Variation in the Efficiency of Nutrient Removal in a Pilot-Scale Natural Wetland

This two-year study focused on mechanisms of nutrient removal efficiency and variation in this efficiency in a pilot-scale natural wetland with different macrophyte species. Effects of plant harvesting and the differences among plant species ( Ceratophyllum demersum , Nelumbo nucifera , Zizania latifolia , Hemarthria sibirica , Phragmites communis , and Typha orientalis ) were investigated. Results show that the mean retention of total nitrogen (N), total dissolved N, ammonia N, nitrite N, total phosphorus (P), total dissolved P, and phosphate P in the second year was generally lower than that found in the first year. Harvest of above-ground macrophytes had a beneficial effect on retention capacity, especially for total dissolved N and ammonia N, whereas an increase in nutrient concentration was observed in zones that were not harvested. The total N removal efficiency had a positive relationship with inflow loading. A mixture of Z. latifolia and T. orientalis demonstrated the best potential for both N and P retention.