The effect of secondary treatment and eco-region on the environmental fate of fatty alcohol based surfactants.

Samples of influent, effluent and sediments of the receiving waters of eight WWTPs were collected in each of three eco-regions of the USA, a total of 24 facilities. Six different treatment technologies were included to determine the fate of anthropogenic fatty alcohols. The lipids were analysed by compound-specific stable isotope ratio mass spectrometry. There were significant differences in the profiles of the influent among eco-regions, due to differences in the products used within the catchment, the diets of the inhabitants, or in-pipe processes. The sediments of all the receiving waters had similar fatty alcohol profiles, with terrestrial plant matter dominating and secondary contributions from algal and bacterial synthesis. Any contributions from the WWTP liquid effluents were small (<1%) and not from the original fatty alcohols suite in the influent. These compounds might have the same chain lengths, but they have different stable isotopic signatures. The type of secondary treatment did not affect the removal of fatty alcohols and the sediments of the receiving waters were dominated by terrestrial plant inputs; the eco-region may affect the profile of the influents but not the stable isotopes. The ecological risk from the use of these particular chemicals, which are disposed of down the drain, is minimal.