JPH09150159A - Cod-related component removing method for the component containing water - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the removing ratio of COD-related component in waste water without using chemicals such as alkaline agent by subjecting the component-containing water to an electrolytic oxidation at an anode chamber of a diaphragm electrolytic cell under the copresence of hydrogen peroxide and iron ion, then neutralizing the water in a cathode chamber. SOLUTION: The COD-related component containing water 1 is supplied to the anode chamber 6 of the diaphragm electrolytic cell 2 having an acidic atmosphere of about pH3-4. Fenton's reaction is progressed together with an electrolytically oxidizing reaction by simultaneously adding hydrogen peroxide 9 and iron salt or metal iron (iron ion) 10. Then the water to be electrolytically oxidized flowing out from the anode chamber 6 through a bypass 11 is introduced to a cathode chamber 7. The introduced water to be electrolytically oxidized is neutralized with a hydroxide ion produced at the cathode chamber 7 by the electrolytic reaction. Therefore, a neutral treated water 12 from which the COD-related component is removed is obtained, and a clear treated water is obtained by subjecting the neutral treated water 12 to a solid-liq. separation to remove incorporated iron hydroxide particulates.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a technique for effectively oxidatively decomposing poorly biodegradable COD in various wastewaters, and in particular, it effectively oxidatively decomposes a yellowish brown chromaticity component in biotreated water of manure. It is about technology.

[0002]

2. Description of the Related Art Hitherto, as a technique for oxidatively decomposing poorly biodegradable COD in various kinds of waste water, the Fenton method (hydrogen peroxide-iron salt combination method), ultraviolet ray-hydrogen peroxide combination method, ultraviolet ray-photocatalyst combination method has been used. Method, UV-ozone oxidation combined use method, ozone-hydrogen peroxide combined use method, etc. are known, but all of them are not suitable for the ultrapure water production field because of the high treatment cost but poor COD removal rate. There were few practical examples.

[0003]

In the conventional Fenton method, hydrogen peroxide and an iron salt are added to water to be treated under acidic conditions to generate hydroxy radicals, and CO in the water to be treated is generated.
This is a method of decomposing D and then neutralizing it by adding an alkaline agent, but since the amount of radicals generated is small, the COD removal rate is not as large as expected, and it is necessary to handle a powerful drug such as an alkaline agent. was there. An object of the present invention is to improve the Fenton method, to provide a new technology capable of removing COD in wastewater at a high removal rate and avoiding the need to handle a powerful drug such as an alkaline agent.

[0004]

The above-mentioned problems of the present invention are as follows.
(1) Supplying COD-containing water to the anode chamber of the diaphragm electrolyzer, electrolytically oxidizing it in the anode chamber in the presence of hydrogen peroxide and iron ions, and then introducing it to the cathode chamber of the diaphragm electrolysis tank for neutralization. A method for removing COD-containing water. Preferably, (2) it is achieved by the method for removing COD-containing water COD according to the above (1), characterized in that the electrode material of the anode provided in the anode chamber is iron.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION A flow chart of a treatment process of the present invention, which mainly includes a diaphragm electrolyzer for removing COD in waste water, is shown in FIG. 1, and the present invention will be described below with reference to FIG. Incidentally, the Fenton reaction that occurs in the presence of hydrogen peroxide and iron salts under acidic conditions is shown by the following reaction formula. H ₂ O ₂ + Fe ²⁺ → Fe ³⁺ + HO ⁻ + .OH

In FIG. 1, the structure of the diaphragm electrolysis tank 2 is divided into two chambers by a diaphragm 5 provided in the tank, and an anode chamber 6 and an anode chamber 6 are provided in each chamber by disposing an anode 3 and a cathode 4. Cathode chamber 7
And Both the anode 3 and the cathode 4 are preferably platinum-plated titanium electrodes or electrodes made of iron material. An organic microfiltration membrane (called an MF membrane) is usually used for the diaphragm 5. Filling the diaphragm electrolyzer 2 of the above structure with water to be treated,
When a direct current is applied from the power source 8, hydrogen ions are generated by an electrolytic reaction in the anode chamber 6 of the diaphragm electrolyzer 2 to create an acidic atmosphere of pH 3-4. This electrolytic reaction is represented by the following reaction formula. _{H 2 O → 1 / 2O 2} + 2H + + 2e -

In the present invention, the COD-containing water 1 is added to the anode chamber 6 of the diaphragm electrolyzer 2 in the acidic atmosphere of pH 3 to 4.
At the same time as the supply of hydrogen peroxide, hydrogen peroxide 9 and iron salt or metallic iron (iron powder or the like) 10 are added, and the Fenton reaction proceeds together with the electrolytic oxidation reaction. In the present invention, hydrogen ions are generated in the anode chamber 6 of the diaphragm electrolyzer 2 by an electrolytic reaction. Therefore, even if an acid such as sulfuric acid is not added, the Fenton reaction effectively proceeds together with the electrolytic oxidation reaction, and CO
It was found that D was highly removed. If the material of the anode 3 is iron, iron ions are supplied to the medium from the electrode, so that it is not necessary to add iron salt or metallic iron from the outside, which is preferable.

As described above, COD-containing water is supplied to the anode chamber of the diaphragm electrolyzer in an acidic atmosphere, and at the same time, hydrogen peroxide and iron salt or metallic iron (iron powder, etc.) are added to carry out the Fenton reaction together with the electrolytic oxidation reaction. It is presumed that COD is highly removed from the COD-containing water by advancing the hydrogen peroxide because the active oxygen species such as hydroxy radicals are effectively generated at the electrode interface by the Fenton reaction and the electrolytic reaction at the same time. .

Next, when the electrolytically oxidized water that has flowed out from the anode chamber 6 via the bypass 11 is guided to the cathode chamber 7, the following electrolytic reaction formula is used in the cathode chamber 7, H ₂ O + e ⁻ → 1 / 2H ₂ + OH ⁻ . Since hydroxyl ions are generated by the reaction shown, the acidic electrolytically oxidized treated water is neutralized, and neutral treated water 12 from which COD has been removed is obtained. Since the treated water 12 contains iron hydroxide fine particles, solid-liquid separation is performed to obtain clear treated water. Even if the water to be treated containing COD is treated only by the Fenton reaction instead of performing the electrolytic reaction simultaneously with the Fenton reaction as in the case of the present invention, the COD removing effect is small. Even if the electrolytic treatment of the diaphragm is performed without supplying hydrogen peroxide and iron salt, the COD removing effect is still considerably inferior to the method of the present invention.

[0010]

【Example】

Example, Comparative Example Using the apparatus of FIG. 1, COD removal of the present invention was performed on separated water obtained by subjecting biologically treated water of feces and urine to membrane separation with a UF membrane. Table 1 shows the water quality of the COD-containing water used for the treatment.

[0011]

[Table 1]

Tables 2 and 3 show the capabilities and operating conditions of the anode chamber and cathode chamber of the diaphragm electrolysis tank for supplying COD-containing water. The amount of COD-containing water supplied to the anode chamber of the diaphragm electrolysis tank was 5 liters per day.

[0013]

[Table 2]

[0014]

[Table 3]

Next, when anodized water is transferred from the anode chamber of the diaphragm electrolysis tank to the cathode chamber and electrolyzed in the cathode chamber, hydroxide ions are generated to neutralize the acidic anodized water and remove COD. A pH-neutral treated water is obtained. Since iron hydroxide fine particles are contained in the treated water, this is solid-liquid separated to obtain clear treated water. Table 4 shows the quality of treated water. For comparison, the COD-containing water having the water quality shown in Table 1 is also shown together with the results obtained by treating Fenton alone or electrolytically.

[0016]

[Table 4]

[0017]

【The invention's effect】

1. COD, which cannot be biodegraded, can be effectively removed by the Fenton-diaphragm electrolytic composite method . 2. The pH lowering effect in the diaphragm electrolysis anode chamber can be used to improve the efficiency of Fenton oxidation. 3. The pH increasing effect in the diaphragm electrocathode chamber can be utilized for neutralization after Fuenton oxidation. 4. There is no need to use acid or alkaline agents that are deleterious substances.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing an example of a flow of a COD removal process of the present invention mainly using a diaphragm electrolyzer.

[Explanation of symbols] 1 COD-containing water 2 Diaphragm electrolyzer 3 Anode 4 Cathode 5 Diaphragm 6 Anode chamber 7 Cathode chamber 8 Power supply 9 Hydrogen peroxide 10 Iron ion 11 Bypass 12 Treated water

Claims (2)

[Claims] 1. COD-containing water is supplied to an anode chamber of a diaphragm electrolysis cell, electrolytically oxidized in the anode chamber in the presence of hydrogen peroxide and iron ions, and then introduced into a cathode chamber of the diaphragm electrolysis cell for neutralization. A method for removing COD-containing water, comprising: 2. The method of removing COD-containing water according to claim 1, wherein the material of the anode of the anode provided in the anode chamber is iron.