JPH091139A - Membrane separator - Google Patents

Abstract

PURPOSE: To provide a membrane separator with which clogging hardly arises and the adjustment of a filtration rate is easy. CONSTITUTION: A permeated liquid header pipe 21 disposed in a membrane module 2 is provided with a riser part 21b of a suitable diameter opened at one end into the atmosphere and is provided with a pressure type level gage 25 for measuring the liquid level in this riser part 21b and a Moineau Pump (R) 22 for taking out the permeated liquid flowing into the permeated liquid header pipe 21. The membrane separator is provided with an inverter controller 26 for controlling the driving of this Moineau Pump (R) 22 in such a manner that the flow rate of the permeated liquid taken out of the header pipe attains the prescribed flow rate meeting the liquid level in the riser part 21b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a membrane separation device used in water purification / sewage treatment.

[0002]

2. Description of the Related Art Conventionally, for example, a membrane separation device has been used for separating suspended substances such as activated sludge and coagulated sludge in a liquid to be treated in the purification and lower drainage treatments.

The membrane separation device is as shown in FIG. 3, in which a submerged membrane module 2 in which a plurality of membrane elements are arranged is provided in a treatment tank 1, and the membrane module 2 is provided with:
A permeate header tube 3 is provided which communicates with the permeate flow paths of a plurality of membrane elements. Reference numeral 4 is a liquid to be treated supply pipe for supplying the liquid to be treated 5 into the treatment tank 1, and 6 is a permeate take-out pipe connected to the permeate header pipe 3.

The submerged membrane module 2 is shown in detail in FIG. 4, and has a flat plate-shaped membrane element 8 vertically arranged in a box-shaped casing 7 having upper and lower openings.
Are arranged at appropriate intervals, and an aeration device 9 for supplying aeration air to the liquid to be treated 5 in the tank is provided below the membrane element 8.

The membrane element 8 comprises a filtration membrane 10 disposed on the surface and a permeate flow channel 1 formed inside the filtration membrane 10.
1 and the permeate flow channel 11 communicates with the above-mentioned permeate header pipe 3 via the permeate pipe 12.

The aeration device 9 is connected to an air supply means such as a blower 13 outside the tank. In such a configuration, while the liquid to be treated 5 is supplied from the liquid to be treated supply pipe 4, a suction pressure is applied to the inside of the permeate flow passage 11 of the membrane element 8 by a suction pump (not shown) or the like through the permeate extraction pipe 6. Or by the natural head of the liquid to be treated 5 in the tank,
A differential pressure is generated inside and outside the filtration membrane 10. Then, the permeated liquid that has permeated through the filtration membrane 10 due to this differential pressure and has flowed into the permeated liquid flow path 11 is taken out through the permeated liquid pipe 12, the permeated liquid header pipe 3, and the permeated liquid take-out pipe 6, and the liquid 5 The suspended matter such as the activated sludge is left inside the treatment tank 1.

[0007]

However, in the conventional membrane separation apparatus, a method of applying suction pressure by the above-mentioned suction pump is often adopted. In this case, the suction pressure of the suction pump is directly applied to the membrane surface. Therefore, the clogging of the pores of the membrane may be accelerated.

Further, when the suction pressure is applied by a suction pump or the like, the pumping capacity is drastically changed when the suction pump is started, and the permeate flow rate passing through the membrane surface is drastically changed accordingly. Occasionally, the membrane was clogged.

On the other hand, it has been difficult to adjust the amount of filtration in the system in which filtration is carried out by the natural head of the liquid to be treated in the tank. Further, in a membrane separation device, generally, the permeate flow rate is often set to a fixed amount for filtration, and in this case, even if the filterability of the liquid to be treated deteriorates, a predetermined permeate flow rate should be maintained. As a result, unreasonable filtration was sometimes performed to accelerate the clogging of the membrane.

The present invention solves the above problems, and an object of the present invention is to provide a membrane separation device in which clogging of the membrane is unlikely to occur and the filtration amount can be easily adjusted.

[0011]

In order to solve the above problems, the membrane separation apparatus of the present invention is provided with an immersion type membrane module having a plurality of membrane elements arranged inside a treatment tank, and the membrane module is provided with: A permeate header pipe communicating with the permeate flow channels of the plurality of membrane elements is provided, and the permeate that permeates the membrane surface of each membrane element and flows into the permeate flow channel is taken out through the permeate header pipe. In the constructed membrane separator, the permeate header pipe is provided with a rising part having an appropriate diameter, one end of which is opened to the atmosphere, and liquid level measuring means for measuring the liquid level in the rising part, and the permeate header. Provided is a permeate extraction means for taking out the permeated liquid that has flowed into the tube, and a control means connected to the liquid level measuring means and the permeate extraction means, and controlling the drive of the permeate extraction means by this control means, The above Those configured to retrieve permeate at a predetermined flow rate corresponding to liquid level in the rising portion, which is measured by the position measuring means.

Further, the membrane separation apparatus of the present invention is provided with a flow rate measuring means for measuring the flow rate of the permeated liquid taken out by the permeated liquid take-out means, and connecting the flow rate measuring means to the control means
The control means controls the drive of the permeate extraction means so that the flow rate of the permeated liquid measured by the flow rate measurement means becomes a predetermined flow rate according to the liquid level in the rising portion measured by the liquid level measurement means. It is configured to do.

Further, in the membrane separation apparatus of the present invention, a plurality of immersion type membrane modules in which a plurality of membrane elements are arranged are provided inside the treatment tank, and each membrane module communicates with the permeate flow path of the plurality of membrane elements. The permeated liquid header pipe is provided, and each permeated liquid header pipe is provided with a rising part of an appropriate diameter with one end open to the atmosphere, and the permeated liquid pipe is provided at the bottom of the permeated liquid header pipe. A permeated liquid take-out pipe to which a pipe is connected is provided, and a permeated liquid take-out pipe is provided with a permeated liquid take-out means for taking out the permeated liquid that has flowed into the permeated liquid header pipe. A liquid level measuring means for measuring the liquid level in the rising portion as a pressure is arranged on the upstream side of the means, and a flow rate measuring means for measuring the flow rate of the permeated liquid taken out by the permeated liquid take-out means is arranged on the downstream side. Then, a control means is provided which is connected to the permeated liquid take-out means, the liquid level measuring means and the flow rate measuring means, and the flow rate of the taken out permeated liquid measured by the flow rate measuring means is measured by the control means. The driving of the permeated liquid take-out means is controlled so that the flow rate becomes a predetermined value according to the liquid level in the rising portion measured by the means.

[0014]

According to the above-described first structure, in the pre-operation state in which the driving of the permeated liquid take-out means is stopped, the permeated liquid that has permeated through the membrane surface is filtered by the natural head of the liquid to be treated in the treatment tank. Flows into the permeate header pipe and into the riser. During operation, the permeated liquid in the permeated liquid header pipe is taken out by the permeated liquid take-out means, and the liquid level in the start-up part decreases, so that the difference between the liquid level in the treatment tank and the liquid level in the start-up part is And the filtration is continuously performed. At this time, the liquid level in the rising portion is measured by the liquid level measuring means, and the permeated liquid in the permeated liquid header pipe is set to a predetermined value depending on the liquid level in the rising portion in the state where the control means controls the permeated liquid extracting means. It is taken out at the flow rate. That is, an increase in the liquid level in the rising part is considered to be an increase in the filtration head and the permeate extraction flow rate is increased, and a decrease in the liquid level in the rising part is considered to be a decrease in the filtration head and an increase in membrane resistance. The permeate removal flow rate is reduced. As a result, fluctuations in the filtration head are suppressed, and sudden clogging of the membrane is prevented.

According to the above-mentioned second structure, the liquid level in the rising portion is measured by the liquid level measuring means, and the flow rate of the permeated liquid taken out by the permeated liquid extracting means is measured by the flow rate measuring means. Based on the liquid level in the rising portion and the permeated liquid flow rate, the permeated liquid take-out means is driven by the control means with an appropriate driving force without delay.

According to the above-mentioned third structure, a plurality of membrane modules are filtered by a set of permeate extraction pipe, permeate extraction means, liquid level measuring means, flow rate measuring means and control means in the same manner as above. Can be performed, and the processing amount can be increased. When the operation is performed with the total amount of treatment being constant, load sharing is automatically performed for each membrane module according to the degree of clogging of the membrane.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. (Embodiment 1) FIG. 1 shows the overall structure of a membrane separation apparatus according to a first embodiment of the present invention. In this membrane separation apparatus, the same operation as that of the conventional one described with reference to FIGS. The same reference numerals are given to the members having, and detailed description thereof will be omitted.

The membrane separation apparatus is provided with an immersion type membrane module 2 in which a plurality of membrane elements are arranged inside a treatment tank 1,
The membrane module 2 is provided with a permeate header tube 21 communicating with the permeate flow channels of a plurality of membrane elements.

The permeate header pipe 21 communicates with the permeate flow passage of each membrane element via the permeate pipe 12, and a horizontal portion 21a to which the permeate pipe 12 is connected and the horizontal portion 21a.
A rising part 21b having an appropriate diameter is provided at one end of a, and one end of the rising part 21b is open to the atmosphere.
Here, the rising portion 21b is composed of a hose.

Then, a permeated liquid take-out pipe 23, which is connected to the lower portion of the permeated liquid header pipe 21 and has a mono pump 22 interposed therebetween.
An electromagnetic flow meter 24 for measuring the flow rate in the permeate extraction pipe 23 is provided downstream of the mohno pump 22 in the permeate extraction pipe 23.

A pressure type level gauge 25 for measuring the liquid level in the rising portion 21b is provided below the permeated liquid header tube 21.
Is provided. Further, an inverter control device 26 including a controller 26a for controlling the drive of the mono pump 22 and a VVVF inverter 26b is provided, and the mono pump 22 and the VVVF inverter 26b are connected by a control line 27, and an electromagnetic flow meter 24 and a pressure are provided. The signal line 2 is provided between the level meter 25 and the controller 26a.
It is connected by 8 and 29.

Accordingly, the controller 26a controls the flow rate data of the permeated liquid in the permeated liquid take-out pipe 23 measured by the electromagnetic flow meter 24 and the liquid level in the rising portion 21b measured by the pressure level meter 25. Data is received through the signal line lines 28 and 29, respectively, and based on the received liquid level data, the drive of the mono pump 22 is inverter-controlled via the VVVF inverter 26b, and the permeated liquid extraction tube 2
The flow rate of the permeated liquid in 3 is adjusted to a predetermined flow rate. However, since the flow rate of the permeate that permeates the membrane becomes too large while the membrane is not clogged, the upper limit of the permeate flow rate was set.

The operation of the above configuration will be described below.
When the liquid to be treated 5 is introduced into the processing tank 1, the liquid to be treated 5
Is filtered in the membrane element by its natural head,
The permeated liquid that has permeated the membrane surface of the membrane element flows through the permeated liquid pipe 12 into the permeated liquid header pipe 3 into the horizontal portion 21a and then to the rising portion 21b.

During the filtering operation, the inverter controller 26
The permeated liquid that has flowed into the permeated liquid header pipe 3 is taken out through the permeated liquid take-out pipe 23 through the permeated liquid outlet pipe 23, whereby the liquid level in the rising portion 21b is lowered and the liquid level in the tank rises. The difference from the liquid level in the raising portion 21b acts as a filtration head, and filtration is continuously performed.

At this time, the liquid level in the rising portion 21b is measured by the pressure level gauge 25, and the liquid level data is sent to the inverter control device 26 through the signal line line 28 and the permeated liquid take-out pipe 23 The flow rate of the permeated liquid is measured by the electromagnetic flow meter 24, and the flow rate data is sent to the inverter controller 26 through the signal line 29. Then, the inverter control device 26 performs inverter control of the drive of the mono pump 22 while feeding back the flow rate data according to the size of the liquid level data.

At this time, since the permeate that has flowed into the permeate header pipe 21 is taken out by the mohno pump 22, the force of the mohno pump 22 does not directly act on the membrane surface of the membrane element and clogging of the membrane is prevented. Unlikely to occur.

Further, since the drive of the mono pump 22 is controlled based on the liquid level in the rising portion 21b, the membrane resistance increases and the flow rate of the permeated liquid passing through the membrane surface decreases, so that the rising portion 21b. When the liquid level in the inside decreases, the flow rate of the permeated liquid taken out also decreases.
Therefore, the liquid level in the rising portion 21b is not further lowered to increase the filtered water head, and abrupt clogging of the membrane due to an increase in driving pressure is prevented.

Further, if the diameter of the rising portion 21b is made sufficiently large, even if the flow rate of the permeated liquid passing through the membrane surface changes rapidly, the fluctuation of the liquid level in the rising portion 21b is small, and the filtration head The change in is small. Therefore, the clogging of the film due to the increase in driving pressure is unlikely to occur.

Further, the liquid level in the processing tank 1 and the rising portion 2
If the liquid level in 1b is substantially constant, the filtration head is also substantially constant, and a constant amount of filtration is performed. Therefore, in the inverter control device 26, the startup unit 21
The filtration amount can be easily adjusted by appropriately setting the relationship between the liquid level in b and the flow rate of the permeated liquid taken out.

Further, since the drive of the mono pump 22 is controlled based on the liquid level in the rising portion 21b, even when the flow rate of the permeated liquid taken out becomes large,
Intake of air from one end of the rising portion 21b open to the atmosphere is prevented. (Embodiment 2) FIG. 2 shows the overall structure of a membrane separation apparatus according to a second embodiment of the present invention. In this membrane separation apparatus, the same operation as that described in Embodiment 1 with reference to FIG. The same reference numerals are given to the members having, and detailed description thereof will be omitted.

The membrane separation apparatus is provided with a plurality of submerged membrane modules 2 inside the treatment tank 1, and each membrane module 2 is permeated to communicate with the permeate flow paths of a plurality of membrane elements constituting the membrane module 2. A liquid header tube 21 is provided.

Then, a permeate pipe 23a is provided so as to be connected to the lower part of each permeate header pipe 21, and each permeate pipe 23a is provided.
Is connected to a permeated liquid extraction pipe 23 having a mohno pump 22 interposed therebetween. Mono pump 2 in the permeate extraction pipe 23
An electromagnetic flow meter 24 for measuring the flow rate of the permeated liquid passing through the permeated liquid take-out pipe 23 is provided on the downstream side of
A pressure gauge 30 for measuring the pressure of the permeate is provided upstream of the pressure gauge 30.

The mono pump 22 and the VVVF inverter 26b are connected by a control line 27, and the electromagnetic flow meter 24, the pressure gauge 30 and a controller 26a are connected by signal line lines 28 and 31, respectively. There is. As a result, the controller 26a uses the permeated liquid flow rate data in the permeated liquid take-out pipe 23 measured by the electromagnetic flow meter 24 and the permeated liquid pressure data in the permeated liquid take-out pipe 23 measured by the pressure gauge 30. Signal line 28,
The liquid level in the rising portion 21b is read based on the received pressure data. Then, based on the obtained liquid level data and flow rate data, the drive of the mono pump 22 is inverter-controlled via the VVVF inverter 26b, and the flow rate of the permeate in the permeate extraction pipe 23 is adjusted to a predetermined flow rate.

The permeated liquid pipe 23a and the permeated liquid take-out pipe 23 are constructed to have a sufficiently large diameter, so that the pressure loss in the middle of the pipeline is reduced and the pressure gauge 3
Accurate pressure data is obtained at 0, and the water heads in each membrane module 2 are made equal.

According to the membrane separation device having the above-mentioned configuration, the above-mentioned operation is performed in the plurality of membrane modules 2 by the set of the permeated liquid take-out pipe 23, the pressure gauge 30, the mohno pump 22, the electromagnetic flow meter 24 and the inverter control device 26. The filtration can be performed as in the example, and the throughput can be increased.

Further, when the total amount of treatment is determined, even when the degree of clogging of the membrane differs for each membrane module 2,
Load sharing is automatically performed according to the degree of clogging. The pressure gauge 30 used in the second embodiment may be provided in place of the pressure gauge 25 of the first embodiment. Conversely, the pressure gauge 30 of the second embodiment may be replaced by the pressure gauge used in the first embodiment. It may be replaced with the level meter 25.

In both the first and second embodiments, the horizontal portion 21a and the rising portion 21b of the permeated liquid header tube 21 are
It may be integrally formed or may be composed of another member. In the case of being composed of another member, as the rising portion 21b, a hose,
A start-up pipe, a water tank, etc. can be used.

As the liquid level measuring means, a pressure type or ultrasonic type level gauge attached to the permeated liquid header pipe 21 or a pressure gauge attached to the permeated liquid take-out pipe 23 in the middle of the conduit can be used.

As the permeated liquid extracting means, a mohno pump,
A centrifugal pump, an air lift pump, etc. can be used.

[0040]

As described above, according to the first aspect of the present invention, since the permeated liquid flowing into the permeated liquid header tube is taken out by the permeated liquid extracting means, the filtration using the natural head is performed. The force of the permeated liquid removal means does not directly act on the membrane surface, and the membrane is unlikely to be clogged.

Further, since the permeated liquid take-out means is controlled based on the liquid level in the riser pipe, the membrane resistance increases and the flow rate of the permeated liquid passing through the membrane surface decreases, so that the liquid level in the riser pipe decreases. The flow rate of the permeated liquid taken out also decreases when the water flow rate decreases, and the liquid level in the riser pipe is not further lowered to increase the filtration head. It can prevent clogging.

If the diameter of the riser tube is made sufficiently large, even if the flow rate of the permeate passing through the membrane surface changes suddenly,
The fluctuation of the liquid level in the riser pipe is small, and the change of the filtration head is slight. Therefore, the clogging of the film due to the increase in driving pressure is unlikely to occur.

Furthermore, if the liquid level in the treatment tank and the liquid level in the riser pipe are substantially constant, the filtration head is also almost constant, and a fixed amount of filtration is performed. The amount of filtration can be easily adjusted by appropriately setting the relationship between the liquid level in the raising pipe and the predetermined flow rate of the taken-out permeated liquid.

Further, since the permeated liquid take-out means is controlled based on the liquid level in the riser pipe, even if the flow rate of the taken-out permeated liquid becomes large, air is supplied from one end of the riser pipe opened to the atmosphere. Never inhale.

According to the second aspect of the present invention, the flow rate of the permeate taken out by the permeate take-out means is also measured by the flow rate measuring means, and the permeate is permeated by the control means based on the liquid level in the rising portion and the permeate flow rate. Since the liquid take-out means is controlled, the permeated liquid take-out means can be driven with an appropriate driving force without delay.

According to the third aspect of the present invention, a plurality of immersion type membrane modules are provided inside the treatment tank, and the plurality of membrane modules are provided as a set of permeate extraction pipe, permeate extraction means and liquid level. Since the measurement means, the flow rate measurement means, and the control means are operated, filtration can be performed in a plurality of membrane modules without complicated control, and the throughput can be increased. Further, if the total amount of processing is constant, even if the degree of clogging of the membrane differs for each membrane module, load sharing is automatically performed according to the degree of clogging.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an overall configuration of a membrane separation device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an overall configuration of a membrane separation device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram showing the overall configuration of a conventional membrane separation device.

FIG. 4 is an explanatory view showing a membrane module provided in a conventional and a membrane separation device of the present invention.

[Explanation of symbols]

 1 Processing Tank 2 Membrane Module 21 Permeate Header Tube 21b Start-up Section 22 MONO Pump 24 Electromagnetic Flowmeter 25 Pressure Type Level Meter 26 Inverter Controller 30 Pressure Meter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Soeda 1-247 Shikitsuhigashi, Naniwa-ku, Osaka-shi, Osaka Kubota Corporation

Claims (3)

[Claims] 1. A submerged membrane module in which a plurality of membrane elements are arranged is provided inside a treatment tank, and a permeate header pipe communicating with a permeate flow path of the plurality of membrane elements is provided in the membrane module. In the membrane separation device configured to take out the permeated liquid that has permeated the membrane surface of each membrane element and has flowed into the permeated liquid channel through the permeated liquid header tube,
The permeate header pipe is provided with a rising part having an appropriate diameter, one end of which is opened to the atmosphere, and liquid level measuring means for measuring the liquid level in the rising part, and the permeate flowing into the permeate header pipe. A permeated liquid take-out means for taking out and a control means connected to the liquid level measuring means and the permeated liquid take-out means are provided, and the drive of the permeated liquid take-out means is controlled by this control means,
A membrane separation device configured to take out the permeated liquid at a predetermined flow rate according to the liquid level in the rising portion measured by the liquid level measuring means. 2. A flow rate measuring means for measuring the flow rate of the permeated liquid taken out by the permeated liquid take-out means is provided, the flow rate measuring means is connected to a control means, and the permeation measured by the flow rate measuring means by the control means. The drive of the permeated liquid take-out means is controlled so that the flow rate of the liquid becomes a predetermined flow rate according to the liquid level in the rising portion measured by the liquid level measuring means. The described membrane separation device. 3. A plurality of immersion type membrane modules in which a plurality of membrane elements are arranged are provided inside a treatment tank, and each membrane module is provided with a permeate header pipe communicating with permeate flow channels of the plurality of membrane elements. , Each permeate header pipe is provided with a rising part with an appropriate diameter, one end of which is open to the atmosphere, and a permeate pipe communicating with the bottom of the permeate header pipe is provided. A pipe is provided, and a permeated liquid take-out pipe is provided with a permeated liquid take-out means for taking out the permeated liquid that has flowed into the permeated liquid header pipe. A liquid level measuring means for measuring the liquid level in the raising portion as a pressure is provided, and a flow rate measuring means for measuring the flow rate of the permeated liquid taken out by the permeated liquid take-out means is provided on the downstream side,
A control means is provided connected to the permeated liquid removal means, the liquid level measurement means, and the flow rate measurement means, and the flow rate of the extracted permeated liquid measured by the flow rate measurement means is determined by the liquid level measurement means. The membrane separation device is configured to control the drive of the permeate extraction means so that a predetermined flow rate is obtained according to the measured liquid level in the rising portion.