Mitigation of nitrous oxide emissions from wastewater treatment systems using nitrous oxide respiring bacteria

• Applicants: Professorin Dr. Susanne Lackner; Professor Dr. Jörg Simon
• Subject Area: Hydrogeology, Hydrology, Limnology, Urban Water Management, Water Chemistry, Integrated Water Resources Management
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 515585785

Nitrous oxide (N2O; laughing gas) is a potent greenhouse gas and ozone depleting substance. Over the last century the atmospheric concentration of N2O has been constantly on the rise as a consequence of the invention of man-made nitrogen fixation (the Haber-Bosch process) and intensification of agricultural fertilization practices that resulted in a severe anthropogenic imbalance of the global biogeochemical nitrogen cycle. Despite the fact that N2O emissions have been recognized to play an important role in climate change, corresponding mitigation strategies remained underexplored. The aim of this interdisciplinary and collaborative project is to investigate N2O respiring bacteria (NrB) and their applicability to mitigate N2O emissions from wastewater treatment plants. The two main objectives are (i) to identify the best-suited NrB for the task and (ii) to expose these organisms under continuous conditions that are realistic for wastewater treatment. The work program includes a thorough microbiological characterization of representative NrB in short-term batch experiments including scrutiny of nitrous oxide respiration towards the presence of dissolved oxygen and other relevant factors such as carbon source and impact of the wastewater matrix. Suitable NrB will be exposed to wastewater-like conditions in continuous long-term experiments. These trials will be performed in lab-scale reactors under varying conditions, e.g. dynamic changes in the dissolved oxygen concentration. The project will provide a suitability assessment regarding the use of NrB under wastewater conditions and the implementation of NrB in wastewater treatment systems. It will also contribute to exploit the almost untouched natural resource of N2O respiring bacteria.

• DFG Programme: Research Grants