Fitoremediação de microplásticos presentes nas águas residuais urbanas tratadas: remoção, dinâmica e destino.

The current water crisis is one of the greatest challenges of our time so, a water circular economy approach may reduce pressure on natural resources, minimize waste and decrease pollution. Microplastics (MP) pollution and climate change further intensify pre-existing water stresses. Moreover, the fate of MP is affected by their interaction with the media in the environment, including particle mobility and transport processes during the discharge of treated urban wastewater into the water bodies. Despite wastewater treatment plants relatively efficient MP removal rates (around 90%), they are also point sources of MP release into the environment which may cause serious health effects to aquatic animals and humans. Moreover, the removal of MP in these effluents will greatly contribute to the possibility of their safe reuse in, for example, agriculture activities (in crop irrigation) increasing food safety. The Alentejo region appears to be experiencing a process of rapid agricultural intensification, regardless of its dry Mediterranean climate and a tradition of extensive, multi-functional agricultural systems. Though the two types of production continue to coexist, the transition from a long-lived model of extensive agricultural production toward a predominantly intensive mode of agriculture practices has been extremely fast in the region. To prevent severe water stress, the need of new efficient management practices or novel sources of crop irrigation are in urgent need. Bearing the aforementioned in mind, the project aims the use of phytoremediation, as a sustainable nature-based solution, for the removing of MP remaining in treated urban wastewaters, with the goal of its safety reuse in irrigation. Vertical flow constructed wetlands (VFCW) planted with Vetiveria zizanioides, at laboratorial scale, and treated urban wastewater from a local wastewater treatment plant will be used. Thus, the main goals of this work are: 1) to assess the capacity and efficiency of removing MP of VFCW, as a phytoremediation system, and their ideal operational conditions; 2) to evaluate how Vetiveria zizanioides cope when exposed to effluents with MP and the plant’s role in the treatment; 3) to clarify if the VFCW filling matrix also have a role in the overall MP removal efficiency; 4) to establish if the treated effluent can be reuse in agricultural activities analysing the impact to aquatic and terrestrial ecosystem using ecotoxicological assessment; 5) to assess the technical-economic and environmental sustainability of the established phytoremediation system, in a circular economy approach, considering its possible implementation on a full-scale treatment system.