Ammoniacal nitrogen (NH₃-N) is a measure for the amount of

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

, a toxic

pollutant A pollutant or novel entity is a substance or energy introduced into the environment that has undesired effects, or adversely affects the usefulness of a resource. These can be both naturally forming (i.e. minerals or extracted compounds like o ...

often found in landfill leachate and in waste products, such as sewage, liquid

manure Manure is organic matter that is used as organic fertilizer in agriculture. Most manure consists of animal feces; other sources include compost and green manure. Manures contribute to the Soil fertility, fertility of soil by adding organic ma ...

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 Waste treatment refers to the activities required to ensure that waste has the least practicable impact on the environment. In many countries various forms of waste treatment are required by law. Solid waste treatment The treatment of solid wastes ...

and

water purification Water purification is the process of removing undesirable chemicals, biological contaminants, suspended solids, and gases from water. The goal is to produce water that is fit for specific purposes. Most water is purified and disinfected for hu ...

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 The kilogram (also kilogramme) is the unit of mass in the International System of Units (SI), having the unit symbol kg. It is a widely used measure in science, engineering and commerce worldwide, and is often simply called a kilo colloquially. ...

per liter and are used for specifying water treatment systems and facilities. The typical output of liquid

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.

Structure and Basic Chemical Properties

Ammonium and ammonia forms of nitrogen compounds

Ammonia and Ammonium

Ammonium is an

ion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

ized form of

.
The chemical structure for ammonium is NH.
The chemical structure for ammonia is NH₃. Ammonia is highly soluble in water. Ammonia reacts with water (H₂O) and forms the ionized form: :NH₃ + H₂O ↔ NH + OH⁻ The reaction is reversible. The hydroxide ion (OH⁻) plus NH forms NH₃ + H₂O. The percentage of ammonia increases with increasing

alkalinity Alkalinity (from ar, القلوي, al-qaly, lit=ashes of the saltwort) is the capacity of water to resist acidification. It should not be confused with basicity, which is an absolute measurement on the pH scale. Alkalinity is the strength ...

of dissolved ammonium in water. Ammonium ions are formed with increasing acidity of dissolved ammonia in water. Ammonia is toxic to fish and humans. The toxicity is decreased with lower alkalinity and increases with higher alkalinity as ammonium is converted to ammonia.

Ammonia and mineral forms of Nitrogen

There are 3 main forms of

nitrogen Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at se ...

: * Molecular nitrogen * Mineral nitrogen * Organic nitrogen

=Molecular nitrogen

= Molecular nitrogen is the gas form of nitrogen in the atmosphere. The chemical structure for

nitrogen gas Nitrogen is the chemical element with the symbol N and atomic number 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens. It is a common element in the universe, estimated at seventh ...

is N₂.

=Mineral nitrogen

= The mineral forms of nitrogen are: * Nitrate with the chemical structure of NO * Nitrite with the chemical structure of NO * Ammonium ions, with the chemical structure of NH Ammoniums ions are nitrified and are converted by microorganisms into nitrate. Fish and humans are more tolerant of nitrate nitrogen than they are of ammonium nitrogen. In well aerated water, most of the mineral nitrogen is in the form of nitrate. See

=Organic nitrogen

= Major organic forms of nitrogen include proteins, amino acids, DNA, and RNA.

References

{{DEFAULTSORT:Ammoniacal Nitrogen Ecological data