[Modeling nitrogen transformation in a novel circular-flow corridor wetland].

Nitrogen transformation and removal in a novel circular-flow corridor (CFC) wetland was simulated. A computer model covering 6 nitrogen forms, 3 media and 10 transferring pathways, was developed. The results show that the TN removal is attributed to zeolite adsorption (53.3%), plants NH4(+) -N uptake (27.6%), denitrification (10.2%), plants NO3(-) -N uptake (2.9%) and short-cut denitrification (1.5%). The major removal pathway for NH4(+) -N varies from season to season. In January, the zeolite adsorption played the most important role in NH4(+) -N removal with a contribution of 84.5%. From April to June, the plants uptake accounted for 76.4%-85.3% NH4(+) -N removal. While in July, there were three removal pathways, namely zeolite absorption (36.1%), nirtosation (45.8%) and plants uptake (21.4%), playing an important role in nitrogen removals. Additionally, regular plants harvesting, periodical zeolite regenerating and aquatic plants growing can improve the TN removal rate by 1.7%-7.7%, 43.1%-72.2% and 19.8%-36.2%, respectively. In short, it is by the diverse removal pathways in CFC wetland that nitrogen can be continuously removed.