WO2012165121A1

WO2012165121A1 - Air diffuser

Info

Publication number: WO2012165121A1
Application number: PCT/JP2012/062145
Authority: WO
Inventors: 彰利中川; 寛野口; 泰日李
Original assignee: 株式会社明電舎
Priority date: 2011-06-02
Filing date: 2012-05-11
Publication date: 2012-12-06
Also published as: JP2012250169A; JP5803293B2

Abstract

An air diffuser (1) cleans a membrane module (2) and is formed from an air diffusing tube (10) disposed in the lower part of the membrane module (2). The air diffusing tube (10) has opening parts (11) formed in the lower surface thereof along the axial (L1) direction and has a plurality of air diffusion holes (12) formed so as to be disposed along the direction of the axis (L1) in a position higher than the opening parts (11) and lower than the axis (L1) and so as to be on either side of the opening parts (11). A plurality of opening parts (11) is formed and is disposed along the direction of the axis (L1).

Description

Air diffuser

The present invention relates to an air diffuser provided in a reaction tank using an immersion type membrane module.

As a sewage treatment apparatus using a submerged membrane module, for example, there is a type in which a plurality of external pressure type solid-liquid separation flat membranes are vertically arranged in a reaction tank. In the sewage treatment apparatus of this membrane separation activated sludge treatment (hereinafter referred to as MBR) system, air bubbles are aerated from an air diffuser installed at the lower part of the reaction tank. This is to supply oxygen to the microorganisms that make up the activated sludge in the reaction tank, and the membrane surface is washed by the water flow generated as the bubbles rise to remove clogging on the membrane surface. It is for suppressing.

Since the MBR sewage treatment apparatus can prevent the turbid components from flowing out, it can be operated with a higher activated sludge concentration than in the case of solid-liquid separation in the final sedimentation basin. As a result, the apparatus can be miniaturized and the generated sludge can be reduced.

Since the MBR method has a high activated sludge concentration and a bubble cleaning effect cannot be obtained unless the air bubbles are larger than a certain size, the diameter of the air diffuser of the air diffuser must be relatively large, 3-10 mm. is there. In general, an air diffuser having a structure in which a plurality of holes of this size are formed in a pipe is used (for example, Patent Document 1). Membrane surface cleaning uses a vigorous gas-liquid mixed flow created by rising aerated bubbles, and the gas-liquid mixed flow sweeps the membrane surface to remove film surface contamination and suppress the accumulation of contamination. To do.

In the sewerage field, the membrane to be used is selected according to the substance to be removed and the target treated water quality. MF membranes and UF membranes are used mainly for the purpose of removing solids, and membranes used in MBR are also usually MF membranes. The material of the film can be roughly classified into an organic film and an inorganic film.

As organic membranes, MF and UF membranes are PSF (polysulfone), PE (polyethylene), CA (cellulose acetate), PAN (polyacrylonitrile), PP (polypropylene), PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene). Fluoroethylene) is used. For the NF film and the RO film, a polyamide-based organic film is often used. As the inorganic film, a film using an ceramic (MF film, UF film, NF film) has been developed.

Also, the shape of the membrane can be classified into a hollow fiber membrane, a flat membrane, a tubular membrane, and a monolith. Furthermore, filtration methods in membrane treatment include total volume filtration (dead-end-filtration) and cross-flow filtration.

全 In the total filtration method, what is blocked by the membrane adheres to the membrane and deposits accumulate along with filtration, so filtration must be stopped at regular intervals and the accumulated deposit layer must be removed. On the other hand, the cross-flow filtration method always performs filtration while washing the membrane surface with a flow parallel to the membrane surface. This method allows continuous operation in which deposits are removed in parallel with filtration and maintains a high filtration rate. However, in order to create a sufficient parallel flow, the flow rate on the supply water side becomes larger than the filtration flow rate, and filtration is performed. Energy consumption per flow rate increases.

The MBR method is a wastewater treatment method that combines membrane filtration with biological treatment by the activated sludge method, but in principle it is necessary to always take measures against clogging (fouling) of the membrane. As a preventive method not to deteriorate the membrane filtration performance, it is necessary to always keep the flow velocity at the membrane surface constant by aeration, etc., and there is a problem that the running cost is high because it is necessary to secure the aeration power for that purpose. . Therefore, realization of high flow rate and high-efficiency filtration is required by devising cleaning.

The biological reaction tank of the MBR treatment apparatus is composed of an anoxic tank and an aerobic tank as disclosed in Non-Patent Document 1, for example, and a membrane filtration unit is immersed in the aerobic tank. In the aerobic tank, an air diffuser for cleaning the membrane unit is provided in addition to the diffuser for supplying dissolved oxygen to prevent blockage of the membrane unit due to sludge adhesion, and air bubbles provided from the air diffuser The surface of the membrane is constantly cleaned by Air for air diffusion is supplied to the piping of the air diffuser from a cleaning blower independent of the air diffuser. The inside of the membrane filtration unit is in a negative pressure state by a suction pump, and the filtrate in the water collection channel of the membrane filtration unit is carried out of the aerobic tank by the suction pump. A certain amount of filtered water is stored in the filtered water tank before being discharged out of the system. In order to prevent a decrease in the filtration flow rate due to dirt on the membrane surface, backwashing is performed using this filtered water at regular intervals. Further, a cleaning chemical solution is added to the filtered water to remove organic substances on the membrane surface, and regular chemical cleaning is also performed.

In such a conventional MBR processing apparatus, as a preventive method for preventing the membrane filtration performance from being deteriorated, it is necessary to perform uniform aeration on the membrane surface to secure the flow velocity on the membrane surface and to enhance the cleaning effect. Therefore, a diffuser for cleaning the membrane must be designed and manufactured so that bubbles are uniformly injected into the reaction tank from each diffuser so that the cleaning effect of the highly efficient membrane surface does not vary. .

However, there is a problem that solid matter gradually adheres to the air holes when the air diffuser is continuously operated. This is probably due to the fact that the activated sludge in the vicinity of the air diffuser dries because the temperature of the pressurized air is high. Since the flow rate of the air passing through the air diffuser to which the solid matter adheres decreases, the parallel flow speed of the activated sludge liquid on the outside of the air diffuser decreases, and the adherence of the adhering matter is further accelerated. As a result, a difference occurs in the amount of adhering matter for each air hole, resulting in a difference in the amount of air diffused and uneven cleaning of the film surface.

Maintenance of the membrane permeation flux (membrane flux) is important in the design and operation of the MBR treatment tank, but due to the above reasons, a portion where the membrane surface is insufficiently washed occurs, so that stable solid-liquid separation treatment is possible. become unable. Therefore, for example, techniques disclosed in Patent Documents 2 to 4 have been proposed as countermeasures against clogging of gas discharge holes in the diffuser.

In order to improve the problems of conventional diffuser tubes, diffuser tubes having a structure that prevents the discharge holes from being blocked by adhering solids by increasing the diameter of the discharge holes of the bubbles in the diffuser pipes have been proposed (patented) References 2, 3). Specifically, by forming a notch or slit for air discharge along the axial direction of the diffuser tube or perpendicular to the axial direction on the lower side of the diffuser tube arranged in the horizontal direction, A reduction in the amount of air discharged from the lower side of the air diffuser is avoided.

In such a structure, the bubbles discharged from the diffuser tube are related to the bubble discharge pressure in the diffuser tube installed in the treatment tank (considering the water depth of the diffuser tube) and the air supply pressure of the diffuser air from the blower. The diameter will be greatly affected.

That is, when bubbles are discharged from the air diffuser while the bubble discharge pressure and the air supply pressure are maintained substantially equal, the bubbles to be discharged are formed in the minimum area of the opening of the air diffuser. The air bubbles are discharged from a portion where the bubbles are relatively small in diameter. However, since the difference between the bubble discharge pressure and the air supply pressure of the air for diffusion is small, the discharge flow rate of the bubbles tends to be relatively small. For this reason, the discharge flow rate from the air diffuser is small, the effect of cleaning the film surface becomes insufficient, and the MBR process is hindered.

On the other hand, when the air supply pressure is set to be larger than the bubble discharge pressure, the discharged bubbles are discharged from a portion formed in a wider area of the opening of the diffuser tube. Therefore, the bubbles are likely to have a relatively large diameter. And according to the increase in the air supply pressure of the air for aeration, a bubble diameter and a flow volume become large. As a result, the discharge flow rate from the air diffusing tube increases, so that the cleaning effect on the film surface can be expected to improve. However, since the discharge bubble diameter becomes large, it is difficult to clean the film surface by uniformly distributing the bubbles, and the cleaning effect becomes insufficient, which impedes MBR processing.

Therefore, in order to supply air bubbles uniformly from the air diffuser holes so that high-flow filtration and high-efficiency membrane surface cleaning effects do not occur, it is necessary to understand the structure and discharge characteristics of the air diffuser. It is necessary to adjust the air pressure of the air for aeration to optimize the bubble distribution and discharge flow rate. However, the optimized discharge state does not always satisfy the specifications required in the MBR processing apparatus.

In addition, an air diffuser described in Patent Document 4 having a cleaning function is known as a measure for preventing clogging of other air diffusers. This air diffuser pushes the activated sludge mixed liquid in the air diffuser to the outside from the opening at the tip by air supplied to the air diffuser at the initial stage of aeration. Thereby, the residue of the activated sludge mixed liquid in the diffuser is prevented, and even when the activated sludge concentration is high, blockage of the diffused holes due to drying can be avoided.

However, during normal aeration, due to the pulsation phenomenon of the air pressure, the liquid in the tank is drawn into the diffuser from the discharge hole, and solid matter gradually adheres to the discharge hole. Since clogging occurs, measures to prevent clogging are not sufficient.

From the above, the realization of the air diffuser having the function of simultaneously satisfying the bubble distribution state and the discharge flow rate required for the air diffuser of the MBR processing apparatus without blocking the discharge hole of the air diffuser is highly efficient in MBR processing. It is important in promoting connection and reducing energy consumption.

JP 2009-106874 A Japanese Patent Laid-Open No. 2001-29987 Japanese Patent Laid-Open No. 10-286444 JP 2001-170677 A JP 11-28463 A

Therefore, the air diffuser of the present invention is an air diffuser for cleaning the membrane module, and comprises an air diffuser disposed at the lower part of the membrane module, and the air diffuser discharges contaminants on its lower surface. The opening is formed so as to be arranged along the axial direction of the member, and the shaft is interposed between the opening at a position higher than the opening and lower than the shaft of the member. A plurality of air holes are formed so as to be arranged along the direction.

(A) is the front view which showed the positional relationship of the diffuser in Embodiment 1 of invention and the diffuser, and a membrane module, (b) is the side view which showed the positional relationship. The schematic block diagram of the membrane separator provided with the air diffusion apparatus in Embodiment 1 of invention. (A) is a front view of the aeration apparatus in Embodiment 1 of invention, (b) is a side view of the apparatus. The side view of the aeration apparatus in Embodiment 2 of invention. (A) is a front view of the aeration apparatus in Embodiment 3 of invention, (b) is a side view of the apparatus. (A) is a front view of the aeration apparatus in Embodiment 4 of invention, (b) is a side view of the apparatus. (A) is a perspective view of an air diffuser of Embodiment 5 in which the lower side of the longitudinal section forms a semicircular shape, and (b) shows the diffuser of Embodiment 5 in which the upper side of the longitudinal section is an obtuse triangle and the lower side forms a semicircular shape. The perspective view of an air member, (c) is a perspective view of the diffuser member of Embodiment 5 in which the upper side of the longitudinal section is an acute triangle and the lower side forms a semicircular shape, and (d) is the embodiment in which the longitudinal section forms a circle. FIG. 5E is a perspective view of the air diffusing member of Embodiment 5 in which the upper side of the longitudinal section is a bell-shaped, while the lower side is a semicircular shape. (A) is a front view of the diffuser in Embodiment 6 of invention, (b) is a side view of the apparatus.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The air diffuser 1 according to the embodiment of the present invention shown in FIG. 1 is an air diffuser for cleaning the membrane module 2, and is disposed below the membrane module 2.

The membrane module 2 is immersed in the activated sludge suspension in the membrane separation tank 4 of the MBR processing apparatus 3 shown in FIG. The membrane module 2 is exemplified as a flat membrane type or a hollow fiber membrane type, and is arranged vertically in the membrane separation tank 4. A pump P is connected to one end of the pipe 5 connected to the water collecting part of the membrane module 2 so that the filtrate can be transferred out of the membrane separation tank 4 by suction.

In addition to the diffuser 1 and the membrane module 2, an aeration device 6 is provided in the membrane separation tank 4. The aeration device 6 is disposed at a lower position than the aeration device 1. The aeration apparatus 6 agitates the activated sludge suspension by supplying the air introduced from the aeration blower B1 into the membrane separation tank 4 and supplies oxygen to the activated sludge. A well-known aeration apparatus adopted in the water treatment field may be applied as the aeration apparatus 6. The air supply amount of the aeration device 6 is preset by the flow rate adjusting valve V1.

The diffuser 1 may also serve as an aeration device. In this embodiment, the membrane cleaning blower B2 also serves as an aeration blower. The air diffuser 1 introduces air for membrane cleaning and aeration from the membrane cleaning blower B2 through the blower pipe 7. By installing the check valve V2 in the pipe 7, the backflow of the liquid in the tank 4 into the diffuser 1 due to the siphon effect when the membrane cleaning blower B2 is stopped is avoided.

The air diffuser 1 includes an air diffuser 10 disposed at the lower part of the membrane module 2 as shown in FIG. The diffuser tube 10 is formed with an opening 11 and a diffuser hole 12.

The diffuser tube 10 is formed in a cylindrical shape, and both ends thereof are sealed. The air supply pipe 7 of the membrane cleaning blower B <b> 2 is connected to one end of the air diffusion pipe 10 or is introduced to the inside of the air diffusion pipe 10. Further, when a spare blower can be prepared, the air supply pipe 7 can be installed for each blower so that the processing can be continued even during maintenance of the blower. In this case, the air supply pipe of the membrane cleaning blower B2 may be connected to both ends of the air diffuser 1 separately. Or you may connect to one edge part collectively.

The pressure and the air flow rate of the membrane cleaning blower B2 are adjusted so that the normal air diffused state of the air diffuser 10 is such that the bubbles flow out from the opening 11. If the pressure and the air flow rate of the membrane cleaning blower B2 are appropriately adjusted, there is no problem with the aeration even if the outflow does not occur. However, in order to further improve the effect of the aeration apparatus 1, the setting is such that the outflow from the opening 11 Is good.

The opening 11 forms a liquid surface and discharges impurities such as activated sludge flowing into the diffuser 1 from the liquid surface without drying. A plurality of openings 11 are formed on the lower surface of the diffuser tube 10 so as to be disposed along the direction of the axis L1 of the diffuser tube 10. The opening diameter and the number of the openings 11 are not particularly limited, but the opening diameter is set to be at least larger than the diameter of the diffuser holes 12.

The air diffuser 12 discharges air for membrane cleaning and aeration provided from the membrane cleaning blower B2. A plurality of air diffusion holes 12 are formed so as to be arranged along the axis L1 direction so as to sandwich the opening 11 at a position higher than the opening 11 and lower than the axis L1. By forming the diffuser holes 12 as described above, the rising bubbles discharged from the diffuser holes 12 are detoured and rise along the outer peripheral surface of the diffuser tube 10, and the gas-liquid mixed flow is disturbed and the bubbles are easily dispersed. Therefore, the planar dispersion effect of the bubbles 100 is increased. When the air diffuser 12 is formed higher than the axis L1 of the air diffuser 10, the liquid phase outside the tube 10 flows back into the tube 10 little by little from the air diffuser 12, and the liquid phase in the tube 10 is diffused. The air diffusion hole 12 will not be blocked, but a stable air diffusion cannot be performed.

3 is set to be equal to the effective width of the membrane module 2. When the air diffuser 10 is formed to be shorter than the effective width of the membrane module 2, the air diffuser 10 is installed so that there is no leakage from the membrane module 2. Further, the diffuser tube 10 may be divided into a plurality of parts so that the total length is equal to the length of the effective width.

In addition, since the region where the bubbles discharged from the air diffuser 12 of the air diffuser 10 expand in a plane as the air bubbles rise, the diameter D of the air diffuser 10 depends on the distance between the air diffuser 12 and the membrane module 2 and the air diffuser 10. It is set as appropriate based on the distance d between the air diffusion holes 12 separated by the longitudinal section. For example, when the pitch of the air diffusion holes 12 in the longitudinal direction of the air diffusion tube 10 is set to about 100 to 200 mm, the distance d can be set at a distance corresponding to the diameter D. Is a range in which a diameter D = 100 to 400 mm up to about twice the distance d can be taken. By setting the dimension of the diameter D of the air diffusing tube 10 within this range, the following effects are produced.

For example, when the diameter D of the air diffusion pipe 10 is equal to the diameter of the air supply pipe 7 of the membrane cleaning blower B2 (about several tens of millimeters), the air supply pipe 7 naturally has a pressure loss that cannot be ignored. Even in this part, pressure loss cannot be ignored. Therefore, the connection portion of the air supply pipe 7 at the end portion of the air diffuser pipe 10 has a pressure distribution such that the air supply pressure is higher than that at the other end portion of the air diffuser pipe 10. As a result, a uniform pressure cannot be maintained in the diffuser tube 10, and it becomes difficult to uniformly distribute bubbles from the diffuser tube 10 and clean the membrane surface of the membrane module 2. Therefore, by setting the diameter D of the air diffusion pipe 10 to be larger than the diameter of the air supply pipe 7, the function as a pressure buffer tank is ensured, and the air supply pressure in the air diffusion pipe 10 becomes substantially uniform. Thereby, the distribution of bubbles from the diffuser tube 10 becomes uniform, and the membrane surface of the membrane module 2 can be evenly cleaned.

The plurality of diffuser holes 12 are arranged at the same height level in the diffuser tube 10 as shown in FIG. The air diffuser 12 facing the opening 11 illustrated in FIG. 1 is arranged on a straight line perpendicular to the longitudinal section of the air diffuser 10, but the position of the air diffuser in the invention needs to be limited to this mode. Alternatively, they may be arranged on a straight line that is not perpendicular to the longitudinal section.

The diameter and pitch of the air holes 12 are arranged based on a well-known technique. For example, a diffuser device in which a plurality of diffuser holes with a diameter of 5 to 10 mm are formed in a diffuser tube at a pitch of 100 to 200 mm and the air diffuser speed is set to 10 m / s or more is known (Patent Document 5, etc.).

An example of the operation of the MBR processing device 3 will be described with reference to FIGS.

The liquid phase in the membrane separation tank 4 to which the water to be treated is supplied is always aerated by the aeration device 1 and the aeration device 6. The activated sludge in the separation membrane tank 4 biologically decomposes pollutants in the liquid phase using oxygen provided by this aeration. The liquid phase in the membrane separation tank 4 is supplied to the membrane module 2 by the water flow by aeration and subjected to solid-liquid separation treatment. In the case where the liquid phase in the membrane separation device 4 is in an over-aerated state, the aeration blower B1 is appropriately stopped to control the dissolved oxygen concentration in the liquid phase.

Further, as shown in FIG. 1, air bubbles 100 provided from the membrane cleaning blower B2 are constantly released from the air diffusion holes 12 of the air diffusion tube 10. The air diffuser 10 has a circular vertical cross section, and the position of the air diffuser 12 is set lower than the height of the axis L1 of the air diffuser 10, so that the rising bubbles discharged from the air diffuser 12 are in the air diffuser 10. Ascending while detouring along the outer peripheral surface, the gas-liquid mixed flow is disturbed and bubbles are dispersed.

On the other hand, impurities such as activated sludge are discharged from the opening 11 of the air diffuser 10. Furthermore, since the upper half of the vertical cross section of the air diffuser tube 10 is a semicircle, the activated sludge staying in the vicinity of the lower end of the membrane module 2 is guided downward along the peripheral surface of the air diffuser tube 10, and the air diffuser tube Accumulation of activated sludge on the top surface of 10 is avoided. This prevents a reduction in the absolute amount of the activated sludge that contributes to the decomposition of the pollutant. The gas-liquid mixed flow rising along the curved surface of the lower surface of the air diffuser 10 is swirled above the air diffuser 10, and since this swirl is maintained, a vigorous gas-liquid mixed flow is generated above the air diffuser 10. Continues, prompting the bubble group to divide.

The violent gas-liquid mixed flow bypassing the division is introduced between the individual separation membranes 20 of the membrane module 2 and used for cleaning the surface of the separation membrane 20. Contaminants separated from the surface of the separation membrane 20 by this washing ride on the gas-liquid mixed flow and are discharged from the upper end opening of the membrane module 2 or settle near the bottom of the membrane separation tank 4. The activated sludge contained in the separated impurities contributes to biological decomposition of the pollutant in the membrane separation tank 4.

The inside of the separation membrane 20 of the membrane module 2 is in a negative pressure state by the suction pump P, and the filtered water that has permeated into the water collecting channel of the membrane module 2 is carried out of the membrane separation tank 4 by the suction pump P.

As described above, according to the air diffusion device 1 of the present embodiment, it is possible to satisfy the bubble distribution state and the discharge flow rate required for the air diffusion device 1 of the MBR processing device 3 without closing the air diffusion holes 12. As a result, the MBR processing efficiency is increased, and the energy consumption can be reduced.

(Embodiment 2)
The air diffuser 13 according to the second embodiment shown in FIG. 4 is an air diffuser according to the first embodiment except that one end of the blower pipe 7 of the membrane cleaning blower B2 is introduced from the opening 11 of the air diffuser 10. The configuration is the same as that of the device 1. According to this embodiment, even if the air diffuser 13 has an integral structure with the membrane module 2, there is no need to remove the blower pipe 7 from the air diffuser 13, and the membrane module 2 is moved above the membrane separation tank 4. Since it can be moved, the working efficiency during the maintenance of the membrane joule 2 is improved. Even if the air diffuser 13 is not integrated with the membrane module 2, the membrane module 2, the air diffuser 1, and the air supply pipe 7 can be handled individually, so that maintenance is facilitated.

(Embodiment 3)
The air diffuser 14 of Embodiment 3 shown in FIG. 5 has the same configuration as the air diffuser 1 of Embodiment 1 except that the shape of the longitudinal section of the air diffuser 15 is rectangular. According to this configuration, the manufacture of the air diffuser and the fixing work in the membrane separation tank 4 are facilitated.

(Embodiment 4)
The air diffuser 16 of Embodiment 4 shown in FIG. 6 has the same configuration as the air diffuser 1 of Embodiment 1 except that the shape of the longitudinal section of the air diffuser tube 17 is an inverted triangle. Since this structure can be composed of three plate-like members, the manufacture of the air diffuser of the present invention is further facilitated.

(Embodiment 5)
In the air diffuser 18 of the fifth embodiment shown in FIG. 7, the shape of the longitudinal section of the air diffuser 10 is any of those shown in FIGS. 7 (a) to 7 (e). Is the same configuration as the air diffuser 1 of the first embodiment.

In the air diffusers 18a to 18e shown in FIGS. 7 (a) to 7 (e), the shape of the vertical cross section of the air diffuser 10 is at least the bottom surface of which is formed as a curved surface. After the current collides with the lower surface, a flow along the curved surface is formed. Thereby, the air bubbles discharged from the air diffusion holes of the air diffusion tube 10 can be dispersed in a plane.

In particular, in the air diffusers 18b to 18e shown in FIGS. 7B to 7E, the vertical cross section of the air diffuser tube 10 is formed in a convex shape upward. The guide can be efficiently guided downward, and accumulation of activated sludge on the air diffuser 10 can be avoided.

Moreover, since the upper surface of the air diffuser 10 is formed in a curved surface, the

acid generators

18d and 18e illustrated in FIGS. 7D and 7E rise along the curved surface of the air diffuser 10. The coming gas-liquid mixed flow can be swirled above the diffuser tube 10, and this swirling flow can be maintained. Thereby, a vigorous gas-liquid mixed flow is continued above the diffuser tube 10, and the division of the bubble group is promoted. Then, the vigorous gas-liquid mixed flow bypassing the division can be provided between the separation membranes 20 of the membrane module 2, and the membrane surface cleaning effect can be maintained.

(Embodiment 6)
The air diffuser 19 of Embodiment 6 shown in FIG. 8 has a mode in which a single opening 11 is continuously opened along the axis L1 direction of the air diffuser 10 at the lower surface of the air diffuser 10. Except for this, the configuration is the same as that of the air diffuser 1 of the first embodiment. According to this configuration, the liquid in the membrane separation tank 4 mixed into the diffuser 19 can be quickly discharged.

Although the present invention has been described with specific examples based on the above-described Embodiments 1 to 6, the diffuser of the present invention can be dealt with by appropriately changing the specifications according to the specifications of the membrane module. For example, the number of installed devices is changed according to the air diffusing area of the air diffusing device, and a plurality of air diffusing devices are installed for a single membrane module. Further, the specifications such as the length of the air diffuser are changed according to the required area of the air diffuser of the membrane module.

1, 13, 14, 16, 18a to 18e ... Air diffuser 2 ... Membrane module 7 ... Air pipe 10 ... Air diffuser (air diffuser)
11 ... Opening 12 ... Air diffuser B2 ... Membrane cleaning blower

Claims

A diffuser for cleaning the membrane module,
Consisting of an air diffuser disposed at the bottom of the membrane module;
The diffuser member is formed such that an opening for discharging impurities on the lower surface thereof is disposed along the axial direction of the member, and is higher than the opening and higher than the shaft of the member. An air diffusing device, wherein a plurality of air diffusing holes are formed so as to be disposed along the axial direction so as to sandwich the opening at a low position.
The air diffuser according to claim 1, wherein a plurality of the openings are formed and arranged along the axial direction.
The air diffuser according to claim 1, further comprising a pipe for discharging air supplied from a blower from an end portion, the end portion being arranged to be inserted into the opening.
The air diffusing device according to claim 1, wherein the air diffusing member is formed in a cylindrical shape.
The air diffusing device according to claim 1, wherein the air diffusing member has a rectangular shape in a longitudinal section.
The air diffusing device according to claim 1, wherein the air diffusing member has an inverted triangular shape in a longitudinal section.
The air diffusing device according to claim 1, wherein the air diffusing member is formed in a three-dimensional shape with a lower side of a longitudinal section projecting downward.
The air diffuser according to claim 7, wherein the lower side of the air diffuser has a semicircular shape.
The air diffusing device according to claim 8, wherein the air diffusing member has a triangular shape on the upper side of the vertical cross section and a semicircular shape on the lower half.
10. The air diffuser according to claim 9, wherein the air diffuser has a bell-shaped upper side in the longitudinal section and a semicircular lower half.