Hi Gary, A DAF removes FOG ...

Published April 30, 2015 15:41 by Bruno Peeters, managing director at Model Engineering

Hi Gary, A DAF removes FOG (fat, oil, grease) and particulate COD including colloids after coagulation-flocculation. Hence if turbidity at the DAF outlet = MBR inlet has increased along with the COD, then the DAF needs to optimized as recommended by Ciaran and Stephanus. However if the turbidity did not increase with the COD, then the additional COD is soluble and apparently readily biodegradable. In that case (electro-)chemical pretreatment would probably not be very efficient. An efficient and low cost alternative would be to add biosorption upstream of the DAF (in existing coagulation tank) using some waste activated sludge (WAS) from the MBR after regeneration. The WAS with adsorbed COD will be removed in the DAF. We remove up to 80% COD in 15 minutes via biosorption on regenerated activated sludge.