HYDROTHERMAL PRETREATMENT OF WHEAT-STRAW FOR THE PRODUCTION OF PULP AND PAPER

A chemical-free pretreatment process for the production of pulp is des cribed. By treating wheat straw biomass with hot compressed liquid wat er (e.g, 200 degrees C, 22 bar), almost all the hemicellulose and up t o 62% of the lignin are extracted from the lignocellulosic matrix. The remaining solid residue, the pulp, consists of cellulose and residual lignin. Several modes of operation (percolation, recirculation, and c ombined modes) in a 1 O-L pilot plant were used for this investigation . The combined recirculation-percolation process is advantageous becau se of its low water and energy consumption. Bleaching was carried out by alkaline extraction and by using hydrogen peroxide only. Indication s as to how bleaching can be improved are given. With unbleached pulp, paper tensile strengths of over 3 km were reached. Bleaching increase d this value by approximately 1 km.