The Chemical Oxygen Demand, identified by the acronym COD, assesses the amount of dissolved oxygen (OD) consumed in an acidic environment that leads to the degradation of organic matter, which is biodegradable or do not. It is at this point that it differs from the Biochemical Oxygen Demand (BOD), where the amount of oxygen needed to oxidize biodegradable organic matter is measured.
The resistance of substances to biological attacks led to the need to use chemical products, in which case the organic matter was oxidized by means of a chemical oxidizer. This method is faster than the BOD one, lasts 2-3 hours while the other is equivalent to five days. COD is very important in the control of industrial effluents.
In general, hot potassium bichromate is used in this method, and for water destined for public supply, potassium permanganate is used.
By Líria Alves
Graduated in Chemistry
See more!
Biochemical oxygen demand
Source: Brazil School - https://brasilescola.uol.com.br/quimica/demanda-quimica-oxigenio.htm