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Effect of pH and ionic environment changes on interparticle interactions affecting activated sludge flocs: a
1Laboratoire des Sciences de l'Eau et de l'Environnement, Université de Limoges. Faculté des Sciences et Techniques. 123, avenue A. Thomas, 87060 Limoges Cedex-France.
Environmental Technology
|September 26, 2003
Summary
Activated sludge rheology, measured by equilibrium viscosity, is influenced by pH and salt concentration. Higher pH increases viscosity, while cation addition, regardless of valency, decreases it by altering particle interactions.
Area of Science:
- Environmental Science
- Chemical Engineering
- Material Science
Background:
- Understanding activated sludge rheology is crucial for wastewater treatment processes.
- Rheological properties, like viscosity, are influenced by environmental factors and particle interactions within sludge flocs.
Purpose of the Study:
- To investigate the rheological behavior of activated sludge.
- To determine the influence of pH, sodium chloride, and calcium chloride concentrations on sludge suspension equilibrium viscosity (micro(eq)).
Main Methods:
- Determination of sludge suspension equilibrium viscosity (micro(eq)).
- Systematic variation of pH, sodium chloride, and calcium chloride concentrations.
- Correlation of micro(eq) with zeta-potential to assess surface charge effects.
Main Results:
- Micro(eq) increased with increasing pH.
- Cation addition (NaCl, CaCl2) decreased micro(eq) proportionally, irrespective of cation valency.
- A linear correlation was observed between micro(eq) and zeta-potential, indicating surface charge significantly impacts rheology.
Conclusions:
- Environmental factors like pH and cation concentration significantly alter activated sludge rheology.
- Changes in surface charge and double layer thickness due to cation addition reduce interparticle interactions, leading to lower viscosity.
- Micro(eq) serves as a reliable indicator of interparticle interactions affecting sludge floc behavior.