Wastewater treatment FATTY ALCOHOL SOURCES PROJECT

Fatty alcohol sources

Summary

Within this project, compound specific stable isotope mass spectrometry (13C & 2H) was used to distinguish between natural (plant-based) and synthetic (petroleum-based) alcohols derived from surfactants, as well as from other sources of fatty alcohols (e.g. faecal material, soils, plant material) entering a wastewater treatment plant [WWTP].

Results from a North Wales catchment show that WWTP influent consists mainly of fatty alcohols derived from faecal matter and detergents (3:1). However, WWTP effluent and marine sediments have subsequently different and discrete ’signatures’ as compared to that of the influent, suggesting ‘in-situ’ bacterial synthesis of fatty alcohols both during WWTP treatment, and subsequently by algae during marine production.

Background

Fatty alcohols with long and medium carbon chains can be detected in various environmental compartments as well as sewers and WWTPs. Sources for these alcohols in WWTPs can be either surfactants discharged via waste water or active sludge (i.e. natural biomass) in the WWTP. Previous bio-degradation and monitoring studies with alcohol ethoxylates carried out by ERASM (see CSARA project) have indicated that only a small fraction of alcohol in WWTP effluents originates from alcohol ethoxylates entering the WWTP. Further information was needed on the contribution of natural (non-anthropogenic) free alcohols that may be derived from bound sources or fatty alcohol precursors both in WWTPs and in the environment as a whole.

Outcome

The ERASM research project on alcohol sourcing used stable isotope mass spectrometry (13C & 2H) to distinguish between natural (plant-based) and synthetic (petroleum-based) fatty alcohols derived from surfactants, as well as from other sources of fatty alcohols (e.g. faecal material, soils, plant material) entering a waste water treatment plant (WWTP). Using this methodology it has been shown that the fatty alcohols discharged in the WWTP effluent were not the same as those that entered as influent. This suggests that quantitative biodegradation of the alcohol-based surfactants and bacterial “de novo” synthesis of non-anthropogenic alcohols during the treatment process. Furthermore, fatty alcohols in marine sediments were not the same as those discharged into the estuary as effluent. Such findings are extremely important when undertaking any risk assessment of fatty alcohols in the environment.