Wastewater treatment plants in mediterranean spain : An exploration of relations between water treatments, water reuse, and governance

Wastewater treatment plants (WWTPs) are fundamental to enable the transition towards the principles of a circular economy in water supply. In Mediterranean Spain, an area with recurrent episodes of water stress, treated wastewater may become a critical resource for the future. However, its incorporation into the array of potential water options opens up questions regarding the different qualities obtained with each treatment, the extent of existing water reuse practices, or the governance regime of plants. In this paper, the state of WWTPs in Mediterranean Spain is analyzed, with focus on plant sizes, treatment technologies, water use, and governance regimes. The latter shows a strong presence of private WWTPs and a lesser extent of public-private WWTPs, while the number of public plants is small. Regarding treatment technologies, the most sophisticated systems are found in public-private plants that are also the largest in size. Reclaimed water is very significant for agricultural and golf course irrigation in some areas (Valencia, Murcia, Andalusia), but still relatively incipient for other uses.