JP2013081916A - Water treatment apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water treatment apparatus using discharge generated between facing electrodes, which can improve water treatment ability with a compact and simple structure while suppressing power consumption.SOLUTION: The water treatment apparatus treats water to be treated by applying voltage between the facing electrodes 3, 4 and using discharge generated via bubbles 5 existing between the electrodes 3, 4 in a water treatment tank 1 having an inlet port and a discharge port of the water to be treated. The electrode 3 on the downstream side with respect to the flow of the bubbles 5 of the electrodes 3, 4 has a shape having at least one or more through-holes 2. The electrode 3 has a movable mechanism 9. When the bubbles 5 pass through the electrode 3, the electrode 3 is moved to micronize the bubbles 5 for efficiently interacting with the water and an organic substance and microorganism in the water before disappearance of active species. Consequently, an effect capable of improving the water treatment ability is obtained.

Description

  The present invention is a water treatment device that uses a discharge generated between electrodes facing each other, particularly, tap water, well water, river water, drinking water, sewage, industrial water, industrial wastewater, a pool, a public bath The present invention relates to a water treatment apparatus for treating water to be treated by decomposing organic substances or sterilizing microorganisms contained in water (water to be treated) used in hot springs.

  Conventionally, as a water treatment apparatus using discharge generated between opposed electrodes, air bubbles are introduced or generated between electrodes disposed in the water to be treated, and discharge is performed between the electrodes. What performs a process is known (for example, refer patent document 1).

  Japanese Patent Application Laid-Open No. H10-228688 describes a device that allows the treatment to be performed efficiently by mixing the water to be treated and the active species generated by the discharge by the high-pressure spray device after the discharge treatment.

JP 2009-034583 A

  However, since such a conventional water treatment device has a discharge device and a mixing device, the entire treatment device becomes large.

  In addition, since the active species have a short lifetime and is less than 1 millisecond for hydroxy radicals, there is a problem that the active species generated by the discharge device disappear before reaching the mixing device.

  Therefore, the present invention solves the above-described conventional problems, and when bubbles pass through the electrodes, the electrodes move, so that the bubbles stay between the electrodes due to the effect of covering the outlet. The power consumption can be suppressed by discharging in a state close to vapor phase discharge. Further, the bubbles can be made fine by bubble shearing by the opening of the electrode and cavitation occurring on the electrode surface. In addition, by integrating the discharge part and the mixing part by bubble miniaturization, a compact and simple configuration is possible, and the active species disappears in the electrode opening by minimizing the bubble at the downstream electrode entrance. It can efficiently interact with organic substances and microorganisms in the water before. Water treatment equipment that can efficiently interact with organic substances and microorganisms in the water before the disappearance of active species can be achieved by making the bubbles finer at the outlet of the electrode downstream of the bubbles. The purpose is to provide.

  In order to achieve this object, the present invention applies a voltage between the electrodes facing each other in a water treatment tank having an inlet and an outlet for water to be treated, and eliminates bubbles existing between the electrodes. A water treatment apparatus that treats water to be treated by using a discharge generated via a downstream electrode of the electrode with respect to a flow of bubbles, wherein the downstream electrode has a shape having at least one through hole. Has a movable mechanism, and is characterized in that when the bubble passes through the electrode, the electrode is moved to make the bubble finer, thereby achieving the intended purpose.

  According to the present invention, in a water treatment tank having an inflow port and an outflow port of water to be treated, a voltage is applied between the opposed electrodes, and a discharge generated through bubbles existing between the electrodes is utilized. A water treatment apparatus for treating water to be treated, wherein the downstream electrode of the electrode has a shape having at least one through hole with respect to the flow of bubbles, and the electrode has a movable mechanism, When the air bubbles pass through the electrodes, the electrodes move, so that the air bubbles stay between the electrodes due to the effect of being covered, and it is possible to save power by discharging in a state close to gas phase discharge. Can be.

  In addition, by integrating the discharge part and the mixing part by bubble miniaturization, a compact and simple configuration is possible, and the active species disappears in the electrode opening by minimizing the bubble at the downstream electrode entrance. It can efficiently interact with organic substances and microorganisms in the water before. Also, by making the bubbles finer even at the outlet of the downstream electrode with respect to the bubbles, it becomes possible to efficiently interact with organic substances and microorganisms in the water before the disappearance of the active species, and it is possible to improve the water treatment capacity. Can be obtained.

The schematic block diagram of the electrode part in the water treatment apparatus of Embodiment 1 of this invention Detailed view of electrode section in embodiment 1 of the present invention Detailed view of electrode section in embodiment 1 of the present invention Detailed view of electrode section in embodiment 2 of the present invention Detailed view of electrode section in embodiment 2 of the present invention

  The water treatment device according to claim 1 of the present invention applies a voltage between opposed electrodes in a water treatment tank having an inlet and an outlet of water to be treated, and through bubbles existing between the electrodes. A water treatment apparatus that treats water to be treated by using a discharge generated in such a manner that a downstream electrode of the electrode has a shape having at least one through hole with respect to a flow of bubbles, It has a movable mechanism, and when the bubble passes through the electrode, the bubble is made fine by moving the electrode. As a result, bubbles are retained due to the effect of being covered by the movement of the downstream electrode with respect to the flow of bubbles, and a gas-phase discharge-like discharge is formed between the electrodes, thereby enabling power-saving discharge compared to underwater discharge. become. Further, the bubbles can be made fine by bubble shearing by the opening of the electrode and cavitation occurring on the electrode surface. In addition, by integrating the discharge part and the mixing part by bubble miniaturization, a compact and simple configuration is possible, and the active species disappears in the electrode opening by minimizing the bubble at the downstream electrode entrance. It can efficiently interact with organic substances and microorganisms in the water before. Also, by making the bubbles finer even at the outlet of the downstream electrode with respect to the bubbles, it becomes possible to efficiently interact with organic substances and microorganisms in the water before the disappearance of the active species, and it is possible to improve the water treatment capacity. Can be obtained.

  The movable mechanism may be a rotating mechanism. As a result, bubbles are retained due to the effect of being covered by the movement of the downstream electrode with respect to the flow of bubbles, and a gas-phase discharge-like discharge is formed between the electrodes, thereby enabling power-saving discharge compared to underwater discharge. become. In addition to bubble miniaturization in which the opening of the electrode shears the bubble, it is also possible to miniaturize the bubble by cavitation due to a sudden change in atmospheric pressure near the rotating surface, increasing the surface area of the gas-liquid interface and reducing the ascent rate. As a result, the interaction time increases, and the water treatment capacity can be increased in efficiency.

  The movable mechanism may be a vibration mechanism. As a result, bubbles are retained due to the effect of being covered by the movement of the downstream electrode with respect to the flow of bubbles, and a gas-phase discharge-like discharge is formed between the electrodes, thereby enabling power-saving discharge compared to underwater discharge. become. In addition to bubble miniaturization in which the opening of the electrode shears the bubble, it is also possible to miniaturize the bubble by cavitation due to a sudden change in atmospheric pressure near the rotating surface, increasing the surface area of the gas-liquid interface and reducing the ascent rate. As a result, the interaction time increases, and the water treatment capacity can be increased in efficiency. In addition, it is sufficient that the opening part reciprocates at least 1/2 for shearing the bubbles. Since all the openings are sheared under the same conditions, uniform fine bubbles can be generated, and the efficiency of water treatment can be increased. There is an effect.

  The voltage applied to the electrode may be a pulse voltage. As a result, a high voltage can be applied in a short time, and plasma can be generated with low power. In addition, since the application is stopped before the generated plasma is transferred to arc discharge in which heat is almost lost and energy is lost, there is an effect that active species generation and water treatment with reduced energy loss can be achieved.

  Moreover, it is good also as a structure by which the surface of either one of the said electrodes is coated with the dielectric material. As a result, it is possible to prevent a large current from flowing all at once due to arc discharge and damage the electric system, and it is possible to stably form plasma discharge. Furthermore, since the conductor portion of the electrode is not consumed by discharge, there is an effect that the life of the electrode is prolonged and there is no change in the component of the water to be treated accompanying the elution of the conductor material. Furthermore, since a short circuit between the electrodes can be prevented, there is an effect that the distance between the electrodes can be set as small as possible so that the applied voltage and the power consumption are reduced.

  A power source for discharging from the electrode; a movable mechanism for moving the electrode; and a control unit for controlling the power source and the movable mechanism. The control unit controls a discharge cycle and a cycle of the movable mechanism. May be synchronized. Thereby, there is an effect that wasteful power consumption can be reduced by synchronizing so as to suppress the supply of voltage when the electrode and the opening face each other.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The water treatment tank 1 shown in FIG. 1 has a cylindrical shape, and two electrodes having through holes 2 in the water treatment tank 1 are opposed to each other so as to satisfy the cross-sectional area of the flow path perpendicular to the water flow. And arrange it. The bubbles 5 introduced into the water treatment tank 1 are generated by a porous body 6 and an air pump 7 which are bubble supply means. The bubbles 5 are supplied from the lower part of the electrode 4 to the flow path in the water treatment tank 1 together with the water to be treated, with the flow of water from the bottom to the top.

  The electrodes 3 and 4 are electrically connected to the high voltage power supply 8 and are configured to be able to apply a high voltage pulse between the electrodes, and discharge to the supplied water to be treated and the bubbles 5. Active species such as ozone and hydroxy radicals are generated by the discharge.

  The electrode 3 is connected to the movable mechanism 9, and by moving the electrode 3, the bubble 5 passing through the opening 10 is sheared and the bubble is refined by cavitation occurring on the rotating surface.

  The refined bubbles 5 are treated with water by interacting with organic substances and microorganisms in the water.

  The bubbles 5 have a flow of water from bottom to top, and are supplied from the lower part of the electrode 4 to the flow path in the water treatment tank 1 together with the water to be treated. Since it is made uniform with no bias, the discharge between the electrodes is also performed uniformly.

  Furthermore, as the raw material for the bubbles 5, air in the atmosphere, high-purity oxygen, ozone, or the like can be used, but high-purity oxygen or ozone is preferable.

  FIG. 2 shows a detailed view of the electrode section when the movable mechanism 9 is a rotating mechanism.

  In FIG. 2, the gas-liquid mixture containing bubbles 5 in the water to be treated is introduced between the electrodes after colliding with the electrodes 4, and discharge is performed between the electrodes.

  The electrodes 3 and 4 are formed by coating the inner conductors 3a and 4a with dielectrics 3b and 4b. By this dielectric coating, it is possible to prevent a large current from flowing suddenly due to arc discharge between the electrodes and destroy the power supply circuit and the like, and plasma can be stably formed. Further, since the conductors 3a and 4a are not consumed by the discharge, the life of the electrodes can be expected, and there is no change in the components of the water to be treated due to the elution of the metal material of the conductors 3a and 4a. In addition, since the electrodes can be prevented from being short-circuited, the distance between the electrodes can be set as small as possible so that the applied voltage and the power consumption are reduced.

  Regarding the dielectrics 3b and 4b, the coating method is preferably a method of forming an inorganic oxide film by a sol-gel method, and the material can be SiO2, Al2O3, MgO, ZrO2, TiO2, ZnO, Y2O3, BaTiO2, etc. From the viewpoint of dielectric constant and the like, BaTiO2, Al2O3, and TiO2 are preferable.

  The conductors 3a and 4a need to be made of a material that can withstand oxidation by the water to be circulated, oxidation due to discharge, and deterioration due to high temperature. For example, metals such as stainless steel, titanium, aluminum, copper, and copper alloys can be used, and stainless steel and titanium are preferable.

  The distance between the electrodes should be as small as possible for the purpose of reducing the applied voltage and power consumption, and should be increased for the purpose of increasing the discharge area. It is necessary to determine in advance the concentration and degradability of organic compounds and microorganisms, and to set an optimal interelectrode distance, preferably 0.05 to 50 mm. According to Paschen's law, the distance between the electrodes at which the applied voltage is minimum is several μm to several tens of μm. However, if it is smaller than 0.05 mm, the discharge area becomes smaller, and the flow rate capable of water treatment decreases. Depending on the components contained in the water to be treated, the frequency of clogging between the electrodes increases. On the other hand, if the distance between the electrodes is larger than 50 mm, the applied voltage required for the discharge becomes about 100 kV or more, and the high voltage power supply 8 becomes large and expensive.

  FIG. 3 shows a detailed view of the electrode when the electrode is rotated.

  The flow of the bubbles 5 is indicated by arrows.

  The bubble 5 passes through the opening 10 of the electrode 4, and when the opening 10 of the electrode 3 does not face the opening 10 of the electrode 4 due to rotation, the bubble 5 collides with the electrode surface of the electrode 3 and stays there. When the bubbles 5 stay, they are discharged and active species such as ozone and hydroxy radicals are generated. Thereafter, when passing through the opening 10 of the electrode 3, it is sheared and refined at the end face of the opening 10. The bubbles 5 are also made finer by cavitation occurring on the rotating surface. The refined bubbles 5 are treated with water by interacting with organic substances and microorganisms in the water.

  By retaining the bubbles 5 between the electrodes, it is possible to discharge at a lower voltage than when the bubbles 5 are not present between the electrodes or when the small bubbles 5 are present, and power consumption is suppressed.

  The lower limit of the appropriate rotation frequency is calculated as follows:

If the maximum bubble diameter is set to the diameter d of the opening 10, the terminal velocity v _b of the rising speed of the bubble 5 can be written as Equation 1 from the Stokes equation.

ρ _b is the density of the bubbles 5, ρ is the density of the liquid, g is the acceleration of gravity, and μ is the viscosity of the liquid.

When the terminal velocity v _b of the bubble 5 is faster than the flow velocity v _w , the time t _b required for the bubble 5 to pass through the inlet and outlet end faces of the electrode opening 10 is the time required to move by the bubble diameter d. It becomes.

Given the opening 10 such as to be in contact with the center electrode 3, the bubble 5 is sheared by at least once, the opening 10 the end face of the electrode, in time t _b, expressed in Equation 2, the openings 10 1 / 2 rotations may be performed. That is, since it takes time t _b to make 1/2 rotation, the rotation frequency f _rb is expressed by Equation 3 by dividing 1/2 by time t _b .

In the opening 10 away from the center, the rotation angle required for the bubble 5 to be sheared at least once by the end face of the opening 10 of the electrode becomes small, and therefore the rotation frequency decreases. Therefore, if f _rb is set to the lower limit value, the condition of shearing other than the opening 10 that naturally contacts the center is satisfied.

  There are various bubble sizes, but if the diameter is smaller than Equation 3, the terminal speed becomes slow and the frequency becomes low. Therefore, a safe value can be taken by considering the maximum diameter.

  Since there is a rotation axis at the center of the electrode 3, the opening 10 cannot exist at the center of the electrode 3, and strictly speaking, the opening 10 that touches the center cannot exist, but it is calculated as a safe value.

Terminal velocity v _b of the bubble 5 is formula 4 as the rotation frequency f _rw when slower than the flow velocity v _w is was replaced with v _w.

  The upper limit rotational frequency is 2000 Hz in view of rotational stability, heat generation, and the like.

  By forming fine bubbles, the surface area of the gas-liquid interface increases, the probability of contact with organic matter and microorganisms in the water to be treated increases, and the ascent rate decreases, resulting in a longer interaction time and highly efficient treatment. Water organic matter is decomposed and microorganisms are sterilized.

  The voltage waveform applied between the electrodes may be a high voltage rectangular wave, triangular wave, sine wave, or the like, and preferably a high voltage pulse. By using a high voltage pulse, a high voltage can be applied in a short time, and plasma can be generated with low power. Further, since the application is stopped before the generated plasma is transferred to the arc discharge where the generated plasma becomes almost heat and loses energy, energy loss can be suppressed.

  The magnitude of the voltage applied by the high-voltage power supply 8 varies depending on the shape and size of the electrode, the object to be processed, and the required processing capacity. Considering efficiency, it is preferably 1 to 100 kV.

  As a control method of the high voltage power supply 8, according to the output signal of the turbidity sensor, conductivity sensor, flow rate sensor arranged in any one of the upstream side and downstream side of the electrode part, In synchronization, the ON / OFF time of the applied voltage, the width of the high voltage pulse, and the magnitude of the applied voltage may be adjusted. Thereby, since optimal discharge is performed in accordance with the required processing capacity, it is possible to suppress wasteful power consumption.

  According to such a configuration, it is easy to retain the bubbles 5 between the electrodes, discharge is performed in a wide range between the electrodes, and when there are no bubbles 5 between the electrodes or when there are small bubbles Since discharge can be performed at a voltage lower than that, an effect of suppressing power consumption can be obtained. Moreover, the bubble 5 can be refined | miniaturized by the bubble shear by the opening part 10 of an electrode, and the cavitation which arises on an electrode surface.

  In addition, since the electrode and the fine bubble generating unit are integrated, the water treatment apparatus can be reduced in size, and the bubbles can be refined at the entrance of the electrode 3 on the downstream side with respect to the bubbles 5, so Can interact efficiently with organic matter and microorganisms. Further, by making the bubbles finer at the outlet of the downstream electrode 3 with respect to the bubbles 5, it becomes possible to efficiently interact with organic substances and microorganisms in the water before the disappearance of the active species in the electrode openings, thereby improving the water treatment capacity. The effect is obtained.

  The diameter of the bubble 5 at the time of discharge is the same as the distance between electrodes of 0.05 to 50 mm, whereas the diameter of the refined bubble 5 is 0.05 to 0.01 mm. The effect of improving water treatment capability such as decomposition of organic matter and sterilization of microorganisms can be obtained.

  For example, assuming that the active species has a lifetime of 1 millisecond, when the electrode thickness is 0.5 mm and the opening 10 is 1 mm, bubbles can be made fine at the outlet of the electrode 3 before disappearance of the active species. It becomes possible to interact, and the water treatment capacity can be improved. This condition is an example, and the same effect can be obtained as long as the bubble can be refined before the active species disappear.

  Moreover, although the introduction part of the bubble 5 was made into the front | former stage of an electrode part, you may supply between electrodes directly.

  Further, instead of the air pump 7, a gas cylinder in which compressed gas is sealed may be used, and there is no difference in operation and effect.

  Moreover, although it was set as the structure which has arrange | positioned several electrodes facing each other, you may make it the structure which piled up these electrode pairs. Thereby, since a process flow rate can be increased, the efficiency improvement of water treatment performance can be achieved.

  Further, in this embodiment, the opening 10 is provided for both of the two electrodes, but the electrode 4 may not have the opening 10. In this case, between the electrodes 3 and 4 facing each other, the water to be treated and the bubbles 5 are supplied in a flow parallel to the electrodes 3 and 4 and are discharged. Then, it is discharged from the opening 10 of the electrode 3. The bubbles 5 are refined by the movable electrode 3 at this time, and the bubbles are refined at the entrance of the electrode 3 on the downstream side of the bubbles 5, so that the organic substances and microorganisms in the water and the efficiency are reduced before the active species disappear in the electrode openings. Can interact well. Further, by making the bubbles finer at the outlet of the downstream electrode 3 with respect to the bubbles 5, it becomes possible to efficiently interact with organic substances and microorganisms in the water before the disappearance of the active species, and the effect of improving the water treatment capability is obtained. It is done.

(Embodiment 2)
4, the same components as those in FIGS. 1, 2, and 3 are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 4 shows a detailed view of the electrode section when the movable mechanism 9 is a vibration mechanism.

  In FIG. 4, the difference between FIG. 2 of Embodiment 1 and FIG. 2 is that the electrode 3 is separated from the wall surface by a diameter d of the opening 10 or more, and the other configuration is the same as FIG.

  FIG. 5 shows a detailed view of the electrode showing the flow of the bubbles 5 when the electrode vibrates.

  The bubble 5 passes through the opening 10 of the electrode 4, and when the opening 10 of the electrode 3 does not face the opening 10 of the electrode 4 due to vibration, the bubble 5 collides with the electrode surface of the electrode 3 and stays there. When the bubbles 5 stay, they are discharged and active species such as ozone and hydroxy radicals are generated. Thereafter, when passing through the opening 10 of the electrode 3, it is sheared and refined at the end face of the opening 10. The bubbles 5 are also made finer by cavitation occurring on the vibration surface.

  By retaining the bubbles 5 between the electrodes, it is possible to discharge at a lower voltage than when the bubbles 5 are not present between the electrodes or when the small bubbles 5 are present, and power consumption is suppressed.

  According to such a configuration, since the same shearing condition is applied to all the openings 10, an effect that uniform fine bubbles can be obtained can be obtained.

  Further, there is no need for the movable mechanism 9 to be connected at the center of the electrode 3, and the effect of increasing the degree of freedom of design can be obtained.

  The appropriate vibration frequency is calculated as follows:

The terminal velocity v _b of the rising speed of the bubbles 5 is the same as that in the formula 1. When the terminal velocity v _b of the bubble 5 is higher than the flow velocity v _w , the time t _b required for the bubble 5 to pass through the inlet and outlet end faces of the electrode opening 10 is the same as that in Equation 2.

In order for the bubble 5 to be sheared at least once by the end face of the opening 10 of the electrode, the opening 10 has only to be moved by the diameter d of the opening 10 or more within the time t _b expressed by Equation 2. In other words, it may be a vibration that reciprocates 1/2 with an amplitude of d / 2 or more. Since this takes time t _{b in a} ½ cycle, the vibration frequency f _bb is given by Equation 5 by dividing ½ by time t _b .

When the terminal velocity v _b of the bubble 5 is slower than the flow velocity v _w , Equation 6 is obtained as the vibration frequency f _bw replaced by v _w .

  These are the frequencies necessary for shearing the bubbles 5 at least once, and the size of the bubbles 5 is the same as that described in the first embodiment, and this frequency is the lower limit value.

  The upper limit vibration frequency is 2000 Hz in view of vibration stability and generation of heat.

  In the second embodiment, the shape of the water treatment tank 1 is a cylindrical shape. However, in the second embodiment in which the movable mechanism is a vibration mechanism, it may be a rectangular tube having a polygonal channel cross section. 3 and the wall surface of the water treatment tank 1 are separated from the wall surface of the water treatment tank 1 by at least the diameter d of the opening 10, there is no difference in the effect.

  The water treatment device according to the present invention has a simple configuration and is capable of improving the water treatment capacity while suppressing power consumption. Tap water, drinking water, sewage, industrial water, industrial It is useful as a water treatment device for treating water to be treated by decomposing organic substances contained in water (water to be treated) used for sewage, pools, public baths, hot springs, etc. or sterilizing microorganisms.

DESCRIPTION OF SYMBOLS 1 Water treatment tank 2 Through-hole 3 Electrode 3a Conductor 3b Dielectric 4 Electrode 4a Conductor 4b Dielectric 5 Bubble 6 Porous 7 Air pump 8 High voltage power supply 9 Movable mechanism 10 Opening

Claims (6)

In a water treatment tank having an inlet and an outlet for water to be treated, a voltage is applied between the electrodes facing each other, and the water to be treated is treated by using a discharge generated through bubbles existing between the electrodes. A water treatment device that performs
The downstream electrode of the electrode with respect to the flow of bubbles has a shape having at least one through hole,
The said electrode has a movable mechanism, and when a bubble passes through the inside of the said electrode, a bubble is refined | miniaturized by moving the said electrode. The water treatment apparatus according to claim 1, wherein the movable mechanism is a rotation mechanism. The water treatment apparatus according to claim 1, wherein the movable mechanism is a vibration mechanism. The water treatment apparatus according to claim 1, wherein the voltage applied between the electrodes is a pulse voltage. 5. The water treatment apparatus according to claim 1, wherein a surface of one of the electrodes is coated with a dielectric. 6. A power source for discharging from the electrode;
A movable mechanism for moving the electrode;
Control means for controlling the power source and the movable mechanism;
The water treatment apparatus according to any one of claims 1 to 5, wherein a period in which a voltage is applied by the control means and a period in which the movable mechanism is moved are synchronized.

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