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Water 2017, 9(9), 691;

Adapting the Relaxed Tanks-in-Series Model for Stormwater Wetland Water Quality Performance

Biological & Agricultural Engineering, North Carolina State University, Campus Box 7625, Raleigh, NC 27695, USA
Civil and Environmental Engineering, University of Tennessee, 415 John D. Tickle Building, Knoxville, TN 37996-2010, USA
Author to whom correspondence should be addressed.
Received: 15 July 2017 / Revised: 18 August 2017 / Accepted: 4 September 2017 / Published: 9 September 2017
(This article belongs to the Special Issue Treatment Wetlands for Nutrient Removal)
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Across the globe, water quality standards have been implemented to protect receiving waters from stormwater pollution, motivating regulators (and consequently designers) to develop tools to predict the performance of stormwater control measures such as constructed stormwater wetlands (CSWs). The goal of this study was to determine how well the relaxed tanks-in-series (P-k-C*) model described the performance of CSWs in North Carolina. Storm events monitored at 10 CSWs in North Carolina were used for calibrating the model, and statistical evaluations concluded the model could adequately predict the performance for all pollutants except organic nitrogen. Nash–Sutcliff calibration/validation values were determined to be 0.72/0.78, 0.78/0.74, 0.91/0.87, 0.72/0.62, 0.88/0.73, and 0.91/0.63 for total nitrogen, total ammoniacal nitrogen, oxidized nitrogen, organic nitrogen, total phosphorus, and total suspended solids, respectively. Sensitivity analysis revealed only one calibration parameter with strong sensitivity, the Arrhenius coefficient (temperature dependent model coefficient). With this model, CSWs can be optimized to treat watershed-specific influent concentrations to meet effluent targets. In general, the current design technique used in North Carolina and many other locations (a first flush volume detention method) oversizes CSWs for water quality vis-à-vis the method herein, suggesting improved designs for water quality may be possible through scientifically-informed methods. View Full-Text
Keywords: stormwater; wetlands; kinetics; water quality; hydrodynamics; modeling; design; rate constant stormwater; wetlands; kinetics; water quality; hydrodynamics; modeling; design; rate constant

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Merriman, L.S.; Hathaway, J.M.; Burchell, M.R.; Hunt, W.F. Adapting the Relaxed Tanks-in-Series Model for Stormwater Wetland Water Quality Performance. Water 2017, 9, 691.

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