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Updated: Feb 23, 2026
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Extraction of Structural Extracellular Polymeric Substances from Aerobic Granular Sludge
Published on: September 26, 2016
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Freezing-duration effects on landfilled sludge conditioning via vacuum preloading: EPS-mediated dewaterability,
1Jiangsu Key Laboratory of Low Carbon and Sustainable Geotechnical Engineering, School of Transportation, Southeast University, Nanjing, Jiangsu Province, 211189, PR China.
Journal of Environmental Management
|February 21, 2026
Summary
Extending sludge freezing duration significantly improves dewatering and volume reduction by disrupting extracellular polymeric substances (EPS). This enhances sludge mechanical properties and consolidation, aiding in landfilled sludge management.
Area of Science:
- Environmental Engineering
- Geotechnical Engineering
- Material Science
Background:
- Landfilled sludge requires effective dewatering and volume reduction globally.
- Freezing with vacuum preloading is an established in situ sludge treatment.
- Limited research exists on the impact of freezing duration on sludge properties.
Purpose of the Study:
- To investigate the influence of freezing duration and extracellular polymeric substances (EPS) on sludge dewaterability, mechanical properties, and microstructural changes.
- To determine optimal freezing durations for enhanced sludge treatment.
- To provide guidance for efficient landfilled sludge management.
Main Methods:
- Sludge samples were subjected to varying freezing durations.
- Measurements included specific resistance to filtration (SRF), capillary suction time (CST), void ratio, compression index, consolidation coefficient, and hydraulic conductivity.
- Extracellular polymeric substances (EPS) fractions (LB-EPS, S-EPS) were analyzed.
- Microstructural analysis focused on particle size and pore distribution.
- Volume reduction and water content were quantified.
Main Results:
- Increasing freezing duration significantly reduced SRF and CST, improving dewaterability.
- Longer freezing disrupted EPS, particularly loosely bound (LB-EPS) and soluble (S-EPS) fractions.
- Freezing enhanced consolidation properties, increasing consolidation coefficient and hydraulic conductivity by 1-2 orders of magnitude.
- A 96-hour freezing duration achieved 54.9% volume reduction and reduced water content from 86% to 57.3%.
- Prolonged freezing led to larger particle sizes and increased mesopore/macropore abundance, creating a denser sludge structure.
- EPS content strongly correlated with compressibility, consolidation, dewatering, and microstructural changes.
Conclusions:
- Extending freezing duration is a key factor in enhancing sludge dewatering and consolidation.
- EPS disruption is a critical mechanism underlying the improved sludge engineering performance.
- This study offers vital insights for optimizing in situ treatment of landfilled sludge through controlled freezing duration.
Keywords:
Consolidation propertiesDeep dewateringExtracellular polymeric substances (EPS)Freezing durationVacuum preloadingMore Related Videos
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