JPH0623357A - Pure water production apparatus - Google Patents

Abstract

PURPOSE:To provide an apparatus suppressing the proliferation of bacteria in a reverse osmosis membrane device and capable of efficiently and stably producing high purity water. CONSTITUTION:A pure water producing apparatus is constituted by connecting an activated carbon adsorbing tower 2, a cation exchange resin tower 3, a decarbonation tower 4, a reverse osmosis membrane device 6 and a mixed bed ion exchange tower 7 in this order and an inert gas supply device 5 is connected to the bottom part of the decarbonation tower 4.

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 used in the electronic industry, medical fields, etc., and particularly, it has an improved ability to remove impurities, suppresses the growth of microorganisms, and is stable and high. The present invention relates to a pure water manufacturing apparatus capable of supplying pure water of high purity.

[0002]

2. Description of the Related Art In recent years, LSIs and VLSIs have been actively developed and mass-produced, and pure water and ultrapure water are used in many cleaning processes. As the degree of integration of LSIs increases, the quality of ultrapure water to be used is required to be even higher, and pure water having almost no impurities contained and being extremely close to theoretical pure water is required. In order to obtain such pure water, conventionally, as shown in FIG. 2, an activated carbon adsorption tower 2, a reverse osmosis membrane device 6, a cation exchange resin tower 3, a decarboxylation tower 4 (an anion exchange resin tower as necessary). ) And the mixed bed ion exchange resin tower 7 in this order.

However, since the outlet water of the activated carbon adsorption tower flows into the reverse osmosis membrane device used, the reverse osmosis membrane is used in a neutral or weakly acidic condition, and microorganisms propagate on the reverse osmosis membrane. Therefore, it is usually necessary to wash and sterilize the reverse osmosis membrane device once a week with hot water or 0.5 to 1 wt% hydrogen peroxide solution. If such a sterilization treatment is not carried out, leakage or clogging of microorganisms from the reverse osmosis membrane device may occur, the pressure may increase, and operation may not be possible. Further, since the sterilization treatment is followed by washing with a large amount of pure water, the operating cost becomes high.

[0004]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks of the prior art, suppresses the growth of microorganisms in a reverse osmosis membrane device, and efficiently and stably produces pure water of high purity. It is an object of the present invention to provide a device that can be used.

[0005]

According to the present invention, a cation exchange resin tower and a decarboxylation tower, which are conventionally arranged in the latter stage of the reverse osmosis membrane device, are arranged in the former stage of the reverse osmosis membrane device, and the reverse osmosis is performed. The above object was achieved by reducing the pH and the dissolved oxygen concentration of the water flowing into the membrane device.

That is, the apparatus for producing pure water according to the present invention comprises an activated carbon adsorption tower, a cation exchange resin tower, a decarbonation tower, a reverse osmosis membrane apparatus and a mixed bed ion exchange resin tower, which are connected in this order to remove decarbonation. It is characterized in that an inert gas supply device is connected to the bottom of the tower.

To produce pure water using the apparatus for producing pure water according to the present invention, first, raw water is passed through an activated carbon adsorption tower to remove impurities adsorbed on the activated carbon, and then a cation exchange resin tower is used. Pass water. Here, cations are exchanged with hydrogen ions and removed, increasing the concentration of hydrogen ions in water,
As a result, the pH drops.

When this low pH liquid is introduced into the decarbonation tower, the carbonate ions and bicarbonate ions dissociated in water are
It is removed from the water by an inert gas blown from the bottom of the tower. Here, dissolved oxygen is also removed by using an inert gas such as nitrogen gas or argon gas, and the dissolved oxygen concentration in water is reduced.

When water in such a state flows into the reverse osmosis membrane device, the growth of microorganisms on the reverse osmosis membrane can be suppressed. The reason why the growth of microorganisms is suppressed here is not necessarily clarified, but it is generally known that when the pH of the liquid becomes acidic or alkaline, it becomes difficult to grow except for special microorganisms. . In the pure water producing apparatus of the present invention, the liquid flowing into the reverse osmosis membrane device is low.
Since it shows pH and the dissolved oxygen concentration is low, it is considered that the growth of microorganisms is suppressed.

The water that has passed through the reverse osmosis membrane device is then passed through a mixed bed ion exchange resin tower to remove anions and residual cations in the water. If necessary, an anion exchange resin tower can be provided in front of the mixed bed ion exchange resin tower.

[0011]

Embodiments of the present invention will now be described in detail with reference to the drawings, but the present invention is not limited thereto.

FIG. 1 is a schematic system diagram of an apparatus for producing pure water showing an embodiment of the present invention. The apparatus for producing pure water of the present invention shown in FIG. 1 includes a raw water inflow pipe 1, an activated carbon adsorption tower 2, a cation exchange resin tower 3, a decarbonation tower 4, a reverse osmosis membrane apparatus 6 and a mixed bed ion exchange resin tower 7. An inert gas supply device 5 is arranged at the bottom of the decarbonation tower 4. The treated water is
It flows out from the treated water outflow pipe 8.

In the apparatus shown in FIG. 1, a city water of 1 m ³ was created.
First, the activated carbon adsorption tower (Dia Hope 008,
Mitsubishi Kasei Kogyo Co., Ltd.). Then, water was passed through a cation exchange resin tower (Monosphere 650C, manufactured by Dow Chemical Co.) and a decarbonation tower. In the decarbonation tower, nitrogen gas was blown into the decarbonation tower at 0.5 times the amount of water produced. As a result, the dissolved oxygen concentration in the decarboxylation tower outlet water was 5 ppb and the pH was 2-3.

Then, the reverse osmosis membrane device (SU70
0, Toray's polyimide composite membrane) and mixed bed ion exchange resin tower [Monosphere 650C: Monosphere 550A
(Manufactured by Dow Chemical Co.) was mixed at a ratio of 1: 2].

The number of viable cells in the permeate of the reverse osmosis membrane at the start of water flow was 0 per liter, but after 50 days, microorganisms began to gradually grow. However, the number was 20 or less per liter even after 100 days had passed. The relationship between the number of days of water passage and the number of viable bacteria in the permeate of the reverse osmosis membrane is shown in FIG.

FIG. 3 further shows the number of days of water passage and the viable bacteria of the permeate of the reverse osmosis membrane when pure water was produced in exactly the same manner as above except that the conventional apparatus shown in FIG. 2 was used. Show the relationship with the number. It can be seen from FIG. 3 that the use of the device of the present invention can significantly suppress the growth of microorganisms, and can significantly reduce the number of times of sterilization of the reverse osmosis membrane device.

[0017]

EFFECT OF THE INVENTION By using the pure water producing apparatus of the present invention, the growth of microorganisms in the reverse osmosis membrane apparatus can be remarkably suppressed, and highly pure water of high purity can be produced efficiently and stably.
The number of sterilization of reverse osmosis membrane device can be significantly reduced,
Therefore, the amount of cleaning wastewater generated after the sterilization treatment is drastically reduced, and the operating cost can be significantly reduced.

[Brief description of drawings]

FIG. 1 is a schematic system diagram of an apparatus for producing pure water showing an embodiment of the present invention.

FIG. 2 is a schematic system diagram of a conventional pure water production apparatus.

FIG. 3 is a graph showing daily changes in the viable cell count of permeated water of the reverse osmosis membrane device measured in Examples.

[Explanation of symbols]

 1 Raw water inflow pipe 2 Activated carbon adsorption tower 3 Cation exchange resin tower 4 Decarbonation tower 5 Inert gas supply device 6 Reverse osmosis membrane device 7 Mixed bed ion exchange resin tower 8 Treated water outflow pipe

Claims (2)

[Claims] 1. An activated carbon adsorption tower, a cation exchange resin tower, a decarbonation tower, a reverse osmosis membrane apparatus and a mixed bed ion exchange resin tower are connected in this order, and an inert gas supply apparatus is provided at the bottom of the decarbonation tower. An apparatus for producing pure water characterized by being connected. 2. The apparatus for producing pure water according to claim 1, wherein an anion exchange resin tower is provided between the reverse osmosis membrane apparatus and the mixed bed ion exchange resin tower.