Semimicro determination of COD employing microwave digestion

Abstract

A modified semimicro method is described for determining chemical oxygen demand (COD) employing microwave (MW) digestion (0.5 min exposure at 1,000 W power, and 10 min exposure at 250 W power) with a titration assessment. Composition of reaction mixture was the same as that of the usual reflux method. Determfination was performed in glass vessels of original tetrafluoromethoxil containers. Under given conditions dichromate autoreduction was low. A good agreement with the usual reflux method was obtained with selected substances (potassium hydrogen phthalate, glutamic acid, glucose, dodecyl sulphate, where COD-MW/ThOD is 98.9 - 101.5 %). With real samples (municipal sewage, mixed tanning and chemical wastewaters, and treated wastewater from biological treatment plants) the obtained results were also satisfactory (88.0 - 111.9 %)