Single-sludge nitrogen removal model: Calibration and verification

The objective of this work was to calibrate and verify a modified version o f a mathematical model of a single-sludge system for nitrification and deni trification. The new model is based on long-term experimental results, and the main modifications are related to the biological oxygen demand removal kinetics and biomass activity expressions. The model consists of 22 equatio ns with 54 parameters, including 19 kinetic and stoichiometric coefficients . Experiments were performed on four bench-scale units and one pilot plant fed with domestic wastewater. Six sets of runs were carried out under diffe rent operational conditions. In the calibration procedure, a mathematical a lgorithm was implemented, in which an optimal set of coefficients was selec ted. Several coefficients were directly determined experimentally. Model ve rification was based on the comparison of experimental results with the val ues predicted by the mathematical model using a fixed set of model coeffici ents for each set of runs. From the verification results, the model is cons idered to be a useful one for the design of a new treatment system and oper ation of an existing one.