Which factor is crucial for effective chlorine disinfection in water treatment?

The temperature and pH of the water are critical factors in effective chlorine disinfection because they directly influence the effectiveness of chlorine as a disinfectant. Chlorine exists in different forms in water, primarily as hypochlorous acid (HOCl) and hypochlorite ion (OCl-), and the balance between these forms is affected by the pH of the water. At lower pH levels, more chlorine is in the form of hypochlorous acid, which is a much more effective disinfectant than hypochlorite ion.

Additionally, temperature can affect the rate of disinfection reactions. Higher temperatures typically increase the reaction rates of chlorine with pathogens, thus enhancing disinfection efficiency. Therefore, managing both the temperature and pH appropriately ensures that chlorine disinfection is optimally effective in the treatment process.