JPH0910551A - Treatment of volatile organic compound - Google Patents

Abstract

PURPOSE: To treat a volatile organic compound efficiently and positively and thereby make it harmless by extracting a volatile organic compound from a soil or water by a vacuum or an aeration process, then irradiating the organic compound with an ultraviolet ray in the presence of oxygen to oxidize the organic compound into a first by-product, and bringing the first by-product to come into contact with an alkaline water to obtain a decomposable secondary by-product. CONSTITUTION: Fouled water containing a pollutant such as an organic substance or a nitrogen compound, or a volatile organic compound, is guided to an extraction device 2, then is evaporated by diffusing an air, and is introduced into an irradiation tank 1. In this tank 1, the extract is irradiated with an ultraviolet ray for a specified time using an ultraviolet lamp to obtain a primary by-product by decomposition. Next, the air contained in the irradiation tank 1 is sent to an untreated water tank 6 and the water is allowed to flow into the tank 6 through the water flow orifice, so that the air is diffused from an air diffusion device 7. In addition, alkali is charged into the tank 6, if necessary, to adjust the pH value to 8 or higher, and thereby, a decomposable secondary by-product is obtained. The water contained in the untreated water tank 6 is sent to an aeration tank 12 and then is discharged from a discharging part 14. After mixing this water with fouled water 13, the mixture is allowed to flow through a filled layer 13 and is cleaned using an aerobe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a volatile organic compound which extracts and decomposes a volatile organic compound contained in soil or water.

[0002]

2. Description of the Related Art Conventionally, trichloroethylene (CHCl =
CCl ₂ ) and tetrachloroethylene (CCl ₂ = CCl
_{As a} method for treating a volatile organic compound having a chlorine group such as ₂ ), the constitution described in, for example, JP-A-2-184393 or JP-A2-115096 is known.

In the method for treating a volatile organic compound described in JP-A-2-184393, ozone and hydrogen peroxide are introduced into an aqueous solution containing the volatile organic compound, and ultraviolet rays are applied for about 30 minutes to 1 hour. Irradiation decomposes volatile organic compounds by oxidation.

By the way, in the method described in Japanese Patent Laid-Open No. 2-184393, hydrogen peroxide is used together with the introduction of ozone and the irradiation of ultraviolet rays. However, it is known that the volatile organic compounds contained in the aqueous solution are hardly decomposed unless hydrogen peroxide is used. Therefore, in order to oxidatively decompose the volatile organic compound in the aqueous solution, hydrogen peroxide which is expensive and complicated to operate is required, and there is a problem that the processing apparatus becomes complicated and the processing cost increases.

Further, when the ultraviolet rays pass through the aqueous solution, a considerable amount of the ultraviolet rays are blocked, so that the efficiency of decomposing the volatile organic compounds by the irradiation of the ultraviolet rays is lowered, so that the volatile organic compounds not decomposed in the aqueous solution are reduced. However, in order to surely decompose it without leaving it, it is necessary to irradiate it with ultraviolet rays for a long time of at least 30 minutes to 1 hour or more, and there is a problem that processing efficiency decreases and processing cost increases.

On the other hand, in the method for treating a volatile organic compound disclosed in Japanese Patent Laid-Open No. 2-115096, the volatile organic compound contained in the aqueous solution is volatilized, and the volatilized volatile organic compound is porous together with ozone. Adsorb to the adsorbate,
This porous adsorbate is irradiated with ultraviolet rays to oxidize and decompose volatile organic compounds.

In the method described in Japanese Patent Application Laid-Open No. 2-115096, the volatile organic compound in the gas extracted from the aqueous solution is adsorbed to the porous adsorbate together with ozone and is irradiated with ultraviolet rays. Since it does not block ultraviolet rays, it can be efficiently oxidized and decomposed. However, due to this oxidative decomposition, carbonyl chloride (COC
l ₂ ) and dichloroacetyl chloride (Cl ₂ CHCOC
generate other organochlorine compounds such as l). Therefore, in order to oxidize and decompose these into hydrogen chloride and carbon dioxide, which are the final decomposed products, it is necessary to irradiate ultraviolet rays for a very long time, resulting in a decrease in processing efficiency and an increase in processing cost. There is. Further, a porous adsorbate for adsorbing a volatile organic compound together with ozone is required, which causes a problem that the device becomes complicated and the device price increases. In addition, undecomposed volatile organic compounds and by-products
The porous adsorbate is not surely adsorbed and may be exhausted as it is, and a great deal of labor and cost are required to treat the porous adsorbate on which the by-product is adsorbed harmlessly.

Further, in the methods described in JP-A-2-184393 and JP-A-2-1-115096, when the aqueous solution is sewage or other sewage, in addition to the decomposition treatment of the volatile organic compounds, the sewage is separately purified. It is necessary to perform treatment, and the purification treatment of sewage containing a volatile organic compound is complicated, and there is also a problem of reduction in treatment efficiency.

[0009]

As described above, in the method described in JP-A-2-184393, the volatile organic compounds in the aqueous solution are oxidatively decomposed, so that the hydrogen peroxide is expensive and complicated to operate. Requires complicated processing equipment,
There is a problem that the treatment cost increases, and the reduction of the irradiation amount of the ultraviolet rays by the aqueous solution lowers the decomposition efficiency of the volatile organic compound, lowering the treatment efficiency and increasing the treatment cost.

Further, in the method described in Japanese Patent Application Laid-Open No. 2-115096, another organochlorine compound, which is a by-product oxidatively decomposed by irradiation of ultraviolet rays, is produced, and the oxidative decomposition to the final decomposed product is There is a problem that irradiation with ultraviolet rays is required for a long time, treatment efficiency is lowered, treatment cost is increased, and a porous adsorbate is required, which complicates the apparatus.

Furthermore, in the case of sewage such as sewage, separate steps of decomposing the volatile organic compounds and purifying the sewage must be carried out, which complicates the purifying process and lowers the treatment efficiency. is there.

The present invention has been made in view of the above problems and provides a method for treating a volatile organic compound contained in soil or water efficiently and surely to render it harmless. The purpose is to do.

[0013]

A method for treating a volatile organic compound according to claim 1 extracts a volatile organic compound contained in at least one of soil and water by vacuum or aeration, and extracts this. The gas containing the volatile organic compound is irradiated with ultraviolet rays in the presence of oxygen to oxidize the volatile organic compound, and the gas containing the primary by-product generated by this oxidation is treated with alkaline water. And a secondary by-product that is easily decomposable.

The method of treating a volatile organic compound according to a second aspect is the method of treating a volatile organic compound according to the first aspect, wherein the alkaline water has a pH of 8 or more.

A method for treating a volatile organic compound according to a third aspect is the method for treating a volatile organic compound according to the first or second aspect, in which the first by-product is circulated when contacting with alkaline water. The means forms a closed circulation circuit for concentrating the secondary by-product produced by circulating the alkaline water by means.

A method for treating a volatile organic compound according to a fourth aspect is the method for treating a volatile organic compound according to any one of the first to third aspects, in which the primary by-product is formed by contact with alkaline water. The secondary by-products are decomposed by aerobic organisms.

A method for treating a volatile organic compound according to a fifth aspect is the method for treating a volatile organic compound according to the fourth aspect, wherein water obtained by decomposing the secondary by-product by an aerobic organism is used as a returning means. It is then returned and brought into contact with the primary by-product to form a closed reflux circuit.

A method for treating a volatile organic compound according to a sixth aspect is the method for treating a volatile organic compound according to any one of the first to fifth aspects, wherein a glass tube that transmits 50% or more of ultraviolet rays having a wavelength of 200 nm or less is used. It uses the ultraviolet lamp that it has.

[0019]

The method for treating a volatile organic compound according to claim 1 extracts a volatile organic compound contained in soil or water by vacuuming or aeration, and irradiates ultraviolet rays in the presence of oxygen to the volatile organic compound. Since the compound is oxidized into the primary by-product, the irradiation rate of ultraviolet rays is improved and the efficiency of oxidative decomposition by ultraviolet rays is improved, and the primary by-product is contacted with alkaline water to easily decompose the primary by-products. Since the secondary by-product is efficiently generated and contained in the alkaline water, the alkaline water, which is easy to handle, serves as a carrier for the secondary by-product decomposed from harmful volatile organic compounds, and Processing of by-products becomes easy.

The method for treating a volatile organic compound according to claim 2 is the method for treating a volatile organic compound according to claim 1, wherein the pH of the alkaline water is set to 8 or more.
The secondary by-product is decomposed into a readily decomposable secondary by-product by contact with alkaline water very efficiently.

A method for treating a volatile organic compound according to a third aspect is the method for treating a volatile organic compound according to the first or second aspect, in which the primary by-product is circulated when contacting with alkaline water. By means of which the alkaline water is circulated by means to form a closed circulation circuit and the secondary by-product produced is concentrated, the processing efficiency of the secondary by-product is improved, and
The processing cost of the secondary by-product is reduced.

A method for treating a volatile organic compound according to a fourth aspect is the method for treating a volatile organic compound according to any one of the first to third aspects, in which the primary by-product is formed by contact with alkaline water. Since the easily decomposable secondary by-products thus decomposed are decomposed by aerobic organisms, volatile organic compounds are reliably processed into harmless end products.

The method for treating a volatile organic compound according to a fifth aspect is the method for treating a volatile organic compound according to the fourth aspect, wherein water obtained by decomposing the secondary by-product with an aerobic organism is used as a returning means. Since it forms a closed reflux circuit in which the by-product is returned and brought into contact with the primary by-product again, the by-product is reliably processed without leaking out of the system, and the processing efficiency of the secondary by-product is improved. Improved and the processing cost of secondary by-products is reduced.

The method for treating a volatile organic compound according to claim 6 is the method for treating a volatile organic compound according to any one of claims 1 to 5, wherein a glass tube that transmits 50% or more of ultraviolet rays having a wavelength of 200 nm or less is used. Since the gas containing the volatile organic compound is irradiated with ultraviolet rays by the ultraviolet lamp that it has, the volatile organic compound is oxidatively decomposed into primary by-products in a short time.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of an embodiment of an apparatus for carrying out the method for treating a volatile organic compound of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes an irradiation tank. The irradiation tank 1 is formed in an airtight structure and is provided with an ultraviolet lamp (not shown) such as a xenon lamp, a low-pressure mercury lamp, a high-pressure mercury lamp or the like for irradiating ultraviolet rays. There is. This UV lamp is made of, for example, synthetic quartz glass with 0.001% or less of impurities, and emits UV light with a wavelength of 200 nm or less.
It is composed of a glass tube (not shown) that transmits 0% or more.

Further, the irradiation tank 1 is connected with an extraction device 2 for extracting volatile organic compounds in soil and water together with air by vacuum and aeration. Further, in the irradiation tank 1, a first by-product obtained by decomposing a volatile organic compound by ultraviolet irradiation of an ultraviolet lamp, for example, trichloroethylene (CHCl = CCl ₂ ) as a volatile organic compound.
Is used, an air supply pipe 4 for discharging carbonyl chloride (COCl ₂ ) or dichloroacetyl chloride (Cl ₂ CHCOCl) is connected.

A raw water tank 6 is connected to the air supply pipe 4,
This raw water tank 6 is formed in an airtight structure,
It has a corrosion-resistant structure so that it will not be corroded by acidic water. The raw water tank 6 is provided with a not-shown water inlet into which water flows, and a not-shown stirring means for stirring the introduced water.

Further, at the bottom of the raw water tank 6, an air diffuser 7 communicating with the air supply pipe 4 is formed, and the primary air is conveyed from the air diffuser 7 from the irradiation tank 1 through the air supply pipe 4. Air containing by-products is diffused into the water introduced from the water outlet. Further, in the raw water tank 6, the pH value of the diffused water is detected, and the water flowing from the water outlet is alkaline, for example, pH.
A pH controller 8 for controlling the alkalinity of 8 or more, preferably the alkalinity of 10 or more is connected. Further, at the bottom of the raw water tank 6, a transport pipe provided with a transport pump 9
10 is connected and the alkaline water in the raw water tank 6 is sent out.

The air diffused from the air diffuser 7 is sucked into the raw water tank 6 by the suction means provided at the upper part of the raw water tank 6, and this gas is again irradiated with the oxygen-containing gas such as air into the irradiation tank 1. It may be returned to and irradiated with ultraviolet rays again. By this suction means, the volatile organic substances can be surely decomposed into the primary by-products, the toxic volatile organic substances can be prevented from leaking out of the system, and the treatment can be surely performed.

An aeration tank 12 is connected to the carrier pipe 10, and a raw water pipe (not shown) into which a sewage 13 containing pollutants such as organic substances and nitrogen compounds flows is connected to the aeration tank 12. ing. Further, a discharge unit 14 is provided above the aeration tank 12 to discharge alkaline water from the raw water tank 6 by the transfer pump 9 via the transfer pipe 10.

Further, a packing layer 15 is provided in the aeration tank 12, and the packing layer 15 carries a large number of aerobic organisms which decompose pollutants such as organic substances and nitrogen compounds in the inflowing sewage 13. It is formed by filling a porous material (not shown). Further, above the aeration tank 12, there is provided an aeration device 17 to which a blower 16 that diffuses air into the wastewater 13 and supplies oxygen to aerobic organisms in the packed bed 15 is connected.

At the bottom of the aeration tank 12, there is a packed bed.
A water discharge pipe 19 provided with a water discharge pump 18 for discharging treated water purified by 15 aerobic organisms is connected.
The aeration tank 12 is provided with a backwashing means (not shown) so that the inside of the aeration tank 12 is appropriately backwashed and the collected sludge or the like is separately treated.

Next, the operation of this apparatus will be described for the treatment of sewage.

Containing pollutants such as organic substances and nitrogen compounds, benzene (C ₆ H ₆ ) and toluene (C
₇ H ₈ ), trichloroethylene (CHCl = CCl ₂ )
Sewage 13 containing a volatile organic compound such as or tetrachloroethylene (CCl ₂ = CCl ₂ ) flows into the extraction device 2, and air is diffused into the wastewater 13 to remove the volatile organic compounds in the wastewater 13. Volatilize in the air. Then, the air containing the volatile organic compound flows into the irradiation tank 1. Also,
The wastewater 13 from which the volatile organic compounds have been removed flows into the aeration tank 12 via a raw water pipe (not shown).

Next, an ultraviolet lamp (not shown) of the irradiation tank 1 is turned on, and the air containing the volatile organic compound flowing into the irradiation tank 1 is irradiated with ultraviolet rays. Then, after irradiating the ultraviolet ray for a predetermined time, the air in the irradiation tank 1 is sent to the raw water tank 6 through the air supply pipe 4.

On the other hand, water is introduced into the raw water tank 6 through the water flow port, and the air sent through the air supply pipe 4 is diffused from the air diffuser 7 provided at the bottom of the raw water tank 6. Further, at the time of this air diffusion, the pH value of the water in the raw water tank 6 is measured by the pH controller 8 and sodium hydroxide (NaOH), potassium hydroxide (KOH) or the like is appropriately added to adjust the pH value to pH 8. As described above, the water is stirred by the stirring means (not shown) while controlling the pH to be alkaline at pH 10 or higher.

Then, the air diffusion from the air diffuser 7 is completed,
Even if sodium hydroxide or potassium hydroxide is not added, after the pH value becomes constant at pH 8 or higher, preferably pH 10 or higher, stirring is stopped, the transport pump 9 is driven, and the transport pipe 10 is used. The water in the raw water tank 6 is transported to the aeration tank 12.

Next, the water conveyed from the raw water tank 6 is discharged from the discharge portion 14 provided at the upper part of the aeration tank 12 and flows into the waste water 13 which is flowed in from a raw water pipe (not shown). Then, the water mixed with the dirty water 13 flows through the packed bed 15 in the aeration tank 12 together with the air aerated from the aeration device 17. When the packed bed 15 flows through, the water mixed with the sewage 13 is packed in the packed bed.
It is purified by aerobic organisms supported on a porous material (not shown) 15 and flows down to the bottom of the aeration tank 12.

Then, the purified water at the bottom of the aeration tank 12 is discharged from the water discharge pipe 19 by driving the water discharge pump 18.

By continuing the above treatment steps, aerobic organisms carried on the packed bed 15 in the aeration tank 12 grow, and sludge in the wastewater 13 is filtered by the packed bed 15 to prevent flow-through resistance. In the case of improving the air pollution, sludge and the like are removed by a backflow cleaning means (not shown).

Next, the operation of the above embodiment will be described.

Various experiments were conducted on the treatments in the irradiation tank 1, the raw water tank 6, and the aeration tank 12.

First, as the irradiation tank 1, the irradiation tank 1 as shown in FIG. 2 is formed. The irradiation tank 1 has a diameter of about 400.
The tube body 21 is made of a cylindrical steel plate and has a height of 1000 mm and a height of 1000 mm, and is formed airtight.

Further, a 15 W low-pressure mercury lamp 22 having a length of about 500 mm, which is an ultraviolet lamp, is arranged in the tube body 21. The low-pressure mercury lamp 22 contains, for example, 0.001% impurities.
A glass tube is formed of the following synthetic quartz glass and transmits 50% or more of ultraviolet rays having a wavelength of 200 nm or less. Further, an injection portion 23 is formed on the upper end surface of the tube body 21. Further, the tube body 21 is filled with dry air.

Then, 0.1 ml of trichlorethylene as a volatile organic compound was injected into the tubular body 21, and the irradiation time of ultraviolet rays was changed to carry out Experiment 1-1 on the oxidative decomposition state of trichlorethylene. The results are shown in FIG. 3 and Table 1.

FIG. 3 is a graph in which the vertical axis represents the concentration of trichlorethylene in the tube body 21 (unit is ppm) and the horizontal axis represents the lighting time of the low-pressure mercury lamp 22 (unit is second). In addition, volatile organic compounds such as trichlorethylene and tetrachlorethylene are analyzed by gas chromatography mass spectrometer (GC / MS: Gas
Chromatograph Mass Spectrometer)
Regarding carbonyl chloride (COCl ₂ ) among the primary by-products, after absorbing it in an absorbing solution based on JIS-K-0090,
Dichloroacetyl chloride (Cl ₂ CHCO) was measured by a quantitative method using an ultraviolet absorption spectrum with a colorimeter.
For Cl), dichloroacetic acid (C
HCl2COOH) was measured by the tap water test method (derivatized and quantified by gas chromatography).

Then, in Experiment 1-1 shown in FIG.
It can be seen that the injected trichlorethylene concentration decreases almost exponentially as the irradiation time of ultraviolet rays increases. Also, it can be seen that most of the irradiation time of this ultraviolet ray is oxidized and decomposed only by irradiation for 20 seconds.

Based on this result, 0.1 ml of tetrachloroethylene as a volatile organic compound, cis-1.
2. Dichloroethylene (CHCl = CHCl) 0.05
Each of them was injected and irradiated with ultraviolet rays for about 20 seconds, and the same experiment was carried out for the oxidative decomposition state of these tetrachloroethylene and cis-1.2.dichloroethylene. Table 1 shows the results.

[0050]

[Table 1] From the results shown in Table 1, by irradiation with ultraviolet rays for 20 seconds, most of trichlorethylene was hydrogen chloride (HCl), carbon dioxide (CO ₂ ), as a primary by-product,
It is oxidatively decomposed into carbonyl chloride (COCl ₂ ) and dichloroacetyl chloride (Cl ₂ CHCOCl). Carbonyl chloride is 32 ppm and dichloroacetyl chloride is 130 ppm.
ppm was detected. Also, tetrachlorethylene and ci
Most of s-1.2.dichloroethylene is also oxidatively decomposed into hydrogen chloride, carbon dioxide, carbonyl chloride, etc., and carbonyl chloride is tetrachloroethylene 37 ppm, cis-1.2.
Dichloroethylene was detected at 26 ppm. In addition, in tetrachloroethylene and cis-1.2.dichloroethylene,
There was a by-product other than the above that was generated by decomposition, but could not be identified.

Next, the glass tube of the low-pressure mercury lamp 22 is provided in the irradiation tank 1 with the low-pressure mercury lamp 22 made of fused silica glass which transmits 50% or less of ultraviolet rays having a wavelength of 200 nm or less.
Experiment 1-2 was performed by the same operation as Experiment 1-1. FIG. 4 shows the results.

From the results of Experiment 1-2 shown in FIG. 4, it can be seen that trichlorethylene is hardly oxidatively decomposed even if it is irradiated with ultraviolet rays for a long time when the amount of ultraviolet rays having a wavelength of 200 nm or less is small.

Then, into a glass cell having an inner diameter of 1 cm, 528 ppm of trichlorethylene and 328 ppm of tetrachlorethylene were charged, and the results of measuring the respective transmittances are shown in FIG. From the results shown in FIG. 5, the wavelengths of trichloroethylene and tetrachloroethylene are 2
Absorbs UV light of 40 nm or less, and almost 5 at 200 nm or less
It can be seen that it absorbs nearly 0%.

Next, 80 ml of the gas in the tube body 21 irradiated with ultraviolet rays in Experiments 1-1 and 1-2 was extracted with a glass cylinder (not shown), and 10 ml of ion-exchanged water was collected in this cylinder. Experiment 2 was performed by shaking the cylinder for about 10 minutes. Table 2 shows the results.

[0055]

[Table 2] First, as a result of qualitative analysis of the gas in the cylinder, volatile organic compounds such as carbonyl chloride and dichloroacetyl chloride and primary by-products were detected in trichloroethylene, tetrachloroethylene, and cis-1.2.dichloroethylene. There wasn't.

When the pH value of the liquid in the cylinder was measured, it was found that the pH value in the case of trichlorethylene was 3.
In addition to hydrogen chloride (HCl) and carbon dioxide (CO2), the secondary by-product, easily degradable dichloroacetic acid (C)
HCl2COOH) etc. were detected. 5.9 mg / l of dichloroacetic acid was detected. Furthermore, in the case of tetrachlorethylene and cis-1.2.dichloroethylene, dichloroacetic acid was also not detected.

Therefore, the primary by-products such as hydrogen chloride, carbonyl chloride, dichloroacetyl chloride and the unspecified primary by-products are all dissolved in the ion-exchanged water by contact with the ion-exchanged water or It is considered to have been hydrolyzed.

Next, Experiment 3 was conducted using the experimental apparatus shown in FIG. The experimental apparatus shown in FIG. 6 has substantially the same shape as the irradiation tank shown in FIG. 2, and is made of stainless steel and has a substantially cylindrical tube body 21 having a diameter of about 30 cm and a height of about 80 cm. A xenon flash lamp is provided and an injection part 23 is provided on the upper end surface to form the irradiation tank 1 in an airtight manner. Further, an air supply pipe having a valve 24a from the bottom of the irradiation tank 1
4a is communicated with an air diffuser 7 provided at the bottom of the water tank 6a having an airtight structure to be the raw water tank 6, and the air volume from the top of the water tank 6a is 1
Circulation pipe with blower 24b and valve 24c of 5 l / min
4b communicates with the upper part of the irradiation tank 1 to form a closed circuit. The pipe 21 is filled with dry air, and water having different pH is stored in the water tank 6a.

Then, 0.5 parts of trichloroethylene as a volatile organic compound is injected from the injection part 23 into the tube body 21 of the irradiation tank 1.
After injecting ml and irradiating with ultraviolet light for 20 seconds, bulb 24a,
24c is opened and the blower 24b is driven to aerate the gas in the pipe body 21 to the water in the water tank 6a from the air diffuser 7 and circulate the gas for 15 minutes. Then, the gas in the tube body 21 was quantitatively analyzed. The results are shown in Table 3 and FIG. 7.

[0060]

[Table 3] From the results shown in Table 3 and FIG. 7, the amount of carbonyl chloride, which is the primary by-product in the tube 21, decreases sharply as the pH of water becomes alkaline at 8. No carbonyl chloride was detected. Further, the primary by-product, dichloroacetyl chloride, was not detected regardless of the pH of the water in the water tank 6a.

Therefore, the primary by-product produced by irradiating the volatile organic compound trichlorethylene with ultraviolet rays, particularly carbonyl chloride, is alkaline water, particularly pH 8 or higher, preferably pH 10 or higher. It can be seen that, by using the water of No. 3, the water can be dissolved and absorbed very well, and the water can be efficiently captured.

Next, using vinyl chloride, the diameter is about 400 m.
m, the height of about 600mm synthetic tank 25, and the length of about 210mm,
An aeration tank 26 having a width of about 145 mm and a height of about 500 mm and a settling tank 27 having a diameter of about 150 mm and a height of about 210 mm are formed. Then, as shown in FIG. 8, the bottom of the synthesis tank 25 and the top of the aeration tank 26 are connected by a raw water pipe 29 via a raw water pump 28. Further, the bottom of the aeration tank 26 and the upper part of the settling tank 27 are connected by a water feed pipe 31 via a water feed pump 30, and the settling tank 27
The bottom of the tank is connected to the top of the aeration tank by a reflux pipe 33 via a reflux pump 32. Further, the aeration tank 26 is connected with an air diffuser pipe 35 connected to an air supply pump 34 as an aeration device so that air is aerated in the aeration tank 26. In addition, a water discharge pipe 36 through which the supernatant treated water is discharged outside the apparatus is connected to the upper part of the settling tank 27. Then, using this device, Experiment 4
Was done.

First, water is made to flow into the synthesis tank 25, and 200 mg / l of acetic acid and 100 mg / l of peptone are added to this water to synthesize synthetic wastewater.
Generates 37. This synthetic wastewater 37 has a biochemical oxygen demand (BOD) of 176 mg / l and a chemical oxygen demand (C
OD) was 42 mg / l. On the other hand, the synthetic wastewater 37 that has been synthesized flows into the aeration tank 26 to grow aerobic organisms. The aeration tank 26 does not have the packing layer 15 shown in FIG. 1 and aerobic organisms are suspended in the synthetic sewage 37 by an aeration air lift for purification treatment.

In the treatment of the synthetic sewage 37, the synthetic sewage 37 is allowed to flow into the aeration tank 26 from the synthesis tank 25 at 14 ml / min, and the treated water treated from the aeration tank 26 and floating aerobic organisms are settled in a sedimentation tank. 27 ml at a rate of 14 ml / min, aerobic organisms settling from the bottom of the sedimentation tank 27 are returned to the aeration tank 26 at 7 ml / min, and the treated water in the upper part of the sedimentation tank 27 is discharged at 14 ml / min. Let water drain from.

Under the conditions shown in Table 4, the secondary byproduct dichloroacetic acid produced in Experiment 2 was added to the synthetic wastewater 37 to purify the synthetic wastewater 37. As the purification treatment status of the synthetic wastewater 37, the BOD of the treated water of the supernatant discharged from the settling tank 27 through the discharge pipe 36 was measured, and the result is shown in FIG.

[0066]

[Table 4] From the results shown in FIG. 9, the first treatment stage (RUN) is a purification treatment of only the synthetic wastewater 37 without addition of dichloroacetic acid.
In 1), it can be seen that the BOD value is purified to 10 to 20 mg / l.

Then, in the treatment situation of the synthetic wastewater 37, when 20 mg / l of dichloroacetic acid was added to the synthetic wastewater 37 and the purification treatment of the second treatment stage (RUN2) was carried out, it was slightly BO.
The D value increased and a small amount of dichloroacetic acid was detected in the treated water, but in the latter stage of the treatment, BOD also decreased to 15 mg / l or less and dichloroacetic acid was not detected.

Furthermore, even if the amount of dichloroacetic acid added in the third treatment stage (RUN3) is increased, BOD is also decreased and dichloracetic acid is not detected in the latter stage of the treatment. Then, in the fourth treatment stage (RUN4) in which the amount of added dichloroacetic acid was further increased, dichloroacetic acid was not detected even in the earlier stage of the treatment, the increase in BOD due to the addition of dichloroacetic acid was reduced, and the BOD of treated water was also 15
It drops below mg / l.

That is, in the aerial stage of operation where there are few aerobic organisms decomposing dichloroacetic acid in the aeration tank 26, some dichloroacetic acid is detected in the treated water, but aerobic organisms decomposing dichloroacetic acid in the aeration tank 26 are detected. It can be seen that when is cultivated, it is surely decomposed together with the synthetic wastewater 37.

Therefore, according to the processing method of the present invention,
Toxic volatile organic compounds are decomposed into primary by-products only by short-time UV irradiation, and purified by aerobic organisms by contact with alkaline water, especially pH 8 or more, preferably pH 10 or more alkaline water. Efficient and easy production of easily decomposable secondary by-products and purification treatment with sewage 13, 37 from which volatile organic compounds are extracted makes it easy even without using ozone or hydrogen peroxide. In addition to being able to reliably and efficiently detoxify the wastewater at a low cost, the purification treatment of the wastewater 13 and 37 as well as the purification of the by-product can prevent the contamination by the by-product, and the purification treatment can be performed efficiently.

In the above example, the primary by-product decomposed and produced by the irradiation of ultraviolet rays was once converted into the secondary by-product while controlling the pH value in the raw water tank 6, and this secondary by-product was produced. The secondary by-product was purified in the aeration tank 12,
For example, as shown in FIG. 10, the raw water tank 6 and the aeration tank 12 may be integrally formed.

That is, the aeration tank 12 has an airtight structure, the pH control device 8 is provided in the aeration tank 12, and the primary byproduct is directly aerated to the wastewater 13 in the aeration tank 12, and the secondary byproduct is generated. While forming the product, the secondary by-product is refluxed to the upper part and discharged from the discharge part 14, and the air in the aeration tank 12 is brought into contact with the recycled wastewater 13 while forming the packed bed 15. The secondary by-products in the wastewater 13 are decomposed by aerobic organisms carried by a packing material such as Schichling or a porous material.
With this configuration, the structure of the processing device can be further simplified.

Further, as the contact of the primary by-product with the alkaline water, the explanation was made by aeration in water, but the alkaline water is sprayed into the raw water tank 6 filled with the primary by-product. Either method is possible.

Further, volatile organic compounds are extracted from the wastewater 13 and the soil by vacuum or the like, and the volatile organic compounds are decomposed into primary by-products by ultraviolet rays, and after contact with alkaline water, the wastewater is discharged. Separately from the aeration tank 12, it can be decomposed by aerobic organisms in the aeration tank 12 and then discharged separately from the sewage 13.

Further, although the volatile organic compound having a chlorine group is used as the volatile organic compound, the decomposition treatment can be similarly performed with benzene or toluene.

Next, another embodiment will be described with reference to the drawings.

The embodiment shown in FIGS. 11 and 12 is similar to that shown in FIG.
In addition, an adsorption treatment device is provided instead of the aeration tank 12 of the embodiment shown in FIG.

That is, the volatile organic compounds in the wastewater 13 such as factory wastewater are extracted together with air into the irradiation tank 1 having an airtight structure containing an ultraviolet lamp (not shown) that illuminates 50% or more of ultraviolet rays having a wavelength of 200 nm or less. Device 2 is connected.

The extraction apparatus 2 is provided with an extraction tank 43 in which aeration means 42 for aerating the air from the blower 41 is arranged near the bottom, and the extraction tank 43 is extracted from the wastewater 13 by aeration. Flow control device for volatile organic compounds
An extraction pipe 45, which is adjusted by 44 and sends air, is connected.

Further, the irradiation tank 1 is connected to a raw water tank 6 for diffusing a first by-product decomposed and generated by irradiation of ultraviolet rays from an air diffusing device 7 through an air feeding pipe 4.

Further, as shown in FIG. 12, the raw water tank 6 is formed in an airtight and corrosion resistant structure as in the embodiment shown in FIGS. 1 to 9. Further, a water outlet (not shown) through which the water 48 flows is formed, and a stirring means (not shown) for stirring the introduced water 48 is provided.

At the bottom of the raw water tank 6, an air diffuser 7 communicating with the air supply pipe 4 is formed, and the primary air is transported from the air diffuser 7 from the irradiation tank 1 through the air supply pipe 4. Air containing by-products is diffused into the water 48 that has flowed in through the water outlet. Further, in the intermediate portion of the raw water tank 6, as in the embodiment shown in FIG. 10, a filling layer 49 filled with a filler such as a Raschig ring (not shown) is formed.

Further, as in the embodiment shown in FIG. 10, the raw water tank 6 has a sensor for detecting the pH value of the diffused water 48.
8a, sodium hydroxide (NaOH), sodium carbonate (Na ₂ CO ₃ ), sodium hydrogen carbonate (NaHC
A pH controller 8 for controlling water to neutrality is provided, which is provided with an alkali controller 8b for adding O ₃ ), potassium hydroxide (KOH) and the like.

Further, a circulation pipe 52 provided with a circulation pump 51 as a circulation means is connected to the bottom of the raw water tank 6, and the water in the raw water tank 6 is adjusted while the flow rate is adjusted by a flow meter 53 provided on the way. 48
A closed circulation circuit is constructed in which water is again circulated by water sprinkling means 55 provided on the upper part of the raw water tank 6. The circulation pipe 52 is connected to the carrier pipe 10 provided with a valve 57, and a part of it is returned to the raw water tank 6 so that the inside of the raw water tank 6 drains water 48 as appropriate.

Further, on the upper part of the raw water tank 6, there is an air diffuser 7
Intake means (not shown) for inhaling the gas diffused from is provided, and the inhaled gas is returned to the irradiation tank 1 through the intake pipe 59 to irradiate the ultraviolet rays again. In addition,
The gas from the intake pipe 59 may be appropriately sent to an adsorption treatment device (not shown).

In the adsorption treatment device, an adsorption layer filled with an adsorbent such as activated carbon (not shown) is formed, and when the adsorption layer passes through the adsorption layer, volatile organic compounds contained in the air drawn from the raw water tank 6 By-products are adsorbed,
The treated air is exhausted outside the system.

Next, the processing operation of the apparatus of the embodiment shown in FIGS. 11 and 12 will be described.

Benzene (C ₆ H ₆ ) and toluene (C ₇ H
₈ ) Sewage 13 such as industrial effluent containing volatile organic compounds such as trichlorethylene (CHCl = CCl ₂ ) and tetrachlorethylene (CCl ₂ ═CCl ₂ ) flows into the extraction device 2 and enters this sewage 13. The air from the blower 41 is aerated by the aeration means 42 to volatilize the volatile organic compounds in the wastewater 13 into the air. Then, the air containing the volatile organic compound flows into the irradiation tank 1.

Next, the volatile organic compound-containing air that has flowed into the irradiation tank 1 is appropriately irradiated with ultraviolet rays by an ultraviolet lamp (not shown) as in the embodiment shown in FIGS. When trichloroethylene is used as the compound, for example, volatile organic compound, carbonyl chloride (COCl ₂ ) or dichloroacetyl chloride (Cl ₂ C
HCOCl) and other first by-products are decomposed.

After irradiation with ultraviolet rays for a predetermined time, the air containing the first by-product in the irradiation tank 1 is sent to the raw water tank 6 through the air supply pipe 4. Next, the pH of the water 48 that has flowed into the raw water tank 6 through the water outlet in advance is adjusted by the pH controller 8.
Value is alkaline, eg pH 8 or higher, preferably pH 1
The air blown through the air feeding pipe 4 is diffused from the diffuser 7 while controlling the alkalinity to be 0 or more and stirring the water by a stirring means (not shown).

At the time of this air diffusion, the circulating pump 51 is driven, and the water sprinkling means 55 provided at the upper portion sprinkles the alkaline water 48 to which the air from the irradiation tank 1 is aerated into the packed bed 49,
It is again brought into contact with the air in the raw water tank 6. Further, air is appropriately returned to the irradiation tank 1 from an intake means (not shown) through the intake pipe 59.

By this aeration, the first by-product contained in the air is efficiently dissolved or hydrolyzed in the alkaline water 48 by contact with the alkaline water 48 and captured, and hydrogen chloride (HCl) is added. And dichloroacetic acid (CHCl
2COOH) and other easily decomposable secondary byproducts.
Further, the primary by-product diffused from the water surface into the raw water tank 6 without being contained as a secondary by-product in the water 48 due to contact with the alkaline water 48, is again sprayed by the sprinkling means 55. Contacted with water 48.

Therefore, the primary by-product does not leak to the outside of the system and can be reliably captured by the alkaline water 48, and the sprinkled water 48 already has the primary by-product as the secondary by-product. Since it is contained as a product, the concentration of the secondary by-product in the water 48 is increased and it can be concentrated.

Further, since the air in the raw water tank 6 is sent to the irradiation tank 1 by the suction means, the volatile organic compounds which have not been decomposed by the irradiation of ultraviolet rays are discharged together with the air containing the primary by-product. Even if it flows into the water tank 6, it is returned to the irradiation tank 1 again and decomposed by ultraviolet irradiation, so that harmful volatile organic compounds are surely decomposed into primary by-products without leaking out of the system. , Can be captured in alkaline water. Moreover, even if the volatile organic compound extracted by the extraction device 2 contains a substance that is hardly decomposed by ultraviolet rays, the adsorbent is not returned to the irradiation tank 1 but is blown to the adsorption treatment device 58 that is appropriately extracted. Since it is surely adsorbed and removed by, it is possible to prevent harmful volatile organic compounds from leaking out of the system.

Then, the air diffusion from the air diffuser 7 is completed,
Even without adding sodium hydroxide (NaOH), p
After the H value becomes almost constant, the stirring is stopped and the circulating pump 51 is driven to convey the alkaline water 48 in which the secondary by-products in the raw water tank 6 are concentrated by adjusting the valve 57. tube
It is appropriately extracted through 10 and treated by incineration or biological treatment. Therefore, the second
The amount of water to be treated as the by-product is reduced, and the treatment cost can be reduced.

Next, still another embodiment will be described with reference to the drawings.

The embodiment shown in FIGS. 13 and 14 is similar to that shown in FIG.
The embodiment shown in FIGS. 1 to 12 is provided with the aeration tank 12 of the embodiment shown in FIGS.

That is, the air from the blower 41 is aerated to the irradiation tank 1 having an airtight structure containing an ultraviolet lamp (not shown) that illuminates 50% or more of ultraviolet rays having a wavelength of 200 nm or less.
An extraction device 2 for aerating at 42 and extracting volatile organic compounds in wastewater 13 such as industrial wastewater together with air is connected.

The irradiation tank 1 is connected to a raw water tank 6 for diffusing the first by-product decomposed and generated by irradiation of ultraviolet rays from an air diffusing device via an air feeding pipe 4.

The raw water tank 6 is shown in FIGS.
Similar to the embodiment shown in FIG. 2, it has an airtight and corrosion resistant structure. Further, a water outlet (not shown) through which the water 48 flows is formed, and a stirring means (not shown) for stirring the introduced water 48 is provided.

At the bottom of the raw water tank 6, an air diffuser 7 communicating with the air supply pipe 4 is formed, and the primary air is transported from the air diffuser 7 from the irradiation tank 1 through the air supply pipe 4. Air containing by-products is diffused into the water 48 that has flowed in through the water outlet. Further, in the middle portion of the raw water tank 6, as in the embodiment shown in FIG. 8, a filling layer 49 filled with a filler such as Raschig ring is formed.

Further, a circulation pipe 52 provided with a circulation pump 51 as a circulation means is connected to the bottom of the raw water tank 6, and water 48 in the raw water tank 6 is adjusted while the flow rate is adjusted by a valve 57 provided midway.
A closed circulation circuit is constructed in which water is again circulated by water sprinkling means 55 provided on the upper part of the raw water tank 6. The circulation pipe 52 is connected to the carrier pipe 10 provided with a valve 57, and a part of the water 48 that is not circulated in the circulation pipe 52 is appropriately fed to the aeration tank 12.

Further, on the upper part of the raw water tank 6, an air diffuser 7 is provided.
Intake means (not shown) for inhaling the gas diffused from is provided, and the inhaled air is returned from the intake means to the irradiation tank 1 through the intake pipe 59 to irradiate the ultraviolet rays again. The air from the intake pipe 59 is appropriately sent to an adsorption treatment device 58, which is filled with an adsorbent such as activated carbon (not shown), to adsorb and remove volatile organic compounds, by-products, etc., and is purified. The air is exhausted to the atmosphere.

Then, in the aeration tank 12, the water 48 transferred from the raw water tank 6 to the upper portion of the aeration tank 12 by the transfer pump 51 via the transfer pipe 10.
A discharge part 14 for discharging is provided. Also, aeration tank
A packed bed 15 is provided in the middle of the container 12, and the packed bed 15 contains a large number of packing materials such as porous materials (not shown) carrying aerobic organisms that decompose secondary by-products in the inflowing water. Filled and formed.

Further, in the lower part of the aeration tank 12, there is provided an aeration device 17 to which a blower 16 which diffuses air into the wastewater 13 and supplies oxygen to aerobic organisms in the packed bed 15 is connected. In addition,
The aeration tank 12 is provided with a backwashing means (not shown), and the inside of the aeration tank 12 may be appropriately backwashed, and the collected sludge or the like may be separately treated or used as a nutrient source for aerobic organisms described later.

Further, in the upper part of the aeration tank 12, nitrogen, phosphorus, magnesium, iron, which are necessary for reproduction of aerobic organisms in the packed bed 15,
An adding device 61 for adding a nutrient source such as calcium, manganese, or calcium is provided. Instead of the nutrient source of the addition device 61, sewage 13 or sludge containing pollutants such as organic substances and nitrogen compounds may flow into the upper part of the aeration tank 12.

Furthermore, a packed bed is provided at the bottom of the aeration tank 12.
An outflow pipe 62 for connecting the water 48 purified by 15 aerobic organisms is connected. Further, on the downstream side of the outflow pipe 62, as in the embodiment shown in FIGS. 11 and 12, a pH control device 8 having a sensor 8a for detecting a pH value and an alkali control device 8b for adding sodium hydroxide or the like is provided. And a water tank 63 provided with a stirring means (not shown).

At the bottom of the water tank 63, a return pipe 66 as a return means having a water discharge pump 18 and a valve 65 provided in the middle is connected, and the water 48 in the water tank 63 is appropriately sprinkled in the sprinkling means 55 and A closed reflux circuit is formed to return the gas to the discharge section 14 of the aeration tank 12 for reflux.

The return pipe 66 is provided with a water discharge pipe 19 provided with a valve (not shown) so that the treated water 48 in the water tank 63 is appropriately discharged. Alternatively, the water may not be discharged as it is, but may be discharged after purification treatment with an adsorbent or the like.

Next, the processing operation of the apparatus of the embodiment shown in FIGS. 13 and 14 will be described.

Benzene (C ₆ H ₆ ) and toluene (C ₇ H _6
8 ), wastewater 13 such as industrial wastewater containing volatile organic compounds such as trichlorethylene (CHCl = CCl ₂ ) and tetrachlorethylene (CCl ₂ = CCl ₂ ).
Similarly to the embodiment shown in FIGS. 7 to 7 and the embodiments shown in FIGS. 9 and 10, the extractor 2 is aerated to volatilize the volatile organic compounds into the air. Then, the air containing the volatile organic compound is appropriately irradiated with ultraviolet rays in the irradiation tank 1 to decompose the air into the first by-product, and the air containing the first by-product is fed through the air supply pipe 4 to the raw material. Air is fed to the water tank 6.

Next, the air 48 supplied through the air supply pipe 4 is diffused from the air diffuser 7 into the water 48 which has previously flown into the raw water tank 6 through the water flow port.

At the time of this air diffusion, the circulating pump 51 is driven, and the water sprinkling means 55 provided on the upper portion sprinkles the alkaline water 48 aerated with the air from the irradiation tank 1 on the packed bed 49,
The first contact with the air in the raw water tank 6 again,
By-products are dissolved or hydrolyzed in alkaline water 48 by contact with alkaline water to be trapped to form easily decomposable secondary by-products. And the transport pump
The valve 57 is appropriately adjusted by 51 to supply water to the aeration tank 12 via the transfer pipe 10. Further, the air in the raw water tank 6 is appropriately irradiated with air from an intake means (not shown) through an intake pipe 59.
And is circulated, and part of the gas is sent to the adsorption processing device 58 to be adsorbed and exhausted.

Then, the water 48 from the raw water tank 6 is fed to the aeration tank 12
Discharge from the discharge unit 14 provided on the upper part, while appropriately aerating the nutrient source and aerating the air from the aeration device 17, let the packing layer 15 flow through, and by the aerobic organisms carried on the packing material of the packing layer 15. Purify secondary by-products. When aerobic organisms grow, sludge and the like are removed by a backwashing means (not shown).

Further, the purified water 48 is allowed to flow out into the water tank 63 through the outflow pipe 62, and while stirring with the stirring means, while monitoring the pH with the sensor 8a, appropriately feed sodium hydroxide or the like from the alkali controller 8b. And the pH value is slightly alkaline,
For example, the pH is controlled to 8 and preferably to 10 or more. The alkaline water 48 is appropriately pumped by the pump 18 via the return pipe 66 and the sprinkling means 55 of the raw water tank 6 and the discharge part 14 of the aeration tank 12.
Return to and bring to reflux.

Then, the pH-adjusted and purified water 48 in the water tank 63 is caused to flow into the adsorption treatment device 58 from the water discharge pipe 19 and is discharged through a water discharge port (not shown).

Therefore, according to the above-mentioned embodiment, poisonous volatile organic compounds are decomposed into primary by-products by only irradiation of ultraviolet rays for a short time, and can be purified by aerobic organisms by contact with water 48. A second by-product which is easily decomposable and is purified by appropriately treating water 48 and air under reflux,
Before exhausting and discharging the treated air and water 48, it is adsorbed with an adsorbent and further purified so that it is surely toxic and adsorbed and removed, and harmful volatile organic compounds leak to the outside of the system. The purification process can be performed without fail.

[0118]

According to the method for treating a volatile organic compound described in claim 1, since the extracted volatile organic compound is irradiated with ultraviolet rays in the presence of oxygen to be oxidized into a primary by-product,
Since the irradiation rate of ultraviolet rays can be improved and the efficiency of oxidative decomposition by ultraviolet rays can be improved, the primary by-product is brought into contact with water to form a readily decomposable secondary by-product, which is contained in water. Water, which is easy to use, serves as a carrier for secondary by-products decomposed from harmful volatile organic compounds, and can be easily and efficiently treated.

According to the method for treating a volatile organic compound described in claim 2, in addition to the method for treating a volatile organic compound described in claim 1, since the pH of the alkaline water is 8 or more,
The primary by-product is decomposed into a readily decomposable secondary by-product very efficiently by contact with alkaline water having a pH of 8 or more.

According to the method for treating a volatile organic compound according to claim 3, in addition to the method for treating a volatile organic compound according to claim 1 or 2, the method of contacting a primary by-product with alkaline water is used. At this time, the circulation means circulates the alkaline water to form a closed circulation circuit and concentrates the generated secondary by-product, so that the processing efficiency of the secondary by-product can be improved.
The processing cost of the secondary by-product can be reduced.

According to the method for treating a volatile organic compound described in claim 4, in addition to the method for treating a volatile organic compound according to any one of claims 1 to 3, a primary by-product and alkaline water are added. Since the easily decomposable secondary by-product produced by the contact is decomposed by the aerobic organism, the volatile organic compound can be surely processed into a harmless final product.

According to the method for treating a volatile organic compound described in claim 5, in addition to the method for treating a volatile organic compound according to claim 4, water obtained by decomposing the secondary by-product with an aerobic organism is added. Since a closed reflux circuit for returning by the returning means and contacting with the primary by-product again is formed, the by-product can be reliably processed without leaking out of the system, and the secondary by-product is processed. The efficiency can be improved and the processing cost of the secondary by-product can be reduced.

According to the method for treating a volatile organic compound of claim 6, in addition to the method for treating a volatile organic compound according to any one of claims 1 to 5, 50% or more of ultraviolet rays having a wavelength of 200 nm or less are transmitted. Since a gas containing a volatile organic compound is irradiated with ultraviolet rays by an ultraviolet lamp having a glass tube, the volatile organic compound can be oxidized and decomposed in a short time.

[Brief description of the drawings]

FIG. 1 is a system explanatory view showing the configuration of an embodiment of an apparatus for carrying out the method for treating a volatile organic compound of the present invention.

FIG. 2 is a perspective view showing an experimental apparatus for explaining the oxidative decomposition of the volatile organic compound of the present invention into primary by-products by UV irradiation.

FIG. 3 is a graph showing the state of decomposition of trichlorethylene, a volatile organic compound, using an ultraviolet lamp having a glass tube that transmits 50% or more of ultraviolet rays of 200 nm or less.

FIG. 4 is a graph showing the decomposition state of trichlorethylene, a volatile organic compound, using an ultraviolet lamp having a glass tube that transmits 50% or less of ultraviolet rays of 200 nm or less.

FIG. 5 is a graph showing the transmittance of a volatile organic compound.

FIG. 6 is an explanatory view showing an apparatus for experimenting the relationship between the pH of water which is brought into contact with a volatile organic compound and the solubility of the volatile organic compound.

FIG. 7 is a graph showing the state of dissolution of carbonyl chloride.

FIG. 8 is a system explanatory view showing a configuration of an apparatus for purifying dichloroacetic acid, which is a secondary by-product of the above, by an aerobic organism.

FIG. 9 is a graph showing the purification treatment status of dichloroacetic acid.

FIG. 10 is an explanatory diagram showing a configuration of an apparatus according to another embodiment.

FIG. 11 is a system explanatory view showing a configuration of an apparatus of still another embodiment.

FIG. 12 is an explanatory view showing the same raw water tank as above.

FIG. 13 is a system explanatory view showing a configuration of an apparatus showing still another embodiment.

FIG. 14 is an explanatory diagram showing a raw water tank and an aeration tank of the same as above.

[Explanation of symbols]

 1 Irradiation tank 6 Raw water tank 12 Aeration tank 52 Circulation pipe as circulation means 66 Return pipe as return means

Claims (6)

[Claims] 1. A volatile organic compound contained in at least one of soil and water is extracted by vacuum or aeration, and the gas containing the extracted volatile organic compound is exposed to ultraviolet rays in the presence of oxygen. Irradiating to oxidize the volatile organic compound, and contacting a gas containing the primary by-product generated by this oxidation with alkaline water to generate a readily decomposable secondary by-product. A method for treating a volatile organic compound, comprising: 2. The method for treating a volatile organic compound according to claim 1, wherein the alkaline water has a pH of 8 or more. 3. A closed circulation circuit for concentrating a secondary by-product produced by circulating the alkaline water by a circulation means when the primary by-product and alkaline water are brought into contact with each other. The method for treating a volatile organic compound according to claim 1 or 2, characterized in that: 4. The aerobic organism decomposes the secondary by-product produced by contacting the primary by-product with alkaline water, according to any one of claims 1 to 3. Treatment method of volatile organic compounds. 5. The closed reflux circuit is formed by returning the water obtained by decomposing the secondary by-product with aerobic organisms by the returning means and bringing it into contact with the primary by-product. 4. The method for treating a volatile organic compound according to 4. 6. The method for treating a volatile organic compound according to claim 1, wherein an ultraviolet lamp having a glass tube which transmits 50% or more of an ultraviolet ray having a wavelength of 200 nm or less is used.