The plasma of CH4/H2 was diagnosed with optical emission spectroscopy on a high-pressure microwave plasma apparatus at 2.45 GHz. The existing radicals in the plasma and the influence of the methane concentration on radical concentration and distribution were researched. The results indicate that the radicals of CH, Halpha, Hbeta, Hgamma, C2 and little impurity atom Mo exist in the plasma. The intensity of emission spectrum of the radicals increases with the increase in the methane concentration, especially the intensity of C2 has a notable increase. The ratio of the intensity of the CH to Halpha is unchanging with the increase in methane concentration, while that of C2 to Halpha has a marked increase. The uniformity of the space distribution of the radicals becomes worse with the increase in methane concentration.
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Environ Sci Technol
December 2024
Department of Earth, Planetary, and Space Sciences, University of California, Los Angeles, California 90095, United States.
Wetland methane emissions are the primary natural contributor to the global methane budget, accounting for approximately one-third of total emissions from natural and anthropogenic sources. Anaerobic oxidation of methane (AOM) serves as the major sink of methane in anoxic wetland sediments, where electron acceptors are present, thereby effectively mitigating its emissions. Nevertheless, environmental controls on electron acceptors, in particular, the ubiquitous iron oxides, involved in AOM are poorly understood.
View Article and Find Full Text PDFJ Environ Manage
December 2024
College of Petrochemical Engineering, Lanzhou University of Technology, Lanzhou, 730050, China.
Microbially mediated anaerobic oxidation of methane (AOM) regulates methane (CH) fluxes. Increases in the global atmospheric carbon dioxide (CO) concentration and iron oxide rich in paddy soils influence AOM. However, the response and mechanisms between these two processes and AOM remain unclear.
View Article and Find Full Text PDFWater Res
December 2024
GEMMA - Group of Environmental Engineering and Microbiology, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya-BarcelonaTech, c/ Jordi Girona 1-3, Building D1, Barcelona 08034, Spain. Electronic address:
Cyanobacterial wastewater-based biorefineries are a sustainable alternative to obtain high-value products with reduced costs. This study aimed to obtain phycobiliproteins and carotenoids, along with biogas from a wastewater-borne cyanobacterium grown in secondary effluent from an urban wastewater treatment plant, namely treated wastewater. For the first time, the presence of contaminants of emerging concern in concentrated pigment extracts was assessed.
View Article and Find Full Text PDFHorizontal subsurface flow constructed wetlands (HFCWs) are capable of eliminating organic matter and nitrogen while emitting less methane (CH) and nitrous oxide (NO) than free water surface flow wetlands. However, the simultaneous removal of pollutants and reduction of greenhouse gases (GHG) emissions from high-strength wastewater containing high levels of organic matter and ammonium nitrogen (NH-N) has not get been investigated. The influent COD concentration affected the efficiency of nitrogen removal, GHG emissions and the presence of iron from iron ore, but the COD and TP removal efficiencies remained unaffected.
View Article and Find Full Text PDFSci Rep
December 2024
College of Safety Engineering, Chongqing University of Science and Technology, Chongqing, 401331, China.
In order to promote low-carbon sustainable development in the ecological environment and improve the efficiency of hydrogen and natural gas energy utilization, this project carried out research on the explosive effects of different thicknesses of ordered porous media on the hydrogen-methane gas mixture. A detailed discussion was conducted based on the critical quenching hydrogen blending ratio under the thicknesses of 50 mm and 60 mm of ordered porous media. The results indicate that the critical quenching hydrogen blending ratio is 9% for a thickness of 50 mm and 20% for a thickness of 60 mm, indicating that greater thickness enhances flame suppression capabilities.
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