JP2002059163A - Method of maintaining and managing immersion type membrane separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of maintaining and managing an immersion type membrane separator which is capable of exactly recognizing the operating conditions of the immersion type membrane separator and the characteristics of activated sludge, allows the use of a membrane cartridge to the longest life by regenerating and using the membrane cartridge and allows the easy maintenance of the immersion type membrane separator. SOLUTION: The immersion type membrane separator 21 is provided with a pressure measuring means 35 for measuring the driving pressure acting on the membrane surface of the membrane cartridge 22 and a means 37 for measuring the amount of permeated water for measuring the amount of the treated water flowing in a treated water take-out system. The correlation between the driving pressure and the amount of the permeated water as well as the operating conditions of the immersion type membrane separator and the characteristics of the activated sludge is previously determined as empirical rule. In operating, the operating conditions of the immersion type membrane separator and the characteristics of the activated sludge are judged by referencing the empirical rule with the fluctuation tendencies obtained by continuously measuring the driving pressure and the amount of the permeated water as indices and whether the exchange of the membrane cartridge 22 is needed or not is determined in accordance with the results of the judgment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for maintaining a submerged membrane separation apparatus, and more particularly to a technique for using an organic flat membrane cartridge in a membrane separation activated sludge method.

[0002]

2. Description of the Related Art Conventionally, in the gravity separation type activated sludge method shown in FIG. 4, raw water 1 is guided to an activated sludge tank 2, and organic components in the raw water are biologically separated by activated sludge (aggregate of various microorganisms). After that, the mixed liquid in the activated sludge tank 2 with the activated sludge is guided to the settling tank 3 for gravity separation, and a part of the settled activated sludge is returned to the activated sludge tank 2 and excess sludge is removed. It is discharged outside the system.

In the gravity separation type activated sludge method, a phenomenon called bulking occurs in which the treated water and the activated sludge cannot be separated by gravity depending on the properties of the activated sludge, and troubles facility managers. If bulking occurs, it may take several months to recover. If bulking is severe, activated sludge flows out of the tank together with the treated water, resulting in deterioration of treated water quality.

[0004] As a control index in the gravity separation type activated sludge method, there is an SV value for measuring the settling property of the activated sludge.
This was to measure how much the sludge interface settled by allowing the mixture in the tank to stand for 30 minutes. However, since the SV value is measured manually on site, the measured value is subjectivity of the measurer, and even if the SV value is measured every day, the properties of the activated sludge cannot be controlled.

On the other hand, in the membrane separation activated sludge method, the solid-liquid separation of the treated water and the activated sludge is performed by the immersion type membrane separation apparatus, so that a stable solid-liquid separation can be performed regardless of the concentration and properties of the activated sludge. The treated water quality is also very good if the membrane unit is normal.

In this membrane separation activated sludge method, an immersion type membrane separation device is immersed in an activated sludge tank, and only treated water is taken out of the activated sludge mixture through each membrane cartridge of the immersion type membrane separation device. . In the immersion type membrane separation device, accidents may occur in which the flow path between the membrane cartridges is blocked by activated sludge, the flow path is clogged with foreign substances, or the membrane surface of the membrane cartridge is damaged by hard foreign substances. In order to have a structure in which each of the membrane cartridges can be individually inspected and replaced, a plurality of membrane cartridges are individually and detachably inserted into a membrane case to form a membrane module. . According to this structure, if only the damaged membrane cartridge is replaced, the function of the immersion type membrane separation device can be restored, and the maintenance cost can be reduced. In case of troubles such as sludge obstruction, the membrane cartridge can be pulled up and washed on site to immediately return to normal operation.

[0007]

However, the membrane separation activated sludge method has a problem that when an abnormality occurs in the immersion type membrane separation apparatus, no treated water is discharged and the inflowing raw water cannot be treated. For this reason, it is important to understand not only the operation status of the immersion type membrane separation device but also the properties of the activated sludge.

The life of the membrane cartridge is normally distributed between the third and seventh years, and the average life is about 5 years. For this reason, it is not known when the replacement time will occur between the third and seventh years, and if the damaged membrane cartridges are replaced individually one by one, the replacement time will occur in the May rain type, and the frequency will increase and the maintenance will become complicated and complicated. There was a problem.

Incidentally, the membrane cartridge can be reused as a regenerated membrane cartridge if it is reinforced before the end of its life. Therefore, if an abnormal membrane cartridge is discarded when an abnormality occurs in a part of the membrane cartridges of the membrane module, and the other membrane cartridges are regenerated, many membrane cartridges can be used up to the longest service life.

The present invention has been made to solve the above-mentioned problems, and it is possible to accurately ascertain the operating conditions of an immersion type membrane separation apparatus and the properties of activated sludge, and to regenerate and use a membrane cartridge to reuse it. It is an object of the present invention to provide a method for maintaining and managing a submerged membrane separation apparatus, which enables the use of a submerged membrane membrane for the longest life and allows easy maintenance of the submerged membrane separation apparatus.

[0011]

According to a first aspect of the present invention, there is provided a method for maintaining and controlling a submerged membrane separation apparatus, comprising a plurality of flat membrane cartridges arranged vertically. A membrane module is formed by arranging the membrane module in parallel with a suitable gap inside, immersing the membrane module in the activated sludge tank, disposing an air diffuser below the membrane module, and passing through the permeated liquid flow path of each membrane cartridge. In a immersion type membrane separation device provided with a treated water extraction system in communication, a pressure measuring means for measuring a driving pressure acting on the membrane surface of the membrane cartridge and a permeated water amount measurement for measuring an amount of treated water flowing through the treated water extraction system Means, the correlation between the driving pressure and the amount of permeated water and the operating conditions of the immersion type membrane separation device and the properties of the activated sludge is determined as an empirical rule, and the fluctuation obtained by continuously measuring the driving pressure and the amount of permeated water during operation Toward the light of the heuristics as an index to determine the nature of the operating conditions and the activated sludge of the submerged membrane separator, it is what determines the necessity of replacement of film cartridge on the basis of the determination result.

In the above configuration, in normal operation,
The upward flow generated by the air lift action of the air ejected from the air diffuser circulates in the tank as a gas-solid liquid flow of air, activated sludge, and treated water. The internal mixture is supplied in a cross flow. In addition, the upward flow acts as a sweep on the membrane surface of the membrane cartridge, and suppresses the attachment of sludge to the membrane surface.

In this state, the mixed solution in the tank is filtered through each membrane cartridge, and the filtrate is taken out of the tank through a treated water take-out system. The filtration operation of the membrane cartridge is performed by a gravity filtration method using a water head pressure in a tank as a driving pressure or a suction filtration method using a suction pressure of a suction pump provided in a treated water extraction system as a driving pressure.

The fluctuation tendency of the measured values obtained by continuously measuring the driving pressure and the amount of permeated water has a correlation with the operating condition of the immersion type membrane separation device and the properties of the activated sludge. For example, during the entire operation period of 3 to 6 months in which the continuous operation is performed, the operation condition of the immersion type membrane separation device is good, and no damage to the membrane cartridge or clogging of the flow path between the membrane cartridges is caused. If the properties of the water are sound and bulking does not occur, the amount of permeated water will maintain a stable value throughout the entire operation period, and the driving pressure required to obtain the planned amount of permeated water will gradually increase at the end of the operation period. Show.

In this case, the function of the immersion type membrane separation device is restored by washing the membrane cartridge with a chemical solution.
In addition, when the cause of the mechanical abnormality is present, the driving pressure tends to increase within one to several days after the start of the operation, and the planned permeated water amount cannot be obtained even when the driving pressure is controlled to the upper limit.

In this case, a sufficient sweeping does not act on the membrane surface of the membrane cartridge due to an abnormality of the air diffuser, and the flow path between the membrane cartridges is blocked by sludge adhering to the membrane surface. Pull up and clean the membrane cartridge, and eliminate the abnormality of the air diffuser.

If the activated sludge becomes abnormal due to bulking or the like, the driving pressure required to obtain the planned permeated water amount in one to several days after the start of the operation tends to increase, The amount of water shows a declining trend, and the driving pressure shows a rising trend again in one day to several days even after performing the chemical cleaning,
The amount of permeated water shows a decreasing tendency.

In this case, bulking is eliminated by feeding seed sludge, replacing sludge in the tank, feeding a seeding agent, and the like, thereby normalizing sludge properties. When the life of the membrane cartridge has expired, the operation is started for several weeks after the start of operation.
The driving pressure required to obtain the planned permeate volume in a month tends to increase, the permeate volume is difficult to recover to the initial set value even with chemical cleaning, the interval between chemical cleaning is reduced, and the total permeate volume is also reduced. descend.

In this case, the membrane cartridge is replaced. Therefore, during operation, the driving pressure and the amount of permeated water are continuously measured, and by referring to empirical rules using the fluctuation trends as indices, the current operating conditions of the submerged membrane separator and the properties of activated sludge can be accurately grasped and judged. The worst case in which the inflow raw water cannot be treated due to an abnormality in the immersion type membrane separation device can be avoided. In addition, the timing for replacing the membrane cartridge can be appropriately determined based on the determination result.

According to a second aspect of the present invention, in the maintenance method of the immersion type membrane separation apparatus, all the membrane cartridges mounted on the membrane module are replaced at a time when the membrane cartridge is replaced.

According to this configuration, the timing of replacing the membrane cartridge is appropriately determined, and then all the membrane cartridges are replaced at a time. This eliminates the need for complicated maintenance due to variations in the life of the membrane cartridges, and reduces the immersion type membrane. The separation device can be easily maintained.

According to a third aspect of the present invention, there is provided a method for maintaining a immersion type membrane separation apparatus, comprising the steps of: replacing a membrane cartridge when a service life of the membrane cartridge has exceeded an average life determined in advance as an empirical rule. All membrane cartridges installed in the membrane module were replaced with new membrane cartridges, and when the service life of the membrane cartridge was less than the average life determined in advance as an empirical rule, all membrane cartridges installed in the membrane module were collected in advance by replacement. The cartridge is replaced with a regenerated membrane cartridge obtained by regenerating a cartridge.

According to the above-described structure, it is possible to use the membrane cartridge up to the longest life by regenerating and using the membrane cartridge which has less than the average life.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2, a plurality of membrane separation devices 21 are immersed in an activated sludge tank 20. As shown in FIG. 2, each membrane separation device 21 includes a plurality of flat membrane cartridges 22 and an air diffuser 23 for ejecting a membrane cleaning gas from below the cartridges inside a case 24. Is composed. The case 24 is divided into a membrane case 26 and an air diffusion case 27, and a plurality of flat membrane cartridges 22 are individually and detachably mounted on the membrane case 26 to form a membrane module 28. The entire amount of the membrane surface cleaning gas that is jetted out is formed so as to enter the membrane case 26.

In the membrane cartridge 22, a filtration membrane 30 is disposed on both surfaces of a filter plate 29 made of ABS resin, and the filtration membrane 30 is fused to the filter plate by ultrasonic welding (welding) at a water-stop portion at a peripheral portion thereof. It was done. A permeate channel is formed between the filter plate 29 and the filtration membrane 30 and inside the filter plate 29, and a permeate outlet 31 communicating with the permeate channel is formed at the upper edge of the filter plate 29. I have.

Each of the membrane cartridges 22 has a permeate outlet 3
The treated water extraction system 33 that communicates with the water collecting pipe 32 via a tube 32 a connected to the water collecting pipe 32 is connected to the water collecting pipe 32. Further, a blower 34 is provided so as to be connected to each air diffuser 23. In the treated water extraction system 33,
A pressure gauge 35 as a pressure measuring means for measuring a driving pressure acting on the membrane surface of the membrane cartridge 22, a suction pump 36 for applying a driving pressure (negative pressure), and a measuring amount of treated water flowing through a treated water extracting system 33. A flow meter 37 as a means for measuring the amount of permeated water and a turbidity meter 38 are interposed.
5 and a monitoring unit 3 connected to a flow meter 37 and a turbidity meter 38
9 are provided.

In the present embodiment, the filtration operation of the membrane cartridge 22 is performed by using the suction pressure of the suction pump 36. However, the filtration can be performed by a gravity filtration method using the head pressure in the tank as the driving pressure. In this case, a water level gauge for measuring the water level in the tank is used as pressure measuring means for measuring the driving pressure acting on the membrane surface of the membrane cartridge 22.

The monitoring unit 39 continuously measures the driving pressure and the amount of permeated water, and sends the measured data to a central membrane monitoring center (not shown) through a public line. The central membrane monitoring center stores and stores correlation data between the driving pressure and the amount of permeated water previously obtained as an empirical rule, the operation state of the immersion type membrane separation device 21, and the properties of the activated sludge. The correlation data is as described below.

For example, three months to six months for continuous operation
During the entire operation period of one month, the operation state of the immersion type membrane separation device 21 is good, the damage of the membrane cartridge 22 and the clogging of the flow path between the membrane cartridges 22 do not occur, and the properties of the activated sludge are sound and the bulking etc. Does not occur, the permeated water amount maintains a stable value throughout the entire operation period, and the driving pressure required to obtain the planned permeated water amount shows a gradually increasing tendency at the end of the operation period.

In this case, the function of the immersion type membrane separation device 21 is restored by washing the membrane cartridge 22 with a chemical solution. In addition, when the cause of the mechanical abnormality is present, the driving pressure tends to increase within one to several days after the start of the operation, and the planned permeated water amount cannot be obtained even when the driving pressure is controlled to the upper limit.

In this case, sufficient sweeping does not act on the membrane surface of the membrane cartridge 22 due to the abnormality of the air diffuser 23,
Since the flow path between the membrane cartridges 22 is blocked by the sludge adhering to the membrane surface, the membrane cartridge 22 is pulled up and washed, and the abnormality of the air diffuser 23 is eliminated.

When the properties of the activated sludge become abnormal due to bulking or the like, the driving pressure required to obtain the planned permeated water amount in one to several days after the start of operation tends to increase, and The amount of water shows a declining trend, and the driving pressure shows a rising trend again in one day to several days even after performing the chemical cleaning,
The amount of permeated water shows a decreasing tendency.

In this case, bulking is eliminated by feeding seed sludge, replacing sludge in the tank, feeding a seeding agent, and the like, thereby normalizing sludge properties. When the membrane cartridge 22 has reached the end of its service life, the drive pressure required to obtain the planned permeate flow rate tends to increase within a few weeks to two months after the start of operation. It is difficult to recover to the set value, the interval at which chemical cleaning is performed is shortened, and the amount of permeated water as a whole is also reduced. In this case, the membrane cartridge 22 is replaced.

As shown in FIG. 3, the recovered membrane cartridge 41 recovered by the exchange is carried into a regenerated membrane factory 42, and is sorted into a waste membrane cartridge 44 and a regenerated one in a sorting step 43. Next, in a washing step 45, first, dirt such as sludge is removed by washing with water, and thereafter, a chemical solution is washed with a solution of sodium hypochlorite or oxalic acid. Then, in the repairing step 46, the welded portion of the recovered membrane cartridge 41 after cleaning is formed into a regenerated membrane cartridge 47 by applying a polyurethane bond or the like to reinforce the welded portion, and thereafter a hydrophilic agent is applied, dried and stored.

The operation of the above configuration will be described below. In normal operation, the air supplied from the blower 34 is blown out from the air diffuser 23, and the upward flow generated by the air lift action of the air becomes a gas-solid liquid mixed flow of air, activated sludge, and treated water. The mixture is circulated and the mixed solution in the tank is supplied to the flow path between the membrane cartridges 22 in a cross flow.

The bubbles of the aerated air ejected from the air diffuser 23 and the upward flow generated by the aerated air form a narrow flow path (5-10 m) between the adjacent membrane cartridges 22.
m width), the membrane surface of the membrane cartridge 22 is cleaned, and a decrease in the separation function is suppressed.
1 prevents dysfunction.

In this state, the mixed solution in the tank is filtered through each membrane cartridge 22 using the negative pressure given by the suction pump 36 as the driving pressure, and the filtrate is taken out of the tank through the treated water take-out system 33.

During operation, the driving pressure and the amount of permeated water are continuously measured by the pressure gauge 35 and the flow meter 37, respectively, and the measured data is stored in the monitoring unit 39 and transmitted to the central membrane monitoring center through a public line. The central membrane monitoring center obtains the fluctuation tendency of the driving pressure and the amount of permeated water on the basis of the data transmitted from the monitoring unit 39, and operates the immersion type membrane separation device 21 based on the empirical rule obtained in advance using the fluctuation tendency as an index. Then, the properties of the activated sludge are determined, and whether or not the membrane cartridge 22 needs to be replaced is determined based on the determination result.

Therefore, it is possible to accurately grasp and judge the current operating condition of the immersion type membrane separation device 21 and the properties of the activated sludge, and it is possible to treat the inflowing raw water when an abnormality occurs in the immersion type membrane separation device 21. The worst case that disappears can be avoided. In addition, the timing for replacing the membrane cartridge 22 can be appropriately determined based on the determination result.

The replacement of the membrane cartridge 22 is performed by replacing all the membrane cartridges 22 mounted on the membrane module 28 with a new membrane cartridge at a time when the number of years of use of the membrane cartridge 22 has exceeded the average life determined in advance as an empirical rule. If the membrane cartridge 22 is replaced and the service life of the membrane cartridge 22 is less than the average life determined in advance as an empirical rule, the membrane module 2
All the membrane cartridges 22 mounted on the cartridge 8 are replaced with the regenerated membrane cartridges 47.

As described above, the timing for replacing the membrane cartridge 22 is appropriately determined, and then all membrane cartridges 2 are replaced.
By exchanging the components 2 at a time, the complicated maintenance due to the variation in the life of the membrane cartridge 22 can be eliminated, and the immersion type membrane separator 21 can be easily maintained. By regenerating and using the membrane cartridge 22 that has less than the average life, the membrane cartridge 22 can be used up to the maximum life.

[0042]

As described above, according to the present invention, the operating conditions and activated sludge of the immersion type membrane separation device are determined based on empirical rules using the fluctuation tendency obtained by continuously measuring the driving pressure and the amount of permeated water during operation as an index. By judging the properties of the membrane cartridge and deciding whether or not to replace the membrane cartridge based on the judgment result, it is possible to accurately grasp and judge the current operating condition of the submerged membrane separation apparatus and the properties of the activated sludge. Can,
The worst case in which inflow raw water cannot be treated due to an abnormality in the immersion type membrane separation device can be avoided, and the membrane cartridge can be replaced at an appropriate time. By replacing all the membrane cartridges attached to the membrane module at once,
This eliminates the need for complicated maintenance due to variations in the life of the membrane cartridge, and allows easy maintenance of the immersion type membrane separation device. Select and replace a new membrane cartridge and a regenerated membrane cartridge based on whether or not the average life has expired, and use the membrane cartridge up to the longest life by regenerating and using a membrane cartridge that has less than the average life. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a flow sheet diagram showing a membrane separation activated sludge method in an embodiment of the present invention.

FIG. 2 is a perspective view showing an immersion type membrane separation device in the embodiment.

FIG. 3 is a schematic diagram showing a procedure for regenerating a membrane cartridge according to the embodiment.

FIG. 4 is a flow sheet diagram showing a conventional activated sludge method.

[Explanation of symbols]

 Reference Signs List 20 activated sludge tank 21 immersion type membrane separator 22 flat membrane cartridge 23 diffuser 24 case 25 membrane unit 26 membrane case 27 diffuser case 28 membrane module 29 filter plate 30 filtration membrane 31 permeate outlet 32 tube 33 treated water Removal system 34 Blower 35 Pressure gauge 36 Suction pump 37 Flow meter 38 Turbidity meter 39 Monitoring unit

Continued on the front page (72) Inventor Masaharu Nishi 2-47, Shikitsu Higashi 1-chome, Namiwa-ku, Osaka-shi, Osaka (72) Inventor Tatsuya Uejima 2-1-2 Shikitsu-Higashi, Naniwa-ku, Osaka, Osaka No. 47 F-term in Kubota Corporation (reference) 4D006 GA02 HA53 HA91 HA93 JA52A JB07 JB11 KA01 KA12 KA44 KB21 KE04P KE04Q KE07P KE07Q LA10 MA03 PB08 PC62 4D028 BC03 BC17 BD17

Claims (3)

[Claims] 1. A membrane module is formed by arranging a plurality of flat membrane cartridges arranged in a vertical direction in parallel with an appropriate gap in a case to form a membrane module, and immersing the membrane module in an activated sludge tank. In the immersion type membrane separation device in which an aeration device is arranged below and the treated water removal system is provided in communication with the permeate flow path of each membrane cartridge, the pressure for measuring the driving pressure acting on the membrane surface of the membrane cartridge is measured. Measuring means and permeated water amount measuring means for measuring the amount of treated water flowing through the treated water extraction system are provided, and empirical rules are provided in advance to determine the correlation between the driving pressure and the amount of permeated water and the operating conditions of the submerged membrane separation device and the properties of activated sludge. Determined the operating conditions of the immersion type membrane separation device and the properties of the activated sludge in light of the above empirical rules using the fluctuation tendency obtained by continuously measuring the driving pressure and the permeated water amount during operation as an index, Maintenance method of immersion type membrane separation apparatus characterized by determining the necessity of replacement of film cartridge on the basis of the cross-sectional results. 2. The method according to claim 1, wherein all the membrane cartridges mounted on the membrane module are replaced at a time when the membrane cartridge is replaced. 3. When exchanging a membrane cartridge, if the number of years of use of the membrane cartridge has exceeded the average life determined in advance as an empirical rule, all membrane cartridges mounted on the membrane module are replaced with new membrane cartridges. When the number of years of use is less than the average life determined in advance as an empirical rule, all membrane cartridges mounted on the membrane module are replaced with regenerated membrane cartridges obtained by regenerating membrane cartridges recovered by replacement in advance. A method for maintaining the immersion type membrane separation device according to claim 1.