Florida Wastewater Practice Test

What is a primary disadvantage of using a hypochlorinator in treatment processes?

1. It increases dissolved oxygen levels

2. It lowers the pH and increases disinfection

3. It increases pH and decreases disinfection

4. It raises total suspended solids

The correct answer is: It increases pH and decreases disinfection

Using a hypochlorinator in treatment processes can lead to an increase in pH which can subsequently affect disinfection efficacy. The addition of chlorine can cause certain chemical reactions in the water that may alter its pH levels. When the pH is elevated, it can lead to decreased effectiveness of chlorine disinfection due to changes in the speciation of chlorine; for example, higher pH levels can result in a lower concentration of hypochlorous acid, the more effective form of chlorine used for disinfection. Therefore, if the pH increases, there can be a consequential decrease in disinfection capability, making this a notable disadvantage of hypochlorination. In the context of treatment processes, understanding the chemistry involved in disinfection is crucial, as optimal pH ranges are important for efficient pathogen inactivation.