Kinetics of inactivation of Pseudomonas aeruginosa in aqueous solutions by ozone aeration

Abstract

The effect of ozonation on the disinfection of Gram-negative strain, Pseudomonas aeruginosa was investigated as a function of time. Ozone was generated in situ using corona discharge method, with ozone concentrations ranging from (0.29–9.84) × 10^{− 5} moles L^{− 1}. The microbial inactivation kinetics followed pseudo–first-order kinetics under excess concentration conditions of ozone. With over all second-order constant, k = (4.02 ± 0.20) × 10⁴ M^{− 1} min^{− 1}, the reaction rate had first-order dependence both on the microbial count and ozone. The influence of temperature and pH on the ozone initiated disinfection of the microbe was also investigated. Molecular ozone is found more effective in disinfection than hydroxyl radicals. Probable mechanism for antimicrobial power of ozone in water systems is discussed. The ozone aeration decreased the biochemical oxygen demand (BOD) value of natural and microbe spiked waters significantly.

Keywords:

• Disinfection
• kinetics
• ozone initiated
• microbes
• Pseudomonas aeruginosa

Acknowledgments

Authors sincerely thank the National Research Foundation (Pretoria) and the University of KwaZulu-Natal for the financial support and Ms. Diane Fowlds, School of Microbiology, UKZN for the technical support.