JP2000084377A - Removal of membrane contaminated substance for tubular membrane device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a removing method of membrane contaminated substance in a vertical installation type internal pressure type tubular membrane device using a tubular membrane (hollow fiber membrane, tubular membrane or the like) such as a precise filter membrane, an ultrafiltration membrane, which is capable of effectively removing the membrane contaminated substance stuck to the inner surface of the tubular membrane and excellently cleaning not only the tubular membrane existing at the center part of the membrane module but the tubular membrane existing at the peripheral part of the membrane module. SOLUTION: A water drawing process for drawing a part of or the whole distilled water in the tubular membrane 6 of the membrane module 4 from the inside of the tubular membrane, a high pressure water passing process for passing high pressure water 25 downward through the tubular membrane after finishing the water drawing process and a high pressure gas passing process for passing a high pressure gas 27 upward through the tubular membrane after finishing the high pressure water passing process are performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of removing membrane contaminants in a membrane filtration apparatus for filtering general water, condensate of a power plant, condensate of general industry, industrial water, dilute wastewater of general industry, etc. More specifically, the present invention relates to a method for removing a membrane contaminant of a vertically installed internal pressure type tubular membrane device using a tubular membrane (a hollow fiber membrane, a tubular membrane, or the like) such as a microfiltration membrane or an ultrafiltration membrane.

[0002]

2. Description of the Related Art A hollow fiber membrane module in which a number of hollow fiber membranes such as a microfiltration membrane and an ultrafiltration membrane are vertically installed is used as a membrane filtration device for performing the above-mentioned filtration treatment. There is a vertical installation type internal pressure type hollow fiber membrane device. In this device, raw water flows through the membrane module from bottom to top,
The raw water is filtered by flowing the raw water from the inside to the outside of the hollow fiber membrane.

In the above-described vertical installation type internal pressure type hollow fiber membrane device, components contained in raw water adhere to the inner surface of the hollow fiber membrane during the filtration operation, and the hollow fiber membrane is contaminated. Therefore, the membrane contaminants adhering to the inner surface of the hollow fiber membrane are removed by performing backwashing periodically (usually once every 10 minutes to several tens of minutes) during the filtration operation.

[0004] Backwashing of the vertical installation type internal pressure type hollow fiber membrane device is performed as follows. First, the backwash fluid (usually using permeated water) flows through the membrane module in the opposite direction to that during filtration, that is, the backwash fluid flows from the outside to the inside of the membrane at a flow rate several times higher than that during filtration. Peel off membrane contaminants from the inner surface of the yarn membrane. Next, a flushing fluid (usually using raw water) is allowed to flow upward from the bottom into the hollow fiber membrane (usually in the direction of water flow during filtration), and membrane contaminants separated from the membrane inner surface by the flushing fluid are used. Is washed out and removed from the inside of the hollow fiber membrane. The flushing fluid flows into the hollow fiber membrane from the lower end opening of the hollow fiber membrane and flows out from the upper end opening. In this case, a water / air mixed-phase flow in which bubble air is mixed with water may be used as a flushing fluid in a subsequent step of flushing the membrane contaminants.

[0005]

However, the conventional method for removing film contaminants by back washing described above has the following problems. The hollow fiber membrane has an inner diameter of about 0.8 mm in the case of a small-diameter hollow fiber membrane. In the case of such a small-diameter hollow fiber membrane, sufficient back-washing using only water as the back-washing fluid and the flushing fluid is not sufficient. The cleaning effect cannot be obtained. Further, when the water / air mixed phase flow is used as the flushing fluid, there is a certain effect, but still a satisfactory cleaning effect cannot be obtained. The center part of the hollow fiber membrane module (the central part in the cross section of the module when cut horizontally) is easy for the backwashing fluid and the flushing fluid to flow. Therefore, the inner surface of the hollow fiber membrane existing in this part is relatively well cleaned. Is done. However, the peripheral portion of the hollow fiber membrane module (peripheral portion in a cross section obtained by cutting the module horizontally) is less likely to flow the backwashing fluid and the flushing fluid than the central portion. The inner surface is difficult to clean. Therefore, the hollow fiber membrane existing in the peripheral portion is likely to be blocked, and once the blockage occurs, the peripheral portion of the hollow fiber membrane module is difficult to flow the backwashing fluid and the flushing fluid as described above. Is difficult to recover by normal backwashing. In addition,
This problem is the same in both the case where only water is used as the flushing fluid and the case where a water / air mixed phase flow is used. Since the detergency of the rinsing fluid is weak, it is necessary to use a large amount of the rinsing fluid in order to sufficiently remove the membrane contaminants separated from the inner surface of the membrane, resulting in a low water recovery rate.

[0006] Therefore, the conventional backwashing does not provide a sufficient cleaning effect on the inner surface of the hollow fiber membrane, so that it is relatively frequently used.
Further, even if the backwash is repeated using a large amount of the backwash fluid and the flushing fluid, the contamination of the hollow fiber membrane cannot be effectively prevented, and the hollow fiber membrane existing around the membrane module cannot be prevented. Obstruction was likely to occur. As a result, chemical cleaning, that is, cleaning for removing film contaminants by chemical dissolution, must be performed at a relatively high frequency.

The present invention has been made in view of the above circumstances, and is directed to a vertically installed internal pressure type tubular membrane device using a tubular membrane (such as a hollow fiber membrane or a tubular membrane) such as a microfiltration membrane or an ultrafiltration membrane. A method for removing membrane contaminants, wherein the membrane contaminants adhered to the inner surface of the tubular membrane can be effectively removed, and not only the tubular membrane present at the center of the membrane module but also the periphery of the membrane module It is an object of the present invention to provide a method for removing a membrane contaminant that can well clean a tubular membrane existing in a membrane.

[0008]

In order to achieve the above object, the present invention provides a method for removing membrane contaminants of a vertical installation type internal pressure type tubular membrane device, which comprises: A draining step of draining part or all of the tubular membrane from the inside of the tubular membrane, a high-pressure water passing step of passing high-pressure water downward from above in the tubular membrane after the completion of the draining step, and a tubular membrane after finishing the high-pressure water passing step And a high-pressure aeration step of passing a high-pressure gas from top to bottom in the inside thereof.

When high-pressure water or high-pressure gas is passed through the inside of the tubular membrane (inside the pipe) of the vertical installation type internal pressure type tubular membrane apparatus, the interface between the high-pressure water and the gas in the pipe, or the high-pressure gas and the water in the pipe, When the interface with the membrane passes through the inner surface of the membrane, a strong shearing force is applied to the membrane contaminant attached to the inner surface of the tubular membrane, and this shearing force effectively exfoliates the membrane contaminant on the inner surface of the tubular membrane.

In the present invention, after the filtration is completed, first, a draining step of draining part or all of the water retained in the tubular membrane (raw water remaining in the tubular membrane) is performed. Thereafter, in the high-pressure water passing step, when high-pressure water is passed from above to below in the tubular membrane after the draining step, high-pressure water flows into the gas phase in the tubular membrane,
The interface between the high pressure water and the air in the tube passes through the tubular membrane from top to bottom. Also, in the next high-pressure aeration step, when high-pressure gas is passed from the top to the bottom in the tubular membrane after the high-pressure water passing step, the high-pressure gas flows into the aqueous phase in the tubular membrane, and the high-pressure gas and the The interface with water passes through the tubular membrane from top to bottom. Therefore, at the time of passage through the interface between high-pressure water and gas in the high-pressure water passage process, and at the time of passage through the interface between high-pressure gas and water in the high-pressure ventilation step, the strong shearing force applied to the membrane contaminants causes the inner surface of the tubular membrane to be damaged. The film contaminants are effectively stripped. In the high-pressure ventilation step, the membrane contaminants separated from the inner surface of the tubular membrane are discharged out of the tubular membrane along with the high-pressure gas flow. Furthermore, even if membrane contaminants remain on the inner surface of the tubular membrane, the interface between the gas in the tube and the raw water passes through the inside of the tubular membrane from bottom to top when moving from the high-pressure aeration process to the normal filtration process. Due to the shear force applied to the membrane contaminant by the interface, the membrane contaminant on the inner surface of the tubular membrane is peeled off,
Removed.

When the high-pressure gas flows into the membrane module, a gas phase is first formed in the upper part of the membrane module, and the gas flows from the gas phase and flows into the tubular membrane. Due to the small size, the inertia force at the time of the flow becomes significantly smaller than that of water. As a result, the pressure distribution becomes almost uniform in the upper gas phase in the membrane module,
The high-pressure gas flows into the tubular membranes at the center and the periphery of the membrane module at substantially the same pressure. Therefore, in the process where water is pushed down in the tubular membrane in the early stage of gas inflow,
All of the tubular membranes existing in the central part and the peripheral part of the membrane module will be given a substantially equal pressing force. Therefore, not only the tubular membrane present in the center of the membrane module but also the tubular membrane present in the peripheral part of the membrane module is well cleaned, and the problem that the tubular membrane present in the peripheral part of the membrane module is easily clogged is solved. Is done.

Furthermore, when the high-pressure gas passes through the tubular membrane in the high-pressure aeration step, the above-mentioned effect of the interface between the high-pressure gas and water passing through the tubular membrane and the effect of membrane contaminants on the high-pressure gas flow are obtained. In addition to the function and effect of being discharged out of the tubular membrane, the following function and effect are obtained. Therefore, according to the present invention, the membrane contaminants attached to the inner surface of the tubular membrane are extremely and economically removed. can do. (A) A water film-like substance adhering to the inner surface of the film is formed into droplets and separated while being accompanied by a downward gas flow. (B) When the droplet moves at a high speed, the droplet collides with the film surface adhering substance existing on the downstream side, and the film surface adhering material is peeled off. (C) The tubular membrane is finely vibrated by a high-pressure gas flow, and the vibration causes the substance adhering to the membrane to be peeled off. (D) Since the substance adhering to the membrane surface can be separated by the high-pressure gas flow and the separated substance can be discharged out of the pipe, the amount of washing water can be reduced.

Further, in the present invention, the following effects can be obtained by passing high-pressure gas and high-pressure water through the tubular membrane from top to bottom. Therefore, according to the present invention, the inner surface of the tubular membrane is The attached film contaminants can be removed very effectively. (a) Gravity can be used for draining high-pressure water and discharging accumulated water in pipes when high-pressure gas is ventilated, so that high-speed ventilation and water can be performed, and as a result, the cleaning effect by high-pressure gas and high-pressure water is improved. I do. (b) As described above, the pressure distribution becomes almost uniform in the upper gas phase in the membrane module, and as a result, the high pressure gas flows into the tubular membranes existing at the center and the periphery of the membrane module at substantially the same pressure. Can only be obtained by passing a high pressure gas through the tubular membrane from top to bottom.

Hereinafter, the present invention will be described in more detail. The type of the vertical installation type internal pressure type tubular membrane device to which the present invention can be applied is not limited, and examples thereof include a tubular membrane using a hollow fiber membrane such as an ultrafiltration membrane or a microfiltration membrane, or a tubular membrane. Further, the vertical installation type internal pressure type tubular membrane device may be a cross-flow type device or an all-filtration type device, or may use a plurality of membrane units such as elements or modules, or may use a single unit.

According to the present invention, in the water draining step, accumulated water (raw water remaining in the tubular membrane) can be drained from the tubular membrane by any means. For example, the accumulated water in the tubular membrane is dropped by its own weight. A method in which part or all of the retained water is drained from the inside of the tubular membrane, or a method in which high-pressure gas is passed through the tubular membrane to push out the retained water by the pressure of the gas. The method of extruding with a high-pressure gas is more preferable in that it can be performed.

Further, according to the present invention, after the draining step is completed,
The high-pressure water-flowing step and the high-pressure aeration step can be performed alternately a plurality of times, respectively, whereby the membrane contaminants attached to the inner surface of the tubular membrane can be more effectively removed.

[0017]

FIG. 1 is a flow chart showing an example of a vertically installed internal pressure type tubular membrane device (hollow fiber membrane device) to which the present invention is applied. In the apparatus shown in FIG. 1, 2 is a raw water tank, 4 is a hollow fiber membrane module in which a number of hollow fiber membranes 6 such as a microfiltration membrane and an ultrafiltration membrane are vertically installed, and 8 is a raw water tank 2
2 shows a raw water introducing pipe provided between the raw water chamber 5 at the lower end of the hollow fiber membrane module 4 and the raw water chamber 5. The raw water introduction pipe 8 has an automatic valve 10 and a raw water pump 12 sequentially from the upstream side to the downstream side.
Is interposed. The raw water pump 1 of the raw water introduction pipe 8
A washing water discharge pipe 16 provided with an automatic valve 14 is connected downstream of the two installation locations.

In the figure, reference numeral 18 denotes a permeated water outlet pipe connected to the upper part of the filtered water chamber 7 of the hollow fiber membrane module 4, reference numeral 20 denotes an automatic valve interposed in the permeated water outlet pipe 18, and reference numeral 22 denotes a permeated water outlet pipe 18.
A treated water discharge pipe connected to a treated water storage tank 22; and a concentrated water connected to a concentrated water chamber 9 at the upper end of the hollow fiber membrane module 4. The outflow pipe 26 indicates an automatic valve interposed in the concentrated water outflow pipe 24. The outlet end of the concentrated water outlet pipe 24 is connected to the raw water tank 2.

In the figure, reference numeral 28 denotes a water / gas pressurized tank in the form of a closed container, 29 denotes an air vent pipe connected to the upper part of the water / gas pressurized tank 28, and 31 denotes an automatic valve interposed in the air vent pipe 29. Reference numeral 30 denotes a washing water introduction pipe provided between the treated water storage tank 22 and the water / gas pressurizing tank 28. Air vent pipe 29
Is open to the atmosphere. The washing water introduction pipe 30 is provided with an automatic valve 32 and a washing water pump 34 sequentially from the upstream side to the downstream side.

In the figure, 36 is a high-pressure gas source, 38 is a high-pressure gas introduction pipe provided between the high-pressure gas source 36 and the water / gas pressurizing tank 28, and 40 is an automatic high-pressure gas introduction pipe 38 A valve 42 is a water / gas inlet pipe having an inflow end connected to the lower end of the water / gas pressurized tank 28 and an outflow end upstream of the concentrated water outflow pipe 24 at a location where the automatic valve 26 is installed. An automatic valve interposed in the gas introduction pipe 42, an air vent pipe 46 connected to the upper end of the hollow fiber membrane module 4, and an automatic valve 48 interposed in the air vent pipe 46. Air vent pipe 4
The end of 6 is open to the atmosphere.

The apparatus of this embodiment performs a filtering process by the following operation. That is, the automatic valves 10, 20, and 26 are opened,
4, 32, 40, 44 and 48 are closed and the raw water pump 12
The raw water in the raw water tank 2 is passed through the raw water chamber 5 of the hollow fiber membrane module 4 by the operation of the hollow fiber membrane module 4, and the raw water flows into the hollow fiber membrane 6 from one end opening of the hollow fiber membrane 6 communicating with the raw water chamber 5. The raw water is filtered by the hollow fiber membrane 6 by passing a part of the raw water from the inside to the outside of the hollow fiber membrane 6, and the permeated water (treated water) is sent to the treated water storage tank 22 through the permeated water outflow pipe 18. The other part of the raw water is circulated to the raw water tank 2 through the concentrated water chamber 9 and the concentrated water outlet pipe 24 as concentrated water.

Further, in the apparatus of this embodiment, the film contaminant removing method of the present invention can be carried out by the following operation at predetermined time intervals or as needed. (1) In the state of the filtration operation, the automatic valves 32, 31
Then, a predetermined amount (for example, 20 liters) of permeated water in the treated water storage tank 22 is introduced into the water / gas pressurized tank 28 having a capacity of, for example, 60 liters by the operation of the washing water pump 34. (2) The automatic valves 32 and 31 are closed and the automatic valve 40 is closed.
And a predetermined pressure (for example, 3 kgf)
/ Cm ² G) of high pressure gas (for example, air) is introduced into the water / gas pressurizing tank 28 (for example, 40 liters). (3) Fully automatic valves 10, 14, 20, 26, 31, 32,
With 40, 44 and 48 closed, the filtration operation is stopped.

(4) Opening the automatic valves 14 and 48 to drop the stagnant water (residual raw water) in the hollow fiber membrane 6 of the membrane module 4 by its own weight and discharging the water through the washing water discharge pipe 16 6. Drain some or all of the raw water from inside 6 (draining step). (5) The automatic valve 48 is closed and the automatic valve 44 is opened. As a result, first, water pressurized by high-pressure gas
The permeated water (high-pressure water) 25 in the gas pressurized tank 28 flows downward through the hollow fiber membrane 6 through the concentrated water chamber 9 (1).
The second high-pressure water passage process). Next, when the high-pressure water in the pressurized tank 28 is exhausted, the high-pressure gas 27 in the water / gas pressurized tank 28 passes through the concentrated water chamber 9 into the hollow fiber membrane 6 continuously to the high-pressure water passing step. Flows from top to bottom (first high-pressure ventilation step). Drainage after washing (washing wastewater) and gas after aeration (washing waste gas) are discharged from the washing water discharge pipe 16 through the raw water chamber 5.

(6) The automatic valve 44 is closed and the automatic valves 32 and 31 are opened.
Again, a predetermined amount of permeated water in the treated water storage tank 22 is introduced into the water / gas pressurized tank 28. (7) The automatic valves 32 and 31 are closed and the automatic valve 38 is closed.
Is opened, and a predetermined amount of a high-pressure gas having a predetermined pressure is introduced from the high-pressure gas source 36 into the water / gas pressurizing tank 28. (8) Open the automatic valve 44. Thereby, first, the permeated water (high-pressure water) 25 in the water / gas pressurized tank 28 pressurized by the high-pressure gas flows from the top to the bottom in the hollow fiber membrane 6 (second high-pressure water passage). Process). Next, the high-pressure gas 27 in the water / gas pressurizing tank 28 flows from the top to the bottom in the hollow fiber membrane 6 following the high-pressure water supply step (second high-pressure aeration step). Drained water after washing (washing wastewater) and gas after aeration (washing waste gas) are passed through the raw water chamber 5 to the washing water discharge pipe 16.
Is discharged from (9) Return to the filtering operation.

In the present invention, at the time when the operation (5) is completed, that is, at the time when the first high-pressure water supply step and the first high-pressure ventilation step are completed, the washing is completed and the operation returns to the filtration operation. Of course, it may be possible.

Further, in the apparatus of the present embodiment, it is possible to implement a membrane contaminant removing method in which water is drained by passing high-pressure gas through the following operation. In the state of the filtration operation, the automatic valve 40 is opened, and a predetermined pressure (for example, 3 kgf / cm ² G) is applied from the high-pressure gas source 36.
A predetermined amount (for example, 60 liters) of the high-pressure gas (for example, air) is introduced into the water / gas pressurizing tank 28. At this time, no permeated water is introduced. Fully automatic valves 10, 14, 20, 26, 31, 32, 4
With 0, 44 and 48 closed, the filtration operation is stopped. The automatic valve 44 is opened. Thereby, the water / gas pressurizing tank 28
The high-pressure gas inside is introduced into the hollow fiber membrane 6 through the concentrated water chamber 9, and part or all of the water retained in the hollow fiber membrane 6 is forcibly pushed out by the pressure of the high-pressure gas, and the washing water is discharged. Tube 1
Exhausted from 6.

When the automatic valve 44 is closed, the automatic valve 3
2, 31 are opened, and a predetermined amount (for example, 20 liters) of permeated water in the treated water storage tank 22 is introduced into the water / gas pressurized tank 28 by the operation of the washing water pump 34. The automatic valves 32 and 31 are closed, the automatic valve 40 is opened, and a predetermined pressure (for example, 3 kgf / c
m ² G) of a high pressure gas (eg, air)
(0 liter) is introduced into the water / gas pressurized tank 28. The automatic valve 44 is opened. Thereby, first, the permeated water (high-pressure water) in the water / gas pressurized tank 28 pressurized by the high-pressure gas.
25 flows downward through the inside of the hollow fiber membrane 6 (high-pressure water passage step). Next, water and water
The high-pressure gas 27 in the gas pressurizing tank 28 flows from the top to the bottom in the hollow fiber membrane 6 (second high-pressure ventilation step). Drainage after washing (washing wastewater) and gas after ventilation (washing exhaust gas)
Is discharged from the washing water discharge pipe 16. The operation returns to the filtering operation.

When a plurality of membrane modules are connected and used, the above-described removal of the membrane contaminants may be performed simultaneously on all the membrane modules, or the membrane modules may be divided into a plurality of blocks. May be performed for each block. Further, the operation of removing the film contaminants described above may be automatically executed using a liquid level electrode, a pressure switch, an automatic valve, a timer, or the like.

Further, in the apparatus of this embodiment, by adding a normal backwashing mechanism shown in FIG. 2, in addition to the above-described cleaning of the present invention, normal backwashing is performed at predetermined time intervals or as necessary. You may do so. In FIG. 2, reference numeral 50 denotes a backwash water inlet pipe whose inflow end is connected to the treated water storage tank 22 and whose outflow end is connected to the permeated water outflow pipe 18 at a location upstream of the automatic valve 20. The backwash water introduction pipe 50 is provided with a backwash pump 52 and an automatic valve 54 sequentially from the upstream side to the downstream side. Since the other points are the same as those of the apparatus of FIG. 1, the same parts in FIG. 2 as those in FIG. 1 are denoted by the same reference numerals and the description thereof will be omitted.

The above normal backwashing is performed by the following operation.
That is, the automatic valves 10, 20, 26, 31, 32, 3
4, 40, 44, and 48 are closed, the automatic valves 14 and 54 are opened, and the operation of the raw water pump 12 is stopped to stop the filtration operation. Is introduced into the filtration water chamber 7 of the hollow fiber membrane module 4 through the backwash water introduction pipe 50, and the treated water is passed from the outside to the inside of the hollow fiber membrane 6 in the direction opposite to the water flow direction in the filtration operation. I do. Drainage after washing (washing drainage) is
Is discharged from the washing water discharge pipe 16 through

[0031]

EXAMPLE An experiment was conducted using a vertical installation type internal pressure type tubular membrane device shown in FIG. The membrane module 4 includes an ultrafiltration membrane (UF membrane) hollow fiber membrane (LNV- manufactured by Asahi Kasei Corporation).
5010), a hollow fiber membrane module in which a number of tubes are vertically installed. In the experiment, for each of the three membrane modules used for the filtration treatment of the same raw water, the washing of the present invention consisting of the steps (1) to (4) in which water was drained by passing high-pressure gas, and the usual backwashing also described above. The measurement of the amount of decrease in the transmembrane pressure difference of the UF membrane and the analysis of the washing wastewater discharged from the washing water discharge pipe 16 were performed. In this case, the washing of the present invention was performed twice, with the amount of water used in the high-pressure water-passing step being 40 liters / module in the first experiment and 20 liters / module in the second experiment. Table 1 shows the results.

[0032]

[Table 1]

As can be seen from Table 1, the turbidity and TOC concentration of the washing wastewater in the cleaning of the present invention are much higher than those in the normal backwashing (less than 30 times as compared with the product of the concentration and the amount of water). According to this, it can be seen that the membrane contaminants attached to the inner surface of the hollow fiber membrane can be removed more effectively than ordinary backwashing. Therefore, it is determined that the cleaning of the present invention has a great effect on suppressing the increase in the transmembrane pressure difference of the UF film. Note that TOC is the main cause of the increase in the transmembrane pressure difference in the UF film, which has been confirmed in literatures, tests, and the like.

The following was also found from this experiment. When the properties of the washing drainage were observed during the first and second washing experiments according to the present invention, the gas-liquid interface passes through the UF membrane in the high-pressure water passage step and the high-pressure ventilation step in the first and second experiments, respectively. Occasionally, it was found that the wash effluent was specifically and limitedly turbid. Therefore, when the interface between the high-pressure water and the gas in the pipe or the interface between the high-pressure gas and the water in the pipe passes through the inner surface of the membrane, a strong shearing force is applied to the membrane contaminants attached to the inner surface of the tubular membrane. It was confirmed that the membrane contaminants on the inner surface of the tubular membrane were effectively peeled off by the shearing force.

In the second washing experiment according to the present invention, the amount of washing water was reduced to half of that in the first experiment, but the turbidity and TOC concentration of the washing wastewater almost doubled in the first experiment. It was found that the membrane contaminants can be effectively removed even if the amount of high-pressure water in the high-pressure water supply process is considerably reduced in the cleaning. In this case, judging from this experiment, the flow rate of high-pressure water in the high-pressure flow process can be further reduced than the flow rate of water in the second washing experiment according to the present invention. It is judged that it can be remarkably improved compared to washing.

[0036]

According to the present invention, it is possible to effectively remove the membrane contaminants adhering to the inner surface of the tubular membrane of the vertical installation type internal pressure type tubular membrane apparatus, and to remove the tubular contaminant existing at the center of the membrane module. Not only the membrane but also the tubular membrane existing around the membrane module can be cleaned well.

[Brief description of the drawings]

FIG. 1 is a flowchart showing an example of a vertical installation type internal pressure type tubular membrane device to which the present invention is applied.

FIG. 2 is a flowchart showing another example of the vertical installation type internal pressure type tubular membrane device to which the present invention is applied.

[Explanation of symbols]

 2 Raw water tank 4 Hollow fiber membrane module 6 Hollow fiber membrane 16 Cleaning water discharge pipe 18 Permeated water outflow pipe 22 Treated water storage tank 24 Concentrated water outflow pipe 25 High pressure water 27 High pressure gas 28 Water / gas pressurized tank 30 Cleaning water introduction pipe 36 High-pressure gas source 42 Water / gas introduction pipe 46 Air vent pipe

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoshiaki Nishimura 3-7-1, Ichibancho, Aoba-ku, Sendai, Miyagi Prefecture (72) Inventor Yasuyoshi Sato 1-2-8, Shinsuna, Koto-ku, Tokyo Olga F Co., Ltd. F-term (reference) 4D006 GA06 GA07 HA02 HA16 HA18 HA26 KA12 KA16 KA72 KC03 KC14 KC20 PC31 PC32

Claims (3)

[Claims] 1. A method for removing a membrane contaminant of a vertical installation type internal pressure type tubular membrane device, wherein after a filtration is completed, a part or all of water retained in the tubular membrane is drained from the inside of the tubular membrane. A high-pressure water passage step in which high-pressure water is passed from top to bottom in the tubular membrane after the drainage step, and a high-pressure ventilation step in which high-pressure gas is passed in the tubular membrane after the high-pressure water step from top to bottom. A method for removing membrane contaminants in a tubular membrane device, comprising: 2. The removal of membrane contaminants of a tubular membrane device according to claim 1, wherein in the draining step, part or all of the retained water is drained from inside the tubular membrane by passing a high-pressure gas from top to bottom into the tubular membrane. Method. 3. The method according to claim 1, wherein the high-pressure water-flowing step and the high-pressure aeration step are alternately performed a plurality of times after the draining step.