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IDAEA contributes to the design of the wetland system and the assessment of its impact on aquifer behaviour
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The initiative is part of the PAITIDA project led by the Besòs Tordera Consortium and funded through the Digitalisation of the Water Cycle PERTE programme
Participants in the PAITIDA project during the inauguration of the pilot basin. | Besòs Tordera Consortium
On 28 May, the La Llagosta Wastewater Treatment Plant (WWTP) hosted the inauguration of a pilot managed aquifer recharge basin for the Besòs alluvial aquifer, an innovative infrastructure designed to increase water resource availability and contribute to improving groundwater quality across the basin.
The new pilot basin enables the infiltration of reclaimed water from the La Llagosta WWTP, which has undergone tertiary treatment, in order to evaluate its capacity to safely recharge the alluvial aquifer and improve both the quantity and quality of groundwater resources in the Besòs basin. This solution forms part of Managed Aquifer Recharge (MAR) strategies, widely recognised as a key tool for enhancing the resilience of water systems to drought and the impacts of climate change.
The basin has been designed as a Nature-based Solution (NbS) and incorporates a natural treatment system consisting of floating wetlands and a series of filtering materials installed at the base of the basin. The layered arrangement of these filter media enables the retention of suspended solids, the degradation of organic matter, and the transformation of nutrients through the physical, chemical and biological processes characteristic of vertical-flow treatment systems. This configuration helps ensure that the infiltrated water is of high quality.
“Building on the results of the European project UPWATER, we have scaled up the Montcada i Reixac wetland from an area of 10 m² to 100 m². Over the coming months, we will evaluate the removal of nutrients, metals, emerging contaminants, pesticides, PFAS and other compounds, as well as their effect on aquifer recharge in terms of both water quality and quantity,” explains IDAEA researcher Víctor Matamoros.
The system is monitored through several piezometers installed as part of the same project, which have enabled the hydrogeological characterisation of the site prior to recharge activities. Using this information, different hydrogeological models have been developed to simulate the effects of the basin both in its immediate surroundings and across the aquifer as a whole. Plant operation is complemented by a hydrochemical and isotopic study aimed at evaluating and quantifying the influence of the system.
“This is the first constructed wetland built using a substrate made entirely of biochar and specifically designed for aquifer infiltration, where treatment and recharge take place simultaneously through the infiltration of reclaimed wastewater,” says hydrogeologist and IDAEA researcher Enric Vázquez-Suñé.
The initiative forms part of Activity 22 (A22) of the PAITIDA project – Comprehensive Digitalisation of Sanitation Systems within the Integrated Water Cycle of the Besòs River Basin to Ensure Water Quality and Availability for Public Supply. The project is promoted by the Besòs Tordera Consortium, monitored and partly funded by the Catalan Water Agency (ACA), and largely financed through the Digitalisation of the Water Cycle PERTE programme under the European Union’s Recovery, Transformation and Resilience Plan – NextGenerationEU.
Visit to the La Llagosta WWTP facilities. | Consorci Besòs Tordera
The inauguration event brought together representatives from the organisations involved in the project and public administration bodies. Attendees included members of the Besòs Tordera Consortium, the organisation leading the PAITIDA project; representatives from Amphos 21, the lead contractor; the Spanish National Research Council (IDAEA-CSIC); the University of Barcelona; iAquant; and the Catalan Water Agency.
Over the coming months, the facility will remain operational while the recharge process is monitored in detail. Researchers will assess reclaimed water infiltration, changes in piezometric levels, and groundwater quality through a dedicated monitoring network. The results will help determine the technical, environmental and economic feasibility of implementing larger-scale initiatives aimed at strengthening water availability for supply and enhancing the sustainability of the Besòs basin. All data generated will be integrated into the digital platform developed by the Consortium through other activities within the project.
The experience gained in La Llagosta will also contribute to generating knowledge that can be applied in other regions seeking innovative solutions for integrated water resource management, reinforcing the role of managed aquifer recharge as a strategic tool for climate change adaptation and water security.
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