Sterilization of E. coli by pulsed spark discharge in continuous water circulation system

The application of plasma directly in water has been studied in recent years, because of its practical applications in water sterilization and decontamination. Although the mechanism is not fully understood, it is expected that the physical effects such as high electric field, Shockwaves and ultraviolet radiation, as well as reactive species produced from the discharge, significantly contribute in the inactivation of microorganisms. In this work, the results of recent experiments of sterilization of E. Coli with the use of pulsed spark discharge in a continuous water circulation system are presented. The main objective was to discuss the optimization of water solution sterilization by plasma for more realistic applications and its scalability for industrial use, taking into account the influence of energy density of plasma and various water parameters. An energy requirement of about 500 J/L was observed to achieve three log reduction of E. coli in the circulation system, which is higher than the energy requirement for batch process systems 1. Comparison of inactivation efficiencies determined at different initial bacterial concentration will be made. Also the influence of water parameters including conductivity, flow rate and total water volume et. al. will be discussed.