1. CT Values Dan Lanteigne
CRTPA AGM 2017
CT Values
Dan Lanteigne

2. CRTPA AGM CT Values
CT Values are an important part of calculating disinfectant dosage for the chlorination of drinking water. A CT value is the product of the concentration of a disinfectant (e.g. free chlorine) and the contact time with the water being disinfected. It is typically expressed in units of mg-min/L.

3. CRTPA AGM 2017 CT Values
Chemical disinfection CT values are calculated by multiplying the disinfectant residual concentration (in mg ⁄ L) by the disinfectant contact time (in minutes).
CT = Concentration (mg ⁄ L) × Time (minutes)

4. CRTPA AGM 2017 CT Values
The goal of disinfection is the inactivation of microorganisms. This depends on: the microorganism, the disinfectant being used, the concentration of the disinfectant, the contact time, and the temperature and pH of the water.

5. CRTPA AGM 2017 CT Values

6. CRTPA AGM 2017 CT Values
A log removal value (LRV) is a measure of the ability of a treatment processes to remove pathogenic microorganisms.

7. CRTPA AGM 2017 CT Values
First Nations communities follow the Ontario drinking water guidelines.
3 log 99.9% on protozoa
4 log 99.99% on viruses

8. CRTPA AGM 2017 CT Values
Depending on the treatment process, Ct values and source of water will dictate the log removal credit the process will be granted.

9. CRTPA AGM 2017 CT Values

10. CRTPA AGM 2017 CT Values Calculating CT values
CT = Concentration of free chlorine (C mg/L) * contact time (T Minutes)

11. CRTPA AGM 2017 CT Values
Essentially Ct values are used in conjunction with the treatment process to achieve the required log removal