NAREDENI
Scientific Monitoring of Pilot Tests on Downstream Denitrification Using a Fluidized Bed System at the Ingolstadt Central Wastewater Treatment Plant
Population growth, particularly in metropolitan areas, poses major challenges for infrastructure—and thus also for wastewater treatment plants. The increased volumes of wastewater require greater capacity at treatment plants to ensure that discharge limits for treated wastewater can continue to be met in the future.
In particular, the process of nitrogen removal from wastewater is significantly more complex than the removal of other typical wastewater parameters—carbon and phosphorus—and therefore generally leads to difficulties, especially at overloaded wastewater treatment plants and those with more stringent requirements. The process of downstream residual denitrification in the effluent stream of a wastewater treatment plant can provide a straightforward solution with manageable capital and operating costs. This process specifically removes nitrate nitrogen (NO₃-N) from the already treated wastewater. In particular, plants using the fluidized bed process are well-suited for such post-treatment wastewater treatment systems due to their process stability and low space requirements. This makes it possible to avoid a costly and resource-intensive expansion of the wastewater treatment plant.
To date, no technical regulations or similar guidelines exist for these plants that would enable the general application of the process. The foundations for this are to be developed in this research project in collaboration with the Ingolstadt Central Wastewater Treatment Plant and the engineering firm Dr.-Ing. Schreff.
A full-scale implementation of a downstream residual denitrification process in a fluidized bed is to take place at the Ingolstadt Central Wastewater Treatment Plant. The project was awarded the 2018 Wastewater Innovation Prize by the Bavarian State Ministry for the Environment and Consumer Protection (StMUV). A pilot plant (see photo) has been in operation since March 2019. As part of the scientific investigations, the experience gained from operating the pilot plant and the full-scale facility will be analyzed for application at other wastewater treatment plants, thereby contributing to the development of new technologies in wastewater treatment.
The Swirling Suspended Bed Process for Post-Treatment Denitrification:
Unlike conventional activated sludge processes at wastewater treatment plants, the turbulent suspended bed process uses biofilms for biological nitrogen removal. These biofilms are located on special carriers designed to maximize surface area. Special microorganisms in the biofilms are required for denitrification—the conversion of nitrate nitrogen (NO3-N) to molecular nitrogen (N2). To evaluate the conditions under which these microorganisms can convert nitrate nitrogen, various operating and boundary conditions are simulated in the pilot plant. In addition, laboratory reactors are operated at the Laboratory for Municipal Water Management at Augsburg University of Applied Sciences.