COD-BOD ratio anomaly in Bangalore, Karnataka - Need explanation


We have a Bio-Gas Plant in Bangalore, which treats degradable Food waste & also organic Sludge from the STP. We have tested the samples of the Plant inlet & outlet.

Inlet Concentrations are, BOD - 3230.77 mg/l, COD - 10955.07 mg/l & TSS - 13325.38 mg/l
Outlet Concentrations are, BOD - 600 mg/l, COD - 150 mg/l & TSS - 432 mg/l

By seeing these we come to know that the Ratio between COD:BOD is 4. But as we have studied it should be between 1.6 to 2.

So kindly help me in this. How & what is the reason for this anomaly?

Sreesha T. G.