Combined Ozone and Ultraviolet Inactivation of Escherichia coli

• Published in: Journal of environmental science and health. Part A, Toxic/hazardous substances & environmental engineering Vol. 41; no. 6; pp. 1043 - 1055
• Main Authors: MAGBANUA, BENJAMIN S., SAVANT, GAURAV, TRUAX, DENNIS D.
• Format: Journal Article
• Language: English
• Published: England Taylor & Francis Group 01-07-2006
• Subjects: Colony Count, Microbial; Disinfectants - pharmacology; Disinfection; Disinfection - methods; Dosage; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - isolation & purification; Escherichia coli - radiation effects; Estimates; Hydroxyl radicals; Inactivation; Kinetic models; Kinetics; Mathematical models; Microorganisms; Ozone; Ozone - pharmacology; Potable water; Ultraviolet; Ultraviolet radiation; Ultraviolet Rays; Waste Disposal, Fluid; Water Pollutants - isolation & purification; Water Pollutants - radiation effects; Water Purification - methods; Water Supply; Water treatment
• ISSN: 1093-4529; 1532-4117
• DOI: 10.1080/10934520600620279

The kinetics of Escherichia coli inactivation using ozone and ultraviolet (UV) radiation, separately and simultaneously, was evaluated at 25°C in buffered (pH 6.0, 7.0 and 8.0), demand-free media. While ozone was found to be a stronger disinfectant than UV radiation, using both simultaneously was more effective than using them individually. Inactivation kinetics was pseudo first-order for the three treatment processes, while the disinfection rate was a linear function of the disinfectant dose. The synergism observed in microbial inactivation when the disinfectant processes were combined was illustrated by estimates of kinetic model parameters. This synergy was attributed to the generation of hydroxyl radicals via ozone photolysis. Subsequently, dosage calculations, as based on disinfectant level and exposure time, indicated that the simultaneous use of UV and ozone could substantially reduce their individual doses.