Colloid

Adhesion

Process (computing)

Engineering

Biofilm

Nanoparticle

Bacteria

Biology

Materials science

Chromatography

Operating system

Computer science

Chemical engineering

Physical chemistry

Genetics

DLVO theory

Flocculation

Organic chemistry

Extracellular polymeric substance

Environmental chemistry

Environmental science

Zeta potential

Composite material

Surface charge

Chemistry

Pulp and paper industry

Granulation

The Science of The Total Environment

Different forms of extracellular polymeric substances (EPS) play different roles in the formation process of aerobic granular sludge (AGS). This work focused on the contribution of loosely bound EPS (LB-EPS), tightly bound EPS (TB-EPS) and EPS to the aggregation between sludge cells during the start-up of aerobic granular sludge in a sequencing batch reactor. By analyzing the changes of sludge surface characteristics before and after the extraction of each layer of EPS, the contribution of LB-EPS, TB-EPS and EPS to the adhesion and aggregation of sludge cells in the granulation was calculated by surface thermodynamics and the extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory. The experimental results showed that AGS reactor basically completed the granulation process and kept stable operation within 40 d. In the process of sludge granulation, the effect of LB-EPS on the aggregation of sludge cells shifted from attraction to repulsion. TB-EPS could improve the surface zeta potential and hydrophobicity and show an attractive effect in the granulation process, which was conducive to the adhesion between sludge cells and was the main contributor to the formation of granules. Additionally, EPS played an apparently positive role in sludge flocculation and could promoted cell aggregation in the whole granulation process.

Effect of EPS and its forms of aerobic granular sludge on sludge aggregation performance during granulation process based on XDLVO theory