Assessment of Ozone or Not-Treated Wastewater Ecotoxicity Using Mechanism-Based and Zebrafish Embryo Bioassays

Abstract

Toxicity of wastewater treatment plant (WWTP) effluents is usually assessed with standardized bioassays, as e.g. the Fish Embryo Toxicity test (FET), but assessment of sub-lethal toxic effects requires to develop more adapted tests. The present work aimed to add the recording of several sub-lethal endpoints in exposed zebrafish embryo-larval stages in order to increase the sensitivity of residual toxicity evaluation of WWTP effluents using a semi-quantitative method (iFET score). This approach was complemented with the genotoxicity assessment on the exposed embryos, a sub-acute hazard particularly relevant to evaluate a potential chronic toxicity risk of low and multi-contaminated environmental matrices. Additionally, endocrine activities of effluents were quantified using human reporter cell lines. This test battery was applied to the assessment of the residual toxicity of five biological treatment effluents, further treated or not using various ozonation treatments intended to improve pharmaceutical compounds removal. Acute toxicity towards zebrafish embryos was very low. However, iFET score approach proposed was able to reveal residual toxicity through the presence of developmental abnormalities in all samples tested. Additionally, a low residual genotoxicity was measured in embryos exposed to two of the WWTP effluents when all excepted one exhibited a residual

Antibiotic-resistant bacteria, antibiotic resistance genes, and antibiotic residues in wastewater from a poultry slaughterhouse after conventional and advanced treatments

“…This might be due to low ozone dosages frequently used in practice 13 , 55 . However, increasing the amount of ozone might lead to the release of harmful products to the environment and have an ecotoxicological effect 56 . Applying additional filtration steps (e.g., charcoal or sand filtration) after ozonation to remove remaining ozone and unwanted byproducts may result in bacterial regrowth 13 .…”

Ecotoxicological characterization of micropollutants and wastewater samples from conventional biological and advanced wastewater treatment

“…The adapted bioassay allowed for the combined assessment of developmental and reproductive toxicity (DART) and CYP-35A3 induction (2.3 and Abbas et al 2018). Novel test systems and strategies have been rated highly important, because standard bioassays may be insensitive in detecting relevant water quality deficiencies (Berger et al 2016, Schwarzenbach et al 2006, Sonne et al 2018, Wigh et al 2018.…”

“…Standardized test systems may however not indicate these properties throughout all wastewater investigations leading to variable bioassay results and compromised sensitivities (Berger et al 2016, Wigh et al 2018. Thus the present aim was to examine an integration of the results obtained with C. elegans into the wastewater evaluation matrix and to deduct its usefulness to wastewater investigations (such as discussed under 2.3).…”

“…In addition, it could be argued that an extended selection of robust and sensitive in vitro and in vivo bioassays may have revealed undetected effects, which should be integrated into future wastewater quality evaluations not to overlook significant biological risks (compare Berger et al 2016 for DW, Schwarzenbach et al 2006, Sonne et al 2018, Stamm et al 2016, Wigh et al 2018.…”

Ecotoxicological profiling of sediments from the wurm river (North Rhine-Westphalia, Germany) under different weather and wastewater treatment conditions

“…Subsequently, numerous scientific studies investigated adverse effects of synthetic (plasticizers, pesticides, industrial chemicals, drugs) and natural (phytoestrogens, excreted hormones) EDCs in WWTP effluents (Jarošová et al, 2014;Johnson et al, 2007;Vajda et al, 2008;Vajda et al, 2011;Vethaak et al, 2005). However, effect-based monitoring of WWTP effluents is still not required at the EU level (Wigh et al, 2018). Advanced wastewater treatment by ozonation is increasingly used to eliminate EDCs (Escher et al, 2009;Giebner et al, 2018).…”