FATE OF LINEAR ALKYLBENZENE SULFONATE IN THE ENVIRONMENT

An extensive monitoring study was conducted to determine the fate of l inear alkylbenzene sulfonate (LAS) during wastewater treatment and in the environment. Results showed that LAS was highly removed during act ivated sludge (99.3 +/- 0.6%), lagoon (98.5 +/- 1.8%), oxidation ditch (98.0 +/- 4.2%), and rotating biological contact (96.2 +/- 6.1%) trea tment, with poorer removals observed at trickling filter (77.4 +/- 15. 5%) facilities. Concentrations of LAS in anaerobically digested sludge (10,462 +/- 5170 mug/g) were one to two orders of magnitude greater t han those observed for aerobically digested sludge (152 +/- 119 mug/g) , illustrating that LAS is rapidly degraded during aerobic sludge trea tment. Receiving water concentrations of LAS in rivers of low effluent dilution were generally <50 mug/L. Elevated river sediment concentrat ions of LAS were observed only below the outfall of trickling filter t reatment plants (59.7-182.1 mug/g). Alkyl chain lengths of LAS average d 12.0 carbon units in most environmental compartments, with the excep tion of sludge solids and river sediments, in which an enrichment of l onger chain lengths was observed. Measured concentrations of LAS in ri ver waters under critical low flow conditions were in agreement with P G-GRiDS model predictions [5], thus supporting the validity of the mod eling approach.