Efficacy of copper and silver as residual disinfectants in drinking water

Abstract

Contamination events and biofilms can decrease the amount of free chlorine available in drinking water systems. The efficacy of 100 μg/L silver and 400 μg/L copper, individually and combined, were evaluated as secondary, longer-lasting residual disinfectants against Salmonella enterica serovar Typhimurium, Escherichia coli, Listeria monocytogenes, and Mycobacterium fortuitum at 24°C and 4°C. A >5.0-log10 reduction was observed in E. coli and L. monocytogenes after three hours and S. Typhimurium following seven hours of exposure to silver. M. fortuitum was the most resistant species to silver (1.11-log10 after seven hours). Copper did not significantly reduce S. Typhimurium and E. coli at 24°C; ≥2.80-log10 reductions were observed in the Gram-positive L. monocytogenes and M. fortuitum. Longer exposure times were required at 4°C to achieve significant reductions in all species. A synergistic effect was observed when silver and copper were combined at 24°C. In addition, silver was not affected by the presence of organic matter at concentrations that completely inhibited 0.2 mg/L chlorine. The results of this study suggest that combinations of silver and copper show promise as secondary residual disinfectants. They may also be used in conjunction with low chlorine levels or other disinfectants to provide additional, long-lasting residuals in distribution systems.

Copper-Polyurethane Composite Materials: Particle Size Effect on the Physical-Chemical and Antibacterial Properties

“…Recently, Cu nanoparticles (CuNPs) were shown to exhibit powerful anti-biofilm activity on pathogen bacteria such as Escherichia coli, Salmonella typhi, Shigella flexneri , and Pseudomonas aeruginosa , because cell death was mediated by massive destruction of the plasmatic cell membrane and the production of high concentrations of reactive oxygen species also known as ROS [ 33 ]. Similar results have also recently been published in terms of the use of Cu oxide (CuO) NPs [ 34 , 35 ].…”

Removal of MS-2 Viruses with Recyclable Magnetic Nanoparticles Coated with Metal Ions

“…35 The residual metal ions in the water can also serve as a longterm disinfectant during the distribution of treated water to prevent target viruses from growing again. 36 Thus, the removal of MS-2 with Mag-PCMA-MI should not lead to additional environmental effects.…”

“…Although a small fraction of metal ions will leach into the water after removal (0.8% of adsorbed Ag + , 0.6% of adsorbed Cu 2+ , and 0.9% of adsorbed Fe 3+ ), the concentration of residual metal ions can be maintained below a safe level by adjusting the amount of metal ions coated onto Mag-PCMA during the sorption process . The residual metal ions in the water can also serve as a long-term disinfectant during the distribution of treated water to prevent target viruses from growing again . Thus, the removal of MS-2 with Mag-PCMA-MI should not lead to additional environmental effects.…”

Novel disinfection method for toxic cyanobacteria (Oscillatoria tenuis) and simultaneous removal of cyanotoxins aided by recyclable magnetic nanoparticles

“…Silver nitrate, copper sulfate, nitric acid, sulfuric acid, sodium hydroxide, sodium chloride and calcium carbonate were purchased from Fisher Scientific (USA). Ag + and Cu 2+ are selected as the metal ions disinfectants as they are commonly used as algaecides in many studies [3,27,29] and have demonstrated effectiveness. Our innovative approach allows the recovery of the metal ions for reuse, making it less expensive and more sustainable.…”