JP3400628B2 - Method of removing COD component - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for effectively removing hardly biodegradable COD (for example, a yellow-brown chromaticity component in biologically treated human wastewater) in various wastewaters. And a technology that can be oxidatively decomposed into carbon dioxide and water. [0002] Conventionally, as a method of oxidatively decomposing COD, there are known an ultraviolet-hydrogen peroxide combined method, an ultraviolet-photocatalyst combined method, an ultraviolet-ozone oxidation combined method and an ozone-hydrogen peroxide combined method. However, in each case, the COD removal rate was inferior in spite of the necessity of high treatment cost, and there was no practical use except for the ultrapure water production field. [0003] The present invention provides a new technique capable of removing COD of wastewater at a high removal rate at a practical cost. SUMMARY OF THE INVENTION The present invention provides a method for supplying COD-containing water to a cathode compartment of a diaphragm electrolysis tank, guiding the COD-containing water to an anode compartment of a diaphragm electrolysis tank, and performing electrolytic oxidation while supplying ozone. It is a method characterized by the following. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure and operation of the present invention will be described in detail with reference to FIG. Raw water 1 is supplied to cathode chamber 3 of diaphragm electrolyzer 2
To supply. The electrode is preferably a platinum-plated titanium electrode for both the cathode and the anode. The diaphragm 8 is made of an organic microfiltration membrane (MF)
Membrane) is preferred. Cathode chamber 3 in which water is electrolyzed to generate hydroxyl ions by the following electrochemical reaction in cathode chamber 3
Is raised to about 10-11. H ₂ O + e ⁻ → １ ／ H ₂ + OH ⁻ Next, the high-pH cathode chamber effluent 4 is guided to the anode chamber 5, and electrolytic oxidation is performed while supplying ozone 6. As a result, the anode chamber 5
Electrolytic oxidation reaction, high pH ozone oxidation reaction (COD
The ozone oxidation reaction is accelerated at a high pH), and a complex reaction of the chlorine oxidation reaction proceeds, whereby COD is decomposed and removed to a high degree, and treated water 7 is obtained. One of the reasons why a high removal rate of COD is obtained is that when ozone is supplied to the anode chamber while electrolytic oxidation is performed on the diaphragm, a hydroxyl radical having a strong oxidizing action is generated from the ozone at the anode interface by an electrochemical reaction. I think it is. Even if ozone is supplied without performing electrolysis, COD is hardly removed. Electrolysis without supplying ozone is more effective than the ozone alone method, but the COD removal effect is considerably inferior to the method of the present invention. [0006] Hereinafter, a verification test of the present invention was carried out under the conditions shown in Table 2 by subjecting sewage biologically treated water to membrane separation using a UF membrane according to the process shown in FIG. 1 (average water quality is shown in Table 1). Performed for months. Table 1 Appearance Beer-like yellow water temperature 32 degree pH 7.2 SS 0 mg / l BOD 8 mg / l COD 142 mg / l Table 2 Raw water supply to the cathode chamber of the diaphragm cell 5 l / d Cathode chamber volume 0 0.5 l Anode chamber capacity 0.5 l Electrode area 60 cm ² Current 35 mA Voltage 6 V Ozone addition amount 120 mg / l Table 3 shows the quality of the treated water. The results of the ozone treatment alone and the electrolysis treatment alone are also shown. Table 3 The present invention ozone alone electrolysis alone pH 6.7 7.5 6.1 SS (mg / l) 0.50 BOD (mg / l) 2 8 3 COD (mg / l) 9.8 92 68 According to the present invention, the following effects can be obtained. 1. COD that cannot be biologically decomposed can be effectively removed by the combined ozone oxidation-diaphragm electrolytic method. 2. The effect of increasing the pH in the cathode chamber of the diaphragm electrolytic cell can be used to increase the efficiency of ozone oxidation. (COD ozone oxidation is high p
Promoted by H)

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows the structure of a diaphragm electrolysis tank used in the present invention. [Description of Signs] 1 COD-containing raw water 2 Diaphragm electrolytic cell 3 Cathode (cathode chamber) 4 Cathode chamber effluent 5 Anode (anode chamber) 6 Ozone 7 Treated water from which COD has been removed 8 Diaphragm

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-296992 (JP, A) JP-A-7-265862 (JP, A) JP-A-56-102987 (JP, A) JP-A-50- 153775 (JP, A) JP-A-60-28884 (JP, A) JP-A-4-197489 (JP, A) JP-A-6-182344 (JP, A) JP-A-49-118670 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C02F 1/461 C02F 1/78 ZAB

Claims (1)

(57) [Claim 1] COD-containing water is supplied to a cathode chamber of a diaphragm electrolysis tank, and then guided to an anode chamber of a diaphragm electrolysis tank, and electrolytic oxidation is performed while supplying ozone. And how.