Study on Improvement of Pollutants Removal Efficiency by Backside Aeration in Wavy Subsurface-Flow Constructed Wetland

Abstract

Lower removal rates of ammonium nitrogen in the constructed wetlands were mainly caused by the lack of dissolved oxygen (DO). The traditional wavy subsurface-flow constructed wetland was modified to install an aeration tube in the third wave interval to increase DO and the nitrification rates within the constructed wetlands. As most COD had been removed in the second wave interval, nitrifying bacteria became dominant in the third wave interval, which led to the nitrification extent to reach more than 95%. The ability to endure the impact of hydraulic loading was also enhanced. The hydraulic loading of wetlands was raised up to 0.8m³/m²ldrd^-1, with a COD organic loading of 56-112 g COD/m²ldrd^-1, and ammonium loading rates about 20-28 g NH₄ ⁺-N/m²ldrd^-1. These values were much higher than those reported of nitrification in constructed wetlands.