Adaptability of wastewater wetland models in estimating nutrient removal in a stormwater wetland on dry days

摘要

Several types of nutrient removal models, which were developed for wastewater wetlands, were applied to the data collected from a wetland treating stormwater runoff from extensive cow feeding area. First-order and regression equations were used and calibrated to estimate the removal of total phosphorus (TP), ammonium (NH_4-N), total kjeldahl nitrogen (TKN), and total nitrogen (TN). To evaluate the performance of the models, the coefficient of determination (R~2), relative root mean square error (RRMSE), and model efficiency (ME), were determined. The first-order models developed produced a good prediction of the effluent TP concentration with R~2 = 0.79, RRMSE = 0.23, and ME = 0.66. On the other hand, the regression models produced very good predictions of effluent NH_4-N, TKN, and TN concentrations with R~2 ＞ 0.70, RRMSE ＜ 0.40, and ME ＞ 0.70. Therefore, the models for wastewater wetlands can be used to estimate the nutrient removal in stormwater wetlands during dry days. The removal of nutrients was greatly affected by hydraulic loading rate which means that the surface area of the wetland is the critical design factor in terms of pollutant removal. Moreover, increasing the surface area of the wetland increases nutrient removal through nitrification/denitrification and sedimentation as well as plant and microbial uptake.