Wastewater treatment technology include sedimentation, filtration, flocculation, biodegradation, electrolytic oxidation and other methods. When electrolysis is used to treat wastewater, the electrode not only plays the role of transmitting current, but also catalyzes the oxidative degradation of organic matter without causing secondary pollution. It is called green water treatment technology. For wastewater that cannot be treated by biodegradation, electrolytic oxidation often has a significant effect. Therefore, electrolytic water treatment technology has become a research hotspot in water treatment technology and has been more and more widely used. The basic principle of electrolysis water treatment technology is to cause pollutants to undergo direct electrochemical reaction or indirect electrochemical conversion on the electrode, that is, direct electrolysis or indirect electrolysis.
(1) Direct electrolysis Direct electrolysis means that pollutants are directly oxidized or reduced on the electrodes and removed from wastewater. Direct electrolysis can be divided into anode process and cathode process. In the anode process, the pollutants are oxidized on the anode surface and converted into less toxic substances or substances that are easily biodegradable, and even inorganic organic substances, so as to achieve the purpose of reducing and removing pollutants. The cathode process is the reduction and removal of pollutants on the cathode surface, which is mainly used for the reduction and dehalogenation of halogenated hydrocarbons and the recovery of heavy metals.
(2) Indirect electrolysis Indirect electrolysis refers to the use of electrochemically generated redox substances as reactants or catalysts to convert pollutants into less toxic substances. Indirect electrolysis is divided into reversible process and irreversible process. Reversible process (medium electrochemical oxidation) refers to the electrochemical regeneration and recycling of redox compounds in the electrolysis process. Irreversible process refers to the use of substances produced by irreversible electrochemical reactions, such as strong oxidizing chlorate, hypochlorite, H2O2 and O3 and other processes to oxidize organic matter. It can also use electrochemical reactions to produce strong oxidizing intermediates , Including solvated electrons, HO,; HO2, O2- and other free radicals.
The new technology of water treatment by electrolysis has the advantages of no need to add chemical agents, small equipment size, small footprint, and no secondary pollution. It has been used to treat waste water containing hydrocarbons, alcohols, aldehydes, ethers, phenols and other organic pollution. The removal of COD mainly depends on the oxidation reaction on the anode surface, which directly oxidizes and degrades the organic matter on the anode surface, so that the organic matter in the sewage is converted directly or indirectly into CO2 and water through electrochemical conversion. The anode potential must be higher than the decomposition potential of organic matter, so two competing reactions of organic matter oxidation and oxygen evolution occur on the anode. The shape of the anode is available in various forms such as plate type, tube type, net type, etc., and the quality is reliable. The titanium matrix can be reused.
Successful applications: electroplating wastewater, coking wastewater, organic wastewater, ammonia nitrogen wastewater, printing and dyeing wastewater, garbage seepage, fecal wastewater, oily wastewater, cyanide wastewater, oilfield reinjection water, recycling metal wastewater, hospital wastewater, catering wastewater treatment, etc. New environmental protection technology-electrocatalytic electrolysis.