Abstract
In this study, the effect of the vegetation and subsurface water level on nitrogen removal was elucidated based on two years performance obtained in a real scale vertical flow constructed wetland consisting of five-stage treatment. Neither presence of the vegetation and half-saturated condition had significant positive effect on nitrogen removal in the first year operation. It needs one year operation to stabilize ammonification and nitrification process and presence of the vegetation offered a significant improvement of TN removal in the second year. Stimulation of nitrogen removal was significant at downstream treatment stage among five-stage, resulting in a high overall nitrogen removal in the second year operation. This tendency was obvious especially in the vegetated condition regardless of the subsurface water level, suggesting no significant effect of half-saturated condition. Based on the variation of annual nitrogen removal through five-stage treatment, potential mechanisms of effect of the vegetation and subsurface water level on nitrogen removal were discussed.
