Ammoniacal nitrogen (NH3-N), is a measure for the amount of ammonia, a toxic pollutant often found in landfill leachate and in waste products, such as sewage, liquid manure and other liquid organic waste products.
It can also be used as a measure of the health of water in natural bodies such as rivers or lakes, or in man made water reservoirs. The term is used widely in waste treatment and water purification systems.
Ammonia can directly poison humans and upset the equilibrium of water systems. The values of ammoniacal nitrogen in water or waste liquids are measured in milligram per liter and are used for specifying water treatment systems and facilities. The typical output of liquid manure from a dairy farm, after separation from the solids is 1600 mg NH3-N /L. Sewage treatment plants, receiving lower values, typically remove 80% and more of input ammonia and reach NH3-N values of 250 mg/L or less.
The ammonium nitrogen value is also used in the context of properly designed landfill systems, where the leachate is being pumped to the surface and treated before it enters the ground water, testing the quality of the water exiting the treatment system.
The term NH3-N removal is also commonly used in scientific publications as a short way to depict Ammonia in water, and not the measure of its quantity.