Improved Dewaterability of Waste Activated Sludge by Fe(II)-Activated Potassium Periodate Oxidation

Abstract

Fe(II)-activated potassium periodate (KIO4) oxidation was used to improve the dewaterability of waste-activated sludge for the first time. Compared with those of raw sludge, the capillary suction time (CST), specific resistance filtration (SRF), and water content of filter cake (WC) of sludge treated using the Fe(II)/KIO4 process under the optimal conditions (i.e., the initial pH = 6.8, KIO4 dose = 1.4 mmol/g volatile suspended solids, Fe(II)/KIO4 molar ratio = 1.2) decreased by 64.34%, 84.13%, and 6.69%, respectively. For conditioned sludge flocs, the Zeta potential and particle size were increased, and hydrophilic proteins in extracellular polymeric substances (EPS) were partly degraded, accompanied by the transformation of tightly bound EPS into soluble EPS and the conversion of dense sludge flocs into loose and porous ones. During Fe(II)/KIO4 oxidation, Fe(IV) and the accompanying •OH were determined as the predominant reactive species and the underlying mechanism of sludge EPS degradation was proposed. This work provides a prospective method for conditioning the sludge dewaterability.

Environmentally Safe Method for Conditioning and Dewatering Sewage Sludge Using Iron Coagulant, Cellulose and Perlite

“…Already at a PIX 113 dose of 4.0 mL/L, the zeta potential of filtrate particles was definitely close to the isoelectric point (Table 13). It is possible to associate the increase in zeta potential with the decomposition of negatively charged organic matter and the neutralisation of negative charges by positively charged iron ions [67,68]. Cellulose dosage resulted in an increase in potential, which could be related to the hydrophobicity of cellulose.…”