Biological Oxygen Demand
Biochemical Oxygen Demand (BOD) is used in water monitoring provides as an estimate of the oxygen uptake by microorganisms during the breakdown of organic material present in a water sample. This is normally quoted in mg/L. The value for BOD will always be lower than that of COD.
It is usually measured in the laboratory under controlled conditions over a 5-day period (e.g. BOD5) and oxygen depletion compared to control. The reason for the five days is to give the Biological substance the opportunity to grow to a detectable level.
Bod in waste water and sewage treatment is an important parameter aswell in lake.