What does CT stand for in disinfection and what does it represent?

What does CT stand for in disinfection and what does it represent?

• A. Concentration and Contact Time
• B. Temperature and Time
• C. Concentration × Time
• D. Pressure × Time

Answer: (C)

CT stands for Concentration × Time. It represents the exposure of water to the disinfectant, calculated by multiplying the residual disinfectant concentration (mg/L) by the contact time (minutes). This product summarizes how much disinfection action the water experiences. In practice, CT is used to ensure adequate disinfection by comparing the value to a target: higher concentration or longer contact increases CT and typically leads to more inactivation of pathogens. For example, 2 mg/L of chlorine for 15 minutes gives a CT of 30 mg/L·min; 3 mg/L for 10 minutes also gives 30 mg/L·min. Temperature and pH can affect how effectively the disinfectant works, but CT provides the standard way to express and compare disinfection exposure.

CT stands for Concentration × Time. It represents the exposure of water to the disinfectant, calculated by multiplying the residual disinfectant concentration (mg/L) by the contact time (minutes). This product summarizes how much disinfection action the water experiences. In practice, CT is used to ensure adequate disinfection by comparing the value to a target: higher concentration or longer contact increases CT and typically leads to more inactivation of pathogens. For example, 2 mg/L of chlorine for 15 minutes gives a CT of 30 mg/L·min; 3 mg/L for 10 minutes also gives 30 mg/L·min. Temperature and pH can affect how effectively the disinfectant works, but CT provides the standard way to express and compare disinfection exposure.