Microbial nitrogen removal pathways in integrated vertical flow constructed wetland systems.
Microbial nitrogen (N) removal pathways in planted (Canna indica L. and unplanted integrated vertical flow constructed wetland systems (IVCWs) were investigated. Results of, molecular biological and isotope pairing experiments showed that nitrifying, anammox, and denitrifying bacteria were distributed in both down flow and up flow columns of the IVCWs. Further, the N transforming bacteria in the planted IVCWs were significantly higher than that in the unplanted ones (p<0.05) Moreover, the potential nitrification, anammox, and denitrification rates were highest (18.90, 11.75, and 7.84nmolNg( 1)h( 1) respectively) in the down flow column of the planted IVCWs. Significant correlations between these potential rates and the absolute abundance of N transformation genes further confirmed the existence of simultaneous nitrification, anammox, and denitrification (SNAD) processes in the IVCWs. The anammox process was the major N removal pathway (55.6 60.0% in the IVCWs. The results will further our understanding of the microbial N removal mechanisms in IVCWs.
Bioresource technology