BOD

BOD

BOD means Biochemical Oxygen Demand. BOD represents the quantity of oxygen required by bacteria and other microorganisms during the biochemical degradation and transformation of organic matter present in waste water under aerobic conditions.

BOD test is important-
1. In analysis of sewage.
2. In analysis of industrial effluents.
3. In analysis of polluted water.
4. For assessing organic pollution.
5. For containing stream pollution.

Determination of BOD

The BOD test is essentially consists of measurements of dissolved oxygen content of the sample, before and after incubation at 20 °C for 5 days. If the sample does not contain any oxygen, it supplied with oxygen and the depletion caused is calculated as the measure of BOD.


Number of gram of oxygen required
Thus BOD = --------------------------------------------------------------
Number of liters of sample

While carrying out the BOD test, microbial organism may be also be provided if necessary. The BOD is usually expressed as mg/l.