The chemical oxygen demand (COD) determines the amount of oxygen required for chemical oxidation of organic matter using a strong chemical oxidant, such as, potassium dichromate under reflux conditions.
It is a quick, inexpensive means to determine organics in water. COD samples are prepared with a closed-reflux digestion followed by analysis. The quantity of oxidant consumed is expressed in terms of its oxygen equivalence.
COD often is used as a measurement of pollutants in wastewater and natural waters. Other related analytical values are biochemical oxygen demand (BOD), total organic carbon (TOC), and total oxygen demand (TOD).
The test has its widest application in measuring waste loadings of treatment plants and in evaluating the efficiency of treatment processes. Other applications include testing lake and stream water samples for organic pollution.
COD provides rough idea of Biochemical oxygen demand (BOD) which can be used to determine sample volume for BOD estimation.
Chemical oxygen demand
