Advances in Iron-Based Constructed Wetlands: Mechanisms, Efficiency Enhancement, and Optimization Pathways

Iron mineral-based constructed wetlands (IMCWs) have garnered considerable attention due to their remarkable efficiency in the removal of various pollutants, including nutrients, organic compounds, and heavy metals. The incorporation of iron minerals in constructed wetlands primarily enhances pollutant removal through redox reactions, adsorption, ion exchange, and microbial degradation. IMCWs present a promising water treatment technology with significant potential for widespread application, while existing studies indicate that IMCWs still face several challenges, including the limited long-term performance of iron mineral substrates, passivation during prolonged operation, and instability of microbial communities. To enhance the efficiency and sustainability of IMCWs, researchers have proposed various optimization strategies, such as the selection of suitable iron minerals, improvements in system design, and refinements in operational modes. This study thoroughly summarizes the removal performance of various pollutants, mechanisms of pollutant removal, optimization strategies, and system configurations for the effectiveness of IMCWs. Further researches should focus on the development of integrated IMCWs with other wastewater treatment technologies, regeneration, and recycling of substrates.