Nutrients and Organic Matters Removal in a Full Scale Constructed Wetland; Efficiency and Kinetic Modeling

This study assessed the removal efficiency of organic material and nutrients from subsurface flow constructed wetland followed by anaerobic stabilization ponds under environmental conditions. The pond effluents were distributed evenly into 12 reed beds. Samples were taken as 2 times per month with 6 months duration from several points in the wetland context. The organic matter (BOD, COD), TSS and nutrient removal of the system and also longitudinal effect of reed beds in the removal of the various pollutions were determined. Meanwhile, a numerical modeling effort of flow and Biochemical Oxygen Demand (BOD) fate and nutrients in subsurface flow (SSF) constructed wetlands (CWs), under full scale conditions, were presented. The obtained results of flow rate and concentration of selected parameters indicated that capability of SSF wetlands in removal of organic matter and nutrients in the cold season were less than warm months, as expected. The removal efficiency of BOD, COD, and TSS and also the greatest biological interactions didn’t have a uniform trend and the bed had the highest removal rates in the first few meters of the bed. The hybrid model of Monod - Plug flow regime and also another model, Stover-Kincannon, showed better fitness to accounting the kinetics of processes. The amount of Umax in StoverKincannon model for nitrogen and phosphorus was 3.64 and 0.24 mg/L.d, respectively which are very low, that indicate less consumption and inefficiencies of system for removing nitrogen and phosphorus.

Keywords:

Wetland , Nutrient , Organic matter , kinetic modeling