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Chlorine for Water Disinfection: Properties, Applications and Health Effects.

Drogui, Patrick; Daghrir, Rimeh (2015). Chlorine for Water Disinfection: Properties, Applications and Health Effects. In: CO₂ Sequestration, Biofuels and Depollution. Environmental Chemistry for a Sustainable World, 5 . Springer, Netherlands, p. 1-32. ISBN 978-3-319-11905-2

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Résumé

Chlorine compounds are chemicals commonly used as oxidizing agents for drinking-water disinfection and water treatment . Chlorine (Cl) is an halogen element having 7 electrons on its last electronic layer. To reach the stability of 8 electrons chlorine has a tendency to add an electron. This tendency to add an electron gives chlorine special oxidizing properties. Chlorine indeed kills harmful microorganisms, has decolourization properties, and oxidize and modify organic molecules. Chlorine can be used as a bleaching agent and to fight against biological fouling in cooling systems. Chlorine popularity is not only due to lower cost, but also to its higher oxidizing potential, which provides a minimum level of residual chlorine throughout the distribution system and protects against microbial recontamination with a remarkable remnant effect. Chlorine is used in different forms: gaseous, e.g. Cl₂ and ClO₂, liquid, e.g. NaClO, HClO, and NH₂Cl, and solid, e.g. Ca (OCl)₂. Chlorine is industrially produced by electrolysis of aqueous sodium chloride (NaCl). The application of chlorine to water treatment poses risks by producing by-products such as organochlorinated compounds. Disinfection by-products (DBPs) such as trihalomethanes, haloacetic acids, haloacetonitriles and haloketones are formed when chlorine reacts with natural organic matter such as humic acids and phenols. Some organochlorinated compounds are endocrine disruptors involved in brain cancer, immune and reproductive system troubles, and feminization. Modern legislations in all countries impose environmental regulation and health quality standards that become more and more stringent. Emerging regulation limiting the concentration of by-products in drinking water has increased demands for alternative processes that remove organics before disinfection. Processes include coagulation with active carbon, flocculation, sedimentation, sand filtration. Altenrative disinfection is done by advanced oxidation processes including O₃/H₂O₂, UV/O₃, and UV/H₂O₂, membrane filtration and electrochemical disinfection.

Type de document: Chapitre de livres
Mots-clés libres: water treatment; chlorine; trihalomethane; coagulation; flocculation; sedimentation; UV; O₃; H₂O₂
Centre: Centre Eau Terre Environnement
Date de dépôt: 08 mai 2018 18:02
Dernière modification: 08 mai 2018 18:02
URI: http://espace.inrs.ca/id/eprint/3838

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