Posada en marxa i avaluació de la paret verda per al tractament i reutilització d’aigua gris a l’Institut Català de Recerca de l’Aigua

Abstract

In the current scenario of water scarcity, Nature-Based Solutions (NBS) are identified as sustainable strategies for decentralized treatment and reuse of urban wastewater. These solutions, which combine purification efficiency with multiple environmental and social co-benefits, include green walls, especially suitable for densely built-up urban environments. These structures allow on-site treatment of greywater, facilitating its reuse for non-drinking uses. This particular study is part of the SBN research line, which includes the objective of assessing the feasibility of implementing a green wall in the building of the Catalan Institute for Water Research (ICRA) for the treatment and reuse of greywater generated in the center itself for non-potable uses, in line with the Royal Decree Law 1085/2024, of October 22, which regulates the requirements for water reuse in different applications. The installed system consists of four hybrid sectors, each integrating a vertical flow module and a horizontal subsurface flow module. The planters were filled with LECA and perlite used as substrate and two different ornamental or edible plant species were planted in each sector. Subsequently, the hydraulic retention time of each sector was calculated for comparison. To evaluate the efficiency of the system, water samples were taken at both the inlet and outlet of each sector, measuring key physicochemical parameters (BOD₅, TSS, TOC, cations and anions). Despite obtaining high removal efficiencies in BOD₅ (74%) and TOC (78%), an accumulation of certain ions and suspended solids was observed. So that the output water did not achieve any of the requirements for reuse in irrigation or toilet flushing

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