Recycled Sewage: A Water Resource for Dry Regions of Southeastern Spain

Abstract

The latitude and layout of the Betic orography make southeastern Spain one of the driest climatic regions in Europe. Most of its territory is part of the Segura Hydrographic Demarcation (DHS). The DHS features a water resources vs water demands deficit equal to 480 hm3/ year (1 hm3 = 100 m3) during the 2009–2015 hydrologic planning period. A new paradigm for water policy in Spain has emerged for the hydrological planning period (2016–2021), which calls for a greater contribution of unconventional resources (desalination and reuse of municipal sewage). The investment made in the DHS, in terms of sewage purification and regeneration, produces about 110 hm3/year of purified sewage annually. Irrigation is the main consumer of these reuse flows. Irrigation districts develop conveyance and storage infrastructure to import treated sewage from Sewage Treatment Plants (STPs) and Water Regeneration Stations (WRSs). Anthropogenically-caused climate change has brought additional stress on surface water and groundwater, thus making water recycling an important component of the water supply portofolio in Spanish arid regions. Recycled water increases the resources of semi-arid regions (up to 10% of total resources), like in the Southeast of Spain. It is of great social value as it contributes to water safety, economic dynamism and biodiversity. Investment made in this sector and public policies make possible the implementation of recycling system, turning this limited resource into a social, political and economic interest, reaching levels of 99.5% purified and 97% reused in Murcia. Similar regions could import this management system and the concessionary model of reclaimed water. In dry regions, these water management models make recycled water, rather than an alternative, a significant complement to local water resources