عنوان مقاله [English]
Ozone, as a powerful oxidant and disinfectant, has found wide applications in water treatment since early 20th century. A concentration level of 0.4mg/L for 5 minutes is considered to be sufficient for conventional disinfection in water treatment. The ozonation-chlorination process, with chlorine as a supplementary disinfectant, has been used since 2003 in phase 1 of Isfahan Water Treatment Plant with an influent capacity of 5m3/s. The object of this study is to determine ozone efficiency in decreasing total organic carbon, total coliform, and fecal coliform in raw water. In this study, 25 samples over the 3 months of study were collected from the influent, after both primary and secondary ozonation stages, and from the effluent from Isfahan Water Treatment Plant. The microbial test and total organic carbon (TOC) were measured. The results showed significant differences (p0.05). The result obtained from this study revealed that the application of ozone as a disinfectant in the water treatment plant in Isfahan is not adequately efficient and that final chlorination may, therefore, be necessary.