A comparative study on nitrogen and phosphorus removal performance for three types of constructed wetlands

A pilot-scale experiment was conducted to compare the nitrogen and phosphorus removal performance among the constructed wetlands with a zeolite media substrate, a gravel media substrate, and a soil layer (free surface), respectively. For comparison, we kept a 1 day hydraulic retention time , and fed with the same wastewater in the experiment. The experimental results show that for the zeolite wetland the total nitrogen removal rate is close to 60%, for the gravel wetland phosphorus removal rate is 70% the highest, and the nitrogen and phosphorus removal rate for free surface constructed wetland are between those for zeolite and gravel wetlands. The different nitrogen and phosphorus removal mechanisms for these three wetlands are discussed, and the economic efficiency and operating scheme are compared.