The biochemical oxygen demand (BOD) determination is an
empirical test in which standardized laboratory procedures are
used to determine the relative oxygen requirements of wastewaters,
effluents, and polluted waters. The test has its widest application
in measuring waste loadings to treatment plants and in
evaluating the BOD-removal efficiency of such treatment systems.
The test measures the molecular oxygen utilized during a
specified incubation period for the biochemical degradation of
organic material (carbonaceous demand) and the oxygen used to
oxidize inorganic material such as sulfides and ferrous iron. It
also may measure the amount of oxygen used to oxidize reduced
forms of nitrogen (nitrogenous demand) unless their oxidation is
prevented by an inhibitor. The seeding and dilution procedures
provide an estimate of the BOD at pH 6.5 to 7.5.