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An extension of ASM2d including pH calculation
J Serralta1, J Ferrer, L Borrás
1Dpto. Ingeniería Hidráulica y Medio Ambiente, Universidad Politécnica de Valencia, Camino de Vera s/n, 46022 Valencia, Spain.
Water Research
|October 20, 2004
Summary
This study enhances the Activated Sludge Model No. 2d (ASM2d) with a chemical model to predict pH in biological wastewater treatment. The improved model accurately simulates pH dynamics and nutrient removal, crucial for process optimization.
Area of Science:
- Environmental Engineering
- Biochemical Engineering
- Water Treatment Technologies
Background:
- Wastewater treatment models like Activated Sludge Model No. 2d (ASM2d) often lack accurate pH prediction capabilities.
- pH fluctuations significantly impact biological nutrient removal processes, particularly enhanced biological phosphorus removal (EBPR).
- Accurate modeling of pH is essential for optimizing wastewater treatment plant operations and performance.
Purpose of the Study:
- To extend the ASM2d by incorporating a comprehensive chemical model for precise pH calculation in biological processes.
- To improve the simulation of non-equilibrium biochemical processes by considering all pH-affecting chemical species.
- To validate the extended model's ability to predict pH dynamics alongside nutrient concentrations in EBPR systems.
Main Methods:
- Developed a chemical model integrating aqueous and gaseous phases with instantaneous chemical equilibrium and kinetically governed mass transport.
- Enlarged ASM2d by adding all pH-influencing components and an ion-balance for pH and dissociation species calculations.
- Incorporated a pH inhibition function for polyphosphate accumulating bacteria to simulate observed behaviors.
Main Results:
- The extended ASM2d accurately predicted significant pH variations observed in a sequencing batch reactor during EBPR.
- The model successfully simulated the dynamics of pH, acetic acid, and phosphate concentrations.
- Experimental data from four different operational conditions were accurately reproduced, validating the model's predictive power.
Conclusions:
- The developed chemical model extension significantly enhances ASM2d's capability to predict pH in biological wastewater treatment.
- The model provides a valuable tool for understanding and optimizing EBPR processes by accounting for pH influences.
- This integrated approach offers improved simulation accuracy for wastewater treatment systems with significant pH variations.
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