JP3273665B2 - Hollow fiber membrane filtration device and cleaning method thereof - Google Patents

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 filtration apparatus used for removing fine particles such as iron oxide clad in condensed water treatment and industrial wastewater treatment of a nuclear power plant and a thermal power plant, and a method of cleaning the same.

[0002]

2. Description of the Related Art In a filter using a hollow fiber membrane, a hollow fiber membrane module is formed by bundling a large number of hollow fiber membranes having a large number of micropores, and a large number of the hollow fiber membrane modules are laterally mounted on the filter. It is suspended on a tube sheet.

[0003] In the filtration step, raw water is supplied to the primary side partitioned by a tube sheet so that the raw water passes from the outside to the inside of the hollow fiber membrane, and fine particles in the raw water are captured outside each hollow fiber membrane. Then, the filtered water obtained from the inside of the hollow fiber membrane is collected on the secondary side defined by the tube sheet and flows out from the filter.

[0004] By performing such a filtration step, fine particles such as cladding contained in raw water adhere to the outer surface of the hollow fiber membrane. There is a problem that the filtration efficiency gradually decreases.

Therefore, in order to deal with such a problem,
A pressurized gas is introduced into the inside of the hollow fiber membrane, and filtered water or washing water is jetted from the inside to the outside of the hollow fiber membrane, and a large number of bubbles are jetted upward from below the hollow fiber membrane filter. A method for backwashing and washing off the deposits adhering to the outer surface of the hollow fiber membrane is proposed in, for example, JP-A-60-19002.

A number of similar backwashing and washing methods for a hollow fiber membrane filtration device have been proposed. In these methods, once filtered water is flowed in the reverse direction, and the filtered water is returned to its original state. I have. Therefore, this method lowers the filtration efficiency as a whole, and must be said to be uneconomical.

Further, a large-capacity filter also requires a large amount of pressurized gas for pushing out filtered water at a time. Therefore, a large-capacity backwash air storage tank and the air are exposed to the inner surface of the hollow fiber membrane. In order to prevent clogging from the inner surface of the hollow fiber membrane, it is necessary to provide an air filter and to provide an air flow control device constituting these air backwashing facilities.

[0008]

When condensate containing crystalline fine particles, for example, crystalline iron clad, is treated in the hollow fiber membrane filtration apparatus as described above, the filtration pressure difference is maintained even if the condensate is treated for a long time. It did not rise so much, and there was no problem even when the cleaning method using gas and water was used at appropriate intervals.

However, if the amorphous iron clad exists in the condensate, the amorphous iron has finer particles than the crystalline iron and has a higher caking property, so that it is compacted so as to cover the surface of the hollow fiber membrane. The filtration water flow is interrupted, and the filtration differential pressure rises during short-term processing.

[0010] Further, in the method using gas or water, the backwashing and cleaning effect does not work, the differential pressure does not return, and the life of the hollow fiber membrane is reached in a short period of time. Can not be used.

[0011] Accordingly, it is conceivable to remove the hollow fiber membrane module contaminated with amorphous iron with an appropriate cleaning agent in such a state, that is, removal of iron oxide containing radioactive substances such as condensate of a nuclear power plant. In a filter using a hollow fiber membrane module, the washing and drainage with the above-mentioned chemical solution is subject to radioactive waste treatment.

However, salts generated by neutralizing the reducing agent and the acid contained in the washing wastewater are not preferred in that they increase the solids during radioactive waste treatment. The generation of the chemical cleaning wastewater requires a neutralization treatment and the like from the viewpoint of environmental protection from the viewpoint of environmental protection in the treatment of industrial wastewater even with a thermal power other than nuclear power, which has an undesirable problem.

[0013] Therefore, even in the case of raw water containing a non-crystalline iron, that is, a raw water containing a suspension having a high caking property and lacking in crystallinity, it is possible to effectively remove the adhered substance adhering to the membrane surface of the hollow fiber. In addition, there is a demand for a hollow fiber membrane filtration device and a method for cleaning the same which do not increase the solid matter other than the removed deposits in the washing wastewater while removing the same.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. In a filter using a hollow fiber membrane module, a pressurized gas is introduced into the inside of a conventional hollow fiber membrane to push back and wash filtered water. A non-crystalline iron oxide or suspension that is firmly attached to the membrane surface of the hollow fiber and cannot be easily peeled off even when a method of supplying and cleaning a large number of bubbles from below the hollow fiber membrane module is used. It is an object of the present invention to provide a hollow fiber membrane filtration device capable of effectively removing even turbid matter and not increasing solids other than iron oxide in the washing wastewater, and a method of washing the same.

[0015]

Means for Solving the Problems A first invention of the present application is a hollow fiber formed by bundling a large number of hollow fiber membranes on a tube sheet that partitions the inside of a filter using a hollow fiber membrane into a primary side and a secondary side. On the primary side of the filter with the membrane module suspended, a partition plate for dividing the chamber into an upper chamber and a lower chamber, and the outer middle part of the protective cylinder for protecting the hollow fiber membrane by opening the upper and lower ends of this partition plate In addition, a head tank is provided below the protection cylinder, in which a tip of a bubble ejection nozzle is stored, and a head tank that communicates with the upper chamber of the partition plate is provided.

In the second invention of the present application, the filter and the head tank are filled with water, and the water on the lower side of the partition plate is lowered to a position where the water seal of the protection cylinder cannot be cut off. Form an air pocket in the upper part of the lower chamber below the partition plate,
When bubbles are supplied from the bubble ejection nozzle at the lower part of the protection cylinder, the water in the vicinity of each hollow fiber membrane existing in the water is stirred by the rising flow of the bubbles, and the bubbles rise in the protection cylinder and reach the upper chamber of the partition plate. When the water level in the upper chamber is lowered by forming an air reservoir and the water level in the protection cylinder is also lowered at the same time, the water level in the lower chamber of the partition plate rises, and the process of compressing the air chamber in the upper part of the lower chamber and the continuous supply of air bubbles As a result, the air reservoir in the upper chamber of the partition plate reaches the conduit communicating with the head tank, escapes to the head tank, the pressure of the air reservoir in the upper chamber drops sharply, and the compressed air pool in the lower chamber of the partition plate Expands, and the air expansion process that raises the water level in the protective cylinder acts alternately, thereby generating an ascending flow and a descending flow in which the bubbles are agitated alternately in the protective cylinder, thereby forming each hollow fiber membrane. To separate the fine particles trapped on the outer surface of the hollow fiber membrane. A method for cleaning the hollow fiber membrane filtration apparatus according to claim Rukoto.

Further, the third invention of the present application is directed to a filter and a head tank provided with a pump provided between a filter inlet nozzle and a head tank outlet nozzle by filling the inside of a filter and a head tank of the hollow fiber membrane filtration device. Forced circulation of water in the head tank and supply of air bubbles into the protection cylinder of each hollow fiber membrane to shake each hollow fiber membrane by a gas-liquid multiphase flow to separate fine particles trapped on the outer surface of the hollow fiber membrane. This is a method for cleaning a hollow fiber membrane filtration device.

According to a fourth aspect of the present invention, in the hollow fiber membrane filtration device, a chemical such as an aqueous solution of hydrogen peroxide or an aqueous solution of sulfuric acid is injected into the head tank and forced while supplying air bubbles into the protection cylinder of each hollow fiber membrane. This is a method for cleaning a hollow fiber membrane filtration device, comprising performing circulating cleaning.

[0019]

According to the operation of the present invention, the water backwashing operation from the inner surface of the hollow fiber membrane conventionally performed is not performed, and the treated water chamber in the filter is divided into an upper chamber and a lower chamber by a partition plate. Protective cylinders for each hollow fiber membrane module are provided on the partition plate with upper and lower openings, and a water head pressure equivalent to の of the length of the hollow fiber membrane module is applied to the upper chamber side to allow water in the lower chamber side to pass through the protective tube. It is lowered to a position where the water seal cannot be cut, creating a negative pressure state in the lower chamber of the partition plate.

In this state, when air bubbles are continuously supplied to the lower part of the water-sealed protection cylinder, air is trapped in the upper chamber of the partition plate, the pressure in the upper chamber increases, and the water level of the upper chamber of the partition plate and the water level of the protection cylinder decrease. .

Further, when air bubbles are continuously supplied, the air reservoir above the partition plate reaches the communication pipe of the head tank, and a part of the air in the air reservoir escapes to the head tank, and the pressure above the partition plate increases rapidly. At the same time, the compressed air below the partition plate expands, raising the water level in the protective cylinder.

When the supply of air bubbles is continued in this manner, the gas-liquid multiphase flow alternately rises and falls in the protective cylinder to shake the hollow fiber membrane, and air bubbles are also introduced into the hollow fiber membrane bundle. In the conventional method, even if bubbles are introduced, the upper part of the protective tube is open to the atmosphere even when bubbles are introduced, and bubbles are not introduced into the hollow fiber membrane bundle of the hollow fiber membrane module. Can be washed.

Further, since the upper and lower ends of the protective tube are opened, the washing water can be forcibly circulated in the protective tube, and at the same time, a gas-liquid multi-phase flow can be created by the supply of air bubbles. Cleaning becomes possible.

Further, since the cleaning water is replaced with an aqueous solution of a chemical such as an aqueous solution of hydrogen peroxide or an aqueous solution of sulfuric acid, and forced circulation cleaning can be performed by a gas-liquid mixed-phase flow, more effective cleaning can be performed.

Further, if a filter for preventing re-adhesion is provided on the suction side of the forced circulation pump, the adhering substances separated from the surface of the hollow fiber membrane by washing are captured, and re-adhesion to the hollow fiber membrane is prevented. Cleaning becomes possible.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the hollow fiber membrane filtration device according to the present invention will be described with reference to FIG. FIG. 1 is a sectional view of a hollow fiber membrane filtration device used in the present invention. In FIG. 1, reference numeral 1 denotes a hollow fiber membrane module, and this hollow fiber membrane module 1 is formed by bundling a large number of hollow fiber membranes 2.

The hollow fiber membrane module 1 is protected by protective cylinders 3 having upper and lower ends. A tube sheet 5 is provided above the filter 4, the inside of the filter 4 is partitioned into a treated water chamber 6 and a filtered water chamber 7, and a large number of hollow fiber membrane modules 1 are suspended on the tube sheet 5.

Further, a partition plate 10 for partitioning the treated water chamber 6 of the filter 4 into an upper chamber 8 and a lower chamber 9 is provided, and the partition plate 10 is provided with a protective cylinder for protecting a plurality of hollow fiber membrane modules 1 respectively. The upper part 8 and the lower chamber 9 of the treated water chamber 6 are air-tightly separated from each other by a partition plate 10 while fixing an intermediate portion of the third water treatment chamber 3. The upper and lower ends of the protective cylinder 3 are open.

A bubble distribution pipe 11 is disposed below the filter 4, that is, in the lower chamber 9 of the treated water chamber 6. This bubble distribution pipe 11 is made to correspond to a bubble ejection nozzle 12 immediately below the hollow fiber membrane module 1 and the protection cylinder 3.
Is stored in the protective tube 3.

On the other hand, the upper chamber 8 of the treated water chamber 6 is provided with a vent pipe communicating with a head tank 13 having a head difference H of about 1/2 of the length of the hollow fiber membrane module 1 and the length of the hollow fiber membrane module 1. Road 14
And a drain nozzle 15 for discharging water in the upper chamber 8 and an air vent nozzle 16 for discharging air in the upper chamber 8 are provided.

In the lower chamber 9 of the treated water chamber 6, an air vent nozzle 17 in the lower chamber 9 is provided, and at the lowermost part of the filter 4, a treated water inlet nozzle 18 also serving as a drain is provided. The baffle plate 19 is arranged on the upper part of 18.

A filtered water outflow nozzle 20 and a filtered water drain nozzle 21 are provided above the filter 4. On the other hand, a nozzle 22 connected to a vent pipe 14 communicating with the upper chamber 8 is provided on a lower side surface of the head tank 13 through a communication valve 23,
Outlet nozzle 24 on bottom and over nozzle 25A on top side
25B is provided.

A filtration method and a washing method will be described by using the hollow fiber membrane filtration device having the above-mentioned structure as an example of treated water containing condensate containing amorphous iron oxide as a treatment target.

In the filtration step, the treated water flows into the lower chamber 9 of the treated water chamber 6 from the treated water inlet nozzle 18, and the hollow fiber membrane module 1 filters the iron oxide containing amorphous iron in the treated water. Are collected in the filtered water chamber 7 and the filtered water outflow nozzle 20
Spill out of.

The iron oxide filtered by the hollow fiber membrane 2 is shown in FIG.
As shown in (1), an iron oxide adhesion layer 28 and an iron oxide adhesion layer 29 containing amorphous iron are formed on the surface of the hollow fiber membrane 2. Note that FIG.
The middle arrow indicates the inflow direction of the treated water.

Here, the iron oxide adhesion layer 28 is a non-crystalline, highly caking, dense adhesion layer made of fine iron oxide which is relatively strongly adhered. It is an adhesion layer that is difficult to perform, and gradually accumulates each time filtration and washing are repeated. This accumulation usually becomes a major factor in increasing the filtration pressure difference after washing. Further, the iron oxide adhesion layer 29 is a coarse adhesion layer made of a relatively large iron oxide that adheres relatively weakly to the outside of the iron oxide adhesion layer 28, and can be relatively easily peeled off.

In the filtering apparatus according to this embodiment, the dense iron oxide layer 28 made of fine iron oxide which is amorphous and has high caking properties and is relatively strongly adhered can be easily peeled off.

That is, when the pressure difference of the filter 4 reaches a specified value by continuing the filtration, the filtration is stopped and the iron oxide adhered layer formed on the surface of the hollow fiber membrane is removed. Is performed.

Next, as a second embodiment of the present invention, a method of cleaning a hollow fiber membrane filtration device will be described with reference to the process flow charts of FIGS. In this embodiment, the filtration device shown in FIG. 1 is used.

In the filtration step, when the differential pressure of the filter 4 reaches a specified value, the filtration is stopped, so that the treated water inlet valve 31 is closed and the filtered water outlet valve 32 is closed as shown in FIG. Then, the filter 4 is isolated from the filtration step (Step 1).

Next, as shown in FIG. 4, as a dome draining step, the filtered water outlet valve 32 and the depressurized valve 33 are opened to release the pressure inside the filtered water chamber 7, and the dome drain valve 34 is opened to drain the filtered water. (Step 2). In the step 2, the filtered water is not discharged, and the depressurizing operation of the filtered water chamber 7 alone does not affect the cleaning effect.

Next, as shown in FIG. 5, the treated water inlet valve 31 is opened, the communication valve 23 with the head tank 13 is opened through the treated water chamber 6 of the filter 4, and the overflow of the head tank 13 is started. Water filling is performed up to the nozzle 25B (Step 3).

Next, as shown in FIG. 6, a cleaning wastewater valve 35 also serving as the treated water inlet nozzle 18 is opened to form a negative pressure air reservoir in the upper space in the lower chamber 9 of the treated water chamber 6. Draining (step 4) is performed to a water level at which the water seal at the lower end of the protective cylinder 3 cannot be cut off.

With the communication valve 23 to the head tank 13 opened, the air inlet valve 36 of the bubble separation tube 11 below the treated water chamber 6 is opened, and compressed air is bubbled from the bubble ejection nozzle 12 into the protection cylinder 3. Supply.

Then, the bubbles move upward, and the water near each hollow fiber membrane 2 existing in the water in the protection cylinder 3 is stirred by the rising flow of the bubbles, and the bubbles rise in the protection cylinder 3 and the partition plate. Reach the upper chamber 8 of 10 and gradually form an air pocket.

When the air is compressed, the water level in the upper chamber 8 starts to drop as shown in FIG. At the same time, the water level in the protection cylinder 3 also drops, and the water level in the lower chamber 9 of the partition plate 10 rises, thereby forming a step (step 5) of compressing the air pocket above the lower chamber 9.

When the supply of air bubbles is continued, the partition plate 10
The air pool in the upper chamber 8 reaches the vent pipe 14 communicating with the head tank 13, and the air bubbles escape into the head tank 13 as shown in FIG. Opened to

Then, the pressure of the air reservoir in the upper chamber 8 of the partition plate 10 drops rapidly, and at the same time, the air reservoir compressed in the upper part of the lower chamber 9 expands to increase the water level in the protection cylinder 3. An expansion step (step 6) occurs.

The process 5 and the process 6 are alternately operated by continuous supply of air bubbles, so that an ascending flow and a downward flow in which the air bubbles are mixed are generated alternately in the protective cylinder 3 as shown in FIG. A washing step of shaking each hollow fiber membrane 2 to peel off the iron oxide adhering layers 28 and 29 adhering to the outer surface of the hollow fiber membrane (step 7)
I do.

After sufficient scrubbing, the supply of compressed air is stopped by closing the air inlet valve 36 and the washing wastewater is supplied from the upper chamber 8 of the treated water chamber 6 to the valve 39 while the valves 37 and 38 are open. And a valve 35 is opened from the lower chamber 9 to discharge the washing wastewater including the separated fine particles.

On the other hand, as shown in FIG.
A step of opening the valve 40 to discharge the washing wastewater therein is also performed (step 8).

A third embodiment according to the present invention will be described with reference to FIG. In the hollow fiber membrane filtration device shown in FIG. 1 described above, in order to forcibly circulate the washing water on the line between the treated water inlet pipe 48 of the filter 4 and the forced circulation pipe 49 as the washing water outlet pipe of the head tank 13. Is provided.

With the hollow fiber membrane filtration device thus constructed, washing water is put into the head tank 13 and the treated water chamber 6 in the filter 4 is filled.
Is divided into an upper chamber 8 and a lower chamber 9 by a partition plate 10 so that the washing water circulates in the protection cylinder 3 in which the hollow fiber membrane module 1 is stored.

When the compressed water is supplied to the air distribution pipe 11 by opening the valve 36 at the same time as circulating the washing water, bubbles are blown out of the bubble jet nozzle 12 into the protective cylinder 3 and the forced air of the washing water is used to forcibly remove the air. Each hollow fiber membrane is washed by vibrating vigorously as a liquid mixed phase flow.

Also in this case, since the head pressure is applied to the head tank 13, air bubbles in the protection cylinder 3 are hardly generated, and there is an effect that the air bubbles accumulate in the bundle of the hollow fiber membranes. The attached iron oxide fine particles can be peeled off.

The fourth embodiment according to the present invention is different from the third embodiment in that chemicals such as an aqueous solution of hydrogen peroxide and an aqueous solution of sulfuric acid are injected instead of the washing water, and the compressed air is forcedly circulated. This is a method of cleaning the hollow fiber membrane module 1 in which a gas-liquid multiphase flow is continuously supplied from the feeder to dissolve and remove the iron oxide fine particles attached to the outer surface of each hollow fiber membrane.

A fifth embodiment according to the present invention will be described with reference to FIG. According to the present invention, in the third embodiment and the fourth embodiment, the washing water passes through the treated water chamber 6 from the inlet of the filter 4, enters the head tank 13, and returns to the pump 46 through the forced circulation line 49. This is a cleaning method in which an anti-redeposition filter 47 is provided at the inlet to capture fine particles of iron oxide removed from each hollow fiber membrane module 1 and to prevent re-deposition on the hollow fiber membrane module 1.

A compressed air inflow pipe (not shown) is connected to the filtered water outflow nozzle 20 before and after the scrubbing step in common with the above-described embodiments 2 to 5 of the present invention so that compressed air flows into the filtered water chamber 7. It is also possible to carry out a backwash in which existing filtered water flows backward from the inside of each hollow fiber membrane 2 to the outside.

Next, a concrete example for clarifying the effect of the present invention will be described. Concrete example: hollow fiber membrane with inner diameter 0.3mm, outer diameter 0.4mm, length 860mm 10,000
80mm diameter hollow fiber membrane module (total filtration area)
13m ² ) One of the tubes was subjected to a real liquid test of condensate containing amorphous iron using a full-size filter. Filtration was performed at 2.6 m ³ / H as an external pressure type in which each hollow fiber membrane was passed from the outside to the inside. As a result of the actual liquid test, a filtration differential pressure behavior as shown in FIG. 13 was exhibited.

First, in the first six cycles, washing and regeneration were performed by backflow of gas and water according to the conventional washing method. As a result, the filter tag started to rise in the third cycle, and rapidly increased in the fourth cycle and the fifth cycle, and then increased in the sixth cycle. In the eyes, the differential pressure did not return even after backwashing, and operation became impossible.

The hollow fiber membrane filtration apparatus of the present invention was equipped with a hollow fiber membrane module and washed by backwashing. As a result, the differential pressure recovery rate was about 80%. After this, the process was continued up to 14 cycles, but the hollow fiber membrane module was once clogged,
The backwash cycle was shortened, but the differential pressure recovery by the backwash was good.

FIG. 14 shows the behavior of the filtration pressure difference when the cleaning method according to the present invention uses a new hollow fiber membrane, ie, the state of recovery of the new membrane. The horizontal axis is the number of cycles, and the vertical axis is the filtration pressure difference (Kg / cm ² ).

From FIG. 14, it was confirmed that the water passing and washing cycles were carried out at equal intervals, and that the state of recovery from the differential pressure by back washing was good. Further, in the conventional method carried out under the same conditions, as shown in FIG. 15, the filtration differential pressure increases in the third cycle, and in the fourth cycle, the differential pressure recovery due to the backwashing is also slight, causing a sudden increase in the differential pressure. Became impossible.

[0064]

According to the filtration apparatus of the present invention, even if the amorphous iron oxide is firmly attached to the surface of the hollow fiber membrane which cannot be easily separated by simple vibration of air bubbles or reverse flow of gas, water, etc. It can be easily peeled off.

Further, according to the cleaning method of the present invention, it is possible to recover the filtration pressure difference without using an agent such as a reducing agent or an acid which increases the solid matter, and it is possible to recover the cleaning drainage like a nuclear power plant. It is effective when the radioactive waste must be further treated.

On the other hand, in the industrial field where the use of chemicals does not hinder the use, forced circulation cleaning by a gas-liquid mixed-phase flow can be expected to have a further effect, and the application range of the hollow fiber membrane filtration device can be expanded.

Further, there is no need to provide a backwash air storage tank or an air flow facility for backflowing the filtered water from the inside of each hollow fiber membrane, and when introduced into a large-capacity purification facility such as a condensate treatment, it is economical. Effect.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a hollow fiber membrane filtration device according to the present invention.

FIG. 2 is an enlarged partial cross-sectional view showing a state of the hollow fiber membrane during filtration in FIG. 1;

FIG. 3 is a schematic cross-sectional view showing step 1 (filtration stop) of a method for cleaning a hollow fiber membrane filtration device according to a second embodiment of the present invention.

FIG. 4 is a schematic sectional view showing step 2 (dome drain) in FIG. 3;

FIG. 5 is a schematic cross-sectional view showing step 3 (washing with washing water) in FIG.

FIG. 6 is a schematic cross-sectional view showing step 4 (water drainage, formation of an air reservoir in the lower chamber of the treated water chamber (negative pressure state)) in FIG.

FIG. 7 is a schematic sectional view showing step 5 (formation of an air reservoir in the upper chamber of the treated water chamber (air compression)) in FIG. 3;

FIG. 8 is a schematic cross-sectional view showing a step 6 (air expansion of the lower chamber of the treated water chamber) in FIG.

FIG. 9 is a schematic cross-sectional view showing a step 7 (cleaning step) in FIG.

FIG. 10 shows a step 8 (wash drainage drain) in FIG.
FIG.

FIG. 11 is a schematic cross-sectional view showing a flow of a cleaning method by a forced circulation method in a third embodiment of the present invention.

FIG. 12 is a schematic sectional view showing an example in which a re-adhesion prevention filter is provided in a forced circulation line in a fifth embodiment of the present invention.

FIG. 13 is a waveform chart showing a recovery state of a filtration pressure difference by a backwash cycle in a specific example of the present invention.

FIG. 14 is a waveform chart showing the behavior of filtration differential pressure in the cleaning method according to the present invention.

FIG. 15 is a waveform diagram showing a filtration differential pressure recovery state in a conventional method for cleaning a hollow fiber membrane filtration device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1: Hollow fiber membrane module, 2: Hollow fiber membrane, 3: Protection cylinder,
4 ... filter, 5 ... tube plate, 6 ... treated water chamber, 7 ... filtered water chamber,
8: Upper chamber, 9: Lower chamber, 10: Partition plate, 11: Bubble pipe, 12
... Bubble jet nozzle, 13 ... Head tank, 14 ... Vent line, 15 ... Drain nozzle, 16, 17 ... Air vent nozzle, 18
... treated water inlet nozzle, 19 ... baffle plate, 20 ... filtered water outflow nozzle, 21 ... filtered water drain nozzle, 22 ... nozzle
23 ... communication valve, 24 ... outlet nozzle, 25A, 25B ... overflow nozzle, 28, 29 ... iron oxide adhesion layer, 31 ... treated water inlet valve, 32 ... filtered water outlet valve, 33-45 ... valve, 46 ... pump, 47…
Anti-redeposition filter, 48: treated water inlet pipe, 49: forced circulation line.

Continuation of the front page (56) References JP-A-4-126528 (JP, A) JP-A-2-17925 (JP, A) JP-A-63-271006 (JP, A) JP-A-2-17924 (JP) JP-A-64-51106 (JP, A) JP-A-2-26625 (JP, A) JP-A-58-202020 (JP, A) JP-A-5-138166 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B01D 63/02 B01D 65/02

Claims (4)

(57) [Claims] An inside of a filter is divided into a treated water chamber and a filtered water chamber by a tube sheet, and a hollow fiber membrane module formed by bundling a large number of hollow fiber membranes is suspended on the tube sheet. An upper chamber and a lower chamber are partitioned by a partition plate, upper and lower ends of the partition plate are opened, and an outer intermediate portion of a protection cylinder for protecting the hollow fiber membrane module is fixed, and a bubble ejection nozzle is provided below the protection cylinder. And a head tank communicating with the upper chamber. 2. The method for cleaning a hollow fiber membrane filtration device according to claim 1, wherein the filter and the head tank are filled with water, and the water level of the lower part of the partition plate is not cut off by the water seal of the protection cylinder. Position, and an air reservoir is formed in the upper part of the lower chamber below the partition plate to supply air bubbles from the air bubble ejection nozzle at the lower part of the protection cylinder, and the water in the vicinity of each hollow fiber membrane existing in the water flows upward of the air bubbles. By stirring, the bubbles are raised in the protection cylinder to reach the upper chamber of the partition plate, the water level of the upper chamber is lowered to lower the water level in the protection cylinder, the partition plate lower chamber of the lower Raise the water level and compress the air pocket,
By the continuous supply of the air bubbles, the air reservoir in the upper chamber of the partition plate reaches a pipe communicating with the head tank, and an ascending flow and a descending flow in which the air bubbles are agitated are alternately generated in the protective cylinder to form each of the hollows. A method for cleaning a hollow fiber membrane filtration device, comprising shaking a fiber membrane to remove fine particles captured on an outer surface of the hollow fiber membrane. 3. Filling the filter and the head tank with water, and forcibly circulating water in the filter and the head tank through a pipe provided with a pump between the filter inlet nozzle and the head tank outlet nozzle. 3. The method for cleaning a hollow fiber membrane filtration device according to claim 2, wherein air bubbles are supplied into the protection cylinders of the hollow fiber membranes and the hollow fiber membranes are shaken by a gas-liquid mixed phase flow. 4. A method according to claim 2, wherein a chemical such as an aqueous solution of hydrogen peroxide or an aqueous solution of sulfuric acid is injected into said head tank, and forced circulation washing is performed while air bubbles are supplied into the protective cylinder of each hollow fiber membrane. Alternatively, the method for cleaning a hollow fiber membrane filtration device according to claim 3.