Ozone disinfection Comparison of disinfectants
Comparison between ozone and other disinfectants
| Ozone is a very powerful disinfectant. Table 1 compares Ct-values (concentration * time) of various disinfectants for the deactivation of viruses. |
Allthough chlorine is very suitable for the deactivation of bacteria and viruses, it cannot be used to deactivate protozoa.
Table 2 shows the disinfection rate for the Giardia cyst. In this table you can see that chlorine and chloramines have lower Ct-values. This means that ozone is a more powerful disinfectant to deactivate this microorganism.
The protozoa Cryptosporidium is hardly deactivated by chlorine and chloramines [30,31]. The Ct-value for deactivation by chlorine varies between 3000 and 4000 mg min/L for 1-log deactivation (= 90% deactivation). Both tables are derived from the Enviromental Protection Agency (EPA) .
Table 1: Ct-values for the deactivation of viruses by various disinfectants
Table 2: Ct-values for the deactivation of Giardia cysts by various disinfectants
The benefit of ozone is that it influences pH and temperature minimally on a broad spectrum. Allthough ozone solubility decreases when temperatures rise, disinfection rates increase per 10°C (factor 2 or 3). Within the range of 0 – 30°C, these two factors diminish one another . The disinfection rate of ozone hardly changes in a pH range of 6 – 8,5 . For certain resistant microorganisms (such as Giardia Muris), the disinfection rate increases at higher pH values [30,34]. For other species of microorganisms, this is the other way around.