Mojtaba Khani - Master of science student,Department of chemical engineering,Islamic Azad University South Tehran
Majid Bahmani - Department of Chemistry, Tarbiat Moalem University, Tehran, Dr Mofateh Street
MM Akbarnejad۳ - Department of chemical engineering,Islamic Azad University South Tehran,Technical college,Ahang highway

The biocidal ac vity of UV irradiated 0.5 nm TiO2 nanopowder suspension was utilized as photocatalyst in this study to sterilize a suspension of Escherichia coli (E.Coli) strain ATCC 8739 in real water samples. A batch experimental set up consis ng of 150 ml of 0.25-1 gr/l of Degussa P25 TiO2 nanopowder and 105-106 Colony Forming Units (CFU)/ml of the E.Coli suspension in appropriate buffered solu on was used. Two 8W (Philips, BLB) black lamps (300-420 nm) were used as the source of UV irradiation. Effect of variation of TiO2 nanopowder concentration, UV irradiation intensity and O2 sparging were investigated experimentally. Experiments results show that increasing the TiO2 concentration and UV irradiation intensity increase the disinfection rates of the E.Coli suspension. However, the highest disinfection rate was obtained at a TiO2 concentra on of 0.5 gr/l and further increase in TiO2 concentration does not does not improve the disinfection rate.

E.Coli, disinfection, TiO2 nanopowder, photocatalyst