JPH0822370B2 - Membrane filtration device - Google Patents

Description

Detailed Description of the Invention

[0001]

The present invention relates to river water, lake water, human waste,
The present invention relates to a membrane filtration device for filtering suspensions contained in raw water such as irrigation water and waste water.

[0002]

2. Description of the Related Art Generally, a membrane called a microfiltration membrane has a pore size of 0.01 to several μm, and a membrane called an ultrafiltration membrane has a molecular weight cutoff of 1000 to 300,000. An external pressure type membrane module requires a filtration pressure of 0.1 kg / cm ² or more, although the filtration pressure required for water permeation during filtration depends on the amount of water permeated through the membrane. Conventionally, this filtration pressure has been obtained by pressing the raw water into the membrane with a pump or by sucking the raw water through the membrane.

FIG . 4 shows a flow chart of a conventional system in which an external pressure type filtration membrane is used and raw water is sent to the filtration membrane by a pressure pump to obtain treated water. Further, in FIG. 5 , an external pressure type filtration membrane is used,
A flow chart of a conventional system for obtaining treated water by sucking raw water through a filtration membrane with a suction pump is shown. In the figure, 30 is a raw water supply pipe, 31 is an external pressure type membrane module, 32 is a treated water outflow pipe, 33 is a pressure pump, and 34 is a suction pump.

Needless to say, in the membrane filtration apparatus equipped with the external pressure type membrane module 31 shown in FIG. 4 , raw water is pressurized by using the pressure pump 33, and in the membrane filtration apparatus equipped with the external pressure type membrane module 31 shown in FIG. The raw water is subjected to membrane filtration using the suction pump 34 to obtain treated water.

In the conventional method of pressurizing or sucking with a pump to filter the raw water, the pump must be operated at all times during the operation of the membrane filtration device, which consumes a large amount of power energy and therefore runs. The cost also increases.

[0006]

DISCLOSURE OF THE INVENTION The present invention provides a membrane filtration device in which an external pressure type membrane module is provided, which consumes less power energy for filtration, and therefore requires less running cost. To do.

[0007]

The above object can be achieved by the development of the membrane filtration device described below. 1) In a membrane filtration device provided with an external pressure type membrane module, a treated water outflow pipe of the external pressure type membrane module provided in the treatment tank and a treated water tank at a position lower than the water level of the treatment tank are connected to each other. And a vacuum pump and a vacuum pipe are connected to the communication pipe to form a siphon device.

2) In a membrane filtration device provided with an external pressure type membrane module, a treated water outflow pipe of the external pressure type membrane module provided in the treatment tank and a treated water tank at a position lower than the water level of the treatment tank. And a vacuum pipe connected to the communication pipe to form a siphon device.

3) In a membrane filtration device in which an external pressure type membrane module is provided, a treated water outflow pipe of the external pressure type membrane module provided in the treatment tank and a treated water tank at a position lower than the water level of the treatment tank. And a vacuum forming tank which are connected to each other by a communication pipe and which are capable of being sealed and which are respectively connected to the communication pipe and the treatment tank, and a water sealing tank which is connected to the vacuum generation tank, and a vacuum. A membrane filtration device characterized in that a siphon device is formed by connecting pipes.

[0010]

In the membrane filtration device of the present invention described in 1) to 3) above, the treated water outflow pipe of the external pressure type membrane module and the treatment.
A vacuum valve or a true
The communication pipe is connected with the vacuum pipe equipped with an air release valve.
Through a vacuum pump, ejector or vacuum forming hand
Connected to the tier to form a siphon device, whereby
Between the treated water outlet pipe of the pressure type membrane module and the treated water tank.
By forming a continuous liquid column, the differential pressure required for membrane filtration is increased by a pump or vacuumed by the vacuum pump.
It is not necessary to operate the pump during filtration because it is obtained by using the siphon action rather than the suction by the device and by utilizing the water level difference between the filtration tank in which the membrane is installed and the treated water tank, and therefore the consumption of power energy for filtration Low and running costs are low.

The type of membrane used for the external pressure type membrane module may be a hollow fiber membrane or a ceramic membrane. The membrane filtration device may be of a type in which the external pressure type membrane module is immersed in an open tank for use or a type in which a membrane is sealed in a closed case, but a type of immersion in an open tank for use is preferable.

[0013]

The function of the membrane filtration of the present invention will be described in the case of the membrane filtration device in which the external pressure type membrane module is immersed in these treatment tanks and the raw water is subjected to membrane filtration by the suction method. In the membrane filtration device, a treated water outflow pipe on the secondary side of the external pressure type membrane module and a treated water tank placed at a position lower than the treatment tank are connected by a communication pipe, and the communication pipe and the vacuum forming means are used. The above
The function of the present invention is to form a siphon as described above and perform membrane filtration by utilizing the water level difference between the treatment tank and the treated water tank.

[0014] The method of operating a service alternative version is a water guide to full capacity the treated water to the communicating tube and start the vacuum forming means are connected by vacuum piping communicating the tube interior and the membrane module in the membrane. The siphon operates when the vacuum valve in the vacuum pipe is closed.

Since the membrane used in the present invention is filtered by utilizing the water level difference, it is preferable that the necessary differential pressure is low, and the differential pressure is about 0.1 to 0.8 kg / cm ² . It is necessary to make a membrane from which treated water can be obtained.

The membrane filtration device of the present invention can also be used for treating wastewater by the activated sludge method, and can be used in place of a settling tank for activated sludge treatment, or can be treated biologically by allowing activated sludge to exist in a treatment tank. Therefore, the efficiency of the activated sludge treatment process (particularly the sludge separation / concentration process) can be improved.

[0017]

EXAMPLES Specific examples of the present invention will be shown below, but the present invention is not limited thereto.

(Example 1) In the case of connecting the treatment tank and the treatment water tank with a treated water outflow pipe and a communication pipe, and using a vacuum pump to degas the vacuum pipe provided in the communication pipe to operate the siphon This will be described with reference to FIG.

In the structure of the membrane filtration apparatus shown in FIG. 1, raw water is supplied to the treatment tank 1 from the bottom of the tank through the raw water supply pipe 2.
Untreated raw water is discharged from the overflow weir 3 above the tank to the outside of the system and circulated. An external pressure type membrane module 5 is provided in the processing tank 1.
Are arranged vertically and are immersed. An air diffuser 9 connected from a blower 11 to an air supply pipe 12 is arranged below the membrane module 5. The treated water outflow pipe 13 of the membrane module 5 is connected to the communication pipe 4. Processing tank 1
A treated water tank 6 having a water level lower than that of the treated tank 1 is disposed adjacent to the treated water tank 1. The treated water flows into the treated water tank 6 through the communication pipe 4 and flows from the overflow weir 14 at the upper part of the tank to the treated water outflow pipe 8. It is taken out. The siphon device 7 is composed of a vacuum pipe 10 and a vacuum pump 16 at the top of the communication pipe 4, one of the vacuum pipes 10 is connected to the vacuum pump 16 via a vacuum valve 15, and the other one is an atmosphere release valve. It communicates with the atmosphere through 17. In the figure, H is the water level of the treatment tank 1 and the treated water tank 6
The difference with the water level of.

The raw water in the treatment tank 1 is full and the overflow weir 3
The raw water is being discharged from the system to the outside of the system, the atmospheric release valve 17 of the vacuum pipe 10 is closed, and the vacuum pump 16 is operated with the vacuum valve 15 opened to suck up the treated water from the treated water tank 6 and connect the communication pipe. 4 (and in the membrane of the membrane module 5) is filled with treated water (only the siphon device 7 in Example 2 and subsequent ones).
When the water is full, the siphon device 7 enters the operating state and the filtration is started. After that, the vacuum valve 15 is closed and the operation of the vacuum pump 16 is stopped.

When filtration is continued for a long time and the filtration resistance of the membrane module 5 rises to reach a stage where the filtration rate has decreased, the blower 11 is operated to supply air bubbles from the air diffuser 9 to the membrane module 5 to produce the membrane. Clean module 5. It is not always necessary to stop the filtration during the cleaning of the membrane module 5. The method of air-cleaning the membrane module 5 with air bubbles from the air diffuser 9 is an example of the cleaning method, and other methods may be used. When the atmosphere release valve 17 of the vacuum pipe 10 is opened, air enters the communication pipe 4 to stop the operation and stop the filtration.

(Embodiment 2) Compared with the structure of the membrane filtration device described in the first embodiment, the structure of the membrane filtration device used in the second embodiment has a vacuum pipe 1 attached to a portion of the communication pipe 4.
One of the 0 branch pipes is connected to the ejector 1 via the vacuum valve 15.
The structure is the same as the structure of the membrane filtration device described in Example 1 except that the structure is connected to No. 8, and its schematic diagram is shown in FIG. In FIG. 2, therefore, the reference numerals of the components other than the ejector
The same sign was used.

The operation of the membrane filtration device of the second embodiment will be described with reference to FIG. Raw water is full in the treatment tank 1, and the raw water is discharged from the overflow weir 3 to the outside of the system. Siphon device 7
Is composed of a vacuum pipe 10 and an ejector 18 at a portion corresponding to the top of the communication pipe 4. One of the vacuum pipes 10 is connected to an ejector 18 via a vacuum valve 15. The atmosphere release valve 17 of the vacuum pipe 10 is closed, and the vacuum valve 1
When the ejector 18 which is operated by the drainage of the raw water is operated in the state where 5 is opened, the treated water is sucked up from the treated water tank 6 and the communication pipe 4 is filled with the treated water. Filtration is started. Then, the vacuum valve 15 is closed and the operation of the ejector 18 is stopped.

In FIG. 2, the ejector 18 is used to discharge the raw water.
Although an example in which the drive water is operated is shown, if there is drive water for operating the ejector 18 separately, it may be used.

The method for cleaning the membrane module 5 is the same as in the case of the first embodiment, in which air is cleaned by air bubbles from the air diffuser 9 at the bottom of the processing tank 1. Of course, other methods may be used. When the atmosphere release valve 17 of the vacuum pipe 10 is opened, air enters the communication pipe 4 to stop the operation and stop the filtration. Compared to the method of the first embodiment, this method requires more time to suck up the treated water into the communication pipe 4 by the ejector 18, but has the advantage of not using any power.

(Embodiment 3) Compared with the structure of the membrane filtration device described in the first and second embodiments, the structure of the membrane filtration device used in the third embodiment is attached to the site of the communicating pipe 4. One of the branch pipes of the vacuum pipe 10 is connected to the processing tank 1 via the vacuum valve 15 by a system (vacuum generation system) including a vacuum generation tank 19 and a water sealing tank 20 which can be sealed, and the vacuum generation tank. The structure is the same as the structure of the membrane filtration device described in Example 1 and Example 2 except for the vacuum generation system that generates a vacuum in 19 and thereby degasses the vacuum pipe 10 to operate the siphon. The flow chart is shown in. In FIG.
Therefore, the reference numerals of the constituent members are the same as those in FIG. 1 except the vacuum generating system.

The operation of the membrane filtration apparatus of the third embodiment will be described with reference to FIG. Raw water is full in the treatment tank 1,
From the state where raw water is discharged from the overflow weir 3 to the outside of the system, the atmosphere opening valve 17 of the vacuum pipe 10 is closed and the vacuum valve 15 is also closed. The vacuum generation tank 19 communicates with the processing tank 1 via a vacuum tank inflow valve 21, and communicates with the water sealing tank 20 via a vacuum tank outflow valve 22. First, the vacuum release valve 23 is opened and the vacuum tank outflow valve 22 is closed. Thus, when the vacuum tank inflow valve 21 is opened, the raw water in the processing tank 1 is used to create the vacuum generation tank 1.
9 becomes full. Vacuum release valve 23 and vacuum chamber inflow valve 2
When 1 is closed, the vacuum generation tank 19 becomes an isolated system and the preparation is completed.

The operation of the membrane filtration device is started by the vacuum generation tank 19
When the vacuum valve 15 in the upper part of the vacuum generating tank 19 is opened and the vacuum tank outflow valve 22 in the lower part of the vacuum generating tank 19 is opened, the raw water in the vacuum generating tank 19 drops into the water sealing tank 20 and the treated water is sucked from the treated water tank 6 to form a communication pipe Fill up the treated water to 4. A siphon is formed, the siphon device 7 is activated, and filtration is started. Then, the vacuum valve 15 is closed, the vacuum tank inflow valve 21 of the vacuum generation tank 19 is opened, the vacuum tank outflow valve 22 is closed, and the vacuum release valve 23 is opened for the next siphon formation.

The method for cleaning the membrane module 5 is the same as in the first and second embodiments. Also siphon device 7
To stop the filtration and finish the filtration, the air release valve 17 may be opened. In the case of this method, since the vacuum pressure generated in the vacuum generation tank 19 needs to be higher than the operating pressure of the siphon device 7, the difference n between the upper surface of the vacuum generation tank 19 and the water level in the water sealing tank 20 in FIG. _{For 0, it} is necessary to maintain the relationship of n ₀ > H between the difference H between the water level in the treatment tank 1 and the water level in the treatment water tank 6.

[0030]

[0031]

[0032]

[0033]

EFFECT OF THE INVENTION By developing the membrane filtration device of the present invention which utilizes the water level difference to generate a filtration pressure,
When treated water can be obtained at a filtration pressure of about 0.8 kg / cm ^2, it is not necessary to keep the pump running during filtration, so the consumption of power energy for filtration is low and therefore the running cost is also low. .

[Brief description of drawings]

FIG. 1 is a schematic view of a membrane filtration device of the present invention that operates a siphon using a vacuum pump.

FIG. 2 is a schematic diagram of the membrane filtration device of the present invention of a system in which a siphon is operated by using an ejector that operates with the flowing energy of raw water.

FIG. 3 is a schematic diagram of a membrane filtration device of the present invention in which a siphon is operated using a vacuum generation device mainly having a vacuum generation tank.

FIG. 4 is an explanatory diagram of a method of performing membrane filtration with a pressure pump.

FIG. 5 is an explanatory view of a method of performing membrane filtration with a suction pump.

[Explanation of symbols]

1 Treatment Tank 2 Raw Water Supply Pipe 3 Overflow Weir 4 Communication Pipe 5 External Pressure Membrane Module 6 Treated Water Tank 7 Siphon Device 8 Treated Water Outflow Pipe 9 Diffuser 10 Vacuum Pipe 11 Blower 12 Air Supply Pipe 13 Treated Water Outflow Pipe 14 Over Flow weir 15 Vacuum valve 16 Vacuum pump 17 Atmosphere release valve 18 Ejector 19 Vacuum generation tank 20 Water sealing tank 21 Vacuum tank inflow valve 22 Vacuum tank outflow valve 23 Vacuum release valve 3 0 Raw water supply pipe 31 External pressure type membrane module 32 External pressure type membrane Module 33 Treated water outflow pipe 34 Pressurizing pump 35 Suction pump

Claims (3)

[Claims] 1. In a membrane filtration device having an external pressure type membrane module, a treated water outlet pipe of the external pressure type membrane module provided in the treatment tank and a treated water tank at a position lower than the water level of the treatment tank. And a vacuum pump and a vacuum pipe are connected to the communication pipe to form a siphon device. 2. In a membrane filtration device in which an external pressure type membrane module is provided, a treated water outflow pipe of the external pressure type membrane module provided in the treatment tank and a treated water tank at a position lower than the water level of the treatment tank. And a vacuum pipe connected to the communication pipe to form a siphon device. 3. A membrane filtration device provided with an external pressure type membrane module, wherein a treated water outflow pipe of the external pressure type membrane module provided in the treatment tank and a treated water tank at a position lower than the water level of the treatment tank. And a vacuum forming tank which are connected to each other by a communication pipe and which are capable of being sealed and which are respectively connected to the communication pipe and the treatment tank, and a water sealing tank which is connected to the vacuum generation tank, and a vacuum. membrane filtration equipment, characterized in that the formation of the siphon device by connecting the pipes.