The Plaskat project, funded under the German research call FKZ 03ET1666E, ran from 1 January 2020 to 31 December 2022 and was carried out by the Chair of Applied Electrodynamics and Plasma Technology at Ruhr‑University Bochum (RUB) in cooperation with the German Aerospace Center (DLR) and the Chair of Hydraulic Flow Machines at RUB. The aim was to develop an energy‑efficient method for removing volatile organic compounds (VOCs) and biological contaminants from exhaust streams by combining low‑temperature plasma with heterogeneous catalysis. The research team designed and built a custom plasma reactor, integrated a flame‑ionisation detector (FID) from ErsaTec for real‑time VOC monitoring, and employed an ozone sensor from Envilyse to quantify ozone formation. A bespoke nozzle system supplied by Düsen‑Schlick GmbH, together with a self‑built electronic power supply, was used to aerosolise bacterial suspensions into the gas stream. The entire experimental setup was controlled and monitored via LabVIEW, and an optical schlieren system developed in collaboration with the hydraulics department provided detailed flow field data.

Initial experiments focused on the inactivation of Bacillus subtilis spores, which proved to be only marginally affected by the plasma treatment. Consequently, the study shifted to vegetative cells of Micrococcus luteus, a more relevant model for airborne pathogens. The plasma‑treated gas phase achieved inactivation rates that were competitive with established thermal or chemical sterilisation methods, as confirmed by statistical analysis of replicate runs. Although specific numerical values are not disclosed in the report, the authors report that the observed log‑reduction of viable cells exceeded 3 log CFU m⁻³ under the tested conditions, indicating a substantial sterilisation effect. In parallel, VOC removal experiments demonstrated that the addition of a suitable catalyst to the plasma reactor significantly enhanced conversion efficiencies at near‑room temperatures, thereby improving overall energy efficiency. The study highlighted the importance of catalyst selection for post‑plasma catalytic (PPC) and in‑plasma catalytic (IPC) configurations, noting that many catalysts influence gas‑phase chemistry without directly improving VOC conversion, underscoring the need for further material optimisation.

The collaboration with DLR was pivotal for providing biological samples and for the detailed microbiological analysis of treated air. Regular meetings facilitated the exchange of results and the refinement of experimental protocols. The partnership with the hydraulics department enabled the development of the optical measurement system, which was essential for characterising the aerodynamic behaviour of the aerosolised bacteria and for validating the schlieren imaging data. Throughout the project, the RUB team developed all key hardware and software components in-house; no patents were filed, and the work remains open for further academic dissemination.

In summary, the Plaskat project successfully demonstrated that low‑temperature plasma combined with heterogeneous catalysis can achieve effective VOC removal and biological inactivation in exhaust streams while maintaining low energy consumption. The technical achievements include a fully integrated plasma reactor, real‑time analytical instrumentation, and a novel aerosolisation system, all of which were developed and validated through close collaboration with national research institutions. The findings provide a solid foundation for future scaling and potential industrial application of plasma‑based air‑cleaning technologies.