Characteristics of microdischarge plasma jet in water and its application to water purification by bacterial inactivation

A microdischarge jet with a simple structure and low power consumption was developed, and we investigated its characteristics in a stable plasma jet in water, as well as the effect of the generated active radicals on bacterial disinfection. Sterilization experiments were performed using air and nitrogen plasma jets, and the sterilization rates of Escherichia coli were 99.99% and 66.7%, respectively. Active radicals such as H2O2, OH, NO, and NO2, which could contribute to sterilization, were produced when the plasma jet was generated in water. In particular, a comparison of the results obtained with the air- and nitrogen-plasma jets showed that the radical concentration was highly influenced by sterilization.