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Introduction et stockage des hydrocarbures et des éléments métalliques au sein du réseau d'assainissement unitaire parisien

Abstract : The importance of the combined sewer overflow (CSO) pollution and its acute impact on receiving waters have been largely demonstrated. The development of CSO management strategies requires an improved knowledge on the pollutant loads in sewer deposits since many authors have underlined their significant role as source of pollution in CSO discharges. This work has improved the knowledge on the storage of hydrocarbon and metallic pollutants in the Paris combined sewer system. Results have shown that the major part of micropollutants is stored in the gross bed sediment (87 to 98 %), a lesser part in the organic layer (2 to 13 %) and an insignificant part in the biofilm (below 1 %). According to these results, the potential contribution of the biofilm to wet weather pollution can be considered as negligible compared to the organic layer contribution. Hydrocarbon fingerprints have been investigated in each deposit in order to provide information about the contamination origins and the deposit dynamic in sewer system. Thus, aliphatic hydrocarbon distributions are indicative of prominent petroleum inputs in the gross bed sediment (engine oil) and reflect a mixture of biogenic (vegetal) and petroleum inputs in the organic layer and the biofilm. Aromatic hydrocarbon distributions, characterised by the predominance of phenanthrene, pyrene and fluoranthene, suggest an important pyrolytic contamination (road traffic, residential heating, etc.) in all deposits. Finally, the deposit dynamic study has shown that suspended solids, going through the collectors, are the major components of organic layer and biofilm and that the residence times in the combined sewer for both deposits are quite short compared to time for the gross bed sediment. Moreover, results have shown that there is a spatial fluctuation of metallic contents at the whole sewer network scale and that there is no typical metallic fingerprint for sewer deposits. Spatial fluctuation has been also observed for hydrocarbon contents, but, contrary to metals, there is an homogeneous PAH fingerprint at the whole combined sewer scale. This distribution, characterised by the predominance of phenanthrene, pyrene and fluoranthene, highlights the impact of pyrolytic sources. The second part of this work concerns the pollutant loads conveyed by the different introductory source pathways to the sewer i.e. roof runoff, road runoff, including road runoff during rain events and street cleaning, and sewer effluents (domestic waste waters, restaurant effluents, etc.). Results highlight that both metallic and slate roofs do not act as sources of hydrocarbons and metals - exclusively originating from atmospheric depositions - while they act as sources of some heavy metals (Cu, Pb, Ti and Zn). Characterisation of sediments extracted from lift stations, located near the major road ways of Paris, has shown that contamination levels of road runoff are of 80 and 24 µg.g-1 for aliphatic and aromatic hydrocarbons, and of 27800, 1630, 770, 790, 2.7 µg.g-1 for Fe, Zn, Pb, Cu and Cd, respectively. Study of street cleaning waters has underlined the great quantities of micropollutants produced by the daily street cleaning. Results have shown that, at the “Le Marais” catchment scale (Paris, 4th district), the contribution of street cleaning waters to the sewer pollution is greater than that for roof runoff. Finally, hydrocarbon pollution from domestic, restaurant and garage effluents has been studied. At the “Le Marais” catchment scale, aliphatic hydrocarbon fluxes conveyed by these effluents, estimated at 840 and 1230 g.d-1 for resolved and unresolved compounds respectively, are strongly superior to those conveyed by roof runoff and street cleaning waters. This result underlines the major contribution of sewer effluents to the aliphatic hydrocarbon pollution of sewer network.
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https://pastel.archives-ouvertes.fr/tel-00007154
Contributor : Vincent Rocher <>
Submitted on : Tuesday, October 19, 2004 - 9:12:40 PM
Last modification on : Friday, October 4, 2019 - 1:25:52 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:22:52 PM

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  • HAL Id : tel-00007154, version 1

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Vincent Rocher. Introduction et stockage des hydrocarbures et des éléments métalliques au sein du réseau d'assainissement unitaire parisien. Autre. Ecole des Ponts ParisTech, 2003. Français. ⟨tel-00007154⟩

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