Real-time gas phase monitoring of regulated emissions from a waste recovery center by terahertz rotational spectroscopy

Abstract Atmospheric emissions from waste recovery centers are strictly regulated by industrial emission directives which stipulate that they should be continuously monitored. In this work, we demonstrate and evaluate the capacity of terahertz rotational spectroscopy for real-time diagnosis and monitoring of gases of environmental interest on industrial sites. A spectrometer based on the use of a frequency multiplication chain operating at 530–620 GHz has been constructed, enabling the detection of most of the regulated compounds in waste incineration. The detection limits obtained are compatible with regulatory emission limit values. The installation of the instrument at the waste recovery center in Dunkirk demonstrated its ability to perform real-time quantitative multi-component in situ monitoring in an industrial environment. Continuous measurements of SO 2 and CO over more than 24 h are compared with the measurements performed by two certified infrared instruments. The agreement between the three sets of measurements is excellent, demonstrating that high-resolution terahertz spectroscopy is relevant for real-time in situ monitoring of regulated industrial emissions gases, constituting an interesting alternative to other techniques thanks to a higher degree of selectivity.