JPH0567386U - Water treatment equipment - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to effectively and efficiently purify water by regenerating activated carbon fibers for adsorbing and removing organic substances without discharging organic substances such as trichlorethylene out of the system. In addition, the entire device can be made compact. [Structure] A tank 2 for storing organic substances such as trichlorethylene contained in raw water a is provided, and steam is added to a treatment means 3 equipped with activated carbon fibers for adsorbing organic substances contained in water W discharged from the tank 2. The regeneration fluid source 4 for supplying the regeneration fluid S1 as described above is connected, and the regeneration fluid S1 exiting the processing means 3 is returned to the tank 2 via the return passage 5.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 This invention is for example waste water containing organic substances such as trichloroethylene, 1,1,1-trichloroethane, or halogenated hydrocarbons such as tetrachloroethylene (referred to as trichloroethylene) generated in the semiconductor production process or the clothing cleaning process. The present invention relates to a water treatment device used when removing organic substances such as trichlorethylene from raw water.

[Prior Art]

Exhaust gas containing vapor of low boiling point organic matter such as a solvent such as trichloroethylene generated in a semiconductor production factory, a cleaning process of clothes, etc. is usually passed through a purification device filled with granular activated carbon to remove the organic matter. It is released after being absorbed and removed. 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 with adsorbed organic matter is regenerated with steam. Organic substances generated by this regeneration treatment can be reused. On the other hand, the separated water cannot be discarded as it is because the organic matter is dissolved in high concentration.

A method of treating wastewater containing such harmful organic substances as trichlorethylene at a high concentration is to pass water containing trichlorethylene etc. through granular activated carbon and adsorb trichlorethylene etc. onto the granular activated carbon. A method of reducing the concentration of trichlorethylene or the like in water to 0.5 ppm or less is generally used, but in such a general water treatment method, the treatment of granular activated carbon adsorbing trichlorethylene or the like becomes a problem. In other words, granular activated carbon that has adsorbed trichlorethylene, etc. cannot be incinerated, so it must be disposed of such as by being buried in the soil, or used activated carbon must be placed in a completely sealed container for permanent use. It must be either stored in the store or disposed of.

However, in the case of the method of burial and disposal in the soil, there is a problem that trichlorethylene and the like are secondly diffused into the environment, and the method of disposal which is put in a container and permanently preserved. In this case, there is a big problem not only because the treatment cost is high, but also because there is a shortage of waste treatment plants in recent years.

On the other hand, raw water containing organic substances such as trichlorethylene is brought into contact with activated carbon fibers to adsorb and remove trichlorethylene and the like in the raw water from the activated carbon fibers, while activated carbon fibers adsorbed trichloroethylene and the like. A water treatment method has been proposed in which the water is regenerated with a heating gas such as steam (see JP-A-61-42394). It has been proposed that this method can remove organic substances even when the space velocity (SV) is increased to 30 to 50 or more. By raising the SV, the water purification device can be made smaller. It is also proposed in this method that activated carbon fibers having adsorbed an organic substance can be sufficiently regenerated by steam at 100 ° C to 300 ° C.

Compared with the fact that it is usually necessary to heat the granular activated carbon to about 500 ° C. to 700 ° C. to sufficiently regenerate it, the temperature of 100 ° C. to 300 ° C. is an extremely low temperature. Therefore, a special heating furnace is required to regenerate the granular activated carbon, but a special heating furnace is not required to regenerate the activated carbon fiber, and steam is sent into the tube filled with activated carbon fiber. It can be played. Although activated carbon fiber is currently more expensive per unit weight than granular activated carbon, it may be advantageous in terms of overall cost due to the above-mentioned characteristics regarding the regeneration temperature and SV.

[0007]

[Problems to be solved by the device]

 However, in the conventional water treatment method as described above, since the steam used after the regeneration of the activated carbon fiber is condensed and separately treated as wastewater, organic substances such as trichlorethylene are discharged to the wastewater system. Therefore, it could become a source of wastewater containing organic substances such as trichloroethylene again. If you try to remove organic substances such as trichlorethylene in the wastewater system, you will have a new problem that the size of the treatment equipment will be large.

The present invention has been made in view of the above circumstances, and it is possible to efficiently remove organic substances in water without discharging the organic substances such as trichlorethylene out of the system while making the whole compact. It is intended to provide a processing device.

[0009]

[Means for Solving the Problems]

 In order to achieve the above-mentioned object, a water treatment apparatus according to the present invention is a storage tank for storing raw water containing organic matter, and activated carbon for adsorbing and removing organic matter contained in the water layer in the storage tank to obtain treated water. A treatment means provided with fibers, a regeneration fluid source for supplying a regeneration fluid consisting of hot water or steam to the treatment means, and a reflux passage for feeding the regeneration fluid discharged from the treatment means to the storage tank. is there.

[0010]

[Action]

 According to this invention, organic substances such as trichlorethylene are first stored in the storage tank. By passing the aqueous layer separated from the above organic matter in this storage tank through a treatment means equipped with activated carbon fibers, the organic matter dissolved in the aqueous layer is adsorbed and removed by the activated carbon fibers, and the treated water is treated. Is discharged out of the system.

Next, a regeneration fluid consisting of warm water or steam is supplied to the treatment means to desorb organic substances such as trichlorethylene adsorbed on the activated carbon fibers and regenerate the activated carbon fibers. On the other hand, the desorbed organic matter is returned to the storage tank together with the regenerated fluid. Organic matter can be recovered and reused because it separates from water in the storage tank. By repeating such an operation, it is possible to efficiently treat the raw water containing the organic substance such as trichlorethylene without discharging it to the outside of the system.

[0012]

【Example】

 First, the principle of this 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 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 two layers due to the difference in specific gravity. The organic matter T is dissolved in the water W, but this water W is supplied to the treatment means 3, where the treated water W1 obtained by adsorbing and removing the organic matter T is purified, and discharged to the outside of the system. It

The treatment means 3 allows the water W in which the organic substance T discharged from the storage tank 2 is dissolved to pass through and adsorbs the organic substance T represented by trichlorethylene and the like contained therein. A water purifier having activated carbon fibers (hereinafter referred to as ACF = Activated Carbon Fiber). A regenerative fluid source 4 for supplying a regenerated fluid S1 is connected to the water purifier 3 via an opening / closing valve V2, and a recirculation path 5 for sending the regenerated fluid S1 discharged from the water purifier 3 to the storage tank 2. Are connected. The organic matter T that has been layer-separated in the storage tank 2 is supplied to a desired process in the raw water generation source 1 and reused there.

Next, an embodiment of the present invention in combination with a source of exhaust gas containing organic matter, an activated carbon tank for treating the exhaust gas, and a regeneration fluid source for regenerating the activated carbon in the activated carbon tank will be described. A description will be given based on FIG. 2, which is a diagram. In FIG. 2, exhaust gas b containing organic substances such as trichlorethylene is discharged from a source 6 of exhaust gas containing organic substances such as a cleaning process of clothes or a production process of semiconductors. It is passed through a tank 7 filled with activated carbon (which may be granular). As a result, after the organic substances such as trichloroethylene contained in the exhaust b are adsorbed and removed, the treated exhaust b1 is released.

The granular activated carbon tank 7 is connected with a steam generation source 4 that generates steam of 110 ° C. to 150 ° C., which is an example of a regenerated fluid of the granular activated carbon, from the steam generation source 4 to the tank 7. By supplying water vapor S2 into the inside, granular activated carbon having adsorbed organic substances such as trichloroethylene is regenerated. As a result, the adsorption capacity is recovered by about 70%. By opening and closing the valves V3 and V4, the exhaust gas b in the normal process step and the water vapor S2 in the regeneration step are selectively supplied to the tank 7.

The water vapor c containing organic substances such as trichlorethylene discharged from the tank 7 in the regeneration step is cooled when it passes through the condenser 8 through which the cooling water CW is passed to become raw water a, and the storage tank 2 It is stored inside. In the storage tank 2, the water W and the organic matter T such as trichlorethylene are separated into upper and lower layers due to the difference in specific gravity. It is returned to the organic matter-containing exhaust gas generation source 6 and reused.

On the other hand, the water W existing in the storage tank 2 and containing a saturated concentration of trichloroethylene or the like (in most cases, about 100 to 1000 ppm) is supplied to the treatment means 3 via the valve V5, and the trichlorethylene or the like is adsorbed there. The treated water W1 that has been removed and purified to a discharge allowable concentration or less (usually 0.1 ppm or less) is obtained, and this is discharged to the outside of the system.

The treatment means 3 is a water purifier having an ACF that allows the water W containing trichlorethylene or the like discharged from the storage tank 2 to pass through and adsorbs the trichlorethylene or the like contained therein. The water purifier 3 is connected to a steam generation source 4 (regeneration fluid source) for supplying steam S1 of 110 ° C. to 150 ° C. as a regeneration fluid via an opening / closing valve V2, and the water purifier 3 is discharged. A recirculation path 5 is connected to which the regeneration steam S1 is cooled by a condenser 9 through which cooling water CW is passed to be a liquid and then returned to the storage tank 2. The water W containing trichlorethylene and the like and the steam S1 are selectively supplied to the water purifier 3 by opening and closing the valves V5 and V2.

By the way, the ACF loaded in the water purifier 3 is superior to the granular activated carbon in the saturated adsorption amount by about 2 to 8 times, and the adsorption speed is also extremely high. Therefore, the amount of ACF required to reduce the concentration of trichlorethylene or the like to 0.1 ppm or less is much smaller than in the case of granular activated carbon. Also, the amount of water vapor required for regeneration is much smaller than in the case of granular activated carbon.

For example, when granular activated carbon is used instead of ACF, the amount of activated carbon required to reduce the concentration of trichloroethylene or the like in water to 0.1 ppm or less is lower than that when ACF is used. The amount of water vapor required to regenerate a large amount of the granular activated carbon is about 30 times or more as compared with the case of using ACF. Further, when ACF is used in this way, the amount of water vapor for regeneration is small, so that the amount of liquid sent to the storage tank 2 via the reflux path 5 can be small. That is, when the ACF is used, the amount of the water vapor S1 for regenerating the ACF obtained by purifying the water W can be significantly reduced as compared with the amount of the water W. Since ACF is more expensive than granular activated carbon, inexpensive granular activated carbon is used for exhaust treatment in this embodiment, but it goes without saying that ACF may be used instead.

As the ACF, those having a pore radius of 8 Å or more and 18 Å or less are preferable because they have excellent adsorption performance for trichloroethylene and the like and can be easily regenerated. This point will be described in detail below.

FIG. 3 shows the relationship between the specific surface area (m ² / g) and the pore radius (Å) of the same series of phenolic ACF (solid line), and the case of water at 20 ° C. with a trichlorethylene concentration of 100 μg / liter. 3 shows the relationship (dotted line) between the specific surface area (m ² / g) and the saturated adsorption amount (mg / g) of trichloroethylene. As is clear from the figure, when the pore radius is 12Å (specific surface area 1500 m ² / g), the saturated adsorption amount of trichlorethylene at 20 ° C is 30 mg / g, whereas the pore radius is 16Å. In the case of (specific surface area 2000 m ² / g), the saturated adsorption amount of trichlorethylene at 20 ° C. is 15 mg / g.

From this, considering that the saturated adsorption amount is large, the ACF pore radius is preferably 18 Å or less, more preferably 15 Å or less, and further preferably 12 Å or less. The above-mentioned pore radius is a graph showing the pore radius distribution of the target ACF where the horizontal axis is the pore radius and the vertical axis is the pore volume of the pores having the pore radius. It is the value of the pore radius where the volume is maximum (pore radius when the graph shows the peak top).

The ACF used in the device of the present invention is preferably one that not only has a large saturated adsorption amount but also can be easily regenerated. According to the results of the study by the present inventor, the pore radius is preferably 8 Å or more from the viewpoint of facilitating regeneration.

Further, the amount of the ACF used is preferably about 50 to 300 times the amount of trichloroethylene or the like to be contacted on a weight basis, and the ACF is a phenol type, pitch type, PAN type or cellulose type. Although any of the above may be used, a phenol type or a pitch type is preferable from the viewpoint that it is easy to form the one having a pore radius of about 12Å.

Further, in the above-mentioned embodiment, the steam S1 of 110 ° C. to 150 ° C., which is generated in the steam generation source 4 and is also used for the regeneration of the granular activated carbon, was used as the regeneration fluid of the ACF. 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 this 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, and this phenolic ACF was prepared by the same method as described in JP-B-48-11284. Specifically, a thermoplastic novolac phenolic resin is spun at a spinning temperature of 180 ° C. to a fiber diameter of 15 μm, and the fiber is wound in a tow-like shape after exiting from the spinning nozzle. The fibrous phenolic resin thus obtained was made infusible by reacting it in a formalin hydrochloride solution for 4 hours. The phenol resin fiber thus obtained was heated to carbonize it, and this was further activated in high temperature steam at 950 ° C. for 20 minutes. The thus-obtained ACF has a specific surface area of 1500 m ² / g, a pore radius of 12 liters, a yield of 31% by weight from the infusibilized yarn, and a phenolic ACF fiber after carbonization and activation. The diameter was about 13 μm.

In addition, in the above manufacturing process, by changing the activation time, phenolic AC F having a specific surface area of 1000 m ² / g, 2000 m ² / g, 2500 m ² / g was also manufactured. The pore diameter (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 an isotropic pitch-based carbon fiber (manufactured by Kureha Chemical Co., Ltd., fiber diameter: about 15 μm) in high temperature steam at 950 ° C. Was activated for 25 minutes. The specific surface area of the ACF thus obtained was 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 11Å. In the case of phenol fiber or isotropic pitch carbon fiber, it was easy to produce ACF having a specific surface area of 700 m ² / g or more by activating.

Experimental Example 1. Exhaust gas containing trichlorethylene generated from a commonly used small clothes dry cleaning device was treated using the water treatment device shown in FIG. In the regeneration process of 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 liquid 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 process.

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

On the first day, about 20 liters of waste water W containing trichloroethylene separated in the storage tank 2 at a concentration of 1000 ppm is passed from the storage tank 2 to the water purifier 3 using a small pump. As a result, the concentration of trichloroethylene in the treated water W1 after passing was 0.01 ppm, and it was possible to discard it outside the system as it was.

Next, the phenolic ACF was regenerated by passing steam (steam) S1 at 115 ° C. through the water purifier 3 filled with the above phenolic ACF that adsorbed trichloroethylene. The water vapor S1 having passed through the phenolic ACF was made into a liquid by the condenser 9, and this liquid was 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 clothes cleaning device was operated again to regenerate the granular activated carbon tank 7. As a result, a mixed liquid a of water and trichlorethylene was discharged, and a total of 25 liters was stored in the storage tank 2. The water layer was stored. When this water W was passed through the water purifier 3 to be purified with phenolic ACF, the concentration of trichloroethylene was still 0.01 ppm. Then, the phenolic ACF of the water purifier 3 was regenerated with the steam S1 again. By repeating such an operation, the purification treatment of the mixed liquid a containing trichlorethylene 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 increased to 0.15 ppm on the second day.

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

Experimental Example 3. An experiment was conducted in exactly the same manner as in Experimental Example 1 above, except that 1,1,1-trichloroethane was used as a solvent for dry cleaning clothes. As a result, the purification treatment of the mixed liquid a could be performed under the same conditions as in Experimental Example 1 above. The concentration of 1,1,1-trichloroethane in the treated water W1 on the second day was 0.01 ppm.

Experimental Example 4. An experiment was conducted 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, as in the case of Experimental Example 1 above, the purification treatment of the mixed liquid a could be performed very easily. The concentration of trichloroethylene in the treated water W1 on the second day was 0.01 ppm.

[0039]

[Effect of the device]

 As described above, according to this invention, raw water is stored in the storage tank, organic substances such as trichlorethylene contained in the water layer of the storage tank are adsorbed and removed, and ACF is used as the activated carbon for adsorption removal. By combining it and supplying the regeneration fluid to the ACF to regenerate the ACF, it is possible to perform a predetermined water purification treatment with high efficiency and to dispose of the adsorbent that adsorbs and holds the organic matter. Problems associated with disposal can be resolved.

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

Further, the storage tank is commonly used for storing raw water and for storing a regenerating fluid containing an organic substance such as trichlorethylene, and does not require a separate tank for storing the used regenerating fluid. Moreover, since the amount of regeneration fluid required for regeneration is small due to the use of ACF, the size 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 the discharge of organic substances such as trichlorethylene to the outside of the system can be configured compactly and at low cost.

[Brief description of 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 pore radii and yields in specific surface areas of phenolic ACFs used in 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 ... Generation source of organic substance-containing exhaust gas, 7 ... Granular activated carbon tank, a ... Raw water, b ... Organic matter-containing exhaust gas, c ... Organic matter-containing vapor, S1, S2 ... Regeneration fluid, T ... Organic matter, W ... Water containing organic matter (water layer), W1
… Treated water.

Claims (1)

[Scope of utility model registration request] 1. A storage tank comprising a storage tank for storing raw water containing organic matter, and a treatment means comprising activated carbon fibers for adsorbing and removing organic matter contained in a water layer in the storage tank to obtain treated water.
A water treatment apparatus comprising: a regenerating fluid source for supplying a regenerating fluid consisting of hot water or steam to the treating means; and a reflux path for feeding the regenerating fluid discharged from the treating means to the storage tank.