Oxidative treatment of waste activated sludge by different activated persulfate systems for enhancing sludge dewaterability

The enhancement in dewaterability of waste activated sludge (WAS) by oxidative treatment using thermally- and alkali-activated persulfates (i.e., peroxymonosulfate (PMS) and peroxydisulfate (PDS)) was studied with two indices representing dewaterability change, i.e., centrifuged weight reduction (CWR) and standardized-capillary suction time (SCST). The tested conditions include 50 °C/PMS, 50 °C/PDS, 80 °C/PMS, and 80 °C/PDS as thermally-activated persulfate systems and NaOH/PMS, NaOH/PDS, KOH/PMS, and KOH/PDS as alkali-activated persulfate systems. The oxidation by activated persulfates caused the disintegration of bacterial cells and extracelluar polymeric substance (EPS) of WAS, affecting the sludge dewaterability. The highest dewaterability was found at the KOH/PDS treatment in CWR and at the 80 °C/PDS treatment in SCST. The EPSs were stratified as soluble, loosely-bound (LB) and tigh…