ABSTRACT
This chapter describes the various Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), and Total Oxygen Demand (TOD) analyzers. The main distinction between the various designs is in the speed at which the measurement is obtained and in the correlation of the resulting readings with manomeric BOD tests. In the usual course of the BOD test, the oxygen consumption rises steeply at the beginning of the test owing to attack on carbohydrate materials. Many regulatory agencies recognize as the basis for pollution control only the BOD or COD measurements of pollution load. The term COD usually refers to the laboratory dichromate oxidation procedure, although it has also been applied to other procedures that differ greatly from the dichromate method but which do involve chemical reaction. The TOD method is based on the quantitative measurement of the amount of oxygen used to burn the impurities in a liquid sample.
