[Coliform bacteria removal from contaminated water using nanosilver]

ABSTRACT

Although silver can be used as an effective water disinfectant, it has some disadvantages such as its high costs and darkening of the skin and mucous membrane due to long-term exposure to high silver concentrations. Nanotechnology can solve such problems through reduction of silver content. The aim of this study was to evaluate the effect of nanosilver on removing the coliform bacteria from contaminated water. This bench-scale experimental study was carried out in a batch system on artificially contaminated water samples prepared by adding 5 ml effluent to 60 liters of tap water. In each run, the nanosilver suspension [30-180 microgL-1] was added to 6 containers [500 ml] of contaminated water and then a sample was taken every 20 minutes for a 100-minute period and tested for coliform according to the standard methods book. Results revealed that the coliform bacteria removal significantly increased with increasing the contact time of nonosilver [P=0.001], but there was no significant correlation between the nanosilver concentrations and coliform removal [P=0.6]. The maximum coliform removal [92.41%] was achieved within 100 minutes contact time for 60 microgL-1 of silver. Although nanosilver treatment is effective in removing coliform from contaminated water, further researches are required to study the efficacy of drinking water disinfection