A Vegetation Filter (VF), a type of Land Application System, is a non-conventional water treatment technology where wastewater and/or treated water is applied for the irrigation of a forestry plantation.
The aims of this study are i) quantify the removal capacity of one VF in terms of Contaminants of Emerging Concern (CECs) and ii) assess the capacity of VFs to increase groundwater resources.
For this purpose, two VFs of 56 m² with a planting density of 10,000 plants/ha of Populus x euroamericana (clone I214) were installed in an experimental plot at IMDEA Water Institute (Alcalá de Henares, Madrid) in 2016.
The impact of both filters in its underlying groundwater after three years of operation has been evaluated, paying attention to the influence of the VF on groundwater recharge and dynamics, based on piezometric level measurements and hydric balance calculus. To assess the infiltrating water quality, the study shows the results of two years of water monitoring in different control points: wastewater influent, infiltrating water below one of the VFs and groundwater.
The obtained results indicate that the constant operation of the VFs has contributed to recharge the underlying aquifer. Both, local piezometry and underground flow have been modified due to the water infiltration from the VFs.
Regarding the infiltrating water quality, there is an attenuation of CECs, especially in the first few centimetres of soil, due to sorption and biodegradation processes. Thus, groundwater analysis show that both concentrations and detection frequency of these contaminants greatly decreases in the aquifer.
To enhance these results, woodchips have been added to soil in VFs. This amendment has the advantage of being provided from the IVF itself following therefore a sustainable and resource recovery approach. We expect that woodchips increase sorption sites and stimulate microbial activity.
This study belongs to the project "FILVER+: Water reclamation by using a new concept of land application systems", with the reference CTM2016-79211-C2 (AEI/FEDER, EU), and it is part of the 2016 call for R+D+i projects of the Spanish Ministry of Economy, Industry and Competitiveness.
Keywords: Reclaim, Recharge, Contaminants of Emerging Concern, Vegetation filters.