JP2005313095A - Water treatment method for effectively utilizing exhaust gas - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water treatment method for effectively utilizing an exhaust gas promoting a dechlorination process by an anaerobic UV reaction, a dechlorination reaction by a UV/O<SB>3</SB>reaction and an ozone reaction such as the cleavage of a double bond or the like utilizing oxygen having a high concentration and nitrogen generated in a PSA oxygen generator. <P>SOLUTION: When water to be treated containing a hardly decomposable organic material is treated by an anaerobic UV reactor 23 and a UV/O<SB>3</SB>reactor 24, in a highly concentrated ozone generator 30, air pressured by an air compressor 31 is ventilated to one adsorption column 32a of the PSA oxygen generator 32, highly purified oxygen in which nitrogen is adsorbed by the adsorption column 32a is supplied to an ozone generator 33, while generating ozone, another adsorption column 32b of the PSA oxygen generator 32 is regenerated to carry out desorption of a nitrogen gas, the adsorption column 32a adsorbing nitrogen and the adsorption column 32b carrying out desorption of nitrogen are properly switched to continuously generate ozone and the nitrogen gas, ozone is supplied to the UV/O<SB>3</SB>reactor 24, and the nitrogen gas is supplied to the anaerobic UV reactor 23. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a water treatment method that effectively uses exhaust gas, and relates to a water treatment technique using nitrogen gas discharged in a water treatment facility having a high-concentration ozone generation facility.

Conventionally, most hardly decomposable organic substances such as dioxins in water treatment facilities are organic halogen compounds, and as a decomposition treatment method, a method using ultraviolet (UV) irradiation and ozone (O ₃ ) aeration is effective. Known to be. Even when only ultraviolet irradiation is carried out alone, it is effective for decomposition (mainly dehalogenation) of difficult-to-decompose organic substances, and more effective under anaerobic conditions with low dissolved oxygen concentration, and generation of oxidation by-products Few.

As a method of supplying ozone in equipment using both ultraviolet (UV) irradiation and ozone (O ₃ ) aeration, there are methods as shown in FIGS.
In this configuration, a device called a PSA [Pressure Swing Adsorption] oxygen generator is used to generate high-concentration ozone with high decomposition efficiency.

Air (nitrogen + oxygen) is supplied to the PSA oxygen generator 2 in a pressurized state by the air compressor 1, oxygen and nitrogen in the air are separated in the adsorption tower 3 a or 3 b, and high-purity oxygen is converted into the ozone generator 4. The ozone generator 4 generates high concentration ozone. The generated high-concentration ozone is supplied to the UV / O ₃ reaction facility 5.

  In the PSA oxygen generator 2, oxygen in the air and nitrogen are separated in one adsorption tower 3a to generate high-purity oxygen, and the nitrogen adsorbed under pressure in the adsorption tower in which the other adsorption capacity 3b is saturated Is desorbed by depressurizing (releasing atmospheric pressure) and discharged out of the system to regenerate the adsorption capacity.

High-purity oxygen is supplied to the ozone generator 4 by switching the adsorption towers 3a and 3b, and high-concentration ozone is continuously supplied from the ozone generator 4 to the UV / O ₃ reaction facility 5. In some cases, three or more adsorption towers are provided in the PSA oxygen generator 2.
JP 2001-300557 A JP-A-8-294694

  In Patent Document 1, an ozone aeration treatment tank and a nitrogen aeration treatment tank are communicated with each other through a circulation system. A technique for promoting ozone reaction such as double bond cleavage and promoting dechlorination reaction under reducing (anaerobic) conditions by nitrogen aeration in a nitrogen aeration treatment tank is disclosed. However, providing an ozone supply source and an inert gas supply source in each of the ozone aeration treatment tank and the nitrogen aeration treatment tank has problems in terms of maintenance and cost.

  In Patent Document 2, high-concentration oxygen is generated from air by a PSA device, and this is sent to an ozone generator to generate a high-concentration ozonized gas. A technique for simultaneously aspirating the contact pond is disclosed.

The present invention solves the above-described problems, and utilizes high-concentration oxygen and nitrogen generated in a PSA oxygen generator, dechlorination treatment by anaerobic UV reaction, and dechlorination reaction by UV / O ₃ reaction. Another object of the present invention is to provide a water treatment method that effectively uses exhaust gas that promotes ozone reaction such as double bond cleavage.

In order to solve the above problems, the water treatment method of effectively using the exhaust gas of the present invention is to treat the water to be treated containing a hardly decomposable organic substance in an anaerobic UV reaction facility and a UV / O ₃ reaction facility, In a high-concentration ozone generator, air pressurized by an air compressor is passed through one adsorption tower of the PSA oxygen generator, and high-purity oxygen gas that has adsorbed nitrogen in the adsorption tower is supplied to the ozone generator. While generating ozone, the other adsorption towers of the PSA oxygen generator are regenerated to desorb nitrogen gas, and the adsorption tower for adsorbing nitrogen and the adsorption tower for desorbing nitrogen are switched appropriately so that ozone and nitrogen gas are It is continuously generated, and ozone is supplied to the UV / O ₃ reaction facility and nitrogen gas is supplied to the anaerobic UV reaction facility.

In the above configuration, the nitrogen gas generated as exhaust gas in the PSA oxygen generator of the high concentration ozone generation facility can be effectively used as an inert gas in the anaerobic UV reaction facility, and the anaerobic UV reaction is performed by the high concentration ozone generation facility. The supply of inert gas in the facility and the supply of ozone in the UV / O ₃ reaction facility are performed simultaneously to accelerate the dechlorination reaction by UV irradiation in an anaerobic environment in the anaerobic UV reaction facility, and the UV / O ₃ reaction. A single high-concentration ozone generating facility can realize dechlorination reaction by ultraviolet irradiation in the presence of ozone in the facility and promotion of ozone reaction such as double bond cleavage.

As described above, according to the present invention, the inert gas supply to the anaerobic UV reaction facility and the ozone supply to the UV / O ₃ reaction facility can be performed in one high-concentration ozone generation facility, A nitrogen supply facility for supplying nitrogen gas to the anaerobic UV reaction facility becomes unnecessary.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following, the hard-to-decompose organic substance includes agrochemicals such as organic halogen compounds such as organochlorine compounds and organophosphorus pesticides, and dioxins such as dioxins, furans and coplanar PCBs.

In FIG. 1 to FIG. 2, a treatment system 21 of water to be treated containing a hardly decomposable organic substance includes an anaerobic UV reaction facility 23 and a UV / O ₃ reaction facility 24 for storing a treatment liquid 22 containing a hardly decomposable organic substance. It is also possible to provide a circulation system (including a circulation pump) that communicates the anaerobic UV reaction facility 23 and the UV / O ₃ reaction facility 24. Either the anaerobic UV reaction equipment 23 or the UV / O ₃ reaction equipment 24 may be arranged in the preceding stage or the latter stage, but in the present embodiment, the anaerobic UV reaction equipment 23 is arranged in the preceding stage, and the anaerobic UV reaction equipment 23 The liquid 22 to be processed flows into the UV reaction facility 23 from the pretreatment facility 25, flows through the UV / O ₃ reaction facility 24, and flows out to the posttreatment facility 26.

The anaerobic UV reaction equipment 23 has a nitrogen diffuser (not shown), and the UV / O ₃ reaction equipment 24 has an ozone diffuser (not shown). It is connected to a nitrogen diffuser and an ozone diffuser. The anaerobic UV reaction facility 23 and the UV / O ₃ reaction facility 24 are each provided with an ultraviolet irradiation device (not shown) soaked in a tank.

The high-concentration ozone generation facility 30 includes an air compressor 31 that compresses air, a PSA oxygen generator 32 having at least two adsorption towers 32a and 32b, an ozone generator 33, an air compressor 31, and each adsorption. It has switchable pipes 34a and 34b for connecting the towers 32a and 32b, and switchable pipes 35a and 35b for connecting the adsorption towers 32a and 32b and the ozone generator 33, and each of the adsorption towers 32a. 32b and the nitrogen diffuser tube of the anaerobic UV reaction facility 23 are connected by switchable nitrogen gas supply tubes 36a and 36b, and the ozone generator 33 and the ozone diffuser tube of the UV / O ₃ reaction facility 24 are connected to the ozone supply tube. 37 is connected.

Hereinafter, the operation of the above-described configuration will be described. The high-concentration ozone generation facility 30 ventilates the air pressurized by the air compressor 31 through the pipe 34 to one adsorption tower 32a of the PSA oxygen generator 32. Ozone is generated by supplying high-purity oxygen gas having adsorbed nitrogen in the adsorption tower 32a to the ozone generator 33 through the pipe 35a. The generated ozone is supplied to the ozone diffuser tube of the UV / O ₃ reaction facility 24 through the ozone supply tube 37. Simultaneously with the adsorption operation in the previous adsorption tower 32a, the regeneration operation of the other adsorption tower 32b of the PSA oxygen generator 32 is performed, and the nitrogen gas is desorbed from the adsorption tower 32b. The desorbed nitrogen gas is supplied to the nitrogen diffuser tube of the anaerobic UV reaction equipment 23 through the nitrogen gas supply tube 36b. As shown in FIG. 2, ozone and nitrogen gas are continuously generated by appropriately switching between an adsorption tower 32a that adsorbs nitrogen and an adsorption tower 32b that desorbs nitrogen.

In the anaerobic UV reaction facility 23, the dissolved oxygen contained in the liquid to be treated 22 is removed by aeration of nitrogen gas, so that ozone rays (185 nm) in the ultraviolet rays irradiated from the ultraviolet irradiation device are consumed by the dissolved oxygen. It works effectively without increasing the decomposition efficiency of the hardly decomposable organic substances by the dechlorination reaction. Further, since the inside of the tank becomes an anaerobic (reducing) environment due to nitrogen aeration, it is difficult to generate an oxidation by-product, and the biological or food toxicity of the decomposition product is reduced. On the other hand, in the UV / O ₃ reaction facility 24, the hardly decomposable organic substance contained in the liquid to be treated 22 is oxidatively decomposed by ultraviolet rays in the presence of ozone.

As described above, the nitrogen gas generated as the exhaust gas in the PSA oxygen generator 32 of the high concentration ozone generation facility 30 can be effectively used as the inert gas in the anaerobic UV reaction facility 23. The supply of inert gas in the reactive UV reaction facility 23 and the supply of ozone in the UV / O ₃ reaction facility 24 are simultaneously performed to accelerate the dechlorination reaction by ultraviolet irradiation in the anaerobic UV reaction facility 23. The high-concentration ozone generation facility 30 can realize the dechlorination reaction by UV irradiation in the presence of ozone in the UV / O ₃ reaction facility 24 and the promotion of ozone reaction such as double bond cleavage.

Schematic diagram of water treatment equipment that effectively uses exhaust gas in an embodiment of the present invention Schematic diagram of water treatment equipment that effectively uses exhaust gas in the same embodiment Schematic diagram of conventional water treatment equipment Schematic diagram of conventional water treatment equipment

Explanation of symbols

21 treatment system 22 liquid to be treated 23 anaerobic UV reaction equipment 24 UV / O ₃ reaction equipment 25 pretreatment equipment 26 post-treatment equipment 30 high concentration ozone generation equipment 31 air compressor 32 PSA oxygen generator 32a, 32b adsorption tower 33 ozone Generator 34a, 34b, 35a, 35b Piping 36a, 36b Nitrogen gas supply pipe 37 Ozone supply pipe

Claims (1)

When water to be treated containing persistent organic substances is treated in the anaerobic UV reaction facility and the UV / O ₃ reaction facility, the air pressurized by the air compressor is used in the high concentration ozone generation facility. A gas is passed through one adsorption tower, and the high purity oxygen gas that has adsorbed nitrogen in the adsorption tower is supplied to the ozone generator to generate ozone, while the other adsorption tower of the PSA oxygen generator is regenerated to generate nitrogen gas. The adsorption tower for adsorbing nitrogen and the adsorption tower for desorbing nitrogen are appropriately switched to continuously generate ozone and nitrogen gas, supply ozone to the UV / O ₃ reaction facility, A water treatment method for effectively using exhaust gas, characterized in that an exhaust gas is supplied to an anaerobic UV reaction facility.

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