Air sterlization of spores with non-thermal plasma

Air quality control is important for facilities such as drug manufacturing plants and hospitals to prevent contaminations. The release of airborne biological weapons into the air circulation system is also a possible route of attack for military bases and large office buildings. Currently the most common method of air quality maintenance is the expensive HEPA filter system installed into the air circulation system. The HEPA filter requires routine maintenance and replacements of filters. But in dealing with deadly pathogens, even if the HEPA filter pores are small enough to filter out the pathogens, the filters do not inactivate them therefore threat is maintained. Also cost of the system and maintenance increases significantly with the level of air quality desired. Our focus is to create an air sterilization system using nonthermal plasma i.e. Dielectric Barrier Discharge (DBD) that will reduce the operating cost of maintaining a sterile air environment. Our design uses a grid of dielectric barrier discharge spanning across an opening of a typical air vent. Experiments have shown ~90% reduction of E.coli in controlled circulated. The DBD plasma device was used to inactivate airborne spores. Spores of B. Subtilis were sprayed into the system and treated with plasma discharge for 10 and 20 seconds. The results were then analyzed using plate count method. Results indicate ~1 log reduction in the concentration of airborne spores after 20 seconds of treatment. The results indicate the effectiveness of our DBD plasma discharge in inactivating spores.