JP2006205098A - Apparatus for oxidative decomposition of hardly decomposable organic compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for oxidative decomposition of a hardly decomposable organic compound, which is firstly excellent in terms of treating facilities, capability, time consumption, and cost, and is secondly capable of quickly, surely, and oxidatively decomposing a hardly decomposable organic compound. <P>SOLUTION: The apparatus 13 for oxidative decomposition includes a supply tank 14 and a purifying apparatus 15. Waste water 2 containing the hardly decomposable organic compound 1 is supplied to and stored in the supply tank 14 wherein the waste water 2 is stratified according to the difference of specific gravity due to that of the concentration of the contained organic compound 1. The waste water 2 belonging to a stratum which contains a concentration of the organic compound 1 so high that the waste water cannot be discharged directly is supplied from the supply tank 14 to the purifying apparatus 15 provided with a photocatalyst 21 and an ultraviolet radiation means 22. Since ozone or hydrogen peroxide is dissolved to the waste water 2 in advance, the organic compound 1 in the waste water 2 is oxidatively decomposed by an OH radical generated by irradiation with the ultraviolet rays. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an oxidative decomposition apparatus for a hardly decomposable organic compound. That is, the present invention relates to an oxidative decomposition apparatus for a hardly decomposable organic compound contained in waste water.

<< Regarding Prior Art 1 >>
FIG. 4 is an explanatory diagram of the entire system of this type of conventional example. As shown in the figure, the wastewater 2 containing the hardly decomposable organic compound 1 discharged from the chemical treatment process equipment and used as a solvent, for example, was usually biologically treated as it is.
For example, a large amount of wastewater 2 containing an organic compound 1 that is hardly decomposable such as monochlorobenzene CB, methyl isobutyl ketone MIBK, benzyl alcohol BA, isopropyl alcohol IPA, dimethylformamide DMF, etc. It was transported to a general storage, where it was purified and discarded by biological treatment.
In the example of FIG. 4, the exhaust gas 4 discharged from the chemical treatment process equipment and containing the hardly decomposable organic compound 1 is supplied to the adsorption tank 7 via the filter 5 and the blower 6. In the adsorption tank 7, after such exhaust gas 4 is adsorbed, it is converted into drainage 2 by the supplied steam 8 and condenser 9, and the drainage 2 is temporarily stored in the large tank 11 via the separation tank 10. .
The waste water 2 containing the hardly decomposable organic compound 1 is loaded into the tank truck 3 from the tank 11 via the pump 12, and is transported to a wide general storage area that is generally provided at a remote location. Therefore, for example, biological treatment was performed by the activated sludge method.

<< Regarding Prior Art 2 >>
It should be noted that the waste water 2 containing the hardly decomposable organic compound 1 is not used in the general example of FIG. 4 at the site of chemical treatment process equipment, that is, at the discharge site without being transported to a general storage. Attempts have also been made to disassemble and dispose.
Typically, ozone O ₃ is used to oxidize and decompose the hard-to-decompose organic compound 1 contained in the waste water ₂ to decompose and purify it into carbon dioxide CO ₂ or water H ₂ O, etc. Attempts to make a general wastewater drain were also researched and tested.

By the way, the following problems have been pointed out with respect to such conventional techniques.
<About the first problem>
First, with respect to the prior art 1, problems have been pointed out in the processing equipment, processing capacity, processing time, processing cost, and the like.
That is, with respect to the prior art 1 of FIG. 4 which is transported to a general storage and biologically processed, first, a separation tank 10, a large tank 11 for temporary storage, a tank lorry for transportation 3, a general storage for biological processing, It has been pointed out that a large processing facility is required. Furthermore, these treatment facilities have inherently limited purification treatment capacities, and it has been pointed out that the whole treatment takes a long time, takes time, and increases the treatment cost.

About the second problem
Secondly, with regard to the prior art 2, the problem is that oxidation and decomposition of the hardly decomposable organic compound 1 are very slow, the decomposition reaction does not proceed, and it is easy to stop incomplete and uncertain. It had been.
That is, the decomposition of chain hydrocarbons such as olefinic compounds and paraffinic compounds such as methyl isobutyl ketone MIBK, isopropyl alcohol IPA, and dimethylformamide DMF by ozone O ₃ has stopped until the ozonide ozonide stage. In other words, the ozonide was formed to break the bond and proceed to the aldehyde stage, but the subsequent decomposition reaction was extremely time consuming and difficult to proceed.
In addition, decomposition of cyclic hydrocarbons having aromatic rings such as monochlorobenzene CB and benzyl alcohol BA and other cyclic hydrocarbons by ozone O ₃ has been stopped by the glyoxal (CHO-CHO) stage. In other words, even if it progressed, it was at most to the level of aldehydes containing glyoxal, and the subsequent decomposition reaction was extremely time consuming and difficult to proceed.
As described above, the attempt to purify the wastewater by purifying it at the discharge site is difficult to realize the oxidation and decomposition of the hardly decomposable organic compound 1 within an industrially acceptable time, and has not been put into practical use.

<< About the present invention >>
The oxidative decomposition apparatus for a hardly decomposable organic compound of the present invention has been made as a result of diligent research efforts by the inventor in order to solve the above-described problems of the prior art.
The waste water is first stratified based on the concentration change of the hardly decomposable organic compound in the supply tank, and then the hardly decomposable organic compound is oxidized and decomposed by the purification device corresponding to each layer. To do. This purification device includes a photocatalyst and ultraviolet irradiation means, and ozone or hydrogen peroxide is appropriately introduced in advance.
Thus, the present invention is firstly excellent in processing equipment, capacity, time, cost, etc., and secondly, a hardly decomposable organic compound that can quickly and reliably oxidize and decompose a hardly decomposable organic compound. The object is to propose an oxidative decomposition apparatus for compounds.

<About each claim>
The technical means of the present invention for solving such a problem is as follows. First, claim 1 is as follows.
The oxidative decomposition apparatus according to claim 1 is an oxidative decomposition apparatus for a hardly decomposable organic compound contained in the waste water, and has a supply tank and a purification apparatus.
Then, the wastewater is supplied and stored in the supply tank, and the wastewater is stratified vertically by specific gravity based on the change in the vertical concentration of the contained organic compound. The purification apparatus is supplied with the waste water of the layer containing the organic compound at a concentration that cannot be discarded from the supply tank, and is provided with a photocatalyst and an ultraviolet irradiation means, and oxidizes the organic compound, It is characterized by decomposing.
Claim 2 is as follows. The oxidative decomposition apparatus according to claim 2 is the oxidative decomposition apparatus according to claim 1, wherein the waste water supplied to the supply tank is formed by mixing exhaust gas containing the organic compound with water. The organic compound is characterized by being composed of paraffinic compounds, olefinic compounds, other chain hydrocarbons, cyclic hydrocarbons having an aromatic ring, and other cyclic hydrocarbons.

Claim 3 is as follows. The oxidative decomposition apparatus according to a third aspect of the present invention is the oxidative decomposition apparatus according to the second aspect, wherein the purification apparatus is individually provided corresponding to the layer of the wastewater stratified based on the concentration of the organic compound in the supply tank. .
The purification device for drainage of the organic compound layer and drainage of the emulsion layer is such that ozone and hydrogen peroxide are previously dissolved in the wastewater, and the ultraviolet irradiation means has a medium wavelength ultraviolet ray of 240 nm to 280 nm. Irradiate. Thus, the purification device is characterized in that the organic compound is oxidized and decomposed by the photocatalyst and OH radicals generated by the ozone and hydrogen peroxide.
Claim 4 is as follows. According to a fourth aspect of the present invention, in the oxidative decomposition apparatus according to the third aspect, the waste water is supplied to the purification device via a filter attached in front of the purification device. Further, the ozone and hydrogen peroxide are dissolved in the waste water by using a press-fitting means, a spraying means, a venturi means, and other introducing means attached in front of the purification device.
Claim 5 is as follows. The oxidative decomposition apparatus according to claim 5 is the purifying apparatus for draining an aqueous solution layer according to claim 3, wherein the ultraviolet irradiation means irradiates medium wavelength ultraviolet rays of 240 nm to 280 nm, and the ultraviolet irradiation means is 310 nm. Those irradiating with ultraviolet rays of up to 390 nm are used in combination. Thus, the purification device is characterized in that the organic compound is oxidized and decomposed by OH radicals generated by the photocatalyst.

Claim 6 is as follows. The oxidative decomposition apparatus according to claim 6 is the oxidative decomposition apparatus according to claim 5, wherein the waste water discharged from each of the purification apparatuses is returned to the supply tank with a high concentration of the organic compound, and the remaining low concentration is the first. 2 Supplied to the purification device.
The second purification device includes a photocatalyst and ultraviolet irradiation means. The ultraviolet irradiating means irradiates medium wavelength ultraviolet light of 240 nm to 280 nm, or the ultraviolet irradiating means irradiates long wavelength ultraviolet light of 310 nm to 390 nm. And hydrogen peroxide are dissolved in the waste water. The organic compound is oxidized and decomposed by the generated OH radicals.
Accordingly, the second purification device is characterized in that the waste water is circulated and supplied until the concentration of the organic compound reaches a level at which it can be discarded.

<About action>
Since the oxidative decomposition apparatus of the present invention is configured as described above, it is as follows.
(1) Wastewater mixed with exhaust gas containing a hardly decomposable organic compound is supplied to the oxidative decomposition apparatus. Typical examples of the hardly decomposable organic compounds include chain hydrocarbons such as paraffinic compounds and olefinic compounds, and cyclic hydrocarbons having an aromatic ring.
(2) The waste water is first stored in the supply tank of the oxidative decomposition apparatus, and based on the change in the upper and lower concentrations of the organic compound, for example, a. A purified water layer, b. Aqueous layer, c. An emulsion layer, d. The organic compound layer is divided into upper and lower layers.
(3) Then, for example, b. Aqueous layer, c. An emulsion layer, d. An organic compound layer or the like containing an organic compound that cannot be discarded is supplied from the supply tank to the purification device through a filter.
(4) The purification device includes a photocatalyst and ultraviolet irradiation means, and is provided individually corresponding to the stratified waste water. For example, c. For emulsion layer or d. The purification device for the organic compound layer is preliminarily dissolved with ozone and hydrogen peroxide and irradiated with medium wavelength ultraviolet rays. b. As the purification device for the aqueous solution layer, a device for irradiating medium wavelength ultraviolet light and a device for irradiating long wavelength ultraviolet light are used in combination.
(5) In each purification device, ultraviolet rays are irradiated to the photocatalyst, and also ozone and hydrogen peroxide, and the strong oxidizing power and decomposition power of the generated OH radicals cause the photocatalyst and ozone or hydrogen peroxide, in particular. In the case of the combined use, a more powerful oxidizing power and decomposing power by synergistic action, a hard-to-decompose organic compound is cleaved by its carbon chain and organic bond, and is quickly and reliably oxidized, and carbon dioxide gas, water, etc. The waste water is purified.
(6) In order to make such oxidation and decomposition more reliable, the wastewater discharged from each purification device is returned to the supply tank with a high concentration of organic compound, and the remaining low concentration is the second. Supplied to the purification device. The second purification device has a configuration and action similar to those of the purification device described above, and oxidizes and decomposes organic compounds. The wastewater is circulated and supplied, and purified to be discharged as general wastewater.

(7) Now, first, this oxidative decomposition apparatus is directly connected to a chemical treatment process facility in which exhaust gas and waste water containing a hardly decomposable organic compound are discharged. Purify a large amount of wastewater. And since the processing equipment and processing contents are relatively simple and easy and can be sequentially purified, the entire processing time is short and there is no processing limit.
Secondly, in this oxidative decomposition apparatus, the waste water is stratified based on the concentration of the hardly decomposable organic compound, and the purification apparatus is provided individually correspondingly.
For example, c. An emulsion layer or d. In high-concentration purifiers for organic compound layers, etc., ozone and hydrogen peroxide are dissolved and irradiated with medium-wavelength ultraviolet rays, so the energy is strong, and the synergistic action of the photocatalyst with ozone and hydrogen peroxide is also added. Oxidation and decomposition are performed. In contrast, for example, b. In low-concentration purification devices such as aqueous solution layers, those that irradiate with long-wavelength ultraviolet rays are also used in combination, and oxidation and decomposition are carried out efficiently and efficiently without waste due to relatively weak energy. .
In this way, the organic compound is oxidized and decomposed quickly and reliably.

<Features of the present invention>
In this way, the oxidative decomposition apparatus for a hardly decomposable organic compound according to the present invention, in this way, the wastewater is first stratified based on the concentration change of the hardly decomposable organic compound in the supply tank, and then the purification apparatus corresponding to each layer. It is characterized by oxidizing and decomposing persistent organic compounds. This purification device includes a photocatalyst and ultraviolet irradiation means, and ozone or hydrogen peroxide is appropriately introduced in advance.
Therefore, the present invention exhibits the following effects.

<< First effect >>
First, it is excellent in processing equipment, processing capacity, processing time, processing cost, and the like. That is, the oxidative decomposition apparatus of the present invention is directly connected to the chemical treatment process facility, and purifies wastewater at the discharge site to produce general wastewater.
Therefore, unlike the above-described general prior art, there is no need for processing facilities such as a separation tank, a large tank for temporary storage, a tank lorry for transportation, a general storage for biological treatment, and the like. In addition, there is no limit to the purification capacity (storage capacity, transport capacity, biological capacity) as in the case of using these treatment facilities, and the purification process can be performed sequentially and the overall processing time is greatly increased. Shortened to
Therefore, compared to this type of conventional technology, the configuration is simple, the processing equipment cost is reduced, and since the purification process is sequentially performed at the site, the processing cost is not high, and thus the cost is excellent.

<< Second effect >>
Second, wastewater can be purified by oxidizing and decomposing a hardly decomposable organic compound quickly and reliably.
That is, the oxidative decomposition apparatus of the present invention can use the purification apparatus effectively and efficiently by first stratifying the wastewater in the supply tank. In the purification device, the OH radicals generated by irradiating ultraviolet rays to ozone and hydrogen peroxide are used to reliably oxidize persistent organic compounds in an extremely short time as compared with the above-described conventional example. , It is decomposed, and the wastewater is treated for purification and general wastewater.
As described above, the effects exerted by the present invention are remarkably large, such as all the problems existing in this type of conventional example are solved.

《About drawing》
Hereinafter, the oxidative decomposition apparatus of a hardly decomposable organic compound of the present invention will be described in detail based on the best mode for carrying out the invention shown in the drawings.
FIG. 1 is a diagram illustrating the configuration of the entire system. FIG. 2 is a diagram illustrating the configuration of the former part of the example, and FIG. 3 is a diagram illustrating the configuration of the latter part of the example.

<< About drainage 2 etc. >>
The oxidative decomposition apparatus 13 of the present invention includes a supply tank 14 and a purification apparatus 15, and oxidizes and decomposes the hardly decomposable organic compound 1 contained in the waste water 2.
First, with reference to FIG. 1, the drainage 2 and the like to be treated will be described. The waste water 2 discharged from the chemical treatment process of industrial facilities often contains a hardly decomposable organic compound 1.
In the illustrated example, in the exhaust gas 4 discharged from the bonding process, the painting process, and other chemical processing process facilities, for example, the hardly decomposable organic compound 1 used as a solvent is contained. The discharged exhaust gas 4 is supplied to an adsorption tank 7 via a cooler-equipped filter 5 through which cooling water is circulated and a blower 6. In the adsorption tank 7, after the supplied exhaust gas 4 is adsorbed, steam 8 is sprayed and desorbed to form the drainage 2. Further, if necessary, the waste water 2 is surely converted by passing through the condenser 9 through which the cooling water circulates.
Then, the waste water 2 containing the hardly decomposable organic compound 1 is supplied to the supply tank 14 of the oxidative decomposition apparatus 13.

Thus, the waste water 2 supplied to the oxidative decomposition apparatus 13 consists of the exhaust gas 4 containing the hardly decomposable organic compound 1 mixed in water. The organic compound 1 is a paraffinic compound, an olefinic compound having a C═C bond, other chain hydrocarbons, a cyclic hydrocarbon having an aromatic ring, that is, a phenyl group C ₆ H ₅ —, and other cyclic hydrocarbons. It becomes more.
For example, the waste water 2 contains about 1% to about 0.03% of a hardly decomposable organic compound 1 such as monochlorobenzene CB, methyl isobutyl ketone MIBK, benzyl alcohol BA, isopropyl alcohol IPA, and dimethylformamide DMF, respectively. Become.
In the illustrated example, the amount of exhaust gas 4 is, for example, 360 Nm ³ / min at 0 ° C. and 1 atmosphere, the contained organic compound 1 is, for example, 757 ppm, and the amount of waste water 2 is, for example, 660 L / h.
Incidentally, as the hardly decomposable organic compound 1, environmental hormones such as dioxin and bisphenol A are also representative.
The drainage 2 etc. are like this.

<< About supply tank 14 etc. >>
Next, the supply tank 14 and the like of the oxidative decomposition apparatus 13 of the present invention will be described with reference to FIGS.
The drainage 2 is supplied to the supply tank 14 via the neutralization tank 16 and the pump 12. The neutralization tank 16 decomposes the contained harmful substances into water H ₂ O or the like with, for example, sodium hydroxide NaOH.
The supply tank 14 is supplied and stored with the drainage 2, so that the drainage 2 is stratified vertically by specific gravity based on the change in the upper and lower concentration of the persistent organic compound 1 contained therein. That is, the supplied wastewater 2 is stored in the supply tank 14 for a certain period of time, for example, about 24 hours, so that the concentration of the organic compound 1 is lower in the upper part and the content concentration is higher in the lower part and changes with time. Depending on the specific gravity, it is divided into upper and lower areas, stratified, and separated.

For example, a. A purified water layer 17 in a state where the concentration of the organic compound 1 is extremely reduced (for example, 40 ppm, that is, about 40 mg / L or less) and reaches a disposable level; b. An aqueous solution layer 18 in which the organic compound 1 is uniformly dissolved in water; c. An emulsion layer 19 in which the organic compound 1 is dispersed and mixed in water and mixed, and d. The organic compound layer 20 is layered into an organic compound layer 20 having a very high concentration of the organic compound 1.
Of course, the boundary area between these layers is in an intermediate state. Depending on the storage time and other conditions, the upper and lower layers (2 phases) and 3 layers (3 phases) are divided into layers, and the upper and lower layers (5 phases) and more are divided, regardless of the illustrated example. In any case, in any case, the waste water 2 in the supply tank 14 is thus divided into two or more layers.
In addition, a discharge drain is attached on the boundary area between the layers (that is, the lower part of each layer). The waste water 2 from the water purification layer 17 of a may be discarded as general waste water as it is, but may be supplied immediately before the TOD measuring instrument of the second purification device described later.
The supply tank 14 and the like are as described above.

<About the purification device 15>
Next, the purification apparatus 15 of the oxidative decomposition apparatus 13 of the present invention will be described with reference to FIGS.
The purification device 15 is provided individually corresponding to each layer of the waste water 2 stratified based on the concentration of the organic compound 1 in the supply tank 14.
Each purifier 15 is supplied with a layer of wastewater 2 containing the organic compound 1 at a concentration that cannot be discarded from the supply tank 14, and includes a photocatalyst 21 and an ultraviolet irradiation means 22. The organic compound 1 is oxidized and decomposed.

Such a purification device 15 will be further described in detail. The drainage 2 from the supply tank 14 is supplied to the respective purifiers 15 via the pipes 12 and the filters 24 that are interposed and attached to the previous stage of the purifier 15 sequentially in the pipes 23 for each layer. The filter 24 removes in advance the produced substances, fine dust, and the like contained in the waste water 2 so as not to hinder the oxidizing and decomposing actions of the purification device 15.
Further, ozone O ₃ and hydrogen peroxide H ₂ O ₂ are dissolved in the waste water 2 in advance by using a press-fitting means, a spraying means, a venturi means, and other introducing means attached to the previous stage of the purification device 15. There are many things.
That is, both or one of the ozone supply unit 25 and the hydrogen peroxide supply unit 26 may be interposed in the middle of the pipe 23 to the purification device 15, and each may be press-fitted with a mixing pump or sprayed with a nozzle. By accelerating with a venturi, ozone O ₃ and hydrogen peroxide H ₂ O ₂ are uniformly dissolved and introduced into the waste water 2. The ozone supply unit 25 is typically an ozonizer that converts oxygen O ₂ into ozone O ₃ by electric discharge, or an ozone lamp that emits an ultraviolet short wavelength having a peak value near 185 nm.

In the example of FIG. 2, the purifiers 15 to which the waste water 2 from the organic compound layer 20 of d and the waste water 2 from the emulsion layer 19 of C are respectively supplied are ozone O ₃ and peroxidation in advance. Hydrogen H ₂ O ₂ is dissolved in the waste water 2 and the ultraviolet irradiation means 22 irradiates medium wavelength ultraviolet light of 240 nm to 280 nm (for example, 254 nm). For example, in the purification device 15 arranged in two front and rear, both medium wavelength ultraviolet rays are irradiated.
Therefore, these purification apparatuses 15 oxidize and decompose the hardly decomposable organic compound 1 by the photocatalyst 21, the ozone O ₃ and the hydrogen peroxide H ₂ O ₂ and the OH radicals generated by the medium wavelength ultraviolet rays.
On the other hand, the purifier 18 to which the waste water 2 from the aqueous solution layer 18 of b is supplied has an ultraviolet irradiation unit 22 that irradiates medium wavelength ultraviolet rays of 240 nm to 280 nm (for example, 254 nm), and an ultraviolet irradiation unit 22. However, those that irradiate ultraviolet rays having a long wavelength of 310 nm to 390 nm (for example, 360 nm) are used in combination. For example, in the purification device 15 arranged in two series, the front stage is for irradiation with medium wavelength ultraviolet light, and the rear stage is for irradiation with long wavelength ultraviolet light.
Accordingly, these purification devices 15 oxidize and decompose the hardly decomposable organic compound 1 by the OH radicals generated by the photocatalyst 21.

First, in the example of FIG. 2, the purifying device 15 is separately provided for the drainage 2 from the organic compound layer 20 and the drainage 2 from the emulsion layer 19. A common purification device 15 may be used. Furthermore, it is also possible to use this purification device 15 for the drainage 2 from the aqueous solution layer 18 of b.
Secondly, in the example of FIG. 1, medium wavelength ultraviolet rays are irradiated in the former stage of the two purification apparatuses 15 and long wavelength ultraviolet rays are irradiated in the latter stage, but both may be irradiated with the medium wavelength ultraviolet rays. Good.
Thirdly, although each purification device 15 has a duplex system in the illustrated example, except for the one corresponding to the aqueous solution layer 18, it may be a single system (one), or a triple system or more. .
Fourthly, the photocatalyst 21 usually applies titania, that is, titanium oxide TiO ₂ particles on the inner peripheral wall surface of the cylindrical tank of the purifier 15 to which the drainage 2 is supplied together with, for example, metal fines and an adsorbent. It forms by adhesion.
Fifth, the ultraviolet irradiation means 22 irradiates medium wavelength ultraviolet light of 240 nm to 280 nm or long wavelength ultraviolet light of 310 nm to 390 nm. If the numerical value is exceeded, generation of OH radicals becomes difficult due to insufficient energy. On the contrary, if the value is lower than that value, the energy is too strong to be absorbed and attenuated by other substances, and as a result, the generation of OH radicals becomes difficult.
Sixth, the ultraviolet irradiation means 22 is suspended in the shape of a thin column coaxially with the center of the cylindrical tank of the purification device 15. A special lamp such as a mercury lamp is used for irradiation of strong energy medium wavelength ultraviolet rays. A dedicated lamp can be used for irradiation of long-wavelength ultraviolet rays that require less energy, but a black light that is superior in cost, including the cost of use, is mainly used, and LEDs can be used.
The purification device 15 is as described above.

<About generation of OH radicals>
Next, generation of OH radicals in the purification device 15 will be described in detail. First, the generation of OH radicals by the photocatalyst 21 is as follows.
That is, when the photocatalyst 21 is irradiated with, for example, light energy (photon) hν of ultraviolet light having a medium wavelength or a long wavelength, an electron e ⁻ in the valence band in the outer electron region of the titanium oxide TiO ₂ surface is excited and jumped out. It moves to the conductor and becomes an electric current. → As a result, a hole hole ^{+ in} which the electron e ⁻ escapes and is lost is generated in the valence band. → See the following formula 1.

Hole hole ⁺ has a property of pulling out electrons e ⁻ from other substances that come into contact, for example, water H ₂ O that comes in contact with the electron vacancies, that is, has a strong oxidizing power.
On the other hand, water H ₂ O is ionized by irradiation with light energy to generate a hydroxide ion OH ^{− according} to the following formula 2.

Therefore, the hole hole ⁺ having a stronger oxidizing power extracts electrons e ⁻ from the hydroxide ions OH ⁻ of water H ₂ O. → Hydroxyl ion OH ⁻ deprived of electron e ⁻ generates a hydroxy radical (.OH), that is, an OH radical, according to the following formula 3.

Next, the generation of OH radicals by ozone O ₃ or the like is as follows (note that the generation of OH radicals by hydrogen peroxide H ₂ O ₂ is similar to this).
That is, for example, when ozone O ₃ is irradiated with light energy (photon) hν of medium-wavelength ultraviolet light, → excited singlet oxygen atom O ( ¹ D), that is, an oxygen atom extremely rich in reactivity, is generated. → See the following formula 4.

The singlet oxygen atom O ( ¹ D) reacts with water H ₂ O in contact therewith, and generates a hydroxy radical (.OH), that is, an OH radical, according to the following formula 5.

<Oxidation and decomposition by OH radicals>
And thus, an optical catalyst 21, or ozone O _3, OH radicals generated by hydrogen peroxide H ₂ O ₂ as reactive oxygen species, very strong oxidizing power unmatched, active force, It has a decomposing power, and tries to stabilize it by strongly taking electrons from the nearby organic compound 1.
That is, the hardly decomposable organic compound 1 in the waste water 2 in contact with the OH radical is deprived of electrons by such OH radical, and then → its carbon chain (for example, single bond, double bond, triple bond, aromatic ring) Bonds, etc.), organic bonds, and molecular bonds themselves are broken, decomposed, and broken, and then quickly and strongly oxidized.
For example, in the case of ozone O ₃ , chain hydrocarbons of olefinic compounds that are relatively easy to oxidize and decompose have been limited to aldehydes via the ozonide stage, but are also difficult to oxidize and decompose. For the cyclic hydrocarbons with aromatic rings, etc., which were in the Oxine O _{3 state} , they were stopped at the glyoxal stage, but → OH radicals led to further smooth, rapid and powerful oxidation and decomposition. To do.
That is, by an OH radical having an extremely high oxidative activity for depriving electrons, for example, an aromatic ring is immediately opened, chained, aldehyded and carboxylated, and finally carbon dioxide CO ₂ and water It is immediately decomposed into H ₂ O and other low molecular weight compounds.
The OH radical has such excellent oxidizing power and decomposing power.

<< About the 2nd purification device 27 grade >>
Next, with reference to FIG. 3 etc., the 2nd purification | cleaning apparatus 27 grade | etc., Of the oxidative decomposition apparatus 13 of this invention is demonstrated.
As for the waste water 2 sequentially discharged from each purification device 15 of FIG. 2, the high concentration of the hardly decomposable organic compound 1 is returned to the supply tank 14, and the remaining low concentration is the second purification. Supplied to the device 27.
And the 2nd purification apparatus 27 is provided with the photocatalyst 21 and the ultraviolet irradiation means 22, and the ultraviolet irradiation means 22 irradiates the medium wavelength ultraviolet light of 240 nm-280 nm, or the long wavelength whose ultraviolet irradiation means 22 is 310 nm-390 nm. Those which irradiate ultraviolet rays are used. Further, if necessary, ozone O ₃ and hydrogen peroxide H ₂ O ₂ are dissolved in the waste water 2 in advance, so that the organic compound 1 is generated by OH radicals generated thereby. Is oxidized and decomposed.
And in the 2nd purification apparatus 27, the waste_water | drain 2 is circulated and supplied until the density | concentration of the organic compound 1 reaches the grade which can be discarded.

Such a 2nd purification apparatus 27 is explained in full detail. The waste water 2 discharged sequentially from each purification device 15 and the organic compound 1 is considerably oxidized and decomposed is supplied to the discrimination means 28 through the pipes 23 (see FIG. 1).
The discriminating means 28 measures and discriminates the residual concentration of the hardly decomposable organic compound 1 from the supplied waste water 2 (in the example of FIG. 1, the TOD measuring instrument 30 is used for the measurement).
Then, the waste water 2 with a high residual concentration is returned to the supply tank 14, and the waste water 2 with a low residual concentration is supplied to a tank 29 attached to the previous stage of the second purification device 27 in the example of FIG. 3. . (In addition, in the example of FIG. 1, the waste water 2 with a residual concentration as low as 40 ppm or less is discarded as general waste water.)
The tank 29 temporarily stores the supplied drainage 2. And it supplies to the 2nd purification apparatus 27 with the piping 23 from the discharge drain attached to the lower part. (In addition, when the layer according to the said water purification layer 17 is formed in the upper part in the tank 29, you may supply immediately before the TOD measuring instrument 30, or you may discard as general waste water irrespective of the example of illustration. .)

Various configurations of the second purification device 27 are conceivable. In the illustrated example, an ozone supply unit 25, a pump 12, a filter 24, a hydrogen peroxide supply unit 26, and the like are interposed in series and attached to the pipe 23 in the previous stage.
In the illustrated example, the second purification device 27 includes a photocatalyst 21 and an ultraviolet irradiation unit 22 that irradiates medium wavelength ultraviolet rays, and a photocatalyst 21 and an ultraviolet irradiation unit 22 that irradiates long wavelength ultraviolet rays. The two are provided in series (these configurations and functions are the same as those described above in the purification device 15).
However, various other configurations of the second purification device 27 and the like are conceivable. In other words, various types are possible depending on the degree of residual concentration of the organic compound 1 in the wastewater 2 to be supplied.
For example, an example in which the hydrogen peroxide supply unit 26 is not provided, an example in which the ozone supply unit 25 is not provided, an example in which the ultraviolet irradiation unit 22 of the second purification device 27 irradiates only one of medium wavelength ultraviolet rays and long wavelength ultraviolet rays, An example in which the ultraviolet irradiating means 22 irradiates two or more second purifying devices 27 that irradiate medium wavelength ultraviolet light, an example in which the ultraviolet irradiating means 22 irradiates two or more second purifying devices 27 that irradiates long wavelength ultraviolet rays, and so on. Conceivable.

Then, the waste water 2 discharged from the second purification device 27 is stored in the residual concentration of the organic compound 1 in a measuring unit such as a total oxygen consumption measuring instrument 30 attached to the pipe 23, that is, a TOD (Total Oxygen Demand) measuring instrument 30. Is measured.
Based on, for example, the electrical resistance value of the measurement result of the TOD measuring instrument 30, the discrimination means 31 returns the waste water 2 that still has a high residual concentration to the tank 29, and the waste water 2 that has a low residual concentration is discarded as general waste water. . As a discrimination reference value of the discriminating means 31, a content concentration of the organic compound 1 is typically 40 ppm.
The drainage water 2 returned to the tank 29 is circulated through the second purification device 27 and the like until this discrimination criterion is cleared.
The second purification device 27 and the like are as described above.

《Action etc.》
The oxidative decomposition apparatus 13 of the present invention is configured as described above. Therefore, it becomes as follows.
(1) Wastewater 2 discharged from a chemical treatment process facility and containing refractory organic compound 1, for example, wastewater 2 in which exhaust gas 4 containing refractory organic compound 1 is mixed with water, It is supplied to the oxidative decomposition apparatus 13. The oxidative decomposition apparatus 13 includes a supply tank 14 and a purification apparatus 15 (see FIG. 1).
Typical examples of the organic compound 1 include paraffinic compounds, olefinic compounds, other chain hydrocarbons, cyclic hydrocarbons having an aromatic ring, and other cyclic hydrocarbons.

(2) The drainage 2 is first supplied to the supply tank 14 of the oxidative decomposition apparatus 13 and stored. And the stored waste water 2 is divided into upper and lower layers by specific gravity based on the upper and lower concentration change of the contained hardly decomposable organic compound 1 (see FIGS. 1 and 2).
That is, the drainage 2 in the supply tank 14 is, for example, a. A water purification layer 17 in which the concentration of the organic compound 1 decreases (for example, 40 ppm or less) and can be discarded; b. An aqueous solution layer 18 in which the organic compound 1 is dissolved; c. An emulsion layer 19 in which the organic compound 1 is turbid, d. The organic compound layer 20 having a high concentration of the organic compound 1 is divided into layers.

(3) Then, the waste water 2 is supplied from the supply tank 14 of the oxidative decomposition apparatus 13 to the purification apparatus 15 in a layer containing the hardly decomposable organic compound 1 at a concentration that cannot be discarded yet ( (See FIGS. 1 and 2).
For example, the a. The waste water 2 from the water purification layer 17 is first discarded as general waste water. → Then, the waste water 2 of the above-mentioned b, c, d aqueous solution layer 18, emulsion layer 19, and organic compound layer 20 in the supply tank 14 is sequentially discharged from the upper layer side. → And then through the filter 24, respectively → After the ozone O ₃ from the ozone supply unit 25 and the hydrogen peroxide H ₂ O ₂ from the hydrogen peroxide supply unit 26 are introduced and dissolved as necessary. , → supplied to the respective purification devices 15.

(4) The purification device 15 includes a photocatalyst 21 and an ultraviolet irradiation means 22 (see FIGS. 1 and 2), and wastewater stratified in the supply tank 14 based on the concentration of the hardly decomposable organic compound 1 These are provided individually corresponding to the layers (see FIG. 2).
That is, the above c. A purification device 15 for drainage 2 from the emulsion layer 19, d. In the purifying device 15 for the waste water 2 from the organic compound layer 20, the ozone O ₃ and the hydrogen peroxide H ₂ O ₂ are previously dissolved in the waste water 2 as described above, and the ultraviolet irradiation means 22 is in the range of 240 nm to 280 nm. Irradiate with UV light.
In contrast, b. The purifier 15 for the waste water 2 from the aqueous solution layer 18 is one in which the ultraviolet irradiation means 22 irradiates medium wavelength ultraviolet light of 240 nm to 280 nm, and the ultraviolet irradiation means 22 irradiates long wavelength ultraviolet light of 310 nm to 390 nm. And are used together.

(5) Then, in each purification device 15, OH radicals are generated by irradiating the photocatalyst 21, further ozone O ₃ and hydrogen peroxide H ₂ O ₂ with ultraviolet rays from the ultraviolet irradiation means 22, and then → OH The radically decomposed organic compound 1 contained in the waste water 2 is oxidized and decomposed by radicals, and the waste water 2 is purified (see FIGS. 1 and 2).
That is, due to the strong oxidizing power and decomposing power of OH radicals, which are the active oxygen species generated, → especially when the photocatalyst 21 and ozone O ₃ or hydrogen peroxide H ₂ O ₂ are used in combination, the two are synergistic. Due to the oxidizing power and decomposing power that act even more strongly, the hard-to-decompose organic compound 1 that contacts the OH radical is strongly oxidized at a fast reaction rate by breaking its carbon chain and organic bond, → Thus, it is quickly and reliably decomposed into carbon dioxide gas CO ₂ , water H ₂ O and other simple low-molecular compounds that are easy to handle.

(6) It should be noted that the oxidative decomposition apparatus 13 is further provided with a second purification apparatus 27 in the example shown in FIG. 3 in order to more reliably carry out such oxidation and decomposition of the hardly decomposable organic compound 1. ing. → That is, the waste water 2 discharged from each purification device 15 is still returned to the supply tank 14 with a high concentration of the organic compound 1 and the remaining low concentration is supplied to the second purification device 27. .
→ And the 2nd purification apparatus 27 is provided with the photocatalyst 21 and the ultraviolet irradiation means 22, the ultraviolet irradiation means 22 irradiates the medium wavelength ultraviolet rays of 240 nm-280 nm, and the ultraviolet irradiation means 22 is 310 nm-390 nm. What irradiates with long wavelength ultraviolet rays is used, and ozone O ₃ and hydrogen peroxide H ₂ O ₂ are dissolved in the waste water 2 in advance as needed.
→ Accordingly, the second purification device 27 oxidizes and decomposes the hardly decomposable organic compound 1 by the generated OH radicals in accordance with the above-described place. → The drainage 2 is circulated and supplied to the second purification device 27 until the concentration of the contained organic compound 1 reaches a level at which it can be discarded. → Then, the concentration of the organic compound 1 is reduced (for example, 40 ppm or less), and the waste water 2 that has reached a level that can be discarded is discarded as general waste water.

(7) Now, according to the oxidative decomposition apparatus 13 for the hardly decomposable organic compound 1, the following first and second cases are obtained.
First, the oxidative decomposition apparatus 13 is directly connected to a chemical treatment process facility. In other words, it is directly connected to the chemical treatment process equipment from which exhaust gas 4 and waste water 2 containing the hardly decomposable organic compound 1 are exhausted, and a large amount of waste water 2 is purified sequentially on the spot. Treat and dispose of general wastewater.
The oxidative decomposition apparatus 13 includes a supply tank 14, a purification apparatus 15, a second purification apparatus 27, and the like. The configuration of the processing equipment is relatively simple, the processing content is relatively easy, and directly. Therefore, the purification process can be performed sequentially, the entire process can be completed in a short time, and there is no processing limit. In other words, compared to the case where a large tank 11 for storage, a tank lorry 3 for transportation, a general storage for biological treatment, etc. are used (see FIG. 4), the processing facilities and processing contents are simplified and the entire processing is simplified. It does not take a long time and there is no processing limit.

Secondly, in the oxidative decomposition apparatus 13, the waste water 2 is first stratified in the supply tank 14, and thus corresponds to the layer of the waste water 2 stratified based on the concentration of the hardly decomposable organic compound 1. The purification device 15 is provided individually.
And the purification apparatus 15 for the waste_water | drain 2 of the layer with the high density | concentration of the organic compound 1 contained, for example, said c. The purifying device 15 for the drainage 2 from the emulsion layer 19, and the d. In the purification device 15 for the waste water 2 from the organic compound layer 20, ozone O ₃ and hydrogen peroxide H ₂ O ₂ are dissolved in advance, and the ultraviolet irradiation means 22 irradiates medium wavelength ultraviolet rays.
Therefore, more powerful oxidation and decomposition are carried out by the synergistic action by the combined use of the photocatalyst 21 and ozone O ₃ or hydrogen peroxide H ₂ O ₂ due to the strong energy ultraviolet rays. By combining the photocatalyst 21 with ozone O ₃ and hydrogen peroxide H ₂ O ₂ , a large amount of OH radicals are efficiently generated at a time. And the organic compound 1 in the waste water 2 of the outer peripheral part in the purification apparatus 15 is mainly by the OH radical produced | generated from the photocatalyst 21, and the organic compound 1 in the waste water 2 of the center part (from the photocatalyst 21). It is oxidized and decomposed all over by OH radicals generated mainly from ozone O ₃ and hydrogen peroxide H ₂ O _{2 (} though far).
On the other hand, the purification device 15 for the drainage 2 of the layer in which the concentration of the contained organic compound 1 is low, for example, b. In the purification device 15 for the drainage 2 from the aqueous solution layer 18, ozone O ₃ and hydrogen peroxide H ₂ O ₂ are not dissolved in advance, and a black light that irradiates long-wavelength ultraviolet rays is used in combination as the ultraviolet irradiation means 22. . Therefore, appropriate oxidation and decomposition are performed efficiently and cost-effectively by using ultraviolet rays having relatively weak energy.
By such a combination, in this oxidative decomposition apparatus 13, the hardly decomposable organic compound 1 contained in the waste water 2 is rapidly and reliably oxidized and decomposed.

<About measurement data>
Table 1 shows measurement data obtained by purifying the waste water 2 using the oxidative decomposition apparatus 13 of the example shown in FIG.
That is, the wastewater 2 having a pH of 4.12 at 23.1 ° C. and CODMn of 13,200 mg / L was supplied, and the result of purification by the purification device 15 without being stored in the supply tank 14 was measured and analyzed over time. COD indicates chemical oxygen demand and was measured using potassium permanganate. The pH value and COD value were measured according to JIS.
As a result, the COD value decreased with the passage of time, and therefore, progress of oxidation and decomposition of the hardly decomposable organic compound 1 contained in the waste water 2 was confirmed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration explanatory diagram of the entire system for explaining a best mode for carrying out the invention of an oxidative decomposition apparatus for a hardly decomposable organic compound according to the present invention. It is for explanation of the best mode for carrying out the invention, and is a configuration explanatory view of a front part of one example thereof. It is for explanation of the best mode for carrying out the invention, and is a configuration explanatory view of the latter part of one example. It is a structure explanatory drawing of the whole system for description of this kind of conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic compound 2 Waste water 3 Tank truck 4 Exhaust gas 5 Filter 6 Blower 7 Adsorption tank 8 Steam 9 Capacitor 10 Separation tank 11 Tank 12 Pump 13 Oxidation decomposition apparatus 14 Supply tank 15 Purification apparatus 16 Neutralization tank 17 Water purification layer 18 Aqueous solution layer 19 Emulsion layer DESCRIPTION OF SYMBOLS 20 Organic compound layer 21 Photocatalyst 22 Ultraviolet irradiation means 23 Piping 24 Filter 25 Ozone supply part 26 Hydrogen peroxide supply part 27 2nd purification apparatus 28 Discriminating means 29 Tank 30 TOD measuring instrument 31 Discriminating means

Claims (6)

An oxidative decomposition apparatus for a hardly decomposable organic compound contained in waste water, comprising a supply tank and a purification apparatus,
The supply tank is supplied and stored with the drainage, and the drainage is stratified vertically by specific gravity based on the vertical concentration change of the organic compound contained,
The purification apparatus is supplied with the waste water of the layer containing the organic compound at a concentration that cannot be discarded from the supply tank, and is provided with a photocatalyst and an ultraviolet irradiation means, and oxidizes the organic compound, An oxidative decomposition apparatus for a hardly decomposable organic compound, characterized by decomposing.   The waste water supplied to the supply tank is made of exhaust gas containing the organic compound mixed with water, and the organic compound includes paraffinic compounds, olefinic compounds, other chain hydrocarbons, 2. The oxidative decomposition apparatus for a hardly decomposable organic compound according to claim 1, comprising: a cyclic hydrocarbon having an aromatic ring, and another cyclic hydrocarbon. The purification device is provided individually corresponding to the drainage layer stratified based on the concentration of the organic compound in the supply tank,
The purification device for the drainage of the organic compound layer and the drainage of the emulsion layer is such that ozone and hydrogen peroxide are previously dissolved in the wastewater, and the ultraviolet irradiation means irradiates medium wavelength ultraviolet rays of 240 nm to 280 nm. And
Thus, the purification device oxidizes and decomposes the organic compound by OH radicals generated by the photocatalyst and the ozone or hydrogen peroxide. Oxidative decomposition equipment.   The waste water is supplied to the purification device via a filter attached in front of the purification device, and the ozone and hydrogen peroxide are supplied by a press-fitting means, a spraying means, a venturi provided in front of the purification device. 4. The oxidative decomposition apparatus for a hardly decomposable organic compound according to claim 3, wherein the apparatus is dissolved in the waste water using other means. The purification device for the drainage of the aqueous solution layer is a combination of a device in which the ultraviolet irradiation means irradiates a medium wavelength ultraviolet ray of 240 nm to 280 nm and a device in which the ultraviolet irradiation means irradiates a long wavelength ultraviolet ray of 310 nm to 390 nm. Has been
4. The oxidative decomposition apparatus for a hardly decomposable organic compound according to claim 3, wherein the purification apparatus oxidizes and decomposes the organic compound by OH radicals generated by the photocatalyst. The waste water discharged from each purification device is returned to the supply tank with a high concentration of the organic compound, and the remaining low concentration is supplied to the second purification device,
The second purification device includes a photocatalyst and ultraviolet irradiation means, and the ultraviolet irradiation means irradiates medium wavelength ultraviolet light of 240 nm to 280 nm, and the ultraviolet irradiation means irradiates long wavelength ultraviolet light of 310 nm to 390 nm. In addition, ozone and hydrogen peroxide are dissolved in the waste water as needed in advance, and the organic compound is oxidized and decomposed by the generated OH radicals.
6. The oxidative decomposition apparatus for a hardly decomposable organic compound according to claim 5, wherein the waste water is circulated and supplied to the second purification device until the concentration of the organic compound reaches a level at which the organic compound can be discarded.

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