Efficiency of floating treatment wetlands planted with Iris pseudacorus and Glyceria maxima.

Global water shortages and declining water quality are critical challenges. Natural-based solutions (NBSs), such as floating treatment wetlands (FTWs), offer promising methods for water restoration and climate adaptation. This study evaluates the efficiency of FTWs planted with Iris pseudacorus and Glyceria maxima in improving water quality by removing nutrients and organic matter. Conducted in a controlled climate chamber, the experiments utilized treated wastewater in six tanks, with FTWs constructed from PE pipes, coconut mats, and hydroponic pots. The study spanned two sequential experiments, lasting 35 and 21 days, respectively. Results indicated that FTWs significantly enhanced pollutant removal compared to control tanks. Iris pseudacorus demonstrated higher removal rates for both phosphates and total nitrogen than Glyceria maxima. The presence of FTWs altered dissolved oxygen concentrations, pH, and oxidation-reduction potential, highlighting complex interactions between biological processes and physicochemical conditions. The study confirmed that FTWs can reduce hydraulic retention time for effective total nitrogen removal from 21 to 5 days. Algal growth, prominent in control tanks, was absent in FTW systems, likely due to nutrient competition and shading by macrophytes. The findings underscore the importance of plant species selection in FTW design and implementation. This study supports the potential of FTWs as a tertiary wastewater treatment method and a strategy for mitigating eutrophication.