Techno-economic preliminary evaluation for the possible application of the EU Regulation on wastewater reuse in agriculture: a case-study

The pursuit for alternative water sources is crucial to face the increasingly frequent episodes of drought occurring around the world and to promote circular economy, especially in agriculture, one of the major source of water consumption worldwide. EU governance has recognised reclaimed wastewater (RWW) reuse in agriculture as the key strategy to reduce water sources pressure. Indeed, the new European Regulation 741/2020 on water reuse, come into force in 2023, aims to promote RWW reuse in agriculture. It outlines the minimum quality requirements for a safe water reuse and introduces a 'risk assessment' approach, based on “scientific evidence” , to establish additional requirements, especially for contaminants of emerging concern (CECs). The present study intend to conduct a preliminary evaluation of the possible implementation of the EU Regulation 741/2020 in a selected territory, for the irrigation of edible local crops, assessing the potential reuse of RWW for irrigation, from both the technical and economic points of view. The evaluation was based to the minimum requirements set by the Regulation. Furthermore, the risk assessment due to the presence of selected CECs in the RWW was also conducted. The study was carried in collaboration with) the local Water Service Utility, Acqua Pubblica Sabina (ApS). The strict conjunction with the water utility company provided the needs and issues of the final utilizer, which must be addressed, beside the scientific requirements, to make the RWW reuse technically feasible and sustainable. The selected area for the case study was the Rieti province, in the Lazio region (central Italy), a territory dedicated to agriculture activities with an important economic impact (e.g. olive trees, potatoes and maize).

The study was conducted in several phases. Firstly, the wastewater treatment plants (WWTPs) located in the selected area were classified based upon the main characteristics (such as the treatment capacity, layout, produced water quality) and water quality 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 risk 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.