This research had as main objective to investigate the involved processes in the transformations of nitrogen in a system of waste stabilization ponds. In nictemeral sampling (24 hours) strong thermal stratification was observed during most of the showed cycle which conditioned two vertical compartments and the chemical stratification in the two lagoons, making possible the analysis of the processes of segmented form for PCA (Principal Components Analysis) that was a very useful statistics tool in the characterization of the processes. The protein degradation was observed with subsequent generation and accumulation of ammoniacal nitrogen, beyond the possible excretion of protein or amino acids for phytoplanktonic organisms in the surface of the ponds. The probable occurrence of nitrification in the surface layer of the anaerobic pond evidenced the necessity of improving the operation parameters of the system in order to reach a greater nitrogen removal through the denitrification, process probably inhibited by significant high concentrations of oxygen dissolved registered in superficial layers, particularly during the day.
Waste stabilization ponds; nitrogen dynamics; nictemeral cycle; principal component analyses (PCA)
