JP2001104761A - Operation method for membrane separation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation method for a membrane separation apparatus easy to set the flow rate of a non-permeable liquid at which the flow passages in the membrane module are not clogged. SOLUTION: The average flow velocity of a non-permeable liquid in the passages in a membrane module is increased more as the viscosity of the non- permeable liquid is increased more. The flow rate of the non-permeable liquid at which the passages in the membrane module are prevented from clogging is calculated by multiplying the average flow rate of the non-permeable liquid with the cross-section surface area of the passages.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a latex concentrate,
The present invention relates to an improvement in an operation method of a membrane separation device useful for colloidal silica concentration, valuable resource recovery, waste liquid treatment, metal classification, tap water filtration, activated sludge treatment, tap water sludge treatment, food waste liquid treatment, slurry washing, and the like.

[0002]

2. Description of the Related Art Heretofore, as a method for concentrating a liquid to be treated, there has been known a method for concentrating a liquid to be treated by a cross-flow type membrane separation apparatus having a permeable membrane having micropores. . The cross-flow type membrane separation device separates the liquid to be treated into a permeate component and a non-permeate component by a permeable membrane, and supplies the non-permeate component again to the apparatus inlet side, and the permeate component and the non-permeate component are also transmitted by the permeable membrane Then, the same operation is repeated to increase the concentration of the non-permeated liquid. In this case, in order to avoid clogging of the membrane due to the suspended matter in the non-permeate and prevent the permeation efficiency from decreasing, the flow rate of the liquid to be treated is increased to increase the shear force on the membrane surface. There is a method of removing foreign matter from the material. That is, the most important thing in membrane separation is to prevent the membrane surface from being contaminated with foreign matters so that a uniform flow of the processing solution is formed on the membrane surface.

However, since the fluidity decreases with an increase in the concentration of the non-permeate, the flow rate of the non-permeate, that is, the non-permeate before the flow path in the membrane module is closed by the suspended matter in the non-permeate. It is necessary to set the flow rate of the liquid to an appropriate value. However, since the relationship between concentration and fluidity differs depending on the type of liquid to be treated, a test is performed for each liquid to be treated to determine the flow rate of the non-permeate liquid so that the flow path in the membrane module is not blocked. Has to be set on the basis of the flow rate of the non-permeate liquid.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to easily set a flow rate of a non-permeate liquid so as not to block a flow path in a membrane module. It is an object of the present invention to provide a method of operating a membrane separation device that can perform the operation.

[0005]

In order to achieve the above object, the present invention employs a method of generalizing the fluidity of a non-permeate by viscosity. That is, the present inventor has found that the flow rate of the non-permeate liquid in which the flow path in the membrane module does not block changes according to the viscosity of the non-permeate liquid. The flow rate of the non-permeate liquid that does not block the flow path can be known. By multiplying the flow rate of the non-permeate liquid by the cross-sectional area of the non-permeate liquid flow path in the membrane module, the non-permeate liquid that does not block the flow path in the membrane module is obtained. The flow rate of the liquid can be determined.

[0006]

That is, the gist of the present invention is that a liquid to be treated is supplied to one side of a membrane separation apparatus having a permeable membrane, a permeated component is transmitted to the other side, and the permeated liquid is supplied from the other side. When the liquid to be treated is concentrated by removing the non-permeate liquid that does not pass through the permeable membrane from one side, the viscosity of the non-permeate liquid increases and the average flow rate of the non-permeate liquid in the flow path in the membrane module increases. The operation method of the membrane separation device is characterized in that the flow path in the membrane module is prevented from being blocked by the operation.

According to the present invention configured as described above,
By performing an operation of increasing the average flow rate of the non-permeate liquid in the flow path in the membrane module according to the increase in the viscosity of the non-permeate liquid, the liquid to be treated is mixed with the permeate liquid so that the flow path in the membrane module is not blocked. It can be separated into non-permeate liquids.

That is, the average flow velocity V ₀ (m / sec) of the non-permeate which blocks the flow path in the membrane module is determined by the viscosity η of the non-permeate.
(Pa · s), which is a function of η, wherein the average flow rate of the non-permeate in the flow path in the membrane module is V (m / sec)
Then, it is preferable to set the average flow velocity V of the non-permeate liquid so as to satisfy V> V ₀ .

Then, a flow control valve is provided in the non-permeate discharge line of the membrane separation apparatus, and the flow rate of the non-permeate is adjusted to Q (m ³ / h).
r) and the cross-sectional area of the non-permeate liquid flow path in the membrane module is A
(M ² ), and the average flow rate V of the non-permeate liquid satisfying V> V ₀
By adjusting the opening of the flow rate control valve so as to satisfy Q = V × A using the liquid, the liquid to be treated can be smoothly separated into a permeated liquid and a non-permeated liquid without blocking the flow path in the membrane module. can do.

If the permeable membrane can vibrate and the membrane is separated while vibrating the permeable membrane, the high concentration component near the membrane surface comes into contact with the membrane surface due to the shear force generated by the vibration of the permeable membrane. Without being discharged from the non-permeate side outlet, the permeated component permeates the permeable membrane with a high permeation flux. In addition, since a high shear field is formed on the membrane surface due to the vibration, the membrane surface is kept in a clean state, and the blockage of the flow path in the membrane module is prevented. Even if the liquid to be treated with a higher viscosity flows, a shear field is generated on the membrane surface due to vibration, so that the water trapped between the particles becomes free water and the fluidity is improved. Since the apparent viscosity coefficient is reduced, it is possible to process a high-concentration liquid to be processed, and it is possible to reduce the average flow rate of the non-permeate liquid.

[0011] Most of the energy for moving the membrane surface is converted into a fluid near the membrane surface as a shear force, and the liquid to be treated can be concentrated with high efficiency.

Thus, the liquid to be treated supplied to one side of the permeable membrane is taken out as a permeated liquid from the other side, taken out as a non-permeated liquid from one side, and described above according to an increase in the viscosity of the non-permeated liquid. By performing the permeation treatment by vibrating the permeable membrane while changing the flow rate of the non-permeate liquid in such a manner, the liquid to be treated can be smoothly concentrated to a predetermined concentration without blocking the flow path in the membrane module. Can be.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a schematic configuration of a vibration type membrane separation apparatus suitable for applying the operation method of the present invention. Referring to FIG. 1, 1 is a supply tank of a liquid to be treated, 2 is a pump for pumping the liquid to be treated, 3 is a membrane module in which many flat membrane type permeable membranes are laminated, and 4 is a membrane module in the membrane module 3. A torsion bar that gives the permeable membrane a reciprocating motion with a small amplitude of 1 to 2.5 cm in amplitude and a vibration frequency of 40 to 60 Hz in the circumferential direction in the horizontal plane, 5 is a storage tank for non-permeated liquid (concentrated liquid), and 6 is permeable. It is a liquid storage tank. Reference numeral 7 denotes a flow control valve for controlling the discharge amount of the non-permeate discharged from the membrane module 3 via the pipe line 8.

As shown in FIG. 2, a metal plate 11 is provided inside the membrane module 3 between two upper and lower permeable membranes 9 and 9 'via two to fifteen nonwoven fabric drain cloths 10 and 10'. The stacked components are arranged in a horizontal direction, and are arranged in multiple stages with a predetermined gap provided in a vertical direction. In the figure, the upper side of the upper permeable film 9 is one side (supply side), and the drain cross 10 side is the other side (transmission side). When the liquid to be treated is supplied to the supply side, the internal pressure on the supply side is set to a higher pressure (about ^{2 to} 40 kgf / cm ² ) than that on the permeation side, so that the permeated component in the liquid to be treated, ie, as shown in FIG. Thus, particles (permeation components) smaller than the micropores of the permeable membrane 9 pass through the membrane pores 12 and reach the other side. The non-permeate liquid after the permeation component has passed is supplied to the supply side of the permeable membrane 9 in the next stage in FIG. 2, and the permeation component permeates through the membrane pores.

During the permeation process, the permeable membrane in the membrane module 3 shown in FIG. 1 continues to reciprocate with a small amplitude in the circumferential direction in the horizontal plane due to the action of the torsion bar 4.
Concentration polarization of the liquid to be treated near the film surface due to the shearing effect due to vibration (part where the concentration is abnormally high on the film surface)
And clogging of the film is prevented. Further, the flow path in the membrane module is less likely to be blocked. Thus, pump 2
By applying a more appropriate pressure to the liquid to be treated, the liquid to be treated can be efficiently separated into a permeated liquid and a non-permeated liquid under a high permeation flux. The permeation process is sequentially performed in this manner, and the obtained permeate is passed through the pipe 13 to the storage tank 6.
And the non-permeated liquid in the pipe 8 is sent to the storage tank 5. Thus, the liquid to be treated in the tank 1 can be supplied to the membrane module 3 via the conduit 14, and can be efficiently separated into a permeated liquid and a non-permeated liquid by the above-mentioned vibration type membrane separation device.

As the permeable membrane of the vibration type membrane separation device, a reverse osmosis membrane, a microfiltration membrane, a nanofilter, an ultrafiltration membrane or the like can be suitably used.

FIG. 4A is a view showing the flow of the liquid to be treated in the membrane module. The liquid to be treated flows into the membrane module from the path 15, and the permeated liquid that has passed through the permeable membrane passes through the path 16.
And the non-permeated liquid is discharged from the passage 17. 1
Reference numeral 8 denotes a non-permeate liquid flow path (a gap between the permeable film 9 'immediately above and the permeable film 9 immediately below is a non-permeate liquid flow path; see an enlarged view of FIG. 2). FIG. 4B is an enlarged plan view of the permeable membrane.
Reference numeral 19 denotes a flow path for the permeated liquid, and reference numeral 20 denotes a flow path for the liquid to be treated.

The vibrating membrane separation apparatus is a concentrating apparatus in which the membrane is not easily clogged. However, when the concentration of the non-permeate increases, the fluidity decreases. Therefore, the force for pushing out the non-permeate by increasing the flow rate of the non-permeate is used. If the flow rate of the non-permeate liquid is not adjusted to an appropriate range so that the flow rate increases, the flow path of the non-permeate liquid of the membrane module (see No. 18 in FIG. 4 (a)) eventually becomes a suspension in the non-permeate liquid. May block. Therefore, the following experiment was conducted in order to find a condition in which the flow path of the non-permeated liquid in the membrane module was not blocked.

That is, using a vibration type membrane separation apparatus having a configuration shown in FIG. 1 in which two kinds of circular flat membranes having a diameter of 30 cm and 60 cm are arranged as a permeable membrane (ultrafiltration membrane), a concentration of 2 to 1 is used.
For a liquid to be treated in the range of 0% by weight (several types of water sludge having different concentrations and viscosities), the permeable membrane has an amplitude of 2.
The membrane separation test (concentration test) was performed by changing the pumping amount of the liquid to be treated by the pump 2 while vibrating under conditions of ² cm, a vibration frequency of 50 Hz, and an operating pressure (pressure on the supply side) of 5.0 kgf / cm ^2. Performed to obtain non-permeated liquids of various concentrations.

In order to avoid blockage of the flow path in the membrane module, it is important to increase the flow rate of the liquid to be treated and increase the force for pushing out the non-permeate liquid. The following operation was carried out on the assumption that there should be a condition that would not block the flow path in the membrane module between the average flow rate of the non-permeated liquid in the internal flow path.

That is, the viscosity (Pa · s) of each non-permeate obtained by the concentration test is measured with a viscometer, and the flow rate (m ³ / h) of the non-permeate flowing out from the membrane module outlet to the pipe 8 is measured.
r) is divided by the vertical cross-sectional area (m ² ) of the non-permeate liquid outlet flow path of the membrane module (see No. 18 in FIG. 4 (a)) to obtain the average of the non-permeate liquid at the membrane module outlet flow path. The flow rate (m / sec) was determined.

Further, by changing the pressure of the liquid to be treated by the pump 2, the average flow velocity of the non-permeate liquid is made lower than the current flow velocity. The flow rate of the non-permeate liquid is changed to 10% or less, "no blockage of the flow path in the membrane module", and the flow rate of the non-permeate liquid is reduced to more than 10%, "the flow path in the membrane module". Indicates that the flow path in the membrane module is blocked with respect to each viscosity η (Pa · s) of the non-permeate liquid and the average flow rate of the non-permeate liquid in the non-permeate liquid outlet flow path of the membrane module. When the line is plotted, it is as shown by the line L in FIG. The upper part of the line L in FIG. 5 indicates a range in which the flow path in the membrane module is not blocked, and the lower part of the line L indicates a range in which the flow path in the membrane module is blocked. When L is represented by a function of η, L = f (η) = 0.047η ^0.5121 . Note that the actual function form of f (η) changes depending on the membrane module structure and the membrane separation method. The measurement of viscosity is
Rotor No. of B-type viscometer 3 and rotating at a rotation speed of 12 rpm.

As apparent from FIG. 5, the average flow rate of the non-permeate in the flow path in the membrane module in which the flow path in the membrane module is not blocked can be obtained by calculating the viscosity of the non-permeate liquid. By multiplying the flow velocity by the cross-sectional area of the flow path, it is possible to obtain a flow rate of the non-permeate liquid that does not block the flow path in the membrane module. As a specific operation method, the flow rate of the non-permeated liquid can be set by adjusting the opening of the flow control valve 7 in FIG. 1 so that the flow path in the membrane module is not blocked. As the viscometer, a B-type viscometer was used, but the viscometer is not limited to this, and a rheometer, a vibrating viscometer, or the like can be used. However, since the value of viscosity differs depending on the viscometer and measurement conditions used,
It is necessary to use the relationship between the viscosity obtained by each viscometer and the flow rate. Further, in the above embodiment, the vibration type membrane separation device was used, but the relationship between the viscosity of the non-permeate and the flow rate at which the flow path in the membrane module is not blocked is determined in the same manner in the conventional cross flow type membrane separation device. Is possible.

Further, since a so-called latex such as a colloidal dispersion of a vinyl chloride resin contains a dispersant, the viscosity is low and the membrane separation operation at a higher concentration is possible. In addition, it is possible to set the non-permeate flow rate so as not to block the flow path in the membrane module and to perform the concentration.

[0025]

Since the present invention is configured as described above, the following effects can be obtained.

According to the first aspect of the present invention, the operation of increasing the average flow rate of the non-permeate liquid in the flow path in the membrane module in accordance with the increase in the viscosity of the non-permeate liquid is performed, whereby the flow path in the membrane module is increased. The liquid to be treated can be separated into a permeated liquid and a non-permeated liquid so that the liquid does not block.

That is, as described in claim 2, the average flow velocity V (m / sec) of the non-permeate in the flow path in the membrane module is as follows:
The average flow velocity V ₀ (m) of the non-permeate that blocks the flow path in the membrane module, which varies depending on the viscosity η (Pa · s) of the non-permeate
/ Sec), that is, by setting the average flow velocity V of the non-permeate liquid so as to satisfy V> V ₀ , so that the liquid to be treated is not mixed with the permeate liquid so that the flow path in the membrane module is not blocked. It can be separated into permeate.

Specifically, as described in claim 3, V>
By multiplying the average flow velocity V of the non-permeate liquid satisfying V ₀ by the cross-sectional area A of the non-permeate liquid flow path in the membrane module of the membrane separation device, the flow rate of the non-permeate liquid that does not block the flow path in the membrane module can be simplified. By adjusting the opening of the flow control valve arranged in the non-permeate discharge line of the membrane separation device to satisfy the flow rate, the flow in the membrane module can be The liquid can be stably separated into a permeated liquid and a non-permeated liquid.

According to the fourth aspect of the present invention, by vibrating the permeable membrane, the high shearing force generated on the membrane surface by the shearing effect of the vibration increases the effect of preventing the blockage of the flow path in the membrane module.

As described above, according to the present invention, it is not necessary to experimentally determine the flow rate of the non-permeate liquid that does not block the flow path in the membrane module for each liquid to be treated, and by measuring the viscosity of the non-permeate liquid. Knowing the average flow rate of the non-permeate in the flow path in the membrane module in which the flow path in the membrane module is not blocked, and setting the appropriate non-permeate flow rate easily based on this average flow rate,
The concentration operation is extremely smooth.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a vibrating membrane separation apparatus suitable for applying the operation method of the present invention.

FIG. 2 is a sectional view showing a part of a membrane module used in the vibration type membrane separation device of FIG.

FIG. 3 is a diagram showing a concept of a permeation process by a vibration type membrane separation device.

FIG. 4 (a) is a diagram showing a flow of a liquid to be treated in a membrane module by a vibrating membrane separation device, and FIG. 4 (b) is an enlarged plan view of a permeable membrane.

FIG. 5 is a diagram showing the blockage limit of the flow path in the membrane module with respect to the viscosity of the non-permeate liquid and the average flow rate of the non-permeate liquid in the flow path in the membrane module in the vibration type membrane separation device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Supply tank 3 ... Membrane module 5 ... Non-permeate liquid storage tank 6 ... Permeate liquid storage tank 7 ... Flow control valve 9, 9 '... Permeable membrane 18 ... Non-permeate liquid flow path 19 ... Permeate liquid flow path 20 ... Flow path of liquid to be treated

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4D006 GA03 GA06 GA07 HA45 JA03C JA07C JA33A JA53Z JA59A JA64Z JA67Z KA12 KA16 KA31 KA41 KB30 KC27 KE02Q KE04Q KE14P KE22R MA03 MB02 PB04 PB05 PB20 PB20 PB15 PB15 PB15

Claims (4)

[Claims] 1. A liquid to be treated is supplied to one side of a membrane separation apparatus provided with a permeable membrane, a permeated component is permeated to the other side, and a permeated liquid is taken out from the other side. When the liquid to be treated is concentrated by removing the non-permeate liquid that does not permeate, the viscosity of the non-permeate liquid increases and the average flow velocity of the non-permeate liquid in the flow path in the membrane module increases, thereby blocking the flow path in the membrane module. A method for operating a membrane separation device, characterized in that the separation is prevented. 2. A liquid to be treated is supplied to one side of a membrane separation device provided with a permeable membrane, a permeated component is transmitted to the other side, a permeated liquid is taken out from the other side, and a permeable membrane is supplied from one side. When the liquid to be treated is concentrated by taking out the non-permeate which does not permeate, the average flow velocity V ₀ (m / sec) of the non-permeate closing the flow path in the membrane module is the viscosity η (Pa · s) of the non-permeate. And the average flow rate of the non-permeate in the flow path in the membrane module is V (m / sec), V>
A method for operating a membrane separation apparatus, comprising: setting an average flow velocity V of a non-permeate liquid so as to satisfy V ₀ to prevent blockage of a flow path in a membrane module. 3. A cross-sectional area of a non-permeate flow path in a membrane module, wherein a flow control valve is disposed in a non-permeate discharge line of the membrane separation device, and a flow rate of the non-permeate is Q (m ³ / hr). A
(M ² ), and the average flow velocity V of the non-permeate liquid satisfying V> V ₀
3. The operation of the membrane separation apparatus according to claim 2, wherein the opening of the flow rate control valve is adjusted so as to satisfy Q = V × A to prevent the flow path in the membrane module from being blocked. Method. 4. The membrane as set forth in claim 1, wherein the permeable membrane is capable of vibrating, and the membrane is separated while vibrating the permeable membrane to prevent the passage in the membrane module from being blocked.
Or the operation method of the membrane separation device according to 3.