Calibration and validation of an activated sludge model for a pilot-scale anoxic/anaerobic/aerobic/post-anoxic process

The aim of this study was to establish an activated sludge model and to verify its predictability for use in a pilot-scale anoxic/anaerobic/aerobic/post-anoxic (modified AAO) process. Respirometric measurements were conducted to identify the influent organic characteristics and to determine the yield coefficient ( Y H ) and decay coefficient ( b H ) for heterotrophic biomass (OHOs). The values obtained for Y H and b H were 0.72 mg COD/mg COD and 0.275 d −1 , respectively. Within the model’s calibration, the most influential stoichiometric and kinetic parameters were identified with the aid of sensitivity analysis. The output of the model was most sensitive to parameters associated with the growth and decay of OHOs and ammonia-oxidizing biomass (AOB) ( Y H , µ maxH , K s , b H , µ maxA , K NH4A , and b aeroa,A ). Furthermore, all the calibrated parameters, with the exception of Y PAO, aerob related to the phosphorus accumulating organisms (PAOs), could be regarded as influential. Both steady-state and dynamic simulations indicated good agreement between the simulated and measured values of the output variables. The calibrated model can be used to provide insight into the pilot-scale modified AAO process, and information needed to optimize design and operation when applied at full-scale.