Characterization of Constructed Wetlands: A Safe and Sustainable Solution for Water Resources Treatment—An Overview

Water scarcity and pollution from anthropogenic sources pose significant global challenges, requiring sustainable and cost-effective wastewater treatment solutions. This study explores the potential of constructed wetlands as a nature-based solution for wastewater treatment. Additionally, it explores their role in resource recovery, aligning with circular economy principles and the United Nations Sustainable Development Goals. Constructed wetlands replicate natural wetland ecosystems, using essential macrophytes and different substrates to remove pollutants from wastewater. The study begins with an overview of natural wetlands and their ecological significance, highlighting their roles in water purification, flood control, and biodiversity conservation. It then examines the design and operation of constructed wetlands, including surface flow and subsurface flow systems. The study further investigates the mechanisms of pollutant removal in constructed wetlands, the importance of plant selection, and system maintenance for achieving optimal performance. A case study is presented on a constructed wetland implemented within an eco-friendly dog shelter in Portugal. This system treats wastewater from animal enclosures, demonstrating the practical application of this nature-based solution in a real-world scenario. The performance of the system was assessed based on the removal rates of key water quality parameters, including chemical oxygen demand, total suspended solids, and ammonium. The results indicate that the constructed wetlands effectively reduce most of these parameters to levels meeting national and European standards for irrigation water. However, ammonium removal requires further optimization. The study concludes that constructed wetlands provide a sustainable alternative to conventional wastewater treatment technologies. Their low energy needs, minimal maintenance, and potential for water reuse make them an attractive option for addressing water scarcity and pollution challenges. Further research is recommended to optimize their designs for enhanced pollutant removal and to explore their application across different environmental conditions.