Effect of EPS on the dewaterability of CAS and MBR sludge

In this study, the dewaterability of raw CAS and MBR sludge samples was mostly affected by the extracellular polymeric substance (EPS) concentration and composition. A significant quadratic correlation between the concentration of proteins and carbohydrates and the specific resistance to filtration (SRF) indicated that the dewaterability properties of both CAS and MBR raw sludge were enhanced at protein and carbohydrate concentrations lower than 400 and 250 mg/L, respectively. On the contrary, at higher EPS concentrations the SRF constantly increased. Generally, MBR operation resulted in sludge with a lower EPS content and, thus, a better dewaterability. Anaerobic digestion worsened the dewaterability properties of all CAS and MBR sludge samples, with EPS being considerably decreased and having no effect on the dewaterability of the digested sludge.