Chemical Oxygen Demand (COD) is a measurement of the oxygen required to oxidize soluble and particulate organic matter in water. It is an important water quality parameter that provides an index to assess the effects of discharged wastewater on the receiving environment. Higher COD levels mean a greater amount of oxidizable organic material in the sample, which will reduce dissolved oxygen levels. Thus, it will be harmful to aquatic life. COD can be determined by various method such as closed reflux digestion, by titrimetric method.