JP3667131B2 - Immersion membrane separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a submerged membrane separation apparatus used for solid-liquid separation in sewage wastewater treatment, sludge concentration, and the like.
[0002]
[Prior art]
In sewage wastewater treatment, sludge concentration, etc., for example, a submerged membrane separation apparatus as shown in FIG. 7 is used for solid-liquid separation. This membrane separation device 1 has a flat membrane cartridge 3 arranged in the upper part of a casing 2 and an air diffuser 4 provided in the lower part thereof, and is installed in a treatment tank 5 as shown in FIG. Then, in a state where raw water 6 is continuously introduced and diffused from the diffuser 4, the liquid 7 to be treated in the tank is filtered by the membrane cartridge 3, and the permeated water that has passed through the membrane surface is collected in the tube 8 It is led out of the tank through the water pipe 9 and the permeated water lead-out pipe 10.
[0003]
In such a membrane separation apparatus 1, in order to facilitate maintenance, the membrane cartridge 3 is manufactured to about 500 × 1000 × 6 mm (about 3 kg in a non-water-containing state) that can be taken out one by one, and if necessary, The casing 2 is divided into a membrane case 2A for arranging the membrane cartridges 3 and an air diffuser case 2B for housing the air diffuser 4, and when used for solid-liquid separation of activated sludge, In order to induce a cross flow flow with respect to the membrane surface, 10 to 15 L / min of air is ejected from the diffuser 4 with respect to one membrane cartridge 3. This air also serves as oxygen supply to the activated sludge and membrane surface cleaning.
[0004]
[Problems to be solved by the invention]
With the above air amount, oxygen is insufficient for high-concentration sewage such as industrial effluent (BOD concentration of 500 mg / L or more). Living system wastewater (merged treatment septic tanks, sewage, village wastewater, etc.) becomes excessive in oxygen, and improvements are desired from the viewpoint of saving power.
[0005]
Further, when installed near the wall as in the membrane separation device 1 shown on the right side of FIG. 8, the penetration of the liquid to be treated accompanying the cross flow flow becomes larger from the opposite wall side, and the bubble flow is increased. Since it is biased to the wall side, the film surface cleaning effect may be reduced on the opposite wall side.
[0006]
An object of the present invention is to solve the above problems, and to provide a submerged membrane separation apparatus that can efficiently induce a crossflow flow while reducing the amount of diffused air as much as possible, and that can evenly clean the membrane surface. To do.
[0007]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides a plurality of plate-like membrane cartridges having rigidity inside a membrane case that is open at the top and bottom when constituting a submerged membrane separation apparatus that is immersed in a liquid to be treated. The membrane case unit is configured by arranging the surfaces in a vertical direction with a certain gap between the membrane surfaces, and a plurality of membrane case units are arranged in multiple stages up and down, and an open space is formed between the membrane cases. An interval case is provided, and an air diffuser case having an air diffuser is provided below the lowermost membrane case unit.
[0008]
According to the present invention, in the above-described submerged membrane separation apparatus, the spacing case has a plurality of holes through which tubes connected to the permeate flow paths of the membrane cartridges arranged in the membrane case, and the tubes are watertight in each hole. It is characterized in that a seal ring for holding is provided.
[0009]
In addition, the interval case has a structure integrated with the membrane case.
[0010]
According to the configuration described above, as the gas diffused from the air diffuser rises, an upward flow of the liquid to be treated is generated by the air lift action, and this gas-liquid mixed upward flow is arranged in multiple stages. The liquid to be treated flows into the membrane case sequentially and passes through the gap between the membrane cartridges. During that time, the liquid to be treated is cross-flow filtered on the membrane surface, and the permeated water that permeates the membrane surface and flows into the permeate flow path is the device. Derived outside.
[0011]
That is, the air diffuser arranged at the lowermost stage can induce a cross flow flow across a plurality of membrane case units, can efficiently filter the liquid to be treated, and can reduce the amount of air diffused per membrane cartridge. .
[0012]
At that time, the gas-liquid mixed upward flow once diffuses in the open space of the spacing case, so there is no drift due to misalignment between the upper and lower membrane cartridges, preventing local deposition of the cake layer and inter-membrane clogging due to it. it can.
[0013]
Further, since the apparatus installation area per film cartridge can be reduced, a sufficient gap can be taken around the apparatus to prevent uneven flow, and this can also prevent local deposition of the cake layer and intermembrane clogging caused thereby.
[0014]
When the interval case is provided with a plurality of holes through which the tube passes and a seal ring that keeps the tube watertight, the gas-liquid mixed flow is guided to the upper membrane case without leakage without drawing the liquid to be processed outside the case. This can reliably prevent the occurrence of drift.
[0015]
When the membrane case and the spacing case have an integrated structure, the detachment operation in the processing tank is easy.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0017]
The membrane separation apparatus 11 shown in FIG. 1 includes a plurality of rigid plate-like membrane cartridges 13 (thickness of about 6 mm) in a membrane case 12 that is open at the top and bottom, with the membrane surface set in the vertical direction, Are arranged with a certain gap (usually 6 to 10 mm) to form a membrane case unit 14, and a plurality of membrane case units 14 are arranged vertically in two stages and an open space is formed between the membrane cases 12. An interval case 15 is provided, and an air diffuser case 17 provided with an air diffuser 16 is provided below the lower membrane case unit 14.
[0018]
The membrane cartridge 13 is as shown in FIGS. 2 (a) and 2 (b). A membrane membrane 13B made of polyolefin or the like is arranged on both surfaces of a filter plate 13A having rigidity such as ABS resin, and the membrane cartridge 13 is used. A permeated water outlet 13C that is bonded (or welded) at the peripheral edge and communicates with the permeated water flow path between the filter plate 13A and the filter membrane sheet 13B and inside the filter plate 13A is formed on the filter plate 13A. Yes. The filtration membrane sheet 13B is obtained by integrally forming a filtration membrane on the surface of a base material that is also a spacer.
[0019]
A slit 12A for inserting the peripheral edge of the membrane cartridge 13 is formed on the inner surface of each membrane case 12, and a circulation opening 17A for the liquid to be treated is formed in the diffuser case 17. On the side of the upper membrane case 12 and the spacing case 15, a water collection pipe 19 that communicates with the permeate outlet 13 </ b> C of the membrane cartridge 13 via a tube 18 is provided.
[0020]
As shown in FIGS. 3 to 4, the spacing case 15 is formed with tube insertion holes 20 at the same pitch as the arrangement pitch of the membrane cartridges 13, and each tube insertion hole 20 is sealed with water around the tube 18. An annular rubber packing 21 is provided.
[0021]
Each water collecting pipe 19 communicates with a permeated water outlet pipe 22 leading to a treated water tank (not shown) outside the tank, and a pump device 23 is interposed in the middle of the pipe line. The air diffuser 16 communicates with an air supply source such as a blower 25 or a compressor via an air supply pipe 24.
[0022]
The operation of the above configuration will be described.
[0023]
In the treatment tank 26 for performing biological treatment, the membrane separator 11 is immersed and installed in the activated sludge mixed liquid 27 in the tank, the raw water 28 is continuously introduced, and the activated sludge treatment is performed in a state where the raw air 28 is diffused. At the same time, the activated sludge mixed liquid 27 is filtered by the membrane surface of the membrane cartridge 13 by the suction pressure by the pump device 23, and the permeated water that permeates the membrane surface and flows into the permeated water flow path 13C, the tube 18, The water is led to the treated water tank through the water collecting pipe 19 and the permeate outlet pipe 22. Depending on the quality of the raw water 28, a separate air diffuser (not shown) is also diffused so as not to run out of oxygen.
[0024]
By processing in this way, as the diffused air rises, an upward flow of the activated sludge mixed liquid 12 is generated by the air lift action, and the gas-liquid mixed upward flow is arranged in two stages. Sequentially flows into the unit 14 and passes through the gap between the membrane cartridges 13, and at that time, the activated sludge mixed liquid 27 is cross-flow filtered on the membrane surface of each membrane cartridge 13.
[0025]
That is, the cross-flow flow over the plurality of membrane case units 14 can be caused by the air diffuser 16 at the lower part of the device, and the activated sludge mixed liquid 27 can be efficiently filtered, and the air diffused per membrane cartridge 13 The amount can be reduced.
[0026]
The generation of this gas-liquid mixed upward flow is accompanied by the generation of a circulating flow through the flow opening 17A inside and outside the apparatus, so that the activated sludge mixed liquid 27 is sufficiently stirred and mixed, preventing concentration polarization and filtering efficiency. In addition, the contact rate of activated sludge, oxygen, and pollutants increases and the activated sludge treatment efficiency increases.
[0027]
Further, since the apparatus installation area per sheet cartridge 13 can be reduced, a sufficient gap can be taken around the apparatus to prevent the drift, and the cake layer can be locally deposited and the film can be blocked.
[0028]
Moreover, since the gap case 15 exists, the gas-liquid mixed upward flow once diffuses in the open space and then uniformly flows into the gaps between the upper film cartridges 13, which also causes local deposition of the cake layer. Further, it is possible to prevent the intermembrane blockage. At this time, since the rubber packing 21 is provided in the gap case 15, the gas-liquid mixed flow inside the case can be guided to the upper membrane case 12 without leaking without drawing the activated sludge mixed liquid 27 outside the case. The occurrence of drift in the spacing case 15 can be prevented. Wear of the tube insertion hole 20 by the tube 18 vibrated vigorously by the gas-liquid mixed flow can also be prevented.
[0029]
On the other hand, when the interval case 15 is not provided, the positions of the upper and lower membrane cartridges 13 may be somewhat shifted to cause a step or a gap. When a step is generated, the gas-liquid mixed upward flow that has exited the gap between the lower membrane cartridges 13 cannot smoothly enter the gap between the upper membrane cartridges 13 or a drift occurs, so that high installation accuracy is required. . If there are steps or gaps, as shown schematically in FIG. 5, the gas-liquid mixed upflow flows smoothly at the beginning of operation (1 in the figure), but gradually activated sludge and impurities (hair) And (fibers, etc.) are deposited ((2) (3) in the figure), and eventually the opposing film gap is closed ((4) in the figure).
[0030]
However, during operation of the membrane separator 11 for a long period of time, deposits on the membrane surface gradually accumulate on each membrane cartridge 13 and the permeation flux decreases, and the membrane cartridge 13 is damaged. Etc. need to be done. At that time, the permeated water outlet tube 22 is removed from the water collecting tube 19, and the upper membrane case unit 14, then the spacing case 15 and the lower membrane case unit 14 are integrally taken out of the treatment tank 26, and the membrane cartridge 13 Inspect, repair or replace.
[0031]
FIG. 4 shows the membrane separation device 11 in the second embodiment, and the casing 29 has an integral structure equivalent to the above-described membrane case 12 and the spacing case 15 arranged in this order in the upper and lower sides. The membrane case 12 and the diffuser case 17 described above form an integrated structure equivalent to that arranged in this order. The casings 29 and 30 are formed with slits 29A and 30A for inserting the periphery of the filter plate of the membrane cartridge 13, and through holes 29B and 30B are formed at positions corresponding to the permeated water outlet 13C of the membrane cartridge 13, The tube 18 is provided by fitting into each of the through holes 29B and 30B, and the water collecting pipe 19 is attached to the outer surface. The casing 30 is formed with a flow opening 30A for the liquid to be treated.
[0032]
Even with such a configuration, the same operation and effect as the above-described membrane separation apparatus 11 can be obtained. The casing 29 can be provided with the tube 18 and the water collecting pipe 19 in the same manner as the upper membrane case 12 described above.
[0033]
Furthermore, it is possible to form a casing having an integral structure equivalent to the case in which the spacing case 15 and the membrane case 12 are arranged in this order.
[0034]
The number of stages of the membrane case 12 and the spacing case 15 (or the casings 29 and 30) is not particularly limited. The height of the spacing case 15 is not particularly limited in terms of performance, but if it is too high, it is difficult to attach and detach the membrane cartridge 13, and therefore about 500 mm is appropriate.
[0035]
【The invention's effect】
As described above, according to the submerged membrane separation apparatus of the present invention, the cross-flow flow over a plurality of stages of the cartridge cartridges can be induced by the air diffuser disposed at the lowermost part of the apparatus. Compared with the conventional system in which the membrane separation apparatus with the gas is arranged in parallel, the amount of air diffused for causing the cross flow flow, that is, the operation cost can be reduced. The maintenance of membrane cartridges can be performed in units of membrane cartridge rows as in the prior art.
[0036]
In addition, since the device installation area per film cartridge can be reduced, it is possible to prevent a drift by taking a sufficient gap around the apparatus, and even if a drift occurs, it can be mitigated by an interval case, so that the cake layer is locally deposited. Further, it is possible to prevent the intermembrane blockage.
[0037]
It is possible to reduce the installation area of the treatment tank and the construction cost at the time of installation, and it is easy to apply to existing treatment plants. When this membrane separation apparatus is applied to a deep aeration tank, the oxygen dissolution rate increases, so that the amount of aeration (or supply amount of oxygen-containing gas) can be further reduced.
[0038]
Further, when the permeated water leading tube is inserted into the spacing case, the water tightness is maintained by the seal ring, thereby preventing the occurrence of drift in the apparatus.
[0039]
By making the membrane case and the spacing case into an integrated structure, it is possible to facilitate the detachment work in the treatment tank.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a state in which a membrane separation apparatus according to a first embodiment of the present invention is immersed in a processing tank.
FIG. 2 is an explanatory view showing a configuration of a conventional membrane cartridge arranged in the membrane separation apparatus.
FIG. 3 is a perspective view showing a configuration of a spacing case arranged in the membrane separation apparatus.
FIG. 4 is a longitudinal sectional view showing the configuration of the same spacing case.
FIG. 5 is a schematic diagram for explaining inconveniences that occur when the same spacing case is not arranged.
FIG. 6 is an explanatory view showing a state in which a membrane separation apparatus according to a second embodiment of the present invention is immersed in a treatment tank.
FIG. 7 is a perspective view of a conventional membrane separation apparatus.
FIG. 8 is an explanatory view showing a state in which the membrane separation apparatus is immersed in the treatment tank.
[Explanation of symbols]
11 Membrane separator
12 Membrane case
13 Membrane cartridge
14 Membrane case unit
15 spacing case
16 Air diffuser
17 Aeration case
18 tubes
20 Tube insertion hole
21 Rubber packing
27 Activated sludge mixture
29 Casing

Claims (3)

A submerged membrane separation device that is immersed in the liquid to be treated, and a plurality of rigid plate-like membrane cartridges inside the membrane case that is open at the top and bottom. A membrane case unit is configured by arranging with a gap, and a plurality of membrane case units are arranged in multiple stages up and down, and an interval case is formed to form an open space between the membrane cases. A submerged membrane separation apparatus, characterized in that a diffuser case having a diffuser is provided below. The interval case has a plurality of holes through which tubes connected to the permeate flow paths of the membrane cartridges arranged in the membrane case, and each hole is provided with a seal ring for holding the tubes watertight. Item 4. The submerged membrane separation apparatus according to Item 1. 2. The submerged membrane separator according to claim 1, wherein the spacing case has a structure integrated with the membrane case.

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