Are you referring to influent or effluent.
Regards
TerryF
There is much variation between plants in terms of influent COD/BOD and a lot depends on your climate , the amount of industry and domestic load , whether you have infiltration problems etc. A BNR process can be used over a wide range of COD/BOD but the influent strength will also dictate certain treatment processes and to what your effluent limits might be.
I don't know that you could really say there was any typical values but BNR processes are being used with influent CODs from perhaps as low as 150mg/l to over 1000 mg/l.
Plants treating largely domestic loads are probably in the range of 300-500mg/l COD provided there is not too much infiltration with BODs generally about 40% of the COD unless collection system detention time is really long.