the invention relates to a method of purifying contaminated degreasing liquids including adding a collection polymer or polymer mixture forming two phases to the degreasing liquid ; mixing the collection polymer with the degreasing liquid ; separating the collection polymer and the degreasing liquid gravimetrically , whereby the collection polymer and the major part of the contaminants form a hydrophobic bottom phase and the degreasing agent forms a hydrophilic top phase ; removing the bottom phase ; and reusing the top phase directly or for further processing .