What is meant by the term "breakpoint" in chlorination?

The term "breakpoint" in chlorination refers to the specific point at which the amount of chlorine added to water is sufficient to completely react with all the chlorine-demanding substances present, such as organic materials, ammonia, and other oxidizable compounds. At this juncture, the chlorine dose meets the demand of those substances, and any additional chlorine added will begin to provide a free chlorine residual, which is important for disinfection purposes.

Understanding this concept is critical in water treatment processes because reaching the breakpoint ensures that the water is not only treated effectively, but also that the residual chlorine can continue to provide disinfection. Chlorine demand can vary based on the type and concentration of contaminants in the water, which is why determining the breakpoint is essential for operators aiming to achieve optimal water quality.

Other choices don't accurately capture the technical meaning of "breakpoint" in the context of chlorination. The idea of making water drinkable is more about overall water treatment processes than specifically relating to chlorine demand. Maximum chlorine levels refer to regulatory standards rather than the operational concept of breakpoint. Complete sterilization involves removing or killing all microorganisms, which goes further than simply meeting chlorine demand. Thus, the best understanding of "breakpoint" focuses on the relationship between chlorine dosage and