Simulation Of Simultaneous Nitrification-Denitrification Using Activated Sludge Model No. 1
The operation of biological wastewater treatment systems performing simultaneous nitrificationdenitrification (SND) was simulated using Activated Sludge Model No. 1 (ASM1). Properties and parameters typical of domestic sewage were used in the simulations. System performance was simulated under a range of conditions to identify an appropriate operating window for the process. Simulation results indicated optimum nitrogen removal was achieved when the dissolved oxygen concentration was 0.3 mg/L and the solids residence time was 15 d. The availability of electron donor to drive denitrification was also a major determinant of overall nitrogen removal. On the other hand, the effect of the hydraulic residence time, the recycle ratio, and the readily biodegradable fraction of the influent organic matter on overall nitrogen removl was minimal. Analysis of the simulation results with reported field and laboratory data, however, suggests that the structure of ASM1 and the parameter values used could reproduce general trends in SND system response and predict nitrogen removal performance. However, model parameter estimates better suited to the SND process are required to accurately define an optimum window for the SND operations.