2018 Volume 61 Issue 3 Pages 113-118
Plasma water treatment for organic decomposition is promising as an environment-friendly treatment technique because organic compounds are decomposed by chemically reactive OH radicals produced by the plasma without producing by-products. In this paper, water treatment using microwave plasmas is discussed, especially focusing on the pressure control during the process. Using a microwave plasma source where a slot is immersed in the water, improvement of the plasma ignition is shown at reduced pressure condition. As an alternative technique to enhance the plasma production ultrasonic wave is superposed to the microwave plasma. By synchronizing the ultrasonic wave and the pulsed microwave, enhancement of the organic compound decomposition is realized. As a new treatment technique of flowing water by the plasma, a microwave plasma source that utilizes a nozzle to produce the reduced pressure is developed. High efficiency organic decomposition is demonstrated under flowing water condition.