Investigation of microbial cell inactivation using plasma discharge treatment of liquids

Summary form only given, as follows. A pulsed plasma discharge system has been employed to allow the inactivation of pathogenic microorganisms in liquids. Microbial cell inactivation is achieved through the application of high voltage pulses to test liquids sparged with a treatment gas. Upon application of high voltage pulses to the sparged test liquid, partial discharge activity results. The partial discharge activity can also lead to complete breakdown of the gas and liquid medium. Antimicrobial ultraviolet light photons and ozone are formed, along with the formation of other potent species such as free radicals and electrons, which facilitate microbial inactivation in the test liquid. Substantial reductions in microbial cell population have been achieved using this system, but much is unknown regarding the inactivation kinetics of the plasma process. Results are presented that demonstrate the effect on microbial cell inactivation through the use of varying pulse repetition rates and input charging voltages. In addition, results are also presented on the viability of using a sparging gas ioniser in the discharge process in an attempt to increase antimicrobial species such as ozone and free radicals, thereby increasing the plasma discharge treatment efficiency.