A method to estimate denitrification potential for predenitrification systems using NUR batch test

Nitrate utilisation rate (NUR) batch tests with wastewater and acetate as carbon sources were carried out. A pulse dosage of wastewater to activated sludge in anoxic conditions enables to distinguish the denitrification rates on subsequent wastewater fractions and to determine the concentrations of readily (SS) and slowly biodegradable COD (XS). The anoxic substrate utilisation rates of SS and XS under anoxic conditions can be calculated. Using mentioned parameters the overall denitrification rate can be modelled as a function of the anoxic sludge loading rate in the predenitrification volume. The denitrification potential of the wastewater, defined as the amount of nitrate which can be reduced with the biodegradable COD-fractions in the influent and endogenous denitrification potential allow to calculate the denitrification potential of the treatment plant and to predict the nitrate effluent quality. If the denitrification potential of the plant is not sufficient the addition of an external carbon source has to be considered to enhance the denitrification. In this study, batch NUR tests with acetate were carried out to extract process kinetics. The relation between the obtainable denitrification rate and the anoxic sludge loading rate can be used to design the rate of dosage of acetate and can be a base for developing control strategies. In all denitrification NUR batch tests a precaution should be taken concerning accumulation of nitrite and biological phosphorus removal activity. The possible transfer of the results to full-scale treatment plants is discussed.