Partial denitrification-anammox for resource efficient and climate-friendly nitrogen removal from municipal wastewater

Research Project, 2021 – 2023

To minimise eutrophication, nitrogen removal from municipal wastewater is vital. The biological processes used today are energy-intensive and have a large carbon footprint because electricity is required for aeration (nitrification) and organic matter, that instead could have been used for biogas production, is needed for denitrification. Nitrogen removal with anaerobic ammonium oxidation (anammox) does not consume organic matter and the need for aeration is much lower. We want to test a new process solution to implement anammox: partial denitrification-anammox (PDA). For treatment of municipal wastewater, a more stable anammox process seems possible with PDA than with the other much more investigated process solutions. We will study how to control PDA to attain high removal rates and low effluent concentrations at realistic conditions based on studies of the interplay between operational factors, environmental conditions and microbial interactions. We evaluate the reproducibility and stability of PDA and assess the real gains in terms of usage of energy, carbon footprint, demand for area and economic costs. For studies at realistic conditions, a pilot plant for PDA is built at Källby wastewater treatment plant in Lund. Bench-scale reactors are used for experiments at well-defined conditions. To address the research questions, we use chemical analyses, molecular biology tools (metagenomics and metatranscriptomics), mass flow analysis and life-cycle analysis.