Aggregation and construction mechanisms of microbial extracellular polymeric substances with the presence of different multivalent cations: Molecular dynamic simulation and experimental verification

•A molecular model was built to reveal the arrangements and dynamic characteristics of biopolymers in EPS.•Biopolymers form agglomerates spontaneously through electrostatic and hydrophobic interactions.•Rearrangement of EPS molecular conformation reduced the exposure of hydrophilic groups.•Contact of biopolymers promoted by multivalent cations enhancing the intermolecular forces and compactness of EPS.•The hydration of Al3+ and Mg2+ affect the stability of association with biopolymers.