Spain, as most other Mediterranean countries, faces near future water shortages, generalized pollution and loss of water dependent ecosystems. In Spain, the Llobregat River and aquifers, which supply water to Barcelona, have been overexploited and suffer, therefore, from serious damages: the river dries up on summer, riparian vegetation has disappeared and seawater has intruded the aquifer. Water stress is a major global problem that needs to be addressed in a sustainable approach. In this context, Managed Aquifer Recharge (MAR) can play an important role thus providing benefits such as (i) storage capacity to cope with seasonal fluctuations of water demand, (ii) protection of coastal aquifers from saltwater intrusion, (iii) mitigation of the depletion of groundwater levels and (iv) additional natural treatment when low quality water is recharged.
On the other hand, recent development of analytical techniques has allowed detecting the presence of the so-called “emerging organic micropollutants” in water and soils. Such compounds may affect living organisms when occurring in the environment at very low concentrations (microg/l or ng/l). In wastewater and drinking water plants, a remarkable removal of these chemicals from water can be obtained only using advanced and costly treatments. Nevertheless, a number of studies are demonstrating that physical, chemical and biochemical processes associated with water movement within the subsoil represent a natural alternative way to reduce the presence of these contaminants. This processes are called Soil Aquifer Treatment (SAT).
In order to improve the quantity and quality of the upper Llobregat aquifer two recharge systems located at Sant Vicenç dels Horts (SVH) and Santa Coloma has been constructed in 2007 in the Barcelona area. Each of these MAR sites consists of a decantation and an infiltration pond and recharge water will come mainly from the tertiary effluent of the El Prat del Llobregat WWTP. For aquifer recharge to become a source for indirect potable reuse purposes, all contaminations with pathogens as well as organic and inorganic pollutants should be avoided. To this end, understanding and enhancement of the degradation biogeochemical processes occurring within the aquifer during infiltration is capital. This project aims at improving the quality of the recharge water at Sant Vicenç dels Horts MAR site by means of the implementation of an organic substrate layer for enhancing Soil Aquifer Treatment (SAT).