Dear Oscar, Thank you for ...
Published by Bruno Peeters, managing director at Model Engineering
Dear Oscar,
Thank you for your clarifications. I do agree that a DAF (with some flocculation if/as needed) is required to remove the FOG (fat oil grease) after screening, FOG trap and full equalisation.
However coagulation-flocculation (consuming most chemicals and producing most chemical waste sludge) would not be required for biological treatment after a basic DAF unless an UASB is used and the TSS/COD ratio in the UASB feed would be higher than 0.2 at 35 - 38 °C. Only in that case coagulation-flocculation upstream of the DAF would be needed as to lower the TSS/COD ratio.
As indicated by Don, coagulation would be most efficient with minimal chemicals at low pH. Of course this would also require a pH correction after the DAF. The use of hydrogen peroxide (resulting in high ORP) as suggested by Sean is not recommended upstream of an UASB which operates at very low ORP.