Circular economy: water quality assessment for irrigation purposes in a constructed-wetland scenario

Abstract Water is an essential natural resource that sustains life and ecosystems. However, the increasing pressure on freshwater reserves due to climate change, rapid population growth, and industrialization is exacerbating the issue of water scarcity.In this context, wastewater reuse has emerged as a vital strategy to address water shortage. Also, it supports United Nations Sustainable Development Goals and aligns with the principles of the circular economy. In this context, phytoremediation seems to be a solution that aims an economically viable technique that employs plant species to purify water, thus contributing to water reuse. So, this study focuses on evaluating the feasibility of using treated wastewater from a constructed wetland for irrigation purposes. The investigation involved establishing a comprehensive monitoring plan, including sampling and analytical processes, followed by in situ and laboratory analyses of the collected water samples.The results indicate that the treated wastewater met the quality standards set by National and European legislation, for irrigation purposes. Some parameters demonstrating high removal efficiencies, such as chemical oxygen demand, total suspended solids and turbidity, with maximum removal efficiencies above 97%. The anions and potentially toxic elements showed very low values, being within the standards for water reuse for irrigation, except ammonium (NH₄⁺), which did not comply with any of the campaigns. The SAR, with a value of less than 2, was below the maximum recommended value (MRV) of 8.Overall, the findings support using treated wastewater from constructed wetlands for irrigation, which offers an effective solution for water reuse and contributes to environmental sustainability.