Efficient Bacterial Inactivation by Transition Metal Catalyzed Auto-Oxidation of Sulfite

Disinfection is an indispensable process in wastewater treatment plants. New bacterial inactivation technologies are of increasing interest and persistent demand. A category of simple and efficient bactericidal systems have been established in this study, that is, the combination of divalent transition metal (Mn­(II), Co­(II), Fe­(II), or Cu­(II)) and sulfite. In these systems, metal catalyzed auto-oxidation of sulfite was manifested to generate reactive intermediary SO₄^•– that played the major role in Escherichia coli inactivation at pH 5–8.5. Increasing concentrations of metal ion or sulfite, and lower pH, led to higher bacterial deaths. Bacterial inactivation by Me­(II)/sulfite systems was demonstrated to be a surface-bound oxidative damage process through destructing vital cellular components, such as NADH and proteins. Additionally, the developed Me­(II)/sulfite systems also potently killed other microbial pathogens, that is, Pseudomonas aeruginosa, Bacillus subtilis, and Cu­(II)-antibiotic-resistant E. coli. The efficacy of Me­(II)/sulfite in treating real water samples was further tested with two sewages from a wastewater treatment plant and a natural lake water body, and Cu­(II)/sulfite and Co­(II)/sulfite rapidly inactivated viable bacteria regardless of bacteria species and cell density, therefore holding great promises for wastewater disinfection.