Novel metabolomic method to assess the effect-based removal efficiency of advanced wastewater treatment techniques

Abstract

Environmental contextAdvanced wastewater treatment is required to remove pharmaceuticals and many other consumer chemicals from wastewater effluent. There are conflicting findings, however, on the toxicity of treated effluent, and its effect on living organisms is often neglected. We show that the effect-based removal efficiency of wastewater treatment technologies can be assessed by metabolomic methods, and that this approach contributes to a safer and more controlled water quality. AbstractThere are conflicting findings on the toxicity of effluent from wastewater treatment plants, and only limited possibilities for assessing the effect-based removal efficiency (EBRE) of different treatment techniques. We describe a metabolomics approach to detect perturbations in fatty acid catabolic pathways as a proxy for biological effects. Metabolites in three fatty acid pathways were analysed in a common damselfly larva (Coenagrion hastulatum) by liquid chromatography coupled to mass spectrometry. The larvae were exposed for one week to either conventionally treated effluent (activated sludge treatment), effluent additionally treated with ozone, or effluent additionally treated with biochar filtration, and results were compared with those from tap water control exposure. Five lipoxygenase-derived oxylipins (9,10,13-TriHOME, 9,12,13-TriHOME, 9-HODE, 9-HOTrE, and 13-HOTrE) decreased in response to conventionally treated effluent exposure. By using an additional treatment step, oxylipin levels were restored with exception of 9,10,13-TriHOME (ozonated effluent), and 9-HOTrE and 13-HOTrE (effluent filtered with biochar). Thus, exposure to wastewater effluent affected fatty acid metabolite levels in damselfly larvae, and a subset of the analysed metabolites may serve as indicators for biological effects in biota in response to effluent exposure. To that effect, our findings suggest a new metabolomics protocol for assessing EBRE.