Physicochemical properties and trace organic compounds in a dairy processor's aerobic bioreactor

► Dairy processing wastewater is analysed for indicators of bioreactor performance. ► Physicochemical and GC-MS analyses are combined using metabolomic techniques. ► Phosphorus concentrations is related to bioreactor mixed liquor. ► Nitrogen concentrations are related to infeed into mixed liquor. ► 4-Nitrophenol is correlated to analyses relating to anaerobicity (e.g. NH3/NO3).