COD-1C Chemical Oxygen Demand (COD or CODcr) refers to the amount of oxidant consumed caused by oxidation of reducing substances in water under specific condition, recorded as the amount of oxygen consumption counted by “mg/L”. It indicates the water pollution degree by these reducing substances, including organic matter, nitrite, ferrous salt and sulfide, etc. There is a small amount of inorganic reducing substances but a large amount of organic matters. So, COD can be used as a comprehensive index of relative content of organic matters.
