In this study, we found that dewatering properties were related with physico-chemical properties such as sludge concentration, pH, and zeta potential with sewage sludge, Ionic contents in digested sludge were in the order of $Ca^{2+}$ (14.2 mg/g) > $Mg^{2+}$ (1.9 mg/g) > $Na^+$ (1.4 mg/g) > $K^+$ (1.0 mg/g). Divalent ion more than monovalent have influenced on physico-chemical and dewatering properties. Floc size distribution in activated (AS) and digested sludge (DS) increased on lower pH range to be near isoelectric point and than specific resistance to filtration (SRF) decreased. A linear increase in SRF ($5.25 imes10^{13}sim2.86 imes10^{14}$ m/kg in AS and $6.89 imes10^{14}sim1.09 imes10^{15}$ m/kg in DS) was observed throughout low concentration range of 1230~9960 mg/L in AS and 2700~5400 mg/L in DS.