Adhesion behavior of dewatered sewage sludge during indirect thermal drying

Area of Science:

• Environmental Engineering
• Waste Management
• Material Science

Background:

• Sludge adhesion during thermal drying poses operational challenges.
• Understanding factors influencing sludge stickiness is crucial for efficient drying processes.

Purpose of the Study:

• To investigate factors affecting sludge adhesion during indirect thermal drying.
• To analyze the correlation between sludge properties, extracellular polymeric substances (EPS), and adhesion.
• To identify strategies for mitigating sludge adhesion.

Main Methods:

• Sludge properties and adhesion were assessed using peel and shear tests.
• Thermal drying was conducted at temperatures ranging from 100 to 180 °C.
• Changes in soluble EPS (S-EPS) concentration during drying were monitored.

Main Results:

• Sludge adhesiveness increased with higher drying temperatures and initial S-EPS concentration (R > 0.88).
• S-EPS concentration initially increased then decreased during drying, with higher initial concentrations releasing more S-EPS early on.
• Sludge adhesion increased after S-EPS concentration began to decline.

Conclusions:

• Sludge adhesion is influenced by heat-induced transformation of organic matter, not directly by S-EPS levels.
• Lowering drying temperature or reducing initial S-EPS concentration via anaerobic digestion can mitigate sludge adhesion.