If it is true that you have ...

Published by

If it is true that you have your biological system optimized, then we can say that most of the 250 mg/l COD would consist of biologically inert material.

In that case to lower the COD to reasonable levels for RO feed would require either adsorption or (chemical) oxidation.

I suggest you explore using powdered activated carbon (PAC) dosed in the aeration tanks. There are systems out there that can be installed along with PAC regeneration to reduce the PAC usage. Otherwise the PAC will be removed together with the WAS.