Do you know what is COD, BOD, ammonia nitrogen, total nitrogen?

1. COD (chemical oxygen demand)

COD: chemical oxygen demand, (COD or CODcr) refers to the amount of oxidant consumed when reducing substances in water are oxidized and decomposed under the action of an external strong oxidant under certain strict conditions, expressed in mg/L .

Chemical oxygen demand reflects the degree of water pollution by reducing substances, including organic matter, nitrite, ferrous salt, sulfide, etc., but the amount of inorganic reducing substances in general water and wastewater is relatively small, and is Organic matter pollution is very common, therefore, COD can be used as a comprehensive indicator of the relative content of organic matter.

2. BOD (Biochemical Oxygen Demand)

BOD: Biochemical Oxygen Demand, which is an important indicator that indirectly indicates the degree of water pollution by organic matter by the amount of dissolved oxygen consumed by microbial metabolism.

Its definition is: under aerobic conditions, the amount of free oxygen consumed by aerobic microorganisms oxidatively decomposes organic matter per unit volume of water, expressed in mg/L).

3. Ammonia nitrogen

Ammonia nitrogen: refers to nitrogen in water in the form of free ammonia (NH3) and ammonium ions (NH4).

Ammonia nitrogen is a nutrient in water, which can lead to water eutrophication. It is the main oxygen-consuming pollutant in water and is toxic to fish and some aquatic organisms.

4. Total nitrogen

Total nitrogen: The total amount of various forms of inorganic and organic nitrogen in water.

Including inorganic nitrogen such as NO3-, NO2- and NH4+ and organic nitrogen such as protein, amino acid and organic amine, calculated in milligrams of nitrogen per liter of water. Often used to indicate the degree to which water bodies are polluted by nutrients.