Effects of potassium ferrate on extracellular polymeric substances (EPS) and physicochemical properties of excess activated sludge

► Potassium ferrate pretreatment was detrimental to the filterability based on the CST results. ► Potassium ferrate pretreatment slightly enhanced the sludge settleability and dewaterability. ► LB-EPS content was increased and TB-EPS content was reduced after pretreated by potassium ferrate. ► The increased LB-EPS was the major reason for the changes in sludge settleability and filterability. ► TB-EPS and PN in TB-EPS were negatively correlated with CST.