KR20230132268A - Desalination Device and Desalination Method Using a Net Flow in a Constant Direction - Google Patents

Abstract

The present invention is a desalination device for removing contaminants in treated water, comprising: an electrolysis unit including a cathode, an anode, and an anion exchange membrane; a water supply channel located on the cathode side and supplying water to be treated from the outside of the desalination device toward the anion exchange membrane; a treated water discharge channel located on the cathode side and discharging the treated water removed by passing the contaminants through the anion exchange membrane to the anode side to the outside of the desalination device; a washing water supply channel located on the anode side and supplying washing water from the outside of the desalination device to the anion exchange membrane; And a washing water discharge channel located on the anode side and discharging the washing water containing the contaminants transferred from the cathode side through the anion exchange membrane to the outside of the desalination device; a net flow (net) of the washing water. -flow) relates to a desalting device and a desalting method having a linear flow along the longitudinal direction of the washing water supply passage.

Description

Desalination Device and Desalination Method Using a Net Flow in a Constant Direction}

The present invention relates to desalination technology using washing water. More specifically, by supplying treated water discharged from a wastewater facility as washing water with a net flow in a certain direction, damage to the ion exchange membrane and electrodes is prevented and salts in the wastewater are efficiently removed. It's about separation technology.

Existing desalination devices using electrochemical reactions were mainly configured as a batch type or a continuous flow type. However, during the ion exchange process, the surface of the ion exchange membrane within the desalination device was contaminated, and as a result, the concentration gradient in the ion exchange membrane dropped significantly. There is a disadvantage that ion exchange efficiency rapidly decreases. This is because organic substances generated on the surface of the ion exchange membrane during the desalting reaction process are deposited on the surface of the ion exchange membrane and cover the functional groups that play an ion exchange role, resulting in a significant decrease in ion exchange performance.

Therefore, cleaning the surface of the ion exchange membrane is necessary to maintain ion exchange performance. In general, ion exchange membranes are very vulnerable to acids and bases, so acid and base cleaning of the ion exchange membrane is not possible, and the ion exchange membrane must be cleaned periodically without separate scale removal. It is currently being replaced.

Due to the shortcomings of these desalination devices, electrochemical desalination devices equipped with ion exchange membranes cannot be used in most continuous-flow industrial processes, and even in some facilities that are used, continuous electric desalination operation cannot be achieved and ionization occurs after intermittent interruptions. The exchange membrane is currently being replaced. This leads to problems of reduced performance of electrochemical ion exchange facilities and increased maintenance costs, making it difficult to commercialize electrochemical desalination technology using ion exchange membranes.

For this reason, in most cases, ion exchange membranes cannot be used in electrochemical desalination systems for the purpose of chlorine ion separation, and high-performance selective separation of chlorine ions using ion exchange membranes is virtually impossible. In the case of electrical desalination of seawater, chlorine ions are oxidized to chlorine gas and converted to hypochlorous acid without using an ion exchange membrane. However, since all cations and anions move because an ion exchange membrane is not used, chlorine ions from raw water through electrochemistry are transferred. Selective separation is not possible. In addition, the high concentration of chlorine gas, hypochlorous acid, and chlorous acid generated during the desalination process of chlorine ions oxidizes the electrodes, making it impossible to operate the desalination process continuously, and the disadvantage is that the electrodes must be replaced periodically.

Therefore, in order to remove high concentrations of salt from wastewater, the use of an ion exchange membrane is essential, and an electrochemical desalination device must be used to construct a high-performance salt separation system through an ion exchange membrane. However, despite this need, there is no technology to safely separate chlorine ions from raw water, and there is no desalination device that can maintain high efficiency over a long period of time without damaging the ion exchange membrane and electrode even if chlorine ions are separated, so treatment of high-concentration salt wastewater The technology is currently showing its limitations.

The present invention is intended to solve the above-described problem, in which electrochemically separated chlorine ions and contaminants diffused through an ion exchange membrane are washed with a linear net flow, without mixing in the direction of flow within the wash water. , a desalting device and desalting method are provided in which the ion exchange membrane is washed by sequentially passing from the washing water supply passage through the anion exchange membrane to the washing water discharge passage.

According to one embodiment of the present invention, a desalination device for removing contaminants in water to be treated, comprising: an electrolysis unit including a cathode, an anode, and an anion exchange membrane; a water supply channel located on the cathode side and supplying water to be treated from the outside of the desalination device toward the anion exchange membrane; a treated water discharge channel located on the cathode side and discharging the treated water removed by passing the contaminants through the anion exchange membrane to the anode side to the outside of the desalination device; a washing water supply channel located on the anode side and supplying washing water from the outside of the desalination device to the anion exchange membrane; And a washing water discharge channel located on the anode side and discharging the washing water containing the contaminants transferred from the cathode side through the anion exchange membrane to the outside of the desalination device; a net flow (net) of the washing water. -flow) provides a desalination device having a linear flow along the longitudinal direction of the washing water supply flow path.

In addition, according to another embodiment of the present invention, as a desalination method for removing contaminants in water to be treated, the water to be treated is directed to the anion exchange membrane through the cathode of the electrolysis unit through the water to be treated supply passage. A supply step of treated water supplied to; A contaminant transfer step of removing contaminants in the treated water by passing them through the anion exchange membrane and transferring them to the anode side; A discharge step of discharging the treated water from which the contaminants have been removed from the anion exchange membrane, through the cathode, and discharging the treated water to the outside through a treated water discharge passage; A washing water supply step of supplying washing water through a washing water supply passage toward the anion exchange membrane; and a discharge step of discharging the washing water containing the contaminants transferred through the anion exchange membrane through the anode to the outside through the washing water discharge passage, wherein the net flow of the washing water is in the washing water supply passage. A desalting method having a linear flow along the longitudinal direction is provided.

Using the desalination device and desalination method of the present invention, the washing water is continuously injected in only one direction along the washing water supply flow path and at the same time continuously discharged along the washing water discharge flow path, resulting in the surface of the ion exchange membrane being continuously cleaned. Salt, organic contaminants, or ammonia contained in the washing water can be moved toward the anode without backflow. Accordingly, wastewater containing a high concentration of salt can be treated with high efficiency in a simpler process.

Figure 1 is a diagram schematically showing a desalination device using laminar flow according to Example 1.
Figure 2 is a diagram schematically showing a desalination device using turbulent flow according to Comparative Example 1.
Figure 3 is a diagram comparing the pH of the washing water finally discharged from the desalination device according to Example 1 and the final effluent water from the desalination device according to Comparative Example 1 according to current density.
Figure 4 is a diagram comparing the concentration of chlorine ions (Cl ^- ) in the treated water flowing in from the desalination device according to Example 1 and the final outflow washing water according to the current density.
Figure 5 is a diagram comparing the COD of the washing water finally discharged from the desalination device according to Example 1 and the final discharge water from the desalination device according to Comparative Example 1 according to current density.
Figure 6 is a diagram comparing the concentration of ammonium ions (NH ₄ ⁺ ) in the washing water finally discharged from the desalination device according to Example 1 and the final discharge water from the desalination device according to Comparative Example 1 according to current density.
Figure 7 is a diagram comparing theoretical and actual values for the fluxes of COD, ammonium ions, and chlorine ions on the surface of the anion exchange membrane of the desalination device according to Example 1 and the desalination device according to Comparative Example 1.

Hereinafter, with reference to the attached drawings, the method of treating decontamination waste liquid according to the present invention will be described in detail so that a person skilled in the art can easily carry out the method.

A desalination device according to an embodiment of the present invention is a desalination device for removing contaminants in treated water, including an electrolysis unit including a cathode, an anode, and an anion exchange membrane; a water supply channel located on the cathode side and supplying water to be treated from the outside of the desalination device toward the anion exchange membrane; a treated water discharge channel located on the cathode side and discharging the treated water removed by passing the contaminants through the anion exchange membrane to the anode side to the outside of the desalination device; a washing water supply channel located on the anode side and supplying washing water from the outside of the desalination device to the anion exchange membrane; And a washing water discharge channel located on the anode side and discharging the washing water containing the contaminants transferred from the cathode side through the anion exchange membrane to the outside of the desalination device, wherein the net flow of the washing water is the Provided is a desalination device having a linear flow along the longitudinal direction of a washing water supply flow path.

Desalination technology is a technology that desalinates water by removing various suspended substances or ionic components contained in contaminated water such as seawater or wastewater. It involves an evaporation method that evaporates moisture using a heat source such as fossil fuel or electricity, and a separation membrane that removes foreign substances. There is a filtration method that removes ions by filtering them out, and an electrodialysis method that removes ions using the electrolysis action of electrode cells.

The evaporation method uses fossil fuels or electricity as a heat source to evaporate moisture. When applying the evaporation method, the volume of the desalination device used is large, which makes it inefficient. Energy consumption increases, which not only increases the manufacturing cost, but also increases the consumption of fossil fuels. It causes air pollution due to its use. The filtration method requires applying high pressure to the separation membrane to remove foreign substances, which increases energy costs, and the electrodialysis method requires continuous replacement of electrode cells, which not only causes waste due to replacement of electrode cells, but also causes additional human and material costs. There are increasing disadvantages.

The desalination device according to the present invention supplies washing water having a linear flow along the longitudinal direction of the washing water supply passage. Specifically, the net flow of the washing water is from the outside of the desalination device along the washing water supply passage to the anion exchange membrane. It may have a linear flow, a flow in a direction parallel to the anion exchange membrane, and a linear flow in a direction from the anion exchange membrane to the outside of the desalination device along the washing water discharge path.

Accordingly, the ion-exchanged contaminants are moved toward the anode without backflow by the washing water having a constant forward flow, and as a result, oxidative decomposition of the cationic functional group contained in the ion exchange membrane can be prevented. Specifically, among the contaminants, chlorine ions in particular are converted to chlorine-based oxidants at the anode of the desalination device, then oxidize and decompose other contaminants contained in the washing water or separated from the water to be treated, and are converted back to chlorine ions. It is possible to prevent oxidative decomposition of the cationic functional group contained in the ion exchange membrane due to countercurrent flow, and has the effect of enabling highly efficient desalination without separate ion exchange membrane replacement or washing.

The water to be treated may be wastewater that is subject to treatment in a separate wastewater treatment facility. Specifically, the water to be treated may be food wastewater, livestock wastewater, landfill leachate, etc. containing a high concentration of non-decomposable organic matter or a high concentration of salt.

The net flow of the water to be treated is a linear flow from the outside of the desalination device along the water supply flow path to the anion exchange membrane, a flow in a direction parallel to the anion exchange membrane, and a flow of the water from the anion exchange membrane to the anion exchange membrane. It may have a linear flow toward the outside of the desalination device along the treated water discharge path. As the treated water has a net flow in a certain direction, the separation efficiency of contaminants, including chlorine ions, in the treated water can be further increased.

The pollutants consist of chlorine ions (Cl ^- ), ammonium ions (NH ₄ ⁺ ), sulfate (SO ₄ ^2- ), nitrate (NO ₃ ^- ), nitrite (NO ₂ ^- ), and phosphate (PO ₄ ^3- ). It may contain ionic pollutants and dissolved organic pollutants including at least one selected from the group. In particular, cations and dissolved organic contaminants such as ammonium ions in treated water may be dispersed or diffused through the anion exchange membrane by the donnan effect.

The chlorine ions may be classified and discharged at a high concentration by the desalting device, and after the chlorine ions that have passed through the ion exchange membrane are converted to a chlorine-based oxidizing agent at the anode of the electrolysis unit, the chlorine-based oxidizing agent may be converted to other substances except chlorine ions. Contaminants may be removed by oxidation and decomposition. The chlorine-based oxidizing agent may be converted back into chlorine ions after an oxidation decomposition reaction and discharged from the desalination device.

The anion exchange membrane included in the electrolysis unit serves to separate ions and selectively adsorb them to the electrode, and may be porous. Ionic substances dissolved in wastewater can be separated using the electric field formed in the anion exchange membrane by direct current power. The anion exchange membrane may include a cationic functional group on the surface of the skin layer, and thus an anionic material capable of ionic bonding with the fixed cationic functional group may exhibit selective permeability.

The anion exchange membrane is prepared by coating a woven or non-woven fabric as a support with an ion exchange solution prepared by dissolving a polymer resin having a cationic functional group in an organic solvent and then drying it to produce a skin layer, or by coating the woven or non-woven fabric as a support with an ion exchange solution prepared by dissolving a polymer resin having a cationic functional group in an organic solvent and then drying it. The skin layer can be manufactured by grafting polymer resin.

The woven fabric or non-woven fabric is a support coated or impregnated with an ion exchange solution, and includes polyamide series, polyethylene series, polypropylene series, cellulose series, acrylic series, It may be formed of at least one polymer selected from the group consisting of polyvinyl chloride (PVC), polyvinyl alcohol (PVA), polyester series, and natural fibers.

The organic solvent may be at least one selected from dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone acetone, chloroform, dichloromethane, trichlorethylene, ethanol, methanol, n-hexane, etc.

The cationic functional group may include at least one positively charged functional group selected from the group consisting of -NH ₃ ⁺ , -NRH ₂ ⁺ , -NR ₂ H ⁺ , -NR ₃ ⁺ , -PR ₃ ⁺ and -SR ₂ ⁺ there is.

The anode is made of diamond (BDD) doped with iridium (Ir), ruthenium (Ru), tin (Sn), titanium (Ti), molybdenum (Mo), tantalum (Ta), zirconium (Zr), and boron (B). It may contain at least one metal or alloy selected from the group consisting of, or an oxide thereof.

The cathode may have a high reaction potential, and the anode may have a low reaction potential. The cathode may be characterized as being relatively low in reactivity and difficult to be oxidized due to its high reaction potential, and the anode may be characterized as having relatively high reactivity and being easily oxidized due to its low reaction potential. Accordingly, when voltage is applied to the electrolysis unit, a reduction reaction may occur at the cathode and an oxidation reaction may occur at the anode.

Chlorine ions present in the space between the anode and the anion exchange membrane may be converted to a chlorine-based oxidizing agent on the anode surface due to an electrochemical reaction with the anode. At this time, the electrical neutrality of the space between the cathode and the anion exchange membrane and the space between the anode and the anion exchange membrane is temporarily broken, and the anions existing in the space between the cathode and the anion exchange membrane are transferred to the anode through the anion exchange membrane. It can diffuse and move into the space between the anion exchange membrane and the anion exchange membrane. By placing an anion exchange membrane between the anode and the cathode to allow contaminants including chlorine ions to move, desalination and production of a chlorine-based oxidizing agent can be performed simultaneously.

Meanwhile, after the chlorine ions are converted to the chlorine-based oxidizing agent at the anode, the chlorine-based oxidizing agent again removes contaminants that have moved through the anion exchange membrane, such as ammonium ions (NH ₄ ⁺ ), sulfate (SO ₄ ^2- ), and nitrate. (NO ₃ ^- ), nitrite (NO ₂ ^- ), phosphate (PO ₄ ^3- ), etc. can be oxidized and decomposed and then converted back to chlorine ions. Accordingly, not only can it prevent contamination of the anion exchange membrane due to the backflow of the contaminants and oxidative decomposition of the cationic functional group contained in the anion exchange membrane due to the backflow of the chlorine-based oxidant, but also separate chlorine ions in the wastewater with high efficiency. can do.

The desalination device according to the present invention not only has an electrolysis unit that separates salts contained in wastewater, but also has a treated water supply passage, a treated water discharge passage, a washing water supply passage, and It may include a washing water discharge path.

The treated water supply flow path may be located on the cathode side to supply treated water from the outside of the desalination device to the anion exchange membrane. In addition, the treated water discharge flow path may be located on the cathode side so that the contaminants pass through the anion exchange membrane and are transferred to the anode side to discharge the removed treated water to the outside of the desalination device.

Specifically, the treated water supply flow path and the treated water discharge flow path are in contact with a diaphragm in between, and the opposite sides of the inlet of the treated water supply flow path and the outlet of the treated water discharge flow path are both blocked by an anion exchange membrane. . Therefore, the treated water flowing in along the treated water supply passage passes the cathode and moves to the anion exchange membrane, then the contaminants in the treated water are separated through the anion exchange membrane, and the treated water from which the contaminants have been separated is again The treated water can be discharged through the discharge channel.

As shown in FIG. 1, the treated water has a net flow in a certain direction between the cathode and the anion exchange membrane due to the treated water supply flow path and the treated water discharge flow path located on the cathode side, that is, the treated water has a net flow in a certain direction between the cathode and the anion exchange membrane. The treated water flowing into the water supply passage flows to the anion exchange membrane, and when the treated water reaches the anion exchange membrane, it may bend and flow in the direction of the treated water discharge passage. At this time, contaminants in the water to be treated, such as chlorine ions, ammonium ions, and nitrate ions, can selectively move to the anode side on the surface of the anion exchange membrane.

Meanwhile, the washing water supply passage may be located on the anode side to supply washing water from the outside of the desalination device to the anion exchange membrane. Additionally, the washing water discharge passage may be located on the anode side to discharge the washing water containing the contaminants transferred from the cathode side through the anion exchange membrane to the outside of the desalination device.

Specifically, the washing water supply flow path and the washing water discharge flow path are in contact with a diaphragm in between, and the opposite sides of the inlet of the washing water supply flow path and the outlet of the washing water discharge flow path are both blocked by an anion exchange membrane. Therefore, the washing water flowing in along the washing water supply flow path may pass through the anode, move to the anion exchange membrane, and then bend and flow in the direction of the washing water discharge flow path.

In this process, chlorine ions in the washing water are oxidized while passing through the anode and converted to a chlorine-based oxidizing agent, and the converted chlorine-based oxidizing agent moves along the forward flow direction of the washing water and removes contaminants from the treated water that have moved through the anion exchange membrane. After oxidation and decomposition, it is reconverted into chlorine ions, and the washing water containing the reconverted chlorine ions can be discharged through the washing water discharge passage.

The washing water may be supplied by treating the treated water from a wastewater treatment facility. Alternatively, the washing water may be supplied from external groundwater. That is, treated water or groundwater from which a significant portion of the contaminants in the treated water have been removed may be supplied to the anode as washing water. As the supplied washing water passes through the washing water supply flow path and the washing water discharge flow path, it has a net flow in a certain direction between the anode and the anion exchange membrane, and residual contaminants in the washing water are removed through an electrochemical reaction at the anode. In addition, contaminants remaining on the anion exchange membrane can be washed. Accordingly, the concentration gradient of ionic contaminants on the surface of the anion exchange membrane can be maintained to a maximum, thereby enabling stable and efficient separation of chlorine ions.

Chlorine ions contained in the ionic contaminants from the treated water and chlorine ions contained in the ionic contaminants from the washing water that moved to the anode side through the anion exchange membrane are chlorine (Cl ₂ ) and chlorous acid (HClO) on the anode side. ₂ ), is converted into at least one chlorine-based oxidizing material selected from the group consisting of hypochlorous acid (HClO) and hypochlorite ion (OCl ^- ), and the converted chlorine-based oxidizing material removes contaminants from the treated water or washed water. It can be oxidized and decomposed.

The chlorine-based oxidant material converted at the anode side can be reconverted back to chlorine ions after oxidizing and decomposing the ionic contaminants, and the converted chlorine-based oxidizing material moves along the forward flow direction of the washing water, resulting in the It can prevent oxidation of the anode electrode by chlorine-based oxidizing agents and oxidative decomposition of the cationic functional group contained in the anion exchange membrane.

The washing water may have a laminar flow with a Reynolds number of 2000 or less. Reynolds number may be defined as Equation 1 below.

[Equation 1]

(Re: Reynolds number, u: flow rate, d: pipe diameter, μ: dynamic viscosity coefficient of fluid)

If the Reynolds number of the washing water exceeds 2000, that is, in the case of turbulent flow, the washing water cannot have a constant flow direction and is irregularly mixed, so the chlorine-based oxidizing agent converted at the anode side spreads through the entire fluid by dispersion or diffusion. As a result, contamination of the anion exchange membrane may become more severe, and the cationic functional group contained in the anion exchange membrane may be oxidized and decomposed, thereby losing the ability of the anion exchange membrane to selectively separate chlorine ions.

Additionally, the water to be treated may be a laminar flow with a Reynolds number of 2000 or less. Like the washing water, the treated water also has a laminar flow, which results in continuous and constant contact of the treated water in the direction of the anion exchange membrane, resulting in the separation efficiency of contaminants, including chlorine ions, contained in the treated water through the anion exchange membrane. can be further increased.

In the case of the desalination device according to the present invention, since the pH rises on the cathode side and the pH decreases on the anode side continuously occurs, a process of adjusting the pH of the water to be treated and the washing water to near neutral may be necessary.

Specifically, on the cathode side where treated water is supplied, a water reduction reaction occurs as shown in Equation 2 below, and hydroxide ions (OH ^- ) are continuously generated, so the pH may increase to 12 or more.

[Equation 2]

2H ₂ O + 2e ^- → H ₂ + 2OH ^-

Meanwhile, on the anode side, where ionic contaminants including chlorine ions are separated and moved, the pH may decrease to 2 or more as hydrogen ions (H ⁺ ) are continuously generated by the continuous electrolysis reaction of water as shown in Equation 3 below. there is.

[Equation 3]

2H ₂ O → O ₂ + 4H ⁺ + 4e ^-

Accordingly, the pH of the treated water and the washing water may each independently be 5 to 10, preferably pH 6 to 9, and more preferably pH 7 to 8. When the pH of the water to be treated and the washing water exceeds the upper limit of the numerical range, the cationic functional group included in the anion exchange membrane excessively forms ionic bonds with hydroxide ions or the functional group is replaced by hydroxide ions, thereby preventing the ion exchange function. There may be a problem of loss of ion exchange membrane, and if it falls below the lower limit of the above numerical range, the functional groups distributed in the anion exchange membrane are oxidized and decomposed by hydrogen ions and separated from the polymer support, resulting in a serious deterioration in the ion exchange performance of the ion exchange membrane. You can.

As shown in FIG. 1, the desalination device according to the present invention has a repeating unit including the treated water supply passage and a treated water discharge passage and a repeating unit including the washing water supply passage and the washing water discharge passage between the anion exchange membrane. There may be a plurality of them arranged opposite to each other. In this way, the efficiency of separating chlorine ions and removing pollutants in wastewater can be further increased by arranging a plurality of repeating units including supply and discharge passages for treated water and repeating units including supply and discharge passages for washing water.

In addition, the desalination device according to the present invention may have a plurality of repeating units including a cathode and an anode disposed at the rear end of the electrolysis unit to perform additional electrolysis on the wash water discharged from the wash water discharge passage. Accordingly, by continuously using the separated chlorine ions, the formation of a chlorine-based oxidizing agent and the resulting oxidative decomposition of contaminants can be continuously performed, thereby maximizing the performance of desalination and decomposition of contaminants.

The concentration of chlorine ions in the discharged treated water may be reduced by 80% or more, preferably 85% or more, and more preferably 90% or more compared to the chlorine ion concentration in the supplied treated water. In addition, the chemical oxygen demand (COD) in the wash water discharged from the wash water discharge unit may be reduced by more than 75%, preferably by more than 80%, and more preferably by more than 82% compared to the chemical oxygen demand in the supplied wash water. .

The concentration of ammonium ions (NH ₄ ⁺ ) in the wash water passing through the electrolysis unit and discharged from the wash water discharge unit may be reduced by more than 94%, preferably by more than 95%, compared to the concentration of ammonium ions in the supplied wash water. .

In order to achieve the reduction rate of chlorine ion concentration in treated water, chemical oxygen demand and ammonium ion concentration in washing water as described above, the desalination device according to the present invention includes 10 to 30 mA/cm2, preferably 15 to 30 mA/cm2, More preferably, a current density of 20 to 25 mA/cm2 or more may be applied.

According to a desalination method according to another embodiment of the present invention, it is a desalination method for removing contaminants in water to be treated, wherein the water to be treated is passed through a cathode of an electrolysis unit through a water supply channel to an anion exchange membrane. A supply step of supplying treated water in the direction of; A contaminant transfer step of removing contaminants in the treated water by passing them through the anion exchange membrane and transferring them to the anode side; A discharge step of discharging the treated water from which the contaminants have been removed from the anion exchange membrane, through the cathode, and discharging the treated water to the outside through a treated water discharge passage; A washing water supply step of supplying washing water through a washing water supply passage toward the anion exchange membrane; and a discharge step of discharging the washing water containing the contaminants transferred through the anion exchange membrane through the anode to the outside through the washing water discharge passage, wherein the net flow of the washing water is in the washing water supply passage. A desalting method having a linear flow along the longitudinal direction is provided.

Among the contents described about the desalination device of the present invention, contents that overlap with the desalination method of the present invention may be equally applied even if the detailed description is omitted.

The net flow of the washing water is a linear flow from the outside of the desalination device in the direction of the anion exchange membrane along the washing water supply passage, a flow in a direction parallel to the anion exchange membrane, and a flow in a direction parallel to the anion exchange membrane, and along the washing water discharge passage from the anion exchange membrane. It may have a linear flow toward the outside of the desalination device.

In addition, the net flow of the water to be treated is a linear flow from the outside of the desalination device along the water supply flow path to the anion exchange membrane, a flow in a direction parallel to the anion exchange membrane, and a flow from the anion exchange membrane. It may have a linear flow toward the outside of the desalination device along the discharge flow path of the treated water.

The washing water may be a laminar flow with a Reynolds number of 2000 or less. If the Reynolds number of the washing water exceeds 2000, that is, in the case of turbulent flow, the washing water cannot have a constant flow direction and is irregularly mixed, so the chlorine-based oxidizing agent converted at the anode side spreads through the entire fluid by dispersion or diffusion. As a result, contamination of the anion exchange membrane may become more severe, and the cationic functional group contained in the anion exchange membrane may be oxidized and decomposed, thereby losing the ability of the anion exchange membrane to selectively separate chlorine ions.

Additionally, the water to be treated may be a laminar flow with a Reynolds number of 2000 or less. Like the washing water, the treated water also has a laminar flow, which results in continuous and constant contact of the treated water in the direction of the anion exchange membrane, resulting in the separation efficiency of contaminants, including chlorine ions, contained in the treated water through the anion exchange membrane. can be further increased.

The pollutants consist of chlorine ions (Cl ^- ), ammonium ions (NH ₄ ⁺ ), sulfate (SO ₄ ^2- ), nitrate (NO ₃ ^- ), nitrite (NO ₂ ^- ), and phosphate (PO ₄ ^3- ). It may contain ionic pollutants and dissolved organic pollutants including at least one selected from the group. In particular, cations and dissolved organic contaminants such as ammonium ions in treated water may be dispersed or diffused through the anion exchange membrane by the donnan effect.

The contaminants may be included in both the treated water and the washing water, and may be contained in the treated water at a relatively higher concentration than the washing water.

In addition, in the desalination method, chlorine ions contained in contaminants derived from the treated water or washing water are converted to chlorine (Cl ₂ ), chlorous acid (HClO ₂ ), hypochlorous acid (HClO), and hypochlorite ions (OCl ^- ) Converting to at least one substance selected from the group consisting of; and allowing the converted material to oxidize and decompose contaminants derived from the treated water or washed water.

In the oxidative decomposition step, the converted material may be converted back into chlorine ions after oxidizing and decomposing the contaminants.

As the treated water and the washing water maintain a net flow in a certain direction, the contaminants contained in the treated water and the washing water move consistently in the anode direction, resulting in chlorine ions in the treated water and the washing water passing through the anion exchange membrane. After the chlorine ions are converted to chlorine-based oxidants such as chlorine, chlorous acid, hypochlorous acid, and hypochlorite ions at the anode, contaminants other than chlorine ions contained in the treated water and washing water are oxidized and decomposed and converted back to chlorine ions. As it is discharged, contamination of the anion exchange membrane and oxidation of the electrode due to backflow of the chlorine-based oxidizing agent can be prevented, and oxidative decomposition of the cationic functional group contained in the anion exchange membrane can be prevented. In addition, since the surface of the anion exchange membrane is continuously cleaned, the concentration gradient of contaminants on the surface of the anion exchange membrane can be maintained to a maximum, thereby enabling stable and efficient separation of chlorine ions.

Hereinafter, the present invention will be described in more detail through examples. However, these examples are only intended to aid understanding of the present invention, and the scope of the present invention is not limited to these examples in any way.

<Example 1> Confirmation of desalination effect using a desalination device using laminar flow

As shown in Figure 1, the electrolysis unit of the desalination device consisted of a Ti mesh cathode, an anion exchange membrane, and an IrO ₂ /Ti mesh anode, and an anion exchange nonwoven fabric with micropores of 1㎛ was used as the anion exchange membrane. The cathode was located 10 cm away from the anion exchange membrane, and the anode was located 15 cm away. The size of the cathode and anode was 7 cm x 7 cm.

A treated water supply channel and a treated water discharge channel were installed on the cathode side, and a washing water supply channel and a washing water discharge channel were installed on the anode side. The treated water supply channel and the treated water discharge channel consisted of a cylindrical pipe with a diameter of 10 cm. Five repeating units consisting of a repeating unit and a washing water supply channel and a washing water discharge channel were installed opposite each other along the anion exchange membrane.

In order to supply the treated water and washing water in the direction of the anion exchange membrane while maintaining a laminar flow, pumps were installed in the treated water supply channel and the washing water supply channel, respectively.

In addition, in order to continuously produce a chlorine-based oxidant, oxidize and decompose ionic organic pollutants including ammonium ions, and continuously use the separated chlorine ions, the washing water passes through the electrolysis unit multiple times after passing through the cathode. Five pairs of cathodes and anodes were installed every 10 cm to undergo an electrochemical reaction. The distance between the additionally installed anode and cathode pairs was 1 cm. An anion exchange membrane was installed to fit the diameters of the five influent and wash water pipes.

The overall size of the cathode side of the desalination device was 150 cm wide, 10 cm wide, and 100 cm high, and the overall size of the anode side was 150 cm wide, 10 cm wide, and 100 cm high.

Wastewater with pH 8.0, COD 8,310 ppm, ammonia 2,450 ppm, and salinity 51,200 ppm (5.12%) was used as treated water, and the wash water was treated at a water treatment facility with pH 8.3, COD 840 ppm, ammonia 880 ppm, and salinity 5,300 ppm. Runoff water discharged from was used.

The Reynolds number was maintained below 2000 by supplying treated water and washing water at a flow rate of 50 L/h to the treated water supply channel and the washing water supply channel through the pump.

Meanwhile, the pH was adjusted using pHI/C using 0.1N sulfuric acid and 0.1N sodium hydroxide so that the pH could be operated between 5 and 10.

A desalting reaction was performed by applying a current density of 10, 15, 20, 25, and 30 mA/cm2 to the desalting device, respectively. In order to confirm the cleaning effect and optimization of the concentration gradient on the surface of the anion exchange membrane, the desalination device was operated continuously for 24 hours, and the concentrations of pH, COD, ammonia, and chlorine ions before and after passing through the anion exchange membrane were measured and compared, and the anion The flux passing through the exchange membrane surface was calculated and the degree of cleaning of the anion exchange membrane surface immediately after ion exchange was observed, and are shown in Tables 1 to 4 below. Specifically, Table 1 compares the concentration before and after passing through the anion exchange membrane, Table 2 shows the effluent concentration of the treated water and the inflow of the treated water, the difference in the effluent concentration (concentration exchanged through the anion exchange membrane), and Table 3 shows the inflow and inflow of the washing water. Final effluent concentration, Table 4 shows a comparison of flux according to the effect of washing the ion exchange membrane with washing water at 25 mA/cm2 after 24 hours.

current density
(mA/㎠) 10 15 20 25 30 Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) pH 8.0 8.1 8.0 8.1 8.0 8.1 8.0 8.1 8.1 8.1 COD
(mg/L) 8300 1320 8310 1450 8210 1360 8310 1420 8350 1330 ^NH ₄₊
(mg/L) 2400 580 2410 675 2410 670 2450 680 2470 690 Cl ^-
(mg/L) 51200 23300 51150 24500 51200 25750 51200 27420 51200 26950

In Table 1, the concentration before passing through the anion exchange membrane is the concentration of the treated water, and the concentration after passing through the anion exchange membrane is the concentration of the treated water passing through the anion exchange membrane and mixed with the washing water.

current density
(mA/㎠) 10 15 20 25 30 Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow pH 8.0 - 8.0 - 8.0 - 8.0 - 8.1 - COD
(mg/L) 6500 1810 6510 1980 4620 1890 6520 1790 6510 1790 ^NH ₄₊
(mg/L) 2150 300 1980 470 2000 450 1940 510 2010 510 Cl ^-
(mg/L) 9820 41380 7430 43770 2860 45840 2500 48700 2570 48630

In Table 2, the effluent concentration of the treated water is the concentration that flows out from the influent treated water through the anion exchange membrane, and is the residual concentration remaining after ions are exchanged from the influent treated water through the anion exchange membrane.

current density
(mA/㎠) 10 15 20 25 30 Washing water inlet concentration Wash water final effluent concentration Washing water inlet concentration Wash water final effluent concentration Washing water inlet concentration Wash water final effluent concentration Washing water inlet concentration Wash water final effluent concentration Washing water inlet concentration Wash water final effluent concentration pH 8.3 7.2 8.3 7.3 8.3 7.2 8.3 6.8 8.3 6.9 COD
(mg/L) 840 185 845 150 840 145 840 120 860 150 ^NH ₄₊
(mg/L) 890 40 900 45 880 42 890 32 880 48 Cl ^-
(mg/L) 5300 22000 5100 21800 5250 26300 5150 27100 5200 27200

In Table 3, the effluent concentration of the washing water is the residual concentration remaining after passing through the anion exchange membrane and oxidative decomposition through five repeating units consisting of an anode and a cathode pair.

Theoretical value after passing through anion exchange membrane Actual value after passing through anion exchange membrane Difference between theoretical and actual values compared to theoretical value (%) COD flux (kg/㎡·s) 0.16 0.12 25% NH ₄ ⁺ flux (kg/㎡·s) 0.05 0.04 20% Cl ^- Flux (kg/㎡·s) 4.31 4.27 0.9%

In Table 4 above, the theoretical positive value after passing through the anion exchange membrane is the flux value on the surface of the ion exchange membrane of ionic contaminants that appear after passing through the anion exchange membrane immediately after the water to be treated is ion exchanged.

The actual measured value after passing through the anion exchange membrane is the flux value on the surface of the anion exchange membrane calculated by measuring the concentration of ionic contaminants ion exchanged on the surface of the anion exchange membrane when the anion exchange membrane was washed with washing water.

If the theoretical and actual values of the anion exchange membrane flux are similar, the anion exchange membrane surface is washed after ion exchange and the concentration of contaminants on the anion exchange membrane surface decreases, resulting in the ion exchange rate of ionic contaminants due to the electric gradient and concentration gradient. This indicates that ion exchange continues close to the theoretical value without being reduced.

<Comparative Example 1> Confirmation of desalination effect using a desalination device using turbulent flow

In order to compare the desalination effect with the desalination device using laminar flow according to Example 1, as shown in FIG. 2, a reaction tank of the same volume as Example 1 was manufactured and a desalination experiment was performed using a turbulent completely mixed flow. did.

The electrolysis unit of the desalination device consisted of a Ti mesh cathode, an anion exchange membrane, and an IrO ₂ /Ti mesh anode, and an anion exchange nonwoven fabric with micropores of 1㎛ was used as an anion exchange membrane. The size of the reaction tank on the cathode and anode sides was manufactured to be the same around the anion exchange membrane, and the cathode and anode were positioned 10 cm and 15 cm away from the ion exchange membrane, respectively, as in Example 1.

A treated water supply flow path and a treated water discharge flow path were installed on the cathode side, and an inflow water supply flow path and an inflow water discharge flow path were installed on the anode side. In order to supply the treated water and influent water, pumps were installed in the treated water supply flow path and the influent water supply flow path, respectively.

The overall size of the cathode side was 150 cm wide, 10 cm wide, and 100 cm high, and the overall size of the anode side was 150 cm wide, 10 cm wide, and 100 cm high. The size of the anion exchange membrane was 10 cm wide and 100 cm long as in Example 1, and the size of the cathode and anode was 7 cm wide and 7 cm long, and 10 electrodes were connected vertically in series.

In order to compare with Example 1, treated water at a flow rate of 50 L/h was introduced to the cathode side and influent water at a flow rate of 50 L/h to the anode side, and the treated water had pH 8.1, COD 8,420 ppm, ammonia 2,150 ppm, and salinity 50,800 ppm. (5.08%) wastewater was used, and the effluent discharged from the treated water treatment facility was used as the influent supplied to the anode, and the pH was 8.2, COD 1020 ppm, ammonia 1250 ppm, and salinity 7,100 ppm. The cathode and anode side reaction tanks were thoroughly mixed with a mixer.

The pH was adjusted using pHI/C using 0.1N sulfuric acid and 0.1N sodium hydroxide.

The current density of the desalination device was applied at 10, 15, 20, 25, and 30 mA/cm2 as in Example 1, and after continuous operation for 24 hours to confirm the concentration gradient on the surface of the anion exchange membrane, anions were removed near the surface of the anion exchange membrane. The concentrations of pH, COD, ammonia, and salt before and after passing through the exchange membrane were measured and compared, the flux passing through the anion exchange membrane surface was calculated, and the degree of cleaning of the anion exchange membrane surface immediately after ion exchange was observed and shown in Tables 5 to 8 below. It was. Specifically, Table 5 compares the concentration before and after passing through the anion exchange membrane, Table 6 shows the difference between the effluent concentration of the treated water, the inflow of the treated water, and the effluent concentration (concentration exchanged through the anion exchange membrane), and Table 7 shows the influent of the anode side. Inlet and final outlet concentrations, Table 8 shows a comparison of flux according to the effect of washing the ion exchange membrane with washing water at 25 mA/cm2 after 24 hours.

current density
(mA/㎠) 10 15 20 25 30 Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) Before passing through anion exchange membrane (water to be treated) After passing through anion exchange membrane (treated water + washing water) pH 8.1 3.0 8.1 2.8 8.1 2.1 8.1 2.2. 8.1 2.0 COD
(mg/L) 8310 1090 8340 1010 8320 1080 8420 1040 8300 1080 ^NH ₄₊
(mg/L) 2180 1320 2240 1310 2150 1280 2150 1340 2400 1320 Cl ^-
(mg/L) 50100 7400 50100 8100 50400 7800 50800 8950 50800 8240

current density
(mA/㎠) 10 15 20 25 30 Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow Treatment water effluent concentration Differences in concentration of treated water inflow and outflow pH 8.1 - 8.1 - 8.1 - 8.1 - 8.1 - COD
(mg/L) 8120 190 8100 240 8240 80 8320 100 8250 50 ^NH ₄₊
(mg/L) 2040 140 2100 140 2050 100 2040 110 2310 90 Cl ^-
(mg/L) 49900 200 48900 1200 50100 300 50700 100 50720 80

current density
(mA/㎠) 10 15 20 25 30 Influent influent concentration Influent final effluent concentration Influent influent concentration Influent final effluent concentration Influent influent concentration Influent final effluent concentration Influent influent concentration Influent final effluent concentration Influent influent concentration Influent final effluent concentration pH 8.2 3.0 8.2 2.8 8.1 2.1 8.1 2.2 8.1 2.0 COD
(mg/L) 1020 1090 1030 1010 1030 1080 1020 1040 1030 1080 ^NH ₄₊
(mg/L) 1240 1320 1210 1310 1200 1280 1320 1340 1210 1320 Cl ^-
(mg/L) 7000 7400 7200 8100 7100 7800 7150 8950 7150 8240

Theoretical value after passing through anion exchange membrane Actual value after passing through anion exchange membrane Difference between theoretical and actual values compared to theoretical value (%) COD flux (kg/㎡·s) 0.008 0 100% NH ₄ ⁺ flux (kg/㎡·s) 0.01 0 100% Cl ^- Flux (kg/㎡·s) 0.008 0 100%

<Interpretation of results>

1. pH

Referring to FIG. 3, when using the desalination device applying laminar flow according to Example 1, the chlorine-based oxidant generated on the anode surface is completely separated by the treated water and washing water flowing in a certain direction, and the pH is maintained throughout the entire current density. After flowing in at a pH of 8.0 to 8.1, the final effluent of the washing water was discharged at a pH of 6.8 to 7.3 and operated stably (e.g., at a current density of 25 mA/cm2, the treated water before passing through the anion exchange membrane in Table 1 had a pH of 8.0. After washing, the final effluent of the washing water in Table 3 discharges at pH 6.8).

When using the turbulent fully mixed flow desalination device according to Comparative Example 1, as the chlorine-based oxidant generated on the anode surface is mixed into the entire fluid, the pH flows in at 8.1 and then flows out at pH 2.2 to 3.0 across the entire current density. After completely consuming the 0.1N NaOH connected to the pH I/C, the pH continued to lower (e.g., at a current density of 25 mA/cm2, the pH of the treated water before passing through the anion exchange membrane in Table 5 was 8.1, and then in Table 7 The anode-side influent and final effluent discharged at pH 2.2). In other words, the ion exchange functional group of the anion exchange membrane is oxidized and decomposed, and the ion exchange function is completely lost.

2. Separation of chlorine ions from treated water

When using the desalination device applying laminar flow according to Example 1, chlorine ions were reduced to 80.8%, 85.5%, 94.4%, 95.1%, and 94.9%, respectively, at current densities of 10, 15, 20, 25, and 30 mA/cm2. Separated (e.g., at a current density of 25 mA/cm2, 51200 ppm of chlorine ions flow in from the inflow concentration of treated water before passing through the anion exchange membrane in Table 1, and 2500 ppm flows out from the effluent concentration of treated water in Table 2. Bar, 95.1% of chlorine ions can be separated). The results are shown in Figure 4.

On the other hand, when using the turbulent fully mixed flow desalination device according to Comparative Example 1, chlorine ions were 0.4%, 2.4%, 0.6%, and 0.2%, respectively, at current densities of 10, 15, 20, 25, and 30 mA/cm2. , was separated by 0.16% (e.g., at a current density of 25 mA/㎠, 50800 ppm of chlorine ions were introduced at the inflow concentration of treated water before passing through the anion exchange membrane in Table 5, and 50700 ppm at the effluent concentration of treated water in Table 6). As ppm is leaked, 0.2% of chlorine ions can be separated).

3. Final discharge of organic pollutants from the anode side (COD)

Referring to Figure 5, when using the desalination device applying laminar flow according to Example 1, organic pollutants were reduced by 78%, 82.2%, and 82.7%, respectively, at current densities of 10, 15, 20, 25, and 30 mA/cm2. , 85.7% and 82.6% were removed by a chlorine-based oxidizing agent (e.g., in Table 3, at a current density of 25 mA/cm2, the COD of the inflow washing water was 840 ppm, and the COD of the final effluent of the anode-side washing water was 120 ppm, which is 85.7%. organic matter is removed by a chlorine-based oxidizing agent).

When using the turbulent fully mixed flow desalination device according to Comparative Example 1, only 1.94% of organic contaminants were removed at a current density of 15 mA/cm2, and at current densities of 10, 20, 25, and 30 mA/cm2, respectively. Organic pollutants were not removed, but rather increased (e.g., at a current density of 25 mA/cm2 in Table 7, the COD of the anode-side influent was 1020ppm, while the COD of the final effluent from the anode was 1040ppm, indicating that organic pollutants were not removed). This is presumed to be the result of no chlorine-based oxidizing agent being generated.

4. Final outflow of ammonium ions from the anode side

Referring to Figure 6, when using the desalination device applying laminar flow according to Example 1, ammonium ions in the wash water were 95.5%, 95%, and 95.2%, respectively, at current densities of 10, 15, 20, 25, and 30 mA/cm2. %, 96.4%, and 94.5% were removed (e.g., at a current density of 25 mA/cm2 in Table 3, NH ₄ ⁺ 890 ppm was inflow, and 32 ppm was discharged from the final effluent on the anode side, so 96.4% of NH ₄ ⁺ was chlorine-based removed by oxidizing agents).

When using the turbulent fully mixed flow desalination device according to Comparative Example 1, ammonium ions in the wash water were not removed but rather increased at current densities of 10, 15, 20, 25, and 30 mA/cm2 (e.g., in Table 7 At a current density of 25 mA/㎠, the COD of the influent water on the anode side was 1320ppm, and 1340ppm was discharged from the final effluent water on the anode side, and NH ₄ ⁺ not removed), it is presumed to be the result of the chlorine-based oxidizing agent not being generated.

5. Comparison of the difference between flux theoretical and actual values

When using the desalination device applying laminar flow according to Example 1, the difference between the theoretical value and the actual measured value compared to the theoretical value of COD flux, NH ₄ ⁺ flux, and Cl flux at a current density of 25 mA/cm2 is 25%, Even in continuous operation for 24 hours at 20% and 0.9%, the flux was close to the theoretical value due to the continuous cleaning effect of the anion exchange membrane surface.

On the other hand, when using the turbulent fully mixed flow desalination device according to Comparative Example 1, the difference between theoretical and actual values compared to the theoretical values of COD flux, NH ₄ ⁺ flux, and Cl flux at a current density of 25 mA/cm2 It was impossible to desalt in continuous operation for 24 hours at 100%, 100%, 100%.

Claims (21)

A desalting device for removing contaminants in treated water,
An electrolysis unit comprising a cathode, an anode and an anion exchange membrane;
a water supply channel located on the cathode side and supplying water to be treated from the outside of the desalination device toward the anion exchange membrane;
a treated water discharge channel located on the cathode side and discharging the treated water removed by passing the contaminants through the anion exchange membrane to the anode side to the outside of the desalination device;
a washing water supply channel located on the anode side and supplying washing water from the outside of the desalination device to the anion exchange membrane; and
a washing water discharge channel located on the anode side and discharging the washing water containing the contaminants transferred from the cathode side through the anion exchange membrane to the outside of the desalination device;
Including,
A net-flow of the washing water has a linear flow along the longitudinal direction of the washing water supply flow path. In claim 1,
The net flow of the washing water is a linear flow from the outside of the desalination device in the direction of the anion exchange membrane along the washing water supply passage, a flow in a direction parallel to the anion exchange membrane, and a flow in a direction parallel to the anion exchange membrane, and along the washing water discharge passage from the anion exchange membrane. A desalting device having a linear flow in a direction out of the desalting device. In claim 2,
A desalting device wherein the washing water has a laminar flow with a Reynolds number of 2000 or less. In claim 1,
The washing water is supplied by treating the water to be treated from a wastewater treatment facility. In claim 1,
The net flow of the water to be treated is a linear flow from the outside of the desalination device along the water supply flow path to the anion exchange membrane, a flow in a direction parallel to the anion exchange membrane, and a flow of the water from the anion exchange membrane to the anion exchange membrane. A desalination device having a linear flow toward the outside of the desalination device along the treated water discharge flow path. In claim 5,
A desalination device wherein the water to be treated has a laminar flow with a Reynolds number of 2000 or less. In claim 1,
The anode is made of diamond (BDD) doped with iridium (Ir), ruthenium (Ru), tin (Sn), titanium (Ti), molybdenum (Mo), tantalum (Ta), zirconium (Zr), and boron (B). A desalination device comprising at least one metal or alloy or an oxide thereof selected from the group consisting of. In claim 1,
Desalination, wherein a plurality of repeating units including the treated water supply flow path and the treated water discharge flow path and the washing water supply flow path and the washing water discharge flow path are arranged opposite to each other with the anion exchange membrane in between. Device. In claim 1,
A desalination device in which a plurality of repeating units including a cathode and an anode are disposed at a rear end of the electrolysis unit to perform additional electrolysis on the washing water discharged from the washing water discharge passage. In claim 1,
The anion exchange membrane includes a woven or non-woven support; and
A desalting device comprising a skin layer containing a polymer resin having a cationic functional group. In claim 1,
A desalination device in which the concentration of chlorine ions in the discharged treated water is reduced by more than 80% compared to the chlorine ion concentration in the supplied treated water. In claim 1,
A desalination device in which the chemical oxygen demand (COD) in the washing water discharged from the washing water discharge unit is reduced by more than 75% compared to the chemical oxygen demand in the supplied washing water. In claim 1,
A desalination device in which the concentration of ammonium ions (NH ₄ ⁺ ) in the wash water passing through the electrolysis unit and discharged from the wash water discharge unit is reduced by more than 94% compared to the concentration of ammonium ions in the supplied wash water. In claim 1,
A desalination device wherein the pH of the treated water and the washing water are each independently 5 to 10. As a desalting method for removing contaminants in treated water,
A supply step of supplying the water to be treated through a water supply channel to the anion exchange membrane through the cathode of the electrolysis unit;
A contaminant transfer step of removing contaminants in the treated water by passing them through the anion exchange membrane and transferring them to the anode side;
A discharge step of discharging the treated water from which the contaminants have been removed from the anion exchange membrane, through the cathode, and discharging the treated water to the outside through a treated water discharge passage;
A washing water supply step of supplying washing water through a washing water supply passage toward the anion exchange membrane; and
Discharging washing water containing the contaminants transferred through the anion exchange membrane through the anode and discharging the washing water to the outside through a washing water discharge passage;
Including,
A desalination method in which the net flow of the washing water has a linear flow along the longitudinal direction of the washing water supply flow path. In claim 15,
The net flow of the washing water is a linear flow from the outside of the desalination device in the direction of the anion exchange membrane along the washing water supply passage, a flow in a direction parallel to the anion exchange membrane, and a flow in a direction parallel to the anion exchange membrane, and along the washing water discharge passage from the anion exchange membrane. A method of desalting, having a linear flow in a direction outward of the desalting device. In claim 15,
A desalination method wherein the washing water has a laminar flow with a Reynolds number of 2000 or less. In claim 15,
The chlorine ions contained in the contaminants derived from the treated water or washing water are selected from the group consisting of chlorine (Cl ₂ ), chlorous acid (HClO ₂ ), hypochlorous acid (HClO), and hypochlorite ions (OCl ^- ) on the anode side. Converting to at least one substance that is; and
causing the converted material to oxidize and decompose contaminants derived from the treated water or washed water;
A desalting method further comprising: In claim 18,
A desalination method in which the converted material in the oxidative decomposition step is reconverted back to chlorine ions after oxidizing and decomposing the contaminants. In claim 15,
The net flow of the water to be treated is a linear flow from the outside of the desalination device along the water supply flow path to the anion exchange membrane, a flow in a direction parallel to the anion exchange membrane, and a flow of the water from the anion exchange membrane to the anion exchange membrane. A desalination method having a linear flow toward the outside of the desalination device along the treated water discharge flow path. In claim 20,
A desalination method wherein the treated water has a laminar flow with a Reynolds number of 2000 or less.