Biomass washed out from an expanded granular sludge bed (EGSB) reactor treating oleate (82%, w/w) was investigated. This biomass had a 50% higher activity compared to granules present in the EGSB reactor. Recirculation of washed out biomass into reactor remarkably improved the treatment performance. The highest methane conversion rate from oleate, 300 mg CH4-COD/g VSS.d, was achieved at a concentration of 4 g oleate-COD/l and a volumetric loading rate of 8 g COD/l.d.