Significance of denitrifying enzyme dynamics in biological nitrogen removal processes: a simulation study.

Activated Sludge Model No.1 (ASM1) was extended to include the enzyme kinetics of denitrifying bacteria switching between oxygen and nitrate as electron acceptors. The extended ASM1 (eASM1) model was applied to two different periodic process configurations, fed-batch and Biodenipho, commonly used for nitrogen removal from wastewater. Predictions of optimal unaerated volume fraction (UVF) by eASM1 were similar to those by ASM1 for both the fed-batch and Biodenipho processes. However, eASM1 predicted substantially longer optimal cycle lengths than ASM1 for both processes. Predictions of optimal UVF and cycle length for the Biodenipho process by eASM1 were closer to current operational values for the University of Florida Biodenipho process than predictions by ASM1.