LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Remarks: This study demonstrates that significant biodegradation of LAS occurs prior
to reaching wastewater treatment plants. Additional removal (up to >95%)
occurs in the plants themselves.
Reference: Moreno, A., de Ferrer, J. and Berna, J.L. 1990. Biodegradability of LAS in a
sewer system. Tenside Surf. Det. 27:312-315.
Reliability: 2 Valid with restrictions
(b)
Results: The average removal rate for LAS in activated sludge treatment was > 99%.
A lower and more variable rate was observed in trickling filter treatment
plants with an average removal of 82% for LAS.
Remarks: Samples were collected from six trickling filter and four activated sludge
treatment plants located in the midwestern United States.
Reference: McAvoy, D.C., Dyer, S.D., Fendinger, N.J., Eckhoff, W.S., Lawrence, D.L.
and Begley, W.M. 1998. Removal of alcohol ethoxylates, alkyl ethoxylate
sulfates, and linear alkylbenzene sulfonates in wastewater treatment.
Environ. Toxicol. Chem. 17:1705-1711.
Reliability: 2 Valid with restrictions
(c)
Results: The model predicted average removal of LAS from wastewater treatment
plants is 99.2%. Predicted 90 th -percentile concentrations at 1,000 m
downstream from the sewage outfall, based on actual measured raw sewage
concentrations and actual measured effluent calculations, ranged from 3.7 to
9.2 µg/L for different predicted instream removal rates.
Method: Modeling was conducted to predict the 90 th -percentile environmental
concentration (PEC) of LAS and other detergent substances in aquatic
environments in the Netherlands. Inputs included emissions data, prediction
of raw sewage concentration and initial material characterization. Model
predictions included the removal of LAS in wastewater treatment plants,
concentrations in surface waters, and prediction of the 90 th -percentile
concentrations.
Remarks: The authors emphasize that to provide a fate assessment adequate for
regulatory purposes, a need clearly exists for a fundamental interplay
between monitoring, laboratory data, and these predictive models. This study
is part of an extensive monitoring program executed jointly by the Dutch
Soap Association (NVZ) and the Dutch Ministry of Housing, Spatial
Planning and the Environment (VROM). Monitoring data from this program
can be found in Matthijs et al. 1999.
Reference: Feijtel, T.C.J., Struijs, J., and Matthijs, E. 1999b. Exposure modeling of
detergent surfactants – Prediction of 90 th -percentile concentrations in the
Netherlands. Environmental Toxicology and Chemistry 18:2645-2652.
Reliability: 2 Valid with restrictions
(d)
Results: The average concentration of LAS in the treated sewage of the sum
wastewater treatment plants was 39 µg/L. The average total removal of LAS
was 99.2%.
Method: Twenty four hour flow proportional samples of raw, settled, and treated
sewage were collected by automatic samples during three consecutive days at
seven sewage treatment plants in the Netherlands. All samples were
collected between April and July 1994 and analyzed for traditional sewage
treatment plant water quality parameters. Samples for the analysis of LAS
and other surfactants were taken every 15 minutes (hourly composites) using
a time proportional automatic sampler. The LAS in these samples was
analyzed using an HPLC method with fluorescence detection.
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