Utilizing silver and copper ions for bacterial disinfection and subsequent removal of ions to supply safe drinking water

Abstract

Inadequate access to safe drinking water is a critical challenge facing millions of people in third world countries. Ionic silver and copper both have proven biocidal capacities and are used in various water treatment applications such as cooling water and swimming pool disinfection. However, these methods of bacterial inactivation have not been expanded to include drinking water treatment due to the inherent health risks associated with consuming high concentrations of the metals which can accumulate in the systems, and therefore also the treated water. The goal of this research was to utilize copper and silver ions to inactivate bacteria in order to provide a method of drinking water treatment that does not require the use of toxic chemicals or large amounts of electricity, as under resourced communities do not have reliable access to these resources. This research also examined methods of removing or recovering residual metal from treated water. The ability to reduce the residual metal concentration not only allows the effluent to meet drinking water guidelines, it also allows for the concentration of metal used during disinfection to be significantly larger than used in previous research. By using a metal concentration that is one or two orders of magnitude higher than typical silver or copper ionization the disinfection is able to be carried out faster and to a fuller extent, all the while not increasing the risk to the consumer as the metal concentration can be decreased to within an acceptable range post disinfection. The lab scale, proof of concept methods used in this research show strong potential as prospective techniques to provide safe drinking water to people in third world nations.