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Adaptive control of the nitrate level in an activated sludge process
M Ekman1, P Samuelsson, B Carlsson
1Dept. of Systems and Control, Uppsala University, P O Box 337, SE-751 05 Uppsala, Sweden. mats.ekman@it.uu.se
Summary
This study presents an automatic control strategy for managing nitrate levels in activated sludge systems by adding an external carbon source. The automated system effectively controls nitrate concentration, optimizing nitrogen removal in wastewater treatment.
Area of Science:
- Environmental Engineering
- Wastewater Treatment Technologies
- Microbial Ecology
Background:
- Nitrogen removal in activated sludge processes relies on facultative heterotrophic bacteria converting nitrate to nitrogen gas under anoxic conditions.
- Sufficient readily biodegradable carbon compounds are essential for this denitrification process, often necessitating external carbon source addition.
- Effective nitrate level control is crucial for optimizing nitrogen removal efficiency in wastewater treatment plants.
Purpose of the Study:
- To develop and evaluate an automatic control strategy for managing nitrate levels in activated sludge systems using an external carbon source.
- To implement on-line estimation of key process parameters for a simplified Activated Sludge Model No 1.
- To utilize estimated parameters for updating a linear quadratic controller for precise nitrate control.
Main Methods:
- An automatic control strategy was designed to dose an external carbon source into the first anoxic zone to regulate nitrate concentration in the final anoxic zone.
- Key process parameters were estimated on-line using a simplified Activated Sludge Model No 1.
- A linear quadratic controller was updated with the on-line estimated parameters.
Main Results:
- The proposed control strategy demonstrated effective control of nitrate concentration in the simulated activated sludge system.
- On-line parameter estimation and controller updating allowed for adaptive and responsive nitrate management.
- Simulation studies with realistic influent data confirmed the robust performance of the developed strategy.
Conclusions:
- The presented automatic control strategy offers a viable solution for optimizing nitrate removal in activated sludge processes.
- On-line parameter estimation and adaptive control are key to achieving efficient and stable nitrogen removal.
- This approach enhances the operational efficiency of wastewater treatment plants by ensuring consistent nitrate reduction.