Hydrocarbons and heavy metals fixed to the lift station sediment of the Paris combined sewer network

This work aims to characterise the pollutant loads fixed to the Lift Station (LS) sediments. Firstly, levels of n-alkanes, PAH and heavy metals (Fe, Zn, Cu, Pb and Cd) of LS sediments were assessed, and were found of the same order of magnitude as those reported for street runoff. In addition, investigations on LS sediment reveal that n-alkane distributions reflect the combination of biologic and petrogenic inputs, while PAH distributions indicate a major pyrolytic origin with traces of petrogenic contaminations. The metallic fingerprints also attest to the important contribution of road traffic emissions. Secondly, a comparison between LS sediment and the Gross Bed Sediment (GBS) pollutant contamination was established in order to optimize the in-sewer deposits management. For hydrocarbons, a similar contamination between both sediments is found. For the heavy metals, this comparison indicates a similar Fe and Zn content, while Pb, Cu and Cd contents differ. Indeed, LS sediment shows a higher Cu content, linked to the occurrence of intensive brake lining abrasion, compared with GBS, which reflects a higher Pb and Cd content, owing to the contribution of roof runoff. This result reveals the impact of specific inputs such as road traffic or roof runoff on the in-sewer sediments contamination, and provides a complete overview of the LS sediment contamination. This database could be used by the municipality to optimize their contaminated in-sewer sediment management.

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