Effects of plasma activated species produced by a surface micro-discharge device on growth inhibition of cyanobacteria

Abstract

Akind of surface micro-discharge (SMD) device is developed to produce the reactive oxygen/nitrogen species (RONS). According to the yield of ozone and nitrides which is heavily dependent on the applied discharging voltages, the discharges of this SMD can be categorized into three modes, i.e. ozone dominating, nitrogen oxides dominating and transition modes. RONS airflow (or air plasma flow) is led into cyanobacteria solution. Not only ozone but also thep H decrease caused by nitrogen oxides can effectively inhibit the growth and reproduction of cyanobacteria. The pH threshold below which the acidity takes effect is 6.8. In the transition mode, when the solution is alkaline ozone plays a major role, and when the solution is converted to acidic the effect of pH decrease catches up even more than ozone. For this SMD device, direct RONS airflow with an applied voltage range of 20 to 30 kV and a time period of 8 to 11-min treatment is optimal to successfully inhibit the growth and reproduction of cyanobacteria, without obvious changes of environmental acidity.