JP2010063985A - Method and mechanism for reducing halogen acids - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method and a mechanism which can reduce halogen acids such as chloric acid and bromic acid. <P>SOLUTION: The method for reducing halogen acids is characterized in that the water to be treated containing halogen acids is fed to an electrolytic region on the cathode side so as to be electrolyzed through a diaphragm, and further, the water pressure in the electrolytic region on the cathode side is set so as to be higher than that in an electrolytic region on the anode side. The mechanism for reducing halogen acids is characterized in that the water to be treated comprising halogen acids is fed to an electrolytic region on the cathode side so as to be electrolyzed through the diaphragm, and further, the water pressure in the electrolytic region on the cathode side is set so as to be higher than that in an electrolytic region on the anode side. Chloric acid, bromic acid, hypochlorous acid and hypobromous acid comprised in the water to be treated are reduced, thus their concentration can be reduced. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a reduction method and a reduction mechanism of halogen acids such as chloric acid and bromic acid.

The enforcement regulations of the Water Supply Law stipulate that the water in the faucet should be sterilized so that free residual chlorine such as hypochlorous acid (HCI) is retained at 0.1 mg / L or more. In addition, facilities that pump up groundwater, filter it, and purify it into drinking water are treated in the same way.
By the way, chloric acid (HClO ₃ ) was added to the water quality standard item of the Water Supply Law that came into effect from April 2008, and the standard value became 0.6 mg / l or less. This is because oxidative damage (hemoglobin, blood cell volume, decrease in red blood cells, etc.) to red blood cells has been considered, although knowledge about carcinogenicity is not sufficient as a health effect of chloric acid (Non-patent Document 1).
However, when water containing hypochlorous acid is stored for a long period of time, the concentration of chloric acid tends to increase due to disproportionation. There was a problem that it was easier to cross.
Addition of “chloric acid” to tap water quality standards / Naito Environmental Management Co., Ltd .; www.knights.jp/knightsreport/reports/KR06012.pdf

  Therefore, the present invention intends to provide a method and mechanism capable of reducing halogen acids such as chloric acid and bromic acid.

In order to solve the above problems, the present invention takes the following technical means.
(1) In the method for reducing halogen acids of the present invention, water to be treated containing halogen acids is supplied to the cathode-side electrolysis region and electrolyzed with a diaphragm, and the cathode-side electrolysis region has a water pressure higher than that of the anode-side electrolysis region. Is set high.
In addition, the halogen acid reduction mechanism of the present invention has an electrolysis mechanism in which water to be treated containing halogen acids is supplied to the cathode-side electrolysis region and electrolyzed by the diaphragm, and the cathode-side electrolysis region is the anode-side electrolysis region. The water pressure is set higher than that.

The “halogen acids” include halogen acids (chloric acid, bromic acid) and hypohalous acids (hypochlorous acid, hypobromous acid). It is only necessary that the “treated water” includes at least one of the above. Relatively clean water such as tap water can be supplied to the anode-side electrolysis region (as treated water necessary for electrolysis), and waste water can be supplied as described later.
This reduction method and mechanism of halogen acids (HClO, HClO ₃ , HBrO, HBrO ₃ ) is such that water to be treated containing halogen acids is supplied to the cathode-side electrolysis region side and electrolyzed with a diaphragm. Therefore, chloric acid, bromic acid, hypochlorous acid and hypochlorous acid contained in the water to be treated can be reduced and the concentration thereof can be reduced. For example, chloric acid is reduced to form hypochlorous acid, and the concentration is reduced. As a result, for example, it can be processed so that it can comply with the water quality standard value of 0.6 mg / l or less of the chloric acid of the revised Waterworks Law. The storage temperature and storage period of the sodium solution itself are even more important). In the anode-side electrolysis region, hypohalous acid or the like is generated reversely by anodic oxidation, but interference from the anode side to the cathode side is suppressed or prevented by the diaphragm. For example, a reverse osmosis membrane can be used as the diaphragm.

In addition, since the cathode side electrolysis region has a higher water pressure than the anode side electrolysis region and has a differential pressure, the halogen acids in the anode side electrolysis region pass through the diaphragm and enter the cathode side electrolysis region to contaminate the region. Can be prevented. On the other hand, ionic species such as halogen acids, chlorine ions, bromine ions, etc. in the cathode side electrolysis region pass through the diaphragm due to the differential pressure and are pushed out to the anode side electrolysis region and are easily removed and reduced. .
Furthermore, although hydroxide ions (OH ⁻ ) are generated in the cathode-side electrolysis region, the hydroxide ions are also subjected to stress that is pressed against the diaphragm by the differential pressure, and the mutual interaction with the halogen acids in the water to be treated in the vicinity of the diaphragm. The action is promoted by pressurization, and the ionic species after the reaction are easily removed and purified by passing through the diaphragm and being pushed out to the anode side electrolysis region.

Here, when the drainage water is supplied to the anode side electrolysis region as described above, the organic components in the wastewater (ordinary organic components, benzene, toluene, dioxins, PCB, etc.) are anodized. COD and TOC can be reduced and purified by decomposing refractory organic compounds. That is, reduction treatment of halogen acids in the water to be treated in the cathode side electrolysis region and purification treatment of waste water in the anode side electrolysis region (reduction of COD and TOC, decomposition of difficult-to-decompose organic compounds) are combined in one device. Will be able to.
In addition, when a porous material is added to the diaphragm in the anode side electrolysis region so as to function as a structural material, the diaphragm can be prevented from being bent and deformed by the differential pressure toward the anode. When several layers of the cathode side electrolysis region and the anode side electrolysis region are stacked and integrated, a large volume of water to be treated can be treated more compactly.

(2) You may make it circulate through the said anode side electrolysis area | region.
With this configuration, in the electrolysis, treated water such as tap water can be saved, and in the case of drainage, organic components can be sufficiently decomposed, and hypochlorous acid is generated and circulated on the anode side. Can be concentrated. This concentrated water of hypochlorous acid has an oxidizing action, and can be taken out from the circulation path to purify it to reduce COD and TOC in various wastewaters, and can also be used as sterilizing water in factories and others. . In the anode side electrolysis region, it may be circulated while taking out a part of the treated water, or may be circulated while newly supplying the treated water.
Here, when the cathode side electrolysis region is circulated, the reducing action can be exerted again on the halogen acids that have not been decomposed before.

(3) The cathode-side electrolysis region and the anode-side electrolysis region may have a flow in opposite directions through the diaphragm.
As a mode having a flow in the opposite direction through the diaphragm, in the flow direction along the diaphragm, the opposite direction (for example, one side of the diaphragm arranged in the vertical direction flows from left to right and the other side flows from right to left. Or a crossing direction (for example, one side of the diaphragm arranged in the vertical direction flows from the lower left to the upper right, and the other side flows from the lower right to the upper left).
If comprised in this way, the relative gap | deviation speed of the flow of both area | regions will become large, and the interaction through a diaphragm will increase. Also, due to this, regarding the transfer of ion species from the cathode side to the anode side where the water pressure is high, chlorine ions and bromine ions in the cathode side electrolysis region are electrically attracted to the anode side electrolysis region via the diaphragm. The tendency to migrate and be eliminated / reduced will be increased. Furthermore, it can suppress that a diaphragm bends and deform | transforms in one direction (flow direction) like the case where it flows in the same direction.

(4) The cathode-side electrolysis region and the anode-side electrolysis region may be provided with rows each composed of a plurality of columnar electrodes as a cathode electrode and an anode electrode.
If comprised in this way, electrolysis efficiency can be increased by being able to expand a surface area three-dimensionally by the row | line | column which consists of a columnar electrode instead of a flat surface like a plate-shaped electrode.
In addition, the treated water does not flow as a mere laminar flow along the electrode surface like a plate-like electrode, but rather acts as a turbulent flow around the columnar electrode array, causing the flow direction to change in a complex manner. The mixing is promoted by the stirring action of the water to be treated. In addition, the reduction reaction of the halogen acids can be accelerated by amplifying the turbulent flow by the differential pressure of the water pressure.
Here, the electrode can be made of a conductive ceramic which is difficult to elute. The columnar electrodes can be formed by connecting a plurality of short electrodes in the longitudinal direction. With such a short articulated structure, the yield at the time of firing in the case of being made of ceramics is improved as compared with the long body. Examples of the shape of the columnar electrode include a columnar shape, a cylindrical shape, a polygonal cross-sectional shape with smoothed corners to prevent local discharge, an elliptical cross-sectional shape, and those in which spherical electrodes are continuously arranged in a columnar shape.

(5) The treated water generated by the halogen acids through the anode-side electrolysis region may be exerted on the waste water, and at least a part of the treated water may be supplied to the cathode-side electrolysis region as treated water.
When treated water passes through the anode-side electrolysis region, halogen acids (residual chlorine) are generated by anodic oxidation (halogen acids may be intentionally generated at a high concentration). When this treated water containing residual chlorine is applied to wastewater from factories and other places, COD and TOC can be reduced and purified, and residual chlorine is consumed and reduced with the purification reaction.
COD and TOC are reduced, and at least a part of the treated water that has been consumed and reduced due to consumption of halogen acids (residual chlorine) is supplied to the cathode side electrolysis region as treated water to further reduce the concentration of halogen acids. Then, it is possible to obtain clean water to be treated in which COD and TOC are reduced and the concentration of halogen acids is further reduced. This clean treated water is reused as factory water. Treated water with reduced COD and TOC and consumption of halogen acids (residual chlorine) is supplied to the cathode side electrolysis area as described above, and part of it is discharged outside the treatment system. Alternatively, a part of it may be supplied (circulated) to the anode side electrolysis region to regenerate residual chlorine as treated water.
And the to-be-processed water after utilization as factory water etc. feeds back toward the said anode side electrolysis area | region as waste_water | drain, and is purified. In this way, a wastewater treatment cycle can be formed using the anode-side electrolysis region and the cathode-side electrolysis region.

(6) Conventionally, residual chlorine has generally been treated with a reducing agent such as sodium bisulfite, but it could hardly be adjusted even if the residual chlorine concentration was controlled by the amount of the reducing agent. In other words, the amount of the reducing agent was excessively adjusted, and there was a tendency that the amount of the reducing agent was too much or too little to go too quickly. On the other hand, according to the halogen acid reduction method and reduction mechanism, the concentration of residual chlorine after the reduction of residual chlorine can be adjusted by adjusting the applied voltage, current value, residence time of water to be treated in the electrolysis region, etc. during electrolysis. The control can be performed more precisely. For example, when the treated wastewater is reused without being discharged, the residual chlorine concentration appropriate for the intended use (for drinking water or sterilizing water in the factory, etc.) ) Can be adjusted.

  This method and mechanism for reducing halogen acids can be applied when chlorine disinfection is performed such that groundwater such as well water is pumped and filtered to obtain drinking water. That is, the chloric acid concentration can be suitably reduced and controlled. Also applied when wastewater COD and TOC are reduced by addition of oxidant or electrolysis, and the remaining hypohalous acids are reduced or removed to regenerate drinking water, sterilizing water, or industrial water. be able to. Furthermore, it can be suitably applied to residual chlorine concentration management in swimming pools, baths (baths), hot springs, and the like.

The present invention is configured as described above and has the following effects.
Since the water to be treated containing halogen acids was supplied to the cathode side electrolysis region in particular and electrolyzed with the diaphragm, chloric acid, bromic acid, hypochlorous acid contained in the water to be treated, Hypobromite can be reduced to reduce its concentration.

Embodiments of the present invention will be described below.
(Embodiment 1)
As shown in FIG. 1, the halogen acid reducing mechanism of this embodiment has an electrolysis mechanism in which water to be treated 1 containing halogen acids is supplied to the cathode-side electrolysis region 2 and electrolyzed by the separation membrane 3. A reverse osmosis membrane is used as the diaphragm 3. The cathode side electrolysis region 2 is set to have a higher water pressure than the anode side electrolysis region 4. The anode side electrolysis region 4 is circulated.
In the cathode-side electrolysis region 2 and the anode-side electrolysis region 4, a row of a plurality of columnar electrodes is disposed as the cathode electrode 5 and the anode electrode 6, respectively. The electrodes are made of conductive ceramics that are difficult to elute. The columnar electrodes are formed by connecting a plurality of short electrodes in the longitudinal direction (not shown), and since such a short connection structure is used, the yield during firing is longer than that of the long body. It has improved.

The to-be-treated water 1 contains halogen acids, and can be exemplified by original water for supplying as drinking water, factory waste water, and the like. Examples of the halogen acids include halogen acids (chloric acid HClO ₃ , bromic acid HBrO ₃ ) and hypohalous acids (hypochlorous acid HClO, hypobromite HBrO). The anode-side electrolysis region 4 can be supplied with relatively clean water such as tap water as the treated water 7 necessary for electrolysis, or can be supplied with waste water as described later.
In the anode side electrolysis region 4, a porous material 8 is added to the diaphragm 3 to function as a structural material, and the diaphragm 3 is prevented from being bent and deformed to the anode side due to a differential pressure of water pressure.

Next, the usage state of this halogen acid reduction mechanism will be described. That is, to-be-treated water 1 containing halogen acids is supplied to the cathode-side electrolysis region 2 and electrolyzed by the diaphragm 3, and the cathode-side electrolysis region 2 is set to have a slightly higher water pressure than the anode-side electrolysis region 4. use.
(1) The mechanism for reducing halogen acids is that the water to be treated 1 containing halogen acids is supplied to the cathode side electrolysis region 2 in particular and electrolyzed with the diaphragm 3. Chloric acid, bromic acid, hypochlorous acid, and hypobromous acid contained therein can be reduced to reduce their concentration. For example, chloric acid is reduced to form hypochlorous acid, and the concentration is reduced. As a result, for example, it can be processed so that it can comply with the water quality standard value of 0.6 mg / l or less of the chloric acid of the revised Waterworks Law. The storage temperature and storage period of the sodium solution itself are even more important). On the other hand, hypohalous acid or the like is generated reversely by anodic oxidation in the anode side electrolysis region 4, but interference from the anode side to the cathode side is suppressed or prevented by the diaphragm 3.

Further, since the cathode side electrolysis region 2 has a higher water pressure and a differential pressure than the anode side electrolysis region 4, the halogen acids in the anode side electrolysis region 4 pass through the diaphragm 3 and enter the cathode side electrolysis region 2. It is possible to prevent the region from being contaminated. On the other hand, ionic species such as halogen acids, chlorine ions, bromine ions, etc. in the cathode side electrolysis region 2 pass through the diaphragm 3 due to the differential pressure and are pushed out to the anode side electrolysis region 4 to be easily removed and reduced. It has become.
Furthermore, although hydroxide ions (OH ⁻ ) are generated in the cathode-side electrolysis region 2, the hydroxide ions are also subjected to stress that is pressed against the diaphragm 3 due to the differential pressure, and thus in the treated water 1 in the vicinity of the diaphragm 3. The interaction with the halogen acid is promoted by pressurization, and the ionic species after the reaction are easily pushed out to the anode side electrolysis region 4 through the diaphragm 3 and easily removed and purified.

(2) Since the cathode side electrolysis region 2 and the anode side electrolysis region 4 are provided with a plurality of columnar electrodes as the cathode electrode 5 and the anode electrode 6, respectively, a flat plate like a plate electrode is provided. Since the surface area can be expanded three-dimensionally not by a surface but by a row of a plurality of columnar electrodes, electrolysis efficiency can be increased.
Further, the treated water 1 does not flow as a mere laminar flow along the electrode surface like a plate-like electrode, but rather turbulently flows around the columnar electrode row so as to change the flow direction in a complicated manner. Mixing is promoted by the stirring action of the water 1 to be treated due to the behavior. In addition, the reduction reaction of the halogen acids can be accelerated by amplifying the turbulent flow by the differential pressure of the water pressure.
(3) The anode-side electrolysis region 4 is circulated to save treated water 7 such as tap water for electrolysis, and in the case of drainage, organic components can be sufficiently decomposed. Hypochlorous acid can be produced on the anode side and concentrated by circulation. This concentrated water of hypochlorous acid has an oxidizing action, and can be taken out from the circulation path to purify it to reduce COD and TOC in various wastewaters, and can also be used as sterilizing water in factories and others. . That is, the anode side electrolysis region 4 may be circulated while taking out a part of the treated water 7 or may be circulated while newly supplying the treated water 7.
In addition, when the cathode side electrolysis region 2 is circulated (not shown), the reducing action can be exerted again on the halogen acids that have not been decomposed before.

(4) When wastewater is supplied to the anode-side electrolysis region 4, the organic components in the wastewater are anodized (ordinary organic components, refractory organic compounds such as benzene, toluene, dioxins, PCB, etc.) ) To reduce and purify COD and TOC. That is, the reduction treatment of the halogen acids in the water 1 to be treated in the cathode side electrolysis region 2 and the purification treatment of the waste water (reduction of COD and TOC, decomposition of the hardly decomposable organic compound) in the anode side electrolysis region 4 are one. It can be used in combination with the device.
(5) In the past, residual chlorine was generally treated with a reducing agent such as sodium bisulfite, but it was hardly possible to control the residual chlorine concentration with the amount of reducing agent. In other words, the amount of the reducing agent was excessively adjusted, and there was a tendency that the amount of the reducing agent was too much or too little to go too quickly. On the other hand, according to the method and mechanism for reducing halogen acids, the concentration after reduction of residual chlorine is adjusted by adjusting the applied voltage, current value, residence time of water to be treated 1 in the electrolysis region, etc. during electrolysis. In this case, for example, when the treated wastewater is reused without being discharged, the residual chlorine concentration can be adjusted to an appropriate concentration according to the application.

(6) This halogen acid reduction method and reduction mechanism can be applied when chlorine disinfection is performed such that groundwater such as well water is pumped and filtered to obtain drinking water. That is, the chloric acid concentration can be suitably reduced and controlled. Also applied when wastewater COD and TOC are reduced by addition of oxidant or electrolysis, and the remaining hypohalous acids are reduced or removed to regenerate drinking water, sterilizing water, or industrial water. be able to. Furthermore, it can be suitably applied to residual chlorine concentration management in swimming pools, baths (baths), hot springs, and the like.

(Embodiment 2)
As shown in FIG. 2, in this embodiment, the cathode-side electrolysis region 2 and the anode-side electrolysis region 4 have a flow in opposite directions through the diaphragm 3. As an aspect having a flow in the opposite direction through the diaphragm 3, as shown in FIG. 3, in the flow direction along the diaphragm 3, the opposite direction (for example, one side of the diaphragm 3 arranged in the vertical direction is from left to right. Flow, the other side flows from right to left), and as shown in FIG. 4, the crossing direction (for example, one side of the diaphragm 3 arranged in the vertical direction flows from the lower left to the upper right, and the other side is the lower right To the upper left).
Since it comprised in this way, the relative gap | deviation speed of the flow of both area | regions becomes large, and the interaction through the diaphragm 3 increases. Further, due to this, regarding the transfer of ionic species from the cathode side to the anode side having a high water pressure, chlorine ions and bromine ions in the cathode side electrolysis region 2 are electrically supplied to the anode side electrolysis region 4 through the diaphragm 3. The tendency to be attracted and transferred to be eliminated / reduced is increased. Further, the diaphragm 3 can be prevented from being bent and deformed in one direction (flow direction) as in the case of flowing in the same direction.

(Embodiment 3)
As shown in FIG. 5, in this embodiment, treated water 7 that has passed through the anode-side electrolysis region 4 and produced halogen acids (residual chlorine) is joined to and mixed with the drainage 9, and after that part of the treated water 7 is applied. It is made to supply to the cathode side electrolysis area | region 2 as to-be-processed water 1 (a in FIG. 5).
That is, when the treated water 7 passes through the anode side electrolysis region 4, halogen acids are generated by anodic oxidation. However, if treated water 7 containing this residual chlorine is applied to the factory 10 and other waste water 9, COD and TOC are reduced. In addition to being purified, residual chlorine is consumed and reduced with the purification reaction. COD and TOC are reduced, and a part of the treated water 7 which is consumed and reduced as a result of consumption of halogen acids is supplied to the cathode-side electrolysis region 2 as treated water 1 to further reduce the concentration of halogen acids. Then, it is possible to obtain clean treated water 1 in which COD and TOC are reduced and the concentration of halogen acids is further reduced. This clean water 1 to be treated is reused as water for treatment in the factory 10.

  Further, COD and TOC are reduced by merging and mixing, and another part of the treated water 7 reduced by consumption of halogen acids (residual chlorine) is fed back (circulated) toward the anode-side electrolysis region 4. Then, it is purified again and residual chlorine is generated (b in FIG. 5). In addition, COD and TOC are reduced by merging / mixing, and other part of the treated water 7 that has been reduced due to consumption of halogen acids (residual chlorine) is discharged out of the treatment system (c in FIG. 5). . As described above, the anode-side electrolysis region 4 and the cathode-side electrolysis region 2 are used to form a cycle of treatment and reuse of the waste water 9 of the factory 10.

Since the concentration of halogen acids can be reduced, it can be applied to the following uses.
(1) It can be applied when chlorination is performed so that groundwater such as well water is pumped and filtered to make it suitable for drinking. In other words, hypochlorite is disproportionated and chloric acid is likely to be produced in high temperatures such as in summer, and there is concern about compliance with the standards of the Waterworks Law. When applied, the chloric acid concentration can be suitably reduced and controlled (note that the storage temperature and storage period of the sodium hypochlorite solution itself, which is the basis for residual chlorine, are more important as countermeasures for chloric acid in drinking water).
(2) Applicable when wastewater COD and TOC are reduced by adding oxidants or electrolysis, and then reducing or removing residual hypohalous acids to regenerate them into drinking water, sterilized water, or industrial water. can do.
(3) It can be suitably applied to residual chlorine concentration management in swimming pools, baths (baths), hot springs, etc.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a layout diagram for explaining Embodiment 1 of a halogen acid reducing mechanism of the present invention. FIG. 6 is a layout diagram for explaining Embodiment 2 of the halogen acid reducing mechanism of the present invention. Explanatory drawing of 1 aspect of embodiment of the reduction mechanism of halogen acids of FIG. Explanatory drawing of 1 aspect of embodiment of the reduction mechanism of halogen acids of FIG. FIG. 6 is a layout diagram for explaining Embodiment 3 of the halogen acid reducing mechanism of the present invention;

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Water to be treated 2 Cathode side electrolysis region 3 Membrane 4 Anode side electrolysis region 5 Cathode electrode 6 Anode electrode 7 Treated water 9 Drainage

Claims (6)

  The treated water 1 containing halogen acids is supplied to the cathode side electrolysis region 2 and electrolyzed by the diaphragm 3, and the cathode side electrolysis region 2 is set to have a higher water pressure than the anode side electrolysis region 4. And a method for reducing halogen acids.   It has an electrolysis mechanism for supplying water to be treated 1 containing halogen acids to the cathode side electrolysis region 2 and electrolyzing it with the diaphragm 3, and the cathode side electrolysis region 2 has a higher water pressure than the anode side electrolysis region 4. This is a mechanism for reducing halogen acids.   The mechanism for reducing halogen acids according to claim 2, wherein the anode-side electrolysis region (4) is circulated.   The halogen acid reduction mechanism according to claim 2 or 3, wherein the cathode side electrolysis region 2 and the anode side electrolysis region 4 have a flow in a direction opposite to each other through the diaphragm 3.   The halogen acid according to any one of claims 2 to 4, wherein the cathode side electrolysis region 2 and the anode side electrolysis region 4 are provided with a plurality of columnar electrodes arranged as a cathode electrode 5 and an anode electrode 6, respectively. Reduction mechanism. The treated water 7 generated by halogen acids through the anode-side electrolysis region 4 is applied to the waste water 9, and at least a part of the treated water 7 is supplied to the cathode-side electrolysis region 2 as the treated water 1. A mechanism for reducing halogen acids according to any one of 2 to 5.