Remember the water: a comment on EPS colligative properties

The relationship between water and activated sludge components was examined. Reevaluation of published data on freezing point depression, drying rates and dewatering has been performed. The basis of this has been the assumption that the water/sludge relationship is considered to be a colligative effect. Since the results indicate this to be the case, we suggest that the published concepts of "pools of water" are false. Data on swelling properties of EPS as a function of pH suggests that the colligative properties are largely determined by the counterions of charged polymers and surfaces.