Nitrogen removal and nitrous oxide emission in surface flow constructed wetlands for treating sewage treatment plant effluent: Effect of C/N ratios.

In order to design treatment wetlands with maximal nitrogen removal and minimal nitrous oxide (NO) emission, the effect of influent C/N ratios on nitrogen removal and NO emission in surface flow constructed wetlands (SF CWs) for sewage treatment plant effluent treatment was investigated in this study. The results showed that nitrogen removal and NO emission in CWs were significantly affected by C/N ratio of influent. Much higher removal efficiency of NH-N (98%) and TN (90%) was obtained simultaneously in SF CWs at C/N ratios of 12:1, and low NO emission (8.2mg/m/d) and the percentage of NO-N emission in TN removal (1.44%) were also observed. These results obtained in this study would be utilized to determine how NO fluxes respond to variations in C/N ratios and to improve the sustainability of CWs for wastewater treatment.