JPH10211487A - Activated carbon treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the short-circuiting caused by channeling by easily venting generated oxygen gas upwardly. SOLUTION: An activated carbon tower 10 is formed into an inverted truncated cone shape and made large in its cross-sectional area upwardly. Therefore, the cross-sectional area of the activated carbon bed 12 in the tower 10 also becomes large upwardly gradually. A liquid to be treated is introduced into the bottom part of the activated carbon tower 10 and the treated soln. is discharged from the upper part of the tower 10. Therefore, the liquid to be treated is brought into contact with activated carbon on the bottom part of the activated carbon bed 12 at first and a large amt. of oxygen gas is generated at this part and increases diameter of bubbles to be vented upwardly. Herein, activated carbon in the activated carbon bed 12 becomes easy to move toward the upper part of the bed 12. Therefore, the upper activated carbon is easily replaced with air bubbles when air bubbles are vented and the short-circuiting caused by channeling can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an activated carbon treatment apparatus for introducing a liquid to be treated containing hydrogen peroxide into an activated carbon column filled with granular activated carbon, and bringing the liquid to be treated into contact with the granular activated carbon to decompose hydrogen peroxide. .

[0002]

2. Description of the Related Art In many cases, wastewater discharged from manufacturing processes of various semiconductor devices and liquid crystal display devices contains hydrogen peroxide. This is because a cleaning liquid containing hydrogen peroxide is used in a semiconductor wafer cleaning step or the like. Usually, the concentration of hydrogen peroxide in these wastewaters is about several tens to several hundreds mg / L, and cannot be discharged to public waters or reused as it is. Therefore, it is necessary to decompose and remove hydrogen peroxide in wastewater, and a method of decomposing hydrogen peroxide into oxygen and water by bringing the liquid to be treated into contact with granular activated carbon has been widely adopted.

However, in this method, the oxygen gas generated by the treatment does not flow smoothly upward, but tends to accumulate to some extent in the activated carbon layer to form large bubbles and then intermittently. In such a state, channeling occurs in the flow of the fluid, so that the granular activated carbon and the liquid to be treated are not sufficiently brought into contact with each other, and there is a problem that hydrogen peroxide cannot be sufficiently decomposed.

[0004] To prevent such channeling,
The liquid to be treated is circulated in the activated carbon layer in an upward flow. If the flow is upward, the upward movement of the bubbles is promoted by that amount, and the generated oxygen gas easily escapes from the inside of the activated carbon layer, so that channeling hardly occurs.

[0005]

In the case where the concentration of hydrogen peroxide is as described above, an upward flow is effective for preventing channeling. However, it has been found that when the hydrogen peroxide concentration is further increased, sufficient channeling prevention cannot be achieved even with an activated carbon treatment tower having an upward flow.

Particularly, in recent years, due to manufacturing reasons and the like,
In some cases, wastewater containing a high concentration of hydrogen peroxide of several thousand to 10,000 mg / L, or even higher, may be discharged temporarily. When activated carbon treatment is performed on such wastewater, hydrogen peroxide cannot be sufficiently decomposed temporarily. Furthermore, bubbles generated in large quantities cannot be fully removed upward,
There is a problem that the leakage of hydrogen peroxide is continued for a long time even after channeling occurs and the temporary discharge of the high-concentration wastewater ends and the concentration of hydrogen peroxide in the wastewater decreases.

[0007] The present invention minimizes the occurrence of channeling in wastewater containing a high concentration of hydrogen peroxide,
An object of the present invention is to provide an activated carbon treatment device capable of stably decomposing hydrogen peroxide.

[0008]

According to the present invention, a liquid to be treated containing hydrogen peroxide is passed through an activated carbon tower filled with granular activated carbon in an upward flow from the bottom side to the upper side, and the liquid to be treated is granulated. An activated carbon treatment device for decomposing hydrogen peroxide by contacting with activated carbon, characterized in that the cross-sectional area on the upper side of the activated carbon layer formed by granular activated carbon filled inside the activated carbon tower is larger than that on the bottom side. I do.

When the liquid to be treated containing hydrogen peroxide is introduced into the activated carbon tower from the bottom thereof, the liquid to be treated comes into contact with the granular activated carbon filled therein, and its catalytic action effectively converts oxygen gas and water. Decomposed. Therefore, oxygen gas is rapidly generated in the activated carbon layer. The generated oxygen gas bubbles merge with nearby ones and increase in diameter. Then, the bubbles having an increased diameter rise in the activated carbon layer. In the apparatus of the present invention, since the cross-sectional area of the activated carbon layer formed inside the tower is larger upward, the bubbles having an increased diameter are removed from the activated carbon layer. Easy to get out. It is not clear why air bubbles are easily released by increasing the cross-sectional area of the activated carbon layer upward, but the filled granular activated carbon has a higher degree of freedom of movement as it goes upward, making it easier to move. It is thought that it is. For this reason, the bubbles that have risen by pushing the granular activated carbon at the bottom escape above the activated carbon layer without being hindered from moving above, and the granular activated carbon that has been displaced by the passage of the bubbles also quickly returns to its original position. it is conceivable that. In any case, it is apparent that the present invention can effectively prevent the conventional short circuit due to channeling, as will be described in the following embodiments.

[0010]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings.

FIG. 1 shows a configuration of an activated carbon processing apparatus according to one embodiment of the present invention. Inside the activated carbon tower 10, granular activated carbon is filled to form an activated carbon layer 12. Also,
An inflow pipe 14 for introducing the liquid to be treated into the activated carbon tower 10 is connected to the bottom of the activated carbon tower 10, and an outflow pipe 16 for the processing liquid is connected to the upper part of the activated carbon tower 10.

The inflow pipe 14 has a leading end extending to the bottom in the activated carbon layer 12 and a leading end plate 18 at the leading end.
Is arranged. The perforated plate 18 prevents the activated carbon from flowing back into the inflow pipe 14 while supplying the liquid to be treated from the inflow pipe 14 into the activated carbon layer 12. The outlet pipe 16 has a tip extending to an upper portion of the activated carbon tower 10, and a collector 20 is connected to the outlet pipe 16. The collector 20 is for collecting the processing liquid evenly from the upper part in the activated carbon tower 10, and a pipe-shaped one having a large number of openings is employed.

In this embodiment, the activated carbon tower 10 has a substantially inverted frustoconical shape (hopper shape) whose diameter decreases downward. Therefore, the cross-sectional area of the activated carbon layer 12 accommodated therein is gradually reduced downward.

In such an apparatus, the liquid to be treated is introduced into the activated carbon tower 10 via the inflow pipe 14. The liquid to be treated is, for example, waste water from a semiconductor device manufacturing process, and contains high concentration hydrogen peroxide. Although not shown, the liquid to be treated is usually once stored in a drainage storage tank and pumped by a pump. When the liquid to be treated is introduced into the activated carbon tower 10 from the bottom thereof, the liquid to be treated comes into contact with the granular activated carbon, and its catalytic action causes oxygen gas and
Decomposes effectively in water. Therefore, oxygen gas is rapidly generated in the activated carbon layer 12. The generated oxygen gas bubbles merge with nearby ones and increase in diameter. Then, the bubbles having a larger diameter rise, but in the present embodiment, the cross-sectional area of the activated carbon layer 12 increases as it goes upward. Therefore, the granular activated carbon of the activated carbon layer 12 has a higher degree of freedom of movement as it goes upward, and is more likely to move. Therefore, the bubbles that have been pushed up by pushing down the granular activated carbon at the lower portion escape above the activated carbon layer 12 without being hindered from moving above, and the granular activated carbon displaced by the passage of the bubbles is also quickly returned to the original position. Return. Therefore, it is possible to effectively prevent a short circuit of the liquid to be processed due to channeling as in the related art.

[Other Configurations] FIG. 2 shows another embodiment. In this example, the activated carbon tower 10 has a small diameter lower straight body 1.
0a and an upper straight body portion 10b having a diameter larger than that of the lower straight body portion 10a.
And the activated carbon layer 12 has reached the upper straight body portion 10b. Therefore, also in this embodiment, as in the above-described case, the upper part of the activated carbon layer 12 has a larger cross-sectional area than the lower part. Therefore, the bubbles are effectively removed upward as in the above-described case, and short-circuiting of the liquid to be treated due to channeling is prevented.

FIG. 3 shows still another embodiment. In this device, the outer shape of the activated carbon tower 10 is a cylindrical shape having a constant diameter. And near the bottom of the activated carbon tower 10,
A strainer 22 composed of a donut-shaped perforated plate as shown in FIG. 3B is arranged, and a liquid chamber 24 to be treated is defined below the strainer 22. The granular activated carbon in the activated carbon layer 12 is prevented from falling by the strainer 22, and the liquid to be treated is supplied to the activated carbon layer 12 via the strainer 22. A conical sealing body 26 is provided above the inside of the strainer 22 and occupies the conical space inside the strainer 22. Therefore, the activated carbon tower 10 has the strainer 2
Above 2, the inner space is formed so as to gradually expand. That is, the cross-sectional area of the activated carbon layer 12 formed by the granular activated carbon filled in the activated carbon tower 10 is:
It gradually grows upward.

A disc-shaped strainer 28 is provided above the activated carbon tower 10, and a processing liquid chamber 30 is formed above the strainer 28. Accordingly, the processing liquid is collected in the processing liquid chamber 30 from the entire upper surface of the activated carbon tower 10, and is discharged therefrom through the outflow pipe 16.

Also in this configuration, similarly to the above-described case, the air bubbles can be suitably removed upward, and short-circuiting of the liquid to be processed due to channeling is prevented.

FIG. 4 shows still another embodiment. In this example, the activated carbon tower 10 is formed in a spherical shape, and the activated carbon layer 12 is set to about half a place from below. In other respects, the configuration is almost the same as that of FIG. Even with this configuration, the cross-sectional area of the activated carbon layer 12 increases as it goes upward, and short-circuiting of the liquid to be treated due to channeling can be prevented as in the case described above.

FIG. 5 shows still another configuration example.
In this example, an activated carbon tower 10 having the same configuration as shown in FIG.
At the later stage (referred to as the first activated carbon tower), an open-air storage tank 3
2. A second activated carbon tower 36 is connected via a pump 34. Here, the second activated carbon tower 36 may be either a downward flow or an upward flow, and any shape can be adopted.

In this apparatus, the first activated carbon tower 10
The primary treatment liquid treated in the upward flow is once stored in the storage tank 32. Since the upper portion of the storage tank 32 is open to the atmosphere, oxygen gas contained in the primary processing liquid is removed here. In addition, since the storage tank 32 has a certain capacity, a primary treatment liquid containing no air bubbles is supplied to the second activated carbon tower 36, where the primary treatment liquid is further contacted with granular activated carbon and hydrogen peroxide remaining in the primary treatment liquid is supplied. Is further removed. By treating the wastewater with the two-stage activated carbon towers 10 and 36 in this way, even if wastewater containing a high concentration of hydrogen peroxide is temporarily discharged, it can be reliably treated.

Here, if the second activated carbon tower 36 is of a downflow natural flow type and the upper part of the activated carbon tower 10 is opened to the atmosphere so that oxygen gas can be discharged to the atmosphere, the pump 34 and the storage tank 32 can be omitted.

FIG. 6 shows still another embodiment. In this example, the first and second activated carbon towers 10 and 36 are formed in an inverted conical shape having the same shape.
The liquid to be treated is transferred from the first activated carbon tower 10 to the second activated carbon tower 36.
, Or vice versa, from the second activated carbon tower 36 to the first
The activated carbon tower through which the liquid to be treated is first passed is set as the upward flow liquid, and the activated carbon tower at the subsequent stage is set as the downward flow liquid so that the liquid can be passed in the order of the activated carbon tower 10 in order. The distribution channel can be switched so that it can be performed.

That is, the liquid to be treated can be supplied to the lower part of the first activated carbon tower 10 via the valve 40 or to the lower part of the second activated carbon tower 36 via the valve 42, respectively. Further, the final treatment liquid by the series flow from the first activated carbon tower 10 to the second activated carbon tower 36 can be discharged from the lower part of the second activated carbon tower 36 via a valve 44, and vice versa. The treated final treatment liquid can be discharged from the lower part of the first activated carbon tower 10 via a valve 46. Further, from the top of the first activated carbon tower 10, a valve 5
0, the primary treatment liquid treated in the first activated carbon tower 10 can be discharged to the storage tank 32, and the second activated carbon tower is supplied from the storage tank 32 to the upper part of the activated carbon tower 10 via the pump 34 and the valve 52. The primary processing liquid in the storage tank 32 processed at 36 can be supplied. In addition, the second activated carbon tower 36
The primary treatment liquid in the storage tank 32 treated in the first activated carbon tower 10 can be supplied from the storage tank 32 via a pump 34 and a valve 54 to the upper part of the second activated carbon tower 36. From the storage tank 32 through the valve 56
The primary treatment liquid treated in the activated carbon tower 36 can be discharged.

Therefore, by opening the valves 40, 50, 54 and 44 and closing the valves 42, 52, 56 and 46, the liquid to be treated is discharged through the valve 40 and the pipe 58 to the first liquid.
From the lower part of the activated carbon tower 10
Is discharged from the top of the tower through a pipe 60 as a primary treatment liquid through a pipe 60, and is introduced into a storage tank 32 through a valve 50. Thereafter, the pump 34 and the valve 54
And is supplied to the upper part of the second activated carbon tower 36 via a pipe 62, passes through the second activated carbon tower 36 in a downward flow, and the processing liquid is supplied as a final processing liquid from the lower part of the pipe 64, the valve 44, the pipe 6
Exhausted through 6. On the other hand, valves 40, 50, 5
4 and 44 are closed and the valves 42, 52, 56 and 46 are opened, so that the liquid to be treated flows through the second activated carbon tower 36 in an upward flow, and then the first activated carbon tower is passed through the storage tank 32. 10
Through a downward flow.

As described above, in this embodiment, it is possible to switch which of the two activated carbon towers 10 or 36 is used as the preceding stage. Here, each of the two activated carbon towers 10 and 36 has an inverted conical shape, and has a large diameter upward. Then, the activated carbon tower 10 or 36 used as the first stage flows upward, and the activated carbon tower 10 or 36 used as the second stage flows downward.

Therefore, the first liquid through which the liquid to be treated first flows is
In the activated carbon tower 10 or 36 of the second stage, a large amount of oxygen gas generated can be efficiently discharged upward, while in the activated carbon tower 10 or 36 of the second stage, the flow velocity of the liquid flowing in the activated carbon tower 10 or 36 , The flow velocity becomes higher on the outlet side (lower side) of the tower. Therefore, the granular activated carbon and the liquid to be treated come into contact with each other at a high flow rate in a portion where the concentration of hydrogen peroxide is low. When the flow rate is high, the Reynolds number of the liquid to be treated flowing through the activated carbon layer 12 is increased, and the surface of the activated carbon and the liquid to be treated are more easily contacted. Therefore, hydrogen peroxide having a low concentration can be effectively removed.

Further, by changing the order of passing the first and second activated carbon towers 10 and 36 as described above,
The generation of slime on the surface of the granular activated carbon in the activated carbon layer in the first and second activated carbon towers 10 and 36 can be effectively prevented. That is, the liquid to be treated containing a high concentration of hydrogen peroxide is supplied to the activated carbon tower 10 or 36 used as the preceding stage. At this time, hydrogen peroxide is contained in the treatment liquid of the activated carbon tower. By passing the liquid to be treated at such a flow rate as to leave a small amount, almost all of the granular activated carbon in the activated carbon tower 10 or 36 is exposed to hydrogen peroxide. Therefore, the generation of slime is suppressed by the bactericidal action of hydrogen peroxide. On the other hand, most of the hydrogen peroxide is decomposed in the activated carbon tower in the preceding stage and the primary treatment liquid having a reduced concentration of hydrogen peroxide is supplied to the activated carbon tower 10 or 36 in the subsequent stage.
Hydrogen peroxide is almost decomposed in the upper part of the activated carbon layer, and activated carbon existing below the intermediate layer is not exposed to hydrogen peroxide. Therefore, slime is generated below the intermediate layer. However, in this embodiment, since the flow order of the liquid to be treated is periodically switched, the activated carbon in both activated carbon layers of the activated carbon towers 10 and 36 is surely sterilized even if intermittent, and the generation of slime is totally reduced. Is suppressed.

When slime is generated, there are problems such as the slime flowing out into the processing solution, a dead space being generated, short-circuiting of the processing solution, and an increase in pressure loss in flowing water. Generation can be suppressed.

[0030]

EXAMPLE An experiment for treating hydrogen peroxide-containing water was performed using the apparatus shown in FIG. Further, an experiment on a comparative example was also performed using an activated carbon tower having a constant cross-sectional area. The diameter of the lower part 10a of the activated carbon tower 10 of the embodiment is 1.1 m, the height of the straight body is 0.8 m (therefore, the capacity of the straight body is about 800 L),
The diameter of the upper portion 10b was 1.6 m, and the granular activated carbon was filled with 2,400 L of Diamond Hope 006 (manufactured by Mitsubishi Chemical Corporation).
The comparative example is a cylinder having a diameter of 1.1 m, and the filling amount of activated carbon is the same.

As the liquid to be treated, a hydrogen peroxide concentration of 500 m
g / L of wastewater was prepared and supplied at a flow rate of 12 m ³ / h for 24 hours.
Water passed for hours. As a result, in the apparatus of the embodiment, the concentration of hydrogen peroxide in the treated water was stable and zero during the passage, but in the comparative example, the concentration after 24 hours was about 80 mg / L, which was considerably high. It was estimated that a short circuit had occurred.

Further, the concentration of hydrogen peroxide in the liquid to be treated is temporarily increased to 5000 mg / L, and thereafter, the concentration is increased to 500 mg / L.
Back to. In the apparatus of the embodiment, the concentration of hydrogen peroxide in the treatment liquid temporarily increased to 4 mg / L, but immediately returned to zero. On the other hand, in the comparative example, the concentration increased to 120 mg / L, and the hydrogen peroxide concentration became high for a considerable time thereafter.

[0033]

As described above, according to the present invention,
The cross-sectional area of the activated carbon layer increases as it goes upward, and the liquid to be treated containing hydrogen peroxide is circulated in the upward flow. Therefore, the bubbles formed of the oxygen gas generated in the activated carbon layer effectively escape upward. Therefore, an effective processing can be performed by preventing a short circuit due to channeling.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of an embodiment.

FIG. 2 is a diagram illustrating a configuration of another embodiment.

FIG. 3 is a diagram illustrating a configuration of still another embodiment.

FIG. 4 is a diagram showing a configuration of still another embodiment.

FIG. 5 is a diagram showing a configuration of still another embodiment.

FIG. 6 is a diagram showing a configuration of still another embodiment.

[Explanation of symbols]

10 activated carbon tower, 12 activated carbon bed, 14 inflow pipe, 16
Outflow pipe, 18th board, 20 collector, 22 strainer, 24 liquid chamber to be processed, 26 sealed body, 28 strainer, 30 processing liquid chamber, 32 storage tank, 34 pump, 36
Activated carbon tower, 40, 42, 44, 46, 50, 52, 5
4,56 valves.

Claims (1)

[Claims] 1. A liquid to be treated containing hydrogen peroxide is passed through an activated carbon tower filled with granular activated carbon in an upward flow from the bottom side to the upper side, and the liquid to be treated is brought into contact with the granular activated carbon to form hydrogen peroxide. Activated carbon treatment apparatus for decomposing an activated carbon, wherein an activated carbon layer formed by granular activated carbon filled in an activated carbon tower has a cross-sectional area on an upper side larger than that on a bottom side.