JPH09108548A - Immersion type membrane separator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform cleaning of a membrane module immersed in water held in a bioreaction tank in which activated sludge is floated without being inhibited by activated sludge. SOLUTION: The immersion type membrane separator consists of a bioreaction tank 10 in which a membrane module 12 is immersed, a cleaning tank 16 for cleaning the membrane module and a transfer means 17 for transferring the membrane module between the bioreaction tank and the cleaning tank. Fine particles 22 for cleaning and an ultrasonic vibrator are provided in the inside of the cleaning tank or either of both is provided therein.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method of immersing a membrane module in water of a biological reaction tank in which activated sludge floats, decomposing organic matter in raw water containing organic matter supplied to the biological reaction vessel with the activated sludge, The present invention relates to an immersion type membrane separation device that collects permeated water that permeates a membrane in raw water from the inside of a membrane module.

[0002]

2. Description of the Related Art An air diffusing pipe is laid at the bottom of a biological reaction tank in which a membrane module is immersed to enhance the activity of activated sludge suspended in the premises by air bubbles ejected from the air diffusing pipe. A sludge, undecomposed organic matter, and intermediate metabolites generated during the decomposition process (hereinafter, also collectively referred to as sludge, etc.) are formed into a film by causing an ascending upward flow by contact with the sludge. It has been conventionally practiced to carry out membrane filtration while suppressing adhesion to the surface of the membrane, and to draw permeated water that has permeated through the membrane by pumping from inside the membrane module. In this way, even if membrane filtration is performed while suppressing sludge and the like from adhering to the surface of the membrane, sludge and the like gradually adhere to and accumulate on the surface of the membrane due to continuous operation, and filtration resistance increases. Therefore, the microparticles are suspended in the water of the biological reaction tank, and the air bubbles ejected from the air diffuser fluidize the microparticles in the water, and the sludge that adheres to the membrane surface is peeled off by the impact of the microparticles colliding with the membrane. Alternatively, an ultrasonic vibrating plate is attached to the membrane module, and the vibrating plate gives a slight vibration to the membrane surface to remove sludge and the like adhering to the membrane surface.

[0003]

However, when fine particles are suspended in the biological reaction tank, when the sludge concentration in the tank is increased, when the sludge is pulled out to lower the concentration to make it stationary,
The fine particles are mixed with the sludge and are also discharged and reduced. Therefore, the fine particles must be replenished each time. Further, even if the fine particles discharged together with the sludge are to be recovered for reuse, it is difficult to separate them from the sludge. Furthermore, even if the microparticles are fluidized in the biological reaction tank, a large amount of activated sludge floats in the water in the tank, so the microparticles also collide with the activated sludge, weakening the collision force on the membrane. ,
The number of collisions decreases, and the effect of removing sludge cannot be fully achieved. When the ultrasonic diaphragm is attached to the membrane module, the vibration is absorbed by a large amount of activated sludge suspended in water. Therefore, the vibration is not sufficiently transmitted to the film surface, and the effect of peeling off the arrow sludge cannot be sufficiently exerted. Further, when a plurality of membrane modules are immersed in the biological reaction tank, a plurality of diaphragms corresponding to the respective membrane modules are required, and the structure becomes complicated.

[0004]

The present invention was developed in order to solve the above-mentioned problems. It is a biological reaction tank in which a membrane module is immersed, a cleaning tank for cleaning the membrane module, and an organism. It comprises a moving means for moving the membrane module between the reaction tank and the cleaning tank, and the cleaning small particles and / or the ultrasonic vibrator are provided inside the cleaning tank. .

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION In each of the illustrated embodiments, 10
Is a biological reaction tank in which organic wastewater is supplied as raw water by a pump P1 and a supply pipe 11, and a membrane module 12 having an MF membrane or a UF membrane is immersed in water in the tank in which a large amount of activated sludge floats. In order to aerobically bioprocess organic matter in the raw water with activated sludge at the bottom of the tank, an upward flow of an air lift that rises in contact with the membrane of the membrane module 12 is generated in the raw water in the tank. In order to prevent sludge and the like from adhering to the surface of the membrane due to the shearing force of the bubbles, an air diffuser 13 is installed which blows the air blown from the blower B1 as bubbles. Further, a water sampling pipe 14 connected to a suction pump P2 is connected to the membrane module 12, and the permeated water that has permeated the membrane of the membrane module is sucked by the suction pump to collect water. The biological reaction tank 10 is constructed by digging down the ground in the drawing. Further, the membrane module is installed on a pedestal (not shown) provided on the bottom of the tank and separated from the air diffuser 13 upward. In the figure, two membrane modules are installed, and each membrane module is connected to the water sampling pipe 14 by a branch pipe 15.

A cleaning tank 16 capable of immersing the membrane module is provided on the ground near the biological reaction tank 10, and
A gate-shaped frame 18 that crosses the biological reaction tank 10 and the cleaning tank 16 in series is erected on the ground.
An electric hoist 20 is provided so as to be movable along 9. The gate-shaped frame 18 and the electric hoist 20 constitute a moving means 17 for moving the membrane module 12 between the biological reaction tank 10 and the cleaning tank 16. An air diffuser 21 is also installed at the bottom of the cleaning tank to eject the air blown from the blower B2 as bubbles.

To immerse the membrane module in the biological reaction tank in the cleaning tank, the valve in the middle of the branch pipe 15 connected to the water sampling pipe 14 is closed, and the flange joint below the valve is removed to separate the upper and lower parts of the branch pipe. , Move the electric hoist directly above the membrane module in the biological reaction tank, hang the electric hoist, lower the hanging rope 20 ', connect the hook at the lower end to the membrane module, and wind the rope. While lifting the membrane module, the electric hoist is moved onto the washing tank, the rope is lowered to immerse the membrane module in the washing tank, the hook is removed from the membrane module, and the rope is pulled up. A pedestal (not shown) is also provided in the cleaning tank, and the membrane module is placed on the pedestal and separated from the air diffusing pipe 21. In order to immerse the membrane module in the cleaning tank in the biological reaction tank, the above-described moving operation may be performed in reverse, and the upper and lower sides of the branch pipe 15 may be joined.

In the first embodiment shown in FIG. 1, fine particles 22 having a particle size of 0.5 to 5.0 mm are suspended in the cleaning tank and are caused to flow by the bubbles ejected from the air diffuser 21. The cleaning is performed by cleaning with a chemical solution and rinsing with water. For cleaning, for example, adjust sodium hypochlorite (0.05%) in a cleaning tank,
The pH was adjusted to 12 with caustic soda, and 5 kg of synthetic resin fine particles having an average diameter of 3 mm and a specific gravity of 1.1 were added to the chemical solution. The size of the cleaning tank is 1.5 m in length and 0.5 in width.
m, depth 2.0 m, effective water depth 1.5 m. Then, the fine particles are caused to flow by the bubbles ejected from the air diffuser 21. Then, the contaminated membrane module in the biological reaction tank is immersed in the cleaning tank for several hours. The sludge in the liquid in the cleaning tank is only the fine ones separated from the membrane surface of the membrane module, and the sludge concentration is 1/10 to 1/100 of the sludge concentration in the biological reaction tank in which a large amount of activated sludge floats. Is. Therefore, the fine particles flow in the washing tank without being obstructed by sludge,
Effectively peels sludge and the like that strongly collides with the membrane surface and adheres to the membrane surface.

Then, the cleaning waste liquid in the cleaning tank is discharged to the outside of the tank through a discharge pipe 24 through an opening screen 23 through which fine particles cannot pass. As a result, the exfoliated substances from the film surface are discharged together with water through the screen, and all the fine particles 22 are retained in the tank. Then, the washing tank is filled with water, and the membrane module is washed while flowing the fine particles by the bubbles from the air diffuser 21. When the washing with water is completed, the water in the washing tank is discharged, and the washed membrane module is moved to and immersed in the biological reaction tank. The fine particles remaining in the cleaning tank can be repeatedly used for subsequent cleaning of the membrane module.

The fine particles 22 have an average diameter of 3 m.
When a synthetic resin having a specific gravity of 0.96 and a specific gravity of 0.96 is used, it is buoyant. Therefore, if the diffusing pipe 21 is stopped and left standing after washing, the fine particles float on the surface of the water, and sludge and other debris. Will settle. Therefore, the fine particles can be recovered and repeatedly used without using the screen 23.

In the second embodiment of FIG. 2, an ultrasonic vibrating plate 25 that can be controlled by a frequency controller 26 in the cleaning tank.
1 is installed by immersion, and washing is performed by the synergistic effect of the air lift circulation flow due to the bubbles ejected from the air diffusing pipe 21 and the vibration stirring flow due to the vibrating plate. For cleaning, cleaning with a chemical solution and rinsing with water are performed. To perform the cleaning, for example, sodium hypochlorite (0.05%) is adjusted in a cleaning tank, and the pH is adjusted to 12 with caustic soda. Then, the contaminated membrane module in the biological reaction tank is dipped in the cleaning tank for several hours, during which air bubbles are ejected from the air diffuser 21 and vibration of the diaphragm 25 at a low frequency (10 to 60 Hz) is applied to the liquid. The synergistic effect of the air lift circulation flow due to the air bubbles and the vibrating stirring flow due to the vibrating plate separates adhered substances such as sludge adhering to the membrane surface of the membrane module. The sludge in the liquid in the cleaning tank is only the fine ones separated from the membrane surface of the membrane module, and the sludge concentration is 1/1 of the sludge concentration in the biological reaction tank in which a large amount of activated sludge floats.
It is 0 to 1/100. Therefore, the vibration from the diaphragm is not absorbed by the sludge, and the sludge adhering to the film surface is effectively separated.

Then, the waste cleaning liquid in the cleaning tank is discharged outside the tank together with the separated sludge through the drainage pipe 24, and then the cleaning tank is filled with water, and the membrane module is again rinsed with aeration and vibration to complete the washing with water. After that, the water in the washing tank is discharged, and the membrane module that has been washed with water is moved to and immersed in the biological reaction tank.

In the above-mentioned embodiment, inside the cleaning tank,
The description has been given on the case where either one of the cleaning fine particles and the ultrasonic transducer is provided. However, both the cleaning fine particles and the ultrasonic vibrator may be provided inside the cleaning tank. In this case, the synergistic effect of both can further improve the cleaning effect.

[0014]

As is apparent from the above, according to the present invention, a membrane module having a membrane surface contaminated with sludge or the like is pulled up from a biological reaction tank having a high sludge concentration to reduce the sludge concentration. Since it is immersed in a cleaning tank for cleaning, sludge floating in water does not interfere with chemical cleaning and water cleaning.

That is, when the fine particles are washed by flowing, the flow rate of the air lift circulating flow for flowing the particles is high, so that the particles having a large specific gravity can be uniformly flowed.
Since the particles rarely collide with sludge in the cleaning tank, the number of effective collisions with the film surface increases, and the deposits on the film surface are effectively separated. Further, since it is only necessary to separate the fine particles from the sludge separated by washing, the fine particles can be easily separated and collected, and since the fine particles are not consumed, the usage amount can be small.

In the case of cleaning by ultrasonic vibration, since vibration is not absorbed by sludge, a strong vibration stirring flow can be generated, and vibration is transmitted to the membrane surface, so that sludge and the like that adhere can be effectively separated. Further, it suffices to install only one ultrasonic vibration plate in the cleaning tank.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment.

FIG. 2 is an explanatory diagram of a second embodiment.

[Explanation of symbols]

 10 Bioreaction tank 11 Raw water supply pipe 12 Membrane module 13 Diffuser pipe 14 Water sampling pipe 15 Branch pipe 16 Washing tank 17 Means for moving membrane module 18 Gate frame 19 Upper horizontal beam of gate frame 20 Electric hoist 21 Air diffuser 22 Micro particles 25 Ultrasonic Vibration Plate 25 Ultrasonic Vibration Plate Frequency Controller

Claims (1)

[Claims] 1. A biological reaction tank in which a membrane module is immersed,
A cleaning tank for cleaning the membrane module, and a moving means for moving the membrane module between the biological reaction tank and the cleaning tank, both of the cleaning microparticles and the ultrasonic transducer inside the cleaning tank. Or a submerged membrane separation device, characterized in that either one is provided.