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Updated: Jun 27, 2026
07:59
Estimating Sediment Denitrification Rates Using Cores and N2O Microsensors
Published on: December 6, 2018
An updated process model for carbon oxidation, nitrification, and denitrification
William C Hiatt1, C P Leslie Grady
1SCH2M Hill Inc., Spartanburg, South Carolina, USA.
Summary
A new Activated Sludge Model for Nitrogen (ASMN) improves upon existing models by accurately simulating nitrification and denitrification processes, including key intermediates and emissions, for enhanced wastewater treatment. This model offers comparable results to ASM#1 for essential parameters.
Area of Science:
- Environmental Engineering
- Environmental Microbiology
- Wastewater Treatment Technology
Background:
- Existing activated sludge models like ASM#1 and ASM#3 inadequately represent nitrification and denitrification.
- Limitations include poor description of ammonia oxidation inhibition, nitrite accumulation, and gaseous emissions (nitric oxide, nitrous oxide).
Purpose of the Study:
- To introduce a novel, comprehensive activated sludge model named ASMN.
- ASMN aims to accurately simulate nitrogen transformations in wastewater treatment processes.
Main Methods:
- ASMN models two nitrifying populations: ammonia-oxidizing bacteria and nitrite-oxidizing bacteria.
- It utilizes free ammonia and free nitrous acid as specific substrates.
- ASMN incorporates a four-step denitrification process with reaction-specific parameters.
Main Results:
- Simulations using ASMN were conducted for three activated sludge configurations.
- Steady-state and dynamic municipal-type influent conditions were evaluated.
- ASMN results for ammonia, nitrate, soluble substrate, and biomass concentrations were comparable to ASM#1.
Conclusions:
- The ASMN provides a more robust framework for modeling nitrogen removal in activated sludge systems.
- It addresses critical limitations of previous models concerning nitrification and denitrification pathways.
- The model's accuracy is validated by its comparable performance to established models under various conditions.
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