Abstract: To study the effects of plant diversity on the nitrogen removal efficiency in constructed wetland, a simulated constructed wetland with monoculture and mixed planting of four plant species was established, and nitrate was supplied periodically to simulate the sewage nitrogen inflow. In the mixed planting system, the effluent nitrate concentration was significantly lower than that in monoculture system (P<0.05), but the substrate nitrogen and plant nitrogen had no significant difference between the monoculture and mixed planting systems. The denitrification rate in the mixed planting system was higher than that in the monoculture system. The nitrogen removal efficiency in monoculture system Coix lacrymajobi was significantly higher than that in the monoculture systems Typha angustifolia,Phragmites australis, andAcorus calamus, and no significant differences were observed between the latter three monoculture systems. This study showed that higher nitrogen removal from constructed wetlands could be achieved by mixed planting of multiple species with high nutrient removal efficiency.

Key words: graphene, carbon nanomaterials, transport, sorption, ecological risk.