Existing high rate anaerobic technology such as UASB, EGSB and IC reactors based on granular sludge is not robust when applied to industrial effluents with high lipids content. After discovering the potential of converting fat and long chain fatty acids to methane, the development of a compact high rate anaerobic reactor technology for the treatment of effluents of high lipid content was pursued. In this paper the fundamentals of anaerobic LCFA degradation are revised.the basic principles of the IASB technology are described and results of a pilot plant treating a slaughterhouse effluent are presented. An organic loading rate of 16 kg COD/m3.day was applied being 63% of FOG. Effluent VSS were around 500 mg/L COD, removal efficiency was consistently above 80% and excessive LCFA accumulation was prevented (<1 g COD-LCFA/gTS). The start-up of the first full scale reference of the IASB reactor located in a fish canning factory (A Poveira, Portugal) is described
