In order to recover surfactants from washing solutions which have been used to wash soiled parts, in particular to wash contaminated soil, and which contain surfactants loaded with organic pollutants, surfactants are used which have a micelle-forming temperature (cmt) in the washing solution equal to or higher than 40 °C. Washing is carried out at a processing temperature higher than cmt, and after washing the surfactants are precipitated at a temperature below cmt. In order to carry out this process without changing temperatures, an aqueous alcoholic surfactant solution whose alcohol content is lowered to precipitate the pollutant-containing surfactants is used as washing solution. Purified surfactants which may be reused are recovered by extracting the pollutants from the surfactants.