JP2005058887A - Waste water treatment apparatus using high-voltage pulse - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste water treatment apparatus using a high-voltage pulse which can treat organic substances at high removal rates in a short time even in the case of waste water containing a high concentration of the organic substances, and enables a high-efficiency treatment by improving a reaction efficiency in a decomposition reaction regions of the organic substances. <P>SOLUTION: In the waste water treatment apparatus, a treatment tank 2 having a cathode nozzle 3 connected to a high-voltage pulse power source 5 is installed, the cathode nozzle 3 is covered with an insulator 15 so that its tip end is exposed, gas is supplied between the cathode nozzle and an anode 4 while applying the high-voltage pulse between them to generate bubble discharge 14 in the waste water, and the organic substances are decomposed and removed by oxidative radicals produced in the waste water 1. The cathode nozzle has a double pipe structure provided with a gas passage guide 16, and is structured so that the gas flows through its outer periphery-side space. A mesh 18 for gas flow straightening is installed in a gas passage 17, and a rotating flow generation nozzle 20 is equipped for liquid innovation. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to wastewater treatment for organic material-containing wastewater such as human waste, sewage, landfill leachate, food processing wastewater, and factory wastewater, and more particularly, a high-voltage pulse for electrochemically decomposing and removing organic materials. The present invention relates to a wastewater treatment apparatus using treatment.

  Conventionally, treatment of wastewater containing organic substances is mainly performed by an activated sludge method, an intermittent aeration digestion method, a denitrification method, or the like. However, since all of these methods are biodegradation methods, if the wastewater to be treated contains a large amount of hardly decomposed organic substances, the wastewater must be diluted by adding a large amount of water. As a result, the amount of wastewater to be treated is increased, resulting in an increase in power consumption and high wastewater treatment costs. In addition, a long reaction time (several days to several weeks) for biodegradation is required.

In recent years, electrochemical processing apparatuses have been actively developed for the purpose of improving such problems. As the electrochemical wastewater treatment, as disclosed in US Pat. No. 5,464,513 (Patent Document 1) and the like, the organic substance is decomposed by subjecting the organic substance-containing wastewater to underwater high-pressure pulse discharge treatment. A method is mentioned.
Such a method is a method of sterilizing by high-pressure pulse discharge and decomposing an organic substance by an oxide generated by the discharge, and has an advantage that no sludge is generated without using chemicals.
Further, in JP-A-10-323684 (Patent Document 2), organic substance-containing water is subjected to high-pressure pulse discharge treatment in a high-pressure pulse discharge treatment apparatus, and soluble organic matter molecules are aggregated and suspended particles are generated by the active oxygen species generated. A wastewater treatment method has been proposed in which a reaction such as neutralization of the surface charge is caused to increase the cohesiveness of the suspended solids, thereby efficiently separating the contaminants in combination with solid-liquid separation.

  Further, as a process for efficiently performing the electrochemical reaction, as shown in FIG. 9, the anode 04 and the cathode 03 are arranged opposite to each other in a treatment tank 02 holding waste water containing an organic substance. There is an apparatus for decomposing an organic substance by generating a bubble 13 between electrodes while applying a high voltage pulse between the electrodes from a high voltage pulse power source 5 and performing a high-pressure pulse discharge treatment in water. For example, as disclosed in Japanese Patent Application Laid-Open No. 2001-293478 (Patent Document 3), there is a processing apparatus that uses the gas tank 06 as an ozone generator and introduces bubbles made of ozone into the processing tank 02.

  In these treatments, an electric field is formed in the bubble existence region by a high voltage pulse applied between the electrodes, and discharge in the bubble (bubble discharge) and in-liquid discharge extending from the bubble to the liquid and from the electrode to the liquid are generated. This is a method utilizing the action of generating and generating oxidative radicals such as OH radicals (hydroxy radicals) having high oxidizing power and promoting the decomposition of organic substances in wastewater by the oxidative radicals. Furthermore, in Patent Document 3, since ozone is used as the bubbles, OH radicals are likely to be generated using ozone as a raw material by bubble discharge or submerged discharge, and decomposition of organic substances is promoted.

As a method for improving the generation efficiency of oxidation radicals such as OH radicals and O radicals (oxygen radicals), Japanese Patent Application Publication No. 2002-539860 (Patent Document 4) specifies an electric field applied between radical generation electrodes as a specific condition. In addition, a treatment method has been proposed in which the metal oxide surface forming one electrode and the waste water are brought into contact with each other for a long time. Specifically, the wastewater is passed through a radical generating part composed of a tubular member coated with titanium dioxide that forms one electrode and a negative electrode rod that forms another electrode held on the axis, Oxidative decomposition of organic substances. At this time, the DC voltage gradient between the electrodes is set to a rectangular waveform with a voltage of 0.2 to 6 KV / cm, a frequency of 10 kHz to 150 kHz, and a pulse current density of 5 μm / cm ^{2 to} 50 mA / cm ² .
By these treatment methods, a certain amount of power consumption and wastewater treatment costs have been reduced, and reaction time has been shortened.

US Pat. No. 5,464,513 Japanese Patent Laid-Open No. 10-323684 JP 2001-293478 A Special table 2002-538960 gazette

However, although the treatment methods disclosed in Patent Documents 1 to 3 and the like are suitable for treatment of wastewater containing a low concentration of organic substances, a high voltage is required to cause underwater discharge. In the case of wastewater containing a high concentration of organic substances, the conductivity is high, so there is a problem that a high power supply is required to apply a high voltage and the processing efficiency is deteriorated. There was a need to improve the decomposition performance.
Moreover, in patent document 2, since it is not a decomposition | disassembly process but an aggregation process, apparatuses, such as a solid-liquid separation and a sedimentation tank, are needed, an installation enlarges and the post-process of an aggregate is needed and a process becomes complicated.
In addition, when electrical treatment is performed using ozone as in Patent Document 3, organic substances can be treated with a relatively high removal rate even for wastewater containing a high concentration of organic substances. However, since ozone is harmful to the human body, it is difficult to handle, and since ozone is expensive, running costs increase.

Furthermore, since the radical generated from the electrode surface is used in the treatment method of Patent Document 4, when the water to be treated is waste water containing organic substances such as human waste, sewage, or factory waste liquid, it is included in the waste water. There is a problem that SS (floating substance) adheres to the electrode surface, and the electrode surface activity changes to greatly change the processing performance.
Therefore, in view of the problems of the prior art, the present invention can treat an organic substance in a short time with a high removal rate even if it is wastewater containing a high concentration of the organic substance. An object of the present invention is to provide a wastewater treatment apparatus using a high-voltage pulse that improves the reaction efficiency in the decomposition reaction region of the gas and enables high-efficiency treatment.

Therefore, in order to solve this problem, the present invention provides:
Wastewater comprising a treatment tank having a pair of electrodes connected to a high-voltage pulse power source, subjecting wastewater to high-voltage pulse treatment in the treatment tank, and decomposing organic substances in the wastewater by the generated oxidation radicals In the processing device,
A waste water supply means for supplying waste water to the treatment tank; and a gas supply means having a gas supply nozzle formed of an electric conductor;
The gas supply nozzle is connected to the high voltage pulse power source, and the nozzle periphery is insulated so that the nozzle tip is exposed,
A feature is that gas is supplied while applying a high voltage pulse between the gas supply nozzle forming one electrode and the other electrode to generate bubble discharge in the wastewater.

According to this invention, since it is possible to efficiently generate oxidized radicals having very strong oxidizing power, even wastewater containing a high concentration of organic substances can be treated with a high removal rate. This makes it possible to improve the treatment water quality.
In addition, an electric field can be directly applied to the bubbles generated in the wastewater by using the gas supply nozzle as a cathode, exposing the tip of the nozzle to cover with an insulator, and generating bubbles from the tip of the cathode. Bubble discharge can be easily generated. Therefore, it is possible to discharge the wastewater having high conductivity stably and at a lower voltage than the liquid discharge.
Moreover, since gas and wastewater can be controlled independently, it becomes possible to control discharge more stably than in a gas-liquid mixing system.

Further, the present invention is characterized in that the gas flow path ejected into the wastewater through the gas supply nozzle has a gas flow path structure in which gas is concentrated and concentrated from the vicinity of the opening edge of the nozzle, Preferably, the gas supply nozzle has a double pipe structure, and the gas flow path structure has a structure in which the gas is concentrated and ejected from the vicinity of the opening edge through a gap on the outer peripheral side of the nozzle.
Thereby, bubbles can be stably supplied to a high electric field strength region where discharge is easily started, and the generation reaction efficiency of oxidized radicals is improved.

Further, the present invention is characterized in that a gas rectifying mesh member is provided on a flow path of gas ejected into the wastewater through the gas supply nozzle.
Thereby, it is possible to prevent the gas flow path from being eccentric, and to suppress pressure pulsation generated on the gas flow path. Further, since the gas passes through the mesh member, minute bubbles can be supplied to the high electric field strength region, and an atmosphere in which bubble discharge easily occurs can be formed. Therefore, the oxidation radical effective for the decomposition of the organic substance is more easily generated by the discharge, so that the waste water can be efficiently decomposed.

In addition, a gas retention portion made of an insulating material is provided outside the tip of the gas supply nozzle so that bubbles are retained in the high electric field strength region.
As a result, the bubbles can be reliably retained in the high electric field strength region, and stable discharge can be performed at a lower voltage than in the prior art. As a result, oxidation radicals effective for organic decomposition are more easily generated by the discharge, so that waste water can be efficiently decomposed.

Further, the present invention is characterized in that there is provided means for renewing waste water existing in the oxidized radical generation region on the outer periphery of the gas supply nozzle.
At this time, the waste water update means is a swirl flow generation nozzle provided so as to cover the gas supply nozzle, and the swirl flow generation nozzle swirls waste water in the oxidation radical generation region along the outer peripheral surface of the nozzle. It is preferable to configure as described above.
In general, the reaction starting from a discharge reaction by a high voltage pulse is performed by excitation decomposition in a gas, reaction of the exciter with a solution, collision of high-speed electrons with the solution, or metal oxide-treated electrode surface. Oxidized radicals generated by reaction or the like contribute, but all occur in a region near the surface of the number of liquid surface layers to about several tens of μm. Therefore, the reaction of the whole system is usually governed by diffusion.
Therefore, by updating the waste water in the radical generation region that is in contact with the discharge, the unreacted region can always be brought closer to the discharge reaction surface, so that the reaction efficiency can be improved.

Furthermore, the gas is an oxygen-enriched gas, a chlorine-containing gas, or a mixed gas thereof.
In this invention, by using the oxygen-enriched gas, active oxidizing species having strong oxidizing power such as O ₃ , O radicals, and O ²⁻ ions are efficiently generated in the discharge, thereby improving the decomposition performance of organic substances. In addition, by using a chlorine-containing gas, Cl radicals are efficiently generated in the discharge, and the decomposition performance of the organic substance can be improved.

As described above, according to the present invention, even wastewater containing a high concentration of an organic substance can be treated in a short time with a high removal rate, and the reaction in the decomposition reaction region of the organic substance High efficiency processing is possible by improving the efficiency.
That is, the tip of the cathode nozzle is exposed and covered with an insulator, and bubbles are generated from the tip of the cathode, so that an electric field can be directly applied to the bubbles generated in the wastewater, and bubble discharge is easily generated. Can be made. Therefore, it is possible to discharge the wastewater having high conductivity stably and at a lower voltage than the liquid discharge.
Further, by making the gas flow path structure such that gas is concentrated from the vicinity of the opening edge of the nozzle, bubbles can be stably supplied to a high electric field strength region where discharge is likely to start. , Oxidation radical generation reaction efficiency is improved.

Further, by providing a gas rectifying mesh member on the gas flow path, it is possible to prevent the gas flow path from being eccentric and to suppress pressure pulsation generated on the gas flow path. Furthermore, since the gas passes through the mesh member, an atmosphere in which minute bubbles are generated and bubble discharge is likely to occur can be formed.
Furthermore, by adopting a structure in which the wastewater in the radical generation region that is in contact with the discharge is renewed, the unreacted region can always be brought closer to the discharge reaction surface, so that the reaction efficiency can be improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, but are merely illustrative examples. Not too much.
FIG. 1 is a configuration diagram of a wastewater treatment apparatus according to the first embodiment of the present invention, FIG. 2 is a graph showing a change with time of OH radical fluorescence intensity in the first embodiment, and FIG. 3 is H ₂ O ₂ in the first embodiment. The graphs showing the change over time in concentration, FIGS. 4, 5 and 7, 8 are configuration diagrams of the wastewater treatment apparatus according to the second, third, fourth and fifth embodiments of the present invention, respectively.

First, a wastewater treatment apparatus according to a first embodiment of the present invention will be described with reference to FIG.
According to FIG. 1, a cathode nozzle (gas supply nozzle) 3 and an anode 4 that also serve as a gas supply mechanism are arranged in a treatment tank 2 that holds the organic waste water 1. The anode 4 may be disposed at the liquid supply port. A high voltage pulse power source 5 is connected to both electrodes, and pulse power suitable for processing conditions is supplied. The treatment tank 2 is provided with a gas supply mechanism for introducing the gas stored in the gas tank 6 from the cathode nozzle 3 to the waste water 1 in the treatment tank through the gas supply pipe 7. A desired type and amount of gas is introduced into the treatment tank 2 by the gas supply mechanism, and bubbles are generated in the waste water 1. The gas tank 6 can be replaced with a compressor.

The treatment tank 2 is connected to a pretreatment tank 10 via a wastewater supply mechanism comprising a liquid supply pipe 8 and a liquid supply nozzle 9 and to a post-treatment tank 12 via a wastewater discharge mechanism comprising a liquid discharge pipe 11. The The pretreatment tank 10 can use a screen for removing impurities in wastewater, and the posttreatment tank 12 can use a biological treatment tank such as an aerobic fermentation process and an anaerobic fermentation process. .
Each of the gas supply mechanism, the waste water supply mechanism, and the waste water discharge mechanism is configured to be able to adjust the supply amount and the discharge amount as appropriate by providing liquid amount control means such as valves. As described above, the gas supply mechanism, the waste water supply mechanism, and the waste water discharge mechanism can be independently controlled. With this configuration, gas and liquid are separately supplied into the processing tank 2 and mixed in the processing tank 2.
Further, although the waste water 1 in the treatment tank 2 is in a stirring state by the bubbles 13 from the cathode nozzle 3, a mechanical stirring means such as a stirring blade and a waste water circulation means (not shown) may be provided. .

In the present embodiment, the cathode nozzle 3 is used as one electrode (cathode 3), the other electrode (anode 4) is disposed opposite to the electrode, and the high voltage pulse is provided outside the processing tank. Each is connected to a power source 5. The cathode nozzle 3 is made of a metal conductor, and the outer peripheral surface of the nozzle is covered with an insulator 15 and only the end of the cathode nozzle 3 is covered and exposed. The treatment tank itself may function as an anode (the same applies to other embodiments).
In the treatment tank 2 having such a configuration, a high frequency voltage including a pulse is applied between the two electrodes by the high voltage pulse power source 5, thereby generating a discharge 14 with the bubbles 13 generated in the waste water 1. And an oxidation radical is produced | generated by bubble discharge and the organic substance in wastewater is decomposed | disassembled.

As described above, by using the electrode having the above-described configuration, an electric field can be directly applied to bubbles generated in wastewater. And since this electric field can generate a bubble discharge, it is possible to discharge stably even at a high conductivity wastewater at a lower voltage than a liquid discharge. In particular, by insulating the portion of the cathode nozzle 3 other than the portion in contact with the waste water in the treatment tank and electrically exposing only the portion, it is possible to effectively apply a voltage to the bubbles without flowing a large current. .
In addition, since the supply amount of the gas and the waste water can be controlled independently, it is possible to control the discharge stably as compared with the case where an electric field is directly applied to the gas-liquid mixing system as in the past. it can.

As a result, oxidation radicals such as OH radicals and O radicals (oxygen radicals) that are effective for decomposing organic substances in the discharge are excited and decomposed in the gas, reacted with the solution of the exciter, or a solution of fast electrons. It is easily generated through collision with the electrode, reaction of the electrode surface treated with metal oxide, and the like.
OH radicals and H ₂ O ₂ which are reaction products effective for decomposing organic substances are generated by the following reaction formulas (1) and (2).
H ₂ O → H ⁺ + · OH + e ⁻ (1)
2.OH → H ₂ O ₂ (2)
Oxidized radicals having very strong oxidizing power, such as OH radicals or O radicals generated by the above reaction formula, and hydrogen peroxide generated by the oxidized radicals react with an organic substance, and finally CO2. ₂ is discharged.
Thus, according to this embodiment, since the generation efficiency of oxidation radicals can be improved, wastewater can be treated with high efficiency.

Next, a specific example (first example) in the first embodiment will be described below.
In the processing apparatus in this embodiment, a beaker container having a volume of about 0.5 L is used as the processing tank 2, and the outer periphery of the titanium pipe (outer diameter φ10 mm × inner diameter φ8 mm) as the cathode nozzle 3 is an insulating Teflon (registered trademark). A simulated liquid (liquid conductivity) in which a titanium pipe (outside diameter φ60 mm × inside diameter φ54 mm) as an anode 4 and an anode 4 are coaxially arranged in the vessel and sodium chloride is dissolved in distilled water as a liquid to be treated. 2S / m) was used. In addition, using a solution added with coumarin as a reagent for obtaining fluorescence proportional to the amount of OH produced, the following reaction formula (3) was selectively generated with OH radicals, and confirmed by using fluorescence. .

In the processing method using the processing apparatus, atmospheric air is supplied to the cathode nozzle at 1 to 2 L / min, and a voltage of 2 kV and a pulse width of about 1 μs are supplied from the high voltage pulse power source between the cathode nozzle and the anode at regular intervals. The pulse high voltage was applied at a repetition frequency of 1 kHz.
As a comparative example, processing was performed with the same apparatus configuration as that of the conventional technique shown in FIG. In this comparative example, an electrode similar to that of the present embodiment shown in FIG. 1 is disposed in a beaker container holding a liquid to be processed equivalent to that of the above embodiment, gas is not supplied to the cathode nozzle, and an electrode is separately supplied from a gas tank. The process was carried out by applying the same high voltage pulse as in the above example while generating bubbles in between.

Differences in the operation between the embodiment and the comparative example are shown in FIGS. FIG. 2 shows the change over time of the OH radical concentration in the wastewater obtained from this example and the comparative example, and FIG. 3 shows the change over time of the H ₂ O ₂ concentration. According to this, as shown in FIGS. 2 and 3, in this example, H ₂ O ₂ and OH radicals, which are reaction products effective for organic decomposition, could be obtained. In contrast, in the comparative example, H ₂ O ₂ and OH radicals were not obtained.
Further, in the same configuration as in FIG. 1, the same treatment as in this embodiment is performed using a supernatant obtained by adding polyaluminum chloride (PAC) to human urine as a treatment target solution and precipitating and removing SS (floating matter). Table 1 shows the measurement results of the total carbon amount (TOC).

As is clear from Table 1, it was shown that the TOC decreased in the configuration of this example, and it became clear that the organic substance was decomposed.
In addition, when acquiring the effect described in this application, it is not limited to these dimensions and material specifications. Empirically, it is preferable that the cathode nozzle size is φ2 to φ15 mm, the voltage is 1 to 5 kV, the pulse width is 0.2 to 5 μs, and the repetition frequency is 0.1 to 10 kHz.

FIG. 4 shows a processing apparatus according to the second embodiment of the present invention. Similar to the first embodiment, such a processing apparatus includes a cathode nozzle 3 and an anode 4 in the processing tank 2, a high voltage pulse power source 5 for applying a voltage to these, a gas tank 6 as a gas supply mechanism, and a gas supply pipe. 7. Insulator 15 which covers the liquid supply pipe 8 and the liquid supply nozzle 9 which are the waste water supply mechanism, the pretreatment tank 10, the liquid discharge pipe 11, the posttreatment tank 12, and the cathode nozzle 3 with the tip portion exposed. , And have the structure provided.
Further, in the second embodiment, the gas flow path ejected into the waste water 1 through the cathode nozzle 3 is the gas flow path structure 17 in which gas is concentrated from the vicinity of the opening edge of the nozzle.

That is, in this embodiment, the gas sent from the gas tank 6 to the treatment tank side through the gas supply pipe 7 is concentrated at the end of the cathode nozzle 3. Preferably, as shown in FIG. 4, the cathode nozzle 3 has a double tube structure, and the gas flow path structure 17 is concentrated in the vicinity of the opening edge through the gap on the outer peripheral side of the nozzle. A structure that erupts is good.
Thereby, bubbles can be stably supplied to a high electric field strength region where discharge is easily started, and the generation reaction efficiency of oxidized radicals is improved.

The processing apparatus according to the third embodiment shown in FIG. 5 has substantially the same configuration as that of the first embodiment, and includes a processing tank 2, a cathode nozzle 3, an anode 4, and a high voltage pulse power source 5. A gas tank 6, a gas supply pipe 7, a liquid supply pipe 8, a liquid supply nozzle 9, a pretreatment tank 10, a liquid discharge pipe 11, a posttreatment tank 12, and an insulator 15.
Further, in the third embodiment, a gas flow guide 16 is provided as in the second embodiment, and a gas rectifier that is a donut ring-shaped mesh member is provided on the gas flow channel 17 in the cathode nozzle 3. The mesh 18 is provided.
Thereby, it is possible to prevent the gas flow path 17 from being eccentric, and to suppress pressure pulsation generated on the upstream side of the gas flow path 17.
Moreover, since the gas supplied from the gas tank 6 passes through the rectifying mesh 18, minute bubbles having a diameter of 1 mm or less can be supplied to the high electric field strength region.
According to Paschen's law representing the dielectric breakdown voltage, the condition that gives the minimum spark voltage of gas centered on air is obtained by the following mathematical formula (1).

According to this, d which gives the minimum spark voltage at atmospheric pressure (760 mmTorr) is about 4 to 50 μm, so that it is usually a minute one having a diameter of 1 mm or less with respect to bubbles (about several mm in diameter) supplied from the nozzle. It can be seen that discharge is more likely to occur in bubbles.
Therefore, by performing discharge with fine bubbles having a diameter of 1 mm or less by the rectifying mesh 18, a stable discharge process can be performed at a low voltage. As a result, the radicals effective for the decomposition of the organic substance are more easily generated by the discharge, so that the waste water can be efficiently decomposed.

FIG. 6 shows a processing apparatus according to the fourth embodiment of the present invention. The processing apparatus has substantially the same configuration as that of the first embodiment, and includes a processing tank 2, a cathode nozzle 3, an anode 4, a high voltage pulse power source 5, a gas tank 6, a gas supply pipe 7, and a liquid supply pipe 8. , A liquid supply nozzle 9, a pretreatment tank 10, a liquid discharge pipe 11, a posttreatment tank 12, and an insulator 15.
Further, a gas retention guide 19 made of an insulating material is provided outside the tip of the cathode nozzle 3 so that bubbles are concentrated in the high electric field strength region.
That is, the gas retention portion is provided in a region having a high electric field strength in the vicinity of the insulating exposed portion of the cathode nozzle 3 so that the bubbles 13 can be concentrated on the end portion of the cathode nozzle 3 having a high electric field strength.

  Thereby, the bubbles 13 can be stably retained in the high electric field strength region where discharge is easily started. Furthermore, by using the structure including the gas flow path guide 16 and the rectifying mesh 18 shown in the second embodiment, it is possible to reliably retain bubbles in the high electric field strength region. Therefore, stable discharge can be performed at a lower voltage than in the prior art. As a result, the radicals effective for organic decomposition are more easily generated by the discharge, so that the waste water can be efficiently decomposed.

Next, specific examples (third example and fourth example) in the third and fourth embodiments shown in FIGS. 5 and 6 are shown below.
First, in the third embodiment, a beaker container having a volume of about 0.5 L is used as the processing tank 2, and the outer periphery of the titanium pipe (outer diameter φ10 mm × inner diameter φ8 mm) as the cathode nozzle 3 is covered with an insulating Teflon. A glass pipe (outside diameter φ4 mm x inside diameter φ2 mm) is placed inside a plastic fiber gas rectifying mesh 18 of φ8 mm x φ4 mm x thickness 5 mm inside, and a titanium pipe (outside diameter φ60 mm x inside diameter φ54 mm) as the anode 4 Was installed coaxially in the container. A supernatant liquid obtained by adding PAC to human urine and removing SS by precipitation was used as a liquid to be treated. As a processing method using such a processing apparatus, atmospheric pressure air is supplied to the cathode nozzle, and air is supplied to the gap flow path between the SUS cathode inner side and the glass outer periphery at a rate of 1 to 2 L / min. A pulse high voltage with a voltage of 2 kV and a pulse width of about 1 μs was applied between the anode and the anode at a frequency of 1 kHz from a high voltage pulse power source.

  In the fourth embodiment, a beaker container having a volume of about 0.5 L is used as the treatment tank 2, a titanium pipe (outer diameter φ10 mm × inner diameter φ8 mm) is used as the cathode nozzle 3, and the outer periphery of the titanium pipe is made of an insulator. An acrylic pipe (outside diameter φ16 mm x inside diameter φ15 mm x length 5 mm) is placed outside the tube covered with Teflon, and a titanium pipe (outside diameter φ60 mm x inside diameter φ54 mm) is used as the anode 4, and these are coaxial in the container. Installed. The liquid to be treated and the treatment method were the same as those in the third example.

Here, FIG. 7 shows the discharge frequency obtained from the measured value of the discharge current when the high voltage pulse is applied with respect to the voltage application frequency of 1 kHz. According to this, it has been clarified that the configuration shown in FIGS. 5 and 6 stabilizes the discharge and increases the discharge frequency compared to the case where the configuration is not adopted.
Table 2 below shows the measurement results of the total carbon amount (TOC) when the discharge treatment is performed according to the second to third examples of the second to fourth embodiments. As is clear from Table 2, it was shown that the TOC decreased in the second to fourth examples, and it was clear that organic decomposition was effectively carried out.

FIG. 8 shows a processing apparatus according to the fifth embodiment of the present invention. Similar to the first embodiment, the processing apparatus includes a processing tank 2, a cathode nozzle 3, an anode 4, a high voltage pulse power source 5, a gas tank 6, a gas supply pipe 7, a liquid supply pipe 8, a liquid supply nozzle 9, a front A treatment tank 10, a liquid discharge pipe 11, a post-treatment tank 12, and an insulator 15 are provided. Moreover, it is set as the structure which comprised the gas flow path guide 16 similarly to the said 2nd Embodiment.
Further, in the fifth embodiment, there is provided means for renewing the waste water existing in the oxidized radical generating region where the oxidized radical is most easily generated on the outer periphery of the cathode nozzle 3.
For example, as shown in FIG. 8, the waste water renewing means includes a swirl flow generating nozzle 20 attached to cover the cathode nozzle 3 and a swirl liquid inflow pipe 21 for supplying waste water to the nozzle 20. The The swirl flow generation nozzle 20 swirls waste water in the oxidation radical generation region along the outer peripheral surface of the nozzle, and the waste water is renewed.

In general, the reaction starting from a discharge reaction by a high voltage pulse is performed by excitation decomposition in a gas, reaction of the exciter with a solution, collision of high-speed electrons with the solution, or metal oxide-treated electrode surface. Oxidized radicals generated by reaction or the like contribute, but all occur in a region near the surface of the number of liquid surface layers to about several tens of μm.
Therefore, the reaction of the whole system is usually governed by diffusion. Therefore, by updating the wastewater in the radical generation region that is in contact with the discharge, the unreacted region can always be brought closer to the discharge reaction surface, so that the reaction efficiency can be improved.

Next, a specific example (fifth example) of the fifth embodiment will be described. In this embodiment, a beaker container having a volume of about 0.5 L is used as the treatment tank 2 and an acrylic pipe (outer diameter φ30 mm × inner diameter φ15 mm) is arranged outside the titanium pipe (outer diameter φ10 mm × inner diameter φ8 mm) as the cathode nozzle 3. Then, a titanium pipe (outer diameter φ60 mm × inner diameter φ54 mm) was used as the anode 4 and was installed coaxially in the container. The acrylic pipe was provided with a liquid ejection port having a diameter of 3 mm in the circumferential direction of the inner diameter.
As a treatment target liquid, a supernatant liquid obtained by adding PAC to human waste and precipitating and removing SS was used.

As a processing method using the processing apparatus, atmospheric pressure air is supplied to the cathode nozzle, and the liquid is supplied at a flow rate of 0.2 to 1 L / min while supplying air to the gap between the inner side of the titanium cathode and the outer periphery of the glass at 1 to 2 L / min. The liquid was supplied as a swirl flow along the inner acrylic pipe.
As for the power condition, a pulse high voltage having a voltage of 2 kV and a pulse width of about 1 μs was repeatedly applied at a frequency of 1 kHz between a cathode and an anode for a certain time.
Table 3 below shows the measurement result of the total carbon content (TOC) when the processing in the above-described example was performed. As apparent from Table 3, it was shown that the TOC decreased in the configuration of this example, and it became clear that the organic substance was decomposed.

Furthermore, in these embodiments, the gas supply mechanism is independently controllable, and any gas species necessary to generate the desired reactive radical, such as air, oxygen-enriched gas, chlorine-containing gas or these It is possible to selectively supply a mixed gas or the like. In this case, by using an oxygen-enriched gas, active oxidizing species having strong oxidizing power such as O ₃ , O radicals, and O ²⁻ ions can be efficiently generated by discharge, and the decomposition performance of organic substances can be improved. Can be improved.
Further, by using a chlorine-containing gas, Cl radicals can be efficiently generated by discharge, and the decomposition performance of the organic substance can be improved.

Thus, an example using an oxygen-enriched gas as the gas will be described. The apparatus configuration is the same as that of the first embodiment shown in FIG. A beaker container having a volume of about 0.5 L is used as the treatment tank 2, a titanium pipe (outer diameter φ10 mm × inner diameter φ8 mm) is used as the cathode nozzle 3, and a titanium pipe (outer diameter φ60 mm × inner diameter φ54 mm) is used as the anode 4. Was coaxially arranged in the container. As the treatment target liquid, a supernatant liquid obtained by adding PAC to human waste and precipitating SS was used. However, as a treatment method, pure oxygen gas (purity 99.9%) is supplied to the cathode nozzle 3 in an amount of 1 to 2 L / min, and a pulse height of 2 kV and a pulse width of about 1 μs from a high voltage pulse power source is provided between the cathode and the anode for a fixed time. The voltage was applied repeatedly at a frequency of 1 kHz.
Table 4 below shows the measurement result of the total carbon amount (TOC) when the treatment in the above-described example is performed. As a comparative example, the result of supplying atmospheric pressure air to the gas is also shown. As is clear from this table, it is shown that the TOC is reduced in the configuration of this example, and organic It became clear that the chemical substance was decomposed.

  By making the treatment tank itself function as an anode, the treatment efficiency can be improved and the treatment tank can be applied to a wastewater treatment plant for large-capacity wastewater.

It is a block diagram of the waste water treatment apparatus of 1st Embodiment which concerns on this invention. It is a graph which shows a time-dependent change of the OH radical fluorescence intensity in the 1st embodiment. This is a graph showing the time course of concentration of H ₂ O ₂ in the first embodiment. It is a block diagram of the wastewater treatment apparatus of 2nd Embodiment which concerns on this invention. It is a block diagram of the waste water treatment apparatus of 3rd Embodiment which concerns on this invention. It is a block diagram of the waste water treatment apparatus of 4th Embodiment which concerns on this invention. It is the figure which showed the discharge frequency in FIG. 5, FIG. It is a block diagram of the wastewater treatment apparatus of 5th Embodiment which concerns on this invention. It is a block diagram of the conventional wastewater treatment apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 2 Processing tank 3 Cathode nozzle 4 Anode 5 High voltage pulse power supply 6 Gas tank 13 Bubble 14 Discharge 15 Insulation coating 16 Gas flow guide 17 Gas flow guide 18 Rectification mesh 19 Bubble retention guide 20 Swirling flow generation nozzle 21

Claims (8)

Wastewater comprising a treatment tank having a pair of electrodes connected to a high-voltage pulse power source, subjecting wastewater to high-voltage pulse treatment in the treatment tank, and decomposing organic substances in the wastewater by the generated oxidation radicals In the processing device,
A waste water supply means for supplying waste water to the treatment tank; and a gas supply means having a gas supply nozzle formed of an electric conductor;
The gas supply nozzle is connected to the high voltage pulse power source, and the nozzle periphery is insulated so that the nozzle tip is exposed,
A high voltage pulse characterized in that a gas discharge is generated in waste water by supplying a gas while applying a high voltage pulse between the gas supply nozzle forming the one electrode and the other electrode. Waste water treatment equipment using   2. The gas flow path structure in which the gas flow path that is ejected into the wastewater through the gas supply nozzle is configured to be concentrated from the vicinity of the opening edge of the nozzle and the gas is ejected. Wastewater treatment equipment using high voltage pulses.   The gas supply nozzle has a double pipe structure, and the gas flow path structure has a structure in which the gas is concentrated and ejected from the vicinity of the opening edge through a gap on the outer peripheral side of the nozzle. Waste water treatment equipment using the described high voltage pulse.   The wastewater using high voltage pulses according to any one of claims 1 to 3, wherein a mesh member for gas rectification is provided on a flow path of gas ejected into the wastewater through the gas supply nozzle. Processing equipment.   The high voltage pulse according to any one of claims 1 to 4, wherein a gas retaining portion made of an insulating material is provided outside the tip of the gas supply nozzle so that bubbles are retained in a high electric field strength region. Waste water treatment equipment using   The wastewater treatment apparatus using high voltage pulses according to any one of claims 1 to 4, further comprising means for renewing wastewater existing in an oxidized radical generation region on an outer periphery of the gas supply nozzle.   The waste water renewing means is a swirl flow generation nozzle provided so as to cover the gas supply nozzle, and the swirl flow generation nozzle is configured to swirl waste water in the oxidation radical generation region along the outer peripheral surface of the nozzle. The wastewater treatment apparatus using the high voltage pulse according to claim 6.   The wastewater treatment apparatus using a high-voltage pulse according to any one of claims 1 to 6, wherein the gas is an oxygen-enriched gas, a chlorine-containing gas, or a mixed gas thereof.

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