Non-thermal plasma for decontamination of bacteria trapped in particulate matter filters: plasma source characteristics and antibacterial potential

Abstract

The aims of this study encompass the characterization of process parameters and the antimicrobial potential during operation of a novel non-thermal plasma (NTP) source in a duct system containing a particulate matter (PM) filter thus mimicking the interior of an air purifier. Simulating conditions of a long-term operation scenario, in which bacterial aerosols in indoor environments accumulate on PM filters, the filter surfaces were artificially inoculated with Escherichia coli (E. coli) and exposed to an air stream enriched with reactive species. Electrical power consumption, key plasma parameters, volume flow and air flow velocity, reactive gas species concentrations as well as inactivation rates of E. coli were assessed. The NTP operated at a gas temperature close to ambient air temperature and featured a mean electron energy of 9.4 eV and an electron density of 1∙1019 m−3. Ozone was found to be the dominating reactive gas species with concentrations of approx. 10 ppm in close vicinity to the PM filters. An inactivation rate of 99.96 % could be observed after exposure of the PM filters to the gas stream for 15 min. This inactivation efficiency appears very competitive in combating realistic bacterial aerosol concentrations in indoor environments.