Inactivation of E. coli by copper and silver wire in the presence of synthetic sunlight for safe drinking water

Bacterially-contaminated water is a major health concern leading to infectious diseases in emerging nations. The use of copper (Cu) and silver (Ag) wire independently, and Cu wire in combination with synthetic sunlight (SySu), were investigated as a low-cost water treatment method. Water inoculated with 1,100 colony forming units/mL of Escherichia coli was treated with one of these four treatments: (1) 50 cm²/L surface area (SA) pure Cu wire; (2) 37.8 W/m² SySu irradiation; (3) a 50 cm²/L SA pure Cu wire combined with the 37.8 W/m² SySu irradiation; and (4) 5 cm²/L pure Ag wire. An improved rate of bacterial inactivation was achieved using the combined Cu-SySu treatment method compared to either treatment applied independently. When given independently, the Ag wire treatment was more effective than the Cu wire treatment. Cu and Ag content in the water, tested at the end of the experiment, remained far below the safety limits suggested by the World Health Organization. The Cu-SySu combination method has a great potential to be used as a low-cost, re-useable, low-maintenance method of choice for purification of contaminated drinking water.