Model-Based Evaluation of Competition between Polyphosphate- and Glycogen-Accumulating Organisms

The competition between polyphosphate-accumulating organisms (PAOs) and glycogenaccumulating non-polyphosphate organisms (GAOs) were evaluated using mathematical model simulations. The models for PAOs and GAOs were calibrated and able to provide satisfactory predictions of acetate, ortho-phosphate, biomass glycogen, biomass polyhydroxyalkanoates (PHAs), and biomass concentrations compared with experimental observations. It was demonstrated that both anaerobic acetate uptake and aerobic distribution of stored PHAs are important factors in determining the competition between PAOs and GAOs. At 30°C and 10-day sludge age, the kinetic advantage of anaerobic acetate uptake for GAOs is one of the most important factors in determining the competition between PAOs and GAOs. At 30°C and 3-day sludge age, aerobic glycogen formation rate for GAOs (), in addition to anaerobic acetate uptake, was demonstrated to be an important factor in determining the dominance between PAOs and GAOs. In addition, the mathematical models were able to simulate the coexistence of PAOs and GAOs at 30°C and 5-day sludge age