JP5534846B2 - Water treatment equipment - Google Patents

Description

  The present invention relates to a water treatment apparatus for decomposing organic substances, inorganic substances, microorganisms contained in clean water, sewage, waste water and the like with active species such as radicals generated by electric discharge and ozone.

Conventionally, ozone has been used for treatments such as oxidative decomposition, sterilization, and deodorization of organic substances in water in fields such as clean water, sewage, industrial wastewater, and pools (see Patent Document 1).
However, ozone has a weak oxidizing power and cannot be mineralized even if it can be made hydrophilic and low molecular. In addition, hardly decomposable organic substances such as dioxins cannot be decomposed.

Therefore, in order to improve the treatment capacity, ozone is generated by discharge, and OH radicals and O radicals having oxidizing power stronger than ozone are generated, and the water to be treated is exposed to a discharge space containing the ozone and radicals. There has been proposed a water treatment apparatus that performs oxidation treatment not only by ozone but also by radicals (see Patent Document 2).
However, radicals have a short lifetime and tend to disappear, so that the efficiency is low, and the water treatment apparatus previously proposed cannot sufficiently exhibit the oxidizing action by radicals.
Therefore, the inventor of the present invention provides a linear electrode as a voltage application electrode along the central axis of the cylindrical electrode as a ground electrode, and applies a high voltage to the linear electrode to cause discharge between both electrodes. At the same time, we proposed a water treatment device that supplies treated water in the form of water droplets to this discharge field and decomposes the material to be treated in the treated water using active species such as radicals and ozone generated in the discharge field. (See Patent Document 3).
In other words, this water treatment apparatus generates radicals and ozone one after another by electric discharge, and improves the treatment efficiency by increasing the surface area of contact with the radicals and ozone by forming water to be treated into water droplets.

Japanese Patent Laid-Open No. 9-267096 JP 2000-279977 A JP 2009-241055 A

  However, in the case of the water treatment apparatus proposed above, the treatment efficiency was better than that of the conventional method, but it is required to further improve the treatment efficiency when put into practical use.

  In view of the above circumstances, an object of the present invention is to provide a water treatment apparatus capable of improving the treatment speed by causing active species such as radicals generated by discharge to act on the water to be treated efficiently.

In order to achieve the above object, a water treatment apparatus according to claim 1 of the present invention (hereinafter referred to as "water treatment apparatus of claim 1") is configured to discharge water to be treated into water droplets by a water droplet forming means. a was supplied into the processing chamber to form a field of water treatment apparatus for decomposing the processed substance in water droplets, oxygen 25 to 90 volume% seen including in the processing chamber, filling the mixed gas balance being nitrogen It is characterized by comprising a mixed gas supply means.
In the water treatment apparatus according to claim 1, the oxygen concentration of the mixed gas is limited to 25 to 90% by volume (more preferably 40 to 90% by volume), because the oxygen concentration is less than 25% by volume. This is because it is thin and the generation amount of OH radicals and O radicals is insufficient, and the decomposition efficiency is deteriorated. If it exceeds 90% by volume, the decomposition efficiency is high, but the discharge state is not stable.
In the water treatment apparatus according to claim 1, the method of supplying the mixed gas is not particularly limited. For example, oxygen gas and nitrogen gas are respectively sent from a oxygen cylinder and a nitrogen cylinder to a treatment chamber by piping using a pump. Examples of the method include a method of mixing in a room, a method in which an oxygen gas pipe and a nitrogen gas pipe are joined together and mixed, and then sent into a processing chamber. Further, there is a method in which a high concentration oxygen gas and air are merged on the way using a PSA (Pressure Swing Adsorption) oxygen concentrator and a blower and then sent into the processing chamber as a predetermined concentration.

The water treatment equipment of the present invention is also configured to and a means for supplying an oxidizing agent in the water to be treated before the step of water droplets of water to be treated.
Although it does not specifically limit as an oxidizing agent, For example, oxygen, ozone, and hydrogen peroxide are mentioned.

As a method for supplying oxidation agent is not particularly limited, for example, in the case of a liquid oxidant, a liquid oxidant using a pump from a tank, a method of supplying in the piping for sending the water to be treated water drop means And a method of supplying a liquid oxidant from a tank to a pretreatment tank in which treated water is stored using a pump. In the case of a gaseous oxidant, pretreatment in which treated water is stored from a cylinder The method of supplying to a tank and bubbling is mentioned. Moreover, the method etc. which supply the ozone generated by the ozone generator to the pretreatment tank in which the to-be-processed water was stored, and bubbling are mentioned.

In the present invention, the substance to be treated is not particularly limited, and examples thereof include various organic substances, bacteria, and odor components.
In the present invention, the water droplet forming means is not particularly limited, and examples thereof include a spray nozzle and a shower nozzle.
In addition, although the said water droplet is not specifically limited, In order to improve the contact with the radical and ozone which generate | occur | produce within a discharge field, it is preferable to use a water droplet as fine as possible.

In the present invention, the discharge method is not particularly limited as long as a discharge that generates high-energy electrons or ultraviolet rays occurs, but one electrode is a voltage application electrode, the other electrode is a ground electrode, and the voltage application electrode is a high voltage. A method of applying a pulse voltage can be mentioned.
The materials for the voltage application electrode and the ground electrode are not particularly limited, but titanium and stainless steel are preferable in consideration of corrosion resistance.

The shape of the electrode is not particularly limited, but in the case of the ground electrode, it is not particularly limited, and examples thereof include a cylindrical electrode such as a cylindrical electrode and a cylindrical mesh electrode, and a flat plate electrode.
On the other hand, in the case of a voltage application electrode, for example, when the ground electrode is a cylindrical electrode, a wire electrode provided along the central axis of the cylindrical electrode, a screw electrode, a sword mountain electrode, a wire brush electrode, etc. When the ground electrode is a flat plate electrode, a flat plate electrode provided in parallel to the flat plate electrode is exemplified.

  Further, a plurality of pairs of voltage application electrodes and ground electrodes may be provided in the processing chamber instead of only one pair.

  The discharge voltage applied between the voltage application electrode and the ground electrode is not particularly limited as long as it is a voltage at which discharge occurs.

  Furthermore, the water treatment apparatus of the present invention includes a water treatment circulation structure comprising a water storage tank that receives and stores the water to be treated, and a pump that sends the water stored in the water storage tank to the supply means as the water to be treated. May be.

As mentioned above, since the water treatment apparatus of Claim 1 is equipped with the mixed gas supply means which fills the process chamber with the mixed gas of oxygen and oxygen containing 25 to 90 volume% of oxygen, it is discharged by discharge. The generated high-energy electrons and ultraviolet rays efficiently react with high-concentration oxygen molecules in the treatment chamber, and a large amount of active species including radicals are generated. The generated active species such as radicals in the water to be treated in droplets. Contact with certainty and act efficiently on organic matter in the water to be treated.
Therefore, the organic matter in the for-treatment water is decomposed quickly and efficiently.

Moreover, when provided with a means for supplying an oxidizing agent in the water to be treated before the step of water droplets of water to be treated, high-energy electrons generated by the discharge, ultraviolet light is supplied to the water to be treated as the oxidizing agent It is possible to efficiently generate active species such as OH radicals and O radicals by efficiently reacting with oxygen molecules, ozone molecules or hydrogen peroxide molecules. And since these produced | generated active species are produced | generated in to-be-processed water, it can be made to act efficiently with respect to the process target substance which exists in to-be-processed water. Therefore, the organic matter in the for-treatment water is decomposed quickly and efficiently.

  That is, when oxygen is used as the oxidant, high-energy electrons generated by discharge react with oxygen molecules supplied into the water to be treated, generate O radicals, and can efficiently decompose the material to be treated. .

  In addition, when ozone or hydrogen peroxide is used as the oxidant, the ultraviolet rays generated by the discharge act on the ozone molecules and hydrogen peroxide molecules supplied into the water to be treated, generating OH radicals, making the target substance efficient. Can be decomposed well.

  Furthermore, ozone molecules generated by the discharge react with hydrogen peroxide molecules supplied into the water to be treated, generate OH radicals, and can efficiently decompose the material to be treated.

It is a schematic diagram explaining 1st Embodiment of the water treatment apparatus concerning this invention. It is a circuit diagram of the high voltage pulse generator of the water treatment apparatus of FIG. It is a schematic diagram explaining another water treatment apparatus. It is a horizontal sectional view of a container main part of a water treatment equipment used in an example and a comparative example. It is a graph which compares and shows the indigo carmine density | concentration change of to-be-processed water with progress of the processing time investigated in Example 4 and Comparative Examples 3 and 4. FIG. Indigo carmine decomposition rate and decomposition efficiency obtained from the results of changes in the indigo carmine concentration of the water to be treated with the passage of treatment time investigated under the water treatment conditions of Examples 1 to 8 and Comparative Examples 1 to 4 are shown in comparison. It is a graph. It is a graph which calculates | requires the decomposition speed and decomposition efficiency from the result of the change of the supply amount of the mixed gas investigated in Example 1, and Examples 9-13, and makes it contrast. It is a graph showing the indigo carmine density | concentration change of to-be-processed water with progress of processing time when it processes on the water treatment conditions of the reference example 1. FIG. It is a graph showing the indigo carmine density | concentration change of to-be-processed water with progress of processing time when it processed on the water treatment conditions of the reference example 2. FIG. It is a graph showing the indigo carmine density | concentration change of to-be-processed water with progress of processing time when it processed on the water treatment conditions of the reference example 3. FIG.

Hereinafter, the present invention will be described in detail with reference to the drawings showing embodiments thereof.
FIG. 1 shows a first embodiment of a water treatment apparatus according to the present invention (a water treatment apparatus according to claim 1).

As shown in FIG. 1, this water treatment device 1a includes a container 2, a cylindrical electrode 3, a linear electrode 4, a treated water tank 5 as a storage tank, a pump 6, and a shower as a water droplet forming means. A nozzle 7, a treated water supply hose 71 serving as a circulation path, a mixed gas supply means 8 a, a treated water tank storage box 9, and a high voltage pulse generator 10 as a high voltage power source are provided.
The container 2 is formed of, for example, an insulating material such as acrylic resin, and is provided so as to close the container body 21 as a cylindrical processing chamber and the lower end of the container body 21 except for the water passage hole 22a. The lower lid portion 22 and the upper lid portion 23 provided so as to close the upper end of the container main body 21 except for the shower nozzle installation hole 23a portion, the lower lid portion 22 being the treated water tank storage box 9. The opening 91 of the to-be-processed water tank storage box 9 is received by the periphery of the opening 91 in a state in which the opening 91 is closed.
An exhaust pipe 25 is provided at the lower end of the container body 21. It is preferable to provide an ozone removing device such as an ozone removing filter in the middle or the outlet of the exhaust pipe 25.

The cylindrical electrode 3 is obtained, for example, by processing a stainless steel 2.5 mesh, wire net of 1.1 mm into a cylindrical shape, and the outer diameter is slightly smaller than the inner diameter of the container body 21.
The linear electrode 4 is formed of, for example, a titanium steel wire having a diameter of 1 mm, and is provided along the central axis of the cylindrical electrode 3.

The to-be-treated water tank 5 is accommodated in the to-be-treated water tank accommodation box 9 so that the water passage hole 22a of the lower lid part 22 faces from below.
The pump 6 is provided adjacent to the treated water tank 5 in the treated water tank storage box 9, and the treated water W in the treated water tank 5 is supplied to the shower nozzle 7 via the treated water supply hose 71. To send to.

The shower nozzle 7 sprays the water to be treated, which has been sent through the water to be treated supply hose 71, into a mist state composed of water droplets having a particle diameter of 1500 μm or less toward the upper opening of the cylindrical electrode 3. ing.
Moreover, the spray angle of the shower nozzle 7 is adjusted to an angle along the inner wall surface of the cylindrical electrode 3 that is the outermost edge of the discharge space at the maximum spread portion of the sprayed water mist M to be sprayed.

  The mixed gas supply means 8a includes an oxygen cylinder 81, an oxygen supply pipe 82, a nitrogen cylinder 83, a nitrogen supply pipe 84, a gas mixer (for example, GM-A2 manufactured by Matsumoto Machinery Co., Ltd.) 85, and a mixed gas supply pipe. 86.

The gas mixer 85 divides oxygen sent from the oxygen cylinder 81 through the oxygen supply pipe 82 and nitrogen sent from the nitrogen cylinder 83 through the nitrogen supply pipe 84 into 25 to 90% by volume of oxygen, Nitrogen is mixed at a predetermined mixing ratio with the remainder.
The mixed gas supply pipe 86 supplies the mixed gas obtained by mixing with the mixer 85 from the upper end of the container main body 21 into the container main body 21.

  As shown in FIG. 2, the high-voltage pulse generator 10 includes a high-voltage DC power supply 101, a capacitor 102, a resistor 103, a trigger tron gap switch 104, a pulse transformer 105, and a trigger circuit 106.

The high voltage pulse generator 10 operates as follows.
That is, the current from the high voltage DC power supply 101 is supplied to the capacitor 102 via the resistor 103, and the capacitor 102 is charged. After the capacitor 102 is charged to the target voltage, the trigger tron gap switch 104 is turned on by a high voltage trigger pulse from the trigger circuit 106. At this time, the electric charge charged in the capacitor 102 flows into the primary side of the pulse transformer 105, and a pulse-like induced voltage is generated on the secondary side due to the mutual inductance.

The high voltage pulse generated on the secondary side of the pulse transformer 105 in this way is applied between the linear electrode 4 and the cylindrical electrode 3.
That is, the terminal 107 is brought into conduction with the linear electrode 4, and the terminal 108 is brought into conduction with the cylindrical electrode 3.

  The number of repetitions of pulses output between the terminals 107 and 108 is controlled by changing the output frequency of the trigger pulse in the trigger circuit 106. The voltage of the output pulse is controlled by switching the output voltage of the high-voltage DC power supply 101.

The water treatment apparatus 1a is configured as described above, and charges water to be treated W containing organic matter or the like into the water tank 5 to be treated, and the cylindrical electrode 3 and the linear electrode 4 by the high voltage pulse generator 10 In between, a high voltage is applied in the form of a pulse to form a discharge space having a cylindrical shape in the vertical direction in the cylindrical electrode 3.
Then, the pump 6 is driven to feed the water to be treated W in the water tank 5 to be treated to the shower nozzle 7 via the hose 71, from above the cylindrical electrode 3 toward the central axis of the cylindrical electrode 3. The water to be treated W is treated while being circulated.
The container main body 21 is supplied by the mixed gas supply means 8a so that the mixed gas containing 25 to 90% by volume of oxygen and the balance of nitrogen is filled.

  That is, in the water treatment apparatus 1a, active species such as ozone, OH radicals, and O radicals are generated in the discharge space by the discharge, and the water droplets in the treated water mist M ejected from the shower nozzle 7 have a cylindrical shape. While falling in the discharge space, these active species come into contact with each other, and the organic matter in each water droplet is efficiently oxidized and decomposed. As described above, the mixed gas is supplied into the container body 21. By means 8a, oxygen is supplied in an amount of 25 to 90% by volume and nitrogen is the balance, so that a large amount of OH radicals and O radicals are efficiently generated, and the process can be performed faster than before. Can do.

FIG. 3 shows another water treatment apparatus .
As shown in FIG. 3, this water treatment apparatus 1b includes oxygen supply means 8b instead of the mixed gas supply means 8a, and other than that the tank 5 has the following configuration. The configuration is the same as that of the water treatment device 1a of the first embodiment.
That is, the oxygen supply means 8b includes an oxygen cylinder 87 and an oxygen supply pipe 88.

The treated water tank 5 includes an oxidizing agent supply unit 55 and a receiving tank unit 54 that receives the treated water W that has fallen through the container main body 21. The oxidant supply unit 55 and the receiving tank unit 54 are partitioned by a partition 51 having a treated water communication hole 53 at the lower end.
The oxidant supply unit 55 is closed at the top, and oxygen is bubbled from the oxygen supply pipe 88 of the oxygen supply means 8b into the water to be treated W to increase the amount of dissolved oxygen in the water to be treated W. In addition, the exhaust pipe 52 provided at the upper portion is used to remove the gas containing excess oxygen inside the oxidant supply unit 55 (excess ozone when ozone is used as the oxidant) from the treated water tank housing box 9. Can be exhausted.

And the oxidizing agent supply part 55 sends the to-be-processed water W which the amount of dissolved oxygen increased as mentioned above to the shower nozzle 7 via the to-be-processed water supply hose 71 by the pump 6. FIG. In addition, when ozone is used as the oxidizing agent in the exhaust pipe 52, it is preferable to provide an ozone removing device such as an ozone removing filter in the middle or at the outlet.
The receiving tank portion 54 is open at the top, and receives the water to be treated W that has passed through the container body 21.

  This water treatment apparatus 1b is configured as described above, and charges water to be treated W containing organic matter or the like into the water to be treated tank 5 and oxygen to the water to be treated in the oxidant supply unit 55 by the oxygen supply means 8b. Bubbling. Further, a high voltage pulse generator 10 applies a high voltage between the cylindrical electrode 3 and the linear electrode 4 in a pulsed manner, and a discharge space having a cylindrical shape in the vertical direction is formed in the cylindrical electrode 3. Then, the pump 6 is driven and the water to be treated W in which the amount of dissolved oxygen in the oxidant supply unit 55 is increased is sent to the shower nozzle 7 via the hose 71 and is cylindrical from above the cylindrical electrode 3. By spraying in the direction of the central axis of the electrode 3, the water to be treated W is treated while being circulated.

  That is, in the water treatment apparatus 1b, active species such as ozone, OH radicals, and O radicals are generated in the discharge space by the discharge, and the water droplets in the treated water mist M ejected from the shower nozzle 7 have a cylindrical shape. While falling in the discharge space, it contacts these active species, and the organic matter in each water droplet is efficiently oxidized and decomposed, but before the water to be treated is converted into water droplets, Since oxygen is supplied and the amount of dissolved oxygen increases, high-energy electrons generated by discharge in the container body 21 react with oxygen molecules supplied into the water to be treated to generate O radicals, The target substance can be efficiently decomposed.

Further, in this water treatment apparatus 1b, the water tank 5 to be treated is divided into an oxidant supply part 55 to which oxygen is supplied and a receiving tank part 54 for receiving water treated below the container body 21 by a partition 51. Since the oxidant supply part 55 and the receiving tank part 54 are communicated only through the communication hole 53 provided at the lower end of the partition 51, oxygen supplied to the oxidant supply part 55 (oxidant) When ozone is used, ozone) does not enter the receiving tank portion 54. That is,
Oxygen supplied into the treated water tank 5 can be prevented from entering the container main body 21 from the water passage hole 21a, and the effect of only dissolved oxygen can be grasped. However, it is not necessary to grasp the effect of only dissolved oxygen. In actual water treatment, the partition 51 is eliminated, and oxygen supplied into the treated water tank 5 enters the container body 21 from the water passage hole 21a. It doesn't matter if it goes in.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the high voltage pulse generator is provided, but a commercially available high voltage pulse generator may be separately provided.
In the above embodiment, the water treatment apparatus includes the mixed gas supply unit. However, the water treatment apparatus may include both the mixed gas supply unit and the oxidant supply unit .

In the above embodiment, the water to be treated is circulated, but it is not necessary to circulate.
In the above-described embodiment, the water to be treated is sprayed from above and sprayed. However, when the cylindrical electrode is a mesh, the cylindrical electrode is connected from the side of the cylindrical electrode through the mesh. The water to be treated may be supplied into the inside.

  Specific examples of the present invention will be described below in comparison with comparative examples.

Example 1
As shown in FIG. 4, a water treatment device having the same configuration as the water treatment device 1a shown in FIG. 1 except that six pairs of cylindrical electrodes 3 and linear electrodes 4 are provided in parallel in the container body 21. The indigo carmine is decomposed as the water to be treated under the following experimental conditions using a UV-visible spectrophotometer (trade name UVmini-1240, manufactured by Shimadzu Corporation), and the light is treated at 610 nm. The change in the concentration of indigo carmine with the lapse of the treatment time of water W was examined.
[Experimental conditions]
Indigo carmine initial concentration in treated water W: about 20 ppm
Amount of treated water W: 7 liters Injection speed (circulation speed) of treated water W: 14 L / min Charging voltage: 20 kV
Number of discharges: 100 times / second Properties of cylindrical electrode 3: 2.5 mesh, wire diameter 1.1 mm, hole area ratio 79.5%, welded wire mesh Outer diameter of cylindrical electrode 3: 39.5 mm
Length of cylindrical electrode 3 (length in the central axis direction): 200 mm × 6 Particle diameter of water mist to be treated: 750 to 970 μm
Spray angle of shower nozzle 7: 30 °
Distance from shower nozzle 7 to cylindrical electrode: The outermost edge of the water mist M to be treated was adjusted to be the upper end of the outer edge of the cylindrical electrode located at the outermost part.
Oxygen / nitrogen ratio of gas mixture: Oxygen: Nitrogen
Mixed gas supply conditions: The mixed gas was supplied into the container main body 21 at 10 L / min (normal temperature and normal pressure).

(Example 2)
Changes in the concentration of indigo carmine were examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 30: 70.

(Example 3)
Changes in the concentration of indigo carmine were examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 40: 60.

Example 4
The change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 50: 50.

(Example 5)
Changes in the concentration of indigo carmine were examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 60: 40.

(Example 6)
Changes in the concentration of indigo carmine were examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 70: 30.

(Example 7)
The change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 80: 20.

(Example 8)
Changes in the concentration of indigo carmine were examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 90: 10.

(Comparative Example 1)
The change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 20: 80.

(Comparative Example 2)
Changes in the concentration of indigo carmine were examined in the same manner as in Example 1 except that the oxygen-nitrogen ratio of the mixed gas was changed to oxygen: nitrogen = 10: 90.

(Comparative Example 3)
A change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that only oxygen was supplied to the container body 21 instead of the mixed gas.

(Comparative Example 4)
A change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that only nitrogen was supplied to the container body 21 instead of the mixed gas.

Example 9
The change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the supply amount of the mixed gas to the container main body 21 was changed to 4 L / min.

(Example 10)
The change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the supply amount of the mixed gas to the container body 21 was 20 L / min.

(Example 11)
The change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the supply amount of the mixed gas to the container body 21 was 30 L / min.

(Example 12)
The change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the supply amount of the mixed gas to the container body was 40 L / min.

(Example 13)
A change in the concentration of indigo carmine was examined in the same manner as in Example 1 except that the supply amount of the mixed gas to the container body 21 was 50 L / min.

FIG. 5 shows a comparison of the change in indigo carmine concentration of the water W to be treated with the passage of treatment time in Example 4, Comparative Example 3, and Comparative Example 4.
Moreover, the decomposition rate and decomposition efficiency were calculated | required from the result of the density | concentration change investigated in the said Examples 1-8 and Comparative Examples 1-4, and it compared and showed in FIG.

Furthermore, the decomposition rate and the decomposition efficiency were obtained from the results of the change in the supply amount of the mixed gas investigated in Example 1 and Examples 9 to 13, and are shown in FIG.
The decomposition efficiency (ppm / min / W) was a value obtained by dividing the decomposition rate (ppm / min) by the power (W) consumed by the discharge.

From FIG. 5, as in Comparative Example 4, when only nitrogen is supplied and the container body 21 is substantially free of oxygen, the decomposition rate of indigo carmine is only slightly increased, and only oxygen is supplied. It can be seen that even when the oxygen content is almost 100% by volume, the decomposition rate becomes slower than when the mixed gas of 50% by volume of oxygen is filled in the container body 21.
Further, in the case of 100% by volume of oxygen, there is a problem in terms of safety because the discharge is not stable and spark discharge is recognized.

Further, from FIG. 6, the decomposition rate is improved almost linearly until the oxygen mixing ratio reaches 50% by volume, becomes almost flat when the mixing rate is less than 50% by volume to less than 100% by volume, and when it is set to 100% by volume. It turns out that it reduces compared with the case where the mixed gas of oxygen 50-90 volume% is filled in the container main body 21. The decomposition efficiency is improved almost linearly until the oxygen mixing ratio reaches 40% by volume, and is almost flat when the mixing ratio is less than 40% by volume to less than 100% by volume. It turns out that it reduces compared with the case where 90 volume% mixed gas is filled in the container main body 21.
That is, when the oxygen concentration is 25% or more of the concentration higher than that of air, the decomposition rate and decomposition efficiency increase almost linearly. The decomposition rate is highest when oxygen: nitrogen = 50: 50 to 90:10 and the decomposition efficiency is oxygen: nitrogen = 40: 60 to 90:10. Therefore, it can be seen that the decomposition rate and the decomposition efficiency become higher if the oxygen mixing ratio corresponding to air is 21% by volume if the oxygen mixing ratio is higher than that.

  Furthermore, it can be seen from FIG. 7 that if the mixture ratio of the mixed gas is constant, the supply amount of the mixed gas does not significantly affect the decomposition efficiency.

( Reference Example 1 )
As shown in FIG. 4, a water treatment device having the same configuration as the water treatment device 1 b shown in FIG. 3, except that six pairs of cylindrical electrodes 3 and linear electrodes 4 are provided in parallel in the container body 21. The indigo carmine was treated as the water to be treated under the following experimental conditions, and the change in the indigo carmine concentration of the water to be treated with the lapse of the treatment time was examined. The result is shown in FIG.
[Experimental conditions]
Indigo carmine initial concentration in treated water W: about 20 ppm
Amount of treated water W: 7 liters of treated water W injection speed (circulation speed): 14 L / min Charging voltage: 20 kV
Number of discharges: 100 times / second Properties of cylindrical electrode 3: 2.5 mesh, wire diameter 1.1 mm, hole area ratio 79.5%, welded wire mesh Outer diameter of cylindrical electrode 3: 39.5 mm
Length of cylindrical electrode 3 (length in the central axis direction): 200 mm × 6 Particle diameter of water mist to be treated: 750 to 970 μm
Spray angle of shower nozzle 7: 30 °
Distance from shower nozzle 7 to cylindrical electrode: The outermost edge of the water mist M to be treated was adjusted to be the upper end of the outer edge of the cylindrical electrode located at the outermost part.
Oxidant supply conditions: Oxygen was supplied at 1 L / min using the oxygen supply means 8b.
Nitrogen was supplied into the container main body 21 at 4 L / min.

( Reference Example 2 )
As an oxidant supply condition, ozone as an oxidant was generated using an ozone generator (N15 manufactured by Nomura Electronics Co., Ltd.), and air containing 50 ppm of ozone was bubbled into the water tank to be treated at 1 L / min. Was treated with indigo carmine in the same manner as in Example 1, the change in indigo carmine concentration of the water to be treated with the lapse of the treatment time was examined, and the result is shown in FIG.

( Reference Example 3 )
As the oxidizing agent supply condition, indigo carmine was treated in the same manner as in Example 1 except that hydrogen peroxide water as the oxidizing agent was dissolved in the water to be treated so that the hydrogen peroxide concentration was 100 ppm. Changes in the indigo carmine concentration of the water to be treated with the progress were examined, and the results are shown in FIG.

  When the oxidizing agent is not added and the inside of the container body 21 is replaced with nitrogen as in the comparative example 4, the decomposition rate of indigo carmine is slight (see FIGS. 5 and 6), but FIGS. As shown in FIG. 10, if the oxidant is supplied to the water to be treated before the water to be treated is made into water droplets and supplied into the container main body 21, the decomposition rate of indigo carmine is dramatically increased. I understand.

  Although the water treatment apparatus of this invention is not specifically limited, For example, it can use for purification | cleaning of the waste_water | drain containing organic substance, disinfection of contaminated water, etc.

1a, 1b Water treatment device 2 Container 21 Container body (treatment chamber)
3 Cylindrical electrode 4 Linear electrode 5 Water tank to be treated (storage tank)
6 Pump 7 Shower nozzle (water droplet forming means)
71 Untreated water supply hose (circulation path)
8a Mixed gas supply means 81 Oxygen cylinder 82 Oxygen supply pipe 83 Nitrogen cylinder 84 Nitrogen supply pipe 85 Mixer 86 Mixed gas supply pipe 8b Oxygen supply means (oxidant supply means)
87 Oxygen cylinder 88 Oxygen supply pipe 10 High voltage pulse generator (high voltage power supply)
W Treated water M Treated water mist

Claims (5)

A water treatment apparatus that decomposes water to be treated into water droplets by means of water droplets, supplies the water into a treatment chamber in which a discharge field is formed, and decomposes the target substance in the water droplets,
Water treatment device, characterized in that oxygen 25 to 90 volume% seen including in the processing chamber, and a mixed gas supply means for filling the mixed gas balance being nitrogen.  The water treatment apparatus according to claim 1, wherein the mixed gas contains 45 to 90% by volume of oxygen, and the balance is nitrogen. The water treatment apparatus according to claim 1 or 2, further comprising means for supplying an oxidant into the water to be treated in a previous step of converting the water to be treated into water droplets.   The water treatment apparatus according to claim 3, wherein the oxidizing agent is at least one selected from oxygen, ozone, and hydrogen peroxide.   5. A storage tank that receives and stores water droplets that have passed through the discharge field, and a circulation path that sends the water stored in the storage tank to the water droplet forming means again, and supplies an oxidizing agent into the storage tank. The water treatment apparatus of crab.

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