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Published on: April 10, 2017
Viscous and filamentous bulking in activated sludge: Rheological and hydrodynamic modelling based on experimental
V Bakos1, B Gyarmati2, P Csizmadia3
1Department of Applied Biotechnology and Food Science, Faculty of Chemical Technology and Biotechnology, Budapest University of Technology and Economics, Műegyetem rkp. 3., H-1111 Budapest, Hungary; Department of Chemical Engineering, University of Bath, Claverton Down, Bath, BA2 7AY, UK.
Sludge floc structure impacts rheological properties and energy efficiency in wastewater treatment. Understanding these relationships aids in optimizing sludge pumping and energy use.
Area of Science:
- Environmental Engineering
- Fluid Mechanics
- Wastewater Treatment
Background:
- Activated sludge settleability is crucial for effluent quality.
- Filamentous bulking is well-studied, but viscous sludge formation is less understood.
- Sludge floc structure changes can negatively impact wastewater treatment plant operations.
Purpose of the Study:
- To investigate the relationship between sludge floc structure and rheological properties.
- To model non-Newtonian sludge flow and estimate pressure loss in pipe networks.
- To develop a protocol for improving energy efficiency in sludge pumping.
Main Methods:
- Generated viscous and filamentous bulking in lab-scale systems.
- Monitored sludge floc structure and rheological property evolution.
- Applied computational fluid dynamics (CFD) for hydrodynamic modeling.
Main Results:
- A correlation was found between sludge floc structure transformations and rheological properties.
- The Herschel-Bulkley model best described the sludge rheology.
- CFD accurately estimated pressure loss for different sludge types.
Conclusions:
- Sludge rheology is directly linked to floc structure.
- The Herschel-Bulkley model is suitable for characterizing sludge flow.
- A modeling protocol can enhance energy efficiency in sludge pumping.
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