LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
GLP: Yes [ ] No [X] ? [ ]
Test Substance: C10 to C13 homologues of LAS with varying phenyl positions
Remarks: The results show that longer chain homologues are removed faster than the
shorter chain homologues, indicating that primary biodegradation increases
as the chain length increases. In addition, the greater the distance between
the sulfonic group and the more distant terminal methyl group on the alkyl
chain the faster the degradation (i.e., phenyl position 2 degrades faster than
phenyl position 5 for the same homologue). For example, percent removal
was 52, 68, 88 and 92% for the C10 LAS with phenyl positions 5, 4, 3, and 2,
respectively.
Reference: 1) Bock, K.J. and Wickbold, R. 1966. Auswirkungen der Umstellung auf
leicht abbaubare Waschrohstoffe in einer großtechnischen Kläranlage und im
Vorfluter. Vom Wasser 33:242-253.
2) Wickbold, R. 1964. Zwischenprodukte beim Abbau eines geradkettigen
Alkylbenzolsulfonates. Vortrage IV, Inern. Kongr. F. grenzflachenaktive
Stoffe, Brussel. (not available for review)
Reliability: 2 Valid with restrictions
(b)
Type: aerobic [X]; anaerobic [ ]
Inoculum: adapted [X]; non-adapted [X]; activated sludge [X]
Concentration of the chemical: 10 mg/L related to COD [ ]; DOC [X] test substance
Medium: water [ ]; water-sediment [X]; soil [ ]; sewage treatment [ ]
Degradation: 69.6% after 28 days (acclimated inoculum)
66.7% after 28 days (non-acclimated inoculum)
Results: readily biodeg. [ ]; inherently biodeg. [ ]; under test condition no
biodegradation observed [ ], other [X]
Kinetics:
% Biodegradation % Biodegradation
Days
(Acclimated) (non-Acclimated)
5 14.3 9.2
8 32.4 24.5
12 49.5 43.6
19 63.9 60.8
28 69.6 66.7
Method: OECD 301 B, modified Sturm test, also reported as method C 5 in the Italian
D.M. 109. The reference standard sodium benzoate was used at the same
concentration of the tested surfactants (about 10 mg/L). The testing period
was 28 days and during this time the testing solutions were kept in dark glass
vessels. A supernatant solution from a sludge, which was aerated and left to
settle, was used as an inoculum for each biodegradation test at an amount
equal to 1% of the solution. Both the STP sludges and the laboratory
assimilated sludges were analysed for the dry matter contents. Tests were
conducted using acclimated or non-acclimated inocula to determine whether
this affected ultimate biodegradation. Acclimation was achieved by running
the laboratory activated sludge plant for seven days before testing with a
synthetic influent containing LAS at a concentration of abourt 10 mg/L.
Tests were conducted on LAS and three other surfactants.
GLP: Yes [X] No [ ] ? [ ]
Test substance: C10-13 LAS; average alkyl chain length = C11.6
Remarks: LAS was biodegradable using both acclimated and non-acclimated inocula.
Acclimated inocula did not significantly improve the total biodegradation,
but did accelerate the attainment of the degradation plateau. The 10-day
time-window criterion was missed slightly, so this study does not meet the
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