At what pH does chlorine destroy bacteria most rapidly?

Chlorine is a commonly used disinfectant in water treatment, and its effectiveness in destroying bacteria is influenced by the pH of the water. At a pH of around 7.5, chlorine is most effective because this pH level allows for a favorable balance between free chlorine and chloramine forms, optimizing the disinfection process.

At this pH, the chlorine molecules remain adequately ionized, enhancing their ability to penetrate bacterial cell walls and react with cellular components, leading to effective bacterial inactivation. As the pH increases beyond this point, such as at 8.0, the effectiveness of chlorine can diminish due to the lower proportion of available hypochlorous acid, the more potent microbial-fighting agent.

Overall, a pH of 7.5 strikes the right balance for rapid chlorine disinfection, making it the optimal choice for effective bacterial destruction in water treatment processes.