Modelling inactivation kinetics of waterborne pathogens in municipal wastewater using ozone.
Mecha, Achisa C. Onyango, Maurice S. Ochien, Aoyi Momba, Maggy N.B.
Mecha, Achisa C.
Onyango, Maurice S.
Ochien, Aoyi
Momba, Maggy N.B.
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Abstract
Microbial water pollution is a key concern leading to waterborne diseases. This study evaluated the disinfection of wastewater using ozonation. The following aspects were investigated: inactivation efficiency against Escherichia coli, Salmonella species, Shigella species, and Vibrio cholerae; modelling of inactivation kinetics using disinfection models; and evaluation of microbial regrowth studies. 99% bacterial inactivation was obtained within 15 min, irrespective of the water matrix, showing the strong oxidizing potential of ozone. The disinfection data were fitted into the log-linear and Weibull models. The survival curves were non-linear and fitted the Weibull model (fractional bias and normalized mean square error equal to 0.0), especially at high bacterial concentrations (106 CFU/mL). The inactivation occurred in two stages: an initial rapid stage (15 min) and a final slow stage exhibiting a tailing mechanism (15-45 min) probably as a result of the self-defence mechanisms adopted by the bacteria to limit oxidative stress. Considering the pattern of survival curves, no significant differences (p > 0.05) were observed among the four tested bacterial species; thus showing that ozone was effective against all the bacteria tested. There was minimal bacterial regrowth in the treated samples 24h after ozone disinfection with reactivation values of 0-5% obtained.
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Date
2019-12-05
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Publisher
Advanced Research Publications
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Keywords
Disinfection, Modelling, Municipal wastewater, Ozone, Regrowth