Alternating aerobic-anoxic process for nitrogen removal: Dynamic modeling

A dynamic mathematical model was developed for the alternating aerobic-anoxic (AAA) completely mixed activated sludge process for the removal of carbonaceous substrate, nitrification, and denitrification. The model is constructed on the Activated Sludge Model No. 1 (ASM 1) of the International Association on Water Pollution Research Control with some revisions including pH and alkalinity. Experimental data obtained from a bench-scale AAA reactor under different operational conditions were used for parameter estimation and model validation. Model parameters were found to agree well with those used by the ASM1. Process performance at steady-state and dynamic conditions can be well predicted by the AAA model. Because nitrite is not treated as a state variable in the ASM 1, a modified model incorporating nitrite as a state variable has been developed to account for nitrite accumulation.