure of the regulator 31 is detected. For example, 2kg / cm ² If the pressure is higher, there is a risk of damaging the hollow fiber membrane. ² In the case of a lower pressure, there is a possibility that cleaning may be defective due to back-washing with air, so that an alarm may be issued.
[0038]
As described above, in the filtration device of the present embodiment, 2 kg / cm ² By using the pressurized air described above, the treated water inside the device is flushed in the direction opposite to the direction of water flow during filtration (from inside to outside of the hollow fiber membrane), and the hollow fiber membrane is subjected to air-push backwash. Backwash air pressure is 2kg / cm ² However, in order to reduce the capacity of the air tank 29, the stored air pressure in the air tank 29 is 5 kg / cm. ² About. When the amount of treated water inside the device is about 14 L, it should be 2 kg / cm ² The air pressure of the air tank 29 is increased by about 2 to 3 times to 5 kg / cm. ² By doing so, the tank capacity of the air tank 29 can be reduced to about 7 L, which is about half.
[0039]
In addition, since the air is stored in the air tank 29 during an operation time (such as a filtration step) other than the time of the backwash, there is no need to separately provide a storage time. Further, the air supply amount from the compressor 14 can be about 120 L / min for the existing bubbling air supply. And even in that case, the storage time in the air tank 29 is about 30 seconds, which can cope with frequent backwashing.
[0040]
Now, in the hollow fiber membrane filtration device configured as described above, first, as shown in FIG. 3, a step of filling the housing 2 with water is performed. To do this, with the bubbling valve 13 and the drain valve 12 closed, the raw water inlet valve 11 is opened, and the raw water from the raw water pump 10 may be sent to the housing 2 via the raw water supply pipe 7.
[0041]
At the time of filling, the treated water outlet valve 18 of the treated water line 17 is closed. Further, the air push valve 20 of the backwash air supply line 19 is closed, while the overflow valve 16 of the overflow line 15 is opened. If the air is not evacuated, the air remains in the raw water portion of the housing 2 and the filtration area is reduced. However, by opening the overflow valve 16, the air bleeding of the raw water portion of the housing 2 can be performed. Done. In addition, the air release valve 28 is opened, and the residual air from the previous air pushing backwashing in the treated water pipe 17 is discharged.
[0042]
In this way, with the raw water inlet valve 11, the air release valve 28, and the overflow valve 16 opened, the raw water pump 10 is operated to remove air from the housing 2 of the hollow fiber membrane module 1, Supply raw water. When the inside of the housing 2 becomes full, the overflow water of the raw water is drained from the overflow pipe 15.
[0043]
In the above-mentioned water filling step, the overflow valve 16 and the air release valve 28 are closed, while the treated water outlet valve 18 is opened, thereby shifting to the filtration step. In this filtration step, raw water is supplied under pressure from the raw water supply pipe 7 to the hollow fiber membrane module 1 so that the raw water passes from the outside to the inside of the hollow fiber membrane. As a result, bacteria and suspended matter in the raw water are captured outside the hollow fiber membrane. That is, the raw water is filtered by the hollow fiber membrane, and the filtered water is led out of the treated water pipe 17 as treated water. By opening the air bleed valve 28 and the overflow valve 16 only for a certain period immediately after the start of filtration, a rapid pressure increase in the housing 2 can be prevented and the air pool in the treated water pipe 17 is removed.
[0044]
After the filtration for a certain period of time, an air pushing backwashing step (backwashing of treated water by water pushing backwater) is performed. When the flow of water in the filtration step is stopped, the filtered treated water is stored in the treated water portion in the upper part of the housing 2, and the treated water outlet valve 18 provided at a point downstream from the treated water portion is closed. When air pressure is applied between the treated water section and the treated water section, the treated water flows from the inside of the hollow fiber to the outside due to the pressure. Dirt is removed.
[0045]
Specifically, the air pushing backwashing step is performed by closing the raw water inlet valve 11 and the treated water outlet valve 18 and opening the air pushing valve 20 and the overflow valve 16 as shown in FIG. By closing the treated water outlet valve 18, the treated water stays in the treated water pipe 17 on the housing 2 side of the treated water outlet valve 18 or on the treated water side of the housing 2. When the air push valve 20 is opened in this state, pressurized air is supplied to the treated water side of the hollow fiber membrane module 1. As a result, the treated water is pushed out to the raw water side by the air pressure, and a part of the water in the housing 2 is discharged from the overflow pipe 15.
[0046]
The filtering apparatus of the present embodiment is characterized by the air pushing backwashing step, and this point will be described below. If the air push valve 20 is left open while it is open, the pressure on the housing 2 side from the air push valve 20 also increases with the passage of time to a backwash air pressure of 2 kg / cm. ² Approach. For example, the air pressure for backwashing is 2 kg / cm in about 2 seconds. ² And the treated water in the stagnation section is also returned to the raw water side. However, in the filtration device of the present embodiment, such an air pressure for back washing is 2 kg / cm. ² Is controlled so that the air push valve 20 is opened and closed intermittently a plurality of times. For example, the pulse-like operation of opening the air push valve 20 for about 0.5 second, closing it immediately, and then opening it again one second later is repeated twice or more. By the air-push wavy backwash, the state of detachment of the adhered matter from the hollow fiber membrane surface is improved by the impact force at the time of blowing the pressurized air.
[0047]
By the way, in consideration of the compactness and the cleaning effect of the filtration device, the volume of the retained treated water portion is set to be at most twice the amount of water held by the module on the treated water side of the hollow fiber membrane module 1. Is preferred. Here, “the amount of water possessed by the module on the treated water side” means only treated water inside the hollow fiber membrane, and the amount of retained water of treated water is set to within twice as much as the rest. For example, when the amount of water retained in the module is about 0.1 L, the volume of the treated water section is preferably set to 0.2 L or less. As will be described later, by performing bubbling in the next step, a cleaning effect can be expected even with a small amount of backwash water.
[0048]
Next, as shown in FIG. 5, while the air push valve 20 is closed, while the bubbling valve 13 and the overflow valve 16 are opened, air is jetted from the bubbling air supply pipe 8 into the housing 2 to perform a bubbling step. Is carried out. The hollow fiber membrane is swung by bubbling, and the dirt attached to the gap between the hollow fiber membranes and the membrane surface is removed.
[0049]
When the treated water portion (residence portion) in the air-pushed backwashing step is reduced for compactness, the separated suspended substance remains in the vicinity of the outer surface of the hollow fiber, but becomes hollow from the lower portion of the hollow fiber bundle. When bubbling is performed on the entire yarn, the yarn is spread from the vicinity of the outer surface of the hollow fiber to the raw water portion. If this spread did not occur, even if the next process was blown, the suspended solids would reattach to the outer surface of the hollow fiber and the efficiency of washing would be reduced. Is prevented.
[0050]
Finally, as shown in FIG. 6, in order to discharge dirt removed from the hollow fiber membrane by backwashing or bubbling to the outside of the apparatus, the drain valve 12 is opened, and the water in the housing 2 is drained (blown). A process is performed. At this time, the bubbling valve 13 is opened, and the air from the bubbling air supply pipe 8 is sent into the housing 2 to perform bubbling while draining. This blowing prevents the re-adhesion of suspended matter. Then, from the state of attachment to the outer surface of the hollow fiber, the suspended matter spread to the raw water portion by the air pushing backwashing step or the bubbling step can be effectively discharged from the housing raw water portion.
[0051]
By opening the overflow valve 16, air is removed from the bubbling. After such a drainage step, the water is supplied into the housing 2 and returned to a water filling step for overflowing. By adding bubbling at the time of water replenishment, the effect of discharging suspended substances is enhanced, and the hollow fiber membrane is washed again to improve the membrane washing effect. Moreover, the overflow at the time of water replenishment is effective for draining out the re-attached suspended solids.
[0052]
【The invention's effect】
As described in detail above, according to the hollow fiber membrane filtration device of the present invention, the hollow fiber membrane can be effectively cleaned by a plurality of air-pressed backwashes with pressure changes. In addition, by adding bubbling at the time of drainage, dirt and particles can be reliably discharged to the outside of the housing while preventing re-adhesion to the membrane surface.
[Brief description of the drawings]
FIG. 1 is a schematic view showing a main part of one embodiment of a hollow fiber membrane filtration device of the present invention.
FIG. 2 is a flowchart showing an example of an operation process of the hollow fiber membrane filtration device in FIG.
FIG. 3 is a view showing a use state of the hollow fiber membrane filtration device of FIG. 1, showing a water filling step.
FIG. 4 is a view showing a use state of the hollow fiber membrane filtration device of FIG. 1, showing an air-pressed backwashing step.
FIG. 5 is a view showing a use state of the hollow fiber membrane filtration device in FIG. 1, showing a bubbling step.
FIG. 6 is a view showing a use state of the hollow fiber membrane filtration device of FIG. 1, showing a drainage step.
[Explanation of symbols]
2 Housing
3 Hollow fiber membrane
7 Raw water supply pipeline
8 Bubbling air supply line
9 drainage pipeline
15 Overflow pipeline
17 Treatment water pipeline
18 Treated water outlet valve
19 Backwash air supply line
20 Air push valve
28 Air release valve

Claims (6)

A housing containing the hollow fiber membrane,
A raw water supply pipe capable of supplying raw water to the housing,
A treated water pipe for drawing treated water obtained by filtering raw water through a hollow fiber membrane from a housing,
A drain pipe that can discharge raw water from the lower part of the housing,
A bubbling air supply line connected to the raw water supply line or the drainage line or the housing at the lower part of the housing, and for supplying air so that air bubbles can be ejected from the lower part of the housing into the housing at the time of drainage from the housing to the drainage line; A hollow fiber membrane filtration device comprising: A housing containing the hollow fiber membrane,
A raw water supply pipe capable of supplying raw water to the housing,
A treated water pipe provided with a treated water outlet valve that can be opened and closed while extracting treated water obtained by filtering raw water through a hollow fiber membrane, and
A drain pipe that can discharge raw water from the lower part of the housing,
The treated water outlet valve is connected to the treated water pipe on the housing side from the treated water outlet valve, or the treated water section of the housing, the treated water outlet valve is closed, and the treated water is retained in the treated water pipe or the treated water section of the housing. A backwash air supply pipe for performing air-push backwash for returning the treated water of the stay portion to the raw water side through the hollow fiber membrane by applying pressure by air to the stay portion a plurality of times; A fiber membrane filtration device, or the hollow fiber membrane filtration device according to claim 1. In the backwash air supply pipe, an air push valve is provided so as to be openable and closable,
Before and after the pressure on the housing side from the air push valve becomes equal to the pressure on the compressor side from the air push valve, the backwash air supply pipeline is opened and closed a plurality of times to perform the air push backwash. The hollow fiber membrane filtration device according to claim 2, wherein: A water filling step of supplying raw water into the housing containing the hollow fiber membrane, a filtration step of filtering the raw water through the hollow fiber membrane to obtain treated water, a washing step of the hollow fiber membrane, and a draining step from the housing are sequentially performed. A method of operating a hollow fiber membrane filtration device to be performed,
The method for operating a hollow fiber membrane filtration device, wherein the draining step is performed while bubbles are ejected from a lower portion of the housing. A water filling process for supplying raw water into the housing in which the hollow fiber membrane is housed,
Filtration step of filtering raw water supplied to the housing with a hollow fiber membrane to obtain treated water, processing of the upper part of the housing while closing the treated water pipe from the housing while opening the overflow pipe of the raw water from the housing An air-pressed backwashing step of washing the hollow fiber membrane by applying pressure from the air to the water accumulation section to return the treated water in the accumulation section to the raw water side via the hollow fiber membrane and draining it from the overflow conduit. ,
A bubbling step of washing the hollow fiber membrane by ejecting air bubbles from the lower part of the housing,
A method for operating a hollow fiber membrane filtration device, comprising a draining step of discharging air from a housing while ejecting air bubbles from a lower part of the housing. The method for operating a hollow fiber membrane filtration device according to claim 5, wherein in the air pushing backwashing step, pressure application by air to the treated water retaining portion is performed a plurality of times.

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