Numerical modelling on sorption kinetics of nitrogen species in wastewater-applied agricultural field.

A one-dimensional numerical model is developed to simulate the nitrogen species in wastewater-applied agricultural field to investigate the effect of various isotherms of ammonium nitrogen and nitrate nitrogen. Results suggest that the ammonium nitrogen concentration reaches up to the depth of 40, 25 and 16 cm due to the linear, Freundlich and Langmuir isotherms of ammonium nitrogen, which is corresponding to the reduction in migration depth up to 37% by Freundlich isotherm and 55% by Langmuir isotherm as compared with linear isotherm. Similarly, the peak concentration of 25, 15 and 12 mg/l of nitrate nitrogen is observed during linear, Freundlich and Langmuir isotherms of NH₄-N, respectively. Further, the results show that 4% peak concentration reduction is experienced for NO₃-N due to the linear NH₄-N sorption alone, 7% peak reduction is observed for NO₃-N concentration by Freundlich NH₄-N sorption alone, and 12.5% peak reduction is monitored for NO₃-N concentration due to Langmuir NH₄-N sorption alone compared with the combination of Freundlich NO₃-N sorption. The numerical results suggest that the combination of Langmuir isotherm of NH₄-N and Freundlich isotherm of NO₃-N is identified as a best combination of isotherm scenario, which mitigates the NO₃-N contamination in groundwater resources. [ABSTRACT FROM AUTHOR]