Sulfate Radical-Induced Disinfection of Pathogenic Escherichia coli O157:H7 via Iron-Activated Persulfate

Sulfate radical (SO 4 •– ) has been increasingly applied as an efficient oxidant for water treatment in recent years. This study investigated the disinfection efficacy of SO 4 •– on Escherichia coli O157:H7, i.e., a pathogenic strain of E. coli on the U.S. Environmental Protection Agency’s Contaminant Candidate List. SO 4 •– was generated via persulfate (S 2 O 8 2– ) activation using ferrous iron (Fe 2+ ). Results showed that S 2 O 8 2– activation and subsequent SO 4 •– exposure induced the loss of pathogenic E. coli viability. The disinfection, kinetics exhibited an induction phase followed by a rapid first-order decay phase. Dosages of S 2 O 8 2– and Fe 2+ significantly impacted the duration of the induction phase and the rate of disinfection; on the other hand, the solution pH preferentially impacted the induction time, and the dosage of Fe 3+ -reducing agent hydroxylamine (NH 2 OH) impacted the rate of disinfection. The disinfection kinetics depended on the CT equivalence of total SO 4 •– exposure. Results showed that SO 4 •– exposure initiated the loss of E. coli O157:H7 cell viability 5 times faster than HO • exposure did. This unique feature of SO 4 •– is possibly associated with its highly selective reactivity with electron-rich moieties on the surface of E. coli O157:H7 cell membranes.