Smith, L. K.. University of Colorado/CIRES, smithlk@spot.colorado.edu
Sartoris, J. K.. U.S. Geological Survey, James_J_Sartoris@usgs.gov
Thullen, J. S.. U.S. Geological Survey, Joan_Thullen@usgs.gov

 
NITROGEN REMOVAL MECHANISMS IN A SOUTHERN CALIFORNIA CONSTRUCTED WASTEWATER TREATMENT WETLAND
 
Input/output models have demonstrated the efficacy of using constructed wetlands to remove nitrogen from secondary effluent. Denitrification has been assumed as the primary removal mechanism by these wetlands, however empirical data on denitrification rates as well as other removal pathways are lacking. To provide such data, the dynamics of N transformations were studied over a 2-year period within the Hemet/San Jacinto Demonstration Wetland (HSJDW), which receives 3785-7570 cubic meters per day of secondary effluent. Daily inflow and outflow volume data were combined with weekly water quality measurements to estimate the mean daily N mass balance. The HSJDW was responsible for removal of ca. 30% of the total N inputs over the study period. Denitrification rates, determined by membrane inlet mass spectrometry, accounted for a small fraction (<20%) of the total average N removed by the wetland. N uptake by the macrophytes was responsible for the majority of the N removal, but cannot be viewed as a permanent removal mechanism because of internal N loading upon plant die-back. N removal efficiencies declined over the second half of the study period (from 60% to 30%) possibly in response to internal loading. Vegetation harvesting is being investigated as a means of reducing internal N loading.
 
Day: Monday, Feb. 1
Time: 02:15 - 02:30pm
Location: Hilton of Santa Fe
 
Code: SS06MO0215H