| A constructed wetland for the treatment of agricultural wastewater from a 150-cow dairy operation in eastern Ontario, Canada was monitored in its eighth operating season to evaluate the proportion of TN (approximated by TKN due to low NO3-) and TP removal that could be attributed to storage in Typha spp., which dominate this system. Nutrient loading rates were high, with 16.2 kg/ha/d N and 3.4 kg/ha/d P entering the system. Nutrient removal at the wetland was considerable, with TKN and TP removal efficiencies of 69.7% and 39.7%, respectively for the 2003 operating season. Plant uptake accounted for 0.7% of TKN removal when vegetated components were considered together. However, separately, in the cell with lower N and P loading rates, plants accounted for 9% of TKN and 4.6% of TP removal, and 21.4% of NH4+ removal. Plant uptake was significant to overall removal given wetland age and nutrient loading. |
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