Comparison of Four Nitrate Removal Kinetic Models in Two Distinct Wetland Restoration Mesocosm Systems

Abstract

Abstract:The objective of the study was to determine the kinetic model that best fit observed nitrate removal rates at the mesocosm scale in order to determine ideal loading rates for two future wetland restorations slated to receive pulse flow agricultural drainage water. Four nitrate removal models were investigated: zero order, first order decay, efficiency loss, and Monod. Wetland mesocosms were constructed using the primary soil type (in triplicate) at each of the future wetland restoration sites. Eighteen mesocosm experiments were conducted over two years across seasons. Simulated drainage water was loaded into wetlands as batches, with target nitrate-N levels typically observed in agricultural drainage water (between 2.5 and 10 mg L −1 ). Nitrate-N removal observed during the experiments provided the basis for calibration and validation of the models. When the predictive strength of each of the four models was assessed, results indicated that the efficiency loss and first order decay models provided the strongest agreement between predicted and measured NO 3 -N removal rates, and the fit between the two models were comparable. Since the predictive power of these two models were similar, the less complicated first order decay model appeared to be the best choice in predicting appropriate loading rates for the future full-scale wetland restorations.

Nitrate Removal by Floating Treatment Wetlands Amended with Spent Coffee: A Mesocosm-Scale Evaluation

“…A field-scale FTW study evaluated the removal of NO 3 -N following 17 storms throughout an establishment year and reported a median reduction of approximately 50%, which was significantly more NO 3 -N removal than the control pond (Borne et al, 2013). The NO 3 -N removal rates were likely less in that study compared to our study due to the lower NO 3 -N concentrations (~1 mg L -1 ), which have been found to reduce NO 3 -N removal rates (Messer et al, 2017c). In contrast, Winston et al (2013) found that NO 3 -N concentrations were significantly greater after implementa-tion of FTWs.…”

“…Significant differences in DO were observed between the coffee-amended treatments (Rush Coffee, Diverse Coffee, and Control Coffee) and all other treatments (Rush, Diverse, and Control) during the Summer 1 experiment ( = 0.05). Additionally, the coffee-amended mesocosms (including Control Coffee) established ideal anaerobic conditions for denitrification within three days of experiment initiation in both the Summer 1 and Summer 2 experiments (<2 mg L -1 ; Messer et al, 2017aMesser et al, , 2017cVymazal, 2007). Lower DO concentrations have been found in other full-scale FTW evaluations (Lane et al, 2016;White and Cousins, 2013).…”

“…NO 3 -N first-order removal rates were calculated for all mesocosms following each experiment using the first-order removal rate equation, which has been found to represent pulse-flow wetland systems as assessed in this study (Benjamin, 2010;Brezonik and Arnold, 2011;Messer et al, 2017c):…”

Correction: Messer, T.L.; Burchell, M.R.; Birgand, F. Comparison of Four Nitrate Removal Kinetic Models in Two Distinct Wetland Restoration Mesocosm Systems. Water 2017, 9, 517

“…The authors wish to make the following corrections to this paper [1]: (1): The author name "François Bírgand" should be François Birgand. …”

Improving the design of saturated riparian buffers for removing nitrate from subsurface drainage

“…coefficient Ks; in particular, the error in the actual denitrification rate is about 17% when C/Ks = 0.5 and 50% when C/Ks = 1, and accounting for the decrease in the removal rate at high concentrations would yield a larger required buffer width. In a study of denitrification beds (Ghane et al, 2015) and a study of wetlands (Messer et al, 2017), a first-order model better fit nitrate removal than a zeroth-order model did. Many values of Ks in soil have been reported, including 0.5 mg/L (Kinzelbach and Schäfer, 1991), 0.89 mg/L (Killingstad et al, 2002), and 10 mg/L, which is used in three of the models reviewed by Heinen (2006a).…”