LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
Remarks: This paper indicates qualitatively that LAS undergoes anaerobic degradation,
but no quantitative results are presented.
Reference: Angelidaki, I., Mogenen, A.S. and Ahring, B.K. 2000b. Degradation of
organic contaminants found in organic waste. Biodegradation. 11:377-383.
Reliability: 2 Valid with restrictions
(t)
Type: aerobic [ ]; anaerobic [X]
Inoculum: Activated sludge
Concentration: 100 mg/L
Medium: water [ ]; water-sediment [ ]; soil [ ]; sewage treatment [X]
Degradation: Transformation of C12 LAS occurred under anaerobic conditions. The degree
of transformation varied between 14 to 25%.
Methods: Two lab-scale continuous stirred tank reactors (CSTR) were set up with
automatic, semi-continuous feeding and were run under mesophilic
conditions (37 o C) with a hydraulic retention time of 15 days. The reactors
were started with anaerobic stabilizer sewage sludge and operated for several
months before the experiment started. The feed was diluted sludge at a total
solids concentration of 20 g TS/L. The sludge was spiked with C12 LAS at a
concentration of 100 mg/L and the two reactors were operated similarly for
36 days. After this period, the LAS concentration in reactor 1 was increased
to 268 mg/L, while for reactor 2 the influent TS was decreased to 11.4 g
TS/L, and both reactors continued to operate for a total of 90 days (including
the original 36 days).
GLP: Yes [ ] No [ ] ? [X]
Test Substance: C12 LAS (pure homologue)
Remarks: A clear correlation was shown between degradation of organic matter
contained in the sludge and anaerobic degradation of LAS, giving an
increase in transformation with the higher the reduction of organic matter.
Transformation was limited by bioavailability due to sorption of LAS (i.e.,
only the bioavailable fraction of LAS is transformed by anaerobic digestion).
When the reduction degree of the organic matter increased from 22% to
28%, the transformation degree of C12 LAS increased from 14% to 20%.
Decreasing the total solids concentration of the influent sludge or increasing
the spiked concentration of C12 LAS did not significantly alter the degree of
LAS transformation.
Reference: Angelidaki, I., Haagensen, F. and Ahring, B.K. 2000a. Anaerobic
transformation of LAS in continuous stirred tank reactors treating sewage
sludge. 5 th World CESIO Congress. V.2:1551-1557, Firenze, Italy.
Reliability: 2 Valid with restrictions
(u)
Type: aerobic [ X]; anaerobic [ ]
Medium coastal sea water
Concentration: 5 mg/L related to test substance
Results: LAS primary degradation half-lives ranged from 3.4 to 13.8 days, with 4-9
days being the most frequent values.
Method: Coastal sea water from the Mediterranean Sea was collected from three areas
in Spain (Barceloneta, Ebro delta, and Sant Feliu de Guixols, Girona).
Samples of 1.5- L were placed in 3-L flasks and incubated in the dark at 20 o C
with orbital shaking (100 rpm) for 30 days. Viable bacteria were determined
by plate counts on marine agar media, while total bacteria were determined
by flow cytometry after SYTO-13 staining. LAS degradation was monitored
by HPLC. A reference substance was not used. LAS quantification was
based on an external standard.
GLP: Yes [ ] No [ ] ? [X]
UNEP PUBLICATIONS 165