JP3573385B2 - Electrolyzer for electrolytic treatment of water to be treated - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to an electrolytic cell for electrolytic treatment of water to be treated for suppressing various performance deteriorations caused by the microorganisms in various kinds of water to be treated containing microorganisms, and more specifically, to a relatively large volume of treated water, for example, Photographic processing solutions, pure water from various factories, ultrapure water or pool water, paper washing water, cooling water for heat exchangers, drinking water (tap water), storage for cup-type vending machines, water for fish farming, chemical dilution water, baths Use of a carbon electrode for electrolytic treatment of water to be treated containing microorganisms such as water and circulating water for gas washing towers, or of various kinds of water to be treated with the possibility of generating microorganisms, especially drinking water requiring improvement and retention of water quality. Regarding the electrolytic cell, especially the clogging of the carbon electrodeRiniThe present invention relates to an electrolytic cell that can prevent instability of the electrolysis operation caused by the electrolysis.
[0002]
[Prior art]
Conventionally, various kinds of aqueous solutions or single water or pure water in which other substances are not dissolved have been used for various purposes. In these aqueous solutions and the like, when the solute provides an appropriate nutrient, or when the temperature of the aqueous solution is a relatively high temperature suitable for propagation, microorganisms such as bacteria propagate and the microorganisms deteriorate the performance of the aqueous solution or the like. Often, they cause damage to the product, float or accumulate in the processing apparatus, and impair the function of the processing apparatus. The number of microorganisms in ordinary tap water is reduced to 30 / ml or less by leaving residual chlorine as a disinfectant. However, when this tap water is used as, for example, cooling water for a heat exchanger, the microorganisms proliferate dramatically. Corrosion and bad smell of piping occur.
Conventionally, in order to prevent these phenomena, various chemicals such as a fungicide and a precipitation inhibitor have been introduced into the water to be treated and various filters have been installed in the middle of the piping. It has been pointed out that adverse effects on the water to be treated due to residual chemicals and problems with the cost of using chemicals have been pointed out. Furthermore, there is a problem that antibacterial action against the added drug occurs after a while, and it is necessary to examine the next drug or to supply a drug in a larger amount than necessary. Further, in principle, it is impossible to filter and separate live bacteria by a filter operation, and permanent bacteria cannot be removed.
[0003]
Of the above-mentioned water to be treated, drinking water in particular is directly linked to human health, and it is essential to sterilize bacteria contained therein and prevent the growth of fungi, that is, kill and remove microorganisms. The main method is chlorine. However, in city water sterilization, river water and lake water, which are raw water, are contaminated with various organic substances and chlorine is added in excess of the amount necessary for the elimination of microorganisms. It has adverse effects such as occurrence. In order to solve the above-mentioned disadvantages caused by the chlorine method, sterilization methods other than the chlorine method have been proposed.
In order to solve the above-mentioned drawbacks in the respective treated waters including drinking water, the present applicant supplies the treated water to an electrolytic cell containing a plurality of carbonaceous three-dimensional fixed-bed electrodes and performs electrolytic treatment. Accordingly, a water treatment apparatus and method for sterilizing microorganisms in the water to be treated have been proposed.
[0004]
[Problems to be solved by the invention]
This so-called electrolytic sterilization method is to sterilize microorganisms that are in contact with the positively polarized electrode portion by polarizing the electrode by energizing the carbon electrode, and sterilization of the microorganisms is continued as long as the energization is continued. In addition, since chemicals such as chlorine and ozone are not used, there is an advantage that even if the treatment is performed for a long period of time, only a small amount of electricity is required and economical operation becomes possible.
However, the carbon electrode has a relatively small opening diameter and is likely to cause clogging, and is relatively brittle, so that the peripheral portion is chipped or suspended in an electrolytic cell as a fine powder to accelerate the clogging. There is a disadvantage that.
Due to the pressure of the water to be treated flowing in the electrolytic cell, the carbon electrode moves in the cell and comes into contact with the terminal electrode, so that the carbon electrode does not have a predetermined polarization.
[0005]
FIG. 1 is a longitudinal sectional view showing an example of a conventional electrolytic cell for treating water to be treated containing a carbon electrode.
The electrolytic cell 1 has a short columnar shape made of a carbonaceous material or the like inside an electrolytic cell body 6 having a water supply port 3 at the center of a bottom plate 2 and a water outlet 5 at a center of a top plate 4. Are accommodated so as to form a small gap with the inner wall of the main body 6 so that substantially no liquid flow occurs, and a power is supplied slightly above the uppermost carbon electrode 7. An anode terminal 8 for power supply is provided, and a cathode terminal 9 for power supply is provided slightly below the lowest carbon electrode 7. Also, four mesh-shaped diaphragms or spacers 10 are sandwiched between the carbon electrodes 7 and between the carbon electrodes 7 and the two electrode terminals 8 and 9.
The electrolytic cell 1 having such a configuration is installed, for example, in the middle of a water supply pipe or at a faucet of a water supply. When the water is supplied, the water to be treated first contacts the positively polarized lower surface of the carbon electrode 7 and sterilization of the microorganisms occurs mainly on the positively polarized surface. 7, that is, the negatively polarized surface, where precipitation of metals, decomposition of available chlorine components, and the like mainly occur.
[0006]
From the viewpoint of microbial sterilization, this electrolytic treatment operation shows that dead microorganisms accumulate in the positively polarized part where microbial sterilization occurs, and the negatively polarized part where the microbial sterilization effect is weak or the central part where substantially no polarization occurs. In the part, microorganisms may propagate, and as the number of microorganisms increases dramatically, the number of the microorganisms increases dramatically, so that the negatively polarized part and the central part of the carbon electrode are clogged by closing the opening of the electrode, There is a drawback that the flow of the water to be treated is hindered.
In the electrolytic treatment operation, the polarity of the polarization may be reversed by periodically inverting the anode terminal and the cathode terminal. In this case, the growth of microorganisms on both end surfaces of the carbon electrode 7 can be prevented, but clogging of the opening due to the growth of microorganisms at the center of the carbon electrode 7 cannot be prevented.
[0007]
Further, in the conventional electrolytic cell for electrolytic treatment of the water to be treated shown in FIG. 1, since the resistance of the water to be treated passing through each carbon electrode 7 is large, the water to be treated is electrolyzed from the water supply port 3 at a relatively high pressure. It is supplied into the tank body 6. Therefore, the carbon electrode 7, which does not have a large mechanical strength, is particularly lacking in its peripheral portion or is powdered by the high-speed flow of the water to be treated and suspended in the water to be treated. Once suspended in the water to be treated, it may pass through the mesh diaphragm or spacer 10 relatively easily and reach the upper carbon electrode 7, which may cause clogging of the carbon electrode 7.You.
[0008]
[Object of the invention]
Therefore, the present invention solves the above-mentioned drawbacks of the prior art, and the clogging of the carbon electrode in the electrolytic cell for electrolytic treatment of the water to be treated using the carbon electrode.TheAn object of the present invention is to provide an electrolytic cell for electrolytic treatment of water to be treated, which is provided with an electrode which can be suppressed to a minimum and has almost ideal electrodes.
[0009]
[Means for solving the problem]
The present inventionIs 1Or two or more porous block-shaped or sponge-shaped three-dimensional fixed bed type carbon electrode, placed between the power supply anode terminal and the power supply cathode terminal, to supply treated water containing microorganisms to the carbon electrode. In an electrolytic cell for electrolytic treatment, electrolysis for electrolytic treatment of water to be treated in which the opening diameter or porosity of the carbon electrode in the flow direction of the treated water is varied.It is a tank. WhatIn the electrolytic cell according to the present invention, an electrochemical reaction such as a substantial oxidation-reduction reaction may not occur on the electrode surface, so the electrolytic cell according to the present invention should be called an electrochemical treatment tank. , According to a general name.
[0010]
Hereinafter, the present invention will be described in detail.
The electrolytic cell according to the present invention includes drinking water, water storage for cup-type vending machines, photographic processing solutions, pure water from various factories, ultrapure water or pool water, paper washing water, heat exchanger cooling water, fish farming water, and chemicals. Various treated water containing microorganisms such as dilution water, bath water and circulating water for gas cleaning towers, or other treated water that may generate microorganisms, especially drinking water that must sufficiently suppress the contamination of microorganisms, is to be treated. The water to be treated is supplied to the electrolytic cell for electrolytic treatment of the water to be treated according to the present invention, and a DC or AC voltage is applied to the electrolytic cell to sterilize, sterilize or sterilize the microorganisms in the water to be treated.
At this time, although the processing efficiency is not directly and immediately affected, the carbon electrode is clogged due to the above-mentioned disadvantages of the conventional carbon electrode.RihaIn the long term, the processing efficiency is reduced, and cost and time are lost due to replacement.
[0011]
The carbon electrode specificAbout cloggingDisadvantages,By the method described aboveIt is something to try to eliminate. The microorganism of the present invention includes bacteria (bacteria), fungi, filamentous fungi (molds), Escherichia coli, yeast, deformed fungi, unicellular algae, protozoa, viruses and the like.
In the present invention, the carbon electrode contained in the electrolytic cell for electrolytic treatment described above has a larger pore diameter or percentage of a portion where microorganisms are highly likely to grow than a portion where there is little possibility of microorganisms growing. It is characterized by the following. Specifically, the opening diameter or porosity of the non-positively polarized portion of the carbon electrode, that is, the portion that is negatively polarized and the portion that is not polarized, is made larger than the opening diameter or porosity of the positively polarized portion. With this configuration, the pore diameter or pore ratio of the portion that is positively polarized causing microbial sterilization is kept relatively small, and the water to be treated sufficiently contacts the wall surfaces of the pores inside the carbon electrode to be treated. While maintaining a sufficient killing effect of the microorganisms in the water, the microorganisms are not sufficiently killed and their propagation is liable to occur. It is possible to maintain the pore diameter or the pore ratio relatively large so that even if microorganisms propagate in the portion, the pores of the carbon electrode through which the water to be treated flows are not closed.
[0012]
As mentioned aboveThe present inventionIn the case of the carbon electrode, it is premised that the opening diameter or the opening ratio at both ends is smaller than the opening diameter or the opening ratio at the center, but the opening diameter at both ends to be anodic polarized is 20 to 500 μm. It is preferable that the non-polarized central portion has an opening diameter of 50 to 5000 μm.
The reason why the opening diameter at both ends is 20 to 500 μm is that if it is less than 20 μm, smooth flow of the water to be treated is hindered, and if it exceeds 500 μm, microorganisms that pass through the electrode without contacting the carbon electrode surface are generated. . The reason why the diameter of the opening at the center is 50 to 5000 μm is that if the diameter is less than 50 μm, there is no point in changing the diameter of the opening, and if it exceeds 5000 μm, the mechanical strength decreases.
Further, the more preferable properties of the carbon electrode are as follows: the porosity expressed by (pore volume of the carbon electrode) / (volume of the carbon electrode) × 100 (%) is 20 to 50%. It is preferable that the porosity of the central portion that is not positively polarized at 80% is 25 to 95%, and the ratio of the porosity of both ends that are positively polarized and the porosity of the central portion that is not positively polarized is 0.2 to 0.85. When the porosity of both ends is 20 to 80%, if it is less than 20%, smooth flow of the water to be treated is hindered, and if it exceeds 80%, microorganisms that pass through the electrode without contacting the carbon electrode surface are generated Because. The reason why the opening ratio at the center is 25 to 95% is that if the opening ratio is less than 25%, there is no point in changing the opening ratio, and if it exceeds 95%, the mechanical strength is reduced.
[0013]
In a more desirable form, the carbon electrode composed of the carbon electrodes at both ends that are positively polarized and the carbon electrode at the central part that is not positively polarized has an average pore diameter of 25 to 125 μm as a whole and a porosity of 20 to 80%. It is desirable to set as follows.
Such carbon electrodes having different opening diameters or opening ratios include, for example, a single thin-walled carbon electrode plate having a large opening diameter or opening ratio and two thin circular plates having a small opening diameter or opening ratio. The carbon electrode plate can be used as it is, and the former carbon electrode plate can be used as it is by sandwiching it between the latter two carbon electrode plates. Or by heat treatment at a temperature of 1000 to 3000 ° C. after bonding. The opening diameter or opening ratio of each carbon electrode plate used at this time is determined in consideration of the number of breeding microorganisms that can be expected in advance. Also, the carbon electrode is a paper made of organic fibers such as cellulose-based paper having a predetermined opening diameter or opening ratio distribution, that is, by appropriately adjusting the opening diameter or opening ratio of individual paper or the like as a whole, for example, By obtaining a laminate using a thermosetting resin such that the opening diameter or opening ratio of the upper and lower surfaces is small and the opening diameter or opening ratio of the central portion is large, and then heat-treated at 1000 to 3000 ° C, A carbon electrode having desired performance can be obtained.
[0015]
ThisElectrolysis according to the present invention described aboveTankA fixed-bed type three-dimensional electrode electrolytic cell, that is, a fixed-bed type monopolar electrolytic cell and a fixed-bed type bipolar electrolytic cell. In these electrolytic cells, the three-dimensional electrode of the electrolytic cell has an enormous surface area. This is advantageous in that the contact area between the surface and the water to be treated can be increased, whereby the size of the apparatus can be reduced and the efficiency of the electrolytic treatment can be increased.
[0016]
The electrode in the fixed-bed type three-dimensional electrode electrolytic cell of the present invention generally includes a carbonaceous electrode which causes a polarization phenomenon and a power supply electrode terminal, and the carbonaceous electrode has a shape corresponding to the electrolytic cell used as described above and is porous. As described above, it is formed of a carbonaceous material such as activated carbon, graphite, carbon fiber or the like, which is configured as a porous block or sponge and through which the water to be treated can pass. A pair of a power supply anode terminal and a power supply cathode terminal formed of a perforated plate such as a flat plate, an expanded mesh, or a perforated plate disposed at both ends of one or more carbon electrodes having such a configuration. A direct current voltage is applied to polarize the carbon electrode to form a positively polarized portion and a negatively polarized portion at one end and the other end, respectively. If necessary, the polarity of the power supply anode terminal and the power supply cathode terminal is periodically converted or an AC voltage of 10 Hz or less is applied so that the positively polarized portion and the negatively polarized portion are generated at regular intervals. May be.
[0017]
Since the electrode is made of carbon, the electrode may be oxidized by oxygen gas, which is an electrolytic reaction product, and collapse as carbon dioxide gas. In order to prevent this, a material such as titanium or the like is coated with a platinum group metal oxide such as iridium oxide or ruthenium oxide on the positively polarized side of the electrode to form a porous material or titanium which is usually used as an insoluble metal electrode. An electrode material in which a platinum group metal is coated by plating or the like on a substrate such as the above may be placed in contact with each other so that oxygen generation mainly occurs on the porous material.
When the water to be treated is supplied to the electrolytic cell provided with the carbon electrode according to the present invention, the microorganisms in the water to be treated come into contact with the electrodes polarized by the liquid flow, receive high-potential energy supply on their surfaces, and receive strong power. It is considered that an oxidative reaction occurs in the microbial cells, and its activity is weakened or the microorganism itself is killed and sterilization is performed.
Such electrolytic treatment almost completely sterilizes microorganisms in the water to be treated. However, the water to be treated after the electrolytic treatment is not necessarily provided immediately for drinking or other uses. Are often used for various purposes after a relatively long time has passed.
[0018]
In the electrolytic treatment using the electrolytic bath for electrolytic treatment of the water to be treated according to the present invention, the carbon electrode is appropriately polarized and the supplied water to be treated is surely applied to the positively polarized portion of the carbon electrode. The microorganisms are sterilized as long as they come in contact with each other, and if any of these conditions are missing, the efficiency of disinfecting the microorganisms in the water to be taken out of the electrolytic cell will not increase.
The data that can be measured during electrolysis include the temperature, liquid volume and electrical conductivity of the water to be treated, and the voltage and current of the electrolytic cell. Even if these data are used alone or in combination, the operation can be performed normally. It cannot be determined whether it is abnormal or abnormal. If the concentration of microorganisms in the treated water is higher than the allowable limit, the cause of the abnormal operation can be clarified only by comparing with the fluctuation of the concentration of microorganisms, or the operation of the electrolytic cell is normal. And the conclusion that increased microbial concentrations in the treated water should be attributed to other causes.
[0019]
For this purpose, it is desirable that data over the entire time during the operation of the electrolytic cell is recorded, and the operating state of the electrolytic cell can be grasped by comparing the data with data on the concentration of microorganisms obtained later.
Therefore, in the electrolytic treatment of the water to be treated using the electrolytic cell of the present invention, at the same time as the electrolytic treatment, the temperature, liquid volume and electric conductivity of the treated water, and at least data selected from the voltage and current of the electrolytic cell. One type, preferably all of these data, can be continuously recorded with the operation of the electrolytic cell and stored, for example, in a computer. Generally, the range of the above conditions suitable for the electrolytic treatment is as follows: the temperature of the water to be treated is 5 to 45 ° C., the linear velocity passing through the electrolytic bath is 5 to 30 mm / sec, the electric conductivity of the water to be treated is 0 to 5000 μs / cm, The voltage is 2.0 to 8.0 V / electrolyzer, and the current density is 0 to 5.0 A / dm.²And the relationship between the height of the carbon electrode accommodated in the electrolytic cell and the linear velocity satisfies [electrolytic cell height (mm)] / [linear velocity value (mm / sec)] ≧ 1.0 (second) Then, the water to be treated can be efficiently treated. Since these values may fluctuate in relation to each other, any value within this range does not necessarily mean that the concentration of microorganisms is at a sufficiently low level, and conversely, any value outside this range. Even in such cases, the concentration of microorganisms may be at a sufficiently low level, and it is not possible to confirm whether the operation is performed normally simply by measuring these values.
[0020]
With the recording of this data, the treated water to be treated is sampled, and the concentration of microorganisms in the sample is measured in parallel. Two to three days after data on the concentration of microorganisms is obtained, abnormalities in the concentration of microorganisms are detected. In such a case, it is possible to identify which item of the electrolysis condition is associated with abnormal microorganism concentration by comparing the change with time of each data. When the microorganism concentration is maintained at a sufficiently low level, it can be understood that normal operation is performed according to the corresponding temporal change of each data. Further, if there is no abnormality in each data even though the microorganism concentration is abnormal, it is presumed that an abnormality in the microorganism concentration has occurred due to factors other than the operating conditions of the electrolytic cell. Other factors can be considered.
[0021]
In particular, after the enforcement of the PL Act, it is expected that pursuing and clarifying the causes of product defects will affect the survival of the company. Especially when the electrolytic treatment by the electrolytic cell of the present invention is applied to drinking water which is directly linked to human health, the effect is particularly large. In some cases, it cannot be determined whether the defect is caused by a method defect or other factors.
However, as described above, by recording various data relating to electrolysis conditions and leaving them at a later date, it is possible to reliably identify the cause of a product defect by combining it with data relating to the concentration of microorganisms obtained later.
Even when there is no abnormality in the microorganism concentration, it can be used as auxiliary data indicating that the electrolytic treatment was performed normally.
[0022]
Next, preferred examples of the electrolytic cell for electrolytic treatment of the water to be treated according to the present invention will be described with reference to the accompanying drawings, but the electrolytic cell is not limited thereto.
FIG. 2 is a schematic vertical sectional view showing an example of a bipolar fixed-bed type electrolytic cell which is the electrolytic cell of the present invention.
A mesh-type power supply anode terminal 13 and a power supply cathode terminal 14 are provided near an upper end and a lower end of a cylindrical electrolytic cell main body 12 having a flange 11 at upper and lower sides, respectively. In the illustrated example, three spongy fixed-bed carbon electrodes 15 are stacked between the two electrode terminals 13 and 14, and between the carbon electrodes 15 and between the carbon electrode 15 and the two electrode terminals 13. Four mesh-shaped diaphragms or spacers 16 are sandwiched between 14. Each of the carbon electrodes 15 has a pair of small opening diameter (ratio) electrode plates 15a and 15b at both lower and upper ends, and a large opening diameter (ratio) disposed between the small opening diameter (ratio) electrode plates 15a and 15b. ) The electrode plate 15c is integrated by bonding or sintering, and the carbon electrode 15 is in close contact with the inner wall of the electrolytic cell main body 12, does not pass through the inside of the carbon electrode 15, and The arrangement is such that the leakage flow of the water to be treated flowing between the side wall of the main body 12 and the side wall is as small as possible.
[0023]
The electrolytic cell main body 12 is preferably formed of an electric insulating material that can withstand long-term use or re-use. Particularly, synthetic resins such as polyepichlorohydrin, polyvinyl methacrylate, polyethylene, polypropylene, polyvinyl chloride, and polyvinyl chloride Ethylene, phenol-formaldehyde resin, polyacrylonitrile resin and the like can be preferably used.
When electricity is supplied to the electrolytic cell having such a configuration while supplying water to be treated from below as indicated by an arrow, the small aperture (ratio) electrode plate 15a below each of the carbon electrodes 15 is positively polarized. In addition, the small aperture (rate) electrode plate 15b above each carbon electrode 15 is negatively polarized, and the large aperture diameter (rate) electrode plate 15c at the center of each carbon electrode 15 is not polarized. The supplied water to be treated is sterilized by sequentially contacting a total of three positively polarized lower small-diameter (rate) electrode plates 15a, and then sterilized. Thereafter, the water is taken out above the electrolytic cell and guided to a faucet or the like. I will The polarity of the above-mentioned two electrode terminals 13 and 14 may be periodically inverted. In this case, the small aperture (rate) electrode plate 15b indicated by reference numeral 15b in FIG. Sterilize microorganisms in treated water.
[0024]
In this way, at the time of energization, one of the two small opening diameter (rate) electrode plates 15a and 15b is positively polarized, and the microorganisms in the water to be treated are sterilized. In the case of the polarity shown in FIG. 2, only the lower small aperture (rate) electrode plate 15a can be effectively sterilized, and the large aperture (rate) electrode plate 15c and the upper small aperture (rate) are effective. Microbes are hardly sterilized in the electrode plate 15b. Therefore, if microorganisms are adsorbed on these parts, they may propagate and increase their number.
However, as described above, when the polarity is reversed, the microorganisms are sterilized also in the upper small opening diameter (rate) electrode plate 15b, and by periodically performing the polarity inversion, the upper and lower small opening diameter (rate) electrode plates 15a, 15b. In this case, sterilization is performed, and sterilization of microorganisms is not effectively performed only at the central large opening diameter (rate) electrode plate 15c. Even if the number of microorganisms increases due to the propagation of microorganisms on the electrode plate 15c, the diameter of the opening of the carbon electrode is increased, so that the opening does not become clogged, and the water to be treated flows smoothly, Water electrolysis can be continued.
[0025]
FIG. 3 shows another example of a bipolar fixed-bed type electrolytic cell which is the electrolytic cell of the present invention. The electrolytic cell is an improvement of the electrolytic cell of FIG. 2, and the same members are denoted by the same reference numerals. The description is omitted.
The opening diameter (rate) of the carbon electrode 15 ′ is adjusted so as to be smaller as the opening diameter (ratio) of the lower side, that is, the positively polarized side, and larger as the opening diameter (ratio) of the upper side, that is, the side that is negatively polarized. A mesh-shaped insoluble metal electrode 17 is provided in a close contact state on the side of the carbon electrode 15 ′ toward the power supply cathode terminal 14, that is, on the side that is positively polarized, and the other members are the same as those in FIG. 2.
When electricity is supplied to the electrolytic cell 12a in the same manner as in the electrolytic cell of FIG. 2, the lower part of each carbon electrode 15 ', that is, the small opening diameter (rate) part is positively polarized, and the upper part, that is, the large opening diameter (rate) part is negatively polarized. Then, the microorganism is sterilized in the small opening diameter (rate) portion that is positively polarized, and no clogging occurs because the microorganism does not propagate in this portion. On the other hand, sterilization is not performed more effectively in the large opening diameter (ratio) portion where the polarization is negative than in the small opening diameter (ratio) portion, and microorganisms may propagate. However, because of the large pore diameter (rate), the propagated microorganisms do not completely block the pores, and the microorganisms in the water to be treated can be smoothly sterilized.
The electrolytic cell shown in FIG. 3 is different from the electrolytic cell shown in FIG. 2 on the assumption that the polarity is not reversed. When the electrolytic cell is used for the purpose of reversing the polarity, the opening diameter (ratio) of the central portion where no polarization occurs. May be adjusted to be larger than the opening diameter (rate) of the polarized portions on both sides.
[0026]
FIG. 4 is a longitudinal sectional view showing still another example of a bipolar fixed-bed type electrolytic cell which is the electrolytic cell of the present invention. The electrolytic cell relates to an improvement of the electrolytic cell of FIG. 2, and the same members as those of the electrolytic cell shown in FIG.
In the present electrolytic cell 12b, instead of the spacer 16 of FIG. 2, a porous electric insulating material 18 is placed in close contact with each carbon electrode 15 ″ having a uniform opening diameter (ratio), and the porous electric insulating material 18 On the upper flange 11, a lid 22 having an upwardly directed cylindrical body 21 formed in the center is placed, and between the flange at the upper end of the cylindrical body 21 and the flange at the lower end of the treated water discharge pipe 23. Has a filter 24 interposed therebetween.
Reference numeral 25 denotes a bottom plate in which a water supply pipe 26 is formed downward on the lower surface of the center.
[0027]
When current is supplied to the electrolytic cell having such a configuration while supplying water to be treated as indicated by an arrow from below, the carbon electrodes 15 "are polarized such that the lower surface is positive and the upper surface is negative as shown in FIG. A potential is generated in the electrode 15 "and between the carbon electrode 15", and the water to be treated flowing through the electrolytic bath contacts the carbon electrode 15 "having this potential to improve the sterilization of microorganisms contained therein. Quality treatment is carried out and taken out from the treated water discharge pipe 23 of the electrolytic cell main body 12b. Although the upper edge of each carbon electrode 15 ″ may be damaged or powdered due to strong flow of the water to be treated, in the present electrolytic cell, each porous electric insulating material 18 adheres to the upper surface of each carbon electrode 15 ″. Therefore, the above-mentioned damage and powdering are unlikely to occur and even if they occur, they remain on the surface of the carbon electrode 15 "and hardly suspend in the water to be treated, so that the mechanical strength of the carbon electrode 15" is maintained and Water contamination is prevented, and clogging of the carbon electrode located downstream is also prevented.
[0028]
FIG. 5 is a longitudinal sectional view showing still another example of a bipolar fixed-bed type electrolytic cell which is the electrolytic cell of the present invention. The electrolytic cell relates to an improvement of the electrolytic cell shown in FIG. 4, and the same members as those of the electrolytic cell shown in FIG.
In the electrolytic cell 12c of FIG. 5, the distance (x) from the uppermost carbon electrode 15 ″ to the power supply anode terminal 13 is longer than the width (y) of the uppermost carbon electrode 15 ″, and And a wide space 19 between the power supply anode terminal 13 and the power supply anode terminal 13.
When current is supplied to the electrolytic cell 12c having such a configuration while supplying water to be treated as indicated by an arrow from below, the water to be treated must permeate through a total of three carbon electrodes 15 ″. The water to be treated is supplied at a high water pressure into the electrolytic cell 12c, in which case if the water pressure is too high, the lowest and middle carbon electrodes 15 "will stop at that position due to the weight of the upper carbon electrode 15". Since the uppermost carbon electrode 15 ″ is not pressed from above, it may be pushed upward by the water pressure.
At this time, if a wide space 19 is formed between the uppermost carbon electrode 15 "and the power supply anode terminal 13 as in the electrolytic cell 12c, the pushed carbon electrode 15" comes into contact with the power supply anode terminal 13. I can't. Therefore, the uppermost carbon electrode 15 ″ does not contact the hard and sharp power supply anode terminal 13, and there is no contact between the power supply anode terminal 13 and the carbon electrode 15 and no damage to the carbon electrode 15; The electrolytic treatment of the water to be treated can be continued for a long time without replacement.
[0029]
【Example】
Hereinafter, examples of the electrolytic treatment of the water to be treated using the electrolytic cell according to the present invention will be described, but the examples do not limit the method of the present invention.
Embodiment 1
The electrolytic cell of this example was configured as follows.
First, a 39.5 mm diameter carbon fiber is placed between two small-diameter 39.5 mm diameter, 3 mm thick electrode plates (porous graphite, manufactured by Tokai Carbon Co., Ltd., approximately 45 μm in diameter). One electrode plate (porous graphite, manufactured by Tokai Carbon Co., Ltd., having a hole diameter of about 100 μm) having a thickness of 3 mm was inserted to form an electrode precursor having a three-layer structure. Then, the precursor was press-bonded to produce a carbon electrode having a small opening diameter at the top and bottom and a large opening diameter at the center (opening ratio at the center was 85%).
The five carbon electrodes (three in FIG. 2) produced as described above were placed in the electrolytic cell shown in FIG. 2 which is a transparent rigid polyvinyl chloride resin having a height of 75 mm and an inner diameter of 40 mm and having a flange and a cylindrical shape. A 38 mm diameter, 1 mm thick anode terminal for power supply made of titanium sandwiched between six polyethylene resin spacers having an aperture ratio of 80% and having a diameter of 40 mm and a thickness of 1 mm and made of titanium plated on the upper and lower diaphragms. And the power supply cathode terminal were placed in contact with each other to form an electrolytic cell of this example.
[0030]
Also, 795 microorganisms / milliliter were added to tap water to prepare treated water for testing.
The test water to be treated was supplied from the lower part of the electrolytic cell at a rate of 1.5 liter / minute (the supply pressure of the water to be treated at the start of energization was 2.03 kg / cm at the inlet pressure of the electrolytic cell).²) Apparent current density 0.2 A / dm by DC power supply²The electrolytic treatment of the water to be treated was performed by adjusting the electrolytic voltage to 4.3 to 8.8 V (average electrolytic voltage: 5.8 V). The number of microorganisms in the obtained treated water to be treated was 0 to 5 / ml.
The supply pressure of the water to be treated required to supply the water to be treated at a rate of 1.5 liter / min after the power was supplied for 7 days was 2.16 kg / cm.²And rose only slightly.
In addition, a large number of scratches were formed on the upper surface of the uppermost carbon electrode after the power supply was stopped, and slight cracks were also observed.
[0031]
[Comparative Example 1]
An electrode plate made of carbon fiber having a diameter of 39.5 mm and a thickness of 9 mm and having a substantially uniform pore size distribution (porous graphite, manufactured by Tokai Carbon Co., Ltd .; The treatment of the water to be treated was carried out under the same conditions, except that.
The supply pressure of the water to be treated at the start of energization required to supply the test water to be treated at a rate of 1.5 L / min is 2.35 kg / cm.²The supply pressure is 2.91 kg / cm after 7 days.²It was estimated that the carbon electrode was clogged.
[0032]
Embodiment 2
The spacer was replaced with a disc-shaped porous electric insulating material (woven cloth made of polypropylene) having a diameter of 39.5 mm and a thickness of 0.1 mm manufactured by NBC Industries Co., Ltd. having an opening diameter of about 60 μm, and replacing this with the carbon electrode. The treatment of the water to be treated was carried out under the same conditions as in Example 1 except that it was brought into close contact with the upper surface.
After supplying electricity for 7 days, the supply pressure of the water to be treated required to supply the water to be treated at a rate of 1.5 L / min was 2.09 kg / cm.²And increased only slightly.
[0033]
Embodiment 3
The electrolytic treatment of the water to be treated was carried out under the same conditions as in Example 1 except that an electrolytic cell having a height higher than that in Example 1 was used, and the distance between the uppermost carbon electrode and the power supply anode terminal was set to 15 mm. Was.
After energization for 35 days, each carbon electrode was taken out of the electrolytic cell, washed and dried. After observing the upper surface of the uppermost carbon electrode, only slight scratches were formed and no cracks were observed.
[0034]
【The invention's effect】
According to the present inventionRudenDissolving tank, one or two or more porous block-shaped or sponge-shaped three-dimensional fixed bed type carbon electrode, placed between the power supply anode terminal and the power supply cathode terminal, the treated water containing microorganisms, An electrolytic cell for electrolytic treatment of water to be treated, wherein the diameter of the pores or the rate of opening in the flow direction of the water to be treated of the carbon electrode is varied in an electrolytic cell supplied to the carbon electrode for electrolytic treatment. Item 1).
Specifically, the pore diameter or porosity at both ends in the vicinity of both terminals of the carbon electrode, which is positively polarized and causes microbial sterilization, is determined by the central part of the carbon electrode where almost no polarization occurs and therefore microbial sterilization hardly occurs. (Claim 2). This embodiment is particularly advantageous when treating the water to be treated while reversing the polarity of the power supply electrode terminal. It is desirable that the opening diameter is 20 to 500 μm, and the opening diameter at the center is 50 to 5000 μm.
[0035]
In this electrolytic cell, the pore diameter of the positively polarized portion where the microorganisms are sterilized and the microorganisms do not grow is reduced, so that the water to be treated sufficiently contacts the wall surfaces of the pores of the carbon electrode in the positively polarized portion. Microorganisms are sterilized by electrolytic treatment, whereas microorganisms that have not been polarized and do not need to be in contact with the walls of the pores of the carbon electrode do not need to contact the water to be treated. Even if the pores of the carbon electrode tend to be closed due to, the pores of the carbon electrode are closed to the extent that the flow of the water to be treated is hindered because the pore diameter (ratio) is large from the beginning. Nothing. Therefore, when the treatment of the water to be treated is performed using the electrolytic cell having such a configuration, the flow of the water to be treated is substantially equal to that at the start of the operation by preventing the carbon electrode from being clogged without lowering the treatment efficiency. It is possible to maintain the treatment of the water to be treated without replacing the members for a long period of time while maintaining.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing an example of a conventional electrolytic bath for treating water to be treated.
FIG. 2 is a schematic longitudinal sectional view showing an example of a bipolar fixed-bed type electrolytic cell which is the electrolytic cell of the present invention.
FIG. 3 is a schematic longitudinal sectional view showing another example.
FIG. 4 is a schematic longitudinal sectional view showing still another example.
FIG. 5 is a schematic longitudinal sectional view showing still another example.
[Explanation of symbols]
11 ... Flange 12, 12a, 12b, 12c ... Electrolyzer main body 13 ... Power supply anode terminal 14 ... Power supply cathode terminal 15, 15 ', 15 "... Carbon electrode 15a, 15b ..Small hole diameter electrode plate 15c ... large hole diameter electrode plate 16 ... spacer 17 ... insoluble metal electrode 18 ... porous electrical insulating material 19 ... space

Claims (3)

One or two or more porous block-shaped or sponge-shaped three-dimensional fixed-bed carbon electrodes are installed between a power supply anode terminal and a power supply cathode terminal, and water to be treated containing microorganisms is supplied to the carbon electrode. An electrolyzer for electrolyzing water to be treated, wherein an opening diameter or an opening ratio of the carbon electrode in the flow direction of the to-be-treated water is changed in the electrolyzer to be subjected to electrolytic treatment. 2. The electrolytic cell for electrolytic treatment of water to be treated according to claim 1, wherein the opening diameter or the opening ratio at both ends on both terminal sides of the carbon electrode is smaller than the opening diameter or the opening ratio at the central portion. The electrolytic cell for electrolytic treatment of water to be treated according to claim 2, wherein the opening diameter at both ends of the carbon electrode is 20 to 500 µm, and the opening diameter at the center is 50 to 5000 µm .

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