Electro-oxidation for Wastewater Treatment
Electro-oxidation (EO), also known as Electro Chemical Oxidation, is a relatively recent discovery along similar lines as electro-coagulation where anodic oxidation on the anode surface is employed in place of direct chemical/photochemical oxidation.
Similarly to the conventional oxidation process, common oxidizing agents are the hydroxyl radical, hydrogen peroxide, chlorine, and ozone.
Typically, the available electro-oxidation processes are effective in degrading refractory pollutants that are difficult to degrade otherwise, such as PFAS. These mainly include toxic compounds and ammoniacal nitrogen which are a great issue in industrial wastewater treatment applications.
An alternate variation of electrooxidation involves only the generation of an oxidizing species using the electrochemical route followed by direct oxidation by the generated oxidizing agents. Thus, the basic mechanism is the same while the location and the form of the oxidation reaction are slightly different.
Electro-oxidation Test Equipment Introduction
In electro-oxidation, the design of the electrochemical cell, selection of electrodes, operational parameters, and cost of power are critical parameters for the application of electro-oxidation in wastewater treatment.
Furthermore, the efficiency of the Electro-oxidation (EO) process in pollutants removal largely depends on cell configuration, electrode material, electrolyte composition and other experimental parameters, such as current density or the temperature of the treated water.
For these reasons at YASA ET we designed a test equipment that is fully customizable, from the electro-oxidation cell size to the electrode materials.
Electro-oxidation (EO) Process Working Principle for Wastewater Treatment
Electrooxidation (EO) or Electro-oxidation process for wastewater treatment involves the application of an external source of energy into an electrochemical cell that contains one or more pairs of electrodes. At the cathode, a reduction reaction occurs, and the oxidation reaction takes place at the anode.
Electrooxidation (EO) can eliminate contaminants at the interface of the anode/aqueous solution (direct oxidation), and via anodically generated intermediates e.g. reactive oxygen species like hydroxyl radicals (HO•) and active chlorine species (indirect oxidation) from the waste effluent.
When an energy input and sufficient supporting electrolyte are provided to the system, strong oxidizing species are formed, which interact with the contaminants and degrade them. The refractory compounds are thus converted into reaction intermediates and, ultimately, into water and CO2 by complete mineralization.
Hydroxyl radicals are highly reactive oxidants that can react with nearly all organic contaminants and eventually mineralize them to CO2 and H2O non-selectively in ambient pressure and atmospheric temperature.
Electrodes for Electro-oxidation (EO) in Wastewater Treatment Applications | MMO or DSA Electrode
Mixed metal oxide (MMO) electrodes, also called Dimensionally Stable Anodes (DSA), are devices with high conductivity and corrosion resistance for use as anodes in Electro-oxidation wastewater treatment applications. They are made by coating a substrate, such as pure titanium plate or expanded mesh, with several kinds of metal oxides. One oxide is usually RuO2, IrO2, or PtO2, which conducts electricity and catalyzes the desired reaction.
These kinds of electrodes are very popular in electrochemical process industry, because they are very effective in promoting both chlorine and oxygen evolution. In the case of wastewater treatment, they provide low current efficiency, because they favour the competitive reaction of oxygen evolution.
Due to their ability to promote chlorine evolution reaction, dimensionally stable anodes are the most common choice for processes relying on mediated oxidation mechanism, especially in the case of chlorine and hypochlorite production.