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Mathematical model for sizing combined nitrification and pre-denitrification activated sludge systems.
G Esposito1, M Fabbricino, P Lens
1Department of Mechanics, Structures and Environmental Engineering, University of Cassino, via Di Biasio 43, 03043 Cassino, FR, Italy
Environmental Technology
|May 16, 2007
Summary
This study presents two mathematical models for sizing activated sludge systems. These models help determine biological reactor volumes for effective nitrogen and organic matter removal from wastewater.
Area of Science:
- Environmental Engineering
- Wastewater Treatment Technologies
- Biochemical Engineering
Background:
- Activated sludge systems are crucial for removing nitrogen and organic matter from wastewater.
- Accurate sizing of these systems is essential for efficient treatment and regulatory compliance.
Purpose of the Study:
- To develop and present two mathematical steady-state models for sizing single activated sludge systems.
- To focus on combined nitrification and pre-denitrification systems for nitrogen and organics removal.
- To provide explicit expressions for biological reactor volumes based on influent composition and kinetic parameters.
Main Methods:
- Development of two mathematical steady-state models for activated sludge systems.
- Consideration of combined nitrification and pre-denitrification configurations.
- Inclusion of growth and decay kinetics for heterotrophic and autotrophic bacteria.
- Analysis of three (organic matter, ammonia nitrogen) and four (organic matter, ammonia nitrogen, nitrate nitrogen) substrates.
Main Results:
- Explicit expressions for biological reactor volumes are derived when influent composition, kinetic parameters, and effluent nitrogen concentration are known.
- The pre-denitrification model allows for a priori assessment of system applicability for specific wastewaters.
- Nitrification reactor volume increases with higher influent organic load or desired ammonia nitrogen removal efficiency.
- A smaller denitrification volume is needed for higher influent organic loads.
Conclusions:
- The proposed models provide a robust framework for sizing activated sludge systems for nutrient and organic removal.
- Kinetic parameters, particularly the maximum ammonia nitrogen removal rate and biomass decay ratios, significantly influence nitrification reactor volume.
- The models offer valuable tools for optimizing wastewater treatment plant design and operation.
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