How much chlorine (CL2) is needed to reach breakpoint for every 1 mg/L of ammonia nitrogen (NH3-N) present?

The amount of chlorine necessary to reach the breakpoint for ammonia nitrogen is based on the stoichiometric relationship between chlorine and ammonia. At the breakpoint chlorination stage, chlorine reacts with ammonia to form chloramines before any residual chlorine is available for disinfection. The general rule of thumb is that it takes about 10 mg/L of chlorine to effectively treat each 1 mg/L of ammonia nitrogen present.

This ratio reflects the need for a sufficient quantity of chlorine to not only react with the ammonia in the water but also to influence the formation of chloramines before reaching a point where free chlorine can effectively disinfect the water. Understanding this relationship is critical in wastewater treatment processes to ensure optimal chlorine dosage, preventing any excess or insufficient chlorination that could lead to subpar treatment or unnecessary chlorine usage.