Inactivation of Viruses in Water by Biogenic Silver: Innovative and Environmentally Friendly Disinfection Technique

The presence of enteric viruses in drinking water is a potential health risk. Growing interest has arisen in nanometals for water disinfection, in particular the use of silver based nanotechnology. In this study, Lactobacillus fermentum served as reducing agent and bacterial carrier matrix for zerovalent silver nanoparticles, referred to as biogenic Ag0. The antiviral action of biogenic Ag0 was examined in water, spiked with an Enterobacter aerogenes infecting bacteriophage (UZ1). Addition of 5.4 mg L-1 biogenic Ag0 caused a 4.0 log decrease of the phage after 1 h, whereas the use of chemically produced silver nanoparticles (nAg0) showed no inactivation within the same time frame. A control experiment with 5.4 mg L-1 ionic Ag+ resulted in a similar inactivation after 5 h only. The antiviral properties of biogenic Ag0 were also demonstrated on the murine norovirus 1 (MNV-1), a model organism for human noroviruses. Biogenic Ag0 was applied to an electropositive cartridge filter to evaluate its ability for continuous disinfection. Addition of 31.25 mg m-2 biogenic Ag0 on the filter (135 mg biogenic Ag0 kg-1 filter media) caused a 3.8 log decline of the virus. On the contrary, only a 1.5 log decrease could be obtained with the original filter. This type of filters coated with biogenic Ag0 might become a sustainable alternative for water disinfection or can enhance disinfection efficacy in conjunction with existing techniques.