VERIFICATION OF THE DETERMINATION OF CHEMICAL OXYGEN DEMAND IN DISTILLERY WASTEWATER

Abstract

Introduction:
Chemical oxygen demand (COD) is a key parameter for measuring the quality of industrial wastewater, enabling the evaluation of treatment and purification systems. Therefore, it is vitally important that the analytical procedure used for its determination is reliable.
Objective:
To determine a group of parameters for the verification of COD by ultraviolet-visible spectrophotometry in distillery wastewater.
Materials and Methods:
COD was determined by UV-Vis spectrophotometry at 600 nm after digesting the samples at 150 °C for 2 hours, using potassium dichromate as the oxidizing agent. The linearity of the technique was analysed in the 100-900 mgO2/L range, and the repeatability and intermediate reproducibility parameters were evaluated.
Results and Discussion:
As a result, the COD technique was found to be linear in the concentration range used; however, it was not accurate in terms of repeatability and intermediate reproducibility.
Conclusions:
The results obtained from COD verification using the spectrophotometric method in distillery wastewater show that the technique does not meet the analysed parameters. Therefore, the authors recommend ensuring sample homogenization prior to analysing this type of wastewater.