Water Treatment Plant Operator Practice Exam

The CT value, which is a product of the concentration of chlorine (C) and the contact time (T) with the water, plays a crucial role in ensuring effective chlorine disinfection. To effectively inactivate pathogens in water, both an adequate concentration of chlorine and sufficient contact time are required. However, water temperature and pH also significantly influence the efficacy of chlorine disinfection.

Water temperature affects the reaction rates; higher temperatures generally increase the efficiency of chlorine in disinfecting water. Similarly, pH impacts the form of chlorine present in water, with different forms having varying disinfecting capabilities. Chlorine is more effective as a disinfectant at lower pH levels, as a larger proportion exists as hypochlorous acid, which is a stronger disinfectant compared to hypochlorite ion, more prevalent at higher pH levels.

Given that all three parameters—water temperature, pH level, and CT value—collectively contribute to the effectiveness of chlorine disinfection, acknowledging the importance of each in the disinfection process justifies why selecting all of the options is accurate. Each aspect must be carefully monitored and managed to ensure optimal disinfection and water quality.