Best available techniques for PFOS substitution in the surface treatment of metals and plastics and analysis of alternative substances to PFOS when used in equipment for chromium plating and plastic etching : final report / by Wolfram Willand (IUW Integrierte Umweltberatung, Lenzkirch), Yifaat Baron, Markus Blepp (Öko-Institut e.V., Freiburg), Dr. Roland Weber, Christine Herold (POPs Environmental Consulting, Schwäbisch Gmünd) ; on behalf of the Federal Environment Agency ; editors: UBA Division III 2.2 - Sandra Leuthold

Abstract

This research project gives an overview of the baths operated in Germany for chromium plating of metals and plastics and for plastic etching. Processes in which perfluorooctane sulphonic acid (PFOS) was previously used are described. The type and quantity of the fluorine-free and fluorine-containing mist suppressants used were determined for the different types of baths: functional chromium plating (hard chromium plating), decorative chromium plating (bright chromium plating) and plastic etching. According to the data collected in this study, PFOS has been replaced by 6:2 fluorotelomer sulphonic acid (6:2 FTS) in functional chromium plating and in plastic etching. In decorative chromium plating, PFOS was completely replaced by fluorine-free mist suppressants, 6:2 FTS or by the use of chromium (III)-based processes that do not require fluorine-containing mist suppressants. The nationwide consumption of mist suppressants has been estimated on the basis of the industry data collected. The extrapolation of this data for 6:2 FTS consumption in the electroplating industry results in approx. 12 tons for the year 2017. 6:2 FTS as well as the fluorine-free mist suppressants used as an alternative have been characterised by short portfolio fiches. According to current knowledge, 6:2 FTS is toxic, bioaccumulative only in invertebrates and forms persistent degradation products. The report describes the degradation and behaviour of 6:2 FTS in the environment in detail. Using the example of two facilities in which PFOS (old bath) and 6:2 FTS were or are used, the path of the mist suppressants applied was traced from the point of use to the point of discharge into the public sewerage system or watercourse. It was then investigated how the release of these fluorinated mist suppressants can be reduced in the process itself and in wastewater treatment. The report further describes existing and developing chemical and physical alternatives to surface treatment that do not use chromium(VI) or fluorinated mist suppressants and presents possible obstacles to their use.