Extending and calibrating a mechanistic hindered and compression settling model for activated sludge using in-depth...

Area of Science:

• Environmental Engineering
• Fluid Mechanics
• Wastewater Treatment

Background:

• Accurate modeling of activated sludge batch settling is crucial for wastewater treatment plant optimization.
• Existing models lack the mechanistic basis to fully describe sludge behavior.

Purpose of the Study:

• To extend and apply a mechanistic model for activated sludge batch settling.
• To validate the model using experimental data from two distinct wastewater treatment plants.

Main Methods:

• The mechanistic model integrates Kynch batch density functions for hindered settling and effective solids stress for compression.
• Radiotracer technology was employed to obtain detailed spatio-temporal solids concentration profiles.
• Inverse modeling techniques were utilized to determine model parameters.

Main Results:

• The extended mechanistic model accurately described batch settling experiments for sludges from different sources.
• Cole's power function provided acceptable results for initial settling velocities.
• A single effective solids stress function was identified using a time-dependent compression solids concentration.

Conclusions:

• The developed mechanistic model demonstrates strong descriptive power for activated sludge batch settling.
• The model's success suggests potential for wider application in wastewater engineering.
• Understanding solids concentration profiles is key to effective sludge management.