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

•Effect of influent C/N ratios on nitrogen removal and N2O emission was studied.•Higher removal of NH4+-N (98%) and TN (90%) was achieved at C/N ratio of 12.•Low N2O emission accounting for 1.44% of TN removal was found at C/N ratio of 12.•Results would be useful for improving the sustainability of CW treatments.

In order to design treatment wetlands with maximal nitrogen removal and minimal nitrous oxide (N2O) emission, the effect of influent C/N ratios on nitrogen removal and N2O 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 N2O emission in CWs were significantly affected by C/N ratio of influent. Much higher removal efficiency of NH4+-N (98%) and TN (90%) was obtained simultaneously in SF CWs at C/N ratios of 12:1, and low N2O emission (8.2 mg/m2/d) and the percentage of N2O-N emission in TN removal (1.44%) were also observed. These results obtained in this study would be utilized to determine how N2O fluxes respond to variations in C/N ratios and to improve the sustainability of CWs for wastewater treatment.

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