Denitrifying sites in constructed wetlands treating agricultural industry wastes: A note

The denitrification potential (rate of denitrification under anoxic conditions and in the presence of excess nitrate and glucose) was measured in different zones of constructed wetlands receiving anaerobic/aerobic treated meat processing and dairy‐shed effluents. The wetland receiving meat processing effluent was of the surface flow type and about 67% of the influent nitrogen was in the nitrate form. Most of the denitrifying potential in this wetland was in the surface mat of decaying plant material. The dairy‐shed wetland was of the subsurface flow type and received an effluent that contained little nitrate (<1%). In this wetland denitrifying potential increased from the inlet to the outlet. The patterns of denitrifying activity suggest that nitrogen removal in wetland systems may be improved by better contact between the effluent and decaying plant material on the wetland surface.