Bacteriophage inactivation as a function of ferrous iron oxidation†
Iron-based disinfection has been promoted as a potential low-cost, low-byproduct means of virus mitigation. This research is the first to establish that virus inactivation due to ferrous iron is impacted both by the extent of iron oxidation (from ferrous to ferric iron) and the rate of iron oxidation. Log inactivation of bacteriophages increased linearly with ferrous iron concentration at low doses (<3 mg L−1 Fe), but higher doses limited disinfection, likely due to floc formation. The rate of iron oxidation was controlled by independently varying pH and dissolved oxygen concentration. Bacteriophage inactivation increased with the inverse of ferrous oxidation rate, suggesting that slower iron oxidation rates allow better contact between viruses and reactive ferrous iron. Ferrous iron showed potential for disinfection in conditions of low pH and dissolved oxygen, though these conditions preclude effective iron coagulation/flocculation.