Nitrogen removal kinetics in wastewater stabilization pond systems in Greece

This paper refers to the dynamic of nitrogen removal in wastewater stabilization ponds (WSP) in Northern Greece. Three full-scale WSP systems treating municipal wastewater and consisting of one facultative pond, one or two maturation ponds and a rock filter before the final discharge were investigated. Systems were monitored during a year. The kinetic constants of TN,NH4 +/-, N-NO3- removal were determined. For this aim the first-order model, the second-order model, the Kadlec and Knight model, the Stratton model and the Reed model were used. The models assessment, the accuracy and reliability of the results are evaluated by comparison with existing real data. The Kadlec and Knight model give the best adjustment. The biodegradation rate constant (K-T) of TN ranges from 0.0316 to 0.0416 md(-1), of N-NH4 +/- from 0.013 to 0.0415 md(-1) and of N-NO3- from 0.00265 to 0.01005 md(-1). The constants K-T have a strong positive correlation with the organic input load and the dissolved oxygen (DO) concentration of WSPs. The study estimates these essential design parameters pertaining to local conditions to optimize the design considerations and sizing requirements. The estimated parameters can effectively be applied in sizing WSPs under Mediterranean or similar climatic conditions.