Two expanded granular sludge bed reactors were operated. R-AB (adapted biomass) was operated in two stages: Stage I, with standard LAS (13.2 mg L (1)); and Stage II, in which the standard LAS was replaced by diluted laundry wastewater according to the LAS concentration (11.2 mg L (1)). R-NAB (not adapted bio-mass) had a single stage, using direct wastewater (11.5 mg L (1)). Thus, the strategy of biomass adaptation did not lead to an increase of surfactant removal in wastewater (R-AB-Stage II: 77%; R-NAB-Stage I: 78%). By means of denaturing gradient gel electrophoresis, an 80% similarity was verified in the phases with laundry wastewater (sludge bed) despite the different reactor starting strategies. By pyrosequencing, many reads were related to genera of degraders of aromatic compounds and sulfate reducers (Syntrophorhabdus and Desulfobulbus). The insignificant difference in LAS removal between the two strategies was most likely due to the great microbial richness of the inoculum. Crown Copyright (C) 2013 Published by Elsevier Ltd. All rights reserved.