What is the term for the amount of chlorine required to oxidize ammonia in water?

The correct term for the amount of chlorine required to oxidize ammonia in water is break-point chlorination. This process is essential in water treatment because ammonia can react with chlorine, forming chloramines, which are less effective as disinfectants.

Break-point chlorination refers specifically to the point at which the chlorine added to the water exceeds the amount required to react with all the ammonia present. Once this break-point is reached, free chlorine becomes available for disinfection because it has effectively oxidized the ammonia and achieved a breakpoint in the chlorination process. This step is crucial for ensuring that the water is disinfected efficiently and effectively.

The other terms mentioned refer to various aspects of chlorination but do not define the process of oxidizing ammonia specifically. For example, free chlorination typically refers to the use of chlorine to disinfect without the formation of chloramines. Total chlorination encompasses all forms of chlorine present, while combined chlorination describes the situation where chlorine is reacting with ammonia to form chloramines, which is not the same as oxidizing the ammonia completely.