Nitrogen transformations and mass balance in an integrated constructed wetland treating domestic wastewater.
Nitrogen (N) transformations and removal in integrated constructed wetlands (ICWs) are often high, but the contributions of various pathways, including nitrification/denitrification, assimilation by plants and sediment storage, remain unclear. This study quantified the contributions of different N removal pathways in a typical multi-celled ICW system treating domestic wastewater. Findings showed near complete average total N retention of circa 95% at 102.3 g m⁻² yr⁻¹ during the 4-year period of operation. Variations in total N and NH4-N removal rates were associated with effluent flow volume rates and seasons. According to the mass balance estimation, assimilation by plants and sediment/soil storage accounted for approximately 23% and 20%, respectively, of the total N load removal. These were the major N removal route besides microbial transformations. Thus, the combination of plants with high biomass production offer valuable opportunities for improving ICW performance. The retrieval and use of sequestered N in the ICW sediment/soils require coherent management and provide innovative and valuable opportunities.
Centre for Water Resources Research, School of Civil, Structural and Environmental Engineering, Newstead Building, University College Dublin, Belfield, Dublin 4, Ireland E-mail: mawuli_dzkps@yahoo.com.au; Civil Engineering Research Group, School of Computing, Science and Engineering, Newton Building, The University of Salford, Salford M5 4WT, UK.
Mawuli
M
Dzakpasu
Civil Engineering Research Group, School of Computing, Science and Engineering, Newton Building, The University of Salford, Salford M5 4WT, UK.
Miklas
M
Scholz
Centre for Freshwater and Environmental Studies, North Building, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland.
Valerie
V
McCarthy
Centre for Freshwater and Environmental Studies, North Building, Dundalk Institute of Technology, Dundalk, Co. Louth, Ireland.
Siobhán
S
Jordan
D007494:Ireland; D009584:Nitrogen / Q000378:metabolism*; D010944:Plants / Q000378:metabolism*; D012621:Seasons; D062065:Wastewater / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000378:metabolism*; D018508:Water Purification / Q000592:standards*; D053833:Wetlands
D009584:Nitrogen; D062065:Wastewater; D014874:Water Pollutants, Chemical