BIODEGRADATION OF COPRODUCTS OF COMMERCIAL LINEAR ALKYLBENZENE SULFONATE

Dialkyltetralin sulfonate (DATS) and single methyl-branched isomers of linear alkylbenzene sulfonate (iso-LAS) are coproducts that together can range from 1 to 10% of commercial LAS depending on the manufacturi ng process. Biodegradation studies using radiolabeled CATS and iso-LAS showed mineralization by indigenous microbial populations in laborato ry simulations of aquatic and soil environments. Half-lives ranged fro m 2 to 20 days, which is rapid enough to suggest that accumulation wou ld not occur in these environments. Upon exposure to laboratory activa ted sludge treatment, most model iso-LAS compounds showed greater than 98% parent compound removal, extensive mineralization (>50%), and 79- 90% ultimate biodegradation (mineralization plus conversion to biomass ). Activated sludge treatment of CATS and one of the iso-LAS isomers ( methyl group attached to the benzylic carbon of the alkyl chain) resul ted in >98% removal, 3-12% ultimate biodegradation and apparent format ion of carboxylated biodegradation intermediates that accounted for 88 -97% of the original material. These CATS and iso-LAS biodegradation i ntermediates continued to mineralize in simulated receiving water and soil environments at rates similar to that of sulfophenyl carboxylate (SPC) intermediates of a standard LAS.