JP2011045856A - Washing method of uf membrane module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a washing method of a highly purified UF membrane module which prevents the contamination due to air suction at the time of washing completion during the washing process before incorporating the UF membrane module into the ultrapure water producing apparatus. <P>SOLUTION: In the method for washing the UF membrane module used in the ultrapure water producing apparatus, the method comprises the process of extruding ultrapure water within the module with purified gas to discharge after washing by using the ultrapure water as final washing water. The influx of air in the atmosphere accompanying the outflow of the ultrapure water within the UF membrane module into the UF membrane module can be inhibited by extruding and discharging the ultrapure water within the UF membrane module with the purified gas at the time of washing completion. Thus, the problems of contamination due to the air can be resolved. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for cleaning an ultrafiltration (UF) membrane module, and more particularly, a terminal of an ultrapure water production apparatus, that is, a secondary ultrapure water system (subsystem) installed immediately before a use point of the ultrapure water production apparatus. UF membrane module for supplying a highly clean UF membrane module by preventing contamination at the end of washing in the step of washing the UF membrane module installed at the end of) before incorporating it into the ultrapure water production apparatus About.

  The ultrapure water production equipment used in the electronics industry is a pretreatment device that removes turbidity from normal water such as industrial water and tap water, and most impurities are purified by purifying the treated water from the pretreatment device. It consists of a primary pure water device that produces pure water from which impurities have been removed, and a secondary pure water device (subsystem) that produces ultrapure water from which the primary pure water has been further refined to remove impurities almost completely. The

  Among these, the secondary pure water device is basically an ultraviolet (UV) oxidation device that decomposes organic substances, a cartridge polisher filled with an ion exchange resin that adsorbs and removes ionic impurities, and a UF for completely removing fine particles. It consists of a membrane device.

  Therefore, in the UF membrane module of the UF membrane device provided at the end (last stage) of the secondary pure water system (subsystem) of this ultrapure water production apparatus, the final stage just before the use point of ultrapure water is used. Since it is a processing apparatus, it is desirable that it is highly purified so that contamination due to passing through the UF membrane apparatus does not occur.

  Conventionally, for a UF membrane module to be loaded in a UF membrane device of an ultrapure water production apparatus, chemical cleaning with an acid or the like is performed in a pre-cleaning step before shipment, and then final cleaning with ultrapure water is performed. .

  1 and 2 are schematic cross-sectional views showing a configuration of a general hollow fiber UF membrane module. A UF membrane module 10A in FIG. 1 includes a plurality of hollow fiber UF membranes 2 in a module container 1. Both ends of the container 1 are fixed by adhesive resins 3A and 3B, outlets 4A and 4B for treated water (membrane permeated water) are provided at the top and bottom of the container 1, and water supply (covered water) is provided at the bottom of the side surface of the container 1. A treated water) inlet 5 is provided, and a concentrated water outlet 6 is provided at the top. In the UF membrane treatment by the UF membrane module 10A, the permeated water that has passed through the hollow fiber UF membrane 2 out of the water flowing in from the feed water inlet 5 is taken out from the treated water outlets 4A and 4B as treated water and permeated through the membrane. The concentrated water that did not exist is discharged from the concentrated water outlet 6.

  In the UF membrane module 10B shown in FIG. 2, one end of the hollow fiber UF membrane 2 is embedded and sealed in the adhesive resin 3B, and there is a gap between the adhesive resin 3B side and the inner wall of the container 1. This UF membrane is different from the UF membrane module 10A shown in FIG. 1 in that the permeated water is taken out only from the other end side of the UF membrane 2 and the water supply inlet 5 is provided at the bottom of the container 1. Also in the UF membrane treatment by the module 10B, out of the water flowing in from the feed water inlet 5, the permeated water that has permeated through the hollow fiber UF membrane 2 is taken out from the treated water outlet 4 as treated water and has not permeated through the membrane. Is discharged from the concentrated water outlet 6.

In FIGS. 1 and 2, V ₄ , V _4A , V _4B , V ₅ , and V ₆ indicate valves provided at the respective entrances and exits.

  In order to clean such UF membrane modules 10A and 10B, the UF membrane module is attached to the cleaning equipment, and the cleaning chemical solution is injected from the treated water outlet, the concentrated water outlet, or the feed water inlet, and finally the chemical cleaning is performed. Finish and wash with ultra pure water. After a series of cleaning steps, the UF membrane module is removed from the cleaning facility and shipped.

  When removing the UF membrane module from the cleaning facility, the module container of the UF membrane module is filled with ultrapure water as the final cleaning water. Conventionally, since such a UF membrane module is removed from the cleaning equipment as it is, when the UF membrane module is removed from the cleaning equipment, as shown by an arrow A in FIGS. The ultrapure water filled in the container flows out, and at the same time, the air in the atmosphere is sucked into the container 1 as indicated by the arrow B. As a result, there is a problem that the container 1 is contaminated by the air flowing in. .

  That is, the atmosphere air in the cleaning chamber of a general UF membrane module contains dust (fine particles of metals, other various inorganic or organic components), viable bacteria, etc., and such air is used as the UF membrane. When flowing into the container of the module, these fine particles adhere to the UF membrane in the container and the inner wall of the container, resulting in fine particle contamination. In addition, the measurement result of the fine particles of the atmospheric air in the cleaning chamber of a general UF membrane module is as shown below.

<Measurement results of fine particles in the atmosphere air of the UF membrane module cleaning room (Unit: Individual / Cubic Feet)>
Fine particles having a diameter of 0.3 μm or more and less than 0.5 μm (average value): 6119
Fine particles having a diameter of 0.3 μm or more and less than 0.5 μm (minimum value): 0
Fine particles having a diameter of 0.3 μm or more and less than 0.5 μm (maximum value): 67360
Fine particles having a diameter of 0.5 μm or more (average value): 822
Fine particles with a diameter of 0.5 μm or more (minimum value): 0
Fine particles having a diameter of 0.5 μm or more (maximum value): 960

  In the UF membrane module 10 </ b> B shown in FIG. 2, the air flowing in from the concentrated water outlet 6 only flows through the outer surface side (concentrated water side) of the UF membrane 2 toward the feed water inlet 5, and enters the UF membrane 2. However, in the UF membrane module 10A shown in FIG. 1, in addition to the air flowing from the concentrated water outlet 6 to the feed water inlet 5, the air flowing from the treated water outlet 4A is treated by the treated water outlet 4B. As a result of circulating through the hollow fiber UF membrane 2 toward the surface, not only the outer surface side (concentrated water side) but also the inner surface side (treated water side) of the UF membrane 2 may be contaminated.

  When a UF membrane module with particulate contamination is used in a UF membrane device as a final treatment device at the end of an ultrapure water production apparatus, water from the upstream side is contaminated by circulating this UF membrane device, Depending on the degree of contamination, the required water quality as ultrapure water may not be satisfied. Normally, when the production of ultrapure water is started by the ultrapure water production apparatus, impurities (metal ions, etc.) are released from the apparatus constituting the ultrapure water production apparatus by elution, etc., and treated water (ultrapure water). In order to prevent contamination in water), after assembly and installation of ultrapure water production equipment, prior to the start of ultrapure water production, circulation cleaning is performed to circulate wash water to each device. If the UF membrane module incorporated in the container is contaminated, there will be a problem that the time required for this circulation cleaning is long, or the rise time from the start of production of ultrapure water to the sampling of ultrapure water becomes long. .

  Conventionally, several proposals (for example, Patent Document 1) have been made on a method for cleaning a UF membrane module after being incorporated into an ultrapure water production apparatus. No countermeasures have been considered for contamination due to air suction as described above at the end of cleaning in the module cleaning process.

  That is, for example, in Patent Document 2, in order to reduce the time required for the circulation cleaning after the installation of the ultrapure water production apparatus, the UF membrane used in this ultrapure water production apparatus is subjected to acid cleaning, and then ultrapure water is used. Although a method for pre-cleaning the UF membrane to be cleaned in the above method has been proposed, after the ultrapure water cleaning, there has been no study on contamination due to air suction when the UF membrane module is removed from the cleaning facility.

JP-A-10-296060 JP 2002-301052 A

  The present invention solves the above-mentioned conventional problems, prevents contamination due to air suction at the end of cleaning in a cleaning process before incorporating the UF membrane module into the ultrapure water production apparatus, and provides a highly clean UF membrane module. It is an object of the present invention to provide a method for cleaning a UF membrane module that can supply UF.

  As a result of intensive studies to solve the above problems, the present inventor has pushed out ultrapure water in the UF membrane module with a clean gas and discharged it at the end of cleaning of the UF membrane module. It has been found that the air in the atmosphere accompanying the outflow of ultrapure water in the inside is prevented from flowing into the UF membrane module, and the problem of contamination by air can be solved.

  The present invention has been achieved on the basis of such findings, and the gist thereof is as follows.

[1] In a method of cleaning a UF membrane module used in an ultrapure water production apparatus, after cleaning using ultrapure water as the final cleaning water, the ultrapure water in the module is pushed out by a clean gas and discharged. A method for cleaning a UF membrane module.

[2] A method for cleaning a UF membrane module according to [1], wherein the clean gas is nitrogen gas.

[3] A cleaning method for a UF membrane module according to [2], wherein the purity of the nitrogen gas is 99.99% or more.

[4] The method of cleaning a UF membrane module according to any one of [1] to [3], wherein the UF membrane module is a UF membrane module installed at a terminal of an ultrapure water production apparatus.

  In the cleaning method of the UF membrane module of the present invention, after cleaning using ultrapure water as the final cleaning water, the ultrapure water in the module is pushed out by a clean gas and discharged. The problem of the inflow of air in the atmosphere accompanying the outflow and the resulting contamination in the module is solved (claim 1).

  In the present invention, the clean gas is preferably nitrogen gas, particularly nitrogen gas having a purity of 99.99% or more (claims 2 and 3).

  The cleaning method for a UF membrane module of the present invention is a cleaning method for a UF membrane module installed especially at the terminal of an ultrapure water production apparatus. It is possible to shorten the time or shorten the apparatus start-up period leading to the water sampling at the beginning of ultrapure water production (Claim 4).

It is typical sectional drawing which shows an example of a structure of a general hollow fiber UF membrane module. It is typical sectional drawing which shows the other example of a structure of a general hollow fiber UF membrane module.

  Embodiments of the method for cleaning a UF membrane module of the present invention will be described in detail below.

  The cleaning method for the UF membrane module according to the present invention is performed by attaching the UF membrane module to a cleaning facility before incorporating it into an ultrapure water production apparatus, performing various chemical cleaning as required, and then performing final cleaning with ultrapure water. Before removing the cleaned UF membrane module from the cleaning facility, clean gas is introduced into the module, the ultrapure water in the module is pushed out and discharged, and the ultrapure water in the module is removed from the clean gas (hereinafter referred to as clean gas). , This gas is sometimes referred to as “extruded gas”).

  In the present invention, the clean gas used for extrusion of ultrapure water in the module is not particularly limited, but nitrogen gas having a purity of preferably 99.9% or more, more preferably 99.99% or more is preferably used.

The supply pressure of the extrusion gas to the module is preferably 0.3 MPa or less in order to prevent the UF membrane module from being damaged by supplying the extrusion gas. However, if the supply pressure is excessively low, the extrusion efficiency of ultrapure water is poor. Therefore, the supply pressure of the extrusion gas is preferably 0.1 MPa or more, for example, 0.2 to 0.3 MPa.
Therefore, if necessary, it is preferable to provide a pressure reducing valve or the like in the supply line of the extruded gas to adjust the supply pressure of the extruded gas.

  The cleaning method for the UF membrane module of the present invention is carried out in the same manner as the conventional UF membrane module cleaning method, except that, at the end of cleaning, the extrusion gas is supplied and the ultrapure water in the module is pushed out and discharged. The cleaning equipment used for cleaning the UF membrane module is not particularly limited as long as it includes at least an extrusion gas supply line and ultrapure water supply and discharge lines to the UF membrane module.

  In the method for cleaning a UF membrane module of the present invention, normally, ultrapure water as cleaning water is pumped to the water supply inlet and / or the treated water outlet of the UF membrane module, and when the ultrapure water in the module is extruded, This is carried out by pumping an extruded gas from the treated water outlet and concentrated water outlet of the module and discharging ultrapure water from the feed water inlet and / or the treated water outlet.

  Below, the procedure of the extrusion method of the ultrapure water in the module by this invention is demonstrated about UF membrane module 10A, 10B shown to FIG. 1, 2, respectively.

{Procedure I: UF membrane module 10A shown in FIG. 1}
The ultrapure water filled in the module is extruded and discharged by the following procedure.
(1) From the state in which the valves V _4A , V _4B , V ₅ , and V ₆ are closed, the valve V _4A of the treated water outlet _4A and the valve V _4B of the treated water outlet 4B are opened, and the treated water outlet 4A The extruded gas is put into the module container 1 and ultrapure water is extruded and discharged from the treated water outlet 4B. Thereafter, the supply of the extrusion gas is stopped, and the valves V _4A and V _4B of the treated water outlets 4A and _4B are closed.
(2) with opened valve V ₅ of the feed water inlet 5 and valve V ₆ of concentrated water outlet 6, placed extrusion gas into the module container 1 from concentrated water outlet 6 to discharge extruded from the ultrapure water feed water inlet 5. Thereafter, the supply of the pushing gas is stopped, and the valve V ₆ of the concentrated water outlet 6 and the valve V 5 of the feed water inlet ₅ are closed.
Thereafter, the UF membrane module 10A is removed from the cleaning facility.
Note that the above procedures (1) and (2) may be performed in reverse.

{Procedure II: UF membrane module 10B shown in FIG. 2}
The ultrapure water filled in the module is extruded and discharged by the following procedure.
(1) From the state in which the valves V ₄ , V ₅ , and V ₆ are closed, the valve V ₆ of the concentrated water outlet 6 and the valve V 5 of the feed water inlet ₅ are opened, and the gas extruded from the concentrated water outlet ₆ is supplied to the module container 1. The ultrapure water is pushed out from the water supply inlet 5 and discharged. Thereafter, the supply of the pushing gas is stopped, and the valve V ₆ of the concentrated water outlet 6 and the valve V 5 of the feed water inlet ₅ are closed.
Thereafter, the UF membrane module 10B is removed from the cleaning facility.

  When the UF membrane module is removed from the cleaning equipment by the above procedures I and II, atmospheric air does not flow into the module container 1, and the UF membrane module immediately after cleaning is pushed out of the module container 1 with gas. It can be shipped in the state of high cleaning that has been filled and used for assembling an ultrapure water production apparatus at the site of use.

  For this reason, the ultrapure water produced by the ultrapure water production apparatus using this UF membrane module has no problem of contamination derived from the UF membrane module, and has a high purity. Even when circulating cleaning is performed in advance, the cleaning time can be shortened, and the apparatus start-up period leading to sampling of ultrapure water at the start of production of ultrapure water can be shortened.

  In the present invention, as described above, since the module is prevented from being contaminated by the suction of the atmosphere air by the extrusion discharge of the ultrapure water by the extrusion gas, the atmosphere air in the cleaning work space of the UF membrane module is highly clean. There is no need, and the present invention can be applied in a normal atmospheric work environment. However, it is desirable to perform a series of cleaning operations in a green room when implementing the present invention in preparation for an unexpected accident such as contamination from a leaked portion of a pipe.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

<Example 1>
A hollow fiber UF membrane module having a structure shown in FIG. 1 (diameter 1 mmφ, manufactured by polysulfone, molecular weight cut off 6,000) 10A was washed with a 0.5 wt% hydrochloric acid aqueous solution and then finished with ultrapure water. Thereafter, in a state where the module was filled with ultrapure water, ultrapure water in the module was extruded using nitrogen gas having a purity of 99.99% by the procedure of I described above. The supply pressure of nitrogen gas was 0.2 MPa.

Remove the UF membrane module that pushed out the ultrapure water from the cleaning equipment, and pass ultrapure water through the UF membrane module at a flow rate of 15 m ³ / h to check the contamination status of the UF membrane module. It evaluated by calculating | requiring the difference ((DELTA) metal concentration = UF membrane permeated water-UF membrane water supply) of various metal ion concentrations of ion concentration and UF membrane water supply (ultra pure water). In addition, the various metal density | concentration in water was measured by ICP-MS.
The results are shown in Table 1.

<Comparative Example 1>
After the UF membrane module was cleaned in the same manner as in Example 1, the UF membrane module was removed from the cleaning equipment without extruding ultrapure water with nitrogen gas. When the UF membrane module was removed, air in the atmosphere flowed into the module with the outflow of ultrapure water in the module.
For this UF membrane module, the contamination status was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

  From Table 1, it can be seen that according to the present invention, a highly clean UF membrane module with significantly reduced contamination at the end of cleaning can be supplied.

DESCRIPTION OF SYMBOLS 1 Module container 2 Hollow fiber UF membrane 3A, 3B Adhesive resin 4, 4A, 4B Treated water outlet 5 Feed water inlet 6 Concentrated water outlet 10A, 10B UF membrane module

Claims (4)

  In the method of cleaning the UF membrane module used in the ultrapure water production apparatus, after cleaning using ultrapure water as the final cleaning water, the ultrapure water in the module is pushed out by a clean gas and discharged. A method for cleaning a UF membrane module.   2. The method for cleaning a UF membrane module according to claim 1, wherein the clean gas is nitrogen gas.   The method for cleaning a UF membrane module according to claim 2, wherein the purity of the nitrogen gas is 99.99% or more.   4. The method of cleaning a UF membrane module according to claim 1, wherein the UF membrane module is a UF membrane module installed at a terminal of an ultrapure water production apparatus.

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