JP5126153B2 - Membrane separation activated sludge treatment equipment - Google Patents

Description

  The present invention relates to a membrane separation activated sludge treatment apparatus, and performs sewage treatment such as domestic wastewater and industrial wastewater.

Conventionally, a water treatment apparatus that performs sewage treatment by a membrane separation activated sludge method has been provided.
In the water treatment by the membrane separation activated sludge method, there are an in-tank installation type in which a biofilm and a separation membrane are arranged in one aeration tank, and an out-of-tank installation type that is arranged in another tank and connected via a pipe. is there.
The in-tank installation type can simplify the water treatment apparatus, but since the separation membrane is arranged in the biofilm tank, there is a problem that the suspended components are likely to adhere to the separation membrane surface and clogging is likely to occur. On the other hand, since the separation type surface can be periodically cleaned with a chemical solution and reversely cleaned, the outside-tank installation type can suppress a decrease in permeation flow rate due to clogging. However, when the suspended components separated from the separation membrane surface by backwashing are refluxed to the biofilm tank, there are problems that the original microparticles are formed and the attached microorganisms are excessive in the biofilm tank. In addition, the piping from the biofilm tank to the separation membrane tank is likely to be clogged, and two tanks are required, resulting in an increase in the size of the water treatment apparatus.
Thus, both the in-tank installation type and the out-of-tank installation type have advantages and disadvantages.

In the outside installation type, Japanese Patent Application Laid-Open No. 2008-86863 (Patent Document 1) passes backwash wastewater containing a membrane surface blocking substance generated by backwashing a separation membrane in a separation membrane tank through an ozone tank. The membrane is clogged with ozone by decomposing it into backwash wastewater and then micronized, treated with activated sludge in a biofilm tank, filtered through a separation membrane tank, and the separation membrane surface is not blocked during the filtration. .
Moreover, in the said installation type in a tank, Unexamined-Japanese-Patent No. 2001-62483 (patent document 2) WHEREIN: A predetermined amount of ozonized air is mixed in the air diffused from the diffuser pipe piping to an aeration tank, and it is in an aeration tank. The required amount of oxygen is supplied to the activated sludge without increasing the amount of aerated air.

In the outside installation type of Patent Document 1, the backwash water is returned to the biofilm tank after passing through the ozone tank, and organic substances in the backwash water returned to the biofilm tank can be miniaturized. The problem of clogging of the separation membrane itself has not been solved, and the clogging of the separation membrane is likely to occur as described above when it is set in the tank.
In particular, in the case of a highly polluted water treatment such as the membrane separation activated sludge method, the viscosity of the treatment liquid is high, and the deposit on the surface of the separation membrane is deposited on the surface of the separation membrane due to sticky deposits peculiar to biological treatment. Dirt (bio-fouling) occurs. Therefore, compared with the filtration of a general drainage system, suspended components are likely to be deposited on the separation membrane, and the permeate flow rate is significantly reduced due to the adhesion and clogging of deposits.
Therefore, filtration devices using membrane modules usually send pressurized air from the diffuser pipe during operation and create a flow of drainage by air bubbling, etc., which causes mechanical loads due to the separation of deposits and the oscillation of the filtration membrane. A cleaning operation (aeration process) is performed to remove deposits caused by the above.
Therefore, in addition to having high filtration performance, the separation membrane is required to have a strength capable of withstanding a mechanical load during long-term operation.
In particular, a separation membrane in which activated sludge adheres to the surface of the separation membrane needs to be sterilized and washed using a chemical solution, and therefore it is desired to have excellent chemical resistance against acids and alkalis.

However, the conventional separation membrane described above uses a porous membrane made of a polyolefin resin such as chlorinated polyethylene or a porous membrane made of a polyvinylidene fluoride (PVDF) resin. There are many cases.
As described above, the separation membranes that have been widely used in the past are mostly polyolefin-based resins, and are made of polypropylene, polyethylene, polystyrene, polyacrylonitrile, cellulose acetate, polysulfone, or the like.
These resins used as conventional separation membranes are not sufficiently resistant to chemicals with respect to cleaning liquids composed of highly concentrated acids and alkalis.

  In addition, as an in-tank installation type of Patent Document 2, when air containing ozone is diffused from a diffuser tube, the amount of dissolved oxygen increases, but the separation membrane needs to be constantly diffused to reduce clogging. If ozone is included in the air, there is a problem that the amount of dissolved oxygen becomes excessive and microorganisms become excessive.

JP 2008-86863 A JP 2001-62483 A

  The present invention has been made in view of the above problems, and as a membrane-separated activated sludge treatment apparatus installed in a tank, it has a simple configuration and reduces the occurrence of clogging in the separation membrane immersed in the tank. The problem is to prevent the microorganisms from growing excessively while maintaining the flow rate.

In order to solve the above problems, the present invention provides:
In the state where the biological treatment unit and the separation membrane treatment unit are communicated with each other through the lower flow path in the aeration tank,
A biological film in which a microorganism is attached to a porous body made of a tetrafluoroethylene resin is disposed in the biological treatment section,
A separation membrane module made of a tetrafluoroethylene resin separation membrane is suspended and immersed in the separation membrane treatment section, and the separation membrane module is a suction filtration type and separates water to be treated from the biological treatment section. And an ozone generator is disposed below the separation membrane module in the separation membrane treatment section, and
An automatic cleaning device is attached to the separation membrane module, and a membrane separation activated sludge treatment device is provided in which the separation membrane is washed with a chemical solution and backwash water.

As described above, in the present invention, the separation membrane activated sludge treatment method installed in the tank is used, but the biological treatment section and the separation membrane treatment are performed by the partition wall in a state where the inside of the aeration tank is communicated via the lower flow path. A part of the activated sludge generated in the biological treatment part is precipitated in the biological treatment part and flows into the separation membrane treatment part through the lower flow passage. Therefore, the amount of activated sludge flowing into the separation membrane treatment unit can be reduced, and the occurrence of clogging of the separation membrane can be reduced. In addition, the biological treatment unit and the separation membrane treatment unit are communicated with each other through the lower flow path without using the piping used outside the tank, so that blockage due to flocs in the piping is prevented and the apparatus is simplified.
In particular, organic substances are decomposed by supplying ozone to the activated sludge (aggregated floc) that separates from the biological treatment section in the aeration tank and flows into the separation membrane treatment section through the lower flow passage and adheres to the surface of the separation membrane. Therefore, the occurrence of clogging on the surface of the separation membrane and in the membrane can be reduced. Furthermore, since the sterilization treatment can be performed on the surface of the separation membrane, a sterilization treatment tank for sterilizing the permeated liquid of the separation membrane can be omitted.
In addition, an ozone generator is installed in the separation membrane treatment section partitioned by the partition wall, and no ozone generator is installed in the biological treatment section, so the amount of dissolved oxygen in the biological treatment section becomes excessive and microorganisms are appropriate. It is possible to prevent the number from becoming excessive.

The ozone generator installed in the liquid in the separation membrane processing unit is surrounded by a shielding frame with upper and lower openings, and the ozone generated from the ozone generator is supplied to the separation membrane of the separation membrane module and directly supplied to the separation membrane. To be.
As a result, ozone can be efficiently supplied to the surface of the separation membrane of the separation membrane module, the floc organic matter adhering to the surface of the separation membrane can be refined by oxidation, and clogging between the separation membrane surface and between the membranes can be reduced. . On the other hand, since ozone is not directly supplied to the biological treatment unit, it is possible to suppress excessive growth of microorganisms.

Further, the present invention is characterized in that the separation membrane is formed of tetrafluoroethylene resin (polytetrafluoroethylene, hereinafter referred to as PTFE). PTFE has chemical resistance, chemical stability, high strength, non-adhesiveness that is easy to slip and does not adhere to suspended components, low friction coefficient, non-flammability, and excellent weather resistance. An acidic liquid can be used as a cleaning liquid. As the PTFE separation membrane, the “Poreflon (registered trademark) membrane” series manufactured by Sumitomo Electric Fine Polymer Co., Ltd. can be suitably used.
As described above, the separation membrane module made of PTFE separation membrane is arranged in the aeration tank of the membrane separation activated sludge treatment apparatus, and the floc adheres to the separation membrane module made of PTFE separation membrane. Even if components accumulate, clogging can be reduced by using a high-concentration alkaline liquid or acidic liquid as a cleaning liquid, and water treatment can be performed while maintaining a high permeation flow rate stably over a long period of time.

The separation membrane made of PTFE is a single layer or a multilayer hollow fiber, and the separation membrane module is a hollow fiber membrane module.
Alternatively, the PTFE separation membrane is a single-layer or multi-layer flat membrane, and the separation membrane module is a flat membrane module.

  Specifically, for example, when a multi-layer hollow fiber made of PTFE is used, the porous multi-layer hollow fiber described in Japanese Patent No. 385186 is preferably used, and a separation membrane in which the hollow fibers are concentrated is used. As the module, the hollow fiber membrane module described in Japanese Patent No. 3077260 and the above Patent No. 385186 is preferably used.

  When the separation membrane is composed of a stretched PTFE porous membrane as described above, it is excellent in strength, durability, and corrosion resistance, and can exhibit extremely usefulness in high turbidity wastewater treatment. Furthermore, since the expanded PTFE porous membrane is manufactured through extrusion and stretching processes, the fine pores can be made to have a high porosity by a high molecular orientation. Therefore, even if a high-performance filter membrane with a large amount of permeated water is used, even if shaking is generated by aeration treatment, the separation membrane does not crack or break, and has excellent durability.

  In particular, as described above, the expanded porous PTFE membrane has chemical stability that is not violated by most chemicals and is excellent in corrosion resistance. In general, a porous film having a large specific surface area is more easily eroded by chemicals than a bulk body and has a low strength. However, an expanded PTFE porous film is an organic / inorganic acid, alkali, oxidizing agent, reducing agent, and organic solvent. It is inert to almost all organic and inorganic chemicals such as, and has excellent chemical resistance. Therefore, cleaning chemicals are not restricted like conventional separation membranes made of polyolefin, polyethylene, etc., and various chemicals are selected according to the type of deposit, and when necessary, the filtration membrane can be used for a long time with a high concentration cleaning liquid. Can be washed. For example, a high-concentration solution of a strong oxidizer such as hydrogen peroxide or hydrochloric acid can be used to completely dissolve and sterilize biofouling, and hypochlorous acid can be used to remove oil in wastewater. A strong alkaline aqueous solution such as a sodium aqueous solution or a sodium hydroxide aqueous solution can be used.

The expanded PTFE separation membrane has, for example, an average pore diameter of 0.01 μm or more on the filtration surface, an average film thickness of 0.1 to 10 mm, a porosity of 40 to 90%, and a tensile strength specified in JIS K 7113 of 10 N. / Mm ² or more is preferable.
The average pore diameter is preferably 0.01 μm or more, the upper limit is 10 μm or less, and more preferably 5.0 μm or less. The average pore diameter is measured by a palm porometer (model number CFP-1200A) manufactured by PMI.
The expanded PTFE separation membrane preferably has a particle trapping rate of 90% or more for particles having a particle diameter of 0.5 μm when the wastewater containing activated sludge or wastewater containing fine particles is used as raw water.
The average film thickness is measured with a dial gauge. The porosity is measured by the method described in ASTM D792.
Furthermore, it is preferable to have resistance to a strong alkaline cleaning solution having a pH of 10 or higher and a strong acidic cleaning solution having a pH of 3 or lower.

The expanded porous PTFE used as a filtration membrane means that PTFE is 80% or more by weight, and more preferably 90% or more.
Examples of the thermoplastic fluororesin used in combination include PFA, FEP, ETFE, PCTFE, PVDF, PVF, etc. Among them, FEP having a relatively low decomposition rate even at a melting point peak of PTFE (327 ° C. or higher) is preferable. Is more preferable.

As described above, the biological treatment unit, a tetrafluoride ethylene resin porous body as a support, these carrier to adhere the microorganisms fixed bed organisms adhering microorganisms to the gap of the surface and the support of the carrier It is a film.
Incidentally, the partial separation membrane unit and for connecting via a lower flow passage, when the fluidized, since there is a risk that the carrier was suspended in the water to be treated flows into the separation membrane treatment unit, the fixed bed biofilm Are preferably used. And if it is set as a fixed-bed type biofilm, oxygen can be accurately supplied with respect to a biofilm from the diffuser pipe piping under it. A flocculant may be added to the biological treatment unit.

Further, as described above, an automatic cleaning device is attached to the separation membrane module, and the separation membrane is cleaned with a chemical solution and backwash water.
It is preferable to use a sodium hypochlorite aqueous solution, a sodium hydroxide aqueous solution, or a mixture thereof as the chemical solution.
In particular, it is preferable to wash by supplying backwash water and the cleaning chemical solution alternately to the separation membrane from an automatic cleaning device.
As described above, PTFE has better chemical resistance than polyolefin, polyethylene, and the like, and therefore, it is cleaned using a cleaning chemical solution composed of a high concentration sodium hypochlorite aqueous solution, sodium hydroxide aqueous solution, or a mixture thereof. be able to. Therefore, it is possible to dissolve the hardly soluble component that adheres and accumulates on the surface of the separation membrane. Furthermore, since the PTFE separation membrane has good surface smoothness and is easy to slide, there is also an advantage that the suspended component (MLSS) adhering to the separation membrane surface can be easily removed by the cleaning liquid.

  Further, in the present invention, the biological treatment unit and the separation membrane treatment unit are merely communicated via the lower flow path, and are partitioned by the partition wall, so that the influence of the chemical solution is not directly given to the biological membrane. In addition, by supplying neutral water as backwash water, neutrality suitable for microorganisms in the biological treatment section can be obtained.

In the aeration tank of the present invention, independent aeration pipes are provided for the biological treatment unit and the separation membrane treatment unit, and the aeration from these aeration tubes is individually controlled.
In this way, by separating the diffuser tube of the biological treatment unit and the diffuser tube of the separation membrane treatment unit, the injection time, the amount of air and the air injection pressure injected from these diffuser tubes are respectively applied to the biological membrane and the separation membrane. It can be controlled to a suitable one. Therefore, in the diffuser tube of the biological treatment unit, for example, while monitoring the activity state of microorganisms in the biofilm with the monitoring means, the diffuser diffuses when oxygen supply is necessary, whereas in the diffuser tube for the separation membrane, the separation membrane In order to prevent clogging of the surface, it is possible to perform aeration at all times.

As described above, in the membrane separation activated sludge treatment apparatus of the present invention, the biological treatment unit and the separation membrane treatment unit are separated by the partition wall in a state where the biological treatment unit and the separation membrane treatment unit are communicated with each other via the lower flow path, and the separation membrane filtration separation unit Then, an ozone generator is installed below the separation membrane module to sterilize floc microorganisms that flow from the biological treatment section and adhere to the surface of the separation membrane to decompose organic matter. Can be further reduced. In addition, the permeated liquid of the separation membrane can be used as a sterilizing liquid.
In addition, by using a PTFE separation membrane that has chemical resistance and high strength as the separation membrane, it is possible to effectively wash the separation membrane that is susceptible to clogging due to suspended components. It can operate stably.
Further, in Patent Document 1, an ozone treatment tank is provided separately from a membrane separation treatment tank and connected via a pipe. However, in the present invention, an ozone generator is disposed in the separation membrane treatment section, so that water treatment is performed. The configuration of the device is simplified.

1 is an overall view of a membrane separation activated sludge treatment apparatus according to a first embodiment of the present invention. The hollow fiber separation membrane module is shown, (A) is a perspective view, (B) is a partially enlarged sectional view. The flat membrane separation membrane module of 2nd embodiment is shown, (A) is a perspective view, (B) is sectional drawing.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 and 2 show a membrane separation activated sludge treatment apparatus according to the first embodiment. The treatment apparatus purifies raw water containing highly turbid suspended components such as sewage and factory effluent.

In the aeration tank 1, the partition wall 2 that divides the interior into two parts is partitioned by opening a lower flow passage 3 between the bottom wall 1 a of the aeration tank 1, the biological treatment unit 4 on one side, and the separation membrane treatment unit on the other side Five.
The biological treatment unit 4 is provided with a fixed bed type biological membrane 6, and the separation membrane treatment unit 5 is provided with a hollow fiber separation membrane module 8 in which hollow fibers 7 made of expanded PTFE porous material are converged.

  In the separation membrane treatment unit 5, a plurality of ozone generators 10 are arranged in parallel below the hollow fiber separation membrane module 8. The ozone generators 10 arranged side by side are surrounded by a holding frame 11 having upper and lower openings, and ozone is directly supplied from the plurality of ozone generators 10 toward all the hollow fibers 7 of the hollow fiber separation membrane module 8. .

  A diffuser pipe 12 is connected to the lower part of the ozone generator 10, and an air supply pipe connected to the diffuser pipe 12 is connected to the blower 13 via a pump P1. Ozone generated from the ozone generator 10 can surely flow into the gap between the hollow fibers 7 by the aeration sprayed from below by the aeration tube 12. The amount of ozone supplied from the ozone generator 10 is an amount that can sterilize microorganisms and oxidatively decompose floc organic matter.

A fixed-bed biofilm 6 is disposed in the biological treatment unit 4. The biofilm 6 uses a porous body made of PTFE as a carrier, and aerobic microorganisms are attached to the surface and pores thereof. Since the carrier made of the PTFE porous material has strength, it is not damaged at the time of aeration and washing, and pores can be easily provided according to the amount of microorganisms to be adhered .
Below the biofilm 6, a biofilm diffuser pipe 14 is diffused toward the biofilm 6, and the diffuser pipe 14 is connected to the blower 13 via a pump P2.
The pump P2 of the diffuser tube 14 for the biofilm and the pump P1 of the diffuser tube 12 for the separation membrane are independently controlled, and the hollow fiber is constantly diffused from the diffuser tube 12 for the separation membrane except during cleaning. 7 is oscillated, while the biofilm diffuser 14 diffuses air when it is necessary to supply oxygen.
A discharge pipe 19 is connected to the bottom wall of the biological treatment section 4 for sucking and discharging the activated sludge that sinks with a pump P6.

The hollow fiber separation membrane module 8 is suspended in the filtrate collecting pipe 16 and disposed in the separation membrane treatment section 5.
As shown in FIG. 2, the hollow fiber separation membrane module 8 folds a large number of expanded PTFE hollow fibers 7 into two U-shapes and arranges them in parallel with a gap therebetween, and seals the upper ends of these hollow fibers 7. It is connected and fixed by a fixing material 24. The sealing and fixing member 24 is provided with a water collecting portion 24a communicating with the hollow portion of each hollow fiber 7, and a water collecting header 25 is fitted and fixed to the water collecting portion 24a. It is connected to the water pipe 16 and suspended in the separation membrane treatment unit 5. On the other hand, the U-shape is held through the support rod 26 at the curved portion at the lower end of each hollow fiber 7. The support rod 26 is held by a holding frame 27.
Thus, in the hollow fiber separation membrane module 8, the lower end of the hollow fiber 7 is not fixed to the sealing fixing material with an interval, so that ozone supplied from the ozone generator 10 piped downward is hollow fiber. 7 is easy to pass through.

  The water collecting pipe 16 is connected to the suction pump P4 and sucks the filtrate that has permeated into the hollow portion of the hollow fiber 7, and the separation membrane of this embodiment is a suction filtration type.

In the present embodiment, the hollow fiber 7 is a porous multilayer hollow fiber. The multilayer hollow fiber has a porous stretched PTFE sheet as a support layer, and a porous stretched PTFE sheet as a filtration layer is tightly wound around the outer peripheral surface of the porous stretched PTFE tube to increase the strength.
The expanded PTFE porous sheet forming the filtration membrane may be obtained by uniaxial stretching or biaxial stretching, but a molded body obtained by extrusion extrusion of PTFE unsintered powder and liquid lubricant is biaxially stretched. It is preferable that the porous sheet obtained by sintering is obtained by sintering. By biaxially stretching, the strength of the fibrous skeleton surrounding the pores can be increased.
Moreover, a laminated body can be easily formed by sintering and integrating a non-sintered PTFE porous membrane with the filtration membrane and the support membrane.

The hollow fiber 7 is not limited to the multilayer hollow fiber but may be a single layer.
The hollow fiber 7 has an average pore diameter of 0.01 μm or more and 10 μm or less on the filtration surface, an average film thickness (a thickness obtained by adding a filtration layer and a support layer in a multilayer) of 0.1 to 10 mm, a porosity of 40 to 90%, The inner diameter is 0.3 to 10 mm, and the IPA bubble point is in the range of 10 to 200 kPa.
Further, the hollow fiber 7 has a tensile strength specified in JIS K 7113 of 10 N / mm ² or more.
Further, the hollow fiber 7 made of PTFE has resistance to a strong alkaline cleaning solution having a pH of 10 or higher and a strong acidic cleaning solution having a pH of 3 or lower.

An automatic cleaning device 30 is attached for cleaning the hollow fiber membrane module 8.
The automatic cleaning device 30 includes a backwash water supply unit 31 that supplies high-pressure water and air to the inside of the hollow fiber 7, and a chemical solution supply unit 32 that supplies a chemical solution to the surface of the hollow fiber 7 by crossflow. ing. As the chemical solution, a mixed solution of a sodium hypochlorite aqueous solution and a sodium hydroxide aqueous solution is used.
The automatic cleaning device 30 includes a control unit 33 connected to a measuring device (not shown) for detecting the internal / external differential pressure of the hollow fiber 7, and the control unit 33 is controlled according to a detection signal from the measuring device. When the differential pressure reaches the threshold value or more, cleaning is started.

  In the water treatment apparatus having the above-described configuration, the water to be treated comprising sewage or factory wastewater introduced into the aeration tank 1 adheres to microorganisms of the fixed bed type biofilm 6 and becomes activated sludge. Suspended components made of activated sludge (floc) that peels off from the biofilm 6 and floats and aggregates in the raw water are sucked down into the lower flow passage 3 because the separation membrane treatment section 5 is a suction filtration type. Part of the biological treatment unit 4 precipitates and flows into the separation membrane treatment unit 5 from the biological treatment unit 4 through the lower flow passage 3.

The water to be treated including floc and inorganic scale that has flowed into the separation membrane treatment unit 5 adheres to the surface of the hollow fiber 7.
Since ozone is supplied to the hollow fiber 7 from the ozone generator 10, flocs adhering to the surface of the hollow fiber 7 are refined by oxidative decomposition of organic matter by ozone, and the surface of the hollow fiber 7 and the distance between the membranes are reduced. Clogging can be reduced. And it is sterilized by ozone with ozone. And since the activated sludge adhering to the hollow fiber 7 is refined and the fines are sterilized, when the treated water containing the activated sludge is returned to the biological treatment unit 4 with a circulation pipe (not shown), It is not necessary to pass an ozone treatment tank like patent document 1.
In addition, since the hollow fiber membrane module 8 is constantly aerated through the separation membrane aeration tube 12, the surface of the hollow fiber 7 can be reduced from being clogged with suspended components.

As described above, the hollow fiber separation membrane module 8 is cleaned by supplying the cleaning liquid from the automatic cleaning device 30 when the internal / external differential pressure reaches the threshold value.
At that time, since the hollow fiber 7 is formed of PTFE in the present invention, the hollow fiber 7 can be washed with a washing liquid composed of a high concentration chemical solution, and the hardly soluble suspended component adhering to the surface of the hollow fiber 7 can be removed and smoothness can be removed. Therefore, suspended components can be removed smoothly with a cleaning solution. And when supplying a chemical | medical solution to the hollow fiber 7, since the separation membrane process part 5 is partitioned off with the biological treatment part 4 by the partition wall 2, the influence of a chemical | medical solution is not directly given to the biological film 6. FIG. And since neutral water is supplied as backwash water, the raw | natural water in the biological treatment part 4 can be hold | maintained in the neutral vicinity (pH 5-8) suitable for microorganisms.
Furthermore, even if the cleaning liquid is sprayed onto the hollow fiber 7 at a high pressure, PTFE has a high strength, so that there is an advantage that the hollow fiber 7 is not damaged or broken.

FIG. 3 shows a second embodiment.
The first embodiment uses a hollow fiber made of PTFE as a hollow fiber membrane separation module. In the second embodiment, a flat membrane type separation membrane module 60 in which flat membrane elements 61 using a flat membrane made of PTFE are converged. The point which is said is different. Since other configurations are the same as those of the first embodiment, description thereof is omitted.

The flat membrane element 61 includes a filtration membrane 62 made of a porous stretched PTFE sheet having a lower end bent and arranged in a U shape, and a support 63 made of a polyethylene resin net between the opposing filtration portions of the filtration membrane 62. A space for the processing liquid flow path is secured.
The filtration membrane 62 is bent in a U shape, and the outer peripheral edge of the opposed counter filtration part is sealed by heat-sealing with a treatment liquid outlet at the upper end to form an outer peripheral sealing part 64. Yes.
A water collecting header 65 connected to the water collecting pipe is fixed to the outer peripheral sealing portion 64 at the treatment liquid outlet.

The expanded PTFE porous membrane used as the filtration membrane 62 may be a single layer or multiple layers.
A hole having a diameter of 0.01 to 20 μm and a particle capturing rate of 90% or more with a particle diameter of 0.45 μm is used. The average film thickness is 5 to 200 μm, and the average maximum length of the fibrous skeleton surrounding the pores is 5 μm or less. The filtration membrane 62 has a tensile strength of 10 N / mm ² or more. And even if it is immersed in each of 3 mass% sulfuric acid, 4 mass% sodium hydroxide aqueous solution, and 10% effective chlorine concentration sodium hypochlorite aqueous solution at a temperature of 50 ° C for 10 days, the amount of permeated water does not decrease and is damaged. It has excellent chemical resistance that is not possible.

Thus, since the constituent material of the flat membrane element 61 is the filtration membrane 62 made of porous expanded PTFE and the support material 63 made of a net, the flat membrane element 61 itself may be flexible so that it can be easily bent. it can. In addition, since the filtration membrane 62 is made of PTFE having strength and plane holding force, it has shape retention while being flexible. The flat membrane element 61 has a very thin overall thickness of 2 mm.
As described above, since the flat membrane element 61 is thin and easily bent, when air is blown out from the diffusion tube for the separation membrane disposed below and bubbles are generated, the filtration membrane 62 is shaken by contact with the bubbles. The occurrence of clogging due to suspended components can be suppressed.

  Even when the separation membrane is a flat membrane as described above, ozone is supplied from the ozone generator to the flat membrane as in the first embodiment, so that floc microorganisms adhering to the flat membrane surface can be sterilized. At the same time, organic substances can be decomposed, clogging can be reduced, and the raw water can be digested stably for a long period of time.

  The membrane separation activated sludge treatment apparatus of the present invention is not limited to the above embodiment, and the configuration of the separation membrane module is not limited to the first and second embodiments.

DESCRIPTION OF SYMBOLS 1 Aeration tank 2 Partition wall 3 Flow path 4 Biological treatment part 5 Separation membrane treatment part 6 Biological membrane 7 Hollow fiber 8 Hollow fiber membrane separation module 10 Ozone generator 12, 14 Aeration pipe 30 Automatic washing apparatus

Claims (5)

In the state where the biological treatment unit and the separation membrane treatment unit are communicated with each other through the lower flow path in the aeration tank,
A biological film in which a microorganism is attached to a porous body made of a tetrafluoroethylene resin is disposed in the biological treatment section,
A separation membrane module made of a tetrafluoroethylene resin separation membrane is suspended and immersed in the separation membrane treatment section, and the separation membrane module is a suction filtration type and separates water to be treated from the biological treatment section. And an ozone generator is disposed below the separation membrane module in the separation membrane treatment section, and
A membrane separation activated sludge treatment apparatus, wherein an automatic washing device is attached to the separation membrane module, and the separation membrane is washed with a chemical solution and backwash water. The separation membrane made of ethylene tetrafluoride resin is a single layer or a multilayer hollow fiber, the separation membrane module is a hollow fiber membrane module,
The membrane separation activated sludge treatment apparatus according to claim 1, wherein the separation membrane made of ethylene tetrafluoride resin is a single-layer or multiple-layer flat membrane, and the separation membrane module is a flat membrane module. The separation membrane has an average pore diameter of 0.01 μm or more, an average film thickness of 10 μm or more, a tensile strength as defined in JIS K 7113 of 10 N / mm ² or more, a resistance to strong alkaline cleaning solutions having a pH of 10 or more and strongly acidic cleaning solutions having a pH of 3 or less. The membrane-separated activated sludge treatment apparatus according to claim 2, which comprises an expanded PTFE porous material having slag. At the time of washing from the automatic washing apparatus, a chemical solution comprising a sodium hypochlorite aqueous solution, a sodium hydroxide aqueous solution, or a mixture thereof is used as a washing solution, and the separation membrane is alternately used with backwash water and the chemical solution by crossflow. The membrane-separated activated sludge treatment apparatus according to any one of claims 1 to 3, wherein the apparatus is supplied to the apparatus. The membrane according to any one of claims 1 to 3 , wherein the biological treatment unit and the separation membrane treatment unit are provided with independent aeration tubes, and the aeration from the aeration tubes is individually controlled. Separation activated sludge treatment equipment.

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