Experimental evaluation and model assessment of coexistence of PAOs and GAOs

The study evaluated the competition and co-existence of PAOs and GAOs in sequencing batch reactor (SBR) systems sustaining enhanced biological phosphorus removal (EBPR). The SBR operation used acetate as the sole external carbon source and covered a wide range of initial COD/P ratios between 6.5 to 25.9 g COD/g P. A mechanistic model, ASMGG, was adopted for this purpose, which basically incorporated model components and processes associated with GAO metabolism and glycogen metabolism of PAOs. Model calibration was successfully performed with the same set of stoichiometric and kinetic coefficients for all the acetate, phosphate, glycogen and PHA profiles obtained in different experiments. Interpretation of experimental results by means of model simulation indicated competition and co-existence of PAOs and GAOs within the EBPR process, numerically assessing the composition of the microbial community sustained and identifying the respective role and function of PAOs and GAOs on the fate of glycogen and PHA.