JP3807423B2 - Immersion membrane separator - Google Patents

Description

  The present invention relates to a submerged membrane separation apparatus in which the growth of a cake layer or the like on the membrane surface is suppressed, peeled off, or the membrane surface is cleaned by air blown into a stock solution.

As shown in FIG. 7, the submerged membrane separator uses a water head difference based on the water depth in the immersion tank 2 in which the membrane element 1 is immersed, and performs membrane separation with low energy by the suction pump 3 to obtain permeated water. be able to. In such a submerged membrane separation apparatus, for example, as described in JP-A-1-293103, an air outlet 5 of an aeration tube 4 is disposed at a lower portion in the immersion tank 2, and the outlet 5 The bubbles 6 blown out from the liquid rise in the stock solution to generate a water flow in the stock solution to increase the membrane separation efficiency, and the adhesion layer on the membrane surface grows by impact when the rising bubbles come into contact with the membrane surface. Suppress.

  In order to generate bubbles at the lower part of the membrane element, an aeration apparatus is required, and in order to uniformly disperse the bubbles between the membrane elements, it is necessary to aerate from a deep position below the membrane element. For this reason, the depth required to immerse the membrane element is not sufficient, and a dip bath to which the depth required for air bubbles to be uniformly dispersed must be used. However, if the immersion tank is deepened, the capacity of the water tank becomes excessive, resulting in waste and inconvenience that the apparatus is bulky. Moreover, in order to be able to peel the cake layer adhering to the film surface, a large amount of air must be intermittently released. Therefore, a large blower or a compressor is required, and an automatic valve must be provided for stopping, resulting in a large apparatus and a complicated structure. Therefore, the present invention is intended to provide an immersion type membrane separation apparatus that can efficiently suppress the growth of the adhesion layer on the membrane surface with a small amount of air without deepening the immersion tank.

The invention described in claim 1 has been proposed in view of the above, and in an immersion type membrane separation apparatus that performs a separation process by immersing a membrane element in an immersion tank, the air siphon chamber is disposed below the membrane constituting the membrane element. And an air supply pipe connected to the air siphon chamber, and the air accumulated and stored in the air siphon chamber is blown intermittently from the air outlet in an instant, and a lump of bubbles and a film blown from the air outlet Is a submerged membrane separator characterized in that
The invention according to claim 2 is the air chamber according to claim 1, wherein the air siphon chamber includes a first chamber having a liquid inlet at a lower end, a second chamber communicating with the first chamber at an upper end communication port, The second chamber is connected to the lower end communication port and is connected to the third chamber having an air outlet at the upper end. The upper end of the opening edge of the lower end communication port is set at a position higher than the opening position of the liquid inlet. It is a submerged membrane separator characterized by the above.

  According to the present invention, air is intermittently blown out from the air outlet opened below the membrane, and the lump of bubbles rises along the flow path between the membrane elements. It is possible to prevent the blown air from coming into contact with the surface and rising unnecessarily without coming into contact with the film surface. Therefore, the film surface can be efficiently cleaned even with a small amount of air. Moreover, since it blows intermittently, the shear force at the time of contacting a film surface as a lump of bubbles is strong, and the cake layer on the film surface can be strongly peeled even with a small amount of air. In addition, since the bubbles blown out from the blowout outlet are in contact with the membrane surface evenly without being dispersed evenly in the middle of ascending, the membrane element is immersed in a depth necessary for immersion A tank is sufficient, and a shallower water tank than the conventional immersion tank can be used, and an excessive volume immersion apparatus is unnecessary. Therefore, the entire apparatus can be made smaller than before.

  Then, when compressed air is pumped into the first chamber through the air supply pipe, air accumulates in the upper portions of the first chamber and the second chamber, and the liquid level in both chambers descends as the stored air increases, When the liquid level falls below the lower end of the upper partition wall, the accumulated air flows into the third chamber and blows out from the air outlet in an instant. The air is blown out intermittently, and the blown-out air bubbles form a lump and can rise in the flow path between the membrane elements to clean the membrane surface.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a membrane element 12 that is immersed in the immersion tank 11 at a predetermined interval. The membrane element 12 includes a membrane support plate 14 having a permeate chamber 13 formed in the width direction therein, a membrane 15 stretched on both sides of the membrane support plate 14, and left and right edges of the membrane support plate 14. It consists of an attached water collecting pipe 16 and an air siphon chamber 17 provided along the lower edge of the membrane 15. The water collecting tube 16 communicates with the permeated water chamber 13 of the membrane support plate 14 and is connected to the upper end of the water collecting pipe 16. The permeated water is extracted from the permeated water outlet pipe 18.

  The membrane support plate 14 is a plastic molded product such as polypropylene or ABS resin, and two flat plates 19 are arranged substantially in parallel at a predetermined interval, and a barrier that is long in the left-right direction between the two flat plates 19. The flat plate 20 and the barrier 20 are integrated by arranging a plurality of the plates 20 in parallel at predetermined vertical intervals, and the permeated water chamber 13 extending in the left-right direction is surrounded by the flat plates and the upper and lower barriers 20. It is formed in multiple stages, and a small permeate collecting hole 21 is formed in the flat plate 19. Therefore, the upper and lower end surfaces of the membrane support plate 14 are sealed by the barriers 20, the openings of the permeate chamber 13 are opened on the left and right end surfaces, and the permeate water collecting holes 21 are formed in the flat plates 19 on both sides. There are many openings along.

  The basic structure of the air siphon chamber 17 includes a first chamber 23 having a liquid inlet 22 at the lower end, a second chamber 25 communicating with the first chamber 23 through an upper end communication port 24, and the second chamber 25. And a third chamber 28 having an air outlet 27 opened at the upper end communicating with the lower end communication port 26. The upper end of the opening edge of the lower end communication port 26 is set at a position higher than the opening position of the liquid inlet 22. In this embodiment, the air siphon chamber 17 is formed in the same width as the water collecting pipe 16 over the entire width of the lower end edge of the membrane element 12.

  Specifically, as shown in FIG. 2, the first upper partition wall 29 suspended from the lower end surface side of the membrane support plate 14 is parallel to the first upper partition wall 29 with a predetermined interval. A second upper partition wall 30 suspended in the state, and two bowl-shaped bottom members 33 each having a first lower partition wall 31 and a second lower partition wall 32 erected from both side edges of the bottom surface. Each first lower partition wall 31 of the bottom member 33 is inserted into the gap between the first upper partition wall 29 and the second upper partition wall 30 from below, and one of the second lower partition walls 32 is inserted into the first upper wall. The other second lower partition wall 32 is positioned outside the second upper partition wall 30 on the outside of the partition wall 29, a predetermined interval is secured between the partition walls, and the lower end edge of the upper partition wall Is separated from the bottom surface of the bowl-shaped bottom member 33, and the upper end edge of the lower partition wall is also separated from the lower end surface of the membrane support plate 14.

  If comprised in this way, the 1st chamber 23 will be formed between both the 1st lower partition walls 31, and the opening part between both 1st lower partition walls 31 will become the liquid inflow port 22, and one 1st lower partition The space between the wall 31 and the first upper partition wall 29 and between the other first lower partition wall 31 and the second upper partition wall 30 is the second chamber 25, and the first upper partition wall 29 and one of the first partition walls The third chamber 28 is formed between the two lower partition walls 32, and a horizontally long slit-shaped opening between the upper edge of the second lower partition wall 32 and the lower edge of the membrane support plate 14 serves as the air outlet 27. In addition to opening, a third chamber 28 is formed between the second upper partition wall 30 and the other second lower partition wall 32 so that the upper edge of the second lower partition wall 32 and the lower edge of the membrane support plate 14 A horizontally elongated slit-shaped opening in between is opened as an air outlet 27.

  Each second chamber 25 communicates with the upper portion of the first chamber 23 at the upper end communication port 24 formed between the upper end edge of each first lower partition wall 31 and the lower end surface of the support plate 14. The lower portion of the third chamber 28 communicates with the lower end of the second chamber 25 at a lower end communication port 26 formed between the lower end edge of the first upper partition wall 29 and the bottom surface of the bowl-shaped bottom member 33.

  In addition, since the lower end edge of the upper partition wall is separated from the bottom surface of the bowl-shaped bottom member 33, the upper end of the lower end communication port 26 that communicates the lower part of the second chamber 25 and the lower part of the third chamber 28 is formed in a bilateral shape. It is located at a position higher than the liquid inlet 22 formed between the bottom side edges of the bottom member 33.

  Note that the end openings of the first chamber 23, the second chamber 25, and the third chamber 28 are collectively blocked by the blocking wall 34. Then, an air supply pipe 35 is connected to the air supply port opened in the closed wall 34 so that the air supply pipe 35 communicates with the first chamber 23.

  When the membrane element 12 provided with the air siphon chamber 17 having the above-described configuration is immersed in the immersion tank 11 and compressed air is pumped from the air supply pipe 35 to the first chamber 23, as shown in FIG. In addition, air is gradually stored in the upper portions of the first chamber 23 and the second chamber 25. When the amount of the stored air gradually increases, the stock solution in the first chamber 23 is pushed out from the liquid inlet 22 to the outside of the air siphon chamber 17 by the air pressure, and the liquid level in the first chamber 23 gradually falls. Also, the stock solution in the second chamber 25 is pushed down by the air pressure and flows into the third chamber 28, the liquid level in the second chamber 25 gradually falls, and the stock solution in the third chamber 28 flows from the second chamber 25. It is pushed by the undiluted solution and is pushed out of the air siphon chamber 17 from the air outlet 27 by that amount. The liquid level in the first chamber 23 and the liquid level in the second chamber 25 are the same because the first chamber 23 and the second chamber 25 communicate with each other in the stock solution outside the air siphon chamber 17. It is (level).

  When the amount of stored air further increases, the liquid level in the first chamber 23 further decreases, and the liquid level in the second chamber 25 also decreases by the same amount. The liquid levels in the first chamber 23 and the second chamber 25 are further lowered by the continuously supplied air, and finally the liquid level in the second chamber 25 reaches the upper end of the opening edge of the lower end communication port 26. When the liquid level drops and the liquid level falls below the upper end of the opening edge of the lower end communication port 26, the air flows into the third chamber 28 through the lower end communication port 26. The liquid level is higher than the liquid inlet 22. Therefore, even if the liquid level in the first chamber 23 and the second chamber 25 gradually falls as described above, the air in the first chamber 23 is not allowed to flow into the third chamber 28 before the air in the second chamber 25 flows into the third chamber 28. The air does not flow out from the liquid inlet 22.

  When air flows into the third chamber 28 from the second chamber 25 through the lower end communication port 26, this air rises in the third chamber 28 and blows out from the air siphon chamber 17 through the air outlet 27. At this time, when the air rises in the third chamber 28, the rising bubbles lift the stock solution in the third chamber 28 and discharge it from the air outlet 27 together with the bubbles, as in the principle of the bubble pump. Further, when air escapes from the second chamber 25 to the third chamber 28 and this air rises in the third chamber 28 and the pressure of the air in the second chamber 25 decreases, the stock solution is supplied from the liquid inlet 22 to the first chamber. The liquid flows into the first chamber 23 and the liquid level in the first chamber 23 rises. Therefore, the lower end communication port 26 has a pressure relationship in which the air in the second chamber 25 easily flows into the third chamber 28 and accumulates in the first chamber 23 and the second chamber 25 as shown in FIG. The air stored in the air blows out from the air outlet 27 in an instant, and the stock solution flows into the first chamber 23 from the liquid inlet 22. The stock solution also flows into the second chamber 25 from the upper end communication port 24. I will do it.

  When the air accumulated in the air siphon chamber 17 in this way blows out from the air outlet 27 in an instant and becomes bubbles, the bubbles are formed between the membrane elements 12 immersed side by side as shown in FIG. It becomes a lump that fills the flow path and rises along the film surface.

  When the bubble mass rises along the membrane surface, an interface of air and stock solution is generated on the membrane surface, and when this interface rises, a large shearing force is generated on the membrane surface, which is formed on the membrane surface by this shearing force. The cake layer is peeled off. Therefore, the film surface is purified.

  Further, in the present embodiment, since the air outlets 27 are opened across the entire width of the lower portions of the membranes on both sides of each membrane element 12, bubbles of bubbles can be generated uniformly over the entire surface of each membrane 15. . Therefore, the immersion tank 11 may have a depth that allows the membrane element 12 to be immersed, and may be shallower than the conventional aeration immersion tank 11.

  Since compressed air is continuously supplied into the air siphon chamber 17 via the air supply pipe 35, even if the accumulated air is blown out once, the air supplied thereafter is gradually stored, and the second chamber 25 The air is blown out again from the air outlet 27 when the liquid level passes the upper end of the opening edge of the lower end communication port 26. Therefore, air is intermittently blown out from the air outlet 27 of each membrane element 12, and the membrane surface is repeatedly purified by the lump of bubbles that blow out intermittently.

  In the first embodiment described above, two sets of air siphon chambers 17 are provided in the thickness direction of the membrane element below the membrane element 12 and the air outlets 27 are opened over the entire width of the membrane 15. However, the present invention is limited to this. It is not something. For example, as in the second embodiment shown in FIG. 5, one air siphon chamber 17 may be provided at the lower part of the membrane element 12, and the air outlet 27 may be opened in about one half of the membrane.

  This air siphon chamber 17 is provided with an upper partition wall 37 in the middle of the width of the membrane element 12 and one chamber divided into two is a third chamber 28 with an air outlet 27 at the upper end, and the other chamber is further approximately The third chamber 28 side is divided into two by the central lower partition wall 38, the remaining chamber is the first chamber 23, and the liquid inlet 22 is opened at the bottom of the first chamber 23. The first chamber 23 and the second chamber 25 communicate with each other through an upper end communication port 24 formed by stopping the upper end of the lower partition wall 38 in the middle, and the second chamber 25 and the third chamber 28 communicate with the upper partition wall 37. The lower end communication port 26 formed by stopping the lower end is communicated, and the upper end of the opening edge of the lower end communication port 26 is configured to be positioned higher than the opening position of the liquid inlet port 22. An air supply pipe 35 is connected.

  Therefore, when compressed air is pumped into the first chamber 23 via the air supply pipe 35, air accumulates in the upper portions of the first chamber 23 and the second chamber 25, and the liquid level in both chambers decreases with the increase in stored air. When the liquid level in the second chamber 25 falls below the lower end of the upper partition wall 37, the accumulated air flows into the third chamber 28 and blows out from the air outlet 27 instantly. The blown air bubbles rise as a lump and clean the membrane surface.

  In the present embodiment, since the air outlet 27 is about half the width of the membrane element 12, when the air outlet 27 is installed in the immersion tank 11, the air outlet 27 has the first chamber 23 and the second chamber 25 ( In other words, the membrane elements 12 are attached by alternately combining the directions so that the air outlets 27 are directed to the portions where the air outlets 27 are not open. If arranged in this way, even if the air outlet 27 is about half the width of the membrane element 12, the air bubbles blown out from the air outlet 27 of the adjacent membrane element 12 will cover the entire width of each membrane 15. Bubble mass can be brought into contact.

  In the present invention, it is not necessary to provide the air siphon chamber 17 in each membrane element 12 itself, and the air siphon chamber 17 may be positioned below the membrane 15. For example, in another embodiment of the submerged membrane separation apparatus shown in FIG. 6, two sets of air siphon chambers 17 are provided in the lower part of the immersion tank 11 along the longitudinal direction of the immersion tank 11 with a space therebetween. A plurality of membrane elements 12 are arranged above the air siphon chambers 17 at predetermined intervals.

  The air siphon chamber 17 shown in this embodiment has a substantially upward bowl-shaped lower member 42 having a liquid passage opening 39 in the lower portion and fourth and fifth lower partition walls 40 and 41 parallel to the upper portion, and an upper surface. The first chamber 23 is formed between the fourth upper partition wall 43 and the fourth lower partition wall 40 by combining the substantially downward-facing bowl-shaped upper member 45 having the fourth and fifth upper partition walls 43 and 44 in parallel. The second chamber 25 is formed between the fourth lower partition wall 40 and the fifth upper partition wall 44, and the third chamber 28 is formed between the fifth upper partition wall 44 and the fifth lower partition wall 41, The upper end communication port 24 is formed by separating the upper end edge of the fourth lower partition wall 40 from the upper surface of the downward bowl-shaped upper member 45 so that the first chamber 23 and the second chamber 25 communicate with each other at the upper end of each chamber. 5 The lower end communication port 26 is formed by separating the lower end edge of the upper partition wall 44 from the bottom surface of the upward hooked lower member 42 to form the second chamber 25 and the second chamber 25. The chambers 28 communicate with each other at the lower end, the liquid inlet 22 is opened at the lower end of the first chamber 23, the air outlet 27 is opened at the upper end of the third chamber 28, and the upper end of the opening edge of the lower end communicating port 26. Is set at a position higher than the opening position of the liquid inlet 22, and an air supply pipe 35 is connected to the first chamber 23. Further, the air outlets 27 of the two air siphon chambers 17 face each other.

  Therefore, when compressed air is pumped into the first chamber 23 via the air supply pipe 35, air accumulates in the upper portions of the first chamber 23 and the second chamber 25, and the liquid level in both chambers decreases with the increase in stored air. When the liquid level in the second chamber 25 falls below the lower end of the upper partition wall, the accumulated air flows into the third chamber 28 and blows out from the air outlet 27 in an instant. This air blowing is performed intermittently in the same manner as in the above-described embodiment, and the bubbles of the blown air rise as a lump and are formed between the membrane elements 12 when they hit the lower end of the membrane element 12. The inside of the flow path 36 is lifted to clean the membrane surfaces on both sides. The bubbles blown out from the air outlet 27 of the air siphon chamber 17 shown on the right side in FIG. 6 mainly blow out the right half of the membrane surface of the membrane element 12 from the air outlet 27 of the air siphon chamber 17 shown on the left side. The air bubbles mainly clean the left half of the membrane surface of the membrane element 12, and the entire surface of the membrane surface is cleaned by the bubbles blown from both the air outlets 27. Further, the bubbles blown out from the air outlet 27 do not rise to the water surface without contacting the film surface. Therefore, the cake layer on the film surface can be efficiently peeled with a small amount of air.

  Further, in the present embodiment, bubbles are blown out from the left and right air outlets 27 and the flow path 36 between the membrane elements 12 is raised, and as shown by arrows in FIG. The water flow that rises from below the membrane element 12 and passes between the membrane elements 12 falls to the left and right, and a circulating flow that passes between the membrane elements 12 again through the liquid passage opening 39 is generated. Therefore, the filtration efficiency can be further enhanced by the generation of this circulation flow. In order to ensure the circulation flow, it is desirable to erect the rectifying plates 46 on both sides of the membrane element 12.

As a preferred embodiment of the present invention, in the submerged membrane separation apparatus that performs the separation treatment by immersing the membrane element in the immersion tank, the air siphon chamber is provided below the membrane constituting the membrane element, An air supply pipe is connected so that the air accumulated and stored in the air siphon chamber is blown intermittently from the air blowing outlet in an instant, and the lump of bubbles blown out from the air blowing outlet is brought into contact with the film. In the submerged membrane separator and the above-described configuration, the air siphon chamber includes a first chamber having a liquid inlet at a lower end thereof, and a first chamber communicated with the first chamber through an upper end communication port. A second chamber and a third chamber which communicates with the second chamber at the lower end communication port and opens an air outlet at the upper end, and the upper end of the opening edge of the lower end communication port is higher than the opening position of the liquid inlet It is set to Is that submerged membrane separator.

  The present invention is not limited to the above-described embodiments, and various design changes can be made without departing from the present invention described in the claims, and the present invention is not limited to the above-described embodiments. Not too long.

FIG. 5 is a partially broken perspective view of a membrane element in which an air siphon chamber is integrally provided at a lower portion. It is sectional drawing of the air siphon chamber shown in FIG. (A) is a cross-sectional view of an air siphon chamber in a state where air is accumulated in the first chamber and the second chamber, (B) is a cross-sectional view of the air siphon chamber showing a state immediately before air is blown out from the air outlet, (C) FIG. 3 is a cross-sectional view of an air siphon chamber showing a state in which air is blown out from an air outlet. It is sectional drawing of the immersion type membrane separator which shows the state which the bubble which blows out is rising in the flow path between membrane elements. It is a front view of the air siphon chamber which opened the blower outlet of about half of the width | variety of a membrane element. It is sectional drawing of the Example which provided the air siphon chamber in the bottom part of the immersion tank separately from the membrane element. It is sectional drawing of the conventional immersion type membrane separator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Immersion tank 12 Membrane element 14 Membrane support plate 15 Membrane 16 Water collecting pipe 17 Air siphon chamber 22 Liquid inlet 23 First chamber 24 Upper end communication port 25 Second chamber 26 Lower end communication port 27 Air outlet 28 Third chamber 29 First Upper partition wall 30 Second upper partition wall 31 First lower partition wall 32 Second lower partition wall 33 Bowl-shaped bottom member 35 Air supply pipe 36 Channel 37 Upper partition wall 38 Lower partition wall 40 Fourth lower partition wall 41 Fifth The lower partition wall 42 The bowl-shaped lower member 43 The fourth upper partition wall 44 The fifth upper partition wall 45 The bowl-shaped upper member 46 The current plate

Claims (2)

In a submerged membrane separation apparatus that performs a separation process by immersing a membrane element in an immersion tank, an air siphon chamber is provided below the membrane constituting the membrane element, an air supply pipe is connected to the air siphon chamber, and the air siphon chamber Immersion type membrane separation characterized in that air accumulated and stored in air is blown intermittently from an air outlet in an instant, and a mass of bubbles blown out from the air outlet is brought into contact with the membrane. apparatus.   2. The air siphon chamber according to claim 1, wherein the air siphon chamber communicates with a first chamber having a liquid inlet at a lower end, a second chamber communicated with the first chamber through an upper end communication port, and the second chamber with a lower end communication port. And a third chamber having an air outlet at the upper end, wherein the upper end of the opening edge of the lower end communication port is set at a position higher than the opening position of the liquid inlet. Separation device.

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