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(16-30) Repetitivity of the USEPA Biodegradation Test in Sea Water: Application to Linear Alkylbenzene Sulphonates (LAS). Perales, Jose*,1, Sales, Diego1, Quiroga, Jose1, 1 University of Cádiz, Puerto Real, Cádiz ABSTRACT- The results of the application of the biodegradation test OPPTS 835.3160 Biodegradability in sea water proposed by USEPA to the most world consumed surfactant, linear alkylbenzene sulphonate (LAS) are shown. The analysis of the surfactant was carried out by means of high performance liquid chromatography (HPLC), and the biodegradation of the reference substrate (sodium benzoate) was followed with the measurement of the total dissolved organic carbon. The test media used was sea water from Cadiz Bay (Southwest of the Iberian Peninsula). The results shows that the tested surfactant has a high primary biodegradation rate in accordance with a logistic kinetic model, with average half lives (t1/2 ) of 6.15 ±0.45 days (n=5, 95%) and lag periods of 6.67 ±0.6 days. The variation coefficient obtained in the quintuplicate test, 7.1 and 7.2 % for half lives and lag times respectively, indicates that the test guideline proposed by USEPA, has a good repetitivity. Key words: Surfactants, Biodegradation, Seawater, kinetics |
