Interdisciplinary assessment for crops irrigation with reclaimed wastewater

The pressure on water supply is steadily increasing and the problem of water scarcity is becoming more central and urgent. Treated wastewater, also called reclaimed wastewater (RWW), could replace primary water, especially in agriculture, one of the major source of water consumption worldwide [1], playing a key role in the ecological transition to a circular economy ([2], [3]). In 2023 a new European Regulation for water reuse entered into effect for regulating and promoting RWW reuse, defining the minimum requirements for a safe water reuse in agriculture and introducing a ‘fit for purpose' approach based on ‘scientific evidence’ to establish additional water requirements, especially for contaminants of emerging concern (CECs) [4]. CECs, indeed, could persist even after treatment in wastewater treatment plants (WWTPs) ([5], [6]) potentially leading to their uptake and bioaccumulation by crops when the effluent is reused for irrigation, posing risks to both the environment and human health ([2], [7]). The aim of this study is to develop an effect-based experimental methodology to evaluate the use of RWW in Lazio region (Italy) applying the EU Regulation 2020/741. A pilot-scale experimental set up was designed, with Eruca vesicaria plants (commonly known as Rocket) being irrigated using treated wastewater sourced from a WWTP in central Italy. Both positive and negative effects of wastewater irrigation on crops were evaluated, considering the content of CECs, assessing associated risks, and examining their interactions with crops. This evaluation also made use of an innovative combination of different tools, such as stable isotope tracing, phytotoxicity assessment and chemical data. In the actual absence of official protocols for evaluating the risks to human health and environment (a fundamental aspect of risk management, KRM5) ([8], [9]), a well-established procedure was used to estimate the potential risk to two exposed receptors (adults and children) from consuming edible crops irrigated with RWW [8].