Dynamics of micropollutant removal in a constructed wetland treating stormwater from a residential urban catchment area in France
The aim of this study was to assess the fate of pollutants and micropollutants in an extensive treatment system and to evaluate its efficiency. The experimental site is located in Strasbourg, France. Stormwater from a residential watershed (27 100 m2) is released into a sedimentation pond, followed by a vertical flow constructed wetland and finally into a water course. The instrumentation consists of an on-site weather station and three automatic samplers. These samplers are located in three points: inlet pipe, pond and constructed wetland outlet. Total suspended solids (TSS), total organic carbon (TOC), total phosphorus (P), total nitrogen (N), heavy metals and polycyclic aromatic hydrocarbons (PAHs) are measured. Seven sampling campaigns were carried out from October 2015 to October 2016. Pollutants (TSS, TOC, N) and chromium were detected at low concentrations (TSS < 18 mg∙L-1, TOC < 8 mg∙L-1, N < 7 mg∙L-1, Cr < 5 μg∙L-1). Zinc and five PAHs were detected in high concentrations that are harmful for aquatic life (Zn = 100-360 μg∙L-1, PHAs = 10-60 μg∙L-1). After five years of operation, the treatment system is efficient in removing pollutants and micropollutants in stormwater.