Highly Efficient Electro-Fenton Process to treat High-Strength Wastewater
Organic compounds are the main pollutants in industrial wastewater and are released by many industries including the pharmaceutical and, petrochemical industries. This effluent poses a great risk to the environmental ecology and public health, and is resistant to conventional wastewater treatment.
Advanced Oxidation Processes (AOP), is a set of chemical reactions designed to degrade organic compounds though their oxidation by hydroxyl radicals. Traditional AOPs e.g. ozone, hydrogen peroxide (H2O2) require high amounts of expensive or hazardous reagents that are inconvenient to handle and store. Another AOP, Fenton reaction, requires non-recyclable soluble iron salts, which produce a large amount of iron oxide sludge, which in turn requires further separation and treatment.
Traditional AOPs are costly since a continuous input of expensive chemical reagents are required to maintain operations and the technically demanding pre-treatment of wastewater is also needed to ensure reliable performance. Given the costs, AOPs cannot individually handle a large amount of wastewater but are instead deployed in the final stage after primary and secondary treatment.
NUS is proposing an evolutionary, more efficient and cost effective electro-Fenton system.
This new AOP system uses innovative electrodes in its electrochemical variant of the Fenton process, in which the Fenton’s reagent is generated electrocatalytically and in-situ at the cathode of the reactor. The resultant hydroxyl radicals are very efficient for the advanced removal of persistent organic pollutants.
The system features a flexible, non-fragile, highly scalable and high performing cathode. It is more cost-efficient as the raw materials for its fabrication can be obtained commercially at low cost. Another advantage is that the cathode can be used to produce high amounts of H2O2 in-situ, which leads to faster degradation of organic compounds in the wastewater. Since iron electrodes are not employed in the system, no sludge is produced, eliminating the need for further costly separation and treatment. The process also allows quicker and up to two times higher degradation and mineralisation with lower energy consumption.