JP4429451B2 - Water purification equipment containing dissolved organic matter and trace amounts of harmful substances - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a purification method and apparatus for methane fermentation digestive fluid, domestic wastewater, sewage, clean water, aquaculture pond water, activated sludge wastewater, food industry wastewater, and the like.
[0002]
[Prior art]
As a method for generating oxygen radicals and hydroxy radicals, there are ozone delivery, ultrasonic irradiation and electromagnetic ultrasonic irradiation. In addition, a method using a photocatalytic reaction between ozone and titanium has been developed. However, the amount of radicals generated is small for a large input power, the decomposition efficiency of harmful substances is low, and the apparatus cost is also high. Ozone is effective in seawater rich in bromine and manganese, but not in fresh water.
[0003]
Further, the combined use of transition metals such as cobalt and manganese and hydrogen peroxide has attracted attention. This method is known to have higher radical generation efficiency than ozone, but it is difficult to handle because hydrogen peroxide has a variability to living organisms and is prohibited from being used for food addition. The final treatment of hydrogen peroxide at the outlet is necessary.
[0004]
In the photocatalytic method, when electrons enter a cavity existing on the surface of a material composed of fine particles such as titanium oxide, tin oxide, rubidium oxide, and platinum, oxygen radicals and hydroxyl radicals may be generated with a lifetime of 10 μs to 100 μs. It is known (see the specification of Japanese Patent Application No. 11-68862, hereinafter referred to as the prior application specification). This radical is known to oxidatively decompose organic substances and aromatic persistent substances including carbon sources and nitrogen sources contained in water.
[0005]
In the specification of the prior application, in order to efficiently generate oxygen radicals and hydroxy radicals generated on the surface of the metal oxide and sustain them for a longer time, there are specific conditions for the electric field applied between the electrodes, and waste water and metal. It is necessary to lengthen the contact time with the oxide surface, and when there is a large amount of suspended suspension in the drainage, it is necessary to clean the electrode surface by ultrasonic transmission, and It has been shown that voltage, current, and electric field frequency depend on the movement of electrons on the metal oxide surface or metal surface.
[0006]
[Problems to be solved by the invention]
In the invention described in the specification of the prior application, the generation of superoxide radicals is insufficient in the high frequency range and becomes excessive in the low frequency range, and the current is unstable in wastewater treatment containing a large amount of ions. There are problems, and in terms of power consumption, the establishment of a treatment method for the combination of low frequency-low current, high frequency-minute current, and stabilization of voltage pulse application when the electrical resistance of raw water changes during treatment There was a problem.
[0007]
[Means for Solving the Problems]
  In order to solve the above problems, the present inventionCeramic oxides mainly composed of feldspar and silicon or titanium, iron, stainless steel, titanium oxide, cobalt oxide, tin oxide, iridium oxide, nickel oxide, iron oxide or vanadium oxide fine particles or titanium, cobalt, nickel, silver, gold A positive electrode comprising the metal oxide or metal or a mixture thereof obtained by applying a liquid in which the same kind of metal salt solution is mixed to the metal fine particles or a mixture thereof and then drying and sintering in a temperature range of 500 ° C. to 1500 ° C. An electrode and a radical generator disposed so as to face each other and a cathode made of platinum, titanium, or stainless steel, and waste water is allowed to flow continuously between both electrodes of the facing electrode, Organic substances dissolved in water and their intermediates by generating a radical by partial decomposition of water by pulse discharge under conditions of voltage, current and frequency In addition to oxidizing and reductively decomposing the product, the positive electrode is coated with fine metal wires of platinum or gold in a 2 mm to 100 mm interval when a metal oxide is applied and sintered. A positive electrode terminal made of titanium, copper, and stainless steel is connected to the end line of the mesh-like metal so as to be buried in the surface of the oxide, and positive voltage led from the power source is surely connected to the positive electrode terminal It was decided to be added.
[0008]
  The invention of claim 2An electrode on which a porous ceramic film having a thickness of 10 μm to 1 mm or a fluororesin film having a thickness of 0.1 to 100 μm, a hard polyethylene film, or a fluorine resin film is deposited or applied on the cathode side facing the positive electrode is disposed. It is characterized by oxidizing and reductive decomposition of organic matter and its intermediate products in wastewater by stable radical generation,
  Claim3According to the present invention, the positive electrode has a cylindrical or truncated cone structure with a total apex angle of 5 ° to 40 ° with respect to the center line, and the inner side surface and the outer side surface of the cylinder are the metal oxide powder and the same metal as this. It consists of a metal surface coated and sintered with powder or a mixture of these and the same metal salt, and a round or square bar cathode made of platinum, titanium, stainless steel at the center of the cylindrical truncated cone. Further, the outside of the cylindrical truncated cone is sealed with an outer casing made of a metal container such as titanium or stainless steel, and the outer casing is disposed at an inlet, an outlet, and a generated gas outlet to constitute a cathode. In addition, the inner side surface and the outer side surface of the cylindrical truncated cone are used as radical generating parts, and organic waste water is fed from the large diameter part inside the cylindrical truncated cone, exits to the small diameter part, and is again cylindrical. Flows in the opposite direction to the inner part , Characterized by having a structure that oxidizes and reduces wastewater by the generated radicals,
  Claim4According to the present invention, the positive electrode is a flat plate inclined at an angle of 2.5 ° to 20 ° with respect to the vertical plane, and two flat plates positioned perpendicular to the thickness direction of the flat plate are the metal oxide powder or metal A mixed liquid composed of powder or a mixture thereof and the same metal salt is applied to both sides and composed of a sintered metal surface, and two of them are used so that the metal surface is symmetrical with respect to the surface. The side surfaces of the flat plate that are not metal oxide surfaces are joined with titanium, stainless steel, or a flat plate having the same metal surface on one side, and the anode voltage is made uniform to form a pyramid, and the metal surface that is the center of the pyramid Titanium plate, stainless steel plate, cathode electrode made of platinum wire net or platinum round bar and outer side of the pyramid are sealed with titanium and stainless steel containers in a plane-symmetrical position to form an outer container. Disposed at the inlet, outlet and generated gas outlet, cathode The inner surface and the outer surface of the two flat plates coated with metal oxide are used as radical generating parts, and organic waste water is fed from the inner diameter or length of the truncated pyramid, Or the wastewater that has come out in the small length part has a structure that oxidizes / reduces and decomposes organic substances and harmful substances contained by the generated radicals while it flows again in the opposite direction to the inner part of the truncated pyramid. As a feature,
  Claim5Is an outer casing made of stainless steel or titanium, in which two or more cylindrical truncated cones of the positive electrode are stacked, and cylindrical cathodes made of stainless steel or titanium are alternately arranged between the truncated cones. The outer casing is provided with a waste water inlet, outlet and gas outlet to form a cathode, and the waste water has a metal oxide surface as a positive electrode and stainless steel or titanium as a radical generating electrode. It is characterized by oxidizing and reductive decomposition treatment of organic substances and harmful substances contained in wastewater by radicals generated so that it can be placed on the cell structure,
  Claim6According to the present invention, the cylindrical pyramid on the positive electrode side is stacked in two or more stages, the cylindrical pyramid cathodes made of stainless steel or titanium are alternately arranged between the pyramids, and the outer container made of stainless steel or titanium The radical generating electrode having the outer casing sealed with a waste water inlet, outlet and gas outlet, constituting a cathode, a metal oxide surface as a positive electrode, stainless steel or titanium as a cathode. It is a water purification device characterized in that waste water is oxidized / reduced and decomposed by generated radicals, which can be disposed in a cell structure.
[0009]
  The invention of claim 7In the water purification device housed so that the gap at the uppermost edge of the electrode structure constituting the positive electrode and the cathode electrode is reduced by 10% to 30%, and this portion can be monitored for discharge. Arrangement of a fluorescence detector having a wavelength of 400 nm to 470 nm, and a hydrogen gas detector in the space immediately above the pipes or both electrodes to the discharge port of the generated gas, and the voltage is controlled by detecting fluorescence. The feedback of the signal to the oscillator is performed automatically or manually so that the current can be controlled by detecting the currentCharacterizeIt is a water purification device.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
First, the outline of the present invention will be described below.
The present inventor studied the invention of the specification of the prior application, and as a result of experimentally investigating the relationship between the frequency and the voltage with respect to the application of the pulse voltage with respect to the transition metal, stable electric field processing at both low and high frequencies. Are considered metals, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Rb, St, Zr, Ru, Sn, W, Ir, Pt, Au, Pb, Co and their oxides Found that is effective.
[0011]
In consideration of the fact that metal dissolution such as irrigation water and tap water must not occur and the durability of oxide salts, the types of metals are narrowed down. Furthermore, when these metals are examined in detail, the commonality is that they are transition metals and their oxides, and it has been found that the electron quasi-transfer of these atoms has a very strong correlation with radical generation. These metals and metal oxides were irradiated with electrons below the plasma discharge or corona discharge, and the size and chemical structure of the generated radicals were examined with an electron spin resonance apparatus using a radical scavenger. Hydroxyl radicals, superoxide radicals, It was confirmed that so-called active oxygen and free radicals such as diphenyl looper picryl hydrol were generated.
[0012]
Furthermore, as a result of examining the pulse wave from direct current to 50 MHz by using pure water and changing the voltage from 0.2 kV / cm to 20 kV / cm, the superoxide radical has a low voltage and low current (0.1 mA / cm) in direct current.²~ 100mA / cm²). This is consistent with the outstanding oxidative decomposition of ammonia and polyphenols in the low frequency range of 5 Hz to 10 kHz. In addition, when the relationship between the electron movement speed between the electrodes and the ion movement speed was calculated at 5 kHz to 50 MHz, it was found that no ion movement was caused by pulse irradiation of about 1 μs or less. It was found that application of pulse voltage is stable even in wastewater with conductivity. Especially in this region, the current density is 0.1 mA / cm.²-10 mA / cm²The hydroxyl radicals were dominant in the voltage range of 0.2 kV / cm to 20 kV / cm, and the amount of hydroxyl radicals tended to increase as the voltage increased.
[0013]
As for radical generation, H, which is called streamer discharge.₂Since the current suddenly drops in the region where gas is slightly generated, the optimum voltage of the electrode part can be selected according to the frequency from this voltage change, and stable electric field irradiation control technology was established.
DC voltage 10-80V, current density 0.1mA / cm²~ 100mA / cm²In the meantime, the generation of superoxide radicals of the above metals and their oxides was very stable. In ultrapure water, generation of radicals was observed at around 2.07 V or higher. However, when ordinary ions are included, a voltage of about 5 times or more is required, and it has been confirmed that it is necessary for operation to maintain a streamer discharge accompanied by a slight generation of hydrogen. Furthermore, this phenomenon was possible by selecting the voltage even at 5 Hz to 1 MHz, but it was necessary to maintain the pulse discharge interval about 5 to 20 times the ion movement speed, and the relationship between the pulse transmitter and the electrode was strictly designed. -Solved the need for calculation and manual operation and automatic control methods from the characteristics of streamer discharge.
[0014]
The selection of an appropriate pulse frequency requires consideration of the solubility of the positive electrode surface metal by pulses. When the above main metals are examined, there is some galvanic corrosion on the metal surface in the high voltage and high frequency range. Because there are conditions, the amount of metal elution differs between the metal oxide sintered on the surface of stainless steel and the one sintered on the ceramic surface. A positive electrode composed of a participating metal surface having a core as a core is useful. Ceramics refers to those made of nonmetallic inorganic materials in a broad sense, and includes, for example, glass.
[0015]
Embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 2 shows a cross-section when the positive electrode portion and the negative electrode portion of the electrode portions of the inventions of claims 1, 2, 3, and 4 are arranged to face each other. 2 in FIG. 2 is a positive electrode and has a groove indicated by 2 extending in the flowing water direction. The positive electrode 1 is made of titanium oxide, cobalt oxide, tin oxide, iridium oxide, nickel oxide, fine particles of iron oxide or vanadium oxide, or titanium on the surface of ceramic (non-metallic inorganic material including glass) mainly composed of feldspar or silicon. The metal oxide obtained by applying a liquid obtained by mixing the same kind of metal salt solution to metal fine particles of cobalt, nickel, silver, gold, or a mixture thereof, and sintering in a temperature range of 500 ° C. to 1500 ° C. after drying treatment Or a metal or a mixture thereof. The cathode portion 3 is made of platinum, titanium, or stainless steel.
[0016]
The positive electrode 1 and the cathode electrode 3 are disposed so as to face each other, and are structured so as to be wrapped by the external cell 4. In the water treatment, most of the pollutants in the treated water are surely sent by sending the treated water from the lower part (arrow) of the outer cell 4 to the upper part and setting the zenith angles of both opposing electrodes to 5 ° to 40 °. Contact the positive electrode. In the treated water, contaminants in the treated water are efficiently decomposed by radicals generated in the positive electrode part 1. In addition, radicals flowing out from the electrode part are also surely eliminated. Note that the wiring between the external cell and the positive power supply section is completely electrically insulated by insulators or polyethylene resin (not shown). The material of the outer cell 4 is preferably a polymer resin such as an acrylic resin or a polyethylene resin.
[0017]
The material of the external cell 4 can be the same metal as the material of the cathode 3, but the electrical insulation between the positive electrode part and the external cell must be complete, and the ground to earth must be perfect. I must.
[0018]
When a pulse wave or direct current electricity sent from the power supply device supplied to the electrode portions 1 and 3 is loaded on the electrode portion, a slight amount of hydrogen gas bubbles start to be generated on the surface of the cathode portion 3, and a slight amount of hydrogen gas is generated. Gas bubbles begin to rise. When the hydrogen gas is further raised from this state, a rapid current rise is observed as the voltage rises as shown in FIG. Furthermore, there is a voltage range in which the voltage drops rapidly when the voltage is raised. In the voltage region where this voltage drops, streamer discharge is observed and fluorescence is generated. At this time, radicals are generated most efficiently.
[0019]
FIG. 3 shows the reaction in a N, N′-dimethyl-P-nitrosoaniline (hereinafter referred to as RNO) solution for scavenging hydroxyl radicals as follows: absorbance at 10 kHz frequency and power × time / electrode area. The relationship shows the state of the reaction. The positive electrode metal is Ti, SnO₂, Al is an example when Ti is used as a cathode electrode. When Al was used as the positive electrode metal, a large amount of hydroxyl radicals appeared to be generated, but as shown in FIG. 4, it was considered that Al was eluted as aluminum hydroxide by hydroxy radicals as shown in FIG. Therefore, in the present invention, Al is not considered as the electrode material.
[0020]
As shown in FIG. 4, other metals have very little oxidation elution due to hydroxy radicals, and are useful as radical generating electrodes. In addition, for precipitation separation of phosphorus and suspended suspended particles, an aggregating precipitant mainly composed of Al and Fe ions can be used, and this is known in an electrolytic elution method in which a DC voltage is applied and has become publicly known. ing. It can be seen from this experimental example that the present invention is based on a completely different principle from this method.
[0021]
FIG. 5 shows the control of the generation of superoxide radicals using the radical scavenger DMPO when the current is controlled to 0.1 A at DC voltages of 400 V, 1000 V and 1500 V, and the positive electrode is Pt and the cathode is Ti or Pt. It is shown as a change, and it can be seen that the generation of superoxide radicals differs depending on the combination of metal materials and voltage.
In addition, using a DMPO radical scavenger, we investigated the tendency of superoxide radicals and hydroxy radicals to be predominantly generated by an electron spin resonance apparatus. When a DC voltage was applied to the transition metal electrode, superoxide radicals were generated. It was found that application of a pulse wave to the transition metal oxide electrode excelled in generating hydroxyl radicals.
[0022]
Therefore, when accelerating the decomposition of pollutants contained in water in an oxidized form, a DC voltage is applied to the former transition metal, and a pulse wave voltage is applied to the latter transition metal oxide when a reduced form is required. This purification method is effective. However, since it is necessary to adjust the electrical resistance when contaminated water is present between the positive electrode and the cathode, it is more effective to make an electrode from a mixture of oxide metal powder and metal powder. Either radical will dominate. Due to the characteristics of the electrodes, the superior electrodes of both radicals are combined in accordance with the characteristics of the polluted water.
[0023]
FIG. 6 shows the removal rate of total nitrogen when a voltage of 400 V is applied to the Ti—Ti electrode part of the polluted water for 30 minutes. It can be seen that ammonia and nitric acid are oxidized and removed. FIG. 15A shows the composition of the gas generated in the experiment of FIG. It can be seen from the gas composition that these substances are oxidized. FIG. 15 (a) shows that N is considered to be derived from nitrate nitrogen.₂O generation is also observed. In order to reduce this, it is necessary to induce the generation of reduced hydroxyl radicals. Therefore, when hydrogen peroxide was added to the polluted water, N₂O generation could be suppressed. When M is a metal as a symbol, the following reaction is promoted, hydroxyl radicals are derived from hydrogen peroxide, and N radicals are reduced by the reducing action of hydroxyl radicals.₂It is considered that the generation of O was suppressed.
[0024]
Reaction formula 1
M + N₂O₂→ M⁺+ ・ OH + OH^-
H₂O₂ + OH^- → HOO^- + H²O
M⁺ + HOO^- → M + HOO
[0025]
Next, stabilization of pulse discharge will be described. FIG. 7 shows a circuit diagram of an example of an embodiment of the present invention in the case of discharging by flowing ultrapure water between the electrodes. 7, 5 is a slidac, 6 is a high voltage transformer, 7 is a high voltage diode, 8 is a high voltage resistor, 9 is a charge / discharge capacitor, 10 is an electrode section, 11 is a high voltage probe, and 12 is a high voltage oscilloscope. Respectively. In the circuit of FIG. 7, a fairly stable discharge can be obtained even at a high voltage. However, in the case of removing contaminated water, brackish water or ammonia in seawater, the electrical conductivity of the target treated water changes during discharge, and a stable current cannot be obtained. If the voltage on the transmission circuit side is constant, the current varies depending on the electric conductivity of the polluted water and the electric conductivity of the metal oxide on the positive electrode side. Therefore, in the present invention, the electric conductivity on the positive electrode side can be adjusted to some extent and the current can be stabilized by mixing the metal oxide powder on the positive electrode side with the same metal powder. In addition, since the amount of radicals generated is affected by a change in electric current, this metal mixing method has a ratio restriction. For this reason, the conditions for stable streamer discharge are greatly affected by changes in the electrical conductivity of the polluted water.
[0026]
In order to stabilize the discharge, the present invention solved the problem by combining the following two points.
1) Selection of voltage application frequency
2) Control of the amount of emitted electrons on the negative electrode side
[0027]
The reason for selecting the voltage application frequency is the concept of controlling the amount of electrons in the relationship between the transmission characteristics on the transmitter side and the movement speed of ions in the polluted water. That is, the pulse rise and fall time delays are taken into account. This is affected by the magnitude and frequency of the output voltage. As a method of giving a pulse, there is a method of applying a voltage within 1 μs for limiting the movement of ions dissolved in water. In addition, the moving speed of electrons passing between the electrodes during the time when the next pulse comes 1 × 10⁷Calculated from m / s, the optimum voltage application and frequency are selected. FIG. 8 shows that when the pulse is 10 KV, the pulse pause time can be selected from 10 μs to 1 ms when calculated from the slew rate of the pulse generator (rise or fall time (V / μs)). At 1 MHz or higher and 10 KV-P or higher, a stable applied current controlled on the electric circuit side can be secured.
[0028]
However, at 1 MHz or less, the time at the top of the pulse wave is 1 μs or more, which promotes ion movement between the electrodes and changes the current (in actual contaminated water, this ion movement tends to increase). For this purpose, voltage control for making the amount of electrons transferred between electrodes constant is performed by a pulse transmission circuit, or the amount of electrons transferred between electrodes is masked. For this reason, as shown in the invention of claim 6, the discharge can be stabilized by sintering the porous ceramic film or coating the polymer resin film on the cathode side. In actual control, the current can be kept constant by gradually decreasing from a higher voltage to a lower voltage.
[0029]
In the high-pressure pulse discharge, when the discharge part is made longer than the flow of water in the electrode part as shown in FIG. 2, the discharge contact time of water is 15 to 30 minutes in this case. Accordingly, the electrical conductivity of water at the entrance and exit is increased, and even if the stability of discharge is observed, the discharge is insufficient or overdischarged. It is necessary to provide a voltage gradient on the positive electrode side so that the voltage at the entrance is high and the voltage near the exit is low. Therefore, when metal oxide is applied and sintered to ceramics, the electrical resistance of the metal oxide surface can be made relatively large, so the voltage on the metal oxide surface should be changed between the water inlet and outlet. In order to achieve this, it is only necessary to prevent voltage loss in the power supply section, so a 2 to 100 mm mesh platinum wire or gold wire net is attached to the surface of the metal oxide, and this is embedded in the surface of the metal oxide. Sintered in a heated state. The metal net terminal and power supply terminal are directly connected. The voltage gradient at the inlet and outlet reaches several tens of volts to several hundreds of volts, and the change in the electrical conductivity of the water to be treated is determined from the batch experiment.
[0030]
FIG. 9 shows the structure of a practical electrode part disclosed in the inventions of claims 7 and 8, wherein 13 is a raw water inlet, 14 is a positive electrode part, 15 is a cathode electrode part, 17 is a treated water outlet, 18 Indicates a product gas discharge port. The total apex angle is 5 for truncated cones and truncated pyramids.^o~ 40^oUntil was useful. 2.5-20 for the flat plate^oAnd any one of the flat plates can be used as a cathode to face the positive electrode. FIG. 10 is a cross-sectional view of a truncated pyramidal electrode part structure having a metal and a metal oxide as a positive electrode. Reference numeral 13 denotes a raw water inlet, 14 a positive electrode part, 15 a cathode electrode part, and 16 a mantle part. (Also used as a cathode), 17 is a treated water outlet, 18 is a generated gas discharge port, and 19 is an electrical insulator. A positive electrode 14 made of a metal and a metal oxide is placed in the jacket 16 of the metallic cathode 15, and a titanium plate, a platinum plate or a platinum rod is placed in the center, and this is connected to the jacket and a jacket electrode. If the doorway is attached, it becomes a water purification device.
[0031]
FIG. 11 shows a cell-shaped conical or truncated pyramid-shaped positive electrode disclosed in the inventions of claims 9 and 10 which are alternately stacked with cathode electrodes having the same shape, and the treated water passes through this in one pass. It has a structure that flows out, 13 is a raw water inlet, 14 is a positive electrode part, 15 is a cathode electrode part, 16 is a mantle part (also used as a cathode), 17 is a treated water outlet, and 18 is a generated gas discharge. Port. Depending on the wastewater, there is a restriction that the number of electrodes cannot be increased when the electrical conductivity between the inlet and the outlet changes extremely. Further, even in the case of one stage, the residence time on one side of the positive electrode may not be set to 15 minutes or more. Practically, it is necessary to adjust the voltage of the power generation unit so that the voltage of each electrode is different from each other in series or in parallel in one or more stages.
[0032]
FIG. 12 shows various treatment water and effluent treatment devices containing exogenous endocrine disrupting chemicals, 20 is a stirrer, 21 is a raw water tank, 22 is a hydrogen peroxide tank, and 23 is a metering pump (P₁), 24 is a water pump (P₂), 25 is an electric field treatment device, 26 is a sedimentation tank, 27 is a treated water outlet, and 28 is a sediment discharge port. Cobalt, nickel, gold, silver, and titanium with little metal elution are used as electrodes. This is because the generation of hydroxyl radicals per se with respect to hydrogen peroxide (see reaction formula 1 above), so that 0.1 mg / L to 1000 mg / L of hydrogen peroxide is introduced before entering this electrode. The pulse source and DC voltage disclosed in the inventions of claims 1, 2, 3, and 4 are added thereto to increase the generation of hydroxyl radicals, and diphenyl phthalic acid, nonylphenol or hardly decomposed by its reducing power. It oxidizes and decomposes substances that are specified as environmental hormones and sterilizes bacteria and molds contained in water. H in FIG.₂O₂FIG. 15C shows the effect of addition of Ag when ammonia is used.
[0033]
In the present invention, it may be difficult to secure a stable discharge and constant current for sewage and water having a large change in the electrical conductivity of water during treatment. An embodiment of the present invention for overcoming this problem is shown in FIG. FIG. 13 is composed of a high-sensitivity CCD camera 29 and a high-voltage pulse generator 30, and has a structure in which the gap 32 at the uppermost edge of the electrode part is narrower by 10% to 30% than the gap (d) 31 between the electrodes. In order to make Furthermore, a CCD detector is placed at the focal point of the optical system with a filter of 400 to 470 nm for detecting fluorescence so that liquid discharge can be monitored in this part, and the appropriate applied voltage is determined from the current amount on the oscillator side. In addition, an infrared or semiconductor type hydrogen detector is applied to the gas phase part above this electrode or piping connected to this electrode, and this concentration and gas flow rate are fed back to the oscillator, mainly controlling the current. It can be carried out.
[0034]
FIG. 14 shows changes in current and voltage when protrusions are formed on the electrode portions. In FIG. 14, 33 is the discharge start point of the electrode protrusion, 34 is the voltage indicating the minimum discharge current of the electrode protrusion, 35 is the discharge current of the electrode without the protrusion, and 36 is the voltage indicating the minimum discharge current of the electrode protrusion. The reference numeral 37 indicates a discharge current of an electrode without a protrusion corresponding to a voltage of 20% increase of the voltage indicating the minimum discharge current of the electrode protrusion. As shown in FIG. 13, the current increases earlier when the gap is smaller. When the lowering point values 34 and 36 are set, the discharge of the wide gap is appropriately performed. This discharge is characterized by a blue discharge color, which is similar to what is said to be a streamer discharge one step before the plasma discharge or corona discharge. It has been found that the corona discharge and the plasma discharge have a large electrode elution and cannot be practically used. The points 33 and 36 in FIG. 14 are the discharge regions of the narrow protrusions, and the points 35 and 37 are the currents and voltages corresponding thereto. If it is detected, a biased applied voltage is set, and the voltage is shifted to the position of the point 34 on the narrow side of the air gap. It will be. The streamer discharge on the narrow gap side becomes stronger, but the current becomes lower. Thus, the electrode provided with the side with the narrowed gap plays a role of a streamer discharge pilot. Actually, since it depends on the detection sensitivity of fluorescence, the combination of an optical system with a high condensing rate and a large lens aperture and a highly sensitive CCD determines the accuracy of this control.
[0035]
【Example】
The present invention will now be described in more detail for the examples.
Example 1
In order to show the effect of removing TOC, TN, TP in domestic wastewater, frequency 10KHz, repetitive pulse 1KHz, voltage 12kV, current density 50μA / cm²The oscillation conditions are as follows: the electrode is a titanium oxide ceramic plate of the positive electrode part, the cathode part is titanium, the gap between the electrodes is 1 cm, and 1 l / min to 2 l / min of domestic wastewater is allowed to flow between them for 30 minutes. ). From this table, reductive decomposition, that is, excellent hydroxyl radical was observed, and the removal rate of TN was slightly poor, but the removal rate of TOC and TP was high. Moreover, the reduction of the removal rate by the increase in the flow rate was not seen so much.
[0036]
Example 2
Most of the methane digestion and desorption liquid occupies ammonia nitrogen in TN, and it is desirable to oxidize and decompose by using superoxide radicals, and the TOC is also high. On the other hand, since the TP concentration is not so large, a direct current voltage of 250 V and a large current density of 4.0 mA / cm are used in order to aim at an oxidative decomposition type and to prevent electrical attenuation by suspended suspended solids.²In this case, a tin oxide-titanium plate was used as a positive electrode with strong generation of superoxide radicals, titanium was used as the cathode, the electrode gap was 2 cm, the liquid feed rate was 3 l / min, and the voltage application time was 30 minutes. The results are shown in FIG. Due to the oxidation type, the removal rate of ammonia nitrogen and TOC was very high. On the other hand, the removal rate of TP was not so high.
[0037]
Example 3
An example of treatment is shown for the supernatant of the initial sedimentation tank in the sewage treatment plant. Two-stage treatment is performed, and superoxide radicals are easily outstanding in the first stage. A tin oxide-titanium plate is used as the positive electrode, the cathode is the titanium plate, DC voltage 250 V, current density 3.0 mA / cm.²The voltage application time was 30 minutes. The second stage uses a titanium oxide-ceramics plate with superior hydroxyl radicals as the positive electrode, titanium as the cathode, frequency 5 kHz, pulse voltage application 15 kV, repetitive pulse 2 kHz, current density 30 μA / cm.²The first stage and the second stage were connected in series at a flow rate of 2 l / min. The results are shown as a table in FIG. It can be seen that the removal rate becomes very high by performing the two-stage treatment. It was also found that the weaknesses of the methods shown in Example 1 and Example 2 can be supplemented.
[0038]
Example 4
After removing coarse particles from rice washing wastewater with 1mm screen, frequency is 5kHz, repetitive pulse is 1kHz, voltage is 1kV, current density is 30μA / cm.²Under the oscillation conditions, the positive electrode was a tin oxide-titanium plate, the cathode was titanium, and a voltage was applied for 30 minutes to observe a decrease in the TOC and the number of general bacteria. The flow rate was 1 to 5 l / min, and the TOC was 80%. ˜90% could be removed and the bacteria count was reduced by 99.9%.
[0039]
【The invention's effect】
In the present invention, the generation of superoxide radicals is stably generated even in a high-frequency region and a low-frequency region. Further, in wastewater treatment containing a large amount of ions, a current flows stably and power consumption is reduced. -Stable processing can be performed even in a combination of low current, high frequency and minute current. Moreover, even when the electrical resistance of the raw water changes during the process, the voltage pulse can be stably applied.
[Brief description of the drawings]
FIG. 1 is a diagram showing changes in voltage and current until discharge when a voltage is applied by the device of the present invention.
FIG. 2 is a cross-sectional view when a positive electrode part and a cathode part of an electrode part according to the present invention are arranged to face each other.
FIG. 3 is a diagram showing generation of hydroxy radicals by an RNO solution.
FIG. 4 is a diagram showing a change in the metal concentration of a liquid layer by a correlation between processing time and concentration.
FIG. 5 is a diagram showing generation of superoxide radicals by a DMPO radical scavenger.
FIG. 6 shows the removal rate of total nitrogen when a voltage of 400 V is applied for 30 minutes to the Ti—Ti electrode part of the polluted water.
FIG. 7 is a circuit diagram showing an example of an embodiment of the present invention, and shows a case where discharge is performed by flowing ultrapure water between electrodes.
FIG. 8 is a view showing an example of a pulse waveform at the time of a 10 KV pulse.
FIG. 9 is a diagram showing a structure of a cylindrical truncated cone electrode portion according to the present invention.
FIG. 10 is a cross-sectional view showing a structure of a truncated pyramid electrode portion according to the present invention.
FIG. 11 is a diagram showing a structure of a cell electrode portion of the present invention.
FIG. 12 is a flowchart showing the flow of the processing method of the present invention.
FIG. 13 is a configuration diagram showing a proper applied voltage control system of the present invention.
FIG. 14 is a diagram showing a difference in discharge characteristics depending on the presence or absence of electrode protrusions in the discharge part of the present invention.
FIG. 15 is a diagram showing the results of various experiments according to the implementation of the present invention.
FIG. 16 is a diagram showing the results of various experiments according to the implementation of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ceramic metal or transition metal, 2 Sintered part (positive electrode) of metal particle or metal oxide, or mixture thereof, 3 Cathode electrode, 4 External cell, 5 Slack, 6 High voltage transformer, 7 High voltage diode, 8 High voltage resistance , 9 charge / discharge capacitor, 10 electrode part, 11 high voltage probe, 12 high voltage oscilloscope, 13 raw water inlet, 14 positive electrode part, 15 cathode electrode part, 16 mantle part (also used as cathode), 17 treated water outlet, 18 generation Gas exhaust port, 19 Electrical insulator, 20 Stirrer, 21 Raw water tank, 22 Hydrogen peroxide tank, 23 Metering pump (P₁), 24 Water pump (P₂), 25 electric field treatment device, 26 sedimentation tank, 27 treated water outlet, 28 sediment discharge port, 29 high sensitivity CCD camera, 30 high voltage pulse generator.

Claims (7)

Ceramic oxides mainly composed of feldspar and silicon or titanium, iron, stainless steel, titanium oxide, cobalt oxide, tin oxide, iridium oxide, nickel oxide, iron oxide or vanadium oxide fine particles or titanium, cobalt, nickel, silver, gold A positive electrode comprising the metal oxide or metal or a mixture thereof obtained by applying a liquid in which the same kind of metal salt solution is mixed to the metal fine particles or a mixture thereof and then drying and sintering in a temperature range of 500 ° C. to 1500 ° C. An electrode and a radical generator disposed so as to face each other and a cathode made of platinum, titanium, or stainless steel, and waste water is allowed to flow continuously between both electrodes of the facing electrode, Organic substances dissolved in water and their intermediates by generating a radical by partial decomposition of water by pulse discharge under conditions of voltage, current and frequency Together with the oxidation and reduction decomposition of Narubutsu,
When applying and sintering the metal oxide, the positive electrode is attached with fine wires of platinum or gold in a mesh shape with an interval of 2 mm to 100 mm so that the mesh metal is embedded in the surface of the metal oxide. The positive electrode terminal made of titanium, copper, stainless steel is connected to the end line of the mesh-like metal, and a positive voltage derived from a power source is reliably added to the positive electrode terminal . Purification equipment. An electrode on which a porous ceramic film having a thickness of 10 μm to 1 mm or a fluororesin film having a thickness of 0.1 to 100 μm, a hard polyethylene film, or a fluororesin film is deposited or applied is disposed on the cathode side facing the positive electrode. the radical-generating water purifying apparatus of claim 1, wherein the oxidizing-reduction decomposition of organic substances and their intermediate products in the waste water by. The positive electrode has a cylindrical or frustoconical structure with a total apex angle of 5 ° to 40 ° with respect to the center line, and the inner side surface and the outer side surface of the cylinder are the metal oxide powder, the same metal powder or the same. It consists of a metal surface coated and sintered with a mixture and a mixed liquid consisting of the same metal salt, and a cylindrical or truncated conical cone is provided with a round bar or square bar cathode made of platinum, titanium, stainless steel, and this The outside of the cylindrical truncated cone is sealed with an outer casing made of a metal container such as titanium or stainless steel, and the outer casing is disposed at the waste water inlet, outlet and generated gas outlet to constitute a cathode, and the cylinder The inside surface and the outside surface of the circular truncated cone are used as radical generators, and organic waste water is fed from the large diameter portion inside the cylindrical circular truncated cone, exits the small diameter portion, and again returns to the cylindrical circular truncated cone. Generates when the outer part flows in the opposite direction to the inner part Water purification device according to claim 1, characterized by having a structure in which oxidation-reduction treatment of wastewater by radicals. The positive electrode is a flat plate inclined at an angle of 2.5 ° to 20 ° with respect to the vertical plane, and two flat plates positioned perpendicular to the thickness direction of the flat plate are the metal oxide powder or metal powder or these A mixture and a mixed solution composed of the same metal salt are applied to both surfaces, and are composed of sintered metal surfaces. Two of these are used so that the metal surfaces are plane-symmetrical, and two flat plates Side surfaces that are not metal oxide surfaces are joined with titanium or stainless steel or a flat plate with the same metal surface on one side, and the anode voltage is configured to be a frustum so that the anode voltage is uniform, and the plane is symmetrical with the metal surface that is the center of the frustum A titanium plate, a stainless steel plate, a cathode electrode made of a platinum wire net or a platinum round bar, and a titanium / stainless steel container on the outside of the truncated pyramid to form an outer container, and the outer container is made into a wastewater inlet and outlet And arranged at the generated gas outlet to form a cathode The inner surface and the outer surface of the two flat plates coated with the metal oxide are used as radical generating parts, and organic waste water is fed from the large diameter or length part inside the truncated pyramid. The waste water discharged to a small portion has a structure for oxidizing / reducing and decomposing organic substances and harmful substances contained by radicals generated while the outer portion of the truncated pyramid flows again in the opposite direction to the inner portion. Item 2. A water purifier according to Item 1 . Two or more cylindrical conical frustums of the positive electrode are stacked, cylindrical cathodes made of stainless steel or titanium are alternately arranged between the conical cones, and the whole is sealed with an outer casing made of stainless steel or titanium. The outer vessel is provided with a waste water inlet, outlet and gas outlet to form a cathode, and the waste water is a cell with a radical generating electrode having a metal oxide surface as a positive electrode and stainless steel or titanium as a cathode. water purification device according to claim 1, characterized in that the radicals produced by allowing disposed on the structure to oxidation and reduction decomposing organic matter and toxic substances contained in the waste water. Two or more cylindrical pyramids on the positive electrode side are stacked, and cylindrical pyramid cathodes made of stainless steel or titanium are alternately arranged between the pyramids, and the whole is hermetically sealed with an outer casing made of stainless steel or titanium. The outer casing is provided with a waste water inlet, outlet and gas outlet to constitute a cathode, and a radical generating electrode having a metal oxide surface as a positive electrode and stainless steel or titanium as a cathode as a cell structure. water purification device according to claim 1, characterized in that the oxidation-reduction decomposition treatment of waste water by radicals generated, characterized in that it disposed. A protrusion is formed so that the gap at the uppermost edge of the electrode structure constituting the positive electrode and the cathode electrode is reduced by 10% to 30%, and 400 nm is provided in the water purifier stored so that the discharge can be monitored in this part. Arrangement of a fluorescence detector having a wavelength of ˜470 nm, and a hydrogen gas detector in the space immediately above the pipes or both electrodes to the generated gas outlet, control the voltage by detecting fluorescence, detecting water purification device according to claim 1, characterized in that a feedback signal to the oscillator so as to be able to control the current by automatically or manually by.

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