Biochemical Oxygen Demand (BOD) refers to the amount of oxygen that would be consumed if all the organics in one liter of water were oxidized by bacteria and protozoa (ReVelle and ReVelle, 1988). The BOD value is most commonly expressed in milligrams of oxygen consumed per liter of sample during 5 days of incubation at 20°C and is often used as a robust surrogate of the degree of organic pollution of water. Applications: •Study of Biodegradability & Toxicity of organic compound. •Study of reaction kinetics biodegradation of specific waste and its removal from the environment. •Study of specific bacterial strength and enzymatic systems responsible for biodegradation of specific compound. •Study of oxygen up take rate of biomass and their viable concentration present in activated sludge systems. •Monitoring of the performance of effluent treatment systems with greater speed and reliability.