JPH06142646A - Method for washing activated charcoal - Google Patents

Abstract

PURPOSE:To efficiently execute a washing/sterilizing treatment of an activated charcoal adsorption column subjected to slime contamination by feeding an alkali water solution to the adsorption column and washing it, and thereafter,washing it by feeding hot water, in the case of washing activated charcoal packed in an adsorption bed by feeding a washing liquid to the activated charcoal adsorption column. CONSTITUTION:In an activated charcoal adsorption column 1, an adsorption bed 1A filled with activated charcoal is formed. Also, in the activated charcoal adsorption column 1, an anion exchange resin column 2 is provided together, and by filling it with an anion exchange resin, an anion exchange resin bed 2A is formed. In such a state, raw water passes through the column 1, a piping 12 and the column 2 from a piping 11 and is treated, and also, treated water is discharged to the outside of a system from a piping 13. On the other hand, an alkali reproducing liquid passes through the column 2 and a piping 22 from a piping 21 and is supplied to the column 1, the activated charcoal adsorption bed 1A is subjected to alkali washing, and thereafter, discharged to the outside of the system from a piping 23. Moreover, hog water passes through a heat exchanger 3 and a piping 32 from a piping 31 and is supplied to the column 1, the activated charcoal adsorption bed 1A is subjected to hot water washing, and thereafter, it is supplied to a storage tank 4 from a piping 33.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning activated carbon, and in particular, it has a high effect of cleaning slime contamination of activated carbon and has a high sterilization effect. Regarding the cleaning method.

[0002]

2. Description of the Related Art For cleaning electronic parts in a semiconductor manufacturing plant,
Although a large amount of ultrapure water is used, the cleaning wastewater contains some impurities, but its purity is still quite high. Therefore, it is recovered and reused. Conventionally, this water recovery system for semiconductor manufacturing wastewater is generally used in an activated carbon adsorption tower →
Ion-exchange resin tower → Reverse osmosis membrane separator → UV-oxidizer combined with hydrogen peroxide → Activated carbon adsorption tower → Anion-exchange resin tower.

In such a recovery system, slime is remarkably generated in the activated carbon adsorption tower in the former stage and the activated carbon adsorption tower in the latter stage of the ultraviolet oxidizer, which causes a problem that the differential pressure in the activated carbon adsorption tower rises and the cell leak increases. Is happening.

Conventionally, as measures against this, methods such as adding a sterilizing agent to the activated carbon adsorption tower and washing with warm water have been adopted.

[0005]

However, the addition of a bactericidal agent does not provide a sufficient effect, and the washing with hot water cannot obtain a sufficient bactericidal effect unless hot water of 80 to 90 ° C. is used. In addition, there is a disadvantage that the slime removing effect is small.

Alkaline cleaning has also been tried,
Alkali cleaning has the effect of removing slime, but it has the drawback that the rising quality of water after cleaning is poor.

For these reasons, there is a demand for a cleaning / sterilizing method capable of efficiently removing the slime generated in the activated carbon adsorption tower and removing the slime, and obtaining a sufficient sterilizing effect.

Conventionally, as a method of cleaning the terminal reverse osmosis membrane separation device of the ultrapure water production system, a method of cleaning with an aqueous solution of hydrogen peroxide and then with alkaline pure water, heated pure water, alcohol or the like is known. (Japanese Patent Application Laid-Open No. 62-25480
No. 5, gazette), no effective cleaning / sterilizing method is provided for the activated carbon adsorption tower.

The present invention has been made in view of the above conventional circumstances, and an object of the present invention is to provide a method for cleaning activated carbon capable of efficiently cleaning and sterilizing a slime-contaminated activated carbon adsorption tower. To do.

[0010]

The method for cleaning activated carbon according to claim 1 is a method for cleaning activated carbon by passing a cleaning liquid through an activated carbon adsorption tower which is filled with activated carbon to form an adsorption bed. It is characterized in that an alkaline aqueous solution is passed through the tower for alkali washing, and then hot water is passed for washing.

The method for cleaning activated carbon according to claim 2 is the method according to claim 1.
In the above, the activated carbon adsorption tower is provided with an anion exchange resin tower, and the recycled waste liquid of the anion exchange resin tower is used as the alkaline aqueous solution.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a system diagram for explaining an embodiment of a method for cleaning activated carbon according to the present invention.

In the figure, 1 is an adsorption bed 1A filled with activated carbon.
Is an activated carbon adsorption tower, and 2 is an anion exchange resin tower filled with an anion exchange resin to form an anion exchange resin bed 2A.

Reference numerals 11, 12, and 13 are water passage pipes, and raw water (water to be treated such as semiconductor manufacturing wastewater) is treated from the pipe 11 through an activated carbon adsorption tower 1, a pipe 12 and an anion exchange resin tower 2 and treated. Water is discharged from the system through the pipe 13.

Reference numerals 21, 22 and 23 are regeneration pipes, and an alkali regeneration liquid such as an aqueous solution of sodium hydroxide (NaOH) is supplied to the anion exchange resin tower 2 through a pipe 21, and this regeneration waste liquid is then activated through a pipe 22. After being supplied to the adsorption tower 1 and washing the activated carbon adsorption bed 1A with an alkali,
The alkaline cleaning waste water is discharged from the system through the pipe 23.

Reference numerals 31, 32, and 33 are hot water washing pipes,
The warm water (warm pure water) introduced through the pipe 31 and heated by the heat exchanger 33 is introduced through the pipe 32 into the activated carbon adsorption tower 1, and the activated carbon adsorption bed 1A is washed with warm water, and the cleaning drainage is the pipe 3.
It is discharged from 3 and collected in the storage tank 4.

That is, the present embodiment is an example in which the present invention is applied to an activated carbon adsorption tower provided with an anion exchange resin tower,
As an alkaline aqueous solution for alkaline cleaning of an activated carbon adsorption tower,
The regeneration waste liquid of the alkali regeneration liquid used for regeneration of the anion exchange resin tower is used.

Therefore, in washing the activated carbon adsorption tower 1, first, the anion exchange resin tower 2 is regenerated.
The regeneration waste liquid is supplied from the pipe 22 to the activated carbon adsorption tower 1 in a downward flow to perform alkali cleaning. After completion of the alkali washing, hot water is supplied to the activated carbon adsorption tower 1 through the pipe 32 in an upward flow to wash the hot water.

In such a method, there is no particular limitation on the amount of water passed through the alkali cleaning liquid (in this embodiment, the regenerated waste liquid of the anion exchange resin tower) supplied to the activated carbon adsorption tower, the water passage time, and the like. It may be set as appropriate according to the reproduction conditions of. Generally, it is preferable that the pH of the alkaline cleaning liquid in the activated carbon adsorption tower is 10 or more. The pH of the recycled waste liquid from the anion exchange resin tower is usually 10 or higher.

Further, the water flow direction of the alkali cleaning liquid in the activated carbon adsorption tower is not particularly limited, either upward flow or downward flow is preferable, but downward flow is preferable. In addition, it is desirable that the regenerant in the anion exchange resin tower also flows downward in the water flow direction.

As hot water for washing with hot water after washing the activated carbon adsorption tower with alkali, water having a water temperature of 50 to 60 ° C. can be used. The water temperature may be higher than this temperature, but it is preferably 50 to 60 ° C. from the viewpoint of heating cost. When the activated carbon adsorption tower is an activated carbon adsorption tower for recycling semiconductor manufacturing wastewater, heated pure water is particularly used as the hot water.

The water flow condition for this hot water washing is LV = 5.
-20 m / hr, especially 5-10 m / hr, water flow rate 10
It is preferably 30 BV. The water flow direction of this warm water washing may be either parallel flow water or counter flow water with respect to the water flow direction of the alkali washing.

The illustrated embodiment is an embodiment of the present invention, and the present invention is not limited to the illustrated method insofar as it does not exceed the gist of the invention.

For example, as shown in the figure, in the case of utilizing the regenerated effluent of the anion exchange resin tower, the anion exchange resin tower is not necessarily provided in the latter stage of the activated carbon adsorption tower, and another one may be provided between the two towers. The device may be incorporated. Further, its installation form is also arbitrary.

Of course, the present invention can also be applied to an activated carbon adsorption column in which an anion exchange resin column is not provided in the system. In that case, N of pH 10 or more is used for alkali washing.
An aOH aqueous solution or the like may be used.

[0027]

The synergistic effect of the combined use of alkali washing and warm water washing makes it possible to wash and sterilize activated carbon contaminated with slime remarkably efficiently. Further, as the hot water, one having a relatively low temperature can be used, and the water quality of the treated water after washing is also excellent in rising property.

According to the method of claim 2, the recycled waste liquid of the anion exchange resin tower can be effectively used.

[0029]

[Examples] Specific examples and comparative examples are given below,
The present invention will be described more specifically.

In any of the examples, isopropyl alcohol: 2 mg-TOC / in a system in which an activated carbon adsorption tower of the following specifications and an anion exchange resin tower were installed side by side.
l, NaHCO _3: The raw water to 10 mg / l was dissolved in pure water was passed through at about 10 days downflow under the condition 10 liters / hr, the activated carbon adsorption tower pressure difference became 0.2 kgf / cm ² Was washed.

Activated carbon adsorption tower Activated carbon: Kuraray Coal KW (10/32 mesh)
(Manufactured by Kuraray Co., Ltd.) Activated carbon filling amount: 1 liter Column: Diameter 5 cm x height 80 cm Anion exchange resin tower Anion exchange resin: Diaion SA10A (manufactured by Mitsubishi Kasei Co., Ltd.) Anion exchange resin filling amount: 0.5 liter Column: diameter 5 cm × height 80 cm Example 1 The anion exchange resin column was regenerated for 30 minutes using a 4% NaOH aqueous solution (50 g-NaOH / l) once every three days.

In cleaning the activated carbon adsorption tower, first,
A single portion of the regenerated waste liquid of the anion exchange resin tower was passed through the activated carbon adsorption tower in a downward flow to carry out alkali washing.
Then, warm water (heated pure water) at 60 ° C. was applied to LV = 10 m / h.
It was washed by flowing water at r for 15 minutes in an upward flow.

After this washing, the recovery rate of the differential pressure of the activated carbon adsorption tower and the viable cell count of the activated carbon adsorption tower outlet water 10 hours after restarting the passage of raw water were examined, and the results are shown in Table 1.

Comparative Example 1 In Example 1, the alkali washing of the activated carbon adsorption tower was not carried out, but pure water (23 ° C.) was passed upward at LV = 25 m / hr for 15 minutes to carry out only back washing. Similarly, the differential pressure recovery rate and the viable cell count were examined, and the results are shown in Table 1.

Comparative Example 2 The pressure difference was the same as in Example 1 except that the activated carbon adsorption tower was not washed with alkali and hot water at 60 ° C. was passed in an upward flow at LV = 10 m / hr for 15 minutes. The recovery rate and the viable cell count were examined, and the results are shown in Table 1.

Comparative Example 3 The same procedure as in Example 1 was carried out except that, after the alkali cleaning, pure water (23 ° C.) was passed by a downward flow of LV = 10 m / hr for 15 minutes to perform cleaning. The pressure recovery rate and the viable cell count were examined, and the results are shown in Table 1.

From Table 1, it is clear that according to the method of the present invention, the activated carbon adsorption tower can be efficiently washed and sterilized to sufficiently recover the differential pressure and to significantly reduce the viable cell count.

On the other hand, without alkali cleaning,
In Comparative Example 1 in which only cold water washing is performed, good results cannot be obtained in terms of differential pressure recovery rate and viable cell count. In Comparative Example 2 in which only washing with warm water is performed, the viable cell count is reduced to some extent, but the differential pressure recovery rate is not good. Furthermore, in Comparative Example 3 in which the alkaline cleaning is performed and then the cleaning is performed with cold water, the differential pressure recovers to some extent, but the number of viable bacteria is large.

[0039]

[Table 1]

[0040]

As described in detail above, according to the method of the present invention, the activated carbon packed in the activated carbon adsorption tower can be easily and efficiently washed and sterilized, and the differential pressure of the activated carbon adsorption tower can be enhanced. It is possible to recover and reduce the rising speed of the differential pressure. The number of viable bacteria in the effluent of the activated carbon adsorption tower can be significantly reduced. The cleaning frequency of the activated carbon adsorption tower can be reduced. It is not necessary to use high temperature water as warm water, and sterilization can be performed with relatively low temperature warm water. The water quality of treated water after washing is also good. An excellent effect such as is achieved.

According to the method of claim 2, it is possible to utilize the regenerated effluent of the anion exchange resin tower provided adjacent to the activated carbon adsorption tower, and to regenerate the anion exchange resin tower and to wash the activated carbon adsorption tower with alkali. Can also be implemented.

[Brief description of drawings]

FIG. 1 is a system diagram for explaining a method of an embodiment of the activated carbon cleaning method of the present invention.

[Explanation of symbols]

 1 Activated carbon adsorption tower 1A Activated carbon adsorption bed 2 Anion exchange resin tower 2A Anion exchange resin bed 3 Heat exchanger

Claims (2)

[Claims] 1. A method for washing a activated carbon by passing a washing liquid through an activated carbon adsorption tower which is filled with activated carbon to form an adsorption bed, wherein an alkaline aqueous solution is passed through the adsorption tower for alkali washing, A method for washing activated carbon, which comprises washing with warm water. 2. The method for cleaning activated carbon according to claim 1, wherein an anion exchange resin tower is provided in addition to the activated carbon adsorption tower, and the recycled waste water of the anion exchange resin tower is used as the alkaline aqueous solution.