It has been generally accepted that microbial process was
the main mechanism for TN removal in CWs. In addition, NH3
volatilization and adsorption of granular nitrogen and NH4
+ in bed
media as well as plant uptake can also contribute to TN removal
(Kadlec and Knight, 1996; Vymazal et al., 1998; Bachand and Horne,
2000; Vymazal, 2007). In our study, TN removal through NH3
volatilization could be neglected due to the pH of the wetland
beds (≤7.6) (Kadlec and Knight, 1996).