Photocatalytic Removal of Escherichia Coli from water by ZnO Nanoparticles Synthesized by the hydrothermal method

Abstract Background and Objective :Photocatalyticprocesses are developed and investigated as new technologies for the purpose of water disinfection.It was a very good process and can be very effective with no side products.The purpose of this study is Photocatalytic removal of Escherichia Coli from water by ZnO Nanoparticlessynthesized by the hydrothermal method. Materials and Methods :After the synthesized of ZnO Nanoparticles ,characteristics of nanoparticles was determined by using SEM electron microscopy and X-ray diffractionmethods. specified number of samples that contaminated with bacteria exposed to UV light with an intensity of 30 watt.And bacteria removal efficiency were examined in equal pH (5.5, 7 and 9), nanoparticle concentration (25/0? 5/0? 1? 2 ?5) grams per liter, the number of bacteria in the samples (102×5/1? 103×5/1? 105×5/1 ? 108×5/1) and exposure times (10, 20, 30, 45 and 60) minutes. Results :efficiency removal of E. coli in pH=7 is higher. Also with increasing nanoparticle concentration from 25/0 to 5to 5 grams per liter, efficiency Increased from 40 to 98/5 percent. Removal efficiency was enhanced with Increasing the contact time and reduce the number of E. coli bacteria . Conclusion :Nano-photocatalytic process has become to a new and efficient method for the removal of environmental pollutants.The use of zinc oxide nanoparticles with ultraviolet light is safe antibacterial methodand can be used in the purification of biological materials .