Biochemical Oxygen Demand and Other Organic Pollution Measures

Abstract

Biochemical oxygen demand (BOD) is the most important and widely used environmental index for monitoring organic pollutants in wastewater. The current international standard method is the five‐day BOD assay (BOD 5 ). The test measures the amount of dissolved oxygen required for the microbial oxidation of carbonaceous organic material under specified conditions. The test has its widest application in measuring waste loadings to treatment plants and in evaluating the BOD‐removal efficiency of such treatment systems. Practical difficulties exist associated with the BOD 5 test, including sensitivity to temperature and oxygen concentration, impact of toxins, lack of stoichiometric validation, and the need to dilute samples. The test is labor intensive with variable results, but the major drawback continues to be the five‐day measurement time. For all its shortcomings and the availability of a number of related measurement techniques, the BOD 5 assay remains the preferred test for reporting the oxygen requirements of wastewaters, effluents, and polluted waters, in part, because of its international regulatory status, but also because it uniquely simulates the microbial decomposition of organic wastes in the environment, thereby approximating the response of natural ecosystems.