efficiency and kinetic modeling of removal of nutrients and organic matter from a full-scale constructed wetland in qasr-e-shirin, iran

Background: this study assessed the removal of organic material and nutrients from fullscale subsurface flow (ssf) constructed wetlands (cws) followed by anaerobic stabilization ponds under environmental conditions. methods: the effluents were distributed evenly in 12 reed beds. sles were taken twice monthly for a total of 6 months from several points in the wetland. biochemical oxygen demand (bod), chemical oxygen demand (cod), total suspended solids (tss), and nutrient removal from the system and the longitudinal effect of the reed beds for removal of pollutions were determined. a fullscale model of flow, bod, and nutrients in ssf in the cws is presented. results: the flow rate and concentrations of parameters indicated that removal of organic matter and nutrients in the cold months decreased rather than in the hot months, as expected. the removal efficiency for bod, cod, and tss and the strongest biological interactions showed no uniform trends. the beds showed the highest removal rates in the first few meters of bed. the hybrid monodplug flow regime and the stoverkincannon models showed the best fit for the kinetics of the processes. umax in the stoverkincannon model was 3.64 mg/l.d for nitrogen and 0.24 mg/l.d for phosphorus. these values are very low, which indicates lower consumption and inefficiency of the system for removing nitrogen and phosphorus. conclusion: it can be concluded that the ssf in cws are able to treat average wastewater as effectively as common mechanical systems at lower cost.