Question About the Value of BOD and COD

Any of these is possible, depending on the particular circumstances.

but I mean in general, is there relation between BOD and COD

The question is essentially meaningless in the first place, which goes along quite well with meaningless acronyms and meaningless answers....

(However, BOD = biological oxygen demand, and COD = chemical oxygen demand, either of which depletes oxygen in the water to which they are added.)

thanks for that, but i still want know if there is realtion between BOD and COD or NOT

Read this

thanks alot

BOD refers to biodegradable waste, COD to waste that is not easily biodegradable. COD may or may not be organic (e.g. ammonia). Generally speaking, BOD is higher in domestic wastes whereas COD will be higher in industrial wastes, especially wastes from the chemical industry. Note that BOD will be higher than COD in wastes from the food industry.

That's not quite right, DVader. "Both the BOD and COD tests are a measure of the relative oxygen-depletion effect of a waste contaminant." *(from the link supplied above.)

BOD is measured biologically so only includes contaminants that are suitable as food for the bacteria used in the test, whereas COD is measured using oxidising chemicals and so will include the oxygen demand from other contaminants, if any. On the face of it , it sounds like COD would be higher, but due to the vagaries of the tests this isn't true. There is not normally a correlation between them.