Sulfate Radical-Induced Disinfection of Pathogenic Escherichia coli O157:H7 via Iron-Activated Persulfate
2017
Wordofa, Dawit N. | Walker, Sharon L. | Liu, Haizhou
Sulfate radical (SO₄•–) has been increasingly applied as an efficient oxidant for water treatment in recent years. This study investigated the disinfection efficacy of SO₄•– on Escherichia coli O157:H7, i.e., a pathogenic strain of E. coli on the U.S. Environmental Protection Agency’s Contaminant Candidate List. SO₄•– was generated via persulfate (S₂O₈²–) activation using ferrous iron (Fe²⁺). Results showed that S₂O₈²– activation and subsequent SO₄•– 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 S₂O₈²– and Fe²⁺ 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 Fe³⁺-reducing agent hydroxylamine (NH₂OH) impacted the rate of disinfection. The disinfection kinetics depended on the CT equivalence of total SO₄•– exposure. Results showed that SO₄•– exposure initiated the loss of E. coli O157:H7 cell viability 5 times faster than HO• exposure did. This unique feature of SO₄•– is possibly associated with its highly selective reactivity with electron-rich moieties on the surface of E. coli O157:H7 cell membranes.
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