A syntetic stormwater recipe for assessing a pilot hybrid constructed wetland reliability in Mediterranean climate

Decentralized systems for effective water management has been clearly described as one of the best practice (BMPs) strategies for promoting the circular economy. The recovery and reuse of natural resources, water in primis, can be pursued through different approach and technologies, variously engineered and/or more likely as nature-based solutions (NBs). In the cities of the future, the chance to rely on unconventional and diffuse water source like stormwater runoff is becoming necessary, but more knowledge on stormwater treatment facilities and performances are required. This study investigates the reliability of a pilot hybrid constructed wetland (H-CW) (Fig. 1) in treating contaminants typically found in stormwater runoff.To cope with the uncertainty in performing representative sampling during storm events, particularly in Mediterranean conditions, with increasingly longer periods of drought and short intense precipitations, a recipe for synthetic stormwater has been proposed and tested for documenting the removal efficiency along the length of the treatment train (μgL-1 Cd, Cr, Fe, Pb, Cu, Zn, total hydrocabons: 5,30,3000,100,80,500,30000). Intensive monitoring activities were conducted during one month and quality analyses regarded the three matrices of the system: water, biomass (Canna indica, Typha latifolia) and filtering medium (volcanic gravel, porosity 0.4). First evaluations showed very high removal efficiency for all the metals (97-99%, except for Fe, 67%) and the total hydrocarbons (95%), mostly at the outlet of the HF units (sampling point #3, Fig.1). Furthermore, among the analysed macrophytes organs, the hypogeal parts presented higher metal concentrations, generally more prevailing in the roots than in the rhizomes, assuming probable biostabilization processes.