LINEAR ALKYLBENZENE SULFONATE (LAS) - UNEP Chemicals

OECD SIDS LINEAR ALKYLBENZENE SULFONATE (LAS)
criteria for ready biodegradability. However, this is expected given
biodegradation kinetic curve dynamics related to increasing dissolved
organic carbon content because the CO2 generated during the biodegradation
process is not totally evolved and removed from the test medium.
Reference: Ruffo, C., Fedrigucci, M.G., Valtorta, L., and Cavalli, L. 1999.
Biodegradation of anionic and non-ionic surfactants by CO2 evolution.
Acclimated and non-acclimated inoculum. Riv. It. Sostanze Grasse LXXVI:
277-283.
Reliability: 1 Valid without restriction
(c)
Type: aerobic [X]; anaerobic [ ]
Inoculum: adapted [ ]; non-adapted [X]; domestic activated sludge from Enid, OK
Concentration: 10 mg/L
Medium: Semi-continuous activated sludge (SCAS)
Degradation: >98% in 20 days (primary biodegradation)
62% in 20 days (inherent biodegradation)
Results: readily biodeg. [ ]; inherently biodeg. [X]; under test condition no
biodegradation observed [ ], other [ ]
Method:
14 14
C ring-labeled LAS and C alkyl-labeled C12 LAS were introduced to a
simulated secondary waste treatment system (SCAS) following the ASTM
and SDA standard methods.
GLP: Yes [ ] No [X] ? [ ]
Test Substance: 1) LAS with the following homologue composition: C11 42%, C12 38%, C13
20%; average alkyl chain length C11.8
2) C12 LAS
Remarks: In a secondary waste treatment environment, the alkyl and ring portions of
LAS both biodegrade extensively, with the fate of the LAS alkyl and ring
carbon nearly identical. Within the 20 day test period, 62% of the alkyl and
ring carbon converted to carbon dioxide.
Reference: Nielsen, A.M. and Huddleston, R.L. 1981. Ultimate biodegradation of linear
alkylbenzene sulfonate alkyl and ring carbon. Developments in Industrial
Microbiology. 22:415-424.
Reliability: 2 Valid with restrictions
(d)
Type: aerobic [X]; anaerobic [ ]
Inoculum: Bacterial biomass obtained from the settled supernatant slurry solution of a
fertile soil
Concentration: 10 mg/L
Medium: water [X]; water-sediment [ ]; soil [ ]; sewage treatment [ ]
Degradation: See methods
Results: See remarks
Method: OECD 301E Ready Biodegradability test, with the following modifications:
LAS was the sole source of carbon introduced (i.e., no activated sludge
inoculum), along with an enriched level of bacterial biomass. Preliminary
tests showed that more than 90% of the LAS disappeared within 4 days, so
LAS was restored by adding about 10 mg/L of fresh substance every 4 days
for 80 days. The test was stopped 4 days after the last LAS addition (i.e., at
84 days). Specific HPLC analysis was used to measure LAS and SPCs.
GLP: Yes [ ] No [ ] ? [X]
Test Substance: Commercial HF-type LAS with a C10-13 alkyl chain and a linearity of about
93% (DATS