Effectiveness of slightly acidic electrolyzed water on bacteria reduction: in vitro and spray evaluation

Bacterial inactivation is a crucial aspect of sanitation and hygiene. The effectiveness of slightly acidic electrolyzed water (SAEW) for reduction or removal of Escherichia coli, Pseudomonas aeruginosa and Staphylococcus epidermidis was evaluated. The bactericidal activity of SAEW and sodium hypochlorite (NaOCl) against E. coli and P. aeruginosa were compared through in vitro experiments. The effectiveness of SAEW spray was tested against S. epidermidis. Results showed that SAEW had a more powerful bactericidal activity than NaOCl at the same available chlorine concentrations. For E. coli, SAEW decreased the bacterial counts from 8.4 log₁₀ CFU/mL to less than 3.9 log₁₀ CFU/mL; NaOCl with the same available chlorine of 0.5 mg/L, caused a decrease from 8.4 log₁₀ CFU/mL to 7.1 log₁₀ CFU/mL. For P. aeruginosa, SAEW caused bacterial counts to decrease from 8.5 log₁₀ CFU/mL to less than 4.1 log₁₀ CFU/mL against 8.5 log₁₀ CFU/mL to 6.2 log₁₀ CFU/mL for NaOCl with the same available chlorine of 0.5 mg/L. Spray experiments showed that 10 mg/L of SAEW spray decreased the bacterial counts of S. epidermidis from 3.7 log₁₀ CFU/m³ to 2.8 log₁₀ CFU/m³, with 20 mg/L causing a reduction from 3.8 log₁₀ CFU/m³ to 0 CFU/m³. The overall findings of this study indicate that SAEW may be a promising disinfectant agent either as a solution or spray.