Water reuse of south Barcelona’s wastewater reclamation plant

The use of water from the wastewater reclamation plant serving the south of Barcelona, Spain, will contribute with new resources to help to solve the water scarcity problem that the Barcelona metropolitan area suffers at present. When the plant starts to operate, it is scheduled to reuse 50 Mm3/y of reclaimed water that will be used for supplying the ecological flow in the lower part of the Llobregat River, irrigation of farm areas and supplying water to wetlands in the river deltaic areas. Another scheduled use pretends to solve the salt-intrusion problem in the Llobregat lower delta aquifer through the implementation of an hydraulic barrier using reclaimed water. For obtaining water with the quality required for all the reuse purposes, it is necessary to modify the existing biological treatment to remove nutrients (nitrogen and phosphorus) and the construction of a tertiary reclamation facility, which for recharge purposes includes a reverse osmosis plant. A pumping station and pipelines for transporting the reclaimed water to the different application areas and a different pipeline for transporting the water to the injection wells where it is introduced into the aquifer at a depth of 60 m are being built.

The defined reuse project will improve ecological conditions in the lower part of the Llobregat River basin, contribute to reduce the scarcity of water resources in the Barcelona metropolitan area and help to avoid seawater intrusion into Baix Llobregat delta aquifer. In order to obtain the required water quality for reuse, two different tertiary treatments are built, with the technologies most suitable in each case. This project is the most important water reuse project on the Mediterranean coast and it is the first time that a barrier against seawater intrusion has been built in Spain. This experience will help to design similar projects of water reuse to avoid intrusion and develop new projects of water reclamation and reuse.