Influence of volume dielectric barrier discharge in argon and argon oxygen atmospheres on water and E. coli suspensions

Summary form only given. Water disinfection by plasma treatment is a highly interesting and important area of research. Furthermore, it is well known that plasma treatment of water results in acidification and generation of several chemical species. Both phenomena are part of complex plasma-liquid-interactions resulting in biological plasma activity. In this study non-stirred liquids (3 ml) in a lower shell of a cell culture dish have been treated by volume dielectric barrier discharge (volume-DBD) where the liquid is part of the electrode configuration. The plasma was ignited in pure argon atmosphere and argon with different oxygen admixtures between 1 and 5 %, respectively. For the experiments the vegetative bacterium E. coli was suspended in physiological saline solution to a concentration of 10⁷cfu ml^-1. Volume-DBD treatment times of E. coli suspensions have been varied between 15 s and 2 min. In all cases a >; 6-log inactivation was reached within 2 min. An influence of the percentage oxygen admixtures on the inactivation of suspended E. coli by volume-DBD treatment was shown. Treatment volumes of 3 ml distilled water under identical conditions resulted in pH decrease to a value of 3 within 30 min plasma treatment as well as increasing hydrogen peroxide concentrations which were detected by colorforming reaction and photometrical measurements. Based on these results, the influence of the oxygen admixtures to the argon atmosphere on distilled water and microorganism suspensions as well as the potential role of chemical species generated in the liquids are discussed.