PANDA stands for Partial Augmented Nitritation Denitritation Alkalinity recover and was mainly developed by Prof. Dr.-Ing. Peter Hartwig and Prof. Dr.-Ing. Karl-Heinz Rosenwinkel from ISAH University of Hannover.

At a Glance PANDA_scheme

»    Efficient nitrogen removal
»    Nitritation/denitritation
»    Saving of carbon source
»    Modification to deammonification
»    Full-scale application


The technology comprises an aerated nitritation tank, followed by a mixed denitritation tank and a final clarifier. The recycle flow of the excess sludge is conncected to both nitritation and denitritation tank. Additionally there is a recirculation of the clear water phase to the nitritation tank. The current state of art for nitrogen removal at municipal wastewater treatment plants are the processes of nitrification/denitrification. The economic efficiency of these processes is mostly controlled by the costs for the provided basin volume, the mixing and the energy demand for the aeration. Depending on the carbon to nitrogen ratio, even the dosing of external carbon can be required, which would create additional costs. In order to reduce the energy costs the nitrification can be shortened by stopping the oxidising process of ammonium at nitrite (NO2) and avoid the formation of nitrate (NO3), this process is named Nitritation. The nitrite is then converted into elemental nitrogen by denitritation. Thereby, it is also possible to reduce the cost for dosing of the external carbon (if it is required) since the denitritation needs just 2/3 of the carbon denitrification would need. Or the process can be used to reduce the NO3-N-effluent concentrations. As an enhanced modification of the nitritation the process of deamonification (Nitration + anaerobic oxidation of ammonia) gets more and more attention. This process saves even more energy and needs no external carbon source at all