Constructed wetlands in circular economy approaches for wastewater treatment: a mini review

The circular economy (CE) promotes sustainable resource management through waste reduction, reuse, and recovery. In this context, constructed wetlands (CWs) have emerged as a promising technology for wastewater treatment. This review examines the role of CWs in CE by analyzing their capacity for nutrient recovery, water reuse, and biomass valorization. CWs offer significant advantages, including low operational costs, minimal energy requirements, and environmental benefits such as habitat creation. Nevertheless, their real contribution to circularity remains limited and poorly quantified. Major challenges include high land demand, limited scalability, lack of standardized performance indicators, and insufficient evidence regarding the removal of complex pollutants. Additionally, regulatory and technological gaps restrict their widespread implementation. Therefore, CWs should be understood as part of integrated systems, requiring improved evaluation frameworks and technological innovation to enhance their effectiveness within CE strategies.