Are we ready for the application of the EU Regulation on wastewater reuse in agriculture? A techno-economic preliminary evaluation based on a case-study

Reuse of reclaimed wastewater (RWW) in agriculture represents one of the key strategies to promote for reducing the pressures on water sources, as also fostered by the EU governance. Indeed, the European Regulation 741/2020 on water reuse, entered into force in 2023, was issued with the aim to extend the reuse of treated water in agriculture under safe conditions. It establishes the minimum quality requirements; it also foresees the possibility to add additional requirements, especially for contaminants of emerging concern (CECs), based on "scientific evidence" and the risk assessment. The present study aims at evaluating from both the technical and economic points of view the potential reuse of RWW for irrigating edible crops in a real case study, considering the requirements set by the EU Regulation 741/2020. The Rieti province in the Lazio region of Italy was selected as the case study, since its territory is devoted to agricultural activities which have an important economic impact (e.g. olive trees, potatoes and maize). Firstly, the wastewater treatment plants (WWTPs) here located were classified based upon the quality of the water produced with respect to the classes listed by the EU Regulation. Then, the nutrients and water demand of the crops grown in the same area were compared with the nutrients and water potentially available through the RWW from the WWTPs. Furthermore, a preliminary assessment was carried out considering only four selected CECs present in the RWW produced by the WWTPs. Combining the quality requirements set by EU Regulation and the results of the preliminary risk assessment, in the investigated territory, there are 17 WWTPs potentially suitable for the irrigation of maize, only 1 plant for potato and 8 plants for olive.