Water Treatment by Atmospheric Discharge Produced with Nanosecond Pulsed Power

Water treatment is one of the industrial applications taking advantage of pulsed power. Electrical discharges produced in atmosphere involve a variety of high energy phenomena, which would be effective to the water treatment. The water treatment system consisting of coaxial cylinder reactor was constructed. The reactor consists of an inner electrode of a wire and an outer cylinder electrode and a water layer is formed on the inner surface of the cylinder. In applying the nanosecond pulsed power on the wire electrode, streamer discharges grow from the wire to the water layer. Decolorization of indigo carmine solution was attempted by using the system. The indigo carmine solution was decolorized in 8 minutes at pulse repetition rate of 50 pps. Decolorization ratio is improved by increasing pulse repetition rate and charging voltage of 3.2 kV is more effective to decolorization than that of 2.78 kV. The highest decolorization efficiency was 5.6 J/mg when oxygen gas was filled in the reactor.