Abstract:
The effect of ozone on the inactivation of two Gram-negative strains (Escherichia coli
and Pseudomonas aeruginosa) and one Gram-positive endospore (Bacillus subtilis)
bacteria, often present in water and the cause of some waterborne diseases was
investigated as a function of ozone concentration and ozonation duration. Ozone was
generated in situ using corona discharge methods where the ozone concentration ranged
from 0.906 - 4.724 mg/L and the inactivation of the three microbes followed pseudo-first
order kinetics with respect to the microbes. Three microbes were cultured and the
influence of temperature and pH of the aqueous systems on the ozone initiated
inactivation rate of the three microbes was also investigated. This study reports that
molecular ozone is more effective than hydroxyl radicals initiated by the ozone chain
reactions. Two suggested mechanisms for the antimicrobial effectiveness of ozone in
water systems from the literature is discussed. The study also found that ozonation
significantly decreased the Biological Oxygen Demand (BOD) value of natural water.
