JP2003024938A - Membrane filter system and operation method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a membrane filter system capable of solving various points at issue in a healthiness evaluation method for a membrane module, capable of accurately and rapidly taking emergency disposal and restoration after the discovery of trouble and especially suitable for large-scaled water treatment equipment, and an operation method therefor. SOLUTION: In the membrane filter system repeating a process for passing water through the membrane module equipped with filter membranes and a backwashing process for the membrane module, when the healthiness of the membrane module or a membrane module group is judged on the basis of the number of fine particles in transmitted water or the turbidity of the transmitted water, the measurement of the number of fine particles in the transmitted water or the turbidity of the transmitted water for evaluating the healthiness of the membrane module or the membrane module group is stopped for a constant time from the start of the whole backwashing process and the water passing process.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for performing membrane filtration of various kinds of water to be treated and a method of operating the same, and more particularly to a membrane module such as a microfiltration membrane or an ultrafiltration membrane or a membrane module group. The present invention relates to a membrane filtration system capable of maintaining and managing the integrity of permeated water (filtrated water) without operating in an abnormal state during filtration, and an operating method thereof.

[0002]

2. Description of the Related Art In recent years, a water treatment device using a filtration membrane has come to be used in a water treatment device such as a pure water device, a desalination device, a water purification device, and a waste water treatment device. In particular, recently, the number of membrane filtration equipment used in water purification plants is increasing to remove protozoa that cannot be completely inactivated by chlorine, and the amount of treatment per treatment is increasing rapidly. Materials, modules, and operating methods have been introduced.

In the membrane filtration device, deterioration of the membrane itself, a bonded portion between the membrane and the casing, a casing material, and the like,
Alternatively, it is undeniable that the quality of the permeated water may deteriorate due to a sudden accident, poor production, etc. In particular, when membrane filtration equipment is adopted at water purification plants, sufficient consideration is required to ensure the uninterrupted safety of tap water and the amount of water supply.

However, at present, it cannot be said that the operation management has been sufficiently studied, and especially when the treatment amount becomes large, the permeated water caused by the trouble of some of the plurality of membrane modules Even if the water quality deteriorates, it will be diluted with the permeate of other healthy membrane modules.
It is extremely difficult to find troubles with membrane modules. In addition, even if some membrane modules have membrane breakage, cracks in the adhesive part, cracks in the structural material, etc., and the raw water and the permeated water are in communication with each other, the solids in the raw water will be in the communication part in the initial stage. There is a possibility that the blocking trouble will not be found.

After a trouble is found in the above-mentioned membrane filtration device, it is essential to take an urgent measure to promptly take measures while ensuring the treated water quality, safety, and water supply amount. Furthermore, after the emergency measures, the membrane module group or the membrane module that has caused the trouble must be identified and repaired or replaced to recover. These, (1) discovery of trouble,
It can be said that the membrane processing device can withstand reliability only after the operation management method of three stages of (2) emergency treatment and (3) restoration is established.

As a method related to the above (1), which has been proposed hitherto, a method has been proposed in which the membrane-permeated water is filtered again by another second membrane and the water flow differential pressure thereof is monitored. (Kaihei 6-15271, JP-A-7-60073). However, in this method, even if there is a problem in the membrane module, rapid detection cannot be performed if the differential pressure increase speed of the second membrane is low, and even if there is no problem in the membrane module, the difference in the second membrane This was a method with reliability issues such as increased pressure.

Further, gas (air) is present on the permeation side of the microfiltration membrane.
There is also proposed a method of pressurizing and encapsulating at about the bubble point to detect the presence or absence of bubbles from the membrane damage part by sound, and a method of sensing a decrease in the encapsulation pressure of gas. However, these are not methods that can be performed during normal continuous operation, but methods that are regularly checked. Therefore, the safety of filtered water cannot be ensured when the membrane module is damaged between regular checks. Also, in the test using pressurized air, air enters the inside of the membrane pores, so after the periodical confirmation, the air remaining in the membrane pores should be pressurized and volume-reduced with raw water before flowing out of the membrane during normal operation. Reduces the effective area of. This method is difficult to apply to a submerged membrane (also referred to as a submerged membrane) in which a membrane element is immersed in water because water cannot be pressurized. Further, this method has problems that the ultrafiltration membrane has a high bubble point and is difficult to carry out, and that if the area of the membrane increases, the rate at which air dissolves in water increases and the sensitivity decreases.

Another method for evaluating the soundness of the membrane module is to measure the turbidity of the permeate and fine particles, especially the number thereof.
A method of monitoring has been proposed (for example, Japanese Patent Laid-Open No. Hei 8).
-252440 publication). However, although the turbidity measurement of permeated water and the measurement of the number of fine particles have a high detection speed, there remains a problem that the detection value largely fluctuates and reliability is poor.

[0009]

Therefore, an object of the present invention is to solve the problems of the method for evaluating the integrity of a membrane module in the prior art as described above, and further to make an emergency measure and a recovery after a trouble is found. It is an object of the present invention to provide a membrane filtration system that can be accurately and quickly taken, and is particularly suitable for a large-scale water treatment facility, and an operating method thereof.

[0010]

In order to solve the above-mentioned problems, a method of operating a membrane filtration system according to the present invention is a permeated water in a water-passing step of passing water to be treated through a membrane module equipped with a filtration membrane. A membrane that obtains permeated water by repeating the backwashing step and the backwashing step in which the membrane module is backwashed with a part of the permeated water or another clear water. In the operating method of the filtration system, when determining the soundness of the membrane module or the membrane module group by the number of fine particles in the permeated water or the turbidity, the entire backwash process and the membrane module for a certain time from the start of the water passage process,
Alternatively, the method is characterized by stopping the measurement of the number of fine particles of permeated water or turbidity for evaluating the soundness of the membrane module group.

In this method, when the soundness of the membrane module or the membrane module group is judged by the number of fine particles or turbidity in the permeated water (filtered water), the sample water is measured before the number of fine particles or the turbidity is measured. It is preferable to perform defoaming and deaeration treatment on. When determining the soundness of a membrane module or a group of membrane modules by the number of fine particles or turbidity in permeated water, both defoaming degassing treatment and membrane concentration are performed on sample water before measurement of the number of fine particles or turbidity. Is preferably applied.

The defoaming degassing treatment is performed in at least two stages selected from defoaming tank (including centrifugal type), heating, decompression (including cavitation), ultrasonic irradiation and membrane degassing. It is preferable to have Further, in the defoaming deaeration treatment, it is preferable to perform the treatment at 50 ° C. under at least 1 atmosphere until a state where foaming does not occur.

Further, the sample water for measuring the number of fine particles or turbidity is preferably sampled from a pipe connecting the membrane module and a suction pump for permeated water. At this time, it is preferable to pass water through a sampling point of water for measuring the number of fine particles or turbidity, defoaming and deaeration, a device for measuring the number of fine particles or turbidity, and a suction pump for sample water.

Further, in the operation method of the membrane filtration system according to the present invention, as a treatment for the membrane module or the membrane module group evaluated to be abnormal by the above soundness evaluation, (a) the membrane module evaluated to be abnormal, Alternatively, the operation of the membrane module group is stopped, (b) the membrane module evaluated as abnormal, or the permeate of the membrane module group is returned to the raw water side, (c) the membrane module evaluated as abnormal,
Alternatively, the permeated water of the membrane module group can be used after re-filtration in a preliminary series, (d) the membrane module evaluated as abnormal, or the permeated water of the membrane module group can be used after re-filtration with an emergency safety filter. be able to.

Regarding the above-mentioned emergency safety filter,
Prior to an emergency, it is preferable to install and store it in a dry state.

In order to identify an abnormal membrane module from the membrane module group evaluated as abnormal, at least 30 times the designed filtered water amount (designed permeated water amount) of the module is specified.
It is preferable to specify it while maintaining the amount of filtered water of not less than%.

Further, in specifying an abnormal membrane module from the membrane module group evaluated as abnormal, it is preferable to first backwash all the membrane modules in the group and then specify the abnormal membrane module.

When the abnormal membrane module is specified or after the specification, the permeated water is treated as follows.
It can be selected from (a) use after re-filtration with a preliminary series, (b) use after re-filtration with an emergency safety filter, and (c) return to the raw water side.

The membrane filtration system according to the present invention is characterized in that the soundness of permeated water is maintained and managed by using the above operating method.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below along with preferred embodiments. It is common to use part of the permeated water for backflow cleaning of the membrane filtration device.For this cleaning water, either part of the permeated water should be stored in the backwash water tank in advance or treated during the backwash process. Part of the permeated water stored in the aquarium is applied. Cleaning water tanks and treated water tanks are often installed and used with the atmosphere open, and special sealing and water sealing are not performed. In the backwashing of the filtration membrane, the backwashing water is introduced from the permeate side of the membrane module to the treated water side, so that some fine particles are brought in from the backwashing water, its water pipe, rotating equipment, etc. during the backwashing process. The inventors of the present invention, when determining the soundness of the membrane module from the fine particle measurement value and turbidity measurement value of the permeated water, bring it to the membrane module by the backwash step if the elapsed time from the start of the water passing step is short. It was confirmed that the generated fine particles and the like greatly exceeded the value that should be detected in the permeated water, and issued an abnormal alarm to the normal membrane module.

As a result of further examination, if the water in the water conduit used to transfer the water in the membrane module and the permeated water is replaced with the permeated water after the water-passing step is started, the fine particles brought in by the backwash will be removed. It was found that the influence on the measured number of fine particles and the measured value of turbidity is eliminated.

Therefore, when finally determining the soundness of the membrane module from the measured values of the number of fine particles of permeated water and the measured value of turbidity, the inventors of the present invention measured the number of fine particles for a certain time after the start of the water passing step. Alternatively, by suspending (stopping) the turbidity measurement, it was found that no abnormal alarm was issued to the sound module, and the present invention was completed. Further, it was confirmed that this rest time is preferably in the range of 30 seconds to 30 minutes, more preferably 5 minutes to 20 minutes. Stopping the particle number measurement or turbidity measurement described here is not only the method of suspending the measuring instrument main body, but also the method of suspending only the measurement signal output, the method of suspending only the measurement signal input and the alarm generator. This is a concept including all the methods such as the method of not using the particle count measurement value and the turbidity measurement value in the alarm activation circuit.

Although the turbidity of the permeated water and the number of fine particles are detected at a high detection speed, the detection value varies greatly and the reliability of the membrane module is sometimes unreliable. As a cause, the effect of bubbles present in the permeate is pointed out (that is, bubbles are detected as measured values). However, even if the number of fine particles was measured after removing the air bubbles, there were cases where the detected value was abnormally high. Therefore, the present inventors proceeded with further studies, and the gas dissolved in the permeated water became fine bubbles due to the pressure difference between the primary side and the secondary side of the membrane, which affects turbidity measurement and fine particle number measurement. It has been revealed that

Therefore, in order to improve the reliability of the turbidity measurement and the fine particle number measurement when evaluating the soundness of the membrane module or the membrane module group, the permeated water should be at least defoamed, preferably defoamed. It is important to perform air treatment to measure turbidity and the number of fine particles.

Here, the defoaming means removing the gas phase generated in water to the outside of the liquid, and is carried out by a defoaming tank (including a centrifugal type). Defoaming can also be performed by using a decompression method using a degassing membrane using a hydrophobic porous membrane such as polypropylene, polyethylene, polytetrafluoroethylene, or polymethylpentene.
In order to make the defoaming more complete, it is also possible to accelerate foaming by some means and then defoam. Examples of methods for promoting foaming include heating, depressurization, and ultrasonic irradiation. As a depressurizing method, it is possible to use a method of providing a siphon structure in a water pipe for taking out filtered water from the membrane module or a suction pump for sucking filtered water. On the other hand, deaeration means not removal of bubbles but removal of gas components dissolved in water from the water. Decompression, a membrane deaeration method (hydrophobic porous membrane, non-porous membrane was used. Decompression method) etc. In the present invention, it is preferable to perform the treatment in at least two stages selected from these, whereby the defoaming and deaeration treatment can be performed more reliably.

Further, the inventors cannot obtain sufficient sensitivity even if the membrane module is obviously damaged even if the method of measuring the turbidity and the number of fine particles after the defoaming degassing treatment is used. I confirmed that there is a case. As a cause, when the hollow fiber of the membrane module or the damage to the adhesive part is a relatively small crack, after a long time, solid matter such as suspended matter in the treated water clogs the crack during the filtration step. , It was found that there is a case where the treated water and the treated water (permeate) do not communicate with each other in the same manner as the apparently healthy module. Therefore, in such a case, it is particularly important to set the measurement stop time in the present invention to be appropriately short, for example, within the range of 30 seconds to 30 minutes as described above. Further, in such a case, immediately after the backwashing step, the solid material having the cracks clogged is discharged, and the discharging state is maintained for at least a while, so that the measurement is performed after the stop time in the present invention. It is also possible to detect the abnormality of the membrane module from the measured value of turbidity in the permeated water and the measured value of the number of fine particles.

Further, the blockage of the membrane module such as cracks is caused by
It occurs more frequently when the amount of filtered water (permeated water) is smaller,
It was found that the larger the amount of filtered water, the less the frequency of crack closure. That is, in a state where the amount of filtered water per membrane module is small, the abnormality of the membrane module may not be detected due to the clogging of cracks and the like, and when the abnormality of the membrane module is to be detected more reliably, the filtration of the membrane module is performed. It has been found that increasing the amount of water is more effective, and it is desirable to maintain the amount of filtered water at 30% or more of the designed amount of filtered water so that the abnormal membrane module can be specified under that condition.

The clogging phenomenon such as cracks in the membrane module as described above is a phenomenon peculiar to the immersion type membrane module in which the permeated water is taken out by the suction force of the suction pump. This is a phenomenon that is rarely seen in casing-containing membrane modules that obtain water.

When the operation of the membrane filtration device in which the abnormality of the membrane module or the membrane module group is detected by the above method is continued, the following measures can be taken. When there is a margin in the scale of the device compared to the required amount of treated water, the water flow to the module or module group itself that has been diagnosed as abnormal is stopped. When there is no margin in the amount of treated water, the permeated water from the module or module group that is diagnosed as abnormal is returned to the raw water side, and when it is necessary to secure a treated water amount above a certain level, The permeated water from the module or group of modules diagnosed as abnormal is re-filtered by a preliminary membrane filtration series to obtain filtered water. If it is necessary to ensure the safety of the treated water and the amount of water supply, especially in the case of clean water treatment, re-filter with an emergency safety filter installed in advance. When no abnormality is detected in the membrane module or the membrane module group, the emergency safety filter described here is preferably suspended in a water-free state from the viewpoints of protection of the apparatus, saving of operating costs, and the like. Therefore, it is desirable to use a filtration membrane made of polyolefin or polyethylene, a filtration element made of ceramics, or a metal, which can be dried and stored, for the emergency safety filter. In addition, as an emergency safety filter, it is possible to use ultrafiltration membranes, microfiltration membranes, or any other type of separation pore size, but in consideration of keeping the power consumption low and dealing with large filtration volumes, Desirably, a membrane or filter having a separation pore diameter of 0.1 μm or more is preferably used.

The membrane filtration device targeted in the present invention is any membrane filtration device that obtains filtered water from the water to be treated using a casing storage method, a tank immersion method, or the like.

The membrane module used in the membrane filtration device is not limited as long as it can be applied to the water treatment device, and has any shape such as a flat membrane, a tubular membrane, a hollow fiber membrane and a spiral membrane. Can be used. In addition, there is no limitation on the film material used, and any organic material film such as cellulose acetate, polyacrylonitrile, polypropylene, polyethylene, polyolefin, polyvinylidene fluoride, polyether sulfone and polyamide, ceramics, stainless steel, carbon, etc. Material membrane is applicable

[0032]

Embodiments of the present invention will be described below with reference to the drawings. In each of the following examples, sampling of permeated water for evaluating the soundness of the membrane module or the membrane module group is shown by a flow performed after treatment with a defoaming tank or an ultrafiltration membrane for concentration. However, in the present invention, it is also possible to directly sample from the permeated water without performing these treatments.

Example 1 The variation in the measured number of fine particles of permeated water after the start of water passage was examined. When judging the damage of the membrane module from the measured value of the number of fine particles of the permeated water, the influence of the measured value of the number of fine particles by the backwash water, the fine particles brought from the piping, the rotating equipment, etc. was confirmed.

In the membrane filtration system shown in FIG. 1, raw water as the water to be treated 1 introduced by the introduction pipe 2 is pressurized by the pressure pump 3 and supplied to the membrane modules 4A and 4B.
Membrane filtered. The permeated water 6 after the membrane filtration is sent to the filtered water tank 7 through the water conduit 5 and is stored therein. Although FIG. 1 shows a so-called total filtration type membrane filtration system in which the entire amount of the water to be treated supplied to the membrane module is filtered and taken out as permeate 6, the present invention is not limited to this. Alternatively, a cross-flow system membrane filtration system may be used in which a part of the water to be treated is taken out as concentrated water without permeating the membrane. A water guiding pipe 8 is branched from the water guiding pipe 5, and a part of the permeated water 6 is collected as measurement sample water and sent to a defoaming tank 9 to be defoamed. The degassed sample water is used for concentration ultrafiltration membrane (UF concentration membrane) 10
After being concentrated in, it is introduced into the fine particle meter 11. From the filtered water tank 7, the stored treated water (permeated water) is backflowed to the membrane modules 4A and 4B as backwash water during the backwash step via the water conduit 12 and the backwash pump 13.

Toda City industrial water was used as raw water. The membrane modules 4A and 4B have a microfiltration membrane with a separation pore diameter of 0.2 μm (MEMCOR CMF, manufactured by US Filter Co., Ltd.).
Water was passed through at a filtration flow rate of 26 m ³ / day. FB02 (manufactured by Daisen Membrane Systems Co., Ltd.) was used as the UF membrane 10 for concentrating sample water, and the amount of filtered water was 0.14 m ³ /
The sample water for the measurement of the number of fine particles was concentrated about 3 times on the condition that the concentrated water amount was 0.7 m ³ / day. A laser beam scanning type fine particle meter (SLPC, manufactured by Organo Corporation) was used as the fine particle meter 11.

Using the system of FIG. 1, the membrane module 4
0.2 to 0.5 when A and 4B are normally operated
Change in the measured value of the number of fine particles of μm, measured value of the number of fine particles of 0.2 to 0.5 μm when 10 hollow fibers were intentionally cut only in the membrane module 4A, 30 seconds after the start of the water passing step, 1
Measurements were made at the time points of min, 5 min, 10 min, and 20 min, and comparison was made. The results are shown in Table 1.

[0037]

[Table 1]

It is confirmed from Table 1 that in Example 1, the measured value of the number of fine particles is not affected by the backwash water in about 10 minutes after the start of the water passing process, and the fine particle measurement is performed for a certain time after the start of the water passing process. It was confirmed that it was necessary to stop.

Example 2 The effect of the defoaming treatment and the membrane concentration on the integrity evaluation of the membrane module was confirmed. When judging the damage of the membrane module etc. from the measured number of fine particles in the filtered water, when the sample water for measuring fine particles is directly introduced into the fine particle meter, when defoaming treatment is introduced into the fine particle meter, the membrane is concentrated and the fine particle meter is measured. Introduced into, the measurement sensitivity was compared and examined for the four methods of defoaming treatment and further membrane concentration.

FIG. 2 shows the membrane filtration system according to the second embodiment.
Shown in. In FIG. 2, the sample water sampling conduit 8 branched from the membrane-filtered permeate conduit 5 from the membrane modules 4A and 4B is provided with the above-mentioned four treatment methods by switching the respective valves. A defoaming tank 9 and a concentration UF membrane 10 are provided so that the sample water can be introduced into the total 11. The raw water, the membrane, the measuring instruments and their operating conditions used in this Example 2 are the same as those used in Example 1, and the configuration of the raw water introduction line is also the same as in Example 1.

Membrane module 4 using the system of FIG.
When A and 4B are operating normally and when 10 hollow fibers of the membrane module 4A are intentionally cut, 0.2
Changes in the measured values of the number of fine particles of ˜0.5 μm were compared. The results are shown in Table 2.

[0042]

[Table 2]

From Table 2, when comparing the measured values of the number of fine particles of the filtered water of the ordinary membrane module and the membrane module obtained by cutting the hollow fiber, the method of using defoaming and membrane concentration in the treatment of sample water, only defoaming It was confirmed that the difference was large in the order of the method. Therefore, it was confirmed that defoaming of the sample water is effective when determining the presence or absence of abnormality of the membrane module by measuring the number of fine particles, and it is more effective to use defoaming and membrane concentration together.

Example 3 Mainly, the effect of defoaming degassing treatment in two stages was confirmed. When determining damage to the membrane module from the measured number of fine particles in the filtered water, the sensitivity of the sample water for measuring the number of fine particles when degassing, degassing, or degassing is improved The effects were compared and examined.

FIG. 3 shows the membrane filtration system according to the third embodiment.
Shown in. In FIG. 3, the dipping tank 14 is used as a membrane module.
Immersion membrane module 15A, 15B immersed in water inside
Is used, and the permeated water 6 is obtained by suction filtration through the water conduit 5 and the suction pump 16. As a line for evaluating the soundness of the membrane, a water guiding pipe 5 is branched from a water guiding pipe 5, and a defoaming device 17 and a degassing treatment device 1 are provided.
Introduce a part of permeate into 8 and further concentrate UF membrane 10
After being concentrated in 1, the water is sent to the fine particle meter 11 so that the number of fine particles can be measured. The suction pumps 19 and 20 collect the sample water into the fine particle measurement line. The defoaming device 17 is provided with any one of a defoaming tank, a degassing film, a heating device, and an ultrasonic irradiation device.
Vacuum degassing or degassing membrane is installed in the, and by switching the valve, defoaming processing and degassing processing can be performed independently,
It is possible to select whether to continuously perform the defoaming process and the degassing process.

Toda city industrial water was used as raw water. The immersion membrane modules 15A and 15B have a separation hole diameter of 0.1 μm.
The microfiltration membrane (UMF5024LA, manufactured by Mitsubishi Rayon Co., Ltd.) was used to pass water at a filtration flow rate of 50 m ³ / day. FB02 (manufactured by Daisen Membrane Systems Co., Ltd.) was used as the UF membrane 10 for concentrating sample water, and the filtered water volume was 0.
14m ³ / day, it was concentrated sample water to the particulate number measured by water flow conditions of the concentrate water 0.7 m ³ / day to about 3 times. The fine particle meter 11 includes a laser beam scanning fine particle meter (SLP
C, manufactured by Organo Co., Ltd. was used. For degassing membrane, "LIQ
UICEL "(manufactured by Celgard Co., Ltd.) is used to accelerate degassing by suctioning and decompressing with a vacuum pump (not shown).

Using the system of FIG. 3, the membrane modules 15A and 15B are operated normally and the hollow fiber 1 of the membrane module 15A is the same as the method performed in Examples 1 and 2.
The case where 0 pieces were intentionally cut was reproduced, and it was compared and examined whether the difference in the measured number of fine particles of 0.2 to 0.5 μm of filtered water could be detected by combining various defoaming treatments and degassing treatments. . The results are shown in Table 3.

[0048]

[Table 3]

From Table 3, although there is a difference depending on each defoaming degassing process and each combination, when the soundness of the membrane module is judged from the measured value of the number of fine particles of the permeated water, the defoaming degassing process is continued. It was confirmed that the sensitivity was better in the case of. It was also confirmed that when the heat treatment was used, the effect was more remarkable by heating to 50 ° C. or higher.

Example 4 A comparison was made of methods for introducing membrane filtration sample water into a fine particle meter. In other words, when judging the damage of the membrane module from the measured value of the number of fine particles of the permeated water, it was compared and examined whether or not the method of introducing the sample water for fine particle measurement into the fine particle meter has an influence on the sensitivity.

In the system shown in FIG. 4, three series of measurement lines are installed for comparison of the method of measuring the number of fine particles, and the first series is a water conduit 8A branched from the water conduit 5 of permeate. The permeated water through the degassing membrane 21A, UF for concentration
The permeated water is sucked by the suction pump 20 while being introduced into the membrane 10A and the fine particle meter 11A. In the second series, through the water conduit 8B branched from the water conduit 5 of the permeated water, and using the suction water pump 22 installed there, to the degassing membrane 21B, the UF membrane 10B for concentration, and the fine particle meter 11B. It is configured to conduct water. The third series is a degassing membrane 21 via a water conduit 8C branched from the water conduit 5 part in the latter stage of the suction pump 16.
C, the UF membrane 10C for concentration, and 11 C of fine particle totals are comprised by the structure which introduce | transduces water. The raw water used for the operation, the membrane module, the deaeration membrane, the equipment, and the operating conditions are the same as those described in the third embodiment.

Using the system of FIG. 4, Examples 1, 2,
Similar to the method performed in 3, the case where the membrane modules 15A and 15B are normally operated and the case where 10 hollow fibers of the membrane module 15A are intentionally cut are reproduced, and 0.2 to 0. Whether or not the sensitivity of the measured value of the number of fine particles of 5 μm was changed in the three series of fine particle measurement series was compared and examined. The results are shown in Table 4.

[0053]

[Table 4]

From Table 4, when comparing the measured values of the number of fine particles of the permeated water of the normal membrane module and the membrane module obtained by cutting the hollow fiber, the difference in the measured values of the number of fine particles is more remarkable in the equipment arrangement of the first series. It was confirmed that it was effective in judging the soundness of the membrane module. Therefore,
It was confirmed that it is preferable to pass water in the order of the sampling point of the water for measuring the number of fine particles, the (degassing) degassing treatment, the fine particle meter, and the suction pump for sample water.

Example 5 Mainly, the influence of the amount of filtered water on the measured value of the number of fine particles of permeated water was examined. That is, when judging the damage of the membrane module or the like from the measured value of the number of fine particles of the permeated water, it was compared and examined whether or not the change of the amount of filtered water affects the sensitivity of the measured value of the number of fine particles.

The system shown in FIG. 5 has a system configuration in which the backwash of the membrane modules 15A and 15B can be carried out by using the permeated water by using the suction pump 16, and the permeated water for the backwash is stored. The backwash water tank 23 is added to the apparatus of FIG. During the backwash process, the permeated water stored in the backwash water tank 23 is changed to the backwash line 24.
The water is sent to the submerged membrane modules 15A and 15B through the backwash line 25 and the water conduit 5 by the suction pump 16 via the. A defoaming tank was used as the defoaming device 17.

The operation of the system was carried out continuously by repeating the steps of water passage for 120 min and backwashing for 1 min. The amount of backwash water was 72 L / min. The raw water, membrane module, equipment, and operating conditions used for other operations are the same as those described in the third embodiment.

Using the system of FIG. 5, Examples 1, 2 and
Similar to the method performed in 3, the case where the membrane modules 15A and 15B are normally operated and the case where 10 hollow fibers of the membrane module 15A are intentionally cut are reproduced, and the amount of filtered water is 20% of the designed filtration flow rate. = 5.2 m ³ / day, 30% = 7.
8m ³ / day, 50% = 13m ³ / day, 100% = 26m
^It was changed between ³ % / day and 120% = 31 m ³ / day, and whether or not the difference in the measured values of the number of fine particles of filtered water of 0.2 to 0.5 μm could be detected was compared and examined. The results are shown in Table 5.

[0059]

[Table 5]

From Table 5, it can be seen that the number of fine particles of the permeated water is different between the normal membrane module and the backwashing of the membrane module obtained by cutting the hollow fiber 30 minutes (that is, after the passage of the fine particle number measurement stop time in the present invention described above). When the measured values were compared for each filtered water amount, it was confirmed that if the filtered water amount was secured at 30% or more of the designed filtered water amount, a difference would occur in the measured value of the number of fine particles when measuring after backwashing. It was found to be effective in judging the soundness of the module. In other words, the design filtered water volume of 2
When the amount of filtered water is as low as 0%, the cut membrane module may be clogged with fine particles or the like, which may cause an overlap area with the measured value in a normal membrane module.
It was found that there may be cases where the soundness of the membrane module cannot be accurately determined.

Example 6 As Example 6, a membrane filtration system according to one embodiment of the present invention is shown in FIG. The system shown in FIG.
A, 14B, submerged membrane modules 15A, 15B and 1
5C, 15D, two membrane filtration series consisting of suction pumps 16A, 16B, and a defoaming device 17 for judging the soundness of the filtration water tank 7, the backwash pump 13 and the submerged membrane module,
It is composed of a concentration UF membrane 10, a fine particle meter 11 and an emergency safety filter 31.

Raw water 1 as water to be treated is introduced through an introduction pipe 2A, 2B branched from an introduction pipe 2 into a dipping tank 1 respectively.
It is supplied to 4A and 14B. Immersion membrane modules 15A and 15B are installed in the immersion tank 14A, and immersion membrane modules 15C and 15D are installed in the immersion tank 14B, and each module is equipped with a suction pump 16A via water conduits 5A and 5B. , 16B, the permeated water 6 is obtained by suction filtration, and is stored in the filtered water tank 7 by the water conduits 32A, 32B.

As a backwash line, a filtered water tank 7 is used.
The backwash pump 13 is connected from the backwash pump 13 through the water conduit 12 from the backwash pump 13 to the backwash lines 33A and 33B.
Are connected to water conduits 5A and 5B, respectively. At the time of backwashing, filtered water (permeate) is backflowed to each membrane module by the above backwashing line to carry out backwashing. The drainage water from each membrane module at the time of backwashing is released into the dipping tanks 14A and 14B, and the excess water level is discharged from the drainage pipes 34A and 34B.

Water conduits 8D and 8E are branched from the water conduits 5A and 5B to a fine particle measuring line for judging the soundness of each membrane module. The sample water of the permeated water from the membrane module is replaced with the water conduit 8D at regular intervals.
Defoaming device 17 consisting of a defoaming tank, U for concentration through 8E
It is guided to the F film 10. The permeated water of the UF membrane 10 is the water conduit 3
5, it is collected in the filtered water tank 7 by the pump 19. The concentrated water from the concentration UF membrane 10 is introduced into the fine particle meter 11 through the water conduit 36 by the suction pump 20 and the number of fine particles is measured. The waste water after the measurement of the number of fine particles is collected in the filtered water tank 7 through the water conduit 37.

When an abnormality is detected in each membrane module group from the measurement result of the number of fine particles of the sample water, the filtered water line obtained through the water conduit 32A or 32B is used as the line 38A or 38 in which the emergency safety filter 31 is installed.
Switch to B. Filter permeated water is collected from the emergency safety filter 31 through the water conduit 39 to the filtered water tank 7.

In such a system, each membrane module group 15A, 15B or 15 evaluated as abnormal
In the case of identifying a further abnormal membrane module from C and 15D, it is possible to switch the permeated water from each membrane module and send the permeated water of the selected membrane module to the measurement system for evaluation. Good. At that time, first, all the membrane modules in the group may be backwashed, and after a certain measurement stop time according to the present invention, the abnormal membrane module may be specified as described above. As a result, even if the abnormal membrane module cracks are partially clogged with solids, the backwashing removes the clogged solids. Is significantly increased, so that the abnormal membrane module can be identified more reliably.

In the above description of each embodiment, the abnormality of the membrane module is judged from the measurement result of the number of fine particles in the sample water, but in the present invention, the measurement object can be turbidity. In this case, in that case, the fine particle meter in each of the above-described embodiments may be changed to a turbidimeter.

[0068]

As described above, according to the present invention,
The integrity of the membrane module can be reliably evaluated, and
It is possible to provide a method capable of surely executing the operation management method of the membrane filtration device regarding the emergency treatment and restoration after the trouble of the membrane module is discovered, and the membrane filtration system for implementing those methods.

[Brief description of drawings]

FIG. 1 is a device system diagram of a membrane filtration system according to a first embodiment of the present invention.

FIG. 2 is a device system diagram of a membrane filtration system according to a second embodiment of the present invention.

FIG. 3 is a device system diagram of a membrane filtration system according to a third embodiment of the present invention.

FIG. 4 is a device system diagram of a membrane filtration system according to a fourth embodiment of the present invention.

FIG. 5 is a device system diagram of a membrane filtration system according to a fifth embodiment of the present invention.

FIG. 6 is a device system diagram of a membrane filtration system according to a sixth embodiment of the present invention.

[Explanation of symbols]

1 treated water 2, 2A, 2B introduction pipe 3 pumps 4A, 4B, 15A, 15B, 15C, 15D membrane modules 5, 5A, 5B water conduit 6 permeated water 7 filtered water tanks 8, 8A, 8B, 8C, 8D, 8E Sample water conduit 9 Defoaming tank 10 Concentration ultrafiltration membrane 11 Fine particle meter 12 Backwash conduit 13 Pump 14 Immersion tank 16 Suction pump 17 Defoaming device 18 Degassing device 19, 20 Suction pumps 21A, 21B, 21C Degassing membrane 22 Pump 23 Backwash water tank 24, 25 Backwash line 31 Emergency safety filter 32A, 32B Water conduit 33A, 33B Backwash line 34A, 34B Drain pipe 35, 36, 37 Water conduit 38A, 38B Emergency safety Line to filter 39 Conduit to filtration tank

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) B01D 19/02 B01D 19/02 61/20 61/20 61/22 61/22 65/02 65/02 F Terms (reference) 4D006 GA06 GA07 HA93 HA95 JA51Z JA52Z JA53Z JA55Z JA59Z JA71 KA12 KA61 KA67 KA90 KC03 LA01 LA03 LA08 MA01 MA02 MA03 MA04 MC02 MC03 MC05 MC18 MC22 MC23 MC29 MC39 MC54 MC62 PA01 PB02 4D011 AD17 AA02 AA16 AA12 AA12 A16 AA12 AA12 AA16 AA12 AA16 AA16 AA12 AA17 AA16 AA12 AA16 AA16 AA02

Claims (14)

[Claims] 1. Backwashing in which permeate is obtained by a water-passing step of passing treated water through a membrane module equipped with a filtration membrane, and the membrane module is backwashed with a part of the permeate or other clear water. In the operating method of the membrane filtration system, which is performed after the water passing step and obtains the permeated water by repeating the water passing step and the backwashing step, the soundness of the membrane module or the membrane module group is determined by the number of fine particles in the permeated water. Alternatively, when judging by turbidity, the number of fine particles of permeated water or turbidity to evaluate the integrity of the membrane module or membrane module group should be measured for a certain period of time from the start of the entire backwashing process and the start of the water passing process. A method of operating a membrane filtration system, characterized by stopping. 2. When the soundness of a membrane module or a group of membrane modules is judged by the number of fine particles or turbidity in permeate, the sample water is subjected to defoaming deaeration treatment before the measurement of the number of fine particles or turbidity. A method for operating the membrane filtration system according to claim 1. 3. When determining the soundness of a membrane module or a membrane module group based on the number of fine particles or turbidity in permeated water, defoaming and deaeration treatment of a sample water and membrane before measurement of the number of fine particles or turbidity. The method for operating a membrane filtration system according to claim 1, wherein concentration is performed. 4. Defoaming degassing treatment is at least 2 selected from defoaming tank, heating, decompression, ultrasonic irradiation and membrane degassing.
4. The method according to claim 2, further comprising a step processing.
The method for operating the membrane filtration system according to claim 1. 5. In the defoaming degassing process, at least 1
The treatment is performed at 50 ° C. under atmospheric pressure to a state where foaming does not occur.
5. A method for operating the membrane filtration system according to any one of 4 to 4. 6. The method of operating a membrane filtration system according to claim 1, wherein the membrane module comprises a submerged membrane. 7. The method of operating a membrane filtration system according to claim 6, wherein sample water for measuring the number of fine particles or turbidity is sampled from a pipe connecting a membrane module and a permeate suction pump. 8. The membrane according to claim 6, wherein the sampling point of the water for measuring the number of fine particles or turbidity, defoaming and degassing, a device for measuring the number of fine particles or turbidity, and a suction pump for sample water are passed in this order. How to operate the filtration system. 9. A treatment for a membrane module or a membrane module group evaluated to be abnormal by the soundness evaluation,
(A) Shutdown of the membrane module or membrane module group evaluated to be abnormal, (b) Return of the permeated water of the membrane module or membrane module group evaluated to be abnormal, to the raw water side, (c) Evaluation as abnormal The permeated water of the membrane module or membrane modules that has
(D) The membrane filtration system according to any one of claims 1 to 8, wherein the permeated water of the membrane module evaluated as abnormal or the permeated water of the membrane module group is used after being re-filtered with an emergency safety filter. how to drive. 10. The method for operating a membrane filtration system according to claim 9, wherein the emergency safety filter is stored in a dry state before an emergency occurs. 11. The method according to claim 1, wherein an abnormal membrane module is identified from the membrane module group evaluated to be abnormal, while maintaining an amount of permeated water of at least 30% of the designed permeated water amount of the module. A method for operating the membrane filtration system according to claim 1. 12. When specifying an abnormal membrane module from a membrane module group evaluated as abnormal, first, all membrane modules in the group are backwashed, and then the abnormal membrane module is specified. A method for operating the membrane filtration system according to any one of 1. 13. When the abnormal membrane module is specified, or after the specification, the permeated water is treated (a) after re-filtration with a preliminary series and (b) after re-filtration with an emergency safety filter. 13. The method for operating the membrane filtration system according to claim 1, wherein the method is selected from utilization and (c) returning to the raw water side. 14. A membrane filtration system, characterized in that the operating method according to any one of claims 1 to 13 is used to maintain and manage the soundness of permeated water.