emand and ozone transfer efficiency, the article says. This yielded high ozone-transfer efficiency and rapid initial ozone demand. Ozone demand resulted in relatively inefficient and variable inactivation of Escherichia coli and required ozone doses of approximately 10 mg/L to approach compliance with discharge permit limitations. Ozonation also yielded small improvements in UV transmittance of effluent samples; preozonation yielded only modest benefits with respect to subsequent UV254 irradiation, the article says.
The study found that compliance with discharge permit limitations could be achieved consistently with a UV254 dose of 12.4 mJ/cm2 at a preozonation dose of 2 to 3 mg/L. Without preozonation, consistent compliance was achieved with a UV dose of 16.5 mJ/cm2. And according to the article, “no evidence of synergism between ozone and UV254 radiation was found in the measured inactivation responses of E. coli.”
The article, “Ozone and UV254 Radiation for Municipal Wastewater Disinfection,” appears in the November issue of Water Environment Research and can be downloaded free at http://goo.gl/PFqHm.