JP4107819B2 - Multi-stage submerged membrane separator - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
TECHNICAL FIELD The present invention relates to a multi-stage submerged membrane separator, and relates to a technology of a submerged membrane separator used for sewage treatment, sludge concentration, and the like.
[0002]
[Prior art]
Conventionally, as shown in FIG. 2, the submerged membrane separation device 1 has a plurality of flat membrane cartridges 3 in a casing 2 with the membrane surfaces in the vertical direction and a constant gap between the membrane surfaces (usually 6 to 10 mm) are arranged, and the diffuser 4 is disposed below them.
[0003]
As shown in FIG. 3, the flat membrane cartridge 3 has filtration membranes 3B disposed on both front and back surfaces of a filter plate 3A having rigidity such as a resin, and the filtration membrane 3B is adhered or welded to the filter plate 3A at the peripheral portion thereof. A permeated water outlet 3D communicating with the permeated water passage 3C formed in the filter plate 3A and between the filter plate 3A and the filter membrane 3B is provided in the filter plate 3A.
[0004]
This submerged membrane separation device 1 is installed in the treatment tank 5 with a necessary number corresponding to the amount of treated water, and in the state where raw water is introduced into the treatment tank 5 and diffused from the diffuser 4, The liquid to be treated is filtered by the flat membrane cartridge 3, and the permeated water that has passed through the filtration membrane is led out of the tank through the tube 6 and the water collection pipe 7.
[0005]
Further, in the submerged membrane separation apparatus 11 as shown in FIG. 4, a plurality of flat membrane cartridges 13 are arranged in the vertical direction inside the membrane case 12 opened up and down, and a constant gap is provided between the membrane surfaces. The membrane case units 14 are configured by arranging them in parallel, and the membrane case units 14 are arranged in two upper and lower stages, and an interval case 15 that forms an open space is provided between the upper and lower membrane case units 14. Thus, the upper and lower membrane case units 14 are covered to prevent air leakage and inflow of liquid in the tank. A diffuser case 17 in which a diffuser 16 is provided is provided below the lower membrane case unit 14, and a circulation opening 17 </ b> A for the liquid to be processed is formed in the diffuser case 17.
[0006]
The upper membrane case 12 and the spacing case 15 are provided with water collecting pipes 19 and 20 that communicate with the permeate outlet 13D of the membrane cartridge 13 via the tube 18, respectively. A permeate discharge pipe 22 having a suction pump 21 is connected to the water collection pipes 19 and 20, and a blower 23 is connected to the air diffuser 16.
[0007]
[Problems to be solved by the invention]
By the way, since only water is removed from the raw water that has passed through the membrane case unit 14, if the membrane case unit 14 is arranged in multiple stages, the sludge concentration increases as the raw water flows to the upper stage, and the filtration resistance increases due to the increase in concentration. Thus, there is a problem of causing a clogging between the flat membrane cartridges 13.
[0008]
Further, the flow rate of the raw water is reduced due to the decrease in the water content, and as a result, the cross flow flow rate of the raw water flowing between the flat membrane cartridges 13 is lowered, and the membrane surface cleaning effect is lowered.
[0009]
The present invention solves the above-described problems, and provides a multi-stage submerged membrane separator that can perform raw filtration smoothly and perform a stable filtering action in each membrane case unit arranged in multiple stages above and below. For the purpose.
[0010]
[Means for Solving the Problems]
In order to solve the above-described problems, the immersion membrane separation apparatus according to the first aspect of the present invention includes a plurality of flat membrane cartridges in a membrane case having upper and lower openings, and a membrane surface between the membrane surfaces in a vertical direction. Membrane case units are configured by arranging them at a certain gap, and a plurality of membrane case units are arranged in multiple stages and immersed in the treatment tank. Between the upper and lower membrane case units, an opening is formed in the surrounding tank interior space. An open space that communicates is formed, and an air diffuser is disposed below the lowermost membrane case unit.
[0011]
With the configuration described above, an upward flow is generated by the air ejected from the diffuser, and the upward flow flows into the lowermost membrane case unit as a solid-gas / liquid mixed phase flow with the surrounding liquid mixture in the tank, The membrane is separated while flowing in the cross flow through the flow path between the flat membrane cartridges. The solid-gas-liquid mixed phase flow that has passed through the lowermost membrane case unit sequentially flows into the upper membrane case units through the open space, and is separated while passing through each membrane case unit.
[0012]
As the liquid mixture in the tank rises in each membrane case unit, the pressure in each film case unit becomes lower than the area in the surrounding tank, and the liquid mixture in the surrounding tank flows into the open space through the opening. For this reason, when the solid-gas-liquid mixed phase flow passes through the open space between the upper and lower membrane case units, the in-tank mixed solution flowing into the open space through the opening newly flows into the upper membrane case unit. .
[0013]
Therefore, the flow rate of the mixed liquid in the tank flowing through each membrane case unit does not fluctuate by supplementing the flow rate decreased by the membrane separation action with the newly flowing in- tank mixed liquid, and the sludge concentration increased in the lower membrane case unit. Can be diluted with the newly introduced in-tank mixture, and the in-tank mixture can be passed through the flow path between the flat membrane cartridges of each membrane case unit at a stable sludge concentration and cross-flow flow rate. It is possible to secure a sufficient film surface cleaning effect and prevent clogging between the films.
[0014]
The submerged membrane separation apparatus of the present invention according to claim 2 is provided with a skirt portion having a predetermined height on the upper edge of the opening.
With this configuration, when the upward flow re-enters the upper membrane case unit, it is possible to suppress the air bubbles from being pushed out by the skirt portion due to a rapid decrease in the flow path cross-sectional area.
[0015]
According to a third aspect of the present invention, there is provided a submerged membrane separation apparatus in which a skirt portion having a predetermined height is provided below a flat membrane cartridge of a membrane case unit.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. Components that perform the same operations as those described above are denoted by the same reference numerals and description thereof is omitted. In FIG. 1, a submerged membrane separation device 11 immersed in a treatment tank 24 vertically places a plurality of plate-like membrane cartridges 13 (thickness: about 6 mm) having rigidity inside each membrane case unit 14 arranged in multiple stages. They are arranged in parallel along the direction and with a certain gap between the film surfaces (usually 6 to 10 mm).
[0017]
Each membrane case unit 14 is connected by an intermediate case portion 25 so as to form an open space 27 communicating with the opening 26 in the surrounding tank space between the upper and lower membrane case units 14. An air diffuser 16 is disposed inside an air diffuser case 17 disposed below the unit 14. A skirt portion 25 a having a predetermined height of 40 mm or more is provided on the upper edge of the opening 26.
[0018]
The upper and lower membrane case units 14 can also be connected by a frame material. In this case, a skirt portion 25a having a predetermined height is formed on the lower end edge of the membrane case unit 14 below the flat membrane cartridge 13 by 40 to 50 mm. It is made of a wide angle material.
[0019]
Hereinafter, the operation of the above-described configuration will be described. Raw water is introduced into the treatment tank 24 for performing biological treatment, diffused through the air diffuser 16, and suction pressure is applied by the suction pump 21.
[0020]
An upward flow is generated by the air ejected from the air diffuser 16, a circulating flow is generated inside the processing tank 24 by this upward flow, and the mixed liquid in the tank containing the activated sludge in the tank is sufficiently stirred and mixed. Efficient activated sludge treatment is performed.
[0021]
This upward flow becomes a solid-gas / liquid mixed phase flow along with the surrounding liquid mixture in the tank and flows into the lowermost membrane case unit 14 while flowing through the flow path between the flat membrane cartridges 13 by cross flow. The membrane is separated. The solid-gas-liquid mixed phase flow that has passed through the lowermost membrane case unit 14 sequentially flows into the upper membrane case units 14 through the open spaces 27 and is separated into membranes while passing through the membrane case units 14.
[0022]
When the solid-gas-liquid mixed phase flow passes through the open space 27 between the upper and lower membrane case units 14, the in-tank mixed solution flowing into the open space through the opening 26 newly flows into the membrane case unit 14. .
[0023]
For this reason, by supplementing the flow rate decreased by the membrane separation action with the newly introduced in-vessel mixture, the flow rate of the in-vessel mixture flowing through each membrane case unit 14 does not fluctuate and increases at the lower membrane case unit 14. The sludge concentration can be diluted with a newly introduced in-tank mixture, and the in-tank mixture can be diluted with a stable sludge concentration and a crossflow flow rate in the flow path between the flat membrane cartridges 13 of each membrane case unit 14. The liquid can be passed through, and a sufficient membrane surface cleaning effect can be secured to prevent clogging between the membranes.
[0024]
Since the skirt portion 25a having a predetermined height is provided on the upper edge of the opening 26, when the upward flow re-enters the upper membrane case unit 14, air bubbles are discharged to the outside due to a sudden decrease in the cross-sectional area of the flow path. Extrusion can be suppressed.
[0025]
【The invention's effect】
As described above, according to the present invention, the solid-gas-liquid mixed phase flow causes the upper membrane to be newly accompanied by the in-tank mixture flowing into the open space through the opening when passing through the open space between the upper and lower membrane case units. Since it flows into the case unit, the flow rate of the mixed liquid in the tank flowing through each membrane case unit does not fluctuate, the sludge concentration in the membrane case unit can be averaged, and the flow path between the flat membrane cartridges of each membrane case unit The liquid mixture in the tank can be passed at a stable sludge concentration and a cross flow rate, and a sufficient membrane surface cleaning effect can be secured to prevent clogging between the membranes. When the upward flow flows back into the upper membrane case unit, it is possible to suppress the bubbles from being pushed out to the outside by the skirt portion.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a multi-stage stacked immersion type membrane separation apparatus according to an embodiment of the present invention.
FIG. 2 is a perspective view of a conventional membrane separation apparatus.
FIG. 3 is a partially broken front view of the flat membrane cartridge of the membrane separation apparatus.
FIG. 4 is a schematic view showing a conventional multi-stage submerged membrane separation apparatus.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 11 Submerged membrane separator 12 Membrane case 13 Flat membrane cartridge 14 Membrane case unit 14a Skirt part 15 Space | interval case 16 Air diffuser 17 Air diffuser case 17A Flow opening 18 Tube 19, 20 Water collecting pipe 21 Suction pump 22 Permeated water outlet pipe 23 Blower 24 Treatment tank 25 Intermediate case part 25a Skirt part 26 Opening part 27 Open space

Claims (3)

A membrane case unit is constructed by arranging a plurality of flat membrane cartridges inside a membrane case opened at the top and bottom with the membrane surface in the vertical direction and a fixed gap between the membrane surfaces. Placed in the treatment tank, forming an open space communicating with the opening in the surrounding tank space between the upper and lower membrane case units, and an air diffuser was placed below the lowermost membrane case unit A multi-stage submerged membrane separator characterized by that. The multistage stacked immersion type membrane separation apparatus according to claim 1, wherein a skirt portion having a predetermined height is provided on an upper edge of the opening. The multi-stage stacked immersion type membrane separation apparatus according to claim 1, wherein a skirt portion having a predetermined height is provided below the flat membrane cartridge of the membrane case unit.

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