Role of different plants on nitrogen and phosphorus removal at low temperature in lab-scale constructed wetlands

In this study, plant growth and nitrogen and phosphorus removal efficiency in lab-scale CWs by five plants (H. vulgaris, N. peltatum, N. tetragona, N. pumilum, S. trifolia ) in winter in Sichuan basin was evaluated. H. vulgaris and N. tetragona would well adapt to the winter wetland environment, and the relative growth at the end of the experiment was 89.83% and 66.85%, respectively. In winter, H. vulgaris kept growing with accumulated stems and leaves, while growth of N. tetragona was mainly caused by the growth of roots and stems underwater. In addition, during the winter, removal efficiencies were 66.29%, 57.47%, 54.78%, 55.47%, 41.66% of TN and 62.40%, 69.75%, 69.97%, 65.65%, 76.55% of TP for each planted CWs respectively. The results indicated that the removal of nitrogen and phosphorus from CWs was mainly achieved by substrate, while a small portion was attributed by plant. However, plants like H. vulgaris and N. tetragona , in the CWs in winter can play the role of landscaping. Thus, H. vulgaris could be considered as a suitable and effective nutrient removal plant for treatment of nitrogen and phosphorus water in winter wetlands in Sichuan basin.