The COVID-19 outbreak circulating the world is far from being controlled, and possible contamination routes are still being studied. There are no confirmed cases yet, but little is known about the infection possibility via contact with sewage or contaminated water as well as with aerosols generated during the pumping and treatment of these aqueous matrices. Therefore, this article presents a literature review on the detection of SARS-CoV-2 in human excreta and its pathways through the sewer system and wastewater treatment plants until it reaches the water bodies, highlighting their occurrence and infectivity in sewage and natural water. Research lines are still indicated, which we believe are important for improving the detection, quantification, and mainly the infectivity analyzes of SARS-CoV-2 and other enveloped viruses in sewage and natural water. In fact, up till now, no case of transmission via contact with sewage or contaminated water has been reported and the few studies conducted with these aqueous matrices have not detected infectious viruses. On the other hand, studies are showing that SARS-CoV-2 can remain viable, i.e., infectious, for up to 4.3 and 6 days in sewage and water, respectively, and that other species of coronavirus may remain viable in these aqueous matrices for more than one year, depending on the sample conditions. These are strong pieces of evidence that the contamination mediated by contact with sewage or contaminated water cannot be ruled out, even because other more resistant and infectious mutations of SARS-CoV-2 may appear.
OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in: http://oatao.univ-toulouse.fr/ Eprints ID : 2602
AbstractThis paper develops an advance in the field of new synthesis techniques for functional materials like Yttria Stabilized Zirconia (YSZ) used as sensors, thermal barriers or electrolytes for high-temperature fuel cells.In recent years, sol-gel routes were developed to prepare, by suitable chemical modifications, submicronic based materials with a controlled morphology, which conventional solid state chemistry paths are unable to provide. Wet chemistry methods provide interesting alternative routes because mixing of species occurs on the atomic scale. In this paper, ultrafine powders were prepared by a novel wet chemistry method based on the sol-gel process. One of the advantages of this method is to decrease the crystallization temperature in comparison to the conventional ones, allowing the synthesis of reactive powders with nanometric particles size. In this study, several processing parameters have been investigated (the hydrolysis ratio, the concentration of metallic precursors in the sol and the role of organic compounds and additives). Pure phases of YSZ were obtained and the characteristics of these powders investigated (crystallographic study, morphology, phase composition, etc.). Also, our optimised synthesis was applied to large scale elaboration by increasing the quantity of precursors. This study underlines the interest of the sol-gel process both to control the morphology of oxides and to prepare large amounts of high purity powders for an eventual industrialization process.
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