Abstract:

The currently available comprehensive activated sludge models, ASM#1 ( <xref ref-type="bibr" rid="waer-80-11-Grady2">Grady et al., 1986</xref>) and its successor ASM#3 ( <xref ref-type="bibr" rid="waer-80-11-Gujer1">Gujer et al., 1999</xref>), do not adequately describe nitrification and denitrification, with respect to ammonia oxidation inhibition, nitrite accumulation, or emissions of nitric oxide and nitrous oxide. A new comprehensive activated sludge process model, the Activated Sludge Model for Nitrogen (ASMN), is presented. The ASMN incorporates two nitrifying populations—ammonia-oxidizing bacteria and nitrite-oxidizing bacteria—using free ammonia and free nitrous acid, respectively, as their true substrates. The ASMN incorporates four-step denitrification (sequential reduction of nitrate to nitrogen gas via nitrite, nitric oxide, and nitrous oxide) using individual, reaction-specific parameters. Simulation results for ammonia, nitrate, soluble substrate, and biomass concentrations determined by using ASMN for three activated sludge process configurations under steady-state and dynamic municipal-type influent conditions are shown to be comparable with ASM#1 results.

Keywords: nitrification; denitrification; modeling; ASM#1; Activated Sludge Model for Nitrogen; pH; temperature; inhibition; free ammonia; free nitrous acid

Document Type: Research article

DOI: 10.2175/106143008X304776