Advantages Of Ozone
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Using an Ozone Generator on any job demonstrates professionalism and gives you a UNIQUE ADVANTAGE over your competitors and save you money.
If You Are Not Offering Ozone Treatments You Are Missing A Very Lucrative Business Opportunity.
Anyone can use a squeeze bottle and cloth, when you walk in with an Ozone Generator and explain a little about the safety and environmental friendliness of ozone and how ozone gets into every nook and cranny, to safely destroy pathogens, your clients will have much more respect for your company and more trust in your services and be amazed at the results you provide.
Ozone Disinfection/Ozone Contact Time Kinetics
Water is disinfected but never completely sterilized in the water treatment process. This disinfection is a two part process that includes:
In "water treatment terms" 1 log inactivation is referred to as 1 credit inactivation. Different types of filtration are assigned certain removal credits. For example, conventional filtration is worth 2.5 credits for Giardia cysts. Since the EPA requires 3 log (credit) removal, an additional 0.5 credit inactivation from disinfection must be attained.
Varying degrees of disinfection can be attained by altering the type and concentration of disinfectant, as well as the time water is in contact with the disinfectant. The decision to use one type of disinfectant versus another will set the precedence for the remainder of the values needed to attain the proper disinfection. The time untreated water is exposed to the disinfectant and the concentration of that disinfectant are the main factors in the equation that will be discussed in the next section. (Notice that the units of contact time are (mg/l)(min).)
A relationship between kill efficiency and contact time, was developed by Harriet Chick while she was a Fellow in the Pasteur institute in Paris, France. The research yielded data supporting her relationship that is shown in Figure 2 below. (No) represents the initial number of organisms and N is the number of organisms at time T. As contact time between water and disinfectant increases, the ratio of No/N decreases as Chick's Law predicts.
Figure 2 Taken from R.C. Hoehn’s CE 4104 Spring Notes
Watson later modified Chick's equation to account for varying types of disinfectants. He developed coefficients that better represented the strength of the disinfectant as well as the pH of the water. From this research, the coefficient of specific lethality (lambda) was developed. Watson’s modification of Chick’s equation is shown below.
Factors Affecting C*t Values
· As pH increases the value of C*t also needs to be increased. This can be explained by examining the effects of pH on free chlorine. As the pH increases, more of the weak disinfectant (OCl-) exists than the strong disinfectant (HOCl-), thus increasing the C*t value. Refer to Table 1 below.
· The greater log removal needed, the greater the C*t needs to be, as can be seen in Table 1.
Table 1: C*t for Removal of Giardia Cysts in Relation to Log Removal and pH
Information from the Virginia Department of Health Waterworks Regulations
· The strength of a disinfectant directly affects the C*t. For a weak disinfectant, the C*t will have to be higher than for a strong disinfectant. As Table 2 below shows, ozone is the strongest disinfectant, thus the C*t value required is less when compared to chlorine and chlorine dioxide.
· Different organisms have different resistances to disinfectants. If an organism has a strong resistance to a certain disinfectant, the C*t will be higher than for an organism with a weaker resistance. Refer to Table 2 below.
Table 2: C*t Values for the 99% Inactivation at 5 Degrees Celsius of Organisms Using Various Disinfectants
* 99% inactivation at 25 degrees CHoff, J.C., Inactivation of Microbial Agents by Chemical Disinfectants, EPA/600/2-86/067, 1986
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Disclaimer: It is important to mention that none of the products presented are a medicine and are not being promoted by us as such. Any information is for educational purposes only and is not intended to diagnose any illness. In any case of illness it is highly recommended to contact a qualified medical practitioner.
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