Integrated pulping and biorefining of palm residues based on semichemical cooking and fiber fractionation

This work validates a new strategy for complete utilization of palm residues by separating fibers and parenchyma for the respective purposes of pulping and biorefining. The parenchyma cells were fractionated from royal palm sheath (RPS) after neutral sulfite semichemical (NSSC) cooking for producing fermentable sugars, leaving vascular bundles for manufacturing pulp and paper. Parenchyma cells could be readily and completely screened out prior to defibration. They were more digestible by cellulase than vascular bundles or the pulp derived from them. Cellulose enzymatic digestibility (CED) of parenchyma cells rapidly reached 82% in 12-h hydrolysis and finally up to 92%. The CEDs of parenchyma were maintained around 90% at a medium solid consistency, 12% (w/w). The average length, retention and drainability of RPS pulp were all improved without loss of physical strength after removing parenchyma. This work may help establish a new platform for maximizing the utilization efficiency of parenchyma-rich biomass.