A polishing filter apparatus employed within a sump pump system for removing mineral oils, natural ester, and synthetic ester-based fluids from an emulsion is provided. The polishing filter apparatus is connected to a sump pump barrier via a polishing filter inlet conduit, Further conduit structures are disposed within the polishing filter apparatus, which lead into a polishing filter cartridge. The polishing filter removes excess synthetic ester-based fluids from a water/oil emulsion fluid flowing therethrough and releases a resultant filtered fluid. The polishing filter cartridge contains a filtration media with a hydrophilic composition for the capture of synthetic ester-based fluid having a surface tension dissimilar to water, and the hydrophilic composition of the media has a surface energy greater than or equal to 35 dynes per centimeter.