Biological Oxygen Demand

A measure of the amount of oxygen used by microorganisms to degrade organic matter over time (expressed in mg/L and normally measured over five days as BOD5). It is an indirect measure of the amount of biodegradable organic material present in water or wastewater: the more the organic content, the more oxygen is required to degrade it (high BOD). A high BOD can be caused by high levels of organic pollution or high nitrate levels, which trigger high plant growth.