What is breakpoint chlorination?

Breakpoint chlorination refers to the point at which the amount of chlorine added to water is sufficient to react with all the organic and inorganic nitrogenous compounds present, leading to the complete destruction of chloramines and the formation of free chlorine residual. This process is crucial in water treatment because, before reaching this breakpoint, added chlorine may react with ammonia and other compounds to form chloramines, which do not provide desirable disinfection.

When sufficient chlorine is added, it effectively eliminates these undesired compounds, leading to a free chlorine residual that can provide effective disinfection. In this context, increasing the chlorine dosage to the point of breakpoint is necessary to achieve that desired effect, making the correct answer pertinent to understanding the processes involved in water treatment and disinfection.