Correction of hydrogen peroxide interference on standard chemical oxygen demand test

The chemical oxygen demand test, which is widely used as an indicator to identify the characteristics of wastewater, could be disturbed by the inorganic substances such as nitrite, chloride, hydrogen peroxide, etc. For hydrogen peroxide differently to the other inorganic substances, the method of overcoming its interference is not mentioned in Standard Methods [APHA (1995) Standard Methods for the Examination of Water and Wastewater, 19th edition. Washington, D.C.] and is also reported insufficiently in the literature until now. This work has been carried out to correct quantitatively the effect of the concentration of hydrogen peroxide on the chemical oxygen demand. The ratio of the chemical oxygen demand to the concentration of hydrogen peroxide is affected by its concentration and is increased up to 0.4706, which is the theoretical value, with decreasing its concentration. The correlation equation, which can be applied to the hydrogen peroxide concentration range of 0–2000 mg/l, is proposed to correct the effect of the concentration of hydrogen peroxide on the chemical oxygen demand. It is also shown that this correlation equation can be applied to the samples containing hydrogen peroxide and organic substances.