Enhancement of continuous bubbles by non-thermal plasma for water treatment

Non-thermal plasma is generated by excitation of the electron in gas or liquid medium. This technique has been applied to many industrial fields, especially for water treatment, because of the byproducts generated electrochemically by high-voltage discharge. Simultaneous production of plasma and bubbles is one of the methods to efficiently reduce the required energy for water treatment. The flow rate of injected gas and supplied electric energy are important parameters. In this study, the characteristics of the continuously generated bubbles with non-thermal plasma discahrge were investigated by experiment. The behavior of bubbles with and without discharge was analyzed by image processing. To verify the water treatment yield of bubbles with plasma generating byproducts, the decomposition of organic dye was investigated and analyzed. Due to the reduction of the surface tension of the interface, the volume of bubble with discharge showed shorter departure time with smaller volume. Bubbles with plasma discharge have faster bubble rising velocity, due to more spherical shape, which lowers the possibility of coalescence between bubbles, and is more effective for water treatment. The higher coalescence probability caused by increased Reynolds number resulted in the reduction of water treatment yield.