JPH0975687A - Membrane separator by hollow fiber membrane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily and surely conduct washing to remove sludge etc., by installing a slant inverting device which slants the screen surface of the hollow fiber membrane of each membrane element alternately forward and backward to the perpendicularity. SOLUTION: A slant inverting device is composed of the rail 12 of a tank wall, a dolly 13 equipped with the upper part supporting material 5 of each membrane element 4, a reciprocation device 14 for moving the dolly 13 forward and backward, a bearing 18 which fixed the lower part supporting material 6 of each membrane element 4 rotatably to the tank wall, and stoppers 19a, 19b. The dolly 13 moves forward and backward for a prescribed distance, each membrane element 4 to which the material 6 is fixed by the bearing 18 is brought in a forward slanting state 4a and a backward slanting state 4b in which the element 4 is slanted at a prescribed angle of α of about 15-45 deg. to the perpendicularity. In this way, bubbles ejected from an air diffusing pipe 10 are arranged to collide strongly and alternately with the screen surface 7' of a hollow fiber membrane 7 directed diagonally downward to surely peel off and remove active sludge adhering to the membrane surface, sludge entered the clearance between the membranes, etc., preventing the decrease in the filtrate quantity of the membrane.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hollow fiber membrane separation device using a membrane element having a large number of MF membranes or hollow fiber membranes composed of UF membranes.

[0002]

2. Description of the Related Art In order to make wastewater treatment equipment compact and to obtain highly advanced treated water stably, a large number of support sludges are placed between the upper and lower supports in the water containing the activated sludge in the treatment tank of the activated sludge treatment device. A plurality of membrane elements with a hollow fiber membrane stretched to form a screen surface are arranged vertically in the front-rear direction with a space between the channels, and the air diffuser at the bottom of the tank creates air bubbles on the vertical screen surface of the hollow fiber membrane. Membrane separation devices using hollow fiber membranes have been developed that generate an upward flow of an air lift that contacts and rises, and collects permeated water that has permeated through the membranes of the hollow fiber membranes. This allows
A settling tank for solid-liquid separation of SS from raw water is not required, and the biological concentration in the biological treatment tank can be increased.
It is possible to continuously perform advanced treatment that is stable against fluctuations in the amount of raw water and fluctuations in water quality, and there is no sludge or SS in the raw water flowing into or mixed with the treated water, which facilitates operation management.

[0003]

However, when the operation is continued, various undegraded contaminants containing activated sludge, proteins, lipids, etc. in the tank are formed on the surface of the hollow fiber membrane constituting the vertical screen surface. Since the substance adheres to reduce the membrane area of the hollow fiber membrane, the permeation performance of the membrane is significantly reduced, and at the same time, activated sludge enters into the vertical adjacent gaps of the hollow fiber membranes to block the gaps. The membrane area of the membrane is reduced, and the permeation performance of the membrane is significantly reduced. When the permeation performance of the hollow fiber membrane is reduced in this way, sludge and contaminants attached to the surface of the hollow fiber membrane by washing water containing an acid, an alkaline solution, or a surfactant or a chemical such as an oxidizing agent. However, it is necessary to remove the sludge that closes the adjacent space of the hollow fiber membrane, but this cleaning work requires a membrane element immersed in water to be raised above the surface of the water, which is very troublesome and troublesome. . In addition, the cost of chemicals increases, which increases maintenance costs.

[0004]

The present invention provides activated sludge and
Various contaminants make it difficult to adhere to the surface of the hollow fiber membrane, and make it difficult for the contaminants to enter the adjacent gaps of the hollow fiber membrane, thus eliminating the above-mentioned problems. A plurality of membrane elements, which are used as the screen surface with a number of hollow fiber membranes stretched in between, are arranged in the front-rear direction at flow channel intervals, and the diffuser pipes at the bottom of the tank diffuse the bubbles onto the screen surface of the hollow fiber membranes. In a membrane separation device using a hollow fiber membrane that produces an upward flow of an air lift that contacts and rises, and collects permeated water that has permeated the membrane of the hollow fiber membrane of each membrane element, the screen surface of the hollow fiber membrane of each membrane element It is characterized in that a tilt reversing device for tilting forward and backward with respect to the vertical is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In each of the illustrated embodiments, 1
Is a processing tank of an apparatus for treating activated sludge supplied by an organic waste water as a raw water by a pump P1, a supply pipe 2, and 4 is a water passage in the tank in which the activated sludge is suspended. Figure 4 shows a plurality of membrane elements lined up in a row. Each of the membrane elements has two upper and lower support members 5, 6 and an MF membrane in which the upper and lower ends are fixed to the upper and lower support members and which are arranged in the vertical direction.
It has a large number of hollow fiber membranes 7 composed of F membranes, and the large number of hollow fiber membranes constitutes the screen surface 7 '. The upper support member 5 is a water sampling pipe communicating with the hollow part of the hollow fiber membrane addressed to one, and the water sampling pipe of each membrane element is connected to the header pipe 9 for water sampling via the flexible tube 8 which is expandable and contractible. The permeated water in the raw water in the tank is permeated into the hollow portion of the hollow fiber membrane by the suction action of the suction pump P2 connected to the header pipe 9, and is collected as treated water. At the bottom of the treatment tank, in order to aerobically biologically treat organic matter in the raw water with activated sludge, an upward flow of an air lift that rises in contact with the hollow fiber membrane is generated in the raw water in the tank, and the hollow fiber membrane is generated. A plurality of air diffusers 10 are laid to prevent the sludge from adhering to the surface of the air blower, and the blower B provided in the header pipe 11 for air diffuser connected to the air diffusers blows air from the air diffuser 10 Disperses as bubbles.

Horizontal rails 12 are attached to the upper portions of the left and right side walls of the processing tank so as to face each other, and wheels are mounted on the rails, and a carriage 13 is provided so as to be movable in the front-rear direction. The trolley 13 has a rectangular frame shape, and the left and right ends of the upper support members 5 of the plurality of membrane elements described above are rotatable between the opposite left and right sides of the trolley 13 in the front-rear direction with a predetermined interval. It has been installed.
Then, the carriage is connected to the reciprocating device 14 in the front-rear direction,
It can be moved back and forth along the rail. The reciprocating device 14 is a rope 15 connected to the front end of the truck in the figure.
a and a winch 17 that winds and unwinds a rope 15b connected to the rear end of the bogie through a turning pulley 16, respectively. The winch 17 winds the rope 15a around a drum to advance the bogie. When the rope 15b is unwound from the drum and the bogie is retracted by winding the rope 15b onto the drum, the rope 15a is unwound from the drum.

In the first embodiment shown in FIGS. 1 to 3, the left and right ends of the lower support member 6 of each membrane element can be rotated by bearings 18 below the left and right side walls of the processing tank with a predetermined gap. It is attached to. The distance in the front-rear direction of the lower support member 6 attached by the bearing 18 and the distance in the front-rear direction of the upper support member 5 attached to the left and right sides of the carriage 13 are equal to the flow passage interval 3. And
The carriage 13 moves forward and backward by a predetermined distance, and each of the membrane elements having the lower support member 6 attached to the bearing 18 is moved to about 1 with respect to the vertical direction.
The tilted state 4a is tilted by a predetermined angle α of 5 to 45 ° and the tilted state 4b is tilted. For this reason, it is preferable that the rail 12 is provided with a stopper 19a with which the carriage contacts when the membrane element is in the forward tilted state, and a stopper 19b with which the carriage contacts when the membrane element is in the backward tilted state.

In the first embodiment shown in FIGS. 1 to 3, the trolley 1 on which the rail 12 on the tank wall and the upper support member of each membrane element are attached.
3, a reciprocating device 14 for moving the carriage in the front-rear direction, and a bearing 18 having a lower support member of each membrane element rotatably attached to the tank wall constitute a tilt reversing device 20.

In the second embodiment shown in FIGS. 4 and 5, horizontal lower rails 22 are attached to the lower parts of the left and right side walls of the processing tank so as to face each other, and wheels are placed on the rails to move the lower carriage 23 in the front-rear direction. Provide as much as possible. The trolley 23 also has a rectangular frame shape, and the left and right ends of the lower support members 6 of the plurality of membrane elements are rotatably provided at predetermined intervals in the front-rear direction between the opposite left and right sides. To do. The attachment interval in the front-rear direction of the lower support member is the same as the attachment interval in the front-rear direction of the upper support member, and is equal to the flow passage interval 3. Then, the lower carriage is connected to the second reciprocating movement device 24 in the front-rear direction so that it can be moved back and forth along the rail. The second reciprocating device 24 is also shown in the drawing from a winch 27 that winds and unwinds a rope 25a connected to the front end of the lower carriage and a rope 25b connected to the rear end of the carriage via turning pulleys 26, respectively. The winch 27 unwinds the rope 25a from the drum when winding the rope 25a around the drum to move the carriage forward, and unwinds the rope 25a from the drum when winding the rope 25b around the drum and retracts the carriage. .

Then, the reciprocating device 14 for the carriage 13 to which the upper support member of the membrane element is attached and the second reciprocating device 2 for the lower carriage 23 to which the lower support member of the membrane element is attached.
The second reciprocating moving device 24 moves the lower carriage 23 backward by the same distance when the reciprocating moving device 14 moves the carriage 13 forward a certain distance, and the second when the reciprocating moving device 14 moves the carriage 13 backward by a fixed distance. The reciprocating device 24 is the lower carriage 2.
Try to move 3 forward by the same distance. This allows
The trolley 13 and the lower trolley 23 vertically overlap each other at an intermediate point of the moving distance, but move in a state of passing each other for the other half of the distance,
Each membrane element is placed in a forward tilted state 4a tilted at a predetermined angle α of about 15 to 45 ° with respect to the vertical and a back tilted state 4b. Therefore, the lower rail 22 also has a stopper 29a with which the lower carriage 23 contacts when the membrane element is tilted forward.
In addition, it is preferable to provide a stopper 29b with which the lower carriage comes into contact when the vehicle is tilted backward.

In the second embodiment shown in FIGS. 4 and 5, the upper and lower rails 12 and 22 of the tank, the upper and lower carriages 13 and 23 to which the upper and lower support members of the respective membrane elements are attached, and the upper and lower carriages in the front-rear direction are passed. The reciprocating moving devices 14 and 24 for moving to the above-mentioned structure constitute the tilt reversing device 20.

In both the first and second embodiments, the carriage 1
When 3 and 23 reach the midpoint of the moving distance when advancing and retracting, each membrane element 4 stands upright vertically, and the upper carriage 13
Is lifted. Therefore, the upper rail 12 is shown in FIG.
It is preferable to use a C-shaped cross section as shown in FIG. 5, and when the carriage 13 is lifted, its wheels slide on the lower surface of the upper piece of the rail 12 to prevent the wheels from derailing from the rail. .

When the pumps P1 and P2 and the blower B are driven for operation, the tilt reversing device 20 is operated,
The membrane element 4 is kept in the forward tilted state (or the backward tilted state). As a result, the raw water containing the organic matter supplied through the supply pipe 22 into the treatment tank is biologically treated with the activated sludge suspended in the water inside the tank, and the organic matter is decomposed. The permeated water that permeates the hollow fiber membranes in the raw water contacts the hollow fiber membranes 7 of each membrane element due to the bubbles ejected from the air diffuser 10 and flows upward, and the negative pressure of the suction pump P2 acts. The permeation of the hollow fiber membrane through the membrane flows into the hollow fiber membrane, and the water is sampled through the water sampling pipe 5 and the water sampling header pipe 9.

Further, the membrane element 4 is in a forwardly tilted state (or backwardly tilted state), and obliquely blocks air bubbles which are jetted from the air diffusing tube 10 and float up right above the flow path interval 3. For this reason, the air bubbles violently contact the screen surface of the hollow fiber membrane, which is directed obliquely downward, to remove sludge adhering to the surface and various pollutants generated in the decomposition process of organic substances, and to adjoin the hollow fiber membrane. Remove the sludge that has entered the gap.
Then, the tilt reversing device 20 is operated once a day, or every other day or every few days, to move the membrane element in the forward tilted state (or the back tilted state) to the backward tilted state (or the forward tilted state). ), And the screen surface of the hollow fiber membrane, which had been diagonally upward until then, is diagonally downward, and similarly, sludge is violently peeled and removed by air bubbles. In this way, the two screen surfaces of the hollow fiber membrane can be reliably washed with air bubbles, and the permeation performance of the hollow fiber membrane can be maintained.

In the illustrated embodiment, the upper support member 5 to which the upper end of the hollow fiber membrane is fixed is used as a water sampling tube so that the upper end of the hollow fiber membrane is fixed and the permeated water that has permeated the hollow fiber membrane is sampled. However, depending on the structure of the hollow fiber membrane, a support member for fixing the upper end of the hollow fiber membrane and a sampling pipe for the permeated water that has permeated the hollow fiber membrane may be installed separately. Further, the lower support member 14b for fixing the lower end of the hollow fiber membrane may also be used as a water sampling pipe so that the lower end of the hollow fiber membrane is fixed and the permeated water that has permeated through the hollow fiber membrane is also used. Furthermore, the hollow fiber membranes are not limited to being arranged vertically, but may be arranged horizontally.

According to the angle of forward inclination and the angle of backward inclination α of the membrane element, the distance in the front-rear direction of the flow path interval 3 is appropriately determined, and the bubbles can come into contact with the entire height of the screen surface of the membrane element. To do so.

[0017]

[Example] Width 600 mm, depth 900 mm, depth 120
0mm, in the water in a test tank with an effective capacity of 540
Fractionation characteristic 0.1μm, material is polyethylene, width 486m
A membrane element (Mitsubishi Rayon Co., Ltd., trade name Stella Bore L), in which hollow fiber MF membranes with m, a height of 798 mm, and an effective surface area of 4 m ² were vertically arranged, was installed in the same manner as in the second embodiment. The vertical spacing between the upper and lower rails is 4
At 70 mm, the membrane element was made to tilt forward and backward at an angle of 30 ° to the vertical. An air diffuser was laid on the bottom of the tank so that air could be blown out uniformly from the entire bottom surface.

Activated sludge was introduced into the treatment tank at a sludge concentration of 5000 mg / vertical, and synthetic raw water having a BOD concentration of 1000 mg / vertical using peptone and glucose was passed for 24 hours. After starting the operation, the membrane element was kept in the forward tilted state for the first 20 days. During this period, the maximum amount of permeated liquid that can be sucked from the hollow fiber membrane under a reduced pressure of −0.3 kg / cm ² is 1.43 m ³ / cm for 5 days from the start of operation.
^Although it was ² days, the maximum permeated liquid gradually decreased and became 10
1.03 m ³ / m ² · day after day, 0.8 after 14 days
m ³ / m ² · day, and after 20 days, it became 0.6 m ³ / m ² · day, and activated sludge was deposited and adhered on the screen surface of the hollow fiber membrane facing upward obliquely. After that, the membrane element is converted into the forward tilted state and the backward tilted state once a day, and
The operation was continued for 0 days. As a result, -0.3 kg / cm
^The maximum permeate that can be aspirated under reduced pressure of ² is 0.8
Increases to m ³ / m ² · day, 0.8m even after 10 days
³ / m ² days were transferred. In addition, as a result of observing the membrane surface of the hollow fiber membrane, no situation was observed in which sludge adhered and accumulated on the membrane surface.

[0019]

As is apparent from the above, according to the present invention, by alternately tilting the membrane element with respect to the vertical and tilting forward and backward, the air bubbles ejected from the air diffuser are directed obliquely downward to the screen surface. Alternately and violently, the activated sludge adhering to the membrane surface, the sludge entering the adjacent gaps of the hollow fiber membrane, etc. can be reliably separated and removed, and the reduction of the permeated liquid amount of the membrane can be prevented.

[Brief description of drawings]

FIG. 1 is a vertical sectional side view of a first embodiment of a membrane separation device according to the present invention.

FIG. 2 is a plan view of FIG.

FIG. 3 is a front view of the left half of FIG.

FIG. 4 is a vertical sectional side view of a second embodiment of the membrane separation device according to the present invention.

5 is a front view of the right half of FIG. 4. FIG.

[Explanation of symbols]

 1 Treatment Tank 2 Raw Water Supply Pipe 3 Flow Interval 4 Membrane Element 5 Upper Support Material of Membrane Element 6 Lower Support Material of Membrane Element 7 Hollow Fiber Membrane 7'Hollow Fiber Membrane Screen Surface 8 Flexible Tube 9 Water Collection Header Tube 10 Air diffusion tube 11 Air diffusion header tube 12 Rail 13 Truck 14 Reciprocating device 15 Rope 16 Turning pulley 17 Winch 18 Bearing 19 Stopper 20 Inclination reversing device 22 Lower rail 23 Lower truck 24 Reciprocating device 25 Rope 26 Turning pulley 29 Stopper

Claims (1)

[Claims] 1. A plurality of membrane elements, which form a screen surface by arranging a large number of hollow fiber membranes between two support materials, are arranged in water in a treatment tank in the front-rear direction with a flow path interval, and the bottom portion in the tank is formed. A hollow fiber membrane that collects permeated water that has permeated through the membrane of the hollow fiber membrane of each membrane element by causing the air diffuser's diffuser bubbles to contact the screen surface of the hollow fiber membrane to generate an upward airlift flow. In the membrane separation device according to the above, a tilt reversing device for tilting the screen surface of the hollow fiber membrane of each membrane element forward and backward with respect to the vertical is provided.