COD(Chemical Oxygen Demand)
COD is determined by the dichromate reflux method.The sample is refluxed with known amounts of potassium dichromate and sulphuric acid,After oxidation,the excess dichromate is measured by titration with Ferrous Ammonium Sulphate /spectophotometry.The amount of oxidatizable organic matter is propotional to the potassium dichromate consumed.Enough potassium dichromate is added so that there will be excess at the end of oxidation.COD can be determined by using micro digestion set-up,potassium dichromate in 50% sulphuric acid solution with silver ions for complete oxidation and mercuric sulphate for elimination of inorganic interference.After the oxidation is over,the excess amount of dichromate present is measured so that the amount
