Enhanced Dewaterability of Waste-Activated Sludge in Presence of Fe(Ⅱ)-Activated Calcium Peroxide

Abstract

Ferrous iron-activated calcium peroxide (Fe2+/CaO2) was innovatively put forward to improve the dewaterability of waste-activated sludge. The effects of initial pH, Fe2+, and CaO2dosages on sludge dewatering performance were investigated and its internal mechanism for achieving deep sludge dewatering was thoroughly explored. The results indicated that the best dewatering performance was obtained by dosing 3.31 mmol·g-1 Fe2+ and 3.68 mmol·g-1 CaO2 under neutral pH, in which specific resistance to filtration (SRF) and water content (WC) reduced from 20.99×1012 m·kg-1 and 86.61% to 3.91×1012 m·kg-1 and 76.15%, respectively. Fe2+/CaO2 oxidation caused sludge microbial cell lysis, release of intracellular organic matter, and degradation of extracellular polymeric substances (EPS). Meanwhile, the generated Fe3+ facilitated re-flocculation of sludge particles into rigid and porous structure flocs, which was beneficial to the release of EPS-bound water to achieve deep sludge dewatering. From the perspective of technology and economy, the Fe2+/CaO2 process is economical and practical, and has a promising application prospect in improving the dewatering performance of waste-activated sludge.