JPH10165781A - Method and apparatus for washing filter membrane and filter apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the maintenance of a filter membrane to prevent lowering of filtering capacity while enhancing the life of the membrane by providing a constant flow rate valve on the primary upstream side of a restriction orifice uniformly distributing the air or liquid supplied to the filter membrane in order to wash the membrane. SOLUTION: Compressed air supplied by a compressor 3 is regulated in its pressure by an air tank 4 and the air made constant in its flow rate by a constant flow rate valve 6 is uniformly distributed and supplied to the primary side of a filter membrane module 12 through a restriction orifice 5. The restriction orifice 5 is provided on the upstream side of each filter membrane module 12 one by one at every module and the air supplied to the restriction orifice 5 flows through the hole with a predetermined diameter provided to the restriction orifice 5 to uniformize the flow rate of the air supplied to the filter membrane module. Therefore, air bubbling operation excluding the suspended substance accumulated on the filter membrane can be well executed without applying excessive vibration to the filter membrane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter provided for a filtration device for filtering while circulating a stock solution, and for supplying cleaning to each filtration membrane at the time of cleaning such as air bubbling for removing suspended substances accumulated in the filtration membrane. The present invention relates to a filtration membrane cleaning device equipped with a restriction orifice for evenly distributing the flow rates of gas and liquid for use.

[0002]

2. Description of the Related Art In a filtration device for purifying a large quantity of river water, lake water, groundwater, seawater, or the like by using a cross-flow type microfiltration or ultrafiltration device as raw water, a circulating filtration is performed to maintain a filtering ability. In such a conventional filtering apparatus, an air bubbling operation for supplying air to the filtration membrane is periodically performed to remove suspended substances accumulated in the filtration membrane.

FIG. 3 is a diagram showing the configuration of a filtration device provided with a conventional filtration membrane cleaning device. In FIG. 3, a stock solution 9a stored in a stock solution tank 9 is driven by a stock solution circulating pump 10 to be connected to a filtration membrane module comprising a plurality of cross-flow type hollow fiber membranes connected in parallel through a pipe 11. The filtrate 9b supplied to the filtration membrane module 12 and filtered by passing from the outside to the inside of the hollow fiber membrane of the filtration membrane module 12
Flows through the inside of the hollow fiber membrane, is led to the filtrate pipe 13, and is stored in a filtrate tank (not shown).

On the other hand, a part of the undiluted solution 9a supplied to the filtration membrane module 12 flows outside the hollow fiber membrane of the filtration membrane module 12 as a circulating return undiluted solution 9c and is led to the undiluted solution return pipe 14 to be returned to the undiluted solution tank 9 Return to

[0005] Further, in order to eliminate suspended substances accumulated in the filtration membrane of the filtration membrane module 12, a filtration membrane cleaning device for performing air bubbling is provided. A restricting orifice 5 for uniformly distributing the flow rate of the air supplied to the filtration membrane is provided.

[0006] Compressed air supplied by a compressor (not shown) is guided to the pipe 2 through an air tank (not shown), and is passed through the restriction orifice 5 to the filtration membrane module 12.
Is supplied from a pipe 1 connected to the upstream side of the filter membrane, flows outside the hollow fiber membrane of the filtration membrane module 12, vibrates the hollow fiber membrane, and removes suspended substances accumulated on the outer surface of the hollow fiber membrane. To wash the filtration membrane.

The limiting orifices 5 are provided one by one for each of the filtration membrane modules 12, and the air supplied to each of the limiting orifices 5 flows through a hole having a predetermined diameter. As a result, the flow rate of the air supplied to each filtration membrane module 12 is fixed at a predetermined flow rate and uniformed, and the suspension accumulated in the filtration membrane without giving excessive vibration to the filtration membrane of each filtration membrane module 12. The air bubbling operation for removing suspended substances can be favorably performed.

In the air bubbling operation, for example, first, the air is pumped in a state where the stock solution 9a is stretched in the filtration membrane module 12, that is, in the first state where the stock solution 9a is stationary and stays in the filtration membrane module 12. After supplying for 2 seconds, air is further supplied for 60 seconds in the second state in which the stock solution 9a is flowed through the filtration membrane module 12.
Supply for seconds. Then, the above-described series of air bubbling operations is performed once every three days for 120 seconds, and this is periodically repeated.

Then, the stock solution circulating pump is
The recirculating undiluted solution 9c, which is a part of the undiluted solution 9a supplied by the step 10, flows outside the hollow fiber membrane of the filtration membrane module 4, and pushes and discharges the suspended substance peeled off as described above. The recirculated undiluted solution 9c containing the suspended substance is led to the undiluted solution return pipe 14 and stored in the waste liquid tank 15.

[0010]

However, the above-mentioned problem is not solved.
In the prior art, the filter membrane module 12 has excess air.
Flows into the hollow fiber membrane, causing the hollow fiber to break.
There is a possibility that the life of the overcoat may be shortened. Specific about the reason
Will be explained. Put undiluted solution 9a in filtration membrane module 12
In the first state, the secondary pressure of the restriction orifice 5
Is 0.3 [kgf / cm ^TwoG], it is usually used
The restriction orifice 5 has a primary pressure of 0.7 [kgf / cm^TwoG],
The secondary pressure is 0.3 [kgf / cm^TwoG] is the differential pressure between the primary and secondary sides
Is 0.4 [kgf / cm^TwoG] is preferable.
New

On the other hand, in the second state in which the stock solution 9a flows through the filtration membrane module 12, the secondary pressure of the restricting orifice 5 is such that the air is further flowed in the first state. When the secondary pressure in the second state is set to 1.0 [kgf / cm ² G], the primary pressure of the restriction orifice 5 must be set to at least 1.4 [kgf / cm ² G] or more. Therefore, the primary pressure of the restriction orifice 5 is usually 2.0
[Kgf / cm ² G] is used when set to less than the vicinity. In this case, the air compressed to a pressure of 7 to 9 [kgf / cm ² G] by the compressor is 2.0 [kgf / cm ² G] when the flow rate is not so large as to the required design value by the pressure reducing valve. Although it is set to be less than the vicinity, when the state changes from the second state to the first state, the secondary pressure of the restriction orifice 5 becomes 1.0 [kgf /
cm ² G] to 0.3 [kgf / cm ² G], and the primary pressure of the restriction orifice 5 also fluctuates.

However, usually, for convenience of use, a compressor having a relatively large output is installed and the flow rate of the air supplied to the primary side of the restricting orifice 5 tends to be relatively large. Since the secondary pressure of the restriction orifice 5 changes when switching from the second state in which the undiluted solution 9a flows through the filtration membrane module 12 to the first state in which the undiluted solution 9a is stretched in the filtration membrane module 12, There is a risk that the flow rate of the air flowing through the filtration membrane module 12 will increase and the hollow fiber membrane of the filtration membrane module 12 will break, or the life will be shortened even if the hollow fiber membrane does not break.

That is, in the first state in which the undiluted solution 9a is stretched in the filtration membrane module 12, the secondary side of the filtration membrane module 12 is in an open state. The pressure of the air supplied to the primary side is 2 [kg
f / cm ² G], a predetermined load is applied to the secondary side of the filtration membrane module 12 in the second state in which the undiluted solution 9a flows through the filtration membrane module 12, so that the restriction is the same as in the first state. The pressure of the air supplied to the primary side of the orifice 5 is 2
When [kgf / cm ² G] is set, the secondary pressure of the limiting orifice 5 is 1.0 [kgf / cm ² G], and the differential pressure between the primary and secondary sides of the limiting orifice 5 is 1. 0 [kgf / cm ² G]
Becomes

At this time, the pressure difference between the primary side and the secondary side at the restriction orifice 5 is 1.0 [kgf / cm ² G] as an actually measured value.
And the flow rate of the air flowing through the restriction orifice 5 is 1
0.5 [Nm ³ / hr].

Therefore, the differential pressure between the primary side and the secondary side is 0.4
Even when the restriction orifice 5 designed to be [kgf / cm ² G] is used, the first and second
The flow rate of the air flowing through the restriction orifice 5 in the condition (1) greatly exceeds the preferable flow rate of 5 [Nm ³ / hr]. There is a possibility that the filtration performance of the filtration membrane module 12 is degraded due to the occurrence of a hollow fiber breakage of the membrane or the like.

When the pressure of the air supplied to the primary side of the restriction orifice 5 fluctuates using a compressor having a relatively large output, the pressure on the primary side of the restriction orifice 5 increases. There is a possibility that the flow rate of the supplied air is further increased to cause the hollow fiber membrane of the filtration membrane module 12 to break the hollow fiber or to shorten the life even if the hollow fiber membrane is not broken.

The present invention solves the above-mentioned problems, and
The object is to provide a filtration membrane cleaning method and a filtration membrane cleaning apparatus capable of securing the maintenance of the filtration membrane, preventing the filtration performance of the filtration membrane from deteriorating, and improving the life of the filtration membrane. It is intended to provide a filtration device provided with the filter.

[0018]

According to the present invention, there is provided a method for cleaning a filtration membrane, comprising the steps of: cleaning a filtration membrane of a cross-flow type microfiltration or ultrafiltration apparatus which performs filtration while circulating a stock solution; In the filtration membrane cleaning method, the flow rate of the gas or liquid supplied to the primary side of the restriction orifice for uniformly distributing the gas or liquid supplied to the filtration membrane for cleaning the filtration membrane is reduced. Features.

According to the filtration membrane cleaning method, the flow rate of the gas or liquid supplied to the primary side of the restriction orifice for uniformly distributing the gas or liquid supplied to the filtration membrane for cleaning the filtration membrane is determined. By increasing the flow rate, the flow rate of the gas or liquid supplied to the filtration membrane becomes constant even if the pressure on the primary side or the secondary side of the restricting orifice fluctuates, and the maintenance of the filtration membrane can be ensured.

Further, the filtration membrane cleaning apparatus according to the present invention is a cross-flow type microfiltration apparatus for performing filtration while circulating a stock solution or a filtration membrane cleaning apparatus for cleaning a filtration membrane of an ultrafiltration apparatus. A constant flow valve is provided upstream of the primary side of the restriction orifice for uniformly distributing the gas or liquid supplied to the filtration membrane for the purpose of maintaining the flow rate of the gas or liquid supplied to the primary side of the restriction orifice. It is characterized by having.

In the above configuration, the flow rate of the gas or liquid supplied to the primary side of the restriction orifice is made constant by the action of the constant flow valve, so that the primary or secondary pressure of the restriction orifice fluctuates. The flow rate of gas or liquid supplied to the filtration membrane becomes constant, and the maintenance of the filtration membrane can be ensured.

Another filtration membrane cleaning apparatus according to the present invention is a filtration membrane cleaning apparatus for cleaning a filtration membrane of a cross-flow type microfiltration or ultrafiltration apparatus which performs filtration while circulating a stock solution. A flow sensor for detecting the flow rate of the gas or liquid supplied to the primary side of the restriction orifice upstream of the primary side of the restriction orifice for evenly distributing the gas or liquid supplied to the filtration membrane for washing, An automatic control valve for controlling a flow rate of gas or liquid supplied to the primary side of the restriction orifice according to detection information of the flow rate sensor.

In the above configuration, the flow rate sensor detects the flow rate of the gas or liquid supplied to the primary side of the restriction orifice, and the automatic control valve responds to this detection information to set the gas supplied to the primary side of the restriction orifice. Or, by adjusting the flow rate of the liquid to make it constant, the flow rate of gas or liquid supplied to the filtration membrane becomes constant even if the pressure on the primary or secondary side of the restricting orifice fluctuates, maintaining the filtration membrane. Can be secured. Further, in this case, it is possible to easily set the flow rate change adjustment.

Further, a filtration device according to the present invention is characterized by having the above-mentioned filtration membrane cleaning device.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of a filtration membrane cleaning method, a filtration membrane cleaning apparatus and a filtration apparatus provided with the same according to the present invention will be specifically described. FIG. 1 is a diagram showing a configuration of a first embodiment of a filtration device provided with a filtration membrane cleaning device according to the present invention.

In FIG. 1, reference numeral 9 denotes a stock solution tank which stores a stock solution 9a to be filtered. In the present embodiment, for example, river water, lake water, groundwater, seawater, or the like is used as the stock solution 9a. A stock solution circulation pump 10 is connected to the downstream side of the stock solution tank 9, and the stock solution 9 a in the stock solution tank 9 is driven by driving the stock solution circulation pump 10.
Is supplied to the pipe 11.

A plurality of filtration membrane modules 12 each composed of a cross-flow type hollow fiber membrane are connected in parallel to the pipe 11, and the stock solution 9a supplied to the filtration membrane module 12 through the pipe 11 is A predetermined pressure is applied by the operation of the undiluted solution circulation pump 10, and the filtration is performed by permeating the hollow fiber membrane from the outside to the inside of the hollow fiber membrane of the filtration membrane module 12, and the filtrate 9b filtered by the filtration membrane module 12 is removed from the hollow fiber membrane. After flowing through the inside, it is guided to the filtrate pipe 13 and stored in a filtrate tank (not shown).

On the other hand, through the pipe 11, the filtration membrane module 12
A part of the undiluted solution 9a supplied to the tank is circulated outside the hollow fiber membrane of the filtration membrane module 12 as the circulating return undiluted solution 9c, guided to the undiluted solution return pipe 14, and returned to the undiluted solution tank 9.

Further, in order to eliminate suspended substances accumulated in the filtration membrane of the filtration membrane module 12, a filtration membrane washing device for performing air bubbling is provided. In FIG. 1, after the compressed air supplied by the compressor 3 is regulated by the air tank 4 on each primary side of a plurality of filtration membrane modules 12 connected in parallel, a constant flow valve which is a feature of the present invention is provided. The air having a constant flow rate by the respective orifices 5
, And are uniformly distributed and supplied.

The constant flow valve 6 is constituted by a self-operating system operated by a pressure difference between a primary pressure and a secondary pressure, and a pressure 2a on the downstream side of the air tank 4 which is a primary pressure and a pressure 2a which is a secondary pressure. It operates by the pressure difference between the primary side of the restriction orifice 5 and the back pressure 2b of the pipe 2 connected to maintain the flow rate of the air supplied to each restriction orifice 5 constant.

The air supplied from the pipe 1 connected to the upstream side of the filtration membrane module 12 through the restriction orifice 5 flows outside the hollow fiber membrane of the filtration membrane module 12 and vibrates the hollow fiber membrane. Then, the suspended matter accumulated on the outer surface of the hollow fiber membrane is peeled off.

The restriction orifices 5 are provided on the upstream side, one for each filtration membrane module 12, and the air supplied to each restriction orifice 5 is
The flow rate of air supplied to each filtration membrane module 12 is made uniform by flowing through a hole of a predetermined diameter provided in,
An air bubbling operation for removing suspended substances accumulated in the filtration membrane without giving excessive vibration to the filtration membrane of each filtration membrane module 12 can be performed well.

In the air bubbling operation, for example, first, the air is supplied in a state in which the stock solution 9a is stretched in the filtration membrane module 12, that is, in the first state in which the stock solution 9a is stationary and stays in the filtration membrane module 12. Supply at a flow rate of 5 [Nm ³ / hr] for 60 seconds.

At this time, the secondary side of each filtration membrane module 12 is open, the secondary pressure of the restriction orifice 5 becomes 0.3 [kgf / cm ² G], and The flow rate of the air supplied to the filtration membrane of No. 12 becomes uniform, so that the air bubbling operation for removing suspended substances accumulated in the filtration membrane without giving excessive vibration to the filtration membrane can be performed well. Has become.

Thereafter, the undiluted solution 9 is further added to the filtration membrane module 12.
In the second state in which a is flowed, supply is performed at a flow rate of 5 [Nm ³ / hr] for 60 seconds. At this time, a predetermined load is applied to the secondary side of each filtration membrane module 12, and the secondary side pressure of the restriction orifice 5 becomes 1.0 [kgf / cm ² G]. The above-described series of air bubbling operations is performed once every three days for 120 days.
This is repeated for a second and periodically.

Then, the stock solution circulating pump is
The recirculating undiluted solution 9c, which is a part of the undiluted solution 9a supplied by the step 10, flows outside the hollow fiber membrane of the filtration membrane module 4, and pushes and discharges the suspended substance peeled off as described above. The recirculated undiluted solution 9c containing the suspended substance is led to the undiluted solution return pipe 14 and stored in the waste liquid tank 15.

According to the above configuration, the filtration membrane module 12 is moved from the first state in which the stock solution 9a is stretched into the filtration membrane module 12.
Even when the secondary pressure of the restriction orifice 5 changes when switching to the second state in which the stock solution 9a flows, the flow rate of the air flowing through the filtration membrane module 12 is kept constant by the action of the constant flow valve 6. As described above, the hollow fiber-shaped membrane of the filtration membrane module 12 does not suffer from breakage of the hollow fiber as in the conventional example described above, and the maintenance of the filtration membrane of the filtration membrane module 12 is maintained to maintain high filtration performance. In addition, the life of the filtration membrane can be improved.

That is, since the flow rate of the air supplied to the primary side of the restriction orifice 5 is made constant by the operation of the constant flow valve 6, the air supplied to the filtration membrane module 12 in the first and second states is controlled. The flow rate can be set to 5 [Nm ³ / hr], and the pressure on the primary side of the restriction orifice 5 fluctuates correspondingly.

Thus, even if the pressure on the secondary side of the restriction orifice 5 fluctuates, the flow rate of the air supplied to the filtration membrane module 12 does not fluctuate. And never.

Further, even when the pressure supplied to the primary side of the constant flow valve 6 is relatively large, the flow rate of the air supplied to the filtration membrane module 12 is similarly kept constant by the action of the constant flow valve 6. I can do it.

Therefore, unlike the above-described conventional example, there is no possibility that the hollow fiber breakage of the hollow fiber membrane of the filtration membrane module 12 occurs due to an increase in the flow rate of air and the filtration performance of the filtration membrane module 12 is reduced. It is possible to secure the maintenance of the filtration membrane of the membrane module 12, prevent the filtration performance of the filtration membrane from deteriorating, and improve the life of the filtration membrane.

Reference numeral 7 shown in FIG. 1 is a valve for controlling the supply of air, and 16 to 19 are valves for preventing backflow during a filtering operation or an air bubbling operation.

Next, a second embodiment of the filtration membrane cleaning method and the filtration membrane cleaning apparatus according to the present invention and the filtration apparatus provided with the same will be described in detail with reference to FIG. FIG. 2 is a diagram showing the configuration of a second embodiment of the filtration device provided with the filtration membrane cleaning device according to the present invention. The same components as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

In the first embodiment, the filtration membrane module
In order to make the flow rate of the air supplied to the primary side of the restriction orifice 5 for uniformly distributing the air supplied to the twelve filtration membranes constant, the primary side of the restriction orifice 5 is provided upstream of the primary side of the restriction orifice 5. The case where the constant flow valve 6 for making the flow rate of the air supplied to the side constant is provided has been described. In the present embodiment, as shown in FIG. Upstream and downstream of the air tank 4, a flow sensor 21 for detecting the flow rate of air supplied to the primary side of the restriction orifice 5 is provided.
An automatic control valve 22 for adjusting the flow rate of air supplied to the primary side of the restriction orifice 5 based on the detection information of the flow rate sensor 21 is provided in series downstream of the flow rate sensor 21.

The flow rate sensor 21 detects the flow rate of air on the downstream side of the air tank 4, performs PID (proportional-integral-derivative) control based on the detection signal, operates the automatic control valve 22, and controls the primary side of the restriction orifice 5. The flow rate of the supplied air is adjusted to be kept constant, whereby the same effect as in the first embodiment can be obtained.

In this embodiment, since the flow setting of the automatic control valve 22 can be changed relatively easily, the flow sensor 21
The flow rate of air supplied to the primary side of the restriction orifice 5 at a constant flow rate can be appropriately changed to a desired flow rate by the operation of the automatic control valve 22 and the automatic control valve 22.

In each of the above embodiments, the case where air (air) is used during the air bubbling operation has been described. However, for example, filtration is performed using another gas such as nitrogen gas or ozone, or a liquid such as ozone water or water. It is also possible to adopt a configuration in which suspended substances accumulated in the filtration membrane of the membrane module 12 are eliminated for washing. In this case, similarly to the above-described embodiments, other components supplied to the primary side of the restriction orifice 5 can be used. The flow rate of the liquid such as gas or water can be made constant by the operation of the constant flow valve 6 of the first embodiment or the flow sensor 21 and the automatic control valve 22 of the second embodiment.

Thus, the constant flow valve 6 or the automatic control valve
Even if the primary pressure of 22 or the secondary pressure of the restriction orifice 5 fluctuates, the flow rate of other liquids such as gas and water supplied to the filtration membrane module 12 does not fluctuate,
Liquids such as other gases and water supplied to 12 do not have an excessive flow rate.

Therefore, as in the above-described conventional example, the hollow fiber-like membrane of the filtration membrane module 12 breaks due to an increase in the flow rate of the liquid such as another gas or water, and the filtration membrane module 12
There is no danger of lowering the filtration performance of the filter module 12
Thus, it is possible to prevent the filtration performance of the filtration membrane from deteriorating and to improve the life of the filtration membrane.

[0050]

As described above, the present invention has the above-described structure and operation, and switches from the first state in which the undiluted solution is filled in the filtration membrane module to the second state in which the undiluted solution flows through the filtration membrane module. Sometimes, even if the secondary pressure of the restriction orifice changes, the gas flowing through the filtration membrane module by the operation of the constant flow valve provided upstream of the restriction orifice on the primary side, or by the operation of the flow sensor and the automatic control valve. And the flow rate of the liquid can be kept constant.

In addition, even if the primary pressure of the constant flow valve or the automatic control valve or the secondary pressure of the restricting orifice fluctuates, the flow rate of other liquid such as gas or water supplied to the filtration membrane module fluctuates. Gas and liquid supplied to the filtration membrane module do not have an excessive flow rate.

Therefore, as in the conventional example, the flow rate of the gas or liquid flowing in the filtration membrane module is increased, so that the hollow fibers of the hollow fiber membrane of the filtration membrane module may be broken, thereby deteriorating the filtration performance of the filtration membrane module. Therefore, the maintenance of the filtration membrane of the filtration membrane module can be secured, the filtration performance of the filtration membrane can be maintained, and the life of the filtration membrane can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a first embodiment of a filtration device provided with a filtration membrane cleaning device according to the present invention.

FIG. 2 is a diagram showing a configuration of a second embodiment of a filtration device provided with a filtration membrane cleaning device according to the present invention.

FIG. 3 is a diagram illustrating a conventional example.

[Explanation of symbols]

 1, 2, piping 3 ... compressor 4 ... air tank 5 ... restriction orifice 6 ... constant flow valve 7 ... valve 9 ... stock solution tank 9a ... stock solution 9b ... filtrate 9c ... circulation return stock solution 10 ... stock solution circulation pump 11 ... pipe 12 ... Filtration membrane module 13 ... Filtrate piping 14 ... Undiluted solution return piping 15 ... Waste liquid tank 16 ~ 19 ... Valve 21 ... Flow sensor 22 ... Automatic control valve

Claims (4)

[Claims] 1. A method for cleaning a filtration membrane of a cross-flow type microfiltration or ultrafiltration apparatus for performing filtration while circulating a stock solution, wherein the filtration membrane is supplied to the filtration membrane for washing the filtration membrane. A method for cleaning a filtration membrane, characterized in that the flow rate of gas or liquid supplied to the primary side of a restriction orifice for uniformly distributing gas or liquid is made constant. 2. A filtration membrane washing apparatus for washing a filtration membrane of a cross-flow type microfiltration or ultrafiltration apparatus which performs filtration while circulating a stock solution, and is supplied to the filtration membrane for washing the filtration membrane. Upstream of the primary side of the restriction orifice, which distributes the gas or liquid evenly,
A filtration membrane cleaning device, comprising: a constant flow valve for keeping a flow rate of a gas or a liquid supplied to a primary side of the restriction orifice constant. 3. A filtration membrane washing apparatus for washing a filtration membrane of a cross-flow type microfiltration or ultrafiltration apparatus which performs filtration while circulating a stock solution, and is supplied to the filtration membrane for washing the filtration membrane. Upstream of the primary side of the restriction orifice, which distributes the gas or liquid evenly,
A flow sensor for detecting a flow rate of gas or liquid supplied to the primary side of the restriction orifice; and an automatic control valve for adjusting a flow rate of gas or liquid supplied to the primary side of the restriction orifice based on detection information of the flow rate sensor. And a filtration membrane cleaning device. 4. A cross-flow type microfiltration or ultrafiltration apparatus for performing filtration while circulating a stock solution, comprising a filtration membrane washing apparatus according to claim 2 or 3. .