Control of nitrogen removal in wastewater treatment plants with predenitrification, depending on the actual purification capacity

In this paper, a control strategy for a wastewater treatment plant with predenitrification is presented, enabling the control of nitrogen removal depending on the current capacity of the purification process. The concept is based on a simple on-line identifiable model of the nitrogen removal process. The model allows the precalculation of process data for several hours in advance. By this, the controller is able to consider future changes in concentration of the effluent variables of interest. For the demonstration of the efficiency of this approach, different controllers are presented in a simulation study. By means of the variation of the volumes of nitrification and denitrification, by an equalizing basin or by the addition of external carbon sources, the ammonium and inorganic nitrogen concentration in the effluent of the biological purification stage will be controlled. Finally, these controllers will be integrated into an overall strategy.