What role does pH play in water disinfection effectiveness?

The correct answer highlights the significant relationship between pH levels and the effectiveness of disinfectants, particularly chlorine, in water treatment. Chlorine is one of the most widely used disinfectants for water sanitation and its effectiveness can vary depending on the pH of the water.

When the pH of water is higher, specifically above a neutral level of 7, the presence of hypochlorous acid (the more effective form of chlorine) decreases, while the formation of hypochlorite ions increases. Hypochlorous acid is more effective at killing pathogens and microorganisms, while hypochlorite ions are less effective. Thus, if the pH rises, chlorine's disinfection power diminishes, making it less effective in sanitizing water.

Conversely, at lower pH levels, more hypochlorous acid is available, which increases the efficacy of chlorine as a disinfectant. Therefore, maintaining an optimal pH level is crucial for ensuring that chlorine remains effective in water disinfection processes. This illustrates the importance of monitoring and adjusting pH levels in water treatment facilities to enhance sanitation outcomes.