A combined system of a biotrickling filter and a non-thermal plasma (NTP) in a downstream airflow was operated for 1220 days for treatment of emissions of styrene and secondary emissions of germs formed in the biological process. The biotrickling filter was operated at variable inlet concentrations, empty bed residence times (EBRT), type and dosage of fertilizers, irrigation densities, and starvation periods, while dielectric barrier discharge and corona discharge were operated at different specific input energy levels to achieve optimal conditions. Under these conditions, efficiencies in the removal of volatile organic compounds (VOCs), germs and styrene of 96–98%, 1–4 log units and 24.7–50.1 g C m⁻³ h⁻¹ were achieved, respectively. Fluid simulations of the NTP and a germ emission-based clocking of the discharge reveal further energy saving potentials of more than 90%. The aim of an energy-efficient elimination of VOCs through a biotrickling filter and of secondary germ emissions by a NTP stage in a downstream airflow for potential re-use of purified waste gas as process gas for industrial application was successfully accomplished.

Experimental findings to contribute to the preliminary design of a metal foil pump for fuel separation in the Direct Internal Recycling loop of the DEMO fusion device are presented. In parametric studies on a small-scale superpermeation experiment with a microwave plasma source and two different metal foil materials, niobium Nb and vanadium V, a substantial increase in permeation with plasma power and with a decrease in pressure was observed. To ease operation in the typical fusion environment, in-situ heating procedures were developed to recover from impurity contamination. The temperature independence of plasma-driven permeation from 600 to 900 °C metal foil temperature was demonstrated. No proof of an isotopic effect for plasma-driven permeation of protium and deuterium could be found. The highest repeatable permeation flux achieved was 6.7 Pa∙m³/(m²∙s) or ~5.5 × 10⁻³ mol H/(m²∙s). The found compression ratios do safely allow the operation of the metal foil pump using ejector pumps as backing stages for the permeate. In a dedicated experimental setup, the operation of the plasma source in a strong magnetic field was tested. Parametric studies of pressure, power input, magnetic flux density, field gradient and field angle are presented.

With rising CO₂ levels and climate change, finding alternatives to fossil fuels is essential. One attractive option is converting CO₂ into CO and O₂ via an atmospheric microwave plasma process. This study evaluates conversion and energy efficiency by increasing microwave power and CO₂ flow. Power and CO₂ flow were varied, with conversion measured using Fourier transform‐infrared spectroscopy, mass spectrometry, and gas analysis. A maximum conversion of 21.1 % was achieved at a specific energy input of 1.1 eV molecule⁻¹, highlighting the potential of this approach for efficient CO₂ utilization.

In order to achieve climate neutrality, preferably accompanied by cost reduction, plasmochemical processes open up attractive alternatives for the currently very energy‐intensive production of fertilizers. They can be cheaper, more environmentally friendly and agiler than the current state‐of‐the‐art for fixation of nitrogen building blocks. NO_x can be obtained from atmospheric nitrogen in an air‐powered plasma torch operating in‐loco and on‐demand, currently yielding a maximum NO_x concentration of 2.8 %. The torch can be further improved in efficiency and is designed for an easy upscaling.

La_0.6Ca_0.4Co_1–xFe_xO_3–d in its various compositions has proven to be an excellent CO₂-resistant oxygen transport membrane that can be used in plasma-assisted CO₂ conversion. With the goal of incorporating green hydrogen into the CO₂ conversion process, this work takes a step further by investigating the compatibility of La_0.6Ca_0.4Co_1–xFe_xO_3–d membranes with hydrogen fed into the plasma. This will enable plasma-assisted conversion of the carbon monoxide produced in the CO₂ reduction process into green fuels, like methanol. This requires the La_0.6Ca_0.4Co_1–xFe_xO_3–d membranes to be tolerant towards reducing conditions of hydrogen_. The hydrogen tolerance of La_0.6Ca_0.4Co_1–xFe_xO_3–d (x = 0.8) was studied in detail. A faster and resource-efficient route based on ultrasonic spray synthesis was developed to synthesise the La_0.6Ca_0.4Co_0.2Fe_0.8O_3–d membranes. The La_0.6Ca_0.4Co_0.2Fe_0.8O_3–d membrane developed using ultrasonic spray synthesis showed similar performance in terms of its oxygen permeation when compared with the ones synthesised with conventional techniques, such as co-precipitation, sol–gel, etc., despite using 30% less cobalt.

Microwave interferometry is a reliable, well established, and non-perturbing method to measure the line-integrated electron density of a non-uniform plasma through the phase shift of a wave that propagates the plasma medium. In this paper we combine the phase shift and the attenuation of the wave to experimentally extract both, the line-integrated density and the electron–neutral collision frequency of an atmospheric plasma torch. In addition, a novel method to obtain the 2D spatial plasma density profile of the torch is demonstrated by measuring the microwave power, without any information of the phase. The receiving antenna of the interferometer is moved perpendicularly to the axis of the torch and measures the spatial distribution of the microwave power. The wave is scattered by the plasma and the scattering profile depends on the plasma density profile. Direct comparison of this scattering profile with 3D full-wave simulations provides information on the electron number density profile of the plasma torch.