KR20040057008A - Electrolytic waste treatment system - Google Patents

Abstract

PURPOSE: Provided is an electrochemical wastewater treating device which efficiently induces an oxidation and reduction reaction at low temperature under atmospheric pressure. CONSTITUTION: The device comprises a plurality of unit electrolytic cell(3) consisting of an anode chamber where a highly concentrated organic compound is oxidized to be completely decomposed, a cathode chamber where wastewater is reduced to harmless gases and a cation exchange membrane(90) separating the anode chamber and the cathode chamber.

Description

Electrochemical waste treatment system

In general, various industrial wastewater treatment methods include physical treatment using plasma, sedimentation and filtration, chemical treatment by adding chemicals, chemical treatment to treat wastewater at high temperature and high pressure near a critical point, There is a biological treatment method for decomposing organic matter using microorganisms.

Such a conventional wastewater treatment device does not meet the water quality standards in the case of high concentration of malignant wastewater, and even if the treatment is possible, the installation cost is expensive, and the installation scale is large, requiring a large installation area, and operating system. It is a very complex feature. In the case of a company trying to install the wastewater treatment device, there was a problem that the treatment device cannot operate normally due to the inexperienced operation due to the lack of expertise due to the burden on the operation and installation cost and the complicated installation structure.

In view of these points, an electrolysis method using electricity has been attempted. The electrolysis method treats wastewater by using redox reaction of electrode in electrolytic cell equipped with electrode plate of cathode and anode. It is effective to remove oil, inorganic pollutants, organic pollutants and colloidal pollutants. It has been known that there is an advantage that can treat a high concentration of contaminated wastewater. Such electrochemical technology can be classified into three categories.

One of them is the method of using electrolytic coagulation. When current is applied to the anode, the components of the electrode are eluted, and the components of the eluate and the waste water are aggregated to treat the waste water. Such methods include Korean Patent Application No. 2020020017901 (Waste water treatment apparatus having an electric condensation treatment unit and a sterilizing water supply unit), 1020020009601 (Water treatment apparatus using first-class technology electrolytic flotation method and its operating method) , 1020010025398 (Kwon, Youngdae Univ. Electric Waste Reactor, Wastewater Treatment System), 1020000071373 (ENI Water Solution Co., Ltd. Electrochemical Aggregator with Dual Structure Electrode and Electrolytic Treatment System with Coagulator), 1020000071371 Electrochemical agglomerator with dual structure electrode and electrolytic treatment system equipped with this agglomerate, 1020000064037 (Veumseong NC Co.,. Disposal Method), 1020000049758 1020020341818 (Waste Oil Separation Device in Conductive Solution Using Charge Aggregation, Pohang Institute of Industrial Science and Technology), 1019990058754 And the like if electrolytic yiaentek wastewater flocculation unit), 1019990052468 (Co. passages environment electrolytic coagulation system),

The other method is an electrode using an electrode insoluble electrode that does not elute the electrode. The method of treating wastewater using an oxidation reaction of an insoluble electrode includes Korean Patent Application No. 020020023947 (Techwin O, advanced treatment and sterilization treatment). 2020020015636 (Wastewater Treatment System Using Icheon Thermal Electrolysis), 1019940005599 (Electrolytic Wastewater Treatment System and Method), 1019940004217 (Annam Environment Co., Ltd.) Electrolytic Oxidation of Degradable Industrial Wastewater), 2020020007808 (Wastewater Treatment System Using Icheon Thermal Electrolysis), 2020010022697 (Electrolysis System for Icheon Thermal Wastewater Treatment), 1020010021258 (Nagara Kunitake Wastewater Treatment System), 1020010015490 (Cho Yongdeok Electrolysis Method) Wastewater Treatment Method), 2020010007140 (Wastewater Treatment Facility by i-Su Electrolysis), 2020010 003493 (Yang Jae-chun wastewater treatment system), 1020010001766 (Veumseong NC Co., Ltd .. wastewater treatment method using electrolysis), etc. Another method is to combine the electrochemical device and other oxidizer treatment. 1020010001743 (degradable water treatment system using electrolysis and biofilm), 2020010000806 (degradable water treatment system using electrolysis and biofilm), 1020000057146 (high-grade wastewater treatment method using flocculation and electrolytic principle).

However, the non-diaphragm electrolysis without a diaphragm between the anode and the cathode causes oxidation and reduction reactions at the anode and cathode simultaneously in the electrolyzer, so that the wastewater is recovered from the cathode by the reduction reaction even if the wastewater is decomposed by the oxidation reaction. Reduced efficiency is reduced, and thus there is a problem that the wastewater treatment efficiency is low, and the wastewater treatment takes a long time.

Therefore, wastewater containing malignant high concentration waste and total nitrogen such as explosives, pesticides, hospital waste, etc. has a problem that the device is large, complicated in composition, expensive in operation cost and equipment cost due to low efficiency including non-diaphragm electrochemical conventional method. In the case of a system with high processing efficiency, the device's operating conditions are high temperature and high pressure, so that the components of the equipment are special, so the equipment cost is very expensive.

In order to solve the above problems, the present invention devised an electrochemical reaction cell for efficiently inducing oxidation and reduction reactions at low temperature and atmospheric pressure, and low operating cost and equipment cost, and very compact wastewater treatment system. The purpose is to provide.

FIG. 1 Unit Electrochemical Wastewater Treatment Cell

2. Principle of Electrochemical Wastewater Treatment

Fig. 3 Drawing of the anode chamber

FIG. 4 Assembly Diagram of Electrolytic Stack for Treating Large Capacity Wastewater

How to treat malignant organic wastewater of high concentration

6 is a method for treating high concentration nitrate concentration wastewater of 1,000 ppm or more

FIG. 7 Treatment of High Concentration Nitrogen Nitrogen and Ammonia Nitrogen Wastewater

The present invention is a wastewater treatment apparatus for continuously treating wastewater using an electrode. The electrolysis apparatus of the present invention uses an electrochemical cell composed of an anode reaction chamber and a cathode reaction chamber with a diaphragm interposed therebetween as a basic unit process.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 is a perspective view showing a unit electrochemical wastewater treatment cell according to the present invention.

The cell 3 has a structure as shown in the drawing, in which the ion exchange membrane 90 is divided into an anode chamber and a cathode chamber on both sides, and the anode chamber, the cathode chamber, and the ion exchange membrane are the basis of the unit electrochemical wastewater cell. do.

The anode chamber is located on the right side of the membrane 90 based on Fig. 1-A, and a plurality of electrode conductors 122 made of titanium (Ti) are disposed on the right side of the membrane 90, and ends of these electrode conductors 122 are disposed. The anode 20 in the form of a mesh is welded. In addition, the anolyte supply pipe 120 communicates with the lower part of the anode chamber, and the anolyte discharge pipe 128 is discharged with the anolyte solution and the reaction gas mixed therein.

The applied electric energy is supplied from the outer wall 130 of the anode chamber to the anode 20 through the electric conductor 122. The electric conductor 122 is a plate welded to the outer wall of the anode chamber, and the plate has a circular electrolyte passage 124 of a predetermined size, and serves as a current conductor at the same time as the electrolyte mixing function.

The anode 20 of the present invention uses a catalyst suitable for this so that the reaction of the anode chamber can occur smoothly. The anode 20 mainly uses a numerically stable electrode (DSA) using an oxide such as iridium (Ir) or ruthenium (Ru), which is a platinum plating or oxygen generating catalyst, on a titanium (Ti) substrate.

The electrical conductor 122 is formed by coating an oxide such as iridium (Ir) or ruthenium (Ru), which is a platinum plating or an oxygen generating catalyst, on a titanium (Ti) substrate such as titanium or the anode 20.

The cathode chamber is located on the left side of the membrane 90 with reference to FIG. 1, and a plurality of electrode conductors 102 made of steel or nickel are installed, and a net cathode 10 is formed at the ends of the plurality of electrode conductors 102. This is welded. The catholyte supply pipe 110 communicates with the lower portion of the cathode chamber, and the catholyte discharge pipe 118 for discharging the catholyte is communicated with the upper portion of the cathode chamber.

The added electrical energy moves from the anode 10 to the cathode chamber outer wall 230 through the cation exchange membrane 90, the cathode 10, and the electrical conductor 102.

The electrical conductor 102 is a plate welded to the outer wall of the cathode chamber, and the plate has a predetermined size circular electrolyte passage 112 to have a mixing function of the electrolyte as in the case of the anode chamber, and at the same time serves as a current conductor.

The negative electrode 10 mainly uses hydrogen generating catalyst platinum and oxides thereof in addition to stainless steel, nickel, mild steel, and titanium substrates. The material of the electrical conductor 102 is preferably the same as the material of the cathode.

The unit cell 3 of the present invention is pressure-coupled using the bolt and nut 192 as shown in FIG. Wastewater treatment principle in the electrolytic cell of the present invention is shown in FIG.

That is, ions of the anolyte supplied to the anode chamber are separated by the current flowing through the anode 20, and ions pass through the ion exchange membrane 90 to move into the cathode reaction chamber. The migrated ions are reduced by the current flowing to the cathode 10. In this case, the oxidation reaction (7 8) occurs, the gas generated by the reaction exits the anode chamber through the anolyte discharge pipe (4), the reducing material and hydrogen gas of the cathode chamber exits the cathode chamber through the catholyte discharge pipe (3). 3 is a drawing of the anode chamber, in which the symbols in the drawings and the symbols in FIG. 1 coincide and have the same function. The anode gasket 37 in close contact with the inside of the anode chamber and the flange face 27 of the anode chamber and the ion exchange membrane 90 adheres closely to the inside of the cathode chamber and the flange face of the cathode chamber and the ion exchange membrane 90. The cathode gasket 39 seals the cathode chamber. Both the anode gasket 37 and the cathode gasket 39 are formed to a size almost similar to that of the cell unit 3.

4 is an example of the electrolysis stack 100 in which a plurality of unit electrochemical cells (b in FIG. 1) are installed to treat a large amount of wastewater, and the unit cells 3 are arranged in close contact for a large amount of wastewater treatment. At both ends of the plurality of cells 3, plates 5 for closely contacting the plurality of cells are arranged. The plate 5 is here supported by a guide rod or a pressing spring 97 or the like.

Through the anolyte supply pipe 21 and the catholyte supply pipe 33, the unit cells are supplied into the anode cell and the cathode chamber of each unit cell. The supplied waste water is interposed between the anode chamber and the cathode chamber with an ion exchange membrane disposed between the anode chamber and the oxidation chamber in the anode chamber and the electrolysis reaction of the reduction reaction in the cathode chamber to treat the wastewater. And hydrogen are collected in the anolyte passage 500 and the catholyte passage 400 and then transferred to the next process.

5 relates to a method for treating high concentrations of malignant organic wastewater. Here, the treatable wastewater refers to general industrial wastewater, pesticides, pharmaceuticals, nuclear power plant waste, military waste water, explosives, and engine oil.

The malignant organic wastewater 1 constantly supplied from the outside is collected in the wastewater storage tank 400 and supplied to the anode chamber of the electrolytic stack through the pump 600 in a predetermined amount. Depending on the wastewater type, the catalyst 5 may be used to promote the electrochemical reaction. As the catalyst mainly used, silver ions and the like are preferable.

At this time, when a current is applied from the DC power supply unit 900 to the anode chamber, the wastewater is completely oxidized by the electrochemical oxidation reaction, converted into carbon dioxide (2), and discharged to the outside of the electrolytic stack. The unreacted electrolyte is separated from the phase separator 200, and partly circulated to the wastewater storage tank 400, and partly discharged. For example, when wastewater containing high concentration of benzene (10% by weight) is supplied to the anode chamber, it is completely decomposed in the anode chamber as shown in Equation 1 below.

C6H6 + 12H2O 6CO2 + 3OH- + 3Oe Equation 1

At this time, the anode of the anode chamber is preferably a titanium electrode coated with platinum.

Supplying electrolyte (acid or alkali) with excellent conductivity to the cathode chamber controls the voltage of the electrolytic stack, removes hydrogen (4) produced by the reduction reaction from the cathode in the phase separator 300 and discharges it out of the process. Circulates back to the electrolyte tank 500.

At this time, a titanium electrode is preferable as a cathode of a suitable cathode chamber.

As the separator of the anode chamber and the cathode chamber, Dupont's Nafion 324, etc. of the United States may be used.

The operating condition of the current density of the electrolytic stack is 0.5 A / cm 2, the pressure is normal pressure, and the temperature is preferably 40 C or higher.

6 relates to a method for treating high concentration of nitrate nitrogen wastewater of 1,000 ppm or more. Wastewater 15 containing nitrate nitrogen constantly supplied from the outside is collected in the wastewater storage tank 500 and supplied to the cathode chamber of the electrolytic stack via a pump 700 in a predetermined amount. In this case, when a current is applied from the DC power supply unit 900 to the cathode chamber, nitrate nitrogen is completely reduced by the electrochemical reduction reaction, converted to nitrogen 14, and discharged to the outside of the electrolytic stack 100. The unreacted electrolyte is separated from the phase separator 300 to circulate a part of the waste water storage tank 500, and part of the discharge condition 13 is discharged. In the cathode chamber, nitrate nitrogen is completely decomposed as shown in Equations 2 and 3 below.

NO3- + H2O + 2e NO2- + 3OH- Formula 2

NO2- + 2H2O + 3e 1 / 2N2 + 4OH- Formula 3

At this time, the cathode of the cathode chamber is preferably a titanium electrode coated with platinum.

Supplying electrolyte (acid or alkali) with excellent conductivity to the anode chamber controls the voltage of the electrolytic stack, removes oxygen (12) produced by the oxidation reaction at the anode from the phase separator 200 and discharges it out of the process. Circulates back to the electrolyte tank 400. At this time, when the concentration of the electrolyte drops, the electrolyte 11 is supplied from the outside. At this time, the cathode of the anode chamber is preferably a titanium electrode coated with platinum-iridium.

As the separator of the anode chamber and the cathode chamber, Dupont's Nafion 324, etc. of the United States may be used.

The operating conditions of the current density of the electrolytic stack are 0.4 A / cm < 2 >

7 relates to a method for treating high concentrations of nitrate and ammonia nitrogen wastewater.

The wastewater 21 containing nitrate nitrogen and ammonia nitrogen, which are constantly supplied from the outside, is collected in the wastewater storage tank 500 and supplied to the cathode chamber of the electrolytic stack via a pump 700 in a predetermined amount. In this case, when a current is applied from the DC power supply unit 900 to the cathode chamber, nitrate nitrogen is completely reduced by the electrochemical reduction reaction, converted to nitrogen 14, and discharged to the outside of the electrolytic stack 100. The unreacted electrolyte is separated from the phase separator 300 and circulated in part to the wastewater storage tank 500 and the anolyte storage tank 400. In the cathode chamber, nitrate nitrogen is completely decomposed as shown in Equation 4.

NO3- + 2H2O + 5e 1 / 2N2 + 7OH- Equation 4

Some nitrate nitrogen is converted to ammonia nitrogen as shown in Equation 5 below.

_{^{NO3 - + 6H 2 O + 8e}} - → NH 3 + 9OH - formula 5

At this time, the cathode of the cathode chamber is preferably a titanium electrode coated with platinum.

In the anode chamber, salt 22 for promoting oxidation of ammonia is added to the anode of the electrolytic stack by adding salt to maintain a salt concentration of the anolyte tank of 0.1 wt%. At the anode of the anode chamber, chlorine ions are generated by oxidation of chlorine ions and dissolution in water as shown in Equations 6 and 7, and ammonia is removed by the reaction of chlorine and ammonia ions as shown in Equation 8.

2Cl ^- → Cl ₂ + 2e ^- Formula 6

Cl ₂ + H ₂ O → HClO + HCl

2NH ₃ + 3HClO → N ₂ ↑ + 3HCl + 3H ₂ O Equation 8

The nitrogen (23) generated at this time is removed from the phase separator 200 and then discharged to the outside of the process, and the anolyte is circulated back to the electrolyte tank 400. At this time, a titanium electrode coated with platinum-iridium is preferable as the anode and the cathode. As the separator of the anode chamber and the cathode chamber, DuPont Sanafion 324 of the United States may be used. The front wheel density operation condition of the electrolytic stack is preferably 0.1 A / cm < 2 >

It is possible to effectively treat high concentration organic wastewater and nitrogen containing wastewater which was not desired by the conventional technology, contributing to the environmental industry due to low cost of equipment and operation cost.

Claims (1)

An electrochemical unit cell consisting of a cathode chamber containing an anode, a cathode chamber containing a cathode, and a cation exchange membrane separating them is installed continuously to treat a large amount of wastewater, and the anode chamber induces an oxidation reaction of a high concentration of organic compounds to completely decompose it. In the cathode chamber, an electrochemical system that converts wastewater that needs to be reduced to a harmless gas