Seasonal variation of nutrient removal in a full-scale horizontal constructed wetland

The main objective of the present study was to evaluate the difference in removal efficiency (RE) of nitrogen and phosphorus compounds based on the seasonal changes in a full-scale gravel-based horizontal subsurface flow constructed wetland located in Interior Central Region of Portugal. The RE of nitrogen and phosphorus compounds were relatively poor, but the results allow us to conclude that season had a significant (p<0.05) effect on the RE of TN, NH4+-N, NOx-N, TP and DP, with higher values in spring-summer period (10.4%, 10.4%, 3.4%, 27.5% and 26.1%, respectively) than in autumn-winter (0%, -7.7%, -9.8%, 12.9% and 0%, respectively).