Biochemical (Biological) Oxygen Demand (BOD)

The characteristic quantity used to express the quality of the water resource or the pollution in the water (or the Sewage) in the form of biologically degradable substances. The determination of the Biological Oxygen Demand is done by establishing the quantity of oxygen required by the micro-organisms which must be added in order to bring about the Decomposition of the Organic Compounds contained in the water (at 20 °C) within a specific period (e.g. within five days = BOD 5).