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 is one of the most challenging topics to cope currently, especially in the regions most affected by climate change such as the Mediterranean basin. The implementation of safe 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 because of the lack of incentives of water companies to invest in it, limited social trust and high governance complexity, amongst other factors. To change this situation, the wastewater sector needs to develop some structural changes that include the transformation of conventional wastewater treatment plants (WWTPs) into novel reclaimed water facilities (RWF), as well as 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 in Italy and to give some recommendations for the implementation of wastewater reuse in agriculture. 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.