Search

Les performances atteintes par les deux systemes biologiques etudies – boues activees conventionnelles (BA) et reacteur biologique a biomasse fluidisee (MBBR) – dans le traitement des dix micro— polluants d’origine pharmaceutique quantifies sont similaires et cela grâce au niveau d’epuration identique en nitrification totale.Les abattements quantifies sont variables et atteignent en moyenne pour les sept composes refractaires seulement 24% (carbamazepine, sulfamethoxazole, propranolol, atenolol, diclofenac, econazole, acide salicylique). Les trois autres composes, bien elimines en traitement biologique, atteignent en moyenne 96% (paracetamol, ketoprofene et ibuprofene).Le traitement biologique combine a l’ozonation tertiaire elimine efficacement les composes pharmaceutiques de l’eau des l’utilisation des doses faibles d’ozone (0,45 gO3/g de carbone organique dissous COD). Un abattement moyen de 92% d’efficacite est quantifie sur la moyenne de composes pharmaceutiques dissous, a comparer aux 24% a 45% d’abattement obtenu en traitement bio logique seul. Le passage a une dose d’ozone de 1,30 gO3/gCOD permet d’augmenter de 6% l’abattement moyen des micropolluants. Cette performance n’est pas amelioree par l’utilisation des doses d’ozone plus importantes.Contrairement aux tests d’ecotoxicite normalises (peu sensibles pour discriminer des effets toxiques dans les eaux traitees biologiquement ou chimiquement), les effets mesures sur les embryons du poisson Danio rerio comme la mortalite, les anomalies sur le developpement et la genotoxicite ont montre un effet toxique (nul a faible) pour les effluents biotraites ou ozones. Par rapport au traitement biologique, l’ozonation tertiaire ameliore significativement le potentiel de perturbation endocrinienne des effluents par la reduction complete de l’activite oestrogenique et glucocorticoide des effluents.L’ozonation n’augmente ni ne diminue le niveau de toxicite des effluents deja atteint avec le traitement biologique seul. Il existe un bruit persistant probablement lie a la presence d’autres micro - polluants remanents dans l’eau et non quantifies par la methode d’analyse ciblee. Leur activite peut etre a l’origine du niveau d’effet toxique faible obtenu pour certains biomarqueurs. Ces resultats montrent la necessite d’ameliorer la sensibilite des bioessais dans le but d’optimiser l’evaluation des effets ecotoxicologiques residuels dans les differents types d’effluents.L’obtention des signatures chimiques, au travers d’une approche non ciblee, s’avere un outil puissant et complementaire. Elles revelent la complexite des effluents etudies par le nombre important de signaux obtenus. Les cartographies realisees, par l’analyse en composantes principales, permettent d’avoir une vision globale des effluents et de leur mise en relation respective. Cette approche globale complete efficacement les resultats obtenus par le dosage cible des micropolluants.

International audience; Standardized ecotoxicity bioassays show some limits to assess properly long-term residual toxicity of complex mixture of pollutants often present at low concentration, such as stormwaters. Among invertebrate organisms used for ecotoxicity testing, the microcrustacean Ceriodaphnia dubia (C. dubia) is considered as one of the most sensitive, especially regarding reproduction impairment as a toxicity endpoint. Consequently, the present work explores the interest to perform a multi-generational assay based on the study of the reproduction of C. dubia to assess long-term ecotoxicity of complex mixture, using stormwater samples. With this in mind, a battery of standardized bioassays (Daphnia magna mobility, Pseudokirchneriella subcapitata population growth, Heterocypris incongruens growth and one generation C. dubia reproduction inhibition assays) was performed in parallel to a three generation C. dubia reproduction inhibition assay on 2 stormwater samples. Results highlighted that while all standardized bioassays failed to reveal residual toxicity in the stormwater samples, the C. dubia multi-generational assay exhibited an higher sensitivity than the previous ones. No adverse effect was observed for the first exposed generation, but an increase in mortality and a reproduction disturbance was obtained in the second and third exposed generation depending of the sample. Further experiments are now needed to optimize the exposure protocol of this multi-generational assay.

International audience; Wastewater treatment plants (WWTPs) are one of the main sources of freshwater pollution eventually resulting in adverse effects in aquatic organisms. Treated effluents can contain many micropollutants at concentrations often below the limit of chemical quantification. On a regulatory basis, WWTP effluents have to be non-toxic to the aquatic environment, wherefore not only chemical abatement but also ecotoxicological evaluation through relevant bioassays is required. Standardized bioassays currently used are often not sensitive enough to reveal a residual toxicity in treated effluents. Therefore, attention must be paid to the development of better-adapted approaches implementing more sensitive organisms and relevant endpoints. In this study, the toxicity of two differently treated effluents (activated sludge treated effluents with and without ozonation) towards the ecologically relevant species Gammarus fossarum was evaluated. Organism fitness traits such as reproduction and sperm DNA integrity were followed in exposed organisms. In complement, enzymatic biomarkers were measured indicating the presence of neurotoxic compounds (acetylcholinesterase activity), the presence of pathogens likely to increase the toxic effects of chemical compounds (phenol-oxidase activity), and the presence of toxic compounds inducing detoxification mechanisms (glutathione-S-transferase activity). Enzymatic activities were not modified, but significant sub-lethal effects were observed in exposed organisms. In both effluents, females showed a retarded molt cycle, a reduced fecundity and fertility, and > 90% of developed embryos exhibited developmental malformations. In addition, a slight but significant genotoxic effect was measured in gammarid sperm. In a whole, no difference in toxicity was found between both effluents. Coupling reproduction impairment and genotoxicity assessment in Gammarus fossarum seems to be a valuable and sensitive tool to reveal residual toxicity in effluents containing a mixture of micropollutants at very low concentrations. Finally, a direct relationship between the observed toxic responses and the quantified micropollutant concentrations could not be evidenced.

International audience; A mixture of urban and hospital effluents (50 % v/v) was evaluated for ecotoxicity with an advanced bioassay battery. Mixed effluents were tested before any treatment, af- ter biological treatment alone, and after biological treatment followed by a tertiary ozonation (15 mg O3/L). Laying a high value on the continuance of organisms’ fitness, essential to preserve a healthy receiving ecosystem, the main objective of this study was to combine normalized bioassays with newly developed in vivo and in vitro tests in order to assess alteration of embryo development, growth and reproduction, as well as genotoxic effects in aquatic organisms exposed to complex wastewater effluents. Comparison of the bioassays sensitivity was considered. Contrary to the lack of toxicity observed with normalized ecotoxicity tests, endpoints measured on zebrafish embryos such as developmental abnormalities and genotoxicity demonstrated a residual toxicity in wastewater both after a biological treatment followed or not by a tertiary O3 treatment. However, the ozonation step allowed to alleviate the residual endocrine disrupting potential measure in the bi- ologically treated effluent. This study shows that normalized bioassays are not sensitive enough for the ecotoxicological evaluation of wastewaters and that there is a great need for the development of suitable sensitive bioassays in order to characterize properly the possible residual toxicity of treated effluents.

International audience; Hospital wastewater (HWW) contain a large number of chemical pollutants such as disinfectants, surfactants, and pharmaceutical residues. A part of these pollutants is not eliminated by traditional urban wastewater treatment plants (WWTP), leading to a risk for the aquatic ecosystems receiving these effluents. In order to assess this risk, we formulated a specific methodology based on the ecotoxicological characterisation of the hospital wastewater using a battery of three chronic bioassays (Pseudokirchneriella subcapitata, Heterocypris incongruens and Brachionus calyciflorus). We used it for the posteriori risk assessment of a hospital recently built in south-east France, and we studied the evolution of this risk during two years. We also used it to assess the decrease of the ecotoxicological risk after treatment of the effluent in a specific line of the local WWTP. Lastly, we compared these results with the risk assessment made before the building of the hospital in the context of a priori risk assessment. The results obtained showed an important evolution of the risk overtime, according to the hospital activities and the river flows, and a real decrease of the risk after treatment in the dedicated line. They also showed that the a priori assessment of ecotoxicological risks, made previously, was overstated, mainly because of the application of the precautionary principle.

International audience; Tamoxifen, a drug used to treat cancer, is regularly found in hydrosystems at concentrations of several hundred ng L-1. To characterize its ecotoxicity, we implemented a battery of bioassays on organisms belonging to 3 different trophic levels: Pseudokirchneriella subcapitata, Chlorella vulgaris and Chlamydo- monas reinhardtii, for primary producers, Daphnia magna (immobilization, grazing and reproduction) for primary consumers, and Danio rerio for secondary consumers (embryotoxicity test). In view of the results obtained and the ecotoxicity values of tamoxifen available in the literature, we established a PNEC (Predictive No Effect Concentration) equal to 81 ng L-1 for continental water. This PNEC allowed us to cal- culate Risk Quotients (RQ) for 4 continental hydrosystems in 4 different countries in which measures of tamoxifen had already been performed on surface waters. In two of the situations studied, RQs were higher than 1, reaching a maximum of 2.6. These results show the need to deepen the characterization of ecotoxicological risks linked to the discharge of tamoxifen in surface waters. In addition, we propose applying this approach to other drug residues detected in the environment.