JP3480458B2 - Sterilization method - Google Patents

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a sterilization method, and
Water treatment equipment for producing pure water or ultrapure water , for example, ultrapure water terminal filter (specifically, ultrafiltration membrane separator, etc.)
The present invention relates to a method of sterilizing the inside of a pipe, the inside of a pipe connected to the pipe, or a pipe inside a cleaning device or a cleaning tank, which can be efficiently sterilized using a low-concentration hydrogen peroxide solution.

[0002]

2. Description of the Related Art Conventionally, about 1% by weight (hereinafter simply referred to as "%") of hydrogen peroxide solution has been used for sterilization of water treatment equipment such as ultrapure water terminal filters and its piping system. The system was circulating. For example, JP-A-62-254
In Japanese Patent No. 805, after sterilizing a terminal reverse osmosis membrane device of an ultrapure water producing device with a 0.5 to 1% hydrogen peroxide solution,
It is described that washing with pure water heated at 45 ° C. or higher is performed. Further, in JP-A-3-202130, it is described that a hollow fiber membrane module is filled with or filled with 0.5 to 5% hydrogen peroxide solution and then hot water or hot water is passed through for washing. Has been done. Then, this Japanese Patent Laid-Open No. 3-202130
The publication describes that a hydrogen peroxide solution of less than 0.5% has a poor sterilizing or sterilizing effect.

[0003]

As described above, in the conventional sterilization method, since the concentration of the hydrogen peroxide solution used to enhance the sterilizing effect is set high (about 1%), It takes a long time to wash after the sterilization with the solution is completed. Therefore, the time required for the entire cleaning process is long. By the way, the whole process from preparation for sterilization to cleaning and subsequent start-up of the device requires half a day to one day. Since the concentration of hydrogen peroxide is high, the amount of chemicals used is large (for example, if the amount of water held is 10 m ³ , about 300 liters of 35% hydrogen peroxide solution is required), and the work is extremely dangerous. . There was such a problem.

Moreover, even if such a high-concentration hydrogen peroxide solution is used, a sterilization dipping time of at least 2 hours is required, and complete sterilization is difficult even if the hydrogen peroxide concentration is increased. It was The reason for this is that when viable bacteria adhere to the wall surface of a pipe or a cleaning tank, a polymer consisting of a polysaccharide is exposed on the surface of the viable bacteria and adheres to the wall surface. Therefore, it is considered that a certain amount of time is required for hydrogen peroxide, which is a bactericide, to penetrate into the polymer and reach the inside of the viable cells.

As a method for completely sterilizing the terminal pipe and the inside of the cleaning tank of the ultrapure water production system in a short time, hot water (80
There is a method that uses heat (such as ℃ or more) or steam, but such a method requires energy cost for heating and it is necessary to make the material of the terminal piping and the cleaning tank heat resistant, so equipment cost (heat exchange) There is a disadvantage that enormous cost is required for equipment and piping).

In some cases, such a sterilization method using hot water or steam cannot be applied from the viewpoint of piping material. For example, the terminal pipe for ultrapure water and the wastewater pipe in the clean room are
Normal polyvinyl chloride piping (non-heat resistant) is often used, and the practical heat resistant temperature of the ordinary polyvinyl chloride piping used here is 45 ° C at the maximum, so hot water or steam should not be used. It cannot be washed away.

The present invention solves the above-mentioned problems of the prior art, and the inside of the water treatment equipment and / or the inside of the pipe communicating with the equipment is
In a method of sterilizing by contacting with hydrogen peroxide, using a low-concentration hydrogen peroxide solution, to sterilize efficiently and inexpensively in a short time, and to provide a sterilizing method that facilitates cleaning treatment after sterilization treatment. With the goal.

[0008]

A sterilizing method according to claim 1 is
In the method of sterilizing the inside of a water treatment device for producing pure water or ultrapure water and / or the inside of a pipe communicating with the same with hydrogen peroxide, 0.01 to 0.1% hydrogen peroxide is used. It is characterized in that a solution containing only is heated to 30 to 60 ° C. before use.

A sterilizing method according to a second aspect is the method according to the first aspect, characterized in that the hydrogen peroxide solution is circulated by a water pump to heat the hydrogen peroxide solution by the heat of the water pump. To do.

The present invention will be described in detail below.

In the method of the present invention, pure water or ultrapure water is used.
The inside of the water treatment equipment for producing water and / or the inside of the pipe communicating with this is heated to 30 to 60 ° C., 0.01 to
Sterilize by contact with a solution containing only 0.1% hydrogen peroxide.

If the temperature of the hydrogen peroxide solution used is less than 30 ° C., it may not be possible to perform sufficient sterilization with such a low-concentration hydrogen peroxide solution. The temperature of the hydrogen peroxide solution is 6
If the temperature exceeds 0 ° C., the heating cost becomes high and there is a problem that a heat-resistant material needs to be used for the piping and the like.

If the hydrogen peroxide concentration of the hydrogen peroxide solution is less than 0.01%, a sufficient bactericidal effect cannot be obtained, and
If it exceeds%, it does not meet the purpose of the present invention for lowering the concentration.

The sterilization method of the present invention can be carried out in the same manner as a usual sterilization method except that a 0.01 to 0.1% hydrogen peroxide solution heated to 30 to 60 ° C. is used. Preferably, it is advantageous in terms of heating cost, heating equipment and the like that the hydrogen peroxide solution is circulated by a water feed pump and the hydrogen peroxide solution is heated to a predetermined temperature by heat generation of the water feed pump.

After sterilization according to the method of the present invention,
According to a conventional method, washing with water and, if necessary, washing with ultrapure water are carried out, and then the apparatus is started up. Also in this cleaning, since the low-concentration hydrogen peroxide solution is used in the present invention, the cleaning time and the amount of cleaning water can be greatly reduced. By the way, a sufficient cleaning effect can be obtained when the cleaning time is about 30 to 60 minutes.

The fields to which the sterilizing method of the present invention is applied include, for example, the following, but it goes without saying that the present invention is not limited to the following fields.

(1) Sterilization of ultrapure water subsystem internal equipment (ultrafiltration membrane separator, ion exchange tower and ion exchange resin, tank) and terminal piping network (2) Sterilization of washing equipment internal piping and washing tank ( 3) Sterilization of ultrapure water primary pure water type reverse osmosis membrane separation device and ion exchange tower and ion exchange resin (4) Sterilization of recovery system (reverse osmosis membrane separation device, ion exchange device, piping, tank, etc.) ( 5 ) Sterilization of pure water production systems (tanks, filters, ion exchange devices, etc.) and piping systems for nuclear power plants and thermal power plants

[0018]

[Function] The hydrogen peroxide solution is heated to a temperature of 30-
By raising the temperature to 60 ° C., the hydrogen peroxide concentration can be set low, and the hydrogen peroxide concentration of 0.01 to 0.1
With a low concentration of%, almost complete sterilization is possible in a short time.
For example, complete sterilization is possible in about 30 minutes using a hydrogen peroxide solution having a hydrogen peroxide concentration of about 0.01%.

In the case of a warmed hydrogen peroxide solution, hydrogen peroxide, which is a bactericidal agent, efficiently permeates the polymer formed on the surface of the above-mentioned viable bacteria and reaches the inside of the viable cells within a short time. It is thought that this is for effective sterilization.

Since the sterilization with the low-concentration hydrogen peroxide solution has become possible in this way, the amount of the drug used can be greatly reduced. For example, if the amount of water held is 10 m ³ , then 3
Sterilization is possible with about 3 liters of a 5% hydrogen peroxide solution.
In addition, since the concentration used is low, the work risk can be greatly improved.

Further, it can be applied to ordinary polyvinyl chloride pipes, and efficient sterilization can be performed without making the material of the members heat resistant.

Therefore, after the sterilization treatment, it can be washed easily and in a short time.

In particular, according to the method of claim 2, by utilizing the heat generation of the water feed pump to heat the hydrogen peroxide solution, the hydrogen peroxide solution can be heated and circulated easily and at low cost. , Industrially very advantageous. For example, the temperature of the hydrogen peroxide solution can be raised to about 40 ° C. by the heat generation of the water pump for circulating the hydrogen peroxide solution.

[0024]

EXAMPLES The present invention will be described more specifically below with reference to experimental examples, examples and comparative examples.

Experimental Example 1 Using a hydrogen peroxide solution having the hydrogen peroxide concentration and temperature shown in Table 1, a glass test piece (10 cm ² ) was immersed in this hydrogen peroxide solution, and a colony was formed per test piece. A test for confirming the relationship between the temperature and the hydrogen peroxide concentration of the hydrogen peroxide solution and the bactericidal effect was conducted by examining the change with time of the number. The results are shown in Table 1.

In Table 1, ◯, Δ, and × indicate the following, and the numbers in parentheses indicate the number of confirmed colonies.

[0027] ○: 10 or less confirmed colonies / test piece △: Number of confirmed colonies 10 to 1000 / test piece X: 1000 or more confirmed colonies / test piece

[0028]

[Table 1]

From Table 1, it is possible to obtain a good bactericidal effect in a short time with a hydrogen peroxide solution heated to a temperature of 30 to 60 ° C. and having a hydrogen peroxide concentration of 0.01 to 0.1%. It is clear that

Example 1 The sterilization method of the present invention was applied to a secondary pure water production system and a terminal piping line of an actual ultrapure water production system. FIG. 1 shows a system diagram of the secondary pure water production apparatus applied.

In FIG. 1, 1 is a tank (capacity: 2 m ³ ), 2 is a pump, 3 is an ultraviolet sterilizer, 4 is a mixed bed type ion exchange column, and 5 is an ultra UF membrane separator. Reference numeral 11 is a pipe for introducing primary pure water obtained by the primary pure water producing apparatus, and 12, 1
3 and 14 are pipes for sending water from the equipment of the previous process to the subsequent process, 15 is a bypass pipe provided so as to be able to bypass the mixed bed type ion exchange tower at the time of cleaning, and 16 is a terminal pipe Line (made of polyvinyl chloride),
Reference numeral 17 is a hydrogen peroxide solution supply pipe.

Table 2 shows the viable cell count at a predetermined position in this system.
Therefore, the sterilization treatment was performed according to the sterilization method of the present invention. First, the water level in the tank 2 in the system was set to 25% (about 500 liters) of the normal level, the introduction of primary pure water was stopped, and the water in the system was circulated through the pump 3. The water temperature was heated to 40 ° C. Then, a 35% hydrogen peroxide solution was introduced into the tank 2 through the pipe 17 to adjust the hydrogen peroxide concentration in the system to 0.01%.

After performing such sterilization treatment for 1 hour,
Washing with ultrapure water was carried out for 60 minutes, the number of viable bacteria after sterilization and washing was examined, and the results are shown in Table 2.

Comparative Example 1 The same procedure as in Example 1 was carried out except that the heating was not performed by preliminarily passing water through a pump, and a sterilization treatment was performed for 1 hour using a hydrogen peroxide solution at a temperature of 20 to 23 ° C. After sterilization and washing treatment, the number of viable bacteria after sterilization and washing was examined, and the results are shown in Table 2.

[0035]

[Table 2]

From Table 2, it is clear that according to the sterilization method of the present invention, the inside of the system can be sufficiently sterilized by using the low concentration hydrogen peroxide solution.

[0037]

As described above in detail, according to the sterilization method of the present invention, a water treatment apparatus for producing pure water or ultrapure water in a short time using a low-concentration hydrogen peroxide solution and a method thereof. The inside of the piping system can be sterilized.

Therefore, according to the method of the present invention, (i) the sterilization processing time can be shortened, and the subsequent cleaning processing time can be shortened by reducing the hydrogen peroxide concentration. The time required for startup can be greatly reduced. (ii) By lowering the concentration of hydrogen peroxide, the drug cost can be significantly reduced. (iii) By reducing the concentration of hydrogen peroxide, the risk of work is greatly reduced. (iv) No heat-resistant material is required for the piping material, etc., and it can be effectively applied to conventional members such as vinyl chloride piping. And the like, and is industrially extremely advantageous.

In particular, according to the method of claim 2, the heat of the water pump can be used to heat the hydrogen peroxide solution easily and efficiently at low cost, which is extremely advantageous.

[Brief description of drawings]

FIG. 1 is a system diagram of a secondary pure water production apparatus that has been sterilized in Example 1.

[Explanation of symbols]

1 tank 2 pumps 3 UV sterilizer 4 Mixed bed type ion exchange tower 5 Ultramembrane separation device

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI B08B 3/08 B08B 3/08 Z (58) Fields investigated (Int.Cl. ⁷ , DB name) C02F 1/50 A61L 2 / 16 B01D 65/00 B08B 3/08

Claims (2)

(57) [Claims] 1. A method of sterilizing by contacting the inside of a water treatment device for producing pure water or ultrapure water and / or the inside of a pipe communicating therewith with hydrogen peroxide to sterilize, A sterilization method comprising heating a solution containing only hydrogen peroxide in a weight percentage to 30 to 60 ° C. before use. 2. The sterilization method according to claim 1, wherein the hydrogen peroxide solution is circulated by a water supply pump to heat the hydrogen peroxide solution by heat generation of the water supply pump.