Disclosed is a solid/liquid separation apparatus including an extruder press combined with a solid/fluid separation module for separating fluid from a mass of solids compressed by the extruder at elevated pressures. The extruder includes two or more extruder screws with flighting intercalated at least along a part of the extruder barrel. The separation module forms a continuation of the barrel, receives the pressurized mass and at least a portion of the twin screws, and includes a filter pack consisting of a filter plate and a backer plate. The filter plate has a throughgoing filter slot extending away from a core opening and into the filter plate for directing fluid away from the core opening. The backer plate has a core opening shaped and sized equal to the barrel and defines a passage for guiding fluid collected in the filter slot to an exterior of the filter pack.