This paper addresses problems arising from in situ measurement of gas content and temperature. Such measurements can be considered indirect. Transmittance or natural radiation of a gas is measured directly. The latter method (spectral radiation measurement) is often called spectral remote sensing. Its primary uses are in astronomy and in the measurement of atmospheric composition. In industrial processes, in situ spectroscopic measurements in the plant are often made with an open path Fourier Transform Infrared (FTIR) spectrometer. The main difficulty in this approach is related to the calibration process, which often cannot be carried out in the manner used in the laboratory. Spectral information can be obtained from open path spectroscopic measurements using mathematical modeling, and by solving the inverse problem. Determination of gas content based on spectral measurements requires comparison of the measured and modeled spectra. This paper proposes a method for the simultaneous use of multiple lines to determine the gas content. The integrated absorptions of many spectral lines permits calculation of the average band absorption. An inverse model based on neural networks is used to determine gas content based on mid-infrared spectra at variable temperatures.

The landfill gas (LFG), produced during decomposition of the organic fraction of waste is a major source of air pollutants. It consists mainly of methane and carbon dioxide, but also contains additional gases, such as nitrogen, oxygen, hydrogen, carbon monoxide, hydrogen sulphide, and a large number of trace components. Aliphatic and aromatic hydrocarbons, halogenated hydrocarbons, heterocyclic compounds, alcohols, aldehydes, ketones, terpenes and siloxanes belong to this group. This work presents the results of field studies concerning the concentration of over fifty non-methane organic compounds in municipal solid waste landfill gas. The sites examined were located in the Middle East macroregion of Poland. The landfills were different in the respect to size, morphology, and age of stored waste. The results reveal that the highest concentrations of the majority of the examined compounds were observed in gas released from the largest landfill at which the waste was not pre-treated prior to deposition. Concentrations often exceeded those found in the literature data. Deposition of waste after separation of biofraction and recyclable materials significantly decreased concentrations of the majority of NMOCs in the LFG.