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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