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Comparison of ozone disinfectants
Ozone is a very effective disinfectant. The CT values (concentration * time) of various disinfectants were compared in Table 1.
Although chlorine is very suitable for inactivation of bacteria and viruses, it cannot be used to inactivate protozoa.
Table 2 shows the disinfection rate of Giardia cysts. In this table, you can see that chlorine and chloramine have lower CT values. This means that ozone is a more effective disinfectant to inactivate the microorganism.
Cryptosporidium protozoa is difficult to be inactivated by chlorine and chloramine. The CT values of chlorine inactivation ranged from 3000 to 4000 mg min / L, and 1-log inactivation (= 90%). Both tables are from the Environmental Protection Agency (EPA).
Table 1: CT value of various disinfectants to virus
Table 2: CT values of various disinfectants inactivating Giardia cysts
The advantage of ozone is that it has the least effect on pH and temperature, and has a broad spectrum. Although the solubility of ozone decreases with the increase of temperature, the solubility of ozone decreases with the increase of temperature ° C disinfection rate will increase (factor 2 or 3). At 0 - 30 ° Within the range of C, the two factors decrease with each other. The disinfection rate of ozone hardly changed in the range of pH 6-8,5. For some drug-resistant microorganisms (such as Giardia), the disinfection rate increased at higher pH value. For other kinds of microbes, the opposite is true.
Other benefits of using ozone are:
-There is no residual taste or odor after treatment
-The formation of disinfection by-products is very small (mainly in the absence of bromine)
Ozone can remove the precursor of disinfection by-products (substances causing the formation of disinfection by-products)
Ozone is not always the most suitable disinfectant. Ozone is not suitable to maintain the residual concentration (secondary disinfectant), resulting in its relatively rapid decomposition in water. Chlorine is more suitable for residue formation.