Nondegraded Metabolites Arising From the Biodegradation of Commercial Linear Alkylbenzenesulfonate (Las) Surfactants in a Laboratory Trickling Filter

The degradation of a commercial linear alkylbenzenesulfonate (LAS) surfactant was examined kinetically in a trickling filter, which allowed simultaneous chemical determinations in the aqueous phase (e.g., DOC) and in the gas phase (CO2). About 60% of the carbon applied as LAS was released as CO2, whereas 15% remained as DOC in the eluate of acclimated trickling filters. The biomass was analysed after the experiment, and it was found to have sorbed about 23 mg LAS/g of dry biomass; this represented about 3% of the LAS applied to the filter. The LAS and the eluates from the trickling filter were further analysed by HPLC and UV and IR spectrometry. The residual carbon from acclimated filters contained no LAS-like material (HPLC), which was obviously subject to quantitative biotransformation. The residual material comprised >50 polar metabolites, some of whose UV spectra differed from that of LAS, and most or all of which were sulfonated. These nondegraded metabolites included carboxylated dialkyltetralinesulfonates and sulfophenylcarboxylates. These residual materials showed no detectable toxicity to algae or Daphnia, and did not significantly lower the surface tension of water.