Plasma-assisted advanced oxidation process by a multi-hole dielectric barrier discharge in water and its application to wastewater treatment

Advanced oxidation process (AOP) is a promising technology to decolorize and reduce organic contaminants in water. It is carried out using hydroxyl radicals (•OH) with an oxidizing potential of 2.80 V. Non-thermal plasma can directly generate •OH while maintaining a low temperature, and O3, H2O2, and UV light are also generated; these are necessary for AOP. In this study, we developed a multi-hole dielectric barrier discharge (DBD) system capable of generating radicals and active species in water for assisting AOP. We confirmed the optimized operating conditions based on critical parameters, including electrical and optical properties and O3 concentration. Furthermore, we described the plasma-based AOP through experimental results. We performed wastewater treatment using the multi-hole DBD: turbidity, BOD, and COD, were reduced by 60%, 40%, and 60%, respectively, after 20 min of treatment. Finally, 99.99% of Escherichia coli were eliminated after plasma treatment.