Phase-Synchronized Nitrogen Dynamics in Avedøre WWTP: Temporal Patterns under Meteorological Variability

The study evaluated nitrogen dynamics using a two-year data set from the Avedøre Wastewater Treatment Plant (WWTP) in Copenhagen. The data set provides a real-time record of nutrient concentrations and physical properties of wastewater. Time-series analysis of the data set showed recurring daily features, like periodic rises and dips, with detection window shifting seasonally. Wastewater temperature showed strong correlation with atmospheric conditions, peaking in negative correlation 17 h postprecipitation. And long segments of synchronized nitrogenous (NH 4 +, NO 3 –, and N 2 O) concentration signals were observed, which are categorized into six patterns based on cross-species coherence. Three patterns showed a strong relationship with precipitation and hydraulic flow changes, exhibiting shifts in nitrogenous species mass ratio concurrent with meteorological variability. In contrast, two recurring single-species signal patterns suggest possible nitrogenous mass conservation during transport in the sewer network. The sixth pattern showed cross-species time-offset signal pairs, suggesting a complex temporal relationship potentially linked to WWTP operational parameters and microbial activity. The study’s limitations include reliance on single-point time-series data, highlighting the need for direct sediment analysis, microbial profiling, and spatial analysis to clarify the synchronized signal origin. The findings may help estimate wastewater nitrogen mass, forming a foundation for nutrient recovery and mitigation of greenhouse gas emissions in circular wastewater systems.