What is the most appropriate use of chloramines in water treatment?

Chloramines serve a vital role in water treatment, particularly as secondary disinfectants. They are formed when ammonia is added to chlorine. Their use as secondary disinfectants helps to maintain a residual level of disinfection throughout the distribution system, which is particularly beneficial in long pipelines where pathogens may grow.

One of the significant advantages of using chloramines is their ability to reduce the formation of disinfection by-products (DBPs), such as trihalomethanes (THMs), which are often a concern with chlorine. By using chloramines, water treatment facilities can minimize the amount of these potentially harmful by-products, thus contributing to safer drinking water.

While chloramines can have some disinfectant properties, they are typically not used as primary disinfectants due to their slower reaction rates compared to chlorine. This means that while they can effectively help with ongoing disinfection in a distribution system, they are not as effective in the initial treatment or disinfection phase.

Thus, the most appropriate application of chloramines in water treatment is as secondary disinfectants and as a means to reduce the formation of disinfectant by-products, aligning perfectly with the correct answer.