JP2558658Y2 - Water treatment equipment - Google Patents

Description

[Detailed description of the invention]

[0001]

The present invention relates to a method for producing halogenated hydrocarbons such as trichloroethylene, 1,1,1-trichloroethane or tetrachloroethylene (referred to as trichloroethylene or the like) generated in a semiconductor production process or a clothing cleaning process. The present invention relates to a water treatment apparatus used for removing organic substances such as trichloroethylene from raw water such as wastewater containing organic substances.

[Prior art]

[0002] Exhaust gas containing low-boiling-point organic substances such as solvents such as trichloroethylene generated in semiconductor manufacturing factories and clothing cleaning processes is usually adsorbed by passing through a purification device filled with granular activated carbon. Released after removal. In this method, in order to use the granular activated carbon for a long period of time while maintaining sufficient adsorption performance, the granular activated carbon to which organic substances have been adsorbed is regenerated with steam. The organic matter generated in this regeneration process can be reused. On the other hand, the separated water cannot be discarded as it is because the organic matter is dissolved at a high concentration.

As a method for treating wastewater containing a high concentration of harmful organic substances such as trichloroethylene, water containing trichloroethylene or the like is passed through granular activated carbon, and trichloroethylene or the like is adsorbed on the granular activated carbon.
A method of reducing the concentration of trichloroethylene or the like in water to 0.5 ppm or less is generally used. However, in such a general water treatment method, there is a problem in treating granular activated carbon to which trichlorethylene or the like is adsorbed. In other words, granular activated carbon that adsorbs trichlorethylene etc. cannot be incinerated, so it must be disposed of by burying it in the soil, or used activated carbon can be stored permanently in a completely sealed container. Or one of the disposal methods must be taken.

However, in the case of burial disposal method in the soil,
There is a problem that trichlorethylene etc. gradually diffuses into the environment.In the case of a disposal method in which it is permanently stored in a container, not only is the treatment cost high, but also recent waste disposal sites There is a major problem in terms of shortage.

On the other hand, raw water containing an organic substance such as trichlorethylene is brought into contact with activated carbon fibers, and trichloroethylene and the like in the raw water are adsorbed and removed by the activated carbon fibers, while activated carbon fibers having adsorbed the trichloroethylene and the like are removed. A water treatment method for regenerating with a heated gas such as water vapor has been proposed (see Japanese Patent Application Laid-Open No. 61-42394). It is suggested that this method can remove organic substances even when the space velocity (SV) is increased to 30 to 50 or more. By increasing the SV, the size of the water purification device can be reduced. Further, in this method, the activated carbon fibers having adsorbed the organic substance are heated to 100 ° C. to 300 ° C.
Can be sufficiently regenerated by water vapor.

[0006] In order to sufficiently regenerate the granular activated carbon, the temperature of 100 ° C to 300 ° C is extremely low as compared with the necessity of heating to about 500 ° C to 700 ° C. For this reason, a special heating furnace is required when regenerating granular activated carbon, but a special heating furnace is not required to regenerate activated carbon fibers, and steam is sent into a tube filled with activated carbon fibers. Can be played. At present, activated carbon fibers are more expensive per unit weight than granular activated carbon, but may be advantageous in terms of overall cost due to the above-mentioned features relating to regeneration temperature and SV.

[0007]

However, in the conventional water treatment method as described above, the steam used after the regeneration of the activated carbon fiber is condensed and treated as a separate wastewater. Organic substances such as trichlorethylene are discharged into the system, and this may again become a source of wastewater containing organic substances such as trichlorethylene.
In addition, when an attempt is made to remove organic substances such as trichlorethylene in the drainage system, a new problem arises in that the processing apparatus is likely to be large.

The present invention has been made in view of the above circumstances, and a water treatment apparatus capable of efficiently removing organic substances in water without taking organic substances such as trichloroethylene out of the system while making the whole compact. It is intended to provide.

[0009]

Means for Solving the Problems To achieve the above object, a water treatment apparatus according to the present invention comprises a storage tank for storing raw water containing organic substances, and an organic substance contained in a water layer in the storage tank. A processing means provided with activated carbon fibers for removing and obtaining treated water, a regenerating fluid source for supplying a regenerating fluid consisting of warm water or steam to the treating means, and a regenerating fluid leaving the processing means being sent to the storage tank. And a return path.

[0010]

According to the invention, an organic substance such as trichloroethylene is first stored in a storage tank. The aqueous layer separated from the organic matter in this storage tank is passed through a treatment means provided with activated carbon fibers, whereby the organic matter dissolved in the aqueous layer is adsorbed and removed by the activated carbon fibers. It is discharged out of the system.

Next, by supplying a regeneration fluid comprising hot water or steam to the treatment means, organic substances such as trichloroethylene adsorbed on the activated carbon fibers are desorbed, and the activated carbon fibers are regenerated. The desorbed organic matter is returned to the storage tank together with the regeneration fluid. Organic matter is separated from water in the storage tank, so it can be recovered and reused. By repeating such an operation, it is possible to efficiently process raw water containing trichloroethylene without discharging the organic matter to the outside of the system.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, the principle of the present invention will be described with reference to FIG. In the figure, raw water a containing an organic substance T such as trichlorethylene is stored in a storage tank 2 from a raw water generation source 1 including a step of using the organic substance T. In the storage tank 2, the layer of water W and the layer of organic matter T are separated into upper and lower layers due to a difference in specific gravity. The organic matter T is dissolved in the water W, and the water W is supplied to the treatment means 3, where the organic matter T is adsorbed and removed to obtain purified treated water W1, which is discharged out of the system. .

The treatment means 3 passes the water W in which the organic matter T discharged from the storage tank 2 is dissolved,
Activated carbon fiber (hereinafter, ACF = Ac) that adsorbs organic matter T typified by trichlorethylene and the like contained therein.
tivated Carbon Fiber). A regenerating fluid source 4 for supplying a regenerating fluid S1 is connected to the water purifier 3 via an on-off valve V2, and a recirculation path 5 for sending the regenerating fluid S1 exiting the water purifier 3 to the storage tank 2 is provided. It is connected. The organic matter T separated into layers in the storage tank 2 is supplied to a desired process in the raw water generation source 1 and is reused there.

Next, an embodiment of the present invention in combination with a source of an organic matter-containing exhaust gas, an activated carbon tank for treating the exhaust gas, and a regeneration fluid source for regenerating the activated carbon in the activated carbon tank is schematically shown. This will be described with reference to FIG. In FIG. 2, an exhaust gas b containing an organic substance such as trichloroethylene is discharged from a source 6 of an organic substance-containing exhaust gas such as a clothing cleaning process or a semiconductor production process. It may be passed through a tank 7 filled with activated carbon. Thereby, after the organic matter such as trichloroethylene contained in the exhaust gas b is adsorbed and removed, the treated exhaust gas b
1 is released.

A steam source 4 for generating steam at 110 ° C. to 150 ° C., which is an example of a regenerating fluid of the granular activated carbon, is connected to the granular activated carbon tank 7 by piping. By supplying steam S2 into the inside, the granular activated carbon which has adsorbed an organic substance such as trichloroethylene is regenerated. This allows
The adsorption capacity recovers by about 70%. By opening and closing the valves V3 and V4, the tank 7 is selectively supplied with the exhaust b in the normal processing step and the steam S2 in the regeneration step.

The steam c containing organic substances such as trichlorethylene discharged from the tank 7 in the regeneration step is
When the cooling water CW passes through the condenser 8 through which water is passed, it is cooled and becomes raw water a, and is stored in the storage tank 2. In the storage tank 2, the water W and the organic substance T such as trichlorethylene are separated into upper and lower layers due to a difference in specific gravity.
Is returned to the organic matter-containing exhaust gas generation source 6 such as in a clothes cleaning step or a semiconductor production step and is reused.

On the other hand, trichlorethylene or the like existing in the storage tank 2 is saturated with a concentration (often 100 to 100).
The water W containing about 0 ppm) is supplied to the processing means 3 through the valve V5, where the above-mentioned trichloroethylene and the like are adsorbed and removed, and the concentration is below the allowable discharge concentration (usually 0.1 ppm or less).
The purified water W1 is obtained and discharged out of the system.

The treatment means 3 is a water purifier having an ACF for passing water W containing trichlorethylene and the like discharged from the storage tank 2 and adsorbing trichloroethylene and the like contained therein. In this water purifier 3,
110 ° C. as a regenerating fluid through the on-off valve V2
The steam generation source 4 (regeneration fluid source) for supplying the steam S1 at 150 ° C. is connected, and the regeneration steam S1 that has exited the water purifier 3 is cooled by the condenser 9 through which the cooling water CW is passed to form a liquid. A return path 5 that returns to the storage tank 2 after
Is connected. By opening and closing the valves V5 and V2, water W containing trichlorethylene and the like and steam S1 are selectively supplied to the water purifier 3.

By the way, A loaded in the water purifier 3
CF has a saturated adsorption amount of 2 compared to granular activated carbon.
It is about 8 times better, and the adsorption speed is extremely high. Therefore, the concentration of trichlorethylene or the like is 0.1 pp.
The amount of ACF required for lowering to less than m is very small as compared with the case of granular activated carbon. Also, the amount of steam required for regeneration is very small as compared with the case of granular activated carbon.

For example, when granular activated carbon is used in place of ACF, the amount of activated carbon required to reduce the concentration of trichloroethylene and the like in water to 0.1 ppm or less is about 10 times less than when ACF is used. Doubled,
Also, the amount of steam required to regenerate the large amount of granular activated carbon is about 30 times or more as compared with the case where ACF is used. When the ACF is used, the amount of liquid sent to the storage tank 2 via the reflux path 5 is small because the amount of steam for regeneration is small. That is, when the ACF is used, the water W
The amount of steam S1 for regenerating CF can be significantly reduced as compared with the amount of water W. Since ACF is more expensive than granular activated carbon, in this embodiment, inexpensive granular activated carbon is used for exhaust treatment, but it goes without saying that ACF may be used instead.

The ACF has a pore radius of 8 °.
As described above, those having a diameter of 18 ° or less are preferable because they have excellent adsorption performance of trichlorethylene and the like and can be easily regenerated. Hereinafter, this point will be described in detail.

FIG. 3 shows the relationship between the specific surface area (m ² / g) and the pore radius (Å) of the same series of phenolic ACFs (solid line), and the case of water at 20 ° C. with a trichlorethylene concentration of 100 μg / liter. Specific surface area (m ² /
The relationship (dotted line) between g) and the saturated adsorption amount (mg / g) of trichlorethylene is shown. As is clear from the figure, the saturated adsorption amount of trichlorethylene at 20 ° C. when the pore radius is 12 ° (specific surface area 1500 m ² / g) is 3
In contrast to 0 mg / g, the saturated adsorption amount of trichlorethylene at 20 ° C. when the pore radius is 16 ° (specific surface area: 2000 m ² / g) is 15 mg / g.

Considering that the saturated adsorption amount is large, the ACF pore radius is preferably 18 ° or less, more preferably 15 ° or less, and further preferably 12 ° or less. Note that the pore radius is defined as a pore volume in a graph showing the pore radius distribution of the target ACF in which the horizontal axis is the pore radius and the vertical axis is the pore volume of the pore having the pore radius. Is the maximum value of the pore radius (pore radius when the graph shows the peak top).

As the ACF used in the device of the present invention, it is preferable that the ACF not only has a large saturated adsorption amount but also can be easily regenerated. According to the study results of the present inventors, the pore radius is preferably 8 ° or more from the viewpoint of easy regeneration.

Further, the amount of the above-mentioned ACF used is, on a weight basis, 50 times the amount of trichloroethylene or the like to be brought into contact.
Preferably, the ACF may be any of phenol-based, pitch-based, PAN-based, and cellulose-based ACFs. Phenolic or pitch based are preferred.

Further, in the above embodiment, the steam S1 of 110 ° C. to 150 ° C. which is generated by the steam generating source 4 and is also used for the regeneration of the granular activated carbon is used as the ACF regeneration fluid. Preferably, hot water of 80 ° C. or higher may be used. In this case, the higher the temperature of the hot water, the smaller the amount of hot water required for regeneration.

Next, an experimental example of the present invention will be described in detail. First, the production of the ACF used in each experimental example will be described. One of them is a phenolic ACF, which is disclosed in JP-B-48-1128.
No. 4 was prepared by the same method as described in Japanese Patent Publication No.
Specifically, a thermoplastic novolak phenol resin is spun at a spinning temperature of 180 ° C. so as to have a fiber diameter of 15 μm, and after exiting from the spinning nozzle, the fiber is wound in a tow shape. The fibrous phenol resin thus obtained was made infusible by reacting in a formalin hydrochloride solution for 4 hours. By heating the phenolic resin fiber thus obtained, carbonization was performed, and this was further activated in 950 ° C. high-temperature steam for 20 minutes. The specific surface area of the ACF thus obtained is 150
0 m ² / g, the pore radius was 12 °, the yield from the infusible yarn was 31% by weight, and the fiber diameter of the phenolic ACF after carbonization and activation was about 13 μm.

In the above-mentioned production process, the specific surface area is changed to 1000 m ² /
g, 2000 m ² / g, 2500 m ² / g phenolic ACF was also prepared. The pore radius (Å) and the yield (% by weight) in the specific surface area of each of the phenolic ACFs are as shown in FIG.

The other one is a pitch-based ACF, which is made of 95% isotropic pitch-based carbon fiber (produced by Kureha Chemical Co., Ltd., having a fiber diameter of about 15 μm).
Activated in hot steam at 0 ° C. for 25 minutes. The specific surface area of the ACF thus obtained is about 1000 m ² /
g, the yield from carbon fibers was 65% by weight and the fiber diameter was about 14 μm. The pore radius was 11 °. In the case of a phenolic fiber or an isotropic pitch-based carbon fiber, it was easy to produce an ACF having a specific surface area of 700 m ² / g or more by activating.

EXPERIMENTAL EXAMPLE 1 Exhaust gas containing trichlorethylene generated from dry cleaning equipment for small clothes generally used,
It processed using the water treatment apparatus of FIG. In the step of regenerating the granular activated carbon tank 7 using the steam S2 from the steam generation source 4, a mixed liquid (raw water) a of trichlorethylene and water was discharged from the granular activated carbon tank 7. The mixed solution a was collected in the storage tank 2, and trichlorethylene and water were separated into layers. The separated trichlorethylene was reused by returning to the original step.

On the other hand, 600 g of a phenol-based ACF having a specific surface area of 1000 m ² / g and a pore radius of 9 ° prepared as described above was placed in a stainless steel cylinder having a diameter of 15 cm and a length of 30 cm. The water purifier 3 was produced by filling. A stainless steel wire mesh of 100 mesh was attached to both sides of the cylinder of the water purifier 3 to prevent the ACF from falling off.

On the first day, about 20 liters of waste water W containing trichlorethylene separated at a concentration of 1000 ppm in the storage tank 2 was passed from the storage tank 2 to the water purifier 3 using a small pump. However, the concentration of trichlorethylene in the treated water W1 after the passage is 0.0%
It was 1 ppm, and it was possible to dispose of the system as it was.

Next, the water purifier 3 filled with the above-mentioned phenol-based ACF to which trichloroethylene has been adsorbed,
The phenolic ACF was regenerated by passing steam (steam) S1 at 15 ° C. Water vapor S1 after passing through the phenolic ACF was converted into a liquid by the condenser 9 and sent to the storage tank 2. The amount of water separated in the storage tank 2 was about 5 liters.

On the next day, the above-mentioned garment cleaning device was operated again, and the granular activated carbon tank 7 was regenerated.
A mixed solution a of water and trichlorethylene was discharged, and a total of 25 liters of an aqueous layer was stored in the storage tank 2. When the water W was passed through the water purifier 3 and purified by the phenol-based ACF, the concentration of trichlorethylene was also 0.01 ppm. Thereafter, the phenol-based ACF of the water purifier 3 was regenerated with the steam S1. By repeating such an operation, the purification treatment of the mixed solution a containing trichloroethylene could be significantly improved.

Comparative Example 1 In Experimental Example 1, when the ACF was not regenerated, the concentration of the treated water W1 from the water purifier 3 was increased to 0.15 ppm on the second day.

Experimental Example 2 The experiment was conducted in exactly the same manner as in Experimental Example 1 except that tetrachloroethylene was used as a solvent for clothing dry cleaning. As a result, the concentration of tetrachlorethylene contained in the aqueous layer of the storage tank 2 was about 150 ppm, but the purification treatment of the mixed solution a containing tetrachloroethylene could be performed very easily as in the case of Experimental Example 1.
The concentration of tetrachloroethylene in the treated water W1 on the second day was 0.01 ppm.

Experimental Example 3 1,1,1- as a solvent for dry cleaning of clothing
The experiment was performed in exactly the same manner as in Experimental Example 1 except that trichloroethane was used. As a result, the purification treatment of the mixed solution a was performed under the same conditions as in the above-described Experimental Example 1. On the second day, the concentration of 1,1,1-trichloroethane in the treated water W1 is 0.1.
It was 01 ppm.

Experimental Example 4 An experiment was performed in exactly the same manner as in Experimental Example 1, except that the pitch-based ACF produced as described above was used. As a result, similar to the case of Experimental Example 1, the cleaning treatment of the mixed solution a could be performed very easily. The concentration of trichlorethylene in the treated water W1 on the second day was 0.01 ppm.

[0039]

As described above, according to the present invention, raw water is stored in a storage tank, and organic substances such as trichlorethylene contained in the water layer of the storage tank are adsorbed and removed. By using the ACF and the regeneration of the ACF by supplying the regeneration fluid to the ACF, it is possible to perform a predetermined water purification process with high efficiency, and to use the adsorbent that adsorbs and retains organic substances. Problems associated with disposal can be eliminated.

Moreover, by sending the regenerated fluid used for the regeneration of the ACF to the storage tank through the reflux path, organic substances such as trichloroethylene contained in the regenerated fluid are completely recovered without being discharged out of the system. be able to.

The storage tank is used for storing raw water and for storing a regeneration fluid containing an organic substance such as trichlorethylene, and does not require a separate tank for storing the used regeneration fluid. In addition, since the amount of regeneration fluid required for regeneration can be reduced by using the ACF, the size of the storage tank can be the same as that without the ACF water purifier, even though the storage tank is shared. Therefore, the entire apparatus capable of completely preventing organic substances such as trichlorethylene from being discharged out of the system can be configured compactly and at low cost.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing the principle of the present invention.

FIG. 2 is a schematic configuration diagram showing an embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a relationship between a specific surface area of a phenolic ACF and a pore radius, and a relationship between a specific surface area and a saturated adsorption amount of trichlorethylene.

FIG. 4 is a chart showing the pore radius and the yield in the specific surface area of each of the phenolic ACFs used in the experimental examples.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Raw water generation source, 2 ... Storage tank, 3 ... Water purifier (processing means), 4 ... Regeneration fluid source, 5 ... Reflux path, 6 ... Source of organic matter-containing exhaust gas, 7 ... Granular activated carbon tank, a ... Raw water, b: Organic substance-containing exhaust gas, c: Organic substance-containing vapor, S1, S2: regeneration fluid, T: Organic substance, W: Water containing organic substance (water layer), W1
... treated water.

Claims (1)

(57) [Scope of request for utility model registration] Claims: 1. A storage means for storing raw water containing organic matter, and a treatment means comprising activated carbon fibers for obtaining treated water by absorbing and removing organic matter contained in an aqueous layer in the storage tank.
A water treatment apparatus comprising: a regenerating fluid source for supplying a regenerating fluid composed of hot water or steam to the processing means; and a recirculation path for sending the regenerating fluid having exited the processing means to the storage tank.