Twelve-Year Performance of a Constructed Wetland for Municipal Wastewater Treatment: Water Quality Improvement, Metal Distribution in Wastewater, Sediments, and Vegetation

Constructed wetlands have been successfully used throughout the world for wastewater treatment. Nowadays, one of the most discussed questions is their long-term performance. The present study summarizes the performance of a constructed wetland designed to treat the municipal wastewater from a rural community in northwestern Spain during a period of 12 years. The monitoring of water quality for organic matter, suspended solids, nutrients, and indicator bacteria revealed that, in general, the effluent concentrations were significantly lower than influent concentrations. Moreover, differences among years were not statistically significant. Metals and metalloids were also monitored in wastewater, sediment, and vegetation. Results showed that these pollutants have mainly accumulated in the sediments, whereas only a minor fraction has been removed by plant uptake.