A combined chemical and ecotoxicological approach to assess nature-based solutions efficiency in removing pharmaceuticals using microcosms

Abstract

Pharmaceutical products (PP) are considered contaminants of emerging concern, and their discharge into the environment has increased due to both, human and veterinary use. These drugs entered freshwater ecosystems and remain physiologically active, posing potential negative effects on aquatic ecosystems. As conventional plants for wastewater treatment are not designed to remove most of these micropollutants, the development of strategies for sustainable management is essential and nature-based solutions (NBS) will be useful in removing pollution, simultaneously benefiting people and nature. This study aims to assess the effectiveness of PP removal of different NBSs implemented at a microcosm scale from chemical and ecotoxicological points of view. Proposed NBSs were based on floating wetlands with improvements based on the use of biochar and bioaugmentation (biofilm coating). The proposed NBSs were able to reduce up to 90 % of the total PP concentration after the whole experimental period (42 days). However, considering a regular hydraulic retention time (7 days), the higher PP removal rate (55 %), took place in the microcosms with floating wetlands enhanced with biochar (FWB), followed by the floating wetlands enhanced with biofilm-coated biochar (FWBB) (51 %) and the floating wetland (FW) (42 %). The selected NBS (FWB) has also been assessed through the toxicological approach, and the acute and behavioural effects of the wastewater were also reduced after 7 days. The proposed solution will benefit both nature and society, reducing PP pollution and enhancing water resource quality. The results obtained with the ecotoxicological approach highlight the relevance of considering the toxic cocktail, as a whole, in environmental risk assessment and the use of behavioural biomarkers for spotlighting its ecological consequences.