The novel pretreatment of Co2+ activating peroxymonosulfate under acidic condition for dewatering waste activated sludge

A novel Co2+/peroxymonosulfate (PMS)/Acid pretreatment enhanced waste activated sludge (WAS) dewaterability. Experimental results showed that Co2+/PMS/Acid pretreatment reduced capillary suction time (CST) of WAS by 52.1% under 0.158 mmol/g TSS PMS and 0.079 mmol/g TSS Co2+ at pH 4. In this circumstance, water content of sludge cake (WCSC) dropped to 73.7%. The mechanisms were elucidated with a suite of macro and spectroscopic evidence. During the pretreatment, Co2+ activated PMS to generate SO4 center dot and (OH)-O-center dot under acidic condition, these radicals decomposed extracellular polymeric substances (EPS) and destroyed integrity of microbial cell wall. They also facilitated removal of high molecular weight biopolymers in EPS fractions. Co2+, its oxidative product (i.e., Co3+), and H+ reduced negative charge of EPS functional groups. Moreover, many voids were formed on sludge surface after pretreatment. Finally, the bound water content and viscosity reduced but the flocculability and amount of drainage holes of WAS increased. All these results induced the enhancement of WAS dewaterability. (C) 2019 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.