JP2002153735A - Membrane module cleaning method and membrane separation device - Google Patents

Abstract

(57) [Problem] To provide a cleaning method that can sufficiently recover the processing efficiency of a membrane module and can be performed at low cost. SOLUTION: A cleaning liquid supply step of supplying a cleaning liquid to a liquid side 3a to be treated of a membrane module 3, a vapor supply step of supplying vapor to a permeated liquid side 3b, and a cleaning liquid supplied to the membrane module 3 are transmitted. A cleaning liquid heating step of heating with the vapor supplied to the liquid side 3b, and a cleaning liquid discharging step of discharging the cleaning liquid in the membrane module 3 by supplying vapor to the permeated liquid side 3b or the liquid side 3a to be treated. And do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a membrane module and a membrane separation apparatus, and more particularly to a method for removing sulfur from a saccharified solution.
The present invention relates to a washing method and a membrane separation device which can be suitably applied to a membrane module used for membrane filtration in a pharmaceutical or food manufacturing process, such as S separation, separation of bacterial cells from a fermented solution, and finish filtration of sake, beer, and wine. More specifically, the present invention relates to a method for cleaning a membrane module and a membrane separation device capable of obtaining a sufficient cleaning effect in a short time with a small amount of a cleaning solution.

[0002]

2. Description of the Related Art In the pharmaceutical and food manufacturing processes,
When performing a membrane separation treatment using a membrane module, if the treatment is performed for a long time, the liquid to be treated is concentrated, and so-called fouling substances such as proteins, saccharides, and microorganisms are formed on the separation membrane surface on the liquid to be treated. Adhere to the membrane module, and the permeation flux of the membrane module is reduced, thereby lowering the processing efficiency. If the separation performance of the separation membrane is reduced by the fouling substance, in order to recover the membrane separation performance, for example, alkali,
BACKGROUND ART Separation membranes are washed by a washing method in which a cleaning solution such as an acid or an oxidizing agent is circulated and supplied to a liquid side of a membrane module to be treated.

[0003]

However, in the conventional cleaning method described above, the cleaning effect tends to be insufficient, and the processing efficiency of the membrane module cannot be sufficiently recovered. Further, there has been a problem that the cleaning cost rises due to an increase in the amount of the cleaning solution used. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a cleaning method that can sufficiently recover the processing efficiency of a membrane module and can be performed at low cost.

[0004]

According to the present invention, there is provided a method for cleaning a membrane module, comprising the steps of: supplying a cleaning solution to a liquid side to be treated of the membrane module; and supplying steam to a permeate side of the membrane module. A cleaning chemical solution heating step of heating the cleaning chemical liquid supplied to the membrane module with the vapor supplied to the permeate liquid side, and further applying steam to the permeate liquid side or the liquid side of the membrane module. A cleaning liquid discharging step of discharging the cleaning liquid in the membrane module from the membrane module by supplying the cleaning liquid. The membrane separation device of the present invention is a membrane module for obtaining a concentrated solution and a permeate by subjecting a liquid to be treated to membrane separation, a liquid to be treated supply path for supplying the liquid to be treated to the liquid to be treated side of the membrane module,
A cleaning liquid supply path for supplying a cleaning liquid to the liquid to be treated;
It is characterized by comprising a vapor supply path for supplying vapor to the liquid to be treated or the permeate liquid, and a cleaning liquid discharge path for discharging the cleaning liquid in the membrane module from the membrane module.

[0005]

FIG. 1 shows an embodiment of a membrane separation apparatus according to the present invention. The membrane separation apparatus 1 shown here comprises a liquid storage tank 2 for storing a liquid to be processed and a storage tank 2 for storing the liquid. The apparatus is provided with a membrane module 3 for subjecting a liquid to be treated from the tank 2 to a membrane separation process, and a cleaning chemical solution storage tank 4 for storing a cleaning chemical solution. The membrane separation apparatus 1 includes a processing liquid supply path 5 for supplying a processing liquid to the processing liquid side 3a of the membrane module 3, and a cleaning liquid supply path 6 for supplying a cleaning liquid to the processing liquid side 3a.
A permeate-side vapor supply path 7 for supplying vapor to the permeate side 3b; a liquid-to-be-treated vapor supply path 8 for supplying vapor to the liquid-to-be-treated 3a; And a cleaning solution discharge path 9 for discharging from the cleaning liquid 3. Reference numerals V1 to V10 indicate valves provided on each path.

The membrane module 3 is provided with a separation membrane 3d in an outer container 3c. As the separation membrane 3d, a material made of a metal, ceramic, an organic material, or the like can be used as long as it can supply steam, and a material made of a material having excellent heat resistance, such as a metal or a ceramic, is preferable. It is. Especially when metal materials are used,
Even when there is a sudden change in temperature or pressure, deterioration of the material of the membrane module can be prevented, which is preferable. In particular, those made of titanium-coated stainless steel whose stainless steel surface is coated with titanium can be suitably used.

The shape of the separation membrane 3d may be tubular, hollow fiber, pleated, spiral, plate and frame, or the like. In particular, the tubular membrane is preferable because even if it is applied to a liquid to be treated containing a large amount of solid content, the separation performance hardly decreases and the pressure resistance is excellent.

[0008] The cleaning chemicals stored in the cleaning chemical storage tank 4 include alkali agents such as sodium hydroxide, organic acids (citric acid, oxalic acid, etc.), mineral acids (sulfuric acid, etc.), oxidizing agents (hydrogen peroxide, Aqueous solution such as peracetic acid) and a surfactant can be used.

Next, a method for performing a membrane separation process using the membrane separation apparatus 1 will be described. In the present invention, the treatment target (liquid to be treated) of the membrane module includes a medicine, a saccharified liquid in a food production process, a fermentation liquid, and a beverage (sake, beer,
Intermediate products and the like. These liquids to be treated usually contain solids composed of proteins, sugars, microorganisms and the like.

In order to carry out the membrane separation treatment of the liquid to be treated, the liquid to be treated in the liquid to be treated storage tank 2 is passed through the liquid to be treated supply path 5 using the pump P1 and the liquid to be treated 3a of the membrane module 3 is treated. To be introduced. When the cross-flow filtration method is adopted as the filtration method, the valves V2, V3, and V4 are opened, and the valves V1 and V5 are closed. As a result, the liquid to be treated introduced into the liquid to be treated 3a is subjected to membrane separation by the separation membrane 3d. That is, a part of the liquid to be treated permeates through the separation membrane 3d, and passes through the permeated liquid outlet path 11b from the permeated liquid side 3b as the permeated liquid.
And the other part is returned to the processing liquid storage tank 2 through the return path 10 as a concentrated liquid. In the case of employing the total filtration method, the valves V2 and V4 are opened and the valves V1, V3 and V5 are closed, and the return of the concentrated liquid from the return path 10 is not performed. Regardless of the filtration method, the valves V7, V8,
V9 and V10 are closed.

When the above-mentioned membrane separation treatment is performed for a long time, the liquid to be treated is concentrated, and the solid content (for example, proteins, saccharides, microorganisms) of the liquid to be treated is deposited on the surface of the liquid to be treated 3a of the separation membrane 3d. Fouling substance) adheres, and the permeation flux of the separation membrane 3d decreases. For this reason, the supply of the liquid to be treated is temporarily stopped, and fresh water or compressed air is supplied from the liquid to be treated 3a or the permeated liquid 3b of the membrane module 3 and is extruded and washed, whereby the liquid to be treated in the membrane module 3 and each path is processed. After collecting the liquid and the permeate, the separation membrane 3d is washed by the washing method described below. This washing can be performed when the permeation flow rate becomes equal to or less than a predetermined value in the membrane separation process (in the case of constant pressure filtration). Further, it can be performed when the internal pressure of the liquid to be treated 3a becomes a predetermined value or more (in the case of constant flow rate filtration).

An embodiment of the method for cleaning a membrane module according to the present invention will be described below, taking the case where the above-mentioned membrane separation apparatus 1 is used as an example. In the cleaning method of the present embodiment, rinse water is supplied into the membrane module 3 from the rinse water supply path (not shown) via the cleaning chemical liquid supply path 6, extruded and washed, and then the valve V5 is opened to discharge the rinse water. After emptying the inside of the membrane module 3, the following four steps are performed.

(1) Cleaning Chemical Liquid Supplying Step (First Step) The cleaning chemical liquid in the cleaning chemical liquid storage tank 4 is introduced to the liquid side 3a of the membrane module 3 through the cleaning chemical liquid supply path 6 using the pump P2. The supply amount of the cleaning liquid is 3
a can be filled with the cleaning solution.

(2) Steam Supply Step (Second Step) Steam supplied from a supply source (not shown) is introduced into the permeate side 3b of the membrane module 3 through the permeate side vapor supply path 7. It is preferable that the supply amount of the steam is such that the permeated liquid side 3b is filled with the steam.

(3) Cleaning Chemical Liquid Heating Step (Third Step) The vapor introduced into the permeate liquid side 3b in the vapor supply step is retained in the permeate liquid side 3b, and this vapor is mixed with the liquid to be treated 3a. This cleaning liquid is heated by heat exchange with the cleaning liquid. When the vapor in the permeate liquid side 3b is condensed due to heat exchange with the cleaning liquid and the amount is insufficient, the vapor can be appropriately supplied to the permeate liquid side 3b through the supply path 7. A part of drainage such as condensed water and steam can be discharged through the discharge path 12.

In the cleaning solution heating step, the liquid to be treated 3a
It is preferable to perform the cleaning until the temperature of the cleaning solution in the inside becomes 50 ° C. or more (preferably 60 ° C. or more). When this temperature is lower than the above range, the cleaning of the separation membrane 3d becomes insufficient, and the permeation flux of the separation membrane 3d tends to be insufficient when the membrane separation processing is restarted.

In the cleaning liquid heating step, the temperature of the cleaning liquid is raised, so that the reaction between the deposits on the separation membrane 3d and the cleaning liquid components (for example, hydrolysis of organic substances by an alkali agent or an acid agent, organic substances by an oxidizing agent). Oxidative decomposition, etc.) is promoted, and the attached matter is easily separated from the separation membrane 3d.

(4) Cleaning Chemical Liquid Draining Step (Fourth Step) Steam is supplied to the processing liquid side 3a through the processing liquid side vapor supply path 8, and the cleaning chemical liquid in the processing liquid side 3a is supplied by the vapor. , Path 5 and cleaning solution discharge path 9. At this time, the deposits on the liquid to be treated side of the separation membrane 3d can be mechanically peeled off by the shearing force due to the vapor flow in the liquid to be treated side 3a. In addition, the high-temperature steam promotes the thermal decomposition and the metamorphism of the attached matter, so that the attached matter can be easily peeled.

In this step, the vapor is supplied to the permeated liquid side 3b through the supply path 7, and this vapor is transmitted through the separation membrane 3d and supplied to the liquid to be treated 3a. The cleaning solution in the inside can be drained. In this case, since the vapor flows from the permeated liquid side 3b to the liquid to be treated side 3a, the vapor can wash the backflow of the separation membrane 3d and promote the separation of the deposits on the membrane surface and in the membrane pores. In this step, steam may be supplied to one of the liquid side 3a to be treated and the permeate liquid side 3b, or steam may be supplied to both of them.

After the completion of the first to fourth washing steps, it is preferable to wash the membrane module 3 and each path with water. Next, the liquid to be treated is introduced into the liquid to be treated 3a of the membrane module 3, and the above-mentioned membrane separation processing is restarted.

According to the method for cleaning a membrane module of the present embodiment, the following effects can be obtained. 1) Since the cleaning liquid is heated in the cleaning liquid heating step, the cleaning effect of the cleaning liquid can be enhanced, and the separation of the deposits from the separation membrane 3d can be promoted. Further, since the cleaning effect of the cleaning liquid can be enhanced, the amount of chemical used can be minimized, and the cleaning cost can be reduced. 2) In the cleaning liquid heating step, the cleaning liquid in the liquid to be treated 3a is heated by the vapor in the permeated liquid 3b, so that the cleaning liquid is heated using the membrane module 3 as a heat exchanger. Can be. Therefore, the cleaning solution can be heated without using a heat exchanger. Therefore, the apparatus configuration can be simplified and the equipment cost can be kept low. 3) In the cleaning chemical liquid discharging step, the cleaning chemical liquid is discharged by supplying steam to the liquid side 3a to be treated or the permeate liquid side 3b of the membrane module 3, so that the vapor promotes the separation of the deposits from the separation membrane 3d. be able to. From the above 1) to 3), the permeation flux of the separation membrane 3d at the time of restarting the membrane separation processing can be increased, and the processing efficiency of the membrane module 3 can be sufficiently recovered. Further, the cleaning cost can be reduced. Further, since a sufficient cleaning effect can be obtained in a short time, the time required for cleaning can be reduced, and the production efficiency can be improved.

FIG. 2 shows another embodiment of the membrane separation apparatus of the present invention. The membrane separation device shown here differs from the membrane separation device shown in FIG. 1 in that a cleaning solution return path 13 for returning the cleaning solution in the liquid to be treated 3a to the cleaning solution storage tank 4 is provided.

In this membrane separation apparatus, in the cleaning liquid supply step (first step), the cleaning liquid introduced into the liquid to be treated 3 a through the supply path 6 is returned to the cleaning liquid storage tank 4 through the return path 13, 6. A circulation operation of circulating through the membrane module 3, the path 13, and the storage tank 4 can be performed. When performing the cleaning liquid circulation operation, the cleaning liquid supply step, which is the first step, is performed while the second and third cleaning liquids are supplied.
A cleaning method of performing the steps (steam supply step, cleaning liquid heating step) can be employed.

In the steam supply step (second step),
The vapor in the permeate liquid side 3b can be continuously supplied to the permeate liquid side 3b while the vapor is sequentially discharged from the discharge path 12. As described above, when performing continuous supply of steam, the first step (cleaning liquid supply step) and the second step (steam supply step) are simultaneously performed, and then the third step (cleaning liquid heating step). The washing method which performs the following can be taken. Moreover,
A cleaning method in which the first to third steps are performed simultaneously (the cleaning liquid is heated while circulating the cleaning liquid and continuously supplying steam) may be employed.

[0025]

The effects of the present invention will be clarified below with reference to specific examples. Example 1 SS separation of a saccharified solution was performed using the membrane separation device 1 shown in FIG. As the separation membrane 3 d of the membrane module 3, a stainless steel membrane (inner diameter: 19 mm, length: 3000 mm, four cylindrical membranes, total membrane area: 0.7 m ² , pore diameter: 0.1 μm) was used. Storage tank 2
A saccharified solution (500 L, dry SS concentration: 0.5%) was put into the reactor, and the saccharified solution was supplied as a liquid to be treated to the membrane module 3 through the passage 5 using the pump P1 to perform a membrane separation process (flow rate: 270 L). / Min). In this process, valves V2, V3, and V4 were opened, valves V1 and V5 were closed, and cross-flow filtration was performed in which the saccharified solution was circulated through the membrane module 3 and the path 10. At this time, the opening degree of the valve V3 was adjusted to increase the internal pressure of the liquid to be treated 3a, so that a sufficient amount of permeate was obtained. The valves V7 to V10 were closed. After the completion of the membrane separation process, the inside of the membrane module 3 and each path were washed with water, and the washing water was discharged from the discharge path 9.

Next, the membrane module 3 is
Was washed. The valves V1, V2, V3, and V4 are closed, the valve V8 is opened while the valve V5 is open, and the cleaning solution (1% aqueous sodium hydroxide solution) in the storage tank 4 is pumped using the pump P2. (Inside the separation membrane 3d). The supply amount of the cleaning liquid was 6 L (cleaning liquid supply step). Next, the valve V5 was closed, the valve V9 was opened, and steam (105 ° C.) was supplied to the permeate side 3b through the path 7 (the valves V2 and V10 were closed) (steam supply step). Next, the cleaning solution on the liquid side 3a to be treated was heated for 10 minutes by the vapor supplied to the permeate side 3b (cleaning solution heating step). Next, the valve V9 is closed, the valve V10 is opened to discharge the vapor on the permeate side 3b through the path 12, and then the valve V7 is opened, and the vapor is discharged from the path 8 through the path 3
a, and the cleaning solution was discharged through the passages 5 and 9 by the vapor. After this steam supply was performed for 3 minutes, the valves V7 and V10 were closed (cleaning liquid discharging step). After washing the membrane module 3 and each path with water, water was supplied to the liquid side 3a of the membrane module 3 to be treated, and the permeation flux was measured. The permeation flux was an initial value (the value at the start of the membrane separation process). It was confirmed that it was almost equal to. In the process of chemical cleaning comprising the above four steps, the amount of the cleaning chemical used was only 6 L. Also, washing with water after the completion of the above-mentioned membrane separation processing,
Total time required for chemical cleaning and water washing after chemical cleaning is 2
5 minutes.

Example 2 An intermediate product (500 L) of beer was used as a liquid to be treated, and supplied to the membrane module 3 of the membrane separation apparatus 1 shown in FIG. 1 to perform a membrane separation process (flow rate 5 L / min). ). In this process, the valve V3 was closed, and the whole amount was filtered without circulating the liquid to be treated. Other processing conditions were the same as in Example 1. After the completion of the membrane separation process, the inside of the membrane module 3 and each path were washed with water, and the washing water was discharged from the discharge path 9.

Next, the membrane module 3 is
Was washed. Close valves V1, V3, and V4 and set valve V
With the valve 5 opened, the valve V8 is opened, and the cleaning solution (mixture of 10% hydrogen peroxide solution and 0.1% sodium hydroxide aqueous solution) in the storage tank 4 is treated with the liquid to be treated 3a (tubular separation membrane). 3d
Inside). The supply amount of the cleaning liquid was 6 L (cleaning liquid supply step). Subsequently, a vapor supply step, a cleaning liquid heating step, and a cleaning liquid discharge step were performed in the same manner as in Example 1. After washing the membrane module 3 and each path with water, water was supplied to the liquid side 3a of the membrane module 3 to be treated, and the permeation flux was measured. The permeation flux was an initial value (the value at the start of the membrane separation process). It was confirmed that it was almost equal to. In the above chemical cleaning process, only 6 L of cleaning chemical was used.
Met. In addition, the time required for the water washing after the completion of the membrane separation treatment, the chemical solution washing, and the water washing after the chemical solution washing was 25 minutes in total.

(Comparative Example 1) Using the same saccharified solution (500 L) as used in Example 1 as a liquid to be treated, a membrane separation treatment was performed using the membrane separation apparatus 1 shown in FIG. Flow rate 270 L / min). In this process, similar to the first embodiment,
Cross flow filtration was performed. Other processing conditions were the same as in Example 1. After the completion of the membrane separation process, the inside of the membrane module 3 and each path were washed with water, and the washing water was discharged from the discharge path 9. Next, the membrane module 3 was washed as follows. The valves V1, V3 and V4 are closed, the valve V8 is opened while the valve V5 is open, and the cleaning chemical solution (1% aqueous sodium hydroxide solution) in the storage tank 4 is treated with the liquid to be treated 3a (the cylindrical separation membrane 3d).
Inside). The supply amount of the cleaning solution was 6 L. After leaving at room temperature for 10 minutes without supplying steam, the valves V7 and V10 are opened to supply water instead of steam from the passage 8 to the liquid side 3a to be treated, and to permeate this water to the permeate side 3b. , And discharged through the passage 12 together with the cleaning solution. After supplying the water for 3 minutes, the valves V7 and V10 were closed. After washing the membrane module 3 and each path with water, water was supplied to the liquid side 3a of the membrane module 3 to be treated, and the permeation flux was measured. The permeation flux was an initial value (the value at the start of the membrane separation process). Was confirmed to be about 40%.

Comparative Example 2 Using the same saccharified solution (500 L) used in Example 1 as the water to be treated, a membrane separation treatment was performed using the membrane separation apparatus 1 shown in FIG. Flow rate 270 L / min). In this process, similar to the first embodiment,
Cross flow filtration was performed. Other processing conditions were the same as in Example 1. After the completion of the membrane separation process, the inside of the membrane module 3 and each path were washed with water, and the washing water was discharged from the discharge path 9. Next, the membrane module 3 was washed as follows. A cleaning solution (1% aqueous sodium hydroxide solution, temperature: 50 ° C.) is placed in the liquid to be treated storage tank 2 in place of the liquid to be treated, and the valve V
2, V5 and V10 are closed and the valves V3 and V4 are opened, and this cleaning solution is circulated through the path 5 using the pump P1 through the membrane module 3 and the path 10 in a cross-flow manner to form the separation membrane 3d. Chemical cleaning was performed.
The cleaning liquid is discharged through the path 9 and the membrane module 3 and each path are washed with water.
When water was supplied to a and the permeation flux was measured, the permeation flux was about 80% of the initial value (the value at the start of the membrane separation process).
However, the time required for water washing after the above-mentioned membrane separation treatment, chemical solution washing, and water washing after the chemical solution washing was 50 minutes in total.

[0031]

As described above, the following effects can be obtained by the method for cleaning a membrane module of the present invention. 1) In the cleaning liquid heating step, the cleaning liquid is heated, so that the cleaning effect of the cleaning liquid can be enhanced and the detachment of the deposits in the membrane module can be promoted. Further, since the cleaning effect of the cleaning liquid can be enhanced, the amount of chemical used can be minimized, and the cleaning cost can be reduced. 2) In the cleaning liquid heating step, the cleaning liquid in the liquid to be treated is heated by the vapor in the permeate, so that the cleaning liquid can be heated using the membrane module as a heat exchanger. Therefore, the cleaning solution can be heated without using a heat exchanger. Therefore, the apparatus configuration can be simplified and the equipment cost can be kept low. 3) In the cleaning chemical liquid discharging step, the cleaning chemical liquid is discharged by supplying steam to the liquid to be treated side or the permeate liquid side of the membrane module, so that the vapor can promote the detachment of the adhered substance. From the above 1) to 3), the permeation flux at the time of restarting the membrane separation process can be increased, and the processing efficiency can be sufficiently recovered.
Further, the cleaning cost can be reduced. Further, since a sufficient cleaning effect can be obtained in a short time, the time required for cleaning can be reduced, and the production efficiency can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a membrane separation apparatus suitable for carrying out one embodiment of a membrane module cleaning method of the present invention.

FIG. 2 is a schematic configuration diagram showing a membrane separation apparatus suitable for carrying out another embodiment of the membrane module cleaning method of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Membrane separation apparatus, 2 ... Treatment liquid storage tank, 3 ... Membrane module, 3a ... Treatment liquid side, 3b ... Permeate liquid side, 3d ...
・ Separation membrane, 4 ・ ・ ・ Cleaning liquid storage tank, 5 ・ ・ ・ Treatment liquid supply path, 6 ・ ・ ・ Cleaning liquid supply path, 7 ・ ・ ・ Permeate side vapor supply path, 8 ・ ・ ・ Treatment liquid Side steam supply path, 9 ... Cleaning liquid discharge path

Claims (2)

[Claims] 1. A method for washing a membrane module (3) for subjecting a liquid to be treated to membrane separation to obtain a concentrated solution and a permeate, wherein a cleaning agent solution is supplied to the liquid to be treated (3a) of the membrane module. A cleaning liquid supply step, a vapor supply step of supplying vapor to the permeate liquid side (3b) of the membrane module, and a cleaning liquid supply heating the cleaning liquid supplied to the membrane module by the vapor supplied to the permeate side. Temperature step; and further, a cleaning chemical liquid discharging step of discharging the cleaning chemical liquid in the membrane module from the membrane module by supplying steam to the permeated liquid side or the liquid to be processed side of the membrane module. How to clean the membrane module. 2. A membrane module (3) for obtaining a concentrated liquid and a permeate by subjecting a liquid to be treated to membrane separation, and a liquid supply passage for supplying the liquid to be treated to the liquid side (3a) of the membrane module. (5) and a cleaning solution supply path for supplying a cleaning solution to the liquid to be treated (6)
And a steam supply path (7, 8) for supplying steam to the liquid to be treated or the permeate, and a cleaning liquid discharge path (9) for discharging the cleaning liquid in the membrane module from the membrane module. A membrane separation device (1), characterized in that: