Sterilization of E. coli by means of pulsed streamer discharges in water using a continuous flow system

Abstract

Pulsed streamer discharges in water using a wire to cylinder electrode contained in 42 mm inner glass tube were investigated with respect to its spatial expanse associated with voltage waveforms. The discharge reactor with a continuous flow system was employed to sterilize E. coli suspended in saline water (10 mS/m). The discharge electrode consisted of a 0.1 mm diameter metal wire for the high voltage and a mesh cylinder for the ground electrode. Tens of disk-shape discharges emerged from the wire electrode and propagated toward the cylinder as long as the voltage lasts. The spatial expanse of the discharge was proportional to the cube of pulse duration and to the amplitude of the voltage. The sterilization experiment showed that the survival ratio of bacteria over discharges was proportional to the average number of the exposure to the discharges while in the reactor. The minimum ratio of survival bacteria was only 15% under 130 exposures, which corresponds to the energy expenditure of 35 J/ml.