NOVELTY - A biomass pre-treatment system comprises a chamber (202) defined by a chamber wall (204); and a cylindrical compartment (206) at a bottom section (208) of the chamber, where the cylindrical compartment comprises a stirring unit (210), and the stirring unit comprises a rotatable shaft (212) containing protruded space curved stirring elements (214) extending from the shaft, the elements are adapted to mix a biomass material received in the chamber and/or the compartment and to propel the received biomass material along a length of the chamber in a pre-determined direction.    USE - As biomass pre-treatment system (claimed) for pretreatment of biomass material.    ADVANTAGE - The biomass pre-treatment system achieves an effective and reliable pre-treatment of biomasses that are to be used in later stages of biogas extraction process, with low production cost; easily handle biomasses with high solids content and coarse structure; increases filling and flushing rate; consumes lower energy for stirring purposes; and has simple and robust sealing mechanism.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are included for the following:    (1) method for a pre-treatment system, involving actuating a stirring unit comprising a rotatable shaft having protruded space curved stirring elements extending from the shaft, where the stirring elements are adapted to rotate within a cylindrical compartment to mix a biomass material received in the chamber and to propel the received biomass along a length of the chamber and/or compartment in a pre-determined direction; receiving the biomass material in the chamber from a top opening; and controlling rotational direction of the stirring elements during operation of the system for propelling the received biomass material from one end to another end of the chamber and vice versa resulting in mixing of the receiving biomass material;    (2) a sealing unit either comprising a sliding mechanism having an elevated opening including, a cut out section for receiving a slidable lid, and a guiderail adapted to allow sliding movement of the lid along the guiderail from an open position through to a closed position and vice versa over the opening; or a sliding sealing mechanism, having a slidable lid supported on at least one slidable support unit; a slidable base in connection with the slidable support unit and adapted to slide over a support unit; and an actuating unit adapted for sliding the slidable base such that the slidable lid is moved from an open position to a closed position from beneath an opening; and    (3) a pressure cooker system, comprising a chamber defined by a chamber wall; a cylindrical compartment at a bottom section of the chamber, where the cylindrical compartment comprises a stirring unit, and the stirring unit comprises a rotatable shaft comprising protruded space curved stirring elements extending from the shaft, the elements are adapted to mix an input material received in the chamber and/or the compartment and to propel the received input material along a length of the chamber in a pre-determined direction.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of a biomass pre-treatment system.    Chamber (202)    Chamber wall (204)    Cylindrical compartment (206)    Bottom section (208)    Stirring unit (210)    Rotatable shaft (212)    Stirring elements (214)