Florida Wastewater Practice Test

The relationship between pH and disinfection can be summarized as?

1. The higher the pH, the greater the disinfection

2. The lower the pH, the greater the disinfection

3. pH has no effect on disinfection

4. Disinfection is optimal at neutral pH

The correct answer is: The lower the pH, the greater the disinfection

The relationship between pH and disinfection is significant because pH levels can influence the effectiveness of various disinfectants, especially chlorine-based ones. At lower pH values, chlorine exists primarily in its hypochlorous acid form (HOCl), which is a more potent disinfectant than its ionized form, hypochlorite ion (OCl-). This means that as the pH decreases, the proportion of the more effective hypochlorous acid increases, thereby enhancing disinfection efficiency. In many wastewater treatment processes, maintaining a lower pH is key to ensuring adequate disinfection. It allows for a more effective pathogen inactivation and improved overall treatment efficacy. Therefore, the correct choice reflects the understanding that lower pH levels facilitate greater disinfection capabilities, particularly through the optimal functioning of chlorination processes in wastewater management.