Total degradation or environmental experiment?

Owing to the alarming state of health of Salmonidae in many Swiss rivers, e ffluents of sewage treatment plants were studies. Water-polluting substance s were enriched by solid-phase extraction (reversed-phase), isolated and fr actionated by thin-layer chromatography using automatic multiple developmen t (AMB). by subsequent biological detection with Bacillus subtilis, Aspergi llus niger, and Chlorella vulgaris the position of the toxic substances wer e verified. The spots were scratched out and eluted, then the toxic substan ces were analysed by infrared spectroscopy and characterized in comparison with reference spectra. The infrared (IR) spectra of the effluents of the s ewage treatment plant resembled strongly those of adducts of ethylene oxide and hydrogenated castor oil, amphoteric surfactants, and fatty alcohol alk oxylates. To verify the indications of the IR spectra the respective raw ma terials were subjected to biodegradation in an extended OECD-test 302B and a laboratory trickling filter test. Two of nine substances proves to be tot ally biodegradable. The refractory intermediates of the seven incompletely degradable substances were obtained through trickling filters, enriched by solid-phase extraction and analysed by infrared spectroscopy. After thin-la yer chromatography and subsequent biological detection by Bacillus subtilis , only the trickling filter effluents of the amphoteric surfactants, e.g. c ocoamphodiacetate and cocoamphodipropioate showed toxic effects. These subs tances are often used in shower gels and shampoos. To our knowledge, data o n the ecotoxic or biological effects of their refractory compounds are not available. Considering the large amounts of these intermediates in surface water, further studies are necessary. The amounts are considerably larger t han, for example, the amounts of drugs or pesticides (although this is not to question at all the problematic nature of drugs and pesticides). From th e point of view of preventive environment protection, substances that are u sed in large amounts should be completely biodegradable in sewage treatment plants under aerobic conditions.