The technology presents filter media and methods of recycling metal-working liquids by removing metal fines and other contaminants using the filter media. An exemplary method includes a series of steps. These steps include filtering a contaminated metal-working liquid that has metal fines through an exemplary filter medium that is comprised of a carrier and a chemical agent. The carrier is impregnated with a chemical agent selected from the group consisting of phosphoric acid, polyphosphoric acid, phosphorous acid, phosphorous pentoxide, and mixtures or derivatives of these. Further, the exemplary method includes collecting a filtrate substantially free of ashable residue; and reusing the filtrate as a metal-working liquid.