Influence of co-substrates in the anaerobic degradation of an anionic surfactant

The removal of linear alkylbenzene sulfonate (LAS) was evaluated in a UASB reactor using short-chain alcohols (ethanol and methanol) and complex co-substrate (yeast extract). Using only methanol and ethanol as co-substrates resulted in removal of LAS between 30 and 41%. At the end, addition of a complex substrate (yeast extract) increased the removal of LAS to 50%. During the assay, water supply aeration increased the volatile fatty acid of the effluent (70 mg HAc.L-1) and decreased the removal of LAS (from 40 to 30%). According to the fluorescence in situ hybridization (FISH) results, the amount of Archaea decreased due to water supply aeration (from 64 to 48%). Furthermore, addition of complex co-substrate increased the total anaerobic bacteria and methanogenic archaea content (three and four log units, respectively), which were estimated using the most probable number technique.