JP2000189975A - Method for removing film deposited on electrode and water purification device using the same method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent scales from being deposited on the surface of each of the electrodes in water purification device for purifying water by electrolyzing aluminum to form a metal hydrate and utilizing coagulation effect of the metal hydrate to form agglomerated flocs of suspended matter. SOLUTION: This device is provided with: at least a pair of electrodes consisting of an anode 31 made of aluminum and a cathode 30; a coagulation control means 54 for controlling current passage through the electrodes 31 and 30; a circulation means 18 for passing water through the space between the electrodes 31 and 30; a heating means 11; and a control means 51; wherein the circulation means 18 is intermittently operated at prescribed time intervals and the electrolysis of aluminum is performed while stopping the current passage through the electrode 31 and 30 when the circulation means 18 is operated, and also, at a prescribed point of time, citric acid is dissolved into water to wash off a deposited film (scale) formed and built up between the electrodes 31 and 30, at a prescribed citric acid concentration, for a prescribed time and at a prescribed temperature. Thus, the deposition of the film (scale) on the electrode is prevented between the electrodes 31 and 30 and the effective utilization rate of aluminum can be enhanced, good purification performance can be obtained and further the electrode service life can be remarkably prolonged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for removing a film such as a scale component formed on an electrode surface when performing electrolysis using an electrode having an aluminum anode, and a method for removing metal water by electrolysis using the aluminum anode as an electrode. The present invention relates to a water purification device that generates a sump, forms flocculated flocs of suspended substances by the flocculating action of this metal hydrate, and removes and purifies suspended substances contained in water to be purified such as bathing water. .

[0002]

2. Description of the Related Art As a conventional water purifying apparatus, there is a water purifying apparatus in which microorganisms are propagated on a microorganism carrier, and organic substances are decomposed and purified by the enzymatic activity of the microorganisms (see, for example, Japanese Patent Application Laid-Open No. Hei 5 (1994)).
-293485).

[0003] However, the microbial water purification apparatus has the following problems. (1) The purification speed is slow because the purification is performed by the enzyme activity of the microorganism. For this reason, once the bath water becomes polluted by bathing, it takes three hours or more to purify the bath water. Therefore, if the bather takes a bath continuously (for example, every 30 minutes), the bather must bathe in the polluted bath water, and there is a psychological resistance.

(2) Sterilization in the filtration tank destroys microorganisms contributing to purification, so that purification ability cannot be obtained. Therefore, it is impossible to sterilize the inside of the filtration tank, which serves as a hotbed for pathogenic bacteria and the like. Therefore, there is a possibility of contamination of bath water bacteria such as Legionella spp.

(3) When a bath agent is used, since microorganisms are killed, the bath agent cannot be used.

As a solution to these problems, as shown in FIGS. 6 and 7, a metal hydrate is formed by electrolysis, and the diameter of the suspended substance is increased by the coagulation action of the metal hydrate. A water purification apparatus for filtering water has been proposed (for example, JP-A-8-132051).

In FIG. 1, 1 is a bathtub, 2 is a circulation pump,
3 is a flocculation means, 4 is a filtration tank provided downstream of the flocculation means, and 5 is a circulation path. Here, the aggregating means 3 is, as shown in FIG. 8, an anode 6 made of, for example, aluminum and a cathode 7 made of stainless steel (here, it also serves as a casing).
It is composed of

In the above configuration, when electricity is supplied to the anode 6 and the cathode 7, aluminum ions are eluted from the anode 6 by electrolysis. This aluminum ion reacts with hydroxide ion OH- of water to form aluminum hydroxide Al (OH) 3.
Is formed. Here, suspended substances such as sebum / stain and bacteria are negatively charged because they have a carboxyl group in the side chain. On the other hand, since aluminum hydroxide has a positive charge, aluminum hydroxide serves as a binding medium, and a fine suspended substance is adsorbed by the crosslinking action to increase the diameter, so-called aggregated flocs are generated. As a result, the flocculated floc is effectively filtered in the filtration tank 4 provided downstream, and purification can be performed in a short time. In addition, since no microorganisms are used, the inside of the filtration tank 4 serving as a hotbed of bacteria can be sterilized by, for example, high-temperature sterilization, and a bathing agent can be used.

[0009]

As described above, the coagulation filtration method has a feature that cannot be obtained by the microbial method. However, metal ions (aluminum ions) are eluted by electrolysis to form a metal hydrate ( In the process of producing (aluminum hydroxide), it has been found that aluminum hydroxide gradually remains on the surface of the anode and deposits between the anode and the cathode, thereby reducing the effective utilization rate of aluminum contributing to aggregation.

In other words, theoretically, aluminum ions Al 3+ having a high ionization tendency are dissolved in accordance with the amount of electricity supplied based on Faraday's law, and react with hydroxide ions to form aluminum hydroxide, which contributes to aggregation. Although it should be, scale components such as Ca, Mg, and Si contained in the bath water and aluminum hydroxide are combined and remain on the anode surface and the cathode surface, and the amount of aluminum that should contribute to agglomeration is reduced. I understand.

As a result, an excessive amount of aluminum is required, and the size of the anode is increased. In addition, since sufficient aluminum hydroxide is not generated, the cross-linking action due to aggregation gradually decreases as the scale component adheres, and the purification ability decreases. In addition, there has been a problem that the deposit between the anode and the cathode is filled with deposits due to long-term use, the electrical resistance between the electrodes increases, and a predetermined electrolytic current cannot be secured.

[0012]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides at least one pair of electrodes composed of an anode and a cathode composed of aluminum, and electrode control means for controlling energization of the electrodes. Circulating means for flowing water between the electrodes, heating means for water flowing through the electrodes, and control means for controlling the electrode control means, the circulating means and the heating means, and energizing the electrodes During the electrolysis operation, the water supply means is intermittently operated at a predetermined cycle, and at the time of the operation of the circulating means, electrolysis is performed while stopping power supply to the electrodes, and citric acid is dissolved in water at a predetermined time. Then, the film formed between the electrodes at a predetermined concentration, time and temperature is washed.

That is, the present inventors have conducted various studies in order to reduce deposits on the surface of the aluminum anode, and as a result,
As an effective method, the water to be purified is not circulated during the electrolytic coagulation operation, and the electrolysis is carried out in a stagnated state (hereinafter referred to as stagnant electrolysis), whereby the adhesion of the scale component mainly composed of aluminum hydroxide on the anode surface is prevented. It has been found that it can be reduced. As a mechanism of this, the residence electrolysis causes hydroxide ions OH- to be consumed on the anode surface to become oxygen gas and chlorine gas, so that aluminum hydroxide Al (OH)
This is because the reaction to No. 3 does not proceed and the precipitation of aluminum hydroxide on the anode surface is prevented. On the other hand, when electrolysis is carried out in a conventional water-flowing state, hydroxide ions OH- are similarly consumed on the anode surface. It is thought that aluminum is generated on the anode surface and reacts with scale components contained in water to deposit scale.

On the other hand, when electrolysis is carried out in a stagnant state, chlorine gas is produced by reacting with oxygen gas and chlorine ions in water as an anodic reaction, and hydrogen gas is produced as a cathodic reaction. It is thought that these gases float as bubbles and contribute to the separation of scale components on the electrode surface.
It is accumulated and accumulated upward. In particular, hydrogen gas is an explosive gas, and chlorine gas is a corrosive gas. In addition, when gas is generated, the electrical equivalent resistance between the electrodes gradually increases, and when constant current control is performed, the voltage increases, and a power supply with a high voltage capacity is required.

That is, in order to solve these problems while preventing the scale on the anode surface, it is desirable to perform intermittent electrolysis and water supply at a predetermined cycle. Also, when water is passed,
In other words, in the state where the circulating means is operating, by stopping the current supply to the electrodes, the aluminum hydroxide accumulated on the electrode surface by the retained electrolysis can be washed with running water,
It is possible to more effectively reduce the deposition of a film such as aluminum hydroxide.

Furthermore, by performing chemical cleaning with citric acid periodically in addition to the above-described electrolytic control, the electrode film can be more effectively removed. In other words, the hydrogen ion concentration (hereinafter referred to as pH) of the water to be purified becomes strongly acidic due to citric acid, and the scale component, aluminum hydroxide, and other films adhered to the electrode surface are decomposed by chemical reaction and ionized, and washed and removed. .

As a result, the effective utilization of aluminum is improved, so that the volume or weight of the anode can be reduced, and the coagulation efficiency is improved, so that good purification performance can be obtained. Further, since the electric resistance between the electrodes does not change, the life of the electrodes can be greatly extended, and stable purification performance can be maintained for a long period of time.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for removing an electrode film according to claim 1 of the present invention comprises the steps of: at least one pair of electrodes comprising a cathode and an anode made of aluminum; Control means, circulating means for passing water between the electrodes, heating means for water flowing through the electrodes, control means for controlling the electrode control means, the circulating means and the heating means, the electrode During the electrolysis operation by energizing the circulating device, the circulating means is intermittently operated at a predetermined cycle, and at the time of operating the circulating device, the electrolysis is performed while the energization to the electrodes is stopped. This is to wash the film formed between the electrodes at a predetermined concentration, time and temperature by dissolving the acid.

During the electrolysis operation by energizing the electrodes, the control means operates to intermittently drive the circulating means at a predetermined cycle, and the energization to the electrodes is stopped in conjunction with the operation of the circulating means. Therefore, only the retained electrolysis and the passage of water are performed alternately. As a result, the accumulation of metal hydrate on the anode surface is prevented by the retained electrolysis, and the film of aluminum metal hydrate, scale, etc. is easily peeled off from the electrode surface by passing water without applying electricity, The citric acid is dissolved in water at a predetermined time and washed at a predetermined concentration, time and temperature, so that the film formed between the electrodes and gradually deposited is exposed to a strongly acidic atmosphere to be ionized and removed more effectively. it can.

As a result, aluminum can be effectively used, and the volume or weight of the aluminum anode can be reduced. In addition, since the electrical resistance between the electrodes does not change, the life of the electrodes can be greatly extended.

In the method for removing an electrode film according to a second aspect of the present invention, the concentration of citric acid is adjusted so that the pH of water during washing with citric acid is in the range of 1 to 3.5.

The aluminum hydroxide Al (OH) 3 adhering to the electrode surface is ionized (Al3 +) due to consumption of OH ions in the pH range of 1 to 3.5, and becomes soluble. Therefore, by mixing citric acid so that the pH is in the range of 1 to 3.5 with respect to the amount of water, the electrode surface film can be effectively removed.

According to a third aspect of the present invention, there is provided a method for removing an electrode coating, wherein 0.01 to 1% by weight of a corrosion inhibitor is mixed with citric acid.

By mixing an appropriate amount of the corrosion inhibitor, it is possible to prevent corrosion and dissolution of the components of the circulation path that comes into contact with citric acid during cleaning due to strong acid. The concentration and type of the corrosion inhibitor vary depending on the material of the constituent members, but the effect of preventing corrosion can be obtained by mixing 0.01 to 1% by weight.

A water purification apparatus according to a fourth aspect of the present invention has a means for circulating the water to be purified and an electrode provided in the circulation path and comprising an aluminum anode and a cathode. An aggregating means for generating a metal hydrate by electrolysis and electrically aggregating a suspended substance contained in the water to be purified, and an aggregating floc provided downstream of the aggregating means, wherein the agglomerated floc generated by the aggregating means are physically separated. Filtration means, and a heating means for heating the water to be purified, the intermittent operation of the circulating means at a predetermined cycle during the coagulation operation by energizing the electrodes, and the operation of the circulating means It has coagulation control means for performing electrolysis while stopping power supply to the electrodes, and dissolves citric acid in circulating water at a predetermined time to wash the coating formed between the electrodes at a predetermined concentration, time and temperature. Also It is.

In the aggregating operation by energizing the electrodes, the aggregating control means is operated, the circulating means is driven intermittently at a predetermined cycle, and when the circulating means is operated, the energizing of the electrodes is stopped. While performing electrolysis. That is, only the retained electrolysis and the passage of water are performed alternately. As a result, the adhesion of metal hydrate on the anode surface is prevented by the retained electrolysis, and the metal hydrate of the dissolved metal is easily peeled off from the electrode surface by passing water without applying electricity, so that a film is formed on the electrode surface. It is difficult to be generated, and a good cake layer (filtration membrane) is formed by being captured by the downstream filtration means, and the gas accumulated by the electrolysis is discharged through the circulation path. In addition, the citric acid is dissolved in the circulating water at a predetermined time to wash the film formed between the electrodes at a predetermined concentration, time, and temperature. The film is exposed and ionized, and the film can be removed more effectively.

As a result, a film (scale) on the anode surface is prevented, and the effective utilization rate of the electrolytic metal is improved, so that a good purification performance can be obtained and the anode can be miniaturized. Further, since the electric resistance between the anode and the cathode does not change, good purification performance can be maintained for a long period of time.

The water purification apparatus according to claim 5 of the present invention is provided with a citric acid supply means for mixing citric acid at a predetermined concentration in a circulation circuit of the purified water.

Then, at a predetermined time, the citric acid supply means automatically operates and the cleaning between the electrodes is performed at a predetermined concentration and temperature, so that a manual operation of the citric acid cleaning is unnecessary.

In the water purifying apparatus according to claim 6 of the present invention, the concentration of citric acid is adjusted so that the pH of water at the time of washing with citric acid is in the range of 1 to 3.5.

Then, aluminum hydroxide (Al (OH) 3) adhering to the electrode surface is ionized (Al3 +) due to consumption of OH ions in a pH range of 1 to 3.5, and a scale component contained in water such as Ca and Mg. Is also ionized and becomes soluble. Therefore, by mixing citric acid so that the pH is in the range of pH 1 to 3.5 with respect to the amount of water, the electrode surface film can be effectively removed, and good purification performance can be maintained for a long time.

The water purifying apparatus according to claim 7 of the present invention is obtained by mixing citric acid with 0.01 to 1% by weight of a corrosion inhibitor.

By mixing the corrosion inhibitor with the citric acid, it is possible to prevent the corrosion and dissolution of the components of the water purification device that come into contact with the citric acid during citric acid washing due to the strong acid, thereby improving the reliability of the equipment. .

The water purifying apparatus according to claim 8 of the present invention is provided with a counting means for measuring the number of times of coagulation operation, and performing citric acid washing when the signal of the counting means reaches a predetermined number. It is.

The amount of electrode film generated by energizing the aluminum electrode is proportional to the energizing time. When the electrolysis time per day is set to a predetermined time, the amount of electrode film generated is proportional to the number of times of aggregation by energizing the electrode. Therefore, by performing citric acid cleaning when the number of times of aggregation reaches a predetermined number, it is possible to effectively perform film cleaning without performing unnecessary cleaning work.

In the water purifying apparatus according to a ninth aspect of the present invention, the temperature of the water to be purified is controlled by controlling the heating means during the washing with citric acid.
The configuration is such that the process is performed in the range of 0 ° C. to 70 ° C.

The higher the solution temperature is, the higher the activity of the citric acid cleaning is, and the more effective the film removing effect is. However, when the temperature is too high, the members constituting the circulation path of the water purification device are thermally deteriorated, and the reliability of the device is reduced. Therefore, by performing the citric acid cleaning in the range of 40 to 70 ° C., it is possible to effectively remove the film of the aluminum electrode while preventing the deterioration of the components of the circulation path.

[0038] The water purifying apparatus according to claim 10 of the present invention comprises:
An electrode signal detecting means for detecting a voltage or a current between the electrodes is provided, and a notifying means for notifying a citric acid cleaning time according to a signal of the electrode signal detecting means is provided.

When a film is deposited on the electrodes, the electric resistance between the electrodes increases, and the voltage (constant current control) or current (constant voltage control) decreases. By providing the electrode signal detecting means, the state of film formation can be constantly monitored, and a notification is issued, so that the citric acid cleaning can be performed at a suitable time that does not affect the purification performance.

The water purifying apparatus according to claim 11 of the present invention comprises:
This is a configuration in which a rinsing operation is performed to cause citric acid remaining in the circulation circuit to flow out of the circulation circuit after the citric acid cleaning.

When the citric acid remains in the circulation path and is left for a long time, the components in the circulation path are oxidized and corroded. Therefore, by performing the rinsing operation after the citric acid cleaning, the remaining citric acid solution is discharged out of the circulation path, and the reliability of the device is improved. Also,
When the next purification, for example, bath water purification, is performed while citric acid remains in the circulation path, the organic carbon of citric acid is mixed into the bath water to increase the total organic carbon amount TOC, thereby increasing the nutrient source of the bacterial group. As a result, the growth may be accelerated and the purification performance may be reduced. By performing the rinsing, such a decrease in purification performance can be prevented.

[0042]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 shows a system configuration diagram of a hot water supply bath apparatus according to Embodiment 1 of the present invention. In FIG. 1, reference numeral 8 denotes a water purification device for purifying water in a bathtub 9 which is water to be purified, and reference numeral 10 denotes a hot water supply unit having a heating unit 11 for keeping the bathtub water warm and boiling.

The bathtub 9 has a bath adapter 1 having a discharge port 12 and a suction port 13 connected to the water purification device 8.
4 are provided.

The water purifier 8 is provided with a suction port 13 of the bathtub 9.
A circulation path 17 including a return pipe 15 communicating with the discharge port 12 and a going pipe 16 communicating with the discharge port 12, a circulation means 18 for circulating bath water, and a circulation path 17 provided with citric acid in the circulation water. Citric acid supply means 19 for supplying, and aggregating means 20 for aggregating and increasing the diameter of suspended substances contained in bath water
A filtration means 23 provided downstream of the filtration means 23, which is filled with a particulate filter medium 21 made of, for example, an inorganic material such as alumina through a filter bed 22, and filters the flocculated floc having a large diameter by the flocculating means 20. A three-way valve 24a provided upstream of the filter and communicating with the heating means 11 and a three-way valve 24b provided downstream of the filtration means 23, and the suspended substance deposited on the filtration means 23 is passed in the opposite direction to that during normal filtration. Back washing means 2 comprising a bypass passage 25 and a discharge passage 26 for washing by washing.
7. The drain 26 is provided with a trap 28 for catching the filter medium 21 flowing out of the filtration means 23 at the time of backwashing, and a two-way valve 29 provided downstream thereof. The backwash water is connected and discharged to the bathtub 9.

The aggregating means 20 has an aluminum anode 31 made of aluminum inside a housing 30 made of stainless steel and opposed to the housing 30, and the anode 31 and the cathode (here, the housing 30 is also used). A power supply 32 for applying a voltage therebetween, and a reverse means 33 capable of switching the polarity of current supplied to the cathode (casing) 30 and the anode 31 are provided.

Reference numeral 34 denotes a water level detecting means for detecting the water level in the bathtub 9, 35a and 35b are check valves, and 36 is a two-way valve.

The hot water supply means 10 includes a water circuit 37 and a gas circuit 3.
The water circuit 37 includes an incoming water temperature detecting means 39 for detecting an incoming water temperature, a flow rate detecting means 40, and a hot water supply heat exchanger 41.
a, a water quantity proportional valve 42, a flow rate control valve 43, and a tapping temperature detecting means 44 for detecting a hot water outlet temperature are sequentially provided, and the terminals thereof are a water terminal 45 such as a shower and a pouring valve 46;
The circulation path 17 of the water purification device 8 passes through the check valves 35a and 35b.
Is configured to be able to be poured into the bathtub 9. Reference numeral 47 denotes a bypass water passage that connects the inlet side water circuit and the water proportional valve 42.

The gas circuit 38 is provided with a main solenoid valve 48, a gas proportional valve 49, and a heating means 11 and a burner 50 for heating the hot water supply heat exchanger 41a. Here, the hot water supply heat exchanger 41a and the heat exchanger 41b of the heating means 11 for keeping the water in the bathtub warm and boiling are integrally formed, and a so-called one-can-two-channel heat exchanger is formed.

FIG. 2 is a configuration diagram of a main part of the water purification device. In the figure, reference numeral 51 denotes a control means, which is a circulation control means 5 for controlling the circulation means 18 based on a time chart described later.
, An aggregation control means 54 comprising an electrolysis control means 53 for controlling the aggregation means 20 via a power supply 32 and a reverse means 33, (electrode control means) three-way valves 24a, 24b
And a backwash control means 55 for controlling backflow washing of the filtration means 23 by controlling the backwashing.

Here, as shown in the operation time chart of FIG. 3, the coagulation operation time, that is, the coagulation control means 54 is operated by the circulation control means 52 to operate the cathode (casing) 30 and the anode 31.
In the state where power is supplied during the period, the first time limit means 56 for setting the time Ta for stopping the circulation means 18 and the second time means 5 for setting the time Tb for operating the circulation means 18
7 is provided, and the time during which the circulation means 18 is operating
In conjunction with Tb, the electrolysis control means 53 sets the cathode 30 and the anode 3
It operates so as to stop energizing 1. When the coagulation operation is completed, the reverse operation is performed by operating the reverse unit 33 for a predetermined time Tr by the electrolysis control unit 53 to reverse the polarities of the cathode 30 and the anode 31.

Next, the operation and operation of this embodiment having the above configuration will be described with reference to FIGS. 1, 2 and 3. FIG.

When the bath hot water switch (not shown) is turned on, the pouring valve 46 is opened, and water is introduced from the water circuit 36.
At the same time, the main solenoid valve 48 of the gas circuit 38 is opened and the burner 50 is ignited. The water passing through the water circuit 36 is heated by the hot water supply heat exchanger 41a, and based on detection signals from the incoming water temperature detecting means 39, the flow rate detecting means 40 and the outgoing water temperature detecting means 44, the water proportional valve 42, the flow rate regulating valve 43 and the gas Proportional valve 4
9 is controlled, and hot water of the set temperature is poured into the bathtub 9 via the return pipe 15 and / or the outgoing pipe 16. Bathtub 9
Is detected at predetermined time intervals by the water level detecting means 34. When the water level reaches the set water level, the pouring valve 46 is automatically closed, and the hot water supply means 10 is stopped. The water level and temperature of the bathtub water are appropriately detected within the bathing time zone, and the set water level and temperature are maintained. Also, when the water terminal 45 is opened, the hot water supply means 10 operates and the desired temperature is discharged.

Next, the operation and operation of the water purification device 8 will be described. After the filling, the power supply 32 of the coagulation means 20 operates during the time Ta set by the first time limit means 56 by the coagulation control means 54 as shown in the time chart of FIG. A voltage is applied in between. In this time zone, the circulating means 18 does not operate and the retained electrolysis is performed, so that aluminum ions Al3 + are eluted from the anode 31 made of aluminum. At this time, the hydroxide ions OH
-Is consumed to become oxygen gas and chlorine gas, so that the reaction to aluminum hydroxide Al (OH) 3 does not easily progress, and the deposition of aluminum hydroxide on the surface of the aluminum anode 31 is reduced. The eluted aluminum ions react with hydroxide ions OH- of water in the gap between the cathode 30 and the anode 31 to become aluminum hydroxide Al (OH) 3 colloid and float.

After elapse of the residence time Ta, the second time limiter 5
7, the circulation means 18 is operated for the time Tb, and in conjunction with this, the energization to the aggregation means 20 is stopped by the electrolysis control means 53. At this time, the aluminum hydroxide floating between the electrodes and adhering to the surface of the aluminum anode 31 is washed away by running water to reach the surface layer of the filter medium 21, and the remaining on the surface of the aluminum anode 31 decreases.

On the other hand, when electrolysis is carried out in a stagnant state, chlorine gas is produced by reacting with oxygen gas and chlorine ions in water as an anodic reaction, and hydrogen gas is produced as a cathodic reaction. These gases float as bubbles and the cathode 3
Although it is considered that this contributes to the separation of the scale components from the surface of the aluminum anode 31 and 0, it is accumulated and accumulated upward. In particular, hydrogen gas is an explosive gas, and chlorine gas is a corrosive gas. In addition, the electric equivalent resistance between the electrodes gradually increases due to the generation of gas, and the voltage value increases when constant current control is performed, so that the power supply 32 having a high voltage capacity is required.
That is, by intermittently performing the retained electrolysis and the flow of water at a predetermined cycle, it is possible to prevent these problems while preventing scale on the electrode surface.

Here, the suspended substances such as sebum, dirt and bacteria contained in the bath water are negatively charged because they have a carboxyl group in the side chain. On the other hand, since aluminum hydroxide has a positive charge, the aluminum hydroxide serves as a binding medium, and a fine suspended substance is adsorbed by the crosslinking action to increase the diameter thereof, so-called agglomerated flocs are generated. As a result, the filter medium 2
The coagulated floc is deposited on the surface layer of No. 1 to form a cake layer (coagulated film) having fine pores. By operating the circulating means 18, the bath water circulates along the path shown by the solid line arrow in FIG. Thus, effective water purification can be performed in a short time. According to the experiment, the water to be purified having a turbidity of 2 degrees was applied between the electrodes at 300 mA.
When the filtration was performed while applying a current, 0.5 ° or less was obtained after elapse of 20 minutes. In the same experiment, it takes 2 to 3 hours for the enzyme activity of the microorganism. In this embodiment, even if the user takes a continuous bath (for example, every 30 minutes), the user can bathe in clear bath water.

During this coagulation operation time, as shown in FIG. 3, the coagulation control means 54 operates to control the circulation means 18 and the coagulation means 20, and the above operation is repeated a predetermined number of times. Note that this operation is performed a suitable number of times (time) depending on the purification load.

Next, at the end of the coagulation operation, the reverse means 33 is operated by the electrolysis control means 53, and the polarity of the cathode 30 and the aluminum anode 31 is supplied with reverse polarity for a predetermined time Tr. By performing the polarity switching operation after the aggregation operation, the anode 31
The oxide film formed on the cathode is reduced by hydrogen and the cathode 3
By dissociating the positive ions of 0, the binding force of the aluminum hydrate Al (OH) n attached to the surface of the cathode 30 is weakened, the deposition of aluminum hydrate on the electrode surface is more effectively prevented, and the longer Life can be extended. The reverse operation may be performed at the beginning of the aggregation operation.

Next, the backwashing operation of the filtering means 23 will be described. At a predetermined time after the end of bathing until the coagulation operation in the next bathing time period, the backwash control means 55 operates to flow through the three-way valves 24a and 24b in the direction shown by the broken arrows in FIG. 1 or FIG. Control. Thereafter, the hot water supply means 10 is operated to open the injection valve 46, and high-temperature water (about 47 ° C., desirably 60 ° C. or more) reaches the bypass 25 through the return pipe 15 and the three-way valve 24 a. From the downstream, it flows in from the opposite direction to the normal filtration direction, and the suspended matter including the flocculated flocs deposited on the surface of the filter medium 21 is back-flow washed,
It passes through a trap 28 and a two-way valve 29 for catching the filter medium 23 flowing out of the filtering means 23 at the time of backwashing through the discharge path 26 and is discharged from the going pipe 16 into the bathtub 9. At this time, the bathtub water may be drained, or the backwash operation may be performed in a hot water state, and then drained. Suitable conditions for the backwashing time and the flow rate are set according to the amount of the suspended substance and the specifications of the filtration means 23.

As described above, by performing the backwashing of the filtration means 23 before the flocculation operation, the flocculated floc containing the trapped suspended substance is discarded to the outside and cleaned, and then a new flocculation operation is performed by performing the flocculation operation. As a result, the cake layer of the flocculated floc is formed and purification is performed, and stable purification performance can be obtained for a long time without increasing the pressure loss of the filtration means 23 by a predetermined value or more.

Further, aluminum hydroxide has viscosity due to its cross-linking action and has a property that it is difficult to dissociate from the surface of the filter medium 21 when performing backwashing, but the cross-linking action has a temperature characteristic. When washed with high-temperature water, the crosslinking effect is rapidly reduced. Since the hot water supply means 10 can arbitrarily obtain high-temperature water, backflow washing with high-temperature water weakens the bonding force of the flocculent floc to the filter medium 21, so that backflow washing can be suitably performed. Therefore, there is no increase in the pressure loss of the filtration means 23 even during long-term use. In addition, since the trap 28 is provided, the filter medium 21 flowing out of the filtering means 23 at the time of backwashing is captured, so that the two-way valve is prevented from being caught and the outflow to the bathtub 9 can be prevented.

Further, since the backwash water is discharged into the bathtub 9, a hot water supply bath apparatus with a purifying function is installed in a high-rise apartment house, such as a house without a backwash water outlet (not shown). Even in this case, it can be installed without the construction work of drainage.

Next, the citric acid cleaning operation will be described.
When the coagulation electrolysis operation is continued for a long time, an electrode film containing aluminum hydroxide as a main component is formed on the cathode 30 and the aluminum anode 31. By operating a switch (not shown) at a predetermined time, the control means 51 is automatically started, the citric acid supply means 19 is operated, and a predetermined concentration (pH 1 to 3.5) is obtained in the circulation path 17. The citric acid is thus mixed, and the heating means 11 of the hot water supply means 10 operates to raise the circulating water temperature to 40 to 70 ° C (preferably 70 ° C). Thereafter, the circulating means 18 is operated to circulate through the circulating path 17 through the bath 9 and contact the cathode 30 and the aluminum anode 31 in the filtering means 23 to mainly remove the aluminum hydroxide Al (OH) 3 adhering to the electrode surface. The electrode film as a component is ionized (Al3 +), and the scale components contained in water such as Ca and Mg are also ionized and dissolved. Therefore, the electrode surface film can be effectively removed, and good purification performance can be maintained for a long period of time.

FIG. 4 shows a case where the electrode is 300 m long by a constant current power supply.
FIG. 9 is a characteristic diagram showing a relationship between an elapsed equivalent number of years and an electrolysis voltage when A is energized and the electrolysis time is set to 90 minutes / day. The characteristic A in the figure is based on the conventional continuous flow electrolysis. Characteristic B is a case where intermittent residence electrolysis was performed, and C is a combination of intermittent residence electrolysis according to the present invention and citric acid washing. The cleaning conditions for citric acid in the characteristic C are as follows: citric acid concentration: 0.3 wt%
(PH 2.6), washing was performed at a temperature of 47 ° C. for 2 hours, and the washing was performed at a cycle corresponding to one year. 24 due to power capacity
Assuming that V is the life, the characteristic C using the citric acid cleaning together is
It can be seen that the life is about 20 times that of the conventional A.

In addition, 0.01 to 1% by weight of a corrosion inhibitor (inhibitor) is mixed with citric acid to prevent corrosion and dissolution of the components of the water purification device which comes into contact with citric acid during washing with citric acid due to strong acid. Can be prevented, and the reliability of the device is improved.

The citric acid washing is performed by citric acid supply means 1
Without providing 9, a predetermined amount may be put into the bathtub 9 by hand to carry out.

(Embodiment 2) FIG. 4 is a main part configuration diagram of a hot water supply bath apparatus having a purifying function in Embodiment 2 of the present invention.

Reference numeral 58 denotes a counting means for detecting the number of operations of the coagulation control means 54. When the number of times of coagulation, that is, the energizing time to the electrode reaches a predetermined time, the notifying means 59 notifies the counting means. To perform the citric acid cleaning operation in the same manner as in the first embodiment. Also 60
Is an electrode signal detecting means for detecting the voltage or current between the electrodes, and a film is formed between the cathode 30 and the anode 31;
When the voltage or the current reaches a value at which the citric acid cleaning is to be performed, the notifying unit 59 is notified, and the citric acid supplying unit 19 is operated to perform the citric acid cleaning operation as in the first embodiment. Further, reference numeral 61 denotes a rinsing cleaning control unit, which detects that the citric acid cleaning has been executed, operates the hot water supply unit 10 after the citric acid cleaning operation, and supplies fresh water to the circulation path including the filtration unit 23 to perform rinsing cleaning. Is performed.

The other parts are the same as those of the embodiment shown in FIGS. 1 and 2, and the same reference numerals are given and the detailed explanation is omitted.

Next, the operation of this embodiment will be described. For the purification, the cathode 30 and the anode 31 are energized for a predetermined time per day to perform the aggregation operation, but the aggregation operation is continued for a predetermined number of days (number of times) (for example, one year).
As a result, an electrode film is formed and the purification performance is reduced as described above, so that it is necessary to wash with citric acid. The counting means 58 detects the number of times of agglutination, and when the number of times required for washing reaches the predetermined number, displays it on the notifying means 59, and displays
By operating No. 9, the citric acid cleaning operation described in the first embodiment is executed, and the electrode film is removed. By performing citric acid washing when the number of times of agglomeration reaches a predetermined number, if aggregating operation is not performed such as a day when bathing is not performed, counting is not performed, so that unnecessary cleaning work is not performed, and the effect is eliminated. The coating can be washed effectively.

The electrode signal detecting means 60 detects a voltage or a current applied to the cathode 30 and the anode 31 to form an electrode film, and the electric resistance between the electrodes is set to a predetermined value (for example, voltage 2).
When the voltage exceeds 4 V), the display is displayed on the notification means 59 and the citric acid supply means 19 is operated to execute the citric acid cleaning operation described in the first embodiment, thereby removing the electrode film.

As a result, the state of electrode film formation can be constantly monitored, and a notification is given, so that the citric acid cleaning can be performed at a suitable time that does not affect the purification performance. When used in combination with the above-mentioned counting means 58, it is possible to cope with variations in the formation of electrode films due to differences in water quality such as electrical conductivity or hardness and pH, and bathing load, etc., and it is possible to maintain good purification performance for a long period of time.

Further, the rinsing washing control means 61 detects that the citric acid washing has been executed, and operates the hot water supply means 10 after the citric acid washing operation, thereby causing the circulation path 17 including the filtering means 23 to operate.
Is supplied with fresh water to perform rinsing, and the citric acid remaining in the circulation circuit is allowed to flow out of the circulation circuit. Therefore, the citric acid solution remaining in the circulation circuit is discharged out of the circulation path, and the reliability of the device is improved. Further, when the next purification, for example, bathtub water purification is performed in a state where the citric acid remains in the circulation path, the organic carbon of the citric acid is mixed in the bathtub water, the total organic carbon amount TOC increases, and the bacteria group is removed. There is a case where the growth becomes accelerated as a nutrient source and the purification performance is reduced. However, such a reduction in the purification performance can be prevented by performing the rinsing.

In the present embodiment, the signals from the counting means 58 and the electrode signal detecting means 60 are used to supply the citric acid supplying means 19.
Was automatically operated to perform citric acid cleaning. However, without providing the citric acid supply means 19, after being notified, a predetermined amount of citric acid was manually poured into the bathtub 9 for cleaning. Is also good.

[0076]

As described above, according to the method for removing an electrode film according to the first aspect of the present invention, only the retained electrolysis and the passage of water are alternately performed. As a result, the accumulation of metal hydrate on the anode surface is prevented by the retained electrolysis, and the film of aluminum metal hydrate, scale, etc. is easily peeled off from the electrode surface by passing water without applying electricity, Since citric acid is dissolved in water at a predetermined time and washed at a predetermined concentration, time and temperature, the film formed between the electrodes is exposed to a strongly acidic atmosphere to be ionized and effectively removed.
As a result, aluminum can be used effectively,
The volume or weight of the aluminum anode can be reduced.
In addition, since the electrical resistance between the electrodes does not change, the life of the electrodes can be greatly extended.

According to the method for removing an electrode film according to the second aspect of the present invention, the concentration of citric acid is adjusted so that the pH of water at the time of washing with citric acid is in the range of 1 to 3.5. A film such as aluminum hydroxide (Al (OH) 3) adhering to the surface can be effectively ionized to remove the electrode film.

According to the method for removing an electrode film according to the third aspect of the present invention, since 0.01 to 1% by weight of a corrosion inhibitor is mixed with citric acid, a circulation path for contacting citric acid at the time of washing is used. Corrosion and dissolution of the constituent members due to strong acid can be effectively prevented.

According to the water purifying apparatus of the fourth aspect of the present invention, the coagulation control means operates for the coagulation operation by energizing the electrodes, and the circulation means is intermittently driven at a predetermined cycle. During the operation of the circulating means, only the retained electrolysis and the water flow are alternately performed, and the retained electrolysis prevents the adhesion of the metal hydrate on the anode surface. Since the hydrate is easily peeled off from the electrode surface, it is difficult to form a film on the electrode surface, and a good cake layer (filtration membrane) is captured by downstream filtration means, and gas accumulated by electrolysis is removed. Released via the circuit. In addition, the citric acid is dissolved in the circulating water at a predetermined time to wash the film formed between the electrodes at a predetermined concentration, time, and temperature. The film is exposed and ionized, and the film can be removed more effectively. As a result, the electrode film (scale) is prevented, and the effective utilization rate of aluminum is improved, so that good purification performance is obtained and the size of the anode can be reduced. Further, since the electric resistance between the anode and the cathode does not change, good purification performance can be maintained for a long period of time.

According to the water purifying apparatus according to the fifth aspect of the present invention, since the citric acid supply means for mixing the citric acid at a predetermined concentration is provided, the citric acid supply means automatically operates at a predetermined time. Cleaning between the electrodes is performed at a predetermined concentration and temperature,
The manual work of washing with citric acid is not required.

According to the water purifying apparatus of the sixth aspect of the present invention, the concentration of citric acid is adjusted so that the pH of water at the time of washing with citric acid is in the range of 1 to 3.5. The coating mainly composed of aluminum oxide Al (OH) 3 can be effectively ionized and removed, and good purification performance can be maintained for a long time.

According to the water purifying apparatus according to the seventh aspect of the present invention, since 0.01 to 1% by weight of the corrosion inhibitor is mixed with citric acid, the water purifying apparatus comes into contact with citric acid at the time of washing with citric acid. Can be prevented from being corroded and deteriorated by the strong acid, and the reliability of the device is improved. According to the water purification apparatus according to claim 8 of the present invention, the counting means for measuring the number of times of coagulation is provided, and the citric acid washing is performed when the number of times of coagulation reaches the predetermined number. If the coagulation operation is not performed, the counting is not performed, so that the coating film can be effectively cleaned without performing unnecessary cleaning work.

According to the water purifying apparatus of the ninth aspect of the present invention, the temperature of the water to be purified is controlled in the range of 40 ° C. to 70 ° C. by controlling the heating means at the time of citric acid washing. Becomes highly active, and the film removing effect is improved. Further, it is possible to prevent a decrease in device reliability due to thermal stress caused by cleaning at a temperature exceeding 70 ° C.

According to the water purifying apparatus according to the tenth aspect of the present invention, since the electrode signal detecting means is provided, and the notifying means for notifying the citric acid cleaning timing in accordance with the signal of the electrode signal detecting means is provided. The state of electrode film formation can be constantly monitored, and a notification is given, so that citric acid cleaning can be performed at a suitable time that does not affect the purification performance. When used in combination with the counting means, it is possible to cope with variations in the formation of electrode films due to differences in water quality such as conductivity or hardness, pH, and bathing load, and to maintain good purification performance over a long period of time.

According to the water purifying apparatus of the eleventh aspect of the present invention, since the rinsing operation for causing the citric acid remaining in the circulation circuit to flow out of the circulation circuit after the citric acid cleaning is performed, the citric acid circulation path Oxidation and corrosion of the constituent members due to remaining in the inside can be prevented, so that device reliability is improved. Also,
In the next purification of bath water, it is possible to prevent an increase in the total organic carbon amount TOC due to the remaining citric acid and prevent a decrease in purification performance due to the proliferation of bacteria.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a hot water supply bath apparatus showing one embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part of the water purification device.

FIG. 3 is a time chart of the electrolysis current and circulation means.

FIG. 4 is a life characteristic diagram showing the relationship between the elapsed years and the electrolytic voltage.

FIG. 5 is a main part configuration diagram of a water purification device showing a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a water purification device showing a conventional example of the present invention.

FIG. 7 is a sectional view of the aggregating means.

[Explanation of symbols]

 Reference Signs List 8 water purification device 11 heating means 17 circulation path 18 circulation means 19 citric acid supply means 20 aggregation means 23 filtration means 30 cathode (casing) 31 aluminum anode 51 control means 52 circulation control means 53 electrolysis control means 54 aggregation control means (electrode Control means) 58 counting means 59 notification means 60 electrode signal detection means 61 rinsing cleaning control means

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (Reference) C23F 1/00 C23G 3/00 Z C23G 1/02 F24H 1/00 602L 3/00 B01D 35/02 J // F24H 1 / 00 602 (72) Inventor Yu Kawai 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. Kazunori Sone 1006 Kadoma, Kazuma, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (11)

[Claims] At least one pair of electrodes comprising a cathode and an anode made of aluminum, an electrode control means for controlling the energization of the electrodes, a circulation means for passing water between the electrodes, Heating means for passing water through the electrode,
The electrode control means and a control means for controlling the circulation means and the heating means, the intermittent operation of the circulation means at a predetermined cycle during the electrolysis operation by energizing the electrode, and the operation of the circulation means A method of removing an electrode film, in which electrolysis is performed while power supply to the electrodes is stopped, and citric acid is dissolved in water at a predetermined time to wash a film formed between the electrodes at a predetermined concentration, time, and temperature. 2. The hydrogen ion concentration (p) of water during washing with citric acid.
2. The method according to claim 1, wherein the concentration of citric acid is adjusted so that H) is in the range of 1 to 3.5. 3. The method for removing an electrode film according to claim 1, wherein 0.01 to 1% by weight of a corrosion inhibitor is mixed with citric acid. 4. An apparatus comprising: a means for circulating water to be purified; an electrode comprising an aluminum anode and a cathode provided in a circulation path; An aggregating means for electrically aggregating suspended substances contained in the water to be purified; a filtering means provided downstream of the aggregating means for physically filtering the floc generated by the aggregating means; Has a heating means for heating the electrode, performs the intermittent operation of the circulating means at a predetermined cycle during the aggregation operation by energizing the electrode, and stops the energization to the electrode during the operation of the circulating means to perform the electrolysis. A water purification device having a coagulation control means for dissolving citric acid in circulating water at a predetermined time and washing a film formed between the electrodes at a predetermined concentration, time and temperature. 5. The water purifying apparatus according to claim 4, further comprising citric acid supply means for mixing citric acid at a predetermined concentration in the circulation circuit of the purified water. 6. The hydrogen ion concentration (p) of water during washing with citric acid.
The water purification device according to any one of claims 4 to 5, wherein the citric acid concentration is adjusted so that H) is in the range of 1 to 3.5. 7. The water purification apparatus according to claim 4, wherein 0.01 to 1% by weight of a corrosion inhibitor is mixed with citric acid. 8. A counting means for counting the number of times of coagulation operation is provided,
The water purifying apparatus according to any one of claims 4 to 7, wherein the citric acid cleaning is performed when the signal of the counting means reaches a predetermined number of times. 9. The water purifying apparatus according to claim 4, wherein the temperature of the water to be purified is controlled in the range of 40 ° C. to 70 ° C. by controlling the heating means during the citric acid washing. 10. An apparatus according to claim 4, further comprising an electrode signal detecting means for detecting a voltage or a current between the electrodes, and an informing means for informing a citric acid washing time in accordance with a signal from said electrode signal detecting means. The water purification device according to claim 1. 11. The water purifying apparatus according to claim 4, wherein after the citric acid cleaning, a rinsing operation is performed to cause citric acid remaining in the circulation circuit to flow out of the circulation circuit.