Assessment of effluents quality through ecotoxicological assays: evaluation of three wastewater treatment plants with different technologies.

The water quality of the effluents is mainly focused on physicochemical and microbiological parameters. However, the ecotoxicological assessments are crucial to ensure an effective water quality of the effluents. This work aims to assess the ecotoxicity of effluents originated from WWTPs with different wastewater treatment technologies. For that, effluent samples from three WWTPs with different treatment processes were seasonally collected. Physicochemical parameters were determined, the toxicity towards daphnia, protozoan, and microalgae organisms was evaluated, and data correlated. Toxicity assays showed different susceptibility of the organisms to the effluents and that toxicity is dependent on the season and wastewater treatment technology. No toxicity was observed to daphnia in winter and spring, but ~100% of mortality was observed in effluent from WWTP A in summer. Growth inhibition was observed for both protozoan and microalgae for all effluents and in all seasons with highest values in spring in WWTP C (~80%) for the protozoan while the highest microalgae growth inhibition percentage was observed for WWTP B in both spring (~80%) and summer (~80%). These results show that effluents might have negative impacts into their receiving water systems and highlight that a global assessment of effluent quality should include ecotoxicological assays to complement physicochemical and microbiological data for an operative environmental management of wastewater treatment plants.

Occurrence of Natural Contaminants of Emerging Concern in the Douro River Estuary, Portugal.

Many studies demonstrated the presence of diverse environmental contaminants in the Douro River estuary, such as natural and synthetic estrogens, pharmaceuticals, industrial compounds and pesticides. This estuary is located between two densely populated cities and is highly impacted due to anthropogenic activities, such as industry and agriculture. Although the presence of mycotoxins and phytoestrogens, such as lignans and coumestrans, in the aquatic environment is reported by some authors, their occurrence in Portuguese waters was not investigated yet. To evaluate the presence of phytoestrogens, phytosterols and mycotoxins in Douro River estuary, water samples were collected seasonally at nine sampling points, preconcentrated by solid phase extraction and analysed by gas chromatography mass spectrometry. Local flora was collected on the riverside, in the same sampling points, for identification and evaluation of the possible relation to the presence of phytoestrogens and/or phytosterols in the estuarine water. Results showed the ubiquitous presence of mycotoxins, namely deoxynivalenol up to 373.5 ng L(-1). Both phytoestrogens and phytosterols showed a possible seasonal fluctuation, which is in accordance to the life cycle of the local flora and agricultural practices. Physicochemical parameters were also determined for water quality evaluation. This study revealed for the first time the presence of mycotoxins and lignans in estuarine waters from Portugal, and highlights the need to consider natural contaminants in future monitoring programs.