It provides information about the readily biodegradable fraction of the organic load in water.
The test has its widest application in measuring waste loadings to treatment plants and in evaluating the BOD-removal efficiency of such treatment systems. A major disadvantage of the BOD test is the amount of time (5 days) required to obtain the results.
In many biological treatment plants, the facility effluent contains large numbers of nitrifying organisms which are developed during the treatment process. These organisms can exert an oxygen demand as they convert nitrogenous to more stable. At least part of this oxygen demand is normally measured in a five-day BOD.
The biochemical oxygen demand has three major applications:
*First, it is an indicator of the conformity of the wastewater discharge and the waste treatment procedure to the current regulations.
*Second, in wastewater treatment plants, the ratio between BOD and COD (chemical oxygen demand) indicates the biodegradable fraction of an effluent.
*Third, the ratio COD/BOD is an indicator of the size of a wastewater treatment plant required for a specific location.
Biochemical oxygen demand (BOD)
