JP2001246365A - Process and equipment for separation/decomposition treatment of volatile organic compound in water to be treated - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate volatile organic compounds such as trichloroethylene and tetrachloroethylene from water to be treated which contains these volatile organic compounds, such as groundwater or industrial wastewater and thereafter, to perform decomposition treatment of the separated volatile organic compounds, with a small-sized equipment. SOLUTION: This separation/decomposition treatment process comprises: irradiating water to be treated 2 received in a separation vessel 1 with ultrasonic waves to volatilize volatile organic compounds contained in the water to be treated 2, from the water 2; extracting the volatilized volatile organic compounds out of the vessel 1, bringing the extracted volatile organic compounds into contact with a nonvolatile liquid 14 in which the organic compounds are soluble to dissolve the extracted volatile organic compounds in the nonvolatile liquid 14; then, irradiating the nonvolatile liquid 14 containing the dissolved volatile organic compounds with ultrasonic waves in a decomposition vessel 13 to cause cavitation within the nonvolatile liquid 14 and to decompose the volatile organic compounds in the nonvolatile liquid 14; and thereafter, returning the nonvolatile liquid 14 thus treated to the preceding stage for dissolving the volatile organic compounds extracted from the separation vessel 1, in the nonvolatile liquid 14.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for separating volatile organic compounds from treated water when the treated water such as groundwater or industrial wastewater contains a volatile organic compound such as trichloroethylene or tetrachloroethylene. Thereafter, the present invention relates to a method for decomposing and a device therefor.

[0002]

2. Description of the Related Art Conventionally, in treating water such as groundwater or industrial wastewater, volatile organic compounds such as trichloroethylene or tetrachloroethylene contained therein are separated from the treated water and then subjected to decomposition treatment. Bubbling (aeration) of blowing gas such as air into the treated water is performed, and volatile organic compounds in the treated water are separated from the treated water by volatilizing in the gas blown into the treated water. A method is employed in which the gas containing the volatile organic compound is guided to a decomposer by irradiating ultraviolet rays or the like to decompose the volatile organic compound.

[0003]

However, in this bubbling method, the amount of bubbling gas blown into the treated water must be increased in order to increase the separation rate of volatile organic compounds from the treated water. In addition, since a large amount of gas must be handled, the size of the entire apparatus cannot be avoided, and the size and size of the blower for feeding the air increase the noise and power consumption.

In addition, in the bubbling method, although a large amount of gas is discharged from the treated water, the amount of volatile organic compounds contained in the discharged gas is extremely small, so that the volatile gas in the large amount of exhaust gas is volatilized. There is also a problem that a large apparatus and a large running cost are required to decompose the organic compound.

An object of the present invention is to provide a method and an apparatus for separating and decomposing volatile organic compounds which have solved these problems.

[0006]

According to a first aspect of the present invention, there is provided a method for irradiating treated water contained in a separation vessel with ultrasonic waves by an ultrasonic transmission vibration unit. Then, the volatile organic compound in the treated water is volatilized from the treated water, and the volatile organic compound that has volatilized is bled out of the separation container, and comes into contact with the nonvolatile liquid in which the volatile organic compound is dissolved. Then, the non-volatile liquid is returned to the dissolution of the volatile organic compound extracted from the separation container after cavitation is generated in the decomposition container by irradiation of ultrasonic waves by the ultrasonic transmission vibration unit. It is characterized by that. "

[0007] The method according to claim 2 is characterized in that "in addition to blowing gas into the treated water contained in the separation vessel,
By irradiating the ultrasonic wave by the ultrasonic transmission vibration part, the volatile organic compound in the treated water is volatilized from the treated water, and the volatile organic compound thus volatilized together with the gas blown into the treated water is used as the separation vessel. It bleeds out and comes into contact with the non-volatile liquid in which the volatile organic compound is dissolved, and then the non-volatile liquid is subjected to cavitation by irradiation of ultrasonic waves with an ultrasonic transmission vibration part in a decomposition container. After the occurrence,
While returning to the dissolution of the volatile organic compound extracted from the separation vessel, the gas discharged from the decomposition vessel is returned to the blowing of gas into the treated water in the separation vessel. Is the thing.

[0008]

According to the first aspect of the present invention, the treated water contained in the separation vessel is irradiated with ultrasonic waves by the ultrasonic transmitting and oscillating portion, so that the treated water is applied to the surface of the treated water. A volatile organic compound having a boiling point different from that of water due to a phenomenon of violent mist atomization and / or degassing occurs from the treated water in a vapor phase above the treated water. Will be volatilized.

Then, the volatile organic compound which has been volatilized is extracted to the outside of the container for separation, and is brought into contact with a non-volatile liquid in which it is dissolved, whereby the volatile organic compound from the container for separation is removed. In other words, the non-volatile liquid is dissolved at a high concentration.

Therefore, the non-volatile liquid is guided into the decomposition container, and cavitation is generated in the non-volatile liquid by irradiating the non-volatile liquid with ultrasonic waves by the ultrasonic transmission vibration unit in the decomposition container. The volatile organic compound dissolved in the liquid is decomposed in a high-temperature, high-pressure reaction field when the bubbles generated in the cavitation collapse and disappear, and thus the volatile organic compound is decomposed. The non-volatile liquid is used repeatedly to dissolve the volatile organic compound extracted from the separation container, thereby separating the volatile organic compound contained in the treated water from the treated water. After that, it is possible to surely perform the decomposition process.

[0011] In addition, the volatile organic compound in the treated water is separated from the treated water by irradiation of ultrasonic waves in the separating container as described in claim 2; In combination with the bubbling method of blowing a gas, the separation of the volatile organic solvent from the treated water can be performed synergistically by irradiation of ultrasonic waves and bubbling of the gas. Compared to the conventional case, the amount of the bubbling gas blown into the treated water is kept at a high value for the separation rate of volatile organic compounds from the treated water, compared to the case where the separation is performed only by bubbling. It can be reduced as much as possible.

Therefore, according to the first to fourth aspects of the present invention, it is possible to eliminate the use of a gas such as air when separating and decomposing volatile organic compounds from treated water. In addition to greatly reducing the amount of gas used, such as air, the process of decomposing volatile organic compounds separated from treated water and generating cavitation by irradiating ultrasonic waves to the non-volatile liquid that dissolves them Therefore, it is possible to reduce the size of the entire apparatus, reduce noise, and reduce power consumption.

In particular, the gas used for bubbling the treated water in the separation vessel is repeatedly used for bubbling the treated water again, so that the amount of newly used gas can be reduced. , The running cost can be further reduced, and the emission of gas into the atmosphere can be reduced to achieve low pollution.

According to a fifth aspect of the present invention, a cooling means for the non-volatile liquid is provided to lower the temperature of the non-volatile liquid, thereby increasing the solubility of the volatile organic compound in the non-volatile liquid. In addition, since the decomposition of the volatile organic compound by cavitation is promoted in the decomposition container, the performance of the decomposition treatment of the volatile organic compound in the decomposition container can be further improved, and the above-described effect can be obtained. It can help further.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment.

In this figure, reference numeral 1 denotes a closed type separation vessel, in which treated water 2 containing a volatile organic compound such as trichloroethylene or tetrachloroethylene is supplied with treated water. The liquid level 2a of the treated water 2 supplied from the pipe 3 is supplied to the discharge pipe 6 with the discharge pump 5 from the separation vessel 1 by the liquid level meter 4 provided for the liquid level 2a. By controlling the opening and closing of the provided discharge valve 7, the height is always kept substantially constant.

On the bottom surface of the separation vessel 1, an ultrasonic transmission vibration section 8 transmits the ultrasonic waves from the ultrasonic transmission vibration section 8 from the liquid phase of the treated water 2 in the separation vessel 1 to the liquid level 2a. It is mounted so that it irradiates in the direction toward it.

A nozzle 9 for blowing gas sent from a bubbling gas supply pipe 10 into the treated water 2 is provided at the bottom of the vessel 1.
As the bubbling gas, air can be used, and an inert gas such as argon or nitrogen and an active gas such as oxygen gas can be used.

In this configuration, the present inventors put 40 cc of treated water 2 initially containing 4 ppm of trichloroethylene into the vessel 1, and added 2 cc to the treated water 2.
Table 1 shows the results of an experiment of irradiating a 2.4 MHz ultrasonic wave with the 0-watt ultrasonic transmitting oscillator 6 and measuring the trichlorethylene concentration at each processing time.

[0021]

[Table 1]

Further, the present inventors have stated that, in the container 1,
Initially, 235 cc of treated water containing 100 ppm of trichloroethylene is charged, and nitrogen gas is blown into the treated water 2 from the nozzle 9 in a large amount of about 1.5 liters per minute in substantially the same manner as the conventional bubbling method. The treated water 2
2.4M with ultrasonic transmitter 8 of 20 watts
When irradiating a high-frequency ultrasonic wave of 2 Hz with a 20-watt ultrasonic transmitting vibrator 6 while blowing nitrogen gas into the treated water 2 at a rate of 0.25 liters per minute, which is smaller than the above, at 2.4 MHz. The results of conducting experiments to measure the residual amount (%) of trichlorethylene at each treatment time as appropriate for the three cases of irradiation with high-frequency ultrasonic waves are as follows:
Table 2 shows the results.

[0023]

[Table 2]

As is clear from these tables, by irradiating the treated water with ultrasonic waves, the trichlorethylene contained in the treated water can be surely separated. When performing bubbling on, by using this together with ultrasonic irradiation,
Even if the amount of the bubbling gas blown into the treated water is reduced to about 1/6 that of the conventional bubbling method alone, trichlorethylene can be reliably separated at a higher rate than before.

As described above, the volatile organic compound volatilized from the treated water 2 in the container 1 into the gas phase above the liquid level 2a is discharged from the exhaust pipe 11 connected to the upper part of the container 1 in a water seal type. Is extracted out of the separation container 1 by the suction pump 12 and sent into the closed type decomposition container 13.

A non-volatile liquid 14 such as water or an ethylene glycol aqueous solution in which a volatile organic compound such as trichloroethylene is dissolved is placed in the decomposition container 13. The water is sucked as water for water-sealing by the water-sealing suction pump 12 from the bottom through a circulation line 16 provided with a circulation pump 15, and then circulated again to the decomposition vessel 13. It is configured as follows.

As a result, the volatile organic compound extracted from the separation vessel 1 via the exhaust pipe 11 is supplied to the water-seal type suction pump 12 by the suction pump 12 and the inside of the decomposition vessel 13. Nonvolatile liquid 1 circulating between
4 and dissolved in it.

The non-volatile liquid includes water,
A chemically stable solution whose volatility is less than that of water, or
Means aqueous solution.

In this manner, the non-volatile liquid 14 in which the volatile organic compound extracted from the separation container 1 is dissolved is
In the disassembling container 13, cavitation is generated by irradiating an ultrasonic wave having a frequency of, for example, 200 KHz from an ultrasonic transmission vibration unit 17 provided on the bottom surface thereof.

The non-volatile liquid 14 in the decomposition container 13
By violently repeating the generation of air bubbles in the cavitation and the collapse and disappearance of the air bubbles, the volatile organic compound dissolved in the nonvolatile liquid 14 is removed by the air bubbles generated in the cavitation. Can be decomposed into final decomposed compounds such as water, carbon dioxide and hydrochloric acid in a reaction field under high temperature and high pressure when crushing disappears.

When the volatile organic compound is separated from the treated water 2 in the separation vessel 1, the bubbling gas blown into the treated water 2 is the volatile organic compound separated from the treated water in the separation vessel 1. Together with the decomposition container 1 by the suction pump 12
The gas is discharged from the gas-liquid separation portion 13a provided at the upper part of the container 3. A part or all of the gas discharged from the decomposition container 13 is supplied to the gas supply pipe for bubbling through a gas circulation line 18. The gas is sent to the passage 10 and is reused as the bubbling gas blown from the nozzle 9 into the separation vessel 1.

Thus, the gas can be used repeatedly, so that the amount of newly used gas can be reduced, the running cost can be further reduced, and the emission of gas into the atmosphere can be reduced.

The gas circulation line 18 is provided with a conventionally known volatile organic compound removing device 19 for decomposing by ultraviolet rays or adsorbing activated carbon. The volatile organic compound is removed therefrom. A part or all of the gas discharged from the container 13 may be used as the bubbling gas blown into the dispensing container 1, and the rest may be released to the atmosphere.

Further, a cooler 20 is provided in a circulation line 16 of the volatile liquid from the decomposition container 13 to the suction pump 12 to lower the temperature of the nonvolatile liquid 14 so as to reduce the temperature of the nonvolatile liquid 14. In addition to increasing the solubility of the volatile organic compound in the decomposition vessel 13, the decomposition of the volatile organic compound by the cavitation is promoted in the decomposition vessel 13. The performance can be further improved.

As the bubbling gas into the separation vessel 1, air can be used.
An inert gas such as an argon gas or a nitrogen gas, and an active gas such as an oxygen gas can be used.When a nitrogen gas or a gas containing a nitrogen gas is used, nitric acid or nitrous acid can be formed by a reaction between water and the nitrogen gas. In this case, it is preferable to avoid using a gas containing nitrogen gas.

Next, FIG. 2 shows a second embodiment.

According to the second embodiment, the contact between the volatile organic compound extracted from the separation container 1 and the non-volatile liquid is controlled by the outside of the decomposition container 13 as in the first embodiment. Instead of using the suction pump 12, the decomposition vessel 1
3 is performed.

That is, a gas-liquid contact portion 21 such as a packed layer of Raschig rings is provided in the upper part of the decomposition vessel 13, and an exhaust blower 22 is provided from the separation vessel 1 through the exhaust pipe 11.
In some cases, a gas is extracted together with a small amount of atmospheric air introduced from the air pipe 24, and the gas is passed upward through the gas-liquid contact portion 21 from the bottom while the gas is extracted inside the decomposition container 13. Of the non-volatile liquid 14 of the gas-liquid contact portion 21
By spraying the volatile organic compound extracted from the separation vessel 1 to the non-volatile liquid in the gas-liquid contact portion 21 by spraying the gas from the nozzle 23 to the upper portion of the gas-liquid contact portion. By contacting the gas and liquid at 21, the volatile organic compound can be dissolved in the nonvolatile liquid, and at the same time, the rise in the temperature of the nonvolatile liquid can be prevented.

In this case, by introducing a small amount of atmospheric air from the air pipe 24, it is possible to further prevent the temperature of the nonvolatile liquid from rising. Atmospheric air introduced here may be configured to be introduced into the separation vessel 1.

In order to contact the volatile organic compound extracted from the separation vessel 1 with the non-volatile liquid, it is needless to say that a conventionally known gas-liquid contact means of a type other than the above may be employed. Absent.

In the above-described embodiment, the ultrasonic oscillation unit 8 is provided on the bottom surface of the separation container 1, and the ultrasonic wave from the ultrasonic oscillation unit 8 is supplied to the treated water 2 in the separation container 1. In this case, the present invention is not limited to this, and the ultrasonic transmission vibrating unit may be provided in the separation vessel 1 as shown in FIG. 8 is inserted so as to be immersed in the treated water 2 in the container 1, so that the ultrasonic waves from the ultrasonic transmission vibration unit 8 are directly irradiated on the treated water 2. Is also good.

In the above-described embodiment, the cavitation is generated in the non-volatile liquid 14 by mounting the ultrasonic transmission vibration unit 17 on the bottom surface of the decomposition container 13. Alternatively, as shown in FIG. 4, it is a matter of course that the cavitation may be generated in the non-volatile liquid 14 by inserting the ultrasonic transmission vibration unit 17 into the decomposition container 13. .

[Brief description of the drawings]

FIG. 1 is a diagram showing a first embodiment of the present invention.

FIG. 2 is a diagram showing a second embodiment of the present invention.

FIG. 3 is a view showing a modification of the separation container.

FIG. 4 is a view showing a modification of the disassembling container.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Separation container 2 Treated water 3 Treated water supply line 9 Ultrasonic transmission vibration part 10 Bubbling gas supply line 11 Exhaust line 12 Water ring type suction pump 13 Decomposition container 14 Nonvolatile liquid 16 Circulation line 17 Ultrasonic transmission vibrating section 18 Gas circulation pipe line 19 Volatile organic compound removal device 20 Cooler 21 Gas-liquid contact section 22 Exhaust blower 23 Nozzle

 ────────────────────────────────────────────────── ─── Continued from the front page (72) Inventor Yoshiaki Miho 6-7-5 Moundoshima, Nishiyodogawa-ku, Osaka F-term in Sasakura Inc. (reference) 4D037 AA01 AA11 AB14 BA11 BA16 BA23 BA26 BB05

Claims (5)

[Claims] An ultrasonic wave is radiated to a treated water contained in a separation vessel by an ultrasonic transmission vibrating unit to volatilize volatile organic compounds in the treated water from the treated water. The compound is bled out of the separation container and brought into contact with the non-volatile liquid in which the volatile organic compound is dissolved, and then the non-volatile liquid is added to the non-volatile liquid in the decomposing container by the ultrasonic transmission vibration unit. A method for separating and decomposing volatile organic compounds in treated water, which comprises returning to the dissolution of the volatile organic compounds extracted from the separation container after cavitation is generated by irradiation of a sound wave. 2. In addition to blowing gas into the treated water contained in the separation container, the treated organic water is irradiated with ultrasonic waves by an ultrasonic transmitting and oscillating section to volatilize volatile organic compounds in the treated water from the treated water. Then, the volatile organic compound thus volatilized is extracted out of the separation container together with the gas blown into the treated water, and comes into contact with the non-volatile liquid in which the volatile organic compound dissolves. After cavitation is generated by irradiating an ultrasonic wave by an ultrasonic transmission vibrating section to the ionic liquid in the container for decomposition, and returning to the dissolution of the volatile organic compound extracted from the container for separation, A method for separating and decomposing volatile organic compounds in treated water, wherein the gas discharged from the container is returned to the blowing of gas into the treated water in the container for separation. 3. A separation container containing treated water, and an ultrasonic transmission vibrator for irradiating treated water in the separated container with ultrasonic waves to volatilize volatile organic compounds in the treated water. Gas-liquid mixing means for bringing the volatile organic compound extracted from the upper part of the separation container into contact with a non-volatile liquid for dissolving the same, a decomposition container for receiving the non-volatile liquid from the gas-liquid mixing means, Means for returning the non-volatile liquid in the container to the gas-liquid mixing means, further comprising: an ultrasonic wave generating cavitation by irradiating the non-volatile liquid in the decomposition container with the ultrasonic wave. An apparatus for separating and decomposing volatile organic compounds in treated water, characterized by having a transmission vibrator. 4. A separation vessel for containing treated water, a means for blowing gas into the treated water in the separation vessel, and an ultrasonic wave for irradiating ultrasonic waves to volatilize volatile organic compounds in the treated water. A transmitting vibrator unit, gas-liquid mixing means for contacting the volatile organic compound extracted together with the gas blown into the treatment water from the upper part of the separation container with a non-volatile liquid for dissolving the volatile organic compound, A decomposition vessel for receiving the non-volatile liquid from the means, a means for returning the non-volatile liquid in the decomposition vessel to the gas-liquid mixing means, and a treatment in the separation vessel for the gas exhausted from the decomposition vessel. Means for returning to the means for blowing gas to water,
Separation / decomposition of volatile organic compounds in treated water, characterized in that the decomposition vessel is provided with an ultrasonic transmission vibrating section for generating cavitation by irradiating ultrasonic waves to the non-volatile liquid in the decomposition vessel. Equipment to process. 5. An apparatus for separating and decomposing volatile organic compounds in treated water according to claim 3 or 4, further comprising cooling means for said non-volatile liquid.