Coupling of partial nitrification and aerated vertical flow constructed wetland for enhancing nitrite removal and reducing nitrous oxide

High nitrous oxide (N2O) and nitrite (NO2--N) emission limit the application of the partial nitrification (PN) technology. A novel aerated vertical flow constructed wetland (VFCW) using waste gas from PN process was designed to enhance nitrogen removal and reduce N2O and NO2--N in PN process. Compared with unaerated VFCW, NH4+-N and TN removal efficiencies in aerated VFCW were significantly improved by 118.48% and 78.14%, respectively. Furthermore, the aerated wetland mode can effectively eliminate the problem of high NO2-- N and N2O pollution. After VFCW purification, the NO2--N concentration was reduced from 17.07 mg/L to 0.34 mg/L. Meanwhile, the N2O removal rate could reach 88.72%. Microbial analysis showed that the higher mi-crobial community abundance and more fully nitrification and denitrification process were found in aerated VFCW, led to its reduced NO2--N and N2O emission.