JP2000140849A - Electrochemical water treating device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove a hardness component in electrochemical treatment of water. SOLUTION: This device is formed by laminating plural metallic electrode units 1, each having spherical protrusions 1a on the surface, through electrical insulating spacers 2. The obtained device is dipped in the water to be treated contg. a hardness component with the units 1 directed vertically to treat the water. A current, when applied, concentrates on the spherical protrusions, the hardness component such as calcium ion in the water deposits on the negatively polarized face of the units 1 with the protrusions 1a as a center, and the deposited metal is released from the units 1 when a sort of power is exerted by the inversion of polarities, etc., dropped by gravity, accumulated in a deposit collecting member 9 and removed outside the system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for electrochemically treating water to be treated, and more particularly to sterilization and water quality of the water to be treated containing a relatively large amount of hardness components such as calcium, magnesium and silicon. The present invention relates to an electrochemical water treatment apparatus and method for smoothly and easily holding and the like.

[0002]

2. Description of the Related Art In recent years, with the increase of buildings such as condominiums and other multi-dwelling houses or buildings formed by gathering a large number of companies, the number of various types of cooling and heating equipment installed in the buildings and the like has increased dramatically. Has increased. In condominiums and buildings where many such cooling and heating facilities are installed,
Usually, equipment for heat exchangers for cooling water of the cooling and heating equipment, for example, a cooling tower is installed on the roof. If the cooling water of this heat exchanger equipment is also used for a long period of time, microorganisms such as molds and bacteria will propagate and precipitate on the heat exchange surface of the heat exchanger to deteriorate the heat exchange performance, or the microorganisms will be generated in a lump. In some cases, piping and the like may be blocked. In addition, serious waste such as corrosion may be caused on piping and equipment due to a large amount of waste of microorganisms. For example, in the case of the cooling water, the total number of microorganisms is 10
^{If it is 5} pieces / ml or more, putrefaction odor becomes severe, heat exchange efficiency of the heat exchanger is deteriorated, and troubles such as pipe clogging may occur. Furthermore, sterilization can be performed using a drug, but if the same drug is used continuously, a resistant bacterium that cannot be sterilized with the drug is generated, and a troublesome problem that it is necessary to change to a more powerful drug is known. I have. Also, it is hard to say that a drug that kills microorganisms is harmless to humans, and it is necessary to control the type and strict concentration of the drug under legal regulations. Moment is growing rapidly.

[0003] In addition to such cooling water, microorganisms inhabit in various types of water to be treated such as pond water, water in a reservoir, water in a fish farm, or pool water, and inhabit a large amount according to the environment. The water to be treated is contaminated. As a water treatment method for overcoming such disadvantages of the prior art, a bipolar fixed-bed type water treatment electrolytic cell that sterilizes microorganisms by contacting water to be treated with a polarized fixed-bed electrode has been disclosed ( For example, Japanese Unexamined Patent Publication
306242, JP-A-3-224684, JP-A-4-1
8980, JP-A-4-108592, JP-A-4-11
4785, JP-A-4-114787). However, since the bipolar fixed-bed type water treatment electrolytic cell uses a porous electrode as a fixed bed, it is difficult to treat water to be treated containing solid or organic substances and ionic occlusive substances. The pressure loss due to water flow is large, a large capacity water pump is required, and the energy cost is high. Further, even when the content of the occluding substance in the water to be treated is small, there is a problem that the sterilization performance is reduced during long-term use. Further, a carbon electrode is used as the porous electrode, and the carbon electrode has a drawback that it is easily worn out. When used for a long time, the electrode is gradually worn out, the distance between the electrodes is increased, and the voltage is increased. Will eventually have to be replaced. This electrode replacement generally requires disassembly of the entire electrolytic cell, which is a very complicated operation and significantly reduces workability.

[0004]

SUMMARY OF THE INVENTION The present applicant has solved the above-mentioned drawbacks of the prior art, and in particular, does not cause clogging of the electrodes even when using water to be treated containing an occlusive substance, so that the electrode can be removed from the electrolytic cell. Proposed an electrochemical treatment apparatus for water to be treated that does not require piping or energy for the introduction and discharge of the water to be treated and does not require an installation space for an electrolytic cell (Japanese Patent Application No. 9-2993).
No. 59, Japanese Patent Application No. 10-178131). The above-mentioned various to-be-treated water contains a relatively large amount of hardness components such as calcium and magnesium, and particularly, the to-be-treated water such as a boiler water, a cooling tower water and a scrubber water tank contains a large amount of hardness components. Calcium and magnesium are dissolved in the water to be treated as respective ions, but when electrochemically treated, they are deposited on the cathode surface as metal compounds.

[0005] When the metal compound is precipitated, there are disadvantages such as a decrease in the amount of electricity and a short circuit between the electrodes. Particularly, the boiler water or the like often flows in the piping, which causes a problem that the deposited metal compound adheres to the inner wall surface of the piping and blocks the piping. Therefore, conventionally, the above-mentioned drawbacks have been solved by reversing the direction of the direct current and anodic oxidizing the metal compound on the surface of the cathode to elute as metal ions again into the electrolyte. However, it is essentially desirable to remove the hardness component from the water to be treated. Conventionally, the hardness component has been removed from the water to be treated using an ion exchange resin. However, the ion exchange capacity of the ion exchange resin decreases with the lapse of time of use, so it is necessary to periodically exchange or regenerate the resin. become.

In the treatment of water to be treated using the porous electrode described above, calcium ions and magnesium ions in the water to be treated precipitate on the surface of the negatively polarized electrode. The surface of a porous electrode, specifically a carbonaceous electrode, has a very complicated microstructure, and it is difficult to mechanically peel off the metal compound once deposited. The metal calcium compound and the metal magnesium compound precipitated by inverting are oxidized and redissolved in the water to be treated as calcium ions and the like. Therefore, hardness components such as calcium ions in the water to be treated are not removed, and it is substantially impossible to remove the hardness components from the water to be treated by a simple electrochemical operation. Various kinds of water to be treated such as cooling water for heat exchangers containing hardness components are electrochemically treated using metal electrodes,
Techniques for depositing and removing the hardness component on the metal electrode are known. However, in this technique, a hard metal component is deposited almost uniformly on the entire surface of the metal electrode using a flat metal electrode, and firmly adheres to the electrode surface. Therefore, it becomes difficult to separate the precipitated components from the electrode surface. For example, in the case of the above-described polarity reversal, the separation takes too much time and is practically difficult to perform. In practice, the operation is stopped to spray high-pressure water or It is removed by mechanical peeling. This operation is quite complicated, and although it is relatively easy to electrochemically deposit the hardness component on the electrode surface, the subsequent operation is troublesome and cannot be said to be an excellent water treatment method. The present invention has been made in view of the above-mentioned drawbacks of the prior art, and in the case of electrochemical treatment of water to be treated containing a hardness component such as calcium and magnesium using a metal electrode, the hardness component is relatively easily operated. It is an object of the present invention to provide an apparatus and a method capable of relatively easily removing a hardness component that can be removed, particularly, a hardness component deposited on an electrode surface.

[0007]

Means for Solving the Problems The constitution of the present invention for solving the above-mentioned problems is that a plurality of metal electrode units having a surface treated with a catalyst and having irregularities on the surface are laminated via an electrically insulating spacer, and the hardness of the unit is increased. An electrochemical treatment apparatus for the water to be treated, characterized in that the apparatus is immersed in the water to be treated containing components and is supplied with a direct current to perform an electrochemical treatment of the water to be treated. The above-mentioned electrochemical treatment may be performed by installing a sediment collection member all around one end of the unit. In addition, the method of the present invention provides an electrochemical water treatment apparatus in which a plurality of metal electrode units having a surface treated with a catalyst and having irregularities on the surface are stacked via an electrically insulating spacer, wherein each of the metal electrode units is oriented vertically. Immerse in the water to be treated containing the hardness component and apply a direct current so as to perform an electrochemical treatment of the water to be treated, deposit the hardness component as a metal compound on the cathode side surface, and the deposited hardness. An electrochemical treatment method for water to be treated, characterized in that components are released from the cathode surface.

Hereinafter, the present invention will be described in detail. In the electrochemical water treatment apparatus according to the present invention, the metal electrode main body configured by stacking a plurality of metal electrode units having irregularities on the surface via a spacer, the metal electrode units preferably face in a vertical direction. By immersing in the water to be treated as described above and applying a current, it is possible to perform the modification of the water to be treated, that is, sterilization of microorganisms, removal of hardness components, decomposition and removal of COD, BOD and pesticides, decolorization of the water to be treated, and the like. Although possible, the present invention mainly focuses on the removal of the hardness component.

On the surface of the negative electrode of each metal electrode unit of the metal electrode body immersed in the water to be treated, a metal calcium compound or a metal magnesium compound (and a trace amount of metal silicon) which is a reduction product of calcium ions or magnesium ions is provided. Compound etc.) precipitate. As described above, it has been almost impossible to separate the deposited metal from the electrode surface by a method other than the mechanical method with the metal electrode and the like in the prior art, but in the present invention, a metal electrode unit having unevenness on the surface is used as the electrode unit. are doing. Therefore, the distance between the adjacent metal electrode units changes, the gap between the convex portions becomes shorter, and the concave portions become longer. In other words, current easily flows into the convex portions of the metal electrode unit, and current concentrates on the convex portions. The hardness component tends to precipitate. At this time, if the area of each projection is made sufficiently small, the precipitated hard component does not form a lump but has a light weight, so that it can be separated from the surface by a relatively weak force, for example, convection of the water to be treated. Further, if each metal electrode unit is oriented vertically, in other words, if the surface on which the metal is deposited is kept vertical, the deposited metal compound is receiving downward gravity due to its own weight, so that the metal is deposited. When a relatively weak force is applied to a metal compound lump or the like, the metal compound separates from the electrode surface and falls directly downward to separate from the electrode surface. At this time, since the precipitated metal compound is in a powder form,
It is easy to handle and can be easily taken out of the system.

When the deposited metal compound does not peel off from the electrode surface only by the force of the convection described above, the peeling may be performed by reversing the direction of conduction, that is, by reversing the polarity of the electrode. The metal compound deposited on the surface of the cathode is anodized to metal ions by polarity reversal, and a portion close to the electrode is eluted to become powdery metal and fall away from the electrode.
Thereby, the hardness component can be removed from the water to be treated by applying the polarity reversal as a part of the electrochemical operation without applying a mechanical force. Also in this case, since the amount of the precipitation hardness component adhering to each convex portion is small, the reverse energization time may be short. The metal electrode unit used for removing the hardness component in the present invention is desirably a flat electrode, but the flat electrode has a smooth surface and is easy to adhere to a precipitated metal calcium compound or the like. However, since the surface area is small and there are no pores, it is inferior to porous electrodes in terms of liquid leakage and contact efficiency, and the electrode surface is temporarily and partially covered by precipitation of hardness components, effective for sterilization of microorganisms etc. The number of electrode surfaces that can be used is reduced. Therefore, even if this flat electrode is used alone, microbial sterilization and removal of hardness components in the water to be treated can be achieved, but the microbial sterilization efficiency is much lower than that of the porous electrode. It is desirable to use the porous electrode having excellent efficiency in combination.
When both electrodes are used together, the removal of the hardness component by the flat electrode
The microbes can be effectively sterilized by the porous electrode, and both the sterilization process and the hardness component removal process, which tend to be biased to one side alone, can be efficiently performed.

[0011] The metal electrode unit comprises a catalyst, a catalyst, a titanium, tantalum, nickel, niobium, etc.
For example, it is desirable to improve electrode performance by coating platinum, iridium, ruthenium, palladium, osmium, rhodium or their oxides alone or in a mixture. The concavo-convex pattern can be arbitrarily formed in a lattice shape or a large number of circular protrusions can be formed. Its size and width are as small as possible, preferably 0.01 to 10 mm, more preferably 0.1 to 1 mm
It is desirable to promote the release of the precipitation hardness component.
The unevenness may be formed by molding the entire electrode or by initially manufacturing a flat plate-like electrode and mechanically forming the unevenness on this electrode.

The porous electrode has an aperture ratio defined as a percentage of a value obtained by dividing the total surface area of each opening by the total electrode area obtained by adding the total surface area of the electrode and the total surface area of the openings. Preferably it is 80%. If the opening ratio is less than 10%, the pressure loss is large and clogging is likely to occur. If the opening ratio is more than 80%, the electrode strength is hindered and deformation or damage may occur. This is because the contact of the treated water may be insufficient, and it is desirable to set an appropriate opening ratio in consideration of both clogging and contact efficiency. In the present invention, a plurality of metal electrode units are stacked via spacers, and each metal electrode unit and each spacer are fastened with bolts and nuts which are electrically insulating fastening materials passing therethrough, or each metal electrode unit and each spacer are fastened. The outer circumference of the electrode unit is fixed with an electrically insulating material, and the metal electrode units are connected to each other to form a metal electrode body. By changing the number of metal electrode units, the thickness of this metal electrode body, consisting of multiple metal electrode units and spacers, can be increased or decreased relatively freely, depending on the amount of water to be treated and the conditions of the installation space. Can be done. The increase or decrease can be easily performed by using an electrically insulating fastening material that is optimally using bolts and nuts. In addition to changing the thickness of the metal electrode body by changing the number of metal electrode units, it may be desirable to change the thickness of the metal electrode unit itself or the thickness of the spacer. The purpose can be easily achieved by attaching and detaching.

The spacer used is for securing electrical insulation between adjacent metal electrode units and for securing a space for depositing the deposited metal compound. If the electrical insulation and the space are ensured, the shape of the spacer is limited. However, in order to improve the contact efficiency between the water to be treated and the metal electrode unit, the area should be as small as possible, for example, in a frame shape,
Further, it is preferable that the metal has a downward U-shape in order to make the deposited metal fall smoothly. The thickness of the spacer is desirably about 1 to 10 mm. When the thickness is less than 1 mm, a short circuit may occur between adjacent electrodes due to the above-described precipitation hardness component. This is because a necessary current does not easily flow. In the case of a porous electrode, the spacer also serves to reinforce the strength of the porous electrode. The spacer has a function of electrically insulating adjacent metal electrode units to secure a space for the deposited metal, and to improve the escape of oxygen gas and hydrogen gas generated by electrolysis. The gas generated on the surface of the metal electrode unit inhibits the water to be treated from contacting the surface of the metal electrode unit, and lowers the efficiency of energizing each metal electrode unit. However, due to the presence of the spacer, the generated gas easily moves from the space between the adjacent metal electrode units to the periphery of the metal electrode body, thereby increasing the processing efficiency. Note that the present invention is not limited to a process involving gas generation.

Further, the generated gas causes convection in the water to be treated, and the convection causes the entire water to be treated to come into contact with the surface of the metal electrode unit evenly, and the above-mentioned precipitation hardness component is peeled off as powder. Will be possible. Therefore, even when treating a large amount of water to be treated, the water to be treated can be treated without installing a separate stirring device. The metal electrode body is basically immersed in the water to be treated as it is, and the electric power is supplied to the electrode body to perform the treatment of the water to be treated on the surface of the electrode body, that is, mainly to remove the hardness component. It is desirable that the electrode body be energized with a DC voltage of 42 V or less for safety reasons. If the current density is adjusted to about 0.1 to 1.0 A / dm ² , optimum processing efficiency can be obtained. This is 0.1 A /
If it is less than dm ² , sufficient sterilization may not be performed, and 1.
If it exceeds 0 A / dm ² , the electrode life may be shortened. If the voltage value or the current density value of this value cannot be obtained, the metal electrode unit may be divided into a plurality.

The energization may be performed while maintaining the polarity. However, it is desirable to reverse the polarity as described above to promote the separation of the precipitation hardness component. Depending on the conditions, even if only the convection of the water to be treated is performed without the polarity reversal, the precipitation hardness component is separated from the electrode surface in a powdery form. Perform inversion.
In general, in the electrochemical treatment of the water to be treated, the polarity is reversed every 5 to 50 hours.However, in the present invention, the interval of the polarity reversal is made shorter than before so that the precipitation hardness component does not adhere firmly to the electrode surface. In order to achieve this, it is desirable to invert at intervals of 2 to 30 minutes . The polarity reversal causes the negatively polarized side of one metal electrode unit to become positively polarized, and the precipitation hardness component that grows and forms a block if not reversed can be removed from the electrode surface as a powder by the polarity reversal. .

The removed precipitation hardness component may be collected by filtering the water to be treated. Preferably, a precipitation collecting member is attached to the entire lower peripheral edge of the metal electrode body to be trapped therein. Collecting eliminates the need for labor such as filtration. The sediment collection member may be made of a non-porous resin material or a durable net. In the latter case, the diameter of the deposited metal compound is at least as large as 0.1 to 1.0 mm. Should be collected. When the water to be treated flows through a flow path having partitions and the like on both sides, the electrodes are arranged as weirs for blocking the water to be treated in the flow path, and the water to be treated makes sufficient contact with the inside of the electrode. Efficiently permeate or overflow over the weir.

Since the metal electrode body is used in water, a power supply is actually required to supply power to the electrode body. The power supply is a member for supplying electricity to the metal electrode unit from outside of the water to be treated. The material of the power supply is not particularly limited as long as the metal has sufficient conductivity and resistance to the water to be treated. From the viewpoint of resistance, it is preferable to use titanium, tantalum, nickel, niobium and the like, and particularly to use titanium. Normal electric welding or the like is used to connect the power supply and the metal electrode unit. The metal electrode body is not merely immersed in water, for example, a pump may be installed in water and the water to be treated may be sprayed on the electrode by the pump to improve the treatment efficiency. The electrode does not need to be entirely immersed in water. For example, the electrode may be located at a falling part of the water to be treated that flows down like a waterfall, and this embodiment is also included in the present invention.

Further, the metal electrode body may be immersed in the water to be treated while being suspended from the wall of the container containing the water to be treated using a hook or the like. The container is a general term for various vessels in which water to be treated is stored, such as a bathtub, a water storage tank, a boiler water, a cooling tower water, and a scrubber water tank. Also, when treating a large amount of water such as pond water, reservoir water, fish farm water or pool water, the metal electrode body is immersed in the water to be treated in a floating member floating on the water to be treated such as a raft. The water to be treated can be treated by mounting as described above. In this case, it is necessary to mount a power supply such as a storage battery. However, if a solar cell is used as the power supply, a large amount of the water to be treated can be treated semipermanently without artificially adding energy.

The mechanism for killing microorganisms according to the present invention can be presumed to be as follows. First, microorganisms strike the anode surface and die. Secondly, trace amounts of chlorine contained in the water to be treated are oxidized on the electrode surface to generate hypochlorous acid, and active oxygen is generated by water electrolysis. Microorganisms in the water to be treated are sterilized by these hypochlorous acid and active oxygen, and trace impurities are decomposed. In the electrochemical treatment according to the present invention, unlike the electrolytic cell which is a conventional water treatment apparatus, the electrode is immersed in the water to be treated, so that there is no need to prepare and install the electrolytic cell itself, No piping or energy is required for the introduction and discharge of water into and out of the electrolytic cell.Also, if overflow is enabled, resistance will be reduced and electrode blockage will be prevented. Therefore, replacement and cleaning of the electrodes are almost unnecessary. When it is necessary to wash the electrode, put the contaminated electrode in a liquid other than the water to be treated, and reverse the polarity to dissolve the precipitate and wash it. You can go out and spray clean water to wash.

The apparatus of the present invention withstands long-term operation and requires almost no cleaning. However, when cleaning is performed, hydrogen peroxide, ozone water, hypochlorous acid, acidic water having a pH of 3 or less, and alkaline water having a pH of 9 or more are used. Either one may be flowed alone or alternately. The use of the method or the device according to the invention makes it possible, in addition to the removal of hardness components, to achieve the disinfection of microorganisms in the water to be treated and other improvements in water quality. The microorganisms include bacteria (bacteria), molds, yeasts, deformed fungi, single-cell algae, protozoa, viruses, and the like, and the improvement of water quality includes decomposition of impurities such as ammonia.

The water to be treated according to the present invention is boiler water, cooling tower water, scrubber water, elevated water tank water,
Water containing a large amount of hardness components such as water for thermal or nuclear power plants is particularly desirable, and in addition to this, it can be widely used in daily life and in many fields of industrial activities. There are freshwater and seawater inside, artificially created aqueous solution, dilution water, etc.More specific examples are industrial water, tap water, purified water, well water, rainwater, recovered water, humidified water, drainage, gutter water, Water storage, seawater (control of microorganisms and sterilization of shells, algae, aquatic organisms, etc.), pond water, pool water, bath water, gas absorption tower water, cooling water, hot water, hydroponic water, fountains,
Photographic developer, water for fish culture (appreciation fish, cultured fish), water for ornamental animals and cultured birds, water emulsion, papermaking water, hot spring water, dye ink dilution water, water-soluble paint dilution water, water-soluble cosmetics dilution water, denture storage system Bacteria water, contact lens storage bacteria water,
Toothbrush storage bacteriostatic water, aqueous solutions containing various chemical substances, and the like. Further, it is necessary or desirable to reduce or eliminate the number of microorganisms in water. Food water, pharmaceutical water, magnetic recording hard disk cleaning water, semiconductor cleaning water, automatic sales This includes machine water. Furthermore, it can be used for pretreatment of water for sterilization of quays, pipes and various intakes.

Next, an embodiment of an electrochemical water treatment apparatus and a water treatment method using the apparatus according to the present invention will be described with reference to the accompanying drawings. 1 to 3 show an example of the electrochemical water treatment apparatus of the present invention, FIG. 1 is a front view thereof, FIG. 2 is a sectional view taken along line AA of FIG. 1, and FIG. It is a line sectional view. Reference numeral 1 denotes a metal electrode unit in which a mixture of, for example, platinum and iridium is carried on the surface of a rectangular titanium flat plate, and a large number of circular projections 1a are formed on the surface to give an uneven pattern. Is a plural number, 4 in the illustrated example.
The metal electrode body 3 is formed by vertically stacking three spacers 2 having a downward open U-shape between the peripheral portions of the adjacent metal electrode units 1 and having a lower opening. At each of the four corners of each of the metal electrode units 1 and the spacers 2, through-holes having an insulating material layer 4 coated on the inner edge side are drilled, and the holes are insulated from the metal electrode units 1 by washers 5 from above. Bolt 6 that penetrated,
A bolt end protruding from the lowermost metal electrode unit 1 is fastened by a nut 8 insulated by a washer 7, and the metal electrode units 1 and the spacer 2 are interconnected. On the side where the spacer 2 opens, that is, on the lower periphery in FIG. 1, a sediment collection member 9 is fitted so as to cover the opening of the spacer.

A conductive wire 10 connected to a positive power supply (not shown) is provided between the metal electrode unit 1 at one end of the metal electrode body 3 and one of the four washers 5, and a metal electrode unit at the other end. A conducting wire 11 connected to a negative power supply (not shown) is connected between one of the one and four washers 7 so as to be energized. When electricity is supplied between the metal electrode units 1 at one end and the other end, two metal electrode units 1 in the middle
Is charged positively on one side of the electrode unit and negatively on the other side by the voltage applied between the two metal electrode units 1. In the vicinity of the negatively charged surface, calcium ions and magnesium ions of the water to be treated are reduced and are precipitated on the surface as a metal calcium compound or a metal magnesium compound. At this time, since the distance between the poles is shortened by the circular protrusion 1a, the current concentrates on the portion of the circular protrusion, and the hardness component is deposited on this portion. Since each circular projection has a very small area, the precipitation hardness component does not clump and easily separates from the electrode surface due to the convection of the water to be treated and the polarity reversal. This hardness component 12 falls downward in FIGS. 1 and 3 by its own weight and accumulates in the sediment collection member 9. By taking out the precipitation collecting member 9, the powdery precipitation hardness component can be taken out of the system.

[0024]

EXAMPLES Next, examples relating to the treatment of water to be treated using the electrochemical water treatment apparatus according to the present invention will be described, but the examples do not limit the present invention.

[0025]

[Example 1] Tap water was placed in a tank having an internal volume of 1 m ³ and left open for about one week until no hypochlorite ion was detected. Water containing high-concentration microorganisms and calcium chloride were added thereto, and total bacteria were added. Test water having a number of 1.25 × 10 ⁵ cells / ml and a calcium ion concentration of 130 mg / ml was used. The surface is coated with platinum and iridium, and a cylindrical projection with a diameter of about 2 mm and a height of about 1 mm
A resin washer with a thickness of 2.0 mm is sandwiched between three flat plate electrodes made of titanium having a thickness of 1 mm, a length of 100 mm, and a width of 100 mm, and resin bolts are inserted into through holes formed at four corners of the plate electrode. The metal electrode unit was inserted, and the other end was fastened with a resin nut. A polyethylene net having an opening width of 0.3 mm was attached to the lower peripheral edge of the metal electrode unit as a precipitate collecting member to form a metal electrode body. This metal electrode body was immersed in the test water (900 liters) so that the sediment collecting member was positioned below, and subjected to an electric current treatment at DC 0.6 A. After 48 hours, the total number of bacteria in the test water was measured. Is 570
And the calcium ion concentration was reduced to 68 mg / liter, and white precipitates were observed inside the precipitate collecting member and on the surface of the metal electrode unit.

[0026]

Embodiment 2 After processing under the same conditions as in Embodiment 1,
When the polarity of the electrode was reversed every 2 hours and energized for 24 hours, no white precipitate was observed on the surface of the metal electrode unit,
All were collected inside the precipitate collecting member.

[0027]

[Example 3] A titanium lath (expanded mesh having a thickness of 1 mm and a diameter of 65 mm, titanium porous plate having a hole diameter of 2.0 mm and a hole diameter of 3.0 mm) having a thickness of 2 mm and having a thickness of 2 mm was coated on the surface with platinum and iridium oxide. A resin bolt was inserted into through holes formed in three places around the titanium lath with a resin washer interposed therebetween, and the other end was fastened with a resin nut to obtain a metal electrode unit. The porous metal electrode body and the metal electrode body used in Example 1 were immersed in test water having a total bacterial count of 1.87 × 10 ⁵ cells / ml and a calcium ion concentration of 150 mg / ml. DC 0.3 A is applied to the main body, and DC 0.6 A is applied to the plate electrode of the first embodiment.
A was energized. After energization for 48 hours, the total number of bacteria fell below the lower detection limit, and the calcium ion concentration decreased to 34 mg / liter.

[0028]

The electrochemical water treatment apparatus and method according to the present invention are characterized in that a plurality of metal electrode units having a surface treated with a catalyst and having irregularities on the surface are laminated via an electrically insulating spacer to reduce the hardness component. And an electrochemical treatment apparatus for treating the water to be treated, wherein the apparatus is immersed in the water to be treated and to which a direct current is applied to perform the electrochemical treatment of the water to be treated. An electrochemical water treatment apparatus in which a plurality of treated metal electrode units having irregularities on the surface are laminated via an electrically insulating spacer, the treated water containing a hardness component such that each of the metal electrode units is oriented vertically. Immersed in a direct current and subjected to electrochemical treatment of the water to be treated, to precipitate the hardness component on the cathode side surface as a metal, and to drop the deposited hardness component from the cathode surface by its own weight. An electrochemical processing method of the water to be treated (claim 4), wherein the door.

As described above, the present invention has as its main object the removal of hardness components in the water to be treated. Hardness components such as calcium ions and magnesium ions are reduced on the surface of the cathode or the negatively polarized electrode and are precipitated as corresponding metal compounds. In conventional electrochemical water treatment, since a flat surface electrode is used, the precipitation hardness component adheres firmly to the electrode surface as a relatively large mass, and thus the precipitation hardness component is separated from the electrode surface. Therefore, smooth treatment of the water to be treated could not be performed. On the other hand, in the present invention, the surface of each metal electrode unit constituting the electrochemical water treatment apparatus is provided with irregularities. Therefore, the current is concentrated on the convex portion, and the hardness component is preferentially deposited on the convex portion. When the area of each convex portion is reduced, the precipitation hardness component does not become a lump but can be removed from the electrode surface in a powdery or the like and easily removed from the system by a relatively weak force.

The relatively weak force may naturally occur due to the convection of the water to be treated, but it is generally desirable to apply a force from the outside, and this force may be applied mechanically.
It is preferable to reverse the polarity of the electrode to the polarity at the time of energization in the treatment of the water to be treated (claim 5), whereby a small amount of the precipitation hardness component adhering to the electrode surface on the electrode surface is anodized. Then, most of the remaining precipitated hardness components are peeled off from the electrode surface and fall down by their own weight to be removed. In this case, if the metal electrode unit is disposed in the vertical direction (claim 2), the precipitation hardness component separated from the electrode is promoted to fall downward due to its own weight. If a sediment collecting member is installed on the entire lower periphery of the plurality of metal electrode units (claim 3), the above-mentioned naturally falling precipitation hardness component accumulates in the sediment collecting member and is subjected to processing. The precipitated hardness component can be collected without performing operations such as filtration of water.

The metal electrode unit for removing a hardness component according to the present invention uses a plate-shaped electrode unit in order to make it easy to deposit a deposited metal, and the plate-shaped electrode unit has a smaller surface area than the porous electrode unit and has a higher precipitation hardness. The surface area is further reduced by coating the components. Therefore, when only the plate-shaped electrode unit is used, the efficiency of microbial sterilization and the like is reduced. In order to prevent this, the metal electrode body composed of a plate-shaped electrode unit and the metal electrode body composed of a porous electrode unit may be immersed in the same water to be treated to perform water treatment (claim 6). Sterilization and removal of hardness components can be achieved at once.

[Brief description of the drawings]

FIG. 1 is a front view showing an example of an electrochemical water treatment apparatus of the present invention.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a sectional view taken along line BB of FIG. 1;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Metal electrode unit 1a ... Circular projection 2.
..Spacer 3 ... Metal electrode body 4 ... Insulating material layer 5 ... Washer 6 ... Bolt 7 ...
Washer 8: Nut 9: Precipitation collecting member
10, 11: Conductor wire 12: Precipitated metal compound

Claims (6)

[Claims] 1. A plurality of metal electrode units having a surface treated with a catalyst and having irregularities on the surface are laminated via an electrically insulating spacer, immersed in water to be treated containing a hardness component, and supplied with a DC current. An electrochemical treatment apparatus for the water to be treated, wherein the apparatus performs the electrochemical treatment of the water to be treated. 2. The electrochemical water treatment apparatus according to claim 1, wherein the metal electrode unit is arranged in a vertical direction. 3. A plurality of metal electrode units having a surface treated with a catalyst and having irregularities on the surface are laminated via an electrically insulating spacer, and a sediment collection member is provided around one end of the plurality of metal electrode units. Installed, immersed in the water to be treated containing the hardness component so that each of the metal electrode units is oriented vertically, and applying a direct current to perform the electrochemical treatment of the water to be treated, and the sediment collection member An electrochemical treatment apparatus for treating water to be treated, wherein a precipitation hardness component is collected. 4. An electrochemical water treatment apparatus in which a plurality of metal electrode units having a surface treated with a catalyst and having irregularities on the surface are stacked via an electrically insulating spacer, so that each of the metal electrode units is oriented vertically. Immersed in the water to be treated containing the hardness component and apply a direct current to perform electrochemical treatment of the water to be treated, depositing the hardness component as a metal compound on the cathode side surface, and the deposited hardness component Electrochemical treatment of water to be treated, characterized in that water is released from the surface of the cathode. 5. An electrochemical water treatment apparatus comprising a plurality of metal electrode units having a surface treated with a catalyst and having irregularities on a surface thereof laminated via an electrically insulating spacer, wherein each of the metal electrode units is oriented vertically. The hardness component is immersed in the water to be treated containing the hardness component and a direct current is applied while reversing the polarity, thereby performing the electrochemical treatment of the water to be treated, and releasing the hardness component precipitated by the polarity reversal from the cathode surface. A method for electrochemically treating water to be treated. 6. A metal electrode body for removing a hardness component, wherein a plurality of plate-like metal electrode units having a surface treated with a catalyst and having irregularities on the surface are laminated via an electrically insulating spacer, and a plurality of porous bodies surface-treated with a catalyst. The sterilizing metal electrode body in which the conductive metal electrode unit is laminated via an electrically insulating spacer is used to treat the treated water containing the hardness component such that at least the metal electrode unit of the hardness component removal metal electrode body is oriented vertically. A method for electrochemically treating the water to be treated, wherein the water is subjected to an electrochemical treatment by immersing the treated water and applying a direct current.