Metals Disinfection of E. coli in Synthetic Ground Water

摘要

Sustainable access to clean and safe drinking water remains a global challenge as large numbers of people still consume water that is not clean and safe. Diarrhea; a preventable waterborne disease remains the major cause of death among children under the age of 5 in most developing countries of the world. Several technologies have been invented to provide point-of-use water treatment. The cost of these technologies often limits their application. This study seeks to evaluate the use of several metals at concentrations below the World Health Organization recommended guideline values in drinking water as potential disinfectants for point-of-use water treatment. The bactericidal activity of Ag~+, Cu~(2+), Co~(2+), Ni~(2+) and Zn~(2+) against a non-pathogenic strain of E. coli in synthetic ground water was evaluated. Different concentration of silver varying from 20-80 ug/L were tested for disinfection efficiency. Samples were taken at 0, 2, 4, 6, 8, 18 and 24-hour time points. Similarly, copper concentrations were varied in the range of 200-800 ug/L. Samples were withdrawn at 0, 4,6,8,12,18 and 24 hours to count viable bacteria using the IDEXX technique. Results showed that 80 µg/L of Ag~+ gives 41og-8.51og reduction of E. coli between 2 to 24 hours. While, 800 ug/L of Cu~(2+) showed llog-71og reduction of E. coli in the range of 4 to 24 hours. A very high concentration (2800 ug/L) of Zn showed llog-5.21og reduction of E. coli between 24-72 hours. Whereas, Co~(2+) and Ni~(2+) did not show any significant disinfection of E. coli even after 72 hours.