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behaviour of las


Behaviour of LAS in sewage treatment plants: fate of LAS in WWTP

fate of las


There is an extensive database on the behavior of LAS in all varieties of Waste Water Treatment Plants (WWTP) including information from activated sludge-based plants, trickling filter works as well as other simple treatment systems such as lagoons and others.

The following split for LAS removal can be assumed on the basis of mass balance studies (Berna et al., 1989; Painter et al., 1989; Cavalli et al., 1993; DiCorcia et al., 1994)80-90% degraded, 10-20% adsorbed into sludge and about 1% released to surface waters.

The risk assessment for LAS in WWTP has recently been conducted under HERA project. The risk characterization expressed as the ratio PEC/PNEC is well below one using exposure data derived from the worst case of a realistic exposure scenario. It is therefore concluded that LAS does not affect the STP functioning

Risk characterization data:





STP, mg/l




Key references

Berna JL, J Ferrer, A Moreno, D Prats, F Ruiz Bevia, The fate of LAS in the environment, Tenside Surf. Det. 26: 101-107, 1989

Cavalli L, A Gellera, A Landone, LAS removal and biodegradation in wastewater treatment plant, Environ. Toxic. Chem. 12: 1777-1788, 1993

DiCorcia A, R Samperi, A Belloni, A Marcomini, M Zanette, K Lemr, L Cavalli, Riv. It. Sostanze Grasse LXXI: 467-475, 1994

Painter HA, T Zabel, The behaviour of LAS in sewage treatment, Tenside Surf. Det. 26: 108-115, 1989

Waters J, TCJ Feijtel, AISE/CESIO environmental surfactant monitoring programme: outcome of five national pilot studies on LAS, Chemosphere 30: 1939-1956, 1995

Matthijs E, MS Holt, A Kiewiet, GB Rijs, Environmental Monitoring for LAS, AE, AES, AS, and soap, Environ. Toxicol. Chem. 18: 2634-2644, 1999

Verge C, A Moreno, J Bravo, J Ferrer, C Bengoechea, Toxicity of LAS vs. activated sludge of waste water treatment plant and microalgae (Scenedesmus subspicatus), SETAC World Congress, Lisbon (P), 1993

Verge C, A Moreno, Toxicity of anionic surfactants to the bacterial population of a waste water treatment plant, Tenside Surf. Det. 33: 323-327, 1996

Moreno, A Ferrer J. Ruiz Beviá, F. Prats, D. Vazquez B, Monitoring of linear alkylbenzene sulphonate (LAS.) removal in a lagoon treatment system. Water Research - (Vol. 28 Nº 10,).

Berna, J.L. Moreno, A. Ferrer, J, An assessment of the ultimate biode-gradation of LAS, Tenside 30(1993)3