The initial COD of my sample sewage water is around 170-200 ppm only but the COD of my supposedly treated water goes up to 300 ppm? I've used iron plate electrodes in a bipolar configuration and a constant current supply of 3.3 A.
During longer electrocoagulation treatment in sample is H2O2 generated which can influence on COD measurement. In such samples, the correction on H2O2 for COD measurement has to be done to get real COD values.
During longer electrocoagulation treatment in sample is H2O2 generated which can influence on COD measurement. In such samples, the correction on H2O2 for COD measurement has to be done to get real COD values.
If you are using an iron electrode you probably have residual ferrous ions in solution . That iron will show up as COD on the test.
To be absolutely sure if your COD test you should use a standard addition method.
That is add a known quantity of COD to your sample from before and and after electrocoagulation and retest. If you do not get the expected results you should question the test method and identify the interference.
Hi guys! I've tried to remove the residual ferrous ions first and tried the COD analysis again. It now resulted to the expected lower COD value. Thank you all for your answers.