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Theses

Origine, comportement et devenir des Terres Rares dans les installations de traitements des eaux résiduaires urbaines et les milieux récepteurs associés

Abstract : Rare Earths Elements (REEs) are naturally present in water due to the erosion of rocks. They are used in human activities (new technologies, energy, agriculture and medicine). These ever-increasing uses eventually disrupted the geochemical and life cycle of REEs and led to the enrichment (positive anomaly) of some REEs in the hydrosphere (La, Ce, Sm and Gd). For anthropogenic Gd, pollution derives from conventional wastewater treatment plants (WWTPs) which are not able to remove the organic complex form of Gd used in MRI analyses. Four areas were therefore studied in order to better understand the behavior of the REEs: the French basin of the Moselle River, the Danube river basin as a whole, the WWTP of Grand Nancy, and the constructed wetland downstream the WWTP of Grand Reims. Along the Moselle River, the presence of positive Gd anomalies and a regular LREEs depletion/ HREEs enrichment pattern on sandstone/limestone substrates were the most distinctive features. In the Danube basin, the positive Gd anomaly ranged from 1.8 to 37.4 in surface water and up to 80.8 in groundwater, showing contamination of alluvial wells. Within the Greater Nancy STEU, the greatest Gd inflows were observed during weekdays (Tuesday and Wednesday), and at the end of the day (7 p.m. to 10 p.m.). Treatment processes did not affect anthropogenic Gd, but increased LREE/HREE fractionation. The waters of the artificial wetland were those with the highest values of positive Gd anomalies (up to 4500). It was shown that the magnitude of Gd anomalies depended on the methodological approach chosen for their calculation. The choice of a threshold value to identify the presence of an anthropogenic Gd anomaly may therefore be basin dependent and may be tricky in areas where anthropogenic pressure is low.
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Theses
File URL :
https://docnum.univ-lorraine.fr/ulprive/DDOC_T_2021_0021_LOUIS.pdf
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https://hal.univ-lorraine.fr/tel-03274534
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Submitted on : Wednesday, June 30, 2021 - 11:11:25 AM
Last modification on : Thursday, July 1, 2021 - 3:36:05 AM

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  • HAL Id : tel-03274534, version 1

Citation

Pauline Louis. Origine, comportement et devenir des Terres Rares dans les installations de traitements des eaux résiduaires urbaines et les milieux récepteurs associés. Génie des procédés. Université de Lorraine, 2021. Français. ⟨NNT : 2021LORR0021⟩. ⟨tel-03274534⟩

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