JP2015171672A - Water treatment apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform decomposition of hardly degradable substances or removal of organic dirt highly efficiently at a high speed.SOLUTION: A flat plate-shaped shower plate 12 is disposed above a plate electrode 2 in a treatment tank 1. The shower plate 12 is provided with a plurality of holes 12a. The shower plate 12 drops supplied water to be treated 4 onto the plate electrode 2 through holes 12a as water droplets 4a. Wire electrodes 6a, 6b, 6c are disposed between the plate electrode 2 and the shower plate 12. The plate electrode 2 is electrically grounded. Electric discharge generating means 10 applies a high voltage between the plate electrode 2 and the wire electrodes 6a, 6b, 6c to generate electric discharges 11a, 11b, 11c.

Description

  The present invention relates to a water treatment apparatus and a water treatment method for treating water to be treated using ozone, radicals, and the like generated by discharge.

  So far, ozone or chlorine has generally been used in the treatment of water and sewage. However, for example, industrial wastewater and reused water may contain a hardly decomposable substance that is not decomposed by ozone or chlorine. In particular, the removal of dioxins and dioxane is a major issue.

In some cases, by combining ozone (O ₃ ) with hydrogen peroxide (H ₂ O ₂ ) or ultraviolet rays, hydroxyl radicals (OH radicals) that are more active than ozone or chlorine are generated in the water to be treated. Although a method for removing a degradable substance has been put into practical use, the apparatus cost and the operation cost are very high and are not so popular. In view of this, a method has been proposed in which OH radicals generated by electric discharge are directly applied to the water to be treated to remove the hardly decomposable substance with high efficiency.

  Specifically, streamer discharge is formed by applying a pulse voltage between a linear high-voltage electrode and a cylindrical ground electrode surrounding the linear high-voltage electrode, and water to be treated is treated from above with a streamer discharge space. A water treatment apparatus for treating water to be treated has been proposed. According to this water treatment apparatus, short-lived OH radicals can be efficiently applied to the water to be treated (see, for example, Patent Document 1).

  Also, a water treatment device that treats the water to be treated by arranging a pair of electrode plates facing each other in an inclined state so that the water to be treated flows down on the lower electrode and forming a barrier discharge between the electrodes. Has also been proposed. According to this water treatment apparatus, water to be treated can be efficiently treated with a simple configuration (see, for example, Patent Document 2).

Japanese Patent No. 4934119 (first page, 1st to 8th lines, FIG. 1) Japanese Patent No. 4635204 (first page, lines 1-14, FIG. 1)

  However, in the conventional water treatment apparatus shown in Patent Document 1 described above, the water to be treated falls vertically in the streamer discharge space, so that the OH radicals present in the streamer discharge space are in contact with the water to be treated. Time is extremely short. For this reason, when decomposing a hardly decomposable substance or removing high-concentration organic dirt, it is necessary to circulate the water to be treated many times or make the discharge electrode very high. For this reason, an increase in the energy to suck up the water to be treated and an increase in the size of the apparatus are problematic.

  On the other hand, in the conventional water treatment apparatus shown in Patent Document 2, contact between OH radicals generated by discharge and the water to be treated is limited to the surface of the water to be treated. I can't make it work. In addition, since the lifetime of OH radicals is as short as 1 millisecond or less, there is a problem that the treatment of deep portions of the water to be treated does not proceed substantially because it is only effective in the immediate vicinity of the water surface.

  The present invention has been made in order to solve the above-described problems, and a water treatment apparatus and water that can perform the decomposition of a hardly decomposable substance or the removal of high-concentration organic stains with high efficiency and high speed. The object is to obtain a processing method.

  The water treatment apparatus according to the present invention is provided with a ground electrode that is inclined with respect to a horizontal plane, disposed above the ground electrode, and provided with a plurality of holes. And a shower plate that drops onto the ground electrode as water droplets through the holes, and a discharge electrode that is disposed between the ground electrode and the shower plate and forms a discharge with the ground electrode.

  In the water treatment apparatus of the present invention, the water to be treated is made into water droplets by the shower plate and dropped onto the ground electrode, so that it is possible to perform the decomposition of the hardly decomposable substance or the removal of high-concentration organic dirt at a high efficiency and at a high speed. it can.

It is sectional drawing of the water treatment apparatus by Embodiment 1 of this invention. It is a perspective view which shows the principal part of the water treatment apparatus of FIG. It is explanatory drawing for demonstrating the water treatment operation | movement of the water treatment apparatus of FIG. It is a graph which shows the result of the water treatment test by the water treatment apparatus of Embodiment 1. It is sectional drawing of the shower plate of the water treatment apparatus by Embodiment 2 of this invention. It is a perspective view which shows the shower plate of the water treatment apparatus by Embodiment 3 of this invention. It is a perspective view which expands and shows the hole of FIG. It is sectional drawing of the shower plate of the water treatment apparatus by Embodiment 4 of this invention. It is sectional drawing of the water treatment apparatus by Embodiment 5 of this invention. It is sectional drawing which expands and shows the principal part of FIG. It is a block diagram which shows the control system of the water treatment apparatus of FIG. It is a perspective view which shows the 1st modification of a discharge electrode. It is a perspective view which shows the 2nd modification of a discharge electrode. It is a perspective view which shows the 3rd modification of a discharge electrode.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
1 is a cross-sectional view of a water treatment apparatus according to Embodiment 1 of the present invention. In the figure, a water supply port 1a and a gas discharge port 1b are provided in the upper part of a metal-made treatment tank 1 having a sealed structure. A drain port 1 c is provided in the lower part of the processing tank 1. A gas supply port 1 d is provided on the side surface of the processing tank 1.

  A plate electrode 2 as a ground electrode is accommodated in the processing tank 1. The flat plate electrode 2 is supported by an upstream frame 3a and a downstream frame 3b that are set up on the bottom surface of the processing tank 1, and is arranged to be inclined with respect to a horizontal plane. That is, the upstream end (right end in FIG. 1) of the plate electrode 2 is higher than the downstream end (left end in FIG. 1).

  A flat shower plate 12 is disposed above the flat electrode 2 in the treatment tank 1. The shower plate 12 is supported by the upstream support member 13a and the downstream support member 13b, and is disposed to be inclined with respect to the horizontal plane. The shower plate 12 is arranged in parallel to the flat plate electrode 2 so as to face the upper surface of the flat plate electrode 2. That is, the upstream end (right end in FIG. 1) of the shower plate 12 is higher than the downstream end (left end in FIG. 1).

  The shower plate 12 is provided with a plurality of (many) holes 12a. As the shower plate 12, for example, a punching metal material or a mesh-like plate material can be used.

  The upstream end of the shower plate 12 is disposed directly below the water supply port 1a. The treated water 4 is supplied into the treatment tank 1 from the water supply port 1 a and flows obliquely downward along the upper surface of the shower plate 12. The shower plate 12 drops the supplied treated water 4 on the plate electrode 2 as water droplets 4a through the holes 12a.

  The treated water 4 that has fallen onto the plate electrode 2 flows obliquely downward along the upper surface of the plate electrode 2 and is discharged out of the treatment tank 1 from the drain port 1c.

  A plurality of (three in this example) wire electrodes 6 a, 6 b, and 6 c as discharge electrodes are disposed above the flat plate electrode 2 in the treatment tank 1 via a gap with respect to the flat plate electrode 2. The wire electrodes 6a, 6b, 6c are disposed between the flat plate electrode 2 and the shower plate 12.

  Further, the wire electrodes 6 a, 6 b, 6 c are arranged at intervals in the flow-down direction of the water 4 to be treated. Furthermore, the wire electrodes 6 a, 6 b, 6 c are arranged at equal intervals with respect to the upper surface of the plate electrode 2. Furthermore, the wire electrodes 6a, 6b, 6c are stretched in parallel and horizontally in the width direction of the plate electrode 2 (X-axis direction in FIG. 1).

  A pulse power source 7 is installed outside the processing tank 1. The wire electrodes 6a, 6b, 6c are connected in parallel to the pulse power source 7 via the wiring 8. The pulse power source 7 is electrically insulated from the processing tank 1 by an insulating portion 9. The plate electrode 2 is electrically grounded. The discharge forming means 10 of the first embodiment has a pulse power source 7 and a wiring 8, and applies a high voltage between the plate electrode 2 and the wire electrodes 6a, 6b, 6c to discharge 11a, 11b, 11c. Form.

  A gas supply source 17 filled with oxygen gas is connected to the gas supply port 1 d via a flow rate regulator 18.

  FIG. 2 is a perspective view showing a main part of the water treatment apparatus of FIG. The plate electrode 2 is inclined by an inclination angle θ with respect to the horizontal direction. A pair of side walls 20 a and 20 b are provided at both ends in the width direction of the plate electrode 2. The treated water 4 flows down between the side walls 20a and 20b on the plate electrode 2.

  A plurality of pairs (three pairs in this example) of holding members 21 holding the wire electrodes 6a, 6b, 6c are fixed on the side walls 20a, 20b. The wire electrodes 6 a, 6 b and 6 c are electrically insulated from the side walls 20 a and 20 b and the plate electrode 2 by the holding member 21.

  Next, the operation will be described. The oxygen gas supplied from the gas supply source 17 is adjusted to a predetermined flow rate by the flow rate regulator 18 and then supplied into the processing tank 1 from the gas supply port 1d. The gas in the processing tank 1 is exhausted from the gas discharge port 1b at the same flow rate as the supply oxygen gas flow rate. As a result, after a predetermined time has elapsed, air is discharged from the processing tank 1, and an atmosphere having a high oxygen concentration is formed in the processing tank 1. By setting it as the atmosphere of high oxygen concentration, ozone concentration becomes high and the decomposition capability of a hardly decomposable substance increases.

  The treated water 4 supplied from the water supply port 1 a onto the shower plate 12 flows on the shower plate 12 as flowing water. At this time, a part of the flowing water becomes the water droplets 4 a from the holes 12 a of the shower plate 12 and sequentially falls on the flat plate electrode 2. The water droplets 4a pour onto the inclined surface of the plate electrode 2, flow down by forming a water film between the side walls 20a and 20b on the plate electrode 2, and are discharged from the drain port 1c.

  While flowing the water 4 to be treated in this way, the pulse power source 7 is operated and a pulse voltage is applied to the wire electrodes 6a, 6b, 6c, thereby discharging from the wire electrodes 6a, 6b, 6c toward the flat plate electrode 2. 11a, 11b, and 11c are formed.

  FIG. 3 is an explanatory diagram for explaining a water treatment operation of the water treatment apparatus of FIG. 1. The surface of the water droplet 4a that has dropped from the shower plate 12 and the surface of the flowing water that flows on the flat plate electrode 2 are exposed to the formed discharge field (space). As a result, a reaction occurs at the contact surface at the gas-liquid interface between the water droplet 4a and the discharge and the contact surface at the gas-liquid interface between the flowing water flowing on the flat plate electrode 2 and the discharge, and the hardly decomposable substance in the treated water 4 Water treatment such as removal of water is performed.

  Here, the size of the hole 12a, the opening ratio of the hole 12a occupying the entire shower plate 12, the flow rate of the water 4 to be treated, and the inclination angle of the shower plate 12 are important setting values for forming the water droplet 4a. . Therefore, it is necessary to optimize the set value in advance through experiments. Here, a punching metal material was used as the shower plate 12, the diameter of each hole 12a was 5 mm, and the aperture ratio was 60%.

  The diameter of the hole 12a is preferably in the range of 1 mm to 100 mm, and the aperture ratio is preferably in the range of 10% to 80%. Moreover, it is desirable that all of the treated water 4 flowing on the shower plate 12 falls as water droplets 4a while flowing from upstream to downstream.

Next, the principle of water treatment by the water treatment apparatus of Embodiment 1 will be described. Here, the decomposition of organic substances will be described as an example, but O ₃ and OH radicals generated by discharge are also effective for sterilization and decolorization.

As described above, the discharge field (space) formed between the wire electrodes 6a, 6b, 6c and the flat plate electrode 2 includes the surface of the water droplet 4a dropped from the shower plate 12 and the surface of the flowing water flowing on the flat plate electrode 2. And is exposed. At this time, oxygen molecules (O ₂ ) and water molecules (H ₂ O) collide with high-energy electrons, and dissociation reactions of formulas (1) and (2) occur. Here, e is an electron, O is atomic oxygen, H is atomic hydrogen, and OH is an OH radical.
e + O ₂ → 2O (1)
e + H ₂ O → H + OH (2)

Part of the atomic oxygen generated by the formula (1) becomes ozone (O ₃ ) by the reaction of the formula (3). Here, M is the third body of the reaction and represents any molecule or atom in the air.
O + O ₂ + M → O ₃ (3)

Further, part of the OH radical generated in the formula (2) becomes hydrogen peroxide (H ₂ O ₂ ) by the reaction in the formula (4).
OH + OH → H ₂ O ₂ (4)

Oxidized particles such as O, OH, O ₃ , and H ₂ O ₂ generated by the reactions of the formulas (1) to (4) are converted into organic substances in the water 4 to be treated by the reaction of the formula (5). Oxidative decomposition into carbon dioxide (CO ₂ ) and water. Here, R is an organic substance to be processed.
R + (O, OH, O ₃ , H ₂ O ₂ ) → CO ₂ + H ₂ O (5)

  According to the water treatment apparatus and the water treatment method of the first embodiment, the plate electrode 2 and the wire electrode 6a are obtained while the water to be treated 4 is dropped as the water droplets 4a on the plate electrode 2 through the holes 12a of the shower plate 12. , 6b, and 6c are formed with discharges 11a, 11b, and 11c, so that many reactions of the formula (5) can be generated, and high-concentration organic dirt can be removed with high efficiency and high speed. it can. In addition, such an effect can be obtained similarly for the decomposition of a hardly decomposable substance.

  That is, in the first embodiment, in addition to the water droplets 4a dropped from the shower plate 12, the dropped water droplets 4a flow on the inclined flat plate electrode 2. Therefore, compared with the case of only the water drop which falls like patent document 1, and the case of only the flowing water which flows through an inclined surface like patent document 2, the area where discharge 11a, 11b, 11c and to-be-processed water 4 contact Will increase. Thereby, the reaction area of the organic substance in the to-be-processed water 4 and an oxidizing particle increases, and decomposition | disassembly of organic substance advances (effect of a wide gas-liquid interface area).

  Moreover, since the to-be-processed water 4 flows on the inclined flat plate electrode 2, a flow-down speed becomes slow compared with the case where it falls vertically, and it contacts the discharge 11a, 11b, 11c for a long time. For this reason, the frequency | count of reaction with the organic substance and oxidizing particle in the to-be-processed water 4 increases, and decomposition | disassembly of organic substance advances (long-term stay effect).

  It was confirmed by the following test that the reaction area is increased and the decomposition rate of the organic matter is improved by generating the water droplet 4a. In the test, 1 L of a solution in which 50 mg of sodium acetate was dissolved in pure water as the water to be treated 4 containing a hardly decomposable substance was decomposed using the water treatment apparatus shown in FIG. As a discharge gas, 500 sccm of oxygen was supplied. Then, the case where there was no water droplet 4a, that is, the case where the solution was directly flowed on the flat plate electrode 2 was compared with the case where the solution was converted into water droplets through the shower plate 12.

  In the test, the solution discharged from the drain port 1c was treated while being returned to the water supply port 1a and circulated. In addition, a part of the solution was sampled at regular time intervals to perform organic carbon (TOC) evaluation.

  FIG. 4 is a graph showing the time change of TOC by the above test. In FIG. 4, the TOC value is normalized by the maximum value, ● indicates that the solution was not formed into water droplets, and ○ represents the case where the solution was formed into water droplets.

  As shown in FIG. 4, the to-be-processed water 4 was decomposed | disassembled with progress of processing time, and the TOC density | concentration decreased. In particular, when the solution was made into water droplets, 80% of organic carbon was decomposed after one hour. On the other hand, when the solution did not form water droplets, only 20% decomposed after 1 hour. From the above, it was confirmed that the decomposition rate was improved by forming the water 4 to be treated into water droplets with the shower plate 12.

Embodiment 2. FIG.
Next, FIG. 5 is a sectional view of a shower plate 12 of a water treatment apparatus according to Embodiment 2 of the present invention. In the second embodiment, a plurality of protrusions 12 b protruding downward from the peripheral edge of the hole 12 a are attached to the lower surface of the shower plate 12. Other configurations are the same as those in the first embodiment.

  In such a water treatment apparatus, since the projection part 12b is attached to the shower plate 12, the drop of the water droplet 4a from the shower plate 12 becomes easy, and water treatment capability can be improved.

Embodiment 3 FIG.
Next, FIG. 6 is a perspective view showing a shower plate 12 of a water treatment apparatus according to Embodiment 3 of the present invention, and FIG. 7 is an enlarged perspective view showing a hole 12a in FIG. In the third embodiment, the portion corresponding to the hole 12a of the plate material constituting the shower plate 12 is cut out into a triangular claw shape, leaving a portion, and the cut-out portion is bent toward the drop direction of the water droplet 4a. Thus, a triangular hole 12a and a protrusion 12c having the same shape are formed at the same time. Other configurations are the same as those in the first embodiment.

  In such a water treatment apparatus, since the projection part 12c is formed in the shower plate 12, the fall of the water droplet 4a from the shower plate 12 becomes easy, and it can improve water treatment capability. Moreover, the protrusion part 12c can be added easily.

  In the third embodiment, the triangular protrusion 12c is shown, but the shape of the protrusion 12c is not limited to this.

Embodiment 4 FIG.
Next, FIG. 8 is a sectional view of a shower plate 12 of a water treatment apparatus according to Embodiment 4 of the present invention. In the fourth embodiment, a barrier member 14 is disposed below the shower plate 12 so as to make the water droplets 4a fall on the flat plate electrode 2 by hitting the water droplets 4a falling from the shower plate 12. As the barrier member 14, for example, a combination of a plurality of wires, a mesh plate, a punching metal plate, or the like can be used, and is selected according to the required size of the water droplet 4a. In this example, the barrier member 14 is supported by the shower plate 12 via a plurality of supports 15. Other configurations are the same as those in the first, second, or third embodiment.

  In such a water treatment apparatus, since the water droplet 4a is refined by the barrier member 14, the total surface area of the entire water droplet 4a is increased, the contact area between the water droplet 4a and the discharge is increased, and more efficiently, and Water treatment can be performed at higher speed.

Embodiment 5 FIG.
9 is a sectional view of a water treatment apparatus according to Embodiment 5 of the present invention. A water supply port 31a and a gas discharge port 31b are provided in the upper part of the metal-made treatment tank 31 having a sealed structure. A drain port 31 c and a gas supply port 31 d are provided in the lower part of the processing tank 31.

  A water amount adjusting mechanism 32 is provided at the water supply port 31a. The water to be treated 4 is supplied from the water supply port 31a to the treatment tank 31 via the water amount adjusting mechanism 32, processed in the treatment tank 31, and then discharged from the drain port 31c.

  A shower plate 12 of the processing apparatus is disposed at the top of the processing tank 31. Below the shower plate 12, first to fourth water treatment units 33a, 33b, 33c, and 33d are arranged in the vertical direction. That is, in the treatment tank 31, the first to fourth water treatment units 33a, 33b, 33c, and 33d are arranged in multiple stages.

  The first to third water treatment units 33a, 33b, and 33c have a shower electrode 34 that is a ground electrode that also serves as a shower plate, and wire electrodes 6a, 6b, and 6c similar to those in the first embodiment. . The shower electrode 34 is provided with a plurality of (many) holes 34a. As the shower electrode, for example, a punching metal material or a mesh plate can be used. The shower electrode 34 drops the supplied treated water 4 as water droplets 4a through the holes 34a.

  The fourth water treatment unit 33d has the same plate electrode 2 and wire electrodes 6a, 6b, 6c as in the first embodiment.

  In the water treatment units 33a, 33b, 33c, and 33d adjacent in the vertical direction, the shower electrodes 34 or the flat plate electrodes 2 are alternately inclined in the opposite direction with respect to the horizontal plane. The shower electrode 34 of the first water treatment unit 33a is inclined in the direction opposite to the shower plate 12 with respect to the horizontal plane. Thus, the shower plate 12, the shower electrode 34, and the flat plate electrode 2 are arrange | positioned so that the to-be-processed water 4 may flow continuously toward the lower stage from the upper stage.

  A weir 35 that dams the water to be treated 4 is attached to the downstream end of the shower plate 12 and the shower electrode 34, and all the flowing water is guided to the lower shower electrode 34 or the flat plate electrode 2.

  The wire electrodes 6a, 6b, 6c of each water treatment unit 33a, 33b, 33c, 33d are electrically connected in parallel with the pulse power source 7 (FIG. 1), and the shower electrode 34 and the plate electrode 2 are electrically connected. Grounded.

  FIG. 10 is an enlarged cross-sectional view showing a main part of FIG. A first end of the shower plate 12 in the direction of flowing water, here, an end on the downstream side, is rotatably connected to a support portion 36 fixed in the treatment tank 31.

  In the treatment tank 31, a plurality of drive devices 37 are provided as angle adjustment mechanisms. The drive device 37 is provided with a vertical drive rod 37a that is driven in the vertical direction. A second end of the shower plate 12 in the direction of running water, here the upstream end, is connected to the upper end of the vertical drive rod 37a. The shower plate 12 is rotated around the downstream end by the driving device 37. That is, the inclination angle of the shower plate 12 can be adjusted by the driving device 37.

  As for the shower electrode 34 and the flat plate electrode 2, the tilt angle can be adjusted in the same manner as the shower plate 12. By adjusting the inclination angles of the shower plate 12, the shower electrode 34, and the flat plate electrode 2, respectively, it is possible to set an optimum processing capability.

  Next, the operation will be described. While supplying gas into the processing tank 31 from the gas supply port 31d and exhausting from the gas discharge port 31b, the inside of the processing tank 31 is filled with gas.

  The to-be-treated water 4 is supplied into the treatment tank 31 through the water supply port 31a, and first falls as water droplets 4a while flowing on the shower plate 12 onto the shower electrode 34 of the first water treatment unit 33a. In addition, the size, opening ratio, flow rate, and inclination angle of the holes 12a of the shower plate 12 are set so that all of the water to be treated 4 flowing on the uppermost shower plate 12 becomes the water droplets 4a.

  The water droplet 4a falling on the first water treatment unit 33a flows on the shower electrode 34 as flowing water, and falls on the shower electrode 34 of the second water treatment unit 33b as water droplet 4a. In this way, the water to be treated 4 sequentially advances to the lower water treatment units 33c and 33d. The gas supplied into the processing tank 31 rises as an air current from the lower area in the processing tank 31 and is exhausted from the gas discharge port 31b.

  In each of the water treatment units 33a, 33b, 33c, and 33d, discharges 11a, 11b, and 11c are generated by applying a pulse voltage to the wire electrodes 6a, 6b, and 6c. The water droplet 4a that has fallen on each of the water treatment units 33a, 33b, 33c, and 33d comes into contact with the discharge field (space) and is treated by the reaction and action described above.

  Moreover, since the to-be-processed water 4 which flows down each water treatment unit 33a, 33b, 33c, 33d is also in contact with a discharge field, it is processed by the above-mentioned reaction and action.

  In addition, although all the to-be-processed water 4 cannot be decomposed | disassembled only by the 1st water treatment unit 33a, by passing 1st thru | or 4th water treatment unit 33a, 33b, 33c, 33d, all The treatment capacity of each water treatment unit 33a, 33b, 33c, 33d is set so that the to-be-treated water 4 is decomposed.

  The treatment capacity of the entire treatment tank 31 and the treatment ability of each of the water treatment units 33a, 33b, 33c, and 33d are adjusted by the flow rate of the water 4 to be treated, the electric power of discharge, and the inclination angle of the shower electrode 34 or the plate electrode 2. . The flow rate of the water to be treated 4 can be adjusted by the water amount adjusting mechanism 32. Further, the inclination angle of the shower electrode 34 and the flat plate electrode 2 can be adjusted by the driving device 37.

  For example, when the concentration of the substance to be treated in the water to be treated 4 is high, or when a hardly decomposable substance is to be treated, the flow rate of the water to be treated 4 is set low, and the shower electrode 34 and the flat plate electrode 2 are set. Set the angle of inclination with respect to the horizontal direction small. Thereby, the to-be-processed water 4 stays in the water treatment units 33a, 33b, 33c, and 33d for a long time, and decomposition | disassembly of a process target substance advances.

  Conversely, when the concentration of the treatment target substance in the treated water 4 is low, or when the substance that is easily decomposed is the treated object, the flow rate of the treated water 4 is set large, and the shower electrode 34 and The inclination angle of the plate electrode 2 with respect to the horizontal direction is set large. Thereby, since the to-be-processed water 4 passes water treatment unit 33a, 33b, 33c, 33d in a short time, high-speed water treatment is performed as a whole.

  In such a water treatment apparatus and water treatment method, since the water treatment units 33a, 33b, 33c, and 33d are arranged in multiple stages, the time during which the treated water 4 is in contact with the discharges 11a, 11b, and 11c is extended, and the water treatment unit and the water treatment method are implemented. Compared with Form 1 of the present invention, a high water treatment effect can be obtained only by passing through the treatment tank 31 once.

  Further, when the organic substance in the vicinity of the gas-liquid interface of the water droplet 4a is decomposed by the action of OH radicals or the like and the concentration thereof is lowered, the reaction frequency of the above-described formula (5) is lowered. On the other hand, in the fifth embodiment, the formed water droplet 4a falls on the surface of the water to be treated 4 in a short time and merges with the water to be treated 4, and then another water droplet 4a from the shower electrode 34 again. Therefore, the formation and coalescence of the water droplets 4a are frequently repeated. As the water droplet 4a is re-formed, the molecules in the vicinity of the gas-liquid interface are exchanged, and new organic molecules appear. Therefore, the reaction of the formula (5) occurs continuously, and the decomposition of the organic matter proceeds. (Molecular exchange effect)

Further, since the water to be treated 4 is agitated in the process of forming and uniting the water droplets 4a, the concentrations of O ₃ and H ₂ O ₂ dissolved in the water to be treated 4 are made uniform, and O ₃ , H in water The decomposition reaction of the organic substance R generated by ₂ O ₂ occurs efficiently (mixing effect).

Furthermore, since the gas is introduced into the lower area in the processing tank 31 and exhausted from the gas discharge port 31b disposed in the upper part of the processing tank 31, an air flow rising in the processing tank 31 is formed. Due to the effect of pushing up the water droplet 4a by the ascending air current, the drop time of the water droplet 4a is delayed, the contact time with O ₃ and OH radicals generated by the discharge is increased, and the reaction is promoted.

  By the above effects, for example, as in Patent Document 1, water to be treated can be circulated many times, and water treatment can be performed without making the discharge electrode very high. Moreover, compared with patent document 2, water treatment can be performed efficiently and at high speed.

  In addition, since the flow rate of the water to be treated 4 and the inclination angle of each shower electrode 34 and the flat plate electrode 2 can be adjusted, an optimum operation according to the water quality and the amount of the water to be treated 4 is possible.

  Here, FIG. 11 is a block diagram showing a control system of the water treatment apparatus of FIG. The central control device 111 outputs control signals to the gas flow rate control unit 112, the water amount control unit 113, the tilt angle control unit 114, and the power control unit 115, respectively, and performs optimal control of the processing capacity of the entire device.

  The gas flow rate control unit 112 outputs a command signal to the gas flow rate adjustment mechanism 116 according to the control signal from the central control device 111 to optimize the flow rate of the gas supplied into the processing tank 31.

  The water amount control unit 113 outputs a command signal to the water amount adjustment mechanism 32 according to the control signal from the central control device 111 and optimizes the flow rate of the water to be treated 4 supplied into the treatment tank 31.

  The tilt angle control unit 114 outputs a signal to the corresponding drive device 37 among the water treatment units 33a, 33b, 33c, and 33d in response to a control signal from the central control device 111, and the shower electrode 34 or the flat plate electrode 2 Optimize the tilt angle.

  A first pulse power source 118 is connected to the first water treatment unit 33a. A second pulse power source 119 is connected to the second water treatment unit 33b. A third pulse power supply 120 is connected to the third water treatment unit 33c. A fourth pulse power supply 121 is connected to the fourth water treatment unit 33d.

  The power control unit 115 outputs a signal for adjusting the power of the pulse power supply 118, 119, 120, 121 in accordance with the control signal from the central control device 111, and discharges the water treatment units 33a, 33b, 33c, 33d. Optimize power.

  In the fifth embodiment, four water treatment units 33a, 33b, 33c, and 33d are used, but the number of water treatment units depends on the dimensions of the treatment tank 31 or the required water treatment capacity. Can be set as appropriate.

  Further, as the water amount adjusting mechanism 32, for example, a metering pump or a mass flow controller can be used, but the water amount adjusting mechanism 32 is not limited to these as long as the water amount can be arbitrarily adjusted.

  Furthermore, the configuration of each water treatment unit may be different from each other. For example, the inclination angle of the ground electrode, the distance between the discharge electrode and the ground electrode, the number of discharge electrodes, the type of discharge electrode, the shape of the discharge electrode, and the discharge power are not necessarily the same, and each water treatment unit It may be different between.

Furthermore, since the treatment of the water to be treated 4 proceeds as it progresses downstream, for example, the water treatment unit located on the downstream side has a steeper slope or lower discharge power, thereby reducing invalid power consumption. Can be suppressed.
In the fifth embodiment, the inclination angle of the shower electrode 34 and the plate electrode 2, the flow rate of the water 4 to be treated, and the discharge power can be adjusted. However, only one or two of these can be adjusted. It may be possible.

Further, in the fifth embodiment, all the ground electrodes of the water treatment units 33a, 33b, and 33c except the lowermost water treatment unit 33d are the shower electrodes 34. The plate electrode 2 may be used. In that case, no weir 35 is provided at the end of the plate electrode 2 located in the middle stage.
Furthermore, the shower plate 12 of the fifth embodiment can be omitted.

Further, in the first to fifth embodiments, the pulse power source is used for the discharge formation. However, the pulse power source is not necessarily required as long as the discharge can be stably formed. For example, an AC power source or a DC power source may be used.
Furthermore, the polarity of the voltage output from the pulse power supply, the voltage peak value, the repetition frequency, the pulse width, and the like can be appropriately determined according to various conditions such as the electrode structure and the gas type. In general, the voltage peak value is desirably 1 kV to 50 kV. This is because a stable discharge is not formed at 1 kV or less, and the cost increases remarkably due to an increase in the size of the power source and difficulty in electrical insulation in order to achieve 50 kV or more.

  The repetition frequency is preferably 10 pps (pulse-per-second) to 100 kpps. This is because, if it is 10 pps or less, a very high voltage is required to supply sufficient discharge power. Conversely, if it is 100 kpps or more, the effect of water treatment is saturated and the power efficiency is lowered. Further, the voltage, pulse width, and pulse repetition frequency may be adjusted according to at least one of the flow rate of the water to be treated 4 and the composition of the substance to be treated.

Further, the plate electrode can be made of a conductive material. In particular, it is desirable to use a metal material having excellent corrosion resistance such as stainless steel or titanium.
Furthermore, the upper surface of the plate electrode can be covered with a dielectric such as glass or ceramic. Thereby, effects such as suppression of corrosion, suppression of arc discharge, suppression of occurrence of metal contamination, and the like can be obtained.

  Moreover, although it is desirable to use a metal material excellent in corrosion resistance, such as stainless steel or titanium, for the discharge electrode, other conductive materials can be used. Further, the surface of the discharge electrode may be covered with a dielectric such as glass or ceramic.

  Furthermore, in Embodiment 1-5, although wire electrode 6a, 6b, 6c was used as a discharge electrode, a discharge electrode does not necessarily need to be wire shape. As the discharge electrode, for example, a needle, mesh, punching metal, or the like can be used. However, in order to form a stable discharge at a relatively low voltage, it is preferable to use a wire, needle, or mesh that causes electric field concentration rather than a plate.

  12 to 14 are perspective views showing first to third modifications of the discharge electrode. FIG. 12 shows a discharge electrode 41 made of a rod having a wedge-shaped cross section. In such a discharge electrode 41, the electric field strength can be increased with a sharp wedge tip.

  FIG. 13 shows a discharge electrode 42 formed by joining a plurality of needle-like metal wires 42a at right angles to a linear electrode body 42a made of a wire or a rod. In such a discharge electrode 42, the electric field strength can be increased by the needle tip of the metal wire 42b.

  Further, FIG. 14 shows a discharge electrode 43 made of a punching metal plate provided with a plurality of punch holes 43a. In such a discharge electrode 43, the electric field strength can be increased by the punch hole 43a.

  In the first to fifth embodiments, oxygen gas is supplied to make the inside of the processing tanks 1 and 31 have a high oxygen concentration (pure oxygen) atmosphere. However, the gas type is not limited to oxygen. If it is in the gas containing oxygen, since the reaction of the above-mentioned formulas (1) to (5) occurs, water treatment can be performed. For example, any of air, nitrogen, and rare gas can be mixed with oxygen at an arbitrary ratio. The mixing ratio may be about 1% to 30% of the additive gas. When the addition rate exceeds 30%, the processing capacity is greatly reduced. In particular, if a rare gas is used, a discharge can be stably formed even at a relatively low voltage, and if air is used, the gas cost can be greatly reduced.

  Furthermore, the flow rate of the supplied gas does not need to be constant, and can be appropriately adjusted according to the characteristics of the water to be treated or discharge conditions. For example, when the concentration of organic matter in the water to be treated is high, a large amount of oxygen is consumed in the oxidative decomposition process, so it is preferable to increase the flow rate of the supply gas. On the other hand, when the organic substance concentration in the water to be treated is low, the ozone concentration in the gas is increased by reducing the flow rate of the supply gas, and the reaction can be accelerated.

  Furthermore, it is possible to increase the gas flow rate at the time of starting the apparatus and replace the internal air in a short time, and then reduce the gas flow rate to an amount necessary and sufficient for water treatment. Thereby, the usage-amount of gas is suppressed and a high-speed water treatment is attained.

Further, the gas exhausted from the gas discharge port may be circulated to the gas supply port. Thereby, the quantity of the gas supplied from a gas supply source can be reduced. In addition, O ₃ and H ₂ O ₂ generated by the discharge can be efficiently utilized by returning them to the treatment tank without exhausting them to the outside.

  Furthermore, the number of discharge electrodes can be appropriately changed according to the dimensions of the ground electrode, the characteristics of the water to be treated, the treatment flow rate, and the like.

  Furthermore, the distance between the discharge electrode and the ground electrode (interelectrode distance) is preferably between 1 mm and 50 mm. This is because if the distance between the electrodes is 1 mm or less, there is an increased possibility that the discharge electrodes will be submerged when the water to be treated is flowed. If the distance between the electrodes is 50 mm or more, a very high voltage is generated in the discharge formation. This is necessary.

  Further, the pressure in the treatment tank is preferably set to atmospheric pressure or the vicinity thereof so that supply and drainage of water to be treated can be easily performed, but can be positive pressure or negative pressure as necessary. When the inside of a processing tank is made into a positive pressure, mixing of the air from the outside is suppressed and it becomes easy to manage the atmosphere in a processing tank.

  Further, when the inside of the processing tank is set to a negative pressure, a discharge is formed at a relatively low voltage, and the power supply can be reduced in size and simplified. Furthermore, since the discharge is more likely to spread as the atmospheric pressure is lower, the water to be treated comes into contact with the discharge in a wide area, and the efficiency and speed of the water treatment are improved. In this case, the pressure is preferably in the range of 50 kPa to atmospheric pressure. Moreover, in order to set it as a negative pressure, it is necessary for a processing tank to have a pressure | voltage resistant structure and to provide a vacuum pump.

Furthermore, in this invention, a water droplet means the aggregate | assembly of the water molecule of the liquid state which exists in air | atmosphere, The particle size and number density are not specifically limited.
In the first to fourth embodiments, at least one of the inclination angle of the shower plate, the flow rate of the water to be treated, and the discharge power of the discharge may be adjustable as in the fifth embodiment.

    2 Flat electrode (ground electrode), 4 treated water, 4a water droplet, 6a, 6b, 6c wire electrode (discharge electrode), 12 shower plate, 12a hole, 12b, 12c protrusion, 14 barrier member, 33a first water Treatment unit, 33b second water treatment unit, 33c third water treatment unit, 33d fourth water treatment unit, 34 shower electrode (ground electrode, shower plate), 35 weir.

Claims (8)

A ground electrode, which is arranged inclined with respect to a horizontal plane,
A shower plate disposed above the ground electrode and provided with a plurality of holes, and allowing the supplied treated water to fall on the ground electrode as water droplets through the holes, and the ground electrode and the ground electrode A water treatment apparatus comprising a discharge electrode that is disposed between a shower plate and that forms a discharge with respect to the ground electrode.   The water treatment apparatus according to claim 1, wherein the shower plate is provided with a plurality of protrusions protruding downward from a peripheral edge of the hole.   The hole and the protrusion are formed by cutting out a part corresponding to the hole of the plate material constituting the shower plate, leaving a part, and bending the notched part in the drop direction of the water droplet. The water treatment apparatus according to claim 2.   4. The apparatus according to claim 1, further comprising a barrier member disposed below the shower plate, wherein the barrier member makes the water droplets fall on the ground electrode by making the water droplets fall upon the water droplets dropped from the shower plate. The water treatment apparatus of Claim 1. A plurality of water treatment units each having the ground electrode and the discharge electrode are arranged in the vertical direction,
In the water treatment unit adjacent vertically, the ground electrode is alternately inclined in the opposite direction with respect to the horizontal plane,
The water treatment according to any one of claims 1 to 4, wherein the ground electrode of at least a part of the water treatment unit is a shower electrode that also serves as the shower plate, and drops water to be treated as water droplets. apparatus.   The water treatment apparatus according to claim 5, wherein a dam that dams up the water to be treated is provided at the downstream end of the shower electrode.   The water treatment apparatus according to any one of claims 1 to 6, wherein at least one of an inclination angle of the shower plate, a flow rate of water to be treated, and a discharge power of the discharge is adjustable. .   Water to be treated supplied to a shower plate provided with a plurality of holes is dropped as water droplets through the holes on a ground electrode that is inclined with respect to a horizontal plane, and is disposed above the ground electrode. A water treatment method for forming a discharge between a discharged electrode and the ground electrode.

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