Int.J.Curr.Microbiol.App.Sci (2013) 2(4): 1-11 1 Original Research Article The Antibacterial Activity of Graphite Oxide, Silver, Impregnated Graphite Oxide with Silver and GO-Coated Sand Nanoparticles against Waterborne Pathogenic E.coli BL21 I.Sheet 1 , H.Holail 1 , Z.Olama 1* , A.Kabbani 2 and M.Hines 3 1 Department of Biological and Environmental Sciences, Faculty of Science, Beirut Arab University, Lebanon. 2 School of Arts and Sciences, Department of Chemistry, Lebanese American University, Lebanon. 3 College of Sciences, Department of Biological Sciences, University of Massachusetts Lowell, U.S.A *Corresponding author e-mail: zakia.olama@bau.edu.lb ABSTRACT Introduction Microbial contamination of surface, ground and drinking waters is an environmental problem around the world that poses a great threat to human health. The presence of coliforms in drinking water is considered to be a public health concern since detection of these microorganisms contributed either to faecal contamination or an exogenous contamination with enteric and other relevant microbial pathogens. It is paramount to protect water sources in our country from any source of contamination, and to construct water disinfection and delivery systems, as well as sewage ISSN: 2319-7706 Volume 2 Number 4 (2013) pp. 1-11 http://www.ijcmas.com Keywords Antibacterial activity; Graphite oxide; GO-Coated Sand; Silver nanoparticles; Escherichia coli BL21. Microbial contamination of drinking water is an environmental problem around the world that poses a great threat to human health and effective treatments are needed to solve such water pollution problems. In the present study, Nanostructured Graphite Oxide (GO) and low-cost GO coated with silver or sand nanoparticles were developed and characterized. Antibacterial efficacy of these nanoparticles was investigated using waterborne pathogenic E.coli strain. Two methods were used to test the antibacterial effect of the prepared nanoparticles against the bacterium under test: (a) Plate Assay Method and (b) Shake Flask Test. The results revealed that both tests showed slight inhibition of pathogenic E.coli with sand and Graphite Oxide nanoparticles. 0.1 to 1.5 mol.L -1 of impregnated GO with silver and GO-Coated Sand showed a higher bactericidal effect against the bacterium under test. Furthermore, the results showed the highest bacterial removal efficiency (100%) by the Coated Graphite Oxide and the lowest by sand filters with 17.9 % to 88.9 % reduction rate from 0 to 24 hours, respectively. Therefore, this study suggests that the filter system with GO composite can be used as an effective filter for water disinfection and production of potable and pathogens free drinking water.