Biochemical Oxygen Demand (BOD) is a measurement of the amount of dissolved oxygen (DO) that is used by aerobic microorganisms when decomposing organic matter in water. Like COD, it is an important water quality parameter because it provides an index to assess the effect discharged wastewater will have on the receiving environment. The higher the BOD value, the greater the amount of organic matter for oxygen consuming bacteria, and thus higher rate of dissolved oxygen consumption. Depletion of DO causes stress on aquatic organisms, making the environment unsuitable for life. BOD is also used extensively for wastewater treatment and is a common gauge to determine the design of the water treatment facility. The most common technique used for the determination of BOD, is the 5-day incubation BOD test and azide modification method.
