JP4774617B2 - Cleaning method of activated carbon - Google Patents

Description

【００３７】
表１より明らかなように、本発明によれば通水開始初期の比抵抗調整水の抵抗率の変動の問題が解消される。
【００３８】
【発明の効果】
以上詳述した通り、本発明の活性炭の洗浄方法によれば、使用開始初期の処理水の抵抗率の変動の問題がなく、目標水質の処理水を直ちに採水することが可能な活性炭を調整することができる。
【図面の簡単な説明】
【図１】実施例１で洗浄を行った活性炭カートリッジを示す模式的な断面図である。
【符号の説明】
１ 活性炭カートリッジ
２ 容器
５ 撒水管
６ 集水管
７ 活性炭[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an activated carbon cleaning method, and more particularly to an activated carbon cleaning method suitable for adjusting activated carbon as a TOC component removing means in a process for recovering and reusing specific resistance adjustment water used as inspection water or the like.
[0002]
[Prior art]
In semiconductor manufacturing processes, silicon wafer manufacturing processes, liquid crystal manufacturing processes, and inspection water processes, highly pure water or pure water adjusted to a specific resistivity by dissolving carbonic acid is used in large quantities. A large amount of used pure water is discharged from this process. Conventionally, spent pure water discharged from these processes has been recovered and desalted to increase its purity and reused, but TOC components are mixed as impurities in the system. In many cases, it is discarded without being reused.
[0003]
However, in recent years, reduction of environmental load and reduction of water treatment costs have been demanded, and used pure water mixed with TOC components has also been collected and reused.
[0004]
Conventionally, processes for removing TOC components in water include a combination of a reverse osmosis membrane separator, an ultraviolet decomposition device, an electrolysis device, an ozone oxidation device, etc., all of which have high initial costs and running costs. Therefore, in order to remove the TOC component in the collected used pure water, there are an increasing number of cases employing activated carbon with a simple mechanism or a combination of activated carbon and other devices.
[0005]
The activated carbon filled in the activated carbon cartridge as a means for removing the TOC component in such a recovery and reuse process is finally cleaned with pure water in the manufacturing process, and the specific resistance value of the cleaning waste water is 1 MΩ · cm. The product is thoroughly washed until it is above.
[0006]
[Problems to be solved by the invention]
However, when the activated carbon cartridge filled with activated carbon that has been washed only with pure water in this way is used as a TOC component removal means in the recovery and reuse process of specific resistance adjustment water that adjusts the specific resistance using carbonic acid, At the beginning of use, there was a problem that the resistivity of the treated water obtained changed and exceeded the set range of resistivity.
[0007]
For this reason, conventionally, when the activated carbon cartridge is replaced with a new activated carbon cartridge, the start-up operation is performed, and the effluent water of the activated carbon cartridge at the initial stage of water flow is not collected, and the water whose resistivity falls within the set range is not obtained. After being obtained, the effluent water from the activated carbon cartridge is collected and fed to the next step. In addition, in this water sampling stop period, continuous processing is made possible by arranging activated carbon cartridges in parallel and switching water flow so that the process does not stop.
[0008]
However, the activated carbon cartridge that cannot collect water at the start of use as described above has poor processing efficiency and is inappropriate for a recovery and reuse process for processing a large amount of water.
[0009]
The present invention solves the above-described conventional problems, and there is no problem of variation in the resistivity of treated water at the beginning of use, and activated carbon capable of adjusting the activated carbon that can immediately collect treated water of the target water quality can be prepared. An object of the present invention is to provide a cleaning method.
[0010]
[Means for Solving the Problems]
The activated carbon cleaning method of the present invention is characterized in that the activated carbon is cleaned with pure water and then brought into contact with carbonated water.
[0011]
When the activated carbon cartridge is replaced in the process of collecting and reusing specific resistance adjustment water, the resistivity of the treated water at the initial stage of water flow increases for the following reason.
[0012]
That is, the activated carbon is washed with pure water to remove the adsorbed carbonic acid. When such activated carbon is used for removing TOC in the process of recovering and reusing specific resistance adjusted water whose resistivity is adjusted by carbonic acid, the carbon dioxide in the specific resistance adjusted water to be passed is adsorbed, and thus the resistance of the effluent water. The rate changes. The activated carbon adsorbs the carbonic acid in the specific resistance adjustment water until the amount of carbonic acid adsorption is saturated and reaches an equilibrium state by continuing the water flow, and therefore the resistivity of the effluent water is high during this period. When the carbon dioxide adsorption amount of the activated carbon reaches saturation, the activated carbon no longer adsorbs carbonic acid, so there is no problem of fluctuation in the resistivity of the outflow water, and treated water having a predetermined resistivity can be obtained. .
[0013]
In the present invention, after the activated carbon is washed with pure water, it is brought into contact with carbonated water obtained by dissolving carbonic acid in pure water, so that carbon is adsorbed on the activated carbon in advance. For this reason, activated carbon does not adsorb carbonic acid in the water to be treated even at the beginning of water flow, and the problem of variation in resistivity is solved. Therefore, water can be collected immediately from the beginning of use.
[0014]
In the present invention, it is preferable to wash with pure water until the specific resistance value of the cleaning wastewater reaches a predetermined value A, and then wash with carbonated water until the specific resistance value of the cleaning wastewater reaches a predetermined value B. As a result, carbon dioxide is sufficiently adsorbed on the activated carbon to achieve an equilibrium state, and it becomes possible to completely eliminate the fluctuation of resistivity due to the adsorption of carbonic acid at the beginning of water flow.
[0015]
Carbonic acid adsorbed on the activated carbon by the carbonated water washing does not become an obstacle when the used activated carbon is regenerated.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the activated carbon cleaning method of the present invention will be described in detail below.
[0017]
In the present invention, cleaning with pure water and cleaning with carbonated water are performed as the final finishing process in the adjustment process of the activated carbon. In addition, the adjustment process of activated carbon may be an adjustment process of new activated carbon, and may be a regeneration process of activated carbon recovered from various processes.
[0018]
In the pure water cleaning process of activated carbon, pure water is passed through activated carbon filled in a cartridge or the like, and the specific resistance value A of the cleaning waste water is 0.1 MΩ · cm or more, particularly about 1.0 to 10.0 MΩ · cm. It is preferable to carry out as follows.
[0019]
When the specific resistance value A is lower than the above range, the purity of the activated carbon is insufficient, and when used in various recovery and reuse processes, problems such as ion contamination occur in the water to be treated, which is not preferable. The higher the specific resistance value A, the higher the purity of the activated carbon, which is preferable. However, cleaning so that the specific resistance value A is excessively high requires a large amount of pure water and time for the cleaning, and the activated carbon is expensive and preferable. Absent.
[0020]
The pure water used for cleaning is preferably high-purity water having a specific resistance of 15 MΩ · cm or less, particularly about 18 MΩ · cm.
[0021]
After the pure water cleaning, cleaning with carbonated water is then performed. The carbonated water has a resistivity value of 0.15 to 0.3 MΩ · cm by dissolving about 5 to 30 ppm of carbonate in pure water having a resistivity value of 1.0 MΩ · cm or more, particularly about 15 to 18 MΩ · cm. What was made into about cm is preferable. If the carbonate concentration of the carbonated water is too low, the amount of carbonated water used for the adjustment of the activated carbon and the washing time are undesirably increased, and conversely if too high, the adjustment is difficult.
[0022]
In the carbonated water washing step of activated carbon, carbonated water is passed through activated carbon after pure water washing filled in a cartridge or the like, and the specific resistance value B of the washing wastewater is a target value in the specific resistance adjustment water process, for example, 0.05 to 1.0 MΩ · cm, particularly 0.1 to 0.5 MΩ · cm, and the concentration of free carbonic acid in the washing waste water is 0.1 to 30 ppm, particularly about 0.5 to 20 ppm. Is preferred.
[0023]
If the specific resistance value B is higher than the above range and the carbonic acid concentration is low, the carbon dioxide adsorption amount of the activated carbon is not sufficient, and there is a problem of carbonic acid adsorption at the beginning of water flow. Conversely, the specific resistance value B is lower than the above range. If the carbonic acid concentration is high, it is not suitable as recovered water.
[0024]
However, the specific resistance values A and B of the cleaning waste water in each cleaning step are appropriately determined according to the purpose of use of the activated carbon, and are not limited to the above range.
[0025]
The cleaning method for activated carbon is not limited to passing pure water or carbonated water through the cartridge, but batch cleaning in which pure water or carbonated water and activated carbon are placed in a container and stirred and washed to replace the cleaning water. It may be.
[0026]
The activated carbon prepared by the activated carbon cleaning method of the present invention is particularly suitable for use in the process of collecting and reusing specific resistance adjusted water whose resistivity is adjusted with carbonic acid. It can be effectively used for water recovery and reuse processes or water treatment processes. In particular, washing with carbonated water facilitates removal of metal ions adsorbed on the activated carbon, which is suitable for a water treatment process that dislikes metal ions.
[0027]
【Example】
Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples.
[0028]
Example 1
The activated carbon in the activated carbon cartridge shown in FIG. 1 was washed according to the method of the present invention.
[0029]
The activated carbon cartridge 1 shown in FIG. 1 has a treated water submerged pipe 5 and a treated water collecting pipe 6 inserted through a lid 4 provided in the upper opening 3 of the container 2. Filled. The submerged portion 5A of the submerged pipe 5 is located above the packed bed of activated carbon 7, and the water collecting section 6 A of the water collecting pipe 6 reaches the lower layer of the packed bed of activated carbon 7. The water to be treated is introduced into the activated carbon cartridge 1 from the feed water inlet 5B of the brine pipe 5 and is poured onto the activated carbon 7 from the flooded portion 5A. The water to be treated flows down the layer of activated carbon 7 and reaches the lower layer. During this time, the TOC component contained by contacting the activated carbon is adsorbed and removed by the activated carbon. And treated water is collected by the water collection part 6A of the water collection pipe 6, and discharged from the treated water outlet 6B.
[0030]
In cleaning, pure water (specific resistance value 10 MΩ · cm) is first introduced from the submerged pipe 5 and the cleaning waste water is taken out from the collecting pipe 6. The cleaning waste water has a specific resistance value A of 1.0 MΩ · It went until it became cm.
[0031]
Next, using carbonated water in which 10 ppm of carbonic acid was dissolved in pure water (specific resistance value 10 MΩ · cm) to a specific resistance value of 0.25 MΩ · cm, the specific resistance value B of the washing waste water was similarly 0.25 MΩ · cm. Washing with carbonated water was performed until the free carbonic acid concentration became 10 ppm in cm.
[0032]
The water quality specific resistance adjustment water shown in Table 1 whose resistivity was adjusted with carbonic acid was passed through the activated carbon cartridge thus washed with activated carbon at a flow rate of SV = 40 hr ^−1. The average water quality of the treated water was examined and the results are shown in Table 1.
[0033]
In this example, the treated water reached a specific resistance value of 0.25 MΩ · cm immediately after the start of water flow.
[0034]
Comparative Example 1
The activated carbon was washed in the same manner as in Example 1 except that the carbonated water was not washed, and a water flow test was conducted in the same manner. The results are shown in Table 1.
[0035]
In this comparative example, it takes 2.5 hours for the specific resistance value of the treated water to reach 0.25 MΩ · cm, and the water flow up to that time is 100B. V. (100 times the amount) was required.
[0036]
[Table 1]

[0037]
As apparent from Table 1, according to the present invention, the problem of fluctuation in resistivity of the specific resistance adjustment water at the beginning of water flow is solved.
[0038]
【The invention's effect】
As described above in detail, according to the activated carbon cleaning method of the present invention, there is no problem of variation in the resistivity of the treated water at the beginning of use, and the activated carbon that can immediately collect the treated water of the target water quality is prepared. can do.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing an activated carbon cartridge that has been cleaned in Example 1. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Activated carbon cartridge 2 Container 5 Flood water pipe 6 Catchment pipe 7 Activated carbon

Claims (2)

A method for cleaning activated carbon, characterized in that the activated carbon is washed with pure water and then brought into contact with carbonated water. 2. The method according to claim 1, wherein the activated carbon is washed with pure water until the washing wastewater has a predetermined specific resistance value A, and then the activated carbon is washed with carbonated water until the washing wastewater has a predetermined specific resistance value B. Cleaning method for activated carbon.

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