Negative effect of high pH on biocidal efficacy of copper and silver ions in controlling Legionella pneumophila.

摘要: ABSTRACT Copper-silver (Cu-Ag) ionization has effectively controlled Legionella spp. in the hot water systems of numerous hospitals. However, it was ineffective at controlling one Ohio hospital despite confirmation adequate total concentrations copper and silver ions. The pH this found to be 8.5 9.0. purpose study investigate impact other quality parameters, including alkalinity (HCO3−), hardness (Ca2+ Mg2+), amount dissolved organic carbon (DOC), on control by Cu-Ag ionization. Initial ions used batch experiments were 3 × 106 CFU/ml 0.4 0.08 mg/liter, respectively. Changes bicarbonate ion concentration (50, 100, 150 mg/liter), 50 100 mg/liter; Mg2+ 40 80 level DOC (0.5 2 mg/liter) had no significant efficacy killing a neutral pH. When elevated 9 these experiments, achieved only 10-fold reduction number organisms 24 h, compared millionfold decrease 7.0. Silver able achieve h all ranges parameters tested. Precipitation insoluble complexes observed above 6.0. These results suggest that may an important factor copper-silver systems.