Electro Oxidation Process :

Electrooxidation is an electrochemical process in which oxidation reactions occur by applying an electric field between the anode and cathode. Electrooxidation can be defined as an electro chemical process which, by way of special, non-sacrificial electrodes we can obtain compounds capable of strongly oxidating the waste water we are treating.

Electro-oxidation (EO) is one of the most promising forefront technologies to remove pollutants from wastewater. Most of the available references have shown interesting results for biorefractory compounds, especially at laboratory scale. However, the continuous operation of an EO process has not been studied in detail, even less at pilot scale. The Electro Oxidation technology has been applied to treat an effluent from an Urban Waste Water Treatment plant.

Electrochemical oxidation is considered a robust technology and easy to use, for that reasons, it has been used for a diversity of wastewater treatment areas. The main advantages of this technology over other conventional treatments are as follows:

• Electron is the main reagent.
• A simple electrochemical cell is required in the process.
• Addition of chemicals is not required.
• The process is carried out at room temperature and atmospheric pressure.

The production of hydroxyl radicals during conductive diamond electrolysis of aqueous wastes is possible. Consequently, a very new class of oxidation processes, the electrochemical advanced oxidation processes (EAOP) were discovered. In the direct electro oxidation, pollutants in the bulk of the wastewater must reach the electrode surface and the oxidation reaction takes places once they are adsorbed onto this surface. Thus, the electrode materials influence the selectivity and efficiency of the oxidation process and mass transfer becomes a very important process.

Advanced Electro Oxidation Process

The electrochemical Advanced Oxidation Process (AOP) allows treating process and waste water, without adding other chemicals. The process is based on an electrolytic cell, wherein a voltage adapted to the problem is applied between two electrodes set in the fluid. This voltage will generate a corresponding electric current invoking several electrochemical processes and thereby destroying or modifying unwanted substances in the electrolyte. Mainly carbon dioxide is formed.

Additionally enduring (long-term) disinfection effects can be achieved if chloride is present in the water forming oxychloride. Oxychloride is a very powerful disinfectant. Especially in the after-treatment of wastewater this effect is desired.

Features of Electro Oxidation:

• Electro Oxidation process can be used as a standalone treatment or complementary treatment for treating high COD wastewater.
• Electro Oxidation can be implemented as a batch process or a continuous process based on the requirement of the industry.
• Very small footprint requirement.
• Zero Sludge Process as compared to other waste water treatment processes.
• In-situ generation of ozone, free radicals, oxidizing chlorine compounds etc. is unique to electro oxidation process.
• No requirement of any addition of chemicals, hence storage and handling of hazardous chemicals is completely eliminated.
• It is an environmentally friendly waste water treatment technology using only electricity.

Electrooxidation-ozonation is an efficient process for the treatment of different kinds of wastewater, since there is always a large reduction in COD, color, and turbidity, conductivity and BOD. The coupled process always has a superior performance compared with the application of separated processes. It is also noteworthy to mention that the coupled process is green, as it does not produce residual sludge. This coupled process has the potential to be used in wastewater in which other processes do not work well, including those with recalcitrant pollutants.

The electrochemical generation of oxidants used for the recovery or treatment of wastewater from industrial plants by electrochemical oxidation processes is playing an ever increasing role due to their reliable operating conditions and ease of handling. The mechanism of the electrochemical process treating dyeing wastewater is making use of electrolytic oxidation, electrolytic reduction, electrocoagulation or electrolytic floating destruct the structure or the existence state to make it bleached. It has the advantages of small devices, small area covering, operation and management easily, higher COD removal rate and good bleaching effect, but the precipitation and the consumption of electrode material is great, and the operating cost is high. The traditional electrochemical methods can be divided into power flocculation, electrical float, electro-oxidation, micro-electrolysis and the electrolysis method. With the development of electrochemical technologies and the appearing of a variety of high efficiency reactor, the cost of treatment will decrease largely. Electro-catalytic advanced  oxidation process (AEOP) is a new advanced oxidation technology developed recently. Because of its high efficiency, easy operation, and environmental friendliness, it has attracted the attention of researchers. Under normal temperature and pressure, it can produce hydroxyl radicals directly or indirectly through the reactions in the catalytic activity electrode, thus the degradation of the difficultly biodegradable pollutants is effective. It is one of the main directions in future research.

BENEFITS OF ELECTRO OXIDATION (EO) FOR TEXTILE WASTEWATER TREATMENT

Physicochemical treatment methods are not preferred generally, for the treatment of such type of dye containing effluents due to expensive chemical coagulants, adsorbents, membranes fouling and production of large volume of secondary pollutants. Whereas, non-biodegradability of reactive dyes and high energy requirement, limits the use of biological methods for the treatment of dye containing wastewater. These shortcomings i.e. large volume of secondary pollutants generation and non-biodegradability of dye bearing wastewater can be overcome by the use of electro oxidation (EO) process. Therefore, EO does not require adding large amount of chemicals to wastewater, as in the case of chemical oxidation, with no generation of secondary pollutants.