The influence of ionic strength and osmotic pressure on the dewatering behaviour of sewage sludge

Abstract

In this work, we investigated the importance of osmotic pressure in the overall dewaterability behaviour of a biotic sludge. Biotic sludges, such as activated or digested sludge from waste water treatment, are known to be difficult to dewater, due to their high compressibility and their gel-like water retention capacity. These properties are partly attributed to the presence of surface charges, which are due to the biological nature and the presence of weakly charged extra-cellular polymeric substances. Both in filtration and centrifugation experiments, charge related effects were partly neutralised through a controlled increase in the bulk ionic strength by the addition of NaCl. It was obse..