Determination of chemical oxygen demand of wastewaters without the use of mercury salts

Abstract

The use of silver nitrate solution to suppress chloride interference in the chemical oxygen demand test is described. Chlorides in wastewater are precipitated as silver chloride and in this form are only slightly oxidised. The proposed procedure obviates the use of toxic mercury(II) sulphate and is similar to the standard procedure in accuracy and reproducibility of results over a wide range of chloride concentrations.