JP3231606B2 - Ultrapure water production equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for producing pure water or ultrapure water, and is not limited thereto. For example, it is used in an industrial field such as an electronic parts manufacturing industry for manufacturing semiconductor substrates (wafers) and the like. And an apparatus for producing pure water or ultrapure water.

[0002]

2. Description of the Related Art Hitherto, high-purity water, which has been removed as much as possible from fine particles, colloidal substances, organic substances, metals, anions, etc., has been used as cleaning water for cleaning objects which are required to obtain extremely clean surfaces such as semiconductor wafers. Water, generally called ultrapure water, is used. The high-purity water described by the terms “pure water” and “ultrapure water” is not necessarily clearly defined, but in general,
A pretreatment device for removing raw water using a coagulating sedimentation device, a sand filtration device, etc., followed by an activated carbon filtration device, a reverse osmosis membrane device,
Purified water or primary purified water from which impurities in pretreatment water have been removed using a three-bed ion exchange device, vacuum degassing device, desalting device, precision filter, etc., is called pure water, and this primary pure water is further irradiated with ultraviolet rays. Using equipment, mixed-bed polishers, ultrafiltration membrane devices, and membrane treatment devices such as reverse osmosis membrane devices, etc., it is possible to remove impurities such as fine particles, colloidal substances, organic substances, metals, ions, etc., remaining in primary purified water in trace amounts. What has been removed as much as possible is often referred to as ultrapure water.

[0003] In such an apparatus for producing ultrapure water, a membrane treatment apparatus such as an ultrafiltration membrane (UF membrane) or a reverse osmosis membrane (RO membrane) is installed not only at the end of the secondary pure water system. However, there has been a problem that this membrane processing apparatus causes a decrease in yield due to contamination. In particular, when the oxidizing device such as an oxidizing agent adding device, an ultraviolet oxidizing device, and an ozone oxidizing device is included in the apparatus regardless of the primary system or the secondary system, the R0 film and the UF film are contaminated on the film surface by long-term continuous use. Substances may accumulate, the pressure loss may increase, and the amount of permeated water may decrease, and it has been found that the yield of the membrane treatment apparatus decreases very early depending on the apparatus.

[0004] When such a decrease in yield is caused, the membrane is usually washed and recovered when the pressure loss reaches a predetermined value. The frequency of the cleaning operation is various because the period during which the pressure loss increases varies from device to device, and there are various types of devices. Cleaning may be required once every 10 days. The reason why the frequency of washing varies greatly depending on the equipment is as an example of examining the causal relationship between the difference in raw water and the equipment configuration, and the relationship between the silica concentration and the hardness component concentration in the water to be treated and the number of bacteria has been reported. Even in recent ultrapure water production equipment in which measures against these have already been sufficiently taken, an example of an early decrease in yield is found, and the reason for this has not always been clarified.

In recent years, construction costs, maintenance costs, and maintenance costs of the apparatus have increased significantly along with the demand for water quality improvement required for ultrapure water, and the pressure loss has been recovered even if periodic cleaning is repeated. If not, the replacement of the membrane or the like is required, so that a large amount of cost tends to be spent on cleaning and replacing the membrane. Therefore, in order to reduce the burden of replacing the R0 membrane and the UF membrane, which occupy a large part of the maintenance and maintenance costs, and replacing the ion exchange resin, it is required to extend the usable period of these members.

Conventionally, as a technique for preventing membrane contamination to reduce the frequency of cleaning the membrane from such a viewpoint, Japanese Patent Publication No. 1-4275 using a combination of a sterilizer and an ion exchanger is known.
No. 4 publication proposes a method.

[0007]

However, the above method is
It is difficult to apply it to the primary pure water system because it uses a combination of a sterilizer and an ion exchange device, and even if this method is applied to a secondary pure water system, the expected effect is obtained depending on the device. It has been found that the case where is not obtained, so a more effective solution has been required.

The inventor of the present invention concluded that the cause of the early decrease in the yield of the membrane apparatus is that a substance contaminating the membrane apparatus cannot be sufficiently removed by the apparatus at the preceding stage of the conventional membrane apparatus, and the membrane is operated at a particularly high recovery rate. Under the premise that the results are to contaminate the equipment, various points that have not been studied in the past for the purpose of preventing a decrease in the yield of the membrane treatment equipment in the ultrapure water production equipment and reducing the frequency of cleaning the membrane treatment equipment The present inventors have made detailed studies and arrived at the present invention.

That is, in a conventional ultrapure water production apparatus, a cartridge polisher (a non-regenerative mixed-bed type ion exchange apparatus) is provided in front of a membrane processing apparatus generally installed at the last stage of a secondary processing system. The average particle size of the strongly basic anion exchange resin among the ion exchange resins to be filled in the cartridge polisher is too small. From the viewpoint that a pump is required, the particle size is generally 0.6 m.
A strongly basic anion exchange resin in the range of 0.55 mm to 0.65 mm centering around m has been used.

[0010] Even in an ultrapure water production apparatus in which such a cartridge polisher filled with a strong basic anion exchange resin having an average particle diameter of about 0.6 mm is installed in the preceding stage of the membrane apparatus, It has been found that, in an ultrapure water production apparatus of the type equipped with an oxidation treatment apparatus, the above-mentioned membrane apparatus often causes an early decrease in yield. Therefore, the present inventor estimated that in an ultrapure water production apparatus equipped with an oxidation treatment apparatus, membrane contaminants that would pass through the cartridge polisher would be generated, and the particle size of the ion exchange resin charged in the cartridge polisher was varied. As a result of the investigation, it has been found that by specifying the particle size of the strongly basic anion exchange resin within a range that can be effectively carried out industrially, it is possible to extremely effectively achieve the purpose of preventing a decrease in the yield of the membrane device.

[0011]

The ultrapure water production apparatus according to the present invention which achieves the above object is characterized by an oxidizing means for oxidizing a substance contained in water to be treated, and an oxidizing means for the oxidizing means. In an ultrapure water production apparatus having a desalination device provided at a subsequent stage and a membrane treatment device further provided at a stage subsequent to the desalination device, an average particle diameter is provided between the oxidation treatment means and the membrane treatment device. An ion exchange device filled with a strongly basic anion exchange resin of 0.5 mm or less is provided.

In the above, the oxidizing treatment means adding an oxidizing agent such as sodium hypochlorite, chloramine, ozone, hydrogen peroxide solution to the water to be treated continuously or intermittently, or applying ultraviolet rays or the like to the water to be treated. Oxidation means used for these treatments is a device that adds an oxidizing agent or a device that oxidizes and decomposes impurities such as organic substances and colloidal substances in water by irradiating ultraviolet rays. Can be mentioned.

The desalting apparatus used in the present invention includes:
A conventionally known apparatus such as an ion exchange resin apparatus or an electric regeneration type desalination apparatus using an ion exchange membrane and an ion exchange resin can be used, but is not particularly limited thereto. In the case of the primary pure water treatment system, various types used in combination with a reverse osmosis membrane can be mentioned.
B), double-bed type (2B3T etc.) and the like. In the secondary pure water treatment system, a non-regenerative type is generally used in many cases.

The above-mentioned ion exchange apparatus of the present invention can be provided separately from the above-mentioned desalination apparatus, and the desalination apparatus itself is filled with a strongly basic anion exchange resin having an average particle diameter of 0.5 mm or less. It can also be used as a device.
Specifically, when the strongly basic anion exchange resin of the regenerative mixed-bed type ion exchange device installed before the reverse osmosis membrane of the primary pure water treatment system has an average particle diameter in the above range, the secondary pure water is used. For example, when the strong basic anion exchange resin of the cartridge polisher (non-regenerative mixed bed type ion exchange device) installed in the last stage of the treatment system before the ultrafiltration membrane has an average particle size in the above range. Preferred examples can be given.

In the ion exchange apparatus which is a feature of the present invention, the strong basic anion exchange resin has an average particle diameter of 0.5.
The term "mm or less" means that the average particle diameter is 0.5 mm or less, and the particle diameter given by the size of the sieve opening where 50% by volume of the total volume remains is preferably 0.5 mm or less. Those having a range of 5 mm are desirable. When the average particle size exceeds 0.5 mm, the pressure loss in the membrane processing device increases early as can be seen in the following Examples and Comparative Examples. That is, it is not preferable because the yield tends to decrease. As the particle size distribution of the strongly basic anion exchange resin, the uniformity coefficient of the index representing the range of variation is about 1.0 to 1.6,
Preferably, those having a thickness of 1.0 to 1.3 are used. If the uniformity coefficient exceeds 1.6, the pressure loss tends to increase, which is not preferable. It is preferable that the uniformity coefficient be as close to 1.0 as possible. However, considering the increased burden of classification and the like, a coefficient of about 1.1 or more can be used effectively.

The method for measuring the average particle size or the uniformity coefficient in the present invention is usually carried out as follows.

First, a column is filled with about 1 liter of a strongly basic anion exchange resin to be treated, and backwashed with water to remove bubbles in the resin layer, and then a sodium hydroxide solution (1N)
After 1.5 liters of the drug are passed at a flow rate of about SV4 and then 1 liter / liter-pure water of the resin is flowed and extruded at the same flow rate, the pure water is passed through the SV10 for 20 minutes for washing.

Next, 8 liters of 0.2N hydrochloric acid was added to SV5
After passing the medicine back and forth, followed by flowing and extruding 1 liter / liter-resin pure water at the same flow rate, the substrate is sufficiently washed with pure water.

Approximately 100 ml of the strongly basic anion exchange resin whose ion form was changed to Cl form by the above operation was collected.
ISZ 8801 (standard screen sieve) aperture 1400
μm, 1180 μm, 1000 μm, 850 μm, 60
0 μm, 425 μm, 355 μm, 300 μm, 250
The sieving operation is performed as follows using μm and 212 μm.

That is, the above-mentioned sieve is successively stacked on the tray in such a manner that the openings become finer downward, and the collected strong basic anion exchange resin is put into the uppermost sieve. After gently pouring pure water into the uppermost sieve for about 2 minutes, the uppermost sieve (eg, 1400 μm) is washed out, and placed on a white plate.

Water is poured onto the flat plate so that about half the depth of the sieve is immersed. The sieve is then gently moved up and down and horizontally to sift. The above-mentioned sieving is performed until the number of resin particles passing through the sieving surface becomes about 10 or less, and the sieving of the passed sample resin is similarly performed using a sieve of the next mesh size.

The sieves are screened in this manner, and the wet volume of the sample resin remaining on each sieve is measured with a measuring cylinder or the like, and recorded in the record table shown in Table 1.

Next, the vertical axis of the log probability graph is sieved, and the horizontal axis is the sieved residue percentage total. Each point is plotted, and a straight line is drawn that satisfies each point as much as possible.

With respect to this straight line, the values of the sieve openings corresponding to the residual volume percentage cumulative values of 90% and 40% are detected on the graph, and the sieve openings corresponding to 40% and 90% are determined. Is the uniformity factor.

In the present invention, the average particle size is determined by conducting a sieving test as described above, and the average particle size given by the size of the sieve opening where 50% by volume of the total volume remains is defined as the average particle size. The fact that it is 5 mm or less is as described above.

[0026]

[Table 1]

As the strongly acidic cation exchange resin used together with the strongly basic anion exchange resin, those which have been conventionally used generally (for example, an average particle size of 0.55 to 0.55)
0.68 mm) can be used.

With respect to the other configuration of the ultrapure water production apparatus, a conventionally known configuration can be used without any particular limitation.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. 1 shows an example in which the present invention is applied to a secondary pure water treatment system.

In the apparatus shown in FIG. 1, raw water is pre-treated by a pre-treatment device 1 comprising known turbidity means and the like, and then subjected to primary pure water treatment in a primary pure water treatment system 2 to form a pure water tank 3.
Is stored. The primary pure water stored in the pure water tank 3 is then sent to a secondary pure water treatment system, where low-pressure mercury lamps capable of irradiating ultraviolet rays having a wavelength of about 185 nm for generating radicals in water and oxidatively decomposing organic substances are provided. Are sequentially passed through a UV oxidizing device 4 containing a water purifier, a cartridge polisher 5 as a desalination device, and an ultrafiltration membrane device 6 as a membrane treatment device, and are treated with secondary pure water.
Water is sent to A part of the secondary pure water is returned to the pure water tank 3 by the circulation path 7.

In the above configuration, the cartridge polisher 5 installed before the ultrafiltration membrane device 6 is a mixture of a strongly basic anion exchange resin having an average particle diameter of 0.5 mm or less and a strongly acidic cation exchange resin. It is configured as a non-regenerative mixed bed type made of resin, and the reduction of the yield of the ultrafiltration membrane is prevented.

Embodiment 2 FIG. 3 shows an example in which the present invention is applied to a primary pure water treatment system.

In the apparatus shown in FIG. 3, in the raw water flowing into the clarifier 11 composed of a sand filter provided with a coagulation treatment device, microorganisms grow in the clarifier 11 to form slime and pressure loss. Sodium hypochlorite is added by an oxidizing agent adding device 12 installed at the entrance of the clarifier, and a double-bed demineralizer (2B3T) Sodium bisulfite is added by a reducing agent adding device 13 installed at the inlet to reduce the remaining oxidizing agent.

The water to be treated, which has been desalinated in the double-bed desalination apparatus 14, passes through a vacuum deaerator 15, a regenerative mixed-bed ion exchange apparatus 16, and a reverse osmosis membrane apparatus 17, and then is subjected to primary pure water. And stored in the pure water tank 18.

The primary pure water stored in the pure water tank 18 is then subjected to secondary pure water treatment through, for example, the ultraviolet oxidizing apparatus, the cartridge polisher, and the ultrafiltration membrane described in Embodiment 1, and then sent to the place of use. Is done.

In this embodiment, the reverse osmosis membrane device 17 is used.
The particle size of the strongly basic anion exchange resin of the regenerative mixed bed type ion exchange device 16 installed before the above is a strong basic anion exchange resin having an average particle size of 0.5 mm or less, and a strongly acidic cation exchange resin. To prevent the yield of the reverse osmosis membrane device 17 from decreasing.

The configuration of the apparatus of the present invention is not limited to those described above with reference to FIGS. 1 and 3. For example, a coagulation / sedimentation apparatus may be installed in the primary pure water treatment system or may be installed alone. Equipped with a filtering device filled with granular fillers such as sand, a membrane treatment device, etc., in which the microorganisms proliferate into slime, increasing the pressure loss. In order to prevent this, an oxidizing agent such as sodium hypochlorite and chloramine is added by an oxidizing agent adding device installed at the inlet of the clarifier, and the oxidizer is added to the inlet of the desalter (here, 2B3T) following the clarifier. A reducing agent such as sodium bisulfite is added by the installed reducing agent addition device, and the remaining oxidizing agent can be reduced.In addition to the reducing agent added by the reducing agent addition device, activated carbon is filled. Install activated carbon tower Such as the formation, it may also be implemented as various modified embodiments.

[0038]

【Example】

Example 1 A strongly basic anion exchange resin having an average particle diameter (diameter R [mm]) shown in FIG. 2 and a usual strong acidic cation were respectively added to the cartridge polisher 5 of the ultrapure water production apparatus shown in FIG. Mixed and charged with an exchange resin (average particle size 0.55 to 0.68),
The increase in pressure loss over time of the ultrafiltration membrane device 6 was measured, and the results are shown in FIG.

The anion exchange resin of each average particle size in the figure is Amberlite IRA-402BL (average particle size of 0.
(55 mm). The uniformity coefficient of the resin adjusted to each particle size was 1.3 or less. Amberlite IR mixed and filled strongly acidic cation exchange resin
-124 (average particle size: 0.63 mm) was used.

As is clear from the results of FIG. 2, by using a strong basic anion exchange resin having a small average particle size,
It was confirmed that the rise in pressure loss of the ultrafiltration membrane device 6 can be reduced.

In this apparatus, in place of the ultraviolet oxidizing apparatus 4, an ultraviolet sterilizing apparatus having no ability to irradiate a wavelength near 185 nm (it has no ability to generate radicals in water because it can irradiate only to a wavelength around 254 nm) ) Was installed, it was confirmed that the pressure loss of the ultrafiltration membrane device did not increase for 360 days or more. However, since there was no oxidizing ability, the TOC concentration in the ultrapure water increased. .

Comparative Example 1 As a comparative example of Example 1, the cartridge polisher 5 of FIG. 1 was filled with Amberlite IRA-402BL (average particle size: 0.55 mm) having a commonly used particle size, and the pressure was increased. The loss rise curve is shown in comparison with FIG. When a resin having a large particle diameter is used, the pressure loss of the ultrafiltration membrane device is increased earlier than in the strongly basic anion exchange resin of the example.

Example 2 A regenerated mixed bed type ion exchange device 16 installed in front of the reverse osmosis membrane device 17 of FIG. 3 was charged with a strongly basic anion exchange resin whose average particle size was adjusted in the same manner as in Example 1. Mixed with the same strongly acidic cation exchange resin as in Example 1, and the reverse osmosis membrane device 17 was used.
Of the pressure loss over time was measured, and the results are shown in FIG.

As is clear from the results shown in FIG. 4, it was confirmed that the use of a strong basic anion exchange resin having a small particle diameter can reduce an increase in pressure loss of the reverse osmosis membrane device.

In this apparatus, the oxidizing agent adding device 12
When the addition of the oxidizing agent in (1) was stopped (the reducing agent was added), it was found that the pressure loss of the reverse osmosis membrane device 17 did not increase for 360 days or more. Since the loss increased, it was necessary to wash the filter by adding sodium hydroxide about once every two weeks.

Comparative Example 2 As a comparative example of Example 2, an Amberlite IRA-402BL (average particle size: 0.55 mm) was charged into a regenerative mixed bed type ion exchange apparatus shown in FIG. 3 and the rise in pressure loss was measured. The results are shown in FIG. This indicates that the pressure loss of the reverse osmosis membrane device increases earlier when a resin having a large particle diameter is used as compared with the strongly basic anion exchange resin of Example 2.

[0047]

According to the present invention, in an ultrapure water production apparatus equipped with an oxidation treatment device and a reduction treatment device, the particle size of the strongly basic anion exchange resin to be charged into an ion exchange device such as a cartridge polisher is determined. By using the particles having an average particle size of 0.5 mm or less, which is a range that can be effectively implemented industrially, it is possible to reduce an increase in pressure loss of the membrane processing apparatus and to prevent a decrease in yield. .

[Brief description of the drawings]

FIG. 1 is a flowchart showing a configuration outline of an ultrapure water production apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing measurement results of Example 1 and Comparative Example 1.

FIG. 3 is a flowchart showing a configuration outline of an ultrapure water production apparatus according to a second embodiment of the present invention.

FIG. 4 is a diagram showing measurement results of Example 2 and Comparative Example 2.

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁷ Identification code FI C02F 9/00 503 C02F 9/00 503B 1/42 1/42 A 1/44 1/44 J (58) .Cl. ⁷ , DB name) C02F 9/00 502 C02F 1/42 C02F 1/44

Claims (4)

(57) [Claims] 1. An oxidation treatment means for oxidizing a substance contained in water to be treated, a desalination device provided at a stage subsequent to the oxidation treatment means, and further provided at a next stage of the desalination device. In an ultrapure water production apparatus having a membrane treatment device, an average particle size of 0.5 is provided between the oxidation treatment means and the membrane treatment device.
An apparatus for producing ultrapure water, comprising an ion exchange device filled with a strongly basic anion exchange resin having a diameter of not more than 1 mm. 2. The apparatus for producing ultrapure water according to claim 1, wherein the uniformity coefficient of the strongly basic anion exchange resin charged in the ion exchange apparatus is 1.0 to 1.6. 3. A primary pure water treatment system for removing a suspended substance from raw water and then removing ionic and nonionic substances to obtain pure water in a primary stage, and a secondary pure water treatment for treating primary pure water. In the ultrapure water production apparatus provided with a secondary pure water treatment system,
A super-characteristic comprising at least an ultraviolet oxidation device, an ion exchange device filled with a strongly basic anion exchange resin having an average particle size of 0.5 mm or less, and a membrane treatment device along a flow direction of treated water. Pure water production equipment. 4. The method according to claim 1, wherein
An ultrapure water production apparatus, wherein the ion exchange apparatus is a cartridge polisher.