JPS62110795A - Device for producing high-purity water - Google Patents

Abstract

PURPOSE:To efficiently produce high-purity water by using a disinfectant, a means for adding a pH regulator, the first reverse osmosis membrane separator, an activated carbon adsorption tower, the second reverse osmosis membrane separator, etc., to treat raw water. CONSTITUTION:A disinfectant and/or a pH regulator are added while raw water pretreated with activated carbon, etc., is supplied to a degasification tower 1 through a pipeline 11. The raw water is treated by the first reverse osmosis membrane separator 2. The permeated water is then treated with activated carbon in the activated carbon adsorption tower 3. The treated water is subsequently treated by the second reverse osmosis membrane separator 4. The permeated water of the reverse osmosis membrane separator 4 is taken out, and the concentrated water of the reverse osmosis membrane separator 4 is returned to the raw water supply system of the reverse osmosis membrane separator 2. Consequently, the troubles in the conventional water purifying device provided with an ion-exchange device are eliminated and high-purity water can be efficiently produced.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the production of high-purity water that continuously produces pure water or so-called ultrapure water, which is widely used in semiconductor manufacturing factories, nuclear power plants, etc. Regarding equipment.

[Prior Art] In the manufacture of LSIs and VLSIs, large amounts of pure water and ultrapure water are used. Ultrapure water is pure water having a specific resistance of 17 to 18 MΩ·cm, which is extremely close to the specific resistance of theoretically pure water (water consisting only of H2O), which is 18.24 MΩ·cm.

A conventional ultrapure water production apparatus is composed of a pretreatment system A, a primary pure water system B, and a subsystem C, as shown in FIG. In the apparatus shown in Fig. 2, raw water such as city water, industrial water, or well water is filtered with activated carbon, sand, or other filter media, or subjected to coagulation and sedimentation treatment in the pretreatment system A. The water is subjected to a combination of treatments, etc., and then sent to the primary pure water system B.

The primary pure water system B includes a reverse osmosis (RO) device 21, a cation exchange tower, and an anion exchange tower (a decarboxylation tower (not shown) is installed between both exchange towers to reduce the burden on the anion exchange resin).
), and a mixed bed tower 2 which is a mixed ion exchange treatment device using a cation exchange resin and an anion exchange resin to further improve the purity of treated water.
Consists of 3. The treated water from the mixed bed tower 23 is finally treated in a subsystem C consisting of an ultraviolet sterilizer, a non-regenerative ion exchanger, an ultrafilter, etc., to obtain ultrapure water. The produced ultrapure water is sent to points of use such as wafer cleaning processes.

In the conventional apparatus shown in FIG. 2, the details of the configuration of the primary pure water system B are as shown in FIG. As shown in FIG. 3, the pretreated raw water is subjected to membrane separation treatment in a reverse osmosis device 21 after adding HOCI and acid. This permeated water is treated with N a HS in order to remove residual chlorine contained therein by reducing action.
After the O3 is added, it is sent to the ion exchanger 22. This ion exchange device 22 is of a two-bed, three-column type, with two lines of ion exchange columns installed, including a cation exchange column (H column).
31a and 31b, degassing tower 32, anion exchange tower (O
H tower) consists of 33a and 33b. Cation tower 31a,
Two anion columns 33a and 33b are each provided in parallel, but even when one is regenerating, the other is used for processing, so that pure water can be extracted without stopping operation. This is to ensure continuous water supply. In addition, 34
35 is a cation column regenerator, and 35 is an anion column regenerator. The treated water of the ion exchanger 22 is treated in the mixed bed tower 23, as described above, and then sent to the subsystem. Note that the ion exchange resin in this mixed bed column 23 also needs to be regenerated, but the frequency of regeneration is lower than that of the anion column and cation column of the ion exchange device 22 in the previous stage, and it is necessary to regenerate it when the point of use is suspended. Therefore, there is no particular need to provide them in parallel.

[Problems to be Solved by the Invention] Such conventional pure water production apparatuses have the following problems because the primary pure water system is equipped with an ion exchange device.

(2) Ion exchange equipment requires regeneration of the ion exchange resin once every 1 to 5 days on average, and equipment for regeneration is essential. Further, it is impossible to continuously operate a single device composed of only 1 series, and in the case of a single device, the operation must be stopped and regeneration is performed.

(2) Continuous operation is possible if two ion exchange devices are arranged in rows as shown in FIG. 2, but even in this case, the regenerator etc. cannot be omitted and the regenerator is consumed.

■ There is a possibility that the eluate from the ion exchange resin of the ion exchange device in the front stage may have an adverse effect on the rear stage.

■ Na HS is used for the purpose of eliminating residual chlorine in the ion exchange equipment feed water (reverse osmosis equipment permeate water) by reduction action.
Although O3 is used, this N a HS O3 may deteriorate the ion exchange resin in the subsequent stage.

Means for Solving Problem E] The high-purity water production apparatus of the present invention includes a means for adding a disinfectant and/or a pH adjuster to raw water pretreated with activated carbon, etc. a first reverse osmosis membrane separator that performs a reverse osmosis membrane treatment on raw water to which a conditioning agent has been added; an activated carbon adsorption tower that performs an activated carbon treatment on the permeated water of the first reverse osmosis membrane separator;
A second step in which the treated water of the activated carbon adsorption tower is further treated with a reverse osmosis membrane.
a reverse osmosis membrane separator, a system for taking out the permeated water of the second reverse osmosis membrane separator, and returning concentrated water of the second reverse osmosis membrane separator to the raw water supply system of the first reverse osmosis membrane separator. It is equipped with a system for

That is, in order to solve the above-mentioned conventional problems, the present applicant has proposed a means for adding a disinfectant and/or a pH adjusting agent to raw water pretreated with activated carbon, etc.
a first reverse osmosis membrane separator that performs reverse osmosis membrane treatment on raw water to which an H regulator has been added; a means for adding hydrazine to the permeated water of the first reverse osmosis membrane separator;
a second reverse osmosis membrane separator that further processes the permeated water of the reverse osmosis membrane separator, a system for taking out the permeated water of the second reverse osmosis membrane separator, and a system of the second reverse osmosis membrane separator. We discovered a high-purity water production apparatus comprising a system for returning concentrated water to the raw water supply system of the first reverse osmosis membrane separator, and previously filed a patent application (Japanese Patent Application No. 179,630/1983). (hereinafter referred to as the "first application").

According to the above-mentioned earlier application, it is possible to solve the problems of conventional pure water production equipment equipped with an ion exchange device and efficiently produce ultrapure water of extremely high purity. The device is equipped with a means for adding hydrazine in order to remove residual nitrogen in the permeated water of the first reverse osmosis component #I-device. Since the necessary amount of added acid changes due to changes in SV, etc., addition errors such as over-addition or under-addition are likely to occur, and if an addition error occurs, the second reverse filtration separator 11 is installed at the rear end. This may have a negative effect on the membrane of the Ff, and the stable operation of the Ff may be impaired.

Therefore, based on the above-mentioned application, the inventors of the present invention have conducted repeated studies to develop a device that can produce pure water more easily and stably, and the permeated water of the first reverse filtration membrane separator As a means for removing residual chlorine, they discovered a device equipped with an activated carbon adsorption tower and completed the present invention.

[Function] The high-purity mature tree manufacturing apparatus of the present invention processes raw water, which has been pretreated with city water, industrial water, well water, etc., using a main system consisting of a two-stage reverse osmosis membrane separator. The action of the thread is as follows.

(2) By adding a disinfectant to the raw water, the reverse osmosis membrane of the first reverse osmosis membrane separator is sterilized, and deterioration due to microorganisms and reduction in recovery rate due to slime generation are prevented.

(2) By adding a pH adjuster to the raw water, hydrolysis of the reverse osmosis membrane of the first reverse osmosis membrane separator is minimized, and precipitation of CaCO3 and the like on the membrane surface is prevented.

(2) The water is sufficiently desalinated by the first reverse osmosis membrane separator, and most of the electrolyte in the water to be treated, for example, about 95%, is separated.

(2) Residual chlorine in the permeated water is adsorbed and removed by treating the permeated water of the first reverse osmosis membrane separator with activated carbon in an activated carbon adsorption tower.

■ By adding a pH adjuster to the permeated water of the first reverse osmosis membrane separator, CO2 in the water becomes HC03-, which enables highly efficient removal of carbonic acid components in the second reverse osmosis membrane separator. . Further, since the second reverse osmosis membrane separator is supplied with the low concentration permeate water that has been subjected to the -transformation separation, the desalination performance is extremely high.

(2) Further desalination is performed by the second reverse osmosis membrane separator, and almost all of the electrolyte contained in the raw water, for example, about 98%, is separated. Further, by returning the concentrated liquid to the raw water supply system of the first reverse osmosis membrane separator, the concentrated liquid can be used effectively.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of the high-purity water production apparatus of the present invention.

The apparatus according to the illustrated embodiment includes a degassing tower 1. First reverse osmosis membrane separator 2, activated carbon adsorption tower 3, second reverse osmosis membrane separator 4
and a mixed bed tower 5, and a pipe 11 for feeding raw water pretreated with activated carbon or the like to the degassing tower 1;
A pipe 12 for adding a disinfectant to raw water, a pipe 13 for adding a PH adjuster to the raw water, a pipe 14 for feeding treated water from the degassing tower 1 to the first reverse osmosis membrane separator 2, and a first reverse osmosis Piping 15 that feeds the permeated water of the membrane separator 2 to the activated carbon adsorption tower 3, Piping 16 that feeds the treated water of the activated carbon adsorption tower 3 to the second reverse osmosis membrane separator 4, and the first reverse osmosis membrane separation. Piping 17 for adding a pH adjuster to the permeated water of the second reverse osmosis membrane separator 4, piping 18 for feeding the permeated water of the second reverse osmosis membrane separator 4 to the mixed bed column 5, and concentration of the second reverse osmosis membrane separator 4 It includes a pipe 19 for returning water to the upstream side of the first reverse osmosis membrane separator 2, and a pipe 20 for feeding treated water from the mixed bed tower 5 to subsystems and the like.

The procedure for treating raw water using the apparatus of the present invention will be described below.

As shown in Fig. 1, pretreated water, which is obtained by subjecting raw water such as city water, industrial water, well water, etc. to normal pretreatment such as activated carbon adsorption, is supplied to the degassing tower l through a pipe 11. During the process, a disinfectant and a pH adjuster are added through the pipes 12 and 13.

As the disinfectant added through the pipe 12, a chlorine-based disinfectant such as HOCu or NacJljo is preferably used, and is adjusted and added so that the residual chlorine in the raw water is detected at about 0.5 to ippm.

By injecting this disinfectant, the reverse osmosis membrane of the first reverse osmosis membrane separator 2 at the rear stage is prevented from being deteriorated by microorganisms, and the permeability is prevented from decreasing due to the generation and adhesion of slime. In addition, in small equipment, NaCl0 is used as a disinfectant.
It is preferable to use

The pH adjuster added from the pipe 13 is H2S.
Acids such as O4 and HC1 are used, and the raw water has a pt+ of 4 to 6.
It is adjusted so that By adjusting the pH of the raw water to 4 to 6, hydrolysis of the reverse osmosis membrane in the first reverse osmosis membrane separator 2 in the subsequent stage is minimized, and precipitation of CaCO3 etc. on the membrane surface is also prevented. be done. Further, degassing in the subsequent degassing tower 1 becomes easy.

As a degassing tower l, by placing the raw water in a vacuum,
A vacuum degassing tower that removes dissolved gas, a decarbonation tower that removes dissolved gas by aeration, etc. are used.

By removing the dissolved gas in the raw water using the degassing tower 1, the CO2 component, which has low removal performance by the reverse osmosis membrane, is removed to the maximum extent, increasing the purity of the treated water, and improving the efficiency of the downstream reverse osmosis membrane separator. Unloading is reduced. This degassing tower
In terms of efficient removal of the CO2 component, it is particularly preferable to adjust the pH of the raw water to about 5 to 5.5.

In the present invention, the degassing tower may be provided before the activated carbon adsorption tower 3, but it is not always necessary, and sufficiently high purity water can be produced even if the degassing tower itself is omitted.

The treated water from the degassing tower 1 is sent to the first reverse osmosis membrane separator 2 through a pipe 14. In the first reverse osmosis membrane separator 2, it is preferable to operate the recovery rate at a relatively high rate, for example, about 75 to 90%, in order to effectively utilize the water to be treated. Further, as the reverse osmosis membrane, it is preferable to use a cellulose acetate membrane, which has excellent stability in long-term operation.

The first reverse osmosis membrane separator 2 desalinates most of the electrolyte in the water to be treated, for example, about 95%.

The permeated water of the first reverse osmosis membrane separator 2 (hereinafter sometimes referred to as "first permeated water") is then fed to the activated carbon adsorption tower 3 via the pipe 15, but at that time the pipe 17 More p
H regulator is added.

A base such as NaOH is used as the pH adjuster, and the pH of the first permeated water is adjusted to 8 to 9.

In this way, by adjusting the pH of the first permeated water, it becomes possible to significantly improve the removal efficiency of carbonic acid components in the second reverse osmosis membrane separator 3.

That is, the carbonic acid component in the first permeate water is in an equilibrium state such as CO2 + H20: H" + HCOa-. Generally, reverse osmosis membranes have a low ability to remove CO2, but a high ability to remove HCOa-. pH 8~
9 to shift this equilibrium to the right, [HCOa
By increasing l/[CO2], it is possible to improve the removal efficiency of carbonic acid components.

After adding the pH adjuster, the first permeated water is sent to the activated carbon adsorption tower 3. While passing through the activated carbon layer in the activated carbon adsorption tower 3, residual chlorine and organic components in the water are quickly adsorbed. removed.

As will be described later, in the second reverse osmosis membrane separator 4, it is preferable to use a polymer membrane such as a polyamide membrane as the reverse osmosis membrane, but generally polymer membranes have little resistance to oxidants. Therefore, membrane deterioration can be prevented by adsorbing and removing oxidizing agents such as residual chlorine through activated carbon treatment. Moreover, in activated carbon treatment, the treatment efficiency is hardly affected by water flow Sv, etc., and residual chlorine in the first permeated water can be removed with reliable and stable high adsorption capacity without requiring complicated operation. .

Note that the particle size of the activated carbon in the activated carbon adsorption tower, the scale of the adsorption tower, etc. are not particularly limited, and are appropriately determined depending on the quality of the first permeated water, the water flow SV, etc.

The treated water adsorbed in the activated carbon adsorption tower 3 is then sent to the second reverse osmosis membrane separator 4 through the pipe 16. In the second reverse osmosis membrane separator 4, from the viewpoint of effective use of the treated water, the recovery rate is preferably about 90%, and the concentrated water is preferably returned to the degassing tower 1 through the pipe 19. In this case, in an apparatus that does not include a degassing tower, the concentrated water is returned to the raw water introduction side of the first reverse osmosis membrane separator. In addition, as a reverse osmosis membrane,
It is preferable to use a polyamide membrane that has high removal efficiency of carbonic acid components in a high pH range of pH 8 to 9. Of course, the reverse osmosis membrane may be made of other materials as long as it has excellent removal efficiency in a high pH range.

The second reverse osmosis membrane separator 4 desalinates most of the electrolyte in the water to be treated, for example, about 98%.

Although the permeated water of the second reverse osmosis membrane separator 4 (hereinafter sometimes referred to as "second permeated water") has a sufficiently high purity,
Further, by feeding the water to the mixed bed tower 5 through the pipe 18 for treatment, it becomes possible to obtain pure water with even higher purity.

The treated water from the mixed bed tower 5 is sent to subsystems etc. through piping 20, and after being further treated, is supplied to a point of use.

An experimental example will be explained below.

Experimental Example 1 Using the high-purity water production apparatus of the present invention shown in Fig. 1 (however, the degassing tower 1 is omitted), city water in Yokohama City, Kanagawa Prefecture was pretreated using the activated carbon adsorption method (conductivity: 160Ω).・C
The process m) was performed.

Note that a cellulose acetate membrane was used as the reverse osmosis membrane of the first reverse osmosis membrane separator 2, and a polyamide membrane was used as the reverse osmosis membrane of the second reverse osmosis membrane separator 4.

The raw water has a residual chlorine content of 1 mg/g by NaCJlo.
n, and adjusted to pH 5 with HCM, and then fed to the first reverse osmosis membrane separator 2. The permeated water from the first reverse osmosis membrane separator was adjusted to pH 8.5 with Na0I (water was passed through it for 5V, 20 hours) and supplied to the '-c' activated carbon adsorption tower 3, and then the treated water was separated by the second reverse osmosis membrane. It was fed to vessel 4.

The recovery rate of each reverse osmosis membrane separator is 80% for the first reverse osmosis membrane separator 2 and 90% for the second reverse osmosis membrane separator 4,
The entire concentrated water of the second reverse osmosis membrane separator 4 was returned to the front of the first reverse osmosis membrane separator 2, and the operation was performed without blowing.

In this way, when the operation is continued for one month, the conductivity of the treated water of the second reverse osmosis membrane separator is 1.5 to 2.5M.
Ω・cm, and S i O2 is 0,03~0,0
It was 4 mg/l. Then, the conductivity of the treated water passed through the mixed bed tower 5 at 5V50hr' is 17~
It was 18 MΩ·Cm.

From the results of this experiment, it is clear that according to the high-purity water production apparatus of the present invention, extremely high-purity pure water can be obtained, and furthermore, the apparatus can be operated continuously for a long period of time.

Experimental Example 2 In Experimental Example 1, the residual chlorine and the water flow Sv of the first permeated water supplied to the activated carbon adsorption tower 3 were changed as shown in Table 1. The chlorine concentration in the treated water was investigated.

The results are shown in Table 1.

Table 1 From Table 1, it can be seen that the residual chlorine removal ability of activated carbon in the activated carbon adsorption tower is not affected by the water flow SV or the quality of the supplied water to be treated, and can always exhibit a stable high removal ability. it is obvious. For this reason, such an activated carbon adsorption tower allows
According to the apparatus of the present invention for removing residual chlorine in the first permeated water, stable treatment can be performed without requiring strict operational management.

[Effect of the invention 1 As detailed above, the high-purity water production device of the present invention is capable of: ■ producing 600 ml of water in a single system without paralleling devices with the same function as in conventional ion exchange devices; Continuous operation is possible for a long period of time, from several months to over one year.

■ Since no ion exchange device is used, problems such as regeneration of the ion exchange resin and effects of ion exchange resin eluates are eliminated.

■ An activated carbon adsorption tower is equipped as a means for removing residual chlorine from the first permeate water, and this activated carbon adsorption capacity is not affected by water flow SV, etc., and has a constantly stable high 11X element removal capacity, so the equipment can be easily operated. It is easy to manage and allows stable processing.

■ High-level removal of carbonic acid components is possible.

■ The removal performance of the second reverse osmosis membrane separator is improved.

(2) S i 02 in the treated water of the second reverse osmosis membrane separator can be treated to the same level as the ion exchange resin system in which an ion exchange tower is connected after the two bed three tower system.

According to the present invention device, which has various effects such as.

For example, extremely high purity ultrapure water with an electrical conductivity of about 1 to 5 MΩ·Cm can be produced extremely easily and efficiently.

[Brief explanation of drawings]

Fig. 1 is a system diagram showing the high purity water production device of the present invention, Fig. 2 is a system diagram showing a conventional pure water production device, and Fig. 3 is a system diagram showing the high purity water production device of the present invention.
FIG. 2 is a system diagram showing details of the primary pure water system of the device shown in the figure. l... Degassing tower, 2... First reverse osmosis membrane separator, 3... Activated carbon adsorption tower, 4... Second reverse osmosis membrane separator. 5...Mixed bed tower/

Claims (1)

[Claims] (1) A means for adding a disinfectant and/or a pH adjuster to raw water pretreated with activated carbon, etc., and
A first reverse osmosis membrane separator that performs a reverse osmosis membrane treatment on raw water to which an H regulator has been added, an activated carbon adsorption tower that performs an activated carbon treatment on the permeated water of the first reverse osmosis membrane separator, and a treatment of the activated carbon adsorption tower. a second reverse osmosis membrane separator for further reverse osmosis membrane treatment of water;
a system for taking out the permeated water of the reverse osmosis membrane separator, and a system for returning the concentrated water of the second reverse osmosis membrane separator to the raw water supply system of the first reverse osmosis membrane separator. High purity water production equipment featuring: