LAUSR

Abstract To avoid the unfavorable SO 4 - · consumption by excessive FeII in traditional FeII-activated peroxymonosulfate (PMS) system, this study investigates the conditioning performance of the electrochemical-FeII activated PMS, i.e., E-FeII-PMS, towards anaerobically digested sludge (ADS) by comparing with chemical-FeII activated PMS (C-FeII-PMS). At equilibrium pH of 6.0, the capillary suction time (CST) of raw ADS was decreased by 51.2% for C-FeII-PMS and 67.6% for E-FeII-PMS with the same total FeII dose of 25 mg/g DS. E-FeII-PMS is more efficient to degrade EPS and damage cells, and thus improves the release of bound water and intracellular water greatly. The cell viability ratios remarkably decreases from 71.8% for raw ADS to 22.6% for C-FeII-PMS and 10.1% for E-FeII-PMS. Moreover, E-FeII-PMS significantly reduces the total PN contents to 41.9% and the total PS contents to 43.8% for EPS fraction. The Fe2+ concentrations in supernatant was determined to be 191.3 mg/L for C-FeII-PMS and much lower of 36.9 mg/L for E-FeII-PMS after 15 min reaction, and the continuous introduction of FeII in E-FeII-PMS achieves stable Fe2+ concentrations and minimizes SO 4 - · consumption by the excessive FeII in C-FeII-PMS as much as possible. Otherwise, FeIII-FeII cycling at cathode side also increases FeII utilization.