Kinetic modelling of biological phosphorus removal with a pure culture of Acinetobacter sp. under aerobic, anaerobic and transient operating conditions

Laboratory-scale batch experiments were conducted for a pure culture of Acinetobacter sp. aiming to develop a kinetic model for the aerobic growth of the bacterium under phosphate and carbon-limited conditions. The ability of the bacterium to take up more phosphorus than is normally needed for cell growth and store it intracellularly as polyphosphate was verified. A sufficiently accurate kinetic model, describing the behaviour of the bacterium under polyphosphate- and carbon-limited anaerobic conditions, was then developed. The transient characteristics of batch cultivation systems with Acinetobacter sp. cells to changes from anaerobic to aerobic conditions and vice-versa were studied in the sequel and an appropriate integrated kinetic model was developed. The model describes adequately the dynamic behaviour of the poly-P bacterium under strictly anaerobic, strictly aerobic and transient conditions. Model predictions were validated with batch experiments conducted under transient aerobic/anaerobic conditions. Acinetobacter sp. cells presented a rapid adaptation ability to either aerobic or anaerobic conditions during shifting from one environment to the other. Batch experimentally observed profiles of biomass growth, acetate consumption and phosphorus uptake and release were found to be in excellent agreement with the predicted ones by the overall kinetic model.