An animal feed producing system comprises a compression screw assembly. The compression screw assembly includes at least a first screw, a second screw and a plurality of barrels. The first and second screws include a plurality of flights and roots. The plurality of screws is configured such that they include a plurality of sections. Each section comprises a set of plurality of flights and a plurality of roots configured to perform a specific compression function, such as perpendicular compression and lateral compression.

An animal feed producing system comprises a compression screw assembly. The compression screw assembly includes at least a first screw, a second screw and a plurality of barrels. The first and second screws include a plurality of flights and roots. The plurality of screws is configured such that they include a plurality of sections. Each section comprises a set of plurality of flights and a plurality of roots configured to perform a specific compression function, such as perpendicular compression and lateral compression.

An infectious waste treatment system and method for decontaminating infectious waste employ a thermal friction extruder (20) in which first and second interleaved counter-rotatable augers (40, 42) include reverse pitch flight sections (62, 72) that urge waste material in a direction opposite to that of the flow stream and into engagement with the back sides of friction plates (50, 52). This increases the amount of heat generated by the extruder. The reverse pitch flight sections can be selectively replaced with forward pitch flight sections to control the amount of heat imparted to the waste material by the friction plates.