JP2002001350A - Liquid treating method and its apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient and economically advantageous high-voltage liquid treating method in which a liquid is sufficiently reformed with a small amount of power, and a useful device for applying such a method. SOLUTION: At least a pair of electrodes are provided, at least one electrode between the electrodes is dipped in a liquid, a pulsed power is supplied between the electrodes to form a discharge between the electrodes, and the liquid between the electrodes is reformed by this method. In this case, the voltage or current of the supplied power is detected, and the power supply is stopped when the value is fluctuated by more than a specified amount per minute time to continue the operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to (1) a biological aerobic process of an organic waste liquid 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. Or anaerobic treatment, (2) sterilization / sterilization of treated water, water and sewage water, food and drinking water in the process of producing pure water, wastewater (including non-organic wastewater) of each factory. Treatment, decolorization treatment, deodorization treatment, or (3) sterilization / sterilization treatment of the above various liquids, decolorization treatment,
A liquid treatment method that appears during deodorization or leachate from a garbage incinerator and is applied to the decomposition of dioxin, environmental hormones, PCBs, and other hardly decomposable substances, and a liquid treatment method such as this. The present invention relates to an apparatus used for carrying out the method.

[0002]

2. Description of the Related Art In various applications described in the above (1) to (3), for example, as a method for purifying a liquid by killing harmful bacteria contained in the liquid, or as a method for purifying the liquid. In order to reduce the volume of polluted components consisting of bacteria and their dead bodies, high-voltage pulse discharge is applied to the above liquid as a method of reforming the polluted components to a state that can be biochemically treated by aerobic microorganisms. A so-called high voltage processing method for processing a liquid by performing processing and / or applying an electric field pulse is known. The present inventors have proposed a technique as disclosed in, for example, JP-A-11-253999 as such a high-voltage processing method and an apparatus therefor.

FIG. 1 is a diagram schematically showing an example of the configuration of a high-voltage processing device proposed by the present inventors. In this device, the target liquid (liquid to be processed) is an organic waste liquid. So,
It is assumed that the organic waste liquid is biologically aerobicly treated.

In the apparatus shown in FIG. 1, first, an organic waste liquid is introduced into a activated sludge tank (aeration tank) 1 from a passage 7 and aerated while mixing the activated sludge in the activated sludge tank 1 with the organic waste liquid. I do. Activated sludge contains aerobic microorganisms,
The organic pollutants in the organic waste liquid are decomposed into carbon dioxide and water by the aerobic microorganisms, and the organic pollutants are assimilated into microorganisms to proliferate activated sludge.

[0005] The treated liquid mixture is introduced into the precipitation apparatus 2 through a path 8 and is separated into a supernatant 20 and a precipitated sludge 10 by solid-liquid separation. The supernatant 20 is discharged from the path 9 as treated water. You. In addition, this treated water is subjected to higher-order treatment (nitrification denitrification treatment, ozone treatment, etc.) as necessary according to the discharge standard of the discharge destination
It is released.

On the other hand, a part of the settled sludge 10 is returned to the activated sludge tank 1 from a return path 11 by a pump 16 and becomes a microbial source in the activated sludge tank 1, and a part of the settled sludge 10 From 12 is introduced into the reforming tank 3 of the reformer 18 by the pump 17. The reformer 18
Is provided with a reforming tank 3 and a power supply 4 so that a rod electrode (+ pole) 5 and a flat plate electrode (-pole) 6 connected to the power supply 4 are immersed in the sludge in the reforming tank 3. Are arranged in parallel.
The sludge (precipitated sludge 10 introduced from the sedimentation device 2) inside the reforming tank 3 can be electrically regarded as a dielectric having a predetermined dielectric constant. When positive and negative charges are respectively applied to the electrodes 5 and 6 by applying a voltage in a state where the electric field is satisfied, an electric field is formed in the dielectric (sludge). Breakage occurs and discharge occurs between the electrodes 5 and 6.

By subjecting the high-voltage pulse discharge treatment between the electrodes 5 and 6 as described above, the precipitated sludge is solubilized and reduced in molecular weight (reformed). That is, microorganisms in the settled sludge are killed by the high-voltage pulse discharge, and are further decomposed by cell destruction to produce low-molecular-weight organic and inorganic substances.Organic substances other than microorganisms are also reduced to a low-molecular-weight aerobic microorganism. It becomes an easily decomposable substance (hereinafter sometimes referred to as modified sludge).

[0008] In such a technique, the same effect can be obtained by applying an electric field pulse application process to sludge instead of performing a high voltage pulse discharge process. That is, when the setting of the applied voltage is lower than the voltage at which the sludge causes dielectric breakdown,
In the case where the distance between the electrodes is large and the capacity between the electrodes is large, the discharge phenomenon does not occur, but even in such a case, a voltage (so-called critical voltage) at which individual cells in the sludge can be destroyed. If an electric field is formed between the electrodes by applying the electric field (electric field pulse application processing), the sludge is reformed. In addition to the case where the high-voltage pulse discharge process or the electric field pulse application process is performed alone, these processes can be performed in combination.

Next, the reformed sludge generated in the reformer 18 is returned from the return path 13 to the activated sludge tank (aerobic treatment tank) 1. In the activated sludge tank 1, the modified sludge is decomposed by aerobic microorganisms as bait.

[0010] Thus, sludge is discharged with a high voltage pulse and / or
Alternatively, the activated sludge tank 1 is modified by applying an electric field pulse.
By recycling the sludge, the sludge is reduced in volume, and as a result, the amount discharged as excess sludge is reduced. The surplus sludge is discharged out of the system via the passage 15.

[0011]

Normally, when a high voltage is applied between electrodes immersed in a liquid, a correspondingly high electric field is formed between the electrodes, and this high electric field causes a so-called primary avalanche. It is formed. In this primary avalanche avalanche path, some residual negative ions (negative ion group) are generated by the attachment action of electrons and positive ions. The amount of charge in the liquid is a predetermined amount of space charge composed of the sum of the residual negative ions and the charge that has existed before, and the electric field in the liquid is between the electric field composed of this space charge and the electrodes in the first place. A combined electric field is formed by combining the applied electric field with the applied high voltage.

If the combined electric field becomes sufficiently large, electrons generated by photoionization during the development of the primary avalanche grow as a secondary avalanche toward the center of gravity of the residual ion group. Due to the primary avalanche and the secondary avalanche, a thin plasma is formed. This is a phenomenon called streamer (discharge).

The streamer discharge is not always maintained in a stable state, but may change to another discharge state in some cases. For example, a thin streamer discharge may transition to another form of discharge where a positive column is formed between the electrodes. Such transition naturally depends largely on how the streamer discharge propagates between the electrodes.

By the way, in the high voltage processing method as described above, the processing is performed in a state where the streamer discharge and the discharge such as the arc discharge other than the streamer which changes after the streamer is generated coexist. It is general, and the treatment efficiency in the reforming treatment of the liquid to be treated under such circumstances is not always sufficient. In other words, in the case of electric discharge such as arc discharge, the reforming of the liquid to be treated does not proceed sufficiently for a large amount of current to flow and consumes a large amount of power, and the desired high voltage treatment effect cannot be obtained. There was a problem. In addition, when an arc discharge or the like has occurred, there has been a situation in which a specific noise is generated.

Accordingly, the present invention has been made in view of the above situation, and an object of the present invention is to enable liquid reforming to be sufficiently performed with a small amount of electric power, to be highly efficient and economically advantageous. An object of the present invention is to provide a liquid processing method and a useful apparatus for performing the method.

[0016]

According to the liquid processing method of the present invention which can achieve the above object, at least one pair of electrodes is provided, and at least one electrode of the electrode pair is immersed in a liquid. In a liquid processing method for reforming a liquid present between electrode pairs by supplying a pulsed power between the electrode pairs to form a discharge state between the electrode pairs, the voltage or current of the supplied power is The gist is that the operation is performed such that the supply of the power is stopped when the detected value is changed by a predetermined amount or more per minute time.

Further, the liquid processing apparatus of the present invention which has achieved the above object has at least one pair of electrodes,
At least one electrode of the electrode pair is disposed so as to be immersed in a liquid, and a pulsed power is supplied between the electrode pair to form a discharge state between the electrode pair, thereby forming a discharge state between the electrode pair. In a liquid processing apparatus for reforming an existing liquid, a detection unit for detecting a voltage or a current of the supplied power, a switching unit provided in a power supply path to the electrode pair, and a detection unit for detecting the voltage or the current. The gist is that a control means is provided for controlling the switching means and stopping the supply of the power when the value is changed by a predetermined amount or more per minute time.

An object of the present invention is to control a pulse length of a voltage or a current of electric power supplied to a liquid to be equal to or less than a predetermined time during which a discharge generated in the liquid at the time of supplying electric power to the liquid maintains a streamer. It is achieved even if it operates.

Further, as an apparatus configuration for implementing such a method, there is provided a pulse length adjusting means for adjusting a pulse length by a voltage or a current of electric power supplied to the liquid, and the pulse length is adjusted by the power supply to the liquid. There is an apparatus that is configured so that the discharge sometimes generated in the liquid is set to a predetermined time or less for maintaining the streamer.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, with the above-described configuration, it is possible to prevent high voltage processing from being performed in a state where discharges other than streamers, such as arc discharges, are mixed. As a result, high-voltage processing can be performed by discharging in a streamer state that enables high-efficiency processing. In addition, it is possible to avoid generation of abnormal noise peculiar to arc discharge or the like.

FIG. 2 is an explanatory diagram schematically showing a state of discharge between an anode (anode) and a cathode (cathode). When the streamer discharge reaches the cathode, the streamer discharge changes to an arc discharge.This transition requires a predetermined minute time, and if a predetermined amount of fluctuation in the voltage or current is observed within this time, By stopping the streamer discharge, it is possible to avoid a state in which the streamer discharge and the discharge such as the arc discharge other than the streamer that changes after the occurrence of the streamer discharge are mixed, and the above-described inconvenience occurs. Was prevented. Alternatively, it has also been found that the same effect as described above can be achieved even when the discharge generated in the liquid to be processed when a high voltage is applied is maintained within a predetermined time for maintaining the streamer.

According to experiments by the present inventors, when ordinary distilled water or tap water was used as the liquid to be treated, the streamer discharge speed was 30 mm.
/ Μsec. Also, according to this experiment, it was confirmed that the streamer propagated at a substantially constant speed without much depending on the magnitude of the applied voltage, and it was also found that the value was the above value. However, if the type of the liquid to be treated is different, it was confirmed that a slight difference was recognized in the value of the speed of the streamer discharge.
Since the streamer propagates at a substantially constant speed without much depending on the magnitude of the applied voltage, it is the same. Therefore, the streamer discharge speed may be detected according to the type of the liquid to be treated.

Hereinafter, the structure and operation and effect of the present invention will be described more specifically with reference to the drawings. However, the structure shown below is not intended to limit the present invention, and design changes are made in accordance with the above and subsequent points. Whatever is done is included in the technical scope of the present invention.

FIG. 3 is an explanatory diagram schematically showing an example of the configuration of the apparatus according to the present invention. In FIG.
Reference numeral 6 denotes a high-voltage switch unit, 27 denotes a processing container, 28 denotes a voltage detection unit, and 29 denotes discharge. Equation 1 for high voltage power supply 25
A voltage of 0 kV or more (preferably, about 70 kV) can be applied. Although the high-voltage switch section 26 has a mechanical switch configuration in FIG. 3, the high-voltage switch section 26 uses a switching means such as a thyratron or a magnetic switch capable of high-repetition operation. Thereby, the voltage from the high voltage power supply 25 can be pulsed. Further, at this time, by employing the switching means, application of a high voltage having a predetermined value or more for a predetermined time or more is not allowed.

The processing vessel 27 corresponds to the reforming tank 3 shown in FIG. 1. The pulse-shaped (usually rectangular wave) high voltage is supplied to the processing vessel 27. Then, a liquid to be processed (not shown) is supplied to the processing container 27, and the processing is performed by the supplied high voltage pulse and / or high electric field pulse (discharge 29). Further, the voltage detecting unit 28 detects a potential difference (voltage) in the processing container 27 (load side).

In the apparatus shown in FIG.
Shows a configuration in which a pair of electrodes are provided, but the number of electrode pairs can be two or more. In addition, in this device, the electrode is immersed in the liquid in a state where both the anode electrode and the cathode electrode are usually immersed. However, when at least one of the electrodes is immersed, the above-described discharge occurs. The state is achieved.

In the apparatus configuration shown in FIG. 3, the voltage applied to the processing container 27 (ie, the voltage applied to the liquid to be processed) is detected by the voltage detecting section 28, and the value is detected by a predetermined amount per minute time. When the above fluctuation is recognized, it indicates that the streamer discharge changes (or shifts) to arc discharge. Then, during the transition to the arc discharge, by controlling the high voltage switch unit 26 to the “open” state, the power of the power supply can be reduced, and the transition from the streamer discharge to the arc discharge is stopped, or Transitions can be kept to a minimum.

That is, the streamer discharge maintains the discharge in a state where the voltage is high, and the arc discharge maintains the discharge in the state where the voltage is low and the current is large. , The voltage between the anode and the cathode suddenly drops. And
By detecting this voltage drop (for example, about 1 kV or more) and turning off the discharge energy by setting the high-voltage switch section 26 to the "open" state, it is possible to prevent the transition from streamer discharge to arc discharge. Alternatively, the transition to arc discharge can be minimized, and the occurrence of a state where streamer discharge and arc discharge coexist can be avoided. In addition, by adopting such a configuration, the liquid to be treated can be sufficiently reformed with a small amount of electric power, which is highly efficient and economically advantageous. The “small time” means several n (nano) seconds to 1 μ (micro) seconds.

In the above configuration, the high-voltage switch section 26 is also configured to also perform high-voltage pulse shaping.
Alternatively, a pulse voltage may be applied to the processing container 27 even if such a configuration may be employed as to connect a lseforming line (PFL) (FIG. 5 described later) or incorporate the high voltage power supply 25. When such a configuration is adopted, a normal mechanical switch may be used as the high-voltage switch section 26.

FIG. 4 is an explanatory diagram schematically showing another configuration example of the device according to the present invention. In this device, a current detecting unit 30 is provided instead of the voltage detecting unit 28 in FIG. Are the same as those shown in FIG. 3, and corresponding portions are denoted by the same reference numerals to avoid duplication. Therefore, the principle of pulse formation and the mechanism of the high voltage switch unit 26 in the device shown in FIG. 4 are the same as those described above.

In the apparatus configuration shown in FIG. 4, the current applied to the processing vessel 27 (ie, the current applied to the liquid to be processed) is detected by the current detecting unit 30 and the value is detected by a predetermined amount per minute time. When the above fluctuation is recognized, the transition from the streamer discharge to the arc discharge can be prevented or minimized by setting the high voltage switch section 26 to the “open” state.

That is, as described above, the current at the time of streamer discharge is small, and the arc discharge is maintained in a state where the current is large. Will increase. Then, the increase of this current (for example, 100 to 1)
000A or more) and detects the high voltage switch unit 26
By turning off the energy of the discharge 29 in the "open" state, preventing the transition from streamer discharge to arc discharge or minimizing the transition to arc discharge, and the state where streamer discharge and arc discharge are mixed Can be avoided.

FIG. 5 is an explanatory view schematically showing still another example of the configuration of the apparatus according to the present invention. In this apparatus, the voltage pulse shaping unit 31 includes the high-voltage switch unit 26a and the voltage pulse shaping unit 31 includes the high-voltage switch unit 26a. It is configured as a mandatory requirement. It should be noted that, as described above, the pulse shaping unit 31
FL, but preferably a Bloomline path.

When the pulse forming unit 31 is formed in the Bloom line path, if the voltage of the high-voltage power supply 25 is V ₀ , the length of the transmission line is L, and the propagation speed of the voltage wave is v, the load side A rectangular wave pulse (FIG. 6) having a wave height V ₀ and a pulse length of 2 L / v is supplied (for example, “High-voltage pulse power optics”, Morikita Publishing, p. 171). In the present invention, the pulse length of the voltage is set to be equal to or shorter than a predetermined time so that the discharge generated in the liquid to be treated when the voltage is applied maintains the streamer.

In order for the discharge to maintain the streamer, it can be achieved by first stopping the applied voltage until the streamer is generated from one electrode and reaches the other electrode. Therefore, assuming that the length between the electrodes is R and the propagation speed of the streamer discharge is v ′ (depending on the type of liquid and not depending on the applied voltage), the pulse forming unit is required to satisfy the following equation (1). What is necessary is just to configure. (2L / v) <(R / v ') (1)

If a variable capacitance capacitor and a variable inductance are provided in the bloom line, the value of v can be changed as appropriate, and the pulse length can be adjusted so as to satisfy the above equation (1). In the above description, the case where the pulse length of the voltage is adjusted has been described. However, it is needless to say that the pulse length due to the current may be adjusted in exactly the same manner.

As described above, the pulse length adjusting means 31 is added to the output side of the high-voltage power supply 25 to adjust the pulse length, and the pulse length is adjusted so as to satisfy the above equation (1). By setting to, to prevent transition from streamer discharge to arc discharge before transition to arc discharge or minimize the transition to arc discharge,
It is possible to avoid occurrence of a state where streamer discharge and arc discharge are mixed.

In setting the pulse length to a predetermined time or less, the time may be determined from the discharge distance between the anode (anode) and the cathode (cathode). For example, assuming that the streamer discharge speed is about 30 mm / μsec as described above and the discharge distance between the anode (anode) and the cathode (cathode) is 30 mm, the pulse length is about 1 mm.
μsec.

[0039]

Industrial Applicability The present invention is constituted as described above, is capable of sufficiently reforming a liquid with a small amount of electric power, is highly efficient and economically advantageous, and a method for treating a liquid. A useful device for implementing the above was realized.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing an example of an apparatus configuration for performing a high-voltage processing method.

FIG. 2 is an explanatory diagram schematically showing a state of discharge between an anode and a cathode.

FIG. 3 is an explanatory diagram schematically showing one configuration example of the device according to the present invention.

FIG. 4 is an explanatory view schematically showing another configuration example of the device according to the present invention.

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

FIG. 6 is an explanatory diagram illustrating an example of an output voltage waveform of a rectangular wave pulse.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Activated sludge tank 2 Precipitation apparatus 3 Reforming tank 4 Power supply 5 Bar electrode 6 Plate electrode 7, 8, 9, 12, 15, 21 Path 10 Precipitated sludge 11, 13, 22 Return path 16, 17, 19 Pump 18 Reforming Apparatus 20 Supernatant 25 High voltage power supply 26 High voltage switch unit 27 Processing container 28 Voltage detection unit 29 Discharge 30 Current detection unit

Continued on the front page (72) Inventor Junji Haga 2-3-1 Shinhama, Arai-machi, Takasago City, Hyogo Prefecture Inside Takasago Works, Kobe Steel Ltd. (72) Inventor Masahiko Miura 1-5-5 Takatsukadai, Nishi-ku, Kobe Stock Company Kobe Steel, Kobe Research Institute F-term (reference) 4D061 DA08 DB01 DB19 DC03 DC04 DC09 DC10 EA15 EB01 EB07 EB14 EB34 EB39 FA15 GC20 4G075 AA13 AA37 BA05 CA15 DA01 EC21 FB02 FB04 FB12 FC13 FC15

Claims (4)

[Claims] At least one pair of electrodes is provided,
At least one of the electrode pairs is immersed in a liquid, and pulsed power is supplied between the electrode pairs to form a discharge state between the electrode pairs, thereby modifying the liquid existing between the electrode pairs. In the liquid treatment method, the voltage or current of the supplied power is detected, and when the value of the voltage or the current fluctuates by a predetermined amount or more per minute time, the supply of the power is stopped to operate. Characteristic liquid treatment method. 2. At least one pair of electrodes,
At least one electrode of the electrode pair is disposed so as to be immersed in a liquid, and a pulsed power is supplied between the electrode pair to form a discharge state between the electrode pair, thereby forming a discharge state between the electrode pair. In a liquid processing apparatus for reforming an existing liquid, a detection unit for detecting a voltage or a current of the supplied power, a switching unit provided in a power supply path to the electrode pair, and a detection unit for detecting the voltage or the current. A liquid processing apparatus comprising: control means for controlling the switching means and stopping the supply of the electric power when the value is changed by a predetermined amount or more per minute time. 3. At least one pair of electrodes is provided,
At least one of the electrode pairs is immersed in a liquid, and pulsed power is supplied between the electrode pairs to form a discharge state between the electrode pairs, thereby modifying the liquid existing between the electrode pairs. In the method for treating liquid, the operation is performed while controlling the pulse length of the voltage or current of the electric power supplied to the liquid to a predetermined time or less in which the discharge generated in the liquid when the electric power is supplied to the liquid keeps the streamer. A liquid processing method characterized by the above-mentioned. 4. At least one pair of electrodes,
At least one electrode of the electrode pair is disposed so as to be immersed in a liquid, and a pulsed power is supplied between the electrode pair to form a discharge state between the electrode pair, thereby forming a discharge state between the electrode pair. In a liquid processing apparatus for reforming an existing liquid, a pulse length adjusting means for adjusting a pulse length by a voltage or a current of electric power supplied to the liquid is provided, and the pulse length is adjusted when the electric power is supplied to the liquid. The liquid processing apparatus is characterized in that discharge generated in the liquid processing apparatus is set to a predetermined time or less for maintaining a streamer.