JP2002059170A - Method and device for liquid treatment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and a device for liquid treatment which suppress not only the rise of the temperature of a liquid to be treated but also the consumption of energy, by reducing a leakage current to the liquid as much as possible and controlling a route of flow of a minute leakage current which cannot be stopped, to suppress the occurrence of a module loss due to the leakage current, when pulselike power is supplied between electrode pairs to reform the liquid existing between electrode pairs. SOLUTION: In a method for liquid treatment in which the pulselike power is supplied between electrode pairs to reform the liquid to be treated which exists between electrode pairs, each electrode pair consists of an electrode electrically exposed to the liquid and an electrode which is so protected that it may not be electrically exposed to the liquid, and at least two electrode pairs are included, and the electrode electrically exposed to the liquid of one of two electrode pairs arbitrarily selected from these electrode pairs and the electrode, which is so protected that it may not be electrically exposed to the liquid, of the other electrode pair are mutually electrically connected to perform operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to (1) a biological aerobic treatment of organic wastewater discharged from a sewage treatment process in a sewage treatment plant or a human waste treatment plant, or a drainage process in a food factory or a chemical factory. Treatment or anaerobic treatment, (2) sterilization of treated water, water and sewage water, and food and drinking water in the process of producing waste liquid (including non-organic waste liquid), pure water, etc. Sterilization treatment, decolorization treatment, or (3)
Liquids used for the sterilization / sterilization treatment of the various liquids described above, the decomposition treatment of dioxin, environmental hormones, and the like that are hardly decomposable substances such as PCBs that appear during the decolorization treatment or the leach of a garbage incinerator. And an apparatus used to carry out such a processing method.

[0002]

2. Description of the Related Art In various applications shown in the above (1) to (3), as a method for reusing water or removing trace contaminants, conventionally, various methods such as activated carbon treatment, ozone treatment, membrane treatment, etc. Is known, and practical use is being promoted. However, in the activated carbon treatment, it is possible to adsorb and remove organic pollutants, but there is no bactericidal effect, and the activated carbon needs to be replaced frequently. Further, the ozone treatment is excellent in decolorization, deodorization and sterilization effects, but has a problem of secondary treatment due to residual ozone. Further, the membrane treatment is excellent from the viewpoint of water treatment, but has a problem that maintenance is complicated, costs are high, and waste is generated.

The present inventors have been studying the improvement of the water treatment technology as described above, and have proposed a technology as disclosed in Japanese Patent Application Laid-Open No. H11-253999. This technique is, for example, a method of purifying the liquid by killing harmful bacteria contained in the liquid, or reducing the volume of a contaminant component such as bacteria or dead bodies contained in the liquid. Therefore, as a method of reforming the fouling component to a state in which aerobic microorganisms can be easily biochemically treated, the liquid is subjected to high voltage pulse discharge treatment and / or electric field pulse application to treat the liquid. is there. This technique will be described with reference to the drawings.

FIG. 1 is a diagram schematically showing the configuration of a processing apparatus proposed by the present inventors. In this apparatus, the liquid to be treated is an organic waste liquid, and the organic waste liquid is subjected to biological treatment. This is a case where aerobic treatment is performed.

In the apparatus shown in FIG. 1, the organic waste liquid is sent to an activated sludge tank (aeration tank) 1 through a passage 7. This activated sludge tank 1 holds a fixed amount of activated sludge containing aerobic microorganisms, and the biodegradation of the aerobic microorganisms oxidizes and decomposes the organic matter in the organic waste liquid under aerobic conditions. And water (aerobic treatment step). At the same time, the organic matter in the organic waste liquid is assimilated and activated sludge multiplies.

[0006] The waste liquid after the treatment is sent to the sedimentation tank 2 via the path 8 while being mixed with the activated sludge,
And a supernatant (liquid to be treated) 20. The supernatant 20
Is discharged from the passage 9 as a liquid to be treated. At this time, if necessary, higher-order treatment such as nitrification denitrification or ozone treatment is performed according to the discharge standard of the discharge destination.

A part of the settled sludge 10 is returned to the activated sludge tank (aerobic treatment tank) 1 by a pump 16 via a return path 11, and a part, preferably all of the sludge is reformed by a pump 17 from a path 12. To be introduced. The reforming device 18 includes a reforming tank 3 and a power supply 4. A rod-shaped electrode (+
The pole 5 and the flat electrode 6 are arranged in parallel so as to be immersed in the sludge in the reforming tank 3. The sludge inside the reforming tank 3 can be electrically regarded as a dielectric material having a certain dielectric constant, and a potential difference between the electrodes 5 and 6 in a state where the dielectric material is filled between the electrodes 5 and 6. When an electric field is applied, an electric field is formed inside the dielectric (sludge). When the intensity of the electric field exceeds a certain level, dielectric breakdown occurs, and a discharge occurs between the electrodes 5 and 6.

By forming a high-voltage pulsed discharge state between the electrodes 5 and 6, microorganisms and organic substances in the settled sludge are modified, and solubilization of the sludge proceeds. That is, microorganisms die, and are further decomposed by cell destruction and the like to produce low-molecular organic substances and inorganic substances. Organic substances are decomposed into low-molecular substances by decomposition and are easily decomposed (hereinafter referred to as “modified sludge”). Sometimes).

[0009] The reformed sludge is returned from the return route (return means) 13 to the activated sludge tank (aerobic treatment tank) 1. The activated sludge tank 1
Inside, the aerobic microorganisms use the modified sludge as feed and decompose.

By forming a circulation system in which sludge is partially or preferably reformed and returned to the activated sludge tank 1, sludge circulating in the system is reduced in volume,
As a result, the amount discharged as excess sludge is reduced.

[0011]

In the high-voltage processing apparatus as described above, the liquid (the liquid to be processed) could be efficiently reformed. However, such a technique still has some problems to be improved. I was FIG. 2 is a schematic explanatory view showing an example of an arrangement state and an electric discharge state of electrodes in a processing vessel (corresponding to the reforming tank 3 in FIG. 1).
23 is a liquid to be treated, 24 is a discharge, 25 is a rod-shaped electrode, 26 is a ring-shaped electrode, 27 is a high voltage pulse power supply, and 28 is a leakage current. In the configuration shown in FIG. 2, the rod-shaped electrode 25 and the ring-shaped electrode 26 are arranged concentrically so that a three-dimensional discharge can be performed on the liquid 23 to be processed in the processing container 22. is there.

In the above configuration, when a steep rising pulse voltage is applied from the high voltage pulse power supply 27 between the rod-shaped electrode 25 and the plate electrode 26, a planar discharge 24 is generated, which is smaller than a linear discharge. The discharge 24 can act on the liquid 23 to be treated in a wide range. And it is general that it is processed by both discharge of streamer discharge and arc discharge before changing to arc discharge.

However, in the above-described discharge state, the area of the leakage current 28 to the liquid 23 to be processed becomes larger than the processing area through which the streamer discharge or the arc discharge passes, and the exposed area of the electrodes 25 and 26 becomes smaller. Large, liquid to be treated 23
A large amount of leakage current 28 flows into the device. As a result, these leakage currents 28 cause Joule loss, which not only raises the water temperature of the liquid 23 to be treated, but also wastes energy.

The present invention has been made under such a circumstance. An object of the present invention is to supply a pulsed electric power between an electrode pair to reform a liquid existing between the electrode pairs. In addition to minimizing the leakage current to the device and controlling the path of the minute leakage current that could not be suppressed, the generation of Joule loss due to the leakage current is suppressed, the rise in the water temperature of the liquid to be treated is suppressed, and the energy consumption is reduced. An object of the present invention is to provide a liquid processing method and a liquid processing apparatus capable of suppressing waste.

[0015]

According to the liquid processing method of the present invention which can attain the above object, the present invention provides a liquid processing method in which a pulsed electric power is supplied between an electrode pair to reform a liquid to be processed existing between the electrode pairs. In the liquid processing method, the electrode pair includes an electrode pair including an electrode electrically exposed to the liquid to be treated and an electrode protected so as not to be electrically exposed to the liquid to be treated. An electrode which is provided with at least two pairs of electrodes, and which is electrically exposed to the liquid to be treated in one electrode pair in two pairs of electrodes arbitrarily selected from the pair of electrode pairs, and the liquid to be treated in the other electrode pair It has a gist in that it is operated by electrically connecting electrodes protected so as not to be electrically exposed to each other, and two pairs of the above-mentioned electrode pairs are provided,
The electrode in one electrode pair electrically exposed to the liquid to be treated and the electrode in the other electrode pair protected from being electrically exposed to the liquid to be treated are electrically connected to each other to operate. You may.

Further, the liquid processing apparatus of the present invention which can achieve the above object is configured such that a pulsed electric power is supplied between the electrode pairs to reform the liquid to be treated existing between the electrode pairs. In the liquid processing apparatus, the electrode pair includes an electrode electrically exposed to the liquid to be processed, and an electrode pair including an electrode protected so as not to be electrically exposed to the liquid to be processed.
An electrode electrically exposed to the liquid to be treated in one electrode pair in two electrode pairs arbitrarily selected from the pair of electrode pairs, and a treatment target in the other electrode pair. It has a gist in that it is configured such that electrodes protected so as not to be electrically exposed to the liquid are electrically connected to each other, and two pairs of the above electrode pairs are provided, and one of the electrode pairs is provided. The electrode electrically exposed to the liquid to be treated in the above and the electrode of the other electrode pair protected so as not to be electrically exposed to the liquid to be treated are electrically connected to each other. You may.

At least the above-mentioned device of the present invention
At least two liquid processing containers having one set of electrode pairs may be connected via a pipe, and it is more preferable that a member having a semipermeable membrane or a small hole is provided in the pipe.

In order to protect one of the two pairs of electrodes, an insulator or a semiconductor may be used, and the other of the two pairs of electrodes may be used. It is more preferable to use an electrode having a metal member attached to the surface facing the electrode.

Further, one of the two electrode pairs and one of the other electrode pairs are connected on a connection for making an electrical connection therebetween. If an electric element for increasing the impedance is provided, the object of the present invention can be efficiently achieved, and it is more preferable that the electric element has a variable impedance.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present inventors have studied from various angles in order to solve the above problems. As a result, during liquid processing, an electrode that is electrically exposed to the liquid to be treated (hereinafter sometimes referred to as a “first electrode”) and an electrode that is protected from being electrically exposed to the liquid to be treated (Hereinafter sometimes referred to as “second electrode”), and at least two pairs of these electrodes are provided,
The operation is performed by supplying pulsed power to the first electrode of the two electrode pairs arbitrarily selected from the pair of electrode pairs and the second electrode of the other electrode pair electrically connected to each other. For example, the present inventors have found that the above-mentioned problem can be achieved brilliantly, and completed the present invention. Incidentally, the electrically exposed electrode may be, in addition to the conventionally used electrode, a plated or the like for improving corrosion resistance, corrosion resistance, etc.
The coating material is a conductor, and the electrode must be in a state capable of supplying electricity to the liquid to be treated. Further, an electrode protected so as not to be electrically exposed means that the electrode itself is immersed in the liquid to be treated, but the electrode is coated with an insulator or a semiconductor, or directly on the electrode itself. An electrode which is protected by an insulator or the like so as to cover the electrode without being in contact with the electrode, and means an electrode which is configured such that the electrode itself does not conduct electricity to the liquid to be treated as much as possible.

As described above, when an electrode pair consisting of an electrode electrically exposed to the liquid to be treated and an electrode protected so as not to be electrically exposed to the liquid to be treated is used, the leakage current between the pair of electrodes is reduced. Can be reduced or prevented.
However, if there is a small leakage current that could not be prevented, the leakage current flows in the liquid to be treated, Joule loss occurs due to the leakage current, and the energy efficiency and the processing efficiency deteriorate. Therefore, in a liquid processing apparatus provided with a plurality of pairs of electrodes configured as described above, an arbitrarily selected 2
The electrode (first electrode) of the pair of electrode pairs electrically exposed to the liquid to be treated and the electrode (second electrode) of the other electrode pair protected from being electrically exposed to the liquid to be treated are mutually connected. And operating by supplying pulsed power, the flow of the leakage current can be controlled so as to connect the first electrodes to each other, resulting in a closed circuit. As a result, generation of leakage current can be suppressed. By suppressing the leakage current, it is possible to control the occurrence of Joule loss due to the leakage current, suppress the rise in the water temperature of the liquid to be treated, and suppress the waste of energy.

Hereinafter, the structure and operation and effect of the present invention will be described in more detail with reference to the drawings. However, the structure shown below does not limit the present invention, and is designed in accordance with the above and following points. All modifications are included in the technical scope of the present invention.

FIG. 3 is a schematic explanatory view schematically showing one configuration example of the device according to the present invention. The liquid processing apparatus shown in FIG. 3 includes a processing container 22a and a processing container 22b, and the two processing containers are connected by a pipe 31. Processing container 22
a and 22b are rod-shaped electrodes 2 electrically exposed to the liquid 23 to be treated.
5a and 25b are insulators so that they are not electrically exposed to the liquid to be treated.
The ring-shaped electrodes 26a and 26b protected by 30 are arranged on the same axis. The rod-shaped electrode 25a and the ring-shaped electrode 26b are electrically connected to each other, and the rod-shaped electrode 25b and the ring-shaped electrode 26a are electrically connected to each other. When a rapidly rising pulse voltage is applied from the high voltage pulse power supply 27 to the electrodes connected as described above, a three-dimensional planar discharge 24 occurs between each pair of electrodes. The three-dimensional planar discharge can be applied to a wider range than the linear discharge, and the processing efficiency is improved.

The electrode pair is composed of the electrode electrically exposed to the liquid to be treated as described above and the electrode protected from being electrically exposed to the liquid to be treated. For example, it is possible to suppress the generation of a leakage current flowing in the direction in which the rod-shaped electrode 25a and the ring-shaped electrode 26a in the processing container 22a are connected, and it is possible to prevent the leakage current connecting the electrodes electrically exposed to the liquid to be processed. Current 28 flows via line 31. Suppressing the leakage current 28 in the direction in which the discharge occurs and consolidating the leakage current 28 into a substantially single flow in this manner has the effect of suppressing the generation of the leakage current 28 itself, and the above object is achieved.

FIG. 3 shows a processing vessel including one set of an electrode pair consisting of an electrode electrically exposed to the liquid to be treated and an electrode protected so as not to be electrically exposed to the liquid to be treated. Is shown, but the number of processing vessels is not particularly limited, and thus electrically connected.
A plurality of liquid processing containers including two pairs of electrodes may be connected via a conduit. Further, at least two sets of electrode pairs configured as described above may be provided in one processing vessel.In this case, two sets of electrode pairs are arbitrarily selected from a plurality of sets of electrode pairs, and The electrodes may be electrically connected as shown in FIG. In the case where the number of electrode pairs is an odd number, the last one may be connected in a conventional manner (see FIG. 2). Further, it is also within the scope of the present invention to connect a plurality of processing vessels configured such that a plurality of electrode pairs are connected in one processing vessel as described above via a pipeline, and the processing efficiency is reduced. Further improve.

A rod-shaped electrode electrically exposed to the liquid to be treated and an insulator 30 so as not to be electrically exposed to the liquid to be treated.
Although the ring-shaped electrode protected by the above is used, the electrode protected by the insulator 30 is not limited to the ring-shaped electrode, and may be configured to protect the rod-shaped electrode side. That is, an electrode pair including a ring-shaped electrode electrically exposed to the liquid to be treated and a rod-shaped electrode protected by the insulator 30 so as not to be electrically exposed to the liquid to be treated may be formed. Here, the material for protecting the liquid to be treated so as not to be electrically exposed to the liquid to be treated is not particularly limited as long as it exhibits the function as described above, but, for example, ceramics, polyethylene, Teflon (registered trademark) or the like can be preferably used. Further, instead of an insulator, a so-called semiconductor member may be used. The member may have an impedance sufficiently higher than that of the liquid to be treated, and specifically, may have an impedance of 100 Ω / cm or more.

FIG. 4 shows another example of the configuration of the apparatus according to the present invention. The same reference numerals are given to the portions corresponding to FIG. 3 to avoid redundant description. In FIG. 4, the processing vessel 2
2a and 22b are connected by a conduit 31, and a semipermeable membrane 36 is provided inside the conduit 31.
Is interposed. When configured as shown in FIG. 4, a large amount of ozone and OH radicals are generated on one electrode to promote the oxidation reaction, whereas a large amount of H radicals are generated on one electrode and the reduction reaction is promoted. Therefore, when the semipermeable membrane 36 is provided in the conduit 31, the solid sludge component in the liquid to be treated does not move between the containers, but only the generated radicals and the liquid to be treated can move, thereby controlling the flow of the leakage current. The oxidation reaction or the reduction reaction can be individually performed in each of the processing vessels while keeping the same. Further, the semipermeable membrane is in the middle of the flow of the leakage current 28, and the semipermeable membrane 36 has a role of an inclusion having a predetermined impedance. By making the impedance appropriate, it is possible to reduce the leakage current itself. From this viewpoint, the member interposed in the conduit 31 is not limited to the semipermeable membrane 36, but may be an insulator, a semiconductor, or a metal member having many small holes. Further, a metal or a porous metal that is not electrically connected may be added.

FIG. 5 shows another configuration example of the device according to the present invention, and the main parts are the same as those in FIG. In the apparatus shown in FIG. 5, in addition to the configuration of the apparatus shown in FIG. 3, a variable resistance element 32 is provided on the connection between the rod-shaped electrodes 25a and 25b, and the liquid discharged from the liquid processing apparatus is provided. And a control device 34 for controlling the resistance of the variable resistance element 32 based on the value measured by the measurement device. As in the case of FIG. 3, the leakage current 28 flows so as to connect the rod-shaped electrodes 25a and 25b that are electrically exposed to the liquid 23 to be treated, thereby forming a closed circuit and reducing the leakage current 28. Furthermore, the variable resistance element 32 has a proper impedance so that the leakage current 28 is reduced most.
Is set, leakage current 28 can be further suppressed. As shown in FIG. 5, in a configuration having a conductivity or impedance measuring device 33 and a control device 34, the control device 34
Is configured to hold the “appropriate impedance of the liquid to be treated” corresponding to the above “appropriate impedance” in the internal storage means, and to control the variable resistance element 32 so as to achieve such conductivity. It is desirable to keep.

In FIG. 5, although the variable resistance element 32 is used, for example, if the proper impedance of the electric resistance element to be interposed is recognized empirically, the variable resistance element 32 need not be used. Alternatively, a resistance element such as a coil or a coil may be used.

Further, when the electrode 24 is protected only by the insulator 30 as in the ring-shaped electrode 26a shown in FIG. 3, when the discharge 24 reaches the surface of the insulator 30, a local melting of the insulator 30 occurs. Failures such as loss or insulation deterioration may occur. Therefore, as shown in FIG. 5, by providing a metal member 35 along the inner periphery of the insulator 30 that protects the ring-shaped electrodes 26a and 26b, facing the rod-shaped electrodes 25a and 25b, The influence from the discharge can be prevented by the metal member 35, and the inconvenience can be suppressed.

[0031]

The present invention is configured as described above. When a pulsed electric power is supplied between the electrode pairs to reform the liquid existing between the electrode pairs, the leakage current to the liquid to be treated is reduced. While reducing as much as possible, controlling the flow of minute leakage current that could not be suppressed, the occurrence of Joule loss due to leakage current is suppressed, and the rise in water temperature of the liquid to be treated is suppressed,
A liquid processing method and apparatus capable of suppressing energy waste can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a horizontal structure of a processing device proposed by the present inventors.

FIG. 2 is a schematic explanatory view showing an example of an arrangement state of electrodes and a discharge state in a processing container.

FIG. 3 is a schematic explanatory view schematically showing a configuration example of an apparatus according to the present invention.

FIG. 4 is a schematic explanatory diagram schematically showing another configuration example of the device according to the present invention.

FIG. 5 is a schematic explanatory view schematically showing another configuration example of the device according to the present invention.

[Explanation of symbols]

 1 Activated sludge tank (aeration tank) 2 Precipitation device 3 Reforming tank 4 Power supply 5, 25, 25a, 25b Rod electrode 6 Plate electrode 7, 8, 9, 12, 15 Route 10 Precipitated sludge 11, 13 Return route 16, 17 Pump 18 Reformer 20 Supernatant 22, 22a, 22b Processing vessel 23 Liquid to be treated 24 Discharge 26, 26a, 26b Ring electrode 27 High voltage pulse power supply 28 Leakage current 30 Insulator 31 Pipe line 32 Variable resistance element 33 Conductivity Rate or impedance measurement device 34 Control device for controlling the variable resistance element 35 Metal member 36 Semi-permeable membrane

Claims (10)

[Claims] 1. A liquid processing method for reforming a liquid to be treated existing between electrode pairs by supplying pulsed power between the electrode pairs, wherein the electrode pairs are electrically exposed to the liquid to be treated. Electrodes and
It is composed of an electrode pair consisting of electrodes protected so as not to be electrically exposed to the liquid to be treated, and comprises at least two pairs of these electrode pairs, and two electrode pairs arbitrarily selected from the pair of electrode pairs. Operate by electrically connecting the electrodes of one electrode pair that are electrically exposed to the liquid to be treated and the electrodes of the other electrode pair that are protected from being electrically exposed to the liquid to be treated. A liquid processing method characterized by the above-mentioned. 2. An electrode pair comprising two pairs of the above-mentioned electrodes, which is electrically exposed to the liquid to be treated in one electrode pair and protected from being electrically exposed to the liquid to be treated in the other electrode pair. Claims that operate by electrically connecting the electrodes to each other
2. The liquid treatment method according to 1. 3. A liquid processing apparatus configured to supply a pulsed electric power between an electrode pair to reform a liquid to be processed existing between the electrode pairs, wherein the electrode pair electrically connects the liquid to be processed with the liquid. Electrodes exposed to the
It is composed of an electrode pair consisting of electrodes protected so as not to be electrically exposed to the liquid to be treated, and comprises at least two pairs of these electrode pairs, and two electrode pairs arbitrarily selected from the pair of electrode pairs. An electrode electrically exposed to the liquid to be treated in one electrode pair and an electrode protected to not be electrically exposed to the liquid to be treated in the other electrode pair are electrically connected to each other. A liquid processing apparatus, comprising: 4. An electrode pair provided with two sets of electrodes, which is electrically exposed to the liquid to be treated in one electrode pair and protected from being electrically exposed to the liquid to be treated in the other electrode pair. 4. The liquid processing apparatus according to claim 3, wherein the liquid processing apparatus is configured to electrically connect the electrodes to each other. 5. The liquid processing apparatus according to claim 3, wherein at least two liquid processing containers each having at least one pair of electrodes are connected via a pipe. 6. The liquid processing apparatus according to claim 5, wherein a member having a semipermeable membrane or a small hole is interposed in the conduit. 7. The semiconductor device according to claim 1, wherein one of said two pairs of electrodes is protected by an insulator or a semiconductor.
7. The liquid processing apparatus according to any one of 3 to 6. 8. A metal member is provided on a surface of one of the two pairs of electrodes facing the other electrode.
8. The liquid processing apparatus according to any one of items 7 to 7. 9. A connection for making an electrical connection between one electrode of one of the two pairs of electrodes and one electrode of the other pair of electrodes on the connection. An electric element for increasing the impedance of
The liquid processing apparatus according to any one of the above. 10. The liquid processing apparatus according to claim 9, wherein the electric element has a variable impedance.