Biological Oxygen Demand - Effect on Water Bodies
Addition of biodegradable matter exerts demand on oxygen of the water body. The demand of oxygen is directly related to increasing loads of organic matter and is expressed as biological oxygen demand (BOD).
It is the measure of dissolved oxygen required by aerobic decomposers to break down organic matter present in a given volume of water over 5-day incubation period at 20°C. It is expressed in parts per million or mg of oxygen per litre. A high value of BOD indicates the high activity of aerobic decomposers which in turn means more organic wastes or sewage in water.