A method of producing a final product from a wastewater dissolved air flotation (DAF) sludge which includes the following dewatering step: 5 - dewatering of the sludge, an aged sludge or a pre-processed sludge to produce a sludge filter cake and a filtrate; such that the pre-processed is sludge, or aged sludge, that has undergone additional processing steps prior to dewatering and aged sludge is sludge that has been stored for a period of time, wherein the dewatering step is a mechanical dewatering step 10 carried out at a maximum of 30 DEG C which results in a sludge filter cake that does not flow under its own mass.