industrial waste water treatment

We have a situation where the feed water is having 300 ppm of BOD, 4700 ppm of COD, TSS is less than 150 ppm and TDS 3000 ppm. This water to be treated up to Less than 10 ppm of BOD , 50 ppm of COD and Less than 50 ppm of TSS, TDS less than 100.

We have designed the plant with following scheme

Pre screening - oil water seperator - coagulation - flocculation - DAF system - Collection tank - MBBR treatment - Collection tank - DMD - Ultrafiltration - RO treatment.

At DAF outlet we are getting 150 ppm of BOD and 800 ppm of COD. As such this water is not suitable for MBBR treatment since biology BOD load is very low. So not much COD reduction is happening in MBBR treatment. Also as per UF membrane manufacturer recommendation we need to reduce the COD to the level of 150 ppm before allowing water to pass through UF.

We tried using secondary DAF by passing primary outlet and found only 100 ppm reduction in COD ( It is coming down from 800 ppm to 700 ppm only. Whereas we require 150 ppm to pass in to UF)

We need to solution to reduce DAF outlet COD reduction from 800 ppm to 150 ppm. Can any one suggest suitable solution please?