It appears to be the COD ...
Published by Ramadurai Rajaraman, Sairam Consultancy Services - owner
It appears to be the COD reduction carry over is from the oil and water separator upstream. Please let me know the complete influent (At the inlet of pre-screening) including the free O&G and emulsified O&G. Also let me know the type of Oil water separator installed. My email address is scs.rajaraman@gmail.com