KR20090086157A - Method and apparatus for water treatment - Google Patents

Abstract

A water treatment method and a water treating device thereof are provided to prevent generation of sludge such as conventional biological treatment by reducing a contamination index of evaluation and cutting bonding of contaminating components. A water treatment method includes the following steps of: generating hydrochloric acid gas(2) from a cathode by flowing a current into water in which chlorine is dissolved; reducing a contamination index of evaluation by collecting the hydrochloric acid gas and flowing into water to be treated directly or indirectly; and reaching sodium hypochlorite generated by the hydrochloric acid gas to the water to be treated.

Description

Method and apparatus for water treatment

The present invention relates to a useful water treatment method and apparatus that is not biologically treated and produces little sludge.

Conventionally, various proposals have been made regarding the wastewater treatment technology (for example, Patent Document 1: Japanese Patent Application Laid-Open No. 2006-281194), and the following water treatment is performed in one liquid crystal manufacturing plant.

In other words, groundwater is sent to the liquid crystal manufacturing plant from the local pumping station to industrial water. More than half of these are supplied to the plant's air-treatment facilities to remove components such as silica, calcium, and magnesium. Ultrapure water is then sent to pure water production and supply facilities. Less than half of the water supplied to the plant is supplied to an air conditioning cooling tower to dissipate the heat generated by a device for cooling cold water by evaporation to the atmosphere, and the residue is filtered through activated carbon and diluted with pure water. Discharged into the river.

The ultrapure water is used for cleaning a glass substrate in a liquid crystal manufacturing process, for cleaning scrubber exhaust, a cooling water production apparatus, and the like. Drainage of ultrapure water is recovered to a wastewater collection facility and is circulated and reused between the pure water production and supply facilities.

It is an object of the present invention to provide a water treatment method and apparatus in which sludge (sludge) does not occur as in the prior art.

In order to solve the above problems, the present invention has been made the following technical features.

(1) In this water treatment method, a chlorine gas is generated from the anode side by flowing an electric current in a lamella membrane current application tank to generate chlorine gas from the anode side (chlorine gas generation step), and recovering the chlorine gas directly or indirectly. It is characterized in that it leads to the to-be-treated water, and reduces the pollution evaluation index (a pollution evaluation index reduction process).

The water treatment mechanism is provided with a diaphragm current application tank that generates a chlorine gas at the anode side by flowing an electric current in the water in which chlorine is dissolved, and recovers the chlorine gas to directly or indirectly the water to be treated to evaluate pollution. It is characterized by reducing the index.

Examples of the water in which chlorine is dissolved include water in which saline and sodium hypochlorite are dissolved. In this case, when a current flows into water (such as to-be-treated water) in which chlorine is dissolved in the diaphragm current application tank, the anode side may be an acidic component and generate chlorine gas. By recovering the chlorine gas directly or indirectly to the water to be treated, the oxidation evaluation index of the water to be treated can be reduced by its oxidation.

This water treatment method and apparatus recovers chlorine gas generated at the anode side of the diaphragm current application tank without opening it to the atmosphere and reaches the treated water, thereby chemically cutting the bonds of the contaminants to reduce the pollution evaluation index. Therefore, sludge (such as the dead sea of microorganism) like the case of biological treatment does not occur. In addition, negative ions, such as chlorine ions, in the water to be treated on the cathode side are electrically attracted to the anode side through the diaphragm to be separated and reduced (anion reduction action).

In this case, when the treated water after reduction of the pollution evaluation index is supplied to the cathode side of the diaphragm current applying tank, the residual chlorine concentration can be reduced in a basic atmosphere, and excess ions (chlorine ions, etc.) in the treated water can be reduced. When the membrane is separated and removed by a later step, the membrane is less likely to be damaged, and its life can be extended.

As the water to be treated, plant drainage, restaurant drainage, general household drainage, PCB and other contaminated soil drainage, paint shop and other VOC gas are replaced by water with a scrubber (scrubber). Pool water, bath water, and the like can be exemplified, and any water for which purification is required is included, and is not necessarily limited to water that is discarded. Circulating use, etc. shall also be included.

In addition, normal organic components (formaldehyde, etc.), hardly decomposable organic compounds such as benzene, toluene, dioxins, PCBs, contaminants eluted from the skin surface of the human body, and ammonia nitrogen and other inorganic substances as contaminants in the water to be treated. Ingredients can be exemplified. The diaphragm current applying tank can be electrolyzed by coexisting chlorides or hypochlorous acid such as salt. As said contamination evaluation index, COD (chemical oxygen demand), TOC, etc. can be illustrated.

(2) The recovered chlorine gas may extend directly to the water to be treated (direct treatment with chlorine gas). For example, the recovered chlorine gas can be blown into the water to be treated. Blown chlorine gas is directly decomposed to meet contaminants, or combined with water or hydroxyl ions in the water to be treated to form hypochlorous acid. You can.

(3) The hypochlorous acid and / or sodium hypochlorite produced by the recovered chlorine gas may be treated with water to be treated (indirect treatment with chlorine gas). For example, chlorine gas, water, or hydroxide ions can be used to produce water having oxidative capacity generated by hypochlorous acid and act on the treated water. In addition, the collected chlorine gas and sodium hydroxide may be combined to produce sodium hypochlorite, and the sodium hypochlorite may be brought to the treated water.

(4) The water to be treated may be electrolyzed to anodize and sent to the cathode side of the membrane current applying tank. With this arrangement, the anodized water can be directly anodized by electrolysis to reduce the pollution evaluation index, and residual chlorine generated in the water to be treated by anodic oxidation can be reduced on the cathode side of the diaphragm current applying tank. .

(5) If ions are separated from the water to be treated on the cathode side of the above-mentioned diaphragm current applying tank by the RO membrane or other separation membranes, they can be reused as industrial water, drinking water, or the like.

(6) The bromine may be dissolved during the electrolysis. With this arrangement, the functional area of the oxidizing ability of hypochlorous acid during electrolysis can be extended to a wide pH range by hypobromic acid. In other words, the oxidation capacity of hypochlorous acid is the maximum at pH 5.5, and it decreases toward both sides to the peak, but when bromine coexists, hypobromic acid is generated, raising the peak of the oxidation capacity from pH 5.5 to pH 8 and trapezoidal shape. Can be extended to

In other words, if bromine is coexisted such as sodium bromide, potassium bromide, hypobromic acid, or the like, the active region of the effective chlorine can be expanded from the neutral region to the alkaline region by the effective bromine.

(7) The water to be treated may be made by mixing water, a protonic amphiphilic solvent, an aprotic amphiphilic solvent, and a hydrophobic organic component.

In this way, even if the contaminated component is a hydrophobic organic component, which is difficult to dissolve in water, it can be used in water and purified. In other words, when the protic and aprotic solvents are used together as the amphiphilic solvent, the protonic amphiphilic solvent (IPA, etc.) coordinates the hydrophobic group to the hydrophobic organic component (benzene, etc.) and the protonic hydrophilic group (hydroxyl group, etc.) to the water side. In the aprotic amphiphilic solvent (DMSO, etc.), the hydrophobic group coordinates to the hydrophobic organic component (benzene, etc.), and the aprotic hydrophilic group (carbonyl oxygen, etc.) coordinates to the water side, and the hydrophilic group coordinated to the water side. Since it is not biased only to either protonic or aprotic, mutual affinity can be increased, thereby improving the compatibility of the hydrophobic organic component with water.

Specifically, when water and protonic amphiphilic solvents (IPA, etc.) are used only (not mixed with aprotic), hydrophobic organic components (benzene, etc.) are rarely used, and a considerable amount of solvent is required. Attempting to make the hydrophobic organic component (benzene, etc.) compatible with only an aprotic amphiphilic solvent (DMSO, etc.) but rarely compatible, required a considerable amount of solvents. By using aprotic ones together, hydrophobic organic components can be made compatible even when the amount of these solvents is relatively small. The amphiphilic solvent has one side as an organic component to be purified, in addition to the significance of introducing into hydrophobic organic components by electrolysis. If the amount can be reduced, the final degree of purification (for example, the amount of COD) is improved. Can contribute to

In addition, the hydrophobic organic components (benzene, etc.) associated with each other due to intermolecular forces are electrolyzed in a state where they are compatible with amphiphilic solvents (IPA, DMSO, etc.) and water, and the molecules of the associated hydrophobic organic components The original aggregation is separated and separated, and the molecules of the hydrophobic organic component are oxidized directly from the surroundings and the bonds in the molecules are broken. Amphiphilic solvents act as an adjuvant interposed between water and hydrophobic organic components at the time of electrolysis, and hydrophobic organic components can effectively effect oxidation.

Here, as the amphiphilic solvent, protonic IPA (isopropyl alcohol), ethanol, methanol, MEA (monoethanolamine), aprotic DMSO (dimethyl sulfoxide), DMAc (dimethylacetamide), etc. can be exemplified. Protons and aprotons can be used in combination suitably.

Benzene, toluene, xylene, styrene, etc. can be illustrated as said hydrophobic organic component. In addition, dioxins, in which soil contamination is a problem, hardly decomposable organic compounds such as PCBs, and contaminants eluted from the skin surface of the human body may be exemplified. The contaminated soil can be washed with water, a protonic amphiphilic solvent and an aprotic amphiphilic solvent, and the washing water can be purified as described above.

The present invention has the following effects with the configuration as described above.

By chemically cutting the bonds of the contaminants in the water to be treated, the contamination evaluation index is reduced, so that a sludge (such as the dead sea of microorganisms) similar to the conventional biological treatment can be provided.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to drawings.

As shown in Fig. 1, in this embodiment, the water to be treated (organic wastewater containing N, N-dimethylacetamide and monoethanolamine) is stored in the raw water tank 1 and pumped in the raw water tank 1 P is sent to the first reactor 2 (flow rate 140cc / min). The saline solution 3 is joined by the pump P to the piping between the raw water tank 1 and the first reaction tank 2. The COD of the first reactor 2 was about 300 ppm. Instead of saline solution, sodium hypochlorite water may be used. In the figure, S denotes a water level sensor and V denotes a valve.

This water treatment mechanism applies a diaphragm current that flows a current (current density of about 1 to 80 A / dm 2) into water in which salt is dissolved (a salt concentration of about 1 to 30%) and generates chlorine gas 4 at the anode side thereof. The tank 5 is provided. When a current flows through the salt-dissolved water in this diaphragm electric current application tank 5, the anode side becomes an acidic atmosphere (about pH 1-3), and chlorine gas 4 is generated. On the other hand, the cathode side is in a basic atmosphere (pH 12 to 14). This anode side water is not purified and the inflow stops in the tank in one way.

The chlorine gas 4 generated at the cathode side is recovered by ensuring airtightness to be directly and indirectly treated water and reducing the COD of the water to be treated by the oxidation.

That is, firstly, the recovered chlorine gas 4 is brought directly to the water to be treated. Specifically, the chlorine gas 4 generated at the anode side of the diaphragm current applying tank 5 is sucked into the water to be treated through the piping by the air pump AP, and mixed well in the first reaction tank 2 ( Treated water stays for a certain time). Inhaled chlorine gas is directly decomposed by encountering contaminants (organic compounds), and combined with water or hydroxyl ions in the water to be treated to form hypochlorous acid (HOCI), attacking contaminants, and cutting off the bonds. Reduce the

Second, sodium hypochlorite (NaOCl) or hypochlorous acid is generated by the recovered chlorine gas (4), and the sodium hypochlorite is extended to the treated water. That is, the collected chlorine gas is introduced into the hypochlorous acid production tank 6 (storage of sodium hydroxide solution) to generate sodium hypochlorite, and the sodium hypochlorite is pumped to the water to be treated through a pipe by a pump P. In this case, the mixture is mixed well in the first reactor (2). Here, the hypochlorous acid generating tank 6 can replenish a portion of the treated water on the cathode side of the diaphragm current applying tank 5. In this hypochlorous acid production tank 6, the alkaline water and the chlorine gas of the replenished cathode side are combined to generate hypochlorous acid.

In addition, the water to be treated that is directly or indirectly decomposed by chlorine gas in the first reaction tank 2 is sent to the electrolytic cell 7 of the membrane, and electrolysis (anode oxidation) in the electrolytic cell 7 reduces COD. (Current density of about 1 to 80 A / dm 2), and to the diaphragm current application tank 5. That is, COD of the water to be treated is reduced by chlorine gas itself, hypochlorous acid caused by chlorine gas, and electrolytic anodic oxidation, respectively.

However, by the electrolysis in the electrolytic cell 7, residual chlorine (Cl ₂ , HOCl) is generated in the water to be treated, thereby reducing COD, and reducing the residual chlorine at the cathode side of the above-described diaphragm current applying tank 5. Do it. That is, when the to-be-processed water is supplied to the cathode side of the said clearance film current application tank 5, the residual chlorine concentration can be reduced in basic atmosphere. In addition, part of the water to be treated is refluxed to the anode side.

The water to be treated after passing through the cathode side of the diaphragm current applying tank 5 is injected with a reducing agent (sodium bisulfite) 8 by a pump P to maintain the second reaction tank 9 (the water to be treated for a predetermined time). To reduce the residual chlorine concentration further, to further remove residual chlorine from the next activated carbon catalyst tank 10, and to pass the RO membrane through the third reaction tank 11 (the water to be treated remains for a certain time). Ions are separated by the other desalted membrane 12. Finally, the COD is less than 5 ppm. Part of the final treated water is circulated by feeding back to the front of the first reaction tank 2 through the pipe. That is, the feedback path 13 of the final treated water is sent to the raw water tank 1 as it is, and the feedback path 14 is mixed with the chlorine gas 4 described above to be sent to the first reaction tank 2.

In addition, when ammonia nitrogen was also contained in the to-be-processed water, it was estimated to decompose | dissolve into nitrogen gas finally by hypochlorous acid.

Next, the use condition of the water treatment apparatus of this embodiment is demonstrated.

In this water treatment method, a current flows through the water in which the salt is dissolved in the diaphragm current applying tank 5, generates chlorine gas 4 at the anode side, and recovers the chlorine gas 4 directly and indirectly. While reducing the COD by reaching the treated water, the treated water after the reduction of the COD is supplied to the cathode side of the play film current application tank 5 so as to reduce the residual chlorine concentration.

This water treatment method and apparatus recovers the chlorine gas generated at the anode side of the diaphragm current application tank 5 without opening it to the water to reach the water to be treated, and chemically cuts and binds contaminant bonds. Since it is reduced, sludge (such as the dead sea of microorganisms) as in the case of biological treatment does not occur.

In addition, since the treated water was supplied after the reduction of COD to the cathode side of the diaphragm current applying tank 5 to reduce the residual chlorine concentration, extra ions (chlorine ions, sodium ions, etc.) in the treated water were removed. There is an advantage in that the membrane is hardly damaged when being separated and removed by the membrane or the like, and the life thereof can be extended.

Further, the water to be treated after COD reduction is supplied to the cathode side of the membrane current applying tank 5, and anions such as chlorine ions in the water to be treated on the cathode side are electrically attracted to the anode side through the diaphragm and transferred. There is an advantage that can be separated and reduced.

In addition, since the chlorine gas 4 was generated on the anode side of the membrane current applying tank 5 and the treated water after COD reduction was supplied to the cathode side to separate and reduce the anions, the membrane current applying tank ( There is an advantage that the anode side and the cathode side of 5) can be utilized cleverly.

By the way, in the biological treatment, when the concentration of COD of the water to be treated is higher than the reference concentration, the nutrition becomes excessive and the treatment by the microorganism becomes impossible, but according to the present invention, the concentration change is increased by increasing the applied current in the electrolytic cell 7. Can easily adapt to a wide range of wastewater treatment.

In addition, when the throughput of the water to be treated is increased, it is necessary to increase the pit in the biological treatment, and a large amount of cost is required for the construction. Can be responded to.

Sludge is not generated as in conventional biotreatment, so it can be applied not only to various plant waters and beverages but also to water management of swimming pools, drainage of plums and udon and other food processing plants, and groundwater. can do.

1 is a system flow diagram illustrating an embodiment of a water treatment apparatus of the present invention.

*** Description of the symbols for the main parts of the drawings ***

4: chlorine gas

5: diaphragm current application tank

Claims (7)

In the diaphragm current application tank, current flows into the dissolved water to generate chlorine gas from the anode side, and the chlorine gas is recovered and directly or indirectly to the water to be treated to reduce the pollution evaluation index. Water treatment method. The water treatment method according to claim 1, wherein the recovered chlorine gas is directly brought to the water to be treated. The water treatment method according to claim 1 or 2, wherein the hypochlorous acid and / or sodium hypochlorite generated by the recovered chlorine gas is brought into the treated water. The water treatment method according to any one of claims 1 to 3, wherein the water to be treated is electrolyzed and anodized so as to be sent to the cathode side of the membrane current applying tank. The water treatment method according to claim 4, wherein bromine is dissolved during the electrolysis. The water treatment method according to any one of claims 1 to 5, wherein the water to be treated is a mixture of water, a protonic amphiphilic solvent, an aprotic amphiphilic solvent, and a hydrophobic organic component. It is provided with a diaphragm current application tank which flows an electric current in the water in which chlorine is dissolved, and generates chlorine gas at the anode side, and recovers the chlorine gas directly or indirectly to the water to be treated to reduce the pollution evaluation index. The water treatment apparatus characterized by the above-mentioned.

Images