Transforming wastewater treatment plants into reclaimed water facilities in water-unbalanced regions. An overview of possibilities and recommendations focusing on the Italian case

Water scarcity will be one of the most challenging topics to cope with in the following years, especially in the regions most affected by climate change such as the Mediterranean basin. The implementation of water reuse practices thus appears essential to satisfy future water demands in a sustainable way, helping to reduce hydric stress in water-unbalanced regions. However, it remains as an underused practice. To change this situation, the wastewater sector needs to develop some structural changes that include not only the transformation of conventional wastewater treatment plants (WWTPs) into novel reclaimed water facilities (RWF), but also some paradigm shifts regarding social, political and legal factors. The goal of this manuscript is to provide a systemic, novel and updated vision of the wastewater treatment sector and to give some recommendations for the implementation of wastewater reuse in agriculture, with a special focus on the Italian case. Extensive data regarding water reuse technologies for the refining, disinfection and advanced oxidation of wastewater is also provided. This comprehensive analysis could help to align the objectives to be achieved from all the perspectives (technical, economic, legal and socio-political), thus helping to fill current gaps and overcome barriers that hinder water reuse development.