JP2023050354A - Water treatment apparatus - Google Patents

Abstract

To provide a water treatment apparatus capable of effectively removing a humic substance from treatment target water.SOLUTION: A water treatment apparatus comprises: an electrolysis cell 4 to which treatment target water 21 including a humic substance 11b flows in; a first electrode 10a and a second electrode 10b soaked in the treatment target water 21 in the electrolysis cell 4; and an electric source 5 applying electric current to between the first electrode 10a and the second electrode 10b, wherein the first electrode 10a and the second electrode 10b are composed of a material from which iron ion 11c is eluted by applying electric current from the electric source 5. The first electrode 10a and the second electrode 10b are arranged in a manner that, on applying electric current from the electric source 5, a first product material 11f formed by reaction of the humic substance 11b and iron ion 11c on the anode side aggregates with a second product material 11g formed by reaction of hydroxide ion 11d and iron ion 11c on the cathode side to form a floc 11h.SELECTED DRAWING: Figure 1

Description

The present invention relates to water treatment equipment.

BACKGROUND ART Conventionally, there have been disclosed water purification methods for purifying water from water sources such as wells, rivers, ponds, etc. for use as drinking water or domestic water. Substances that are removed from water by purification are, for example, inorganic suspended matter that causes turbidity or dissolved organic matter that causes color and odor. Regarding dissolved organic matter, for example, water from peat regions represented by the islands of Kalimantan and Sumatra in Indonesia contains a high concentration of dissolved organic matter called humic substances, so it has a high degree of color and is used as domestic water. In some cases, it causes problems such as coloration of the laundry. As a method for removing humic substances, there is known a coagulation-sedimentation method (see Patent Document 1) in which humic substances are precipitated and removed using a flocculating agent.

JP-A-10-216738

When trying to remove humic substances, which cause chromaticity, from highly colored water containing humic substances by the coagulation-sedimentation method, it is difficult to coagulate them because the molecules of humic substances are small, and precipitation is easy. There is a problem that it is difficult to form large flocs (coagulant and sediment due to suspended matter or dissolved matter).

An object of the present invention is to solve the conventional problems described above, and to provide a water treatment apparatus capable of efficiently removing humic substances from water to be treated, which has been difficult with conventional coagulation sedimentation techniques. and

In order to achieve this object, the water treatment apparatus according to the present invention comprises an electrolytic cell into which water to be treated containing humic substances flows, and first and second electrodes that are immersed in the water to be treated in the electrolytic cell. and a power source that applies a current between the first electrode and the second electrode, and at least one of the first electrode and the second electrode is made of a material that elutes iron ions by applying a current from the power source. When a current is applied from a power supply, the first electrode and the second electrode are configured to produce a first product formed by the reaction of humic substances and iron ions on the anode side and hydroxide ions on the cathode side. The secondary products formed by reaction with iron ions are arranged to agglomerate to form flocs.

ADVANTAGE OF THE INVENTION According to this indication, the water treatment apparatus which can remove a humic substance from to-be-processed water efficiently can be provided.

FIG. 1 is a schematic diagram of a water treatment apparatus 1 according to an embodiment of the present invention during purification treatment. FIG. 2 is a schematic diagram of electrolysis in the electrolytic cell of Embodiment 1 according to the present invention. FIG. 3 is a diagram showing the chromaticity of treated water of the water treatment apparatus 1 of the embodiment according to the present invention. FIG. 4 is a diagram showing the chromaticity of treated water of the water treatment apparatus 1 according to the embodiment of the present invention.

A water treatment apparatus according to the present invention comprises an electrolytic cell into which water to be treated containing humic substances flows, a first electrode and a second electrode immersed in the water to be treated in the electrolytic cell, and a first electrode and a second electrode. a power source that applies a current between the first electrode and the second electrode, at least one of the first electrode and the second electrode is made of a material that elutes iron ions by applying a current from the power source, the first electrode and the second electrode is the first product formed by the reaction of humic substances and iron ions on the anode side and the second product formed by the reaction of hydroxide ions and iron ions on the cathode side when a current is applied from a power source. The two products are arranged so that they agglomerate to form flocs. According to such a configuration, by applying an electric current to the water treatment device, the first product and the second product can be formed, and the aggregation of the first product and the second product causes humin A textured floc can be formed. Therefore, humic substances having a small size can be precipitated as flocs, and humic substances can be efficiently removed from the water to be treated.

Moreover, in the water treatment apparatus according to the present invention, the inter-electrode distance between the first electrode and the second electrode may be 0.5 mm or more. With such a configuration, it is possible to reduce the clogging between the electrodes of the passive state peeled off from the electrodes. Therefore, it is possible to reduce the possibility that the generation of the first product and the second product and the formation of flocs will be inhibited by the current not flowing through the passive state-filled portion.

Further, in the water treatment apparatus according to the present invention, the concentration of iron ions eluted from at least one of the first electrode and the second electrode is doubled or more with respect to the concentration of humic substances contained in the water to be treated by the power supply. Apply a current such that With such a configuration, sufficient iron ions are eluted to produce the first product and the second product. Therefore, flocs, which are aggregates of the first product and the second product, can be efficiently formed, and the humic substances 11b in the water 21 to be treated can be efficiently removed.

Further, in the water treatment device according to the present invention, the first electrode and the second electrode are both made of a material from which iron ions are eluted by applying a current from a power supply, and when a current is applied, the first electrode and the second electrode. By adopting such a structure, the passivity can be peeled off from the electrode surface where the passivity accumulates and the current cannot be sufficiently applied. Therefore, it is possible to suppress the accumulation of passivation, thereby suppressing the decrease in purification treatment efficiency due to the current not flowing due to the passivity.

Moreover, the water treatment apparatus according to the present invention further includes a separation section for removing flocs from the water to be treated that has undergone the electrolytic treatment. With such a configuration, it is possible to more reliably remove flocs remaining in the treated water. Therefore, the removal efficiency of humic substances from the water to be treated can be improved.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. It should be noted that the following embodiment is an example that embodies the present invention, and does not limit the technical scope of the present invention. In addition, each drawing described in the embodiment is a schematic drawing, and the ratio of the size and thickness of each component in each drawing does not necessarily reflect the actual dimensional ratio. .

Before specifically describing the embodiments of the present invention, the problems of the prior art will be described again, and the outline of the embodiments will be described.

As mentioned above, raw water from peat areas contains dissolved organic matter, such as humic substances, and can be highly colored. For example, in Sumatra, Indonesia, raw water has a chromaticity of 100 TCU to 500 TCU (TCU: true color units), and exhibits a color similar to that of black tea. The humic substance contained in raw water is a product produced by decomposition of plants and the like by microorganisms. Humic substances are roughly divided into fume substances, humic acid, and fulvic acid, and the molecular size decreases in the order of fume substances, humic acid, and fulvic acid. Among humic substances, those that precipitate in an alkaline aqueous solution are called fumes, those that are soluble in an alkaline aqueous solution but precipitate in an acid aqueous solution are called humic acids, and those that are soluble in both an alkaline and acid aqueous solution are called fulvic. called acid. Even if the coagulation-sedimentation method is applied to dissolved substances such as humic substances, which are originally extremely small in size, it is difficult to coagulate the substances to be removed into flocs large enough for precipitation, and sufficient purification performance cannot be obtained. . Therefore, the present inventors conducted repeated basic studies and found that a component that aggregates and coarsens humic substances can also be produced by electrolytic treatment using an iron electrode. Specifically, a direct current is applied between iron electrodes immersed in water containing humic substances. As a result, iron ions are eluted from the anode side, iron ions and humic substances form a chelate complex, and hydroxide ions and iron ions generated on the cathode side form iron hydroxide. They found that the chelate complex and iron hydroxide aggregate with each other to form flocs large enough for precipitation. Flocs can be easily removed by precipitation or a solid-liquid separation method such as MF (Microfiltration) membrane separation with a filtration accuracy of about 0.1 to 1 μm. The water treatment apparatus of this embodiment is an apparatus capable of removing humic substances from water to be treated using this aggregation action.

(Embodiment 1)
A water treatment apparatus 1 according to Embodiment 1 will be described with reference to FIG. FIG. 1 is a schematic diagram of a water treatment apparatus 1 according to Embodiment 1 of the present invention during purification treatment.

As shown in FIG. 1, the water treatment apparatus 1 of Embodiment 1 is an apparatus for purifying water 21 to be treated, which contains humic substances and has a high degree of chromaticity, for use as colorless and transparent domestic water. Specifically, the water treatment device 1 includes an inlet 2, a purified water outlet 3, an electrolyzer 4, a power source 5, a separation section 6, an inflow pipe 7, a water pipe 8, and a discharge pipe 9. , a first electrode 10a and a second electrode 10b.

The inflow port 2 is an opening for introducing the water 21 to be treated, which is pressure-fed from the outside of the water treatment apparatus 1, into the apparatus. Water to be treated 21 is introduced into the water treatment apparatus 1 from a water source such as a well, a river, or a pond through the inlet 2 . The inflow port 2 is provided in a housing that constitutes the water treatment device 1, and is connected to the electrolytic cell 4 through an inflow pipe 7 inside the device.

The purified water outlet 3 is an opening for taking out the treated water 21 treated by the water treatment device 1 as the treated water 22 to the outside of the device. The flow rate and purified water discharge port 3 are provided in a housing that constitutes the device, and are connected to a discharge pipe 9 inside the device.

The electrolytic cell 4 is a container for fixing the first electrode 10a and the second electrode 10b inside, taking in the water 21 to be treated, and performing electrolysis. The inside of the electrolytic bath 4 is connected to an inflow pipe 7 and a water pipe 8 for communication.

A power source 5 is connected to the first electrode 10a and the second electrode 10b and applies a current between the first electrode 10a and the second electrode 10b. The power supply 5 also incorporates a circuit for reversing the polarities of the currents applied to the first electrode 10a and the second electrode 10b.

The separation unit 6 separates and removes aggregates generated by electrolysis in the electrolytic bath 4 and containing humic substances. The separation unit 6 is a filtration membrane with a filtration accuracy of 1 μm. As the filtration membrane used in the separation unit 6, for example, an MF filtration membrane can be used. The separation unit 6 is connected to the water pipe 8 and the discharge pipe 9 for communication.

The inflow pipe 7 is connected to the inflow port 2 and the electrolytic cell 4 and delivers the water to be treated 21 taken in from the inflow port 2 to the electrolytic cell 4 .

The water pipe 8 is connected to the electrolytic cell 4 and the separation unit 6 and delivers the water 21 to be treated by electrolysis in the electrolytic cell 4 to the separation unit 6 .

The discharge pipe 9 is communicated with the separation section 6 and the purified water discharge port 3 . The discharge pipe 9 delivers the water to be treated 21 from which the aggregates have been separated and removed in the separation unit 6 to the purified water discharge port 3 .

The water to be treated 21 is continuously taken in from the inflow port 2 and purified by flowing through the inflow pipe 7-the electrolytic bath 4-the water pipe 8-the separator 6-the discharge pipe 9. FIG. Purified water 21 to be treated is continuously taken out as post-treatment water 22 from the purified water discharge port 3 . The flow rate of the water to be treated 21 taken into the inflow port 2, the flow rate of the water to be treated 21 flowing through the inflow pipe 7, the flow rate of the water to be treated 21 flowing into and out of the electrolytic cell 4, the water to be treated 21 flowing through the water pipe 8 The flow rate, the flow rate at which the water 21 to be treated flows into and out of the separation section 6, the flow rate at which the water 21 to be treated flows through the discharge pipe 9, and the flow rate at which the treated water 22 is taken out from the purified water discharge port 3 are all the same.

Both the first electrode 10a and the second electrode 10b are made of iron. The first electrode 10a and the second electrode 10b are installed facing each other, and the distance between the electrodes is 3 mm. In addition, it is preferable that the distance between the electrodes is 0.5 mm or more. This is to reduce the possibility that flocs 11h, which will be described later, or passive states formed on the electrodes clog the gap between the electrodes. In addition, as the distance between the electrodes increases, the frequency of the reaction between the iron ions eluted from the anode and the hydroxide ions generated from the cathode, which is a reaction described later, may decrease. The probability of occurrence of the reaction in which the first product 11f generated in the vicinity and the second product 11g generated mainly between the electrodes to form the flocs 11h decreases is increased. That is, by reducing the distance between the electrodes, the formation efficiency of the second product 11g and the flocs 11h is improved. Therefore, it is preferable that the distance between the electrodes is small enough to prevent clogging of the passive state and the flocs 11h.

The first electrode 10a and the second electrode 10b are connected to the power supply 5. As shown in FIG. A direct current is applied between the first electrode 10a and the second electrode 10b by the power supply 5, and the water 21 to be treated is electrolyzed. One of the first electrode 10a and the second electrode 10b is on the anode side, and the other is on the cathode side. By electrolysis, iron ions 11c are eluted from the anode side electrode and hydroxide ions are generated from the cathode side. The iron ions 11c and hydroxide ions 11d are both components forming flocs 11h that take in the humic substance 11b. The amount of eluted iron ions 11c can be controlled by the amount of current applied, and the amount of eluted iron ions 11c increases or decreases in proportion to the increase or decrease in the amount of current. Therefore, by setting the amount of electric current to be applied according to the concentration of the humic substances 11b contained in the water 21 to be treated, the elution amount of the iron ions 11c can be controlled according to the water quality, and the water 21 to be treated can be purified. be able to.

Also, the first electrode 10a and the second electrode 10b are reversed by a circuit built in the power source 5. FIG. Both the first electrode 10a and the second electrode 10b are made of iron. Therefore, since it can act as either an anode or a cathode in the later-described electrolysis reaction, the purification process can be continued even during the polarity reversal.

Furthermore, by reversing the anode side and the cathode side by reversing the polarity, the electrodes that emit the iron ions 11c can be replaced. Therefore, consumption of only one electrode can be suppressed.

In addition, the reversal of polarity promotes chemical reactions in the vicinity of the electrodes. In other words, the reversal of the poles can improve the frequency of occurrence of the reaction in the purification process. For example, both the iron ions 11c eluted before the pole reversal and the hydroxide ions 11d generated after the pole reversal are present at relatively high concentrations near the pole that has changed from the anode to the cathode due to the pole reversal. Therefore, the second product 11g is likely to be generated by the polarity reversal. Furthermore, flocs 11h are produced by reacting the produced second product 11g with the first product 11f produced before the polarity reversal. Moreover, both the hydroxide ions 11d generated before the pole reversal and the iron ions 11c eluted after the pole reversal are present at relatively high concentrations near the pole where the cathode has become the anode due to the pole reversal. Therefore, the second product 11g is likely to be generated by the polarity reversal. Furthermore, the humic substance 11b, which had not reacted before the polarity reversal due to the relatively low concentration of the iron ions 11c, reacts with the eluted iron ions 11c, facilitating the formation of the first product 11f. Then, the first product 11f and the second product 11g react with each other to easily generate flocs 11h. Therefore, by performing the polarity reversal, it is possible to increase the occurrence frequency of the formation reaction of the second product 11g and the floc 11h. While the polarity reversal for removing the passive state is performed, for example, once a week, the polarity reversal for promoting the chemical reaction may be performed about once every 30 minutes.

Now, with reference to FIG. 2, electrolysis in the electrolytic cell 4 will be described in detail. FIG. 2 is a schematic diagram of electrolysis in the electrolytic cell 4 of Embodiment 1 according to the present invention.

The first electrode 10a arranged inside the electrolytic cell 4 is made of iron. As shown in formula (1), after the water 21 to be treated flows into the electrolytic cell 4, a current is applied by the power source 5 between the first electrode 10a as the anode and the second electrode 10b as the cathode, and from the anode side Fe ²⁺ is eluted by electrolysis.

Fe→Fe ²⁺ +2e ⁻ Formula (1)
Most of the eluted Fe ²⁺ is rapidly oxidized to Fe ³⁺ (iron ions 11c). A method for controlling the concentration of iron ions 11c will be described. When the current value applied between the first electrode 10a and the second electrode 10b by the power supply 5 is x [A], Fe ²⁺ generated per second according to the formula (1) and Faraday's law of electrolysis The molar amount of is x/(96485×2) [mol] and the weight of Fe ²⁺ is 55.85×x/(96485×2×10 ³ ) [mg]. Let y [L/s] be the flow rate at which the water 21 to be treated is taken into the electrolytic cell 4, the concentration of Fe ²⁺ taken into the water 21 to be treated is 55.85×x/(96485×2×y×10 ³ ) [mg/L], ie 2.89×(x/y)×10 ⁻⁷ [mg/L]. Since the concentration of Fe ²⁺ is the same as the concentration of iron ions 11c that are Fe ³⁺ , the concentration of iron ions 11c eluted in the water 21 to be treated is 2.89×(x/y)×10 ⁻⁷ [mg /L].

Iron ion 11c combines with humin 11b to form first product 11f. The humic substance 11b is contained in the water to be treated 21, and its size is about 10 nm to 100 nm. Therefore, it is difficult to remove them with an MF membrane or the like having a filtration accuracy of about 0.1 to 1 μm. However, when the iron ions 11c and the humic substance 11b are combined, the first product 11f, which is a small chelate complex with a size of about 10 nm to 100 nm, is easily aggregated with various particles. Since the first product 11f is a chelate complex, it easily adsorbs the second product 11g, which will be described later.

On the other hand, at the cathode, the water molecules 11a are electrolyzed to produce hydrogen 11e and hydroxide ions 11d, as shown in formula (2).

2H ₂ O+2e ⁻ →H ₂ +2OH ⁻ Formula (2)
As shown in formula (3), the generated hydroxide ions 11d combine with the iron ions 11c to form the second product 11g, which is iron hydroxide particles with a size of about 100 nm to 1 μm.

Fe ³⁺ +3OH ⁻ →Fe(OH) ₃ Formula (3)
The first product 11f and the second product 11g have the property of mutually adsorbing and aggregating, and the agglomeration of the first product 11f and the second product 11g causes coarse flocs 11h to be formed. It is formed. The flocs 11h grow inside the electrolytic bath 4 and inside the water pipe 8 . Since the coarse flocs containing the humic substances 11b eventually reach a size of several μm or more, they can be easily separated by MF membrane filtration (filtration accuracy of about 0.1 to 1 μm) in the subsequent separation unit 6. . The water from which the flocs 11h have been separated and removed is obtained as post-treatment water 22 from the discharge pipe 9 and the purified water discharge port 3, and is supplied as domestic water.

The purification process of the water to be treated 21 in the water treatment apparatus 1 will be explained again. Water to be treated 21 containing humic substances 11 b is introduced into the water treatment apparatus 1 through the inlet 2 and flows into the electrolytic cell 4 . The water 21 to be treated is electrolyzed by the first electrode 10 a and the second electrode 10 b in the electrolytic bath 4 . Due to electrolysis, the reaction of formula (1) occurs at the anode, and the iron ions 11c are eluted. The humic substances 11b in the water 21 to be treated react with the iron ions 11c to produce the first product 11f. Further, as shown in the formula (3), the hydroxide ions 11d generated by the reaction of the formula (2) during electrolysis react with the iron ions 11c to produce the second product 11g. The first product 11f, which is a chelate complex, and the second product 11g adsorb to each other and aggregate to form flocs 11h. That is, the humic substances 11b in the water 21 to be treated are taken into the flocs 11h. The water containing the flocs 11 h is sent to the separation section 6 through the water pipe 8 . The separation unit 6 has an MF membrane and separates the flocs 11h by filtering. The water from which the flocs 11h have been separated is sent to the purified water discharge port 3 through the discharge pipe 9, and discharged as the treated water 22 from the purified water discharge port 3. FIG. The post-treatment water 22 can be used as domestic water with reduced chromaticity.

Here, with reference to FIG. 3, experimental results of a humic substance purification test by the water treatment device 1 are shown. FIG. 3 is a diagram showing the chromaticity of the treated water 22 of the water treatment apparatus 1 of the embodiment according to the present invention. For comparison, the chromaticity of the water to be treated used in the experiment and the experimental results of coagulating with PSI (Poly Silicate Iron) and then filtering with an MF membrane as a general coagulation-sedimentation method are also shown.

The chromaticity of 300 TCU of the water to be treated 21 is mainly due to humic substances 11b, and compared with the chromaticity of 255 TCU after purification by a general coagulation-sedimentation method, the water after purification by the water treatment device 1. The chromaticity of the post-treatment water 22 is reduced to 20 TCU, and the humic substances 11b are well removed.

In addition, when the electrolysis described so far is performed for a long time (for example, 5 days), a passive state such as iron hydroxide is gradually formed on the surface of the second electrode 10b, which is the cathode, and is applied between the electrode plates. This may cause problems such as a decrease in the current applied. Since this passivation can be stripped off by switching the polarity of the electrodes, the polarity of the voltage applied between the first electrode 10a and the electrode plate is changed periodically (for example, once a week). It is desirable that the inversion is controlled by a circuit incorporated in the power supply. After the polarity reversal, after waiting until the passivation is peeled off while the current is applied, the polarity may be reversed to return to the original polarity. In the water treatment device 1, not only the first electrode 10a but also the second electrode 10b are made of iron. Therefore, after the polarity reversal, the first electrode 10a acts as a cathode and the second electrode 10b acts as an anode. Therefore, it is possible to continuously perform the same treatment as the treatment represented by formulas (1) to (3) while stripping off the passive state. In addition, since the size of the passive state that peels off is approximately 0.5 mm, by separating the electrode plates by at least 0.5 mm or more, the passive state that has fallen off between the electrodes clogs the space, and current does not flow in the clogged portion. , it is possible to reduce the possibility that the electrolysis shown in the formulas (1) to (3) cannot be performed. Furthermore, it is desirable that the plates are arranged parallel to the direction of water flow in the electrolytic cell in order to facilitate the stripping of the passivation. In addition, the concentration of the iron ions 11c eluted from the first electrode 10a or the second electrode 10b is set to form a chelate complex with the humic substances 11b in the water 21 to be treated and to obtain a sufficient amount of iron hydroxide. It is desirable to make it twice or more the density|concentration of the humic substance 11b.

Here, with reference to FIG. 4, the relationship between the elution concentration of iron ions and the removal efficiency of humic substances will be described in detail. FIG. 4 shows the result of removing humic substances from water 21 to be treated with a concentration of 100 mg/L of humic substances 11b in the water treatment apparatus 1 according to Embodiment 1 of the present invention, and measuring the chromaticity of the treated water 22. is. When the elution concentration of iron is changed from 10 mg/L to 300 mg/L, the chromaticity, which is an indicator of the concentration of humic substances, at an iron ion concentration of 200 mg/L or more, which is more than twice the concentration of humic substances of 100 mg/L. 5 TCU and sufficiently lowered post-treatment water 22 can be obtained.

When the elution concentration of iron is low (10 mg/L to 150 mg/L in FIG. 4), the generated iron ions 11c are consumed by the formation of the second product 11g, and the first product 11f becomes the humic substance 11b. becomes difficult to capture. Alternatively, although the first product 11f and the second product 11g are produced, they are in small amounts, so that the formation reaction of the flocs 11h is difficult to occur. Therefore, the chromaticity of the water to be treated 21 is increased by the humic substance 11b or the first product 11f or the second product 11g. On the other hand, when the elution concentration of iron is more than twice the concentration of humic substances 11b (200 mg/L to 300 mg/L in FIG. 4), iron ions 11c are not only the second product 11g, but also the second product 11g. It is also fully available for the production of one product 11f. Therefore, the first product 11f and the second product 11g are sufficiently present in the water, and the formation reaction of the flocs 11h easily occurs. Therefore, the chromaticity of the water to be treated 21 can be reduced.

On the other hand, if the elution concentration of iron is excessively increased, excessive iron hydroxide will be generated, so it is not preferable to elute iron ions 11c in excess of the amount of humic substance 11b taken in.

Therefore, the concentration of the iron ions 11c eluted from the first electrode 10a or the second electrode 10b should be such that it forms a chelate complex with the humic substances 11b in the water 21 to be treated and a sufficient amount of iron hydroxide is obtained. In the water treatment device 1, the current was applied so that the concentration of the humic substances 11b was at least twice that of the humic substances 11b. Note that the concentration of the iron ions 11c eluted from the first electrode 10a or the second electrode 10b, which is set to be twice the concentration of the humic substance 11b, is the same as the iron ions 11c and the hydroxide ions 11d that react with the humic substance 11b. This is the concentration containing the reacting iron ions 11c.

As described above, in the water treatment apparatus 1 , the water to be treated 21 can be purified by removing humic substances by performing purification treatment in the above-described electrolytic bath 4 .

As described above, according to the water treatment device 1 according to Embodiment 1, the following effects can be obtained.

(1) The water treatment apparatus 1 includes an electrolytic bath 4 into which water to be treated 21 containing humic substances 11b flows, a first electrode 10a and a second electrode 10b immersed in the water to be treated 21 in the A power supply 5 that applies a current between the one electrode 10a and the second electrode 10b, and at least one of the first electrode 10a and the second electrode 10b is applied with a current from the power supply 5, whereby iron ions are eluted. The first electrode 10a and the second electrode 10b are formed by the reaction between the humic substances 11b and the iron ions 11c on the anode side when a current is applied from the power supply 5, and the first product 11f and the , the second product 11g formed by the reaction between the hydroxide ions 11d and the iron ions 11c on the cathode side aggregates to form flocs 11h. According to such a configuration, by applying an electric current to the water treatment device 1, the first product 11f and the second product 11g can be formed, and the first product 11f and the second product 11g aggregate. By doing so, flocs 11h incorporating humic substances 11b can be formed. Therefore, the humic substances 11b having a small size can be precipitated as flocs 11h, and the humic substances 11b can be efficiently removed from the water 21 to be treated.

(2) The water treatment device 1 is configured such that the inter-electrode distance between the first electrode 10a and the second electrode 10b is 0.5 mm or more. With such a configuration, it is possible to reduce the clogging between the electrodes of the passive state peeled off from the electrodes. Therefore, it is possible to reduce the possibility that the generation of the first product 11f and the second product 11g and the formation of the flocs 11h will be inhibited by the current not flowing through the passivated portion.

(3) The water treatment apparatus 1 uses the power source 5 to increase the concentration of the iron ions 11c eluted from at least one of the first electrode 10a and the second electrode 10b with respect to the concentration of the humic substances 11b contained in the water to be treated 21. Current was applied to more than double. With such a configuration, sufficient iron ions 11c are eluted to generate the first product 11f and the second product 11g. Therefore, flocs 11h, which are aggregates of the first product 11f and the second product 11g, can be efficiently formed, and the humic substances 11b in the water 21 to be treated can be efficiently removed.

(4) In the water treatment device 1, the first electrode 10a and the second electrode 10b are both made of a material from which iron ions 11c are eluted by applying a current from the power supply 5, and when a current is applied, the first electrode 10a and the second electrode 10b The polarity is reversed between the one electrode 10a and the second electrode 10b. With such a configuration, the passivity can be peeled off from the electrode surface where the passivity accumulates and the current cannot be sufficiently applied. Therefore, it is possible to suppress the accumulation of passivation, thereby suppressing the decrease in purification treatment efficiency due to the current not flowing due to the passivity. Further, by reversing the anode side and the cathode side by reversing the polarity, the electrodes that emit the iron ions 11c can be replaced. Therefore, it is possible to suppress the decrease of only one electrode.

In addition, since both electrodes are made of a material that elutes iron ions 11c, for example, in the vicinity of the pole that has changed from the anode to the cathode due to pole reversal, the iron ions 11c eluted before pole reversal and the water generated after pole reversal Both oxide ions 11d are present in relatively high concentrations. Moreover, both the hydroxide ions 11d generated before the pole reversal and the iron ions 11c eluted after the pole reversal are present at relatively high concentrations near the pole where the cathode has become the anode due to the pole reversal. Therefore, by performing the polarity reversal, it is possible to increase the occurrence frequency of the formation reaction of the second product 11g and the floc 11h.

(5) The water treatment apparatus 1 further includes a separation unit 6 that removes the flocs 11h from the water 21 to be treated that has undergone the electrolytic treatment. With such a configuration, the flocs 11h remaining in the post-treatment water 22 can be removed more reliably. Therefore, the removal efficiency of humic substances from the water 21 to be treated can be improved.

The present invention has been described above based on the embodiments. Those skilled in the art will understand that these embodiments are merely examples, and that various modifications can be made to combinations of each component or each treatment process, and such modifications are also within the scope of the present invention. I am where I am.

In the water treatment apparatus 1 according to Embodiment 1, for example, a stirring mechanism such as a stirrer or bubbling may be provided inside the electrolytic bath 4 or the water pipe 8 . As a result, the frequency of the reaction between the iron ions eluted from the anode and the hydroxide ions generated from the cathode, and the first product 11f mainly generated near the anode and the second product 11f mainly generated between the electrodes The occurrence frequency of the reaction that forms the floc 11h with the substance 11g is improved. Therefore, the flocs 11h can be formed and grown more quickly and stably, and the water 21 to be treated can be quickly purified.

Moreover, in the water treatment apparatus 1 according to Embodiment 1, the separation unit 6 is configured to perform MF membrane filtration, but the present invention is not limited to this. For example, in the separation unit 6, filtration using granular filter media can be used in addition to MF membrane filtration. Granular filter media include, for example, sand, anthracite, garnet, ceramics, activated carbon, iron oxyhydroxide, manganese sand, etc., as long as they settle in water and have a hardness that makes them difficult to deform under pressure. may be used by stacking in the vertical direction.

Moreover, in the water treatment apparatus 1 according to Embodiment 1, after the electrolysis treatment in the electrolytic bath 4, a polymer flocculant or an inorganic flocculant may be additionally injected. By doing so, the growth of the flocs 11h can be realized more quickly and stably.

Moreover, in the water treatment apparatus 1 according to Embodiment 1, the separation unit 6 is configured to perform MF membrane filtration, but the present invention is not limited to this. For example, the separation section 6 may be a sedimentation tank for sedimenting the flocs 11h. As a result, after the water to be treated 21 after electrolysis flows into the sedimentation tank, the supernatant liquid is taken out after waiting until the flocs 11h settle at the bottom of the sedimentation tank, so that the treated water with a sufficiently low concentration of the humic substances 11b can be obtained. 22 can be obtained. In the case of a sedimentation tank, in order to more reliably control the floc sedimentation time, a valve is provided in the water pipe 8 to prevent continuous inflow of the water to be treated 21 after electrolytic treatment into the separation unit 6. By doing so, the sedimentation time necessary for all the flocs 11h in the sedimentation tank to sediment can be ensured. Further, the electrolytic bath 4 may also function as a sedimentation tank.

Moreover, in the water treatment device 1 according to Embodiment 1, iron is used as the material of the first electrode 10a and the second electrode 10b, but the material is not limited to this. For example, the material of the electrode is preferably iron, but aluminum, which is cheaper than iron, can be used as a material that chelates the humic substance 11b, hydroxides it, and elutes the ions that aggregate with the chelate complex. can also

Moreover, in the water treatment device 1 according to Embodiment 1, iron is used for both electrodes as the material for the first electrode 10a and the second electrode 10b, but the material is not limited to this. For example, iron may be used only for the anode.

Moreover, in the water treatment device 1 according to Embodiment 1, the circuit for controlling the polarity reversal is built in the power supply 5, but the present invention is not limited to this. The polarity reversal may be controlled by manually switching the circuit connecting the electrodes and the power supply 5 .

Further, in the water treatment apparatus 1 according to Embodiment 1, the flow rate of the water to be treated 21 taken into the inflow port 2, the flow rate of the water to be treated 21 flowing through the inflow pipe 7, and the water to be treated 21 entering the electrolytic cell 4 Flow rate of inflow and outflow, flow rate of water to be treated 21 flowing through water pipe 8, flow rate of water to be treated 21 flowing into and out of separation tank 6, flow rate of water to be treated 21 flowing through discharge pipe 9, and treated water 22 is taken out from the purified water discharge port 3 at the same flow rate, that is, the water to be treated 21 flows through each component in the water treatment apparatus 1 at a constant flow rate. do not have. For example, a certain amount of water to be treated 21 may be stored in the electrolytic cell 4 , the stored water to be treated 21 may be electrolyzed, and the electrolyzed water may be sent to the water pipe 8 . As a result, part of the flocs 11h are precipitated in the electrolytic bath 4, so that the amount of the flocs 11h delivered to the separation section 6 is reduced. Therefore, the maintenance frequency of the separation unit 6 (for example, the frequency of replacement of the MF membrane) can be reduced.

INDUSTRIAL APPLICABILITY The water treatment apparatus according to the present invention is useful for removing humins from water containing humic substances and obtaining domestic water with reduced chromaticity.

1 Water Treatment Device 2 Inlet 3 Clean Water Outlet 4 Electrolyzer 5 Power Source 6 Separation Unit 7 Inflow Pipe 8 Water Pipe 9 Discharge Pipe 10a First Electrode 10b Second Electrode 11a Water Molecule 11b Humic Substance 11c Iron Ion 11d Hydroxide Ion 11e hydrogen 11f first product 11g second product 11h floc 21 water to be treated 22 water after treatment

Claims (5)

an electrolytic cell into which water to be treated containing humic substances flows;
a first electrode and a second electrode that are immersed in the water to be treated in the electrolytic bath;
a power supply that applies a current between the first electrode and the second electrode,
At least one of the first electrode and the second electrode is made of a material from which iron ions are eluted by applying a current from the power supply,
When a current is applied from the power source, the first electrode and the second electrode are connected to the first product formed by the reaction between the humic substance and the iron ion on the anode side, and the hydroxide on the cathode side. A water treatment apparatus characterized in that the ions and the second product formed by the reaction with the iron ions are arranged to agglomerate to form flocs. 2. The water treatment apparatus according to claim 1, wherein the inter-electrode distance between said first electrode and said second electrode is 0.5 mm or more. The power supply applies current so that the concentration of the iron ions eluted from at least one of the first electrode and the second electrode is at least twice the concentration of the humic substances contained in the water to be treated. 3. The water treatment device according to claim 1 or 2, wherein a voltage is applied. Both the first electrode and the second electrode are made of a material from which iron ions are eluted by applying a current from the power supply, and when the current is applied, the first electrode and the second electrode are separated. The water treatment device according to any one of claims 1 to 3, wherein the polarity is reversed between them. The water treatment apparatus according to any one of claims 1 to 4, further comprising a separation unit that removes the flocs from the water to be treated.

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