Chemical Oxygen Demand (COD)

Last updated: January 7, 2017

What Does Chemical Oxygen Demand (COD) Mean?

Chemical oxygen demand is the amount of oxygen needed to oxidize the organic matter present in water. Chemical oxygen demand testing is used to determine the amount of oxidation that will occur and the amount of organic matter in a water sample. Chemical oxygen demand testing is also used to determine the amount of inorganic chemicals in a sample.


Corrosionpedia Explains Chemical Oxygen Demand (COD)

Chemical oxygen demand testing is typically performed using a strong oxidizing chemical. Organic matter is oxidized into carbon dioxide and water in an acidic condition. The quantity of organic matter or the demand of oxygen is calculated by determining how much oxidizing chemical was consumed during the test.

Chemical oxygen demand tests are typically performed on wastewater. The pollution level is calculated by measuring the amount of organic matter in the water. Water with too much organic material can have a negative effect on the environment in which the wastewater is discharged.

Chemical oxygen demand is similar to biochemical oxygen demand in that they are both used to calculate the oxygen demand of a water sample. The difference between the two is that chemical oxygen demand measures everything that can be oxidized, whereas biochemical oxygen demand only measures the oxygen demanded by organisms.


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