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TERRESTRIAL RISK ASSESSMENT
Sludge Amended Soils
The use of sludge from Wastewater Treatment Plants in agricultural soil amendment is a frequent practice
in most European countries, although with a variable degree of application from one country to another.
Surfactants are present in sludge of wastewater treatment works due to their physical - chemical
properties and their ability to adsorb / precipitate. The occurrence and effects of surfactants on
sludge amended soils has been widely investigated with a rich data base on LAS augmented by limited
information on other surfactants. It is estimated that between 10 and 20% of the surfactant load to
a WWTP escape the biological treatment due to precipitation / adsorption into the primary sludge
ending up in the final sludge. LAS in sludge degrades rapidly and extensively in sludge amended soils
as well as during the composting of sludge.
Summary of Data of LAS Occurrence and Behavior in Sludge Amended Soils.
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Typical LAS conc. in anaerobic sludge in Europe |
0.5 - 10 g/Kg d.s |
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LAS removal in sludge amended soils |
> 98% |
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Half life of LAS in sludge amended soils |
10 - 30 days |
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LAS removal during composting |
> 99% |
No accumulation detected in soils after several years of continuous application of sludge.
No LAS has been found in water percolating through soil. The migration (leaching) potential is limited to the first few cm of soil thickness.
No intact LAS is adsorbed by plants growing in sludge amended soils.
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
DiCorcia A, R Samperi, A Belloni, A Marcomini, M Zanette, K Lemr, L Cavalli, Riv. It. Sostanze Grasse LXXI: 467-475, 1994
Feijtel-a TCJ, E Matthijs, A Rottiers, GBJ Rijs, A Kiewiet, A de Nijs, AISE/CESIO environmental surfactant monitoring programme. Part 1: LAS monitoring study in "de Meer" STP and receiving river "Leidsche Rijn", Chemosphere 30: 1053-1066, 1995
Holt MS, Matthijs E, Waters J, The concentrations and fate of LAS in sludge amended soils, Wat. Res 23: 749-759, 1989
Prats-b D, M Rodriguez, MA Muela, JM Llamas, J Ferrer, A Moreno, JL Berna, AM Nielsen, C Naylor, Elimination of LAS in sewage biosolids by composting, 5th World CESIO Congress V.2: 1475-1488, 2000, Firenze, Italy
Sānchez Leal J, MT Garciā, R Tmās, J Ferrer, C Bengoechea, Tenside Surf. Det. 31: 253-256, 1994
Solbč J, JL Berna, L Cavalli, TCJ Feijtel, KK Fox, J Heinze, SJ Marshall, W de Wolf, Terrestrial risk assessment of LAS in sludge-amended soils, 5th World CESIO Congress V.2: 1433-1438, May-June 2000, Firenze, Italy
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