WO2013008522A1 - Air diffuser - Google Patents

Air diffuser Download PDF

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Publication number
WO2013008522A1
WO2013008522A1 PCT/JP2012/062146 JP2012062146W WO2013008522A1 WO 2013008522 A1 WO2013008522 A1 WO 2013008522A1 JP 2012062146 W JP2012062146 W JP 2012062146W WO 2013008522 A1 WO2013008522 A1 WO 2013008522A1
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WO
WIPO (PCT)
Prior art keywords
air diffuser
air
diffuser
membrane
section
Prior art date
Application number
PCT/JP2012/062146
Other languages
French (fr)
Japanese (ja)
Inventor
彰利 中川
寛 野口
泰日 李
Original Assignee
株式会社明電舎
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Filing date
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Publication of WO2013008522A1 publication Critical patent/WO2013008522A1/en

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    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/12Activated sludge processes
    • C02F3/20Activated sludge processes using diffusers
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D61/00Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14Ultrafiltration; Microfiltration
    • B01D61/18Apparatus therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D61/00Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14Ultrafiltration; Microfiltration
    • B01D61/20Accessories; Auxiliary operations
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20Mixing gases with liquids
    • B01F23/23Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/231Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
    • B01F23/23105Arrangement or manipulation of the gas bubbling devices
    • B01F23/2312Diffusers
    • B01F23/23121Diffusers having injection means, e.g. nozzles with circumferential outlet
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20Mixing gases with liquids
    • B01F23/23Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/231Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
    • B01F23/23105Arrangement or manipulation of the gas bubbling devices
    • B01F23/2312Diffusers
    • B01F23/23123Diffusers consisting of rigid porous or perforated material
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20Mixing gases with liquids
    • B01F23/23Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/231Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
    • B01F23/23105Arrangement or manipulation of the gas bubbling devices
    • B01F23/2312Diffusers
    • B01F23/23123Diffusers consisting of rigid porous or perforated material
    • B01F23/231231Diffusers consisting of rigid porous or perforated material the outlets being in the form of perforations
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01FMIXING, e.g. DISSOLVING, EMULSIFYING OR DISPERSING
    • B01F23/00Mixing according to the phases to be mixed, e.g. dispersing or emulsifying
    • B01F23/20Mixing gases with liquids
    • B01F23/23Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids
    • B01F23/231Mixing gases with liquids by introducing gases into liquid media, e.g. for producing aerated liquids by bubbling
    • B01F23/23105Arrangement or manipulation of the gas bubbling devices
    • B01F23/2312Diffusers
    • B01F23/23126Diffusers characterised by the shape of the diffuser element
    • B01F23/231265Diffusers characterised by the shape of the diffuser element being tubes, tubular elements, cylindrical elements or set of tubes
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/12Activated sludge processes
    • C02F3/1236Particular type of activated sludge installations
    • C02F3/1268Membrane bioreactor systems
    • C02F3/1273Submerged membrane bioreactors
    • CCHEMISTRY; METALLURGY
    • C02TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02FTREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
    • C02F3/00Biological treatment of water, waste water, or sewage
    • C02F3/02Aerobic processes
    • C02F3/12Activated sludge processes
    • C02F3/20Activated sludge processes using diffusers
    • C02F3/201Perforated, resilient plastic diffusers, e.g. membranes, sheets, foils, tubes, hoses
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2313/00Details relating to membrane modules or apparatus
    • B01D2313/26Specific gas distributors or gas intakes
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02WCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
    • Y02W10/00Technologies for wastewater treatment
    • Y02W10/10Biological treatment of water, waste water, or sewage

Definitions

  • the present invention relates to an air diffuser provided in a reaction tank using an immersion type membrane module.
  • a sewage treatment apparatus using a submerged membrane module there is a type in which a plurality of external pressure type solid-liquid separation flat membranes are vertically arranged in a reaction tank.
  • MBR membrane separation activated sludge treatment
  • 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.
  • the diameter of the air diffuser of the air diffuser must be relatively large, 3-10 mm. is there.
  • 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).
  • Patent Document 1 In the cleaning of the membrane surface of the membrane module, dirt on the membrane surface is removed by sweeping the membrane surface with a vigorous gas-liquid mixed flow generated by the rise of bubbles due to aeration, and accumulation of dirt is suppressed.
  • 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.
  • MF and UF membranes are PSF (polysulfone), PE (polyethylene), CA (cellulose acetate), PAN (polyacrylonitrile), PP (polypropylene), PVDF (polyvinylidene fluoride), PTFE (polytetrafluoroethylene). Fluoroethylene) is used.
  • NF film and the RO film a polyamide-based organic film is often used.
  • a film using an ceramic MF film, UF film, NF film
  • the shape of the membrane can be classified into a hollow fiber membrane, a flat membrane, a tubular membrane, and a monolith.
  • filtration methods in membrane treatment include total volume filtration (dead-end-filtration) and cross-flow filtration.
  • 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.
  • 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 processing apparatus includes, for example, an anoxic tank and an aerobic tank as disclosed in Non-Patent Document 1, and a membrane module is immersed in the aerobic tank.
  • an aeration device for cleaning the membrane module is provided separately from the aeration device for supplying dissolved oxygen, and the air bubbles provided from this aeration device
  • 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 module is in a negative pressure state by a suction pump, and the filtrate in the water collection channel of the membrane module 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.
  • the said membrane surface is back-washed with the said filtered water with a fixed period.
  • a cleaning chemical solution is added to the filtered water to remove organic substances on the membrane surface, and periodic chemical cleaning is also performed.
  • 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. .
  • membrane permeation flux membrane flux
  • 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.
  • the MBR processing apparatus disclosed in Patent Document 5 improves the cleaning performance of the membrane by increasing the rising speed of the liquid phase in the vicinity of the membrane surface of the membrane module and enhancing the effect of dispersing bubbles below the membrane module.
  • a dispersion means for dispersing bubbles is provided below the membrane module, and a diffuser tube is disposed below the dispersion means.
  • 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.
  • 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.
  • 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.
  • 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.
  • a bubble diameter and a flow volume become large.
  • the discharge flow rate from the air diffusing tube increases, so that the cleaning effect on the film surface can be expected to improve.
  • 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.
  • 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.
  • 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.
  • 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.
  • the MBR processing apparatus of Patent Document 5 that serves both as oxygen supply and membrane cleaning can simultaneously achieve both good dispersion of bubbles supplied to the membrane and high liquid flow velocity near the membrane surface. It has become.
  • the oxygen supply efficiency to the activated sludge it is necessary to increase the contact area at the oxygen transfer interface in the liquid phase as fine bubbles. It is necessary to generate a strong gas-liquid mixed flow due to the upward flow due to.
  • Non-Patent Document 1 a blower facility for the aeration device and the diffuser device is required, and accordingly, the installation space for the facility and the piping line of the air supply system become complicated.
  • JP 2009-106874 A Japanese Patent Laid-Open No. 2001-29987 Japanese Patent Laid-Open No. 10-286444 JP 2001-170677 A JP 2006-2224050 A JP 11-28463 A
  • the air diffuser of the present invention is an air diffuser for aeration to activated sludge and membrane cleaning of the membrane module, and the first air diffuser disposed immediately below the membrane module is not directly below the air diffuser. And a second air diffuser disposed in parallel with the first air diffuser at a position.
  • the first air diffuser is formed such that a plurality of openings are arranged along the axial direction of the member on the lower surface at the position directly below, while a plurality of diffusers having a smaller diameter than the openings are formed. Plural across the cross-section in that direction so that the pores are not directly under the position and are higher than the opening and lower than the axis of the diffuser member along the axial direction. Is formed.
  • the second air diffusion member is formed such that a plurality of openings are arranged along the axial direction of the member on the lower surface thereof, and a plurality of air diffusion holes having a smaller diameter than the opening are provided in the opening.
  • the cross section in the direction is formed so as to be arranged along the axial direction at a position higher than the axis of the diffuser member and lower than the axis of the diffuser member.
  • the top view which showed the positional relationship of the air diffusion apparatus and membrane module in Embodiment 1 of invention.
  • (A) is the front view which showed the positional relationship of the 1st air diffusion member and membrane module in Embodiment 1 of invention,
  • (b) shows the positional relationship of the said 1st air diffusion member and the separation membrane of the said membrane module.
  • the side view shown. is a side view of the first air diffuser of the air diffuser according to Embodiment 1 of the invention,
  • (b) is a cross-sectional view taken along the line AA of the first air diffuser, and
  • (c) is the first air diffuser.
  • BB sectional view (d) is a side view of the second air diffuser of the air diffuser, and (e) is a CC cross sectional view of the second air diffuser.
  • the side view of the aeration apparatus in Embodiment 2 of invention (A) is a side view of the first air diffuser of the air diffuser in Embodiment 3 of the invention, (b) is a cross-sectional view taken along the line AA of the first air diffuser, and (c) is the first air diffuser.
  • (A) is a side view of the first air diffuser of the air diffuser in Embodiment 4 of the invention
  • (b) is a cross-sectional view taken along the line AA of the first air diffuser
  • (b) is the first air diffuser.
  • (C) is a side view of the second air diffuser of the air diffuser
  • (e) is a CC cross sectional view of the second air diffuser.
  • (A) is a perspective view of an air diffuser in Embodiment 5 in which the lower side of the radial cross section forms a semicircular shape
  • (b) is an embodiment 5 in which the upper side of the radial cross section is an obtuse triangle while the lower side forms a semicircular shape.
  • FIG. 7C is a perspective view of the air diffuser in FIG. 5C
  • FIG. 8C is a perspective view of the air diffuser in Embodiment 5 in which the upper side of the radial cross section is an acute triangle and the lower side is a semicircular shape
  • the air diffuser 1 in 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 as shown in FIG.
  • the membrane module 2 is immersed in the activated sludge suspension in the membrane separation tank 4 of the MBR processor 3 as shown in FIG.
  • Examples of the membrane module 2 include those having a separation membrane of a flat membrane type or a hollow fiber membrane type.
  • the membrane module 2 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.
  • the air diffuser 1 also functions as an aerator for supplying air to the activated sludge and an air diffuser for cleaning the membrane of the membrane module 2.
  • the air diffuser 1 introduces air for membrane cleaning and aeration from the blower B through a pipe 6. By installing a check valve V in the pipe 6, the backflow of the liquid in the tank 4 to the blower B due to the siphon effect when the blower B stops is avoided.
  • the air diffuser 1 includes an air diffuser 11 disposed immediately below the membrane module 2, and an air diffuser 12 disposed in parallel with the air diffuser 11 at a position not directly below the air diffuser 11. .
  • the diffuser tube 11 and the diffuser tube 12 are formed in a cylindrical shape, and both ends thereof are sealed.
  • the air supply pipe 6 of the blower B is connected to one end of the air diffusion pipes 11 and 12 or connected to the inside of the air diffusion pipes 11 and 12. Further, when a spare blower can be prepared, the pipe 6 can be installed for each blower so that the processing can be continued even during the maintenance of the blower. In this case, the air supply pipe of the blower B may be connected to both ends of the air diffuser 1 separately. Or you may connect to one edge part collectively.
  • the air diffuser 11 is formed with an opening 111 and air diffuser holes 112.
  • the pressure of the blower B and the air flow rate are adjusted so that bubbles discharged from the opening 111 can clean at least the membrane surface of the membrane module 2.
  • the opening 111 mainly discharges air used for film cleaning. Further, the opening 111 forms a liquid surface and discharges impurities such as activated sludge that has flowed into the diffuser tube 11 from the liquid surface without drying. As shown in FIG. 3B, a plurality of openings 111 are formed so as to be arranged along the direction of the axis L ⁇ b> 11 of the diffuser tube 11 on the lower surface of the diffuser tube 11 at a position directly below the membrane module 2.
  • the opening diameter and the number of openings 111 are not particularly limited.
  • the membrane surface cleaning of the membrane module 2 can be performed uniformly.
  • the air diffuser 112 is formed higher than the axis L11 of the air diffuser 11, the liquid phase outside the air diffuser 11 flows into the air diffuser 11 little by little from the air diffuser 112, and the liquid phase in the air diffuser 11 is obtained. May be filled up to the level of the air diffuser 112, and the air diffuser 112 is not blocked, but a stable air diffuser cannot be performed.
  • the total length L of the air diffuser 11 is set longer than the effective width L0 of the membrane module 2.
  • a plurality of diffusion tubes 11 may be arranged in parallel according to the area of the bottom surface of the membrane module 2.
  • the diameter D of the air diffuser 11 is as shown in FIGS. 4 (a) to 4 (c). The distance is appropriately set based on the distance between the air diffuser 112 and the membrane module 2 and the distance d between the air diffuser holes 112 separating the longitudinal cross section of the air diffuser 11 in the direction of the axis L11.
  • the air supply pipe 6 when the diameter D of the air diffuser 11 is equal to the diameter (about several tens of millimeters) of the air supply pipe 6 of the blower B, the air supply pipe 6 naturally has a portion of the air diffuser 11 as well as the pressure loss cannot be ignored. But pressure loss cannot be ignored. For this reason, the connection portion of the pipe 6 at the end of the air diffuser 11 has a pressure distribution such that the air supply pressure is higher than that at the other end of the air diffuser 11. As a result, a uniform pressure cannot be maintained in the diffuser tube 11, and it becomes difficult to evenly distribute bubbles from the diffuser tube 11 and clean the membrane surface of the membrane module 2.
  • the diameter D of the air diffusion pipe 11 is set to be larger than the diameter of the air supply pipe 6, the function as a pressure buffer tank is ensured, and the air supply pressure in the air diffusion pipe 11 becomes substantially uniform. Thereby, the distribution of bubbles from the air diffuser 11 becomes uniform, and the membrane surface of the membrane module 2 can be evenly cleaned.
  • the diameter and pitch of the air holes 112 are arranged based on a well-known technique.
  • a diffuser 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 an air diffuser speed is set to 10 m / s or more (Patent Document 6, etc.).
  • the air diffuser 12 is arranged in parallel with the air diffuser 11 at a position not directly below the membrane module 2.
  • the diffuser 12 is formed to have substantially the same diameter as the diffuser 11 as shown in FIGS. 4 (d) and 4 (e).
  • An opening 121 and an air hole 122 are formed in the air diffuser 12.
  • a plurality of openings 121 are formed on the lower surface of the air diffuser 12 so as to be disposed along the direction of the axis L12 of the air diffuser 12. Further, the air diffusion holes 122 are formed to have a smaller diameter than the opening 121.
  • a plurality of air diffusion holes 122 are formed symmetrically across the cross section in the direction so as to be disposed along the axis L12 direction at a position higher than the opening 121 and lower than the axis L12.
  • the total length L and diameter D of the air diffuser 12 and the diameters and pitches of the opening 121 and the air diffuser 122 are set to the same specifications as those of the air diffuser 11.
  • the number of the diffuser tubes 11 and 12 is not limited to the illustrated number of installations, and is set as appropriate according to the capacity of the membrane module 2 and the membrane separation tank 4.
  • the air holes 111 and 121 of the air diffusers 11 and 12 are arranged symmetrically with respect to the axial cross section of the air diffusers 11 and 12 as shown in the figure. May be.
  • the pipes 6 connected to the diffuser pipes 11 and 12 are well known so that the flow rate and pressure of the air supplied to the diffuser pipes 11 and 12 can be individually adjusted.
  • a flow control valve and a pressure regulator are installed as appropriate.
  • the liquid phase in the membrane separation tank 4 to which the water to be treated is supplied is always aerated by the aeration pipes 11 and 12 of the aeration apparatus 1, and the aeration amount is determined by the dissolved oxygen concentration of the liquid phase being predetermined. It is controlled to be within the range of.
  • 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 the aeration and subjected to solid-liquid separation processing.
  • 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 passage of the membrane module 2 is carried out of the membrane separation tank 4 by the suction pump P.
  • air bubbles 100 provided from the blower B are constantly released from the air diffuser holes 112 of the air diffuser tube 11.
  • oxygen is provided to the sludge.
  • the air diffuser 11 has a circular cross section in the radial direction and the position of the air diffuser 112 is set lower than the height of the axis L11 of the air diffuser 11. Therefore, the rising bubbles discharged from the air diffuser 112 are scattered. Ascending along the outer peripheral surface of the trachea 11, the gas-liquid mixed flow is disturbed, and the bubbles 100 are dispersed. Thereby, the contact area of the oxygen movement interface in a liquid phase increases, and the oxygen supply efficiency with respect to the said activated sludge increases.
  • bubbles having a diameter larger than at least the bubbles 100 are discharged from the opening 111 of the air diffuser 11 and used for membrane cleaning of the membrane module 2. Furthermore, impurities such as activated sludge are discharged from the opening 111. Further, since the radial cross section in the radial direction of the air diffuser 11 is circular, the activated sludge staying near the lower end of the membrane module 2 is guided downward along the peripheral surface of the air diffuser 11, and Accumulation of activated sludge on the top surface is avoided. This prevents a reduction in the absolute amount of the activated sludge that contributes to the decomposition of the pollutant.
  • 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.
  • air bubbles provided from the blower B are always released from the air diffuser holes 122 in the same manner as the air diffuser 11. These bubbles also come into contact with the activated sludge to provide oxygen to the sludge. Further, bubbles having a diameter larger than that of the bubbles are discharged from the opening 121 and impurities such as activated sludge are discharged from the opening 121. In this way, oxygen can be supplied evenly to the activated sludge staying away from the membrane module 2 in the membrane separation tank 4, and the activated sludge concentration in the liquid phase can be made uniform.
  • the oxygen supply efficiency for the activated sludge and the membrane cleaning efficiency of the membrane module 2 are increased without blocking the air diffusion holes 112 and 122 of the air diffusion tubes 11 and 12. Can improve the processing efficiency and reduce energy consumption.
  • the above air diffuser 20 has an integral structure with the membrane module 2, there is no need to remove the pipe 6 from the air diffuser 20, and the membrane module 2 can be moved above the membrane separation tank 4. Therefore, the work efficiency at the time of the maintenance of the membrane joule 2 is improved. Even if the air diffuser 20 is not integrated with the membrane module 2, the membrane module 2, the air diffuser 20, and the pipe 6 can be taken out and handled individually, so that maintenance is facilitated.
  • the air diffuser 30 according to the third embodiment is the air diffuser 1 except that the shape of the cross section in the radial direction of the air diffusers 11 and 12 is rectangular as shown in FIGS. 6 (a) to 6 (e). It has the same configuration. According to this aspect, the manufacture of the air diffuser and the fixing work in the membrane separation tank 4 are facilitated.
  • the air diffuser 40 according to the fourth embodiment is an air diffuser except that the shape of the cross section in the radial direction of the air diffusers 11 and 12 is an inverted triangle as shown in FIGS. 7 (a) to 7 (e). 1 has the same configuration. According to this aspect, since the plate-like member can be constituted by three pieces, the manufacture of the air diffuser according to the present invention is further facilitated.
  • the air diffuser in the fifth embodiment is an air diffuser except that the shape of the cross section in the radial direction of the air diffusers 11 and 12 is any one of those shown in FIGS. 8 (a) to 8 (d). 1 has the same configuration.
  • the upper side of the radial cross section is an obtuse triangle, while the lower side is semicircular.
  • the upper side of the radial cross section is an acute triangle, while the lower side is a semicircular shape.
  • the air diffusers 11 and 12 of the air diffuser 54 shown in FIG. 8D have a bell-shaped upper side in the radial cross section, while the lower side has a semicircular shape.
  • the air diffusers 52 to 54 are formed so that the radial cross sections of the air diffusers 11 and 12 are convex upward, the activated sludge can be efficiently guided below the air diffusers 11 and 12. , 12 can avoid the accumulation of activated sludge.
  • the diffuser 54 is a gas-liquid mixed flow that rises along the curved surfaces of the diffuser pipes 11 and 12, similarly to the diffuser apparatus 1. Can be swirled above the diffuser tubes 11 and 12, and this swirling flow can be maintained. Thereby, a vigorous gas-liquid mixed flow is continued above the diffuser tubes 11 and 12, and the dispersion of bubbles is promoted.
  • the diffuser of the present invention can be handled by changing the specifications as appropriate 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.
  • Air diffuser 2 ... Membrane module 6 ... Pipe 11 . Air diffuser (first air diffuser) 12 . Air diffuser (second air diffuser) 111, 121 ... opening 112, 122 ... diffuse hole

Abstract

An air diffuser (1) is provided with an aeration tube (11) disposed directly under a membrane module (2) and aeration tubes (12) disposed parallel to the aeration tube (11) in positions not directly below the membrane module. While a plurality of opening parts are formed along the axial direction of the tube (11) on the lower surface of the aeration tube (11) in the position directly below the membrane module (2), a plurality of aeration holes with a diameter smaller than the opening parts are formed so as to be disposed in a position, which is not directly below the membrane module and is higher than the opening parts and lower than the axis of the tube (11) along the axial direction and so as to sandwich a cross-section in that direction. While a plurality of opening parts are formed on the lower surface of the aeration tubes (12) along the axial direction of the tubes (12), a plurality of aeration holes with a diameter smaller than the opening parts are formed so as to be positioned higher than the opening parts and lower than the axis of the tubes (12) along the axial direction and so as to sandwich a cross-section in that direction.

Description

散気装置Air diffuser
 本発明は浸漬型の膜モジュールを用いた反応槽に備えられる散気装置に関する。 The present invention relates to an air diffuser provided in a reaction tank using an immersion type membrane module.
 浸漬型の膜モジュールを用いた下水処理装置として例えば複数の外圧式固液分離平膜を反応槽内に膜面が鉛直に配置されるタイプのものがある。この膜分離活性汚泥処理(以下、MBRと称する)方式の下水処理装置では反応槽の下部に設置された散気管から空気気泡を曝気している。これは反応槽内の活性汚泥を構成する微生物に酸素を供給するためであることと、気泡上昇に伴って生成される水流により膜表面を洗浄して膜面の付着物を除去して目詰まりを抑制するためである。 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.
 MBR方式の下水処理装置は濁質成分の流出を防ぐことが可能であるため、最終沈殿池で固液分離する場合と比べて活性汚泥の濃度を高くして運転することが可能となっている。その結果、装置を小型化でき、さらに発生汚泥を低減できる。 Since the MBR sewage treatment apparatus can prevent the turbid components from flowing out, it can be operated with a higher concentration of activated sludge 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.
 MBR方式は活性汚泥濃度が高いことと一定以上の大きさの気泡でなければ膜面の洗浄効果が得られないことから、散気管の散気孔の径は3~10mmと比較的大きくする必要がある。一般にはこのサイズの孔を配管に複数形成させた構造の散気管が用いられる(例えば特許文献1)。膜モジュールの膜面の洗浄では、曝気による気泡の上昇によって生じる激しい気液混合流により膜表面を掃流することで膜面の汚れを除去し、汚れの蓄積を抑制する。 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). In the cleaning of the membrane surface of the membrane module, dirt on the membrane surface is removed by sweeping the membrane surface with a vigorous gas-liquid mixed flow generated by the rise of bubbles due to aeration, and accumulation of dirt is suppressed.
 下水道分野においては除去対象物質・目標処理水質に応じて使用する膜が選定される。主に固形物の除去を目的とする場合にはMF膜、UF膜が用いられており、MBRで使用される膜も通常MF膜である。膜の材質は大別すると有機膜と無機膜に区分できる。 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.
 有機膜としては,MF膜及びUF膜では、PSF(ポリスルホン)、PE(ポリエチレン)、CA(酢酸セルロース)、PAN(ポリアクリロニトリル)、PP(ポリプロピレン)、PVDF(ポリフッ化ビニリデン)、PTFE(ポリテトラフロロエチレン)のいずれかの材料からなるものが用いられている。NF膜及びRO膜ではポリアミド系の有機膜が多く用いられている。無機膜としては、セラミックを用いた膜(MF膜、UF膜、NF膜)が開発されている。 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.
 また、膜の形状としては中空糸膜、平膜、管状膜、モノリスに区分できる。さらに,膜処理におけるろ過方式は全量ろ過(デッドエンドろ過:dead-end-filtration)とクロスフローろ過(cross-flow filtration)とがある。 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.
 全量ろ過方式は膜で阻止されたものが膜に付着しろ過とともに付着物が累積するのである時点で一定時間ごとに必ずろ過を停止させ、累積した付着物の層を除去しなければならない。一方、クロスフローろ過方式は膜表面に平行な流れで常に膜表面を洗浄させながらろ過する。この方式はろ過と並行して付着物の除去が行われる連続運転ができ且つろ過速度を高く維持できるが、十分な平行流を作るためろ過流量に対して供給水側の流量が大きくなり、ろ過流量当りのエネルギー消費が大きくなる。 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.
 MBR法は活性汚泥法による生物処理に膜ろ過を組み合わせた排水処理方法であるが、原理的に膜の目詰まり(ファウリング)を常に対策する必要がある。膜ろ過性能を低下させないための予防方法として、曝気などにより膜表面での流速を常に一定に保つ必要があり、そのための曝気動力を確保しなければならないことから、ランニングコストが高いという問題がある。それゆえに、洗浄を工夫することで高流量及び高効率なろ過処理の実現が必要とされている。 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.
 MBR処理装置の生物反応槽は例えば非特許文献1に開示されたように無酸素槽と好気槽とからなり、好気槽内に膜モジュールを浸漬させている。好気槽内においては汚泥の付着による膜モジュールの閉塞予防のため、溶存酸素供給用の散気装置とは別に膜モジュール洗浄用の散気装置が具備され、この散気装置から供された気泡によって膜の表面を常時洗浄している。前記散気装置の配管へは散気ブロアとは独立した洗浄ブロアから散気用の空気を供給している。また、前記膜モジュールの内部は吸引ポンプによって負圧状態となっており、膜モジュールの集水路内のろ過水は当該吸引ポンプによって好気槽の外部に搬出される。ろ過水は系外への排出の前にろ過水槽に一定量貯留される。そして、膜モジュールの膜表面の汚れによるろ過流量低下を予防するために一定周期で前記ろ過水による当該膜表面の逆洗浄が行われる。さらに、膜表面の有機物除去のため前記ろ過水に洗浄用の薬液が添加されて定期的な薬液洗浄も実施されている。 The biological reaction tank of the MBR processing apparatus includes, for example, an anoxic tank and an aerobic tank as disclosed in Non-Patent Document 1, and a membrane module is immersed in the aerobic tank. In the aerobic tank, in order to prevent clogging of the membrane module due to adhesion of sludge, an aeration device for cleaning the membrane module is provided separately from the aeration device for supplying dissolved oxygen, and the air bubbles provided from this aeration device 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 module is in a negative pressure state by a suction pump, and the filtrate in the water collection channel of the membrane module 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. And in order to prevent the filtration flow rate fall by the stain | pollution | contamination of the membrane surface of a membrane module, the said membrane surface is back-washed with the said filtered water with a fixed period. Furthermore, a cleaning chemical solution is added to the filtered water to remove organic substances on the membrane surface, and periodic chemical cleaning is also performed.
 このような従来のMBR処理装置においては、膜ろ過性能を低下させないための予防方法として、膜面に対して均等に曝気を実施し、膜表面の流速を確保して洗浄効果を高める必要がある。そのため膜洗浄用の散気装置は、高効率な膜表面の洗浄効果にばらつきが生じないようにそれぞれの散気孔から均一に気泡が反応槽内へ注入されるように設計、製作しなければならない。 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 aeration evenly 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. .
 しかし、散気装置を連続運転していると散気孔へ徐々に固形物が付着しまう問題がある。これは加圧空気の温度が高いので散気孔付近の活性汚泥が乾燥することが原因の一つと考えられる。固形物が付着した散気孔では通過する空気の流量が減少するため、散気孔の外側における活性汚泥液の並行流速度が低下し、付着物の付着がさらに加速される。その結果、散気孔ごとの付着物の量に差異が生じ、散気量の差異が生じて膜表面の洗浄が不均一となる。 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.
 MBR処理槽の設計や処理運転においては膜透過流束(膜フラックス)の維持が重要であるが、上記理由により膜表面の洗浄が不十分な部分が発生するため、安定した固液分離処理ができなくなる。そこで、散気部の気体吐出孔の目詰まり対策として、例えば特許文献2~4に記載の技術が提案されている。 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.
 また、MBR処理装置においては、生物処理効率を維持するためには活性汚泥への酸素供給が重要となる。そこで、特許文献5に開示のMBR処理装置は膜モジュールの膜表面の近傍にて液相の上昇速度を高めると共に当該膜モジュールの下方では気泡の分散効果を高めることで膜の洗浄性能の向上と曝気による酸素の供給性能と向上とを図っている。具体的には膜モジュールの下方にて気泡を分散させる分散手段を備え、さらにこの分散手段の下方に散気管を配置させている。 Also, in the MBR treatment apparatus, oxygen supply to the activated sludge is important in order to maintain the biological treatment efficiency. Therefore, the MBR processing apparatus disclosed in Patent Document 5 improves the cleaning performance of the membrane by increasing the rising speed of the liquid phase in the vicinity of the membrane surface of the membrane module and enhancing the effect of dispersing bubbles below the membrane module. We are trying to improve the oxygen supply performance by aeration. Specifically, a dispersion means for dispersing bubbles is provided below the membrane module, and a diffuser tube is disposed below the dispersion means.
 従来の散気管のもつ問題点を改善するために散気管の気泡の吐出孔の径をより大きくすることにより吐出孔を付着固形物によって閉塞から避ける構造を有する散気管が提案されている(特許文献2,3)。具体的には水平方向に配置した散気管の下部側にて空気吐出用の切れ込みやスリットを当該散気管の軸方向に沿ってまたは軸方向に対して垂直に形成することで固形物の付着による散気管下部側からの空気吐出量の減少を回避させている。 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.
 このような構造では処理槽に設置された散気管における気泡吐出圧(散気管の設置水深が加味される)とブロアからの散気用空気の送気圧との関係にて散気管から吐出する気泡径は大きく影響を受けることとなる。すなわち、前記気泡吐出圧と前記送気圧とがほぼ等しく維持されている状態で散気管から気泡が吐出されている場合には、吐出される気泡は散気管の開口部の最小面積にて形成される部分から吐出されることとなり、気泡は比較的小径のものとはなる。しかしながら、気泡吐出圧と散気用空気の送気圧との差が小さいため、その気泡の吐出流量は比較的少量となりやすい。そのため、散気管からの吐出流量が少なく、膜表面の洗浄効果が不十分となりMBR処理に支障が生じることとなる。 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.
 一方、前記気泡吐出圧よりも前記送気圧がよりも大きくとなるように設定した場合には、吐出される気泡は散気管の開口部のより広い面積にて形成される部分から吐出されることとなり、気泡は比較的大径のものとなりやすい。そして、散気用空気の送気圧の増加に応じて、気泡径と流量とが大きくなる。これにより、散気管からの吐出流量が増加するので膜表面の洗浄効果が向上する期待がもてる。しかしながら、吐出気泡径が大きくなるため気泡を均一に分布させて膜表面を洗浄することが困難となり洗浄効果が不十分となりMBR処理に支障が生じることとなる。 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.
 したがって、特許文献2,3の散気管において、高流量のろ過の実現及び高効率な膜表面の洗浄効果にばらつきが生じないように散気管の散気孔から均一に気泡を供給するには散気管の構造と吐出特性を把握する必要がある。さらに、散気用空気の送気圧を調整し、気泡の分布状態と吐出流量を最適化する必要がある。しかしながら、その最適化した吐出状態がMBR処理装置において要求される仕様を満たすとは限らない。 Therefore, in the diffuser tubes of Patent Documents 2 and 3, in order to supply air bubbles uniformly from the diffuser holes of the diffuser tube so as not to cause variations in the realization of high flow rate filtration and the highly efficient membrane surface cleaning effect, It is necessary to understand the structure and discharge characteristics. Furthermore, it is necessary to adjust the air supply pressure of the air for aeration to optimize the distribution state of the bubbles and the discharge flow rate. However, the optimized discharge state does not always satisfy the specifications required in the MBR processing apparatus.
 また、その他の散気部の目詰まり防止策として洗浄機能を有する特許文献4に記載の散気装置が知られている。この散気装置は曝気の初期時に散気装置に供給する空気によって散気装置内の活性汚泥混合液を先端の開放口から外部へ押し出す。これにより、散気装置内における活性汚泥混合液の残留が防止され、活性汚泥濃度が高い場合にあっても乾燥による散気孔の閉塞を回避できる。しかしながら、通常の曝気時には送気圧の脈動現象などにより、散気装置の内部へ吐出孔から槽内液が引き込まれ、吐出孔へ徐々に固形物が付着し、乾燥、固形化によって散気装置の目詰まりが生ずることとなるため、目詰まり防止対策は十分ではない。 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.
 また、酸素の供給と膜の洗浄を兼ねた特許文献5のMBR処理装置は膜に供される気泡の良好な分散と膜表面近傍での高い液流速の2つを同時に達成することが可能となっている。しかしながら、活性汚泥への酸素供給効率を上げるためには微細気泡として液相での酸素移動界面での接触面積の増大を図る必要がある一方で膜洗浄効率を上げるためには極力大きい径の気泡による上昇流により強い気液混合流を発生させる必要がある。 In addition, the MBR processing apparatus of Patent Document 5 that serves both as oxygen supply and membrane cleaning can simultaneously achieve both good dispersion of bubbles supplied to the membrane and high liquid flow velocity near the membrane surface. It has become. However, in order to increase the oxygen supply efficiency to the activated sludge, it is necessary to increase the contact area at the oxygen transfer interface in the liquid phase as fine bubbles. It is necessary to generate a strong gas-liquid mixed flow due to the upward flow due to.
 特許文献5のMBR処理装置のように、気泡を分散させると、発生した気泡が小径化するので活性汚泥への酸素供給と膜洗浄との効果を同時に発揮させるのは困難となる。そのため、MBR処理装置の生物処理効率を安定的に維持させるには散気装置を目的別に少なくとも2種類設置せざるを得ない(非特許文献1)。したがって、曝気装置、散気装置のためのブロワ設備が必要となり、これに伴い当該設備の設置スペースの確保及び空気供給系の配管ラインが複雑となる。 When the bubbles are dispersed as in the MBR processing apparatus of Patent Document 5, since the generated bubbles are reduced in diameter, it is difficult to simultaneously exhibit the effects of supplying oxygen to activated sludge and cleaning the membrane. For this reason, in order to stably maintain the biological treatment efficiency of the MBR treatment device, at least two types of aeration devices must be installed for different purposes (Non-Patent Document 1). Accordingly, a blower facility for the aeration device and the diffuser device is required, and accordingly, the installation space for the facility and the piping line of the air supply system become complicated.
 以上のことから散気管の吐出孔を閉塞することなくMBR処理に要求される酸素供給量と膜洗浄のための気泡の分布状態と吐出流量を満たす散気管の実現がMBR処理の高効率につながり消費エネルギーの削減を進める上で重要となっている。 From the above, the realization of a diffuser tube that satisfies the oxygen supply amount required for MBR processing, the distribution state of bubbles for membrane cleaning, and the discharge flow rate without blocking the discharge hole of the diffuser tube leads to high efficiency of MBR processing. This is important in promoting energy consumption reduction.
特開2009-106874号公報JP 2009-106874 A 特開2001-29987号公報Japanese Patent Laid-Open No. 2001-29987 特開平10-286444号公報Japanese Patent Laid-Open No. 10-286444 特開2001-170677号公報JP 2001-170677 A 特開2006-224050号公報JP 2006-2224050 A 特開平11-28463号公報JP 11-28463 A
 そこで、本発明の散気装置は、活性汚泥への曝気と膜モジュールの膜洗浄のための散気装置であって、前記膜モジュールの真下に配置される第一散気部材と、前記真下でない位置にて前記第一散気部材と並列に配置される第二散気部材とを備える。 Therefore, the air diffuser of the present invention is an air diffuser for aeration to activated sludge and membrane cleaning of the membrane module, and the first air diffuser disposed immediately below the membrane module is not directly below the air diffuser. And a second air diffuser disposed in parallel with the first air diffuser at a position.
 前記第一散気部材は、前記真下の位置における下面にて複数の開口部が当該部材の軸方向に沿って配置されるように形成される一方で、当該開口部よりも小径の複数の散気孔が前記真下でない位置であって当該開口部よりも高位であり且つ当該散気部材の軸よりも低位の位置にて前記軸方向に沿って配置されるように当該方向の断面を挟んで複数形成されている。 The first air diffuser is formed such that a plurality of openings are arranged along the axial direction of the member on the lower surface at the position directly below, while a plurality of diffusers having a smaller diameter than the openings are formed. Plural across the cross-section in that direction so that the pores are not directly under the position and are higher than the opening and lower than the axis of the diffuser member along the axial direction. Is formed.
 前記第二散気部材は、その下面にて複数の開口部が当該部材の軸方向に沿って配置されるように形成されると共に、当該開口部よりも小径の複数の散気孔が当該開口部よりも高位であり且つ当該散気部材の軸よりも低位の位置にて前記軸方向に沿って配置されるように当該方向の断面を挟んで形成されている。 The second air diffusion member is formed such that a plurality of openings are arranged along the axial direction of the member on the lower surface thereof, and a plurality of air diffusion holes having a smaller diameter than the opening are provided in the opening. The cross section in the direction is formed so as to be arranged along the axial direction at a position higher than the axis of the diffuser member and lower than the axis of the diffuser member.
発明の実施形態1における散気装置と膜モジュールとの位置関係を示した平面図。The top view which showed the positional relationship of the air diffusion apparatus and membrane module in Embodiment 1 of invention. 発明の実施形態1における散気装置を備えた膜分離装置の概略構成図。The schematic block diagram of the membrane separator provided with the air diffusion apparatus in Embodiment 1 of invention. (a)は発明の実施形態1における第一散気部材と膜モジュールとの位置関係を示した正面図,(b)は当該第一散気部材と当該膜モジュールの分離膜との位置関係を示した側面図。(A) is the front view which showed the positional relationship of the 1st air diffusion member and membrane module in Embodiment 1 of invention, (b) shows the positional relationship of the said 1st air diffusion member and the separation membrane of the said membrane module. The side view shown. (a)は発明の実施形態1における散気装置の第一散気部材の側面図,(b)は当該第一散気部材のA-A断面図,(c)は当該第一散気部材のB-B断面図,(d)は当該散気装置の第二散気部材の側面図,(e)は当該第二散気部材のC-C断面図。(A) is a side view of the first air diffuser of the air diffuser according to Embodiment 1 of the invention, (b) is a cross-sectional view taken along the line AA of the first air diffuser, and (c) is the first air diffuser. BB sectional view, (d) is a side view of the second air diffuser of the air diffuser, and (e) is a CC cross sectional view of the second air diffuser. 発明の実施形態2における散気装置の側面図。The side view of the aeration apparatus in Embodiment 2 of invention. (a)は発明の実施形態3における散気装置の第一散気部材の側面図,(b)は当該第一散気部材のA-A断面図,(c)は当該第一散気部材のB-B断面図,(d)は当該散気装置の第二散気部材の側面図,(e)は当該第二散気部材のC-C断面図。(A) is a side view of the first air diffuser of the air diffuser in Embodiment 3 of the invention, (b) is a cross-sectional view taken along the line AA of the first air diffuser, and (c) is the first air diffuser. BB sectional view, (d) is a side view of the second air diffuser of the air diffuser, and (e) is a CC cross sectional view of the second air diffuser. (a)は発明の実施形態4における散気装置の第一散気部材の側面図,(b)は当該第一散気部材のA-A断面図,(b)は当該第一散気部材のB-B断面図,(c)は当該散気装置の第二散気部材の側面図,(e)は当該第二散気部材のC-C断面図。(A) is a side view of the first air diffuser of the air diffuser in Embodiment 4 of the invention, (b) is a cross-sectional view taken along the line AA of the first air diffuser, and (b) is the first air diffuser. (C) is a side view of the second air diffuser of the air diffuser, and (e) is a CC cross sectional view of the second air diffuser. (a)は径方向断面の下辺が半円形を成す実施形態5における散気部材の斜視図,(b)は径方向断面の上辺が鈍角三角形である一方で下辺が半円形を成す実施形態5における散気部材の斜視図,(c)は径方向断面の上辺が鋭角三角形である一方で下辺が半円形を成す実施形態5における散気部材の斜視図,(d)は径方向断面の上辺が釣鐘状である一方で下辺が半円形を成す実施形態5における散気部材の斜視図。(A) is a perspective view of an air diffuser in Embodiment 5 in which the lower side of the radial cross section forms a semicircular shape, and (b) is an embodiment 5 in which the upper side of the radial cross section is an obtuse triangle while the lower side forms a semicircular shape. FIG. 7C is a perspective view of the air diffuser in FIG. 5C, FIG. 8C is a perspective view of the air diffuser in Embodiment 5 in which the upper side of the radial cross section is an acute triangle and the lower side is a semicircular shape, and FIG. The perspective view of the diffuser member in Embodiment 5 whose bottom side comprises a semicircle, while is a bell shape.
 以下、図面を参照しながら本発明の実施の形態について説明する。 Hereinafter, embodiments of the present invention will be described with reference to the drawings.
 (実施形態1)
 図1に示された本発明の実施形態における散気装置1は膜モジュール2を洗浄する散気装置であって図2に示されたように膜モジュール2の下方に配置されている。
(Embodiment 1)
The air diffuser 1 in 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 as shown in FIG.
 膜モジュール2は図2に示したようにMBR処理装置3の膜分離槽4内の活性汚泥懸濁液に浸漬される。膜モジュール2は平膜タイプや中空糸膜タイプの分離膜を備えたものが例示される。膜モジュール2は膜分離槽4において鉛直に配置される。膜モジュール2の集水部に接続された配管5の一端にはポンプPが接続されて吸引によりろ過液を膜分離槽4外に移送できるようになっている。 The membrane module 2 is immersed in the activated sludge suspension in the membrane separation tank 4 of the MBR processor 3 as shown in FIG. Examples of the membrane module 2 include those having a separation membrane of a flat membrane type or a hollow fiber membrane type. The membrane module 2 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.
 散気装置1は活性汚泥に空気を供給するための曝気装置と膜モジュール2の膜洗浄のための散気装置の機能を兼ねている。散気装置1は配管6を介して膜洗浄及び曝気用の空気をブロアBから導入する。配管6には逆止弁Vが設置されることで、ブロアBが停止した時のサイフォン効果による槽4内液のブロアBへの逆流を回避させている。 The air diffuser 1 also functions as an aerator for supplying air to the activated sludge and an air diffuser for cleaning the membrane of the membrane module 2. The air diffuser 1 introduces air for membrane cleaning and aeration from the blower B through a pipe 6. By installing a check valve V in the pipe 6, the backflow of the liquid in the tank 4 to the blower B due to the siphon effect when the blower B stops is avoided.
 散気装置1は、図1,図2に示したように、膜モジュール2の真下に配置される散気管11と、前記真下でない位置にて散気管11と並列に配置される散気管12と、を備える。 As shown in FIGS. 1 and 2, the air diffuser 1 includes an air diffuser 11 disposed immediately below the membrane module 2, and an air diffuser 12 disposed in parallel with the air diffuser 11 at a position not directly below the air diffuser 11. .
 散気管11,散気管12は円筒状に形成され、その両端は密閉されている。ブロアBの送気配管6は散気管11,12の一方の端部に接続されるかまたは散気管11,12の内部まで導入された状態で接続される。また、配管6は予備のブロアが準備可能な場合にはブロア毎に設置することによりブロアのメンテナンス時にも処理を継続することが可能となる。尚、その場合のブロアBの送気配管は散気装置1の両端部に分けて接続してもよい。または、一方の端部にまとめて接続してもよい。 The diffuser tube 11 and the diffuser tube 12 are formed in a cylindrical shape, and both ends thereof are sealed. The air supply pipe 6 of the blower B is connected to one end of the air diffusion pipes 11 and 12 or connected to the inside of the air diffusion pipes 11 and 12. Further, when a spare blower can be prepared, the pipe 6 can be installed for each blower so that the processing can be continued even during the maintenance of the blower. In this case, the air supply pipe of the blower B may be connected to both ends of the air diffuser 1 separately. Or you may connect to one edge part collectively.
 散気管11には図3(a),図3(b)に示したように開口部111と散気孔112が形成されている。散気管11の通常の散気状態は開口部111から排出された気泡が少なくとも膜モジュール2の膜面を洗浄できるようにブロアBの圧力及び空気流量が調整される。 As shown in FIGS. 3A and 3B, the air diffuser 11 is formed with an opening 111 and air diffuser holes 112. In the normal diffused state of the diffuser tube 11, the pressure of the blower B and the air flow rate are adjusted so that bubbles discharged from the opening 111 can clean at least the membrane surface of the membrane module 2.
 開口部111は主に膜洗浄に供される空気を排出する。また、開口部111は液面を形成し散気管11の内部に流入してきた活性汚泥等の夾雑物を乾燥させることなく当該液面から排出する。開口部111は図3(b)に示したように膜モジュール2の真下の位置における散気管11の下面にて散気管11の軸L11方向に沿って配置されるように複数形成されている。開口部111の開口径及び個数は特に限定しない。 The opening 111 mainly discharges air used for film cleaning. Further, the opening 111 forms a liquid surface and discharges impurities such as activated sludge that has flowed into the diffuser tube 11 from the liquid surface without drying. As shown in FIG. 3B, a plurality of openings 111 are formed so as to be arranged along the direction of the axis L <b> 11 of the diffuser tube 11 on the lower surface of the diffuser tube 11 at a position directly below the membrane module 2. The opening diameter and the number of openings 111 are not particularly limited.
 散気孔112は主に活性汚泥に供される空気を排出する。散気孔112はその開口径及び個数は特に限定しないが少なくとも開口部111よりも小径に形成されている。散気孔112は膜モジュール2の真下でない位置であって開口部111よりも高位であり且つ軸L11よりも低位の位置にて散気管11の軸L11方向に沿って配置されるように当該方向の断面を挟んで対称的に複数形成されている。散気孔112がこのように配置されることで、散気孔112から吐出した上昇気泡は散気管11の外周面に沿って迂回して上昇し、気液混合流が乱れて気泡が分散しやすくなり気泡100の平面的な分散効果が高まる。これにより、膜モジュール2の膜面洗浄を均等に行える。尚、散気孔112が散気管11の軸L11よりも高位に形成されると、散気管11外の液相が散気孔112から少しずつ散気管11内に流入し、散気管11内の液相が散気孔112のレベルまで満たされる可能性があり、散気孔112は閉塞しないが安定した散気ができなくなる。 The air diffuser 112 mainly discharges air supplied to activated sludge. The opening diameter and the number of the air diffusion holes 112 are not particularly limited, but are formed at least smaller than the opening 111. The air diffuser 112 is not located directly below the membrane module 2, is higher than the opening 111, and is positioned lower than the axis L11 along the direction of the axis L11 of the air diffuser 11. A plurality of layers are formed symmetrically across the cross section. By arranging the diffuser holes 112 in this manner, the rising bubbles discharged from the diffuser holes 112 detour along the outer peripheral surface of the diffuser tube 11, and the gas-liquid mixed flow is disturbed, so that the bubbles are easily dispersed. The planar dispersion effect of the bubbles 100 is enhanced. Thereby, the membrane surface cleaning of the membrane module 2 can be performed uniformly. When the air diffuser 112 is formed higher than the axis L11 of the air diffuser 11, the liquid phase outside the air diffuser 11 flows into the air diffuser 11 little by little from the air diffuser 112, and the liquid phase in the air diffuser 11 is obtained. May be filled up to the level of the air diffuser 112, and the air diffuser 112 is not blocked, but a stable air diffuser cannot be performed.
 図3(b)に示されたように散気管11の全長Lは膜モジュール2の有効幅L0よりも長く設定される。散気管11は膜モジュール2の底面の面積に応じて複数並列に配置してもよい。また、散気管11の散気孔112から吐出した気泡の存在領域は気泡が上昇するに従い平面的に広がるので図4(a)~図4(c)に示したように散気管11の径Dは散気孔112と膜モジュール2との距離及び散気管11の軸L11方向の縦断面を隔てた散気孔112の間隔dに基づき適宜に設定される。散気管11の径Dは例えば散気管11の長手方向の散気孔112のピッチが100~200mm程度で設けられている場合、これに相当する距離で間隔dが設定され得るので径Dの値としては間隔dの最大2倍程度までの径D=100~400mmが取りうる範囲となる。散気管11の径Dの寸法がこの範囲で設定されることで以下の効果が生ずる。 3B, the total length L of the air diffuser 11 is set longer than the effective width L0 of the membrane module 2. A plurality of diffusion tubes 11 may be arranged in parallel according to the area of the bottom surface of the membrane module 2. In addition, since the region where the air bubbles discharged from the air diffuser 112 of the air diffuser 11 expand in a plane as the air bubbles rise, the diameter D of the air diffuser 11 is as shown in FIGS. 4 (a) to 4 (c). The distance is appropriately set based on the distance between the air diffuser 112 and the membrane module 2 and the distance d between the air diffuser holes 112 separating the longitudinal cross section of the air diffuser 11 in the direction of the axis L11. For example, when the pitch D of the air diffusion holes 112 in the longitudinal direction of the air diffusion pipe 11 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 diffuser 11 within this range, the following effects are produced.
 例えば、散気管11の径DがブロアBの送気配管6の径(数10mm程度)と同等である場合、送気配管6では当然、圧力損失を無視できないことと同様に散気管11の部分でも圧力損失は無視できない。そのため、散気管11の端部における配管6の接続部分は散気管11のもう一方の端部に比べて送気圧が高い状態となるような圧力分布となる。このことにより、散気管11内で均一圧が維持できず、散気管11から気泡を均一に分布させて膜モジュール2の膜表面を洗浄することが困難となる。そこで、散気管11の径Dが送気配管6の径よりも大きく設定されることで、圧力バッファタンクとしての機能が確保され、散気管11内の送気圧が略均一となる。これにより散気管11からの気泡の分布が均一となり膜モジュール2の膜表面を均等に洗浄できる。 For example, when the diameter D of the air diffuser 11 is equal to the diameter (about several tens of millimeters) of the air supply pipe 6 of the blower B, the air supply pipe 6 naturally has a portion of the air diffuser 11 as well as the pressure loss cannot be ignored. But pressure loss cannot be ignored. For this reason, the connection portion of the pipe 6 at the end of the air diffuser 11 has a pressure distribution such that the air supply pressure is higher than that at the other end of the air diffuser 11. As a result, a uniform pressure cannot be maintained in the diffuser tube 11, and it becomes difficult to evenly distribute bubbles from the diffuser tube 11 and clean the membrane surface of the membrane module 2. Therefore, by setting the diameter D of the air diffusion pipe 11 to be larger than the diameter of the air supply pipe 6, the function as a pressure buffer tank is ensured, and the air supply pressure in the air diffusion pipe 11 becomes substantially uniform. Thereby, the distribution of bubbles from the air diffuser 11 becomes uniform, and the membrane surface of the membrane module 2 can be evenly cleaned.
 散気孔112の径及びピッチは周知技術に基づき配置される。例えば直径5~10mmの散気孔が100~200mmピッチで散気管に複数形成され、空気散気速度が10m/s以上に設定される散気装置が知られている(特許文献6等)。 The diameter and pitch of the air holes 112 are arranged based on a well-known technique. For example, there is known a diffuser 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 an air diffuser speed is set to 10 m / s or more (Patent Document 6, etc.).
 散気管12は膜モジュール2の真下でない位置にて散気管11と並列に配置されている。散気管12は図4(d),図4(e)に示したように散気管11と略同径に形成されている。散気管12には開口部121と散気孔122が形成されている。開口部121は散気管12の下面にて散気管12の軸L12方向に沿って配置されるように複数形成されている。また、散気孔122は開口部121よりも小径に形成されている。散気孔122は開口部121よりも高位であって軸L12よりも低位の位置にて軸L12方向に沿って配置されるように当該方向の断面を挟んで対称的に複数形成されている。散気管12の全長Lと径D、及び開口部121,散気孔122の径とピッチは散気管11と同様の仕様に設定される。 The air diffuser 12 is arranged in parallel with the air diffuser 11 at a position not directly below the membrane module 2. The diffuser 12 is formed to have substantially the same diameter as the diffuser 11 as shown in FIGS. 4 (d) and 4 (e). An opening 121 and an air hole 122 are formed in the air diffuser 12. A plurality of openings 121 are formed on the lower surface of the air diffuser 12 so as to be disposed along the direction of the axis L12 of the air diffuser 12. Further, the air diffusion holes 122 are formed to have a smaller diameter than the opening 121. A plurality of air diffusion holes 122 are formed symmetrically across the cross section in the direction so as to be disposed along the axis L12 direction at a position higher than the opening 121 and lower than the axis L12. The total length L and diameter D of the air diffuser 12 and the diameters and pitches of the opening 121 and the air diffuser 122 are set to the same specifications as those of the air diffuser 11.
 以上の散気管11,12の設置数は図示された設置数に限定することなく膜モジュール2,膜分離槽4の容量に応じて適宜に設定される。また、散気管11,12の散気孔111,121は図示されたように散気管11,12の軸方向の断面を挟んで対称に配置されているがこの態様に限定することなく非対称に配置させてもよい。さらに、図1には図示省略されているが散気管11,12に各々接続される配管6には各散気管11,12に供される空気の流量及び圧力を個別に調節できるように周知の流量調整バルブや圧力調整器が適宜に設置される。 The number of the diffuser tubes 11 and 12 is not limited to the illustrated number of installations, and is set as appropriate according to the capacity of the membrane module 2 and the membrane separation tank 4. In addition, the air holes 111 and 121 of the air diffusers 11 and 12 are arranged symmetrically with respect to the axial cross section of the air diffusers 11 and 12 as shown in the figure. May be. Further, although not shown in FIG. 1, the pipes 6 connected to the diffuser pipes 11 and 12 are well known so that the flow rate and pressure of the air supplied to the diffuser pipes 11 and 12 can be individually adjusted. A flow control valve and a pressure regulator are installed as appropriate.
 図1~図3を参照しながらMBR処理装置3の動作例について説明する。 An example of the operation of the MBR processing apparatus 3 will be described with reference to FIGS.
 被処理水が供給される膜分離槽4内の液相は散気装置1の散気管11,12によって常時曝気された状態となっており、その曝気量は当該液相の溶存酸素濃度が所定の範囲内になるように制御される。分離膜槽4内の活性汚泥はこの曝気によって供された酸素を利用して液相中の汚濁物質を生物学的に分解する。また、膜分離槽4内の液相は前記曝気による水流によって膜モジュール2に供されて固液分離処理される。膜モジュール2の分離膜20の内部は吸引ポンプPによって負圧状態となっており、膜モジュール2の集水路内に透過したろ過水は吸引ポンプPによって膜分離槽4外に搬出される。 The liquid phase in the membrane separation tank 4 to which the water to be treated is supplied is always aerated by the aeration pipes 11 and 12 of the aeration apparatus 1, and the aeration amount is determined by the dissolved oxygen concentration of the liquid phase being predetermined. It is controlled to be within the range of. 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 the aeration and subjected to solid-liquid separation processing. 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 passage of the membrane module 2 is carried out of the membrane separation tank 4 by the suction pump P.
 図3(a)に示されたように散気管11の散気孔112からはブロアBから供された空気の気泡100が常時放出される。これらの気泡100は前記活性汚泥と接触することで当該汚泥に対して酸素が供される。また、散気管11は径方向断面が円形を成していると共に散気孔112の位置が散気管11の軸L11の高さよりも低位に設定されているので散気孔112から吐出した上昇気泡は散気管11の外周面に沿って迂回しながら上昇し、気液混合流が乱れて気泡100が分散する。これにより、液相における酸素移動界面の接触面積が増大し、前記活性汚泥に対する酸素供給効率が高まる。 As shown in FIG. 3 (a), air bubbles 100 provided from the blower B are constantly released from the air diffuser holes 112 of the air diffuser tube 11. When these bubbles 100 come into contact with the activated sludge, oxygen is provided to the sludge. The air diffuser 11 has a circular cross section in the radial direction and the position of the air diffuser 112 is set lower than the height of the axis L11 of the air diffuser 11. Therefore, the rising bubbles discharged from the air diffuser 112 are scattered. Ascending along the outer peripheral surface of the trachea 11, the gas-liquid mixed flow is disturbed, and the bubbles 100 are dispersed. Thereby, the contact area of the oxygen movement interface in a liquid phase increases, and the oxygen supply efficiency with respect to the said activated sludge increases.
 一方、散気管11の開口部111からは少なくとも気泡100よりも大径の気泡が排出されて膜モジュール2の膜洗浄に供される。さらには開口部111からは活性汚泥等の夾雑物が排出される。また、散気管11は径方向の径方向断面が円形となっているので、膜モジュール2の下端付近に滞留する活性汚泥は散気管11の周面に沿って下方に案内され、散気管11の上面における活性汚泥の堆積が回避される。これにより前記汚濁物質の分解に寄与する前記活性汚泥の絶対量の低減が防止される。そして、散気管11の下面の曲面に沿って上昇してくる気液混合流は散気管11の上方において旋回し、この旋回流が維持されるので散気管11の上方にて激しい気液混合流が継続し、気泡の存在領域が平面的に広がり、膜モジュール2の膜面を均等に洗浄できる。 On the other hand, bubbles having a diameter larger than at least the bubbles 100 are discharged from the opening 111 of the air diffuser 11 and used for membrane cleaning of the membrane module 2. Furthermore, impurities such as activated sludge are discharged from the opening 111. Further, since the radial cross section in the radial direction of the air diffuser 11 is circular, the activated sludge staying near the lower end of the membrane module 2 is guided downward along the peripheral surface of the air diffuser 11, and Accumulation of activated sludge on the top surface 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 diffuser tube 11 swirls above the diffuser tube 11, and since this swirl flow is maintained, a vigorous gas-liquid mixed flow above the diffuser tube 11 Continues, the bubble existence area spreads in a plane, and the membrane surface of the membrane module 2 can be evenly cleaned.
 前記分割迂回した激しい気液混合流は膜モジュール2の個々の分離膜20間に導入され、分離膜20の表面の洗浄に供される。この洗浄によって分離膜20の表面から剥離された夾雑物は、前記気液混合流に乗って膜モジュール2の上端開口部から排出されるか、または、膜分離槽4の底部付近に沈降する。前記剥離された夾雑物に含まれる活性汚泥は膜分離槽4内における汚濁物質の生物学的分解に寄与する。 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.
 また、散気管12においても散気管11と同様にブロアBから供された空気の気泡が散気孔122から常時放出される。これらの気泡も前記活性汚泥と接触することで当該汚泥に対して酸素が供される。さらに、開口部121からは前記気泡よりも大径の気泡が排出されると共に開口部121からは活性汚泥等の夾雑物が排出される。このようにして膜分離槽4内の膜モジュール2から離れて滞留する活性汚泥に対しても均等に酸素を供給できると共に液相の活性汚泥濃度を均一化させることができる。 Also, in the air diffuser 12, air bubbles provided from the blower B are always released from the air diffuser holes 122 in the same manner as the air diffuser 11. These bubbles also come into contact with the activated sludge to provide oxygen to the sludge. Further, bubbles having a diameter larger than that of the bubbles are discharged from the opening 121 and impurities such as activated sludge are discharged from the opening 121. In this way, oxygen can be supplied evenly to the activated sludge staying away from the membrane module 2 in the membrane separation tank 4, and the activated sludge concentration in the liquid phase can be made uniform.
 以上のように本実施形態の散気装置1によれば散気管11,12の散気孔112,122を閉塞させることなく活性汚泥に対する酸素供給効率と膜モジュール2の膜洗浄効率とが高まるのでMBRの処理効率が向上し消費エネルギーを削減できる。 As described above, according to the air diffusion device 1 of this embodiment, the oxygen supply efficiency for the activated sludge and the membrane cleaning efficiency of the membrane module 2 are increased without blocking the air diffusion holes 112 and 122 of the air diffusion tubes 11 and 12. Can improve the processing efficiency and reduce energy consumption.
 (実施形態2)
 図5に示された実施形態2の散気装置20はブロアBの配管6の一端が散気管11,12の開口部111,121の任意の一つから導入させた態様となっていること以外は散気装置1と同じ構成となっている。図5においては散気管11,12の散気孔112,122の図示が省略されている。配管6の挿入位置は特に限定されない。挿入される開口部111は施工やメンテナンスの作業性に基づき任意に選択される。
(Embodiment 2)
The air diffuser 20 of Embodiment 2 shown in FIG. 5 has a mode in which one end of the pipe 6 of the blower B is introduced from any one of the openings 111 and 121 of the air diffusers 11 and 12. Has the same configuration as the air diffuser 1. In FIG. 5, illustration of the air holes 112 and 122 of the air diffusers 11 and 12 is omitted. The insertion position of the pipe 6 is not particularly limited. The opening 111 to be inserted is arbitrarily selected based on workability of construction and maintenance.
 以上の散気装置20は膜モジュール2と一体的な構造となっていても、配管6を散気装置20から取り外す手間がなくなり、膜モジュール2を膜分離槽4の上方へ移動させることができるので、膜ジュール2のメンテナンス時の作業効率が向上する。また、散気装置20が膜モジュール2と一体的な構造となっていなくても、膜モジュール2と散気装置20と配管6を個別に取り出して扱うことができるのでメンテナンスしやすくなる。 Even if the above air diffuser 20 has an integral structure with the membrane module 2, there is no need to remove the pipe 6 from the air diffuser 20, and the membrane module 2 can be moved above the membrane separation tank 4. Therefore, the work efficiency at the time of the maintenance of the membrane joule 2 is improved. Even if the air diffuser 20 is not integrated with the membrane module 2, the membrane module 2, the air diffuser 20, and the pipe 6 can be taken out and handled individually, so that maintenance is facilitated.
 (実施形態3)
 実施形態3における散気装置30は図6(a)~図6(e)に示されたように散気管11,12の径方向断面の形状が矩形となっていること以外は散気装置1と同じ構成となっている。本態様によれば散気装置の製作及び膜分離槽4内への固定作業が容易となる。
(Embodiment 3)
The air diffuser 30 according to the third embodiment is the air diffuser 1 except that the shape of the cross section in the radial direction of the air diffusers 11 and 12 is rectangular as shown in FIGS. 6 (a) to 6 (e). It has the same configuration. According to this aspect, the manufacture of the air diffuser and the fixing work in the membrane separation tank 4 are facilitated.
 (実施形態4)
 実施形態4における散気装置40は図7(a)~図7(e)に示されたように散気管11,12の径方向断面の形状が逆三角形となっていること以外は散気装置1と同じ構成となっている。本態様によれば板状部材を三枚で構成できるので本発明における散気装置の製作がより一層容易となる。
(Embodiment 4)
The air diffuser 40 according to the fourth embodiment is an air diffuser except that the shape of the cross section in the radial direction of the air diffusers 11 and 12 is an inverted triangle as shown in FIGS. 7 (a) to 7 (e). 1 has the same configuration. According to this aspect, since the plate-like member can be constituted by three pieces, the manufacture of the air diffuser according to the present invention is further facilitated.
 (実施形態5)
 実施形態5における散気装置は散気管11,12の径方向断面の形状が図8(a)~図8(d)に示されたいずれかの形状を成していること以外は散気装置1と同じ構成となっている。
(Embodiment 5)
The air diffuser in the fifth embodiment is an air diffuser except that the shape of the cross section in the radial direction of the air diffusers 11 and 12 is any one of those shown in FIGS. 8 (a) to 8 (d). 1 has the same configuration.
 図8(a)に示された散気装置51の散気管11,12はその径方向断面の下辺が半円形を成している。図8(b)に示された散気装置52の散気管11,12はその径方向断面の上辺が鈍角三角形である一方で下辺が半円形を成している。図8(c)に示された散気装置53の散気管11,12はその径方向断面の上辺が鋭角三角形である一方で下辺が半円形を成している。図8(d)に示された散気装置54の散気管11,12はその径方向断面の上辺が釣鐘状である一方で下辺が半円形を成している。 The lower sides of the radial cross sections of the air diffusers 11 and 12 of the air diffuser 51 shown in FIG. In the air diffusers 11 and 12 of the air diffuser 52 shown in FIG. 8B, the upper side of the radial cross section is an obtuse triangle, while the lower side is semicircular. In the air diffusers 11 and 12 of the air diffuser 53 shown in FIG. 8C, the upper side of the radial cross section is an acute triangle, while the lower side is a semicircular shape. The air diffusers 11 and 12 of the air diffuser 54 shown in FIG. 8D have a bell-shaped upper side in the radial cross section, while the lower side has a semicircular shape.
 以上の散気装置51~54は散気管11,12の径方向断面の形状が少なくともその下面が曲面に形成されているので、膜分離槽4内の流体の流れが当該下面に衝突した後、当該曲面上に沿った流れが形成される。これにより、散気管11,12の散気孔112,122から吐出された気泡を平面的に分散できるので、活性汚泥に対する酸素供給効率が高まると共に膜モジュールの膜面洗浄を均等に行える。 In the above air diffusers 51 to 54, since the shape of the cross section in the radial direction of the air diffusers 11 and 12 is formed at least on the lower surface thereof, after the fluid flow in the membrane separation tank 4 collides with the lower surface, A flow along the curved surface is formed. Thereby, since the air bubbles discharged from the air diffusion holes 112 and 122 of the air diffusion pipes 11 and 12 can be dispersed in a plane, the oxygen supply efficiency with respect to the activated sludge is increased and the membrane surface of the membrane module can be evenly cleaned.
 特に、散気装置52~54は散気管11,12の径方向断面が上に凸の形状に形成されているので、活性汚泥を散気管11,12の下方に効率良く案内でき、散気管11,12上での活性汚泥の堆積を回避させることができる。 In particular, since the air diffusers 52 to 54 are formed so that the radial cross sections of the air diffusers 11 and 12 are convex upward, the activated sludge can be efficiently guided below the air diffusers 11 and 12. , 12 can avoid the accumulation of activated sludge.
 また、散気装置54は、散気装置1と同様に、散気管11,12の上面が曲面に形成されているので、散気管11,12の曲面に沿って上昇してくる気液混合流を散気管11,12の上方において旋回させ、この旋回流を維持させることができる。これにより、散気管11,12の上方において激しい気液混合流が継続し、気泡の分散が促進される。 Moreover, since the upper surface of the diffuser pipes 11 and 12 is formed in a curved surface, the diffuser 54 is a gas-liquid mixed flow that rises along the curved surfaces of the diffuser pipes 11 and 12, similarly to the diffuser apparatus 1. Can be swirled above the diffuser tubes 11 and 12, and this swirling flow can be maintained. Thereby, a vigorous gas-liquid mixed flow is continued above the diffuser tubes 11 and 12, and the dispersion of bubbles is promoted.
 以上の実施形態1~5に基づき本発明について具体例にて説明したが、本願発明の散気装置は膜モジュールの仕様に応じて適宜仕様変更して対応可能である。例えば、散気装置の散気可能面積に応じて、その設置個数を変更し、単一膜モジュールに対して複数の散気装置が設置される。また、膜モジュールの散気の必要面積に応じて、散気装置の長さなどの仕様が変更される。 Although the present invention has been described with specific examples based on the above first to fifth embodiments, the diffuser of the present invention can be handled by changing the specifications as appropriate 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.
1,20,30,40,51~54…散気装置
2…膜モジュール
6…配管
11…散気管(第一散気部材)
12…散気管(第二散気部材)
111,121…開口部
112,122…散気孔
1, 20, 30, 40, 51 to 54 ... Air diffuser 2 ... Membrane module 6 ... Pipe 11 ... Air diffuser (first air diffuser)
12 ... Air diffuser (second air diffuser)
111, 121 ... opening 112, 122 ... diffuse hole

Claims (10)

  1.  活性汚泥への曝気と膜モジュールの膜洗浄のための散気装置であって、
     前記膜モジュールの真下に配置される第一散気部材と、
     前記真下でない位置にて前記第一散気部材と並列に配置される第二散気部材と
    を備え、
     前記第一散気部材は、前記真下の位置における下面にて複数の開口部が当該部材の軸方向に沿って配置されるように形成される一方で、当該開口部よりも小径の複数の散気孔が前記真下でない位置であって当該開口部よりも高位であり且つ当該散気部材の軸よりも低位の位置にて前記軸方向に沿って配置されるように当該方向の断面を挟んで形成され、
     前記第二散気部材は、その下面にて複数の開口部が当該部材の軸方向に沿って配置されるように形成されると共に、当該開口部よりも小径の複数の散気孔が当該開口部よりも高位であり且つ当該散気部材の軸よりも低位の位置にて前記軸方向に沿って配置されるように当該方向の断面を挟んで形成されたこと
    を特徴とする散気装置。
    An aeration device for aeration of activated sludge and membrane cleaning of membrane modules,
    A first air diffuser disposed immediately below the membrane module;
    A second air diffuser disposed in parallel with the first air diffuser at a position not directly below,
    The first air diffuser is formed such that a plurality of openings are arranged along the axial direction of the member on the lower surface at the position directly below, while a plurality of diffusers having a smaller diameter than the openings are formed. Formed with the cross section in the direction sandwiched so that the pores are not directly under the position and are higher than the opening and lower than the axis of the diffuser member. And
    The second air diffusion member is formed such that a plurality of openings are arranged along the axial direction of the member on the lower surface thereof, and a plurality of air diffusion holes having a smaller diameter than the opening are provided in the opening. An air diffuser characterized in that the air diffuser is formed so as to sandwich the cross section in the direction so as to be disposed along the axial direction at a position higher than the axis of the air diffuser member.
  2.  前記第一散気部材及び第二散気部材は複数配置されたことを特徴とする請求項1に記載の散気装置。 The air diffuser according to claim 1, wherein a plurality of the first air diffuser and the second air diffuser are arranged.
  3.  前記第一散気部材及び第二散気部材はブロアから供された空気を端部から排出させる配管を備え、前記端部は前記開口部に挿入されるように配置されたことを特徴とする請求項1に記載の散気装置。 The first air diffuser and the second air diffuser include a pipe for discharging air supplied from a blower from an end, and the end is arranged to be inserted into the opening. The aeration apparatus according to claim 1.
  4.  前記第一散気部材及び第二散気部材は円筒状に形成されたことを特徴とする請求項1に記載の散気装置。 The air diffuser according to claim 1, wherein the first air diffuser and the second air diffuser are formed in a cylindrical shape.
  5.  前記第一散気部材及び第二散気部材はその径方向断面の形状が矩形に形成されたことを特徴とする請求項1に記載の散気装置。 The air diffuser according to claim 1, wherein the first air diffuser and the second air diffuser are formed in a rectangular shape in a radial cross section.
  6.  前記第一散気部材及び第二散気部材はその径方向断面の形状が逆三角形に形成されたことを特徴とする請求項1に記載の散気装置。 The air diffuser according to claim 1, wherein the first air diffuser and the second air diffuser are formed in an inverted triangle shape in a radial cross section.
  7.  前記第一散気部材及び第二散気部材はその径方向断面の下辺が下に凸の立体に形成されたことを特徴とする請求項1に記載の散気装置。 2. The air diffuser according to claim 1, wherein the first air diffuser and the second air diffuser are formed in a three-dimensional shape in which a lower side of a radial cross section is convex downward.
  8.  前記第一散気部材及び第二散気部材はその径方向断面の下辺が半円形を成すことを特徴とする請求項7に記載の散気装置。 The diffuser according to claim 7, wherein the first diffuser member and the second diffuser member have a semicircular lower side in the radial cross section.
  9.  前記第一散気部材及び第二散気部材はその径方向断面の上辺が三角形である一方で下半部が半円形を成すことを特徴とする請求項8に記載の散気装置。 9. The air diffuser according to claim 8, wherein the first air diffuser and the second air diffuser have a triangular shape at the upper side of the cross section in the radial direction and a semicircular shape at the lower half.
  10.  前記第一散気部材及び第二散気部材はその径方向断面の上辺が釣鐘状である一方で下半部が半円形を成すことを特徴とする請求項8に記載の散気装置。 The air diffuser according to claim 8, wherein the first air diffuser and the second air diffuser have a bell-shaped upper side in a radial cross section, and a lower half of the air diffuser has a semicircular shape.
PCT/JP2012/062146 2011-07-14 2012-05-11 Air diffuser WO2013008522A1 (en)

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