03/12/2020
NITRATE ( WATER TREATMENT PARAMETER).
Nitrate is one of the most common groundwater contaminants. It is regulated in drinking water primarily because excess levels can cause methemoglobinemia, or "blue baby" disease.
Nitrate in groundwater originates primarily from fertilizers, septic systems, and manure storage or spreading operations. Fertilizer nitrogen that is not taken up by plants, is volatilized, or carried away by surface runoff leaches to the groundwater in the form of nitrate. This can also elevate the concentration in groundwater above the levels acceptable for drinking water quality.
WHAT IS NITRATE?
Nitrate is an inorganic compound that occurs under a variety of conditions in the environment, both naturally and synthetically. Nitrate is composed of one atom of nitrogen (N) and three atoms of oxygen (O); the chemical symbol for nitrate is NO3. Nitrite (NO2) can be formed from nitrate by a chemical process called reduction. Nitrate does not normally cause health problems unless it is reduced to nitrite.
Nitrate in drinking water is measured either in terms of the amount of nitrogen present or in terms of both nitrogen and oxygen. The federal standard for nitrate in drinking water is 10 milligrams per liter (10 mg/l) nitrate-N, or 45 mg/l nitrate-NO3. when the oxygen is measured as well as the nitrogen. Unless otherwise specified, nitrate levels usually refer only to the amount of nitrogen present, and the usual standard, therefore, is 10 mg/l.
UNDERSTANDING LABORATORY REPORTS ON NITRATE.
Laboratory test results report nitrate concentrations in water in one of two ways: either as nitrate-nitrogen (NO3-N) or as total nitrate (NO3). Most laboratories report nitrate as nitrate-nitrogen (NO3-N), which is the amount of nitrogen in the nitrate form. Be sure to check your test report to determine which quantity—NO3-N or NO3—is reported. Laboratories report nitrate concentration in water as milligrams per liter (mg/L) or as parts per million (ppm), which are equivalent for drinking water (1 mg/L = 1 ppm).
Depending on which reporting system is being used, the acceptable safety levels of nitrate will be different: 10 mg/L nitrate-nitrogen (NO3-N) = 44.3 mg/L nitrate (NO3)
Multipliers to Convert Between Nitrate (NO3) and Nitrate-Nitrogen (NO3-N)
To Covert To Multiply by
Nitrate (NO3) Nitrate- Nitrogen (NO3 - N) 0.22
Nitrate- Nitrogen (NO3 - N) Nitrate (NO3) 44.3
The conversion factor is used because nitrogen makes up 22.5% of the total weight of the nitrate molecule.
Nitrate is a very soluble substance, easily dissolved in water and extremely hard to remove. Treatment for nitrate is, therefore, extremely complicated, and expensive. The three methods of reducing or removing nitrate are:
• demineralization by distillation or reverse osmosis
• ion exchange
• blending
