CHEMICAL OXYGEN DEMAND

NAME:- PRANAV KHANNAROLL NO.:-11204002

WHAT IS COD?

• The chemical oxygen demand (COD) of a waste is measured in terms of the amount of potassium dichromate (K2Cr2O7) reduced by the sample during 2 hr of reflux in a medium of boiling, 50% H2SO4 and in the presence of a Ag2SO4 catalyst

SIGNIFICANCE

1. Measures pollution potential of organic matter organic matter + oxidant CO2 + ⇒H2O

2. Decomposable organic matter results in consumption of DO in the receiving streams

3. Does not differentiate between biologically degradable & non degradable organic matter

COD EQUATION

How would you test for COD?

You need to monitor either the disappearance of dichromate or the appearance of Cr3+

APPARATUSE USED:-

CHEMICALS USED:-

COD DIGESTER

USES OF COD:-

• GIVES A FASTER RESULT THEN BOD• 2 HOURS V/S 5 DAYS

PRECAUTIONS

CALCULATION TABLE

Formula of cod

• COD as mg/l of oxygen consumed =(A-B) x Normality of FAS x 8000 / ml. of sample taken

• Where• A = ml. of FAS used for titration of blank• B = ml. of FAS used for titration of sample