TECHNOLOGY FOCUS - INSTRUMENTATION AND TESTING - Preferred Components: The wear insert of the lower housing part forms a flat bottom wall, which in the cross-sectional area exhibits the U-base area. The wear insert of the lower housing cover exhibits a flat top wall, which forms the U-base region in the closed state in the inverted U-shaped cross-section. The flat top wall and the flat bottom wall are parallely spaced apart in the closed position. A guide prism is formed respectively on the flat bottom wall of the wear insert and on the flat top wall of the wear insert. A triangular shaped projection with concave curved lower support placed in a cross section is respectively present in the middle of the bottom wall and top wall. The projection extends over the total length of the respective wear inserts. The wear inserts consist of a soft support plate, which is covered with a hardened layer made of highly wear resistant composite armor material. An upper housing part with a feed hopper having an upper inlet opening and a lower outlet opening, is provided on the lower housing part in an area, that extends between the rear end plate and the housing cover, where the lower outlet of the feed hopper is placed above the extruder screw. The extruder screw with an insertion bevel sloping towards housing cover, is covered in an area between the feed hopper and the housing cover. The front face plate exhibits a size-adjustable outlet for the dosage amount of the extruded material, where a slider opening originating from one edge of the front face plate is provided in the front face plate, and a control of the size of the outlet opening can take place over the sliding motion of a slide shaped piece within the slider opening by means of an adjusting spindle connected with the slide shaped piece. Preferred Method: The material to be extruded is padded over an external feeding device into a feed hopper, which leads directly to the oppositely rotating screw extruders, and the flow rate of the material is controlled over a size-adjustable outlet on the front face plate of the twin screw extruder. The material to be extruded is a biomass, which is thermo-mechanically digested before being fed into an anaerobic fermentation plant for the production of biogas.