JP2015231592A - Method for operating gas diffuser - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for operating a gas diffuser which can prevent the clogging of gas diffusion holes and can easily remove deposits in branch piping even under the condition of a high MLSS concentration and a high viscosity.SOLUTION: There is provided a method for operating a gas diffuser (A) arranged in a treatment tank in which water to be treated is stored, and a membrane module unit is arranged. The method for operating the gas diffuser (A) includes: a gas diffusion step of repeating a gas diffusion step of continuously supplying gas to branch piping for a prescribed time through the main piping of the gas diffuser (A) and a stop step of stopping the supply of the gas for a fixed time; and a water to be treated inflow step of causing a liquid to be treated to flow into the branch piping during the stop step. The inflow frequency of the liquid to be treated is once per 0.5 h or more and 24 h or less.

Description

  The present invention relates to a method for operating an air diffuser disposed below a membrane module unit.

  In recent years, various methods for solid-liquid separation of activated sludge using a membrane module unit provided with a separation membrane such as a microfiltration membrane or an ultrafiltration membrane have been studied. For example, when an activated sludge treatment device is formed as a water treatment device equipped with a membrane module unit, and the treated water containing activated sludge is filtered by the separation membrane using the activated sludge treatment device, a treatment with high water quality is performed. You can get water.

However, when solid-liquid separation of water to be treated is performed using the separation membrane, the clogging of the separation membrane surface due to suspended solids (solid content) proceeds as the filtration treatment continues, resulting in a decrease in filtration flow rate, Increase in differential pressure occurs.
Therefore, conventionally, in order to prevent clogging of the separation membrane surface, an air diffuser is disposed below the membrane module unit, and air is diffused from the air diffuser holes of the air diffuser to generate bubbles. Cleaning is performed by applying a gas-liquid mixed flow of bubbles to be formed and a liquid to be processed to the membrane module unit. That is, suspended substances such as sludge adhering to the surface of the membrane module are peeled off by the gas-liquid mixed flow and removed from the membrane module.

However, if such cleaning operation is continued for a long period of time, there are problems such as clogging of the air diffuser and accumulation of sludge in the air diffuser, which causes bubbles (gas-liquid mixed flow) to the membrane module. It becomes difficult to apply evenly. As a result, an insufficiently washed portion remains on the surface of the membrane module, and it becomes difficult to stably perform the solid-liquid separation process (filtration process).
In addition, when the air diffuser is clogged or when sludge is accumulated in the air diffuser, it is possible to prevent the solid-liquid separation process from becoming unstable by cleaning the air diffuser. Since a relatively long time is required for the cleaning operation of the air diffusing tube, such a cleaning operation becomes a heavy burden.

  Also, if air is clogged or if sludge accumulates in the air diffuser, if air is fed into the air diffuser with a high air flow, the power consumption of the air supply device such as a blower will increase and the cost will increase. End up. On the other hand, when air is sent at a low air volume, bubbles are not generated from the diffuser holes, and bubbles (gas-liquid mixed flow) do not hit the membrane module, resulting in insufficient cleaning of the membrane module surface. .

  Against this background, the techniques of Patent Documents 1 and 2 have been proposed for countermeasures against clogging of air diffusers, sludge accumulation in the air diffuser, and cleaning of the air diffuser. In the techniques of Patent Documents 1 and 2, the aeration is stopped and the target water is caused to flow back into the aeration pipe from the sludge entrance / exit hole formed at the front end opening of the aeration pipe. The foreign matter is removed from the sludge entry / exit holes by moistening the foreign matter and restarting the air diffuser.

JP 2011-92835 A International Publication No. WO2012137276A1

  However, in the techniques of Patent Documents 1 and 2, an effect is confirmed to some extent against clogging of the air diffuser and sludge accumulation in the air diffuser, but under high activated sludge concentration (MLSS) and high viscosity conditions, After operation for a certain period, the air diffuser and the branch pipe are clogged and blocked.

  This invention is made | formed in view of the said situation, and it aims at providing the operating method of the diffuser which solved the said subject.

The present invention has the following aspects.
[1] An operation method of the following air diffuser (A) disposed in a treatment tank in which treated water is stored and a membrane module unit is disposed,
An air diffusion process for repeatedly supplying a gas to the branch pipe for a predetermined time through the main pipe of the air diffuser (A), and an air diffusion process for repeatedly stopping the gas supply for a predetermined time; and , Having a process water inflow process for allowing the process liquid to flow into the branch pipe during the stop process,
The operation method of the diffuser, wherein the inflow frequency of the liquid to be treated is once in a range of 0.5 hours to 24 hours.
(Air diffuser (A))
A diffuser configured to include a cylindrical main pipe that receives a gas supply from a gas supply apparatus, and a branch pipe connected to the main pipe,
The branch pipe has one end connected to the main pipe, the other end opened and provided with one or a plurality of air diffusion holes on the side surface, and the main pipe arranged horizontally. The branch pipe is an air diffuser configured such that at least some of the air diffuse holes are directed upward in the vertical direction and the opening at the other end is directed downward in the vertical direction.
[2] The operation method according to [1], wherein the operation is performed at a concentration of the water to be treated of 2,000 mg / L to 20,000 mg / L and a viscosity of 120 mPa · sec or less.
[3] In a state where the main pipe is arranged horizontally, the branch pipe is formed so that the portion where the air diffusion hole is formed is horizontal, and a bent portion is provided in the vicinity of the other end of the branch pipe. The operation method according to [1] or [2], wherein the opening at the other end faces downward in the vertical direction with the main pipe arranged horizontally.
[4] The operation method according to any one of [1] to [3], wherein the length Δh of the tip opening in the vertical direction is 2 to 5 times the branch pipe diameter D.
[5] The operation method according to any one of [1] to [4], wherein the front end opening is installed outside the end air diffuser.
[6] The operation method according to any one of [1] to [5], wherein the air diffuser (A) is disposed below the membrane module unit.

According to the operation method of the air diffuser (A) of the present invention, in the state where the main pipe is arranged horizontally, the branch pipe has at least a part of the air diffuser facing upward in the vertical direction, and Since the opening at the other end is configured to face downward in the vertical direction, when flowing the water to be treated into the branch pipe or the main pipe, by simply stopping the gas supply and stopping the aeration, The treated water can be allowed to flow into the branch pipe or the main pipe.
In addition, since the supply of gas is stopped for a certain period of time by setting the inflow frequency of the liquid to be processed, the water to be processed can flow into the branch pipe or the main pipe while the gas supply is stopped. Thus, clogging of the air holes and sludge accumulation in the branch pipes can be prevented even under highly activated sludge properties and high viscosity conditions.

It is a top view of one embodiment of an air diffuser (A) concerning the present invention. It is a side view of the air diffusion apparatus (A) shown in FIG. It is a front view of the air diffusion apparatus (A) shown in FIG. It is a perspective view which shows branch piping. It is a side view of a membrane module unit. It is a front view of a membrane module unit. It is a figure which shows typically the schematic structure of one Embodiment of the water treatment apparatus which concerns on this invention. It is a top view of one Embodiment of the conventional diffuser.

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the following drawings, the scale of each member is appropriately changed to make each member a recognizable size.

<Air diffuser (A)>
FIG. 1 is a plan view showing an embodiment of an air diffuser (A) according to the present invention (hereinafter also simply referred to as “air diffuser”), and FIG. 2 is a side view of the air diffuser shown in FIG. FIG. 3 is a front view of the air diffuser shown in FIG.

In these drawings, reference numeral 1 denotes an air diffuser. The air diffuser 1 includes a cylindrical main pipe 2 that receives a gas supply from an air supply device (not shown) and a plurality of branches connected to the main pipe 2. A pipe 3 is provided.
As shown in FIG. 2, the main pipe 2 is made of metal, for example, made of SUS304, to which one end side of the main pipe 2 is connected via an elbow pipe 4, and another flange pipe is connected to the flange pipe 5 as described later. By being connected, an air supply device (gas supply device) is connected.

  Moreover, the other end side of the main pipe 2 is airtightly closed by opening the lid 2a without opening. Such a main pipe 2 has one side of the elbow pipe 4 (the side opposite to the side connected to the main pipe 2) when the central axis thereof is arranged in the horizontal direction, that is, in a horizontally arranged state. The flange pipe 5 connected to the upper side in the vertical direction is connected to the upper side in the vertical direction.

  In addition, the main pipe 2 is provided with a vertical pipe portion 6 extending downward from a lower portion thereof in communication with the main pipe 2 in a state in which the main pipe 2 is arranged horizontally. In the present embodiment, a screw portion is formed on the outer periphery (or inner periphery) of the vertical tube portion 6, and the fixing member 7 is detachably connected to the lower end side of the vertical tube portion 6 using this screw portion. Yes. The fixing member 7 is a three-way tube (T-shaped three-way tube) formed in a T shape as shown in FIG. 3, and the central tube portion 7a is connected to the vertical tube portion 6 by a fixing mechanism by union connection or screw connection. doing. That is, the fixing member 7 is attached to and detached from the vertical pipe portion 6 by union-connecting or screwing the screw portion formed in the central pipe portion 7a of the fixing member 7 to the screw portion of the vertical pipe portion 6. Connected as possible.

  For the connection of the fixing member 7, for example, fitting and fixing can be employed in addition to the union connection or screw connection. However, as will be described later, in order to ensure that the branch pipe 3 connected to the fixing member 7 is prevented from dropping off, it is preferable to connect the fixing member 7 to the vertical pipe portion 6 by union connection or screw connection.

  The fixing member 7 extends in a direction perpendicular to the central axis of the main pipe 2, with the pipe parts (communication members) 7 b on both sides being horizontally disposed with the central pipe part 7 a connected to the vertical pipe part 6. It is formed and arranged like this. Here, in this embodiment, a plurality of vertical pipe sections 6 (for example, about 5 to 10) are provided at equal intervals along the length direction of the main pipe 2, and accordingly, corresponding to the plurality of vertical pipe sections 6. The same number of fixing members 7 as the vertical pipe portions 6 are provided. That is, the fixing member 7 is connected to each vertical pipe portion 6.

  Then, one end side of the branch pipe 3 is connected to the pipe portions 7 b on both sides of the fixing member 7. The branch pipe 3 is made of a metal that functions as an air diffuser, for example, made of SUS304, and has one or more air diffuser holes 8 formed on the side surface thereof. The number of the air diffusion holes 8 is appropriately set based on the length of the branch pipe 3 and the like, but is preferably 2 to 10. In this embodiment, as shown in FIG. 4, five pieces are formed at intervals (equal intervals) of about 50 mm to 120 mm. Further, as shown in FIGS. 1 and 3, these air diffusion holes 8 are all formed so as to face upward in the vertical direction in a state where the main pipe 2 is horizontally disposed. Although all the diffuser holes 8 are preferably upward in the vertical direction, the other diffuser holes may be downward as long as some of them are directed upward in the vertical direction.

That is, the branch pipe 3 is formed so that the portion where the side air diffuser holes 8 are formed is horizontal in a state where the main pipe 2 is horizontally arranged.
Further, the branch pipe 3 is formed so that the bent part 3a is formed in the vicinity of the other end, so that the opening 3b at the other end faces downward in the vertical direction in a state where the main pipe 2 is horizontally arranged. . The bent portion 3a may be bent by bending the other end portion of the branch pipe 3, or may be formed by assembling a part such as an elbow. However, the diameter of the opening 3b is preferably formed to be the same as the diameter of the branch pipe 3.

  Further, the pipe portion formed by the bent portion 3a and facing downward in the vertical direction is not particularly limited. For example, when the flow rate of air supplied to the branch pipe 3 is large, the length thereof is relatively long. It is preferable to form it to about 50 mm-300 mm. This is because when the air flow rate is increased, a relatively large amount of air is ejected from the opening 3b at the other end, which may affect the uniformity of air ejection from the air diffuser holes 8. . Therefore, as described above, by forming a long pipe portion facing downward in the vertical direction of the branch pipe 3, it is possible to prevent the air ejection uniformity from the air diffuser holes 8 from being affected.

  Under such a configuration, all the branch pipes 3 are arranged in parallel with the other branch pipes 3. Further, since the pipes 7b on both sides of the fixing member 7 are respectively connected along the length direction thereof, the branch pipes 3 are arranged symmetrically about the main pipe 2. .

Such a branch pipe 3 has a length in plan view, that is, a length in plan view from one end to the other end, which is 500 mm or less, preferably 400 mm or less. If the length of the branch pipe 3 is short, it is suitable for uniform aeration, but it is preferable to select 200 mm or more, more preferably 250 mm or more according to the size of the water treatment apparatus.
The inner diameter D of the branch pipe 3 is preferably 10 mm or more and 20 mm or less, although it varies depending on the dimension (size) of the diffuser. Similarly, the diameter d of the air diffusion holes 8 is preferably 4.5 mm or more and 7.0 mm or less.
The reason why the diameter d of the air diffuser 8 is preferably 4.5 mm or greater and 7.0 mm or less is that if the air diffuser 8 is less than 4.5 mm, the air diffuser 8 is likely to be blocked. This is because the flow velocity of the air passing therethrough becomes low and there is a possibility that a sufficient aeration effect cannot be obtained.

  In addition, to the air diffuser 1 having such a configuration, for example, a flange pipe 5 is connected to a decompression unit including a suction pump or the like separately from the air supply device (gas supply device). As a result, as will be described later, when the aeration operation for supplying air by the air supply device is stopped, the liquid to be processed can flow into the main pipe 2 and the branch pipe 3.

  The air diffuser 1 having such a configuration is used by being disposed below the membrane module unit 10 as shown in FIGS. 5 and 6. The membrane module unit 10 includes a plurality of membrane modules 11, and the membrane module 11 includes a membrane element (not shown) such as a hollow fiber membrane.

  In the example shown in FIGS. 5 and 6, the air diffuser 1 shown in FIGS. 1 to 3 is arranged adjacent to each other as shown in FIG. 6. An air supply pipe 21 is connected via a connecting pipe (flange pipe) 20. An air supply device (not shown) such as a blower is connected to the air supply pipe 21 as will be described later. In addition to the air supply device, a pressure reducing means (not shown) including a suction pump is connected to the air supply pipe 21. The communication between the air supply device and the pressure reducing means is switched between the air supply pipe 21 by a switching valve (not shown) or the like. Accordingly, the switching valve can be used to switch between the aeration operation in which air is supplied by the air supply device and the decompression operation in which the decompression process is performed by the decompression means.

  Such a membrane module unit 10 and the diffuser 1 are arranged and used in a water treatment device 30 as shown in FIG. The water treatment device 30 is an embodiment of the water treatment device according to the present invention, and includes a water tank (treatment tank) 32 into which treated water 31 such as activated sludge is charged, and the water tank 32 disposed in the water tank 32. The submerged membrane separation device includes a membrane module unit 10, the air diffuser 1 disposed below the membrane module unit 10, an air supply device 40, a decompression means 43, and a switching valve 46. . In addition, in the water treatment apparatus 30 of this embodiment, it has three membrane module units 10, Therefore, the diffuser 1 is also arrange | positioned under each corresponding to each membrane module unit 10. FIG. However, the numbers of the membrane module units 10 and the air diffuser 1 are not particularly limited and can be arbitrarily set.

Although the water tank 32 has a rectangular parallelepiped shape and the size is not particularly limited, it is preferable that the depth sufficiently exceeds 1 m so that the depth of the water to be treated 31 is 1 m or more.
The air supply device 40 includes a blower 41 and a connection pipe 42 that connects the blower 41 and the air supply pipe 21. The decompression means 43 includes a suction pump 44 and a connection pipe 45 that connects the suction pump 44 and the air supply pipe 21.

  A switching valve 46 composed of a three-way valve is provided between the connection pipe 42, the connection pipe 45, and the air supply pipe 21. Under such a configuration, the blower 41 (air supply device 40) and the air supply pipe 21 are communicated with each other by switching the switching valve 46, or the suction pump 44 (decompression means 43) and the air supply pipe 21 are connected. It can be communicated. That is, as described above, the aeration operation and the decompression operation can be switched by the switching valve 46.

Further, a suction pump (not shown) is connected to the membrane module unit 10 (membrane module 11) via a suction pipe 47 so that suction filtration by the membrane module unit 10 is possible.
In FIG. 7, for convenience, the main pipe 2 and the branch pipe 3 of the air diffuser 1 and the connecting pipe 20 are omitted, but the air diffuser indicated by reference numeral 1 in FIG. 5. As shown in FIG. 6, it is assumed that the air diffuser 1 has two units, that is, two air diffusers 1 shown in FIGS.

<Operation method of air diffuser (A)>
Next, one embodiment of the air diffusion method according to the present invention will be described based on the treatment operation of the water treatment apparatus 30.
First, as shown in FIG. 7, the membrane module unit 10, the diffuser 1, and the like are disposed in the water tank 32, and the water to be treated 31 is stored so as to have a predetermined water level (water depth). And the suction filtration by the membrane module unit 10 is performed by operating the suction pump by the side of the membrane module unit 10 in this state.

  In parallel with such suction filtration, air is continuously (continuously) supplied from the air supply device 40 (blower 41) toward the diffuser device 1 for a predetermined time. Although the air supply amount varies depending on the dimensions of the air diffuser 1, for example, it is set to 75 L / min for each branch pipe 3. By supplying air in this way, most of the air supplied to the diffuser 1 via the air supply pipe 21 is ejected from the diffuser holes 8 of the branch pipe 45 through the main pipe 2. That is, since the water pressure in the air diffuser 8 is lower than that of the opening 3 b at the other end of the branch pipe 3, most of the air supplied to the air diffuser 1 is diffused unless air is supplied at a particularly high air volume. It ejects from the pores 8.

  When air is ejected from the air diffusion holes 8 in this way, the ejected air becomes bubbles and rises in the water tank 32, that is, in the liquid to be treated 31. The rising bubbles form a gas-liquid mixed flow with the liquid 31 to be processed. This gas-liquid mixed flow hits the membrane module unit 10 (membrane module 11) to wash each membrane element (not shown). That is, the gas-liquid mixed flow peels off suspended substances such as sludge adhering to the surface of the membrane element (membrane module unit 10) and removes them from the membrane module unit 10.

  When such a diffuser operation is performed for a predetermined time, the blower 41 is stopped for a certain time, and the supply of air to the diffuser 1 is stopped. Then, the air remaining in the main pipe 2 and the branch pipe 3 passes through the air diffusion holes 8 and is discharged into the water to be treated 31 to clean the membrane module unit 10. In addition, the water to be treated 31 flows from the opening 3 b at the other end of the branch pipe 3 by replacing this air. The treated water 31 flowing in this way wets, for example, dried and accumulated foreign matter (sludge) clogging the diffuser holes 8 and sludge accumulated in the diffuser pipe 3. Therefore, when the blower 41 is actuated and the aeration is resumed after the lapse of a certain time, these foreign matters and sludge can be easily discharged from the aeration holes 8. That is, the inside of the main pipe 2, the branch pipe 3, and the air diffusion holes 8 can be cleaned.

  In this embodiment, since the pressure reducing means 43 is connected to the diffuser 1, the suction pump 44 (pressure reducing means 43) is switched by switching the switching valve 46 while the blower 41 is stopped for a certain time. Can be communicated with the diffuser 1, and the inside of the main pipe 2 and the branch pipe 3 can be decompressed by the suction pump 44. By performing the depressurization process in this way, the treated water 31 can flow more into the branch pipe 3 and the main pipe 2 at a higher speed, and thus the cleaning effect can be enhanced.

  In the air diffuser 1 of the present embodiment, the main pipe 2 is horizontally arranged, the branch pipe 3 has all the air diffuser holes 8 directed upward in the vertical direction, and the opening 3b at the other end is in the vertical direction. Since it is configured to face downward, when the treated water 31 flows into the branch pipe 3 or the main pipe 2, the supply of air is stopped by simply stopping the air supply, The treated water can flow into the main pipe 2. Therefore, a valve or the like for opening to the atmosphere is not necessary, and clogging of the air diffusion holes 8 and sludge accumulation in the branch pipes 3 can be prevented without increasing the cost or complicating the apparatus configuration.

Further, even when air is supplied, the water pressure is high on the opening 3b side of the other end of the branch pipe 3, so that most of the air is ejected from the diffuser hole 8 and air is ejected from the other end opening 3b. It is difficult to do. Therefore, the membrane module 11 can be effectively cleaned, and the installation space can be reduced by suppressing the enlargement of the apparatus.
Further, since the branch pipes 3 are arranged symmetrically about the main pipe 2, the distance from the main pipe 2 to the tip of the branch pipe 3 can be shortened, and sludge in the branch pipe 3 is discharged. It can be made easier.

Further, since the branch pipe 3 is detachably connected to the main pipe 2 via the fixing member 7, the branch pipe 3 can be easily aligned and the branch pipe 3 can be easily replaced and maintained. Become.
Further, a fixing member 7 made of a T-shaped three-way pipe is attached to the vertical pipe portion 6 extending downward from the lower portion of the main piping 2 by a fixing mechanism by union or screwing, and the branch piping 3 is attached to one fixing member 7. Since the two pipes are connected to each other, the branch pipes 3 are horizontal below the main pipe 2, so that air can be ejected from each branch pipe 3 evenly. In addition, foreign matter is less likely to accumulate in the main pipe 2, and the foreign matter is uniformly discharged together with air from each branch pipe 3. Further, it is possible to prevent the branch pipe 3 from falling off due to an impact from the outside, and the branch pipes 3 can be evenly arranged on the left and right.

Further, if the number of air diffusion holes 8 provided in each branch pipe 3 is 2 to 10 per branch pipe, the amount of sludge adhering to each branch pipe 3 can be reduced by the dispersion effect. Even if the air diffuser holes 8 are blocked, the remaining air diffuser holes 8 can diffuse air.
Further, if the inner diameter D of the branch pipe 3 is 10 mm or more and 20 mm or less and the diameter d of the air diffuser hole 8 is 4.5 mm or greater and 7.0 mm or less, the branch pipe 3 and the air diffuser hole 8 are completely formed even if sludge adheres. In addition, the fluid passing through the branch pipes 3 and the air diffusion holes 8 can be given an appropriate flow rate. Therefore, the cleaning performance at the time of cleaning each branch pipe 3 and the air diffuser 8 can be improved, and the cleaning effect of the branch pipe 3 and the air diffuser 8 can be further improved.

  Further, in the air diffusion method of the present embodiment, the air diffuser 1 is arranged in the water tank (treatment tank) 32 and air is continuously supplied to the branch pipe 3 through the main pipe 2 for a predetermined time. Then, the membrane module unit 10 is washed, and then the supply of air is stopped for a certain period of time, so that the water to be treated 31 flows into the branch pipe 3 or the main pipe 2 while the supply of air is stopped. Thus, clogging of the air diffusion holes 8 and sludge accumulation in the branch pipe 3 can be prevented.

  The inflow frequency of the liquid to be treated is preferably 0.5 to 24 hours from the viewpoint of prevention of clogging of the air holes, prevention of sludge blockage in the branch pipes, air diffusion efficiency and energy efficiency, More preferably, it is once every 3 hours to 20 hours, and more preferably once every 6 hours to 12 hours.

  As mentioned above, although preferred embodiment of this invention was described referring drawings, this invention is not limited to the said embodiment. Various shapes, combinations, and the like of the constituent members shown in the above-described embodiments are merely examples, and various modifications can be made based on design requirements and the like without departing from the gist of the present invention.

  For example, in the above embodiment, the air supply device is connected to one end side of the main pipe 2 via the elbow pipe 4 and the flange pipe 5 and the other end side is closed by the lid 2a. Depending on the (size), that is, when the capacity of the air diffuser 1 is large, the both ends of the main pipe 2 are opened and air supply devices are connected to the two so that air is supplied from both sides of the main pipe 2. It may be.

The main pipe 2 and the branch pipe 3 may be made of a synthetic resin such as vinyl chloride resin instead of metal.
In the embodiment, air is supplied from the air supply device to the air diffuser, and the air is ejected from the air diffuser. However, if necessary, a gas other than air, such as nitrogen, may be used as the gas. You may make it supply to a diffuser from a supply apparatus.

EXAMPLES Hereinafter, although an Example demonstrates this invention more concretely, this invention is not limited to these.
(Examples 1-4)
As the air diffuser, the air diffuser shown in FIGS. 1 to 3 (manufactured by SUS304) was used. Here, the diameter (d) of the air diffusion hole 8 was set to 5.5 mm. And about the air supply amount from the air supply apparatus 40, it was made for the air ejection amount of the branch piping 3 to be 50 L / min per one. Table 1 shows the inflow frequency of the liquid to be treated into the diffuser.
The air diffuser was submerged in a water tank having an activated sludge concentration (MLSS) of 18,000 mg / L and a viscosity of 100 mPa · s, and an air diffuser was confirmed to be defective due to blockage of the air diffuser holes 8 of the air diffuser.
After the operation for 60 days, the air diffuser 1 was confirmed. As a result, the branch pipe 3 and the air diffuser 8 were not blocked, and there was no poor air diffuser.

(Comparative Example 1)
As the air diffuser, the air diffuser 2 (manufactured by SUS304) shown in FIG. 8 was used.
The diameter (d) of the air diffuser hole 47 was set to 5 mm, and the air supply amount from the air supply device was set so that the air ejection amount of the branch pipe 48 was 70 L / min. The inflow frequency of the liquid to be treated into the diffuser is shown in Table 1.
The air diffuser 2 is submerged in a water tank having an activated sludge concentration (MLSS) of 12,000 mg / L and a viscosity of 40 mPa · s. After confirming the cleaning performance, after confirming the air diffuser 2 after 20 days of operation, blockage of the branch pipes 48 and the air diffuser holes 47 was observed, resulting in poor air diffusion.

(Comparative Examples 2 and 3)
As the air diffuser, the air diffuser shown in FIGS. 1 to 3 (manufactured by SUS304) was used. Here, the diameter (d) of the air diffusion hole 8 was set to 5.5 mm. And about the air supply amount from the air supply apparatus 40, it was made for the air ejection amount of the branch piping 3 to be 50 L / min per one. Table 1 shows the inflow frequency of the liquid to be treated into the diffuser.
The air diffuser was submerged in a water tank having an activated sludge concentration (MLSS) of 18,000 mg / L and a viscosity of 100 mPa · s, and an air diffuser was confirmed to be defective due to blockage of the air diffuser holes 8 of the air diffuser.
After the operation for 60 days, the air diffuser 1 was confirmed. As a result, the branch pipe 3 and the air diffuser 8 were not blocked, and there was no poor air diffuser.
However, since the time for stopping the supply of air becomes longer, the operation efficiency deteriorates as a result.

(Reference Example 1)
The diffuser used in the comparative example was submerged in a water tank having an activated sludge concentration (MLSS) of 8,000 mg / L and a viscosity of 20 mPa · s, and the diffuser was poor due to blockage of the diffuser holes 47 of the diffuser, The membrane surface was cleaned.
When the diffuser 2 was confirmed after 60 days of operation, the branch pipe 48 and the diffuser hole 47 were not blocked, and there was no poor diffuser.

(Aeration efficiency)
○: No blockage of air diffuser and no accumulation of sludge on branch pipe ×: Poor air diffusion due to obstruction of air diffuser and accumulation of sludge on branch pipe (operation efficiency)
◎: The operation efficiency of the equipment is very good (the sludge inflow frequency is low and the operation stop time is short)
○: Equipment operating efficiency is good ×: Equipment operating efficiency is poor

  From Table 1, by using the air diffuser shown in FIGS. 1 to 3, the air diffuser efficiency is improved, and when the sludge inflow frequency is increased, the stop time of the device is also increased, and the operation efficiency is deteriorated.

DESCRIPTION OF SYMBOLS 1 Air diffuser 2 Main piping 2a Cover 3 Branch piping 3a Bending part 3b Opening 6 Vertical part pipe 7 Fixing member 7b Pipe part (Communication member)
8 Aeration hole 10 Membrane module unit 11 Membrane module 21 Air supply pipe 30 Water treatment device 31 Water to be treated 32 Water tank 40 Air supply device 41 Blower 43 Decompression means 44 Suction pump 46 Switching valve 51 Sludge entry / exit hole 52 Header pipe 53 Aeration part (Air diffuser)

Claims (6)

The operation method of the following air diffuser (A) disposed in the treatment tank in which the treated water is stored and the membrane module unit is disposed,
An air diffusion process for repeatedly supplying a gas to the branch pipe for a predetermined time through the main pipe of the air diffuser (A), and an air diffusion process for repeatedly stopping the gas supply for a predetermined time; and , Having a process water inflow process for allowing the process liquid to flow into the branch pipe during the stop process,
The operation method of the diffuser, wherein the inflow frequency of the liquid to be treated is once in a range of 0.5 hours to 24 hours.
(Air diffuser (A))
A diffuser configured to include a cylindrical main pipe that receives a gas supply from a gas supply apparatus, and a branch pipe connected to the main pipe,
The branch pipe has one end connected to the main pipe, the other end opened and provided with one or a plurality of air diffusion holes on the side surface, and the main pipe arranged horizontally. The branch pipe has a diffuser configured such that at least some of the diffuser holes are directed upward in the vertical direction, and the opening of the other end is directed downward in the vertical direction.   The operation method according to claim 1, wherein the operation is performed at a concentration of 2,000 mg / L to 20,000 mg / L and a viscosity of 120 mPa · sec or less.   In a state where the main pipe is arranged horizontally, the portion where the air diffusion hole of the branch pipe is formed is formed to be horizontal, and a bent portion is provided in the vicinity of the other end of the branch pipe. The operation method according to claim 1 or 2, wherein the main pipe is horizontally arranged and the opening at the other end is directed downward in the vertical direction.   The operating method according to any one of claims 1 to 3, wherein a length Δh of the tip opening in the vertical direction is 2 to 5 times the branch pipe diameter D.   The driving | running method as described in any one of Claims 1-4 which a front-end | tip opening part installs outside the diffuser hole of a terminal.   The operation method according to any one of claims 1 to 5, wherein the air diffuser (A) is disposed below the membrane module unit.