Development and implementation of an integrative bioanalytical approach to identify sources of toxicity formed during ozonation of wastewater
Organic micropollutants (MPs) such as pharmaceuticals, industrial chemicals, and biocides cause undesired effects in the aquatic environment when present above certain concentrations. Conventional wastewater treatment plants (WWTPs) are major point sources of entry of MPs into watercourses, leading to disturbances in the ecosystems of receiving water bodies and potentially to a negative impact on the quality of drinking water resources. Several European countries have started upgrading their WWTPs to reduce discharges of MPs into water bodies. Ozonation is one of the two main technologies used to upgrade WWTPs. The abatement of MPs by ozone has been shown to reduce certain toxicities such as endocrine disruption and algal toxicity. However, toxicological studies which investigated mutagenicity and genotoxicty –two endpoints relevant to carcinogenicity– revealed that ozonated wastewater exhibited mutagenic and genotoxic activities, which were not present before ozonation. To date, the nature of mutagenic and genotoxic ozonation transformation products and byproducts (OTPs and OBPs) as well as their precursors has not been elucidated. Owing to the large number of MPs present in wastewater effluents, testing each compound individually is not a feasible option. Consequently, an integrative strategy that prioritizes identification and targets the mutagenic and genotoxic compounds after toxicity assessment is necessary. OzoToxID aims at developing and implementing an integrative bioanalytical strategy based on effect-directed analysis combining mutagenicity and genotoxicity bioassays, fractionation, and cutting-edge high-resolution mass spectrometry chemical analysis to identify mutagenic and genotoxic OTPs/OBPs, determine their precursors, and elucidate their formation pathways. OzoToxID will provide key data that is crucial to determine the feasibility of ozonation when upgrading WWTPs.